U.S. patent application number 10/895050 was filed with the patent office on 2005-01-27 for circuit module and manufacturing method thereof.
This patent application is currently assigned to Matsushita Electric Industrial Co., Ltd.. Invention is credited to Morimoto, Kenji, Segawa, Shigetoshi.
Application Number | 20050017347 10/895050 |
Document ID | / |
Family ID | 33549970 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050017347 |
Kind Code |
A1 |
Morimoto, Kenji ; et
al. |
January 27, 2005 |
Circuit module and manufacturing method thereof
Abstract
A circuit module includes an electronic component, a ceramic
multilayer substrate and a resin wiring substrate. The ceramic
multilayer substrate is provided with a wiring layer disposed on
top thereof and a cavity in which the electronic component is
mounted, wherein a space between the electronic component and the
cavity is filled with a thermosetting resin and a surface of the
filled cavity is planarized. The resin wiring substrate has an
insulating adhesive layer disposed at one side thereof and provided
with at least one opening filled with a conductive resin. The
ceramic multilayer substrate and the resin wiring substrate are
bonded by the insulating adhesive layer, and the wiring layer on
the ceramic multilayer substrate is electrically connected with the
conductive resin.
Inventors: |
Morimoto, Kenji; (Ehime,
JP) ; Segawa, Shigetoshi; (Ehime, JP) |
Correspondence
Address: |
BACON & THOMAS, PLLC
625 SLATERS LANE
FOURTH FLOOR
ALEXANDRIA
VA
22314
|
Assignee: |
Matsushita Electric Industrial Co.,
Ltd.
Osaka
JP
|
Family ID: |
33549970 |
Appl. No.: |
10/895050 |
Filed: |
July 21, 2004 |
Current U.S.
Class: |
257/703 ;
257/E23.14; 257/E23.178 |
Current CPC
Class: |
H01L 2924/01322
20130101; H01L 2924/15153 20130101; H05K 3/4614 20130101; H05K
2203/061 20130101; H05K 3/4652 20130101; H01L 23/5389 20130101;
H01L 2924/01046 20130101; H01L 2224/16225 20130101; H01L 2924/09701
20130101; H05K 3/4605 20130101; H05K 1/186 20130101; H05K 3/386
20130101; H01L 2924/01079 20130101; H05K 3/4617 20130101; H01L
23/24 20130101; H01L 2924/01019 20130101; H05K 3/4629 20130101;
H05K 1/0306 20130101; H05K 3/4069 20130101; H01L 2924/1517
20130101; H01L 2924/01078 20130101 |
Class at
Publication: |
257/703 |
International
Class: |
H05K 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 22, 2003 |
JP |
2003-277432 |
Claims
What is claimed is:
1. A circuit module comprising: an electronic component; a ceramic
multilayer substrate provided with a wiring layer disposed on top
thereof and a cavity in which the electronic component is mounted,
wherein a space between the electronic component and the cavity is
filled with a thermosetting resin and a surface of the filled
cavity is planarized; and a resin wiring substrate including an
insulating adhesive layer disposed at one side thereof and provided
with at least one opening filled with a conductive resin, wherein
the ceramic multilayer substrate and the resin wiring substrate are
bonded by the insulating adhesive layer, and the wiring layer on
the ceramic multilayer substrate is electrically connected with the
conductive resin.
2. The circuit module of claim 1, wherein the height difference
between a surface of the thermosetting resin filling the cavity and
that of the ceramic multilayer substrate around the cavity is less
than a thickness of the insulating adhesive layer.
3. The circuit module of claim 1, wherein the resin wiring
substrate further includes one or more stacking sheets, each of the
stacking sheets having an insulating adhesive layer, a wiring layer
formed thereon, the insulating adhesive layer being provided with
at least one opening filled with a conductive resin which is
electrically connected to the wiring layer of each of the stacking
sheets.
4. The circuit module of claim 1, wherein the insulating adhesive
layer makes use of a thermosetting material.
5. The circuit module of claim 1, wherein the ceramic multilayer
substrate is made of a glass-ceramic material allowing a low
temperature sintering.
6. The circuit module of claim 1, wherein at least one electronic
component is mounted on a surface of the resin wiring substrate, at
least a part of said at least one electronic component being
located directly above at least a part of the cavity formed in the
ceramic multilayer substrate.
7. The circuit module of claim 1, wherein the electronic component
mounted in the cavity includes a semiconductor integrated circuit
device.
8. A method of fabricating a circuit module, comprising the steps
of: (a) mounting at least one electronic component in a cavity
provided in a ceramic multilayer substrate; (b) filling a space
between the electronic component and the cavity with a
thermosetting resin to planarize a surface of the filled cavity;
(c) providing at least one opening in an insulating adhesive layer
of a sheet having the insulating adhesive layer and a metal layer
stacked on each other or in both of the insulating adhesive layer
and the metal layer, and filling the opening with a conductive
resin connected to the metal layer; (d) bonding the sheet and the
ceramic multilayer substrate by the insulating adhesive layer and
at the same time electrically connecting a wiring layer formed on
the ceramic multilayer substrate with the conductive resin; and (e)
patterning the metal layer of the sheet to form a wiring layer.
9. The method of claim 8, further comprising, after the step (e),
the steps of: (f) bonding a stacking sheet which has an insulating
adhesive layer and a metal layer, at least one opening being
provided in the insulating adhesive layer or in both of the
insulating adhesive layer and the metal layer and filled with a
conductive resin connected with the metal layer, by means of the
insulating adhesive layer, onto an uppermost layer of an assembly
provided in the immediately preceding step and at the same time
electrically connecting the wiring layer formed on the uppermost
layer with the conductive resin of the stacking sheet; and (g)
patterning the metal layer of the stacking sheet to form a wiring
layer, wherein the steps (f) and (g) are repeated N times (N being
an integer not smaller than 1).
10. The method of claim 8, wherein an amount of the thermosetting
resin used in said step (b) of filling the space to planarize the
surface of the filled cavity corresponds to the difference between
a volume of the cavity and that of the electronic component, and
the height difference between a surface of the thermosetting resin
and that of the ceramic multilayer substrate around the cavity is
less than a thickness of the insulating adhesive layer in the
immediate vicinity of the ceramic multilayer substrate.
11. The method of claim 8, wherein the step (b) of filling the
space to planarize the surface of the filled cavity is carried out
by first filling the cavity with the thermosetting resin by using
an amount exceeding the difference between a volume of the cavity
and that of the electronic component, thermally curing the filled
thermosetting resin, and then polishing a surface of the cured
thermosetting resin and wherein the height difference between a
surface of the polished resin and that of the ceramic multilayer
substrate around the cavity is less than a thickness of the
insulating adhesive layer directly abutting the ceramic multilayer
substrate.
12. The method of claim 8, wherein the electronic component
includes a semiconductor integrated circuit device.
13. A method of fabricating a circuit module, comprising the steps
of: (a) mounting at least one electronic component in a cavity
provided in a ceramic multilayer substrate; (b) filling a space
between the electronic component and the cavity with a
thermosetting resin to planarize a surface of the filled cavity;
(c) patterning a metal layer of a sheet to form a wiring layer, the
sheet having an insulating adhesive layer and the metal layer
stacked on each other; (d) providing at least one opening in the
insulating adhesive layer or in both of the insulating adhesive
layer and the wiring layer, and filling the opening with a
conductive resin connected to the wiring layer; and (e) bonding the
sheet and the ceramic multilayer substrate by means of the
insulating adhesive layer and at the same time electrically
connecting a wiring layer formed on the ceramic multilayer
substrate with the conductive resin.
