U.S. patent application number 10/123162 was filed with the patent office on 2002-10-31 for method of producing ceramic multilayer substrate.
This patent application is currently assigned to Murata Manufacturing Co., Ltd.. Invention is credited to Kato, Isao, Kumano, Atsushi, Mandai, Harufumi, Sakai, Norio.
Application Number | 20020157760 10/123162 |
Document ID | / |
Family ID | 26396474 |
Filed Date | 2002-10-31 |
United States Patent
Application |
20020157760 |
Kind Code |
A1 |
Mandai, Harufumi ; et
al. |
October 31, 2002 |
Method of producing ceramic multilayer substrate
Abstract
There is disclosed a method of producing a ceramic multilayer
substrate by laminating a plurality of glass-ceramic green sheets
made of a glass-ceramic containing an organic binder and a
plasticizer to form a laminate; and firing the laminate; further
comprising: applying to or overlaying on the surfaces of the
glass-ceramic green sheets inorganic compositions, the sintering
temperature of the inorganic compositions being higher than that of
the glass-ceramic green sheets; laminating a plurality of the
glass-ceramic green sheets having the inorganic compositions
applied to or overlaid on the surfaces of the glass-ceramic green
sheets respectively, to form a part of the laminate; and laminating
a plurality of the glass-ceramic green sheets to form the other
part of the laminate.
Inventors: |
Mandai, Harufumi;
(Takatsuki-shi, JP) ; Sakai, Norio; (Moriyama-shi,
JP) ; Kato, Isao; (Shiga-ken, JP) ; Kumano,
Atsushi; (Shiga-ken, JP) |
Correspondence
Address: |
DICKSTEIN SHAPIRO MORIN & OSHINSKY, LLP
1177 Avenue of the Americas
New York
NY
10036
US
|
Assignee: |
Murata Manufacturing Co.,
Ltd.
|
Family ID: |
26396474 |
Appl. No.: |
10/123162 |
Filed: |
April 17, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10123162 |
Apr 17, 2002 |
|
|
|
09504919 |
Feb 16, 2000 |
|
|
|
Current U.S.
Class: |
156/89.12 ;
156/89.16; 257/E23.062 |
Current CPC
Class: |
H05K 2201/0195 20130101;
H05K 3/4629 20130101; H01L 23/49822 20130101; H01L 2924/01078
20130101; H01L 2924/15153 20130101; H01L 2224/16 20130101; Y10T
428/2495 20150115; H01L 2924/19105 20130101; Y10T 29/49163
20150115; H01L 2224/0401 20130101; H01L 2924/09701 20130101; H01L
21/4857 20130101; H01L 2924/01012 20130101; H01L 2224/16235
20130101; Y10T 428/24917 20150115; Y10T 156/1056 20150115; H01L
2924/01046 20130101; Y10T 428/24926 20150115; H01L 2924/00014
20130101; H05K 1/0306 20130101; H01L 2924/1517 20130101; H01L
2924/00014 20130101; Y10T 428/24959 20150115; Y10T 428/24942
20150115 |
Class at
Publication: |
156/89.12 ;
156/89.16 |
International
Class: |
C03B 029/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 3, 1999 |
JP |
11-55582 |
Oct 28, 1999 |
JP |
11-307083 |
Claims
What is claimed is:
1. A method of producing a ceramic multilayer substrate which
comprises laminating a plurality of ceramic green sheets to form a
laminate and firing the laminate; wherein at least one surface of
at least one ceramic green sheet has a layer of inorganic
composition whose sintering temperature is higher than that of the
glass-ceramic green sheet thereon.
2. The method according to claim 1, wherein one of the ceramic
green sheets has a smaller thickness than composition layer thereon
and said one sheet is positioned so as to be an outermost layer of
the laminate.
3. The method according to claim 2, wherein said one ceramic green
sheet having a smaller thickness is positioned so the inorganic
composition thereon is disposed in the interior of the
laminate.
4. The method according to claim 1, wherein a plurality of ceramic
green sheets having said inorganic composition layer thereon are
positioned adjacent to one another to form said laminate.
5. The method according to claim 4, wherein at least one ceramic
green sheet does not have said inorganic composition layer thereon
is employed in forming said laminate.
6. The method according to claim 1, wherein two ceramic green
sheets having a smaller thickness than each of the other ceramic
green sheets are positioned so as to be the two outermost layers of
the laminate.
7. The method according to claim 1, including the step of
positioning a plurality of the ceramic green sheets have an opening
therein such that the openings aline to form a cavity in said
laminate.
