U.S. patent application number 14/327836 was filed with the patent office on 2014-10-30 for wiring board and fabrication method therefor.
This patent application is currently assigned to IBIDEN CO., LTD.. The applicant listed for this patent is IBIDEN CO., LTD.. Invention is credited to Michimasa TAKAHASHI.
Application Number | 20140318848 14/327836 |
Document ID | / |
Family ID | 42221760 |
Filed Date | 2014-10-30 |
United States Patent
Application |
20140318848 |
Kind Code |
A1 |
TAKAHASHI; Michimasa |
October 30, 2014 |
WIRING BOARD AND FABRICATION METHOD THEREFOR
Abstract
A wiring board includes a wiring sub board having a conductive
pattern, a board positioned alongside of the wiring sub board such
that the board forms a boundary portion between the board and the
wiring sub board, and an insulating layer made of an insulating
material and continuously extending from the board to the wiring
sub board such that the insulating layer is covering the boundary
portion between the board and the wiring sub board. The boundary
portion between the board and the wiring sub board is filled with
the insulating material of the insulating layer such that the
insulating material of the insulating layer is connecting the board
and the wiring sub board.
Inventors: |
TAKAHASHI; Michimasa;
(Ogaki-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IBIDEN CO., LTD. |
Ogaki-shi |
|
JP |
|
|
Assignee: |
IBIDEN CO., LTD.
Ogaki-shi
JP
|
Family ID: |
42221760 |
Appl. No.: |
14/327836 |
Filed: |
July 10, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12537607 |
Aug 7, 2009 |
|
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|
14327836 |
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Current U.S.
Class: |
174/266 ;
29/846 |
Current CPC
Class: |
Y10T 29/49124 20150115;
Y10T 29/49155 20150115; H05K 2201/2018 20130101; H05K 3/4602
20130101; H05K 1/115 20130101; H05K 3/4694 20130101; H05K 3/10
20130101; H05K 2201/0187 20130101; H05K 1/142 20130101 |
Class at
Publication: |
174/266 ;
29/846 |
International
Class: |
H05K 1/11 20060101
H05K001/11; H05K 3/10 20060101 H05K003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2008 |
JP |
2008-304665 |
Claims
1. A wiring board comprising: a wiring sub board having a
conductive pattern; a board positioned alongside of the wiring sub
board such that the board forms a boundary portion between the
board and the wiring sub board; and an insulating layer comprising
an insulating material and continuously extending from the board to
the wiring sub board such that the insulating layer is covering the
boundary portion between the board and the wiring sub board,
wherein the boundary portion between the board and the wiring sub
board is filled with the insulating material of the insulating
layer such that the insulating material of the insulating layer is
connecting the board and the wiring sub board.
2. The wiring board according to claim 1, wherein the insulating
material of the insulating layer comprises a resin, and the
insulating material filling the boundary portion is the resin
derived from the insulating layer.
3. The wiring board according to claim 1, further comprising: a
second insulating layer comprising an insulating material and
continuously extending from the board to the wiring sub board such
that the second insulating layer is covering the boundary portion
between the board and the wiring sub board and connecting the board
and the wiring sub board from an opposite side of the board and the
wiring sub board with respect to the insulating layer, wherein the
insulating layer is formed on one side of the board and the wiring
sub board, the second insulating layer is formed on the opposite
side of the board and the wiring sub board, and the boundary
portion between the board and the wiring sub board is filled with
the insulating materials of the insulating layer and the second
insulating layer such that the insulating materials of the
insulating layer and the second insulating layer are connecting the
board and the wiring sub board.
4. The wiring board according to claim 1, wherein the wiring sub
board is provided in a plurality, and the board is positioned
alongside of the plurality of wiring sub boards such that the board
forms a boundary portion between the board and the wiring sub
boards.
5. The wiring board according to claim 4, wherein the wiring sub
boards are not electrically connected to one another.
6. The wiring board according to claim 1, wherein the insulating
layer comprises a plurality of insulating materials.
7. The wiring board according to claim 4, wherein the board forms a
frame configured to surround the wiring sub boards.
8. The wiring board according to claim 4, wherein the board
comprises a plurality of elongated bars configured to sandwich the
wiring sub boards aligned in a row.
9. The wiring board according to claim 4, wherein the board is an
insulating board forming a frame configured to surround the wiring
sub boards.
10. The wiring board according to claim 4, wherein the board is an
insulating board comprising a plurality of elongated bars
configured to sandwich the wiring sub boards aligned in a row.