14. The method of claim 13, further comprising, after the step (e),
the step of: (f) bonding a stacking sheet which has an insulating
adhesive layer and a wiring layer, at least one opening being
provided in the insulating adhesive layer or in both of the
insulating adhesive layer and the wiring layer and filled with a
conductive resin connected with the wiring layer, by means of the
insulating adhesive layer, onto an uppermost layer of an assembly
provided in the immediately preceding step and at the same time
electrically connecting the wiring layer formed on the uppermost
layer with the conductive resin of the stacking sheet, wherein the
step (f) is repeated N times (N being an integer not smaller than
1).
15. The method of claim 13, wherein an amount of the thermosetting
resin used in said step (b) of filling the space to planarize the
surface of the filled cavity corresponds to the difference between
a volume of the cavity and that of the electronic component, and
the height difference between a surface of the thermosetting resin
and that of the ceramic multilayer substrate around the cavity is
less than a thickness of the insulating adhesive layer in the
immediate vicinity of the ceramic multilayer substrate.
16. The method of claim 13, wherein the step (b) of filling the
space to planarize the surface of the filled cavity is carried out
by first filling the cavity with the thermosetting resin by using
an amount exceeding the difference between a volume of the cavity
and that of the electronic component, thermally curing the filled
thermosetting resin, and then polishing a surface of the cured
thermosetting resin and wherein the height difference between a
surface of the polished resin and that of the ceramic multilayer
substrate around the cavity is less than a thickness of the
insulating adhesive layer directly abutting the ceramic multilayer
substrate.
17. The method of claim 13, wherein the electronic component
includes a semiconductor integrated circuit device.
18. A method of fabricating a circuit module, comprising the steps
of: (a) mounting at least one electronic component in a cavity
provided in a ceramic multilayer substrate; (b) filling a space
between the electronic component and the cavity with a
thermosetting resin to planarize a surface of the filled cavity;
(c) patterning a metal layer of a sheet to form a wiring layer and
simultaneously providing at least one opening in the wiring layer,
the sheet having an insulating adhesive layer and the metal layer
stacked on each other; (d) bonding the sheet and the ceramic
multilayer substrate by means of the insulating adhesive layer; (e)
removing the insulating adhesive layer located under the opening in
the wiring layer to provide an extended opening exposing
therethrough a surface of a wiring layer formed on the ceramic
multilayer substrate; and (f) filling the extended opening with a
conductive resin to electrically connect the wiring layer of the
sheet with the wiring layer on the ceramic multilayer
substrate.
19. The method of claim 18, further comprising, after the step (f),
the steps of: (g) bonding a stacking sheet which has an insulating
adhesive layer and a wiring layer, at least one opening being
provided in the wiring layer, onto an uppermost layer of an
assembly provided in the immediately preceding step by means of the
insulating adhesive layer; (h), in the stacking sheet, removing the
insulating adhesive layer located under the opening in the wiring
layer to provide an extended opening exposing therethrough a
surface of the uppermost layer; and (i) filling the extended
opening in the stacking sheet with a conductive resin and
electrically connecting the wiring layer of the stacking sheet with
a wiring layer of the uppermost layer, wherein the steps (g) to (i)
are repeated N times (N being an integer not smaller than 1)
20. The method of claim 18, wherein an amount of the thermosetting
resin used in said step (b) of filling the space to planarize the
surface of the filled cavity corresponds to the difference between
a volume of the cavity and that of the electronic component, and
the height difference between a surface of the thermosetting resin
and that of the ceramic multilayer substrate around the cavity is
less than a thickness of the insulating adhesive layer in the
immediate vicinity of the ceramic multilayer substrate.
21. The method of claim 18, wherein the step (b) of filling the
space to planarize the surface of the filled cavity is carried out
by first filling the cavity with the thermosetting resin by using
an amount exceeding the difference between a volume of the cavity
and that of the electronic component, thermally curing the filled
thermosetting resin, and then polishing a surface of the cured
thermosetting resin and wherein the height difference between a
surface of the polished resin and that of the ceramic multilayer
substrate around the cavity is less than a thickness of the
insulating adhesive layer directly abutting the ceramic multilayer
substrate.
22. The method of claim 18, wherein the electronic component
includes a semiconductor integrated circuit device.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a high-performance circuit
module having electronic components such as a semiconductor
integrated circuit (hereinafter, refer to as an "IC") and a
manufacturing method thereof.
BACKGROUND OF THE INVENTION
[0002] Along with a high density integration and a high speed
performance of ICs, concerted efforts are being made to develop
technologies to increase the number of terminals and to narrow the
pitches of a package on which such an IC is mounted. With respect
to this, a technological progress is underway to fabricate a
circuit module, on which electronic devices such as an IC is
mounted, that is larger in scale, faster in speed, and smaller in
size. In order to achieve such a miniaturization and high density
of a circuitry, it is required to increase the number of wiring
layers, to miniaturize wirings, and to develop a technology to
enable mounting of electronic components including an IC inside a
circuit substrate. Further, with respect to a method of mounting an
IC, a flip-chip technology, which allows for a high density
mounting, has been widely available. As a circuit substrate
appropriate for the purposes, a multilayer ceramic substrate, a
multilayer resin substrate, or a combination thereof are being
used.
[0003] With respect to a circuit substrate, a high-density
mountability, high-speed performance and low costs are the
characteristics that are strongly required. As a result, to satisfy
these requirements, efforts are actively being made to develop a
combined multilayer substrate composed of a ceramic multilayer
substrate and a resin substrate. For example, Japanese Patent
Laid-open Publication No. 2002-374067 discloses a circuit substrate
composed of a ceramic multilayer substrate stacked and bonded, by
pressurization and heating, with a resin base material formed of
thermoplastic resin on which conductive wiring patterns are formed
and via holes are disposed within its interlayer connective
sections. In accordance with this configuration, the fabrication
step of a multilayer substrate composed of a multilayer ceramic
substrate and a resin base material becomes simplified. Further,
given that a reliable bonding between a multilayer ceramic
substrate and a resin base material can be achieved, a highly
reliable circuit substrate can be obtained.
[0004] Further, Japanese Patent Laid-open Publication No.
1998-256413 discloses an IC package composed of a ceramic
multilayer substrate, within which a cavity is formed where an IC
is mounted, bonded on and combined with a resin base material
having a conductive layer and an insulating ceramic layer. In
accordance with this configuration, since a wiring length and
distance can both be reduced given that a patterned conductive
layer can be formed on a resin base material, it is possible to
achieve a miniaturized IC package with a high density wiring
therein.
[0005] As noted above, with respect to a circuit substrate,
miniaturization, high-speed performance and high performance are
the characteristics strongly required. However, according to the
first prior art reference above, since a multilayer wiring is not
formed on the ceramic multilayer substrate, the substrate only
serves as a base material. Further, the disclosed technology only
enables an IC to be surface mounted. Therefore, in accordance with
the technology, a high performance complex circuit substrate cannot
be achieved.
[0006] Further, in the second prior art reference above, a resin
base material having a conductive layer is interposed between the
ceramic multilayer substrates while the layers are bonded using an
adhesive and an IC is mounted in the cavity. However, since the
ceramic multilayer substrates disposed on opposed surfaces function
as the main component, fine wiring patterns cannot be achieved.
Further, the problem of high costs has remained to be solved given
that double-surface wirings would be required for a ceramic
multilayer substrate in order to mount additional electronic
components on the surface opposed to a mounting surface, the
mounting surface being connected to a circuit substrate by using
conductive balls. In addition, in order to be compatible with a
high-speed performance IC, for example, a bypass capacitor must be
connected to an electrode terminal of the IC at a minimum distance.