8. The method according to claim 1, wherein the inorganic
composition comprises alumina.
9. The method according to claim 1, wherein each inorganic
composition layer on a ceramic green sheet has a thickness of from
about 1 to 20 .mu.m.
10. The method according to claim 1, wherein each inorganic
composition layer on a ceramic green sheet has a thickness of from
1 to 10 .mu.m.
11. The method according to claim 1, wherein the ceramic green
sheet and inorganic composition are selected such that the
difference between the sintering temperature of the ceramic green
sheets and the sintering temperature of the inorganic composition
is at least about 100.degree. C.
12. The method according to claim 1, including the steps of first
forming one of a ceramic green sheet or an inorganic composition
layer on a carrier film, and then forming the other of the ceramic
green sheet and inorganic composition layer on the first formed
layer.
13. The method according to claim 12, including the steps of
forming a perforation through each of the carrier film, the ceramic
green sheet and the inorganic composition layer, introducing a
conductor material into the perforation to produce a filled
viahole; forming a conductor pattern on the inorganic composition
layer in electrical communication with the conductor material in
said viahole; separating the ceramic green sheet having the viahole
and the inorganic composition layer from the carrier film, and
laminating the glass-ceramic green sheet thus obtained.
14. The method according to claim 12, including the steps of
forming a perforation through each of the carrier film, the ceramic
green sheet and the inorganic composition, separating the ceramic
green sheet having the perforation and the inorganic composition
layer from the carrier film, and positioning the ceramic green
sheet thus obtained adjacent to a glass-ceramic green sheet having
a viahole filled with a conductor material during said lamination
step.
15. The method according to claim 1, including the steps of forming
one of said plurality of ceramic green sheets so as to have a
smaller thickness than each of the other ceramic green sheets and
forming an inorganic composition layer on the surface of said
ceramic green sheet having smaller thickness.
16. The method according to claim 1, including the step of
laminating a ceramic green sheet as the uppermost layer of the
laminate.
17. The method according to claim 1, wherein each of the ceramic
green sheets comprise glass-ceramic, organic binder and
plasticizer.
18. The method according to claim 17, wherein two ceramic green
sheets having a smaller thickness than each of the other ceramic
green sheets are positioned so as to be the two outermost layers of
the laminate and wherein the ceramic green sheet and inorganic
composition are selected such that the difference between the
sintering temperature of the ceramic green sheets and the sintering
temperature of the inorganic composition is at least about
100.degree. C.
19. The method according to claim 18, including the step of
positioning a plurality of the ceramic green sheets having said
inorganic composition layer thereon and having an opening therein
such that the openings aline to form a cavity in said laminate and
at least a part of the cavity surface comprises an inorganic
composition layer.
20. The method according to claim 19, wherein the inorganic
composition comprises alumina and wherein each inorganic
composition layer on a ceramic green sheet has a thickness of from
about 1 to 20 .mu.m.
21. The method according to claim 1, wherein the lamination is
effected such that the layer of inorganic material is sandwiched
between ceramic green sheets.
22. The method according to claim 21, wherein the lamination is
effected such that the layer of inorganic material does not
constitute an outermost layer of the resulting laminate.
23. The method according to claim 21, wherein one of the ceramic
green sheets has a smaller thickness than each of the other ceramic
green sheets and has said inorganic composition layer thereon.
24. A ceramic multilayer substrate comprising a laminate comprising
a plurality of ceramic green sheets, and a layer of inorganic
composition having a sintering temperature higher than that of the
ceramic green sheets disposed between a pair of ceramic green
sheets and not constituting an outermost layer of the laminate.
25. A ceramic multilayer substrate according to claim 24, having a
cavity extending from an outermost surface of the laminate to the
layer of inorganic composition and exposing the layer of inorganic
composition to the interior of the cavity.
26. A ceramic multilayer substrate comprising: a laminate
comprising: a plurality of green ceramic sheets; a cavity having
side surfaces and a bottom surface in the plurality of green
ceramic sheets, and a layer of an inorganic composition having a
sintering temperature higher than that of the green ceramic sheets,
wherein the layer of inorganic composition is disposed between two
of the green ceramic sheets and the layer of inorganic composition
is exposed at side surfaces and the bottom surface of the cavity.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This is a divisional of U.S. patent application Ser. No.
09/504,919, filed Feb. 16, 2000.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method of producing a
ceramic multilayer substrate on which semiconductor LSI, a chip
components, or the like are mounted and wired to each other.
