U.S. patent application number 11/750617 was filed with the patent office on 2007-09-27 for optical transmission channel board, board with built-in optical transmission channel, and data processing apparatus.
This patent application is currently assigned to Matsushita Electric Industrial Co., Ltd.. Invention is credited to Toshiyuki Asahi, Takashi Ichiryu, Seiji Karashima, Seiichi Nakatani, Yasuhiro Sugaya.
Application Number | 20070224735 11/750617 |
Document ID | / |
Family ID | 34890871 |
Filed Date | 2007-09-27 |
United States Patent
Application |
20070224735 |
Kind Code |
A1 |
Karashima; Seiji ; et
al. |
September 27, 2007 |
OPTICAL TRANSMISSION CHANNEL BOARD, BOARD WITH BUILT-IN OPTICAL
TRANSMISSION CHANNEL, AND DATA PROCESSING APPARATUS
Abstract
A fabrication method for an optical transmission channel board
includes a first step of forming on a substrate a layer containing
an electrically conductive material, and a second step of
patterning said layer containing an electrically conductive
material formed on said substrate, and thereby forming circuit
patterns at least a part of which is used as an electric circuit
and at least a part of which positionally regulates an optical
transmission channel.
Inventors: |
Karashima; Seiji; (Osaka,
JP) ; Nakatani; Seiichi; (Osaka, JP) ; Sugaya;
Yasuhiro; (Osaka, JP) ; Asahi; Toshiyuki;
(Osaka, JP) ; Ichiryu; Takashi; (Osaka,
JP) |
Correspondence
Address: |
RATNERPRESTIA
P.O. BOX 980
VALLEY FORGE
PA
19482
US
|
Assignee: |
Matsushita Electric Industrial Co.,
Ltd.
Osaka
JP
|
Family ID: |
34890871 |
Appl. No.: |
11/750617 |
Filed: |
May 18, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11041101 |
Jan 21, 2005 |
7242823 |
|
|
11750617 |
May 18, 2007 |
|
|
|
Current U.S.
Class: |
438/128 ;
257/E21.602 |
Current CPC
Class: |
G02B 6/3676 20130101;
G02B 6/4249 20130101; G02B 6/3668 20130101; G02B 6/3636 20130101;
G02B 6/3692 20130101; H05K 1/0274 20130101; G02B 6/3608 20130101;
G02B 6/4214 20130101; H05K 2203/167 20130101 |
Class at
Publication: |
438/128 ;
257/E21.602 |
International
Class: |
H01L 21/82 20060101
H01L021/82 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 22, 2004 |
JP |
2004-014863 |
Jan 22, 2004 |
JP |
2004-014966 |
Jan 22, 2004 |
JP |
2004-014968 |
Claims
1. A fabrication method for an optical transmission channel board
comprising: a first step of forming on a substrate a layer
containing an electrically conductive material; and a second step
of patterning said layer containing an electrically conductive
material formed on said substrate, and thereby forming circuit
patterns at least a part of which is used as an electric circuit
and at least a part of which positionally regulates an optical
transmission channel.
2. The fabrication method for an optical transmission channel board
according to claim 1, wherein said circuit pattern which
positionally regulates said optical transmission channel forms
guide walls for performing the regulation.
3. The fabrication method for an optical transmission channel board
according to claim 1, wherein said second step of forming said
circuit patterns is a step of forming circuit patterns a part of
which is used as an optical element marker for positioning an
optical element mounted on said optical transmission channel
board.
4. The fabrication method for an optical transmission channel board
according to claim 3, wherein said second step of forming said
circuit patterns is a step of forming circuit patterns used as two
or all selected from said electric circuit, said guide walls, and
said optical element marker.
5. The fabrication method for an optical transmission channel board
according to claim 1, further comprising an A step of stacking
after said second step a guide layer onto said circuit pattern
which positionally regulates said optical transmission channel.
6. The fabrication method for an optical transmission channel board
according to claim 1, further comprising a B step of machining
after said second step an upper part of said circuit pattern used
as said electric circuit.
7. The fabrication method for an optical transmission channel board
according to claim 6, further comprising a C step of stacking after
said first step a layer composed of a material different from that
of said layer containing said electrically conductive material,
onto said layer containing said electrically conductive material,
wherein said B step is a step of machining said layer composed of
the different material.
8. The fabrication method for an optical transmission channel board
according to claim 2, further comprising: a third step of arranging
an optical transmission channel on the basis of said circuit
pattern used as guide walls; a fourth step of forming a retention
board for retaining an optical transmission channel on said
substrate, in such a manner that said circuit pattern and said
optical transmission channel are covered; and a fifth step of
removing said substrate from said retention board.
9. The fabrication method for an optical transmission channel board
according to claim 1, wherein said second step is a step of etching
said layer containing said electrically conductive material by
using a mask corresponding to said circuit patterns, and thereby
forming said circuit patterns.
10. The fabrication method for an optical transmission channel
board according to claim 2, wherein said optical transmission
channel is an optical fiber, and wherein a length of said guide
walls measured in a perpendicular direction relative to a surface
of said retention board is greater than a radius of said optical
fiber.
11. The fabrication method for an optical transmission channel
board according to claim 10, wherein said guide walls are formed
with predetermined spacing such that said optical transmission
channel substantially contacts with said guide walls.
12. The fabrication method for an optical transmission channel
board according to claim 4, further comprising a sixth step of
mounting an optical element on said circuit pattern such that said
optical element is arranged above said optical transmission
channel, wherein said optical element is a laser element or a photo
receiving element.
Description
[0001] This Application is a Divisional of U.S. patent application
Ser. No. 11/041,101 filed on Jan. 21, 2005, which is hereby
incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a fabrication method for an
optical transmission channel board, an optical transmission channel
board, aboard with built-in optical transmission channel, a
fabrication method for a board with built-in optical transmission
channel, and a data processing apparatus.
[0004] 2. Related Art of the Invention
[0005] With recent progress in optical communications and optical
information processing, optical circuit mounting technology
permitting high-density and economical integration of optical
components is increasingly important, and so is the role that
optical modules play. An example of a prior art optical module is
shown in FIG. 50 (see JP-A-H8-78657).
[0006] As shown in FIG. 50, a prior art optical module 1000
comprises a Si substrate (Si terrace) 1101, optical fibers 1102,
and a semiconductor laser (optical element) 1105. Guide grooves (V
grooves) 1104 a formed in the Si substrate 1101. Each optical fiber
1102 is fixed along each guide groove 1104. Electric wirings 1106
and positioning reference planes (positioning markers) 1103a,
1103b, and 1103c are formed in the Si substrate 1101. Using these
positioning reference planes 1103a, 1103b, and 1103c, the
semiconductor laser 1105 is mounted on the Si substrate 1101, and
connected to the electric wirings 1106. That is, in the optical
module 1000, the optical fibers 1102 and the semiconductor laser
(LD) 1105 are integrated on the Si substrate 1101. This module is
driven through the electric wirings 1106. In the configuration
shown in FIG. 50, the guide grooves 1104 can be fabricated with
sufficient accuracy on the basis of the good workability of the Si
substrate 1101. This permits easy integration of the optical fibers
1102 with the optical element such as the semiconductor laser (LD)
1105 and a photo detector (PD).
[0007] FIG. 51 shows another optical module 2000 in which an
optical waveguide 1126 in place of an optical fiber is formed on a
Si substrate 1101 (see JP-A-H8-78657).
[0008] In the optical module 2000 shown in FIG. 51, the optical
waveguide 1126 formed on the Si substrate 1101 is optically
connected to an opto-semiconductor element 1127 mounted via solder
bumps 1128 in a recess formed on the Si substrate 1101.
[0009] The mounting hierarchy in a communication system apparatus
3000 for performing optical communications is described below with
reference to FIG. 52. The communication system apparatus 3000 shown
in FIG. 52 is constructed according to a method called bookshelf
mounting. This method has an advantage in economical efficiency and
packaging density, and hence is used generally.
[0010] Further description is given below.
[0011] A component of the communication system apparatus 3000 is a
semiconductor element (LSI chip) 130. A plurality of semiconductor
elements 130 are used and constitute an MCM (multi-chip module)
1131. The MCM 1131 is mounted on a board (printed circuit board)
1133, so that a board assembly is obtained. A plurality of board
assemblies are accommodated in a sub-rack 1135. A plurality of
sub-racks 1135 are accommodated in a cabinet 1137, so that the
communication system apparatus 3000 is constructed.
[0012] The mounting hierarchy of bookshelf mounting is classified
into six levels. That is, level 0 indicates a distance within a
chip (.about.1 mm). Level 1 indicates a distance between chips
(.about.1 cm). Level 2 indicates a distance within a board
(.about.10 cm). Level 3 indicates a distance within a sub-rack
(.about.1 m). Level 4 indicates a distance between sub-racks
(.about.10 m). Level 5 indicates a distance between apparatuses or
systems (.about.100 m) (each quantity between parentheses indicates
a transmission distance). Among these levels, in the range of
transmission distance exceeding 1 m (level 3, level 4, or higher),
optical fibers have an advantage as a transmission medium. Thus,
the combination of an optical module (such as one shown in FIG. 50)
and an optical fiber is used advantageously. In contrast,
transmission within a board (level 2) is performed generally using
a copper circuit pattern on the printed circuit board. That is,
such transmission is performed using electricity, not using
light.
[0013] On the other hand, JP-A-2000-340907 discloses a wiring board
(printed circuit board) that has built-in optical fibers. The
wiring board disclosed in JP-A-2000-340907 is shown in FIGS. 53,
54(a), and 54(b).
[0014] The wiring board 4000 shown in FIG. 53 comprises an
insulating board 1201. The insulating board 1201 is composed of a
plurality of insulating layers 1202. Wiring circuit layers 1203 are
formed on the insulating layers 1202. Wiring circuit layers 1203
located on different layers are connected through via hole
conductors 1204. Optical wave guide bodies 1205 having a fiber
shape (such as optical fibers) are embedded in an insulating layer
1202a selected from a plurality of the insulating layers.
[0015] As shown in the plan view of FIG. 54(a), the optical
waveguide bodies 1205 having a fiber shape are embedded inside an
insulating board 1201, so that an optical waveguide circuit is
constructed in which optical signals can be transmitted through
these optical waveguide bodies 1205. FIG. 54(b) is a sectional view
taken along line X-X' in FIG. 54(a). The inside of the insulating
board 1201 of FIG. 54(a) is illustrated as a schematic diagram for
general description purpose, and is not necessarily in agreement
with the sectional view of FIG. 53.
[0016] As shown in FIGS. 54(a) and 54(b), an optical connector 1206
is integrally attached to an end of the optical waveguide circuit
in one side of the insulating board 1201. Optical-to-electric
signal conversion elements 1207 capable of converting an optical
signal into an electric signal is attached in the inside or side
portions of the insulating board 1201. Electric signals converted
from the optical signals by the optical-to-electric signal
conversion elements 1207 are electrically transferred through the
wiring circuit layers 1208 (corresponding to the wiring circuits
1203 shown in FIG. 53) and the via hole conductors 1204 arranged
inside the insulating board 1201, to an electronic element or the
electric connector 1209 mounted on the insulating board 1201.
[0017] JP-A-2000-66034 discloses an optical wiring board permitting
the wiring of a large number of optical fibers.
[0018] The optical wiring board disclosed in JP-A-2000-66034 is
shown in FIG. 55. In the optical wiring board 5000 of FIG. 55, one
or two or more optical fibers 1311 are mounted on the board using
the technique of a picture drawn with a single stroke of a pencil.
In the optical wiring board 5000, the optical fibers 1311 are
stacked in a certain part.
[0019] The optical wiring board 5000 shown in the figure has a
four-layer structure. The optical fibers 1311 are arranged on
boards 1312 and 1312'. End portions 1313 of the optical fibers 1311
are arranged in line on the same plane, while end portions 1314 are
multi-layered.
[0020] When an optical module such as the optical module 1000 shown
in FIG. 50 is to be fabricated, in a prior art fabrication method,
the electric wirings 1106 are fabricated on the board 1101 by
etching or the like, and then the guide grooves 1104 are fabricated
by machining or the like. As such, the fabrication processes for
the electric wirings 1106 and for the guide grooves 1104 are
completely separated. This has caused complicated fabrication
processes, and hence caused an increase in time and cost.
[0021] Further, at a glance of the optical module 1000 of FIG. 50,
the module might seem to be fabricated easily. Nevertheless, in
practice, centering is necessary between each of the optical fibers
1102 and the optical element 1105. This centering process is
notably complicated. The "centering" described here indicates the
process of aligning the optical axes of each optical transmission
channel (optical fiber) and the optical element (such as
semiconductor laser).
[0022] For example, when the optical fibers 1102 are single-mode
fibers, only a discrepancy in the submicron order is allowable
between each optical fiber 1102 and the optical element 1105.
Nevertheless, considering the deviation (tolerance) occurring in
the fabrication of the guide grooves (V grooves) 104 in the Si
substrate 101 and the deviation (tolerance) occurring in the
fabrication of the optical element positioning reference planes
1103a, 1103b, and 1103c formed together with the electric wirings
1106, it is concluded that the mounting of the optical element 1105
merely based on the alignment with the optical element positioning
reference planes 1103a, 1103b, and 1103c is insufficient because
the discrepancy can exceed the tolerance between each optical fiber
1102 and the optical element 1105. Thus, the centering is
unavoidable.
[0023] Also in the configuration of FIG. 51, electric wirings (not
shown) located under the solder bumps 1128 are fabricated in a
separate process from that for the optical waveguide 1126. Thus, a
similar problem arises concerning the discrepancy between the
optical fiber 1102 and the optical element 1105.
[0024] Even if the problem of discrepancy between the optical fiber
1102 and the optical element 1105 could not arise in the optical
module 2000 shown in FIG. 51, a higher cost is caused in the
fabrication of the optical waveguide 1126 on the Si substrate 1101
in comparison with the case that an optical fiber 1102 is used.
Thus, another problem arises concerning economical efficiency.
[0025] From the perspective of economical efficiency, the use of
copper circuit patterns of a printed circuit board is advantageous,
for example, in the within-the-board transmission (level 2) in the
communication system apparatus 3000 shown in FIG. 52. Nevertheless,
this causes a problem that the upper limit is reduced in the
transmission speed. This is because despite that GHz-level
transmission is achieved in optical interconnection, merely
MHz-level transmission is achieved in electric interconnection.
[0026] Further, in the wiring board 4000 shown in FIGS. 53 and 54,
centering is necessary between each optical waveguide body 1205
embedded in the insulating board 1201 and each optical-to-electric
signal conversion element 1207. This centering process is
complicated, and hence increases the cost.
[0027] Furthermore, in the within-the-board transmission in the
communication system apparatus 3000 shown in FIG. 52, if the
electric interconnection were replaced with optical interconnection
in order that the problem of transmission speed could be resolved,
an unacceptably large number of optical fibers or optical
waveguides would need to be arranged on the board. Thus, another
problem would arise concerning the actual device structure. More
specifically, the board surface would be filled with optical fibers
or the like. This causes a difficulty in the handling, as well as
an increase in the board size and in the rate of failure such as
disconnection in the optical fibers or the like.
[0028] Thus, in order that a large number of optical fibers or
optical transmission channels should be arranged within a limited
region, the optical fibers or the optical transmission channels
could be constructed in multi-stage. Nevertheless, the method for
this multi-stage construction is a difficult problem to be devised
in the case of the actual configuration of the optical modules 1000
and 2000 shown in FIGS. 50 and 51. A new way of thinking is
necessary for solving this problem. That is, in the optical module
1000 shown in FIG. 50, the guide grooves (V grooves) 1104 are
formed in the Si substrate 1101 so that the optical fibers 1102 are
fixed in the guide grooves 1104. Thus, the configuration of
single-stage arrangement is unavoidable in principle. On the other
hand, in the optical module 2000 shown in FIG. 51, the optical
waveguide 1126 is formed on the Si substrate 1101. Thus, similarly,
the configuration of single-stage arrangement is unavoidable in
principle.
[0029] Further, the wiring board 4000 shown in FIGS. 53 and 54 is
disclosed in the case that a single insulating layer 1202a is used
and that the optical waveguide bodies 1205 are embedded therein. In
contrast, if a plurality of such layers were to be provided in the
configuration, a new problem would arise in the method of attaching
the optical-to-electric signal conversion elements 1207. In
addition, JP-A-2000-340907 does not disclose the case that the
optical waveguide bodies 1205 presently embedded in the insulating
board 1201 are arranged in a different hierarchy from that of the
optical-to-electric signal conversion elements 1207. Accordingly,
no disclosure or indication is provided concerning the method for
precisely adjusting their positions for their optical connection.
Further, although the optical wiring board 5000 shown in FIG. 55 is
a board with built-in optical fibers, no disclosure or indication
is provided concerning the configuration that optical-to-electric
signal conversion elements 1207 are attached directly to all the
optical fibers of the optical wiring board 5000. Thus, it should be
notably difficult to precisely adjust the positions for optical
connection.
[0030] With considering the above-mentioned problems in the prior
art, a purpose of the present invention is to provide: a
fabrication method for an optical transmission channel board which
can be fabricated in a simpler fabrication process; such an optical
transmission channel board; and a data processing apparatus
employing this optical transmission channel board. Another purpose
of the present invention is to provide a fabrication method for an
optical transmission channel board which needs no centering process
or merely a simpler centering process; such an optical transmission
channel board; and a data processing apparatus employing this
optical transmission channel board.
[0031] Yet another purpose of the present invention is to provide a
fabrication method for an optical transmission channel board which
can be fabricated at a lower cost.
[0032] Another purpose of the present invention is to provide a
board with built-in optical transmission channel on which an
optical element (such as a semiconductor laser) can be mounted, and
on which a large number of optical transmission channels (such as
optical fibers) can be mounted efficiently. At the same time, a
purpose of the present invention is to provide a data processing
apparatus employing such a board with built-in optical transmission
channel and a fabrication method for such a board with built-in
optical transmission channel.
SUMMARY OF THE INVENTION
[0033] The 1.sup.st aspect of the present invention is a
fabrication method for an optical transmission channel board
comprising:
[0034] a first step of forming on a substrate a layer containing an
electrically conductive material; and
[0035] a second step of patterning said layer containing an
electrically conductive material formed on said substrate, and
thereby forming circuit patterns at least a part of which is used
as an electric circuit and at least a part of which positionally
regulates an optical transmission channel.