11. The wiring board according to claim 4, further comprising: a
second insulating layer comprising an insulating material and
continuously extending from the board to the wiring sub boards such
that the second insulating layer is covering the boundary portion
between the board and the wiring sub boards and connecting the
board and the wiring sub boards from an opposite side of the board
and the wiring sub board with respect to the insulating layer,
wherein the insulating layer is formed on one side of the board and
the wiring sub boards, the second insulating layer is formed on the
opposite side of the board and the wiring sub boards, and the
boundary portion between the board and the wiring sub boards is
filled with the insulating materials of the insulating layer and
the second insulating layer such that the insulating materials of
the insulating layer and the second insulating layer are connecting
the board and the wiring sub boards.
12. The wiring board according to claim 3, wherein the insulating
material of the insulating layer comprises a resin, the insulating
material of the second insulating layer comprises a resin, and the
insulating materials filling the boundary portion is the resins
derived from the insulating layer and the second insulating
layer.
13. The wiring board according to claim 11, wherein the board forms
a frame configured to surround the wiring sub boards.
14. The wiring board according to claim 11, wherein the board
comprises a plurality of elongated bars configured to sandwich the
wiring sub boards aligned in a row.
15. The wiring board according to claim 5, wherein the insulating
layer comprises a plurality of insulating materials.
16. A method for fabricating a wiring board, comprising:
horizontally positioning a board alongside of a wiring sub board
having a wiring layer such that the board forms a boundary portion
between the board and the wiring sub board; laying an insulating
layer comprising an insulating material such that the insulating
layer is continuously extending from the board to the wiring sub
board and covering the boundary portion between the board and the
wiring sub board; filling the insulating material of the insulating
layer in the boundary portion between the board and the wiring sub
board such that the insulating material of the insulating layer
connects the board and the wiring sub board.
17. The method according to claim 16, further comprising conducting
outline processing on a structure comprising the board and the
wiring sub board connected by the insulating layer.
18. The method according to claim 16, wherein the insulating
material of the insulating layer comprises a resin, and the
insulating layer is pressed onto the board and the wiring sub board
such that the resin is extruded from the insulating layer and fills
the boundary portion between the board and the wiring sub
board.
19. The method according to claim 16, further comprising: producing
the board from a production panel; and producing the wiring sub
board from another production panel separate from the production
panel of the board.
20. The method according to claim 17, wherein the outline
processing is router processing.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of and claims the
benefit of priority to U.S. application Ser. No. 12/537,607, filed
Aug. 7, 2009, which claims the benefits of priority to Japanese
Patent Application No. 2008-304665, filed Nov. 28, 2008. The entire
contents of these applications are herein incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a wiring board having an
insulating board and a plurality of wiring sub boards, and a method
of fabricating the wiring board.
[0004] 2. Description of the Related Art
[0005] For example, Patent Documents Unexamined Japanese Patent
Application Publication No. 2002-289986, Unexamined Japanese Patent
Application Publication No. 20 2002-232089, Unexamined Japanese
Patent Application Publication No. 2007-115855 and Unexamined
Japanese Patent Application Publication No. 2005-322878 describe
wiring boards and fabrication methods therefor. Those wiring boards
each have an insulating board and wiring sub boards connected to
the insulating board.
[0006] The contents of Unexamined Japanese Patent Application
Publication No. 2002-289986, Unexamined Japanese Patent Application
Publication No. 2002-232089, Unexamined Japanese Patent Application
Publication No. 2007-115855 and Unexamined Japanese Patent
Application Publication No. 2005-322878 are herein incorporated in
their entirety.
SUMMARY OF THE INVENTION
[0007] According to the first aspect of the invention, a wiring
board includes: a wiring sub board having a conductive pattern; an
insulating board being laid out alongside of the wiring sub board;
and an insulating layer having a via hole in which a conductor to
be electrically connected to the conductive pattern is formed by
plating, the insulating layer continuously extending from the
insulating board to the wiring sub board so as to cover a boundary
portion between the insulating board and the wiring sub board. An
insulating material for the insulating layer is filled in the
boundary portion between the insulating board and the wiring sub
board.