[0004] 2. Description of the Related Art
[0005] Japanese Unexamined Patent Publication No. 5-102666
discloses a conventional method of producing a ceramic multilayer
substrate. According to this production method, as shown in FIG. 1,
plural glass-ceramic green sheets made of a glass-ceramic,
containing an organic binder and a plasticizer, and having a
conductor pattern (not illustrated) formed on the surfaces thereof
by use of a conductor paste composition are first laminated to form
a laminate 101. Next, ceramic green sheets 102 and 103 containing
as a major component an inorganic composition having a sintering
temperature higher than that of the glass-ceramic green sheet 101
are formed on the back and front sides of the laminate 101,
respectively, and thereafter, pressure-bonded together to form a
lamination pressure-bonding body 100. Next, the lamination
pressure-bonding body 100 is fired under the firing conditions for
the laminate 101. Thereafter, the unsintered ceramic green sheets
102 and 103 are removed, whereby a ceramic multilayer substrate is
obtained. The laminate 101 is inhibited from heat shrinking in the
plane direction at firing, owing to the ceramic green sheets 102
and 103 of the lamination pressure-bonding body 100.
[0006] Such a conventional method of producing a ceramic multilayer
substrate has the following problems.
[0007] When the number of the laminated glass-ceramic green sheets
becomes large, and the thickness of the laminate 101 is increased,
the vicinities of the ceramic green sheets 102 and 103, that is,
the vicinities of the front and back sides of the laminate 101 are
inhibited from heat shrinking in the plane direction. However,
there have been some cases that the central portion 104 in the
thickness direction of the laminate 101 is distorted so as to be
depressed toward the inside thereof as shown in FIG. 2. There has
been a danger that such distortion 104' causes the inside of the
laminate 101 to because cracked and the glass-ceramic green sheets
to peel away from each other.
[0008] In the case that a cavity for accommodating an electronic
component, not illustrated, is formed in the laminate 101, it has
been difficult to provide a ceramic green sheet for inhibiting heat
shrinkage on the bottom of the cavity.
SUMMARY OF THE INVENTION
[0009] To overcome the above described problems, preferred
embodiments of the present invention provides a method of producing
a ceramic multilayer substrate in which the side faces of the
laminate can be prevented from being distorted so as to be
depressed toward the inside thereof, caused by the heat shrinkage
at firing. In addition, it is an object of the present invention to
provide a method of producing a ceramic multilayer substrate in
which an inorganic composition for inhibiting the heat shrinkage
can be easily provided on the bottom of a cavity in the
laminate.
[0010] One preferred embodiment of the present invention provides a
method of producing a ceramic multilayer substrate by lamination of
plural glass-ceramic green sheets made of a glass-ceramic
containing an organic binder and a plasticizer to form a laminate,
and firing of the laminate comprises the step of applying to or
overlaying on the surfaces of the glass-ceramic green sheets
inorganic compositions having a higher sintering temperature than
the glass-ceramic green sheets, the step of laminating a plurality
of the glass-ceramic green sheets having the inorganic compositions
applied to or overlaid on the surfaces of the glass-ceramic green
sheets to form a part of the laminate, and the step of laminating a
plurality of the glass-ceramic green sheets to form the other part
of the laminate.
[0011] The above described method may include the step of forming
one of the glass-ceramic green sheets so as to have a smaller
thickness than each of the other glass-ceramic green sheets, the
step of applying to or overlaying on the surface of the
glass-ceramic green sheet having a smaller thickness the inorganic
composition, the step of arranging the glass-ceramic green sheet
having a smaller thickness as the undermost layer of the laminate,
and the step of laminating a plurality of the glass-ceramic green
sheets having the inorganic compositions applied to or overlaid on
the surfaces thereof, whereby a part of or the whole of the
laminate ranging from the vicinity of the undermost layer to the
uppermost layer is formed.
[0012] The above described method may include the step of
laminating a plurality of the glass-ceramic green sheets having the
inorganic compositions provided on the surfaces thereof, whereby a
part of or the whole of the laminate ranging from the undermost
layer to the vicinity of the uppermost layer is formed, and the
step of laminating the glass-ceramic green sheet as the uppermost
layer of the laminate.
[0013] Moreover, the method may include the step of forming the
glass-ceramic green sheets to constitute the undermost and
uppermost layers of the laminate so as to have a smaller thickness
than the respective glass-ceramic green sheets to constitute the
other layers of the laminate.