[0036] The 2.sup.nd aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 1.sup.st aspect of the present invention, wherein
said circuit pattern which positionally regulates said optical
transmission channel forms guide walls for performing the
regulation.
[0037] The 3.sup.rd aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 1.sup.st aspect of the present invention, wherein
said second step of forming said circuit patterns is a step of
forming circuit patterns a part of which is used as an optical
element marker for positioning an optical element mounted on said
optical transmission channel board.
[0038] The 4.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 3.sup.rd aspect of the present invention, wherein
said second step of forming said circuit patterns is a step of
forming circuit patterns used as two or all selected from said
electric circuit, said guide walls, and said optical element
marker.
[0039] The 5.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 1.sup.st aspect of the present invention, further
comprising an A step of stacking after said second step a guide
layer onto said circuit pattern which positionally regulates said
optical transmission channel.
[0040] The 6.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 1.sup.st aspect of the present invention, further
comprising a B step of machining after said second step an upper
part of said circuit pattern used as said electric circuit.
[0041] The 7.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 6.sup.th aspect of the present invention, further
comprising a C step of stacking after said first step a layer
composed of a material different from that of said layer containing
said electrically conductive material, onto said layer containing
said electrically conductive material, wherein
[0042] said B step is a step of machining said layer composed of
the different material.
[0043] The 8.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 2.sup.nd aspect of the present invention, further
comprising:
[0044] a third step of arranging an optical transmission channel on
the basis of said circuit pattern used as guide walls;
[0045] a fourth step of forming a retention board for retaining an
optical transmission channel on said substrate, in such a manner
that said circuit pattern and said optical transmission channel are
covered; and
[0046] a fifth step of removing said substrate from said retention
board.
[0047] The 9.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 1.sup.st aspect of the present invention, wherein
said second step is a step of etching said layer containing said
electrically conductive material by using a mask corresponding to
said circuit patterns, and thereby forming said circuit
patterns.
[0048] The 10.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 2.sup.nd aspect of the present invention, wherein
said optical transmission channel is an optical fiber, and
wherein
[0049] a length of said guide walls measured in a perpendicular
direction relative to a surface of said retention board is greater
than a radius of said optical fiber.
[0050] The 11.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 10.sup.th aspect of the present invention, wherein
said guide walls are formed with predetermined spacing such that
said optical transmission channel substantially contacts with said
guide walls.
[0051] The 12.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 4.sup.th aspect of the present invention, further
comprising a sixth step of mounting an optical element on said
circuit pattern such that said optical element is arranged above
said optical transmission channel, wherein
[0052] said optical element is a laser element or a photo receiving
element.
[0053] The 13.sup.th aspect of the present invention is an optical
transmission channel board comprising:
[0054] an optical transmission channel;
[0055] a retention board for retaining said optical transmission
channel; and
[0056] circuit patterns which are formed on said retention board
and a part of which is used as an electric circuit; wherein
[0057] said optical transmission channel is positionally regulated
by said part of circuit patterns.
[0058] The 14.sup.th aspect of the present invention is the optical
transmission channel board according to the 13.sup.th aspect of the
present invention, wherein said optical transmission channel is
arranged between guide walls formed under said circuit pattern.
[0059] The 15.sup.th aspect of the present invention is the optical
transmission channel board according to the 13.sup.th aspect of the
present invention, wherein said circuit patterns are formed in a
predetermined thickness along a thickness direction of said
retention board, and wherein
[0060] said optical transmission channel is arranged in middle of
said circuit pattern serving as guide walls.
[0061] The 16.sup.th aspect of the present invention is the optical
transmission channel board according to the 14.sup.th or the
15.sup.th aspect of the present invention, wherein said optical
transmission channel is arranged such as to contact substantially
with said guide walls.
[0062] The 17.sup.th aspect of the present invention is the optical
transmission channel board according to the 13.sup.th aspect of the
present invention, wherein said optical transmission channel is
embedded in said retention board, while an uppermost part of said
optical transmission channel is substantially arranged in plane
with an upper surface of said retention board.
[0063] The 18.sup.th aspect of the present invention is the optical
transmission channel board according to the 13.sup.th aspect of the
present invention, wherein said circuit pattern has a portion lower
than an upper surface of said retention board.
[0064] The 19.sup.th aspect of the present invention is the optical
transmission channel board according to the 18.sup.th aspect of the
present invention, wherein said portion lower than an upper surface
of said retention board is a land part.
[0065] The 20.sup.th aspect of the present invention is the optical
transmission channel board according to the 13.sup.th aspect of the
present invention, wherein said optical transmission channel is an
optical fiber.
[0066] The 21.sup.st aspect of the present invention is a data
processing apparatus comprising:
[0067] an optical transmission channel board according to the 13th
aspect of the present invention;
[0068] at least one semiconductor element selected from a memory
LSI and a logic LSI mounted on said optical transmission channel
board; and
[0069] a laser element and/or a photo receiving element mounted on
said part of circuit patterns; wherein
[0070] said optical transmission channel board has a plurality of
said optical transmission channels.
[0071] The 22.sup.nd aspect of the present invention is a
fabrication method for an optical transmission channel board
comprising:
[0072] a first step of embedding, on a retention board, circuit
patterns formed by patterning a layer containing an electrically
conductive material, wherein at least a part of said circuit
patterns is used as an electric circuit, while at least a part of
said circuit patterns is used as an optical transmission channel
marker; and
[0073] a second step of removing said circuit pattern for an
optical transmission channel marker from said retention board, and
thereby fabricating a groove for said optical transmission channels
on said retention board.
[0074] The 23.sup.rd aspect of the present invention is a
fabrication method for an optical transmission channel board
comprising:
[0075] a first step of embedding, on a retention board, circuit
patterns formed by patterning a layer containing an electrically
conductive material, wherein at least a part of said circuit
patterns is used as an electric circuit, while at least a part of
said circuit patterns is used as an optical transmission channel
marker; and
[0076] a second step of removing a part of board portion located
between adjustment portions of said circuit pattern, and thereby
fabricating a groove for said optical transmission channel on said
retention board.
[0077] The 24.sup.th aspect of the present invention is a
fabrication method for an optical transmission channel board
according to the 22.sup.nd or the 23.sup.rd aspect of the present
invention, wherein said first step of embedding said circuit
patterns is a step of forming a circuit pattern used as an optical
element marker for positioning an optical element.
[0078] The 25.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 24.sup.th aspect of the present invention, wherein
said first step of embedding said circuit patterns is a step of
forming circuit patterns a part of which is used as said electric
circuit and said optical element marker, or alternatively apart of
which is used as said optical element marker and said optical
transmission channel marker.
[0079] The 26.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 24.sup.th aspect of the present invention, wherein
said first step of embedding said circuit patterns is a step of
forming circuit patterns a part of which is used as two or all
selected from said electric circuit, said optical element marker,
and said optical transmission channel marker.
[0080] The 27.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 24.sup.th aspect of the present invention, wherein
said second step is a step of fabricating said groove by etching
using a mask corresponding to said part of board portion.
[0081] The 28.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 22.sup.nd or the 23.sup.rd aspect of the present
invention, wherein said layer containing an electrically conductive
material is composed of a composite material containing resin and
inorganic filler.
[0082] The 29.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 22.sup.nd or the 23.sup.rd aspect of the present
invention, wherein said first step is a step of forming said
circuit patterns by etching said layer containing an electrically
conductive material by using a mask corresponding to said circuit
patterns.
[0083] The 30.sup.th aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 22.sup.nd or the 23.sup.rd aspect of the present
invention, further comprising a third step of arranging an optical
transmission channel in said groove.
[0084] The 31.sup.st aspect of the present invention is the
fabrication method for an optical transmission channel board
according to the 30.sup.th aspect of the present invention, further
comprising a fourth step of mounting an optical element in said
circuit pattern such that said optical element is arranged above
said optical transmission channel, wherein
[0085] said optical element is at least any one of a laser element
and a photo receiving element.
[0086] The 32.sup.nd aspect of the present invention is the
fabrication method for an optical transmission channel board
according to any one of the 1.sup.st, 22.sup.nd, and the 23.sup.rd
aspects of the present invention, wherein said optical transmission
channel is an optical fiber.
[0087] The 33.sup.rd aspect of the present invention is a board
with built-in optical transmission channel comprising:
[0088] a board;
[0089] circuit patterns formed on said board and including a
plurality of wirings; and
[0090] a plurality of optical transmission channels embedded in
said board; wherein
[0091] at least a certain plurality of said optical transmission
channels are arranged in a thickness direction of said board, and
wherein
[0092] in a vicinity of an end portion of each of said optical
transmission channels, an optical element electrically connected to
said circuit pattern can be optically connected to said optical
transmission channel.
[0093] The 34.sup.th aspect of the present invention is the board
with built-in optical transmission channel according to the
33.sup.rd aspect of the present invention, wherein said board is a
multilayered board containing a plurality of sub-boards, and
wherein
[0094] in each of said sub-boards, a single optical transmission
channel or a plurality of said optical transmission channels are
arranged in said thickness direction.
[0095] The 35.sup.th aspect of the present invention is the board
with built-in optical transmission channel according to the
34.sup.th aspect of the present invention, wherein a certain
plurality of said optical transmission channels are arranged also
in a direction substantially perpendicular to said thickness
direction.
[0096] The 36.sup.th aspect of the present invention is the board
with built-in optical transmission channel according to the
33.sup.rd aspect of the present invention, wherein a plurality of
said optical transmission channels are arranged in said thickness
direction within a layer of said board.
[0097] The 37.sup.th aspect of the present invention is the board
with built-in optical transmission channel according to the
36.sup.th aspect of the present invention, wherein a certain
plurality of said optical transmission channels are arranged also
in a direction substantially perpendicular to said thickness
direction.
[0098] The 38.sup.th aspect of the present invention is the board
with built-in optical transmission channel according to the
33.sup.rd aspect of the present invention, wherein said optical
transmission channels are embedded between a plurality of said
wirings.
[0099] The 39.sup.th aspect of the present invention is the board
with built-in optical transmission channel according to the
33.sup.rd aspect of the present invention, wherein each of said
optical transmission channels is an optical fiber.
[0100] The 40.sup.th aspect of the present invention is the board
with built-in optical transmission channel according to the
34.sup.th aspect of the present invention, wherein said board is
composed of a composite material containing resin and inorganic
filler.
[0101] The 41.sup.st aspect of the present invention is the board
with built-in optical transmission channel according to the
33.sup.rd aspect of the present invention, wherein said optical
element is a vertical-cavity surface-emitting laser.
[0102] The 42.sup.nd aspect of the present invention is the board
with built-in optical transmission channel according to the
41.sup.st aspect of the present invention, wherein a light-emitting
surface of said vertical-cavity surface-emitting laser and a
surface of said board are mutually opposing, and wherein
[0103] a plurality of light emission points are arranged in said
light-emitting surface.
[0104] The 43.sup.rd aspect of the present invention is the board
with built-in optical transmission channel according to the
33.sup.rd aspect of the present invention, wherein said end portion
of each of said optical transmission channels is cut substantially
into an angle of 45.degree..
[0105] The 44.sup.th aspect of the present invention is the board
with built-in optical transmission channel according to the
34.sup.th aspect of the present invention, wherein said vicinity of
said end portion of each of said optical transmission channels is
provided with an inclined surface for optically connecting said end
portion of said optical transmission channel with said optical
element.
[0106] The 45.sup.th aspect of the present invention is the data
processing apparatus comprising:
[0107] a board with built-in optical transmission channel according
to the 33.sup.rd aspect of the present invention;
[0108] said optical element arranged on said board with built-in
optical transmission channel; and
[0109] a semiconductor element mounted on said board with built-in
optical transmission channel.
[0110] The 46.sup.th aspect of the present invention is a
fabrication method for a board with built-in optical transmission
channel comprising:
[0111] a first step of forming all or a part of circuit
patterns;
[0112] a second step of forming guiding means for positioning an
optical transmission channel, wherein said forming in said second
step is carried out using said circuit patterns or alternatively at
the same time as the formation of at least a part of said circuit
patterns;
[0113] a third step of embedding said optical transmission channel
using said guiding means, and thereby forming a sub-board; and
[0114] a fourth step of preparing a plurality of sub-boards
mentioned above, and then stacking a plurality of said
sub-boards.
[0115] The 47.sup.th aspect of the present invention is a
fabrication method for a board with built-in optical transmission
channel comprising:
[0116] a first step of forming all or a part of circuit
patterns;
[0117] a second step of forming guiding means for positioning an
optical transmission channel, wherein said forming in said second
step is carried out using said circuit patterns or alternatively at
the same time as the formation of at least a part of said circuit
patterns; and
[0118] a third step of embedding a plurality of above-mentioned
optical transmission channels using said guiding means, and thereby
forming a board; wherein
[0119] in said third step, a certain plurality of said optical
transmission channels are arranged in a thickness direction of said
board.
[0120] The 48.sup.th aspect of the present invention is the
fabrication method for a board with built-in optical transmission
channel according to the 46.sup.th or the 47.sup.th aspect of the
present invention, wherein said first step and said second step are
substantially simultaneously carried out, and wherein said guiding
means is formed at the same time as the formation of a
predetermined wiring included in said circuit patterns.
[0121] The 49.sup.th aspect of the present invention is the
fabrication method for a board with built-in optical transmission
channel according to the 46.sup.th or the 47.sup.th aspect of the
present invention, wherein said optical transmission channel is an
optical fiber one end face of which is an inclined surface, and
wherein said optical fiber is embedded such that said inclined
surface is arranged in a direction opposite to a surface of said
board where an optical element electrically connected to said
circuit pattern is mounted.
[0122] An example of a board with built-in optical transmission
channel according to the present invention described above
comprises: circuit patterns formed on a board; and a plurality of
optical transmission channels embedded in the board, wherein a
plurality of the optical transmission channels are arranged in the
thickness direction of the board. Thus, an optical element can be
mounted above the vicinity of the end portion of each optical
transmission channel, so that a large number of optical
transmission channels can be arranged efficiently. This arrangement
realizes a fabrication method for a board with built-in optical
transmission channel permitting optical connection with an optical
element and realizing efficient arrangement of a large number of
optical transmission channels.
[0123] An aspect of the present invention provides: an optical
transmission channel board which can be fabricated in a simpler
fabrication process; its fabrication method; and a data processing
apparatus employing this optical transmission channel board.
[0124] Another aspect of the present invention provides: an optical
transmission channel board which simplifies a centering process
between an optical element and an optical transmission channel end
fewer, or does not need a centering process; its fabrication
method; and a data processing apparatus employing an optical
transmission channel board. Yet another aspect of the present
invention provides the advantage of permitting optical connection
with an optical element and realizing efficient arrangement of a
large number of optical transmission channels.
BRIEF DESCRIPTION OF THE DRAWINGS
[0125] FIG. 1 is a perspective view schematically showing a
configuration of an optical transmission channel board 100
according to Embodiment 1 of the present invention.
[0126] FIG. 2(a) is a diagram illustrating a fabrication method for
an optical transmission channel board 100 according to Embodiment 1
of the present invention.
[0127] FIG. 2(b) is a diagram illustrating a fabrication method for
an optical transmission channel board 100 according to Embodiment 1
of the present invention.
[0128] FIG. 2(c) is a diagram illustrating a fabrication method for
an optical transmission channel board 100 according to Embodiment 1
of the present invention.
[0129] FIG. 2(d) is a diagram illustrating a fabrication method for
an optical transmission channel board 100 according to Embodiment 1
of the present invention.
[0130] FIG. 3(a) is a diagram illustrating a fabrication method for
an optical transmission channel board 100 according to Embodiment 1
of the present invention.
[0131] FIG. 3(b) is a diagram illustrating a fabrication method for
an optical transmission channel board 100 according to Embodiment 1
of the present invention.
[0132] FIG. 3(c) is a diagram illustrating a fabrication method for
an optical transmission channel board 100 according to Embodiment 1
of the present invention.
[0133] FIG. 3(d) is a diagram illustrating a fabrication method for
an optical transmission channel board 100 according to Embodiment 1
of the present invention.
[0134] FIG. 4(a) is a process sectional view illustrating a
fabrication method for an optical transmission channel board 100
according to Embodiment 1 of the present invention.
[0135] FIG. 4(b) is a diagram illustrating a fabrication method for
an optical transmission channel board 100 according to Embodiment 1
of the present invention.
[0136] FIG. 5 is a sectional view illustrating optical connection
between an optical element 30 and an optical fiber 20 according to
Embodiment 1 of the present invention.
[0137] FIG. 6 is a sectional view illustrating optical connection
between an optical element 30 and an optical fiber 20 according to
Embodiment 1 of the present invention.
[0138] FIG. 7 is a sectional view schematically showing a
configuration in which an optical element 30 is mounted on an
optical transmission channel board 100 according to Embodiment 1 of
the present invention.
[0139] FIG. 8(a) is a sectional view showing a modification of an
optical transmission channel board 100 according to the present
invention.
[0140] FIG. 8(b) is a sectional view showing a modification of an
optical transmission channel board 100 according to the present
invention.
[0141] FIG. 9(a) is a sectional view showing a modification of an
optical transmission channel board 100 according to the present
invention.
[0142] FIG. 9(b) is a sectional view showing a modification of an
optical transmission channel board 100 according to the present
invention.
[0143] FIG. 10(a) is a sectional view showing a modification of an
optical transmission channel board 100 according to the present
invention.
[0144] FIG. 10(b) is a sectional view showing a modification of an
optical transmission channel board 100 according to the present
invention.
[0145] FIG. 11 is a sectional view schematically showing a
configuration in which an MCM 35 is mounted on an optical
transmission channel board 100 according to Embodiment 1 of the
present invention.
[0146] FIG. 12 is a perspective view schematically showing a
configuration of an optical module (data processing apparatus)
employing an optical transmission channel board 100 according to
Embodiment 1 of the present invention.
[0147] FIG. 13(a) is a diagram illustrating a fabrication method
for an optical transmission channel board 100 according to
Embodiment 2 of the present invention.
[0148] FIG. 13(b) is a diagram illustrating a fabrication method
for an optical transmission channel board 100 according to
Embodiment 2 of the present invention.