[0008] According to the second aspect of the invention, a
fabrication method for a wiring board includes: horizontally laying
an insulating board formed of an insulating material and a wiring
sub board having a wiring layer; laying an insulating layer to
cover a boundary portion between the insulating board and the
wiring sub board; filling an insulating material for the insulating
layer in the boundary portion between the insulating board and the
wiring sub board; forming a via hole in the insulating layer and
forming a conductor in the via hole by plating; and electrically
connecting the conductor formed in the via hole to the wiring
layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0010] FIG. 1A is a diagram showing the outline of a wiring board
according to one embodiment of the present invention;
[0011] FIG. 1B is a diagram showing the internal structure of the
wiring board according to the embodiment of the invention;
[0012] FIG. 2 is a cross-sectional view of a wiring sub board
constituting the wiring board;
[0013] FIG. 3 is a cross-sectional view along line A-A in FIG.
1A;
[0014] FIG. 4 is a diagram for explaining a step of producing the
wiring sub board at a production panel;
[0015] FIGS. 5A-5C are diagrams for explaining a step of forming a
first layer of the wiring sub board;
[0016] FIGS. 6A-6C are diagrams for explaining a step of forming a
second layer of the wiring sub board;
[0017] FIGS. 7A-7B are diagrams for explaining a step of forming a
third layer of the wiring sub board;
[0018] FIG. 8 is a diagram for explaining a step of fabricating the
insulating board;
[0019] FIG. 9 is a diagram showing the outline the insulating
board;
[0020] FIG. 10 is a diagram for explaining a step of laying out the
wiring sub board;
[0021] FIGS. 11A-11D are diagrams for explaining a step of forming
insulating layers on both sides of the insulating board and the
wiring sub board;
[0022] FIG. 12 is a diagram for explaining a step of performing
outline processing on the wiring board;
[0023] FIG. 13A is a diagram showing another example of the wiring
sub board;
[0024] FIG. 13B is a diagram showing a different example of the
wiring sub board;
[0025] FIG. 13C is a diagram showing a further example of the
wiring sub board;
[0026] FIG. 14 is a cross-sectional view showing an example of a
wiring board having a one-side wiring sub board; and
[0027] FIG. 15 is a diagram showing another example of the wiring
board.
DETAILED DESCRIPTIONS OF THE EMBODIMENT
[0028] The embodiment will now be described with reference to the
accompanying drawings, wherein like reference numerals designate
corresponding or identical elements throughout the various
drawings.
[0029] A wiring board 10 according to an embodiment, which has the
outline as shown in FIG. 1A and the internal structure as shown in
FIG. 1B, for example, has an insulating board 11 as a frame, and
wiring sub boards 12a, 12b, 12c, 12d, 12e and 12f. The insulating
board 11 and the wiring sub boards 12a to 12f are laid out
horizontally through a boundary portion R1, and the wiring sub
boards 12a to 12f are laid out horizontally through a boundary
portion R2. A sixth insulating layer 313 and a fifth insulating
layer 311 are formed on the top sides and bottom sides of the
insulating board 11 and the wiring sub boards 12a to 12f. FIG. 1B
shows the internal structure of the wiring board 10 with the fifth
and sixth insulating layers 311 and 313 omitted.
[0030] The insulating board 11 is an insulating board made of, for
example, a glass epoxy resin or the like. Particularly, as shown in
FIGS. 1A and 1B, the insulating board 11 is a quadrate frame
surrounding the wiring sub boards 12a to 12f. The wiring sub boards
12a to 12f are laid out inside the insulating board 11. The shape
of the insulating board 11 is optional. For example, the insulating
board 11 may have a circular shape or an elliptical shape, or may
be two thin elongated bars sandwiching the wiring sub boards
aligned in a row.
[0031] The wiring sub boards 12a to 12f are rectangular rigid
boards. The shapes of the wiring sub boards 12a to 12f are
optional, and may be, for example, a parallelepiped shape, a
circular shape, an elliptical shape or so. The wiring sub boards
12a to 12f are not electrically connected to one another.
[0032] Each of the wiring sub boards 12a to 12f whose
cross-sectional structures are shown in FIG. 2 is a so-called
build-up multi-layer printed wiring board. That is, each of the
wiring sub boards 12a to 12f has a rigid base 112, first and second
insulating layers 111 and 113, and third and fourth insulating
layers 114 and 115 laminated.
[0033] The rigid base 112 is made of, for example, a rigid
insulating material. Specifically, the rigid base 112 is made of a
glass epoxy resin or the like with a thickness of, for example,
about 50 to 150 .mu.m, desirably about 100 .mu.m.