However, in the second prior art reference, since a bypass
capacitor cannot be mounted on an upper portion of the cavity, the
capacitor can only be mounted on an external circuit substrate.
Consequently, it has remained to be solved that an extensive wiring
distance prevented achieving a high-speed operation.
SUMMARY OF THE INVENTION
[0007] It is, therefore, an object of the present invention to
provide a circuit module, which is capable of containing a cavity
structure, with a higher-density mountability and high-speed
performance to solve the problems identified thus far, and to
provide a method of fabricating the module.
[0008] In accordance with a preferred embodiment of the present
invention, there is provided a first circuit module including: an
electronic component; a ceramic multilayer substrate provided with
a wiring layer disposed on top thereof and a cavity in which the
electronic component is mounted, wherein a space between the
electronic component and the cavity is filled with a thermosetting
resin and a surface of the filled cavity is planarized; and a resin
wiring substrate including an insulating adhesive layer disposed at
one side thereof and provided with at least one opening filled with
a conductive resin, wherein the ceramic multilayer substrate and
the resin wiring substrate are bonded by the insulating adhesive
layer, and the wiring layer on the ceramic multilayer substrate is
electrically connected with the conductive resin.
[0009] In accordance with this configuration, given that an
electronic component including an IC is mounted within the ceramic
multilayer substrate, and also that the resin wiring substrate
encloses the cavity region, various electronic components can be
mounted on the resin wiring substrate on the cavity. Specifically,
an IC or a passive device can also be mounted on the resin wiring
substrate, including the areas inside and on the cavity. As a
result, a module, which is miniaturized and having a high mounting
density, high-speed performance and little noise can be obtained,
because a higher mounting density of electronic components and a
minimum distance wiring thereof are enabled.
[0010] In accordance with another preferred embodiment of the
present invention, there is provided a second circuit module, which
includes the first circuit module, wherein the height difference
between a surface of the thermosetting resin filling the cavity and
that of the ceramic multilayer substrate around the cavity is less
than a thickness of the insulating adhesive layer.
[0011] In accordance with this configuration, when resin wiring
patterns are formed on the ceramic multilayer substrate, it is
possible to obtain a flat planar shape so that obtaining a
multilayer structure becomes easier.
[0012] In accordance with still another preferred embodiment of the
present invention, there is provided a third circuit module, which
includes the first circuit module, wherein the resin wiring
substrate further includes one or more stacking sheets, each of the
stacking sheets having an insulating adhesive layer, a wiring layer
formed thereon, the insulating adhesive layer being provided with
at least one opening filled with a conductive resin and
electrically connected to the wiring layer of each of the stacking
sheets.
[0013] In accordance with this configuration, since the multilayer
resin wiring substrate can be formed of sheets of a same material,
not only are the fabrication steps simplified, but high performance
circuit modules can be obtained at a low cost as well.
[0014] In accordance with still another preferred embodiment of the
present invention, there is provided a fourth circuit module, which
includes the first circuit module, wherein the insulating adhesive
layer makes use of a thermosetting material. As a result, since the
chemical resistance is increased after bonding on the ceramic
multilayer substrate following thermally curing the adhesive layer,
forming a wiring layer by etching the metal layer becomes easy.
Further, the sturdiness of the module is enhanced.
[0015] In accordance with still another preferred embodiment of the
present invention, there is provided a fifth circuit module, which
includes the first circuit module, wherein the ceramic multilayer
substrate is made of a glass-ceramic material allowing a low
temperature sintering. As a result, since the ceramic multilayer
substrate can be co-sintered with the conductive and insulating
layers, the sintering operation can be carried out at a low cost.
Further, since the difference between the ceramic substrate's
thermal expansion coefficient and that of the resin wiring
substrate is small, the module can withstand heating impact so that
it is prevented from peeling off. Therefore, a highly reliable
circuit module can be obtained.
[0016] In accordance with still another preferred embodiment of the
present invention, there is provided a sixth circuit module, which
includes the first circuit module, wherein at least one electronic
component is mounted on a surface of the resin wiring substrate, at
least a part of said at least one electronic component being
located directly above at least a part of the cavity formed in the
ceramic multilayer substrate. As a result of this configuration,
for instance, if an IC is mounted on the cavity, a bypass capacitor
can be mounted in a minimum distance from the IC's terminal.
Accordingly, a circuit module capable of high-speed performance can
be easily obtained.
[0017] In accordance with still another preferred embodiment of the
present invention, there is provided a first method of fabricating
a circuit module, which includes the steps of: mounting at least
one electronic component in a cavity provided in a ceramic
multilayer substrate; filling a space between the electronic
component and the cavity with a thermosetting resin to planarize a
surface of the filled cavity; providing at least one opening in an
insulating adhesive layer of a sheet having the insulating adhesive
layer and a metal layer stacked on each other or in both of the
insulating adhesive layer and the metal layer, and filling the
opening with a conductive resin connected to the metal layer;
bonding the sheet and the ceramic multilayer substrate by the
insulating adhesive layer and at the same time electrically
connecting a wiring layer formed on the ceramic multilayer
substrate with the conductive resin; and patterning the metal layer
of the sheet to form a wiring layer.
[0018] In accordance with this method, the resin wiring substrate
can be easily stacked on a ceramic multilayer substrate, of which
cavity contains an electronic component such as an IC, and which is
planarized by a thermosetting resin. Especially, since a wiring
pattern on the metal layer of the sheet can be formed by a process
such as etching after the sheet is bonded to the ceramic multilayer
substrate, it is difficult to misalign the wiring pattern with the
top surface wiring layer of the ceramic multilayer substrate.
Consequently, it is possible to form fine patterns, thereby
obtaining a multilayer structure as well. Further, given that it is
easy to fill the opening with a conductive resin, a conduction
failure rarely occurs. Therefore, a highly reliable circuit module
having a high density wiring layer can be obtained.
[0019] In accordance with still another preferred embodiment of the
present invention, there is provided a second method, which
includes the first method, and further includes the steps of:
bonding a stacking sheet which has an insulating adhesive layer and
a metal layer, at least one opening being provided in the
insulating adhesive layer or in both of the insulating adhesive
layer and the metal layer and filled with a conductive resin
connected with the metal layer, by means of the insulating adhesive
layer, onto an uppermost layer of an assembly provided in the
immediately preceding step and at the same time electrically
connecting the wiring layer formed on the uppermost layer with the
conductive resin of the stacking sheet; and patterning the metal
layer of the stacking sheet to form a wiring layer, wherein the
above two steps are repeated N times (N being an integer not
smaller than 1).
[0020] In accordance with this method, the multilayer resin wiring
substrate can be easily formed on a ceramic multilayer substrate,
of which cavity contains an electronic component such as an IC, and
which is planarized by a thermosetting resin.
[0021] In accordance with still another preferred embodiment of the
present invention, there is provided a third method of fabricating
a circuit module, which includes the steps of: mounting at least
one electronic component in a cavity provided in a ceramic
multilayer substrate; filling a space between the electronic
component and the cavity with a thermosetting resin to planarize a
surface of the filled cavity; patterning a metal layer of a sheet
to form a wiring layer, the sheet having an insulating adhesive
layer and the metal layer stacked on each other; providing at least
one opening in the insulating adhesive layer or in both of the
insulating adhesive layer and the wiring layer, and filling the
opening with a conductive resin connected to the wiring layer; and
bonding the sheet and the ceramic multilayer substrate by means of
the insulating adhesive layer and at the same time electrically
connecting a wiring layer formed on the ceramic multilayer
substrate with the conductive resin.