[0149] FIG. 13(c) is a diagram illustrating a fabrication method
for an optical transmission channel board 100 according to
Embodiment 2 of the present invention.
[0150] FIG. 13(d) is a diagram illustrating a fabrication method
for an optical transmission channel board 100 according to
Embodiment 2 of the present invention.
[0151] FIG. 13(e) is a diagram illustrating a fabrication method
for an optical transmission channel board 100 according to
Embodiment 2 of the present invention.
[0152] FIG. 14(a) is a diagram illustrating a modification of a
fabrication method for an optical transmission channel board 100
according to Embodiment 2 of the present invention.
[0153] FIG. 14(b) is a diagram illustrating a modification of a
fabrication method for an optical transmission channel board 100
according to Embodiment 2 of the present invention.
[0154] FIG. 14(c) is a diagram illustrating a modification of a
fabrication method for an optical transmission channel board 100
according to Embodiment 2 of the present invention.
[0155] FIG. 14(d) is a diagram illustrating a modification of a
fabrication method for an optical transmission channel board 100
according to Embodiment 2 of the present invention.
[0156] FIG. 15 is a main part enlarged perspective view which shows
wirings 12 of an optical transmission channel board 100 according
to Embodiments 1 and 2 of the present invention.
[0157] FIG. 16 is a main part enlarged perspective view which shows
wirings 12 of an optical transmission channel board 100 according
to Embodiments 1 and 2 of the present invention.
[0158] FIG. 17 is a plan view schematically showing a configuration
of an optical fiber 20 which has a Y branching section 23 on an
optical transmission channel board 100 according to Embodiments 1
and 2 of the present invention.
[0159] FIG. 18 is a partial enlarged perspective view showing an
optical element 30 and a portion around optical fibers 20 of an
optical transmission channel board 100 according to Embodiments 1
and 2 of the present invention.
[0160] FIG. 19 is a partial enlarged perspective view showing an
optical element 30 and a portion around optical fibers 20 of an
optical transmission channel board 100 according to Embodiments 1
and 2 of the present invention.
[0161] FIG. 20 is a partial enlarged perspective view showing an
optical element 30 and a portion around optical fibers 20 of an
optical transmission channel board 100 according to Embodiments 1
and 2 of the present invention.
[0162] FIG. 21 is a perspective view schematically showing a
configuration of an optical transmission channel board 200
according to Embodiment 3 of the present invention.
[0163] FIG. 22(a) is a process sectional view illustrating a
fabrication method for an optical transmission channel board 200
according to Embodiment 3 of the present invention.
[0164] FIG. 22(b) is a process sectional view illustrating a
fabrication method for an optical transmission channel board 200
according to Embodiment 3 of the present invention.
[0165] FIG. 22(c) is a process sectional view illustrating a
fabrication method for an optical transmission channel board 200
according to Embodiment 3 of the present invention.
[0166] FIG. 22(d) is a process sectional view illustrating a
fabrication method for an optical transmission channel board 200
according to Embodiment 3 of the present invention.
[0167] FIG. 23(a) is a process sectional view illustrating a
fabrication method for an optical transmission channel board 200
according to Embodiment 3 of the present invention.
[0168] FIG. 23(b) is a process sectional view illustrating a
fabrication method for an optical transmission channel board 200
according to Embodiment 3 of the present invention.
[0169] FIG. 23(c) is a process sectional view illustrating a
fabrication method for an optical transmission channel board 200
according to Embodiment 3 of the present invention.
[0170] FIG. 23(d) is a process sectional view illustrating a
fabrication method for an optical transmission channel board 200
according to Embodiment 3 of the present invention.
[0171] FIG. 24 is a process sectional view illustrating a
fabrication method for an optical transmission channel board 200
according to Embodiment 3 of the present invention.
[0172] FIG. 25 is a main part enlarged sectional view showing a
groove 122 and an optical fiber 120 of an optical transmission
channel board 200 according to Embodiment 3 of the present
invention.
[0173] FIG. 26 is a sectional view illustrating optical connection
between an optical element 130 and an optical fiber 120 of an
optical transmission channel board 200 according to Embodiment 3 of
the present invention.
[0174] FIG. 27 is a sectional view illustrating optical connection
between an optical element 130 and an optical fiber 120 of an
optical transmission channel board 200 according to Embodiment 3 of
the present invention.
[0175] FIG. 28 is a sectional view schematically showing a
configuration in which an MCM 135 is mounted on an optical
transmission channel board 200 according to Embodiment 3 of the
present invention.
[0176] FIG. 29 is a perspective view schematically showing a
configuration of an optical module (data processing apparatus)
employing an optical transmission channel board 200 according to
Embodiment 3 of the present invention.
[0177] FIG. 30(a) is a main part enlarged view showing a groove 122
of an optical transmission channel board 200 according to
Embodiment 4 of the present invention.
[0178] FIG. 30(b) is a main part enlarged view showing a state in
which an optical fiber 120 is placed in a groove 122 of an optical
transmission channel board 200 according to Embodiment 4 of the
present invention.
[0179] FIG. 30(c) is a main part enlarged view showing a state in
which an optical fiber 120 is placed in a groove 122 of an optical
transmission channel board 200 according to Embodiment 4 of the
present invention.
[0180] FIG. 30(d) is a main part enlarged view showing a state in
which an optical fiber 120 is placed in a groove 122 of an optical
transmission channel board 200 according to Embodiment 4 of the
present invention.
[0181] FIG. 31 (a) is a main part enlarged view showing a groove
122 of an optical transmission channel board 200 according to a
modification of the present invention.
[0182] FIG. 31 (b) is a main part enlarged view showing a state in
which an optical fiber 120 is placed in a groove 122 of an optical
transmission channel board 200 according to a modification of the
present invention.
[0183] FIG. 32 is a plan view schematically showing a state in
which an optical fiber 120 having a Y branching section 123 is
placed on an optical transmission channel board 200 according to
the present invention.
[0184] FIG. 33 is a sectional view showing relation between an
optical fiber 120 and an edge emitting type element 160 which are
placed and mounted on an optical transmission channel board 200
according to the present invention.
[0185] FIG. 34 is a perspective view schematically showing a
configuration of a board with built-in optical transmission channel
300 according to Embodiment 5 of the present invention.
[0186] FIG. 35 is a sectional view schematically showing a
configuration of a board with built-in optical transmission channel
300 according to Embodiment 5 of the present invention.
[0187] FIG. 36 is a sectional view illustrating optical connection
between an optical element 230 and an optical transmission channel
220.
[0188] FIG. 37 is a sectional view illustrating optical connection
between an optical element 230 and an optical transmission channel
220.
[0189] FIG. 38 is a sectional view illustrating optical connection
between an optical element 230 and a plurality of optical
transmission channels 220a and 220b.
[0190] FIG. 39 is a sectional view illustrating optical connection
between an optical transmission channel 220a and an optical
transmission channel 220b.
[0191] FIG. 40(a) is a process sectional view illustrating a
fabrication method for a board with built-in optical transmission
channel 300.
[0192] FIG. 40(b) is a process sectional view illustrating a
fabrication method for aboard with built-in optical transmission
channel 300.
[0193] FIG. 40(c) is a process sectional view illustrating a
fabrication method for aboard with built-in optical transmission
channel 300.
[0194] FIG. 40(d) is a process sectional view illustrating a
fabrication method for aboard with built-in optical transmission
channel 300.
[0195] FIG. 41(a) is a process sectional view illustrating a
fabrication method for aboard with built-in optical transmission
channel 300.
[0196] FIG. 41(b) is a process sectional view illustrating a
fabrication method for aboard with built-in optical transmission
channel 300.
[0197] FIG. 41(c) is a process sectional view illustrating a
fabrication method for aboard with built-in optical transmission
channel 300.
[0198] FIG. 41(d) is a process sectional view illustrating a
fabrication method for aboard with built-in optical transmission
channel 300.
[0199] FIG. 42(a) is a process sectional view illustrating a
fabrication method for aboard with built-in optical transmission
channel 300.
[0200] FIG. 42(b) is a process sectional view illustrating a
fabrication method for aboard with built-in optical transmission
channel 300.
[0201] FIG. 43 is a sectional view schematically showing a
configuration of a board with built-in optical transmission channel
300 on which an optical element 230 is mounted.
[0202] FIG. 44 is a sectional view schematically showing a
configuration of a board with built-in optical transmission channel
300 on which an MCM 235 is mounted.
[0203] FIG. 45(a) is a process sectional view illustrating another
fabrication method for aboard with built-in optical transmission
channel 300.
[0204] FIG. 45(b) is a process sectional view illustrating another
fabrication method for aboard with built-in optical transmission
channel 300.
[0205] FIG. 45(c) is a process sectional view illustrating another
fabrication method for aboard with built-in optical transmission
channel 300.
[0206] FIG. 46 is a sectional view schematically showing another
configuration of a board with built-in optical transmission channel
300.
[0207] FIG. 47 is a sectional view schematically showing a
configuration of a board with built-in optical transmission channel
300.
[0208] FIG. 48 is a perspective view schematically showing a
configuration of an optical module (data processing apparatus)
employing a board with built-in optical transmission channel
300.
[0209] FIG. 49 is a plan view schematically showing a configuration
of an optical fiber 220 having a Y branching section 223.
[0210] FIG. 50 is a perspective view showing a prior art optical
module 1000.
[0211] FIG. 51 is a sectional view showing a prior art optical
module 2000.
[0212] FIG. 52 is a perspective view illustrating the mounting
hierarchy of a prior art communication system apparatus 3000 for
performing optical communications.
[0213] FIG. 53 is a sectional view showing a prior art wiring board
4000.
[0214] FIG. 54(a) is a plan view showing a prior art wiring board
4000.
[0215] FIG. 54(b) is a sectional view taken along line X-X' in
54(a).
[0216] FIG. 55 is a perspective view showing a prior art light
wiring board 5000.
DESCRIPTION OF REFERENCE NUMERALS
[0217] 10 Board [0218] 11 Reflection surface [0219] 12 Wiring
[0220] 13 Wiring [0221] 15 Circuit pattern [0222] 16, 17 Guide
layer [0223] 18 Guide wall [0224] 20 Optical fiber [0225] 21 End
face [0226] 22 Groove [0227] 23 Branching section [0228] 25 Light
(optical signal) [0229] 26 Level difference [0230] 28 Land [0231]
30 Optical element [0232] 32 Connection member [0233] 34 Interposer
[0234] 36 Mirror [0235] 37 Stopper [0236] 40 Carrier sheet [0237]
42 Metal layer [0238] 51, 52, 53 Mask [0239] 60 Edge emitting type
element [0240] 100 Optical transmission channel board [0241] 110
Board [0242] 111 Reflection surface [0243] 112 Wiring (groove-use
wiring) [0244] 113 Wiring [0245] 120 Optical fiber [0246] 121 End
face [0247] 122 Groove [0248] 123 Branching section [0249] 125
Light (optical signal) [0250] 130 Optical element [0251] 131
Electronic components [0252] 132 Connection member [0253] 134
Interposer [0254] 140 Carrier sheet [0255] 142 Metal layer [0256]
150, 51 Mask [0257] 200 Optical transmission channel board [0258]
210 Board [0259] 210a, 210b Sub-board [0260] 211 Reflection surface
[0261] 212 Wiring [0262] 213 Wiring [0263] 215 Circuit pattern
[0264] 217 Guide layers [0265] 218 Guide wall [0266] 220 Optical
transmission channel (optical fiber) [0267] 221 End face [0268] 222
Groove [0269] 223 Branching section [0270] 225 Light (optical
signal) [0271] 227 Optical connector [0272] 230 Optical element
[0273] 232 Connection member [0274] 234 Interposer [0275] 235 MCM
[0276] 236 Via hole (interlayer connection member) [0277] 237
Electric input and output section [0278] 240 Carrier sheet [0279]
242 Metal layer [0280] 250, 251, 252, 253 Mask [0281] 300 Board
with built-in optical fiber [0282] 1000 Optical module [0283] 2000
Optical module [0284] 3000 Communication system apparatus [0285]
4000 Wiring board [0286] 5000 Optical wiring board
PREFERRED EMBODIMENTS OF THE INVENTION
[0287] Embodiments of the present invention are described below
with reference to the drawings. For the simplicity of description
of the drawings, components having substantially the same function
are designated by like reference numerals. It should be noted that
the present invention is not limited to the embodiments described
below.
Embodiment 1
[0288] An optical transmission channel board according to
Embodiment 1 and its fabrication method are described below with
reference to FIGS. 1-4.
[0289] FIG. 1 is a perspective view schematically showing the
configuration of an optical transmission channel board 100 of
Embodiment 1.
[0290] As shown in FIG. 1, the optical transmission channel board
100 of Embodiment 1 comprises: a board 10; and circuit patterns 15
including a plurality of wirings 12 formed on the board 10. A
plurality of optical fibers 20 are arranged between each the wiring
12 of the circuit patterns 15, respectively. An optical
transmission channel of the present invention indicates an optical
fiber 20 of Embodiment 1. Thus, Embodiment 1 is described for the
case of optical fibers. However, an "optical transmission channel"
in the present specification indicates a line-shaped member capable
of transmitting light. This holds also in the other embodiments
described below.
[0291] When viewed from the above of the board 10 (viewed from the
normal direction of the board 10), the optical fibers 20 are
arranged between the wirings 12 such as to contact substantially
with the wirings 12. More specifically, the optical fibers 20 are
arranged in grooves 22 formed between the wirings 12, and hence are
built in the board 10. In other words, the grooves 22 formed
between the wirings 12 serve as mounting sections for the optical
fibers 20. Further, in Embodiment 1, the uppermost portions of the
optical fibers 20 are substantially in plane with the upper
surfaces of the circuit patterns 15 and the wirings 12. A method
for aligning them in plane is described later in a fabrication
method for the optical transmission channel board 100.
[0292] In the optical transmission channel board (board with
built-in optical fiber) 100 shown in FIG. 1, an optical element 30
is mounted with reference to a marker (an optical element marker,
hereafter) for positioning the optical element. The optical element
is electrically connected to the wirings 12, and optically
connected to the optical fibers 20. Although the optical element
marker is not shown in the figure, a typical marker is composed of
positioning reference planes 1103a, 1103b, and 1103c used in the
prior art of FIG. 50. The optical element 30 is a laser element
such as a semiconductor laser, or alternatively a photo receiving
element such as a photo-diode. In Embodiment 1, the optical element
30 is arranged such as to substantially contact with the upper
portions of the optical fibers 20.
[0293] In Embodiment 1, the board 10 serving as an example of a
retention board of the present invention is composed of a composite
material containing resin (such as a thermosetting resin and a
thermoplastic resin) and inorganic filler. In this example, a
thermosetting resin is used as the resin of the composite material.
The board 10 may be composed only of thermosetting resin without
inorganic filler. The thermosetting resin is an epoxy resin or the
like. When added, the inorganic filler is Al.sub.2O.sub.3,
SiO.sub.2, MgO, BN, AlN, or the like. Various physical properties
(such as the thermal expansion coefficient) can be controlled when
the inorganic filler is added. Thus, the board 10 is preferably
formed of a composite material containing inorganic filler. In
Embodiment 1, inorganic filler of 100 weight units or more
(preferably 140-180 weight units) is contained relative to the
thermosetting resin of 100 weight units.
[0294] The role of inorganic filler is as follows. When
Al.sub.2O.sub.3, BN, or AlN is added as inorganic filler, the
thermal conductivity of the board 10 is improved. Further, when an
appropriate inorganic filler is selected, the thermal expansion
coefficient can be adjusted. In case that the thermal expansion
coefficient is rather increased by the resin component, the
addition of SiO.sub.2, AlN, or the like can decrease the thermal
expansion coefficient. In an appropriate case, when MgO is added,
the thermal conductivity is improved while the thermal expansion
coefficient is increased. Further, when Si.sub.2O (especially,
amorphous SiO.sub.2) is added, the thermal expansion coefficient is
decreased while the dielectric constant is reduced.
[0295] A fabrication method for an optical transmission channel
board according to Embodiment 1 is described below.
[0296] An optical transmission channel board 100 of Embodiment 1 is
fabricated using a transfer method. More specifically, a metal
layer formed on a supporting board is patterned so that circuit
patterns 15 are formed that include: a plurality of wirings 12,
other wirings 13, and wirings used as an optical element marker.
Then, optical fibers 20 are arranged between the wirings 12 of the
circuit patterns 15. After that, a material containing resin is
deposited on the supporting board so as to cover the circuit
patterns 15 and the optical fibers 20. Then, when the supporting
board is removed, the circuit patterns 15 are exposed on the
surface so that the optical transmission channel board 100 of
Embodiment 1 is obtained.
[0297] The above-mentioned fabrication method for an optical
transmission channel board is described below in further detail
with reference to FIGS. 2-4.
[0298] As shown in FIG. 2(a), prepared first is a carrier sheet
(transfer formation material) 40 on which a metal layer 42 serving
as an example of a layer containing an electrically conductive
material of the present invention is formed. The metal layer 42 is
composed of copper or the like. The carrier sheet 40 serving as an
example of a substrate of the present invention is composed of a
metallic foil (a copper or aluminum foil), a resin sheet, or the
like. The thickness values of the metal layer 42 and the carrier
sheet 40 are approximately 3-50 .mu.m and approximately 25-200
.mu.m, respectively.
[0299] Then, as shown in FIG. 2(b), a mask 50 corresponding to the
circuit patterns 15 is placed above the metal layer 42. The metal
layer 42 is then etched. As a result, as shown in FIG. 2(c),
circuit patterns 15 are formed that include: the wirings 12 located
in the surrounding portion of the optical fibers 20; other wirings
13; and the wiring used as an optical element marker.
[0300] After the patterning by the above-mentioned etching, walls
for guiding the optical fibers 20 to be arranged are formed in at
least a part of the circuit patterns 15. In Embodiment 1, the guide
walls are formed on top of the wirings 12.
[0301] More specifically, as shown in FIG. 2(c), a mask 51 having
an opening in the portions corresponding to the wirings 12 is
arranged above the carrier sheet 40. Then, as shown in FIG. 2(d), a
guide layer 16 serving as a layer constituting the guide walls is
deposited on the wirings 12. In an example, the guide layer 16 is
composed of metal, and formed by sputtering. Vapor deposition,
plating, a deposition method, or the like may be used in place of
sputtering. The reason why the sputtering is used in the formation
of the guide layer 16 in Embodiment 1 is that this method provides
a preferable fabrication accuracy.