[0014] Further, the method may include the step of forming opening
portions through a plurality of the glass-ceramic green sheets
arranged as the uppermost layer of the laminate and in its
vicinities and also the inorganic compositions applied to or
overlaid on the glass-ceramic green sheets, and the step of
laminating a plurality of the glass-ceramic green sheets having the
opening portions formed therein to form the laminate having a
cavity formed of the opening portions of the plural glass-ceramic
green sheets which are made continuous to each other.
[0015] In the above described method, the inorganic compositions
applied to or overlaid on the glass-ceramic green sheets may
contain alumina as a major component.
[0016] Further, each of the inorganic compositions applied to or
overlaid on the glass-ceramic green sheets may have a thickness of
from about 1 to 20 .mu.m.
[0017] Furthermore, the differences between the sintering
temperatures of the glass-ceramic green sheets and the sintering
temperatures of the inorganic compositions applied to or overlaid
on the glass-ceramic green sheets is at least about 100.degree.
C.
[0018] Further, the above described method may include the step of
forming a glass-ceramic green sheet on a carrier film, and then
applying to or overlaying on the glass-ceramic green sheet the
inorganic composition to form an inorganic composition layer, the
step of forming a perforation through each of the carrier film, the
glass-ceramic green sheet and the inorganic composition layer,
filling a conductor material into the perforation to produce a
viahole, and further forming a conductor pattern on the inorganic
composition layer, and the step of releasing the glass-ceramic
green sheet having the viahole and the conductor pattern, together
with the inorganic composition layer, from the carrier film and
laminating the glass-ceramic green sheets with the inorganic
composition layers, sequentially.
[0019] Further, the method may include the step of applying to or
overlaying on a carrier film the inorganic composition to form an
inorganic composition layer, and then forming a glass-ceramic green
sheet on the inorganic composition layer, the step of forming a
perforation through each of the carrier film, the inorganic
composition layer and the glass-ceramic green sheet, then filling a
conductor material into the perforation to form a viahole, and
forming a conductor pattern on the glass-ceramic green sheet, and
the step of releasing the glass-ceramic green sheet having the
viahole and the conductor pattern, together with the inorganic
composition layer, from the carrier film and laminating the
glass-ceramic green sheets with the inorganic composition layers
sequentially.
[0020] Moreover, a glass-ceramic green sheet having a viahole and a
conductor pattern and a green sheet having a perforation not filled
with a conductor material, corresponding to the viahole and
containing the inorganic composition as a major component may be
laminated to form a part of the laminate.
[0021] According to the method of producing a ceramic multilayer
substrate of the present invention, the glass-ceramic green sheets
and the inorganic compositions having a higher sintering
temperature than the respective glass-ceramic green sheets are
alternately arranged to form a laminate, and fired. Owing to the
inorganic compositions, the glass-ceramic green sheets constituting
not only the undermost and uppermost layers of the laminate but
also the internal layers are inhibited from heat shrinking in the
plane direction. Accordingly, there is little danger that
distortion of the laminate occurs at firing, that is, the side
faces of the laminate are distorted so as to be depressed toward
the inside. Therefore, the generation of cracks and the peeling of
the glass-ceramic green sheets are prevented. The production of a
high precision ceramic multilayer substrate is enabled.
[0022] By forming the undermost layer of the laminate, or the
undermost and uppermost layers thereof with the glass-ceramic green
sheets, the sintered glass-ceramics after the laminate is fired can
be used as the mounting surfaces of the ceramic multilayer
substrate. Accordingly, the mounting surfaces are stable, and the
ceramic multilayer substrate can be mounted without fail as
compared with the surfaces made of unsintered inorganic
compositions.
[0023] By forming the glass-ceramic green sheets constituting the
undermost or uppermost layer of the laminate or both of them so as
to have a smaller thickness than the respective glass-ceramic green
sheets constituting the other layers of the laminate, the amount of
change caused by heat shrinkage of the respective layers can be
made equal to each other. Accordingly, the peeling or the
generation of cracks can be prevented from occurring between the
glass-ceramic green sheets.
[0024] Further, the inorganic composition having a higher sintering
temperature than the glass-ceramic green sheet is exposed on the
bottom of the cavity formed in the laminate. Accordingly, it is
unnecessary to provide an inorganic composition on the bottom of
the cavity after the cavity is formed. The bottom of the cavity can
be simply protected from heat shrinking at firing.
[0025] Since the inorganic compositions having a higher sintering
temperature than the respective glass-ceramic green sheets are
arranged inside of the laminate, the unsintered inorganic
compositions function as a buffering material against vibration,
impact and thermal shock. Accordingly, cracks or breaks fatal to
the laminate are not generated.