[0034] Formed at top and bottom sides of the rigid base 112 are
first to fourth insulating layers 111, 113 to 115 made of, for
example, a hardened prepreg, wiring layers 122a, 122b, 121, 123 to
125 made of, for example, copper, and via holes (interlayer
connected portions) 131, 133 to 135. Conductors 141, 143 to 145 of,
for example, copper, are filled in the via holes 131, 133 to 135 to
electrically connect the individual wiring layers to one another. A
through hole 132 is formed in the rigid base 112. The through hole
132 is formed by, for example, boring a hole in the conductor 142
of copper or the like through and plating the hole to electrically
connect the wiring layers 122a and 122b at the top and bottom of
the rigid base 112.
[0035] More specifically, the wiring layers 122b, 122a are
respectively formed on the top and bottom sides of the rigid base
112, and are electrically connected to the overlying respective
wiring layers 121, 123 through the via holes 131, 133 and the
conductors 141, 143. Further, the wiring layers 121, 123 are
electrically connected to the overlying respective wiring layers
124, 125 through the via holes 134, 135 and the conductors 144,
145.
[0036] As shown in FIG. 3 (cross-sectional view along line A-A in
FIG. 1A), for example, the sixth and fifth insulating layers 313,
311 are respectively formed on the top and bottom sides of the
insulating board 11 and the wiring sub boards 12a to 12f. The fifth
and sixth insulating layers 311, 313 are laid out to cover the
boundary portion R1 between the insulating board 11 and the wiring
sub boards 12a to 12f, and the boundary portion R2 (see FIGS. 1A
and 1B) between the wiring sub boards 12a to 12f. The fifth and
sixth insulating layers 311 and 313 continuously extend from the
insulating board 11 to the wiring sub boards 12a to 12f.
[0037] Via holes 331, 333 are formed in the fifth and sixth
insulating layers 311, 313, respectively. Conductors 341, 343 of
copper, for example, are formed in the via holes 331, 333. The
conductors 341, 343 are electrically connected to the wiring layers
124, 125 of the wiring sub boards 12a to 12f, respectively. The
wiring sub boards 12a to 12f are not electrically connected to one
another.
[0038] The fifth and sixth insulating layers 311 and 313 are formed
of a rigid insulating material, such as a hardened prepreg. It is
desirable that the prepregs of the first to sixth insulating layers
111, 113 to 115, 311, 313 should contain a resin having the
low-flow property. Such prepregs can be produced by performing
pre-hardening beforehand by, for example, impregnating a glass
cloth with an epoxy resin, then thermally hardening the resin. The
glass cloth may be impregnated with a high viscosity resin, or
impregnated with a resin containing an inorganic filler (e.g.,
silica filler), or the resin contain of the glass cloth may be
decreased. An RCF (Resin Coated copper Foil) or the like may be
used in place of the prepreg.
[0039] Insulating resins 21a to 21c (insulating materials) leaked
out (flowed out) from the fifth and sixth insulating layers 311 and
313 are filled between the insulating board 11 and the wiring sub
boards 12a to 12f, and between the wiring sub boards 12a to 12f.
Accordingly, the wiring sub boards 12a to 12f are secured at
predetermined positions. This therefore requires no bridges or the
like to couple the insulating board 11 to the wiring sub boards 12a
to 12f. The use of the resins 21a to 21c leaked from the fifth and
sixth insulating layers 311 and 313 also eliminates the need for an
adhesive or the like.
[0040] In fabricating the wiring board 10, first, the wiring sub
boards 12a to 12f are produced at a production panel 100 as shown
in FIG. 4, for example. The production panel 100 is a dedicated
production panel at which wiring sub boards having the same
structure (structure shown in FIG. 2) including the wiring sub
boards 12a to 12f are produced.
[0041] The wiring sub boards 12a to 12f are produced separately
from the insulating board 11 according to the fabrication method of
the embodiment. This makes it possible to produce a larger number
of wiring sub boards 12a to 12f at the production panel 100, thus
improving the yield or the number of yielded products.
[0042] In producing the wiring sub boards 12a to 12f, first, a
material common to a plurality of products is cut with, for
example, a laser or the like to prepare the rigid base 112 with a
predetermined shape and size as shown in FIG. 5A.
[0043] Then, after predetermined pre-processing, for example, the
through hole 132 is formed as shown in FIG. 5B by irradiating, for
example, a CO.sub.2 laser beam from a CO.sub.2 laser processing
apparatus.