[0302] In case that the height of the guide walls for supporting
the optical fibers 20 is insufficient even after the guide layer 16
is formed, a mask 52 is arranged above the guide layer 16 as shown
in FIG. 3(a), and then another guide layer 17 is deposited on the
guide layer 16 serving as a base. The mask 52 may be the same as
the previous mask 51. The material constituting the guide layer 17
may be the same as, or different from, the material constituting
the guide layer 16. The material constituting the guide layers 16
and 17 is not limited to a metal, and may be another material (such
as ceramics). The method of deposition to be used is not limited to
sputtering, and may be another technique such as a flame deposition
method.
[0303] As such, as shown in FIG. 3(b), guide walls 18 constructed
from the guide layer 16 and the guide layer 17 is formed on the
wirings 12. The guide walls 18 constitute grooves 22 (optical fiber
mounting sections) in which the optical fibers 20 are to be
mounted. In Embodiment 1, the total thickness of the wiring 12 and
the guide wall 18 (guide layers 16 and 17) is greater than the
radius of the optical fiber 20 arranged between the guide walls 18.
This configuration ensures the optical fibers 20 to contact
substantially with the guide walls 18, and hence reduces mounting
discrepancy.
[0304] Then, as shown in FIG. 3(c), the optical fibers 20 are
arranged between the guide walls 18 (between the wirings 12). That
is, the optical fibers 20 are inserted into the grooves 22 formed
between the guide walls 18 (or the wirings 12).
[0305] The guide walls 18 have such spacing that the optical fibers
20 substantially contact with the guide walls 18 when arranged
therebetween. A slight excess in the spacing is allowable. More
specifically, this excess is preferably 0.1 .mu.m or less between
each optical fiber 20 and each of the right and left guide walls
18. The optical fibers 20 are arranged such as to contact with the
carrier sheet 40.
[0306] Then, as shown in FIG. 3(d), a material containing resin is
deposited on the carrier sheet 40 so that a board (insulating
board) 10 is formed. This deposition is performed such that the
circuit patterns 15 and the optical fibers 20 are covered. That is,
the material constituting the board 10 covers: the circuit patterns
15 including the wirings 12 and 13; the guide walls 18; and the
optical fibers 20. In Embodiment 1, the material constituting the
board 10 is deposited in a thickness of three times or more of the
radius of the optical fiber 20. The thickness of the board 10 can
be 0.18-0.4 mm or the like.
[0307] Then, as shown in FIG. 4(a), the board 10 is reversed and
the carrier sheet 40 is removed. As a result, an optical
transmission channel board 100 of Embodiment 1 is obtained. That
is, the circuit patterns 15 on the carrier sheet 40 are separated
so that the transfer is completed. The board 10 may be reversed
after the removal of the carrier sheet 40.
[0308] In the fabrication method of Embodiment 1, the circuit
patterns 15 and the optical fibers 20 simultaneously contact with
the carrier sheet 40 in the state of FIG. 3(d). Thus, in the state
of FIG. 4(a), the upper surface of the circuit patterns 15 and the
uppermost parts of the optical fibers 20 are substantially in
plane. Further, the resin surface (more specifically, the surface
of the composite material) of the board 10 is substantially in
plane with the upper surface of the circuit patterns 15 and the
uppermost parts of the optical fibers 20.
[0309] Further, according to the fabrication method of Embodiment
1, the optical fibers 20 can be simply embedded (built) in the
board 10. Further, in comparison with the case that the optical
fibers 20 are provided on the surface of the board 10, the optical
fibers 20 are protected more appropriately.
[0310] After that, as shown in FIG. 4(b), when an optical element
30 and an electronic component 31 are mounted on the circuit
patterns 15 exposed in the surface of the board 10, an optical
module is obtained.
[0311] The optical element 30 is a semiconductor laser or the like,
and is arranged such as to substantially contact with the top of
the optical fibers 20 in Embodiment 1. The phrase "arranged above
an optical transmission channel" according to the present invention
includes the state "arranged such as to substantially contact with
the top of an optical transmission channel (optical fiber 20)". The
optical element 30 may be a photo receiving element (such as a
photo-diode). The electronic component 31 mounted on the portion of
the wirings 13 among circuit patterns 15 is a semiconductor element
(such as a logic LSI). In the example shown in FIG. 4(b), the
electronic component (semiconductor element) 31 is electrically
connected to the wirings 13 through solder balls 32.
[0312] The optical element 30 and the optical fibers 20 can be
optically connected, for example, as shown in the schematic
sectional view of FIG. 5. That is, as shown in FIG. 5, a reflection
surface (inclined surface) 11 is formed in a part of board 10, so
that optical connection by light (an optical signal) 25 is
established between the optical element 30 and the optical fibers
20 via the reflection surface 11. In an example, the reflection
surface 11 is obtained by fabricating an inclined surface in the
board 10, and then forming a metal layer (such as an Au layer) on
the surface of the inclined surface. Alternatively, an optical
component (mirror) having a reflection surface 11 may be placed on
the board 10.
[0313] Further alternatively, as shown in the schematic sectional
view of FIG. 6, an end face 21 of the optical fiber 20 may be cut
aslant (such as a 45.degree. cut) so that the light 25 should be
reflected in the end face 21. This permits optical connection
between the optical element 30 and the optical fiber 20. In the
configuration shown in FIGS. 5 and 6, a transparent medium may be
present in the path of the light 25 between the optical element 30
and the optical fiber 20. The transparent medium is air, glass,
transparent resin, or the like. The transparent resin is a material
which permits optical connection between the optical element 30 and
the optical fiber 20 and which transmits light of a wavelength of
850 nm, 1330 nm, and 1550 nm or the like. More specifically, the
transparent resin is composed of polyimide, epoxy aramid, or the
like. Alternatively, an optical component (such as a lens) may be
arranged between the optical element 30 and the optical fiber 20.
The configurations of FIGS. 5 and 6 where the optical element 30
and the optical fiber 20 are not in close contact with each other
are different from those of FIGS. 1 and 4(b), and corresponds to
the configuration of FIG. 7 described later.
[0314] When the optical element 30 is mounted on the portion of the
wirings 12 in the circuit patterns 15, pad sections may be formed
on the wirings 12 so that element terminals of the optical element
30 may be connected to the pad sections by wire bonding.
Nevertheless, such wire bonding connection is disadvantageous in
high speed characteristics. Thus, as an example shown in FIG. 7,
the connection between the optical element 30 and the wirings 12 is
preferably realized by flip chip mounting or the like using
connection members (such as bumps and solder balls) 32. In this
case, lands are formed in the portions of the wirings 12 with which
the connection members 32 contact.
[0315] As described above, in Embodiment 1, the wirings 13 and the
wirings 12 are simultaneously fabricated as the circuit patterns 15
by using a single mask. The guide walls 18 for positioning the
optical fibers 20 are formed with reference to the wirings 12. That
is, in Embodiment 1, the wirings 12 and the portions between the
guide walls 18 used for positioning the optical fibers (correspond
to the previous guide grooves 104) are fabricated as the circuit
patterns 15 in the same process. This simplifies the fabrication
process in comparison with the prior art.
[0316] In Embodiment 1, the optical element marker (not shown)
included in the circuit patterns 15 corresponds to the positioning
reference planes 103a, 103b, and 103c for positioning the previous
optical element. The portions between the guide walls 18 for
positioning the optical fibers 20 correspond to the previous guide
grooves 104. The wirings 12 included in the circuit patterns 15
serve as a reference in the forming of the guide walls 18. That is,
the optical element marker for positioning the optical element 30
and the guide walls 18 for positionally regulating the optical
fibers 20 are formed using the same mask 50. Thus, the optical
element marker and the guide walls are aligned automatically. This
resolves the problem of centering, and permits optical connection
between the optical element 30 and the optical fibers 20.
[0317] In a possible case that a centering process is to be
performed in the optical transmission channel board 100 of
Embodiment 1 in order to further improve the optical connection,
rough centering has already been achieved with a precision better
than that of the prior art configuration. Thus, fine centering
solely is sufficient.
[0318] A first step of the present invention corresponds to the
step shown in FIG. 2(a), for example. A second step of the present
invention corresponds to the step shown in FIGS. 2(b)-2(c), for
example. An A step of the present invention corresponds to the step
shown in FIGS. 2(d)-3(b) 2, for example. A third step of the
present invention corresponds to the step shown in FIG. 3(c), for
example. A fourth step of the present invention corresponds to the
step shown in FIG. 3(d), for example. A fifth step of the present
invention corresponds to the step shown in FIG. 4(a), for example.
A sixth step of the present invention corresponds to the step shown
in FIG. 4(b), for example.
[0319] A part of circuit patterns used as an electric circuit of
the present invention corresponds to the wirings 13 of Embodiment
1. A part of circuit patterns for positionally regulating an
optical transmission channel of the present invention corresponds
to the wirings 12 of Embodiment 1.
[0320] The function of the optical element marker may be performed
by a part of circuit patterns for positioning an optical
transmission channel. The function maybe performed by a circuit
pattern for an electric circuit. The wirings 12 for positioning an
optical transmission channel may be used as an electric
circuit.
[0321] In Embodiment 1, the upper surface of the board 10 and the
upper most portions of the optical fibers 20 are substantially in
plane, and arranged so as to contact with the guide walls 18.
However, as shown in FIG. 8(a), the spacing between the wirings 12
may be smaller than the diameter of the optical fiber 20 so that
the upper surface of the board 10 may be out of plane with the
uppermost portions of the optical fibers 20. Further, the guide
walls 18 may be formed such as to contact with the optical fibers
in a manner shown in FIG. 8(b).
[0322] Alternatively, as shown in FIG. 9(a), a carrier sheet 40 may
serve as a retention board without the use of a board 10. In this
case, optical fibers 20 are arranged between wirings 12 so that the
board is use as an optical transmission channel board. Further,
guide walls 18 may be provided as shown in FIG. 9(b) so that
optical fibers 20 may be arranged. The optical fibers 20 may be
arranged such as to contact or not contact with the retention board
(carrier sheet 40).
[0323] In Embodiment 1, the guide layers 16 and 17 are stacked.
However, as shown in FIG. 10(a), a layer containing an electrically
conductive material may have a thickness permitting the positioning
of an optical fiber, so that guide walls 18 may be formed solely by
wirings 12.
[0324] As shown in FIG. 11, the optical fibers 20 maybe optically
connected to optical elements within an MCM (multi-chip module) 35,
in place of a single discrete optical element 30. In this example,
a plurality of electronic components 33a and 33b are mounted on an
interposer 34 so that an MCM 35 is constructed. At least one of the
electronic components 33a and 33b is an optical element. Both
electronic components 33a and 33b may be laser elements
(semiconductor lasers), or may be photo receiving elements
(photo-diodes). Alternatively, they may be a combination of a laser
element and a photo receiving element. In an example, an opening is
formed in a part of the interposer 34 corresponding to the optical
path between the optical elements and the optical fibers. An
optical component (such as a lens) may be arranged in the position
of the opening. The optical elements 33a and 33b may be mounted on
the back side of the interposer 34.
[0325] In the prior art, position adjustment has been necessary
between the grooves 22, the interposer 34, and the electronic
components 33a and 33b corresponding to the optical fibers 20.
However, according to the fabrication method of Embodiment 1, the
optical fibers 20 are positioned on the basis of the positions of
the grooves 22 formed by the wirings 12. Further, the interposer 34
is positioned by the optical element marker formed using the same
mask as that used in the formation of the wirings 12. This
simplifies the position adjustment between the optical fibers 20
and the interposer 34, and hence simplifies the centering process
in comparison with the prior art.
[0326] In the optical transmission channel board 100 of Embodiment
1, the wirings 12 and the other wirings (such as 13) are formed
simply by a transfer method. Thus, even electronic components other
than optical elements (semiconductor elements) can be mounted
similarly to the case of a typical printed circuit board. FIG. 12
shows an optical module in which electronic components 31 (31a,
31b, 31c, 31d, 31e) in addition to optical elements 30a and 30b are
mounted on an optical transmission channel board 100. The optical
module shown in FIG. 12 can be used as a data processing apparatus.
This module is described below in further detail.
[0327] The optical element 30a is a laser element, and may be a
vertical-cavity surface-emitting laser (VCSEL). On the other hand,
the optical element 30b is a photo receiving element, and may be a
photo-diode element having a plurality of photo-receiving sections.
For the simplicity of understanding the configuration of Embodiment
1, grooves 22 are shown without optical fibers 20 to be optically
connected to the optical element 30a.
[0328] The laser element 30a is connected to a driver IC 31a. The
driver IC 31a is connected to an LSI chip (such as a logic LSI like
an image processing LSI) 31b. The LSI chip 31b is connected to a
memory chip 31c. The photo receiving element 30b is connected to
the LSI chip 31b via an amplifier (preamplifier) 31d and an
amplifier 31e. The electronic components 31 are mutually connected
through the wirings 13 in the circuit patterns 15.
[0329] The problem of centering is resolved by the configuration of
optical element markers for positioning the wirings 12 and the
optical elements. Thus, the wirings 13 may be formed on the board
10 separately in a step other than a transfer process (for example,
in an independent and later step). However, from the perspective of
fabrication procedure, cost, and the like, it is efficient to
fabricate the wirings 13 in the same step as that of the wirings 12
and the optical element markers similarly to the fabrication method
of Embodiment 1.
[0330] The optical module (data processing apparatus) shown in FIG.
12 can perform optical transmission through the optical fibers 20.
Thus, mass data can be transmitted at a high speed. Further, this
module fabricated by the method of Embodiment 1 has a low
fabrication cost.
[0331] That is, the circuit patterns 15 (including the wirings 12)
and the grooves 22 are formed integrally. This simplifies the
fabrication process, and reduces the fabrication cost which has
been increased by a larger tolerance discrepancy in the prior art.
Thus, the cost can be reduced in optical modules presently used in
optical communications (such as the Internet and telephone). This
accelerates the spread of such optical modules.
[0332] Further, the cost reduction permits the use of economical
optical transmission in within-the-board transmission (level 2) in
the communication system apparatus 3000 shown in FIG. 52. This
improves the speed of within-the-board transmission. As such, the
present invention is applicable to the bookshelf type communication
system apparatus 3000 shown in FIG. 52. Similarly, the optical
transmission channel board or optical module 100 of the present
invention may be used as a main apparatus such as a next-generation
high performance optical I/O module and a data processing apparatus
(like an image processing apparatus)
Embodiment 2
[0333] A fabrication method for an optical transmission channel
board according to Embodiment 2 is described below. FIGS.
13(a)-13(e) are sectional views of an optical transmission channel
board used for describing a fabrication method for an optical
transmission channel board according to Embodiment 2.
[0334] First, starting from the state shown in FIG. 2(a), guide
layers 16 and 17 are stacked on a metal layer 42 so that the state
shown in FIG. 13(a) is achieved. Then, as shown in FIG. 13(b),
these layers (17, 16, 42) are etched using a mask 53 for defining
the shape of circuit patterns 15. As a result, circuit patterns 15
are formed that include: wirings 12 for constituting grooves 22;
other wirings 13; and an optical element marker for positioning an
optical element.
[0335] Then, as shown in FIG. 13(c), the guide layers 16 and 17 on
top of the wirings 13 are etched using a mask 54 for defining the
shape of the wiring 13 portion. As a result of this etching, guide
walls 18 and wirings 13 are formed as shown in FIG. 13(d). This
configuration is similar to that of FIG. 3(b) in Embodiment 1.
After that, when processes similar to those of FIG. 3(c) and its
subsequent are performed, an optical transmission channel board 100
or optical module shown in FIG. 13(e) is obtained.
[0336] That is, in Embodiment 1, the guide layers 16 and 17 have
been stacked after the formation of the wirings 12. In contrast, in
Embodiment 2, the wirings 12 are formed after the stacking of the
guide layers 16 and 17.
[0337] A layer composed of a material different from a layer
containing an electrically conductive material according to the
present invention corresponds to each of the guide layers 16 and 17
of Embodiment 2. In place of these two layers which may be composed
of mutually different materials, a single layer may be used that
has a predetermined thickness. Alternatively, more than two layers
may be stacked. That is, it is sufficient that the optical fibers
20 can be positioned.
[0338] A "C" step of the present invention corresponds to the step
shown in FIG. 13(a), for example. A "B" step of the present
invention corresponds to the step shown in FIGS. 13(c)-13(d), for
example.
[0339] The mask 54 of Embodiment 2 has a shape corresponding to the
wirings 13. However, it is sufficient that at least the portion
constituting the guide walls 18 (corresponding to the wirings 12)
is covered.
[0340] In Embodiment 2, the guide layers 16 and 17 on top of the
wirings 13 are removed. However, these layers need not be removed,
and may be kept embedded in the board 10.
[0341] In Embodiment 2, the guide layers 16 and 17 are stacked.
However, as shown in FIG. 10(b), the layer containing an
electrically conductive material may have a thickness sufficient
for positioning the optical fibers, so that the guide walls 18
maybe formed only by the wirings 12. In this case, an unnecessary
portion (indicated by a dotted line in the figure) of the thickness
of the wirings 13 serving as a circuit pattern used as an electric
circuit of the present invention may be removed. This portion
corresponds to the upper portion of the wirings 13, since the
optical transmission channel board 100 is retained upside down
during the fabrication.
[0342] In Embodiment 2, the grooves 22 and the circuit patterns 15
are fabricated simultaneously using the mask 53 corresponding to
the circuit patterns 15. However, as shown in FIGS. 14(a)-14(d),
the circuit patterns 15 may be formed after the formation of the
grooves 22. That is, as shown in FIG. 14(b), the grooves 22 are
first formed using a mask 55 corresponding to the grooves 22. At
the same time, an optical element marker for positioning the
optical element is formed, although not illustrated. Then, etching
is performed using a predetermined mask, so that the guide walls 18
and the circuit patterns 15 (including the wirings 12 and the
wirings 13) are formed as shown in FIG. 14(c). Since FIG. 14(c)
shows a configuration similar to that of FIG. 3(b), when the steps
after FIG. 3(c) are performed, an optical transmission channel
board 100 or optical module shown in FIG. 14(d) is obtained.