[0022] In accordance with this method, the resin wiring substrate
can be easily stacked on a ceramic multilayer substrate, of which
cavity contains an electronic component such as an IC, and which is
planarized by a thermosetting resin. In this method, since before
being bonded to the ceramic multilayer substrate, a wiring pattern
is formed on the sheet's metal layer by a process such as etching,
and at the same time, an opening is formed and is filled with a
conductive resin, the processes of forming openings and
wiring-patterns as well as charging with the conductive resin can
be carried out collectively using a large sheet. Therefore, the
fabrication steps are considerably simplified.
[0023] In accordance with still another preferred embodiment of the
present invention, there is provided a fourth method, which
includes the third method, and further includes the step of bonding
a stacking sheet which has an insulating adhesive layer and a
wiring layer, at least one opening being provided in the insulating
adhesive layer or in both of the insulating adhesive layer and the
wiring layer and filled with a conductive resin connected with the
wiring layer, by means of the insulating adhesive layer, onto an
uppermost layer of an assembly provided in the immediately
preceding step and at the same time electrically connecting the
wiring layer formed on the uppermost layer with the conductive
resin of the stacking sheet, wherein the above step is repeated N
times (N being an integer not smaller than 1).
[0024] In accordance with this method, the multilayer resin wiring
substrate can be easily formed on a ceramic multilayer substrate,
of which cavity contains an electronic component such as an IC, and
which is planarized by a thermosetting resin.
[0025] In accordance with still another preferred embodiment of the
present invention, there is provided a fifth method of fabricating
a circuit module, which includes the steps of: mounting at least
one electronic component in a cavity provided in a ceramic
multilayer substrate; filling a space between the electronic
component and the cavity with a thermosetting resin to planarize a
surface of the filled cavity; patterning a metal layer of a sheet
to form a wiring layer and simultaneously providing at least one
opening in the wiring layer, the sheet having an insulating
adhesive layer and the metal layer stacked on each other; bonding
the sheet and the ceramic multilayer substrate by means of the
insulating adhesive layer; removing the insulating adhesive layer
located under the opening in the wiring layer to provide an
extended opening exposing therethrough a surface of a wiring layer
formed on the ceramic multilayer substrate; and filling the
extended opening with a conductive resin to electrically connect
the wiring layer of the sheet with the wiring layer on the ceramic
multilayer substrate.
[0026] In accordance with this method, the resin wiring substrate
can be easily stacked on a ceramic multilayer substrate, of which
cavity contains an electronic component such as an IC, and which is
planarized by a thermosetting resin. Further, in this method, since
before being bonded to the ceramic multilayer substrate, a wiring
pattern is formed on the sheet's metal layer by a process such as
etching, and after being bonded to the ceramic multilayer
substrate, openings are formed on the insulating adhesive layer and
are filled with a conductive resin, the openings are not yet formed
during bonding and handling during bonding becomes easy, even when
multiple openings are formed.
[0027] In accordance with still another preferred embodiment of the
present invention, there is provided a sixth method, which includes
the fifth method, and further includes the steps of: bonding a
stacking sheet which has an insulating adhesive layer and a wiring
layer, at least one opening being provided in the wiring layer,
onto an uppermost layer of an assembly provided in the immediately
preceding step by means of the insulating adhesive layer; in the
stacking sheet, removing the insulating adhesive layer located
under the opening in the wiring layer to provide an extended
opening exposing therethrough a surface of the uppermost layer; and
filling the extended opening in the stacking sheet with a
conductive resin and electrically connecting the wiring layer of
the stacking sheet with a wiring layer of the uppermost layer,
wherein the above steps are repeated N times (N being an integer
not smaller than 1)
[0028] In accordance with this method, the resin wiring substrate
can be easily stacked on a ceramic multilayer substrate, of which
cavity contains an electronic component such as an IC, and which is
planarized by a thermosetting resin.
[0029] In accordance with still another preferred embodiment of the
present invention, there is provided a seventh method, which
includes one of the first, third and fifth method, wherein an
amount of the thermosetting resin used in said step of filling the
space to planarize the surface of the filled cavity corresponds to
the difference between a volume of the cavity and that of the
electronic component, and the height difference between a surface
of the thermosetting resin and that of the ceramic multilayer
substrate around the cavity is less than a thickness of the
insulating adhesive layer in the immediate vicinity of the ceramic
multilayer substrate. Further preferably, there is provided an
eighth method, which includes one of the first, third and fifth
method, wherein the step of filling the space to planarize the
surface of the filled cavity is carried out by first filling the
cavity with the thermosetting resin by using an amount exceeding
the difference between a volume of the cavity and that of the
electronic component, thermally curing the filled thermosetting
resin, and then polishing a surface of the cured thermosetting
resin and wherein the height difference between a surface of the
polished resin and that of the ceramic multilayer substrate around
the cavity is less than a thickness of the insulating adhesive
layer directly abutting the ceramic multilayer substrate.
[0030] In accordance with these methods, since the height
difference between the cavity region and the surface of the ceramic
multilayer substrate is less than the thickness of the insulating
adhesive layer, when the resin wiring substrate is stacked on the
ceramic multilayer substrate, the height difference can be covered
up by the insulating adhesive layer, and thus it is possible to
prevent unevenness on the resin wiring substrate after bonding. As
a result, it is easy to form the resin wiring substrate with
multilayers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The above and other objects and features of the present
invention will become apparent from the following description of
preferred embodiments given in conjunction with the accompanying
drawings, in which:
[0032] FIGS. 1A and 1B are a cross-sectional view and a top plan
view, respectively, of a circuit module in accordance with the
first embodiment of this invention;
[0033] FIGS. 2A to 2C show a method of manufacturing a circuit
module in accordance with the first embodiment of this invention,
and are cross-sectional views illustrating a step of mounting an IC
on a multilayer ceramic substrate and a step of planarizing the
ceramic substrate;
[0034] FIGS. 3A to 3C are cross-sectional views illustrating a step
of manufacturing a sheet in accordance with the manufacturing
method of the first embodiment of this invention;
[0035] FIGS. 4A and 4B are cross-sectional views illustrating a
step of forming a predetermined wiring layer by attaching a sheet
on a ceramic multilayer substrate in accordance with the
manufacturing method of the first embodiment of this invention;
[0036] FIGS. 5A to 5C are cross-sectional views illustrating a step
of manufacturing a stacking sheet in accordance with the
manufacturing method of the first embodiment of this invention;
[0037] FIG. 6 is a cross-sectional view of a circuit module having
a metal layer of a stacking sheet etched to form a multilayer resin
wiring substrate in the manufacturing method of the first
embodiment of this invention;
[0038] FIGS. 7A to 7C are cross-sectional views illustrating a step
of manufacturing a sheet in accordance with a circuit module
manufacturing method of the second embodiment of this
invention;
[0039] FIGS. 8A and 8B are cross-sectional views illustrating a
step of manufacturing a circuit module having a single-layer resin
wiring substrate by attaching a sheet on a multilayer ceramic
substrate in accordance with the manufacturing method of the second
embodiment of this invention;
[0040] FIG. 9 is a cross-sectional view illustrating a step of
manufacturing a circuit module having a multilayer resin wiring
substrate by stacking a stacking sheet on top of the other in
accordance with the manufacturing method of the second embodiment
of this invention;
[0041] FIGS. 10A to 10D are cross-sectional views illustrating a
step of manufacturing a sheet in accordance with a circuit module
manufacturing method of the third embodiment of this invention;
[0042] FIG. 11 is a cross-sectional view illustrating a step of
manufacturing a circuit module having a single-layer resin wiring
substrate by attaching a sheet on a multilayer ceramic substrate in
accordance with the manufacturing method of the third embodiment of
this invention;
[0043] FIGS. 12A and 12B are cross-sectional views illustrating a
step of manufacturing a circuit module having a multilayer resin
wiring substrate by stacking a stacking sheet on top of the other
in accordance with the manufacturing method of the third embodiment
of this invention;
[0044] FIGS. 13A and 13B are cross-sectional views illustrating a
step of manufacturing a circuit module having a single-layer resin
wiring substrate by attaching a sheet on a multilayer ceramic
substrate in accordance with the manufacturing method of the fourth
embodiment of this invention;
[0045] FIGS. 14A and 14B are cross-sectional views illustrating a
step of manufacturing a circuit module having a multilayer resin
wiring substrate by stacking a stacking sheet on top of the other
in accordance with the manufacturing method of the fourth
embodiment of this invention;
[0046] FIGS. 15A to 15C are cross-sectional views illustrating a
step of manufacturing a circuit module having a single-layer resin
wiring substrate by attaching a sheet on a multilayer ceramic
substrate in accordance with the manufacturing method of the fifth
embodiment of this invention; and
[0047] FIGS. 16A and 16B are cross-sectional views illustrating a
step of manufacturing a circuit module having a multilayer resin
wiring substrate by stacking a stacking sheet on top of the other
in accordance with the manufacturing method of the fifth embodiment
of this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0048] Hereinafter, preferred embodiments of the present invention
are described in detail with reference to the accompanying figures.