[0044] Subsequently, after desmearing (smear removal) and soft
etching are carried out, PN plating (e.g., chemical copper plating
and electric copper plating) is performed. As a result, a
conductive film is formed on the entire surface of the rigid base
112 including the interior of the through hole 132. Then, the
conductive film is made thinner to a predetermined thickness by,
for example, half etching, the conductive film is patterned as
shown in FIG. 5C through, for example, a predetermined lithography
process (pre-processing, lamination, exposure, development,
etching, film separation, inspection of internal layers, etc.). As
a result, the wiring layers 122a and 122b and the conductor 142 are
formed.
[0045] Subsequently, as shown in FIG. 6A, for example, the second
insulating layer 113 and the first insulating layer 111 are
disposed on the top and bottom sides of the wiring board. Then,
they are pressed (e.g., hot-pressed). Thereafter, the resin is
hardened in, for example, a heat treatment or the like, to solidify
the first and second insulating layers 111 and 113. Then, after
predetermined pre-processing, as shown in FIG. 6B, the via hole 131
is formed in the first insulating layer 111 and the via hole 133 is
formed in the second insulating layer 113 with a laser, for
example. Then, after desmearing (smear removal) and soft etching
are carried out, PN plating (e.g., chemical copper plating and
electric copper plating) is performed. As a result, a conductive
film is formed on the entire surface of the wiring board including
the via holes 131 and 133. Then, the conductive film on the surface
of the wiring board is made thinner to a predetermined thickness
by, for example, half etching, the conductive film is patterned as
shown in FIG. 6C through, for example, a predetermined lithography
process (pre-processing, lamination, exposure, development,
etching, film separation, inspection of internal layers, etc.). As
a result, the conductors 141 and 143, and the wiring layers 121 and
123 are formed. Thereafter, the top surfaces of the wiring layers
121 and 123 are processed to form rough surfaces. The wiring layers
121 and 123 can also be formed by printing a conductive paste
(e.g., thermoset resin containing conductive particles) by, for
example, screen printing.
[0046] Subsequently, as shown in FIG. 7A, for example, the fourth
insulating layer 115 and the third insulating layer 114 are
disposed on the top and bottom sides of the wiring board. Then,
they are pressed (e.g., hot-pressed). Thereafter, the resin is
hardened in, for example, a heat treatment or the like, to solidify
the third and fourth insulating layers 114 and 115. Then, after
predetermined pre-processing, as shown in FIG. 7B, the via hole 134
is formed in the third insulating layer 114 and the via hole 135 is
formed in the fourth insulating layer 115 with a laser, for
example. Further, through steps similar to those shown in FIG. 6C,
the conductors 144 and 145, and the wiring layers 124 and 125 as
shown in FIG. 2 are formed. As a result, the wiring sub boards 12a
to 12f are produced at the production panel 100 as shown in FIG.
4.
[0047] Before or after producing the wiring sub boards 12a to 12f,
the insulating board 11 is produced. Specifically, as shown in FIG.
8, a material (production panel 200) common to a plurality of
products is cut with, for example, a laser or the like to produce
the insulating board 11 with a predetermined shape and size.
Accordingly, a quadrate frame shown in FIG. 9 as the insulating
board 11 is obtained. As the insulating board 11 is produced
separately from the wiring sub boards 12a to 12f, an unnecessary
laminate is not formed on the insulating board 11. This reduces the
consumption of the conductive materials, insulating materials and
so forth. This results in reduction in fabrication cost.
[0048] Next, the wiring sub boards 12a to 12f are respectively
separated from the production panel 100, and are laid out inside
the insulating board 11 as shown in FIG. 10. Before separation of
the wiring sub boards 12a to 12f from the production panel 100, an
electrification test or the like is performed on the wiring sub
boards 12a to 12f. This allows any defective board to be removed so
that defect-free boards are used. That is, defect-free boards are
laid out inside the insulating board 11.
[0049] According to the fabrication method of the embodiment, a
defective board can be found and removed before forming the
outermost layer, i.e., at an earlier stage. It is therefore
possible to reduce the consumption of materials which would occur
in case of defective boards present. This results in reduction in
fabrication cost.
[0050] The positional alignment of the wiring sub boards 12a to 12f
before forming the outermost layer can easily achieve
high-precision alignment.