[0343] Further features and further modifications of the optical
transmission channel board 100 are described below with reference
to other drawings.
[0344] As described above, the steps shown in FIGS. 2(a)-4(a)
described in Embodiment 1 are performed so that the circuit
patterns 15 including the wirings 12 are formed, the uppermost
portions of the optical fibers 20 are substantially in plane with
the upper surface of the circuit patterns 15. However, a
predetermined portion or the entirety of the circuit patterns 15
can be depressed relative to the resin surface (or composite
material surface) of the board 10.
[0345] For example, as shown in FIG. 15, the upper surface of the
wirings 12 can be depressed relative to the surface (resin surface)
10a of the board 10 by the following method, so that a level
difference 26 can be formed.
[0346] That is, in the patterning in FIG. 2(b), in addition to the
unnecessary portion of the metal layer 42, a carrier sheet 40
portion constituting the base for the circuit patterns 15 are also
etched. Then, in a resin application step (that is, a step of
applying a composite material) shown in FIG. 3(d), the resin goes
deeper than the surface of the wirings 12 toward the carrier sheet
40. As a result, a level difference 26 is formed between the
surface 10a of the board 10 and the upper surface of the wirings
12. Similarly in Embodiment 2, when a predetermined portion of the
carrier sheet 40 is etched in the patterning in FIG. 13(b), a level
difference 26 is formed.
[0347] When a land 28 used as a mounting section for an optical
element 30 is formed in a part of the wiring 12 (typically, in an
end portion), the level difference 26 serves as a dam for retaining
the solder. That is, the solder serves as a solder resist, or
assists a solder resist. The land 28 portion is usually wider than
the wiring section. Thus, the land 28 may be formed as shown in
FIG. 16. In this case, when the guide walls 18 are designed such as
not to be formed under the wiring 12 where the land 28 is located,
a mounting region (a groove 22) for the optical fiber 20 is
appropriately secured.
[0348] The land 28 shown in FIG. 16 is a rectangular land, but may
be a circular land. Further, description has been made for the case
of the wiring 12. However, a land having such a configuration may
be fabricated in another wiring (such as a wiring 13) in the
circuit patterns 15.
[0349] In the optical transmission channel board 100 of embodiments
1 and 2, the optical fibers 20 are embedded in the board 10. Thus,
even in case that the optical fibers 20 have a Y branching section
23 as shown in FIG. 17 and hence are fragile, the present embedding
enforces the optical fibers 20. More specifically, as shown in FIG.
17, the optical fiber 20 is embedded into the groove 22 (optical
fiber mounting section) formed by the wirings 12 and the guide
walls 18 under the wirings. When such optical fibers 20 having a Y
branching section 23 are used, an optical module (board with
built-in optical fiber) suitable for wavelength multiplexing is
provided.
[0350] Optical connection between the optical element 30 and the
optical fibers 20 can be performed as shown in FIGS. 18-20. FIGS.
18, 19, and 20 are partial enlarged perspective views showing the
surrounding portion of the optical element 30 and the optical
fibers 20. For simplicity, a yet hidden portion in the optical
element 30 is indicated as a shaded region.
[0351] In the configuration shown in FIG. 18, a mirror 36 having a
reflection surface 11 is arranged under the optical element 30. The
optical element 30 and the optical fibers 20 are optically
connected via the mirror 36. In this example, the edges of both
ends of the mirror 36 are defined by the inside lines of the
wirings 12, so that the mirror 36 is positioned by the wirings
12.
[0352] In the configuration shown in FIG. 19, stoppers 37 for the
optical fibers 20 are formed. In this example, as shown in FIG. 6,
end faces of the optical fibers 20 are cut into 45.degree., so that
optical connection between the optical fibers 20 and the optical
element 30 is achieved. The stoppers 37 are formed under the
optical element 30, and arranged in the grooves 22, for example.
The stoppers 37 permit efficient arrangement of the optical fibers
20.
[0353] As shown in FIG. 20, the wirings to be connected
electrically to the optical element 30 need not only be the wirings
12 extended from the optical fiber 20 side, but may also be the
wirings 12' extended from the opposite direction. The wirings 12'
are circuit patterns fabricated with the same positional precision
as the wirings 12. In the example shown in FIG. 20, lands 28 are
formed at the tips of the wirings 12', so that the optical element
30 is mounted on the lands 28.
[0354] Embodiments 1 and 2 have been described for the examples of
an optical transmission channel board employing optical fibers.
However, in place of optical fibers, optical waveguides composed of
plane waveguides (PLCs) may be used as optical transmission
channels 20. When optical waveguides composed of plane waveguides
(PLCs) are used as optical transmission channels, a plurality of
grooves formed on the plane waveguide (PLC) side are engaged with a
plurality of the grooves 22. This improves manufacturability. When
wirings 13 are formed on the plane waveguide (PLC) side, or when
the optical element 30 is mounted on the plane waveguide (PLC)
side, fabrication and the centering problem are further simplified.
Nevertheless, from the perspective of cost, the use of optical
fibers based on the fabrication method of the present embodiment
can be advantageous over the use of the optical waveguides composed
of plane waveguides (PLCs).
[0355] The present invention has been described above with
reference to a preferred embodiment. This description is not a
limitation, and hence various modifications can be made.
[0356] As described above, the fabrication method for a board with
built-in optical transmission channel according to the present
invention comprises: a step (a) of patterning a metal layer formed
on a supporting board and thereby forming circuit patterns
including a plurality of wirings; a step (b) of arranging an
optical transmission channel between wirings of said circuit
patterns; a step (c) of depositing a material containing resin onto
said supporting board in such a manner that said circuit pattern
and said optical transmission channel are covered; and a step (d)
of removing said supporting board.
[0357] In a preferred embodiment, said step (a) includes: a step of
preparing a supporting board and a metal layer formed on said
supporting board; and a step of etching said metal layer using a
mask corresponding to the circuit patterns.
[0358] In an example, a step of forming walls used as a guide for
arranging an optical transmission channel, in at least a part of
said circuit patterns is performed before said step (b).
[0359] In a preferred embodiment, at least a part of said walls is
composed of metal.
[0360] In a preferred embodiment, at least a part of said walls is
formed by sputtering.
[0361] In a preferred embodiment, said optical transmission channel
is an optical fiber. The sum of the thickness values of said wall
and said wiring located under the wiring is greater than the radius
of said optical fiber.
[0362] In a preferred embodiment, in said step (b), said optical
transmission channel is arranged such as to contact with said
supporting board.
[0363] In a preferred embodiment, said optical transmission channel
is arranged between said wirings so as to contact with said
walls.
[0364] In an example, said material containing resin is preferably
a composite material containing resin and inorganic filler.
[0365] In an embodiment, said optical transmission channel is an
optical fiber. In said step (c), said material containing resin is
deposited in a thickness of three times or more of the radius of
said optical fiber.
[0366] In an embodiment, after said step (c) and before or after
said step (d), the deposition film composed of said material is
reversed in said step (c).
[0367] In a preferred embodiment, after said step (d), the
uppermost portion of said optical transmission channel is
substantially in plane with the upper surface of said circuit
patterns.
[0368] In a preferred embodiment, a step of mounting electronic
components electrically connected to said circuit pattern is
further performed after said step (d).
[0369] In a preferred embodiment, at least one of said the
electronic components is at least one optical element selected from
a laser element and a photo receiving element. Said optical element
is arranged above said optical transmission channel, or arranged
such as to substantially contact with said optical transmission
channel.
[0370] In an example, a board with built-in optical transmission
channel according to the present invention comprises: a board
composed of a material containing resin; circuit patterns formed on
said board and including a plurality of wirings; and an optical
transmission channel arranged between said wirings of said circuit
patterns so as to substantially contact with said wirings when
viewed from the above of said board.
[0371] In a preferred embodiment, the uppermost portion of said
optical transmission channel is substantially in plane with the
upper surface of said circuit patterns.
[0372] In a preferred embodiment, a portion lower than the upper
surface of said board is present in at least a part of the upper
surface of said circuit patterns.
[0373] In a preferred embodiment, the entirety of the upper surface
of said circuit patterns is lower than the upper surface of said
board.
[0374] In a preferred embodiment, said portion lower than the upper
surface of said board in said circuit patterns is a land
section.
[0375] In an example, said optical transmission channel may have a
Y branching section arranged in said board.
[0376] In a preferred embodiment, a plurality of said optical
transmission channels are provided, while said board is further
provided with: a semiconductor element at least selected from a
memory LSI and a logic LSI; a laser element; and a photo receiving
element.
[0377] In a preferred embodiment, said optical transmission channel
is an optical fiber.
[0378] In an embodiment, an optical module comprises: a board
composed of a material containing resin; circuit patterns formed on
said board and including a plurality of wirings; and an optical
waveguide arranged between the wirings of said circuit patterns so
as to substantially contact with said wirings when viewed from the
above of said board.
[0379] In an example, a data processing apparatus according to the
present invention comprises: an above-mentioned board with built-in
optical transmission channel; and a semiconductor element mounted
on said board with built-in optical transmission channel.
Embodiment 3
[0380] FIG. 21 is a perspective view schematically showing the
configuration of an optical transmission channel board according to
Embodiment 3.
[0381] As shown in FIG. 21, the optical transmission channel board
200 of Embodiment 3 comprises: a board 110 composed of a material
containing resin; a plurality of grooves 122 formed in the surface
of the board 110; and optical fibers 120 a portion of each of which
is embedded in each groove 122. Circuit patterns (not shown)
including a plurality of wirings are formed on the board 110. In
the configuration of Embodiment 3, apart of the circuit patterns
and the grooves 122 into which the optical fibers 120 are embedded
are formed in self-conformity with each other. This self-conformal
formation is described later in further detail in a fabrication
method for the optical transmission channel board 200.
[0382] The optical transmission channels of the present invention
are optical fibers 120 in Embodiment 3, and hence Embodiment 3 is
described for the case of optical fibers. However, an "optical
transmission channel" in the present specification indicates a
line-shaped member capable of transmitting light.
[0383] In Embodiment 3, the board 110 is composed of a composite
material containing resin and inorganic filler. The depth of the
groove 122 formed in the board 110 is 1 .mu.m through 5 mm or the
like. Thickness of the board 110 is 1/2 or more of the radius of
the optical fiber 120. An optical element 130 is mounted on the
optical transmission channel board 100 shown in FIG. 21. The
optical element 130 is optically connected to the optical fibers
120. The optical element 130 is electrically connected to a part of
the circuit patterns (not shown) with reference to a marker (an
optical element marker, hereafter) which is formed in conformity
with the grooves 122 serving as mounting sections for the optical
fibers 120 and which is used for positioning the optical element.
The optical element marker is not illustrated, but typically
composed of positioning reference planes 1103a, 1103b, and 1103c
shown in FIG. 50 illustrating the prior art.
[0384] The optical element 130 is a laser element such as a
semiconductor laser, or a photo receiving element such as a
photo-diode. In Embodiment 3, the optical element 130 is arranged
above the optical fibers 120. The phrase "arranged above an optical
transmission channel" according to the present invention includes
the state "arranged such as to substantially contact with the top
of an optical transmission channel".
[0385] In Embodiment 3, an example of the electrically conductive
material according to the present invention which constitutes the
board 110 serving as an example of the retention board of the
present invention is a composite material containing resin (such as
a thermosetting resin and a thermoplastic resin) and inorganic
filler. In this embodiment, a thermosetting resin is used as the
resin for the composite material. Without using inorganic filler,
the board 110 may be composed solely of thermosetting resin. The
thermosetting resin is an epoxy resin or the like. When added, the
inorganic filler is Al.sub.2O.sub.3, SiO.sub.2, MgO, BN, AlN, or
the like. The addition of inorganic filler permits the control of
various physical properties (such as the thermal expansion
coefficient). Thus, the board 10 is preferably composed of such a
composite material containing inorganic filler. In Embodiment 3,
inorganic filler of 100 weight units or more (preferably 140-180
weight units) is contained relative to the thermosetting resin of
100 weight units.
[0386] The role of inorganic filler is as follows. When
Al.sub.2O.sub.3, BN, or AlN is added as inorganic filler, the
thermal conductivity of the board 10 is improved. Further, when an
appropriate inorganic filler is selected, the thermal expansion
coefficient can be adjusted. In case that the thermal expansion
coefficient is rather increased by the resin component, the
addition of SiO.sub.2, AlN, or the like can decrease the thermal
expansion coefficient. In an appropriate case, when MgO is added,
the thermal conductivity is improved while the thermal expansion
coefficient is increased. Further, when Si.sub.2O (especially,
amorphous SiO.sub.2) is added, the thermal expansion coefficient is
decreased while the dielectric constant is reduced.
[0387] A fabrication method for an optical transmission channel
board according to Embodiment 3 is described below.
[0388] The optical transmission channel board 200 of Embodiment 3
is fabricated using a transfer method. More specifically, a metal
layer formed on a supporting board is patterned so that circuit
patterns are formed that include: wirings for constituting grooves;
wirings used as an electric circuit; and wirings used as an optical
element marker. Then, a material containing resin is deposited on
the supporting board so as to cover the circuit patterns. The
material including this deposited resin constitutes a board
110.
[0389] Then, the supporting board is removed so that the circuit
patterns are exposed on the surface of the board 110. Then, a part
of the circuit patterns (wirings for constituting the grooves) are
removed so that the grooves 122 are formed in the surface of the
board 110. Then, optical fibers 120 are arranged into the grooves
122. After that, an optical element 130 is mounted with reference
to the optical element marker so that an optical transmission
channel board 200 of Embodiment 3 is obtained.
[0390] As such, the circuit patterns 115 and the grooves 122 are
formed in conformity. Further, a part of the circuit patterns are
used as an optical element marker. This configuration permits
automatic position adjustment with the optical fibers 120 optically
connected to the optical element 130.
[0391] Thus, in comparison with the prior art case of FIG. 50 where
the circuit patterns (including the position reference planes
1103a, 1103b, and 1103c) and the mounting sections (guide grooves
1104) for optical fibers are formed separately, alignment is
achieved with self-conformity in Embodiment 3.
[0392] This resolves the problem of centering, and permits optical
connection between the optical element 30 and the optical fibers
20. In a possible case that a centering process is to be performed
in the optical transmission channel board 200 of Embodiment 3 in
order to further improve the optical connection, rough centering
has already been achieved with a precision better than that of the
prior art configuration. Thus, fine centering solely is
sufficient.
[0393] The optical element 130 is a semiconductor laser or the
like, and is arranged above the optical fibers 120 in Embodiment 3.
The optical element 130 may be a photo receiving element (such as a
photo-diode). In Embodiment 3, the optical element 130 is connected
to the wirings 113 via connection members (solder or bumps) 132. In
the example shown in FIG. 24, the optical element 130 is solely
mounted on the board 110. However, other electronic components
(such as semiconductor elements) may be mounted on the board
110.
[0394] The above-mentioned fabrication method for an optical
transmission channel board is described below in further detail
with reference to FIGS. 22-24.
[0395] First, as shown in FIG. 22(a), a carrier sheet (transfer
formation material) 140 on which a metal layer 142 is formed is
prepared. The metal layer 142 is composed of copper or the like.
The carrier sheet 140 serving as an example of the supporting board
of the present invention is composed of a metallic foil (a copper
or aluminum foil), a resin sheet, or the like.
[0396] Then, as shown in FIG. 22(b), a mask 150 corresponding to
the circuit patterns is arranged above the metal layer 142. Then,
the metal layer 142 is etched. When the mask 150 is removed after
the etching, circuit patterns 115 are formed as shown in FIG.
22(c). The circuit patterns 115 include: wiring portions used as a
plurality of the wirings 113; groove portions (groove-use wirings)
112 to be used as the grooves 122; and wiring portions serving as
an optical element marker (optical element marker wirings).
[0397] Then, as shown in FIG. 22(d), a material containing resin is
deposited on the carrier sheet (supporting board) 140 so as to
cover the circuit patterns 115. This deposited material containing
resin constitutes a board 110 serving as an example of a retention
board of the present invention.
[0398] Then, as shown in FIG. 23(a), the board 110 composed of
resin is reversed. Then, the carrier sheet 140 is removed. As a
result, the circuit patterns 115 including the groove-use wirings
112, the wirings 113, and the optical element marker wirings are
exposed on the surface of the board 110. At this time, the step of
embedding the circuit patterns 115 in the board 110 which
corresponds to a first step of the present invention is completed.
Then, the circuit patterns 115 on the carrier sheet 140 are
separated so that the transfer is completed. The board 110 may be
reversed after the removal of the carrier sheet 140.
[0399] Then, as shown in FIG. 23(b), a mask 151 corresponding to
the groove-use wirings 112 is arranged on the board 110. Then, the
groove-use wirings 112 are etched and removed so that the grooves
122 are formed in the surface of the board 110 as shown in FIG.
23(c). At that time, the wirings 113 and the optical element marker
wirings are covered by the mask 151. Thus, the groove-use wirings
112 are solely removed during the etching.
[0400] Then, when optical fibers 120 are arranged into the grooves
122 as shown in FIG. 23(d), an optical transmission channel board
200 of Embodiment 3 is obtained.
[0401] Then, as shown in FIG. 24, an electronic component (optical
element) 130 is mounted on the wirings 113 exposed on the surface
of the board 110, with reference to the optical element marker. As
a result, an optical module is obtained. The optical element 130
electrically connected to the wirings 113 can be optically
connected to the optical fibers 120 fixed in the grooves 122.
[0402] As described above, in the optical transmission channel
board 200 of Embodiment 3, the wirings 112 constituting the grooves
22 for accommodating the optical fibers 120 and the wirings used as
an optical element marker are fabricated using the same mask, as
shown in FIGS. 22(b) and 22(c). Thus, the discrepancy between the
optical element 130 and the optical fibers 120 can easily be
suppressed within the tolerance.
[0403] In contrast, in the prior art configuration, the formation
of an optical element marker formed together with the circuit
patterns has been independent of the formation of optical fiber
mounting sections. Thus, tolerance discrepancies in these processes
have been affected each other, and hence the discrepancy between an
optical element 130 and optical fibers 120 has been difficult to be
suppressed within the tolerance. Thus, a centering was
necessary.