Same items in the figures are assigned a common reference numeral
throughout the figures.
[0049] First Embodiment
[0050] A circuit module and a method of manufacturing same, in
accordance with a first embodiment of this invention, are described
with reference to FIGS. 1A to 4B.
[0051] FIGS. 1A and 1B are a cross-sectional view and a top plan
view, respectively, of a circuit module in accordance with this
first embodiment.
[0052] Multilayer ceramic substrate 10 is provided with conductive
via 14 formed in dielectric layer 12 to make electrical connection
between layers; interior wiring layer 16, top surface wiring layer
18 and bottom surface wiring layer 20, all of which are
electrically connected with conductive via 14; and cavity 22 for
mounting electronic component 30 thereon. For such multilayer
ceramic substrate 10, for instance, when a glass-ceramic material
is used as dielectric layers 12, it can be sintered at a relatively
low temperature in the range of about 900-100.degree. C.
Consequently, dielectric layers 12 can be co-sintered with
materials that form conductive via 14 and interior wiring layer 16.
Further, it is possible to form top surface wiring layer 18, bottom
surface wiring layer 20 and the like by co-sintering operation.
However, top and bottom surface wirings 18 and 20 are typically
excluded in the co-sintering of dielectric layers 12, conductive
via 14 and interior wiring layer 16; instead, after forming wiring
patterns on the top and bottom surfaces of dielectric layers 12,
the substrate 10 is sintered again for formation of top and bottom
surface wirings 18 and 20. Further, since a glass-ceramic material
has a low thermal expansion coefficient, the reliability of the
mounting part for electronic component 30 such as an integrated
circuit (IC) can be improved.
[0053] Further, a material used for conductive via 14 and interior
wiring layer 16 is not limited so long as it can be co-sintered
with a glass-ceramic material and is conductive, namely, silver
(Ag), copper (Cu), gold (Au), nickel (Ni), palladium (Pd),
silver-palladium alloy, gold-palladium alloy or the like. Further,
not only are wiring patterns formed on top and bottom surface
wiring layers 18 and 20, but also terminal electrodes (not shown)
for mounting the circuit module on a circuit substrate are formed
thereon. The terminal electrodes may be gold plated to enhance
their soldering qualities.
[0054] If, for instance, an IC is used as electronic component 30,
cavity 22 is formed larger than the IC's external dimension.
Further, on the bottom surface of cavity 22, an electrode pad 24 is
formed for connecting with electronic component 30. Ceramic
multilayer substrate 10 having cavity 22 may be fabricated by
stacking and co-sintering a first green sheet with an opening
serving as cavity 22 and a second green sheet with electrode pad
24.
[0055] Electronic component 30 is mounted on cavity 22. In this
embodiment, since the example of using an IC as electronic
component 30 has been illustrated, hereinafter, without further
reference, IC 30 indicates electronic component 30. Bump 32 is
formed on IC 30, and a general flip-chip mounting technique is used
to connect bump 32 with electrode pad 24 formed on the bottom
surface of cavity 22. Examples of the flip-chip mounting technique
are as follows: a connection technique using a bump electrode and a
conductive resin; a connection technique which employs soldering by
using a solder bump; a connection technique using a plated bump and
a conductive resin; and a connection technique employing an
eutectic Au--Sn connection by using gold (Au) as a bump material
and depositing tin (Sn) on a surface of electrode pad 24.
[0056] Since a gap exists in cavity 22, which has IC 30 mounted
thereon, thermosetting resin 40 is used to seal the gap;
thereafter, the surface of cavity 22 is planarized to make it
approximately coplanar with that of ceramic multilayer substrate
10.
[0057] Resin wiring substrate 70 is attached on the surface of
ceramic multilayer substrate 10. Resin wiring substrate 70 is
composed of sheet 50 formed of first insulating adhesive layer 52
and first wiring layer 54, and stacking sheet 60, which is stacked
on sheet 50, formed of second insulating adhesive layer 62 and
second wiring layer 64. Ceramic multilayer substrate 10 is attached
by first insulating adhesive layer 52 and connected electrically to
the terminal electrode, which is a part of top surface wiring layer
18 of ceramic multilayer substrate 10, by conductive resin 56.
Further, insulating adhesive layers 52 and 62 function as
insulating layers between different layers.
[0058] First and second wiring layers 54 and 64 are, for example,
formed by etching copper films attached on first and second
insulating adhesive layers 52 and 62, respectively. In this case,
when each of the copper films is 10 .mu.m or less thick, this
allows for higher densification of wiring than that of ceramic
multilayer substrate 10 because a wiring width and a wiring pitch
may be set to 20-30 .mu.m, respectively.
[0059] Further, in this circuit module, electronic component 80 is
mounted on a surface of resin wiring substrate 70, which includes
an upper region where cavity 22 is formed. Thus electronic
component 80 can be mounted on the surface of resin wiring
substrate 70, which is located just above where cavity 22 is
formed. Such electronic component 80 to be mounted can be a passive
device like a chip capacitor or a chip resistor, or another IC
different from IC 30. With regard to a method of mounting
electronic component 80, a passive device may be connected by a
solder reflow connection or a conductive adhesive connection, while
an IC may be mounted by a flip-chip mounting technique or a wire
bonding technique or the like. For example, when a chip capacitor
is used as electronic component 80, it can function as a bypass
capacitor connected to IC 30 at the shortest distance, thereby
enabling a high-speed operation of IC 30. FIGS. 1A and 1B
illustrate an example where a chip capacitor is mounted as
electronic component 80. The chip capacitor is connected with
second wiring layer 64 of resin wiring substrate 70 by solder
82.
[0060] As noted above, the circuit module of the present invention
allows for enlarging mountable areas in addition to wiring at a
minimum distance between IC 30 mounted on cavity 22 and electronic
component 80 mounted on the surface of the resin wiring substrate
70. Accordingly, the circuit module's high-frequency
characteristics are enhanced and noises generated by a sudden
change of currents are suppressed.
[0061] Hereinafter, the method of fabricating a circuit module in
accordance with the first embodiment will be described with
reference to figures.
[0062] FIGS. 2A to 2C are cross-sectional views illustrating the
steps of mounting IC 30 on ceramic multilayer substrate 10 wherein
cavity 22 is formed and charging cavity 22 with thermosetting resin
40 for planarization.