[0026] Since the glass-ceramic green sheets constituting the
laminate and the inorganic compositions for inhibiting the heat
shrinkage at firing have different sintering temperatures, the
co-firing of the whole laminate is possible, and the simplification
of the manufacturing process and the reduction of the manufacturing
cost can be realized.
[0027] In the case that the materials for use in the inorganic
composition to inhibit the heat shrinkage include no glass, even
though the conductor constituting the internal electrodes is
diffused was firing of the laminate, caused by the plastic flow of
the glass-ceramic green sheets, diffusion can be inhibited owing to
the inorganic compositions for inhibiting the heat shrinkage.
[0028] Other features and advantages of the present invention will
become apparent from the following description of the invention
which refers to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a cross section showing a laminate produced by a
conventional method of producing a ceramic multilayer
substrate.
[0030] FIG. 2 is a cross section showing the state that the
laminate as shown in FIG. 1 is distorted.
[0031] FIG. 3 is a schematic cross section of a glass-ceramic green
sheet 2c formed on a carrier film 1 in a first embodiment of the
present invention.
[0032] FIG. 4 is a schematic cross section showing an inorganic
composition layer 3c further formed in the above embodiment.
[0033] FIG. 5 is a schematic cross section showing a viahole 4c
further formed in the above embodiment.
[0034] FIG. 6 is a schematic cross section showing a conductor
pattern 5c further formed in the above embodiment.
[0035] FIG. 7 consists of schematic cross sections showing the
state that the respective glass-ceramic green sheets are laminated
in the above embodiment.
[0036] FIG. 8 is a schematic cross section of a lamination
pressure-bonding body 10 in the above embodiment.
[0037] FIG. 9 is a schematic cross section of a sintered body
(ceramic multilayer substrate) obtained after the lamination
pressure-bonding body is fired.
[0038] FIG. 10 is a schematic cross section of a ceramic multilayer
module 20 according to the present invention.
[0039] FIG. 11 is a schematic cross section of a ceramic multilayer
substrate 40 having a cavity 36 according to a second embodiment of
the present invention.
[0040] FIG. 12 is a schematic cross section showing an inorganic
composition layer 52c formed on a carrier film 51 in the third
embodiment of the present invention.
[0041] FIG. 13 is a schematic cross section showing a glass-ceramic
layer 53c formed in the above embodiment.
[0042] FIG. 14 is a schematic cross section showing viahole 54c
further formed in the above embodiment.
[0043] FIG. 15 is a schematic cross section showing a conductor
pattern 55c formed in the above embodiment.
[0044] FIG. 16 is a schematic cross section showing the state that
the glass-ceramic layers are laminated in the above embodiment.
[0045] FIG. 17 is a schematic cross section of a lamination
pressure-bonding body 60.
[0046] FIG. 18 is a schematic cross section of a ceramic multilayer
substrate 70 according to a fourth embodiment of the present
invention.
[0047] FIG. 19 is a schematic cross section showing a manufacturing
process for a ceramic multilayer substrate according to a fifth
embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
First Embodiment
[0048] A method of producing a ceramic multilayer substrate
according to a first embodiment of the present invention is
described by use of the drawings. In this embodiment, for the
inorganic composition layers comprising an inorganic composition
having a higher sintering temperature than the respective
glass-ceramic green sheets, a paste (slurry) made of an inorganic
oxide composition containing alumina as a major component is
applied to the surfaces of the respective glass-ceramic green
sheets constituting a laminate. Hereinafter, this will be described
in the order of formation.
[0049] (1) Formation of Glass-Ceramic Green Sheet
[0050] First, a glass-ceramic green sheet is formed as follows. A
glass-ceramic which consists of a composition comprising lead
borosilicate glass powder and alumina powder at a ratio by weight
of 50:50 is added to an organic binder comprising polyvinylbutyral,
a plasticizer comprising di-n-butylphthalate, and a solvent
produced by mixing toluene and isopropyl alcohol at a ratio by
weight of 30:70, and mixed to form slurry. Next, the slurry is
sheet-formed on a carrier film 1 by the doctor-blade method as
shown in FIG. 3, and dried to form a glass-ceramic green sheet
2c.