[0404] On the other hand, in Embodiment 3, the circuit patterns 115
including the groove-use wirings 112 (grooves 122 used as the
mounting sections for the optical fibers 120) and the optical
element marker are formed using the single mask 150. Thus,
conformity is kept through a series of the fabrication processes.
Accordingly, what is necessary is to consider solely the tolerance
discrepancy in the circuit patterns. Thus, the discrepancy between
the optical element 130 and the optical fibers 120 can easily be
suppressed within the tolerance.
[0405] The optical element marker of Embodiment 3 is a marker for
positioning the optical element 130. However, this marker may serve
also as the wirings used as an electric circuit.
[0406] A part of circuit patterns used as an electric circuit
according to the present invention corresponds to the wirings 113
of Embodiment 3. A part of circuit patterns used as an optical
transmission channel marker according to the present invention
corresponds to the groove-use wirings 112 of Embodiment 3. However,
these wirings may serve also as an optical element marker for
positioning an optical element.
[0407] A first step of the present invention corresponds to the
step shown in FIGS. 22(a)-22(d), for example. A second step of the
present invention corresponds to the step shown in FIGS.
23(b)-23(c), for example. A third step of the present invention
corresponds to the step shown in FIG. 23(d), for example. A fourth
step of the present invention corresponds to the step shown in FIG.
24, for example. As shown in FIG. 22(a)-22(d), the first step has
been described for the case that resin is deposited such as to
cover the circuit patterns 115 fabricated on the supporting board
140 by etching, and that the supporting board 140 is then removed.
However, the first step of the present invention is not limited to
this. That is, another process may be used as long as wiring
patterns can be embedded such as to form the groove-use wirings 112
and a plurality of the wirings 113 on the board 110.
[0408] A mask corresponding to a part of circuit patterns used as
an optical transmission channel marker of the present invention
corresponds to the mask 151 shown in FIG. 23(b) of Embodiment 3,
for example. The mask 151 covers the entire surfaces of the board
110 and a plurality of the wirings 113 except for the portion
serving as the groove-use wirings 112. However, it is sufficient
that the portion of a plurality of the wirings 113 is covered. That
is, a part of the surface of the board 110 need not be covered.
[0409] FIG. 25 is a diagram illustrating the detail of a
configuration of Embodiment 3. Part of the optical fiber 120 is
located in the groove 122. The height h of the optical fiber 120
relative to the board 110 surface is 90 .mu.m. The depth d of the
groove 122 is 32 .mu.m. The width w of the groove 122 is 111 .mu.m.
Depending on the dimensions and the type of the optical fibers 120,
dimensions of 1 .mu.m can be sufficient for the attaching of the
optical fibers 120 in some cases. According to the configuration of
Embodiment 3, the optical fibers 120 are embedded (built) in the
board 110. Thus, the optical fibers 120 can easily be arranged by
using the grooves 122 as a guide, rather than by placing the
optical fibers 120 on the board plane.
[0410] The optical element 130 and the optical fiber 120 can be
optically connected, for example, as shown in the schematic
sectional view of FIG. 26. That is, as shown in FIG. 26, a
reflection surface (inclined surface) 111 is formed in a part of
the board 110. Then, optical connection by light (optical signals)
125 is achieved between the optical element 130 and the optical
fiber 120 via the reflection surface 111. In an example, the
reflection surface 111 is obtained by fabricating an inclined
surface in the board 110 and then forming a metal layer (such as an
Au layer) on the surface of the inclined surface. Alternatively, an
optical component (mirror) having a reflection surface 111 may be
placed on the board 110.
[0411] Alternatively, as shown in the schematic sectional view of
FIG. 27, an end face 121 of the optical fiber 120 may be cut aslant
(such as a 45.degree. cut) so that light 125 should be reflected in
the end face 121. As a result, optical connection is achieved
between the optical element 130 and the optical fiber 120. In the
configuration shown in FIGS. 26 and 27, a transparent medium may be
present in the path of the light 125 between the optical element
130 and the optical fiber 120. The transparent medium may be air,
glass, transparent resin, or the like. Similarly to Embodiments 1
and 2, the transparent resin indicates a material permitting
optical connection between the optical element 130 and the optical
fiber 120, and capable of transmitting light of a wavelength of 850
nm, 1330 nm, and 1550 nm or the like. More specifically, the
transparent resin may be polyimide, epoxy aramid, or the like.
Alternatively, an optical component (such as a lens) may be
arranged between the optical element 130 and the optical fiber
120.
[0412] When the optical element 130 is mounted on a portion
corresponding to the wirings 113 of the circuit patterns, pad
sections maybe formed in the wirings 113 so that the pad sections
may be connected to the element terminals of the optical element
130 by wire bonding. Nevertheless, such wire bonding connection is
disadvantageous in high speed characteristics. Thus, as an example
shown in FIG. 24, the connection between the optical element 130
and the wirings 113 is preferably realized by flip chip mounting or
the like using connection members (such as bumps and solder balls)
132. In this case, lands are formed in the portions of the wirings
113 with which the connection members 132 contact.
[0413] As shown in FIG. 28, the optical fibers 120 maybe optically
connected to optical elements within an MCM (multi-chip module)
135, in place of a single optical element 130. As shown in FIG. 28,
a plurality of electronic components 133a, 133b, and 133c are
mounted on an interposer 134 so that an MCM 135 is constructed. At
least one of the electronic components 133a, 133b, and 133c is an
optical element. All the electronic components 133a, 133b, and 133c
may be laser elements (semiconductor lasers), or may be photo
receiving elements (photo-diodes). Alternatively, they may be a
combination of laser elements and photo receiving elements. In an
example, an opening is formed in a part of the interposer 134
corresponding to the optical path between the optical elements and
the optical fibers. An optical component (such as a lens) may be
arranged in the position of the opening. The electronic components
133a and 133b composed of optical elements may be mounted on the
back side of the interposer 134.
[0414] In the prior art, position adjustment has been necessary
between the grooves 122, the interposer 134, and the electronic
components 133a, 133b, and 133c corresponding to the optical fibers
120. However, according to the fabrication method of Embodiment 3,
the positions of the optical element marker and the grooves 122 are
formed in self-conformity using a single mask. This simplifies the
position adjustment between the interposer 134 on the wirings 113
and the optical fibers 120 in the grooves 122, and hence simplifies
the centering process in comparison with the prior art.
[0415] In the optical transmission channel board 2000 of Embodiment
3, the circuit patterns 115 including the wirings 113 with the
groove-use wirings 112 are easily formed by a transfer method.
Thus, even electronic components other than optical elements
(semiconductor elements) can be mounted similarly to the case of a
typical printed circuit board. FIG. 29 shows an optical module in
which electronic components 131 (131a, 131b, 131c, 131d, and 131e)
in addition to the optical elements 130a and 130b are mounted on an
optical transmission channel board 200. The optical module shown in
FIG. 29 can be used as a data processing apparatus. This module is
described below in further detail.
[0416] The optical element 130a is a laser element, and may be a
vertical-cavity surface-emitting laser (VCSEL). On the other hand,
the optical element 130b is a photo receiving element, and may be a
photo-diode unit having a plurality of photo-receiving sections.
For the simplicity of understanding the configuration of Embodiment
3, grooves 122 are shown without optical fibers 120 to be optically
connected to the optical element 130a.
[0417] A driver IC 131a is connected to the optical element 130a
composed of a laser element. The driver IC 131a is connected to an
LSI chip (such as a logic LSI like an image processing LSI) 131b.
The LSI chip 131b is connected to a memory chip 131c. An optical
element 130b composed of a photo receiving element is connected to
the LSI chip 131b via an amplifier (preamplifier) 131d and an
amplifier 131e. These electronic components 131 are mutually
connected through the wirings 113 in the circuit patterns 115.
[0418] The problem of centering is resolved by the configuration of
the groove-use wirings 112 for accommodating the optical fibers 120
and the optical element marker wirings. Thus, other wirings may be
formed on the board 110 separately in a step other than a transfer
process (for example, in an independent and later step). However,
from the perspective of fabrication procedure, cost, and the like,
it is efficient to fabricate other wirings not relevant to the
optical element 130 in the same step as that of the circuit
patterns 115, as in the fabrication method of Embodiment 3.
[0419] The optical module (data processing apparatus) shown in FIG.
29 can perform optical transmission through the optical fibers 120.
Thus, mass data can be transmitted at a high speed. Further, this
module fabricated by the method of Embodiment 3 has a low
fabrication cost.
[0420] That is, in the prior art, the optical element markers and
the optical fiber mounting sections have been fabricated in
separate steps. This has caused a larger tolerance discrepancy and
hence a higher fabrication cost. In contrast, in the present
invention, the circuit patterns 115 including the groove-use
wirings 112, the wirings 113, and the optical element marker
wirings are integrally fabricated first. Then, the grooves 122 used
as an optical fiber mounting sections are formed from the
groove-use wirings 112. This reduces the fabrication cost. Thus,
the cost can be reduced in optical modules presently used in
optical communications (such as the Internet and telephone). This
accelerates the spread of such optical modules.
[0421] Further, the cost reduction permits the use of economical
optical transmission in within-the-board transmission (level 2) in
the communication system apparatus 3000 shown in FIG. 52. This
improves the speed of within-the-board transmission. As such, the
present invention is applicable to the bookshelf type communication
system apparatus 3000 shown in FIG. 52. Further, the optical
transmission channel board or optical module 1000 of the present
invention may be used as a main apparatus such as a next-generation
high performance optical I/O module and a data processing apparatus
(like an image processing apparatus)
Embodiment 4
[0422] Further features and further modifications of the optical
transmission channel board 200 of Embodiment 3 are described below
with reference to other drawings.
[0423] In Embodiment 3 described above, the grooves 122 have been
formed by the groove-use wirings 112. However, the grooves 122 may
be fabricated by etching a part of a board 110 in the state shown
in FIG. 23. Nevertheless, when the grooves 122 are solely
fabricated, the grooves 122 serving as optical fiber mounting
sections and wirings 113 on which the optical element 130 is
mounted are fabricated in separate parts.
[0424] Thus, in place of the mask 151 shown in FIG. 23(b) of
Embodiment 3, a mask is used in which an opening is formed in the
middle of the groove-use wiring 112. That is, in order that the
above-mentioned fabrication in separate parts should be avoided, as
shown in FIG. 30(a), it is preferable that the portion between a
wiring 112' and a wiring 112' corresponding to the groove-use
wiring 112 included in the circuit patterns 115 of Embodiment 3 is
removed so that a groove 122 is formed. In this case, the groove
122 is formed in conformity with the circuit patterns 115.
[0425] A part of a board portion between adjacent ones of said
electrode patterns of the present invention is, for example, the
portion of the board 110 between the wiring 112' and the wiring
112' contained in the circuit patterns 115 shown in FIG. 30(a).
[0426] The optical element marker may serve also as the wirings
used as an electric circuit, and further may serve also as the
wirings used as an optical transmission channel marker.
[0427] A part of the circuit patterns used as an optical
transmission channel marker of the present invention corresponds to
the wirings 112' of Embodiment 4. The wirings 112' are lines for
defining the groove 122. Unlike the groove-use wirings 112 (see
FIG. 23) which disappear later, the wirings 112'remain also in the
optical transmission channel board 200 serving as an end product.
Thus, the wirings 112' may serve as wirings for a signal or for
power supply, that is, as wirings used as an electric circuit of
the present invention. When an optical fiber 120 is mounted, the
configuration shown in FIG. 30(b) is obtained. The optical fiber
120 is an insulator. Thus, even when the optical fiber 120 contacts
with the wirings 112', no problem arises in particular.
[0428] The mask corresponding to a part of a retention board of the
present invention is the mask used for removing the portion between
the wirings 112' of Embodiment 4, for example. The portions of the
wirings 112' and the wirings 113 need not be covered. That is,
sufficient is such a mask that the resin portion between the
wirings 112' is open and that other resin portions are covered.
[0429] In Embodiment 4, positioning of the optical fiber 120 is
regulated by the edge portions of the two wirings 112' on the
surface side of the board 110. Thus, as shown in FIG. 30(c), the
depth of the groove 122 may be deeper than the embedding position
of the wirings 112'. That is, the optical fiber 120 need not
contact with the bottom surface of the groove 122.
[0430] As shown in FIG. 30(d), the depth of the groove 122 and the
spacing between the wirings 112' may be equal to the diameter of
the optical fiber 120 so that the optical fiber 120 should not
protrude above the surface of the board 110. The depth of the
groove 122 may be further deeper.
[0431] Also in Embodiment 3, the size of the groove-use wirings 112
may be changed as described above. In these configurations, the
optical fiber 120 does not contact with the bottom surface of the
groove 122, or alternatively the optical fiber 120 does not
protrude above the surface of the board 110.
[0432] As shown in FIG. 31(a), the shape of the groove 122
described in Embodiments 3 and 4 may be changed so that the groove
edges form a taper. More specifically, the angle .theta. between a
side (upper surface) 110a of the board 110 is not limited to 900,
and may be an obtuse angle. In order that the groove 122 having
obtuse angles .theta., etching is performed from an acute angle
direction, for example. When the edges of the groove 122 form a
taper as shown in FIG. 31(b), the accuracy in the position
adjustment of the center line 127 of the optical fiber 120 is
improved by the inclined surfaces of the walls 122a.
[0433] A Y branching section 123 as shown in FIG. 32 may be formed
in the optical fiber 20 on the optical transmission channel board
200 of Embodiments 3 and 4. The use of such an optical fiber 120
having a Y branching section 123 provides an optical module
(optical transmission channel board) suitable for wavelength
multiplexing. When such an optical fiber 120 having a Y branching
section 123 is used, it is sufficient that the groove 122 is formed
into a form corresponding thereto, so that the optical fiber 120 is
appropriately retained by the groove 122.
[0434] As for the optical connection between the optical element
130 and the optical fiber 120, a mirror having a reflection surf
ace 111 (see FIG. 26) may be arranged under the optical element 130
so that optical connection between the optical element 130 and the
optical fiber 120 may be performed using the mirror. A stopper for
the optical fiber 120 maybe arranged so as to position the optical
fiber 120. The stopper is arranged under the optical element 130,
and may be arrange in the groove 122, for example.
[0435] An optical element of the present invention corresponds to
the optical element 130 in Embodiments 3 and 4, and is arranged
above the optical fiber 120 as shown in FIG. 26. In case that this
optical element is a light emitting element, the optical element
130 is a surface emitting type element (light is emitted from its
bottom surface). In place of this surface emitting type element, an
edge emitting type element (light is emitted from the end face of
the optical element) may be arranged in a direction extended from
of the optical fiber 120 (substantially provided on the same plane
on which the optical fiber is provided).
[0436] FIG. 33 is a side view of an optical transmission channel
board employing an edge emitting type element 160. As shown in FIG.
33, in order that optical connection is established for the edge
emitting type element, the depth of the groove for mounting the
optical fiber 120 needs to be adjusted such as to match with the
height of the edge emitting type element 160. In a prior art
optical transmission channel board employing an edge emitting type
element, position adjustment has been necessary in the depth
direction (perpendicular to the plane of the board 110) and in a
direction parallel to the plane of the board 110. However, in the
fabrication method of Embodiments 3 and 4, position adjustment in
the parallel direction is almost unnecessary. This simplifies the
centering process, and hence reduces the fabrication cost in
comparison with the prior art.
[0437] Embodiments 3 and 4 have been described for the case that
the optical transmission channel board employs optical fibers.
However, in place of the optical fibers 120, optical waveguides
composed of plane waveguides (PLCs) may be used as optical
transmission channels. When optical waveguides composed of plane
wave guides (PLCs) are used as optical transmission channels, a
plurality of grooves formed on the plane waveguide (PLC) side are
engaged with a plurality of the grooves 122. This improves
manufacturability. When wirings 13 are formed on the plane
waveguide (PLC) side, or when the optical element 130 is mounted on
the plane waveguide (PLC) side, fabrication and the centering
problem are further simplified. Nevertheless, from the perspective
of cost, the use of optical fibers based on the fabrication method
of Embodiments 3 and 4 can be advantageous over the use of the
optical waveguides composed of plane waveguides (PLCs).
[0438] The present invention has been described above with
reference to a preferred embodiment. This description is not a
limitation, and hence various modifications can be made. For
example, in the above-mentioned embodiment, the circuit patterns
for arranging the optical element 130 shown in FIG. 24 have also
been embedded. However, the step of embedding the circuit patterns
for the optical element marker may be omitted.
[0439] As described above, a fabrication method for an optical
transmission channel board according to the present invention
comprises: a step (a) of patterning a metal layer formed on a
supporting board and thereby forming circuit patterns including a
plurality of wirings; a step (b) of depositing a material
containing resin on said supporting board so as to cover said
circuit patterns; a step (c) of removing said supporting board and
thereby exposing said circuit patterns in the surface of the resin
film composed of said material containing resin; a step (d) of
removing a part of said circuit patterns and thereby forming a
groove in the surface of said resin film; and a step (e) of
arranging an optical transmission channel into said groove.
[0440] In a preferred embodiment, said step (a) comprises: a step
of preparing a supporting board and a metal layer formed on said
supporting board; and a step of etching said metal layer using a
mask corresponding to the patterns including said circuit
patterns.
[0441] In a preferred embodiment, said circuit patterns include: a
wiring portion serving as a plurality of said wirings; and a groove
portion used as said groove.
[0442] In an example, said material containing resin is preferably
a composite material containing resin and inorganic filler.
[0443] In an embodiment, the depth of said groove is 1 .mu.m or
more and 5 mm or less.
[0444] In an embodiment, in said step (b), said material containing
resin is deposited in 1/2 or more of the thickness of the radius of
said optical transmission channel.
[0445] In a preferred embodiment, in said step (d), said groove is
formed such that the edges of said groove form a taper.
[0446] In a preferred embodiment, a step of mounting electronic
components electrically connected to said circuit pattern is
further performed after said step (e).
[0447] In a preferred embodiment, at least one of said the
electronic components is at least one optical element of a laser
element and a photo receiving element. Said optical element is
arranged on or above said optical transmission channel.