[0063] As shown in FIG. 2A, a ceramic multi-layer substrate 10 can
be easily fabricated by stacking and co-firing a first and a second
green sheets prepared as follows: wiring patterns formed of
conductive pastes such as silver (Ag) and copper (Cu) are deposited
on the first green sheet which has an opening formed by employing
processes such as laser technique or punching so that the opening
functions as cavity 22 to contain IC 30, while wiring patterns are
similarly formed on the second green sheet also. On the bottom
surface of cavity 22, electrode pad 24 is disposed at a position
corresponding to bump 32 of IC 30. Subsequently, interior wiring
layer 16, top surface wiring layer 18, bottom surface wiring layer
20 and conductive via 14 that interconnect these layers are formed
simultaneously.
[0064] FIG. 2B is a cross-sectional view illustrating mounting of
IC 30 in cavity 22 using a flip-chip mounting technique. As the
flip-chip mounting technique, various techniques generally for
mounting an IC can be used as discussed earlier.
[0065] Next, as shown in FIG. 2C, the gap of cavity 22 is sealed
with thermosetting resin 40, and then surface planarization is
achieved. The charged quantity of thermosetting resin 40 is
controlled so that it corresponds to the difference between cavity
22 and IC 30 volumes. As a result, the level difference between the
surface of thermosetting resin 40 filling cavity 22 and the surface
of ceramic multilayer substrate 10 can be made less than the
thickness of first insulating adhesive layer 52, so that a
sufficient adhesive strength is achieved when resin wiring
substrate 70 is attached to ceramic multilayer substrate 10.
Further, since resin wiring substrate 70 can have an even flat
surface after attaching it, the process of forming first wiring
layer 54 by etching a metal layer is facilitated. Further, mounting
electronic component 80 on resin wiring substrate 70 also becomes
easily manageable.
[0066] Alternatively, thermosetting resin 40 may be charged more
than the aforementioned quantity and thermally cured thereafter, so
that a mound of thermosetting resin 40 that formed above the
surface of ceramic multilayer substrate 10 be grinded in order to
planarize it. Since this method allows for a smaller level
difference between the surface of thermosetting resin 40 and that
of ceramic multilayer substrate 10, it is possible to enhance
adhesive strength and processability, to facilitate the mounting
process, and to improve reliability.
[0067] Further, thermosetting resin 40 used may be an epoxy resin,
a polyimide resin, a silicon resin and the like.
[0068] FIGS. 3A to 3C are cross-sectional views illustrating a
process of fabricating sheet 50 which functions as a first level
resin wiring substrate on ceramic multilayer substrate 10 which is
planarized by using thermosetting resin 40.
[0069] As shown in FIG. 3A, sheet 50 is fabricated by first
attaching insulating adhesive layer 52 to a first metal layer 541
such as copper film. Thereafter, as shown in FIG. 3B, an opening
561 is formed in sheet 50 by drilling or punching of holes or the
like.
[0070] Next, as shown in FIG. 3C, first opening 561 is filled with
a conductive resin 56, whose major component is silver (Ag) or gold
(Au), by employing a printing technique or a drawing technique.
Following this method, sheet 50 having first opening 561 filled
with conductive resin 56 is fabricated. Further, as for first
insulating adhesive layer 52, a thermosetting adhesive material
such as an epoxy resin, a polyimide resin or a silicon resin is
used. This adhesive material shaped into a sheet may be used as
first insulating adhesive layer 52, which could be bonded on first
metal layer 541, otherwise, a predetermined thickness of the
adhesive material can be laminated on first metal layer 541 to be
used as first insulating adhesive layer 52.
[0071] Subsequently, sheet 50 shown in FIG. 3C is properly aligned
on ceramic multilayer substrate 10 shown in FIG. 2C. The aligned
sheets are pressurized and heated on its top and bottom major
surfaces, whereby first insulating adhesive layer 52 is bonded to
ceramic multilayer substrate 10 while top surface wiring layer 18
becomes electrically connected with conductive resin 56. Further,
if conductive resin 56 has adhesive characteristics, it can augment
the strength of the electrical connection.
[0072] With respect to the pressurization and heating conditions,
using a mold for example, the stacked layers are preliminarily
pressurized at about 0.8 kgf/cm.sup.2 and heated at about
170.degree. C., and then the heating and pressurizing process is
repeated at about 20 kgf/cm.sup.2 and about 200.degree. C. under a
reduced pressure atmosphere, thereby achieving strong adhesion. The
result is shown in FIG. 4A.
[0073] Subsequently, as shown in FIG. 4B, first metal layer 541 of
the resin wiring substrate of sheet 50 is etched to remove
unnecessary portions to form first wiring layer 54. At this
fabrication stage, since sheet 50 functions as a single-layer resin
wiring substrate, the assembly in this condition can also be used
as a circuit module. Further, upon mounting a passive device such
as a capacitor and a resistor, or a functional device such as an IC
on first wiring layer 54, the assembly can be used as a
high-performance circuit module.
[0074] In this embodiment, a method of fabricating a circuit module
of a multilayer resin wiring substrate 70 stacked on ceramic
multilayer substrate 10 is described.
[0075] FIGS. 5A to 5C are cross-sectional views illustrating a
process of fabricating stacking sheet 60 to be stacked on sheet 50
so as to form a multilayered structure. Stacking sheet 60 is
composed of a second metal layer 641 and second insulating adhesive
layer 62, and has the same configuration as that of sheet 50 shown
in FIGS. 3A to 3C. This is illustrated in FIG. 5A.
[0076] Next, second opening 661 is formed at locations where first
wiring layer 54 of sheet 50 can establish a connection. Second
opening 661 can be formed in the same fashion as first opening 561
of sheet 50. FIG. 5B shows stacking sheet 60 after second opening
661 is formed. Subsequently, second opening 661 is filled with
conductive resin 66. This resin charging process can be carried out
using the same material and in the same manner as in sheet 50. FIG.
5C shows stacking sheet 60 ready to be bonded to sheet 50 after
being charged with conductive resin 66.
[0077] Next, after a predetermined position of first wiring layer
54 of sheet 50 is properly aligned with conductive resin 66 of
stacking sheet 60, the coupled sheets are subjected to pressurizing
and heating for bonding while first wiring layer 54 establishes
electrical connection with conductive resin 66 as well. This
bonding step is carried out in the same fashion as in the bonding
of sheet 50 to ceramic multilayer substrate 10.
[0078] Thereafter, second metal layer 641 of stacking sheet 60 is
etched to remove unnecessary portions, thereby forming second
wiring layer 64 as shown in FIG. 6. On second wiring layer 64 as
fabricated thus far, a passive device, for example, capacitor,
resistor or inductor, or an IC can be mounted. FIGS. 1A and 1B
illustrate a case where a chip capacitor is mounted as electronic
component 80.
[0079] In accordance with the circuit module of this embodiment,
since IC 30 can be mounted on cavity 22 of ceramic multilayer
substrate 10, and various electronic components 80 can also be
mounted on the surface of resin wiring substrate 70 above cavity
22, not only is it possible to enhance high density mounting
capability, but also to achieve, for instance, high speed
performance of an IC and to facilitate its correspondence with a
high-frequency circuit, because the IC can be connected to a chip
capacitor at a minimum distance.
[0080] Second Embodiment
[0081] FIGS. 7A to 7C are cross-sectional views illustrating a
process of fabricating sheet 500 in the method of fabricating a
circuit module in accordance with a second embodiment of the
present invention. Further, FIGS. 8A and 8B are cross-sectional
views showing a process of stacking sheet 500 on ceramic multilayer
substrate 10 wherein IC 30 is mounted on cavity 22 and the
substrate is planarized by using thermosetting resin 40, ultimately
forming a first wiring layer 540.