[0051] Subsequently, as shown in FIG. 11A, for example, the sixth
and fifth insulating layers 313, 311 are disposed on the top and
bottom sides of the wiring sub boards 12a to 12f (only 12a and 12b
shown in FIGS. 11A to 11D) and the insulating board 11. Then, they
are pressed (e.g., hot-pressed) as shown in FIG. 11B. Accordingly,
the resins 21a to 21c are extruded from the fifth and sixth
insulating layers 311 and 313. That is, the pressing causes the
resins 21a to 21c to leak out (flow out) from the prepregs
constituting the fifth and sixth insulating layers 311 and 313 to
be filled in the boundary portion R1 between the insulating board
11 and the wiring sub boards 12a to 12f, and the boundary portion
R2 between the wiring sub boards 12a to 12f. As the sixth and fifth
insulating layers 313, 311 are formed on the top and bottom sides
of the insulating board 11 and the wiring sub boards 12a to 12f at
this time, the resins 21a to 21c are filled from both sides.
Thereafter, the fifth and sixth insulating layers 311 and 313 are
solidified by hardening the resins through, for example, a heat
treatment or the like.
[0052] Subsequently, after predetermined pre-processing, as shown
in FIG. 11C, the via hole 331 is formed in the fifth insulating
layer 311, and the via hole 333 is formed in the sixth insulating
layer 313 with, for example, a laser. Then, after desmearing (smear
removal) and soft etching are carried out, PN plating (e.g.,
chemical copper plating and electric copper plating) is performed.
As a result, a conductive film is formed on the entire surface of
the wiring board including the via holes 331 and 333. Subsequently,
the conductive film on the surface of the wiring board is made
thinner to a predetermined thickness by, for example, half etching,
the conductive film is patterned as shown in FIG. 11D through, for
example, a predetermined lithography process (pre-processing,
lamination, exposure, development, etching, film separation,
inspection of internal layers, etc.). As a result, the conductors
341 and 343, and the wiring layers 321 and 323 are formed.
[0053] Thereafter, outline processing of the wiring board is
performed as shown in, for example, FIG. 12, using a router, for
example. In the outline processing, the wiring board is processed
to a predetermined shape (e.g., quadrate shape) like a cut line L1
in the diagram within the widthwise range of the frame of the
insulating board 11.
[0054] The wiring board 10 shown in FIG. 3 is fabricated this way.
That is, the fifth and sixth insulating layers 311 and 313, and the
wiring layers 321 and 323 in the wiring board 10 become the
outermost layers.
[0055] While the wiring board and fabrication method according to
the embodiment have been described, the present invention is not
limited to the embodiment.
[0056] The wiring sub boards 12a to 12f are not electrically
connected to one another in the embodiment, which is not
restrictive. For example, the wiring sub boards 12a to 12f may be
electrically connected to one another according to the purpose or
the like.
[0057] The wiring sub boards 12a to 12f are not limited to those
shown in FIG. 2. For example, the boards may be flexible printed
wiring boards. Further, the wiring sub board may be a flex-rigid
printed wiring board 101 having a flexible part 101a and rigid
parts 101b and 101c as shown in FIG. 13A. Furthermore, the wiring
sub board may be a printed wiring board 102 incorporating an
electronic part 102a as shown in FIG. 13B, for example. As another
option, the wiring sub board may be a printed wiring board 103
having a cavity 103a formed in the top surface thereof as shown in
FIG. 13C. The wiring sub board may be a one-side printed wiring
board 104a, 104b having wiring layers and insulating layers
laminated only on one side of the core, as shown in FIG. 14
(cross-sectional view corresponding to FIG. 3).
[0058] The materials and sizes of the individual layers, the number
of the layers, and so forth may be changed in the embodiment.
[0059] For example, single-layer insulating layers, i.e., the sixth
and fifth insulating layers 313, 311 are formed on the top and
bottom sides of the insulating board 11 and the wiring sub boards
12a to 12f in the embodiment, which is not restrictive. For
example, as shown in FIG. 15, multiple insulating layers of
different materials, i.e., the sixth and eight insulating layers
313 and 315, and the fifth and seventh insulating layers 311 and
314 may be formed on the top and bottom sides of the insulating
board 11 and the wiring sub boards 12a to 12f.
[0060] Although the wiring board 10 having six wiring sub boards
12a to 12f is exemplified in the foregoing description of the
embodiment, the number of wiring sub boards is optional. That is,
the quantity may be one, two to five, or seven or greater.
[0061] The sequential order of the processes in the embodiment may
be changed without departing from the scope and spirit of the
invention. Some processes may be omitted according to the purpose
or the like.
[0062] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
* * * * *