[0448] In an embodiment, another fabrication method for an optical
transmission channel board according to the present invention
comprises: a step (a) of patterning a metal layer formed on a
supporting board and thereby forming circuit patterns including a
plurality of wirings; a step (b) of depositing a material
containing resin on said supporting board such as to cover said
circuit pattern; a step (c) of removing said supporting board and
thereby exposing said circuit pattern in the surface of the resin
film composed of said material containing resin; a step (d) of
removing the resin present between the wirings of said circuit
patterns and thereby forming a groove in the surface of said resin
film; and a step (e) of arranging an optical transmission channel
into said groove.
[0449] In a preferred embodiment, said optical transmission channel
is an optical fiber.
[0450] In an embodiment, an optical transmission channel board
according to the present invention comprises: a board composed of a
material containing resin; and circuit patterns formed on said
board and including a plurality of wirings. A plurality of grooves
are formed in the surface of said board. A portion of an optical
transmission channel is embedded in each of a plurality of said
grooves.
[0451] In a preferred embodiment, said grooves in which said
optical transmission channels are embedded and a part of said
circuit patterns are formed in self-conformity with each other.
[0452] In a preferred embodiment, said optical transmission channel
has a Y branching section arranged in said groove.
[0453] In a preferred embodiment, the edges of said groove form a
taper.
[0454] In a preferred embodiment, said board is provided with: a
semiconductor element at least selected from a memory LSI and a
logic LSI; a laser element; and a photo receiving element.
[0455] In a preferred embodiment, said optical transmission channel
is an optical fiber.
[0456] A data processing apparatus according to the present
invention comprises: an above-mentioned optical transmission
channel board; and a semiconductor element mounted on said optical
transmission channel board.
Embodiment 5
[0457] A board with built-in optical transmission channel 300
according to Embodiment 5 of the present invention is described
below with reference to FIGS. 34-39. FIG. 34 is a perspective view
schematically showing the configuration of the board with built-in
optical transmission channel 300 of Embodiment 5.
[0458] The board with built-in optical transmission channel 300 of
Embodiment 5 comprises: a board 210; circuit patterns 215 including
a plurality of wirings 212 formed on the board 210; and a plurality
of optical transmission channels 220 (220a, 220b) embedded in the
board 210. The optical transmission channel 220a and the optical
transmission channel 220b are arranged in different hierarchies in
the depth direction 219 of the board 210. Thus, the optical
transmission channels 220 are in multi-layer arrangement. An
optical element 230 is arranged above the end portion of each
optical transmission channel 220 (220a, 220b). Apart (wirings 212)
of the circuit patterns 215 formed on the upper surface of the
board 210 are electrically connected to the optical element 230. A
positioning marker (not shown) for the optical element 230 similar
to the positioning reference planes 103a-103c described in FIG. 50
is formed on the board 210. The circuit patterns 215 includes also
the positioning marker. The thickness direction of the board
according to the present invention corresponds to the depth
direction 219 of the board 210, for example.
[0459] In Embodiment 5, grooves 222 are formed between the wirings
212, while optical transmission channels 220 are arranged in the
grooves 222. In the example shown in FIG. 34, the grooves 222 are
shown that correspond to the optical fibers (optical waveguides)
220a in the upper row. However, other grooves may also be present
that correspond to the optical fibers (optical waveguides) 220b in
the lower row. This example shows a two stage configuration (220a,
220b). However, a three or more stage configuration may be used.
The optical transmission channels 220 in Embodiment 5 are optical
fibers, and hence Embodiment 5 is described for the case of optical
fibers.
[0460] When viewed from the above of the board 210 (viewed from the
normal direction of the board 210) 212, the optical fibers 220 are
arranged between the wirings 212 and adhered with adhesives or the
like, such as to contact with the wirings 212. As described above,
in Embodiment 5, the optical fibers 220 are arranged in the grooves
222 formed between the wirings 212, and are built in the board 210.
In other words, the grooves 222 formed between the wirings 212
serves as mounting sections for the optical fibers 220. In
Embodiment 5, the uppermost portions of the optical fibers 220 are
substantially in plane with the upper surface (that is, the upper
surface of the wirings 212) of the circuit patterns 215.
[0461] An optical element 230 is mounted on the board with built-in
optical transmission channel (board with built-in optical fiber)
300 shown in FIG. 34. This optical element is electrically
connected to the wirings 212, and optically connected to the
optical fibers 220 (220a, 220b). In Embodiment 5, the optical
element 230 is arranged above the optical fibers 220 (220a, 220b),
or alternatively such as to substantially contact with the optical
fibers 220a in the uppermost row.
[0462] The optical element 230 is a laser element such as a
semiconductor laser, or a photo receiving element such as a
photo-diode. In this example, the optical element 230 is a
vertical-cavity surface-emitting laser (VCSEL). The light-emitting
surface of the optical element (VCSEL) 230 is opposing to the
surface of the board 210. The light-emitting surface has a
plurality of light emission points. In case that the optical
element 230 is a photo receiving element, the photo receiving
surface of the optical element 230 is opposing to the surface of
the board 210. The photo receiving surface has a plurality of photo
reception points.
[0463] The board 210 is composed of a material containing resin. In
Embodiment 5, the material constituting the board 210 is composed
of a composite material containing resin (such as a thermosetting
resin and a thermoplastic resin) and inorganic filler. In this
embodiment, a thermosetting resin is used as the resin for the
composite material.
[0464] Without using inorganic filler, the board 210 may be
composed solely of thermosetting resin. The thermosetting resin is
an epoxy resin or the like. When added, the inorganic filler is
Al.sub.2O.sub.3, SiO.sub.2, MgO, BN, AlN, or the like. The addition
of inorganic filler permits the control of various physical
properties (such as the thermal expansion coefficient). Thus, the
board 210 is preferably composed of such a composite material
containing inorganic filler. In Embodiment 5, inorganic filler of
100 weight units or more (preferably 140-180 weight units) is
contained relative to the thermosetting resin of 100 weight
units.
[0465] The role of inorganic filler is as follows. When
Al.sub.2O.sub.3, BN, or AlN is added as inorganic filler, the
thermal conductivity of the board 210 is improved.
[0466] Further, when an appropriate inorganic filler is selected,
the thermal expansion coefficient can be adjusted. In case that the
thermal expansion coefficient is rather increased by the resin
component, the addition of SiO.sub.2, AlN, or the like can decrease
the thermal expansion coefficient.
[0467] In an appropriate case, when MgO is added, the thermal
conductivity is improved while the thermal expansion coefficient is
increased.
[0468] Further, when Si.sub.2O (especially, amorphous SiO.sub.2) is
added, the thermal expansion coefficient is decreased while the
dielectric constant is reduced.
[0469] FIG. 35 is a sectional view schematically showing an example
of the configuration of the board with built-in optical
transmission channel (board with built-in optical fiber) 300 of
Embodiment 5.
[0470] The board with built-in optical transmission channel 300
shown in FIG. 35 is formed from a board 210 obtained by stacking a
sub-board 210a with a sub-board 210b. Grooves 222 are formed both
in the sub-boards 210a and 210b. Optical fibers 220 (220a, 220b)
are arranged in the grooves 222. Guide walls 218 formed by guide
layers 216 and 217 are arranged under the wirings 212 included in
the circuit patterns 215. The optical fibers 220 are arranged
between the guide walls 218. A gap between each of the right and
left guide walls 218 and the optical fiber 220 is preferably 0.1
.mu.m or less, specifically.
[0471] Guiding means of the present invention corresponds to the
guide wall 218, for example.
[0472] The wirings 212 on the sub-board 210a are electrically
connected to the optical element 230. In this example, wirings 213
other than the wirings 212 are also formed in the circuit patterns
215. An electronic components (such as a semiconductor element) 231
is electrically connected to the wiring 213 on the sub-board
210a.
[0473] The electronic component 231 is connected to the wirings 213
via solder balls 232. The wirings 213 in the sub-board 210b can be
connected to the circuit patterns 215 on the sub-board 210a through
via holes (not shown). In this case, the board 210 composed of the
sub-boards 210a and 210b can be used as a multi-layered board. The
wirings 213 on the sub-board 210b may be omitted.
[0474] In the board with built-in optical transmission channel 300
of Embodiment 5, the optical transmission channels (optical fibers)
220 are accommodated and fixed in the grooves 222. Thus, the
optical element 230 can easily be positioned with the optical
fibers 220 (220a, 220b). This is because the grooves 222 are formed
with reference to a part (212) of the circuit patterns 215, and
because the optical element 230 can also be aligned with the
reference. In the configuration shown in FIG. 35, the sub-boards
210a and 210b are fabricated by stacking. Thus, a multi-stage
optical transmission channel board having two, three, or more
stages can be fabricated easily. At the same time, a multi-layer
electricity wiring board can be fabricated.
[0475] The optical element 230 and the optical fibers 220 can be
optically connected to each other, for example, as shown in FIG. 36
which is a schematic partial sectional view of the configuration of
FIG. 35. That is, as shown in FIG. 36, a reflection surface
(inclined surface) 211 is formed in a part of the board 210. Then,
optical connection by light (optical signals) 225 is achieved
between the optical element 230 and the optical fibers 220 via the
reflection surface 211. In an example, the reflection surface 211
is obtained by fabricating an inclined surface in the board 210 and
then forming a metal layer (such as an Au layer) in the surface of
the inclined surface. Alternatively, an optical component (mirror)
having a reflection surface 211 may be placed on the board 210.
[0476] More specifically, the reflection surface 211 can be formed
as follows. In an example, an inclined surface is fabricated in
advance by etching, machining, or the like. Then, a new step of
forming a metal layer (such as an Au layer) on the surface of the
inclined surface is added before the step of FIG. 41(c) described
later or between the steps of FIGS. 45(a)-45(c), or alternatively
performed at the same time as these steps.
[0477] Alternatively, as shown in FIG. 37 which is a schematic
partial sectional view of the configuration of FIG. 35, an end face
221 of the optical fiber 220 is cut aslant (such as a 45.degree.
cut). Then, light 225 is reflected in the end face 221 so that
optical connection is achieved between the optical element 230 and
the optical fiber 220. In this case, as shown in this figure, the
end face 221 of the optical fiber 220 is in an opposite direction
relative to the upper surface of the board 210 where the optical
element 230 is mounted.
[0478] In the configuration shown in FIGS. 36 and 37, the optical
element 230 and the optional fiber 220 are closely contacted, but a
transparent medium may be present in the path of the light 225
between the optical element 230 and the optical fiber 220. The
transparent medium may be air, glass, transparent resin, or the
like. Similarly to Embodiments 1-4, the transparent resin is a
material permitting optical connection between the optical element
230 and the optical fiber 220 and transmitting light having a
wavelength of 850 nm, 1330 nm, and 1550 nm, or the like. More
specifically, the transparent resin maybe polyimide, epoxy aramid,
or the like. Alternatively, an optical component (such as a lens)
may be arranged between the optical element 230 and the optical
fiber 220.
[0479] In the case of multi-stage optical transmission channels,
the configuration is as shown in FIG. 38 which is a schematic
sectional view showing the configuration of FIG. 35. Here, the
optical fibers 220a in the upper row are optically connected to the
optical element 230 by light 225a. On the other hand, the optical
fibers 220b in the lower row is optically connected to the optical
element 230 by light 225b. In this case, as shown in the figure,
the end faces 221a and 221b of the optical fibers 220 are in an
opposite direction relative to the upper surface of the board 210
where the optical element 230 is mounted.
[0480] The end faces 221a and 221b of the optical fibers 220 can be
positioned with a sufficient accuracy as follows. In an example
shown in FIG. 42(b), when the patterns 214 on the lower layer
sub-board 210b are optically aligned with the patterns 214 on the
upper sub-board 210a, accurate stacking is achieved. In another
example shown in FIG. 46, when the upper and lower optical fibers
220a and 220b are closely adhered with each other in advance,
accurate positioning is achieved in the end faces 221a and
221b.
[0481] Further, as shown in FIG. 39 which is a schematic sectional
view showing the configuration of FIG. 35, in place of the optical
connection with the optical element 230, optical connection between
the optical fibers 220a in the upper row and the optical fibers
220b in the lower row is also achieved.
[0482] Although detail is described later, in the fabrication of
the board with built-in optical transmission channel (board with
built-in optical fiber) 300 of Embodiment 5, prepared are
sub-boards 210a and 210b on the surface of each of which circuit
patterns 215 including a plurality of wirings 212 are formed and in
each of which optical transmission channels (optical fibers) 220
are arranged in the grooves 222 formed between the wirings 212.
Then, the sub-boards 210a and 210b are stacked with each other.
Each of the sub-boards 210a and 210b can be fabricated using a
transfer method. More specifically, a metal layer formed on a
supporting board (see numeral 240 in FIG. 40) is patterned so that
the circuit patterns 215 including a plurality of the wirings 212
are formed. Then, optical fibers 220 (220a or 220b) are arranged
between the wirings 212 of the circuit patterns 215. After that, a
material containing resin is deposited on the supporting board so
as to cover the circuit patterns 215 and the optical fibers 220
(220a or 220b). Then, when the supporting board is removed, the
circuit patterns 215 are exposed in the surface so that each of the
sub-boards 210a and 210b is obtained.
[0483] A fabrication method for the board with built-in optical
fiber 300 according to Embodiment 5 of the present invention is
described below in detail.
[0484] First, as shown in FIG. 40(a), a carrier sheet (transfer
formation material) 240 on which a metal layer 242 is formed is
prepared. The metal layer 242 is composed of copper or the like.
The carrier sheet 240 serves as a supporting board, and is composed
of a metallic foil (a copper or aluminum foil) or a resin sheet.
The thickness of the metal layer 242 and the thickness of the
carrier sheet 240 are approximately 3-50 .mu.m and approximately
25-200 .mu.m, respectively.
[0485] Then, as shown in FIG. 40(b), a mask 250 corresponding to
the circuit patterns 215 is arranged above the metal layer 242, and
then the metal layer 242 is etched. As a result, as shown in FIG.
40(c), the circuit patterns 215 including the wirings 212 are
formed. In the example shown in the figure, in addition to the
wirings 212 located in the surrounding portion of the optical
fibers 220, other wirings 213 are shown as wirings included in the
circuit patterns 215.
[0486] After the patterning by the above-mentioned etching, walls
used as a guide for arranging the optical fibers 220 are formed in
at least a part of the circuit patterns 215. In Embodiment 5, the
guide walls are formed on the wirings 212.
[0487] More specifically, as shown in FIG. 40(c), the mask 251
having an opening in the portion of the wirings 212 is arranged
above the carrier sheet 240. Then, as shown in FIG. 40(d), a layer
(guide layer) 216 for constituting the guide walls is deposited on
the wirings 212. The guide layer 216 is composed of metal or the
like and formed by sputtering. In place of the sputtering, vapor
deposition, plating, a deposition method, or the like may be used.
In Embodiment 5, the reason why the guide layer 216 is formed by
sputtering is that this method has good shape reproducibility.
[0488] In case that the height of the guide walls for supporting
the optical fibers 220 is insufficient even after the guide layer
216 is deposited, a mask 252 is arranged above the guide layer 216
as shown in FIG. 41(a), and then another guide layer 217 is
deposited on the guide layer 216 serving as a base. The mask 252
may be the same as the previous mask 251. The material constituting
the guide layer 217 maybe the same as, or different from, the
material constituting the guide layer 216. The material
constituting the guide layers 216 and 217 is not limited to a
metal, and may be another material (such as a resin).
[0489] As such, as shown in FIG. 41(b), the guide walls 218 formed
by the guide layer 216 and the guide layer 217 are fabricated on
the wirings 212. The guide walls 218 form grooves 222 (optical
fiber mounting sections) in which optical fibers 220 are mounted.
In Embodiment 5, the sum of the thickness values of the wiring 212
and the guide wall 218 (guide layers 216 and 217) is greater than
the radius of the optical fiber 220 arranged between the guide
walls 218. This simplifies fabrication and improves accuracy.
[0490] Then, as shown in FIG. 41(c), the optical fibers 220 are
arranged between the guide walls 218 (between the wirings 212). In
other words, the optical fibers 220 are arranged into the grooves
222 formed between the guide walls 218 (or the wirings 212. In
Embodiment 5, the optical fibers 220 are arranged such as to
contact with the carrier sheet (supporting board) 240. Further, the
optical fibers 220 are arranged between the wirings 212 such as to
contact with the guide walls 218.
[0491] Then, as shown in FIG. 41(d), the material containing resin
is deposited on the carrier sheet 240 so that a sub-board
(insulating board) 210ais formed. This deposition is performed such
that the circuit patterns 215 and the optical fibers 220 are
covered. That is, the material constituting the sub-board 210a
covers: the circuit patterns 215 including the wirings 212 and 213;
the guide walls 218; and the optical fibers 220.
[0492] Then, as shown in FIG. 42(a), the sub-board 210a is
reversed, and then the carrier sheet 240 is removed. That is, the
circuit patterns 215 on the carrier sheet 240 are separated so that
the transfer is completed. Alternatively, the sub-board 210a may be
reversed after the removal of the carrier sheet 240. According to
the same fabrication process, the sub-board 210b is also
fabricated. Then, the sub-board 210a and the sub-board 210b are
stacked with each other, so that aboard with built-in optical
transmission channel 300 of Embodiment 5 is obtained as shown in
FIG. 42(b).
[0493] These steps shown in FIGS. 40, 41, and 42(a) correspond
substantially to the steps of FIGS. 2, 3, and 4(a) described In
Embodiment 1. That is, each of the sub-boards 210a and 210b can be
fabricated by the fabrication method for an optical transmission
channel board of Embodiment 1.
[0494] On completion of the board with built-in optical
transmission channel 300, an optical element 230 is mounted on the
wirings 212 of the sub-board 210a, while an electronic component
231 is mounted on the wirings 213. As a result, the configuration
shown in FIG. 35 is obtained.
[0495] The optical element 230 is a semiconductor laser or the
like. In Embodiment 5, this optical element is arranged above the
optical fibers 220, or alternatively such as to substantially
contact with the optical fibers 220. The optical element [? 30?]
230 maybe a photo receiving element (such as a photo-diode). The
electronic component 231 mounted on the portion of the wirings 213
of the circuit patterns 215 is a semiconductor element (such as a
logic LSI). The electronic component (semiconductor element) 231 is
electrically connected to the wirings 213 through solder balls 232.