[0082] The second embodiment is different from the first embodiment
with respect to the processes of fabricating sheet 500 and of
forming first wiring layer 540 after stacking sheet 500 on ceramic
multilayer substrate 10. Hereinafter, a method of fabricating a
circuit module is described while focusing on its differences with
the first embodiment.
[0083] As shown in FIG. 7A, using sheet 500 composed of first metal
layer 542 (e.g., copper film) and first insulating adhesive layer
521, first opening 562 is formed at a predetermined location of
first insulating adhesive layer 521 as shown in FIG. 7B. First
opening 562 serves as a place where it is electrically connected
with top surface wiring layer 18 of ceramic multilayer substrate
10, and it is formed by, for example, laser irradiation. The laser
by its nature is capable of forming an opening in first insulating
adhesive layer 521, but not in first metal layer 542, for example,
of copper film because it is highly reflective. Accordingly, laser
irradiation allows for perforation of only first insulating
adhesive layer 521, not first metal layer 542.
[0084] Next, as shown in FIG. 7C, first opening 562 is filled with
conductive resin 560 whose main component is silver (Ag) or copper
(Cu). With respect to a material of conductive resin 560 and its
filling process, their discussion is omitted given that the
identical material and process may be used as in the first
embodiment.
[0085] Sheet 500 fabricated in this manner is properly aligned and
then bonded on ceramic multilayer substrate 10, as shown in FIG.
8A. This bonding may be carried out in the same fashion as in the
first embodiment.
[0086] Further, as shown in FIG. 8B, first metal layer 542 is
etched to form first wiring layer 540. As a result, since sheet 500
is capable of functioning as a single-layer resin wiring substrate,
it can be used as a circuit module in this form. Further, on a
terminal electrode (not shown) disposed in first wiring layer 540
of sheet 500, an electronic component such as a capacitor, a
resistor, an inductor or an IC may be mounted.
[0087] As noted above, although a resin wiring substrate to be
stacked on ceramic multilayer substrate 10 can be a single-layer
structure, a method of fabricating a multilayer resin wiring
substrate is described in this embodiment.
[0088] FIG. 9 is a cross-sectional view of a circuit module formed
of a multilayer resin wiring substrate 700 wherein stacking sheet
600 is stacked on sheet 500 shown in FIG. 8B. Stacking sheet 600
may be formed in the same manner using the same material as sheet
500 shown in FIGS. 7A to 7C. Further, given that the process of
forming second wiring layer 640 after aligning and bonding stacking
sheet 600 on sheet 500 are identical to that of sheet 500, its
description is omitted.
[0089] Based on the steps described thus far, a circuit module on
which multilayer resin wiring substrate 700 is stacked can be made.
In this embodiment, since the metal layer is not perforated unlike
the first embodiment, laser irradiation can be employed to make
fine openings. As a result, multilayer resin wiring substrate 700
becomes capable of even finer micro wiring so that a module with a
high density circuit substrate can be made.
[0090] Third Embodiment
[0091] FIGS. 10A to 10D are cross-sectional views illustrating a
process of fabricating sheet 510 in the method of fabricating a
circuit module in accordance with a third embodiment of the present
invention. Further, FIG. 11 is a cross-sectional view showing a
process of stacking sheet 510 having first wiring layer 545 formed
thereon, on ceramic multilayer substrate 10 wherein IC 30 is
mounted on cavity 22 and the substrate is planarized using
thermosetting resin 40.
[0092] In this embodiment, with respect to the fabricating step of
sheet 510, its difference with that of the first embodiment lies in
its stacking step on ceramic multilayer substrate 10 which is
carried out after first wiring layer 545 is formed. Hereinafter, a
method of fabricating a circuit module is described while focusing
on its differences with the first embodiment.
[0093] As shown in FIG. 10A, using sheet 510 composed of first
metal layer 544 (e.g., copper film) and first insulating adhesive
layer 522, first opening 564 is formed at a predetermined location
of first insulating adhesive layer 522 and first metal layer 544 as
shown in FIG. 10B. First opening 564 is formed by, for example,
punching or drilling.
[0094] Next, as shown in FIG. 10C, first opening 564 is filled with
a conductive resin 565 whose main component is silver (Ag) or
copper (Cu). With respect to a material of conductive resin 565 and
its filling process, their discussion is omitted given that the
identical material and process may be used as in the first
embodiment.
[0095] Next, as shown in FIG. 10D, first wiring layer 545 is formed
by processing (e.g., etching) first metal layer 544.
[0096] Sheet 510 formed in the manner described thus far is
properly aligned and bonded on ceramic multilayer substrate 10 on
which IC 30 is mounted as shown in FIG. 11. Since this bonding step
can be carried out in the same fashion as the process described in
the first embodiment, its description is omitted. As a result,
given that sheet 510 is capable of functioning as a single-layer
resin wiring substrate, the assembly could be used as a circuit
module in this form. Further, on first wiring layer 545, an
electronic component such as a capacitor, a resistor, an inductor
or an IC may be surface mounted so that the assembly functions as a
circuit module.
[0097] FIGS. 12A and 12B are cross-sectional views illustrating a
step of fabricating a circuit module with multilayer resin wiring
substrate 710 which is formed of stacking sheet 610 stacked on
sheet 510 shown in FIG. 11. Stacking sheet 610 may be fabricated in
the same manner using the same material as sheet 510 shown in FIGS.
10A to 10D. Specifically, as shown in FIG. 12A, stacking sheet 610
is fabricated by forming second wiring layer 645 from etching a
metal layer on second insulating adhesive layer 622 while a second
opening is filled with conductive resin 665.
[0098] As shown in FIG. 12B, stacking sheet 610 on which second
wiring layer 645 is formed is properly aligned and bonded on sheet
510 while first wiring layer 545 of sheet 510 becomes electrically
connected to conductive resin 665 simultaneously. An electronic
component such as a capacitor as shown in FIGS. 1A and 1B can be
mounted on second wiring layer 645 of the circuit module.
[0099] With respect to the method of fabricating a circuit module
in accordance with the third embodiment, before sheet 510 and
stacking sheet 610 are bonded on ceramic multilayer substrate 10,
they are first subjected to charging first and second openings with
conductive resins 565 and 665, and to forming first and second
wiring layers 545 and 645. Thus, a circuit module is fabricated
simply when the sheets are bonded on ceramic multilayer substrate
10. Therefore, sheet 510 and stacking sheet 610 may be fabricated
in a large area collectively, thereafter formed for each ceramic
multilayer substrate 10 and bonded thereon. In this fashion,
fabricating steps can be considerably simplified.
[0100] Further, on second wiring layer 645, an electronic component
which can be mounted is not limited to a capacitor, rather, it can
be a passive device such as a resistor or an inductor, otherwise, a
functional device such as a memory, an IC, or an image sensor,
depending on the function of a fabricated circuit module.
[0101] Fourth Embodiment
[0102] Hereinafter, a method of fabricating a circuit module in
accordance with a fourth embodiment is described with reference to
FIGS. 13A to 14B.
[0103] FIG. 13A is a cross-sectional view of sheet 520, and FIG.
13B is a cross-sectional view of the sheet bonded on ceramic
multilayer substrate 10 on which IC 30 is mounted. In this
embodiment, sheet 520 is composed of a metal layer (e.g., copper
film) formed on first insulating adhesive layer 524 and, before
being bonded on ceramic multilayer substrate 10, the metal layer is
treated to form first wiring layer 547 by employing a process such
as etching. Further, sheet 520 is provided with a first opening
only extending through first insulating adhesive layer 524 and the
hole is filled with conductive resin 567. Since the steps of
forming the first opening and filling it with conductive resin 567
may be carried out in the same fashion as those of the second
embodiment, their description is omitted.