A first step of the present invention corresponds to the step shown
in FIGS. 40(a)-40(c), for example. A second step of the present
invention corresponds to the step shown in FIGS. 40(d)-41(b), for
example. A third step of the present invention corresponds to the
step shown in FIGS. 41(c)-42(a), for example. A fourth step of the
present invention corresponds to the step shown in FIG. 42(b), for
example.
[0496] The step shown in FIGS. 40(a)-40(c) is described for an
exemplary case that "all of the circuit patterns are formed" in the
first step of the present invention. The step shown in FIGS.
40(d)-41(b) is described for an exemplary case that "the guiding
means is formed using said circuit patterns" in the second step of
the present invention.
[0497] In the fabrication method of Embodiment 5, in the state
shown in FIG. 41(d), the circuit patterns 215 and the optical
fibers 220 contact with the carrier sheet 240. Thus, in the state
shown in FIG. 42(a), the upper surface of the circuit patterns 215
and the uppermost portions of the optical fibers 220 are
substantially in plane. Further, the resin surface (accurately, the
surface composed of a composite material) of the sub-board 210a,
the upper surface of the circuit patterns 215, and the uppermost
portions of the optical fibers 220 are substantially in plane.
Thus, the sub-board 210a and the sub-board 210b are easily stacked
with each other in the step shown in FIG. 42(b).
[0498] Further, according to the fabrication method of Embodiment
5, the optical fibers 220 can easily be embedded (built) in the
board 210 (or the sub-boards 210a and 210b). Thus, the optical
fibers 220 are protected more appropriately in comparison with the
case that the optical fibers 220 are formed on the surface of the
board 210.
[0499] When the optical element 230 is mounted on the portion of
the wirings 212 of the circuit patterns 215, pad sections may be
formed in the wirings 212 so that the pad sections may be connected
to the element terminals of the optical element 230 by wire
bonding. Nevertheless, the wire bonding connection is
disadvantageous in high-speed characteristics.
[0500] Accordingly, as shown in FIG. 43, the connection between the
optical element 230 and the wirings 212 is preferably achieved by
flip chip mounting or the like using connection members (such as
bumps and solder balls) 232. In this case, lands are formed in the
portions of the wirings 212 contacting with the connection members
232.
[0501] As shown in FIG. 44, the optical fibers 220 maybe optically
connected to optical elements within an MCM (multi-chip module)
235, in place of a single optical element 230.
[0502] In this example, a plurality of electronic components 233a
and 233b are mounted on an interposer 234 so that an MCM 235 is
constructed. At least one of the electronic components 233a and
233b is an optical element. Both of the electronic components 233a
and 233b may be laser elements (semiconductor lasers), or
alternatively photo receiving elements (photo-diodes).
Alternatively, these electronic components maybe a combination of a
laser element and a photo receiving element. An opening is formed
in the part of the interposer 234 corresponding to the optical path
between the optical element and the optical fiber. An optical
component (such as a lens) may be arranged in the position of the
opening. The optical elements 233a and 233b may be mounted on the
back side of the interposer 234.
[0503] A board with built-in optical transmission channel 300
according to Embodiment 5 of the present invention may be
fabricated in alternative steps shown in FIGS. 45(a)-45(c). This
method is described below in detail.
[0504] First, starting from the state shown in FIG. 40(a), guide
layers 216 and 217 are stacked on a metal layer 242 so that the
state shown in FIG. 45(a) is achieved. Then, as shown in FIG.
45(b), using a mask 253 for defining the shape of grooves 222,
these layers (217, 216, 242) are etched so that grooves 222 are
formed.
[0505] Then, etching is performed using a predetermined mask, so
that guide walls 218 and circuit patterns 215 (including wirings
212 and wirings 213) are formed as shown in FIG. 45(c). FIG. 45(c)
is similar to FIG. 41(b). Thus, after the steps following FIG.
41(c) are performed, a board with built-in optical transmission
channel 300 shown in FIGS. 42(b) and 35 is obtained. "A first step
of forming a part of circuit patterns" and "a second step of
forming together with at least a part of the circuit patterns"
according to the present invention correspond to the step shown in
FIG. 45(b) as an example, and are performed substantially at the
same time.
[0506] In this example, the grooves 222 have been formed first, and
then the circuit patterns 215 has been formed. However, in the
state of FIG. 45(b), the grooves 222 and the circuit patterns 215
may be simultaneously formed (in the same step) using a mask
corresponding to the circuit patterns 215. Then, unnecessary
portions of the guide layers 216 and 217 may be removed so that the
guide wall 218 may be fabricated as shown in FIG. 45(c). At that
time, unnecessary portions of the guide layers 216 and 217 need not
be removed, and may be kept embedded in the board 210. As described
above, these two guide layers 216 and 217 need not be used.
Instead, the guide layers 216 and 217 may be formed from the same
material as a single guide layer.
[0507] Another fabrication method may be used in which the depth of
the groove 222 is increased (that is, the height of the guide wall
218 is increased) so that two optical fibers 220 are inserted in
the groove 222 in the vertical direction. As a result, a board with
built-in optical transmission channel 300 shown in FIG. 46 is
obtained. This another fabrication method according to an
embodiment of the present invention, together with a board with
built-in optical transmission channel according to an embodiment of
the present invention, is described below with reference mainly to
FIG. 46.
[0508] The difference of the fabrication method shown in FIG. 46
from the previous one mentioned above is that a plurality of
optical fibers 220a and 220b are stacked between the guide walls
218 in the thickness direction of the board 210. By virtue of this,
in the board with built-in optical transmission channel 300 shown
in FIG. 46, the distance to the optical element is reduced so that
the optical loss is advantageously reduced. FIG. 46 shows the case
that two optical fibers are stacked and embedded. However, the
present invention is not limited to this. Three or more optical
fibers may be stacked. In this case, the height of the guide wall
218 is adjusted appropriately.
[0509] FIG. 47 is a sectional view schematically showing another
configuration of a board with built-in optical transmission channel
(optical module) 300 of Embodiment 5.
[0510] The board with built-in optical transmission channel 300
shown in FIG. 47 serves as a multi-layered circuit board as well as
a multi-stage optical transmission channel board. Optical
transmission channels (optical fibers) 220 extended from the board
310 are connected to an optical connector 227. Each wiring layer
212 or 213 in the board 210 is electrically connected through
interlayer connection members (via holes) 236. An optical element
(VCSEL) 230 and a semiconductor element (LSI chip) 231 are mounted
on one surface of the board 210 through connection members 232. An
electric input and output section (electric I/O) 237 is formed in
the other surface of the board 210. As described above, a
transparent medium (such as air, glass, transparent resin, or an
optical member) is present between the optical fibers 220 (more
specifically, end faces 221 of the optical fibers 220) and the
optical element 230.
[0511] In the board with built-in optical transmission channel 300
of Embodiment 5, other wirings (such as the wiring layer 213) can
be formed together with the wirings 212 easily by a transfer
method. Thus, electronic components other than optical elements
(semiconductor elements) can be mounted similarly to the case of a
typical printed circuit board. FIG. 48 shows an optical module in
which electronic components 231 (231a, 231b, 231c, 231d, 231e) in
addition to optical elements 230a and 230b are mounted on a board
with built-in optical transmission channel 300. The board with
built-in optical transmission channel (optical module) shown in
FIG. 48 can be used as a data processing apparatus. This module is
described below in further detail.
[0512] The optical element 230a is a laser element and more
specifically a vertical-cavity surface-emitting laser (VCSEL) On
the other hand, the optical element 230b is a photo receiving
element and more specifically a photo-diode having a plurality of
photo-receiving sections. For the simplicity of understanding the
configuration of Embodiment 5, grooves 222 are shown without
optical fibers 220 in the uppermost row optically connected to the
optical element 230a. The wirings 212 are also omitted.
[0513] A driver IC 231a is connected to the laser element 230a. The
driver IC 231a is connected to an LSI chip (such as a logic LSI
like an image processing LSI) 231b. The LSI chip 231b is connected
to a memory chip 231c. A photo receiving element 230b is connected
to the LSI chip 231b via an amplifier (preamplifier) 231d and an
amplifier 231e. These electronic components 231 are mutually
connected through the wirings 213 in the circuit patterns 215. The
optical fibers 220 in the configuration shown in FIG. 48 can also
be connected to the optical connector 227 as shown in FIG. 47.
[0514] The wirings 213 may be fabricated on the board 210 in a step
other than the transfer process (such as in a separate and later
step). Nevertheless, from the perspective of fabrication procedure,
cost, and the like, it is efficient to fabricate the wirings 213 in
the same step as the wirings 212, as in the fabrication method of
Embodiment 5.
[0515] The optical module (data processing apparatus) 300 shown in
FIG. 48 can perform optical transmission through the optical fibers
220. Thus, mass data can be transmitted at a high speed. Further,
the method of Embodiment 5 allows such an optical module (data
processing apparatus) 300 to be fabricated in a simple process.
This reduces the fabrication cost. Thus, the cost can be reduced in
optical modules presently used in optical communications (such as
the Internet and telephone). This accelerates the spread of such
optical modules.
[0516] Further, the cost reduction permits the use of economical
optical transmission in within-the-board transmission (level 2) in
the communication system apparatus 3000 shown in FIG. 52. This
improves the speed of within-the-board transmission. As such, the
present invention is applicable to the bookshelf type communication
system apparatus 3000 shown in FIG. 52. Further, the optical
transmission channel board or optical module 100 of the present
invention may be used as a main apparatus such as a next-generation
high performance optical I/O module and a data processing apparatus
(like an image processing apparatus).
[0517] In the board with built-in optical transmission channel 300
of Embodiment 5, the optical fibers 220 are embedded in the board
210. Thus, even in case that the optical fibers 220 have a Y
branching section 23 as shown in FIG. 49 and hence are fragile, the
present embedding enforces the optical fibers 220. More
specifically, as shown in FIG. 49, the optical fiber 20 is embedded
into the groove 222 (optical fiber 220 mounting section) formed by
the wirings 212 and the guide walls 218 under the wirings. When
such optical fibers 220 having a Y branching section 23 are used,
an optical module suitable for wavelength multiplexing is
provided.
[0518] Embodiment 5 has been described for an exemplary case of a
board with built-in optical transmission channel employing optical
fibers. However, in place of the optical fibers, optical waveguides
composed of plane waveguides (PLCs) may be used as optical
transmission channels 220. When optical waveguides composed of
plane waveguides (PLCs) are used as optical transmission channels,
a sub-board provided with a plurality of grooves and a sub-board
210a shown in FIG. 42(a) are prepared on the plane waveguide (PLC)
side. Then, these sub-boards are stacked with each other by a
predetermined method such as by using a positioning marker (see
FIG. 42(b)). This improves manufacturability. When wirings 213 are
formed on the plane waveguide (PLC) side, or when the optical
element 230 is mounted on the plane waveguide (PLC) side,
fabrication and the centering problem are further simplified.
Nevertheless, from the perspective of cost, the use of optical
fibers based on the fabrication method of Embodiment 5 would be
advantageous over the use of the optical waveguides composed of
plane waveguides (PLCs).
[0519] Embodiment 5 has been described for the case that a single
optical transmission channel is arranged in the thickness direction
in each sub-board. However, the present invention is not limited to
this. A plurality of optical transmission channels maybe arranged
in the thickness direction of the board. In this case, each
sub-board has a configuration, for example, shown in FIG. 46.
[0520] Embodiment 5 has been described for the case that a
plurality of optical transmission channels are arranged also in the
direction substantially perpendicular to the thickness direction of
the board. However, the present invention is not limited to this. A
single optical transmission channel may be arranged in the
above-mentioned perpendicular direction.
[0521] Embodiment 5 has been described mainly for the case that
guide walls are used as guiding means. However, the present
invention is not limited to this. Recesses such as grooves may be
formed on a sub-board formed in advance so that optical
transmission channels may be arranged in the recesses. In this
case, in comparison with the configuration of Embodiment 5
employing guide walls, accuracy can be somewhat poor in the
centering for the optical connection. In spite of this
disadvantage, without using the guiding means of the present
invention, optical transmission channels may be arranged in
predetermined sections such as grooves formed independently of the
formation of the circuit patterns. In this case, the sub-boards are
stacked with each other using a positioning marker or the like.
[0522] Embodiment 5 has been described for the case that the guide
layers 216-217 are stacked on the wirings 212 so that the guide
walls 218 are formed as shown in FIGS. 40 and 41. However, the
present invention is not limited to this. For example, the steps of
FIGS. 40(d)-41(b) may be omitted. In this case, the wirings 212
serve also as the guide layer 218, and has a thickness sufficient
for positioning the optical fibers 220.
[0523] Embodiment 5 has been described for the case that a part of
the circuit patterns and the guide walls 218 are formed
simultaneously in FIG. 45(b), and further that the guide layer 218
and the wirings 213 are formed in FIG. 45(c). However, the present
invention is not limited to this. For example, all the circuit
patterns and all guide walls 218 may be formed in FIG. 45(b). In
this case, the circuit patterns and the guide walls have the same
thickness.
[0524] Embodiment 5 has been described for the case that the board
with built-in optical transmission channel of the present invention
is provided with optical elements or the like. However, the present
invention is not limited to this. For example, optical elements or
the like need not be mounted, and such a structure is sufficient
that permits mounting.
[0525] Embodiment 5 has been described mainly for the case that the
optical element is a surface type light emitting or receiving
element or a photo receiving element. However, the present
invention is not limited to this. An edge-emitting or receiving
element may be used.
[0526] The positioning markers (included in the circuit patterns)
and the guide walls are preferably formed using the same mask.
[0527] As described above, in an example, a board with built-in
optical transmission channel of the present invention comprises: a
board; circuit patterns formed on said board and having a plurality
of wirings; and a plurality of optical transmission channels
embedded in said board. A plurality of said optical transmission
channels are arranged in different hierarchies in the depth
direction of said board. An optical element is arranged above an
end portion of each of said optical transmission channels.
[0528] In an example, a part of said circuit patterns formed on
said board and said optical element are preferably connected
electrically to each other.
[0529] In a preferred embodiment, a groove is formed between said
wirings so that said optical transmission channel is arranged in
said groove.
[0530] In a preferred embodiment, said optical transmission
channels in said different hierarchies is arranged within a single
groove.
[0531] In a preferred embodiment, said board is formed by stacking
a plurality of sub-boards. A groove is formed in each of said
sub-boards. Said optical transmission channel is arranged in said
groove.
[0532] In a preferred embodiment, a plurality of said optical
transmission channels are optical fibers.
[0533] In an example, said board is preferably composed of a
composite material containing resin and inorganic filler.
[0534] Said optical element is preferably a vertical-cavity
surface-emitting laser.
[0535] In a preferred embodiment, the light-emitting surface of
said vertical-cavity surface-emitting laser is opposing to the
surface of said board. Said light-emitting surface has a plurality
of light emission points.
[0536] In a preferred embodiment, said end of said optical
transmission channel is cut into an angle of approximately 45
degrees.
[0537] In a preferred embodiment, an inclined surface for optically
connecting said end of said optical transmission channel to said
optical element is provided in the vicinity of said end of said
optical transmission channel.
[0538] Space or a transparent medium is present between said
optical element and an end portion of said optical transmission
channel.
[0539] In an example, a data processing apparatus according to the
present invention comprises: an above-mentioned board with built-in
optical transmission channel; and a semiconductor element mounted
on said board with built-in optical transmission channel.
[0540] In an example, a fabrication method for a board with
built-in optical transmission channel according to the present
invention comprises: a step of preparing sub-boards on the surface
of which circuit patterns including a plurality of wirings are
formed and in which optical transmission channels are arranged in a
groove formed between said wirings; and a step of stacking said
sub-boards.
[0541] In an example, another fabrication method for a circuit
board with built-in optical transmission channel according to the
present invention comprises: a step of forming a plurality of
grooves in the surface of a board; and a step of arranging at least
two optical transmission channels in the depth direction in each of
said grooves.
[0542] In a preferred embodiment, said optical transmission
channels are optical fibers.
[0543] In an embodiment, performed are: a step (a) of patterning a
metal layer formed on a supporting board and thereby forming
circuit patterns including a plurality of wirings; a step (b) of
arranging an optical transmission channel (such as an optical
fiber) between the wirings of said circuit pattern; a step (c) of
depositing a material containing resin on said supporting board
such as to cover said circuit patterns and said optical
transmission channel; and a step (d) of removing said supporting
board.
[0544] In a preferred embodiment, said step (a) includes: a step of
preparing a supporting board and a metal layer formed on said
supporting board; and a step of etching said metal layer using a
mask corresponding to the circuit patterns.
[0545] In an embodiment, a step of forming walls used as a guide
for arranging an optical transmission channel, in at least a part
of said circuit patterns is further performed before said step
(b).
[0546] In an embodiment, in said step (b), said optical
transmission channel is arranged such as to contact with said
supporting board.
[0547] In a preferred embodiment, said optical transmission channel
is arranged between said wiring such as to contact with said
walls.
[0548] In an embodiment, said material containing resin is a
composite material containing resin and inorganic filler.
[0549] In an embodiment, the uppermost portion of said optical
fiber is substantially in plane with the upper surface of said
circuit patterns after said step (d).
[0550] In an embodiment, a step of mounting an electronic component
electrically connected to said circuit patterns is further
performed after said step (d).
[0551] The present invention has been described above with
reference to the preferred embodiments. This description does not
limit the scope of the present invention, and hence various
modifications can be made.
[0552] An optical transmission channel board and a fabrication
method for an optical transmission channel board according to the
present invention simplifies the fabrication process. That is, a
centering process between an optical element and an optical
transmission channel is advantageously simplified or even avoided.
Thus, the present invention is useful as a data processing
apparatus or the like employing an optical transmission channel
board. Further, in an optical transmission channel board according
to the present invention, a centering process between an optical
element and an optical transmission channel is advantageously
simplified or even avoided. This reduces the fabrication cost
advantageously. Thus, the present invention is useful as a
fabrication method for an optical transmission channel board or the
like. Furthermore, aboard with built-in optical transmission
channel according to the present invention permits optical
connection with an optical element, and advantageously realizes
efficient arrangement of a large number of optical transmission
channels. Thus, the present invention is useful as a board with
built-in optical transmission channel, a data processing apparatus,
a fabrication method for a board with built-in optical transmission
channel, or the like.
* * * * *