[0104] Sheet 520 fabricated in the manner above is properly aligned
and bonded on ceramic multilayer substrate 10 as shown in FIG. 13B
while an electrical connection between top surface wiring layer 18
and conductive resin 567 is established simultaneously. Since this
process can be carried out in the same manner as that of the second
embodiment, its description is omitted. As a result of boding sheet
520, a circuit module having a single-layer resin wiring substrate
can be obtained. While the single-layer resin wiring substrate can
be used as a part of the circuit module, it can also be used after
an electronic component such as a capacitor, a resistor, an
inductor or an IC is surface mounted on first wiring layer 547.
[0105] In the fourth embodiment, the method of stacking a
multilayer resin wiring substrate on a ceramic multilayer substrate
is also described. FIGS. 14A and 14B show a method of fabricating a
circuit module having multilayer resin wiring substrate 720 formed
of stacking sheet 620, which is stacked on sheet 520 shown in FIG.
13B. Stacking sheet 620 is composed of a second metal layer formed
on second insulating adhesive layer 624. The second metal layer is
treated to form second wiring layer 647 by employing a process such
as etching. Further, second insulating adhesive layer 624 is
provided with a second opening at a predetermined place and the
opening is filled with conductive resin 667. Stacking sheet 620 can
be fabricated in the same manner as sheet 520.
[0106] As shown in FIG. 14B, stacking sheet 620 fabricated in this
manner is bonded after properly aligning its conductive resin 667
with first wiring layer 547 of sheet 520 on ceramic multilayer
substrate 10 while first wiring layer 547 becomes electrically
connected to conductive resin 667 simultaneously. Since this
process can be carried out in the same fashion as the bonding
process of sheet 520, its description is omitted. As a result of
bonding stacking sheet 620, a circuit module having multilayer
resin wiring substrate 720 can be obtained. While the stacking
sheet can be used as a part of the circuit module, it can also be
used after an electronic component such as a capacitor, a resistor,
an inductor or an IC is surface mounted on second wiring layer
647.
[0107] Fifth Embodiment
[0108] A method of fabricating a circuit module in accordance with
a fifth embodiment of the present invention will be described with
reference to FIGS. 15A to 16B. As can be seen from FIGS. 15A to
15C, the method of circuit module fabrication of this embodiment is
characterized by fabricating first wiring layer 548, and then
forming a first opening 568 which extends through first wiring
layer 548 and first insulating adhesive layer 526 and subsequently
bonding sheet 530 on ceramic multilayer substrate 10 on which IC 30
is mounted, and finally, filling first opening 568 with conductive
resin 569.
[0109] FIGS. 15A to 15C are cross-sectional views illustrating a
method of fabricating a circuit module having a single layer resin
wiring substrate. As shown in FIG. 15A, sheet 530 used is composed
of a first metal layer formed of, for example, a copper film, and
first insulating adhesive layer 526 while first wiring layer 548 is
formed by employing a process such as etching, on the first metal
layer. Further, first wiring layer 548 is provided at a
predetermined place with first opening 568 which extends through
first insulating adhesive layer 526. This process can be carried
out in the same manner as in the first embodiment.
[0110] FIG. 15B is a cross-sectional view illustrating sheet 530
bonded on ceramic multilayer substrate 10 on which IC 30 is
mounted. This bonding process can also be carried out in the same
fashion as in the first embodiment.
[0111] Thereafter, as shown in FIG. 15C, first opening 568 is
filled with conductive resin 569 so that top surface wiring layer
18 of ceramic multilayer substrate 10 can establish electrical
connection with first wiring layer 548 of sheet 530, thereby
obtaining a circuit module having a single layer resin wiring
substrate. While the single-layer resin wiring substrate can be
used as a part of the circuit module, it can also be used after an
electronic component such as a capacitor, a resistor, an inductor
or an IC is surface mounted on second wiring layer 548.
[0112] In this embodiment, a method of stacking a multilayer resin
wiring substrate on a ceramic multilayer substrate is also
described.
[0113] FIGS. 16A and 16B are cross-sectional views illustrating a
method of fabricating a circuit module having multilayer resin
wiring substrate 730 composed of sheet 530 on which stacking sheet
630 is stacked. As shown in FIG. 16A, stacking sheet 630 is
fabricated in the same manner as sheet 530. Specifically, using
stacking sheet 630 composed of a second metal layer formed of, for
example, a copper film and second insulating adhesive layer 626,
the second metal layer is subjected to a process such as etching to
form second wiring layer 648. Further, second wiring layer 648 is
provided with second opening 668 extending through second
insulating adhesive layer 626 at a predetermined place. This
process carried out in the same fashion as in the first
embodiment.
[0114] Thereafter, as shown in FIG. 16B, first wiring layer 548 of
sheet 530 is bonded to second opening 668 of stacking sheet 630
after they are properly aligned, and then second opening 668 is
filled with a conductive resin 669 so that first wiring layer 548
of sheet 530 establishes electrical connection with second wiring
layer 648 of stacking sheet 630 by the conductive resin 669,
thereby obtaining a circuit module having a multilayer resin wiring
substrate 730. While the multilayer resin wiring substrate can be
used as a part of the circuit module, it can also be used as a
circuit module having an electronic component such as a capacitor,
a resistor, an inductor or an IC is surface mounted on second
wiring layer 648.
[0115] In this fabricating method, an opening may be formed not
only by a mechanical method such as drilling and punching, but also
by various other methods. For example, a predetermined place of a
metal layer is removed by etching, thereby having the opening only
extending through the metal layer, which is then bonded on a
ceramic multilayer substrate. After bonding, laser irradiation is
used to perforate the insulating adhesive layer so that the opening
extends through the lower layer. After forming the opening, it can
be filled with a conductive resin. Since a wiring layer is not
etched when an insulating adhesive layer is perforated by laser
irradiation, it is possible to process in accordance with the same
configuration of openings in the wiring layer in a self-alignment
manner so as to make the precision of the laser irradiation
rough.
[0116] Further, although the first to fifth embodiments illustrate
cases where only one IC is mounted on a cavity, the present
invention is not limited thereto. For example, an IC can be mounted
together with a passive device; otherwise, multiple ICs may be
mounted as well. In addition, there can be more than one
cavity.
[0117] Further, although these embodiments described thus far cases
where a resin wiring substrate has either a single-layer or
double-layer structure, the present invention is not limited
thereto. Even if a resin wiring substrate has a multilayer
structure, the same process is employed to fabricate such a module.
Moreover, with respect to a ceramic multilayer substrate, this
invention is not limited to the method of bonding two green sheets.
For instance, three or more green sheets can be bonded to each
other so that they can be used as a ceramic multilayer
substrate.
[0118] With a circuit module and method of fabricating same in
accordance with the present invention, since an electronic
component such as IC is mounted on a cavity of a ceramic multilayer
substrate while the cavity is planarized by using a thermosetting
resin before stacking a resin wiring substrate, it is possible to
form a wiring and to mount a electronic component on the cavity,
the capabilities not available in the prior art. Consequently, the
mounting density of electronic components is enhanced and the
connection between an IC and a chip capacitor can be established at
a minimum distance. Therefore, it is possible not only to operate
the IC at a high speed but also to obtain a circuit module
compatible with a high frequency. Further, when electronic
components including an IC are mounted, it is possible to diversify
application of the circuit module.
[0119] While the invention has been shown and described with
respect to the preferred embodiments, it will be understood by
those skilled in the art that various changes and modifications may
be made without departing from the spirit and scope of the
invention as defined in the following claims.
* * * * *