[0051] (2) Formation of Inorganic Composition Layer
[0052] As shown in FIG. 4, an inorganic composition layer 3c is
formed on the glass-ceramic green sheet 2c which is formed on the
carrier film 1. The inorganic composition layer 3c is formed by
applying a paste (slurry) to the surface of the glass-ceramic green
sheet 2c and drying, the paste being produced by adding alumina
powder to an organic binder comprising polyvinylbutyral, a
plasticizer comprising di-n-butylphthalate, and a solvent produced
by mixing toluene and isopropyl alcohol at a ratio by weight of
30:70, and mixing them.
[0053] The alumina has a higher sintering temperature than the
glass-ceramic green sheet 2c. The inorganic composition layer 3c
containing the alumina as a major component has a higher sintering
temperature than the glass-ceramic green sheet 2c. That is, the
inorganic composition layer 3c can not be sintered under the
sintering conditions for the glass-ceramic green sheet 2c.
[0054] Zirconium oxide, aluminum nitride, boron nitride, mullite,
magnesium oxide, silicon carbide, or the like, may be substituted
for alumina used as a material for the inorganic composition layer
3c.
[0055] (3) Formation of Viahole
[0056] Next, formed are perforations through each of the carrier
film 1, the glass-ceramic green sheet 2c and the inorganic
composition layer 3c by means of a perforator. Into the
perforations, a conductor material (conductor paste) is filled by
screen printing or the like, whereby a viahole 4c is formed through
the carrier film 1, the glass-ceramic green sheet 2c and the
inorganic composition layer 3c, as shown in FIG. 5.
[0057] For use as the conductor paste, a vehicle comprising ethyl
cellulose as an organic binder dissolved in terpineol is added to
an inorganic component comprising 5 weight parts of glass frit and
100 weight parts of silver powder. Powders of copper,
silver/palladium or silver/platinum or the like may be substituted
for the silver powder used as an inorganic component of the
conductor paste.
[0058] (4) Formation of Conductor Pattern
[0059] As shown in FIG. 6, a conductor paste is printed on the
inorganic composition layer 3c formed on the glass-ceramic green
sheet 2c by a screen printing method, whereby a conductor pattern
5c connecting to the viaholes 4c is formed.
[0060] The conductor pattern 5c may also be formed by use of metal
foil or a metallic wire. In this case, available are a method of
hot pressing a punched metal foil or metal wire against a ceramic
green sheet, or a method of forming a pattern on a resin film by
vapor deposition, sputtering, plating or the like, and heat
transferring the pattern onto a ceramic green sheet.
[0061] (5) Lamination
[0062] As shown in FIG. 7, a plurality of the glass-ceramic green
sheets 2c formed by the procedures (1) through (4) are peeled from
the carrier films 1, respectively. The glass-ceramic green sheets
2c, together with the glass-ceramic green sheets 2a, 2b, 2d
prepared by a technique similar to the above-described one, are
sequentially laminated, with the surface sides thereof where the
inorganic composition layer 3c and the conductor pattern 5c are
formed, being on the upper sides thereof.
[0063] In glass-ceramic green sheets 2b and 2d, the inorganic
composition layers 3b and 3d are formed on one of the main sides
thereof, similarly to the glass-ceramic green sheet 2c, viaholes 4b
and 4d are formed so as to perforate through the glass-ceramic
green sheets 2b and 2d, and the inorganic composition layers 3b and
3d, and conductor patterns 5b and 5d are formed on the surfaces of
the surfaces of the inorganic composition layers 3b and 3d,
respectively.
[0064] The glass-ceramic green sheet 2a constituting the undermost
layer of the ceramic multilayer substrate, and the glass-ceramic
green sheet 2e constituting the uppermost layer of the ceramic
multilayer substrate each have a thickness which is smaller than
the glass-ceramic green sheets 2b, 2c, 2d or the like constituting
the other layers. Further, as to the glass-ceramic green sheet 2a,
after the carrier film is released, a conductor pattern 8 to
function as a surface electrode is also formed on the back side
thereof where the inorganic composition layer 3a is not provided
and a conductor patterns 5a is formed on the front side and the two
conductors are interconnected by viahole 4a. The conductor pattern
8 to function as a surface electrode may also be formed by printing
the conductor pattern and baking after the ceramic multilayer
substrate is fired. The glass-ceramic green sheet 2e constituting
the uppermost layer of the ceramic multilayer substrate with a
conductor pattern 7 and viahole 4e are formed in compliance with
the procedures for producing ordinary glass-ceramic green sheets
without the inorganic composition layer being formed thereon.
[0065] (6) Pressure-Bonding
[0066] The glass-ceramic green sheets 2a through 2e are hot
pressure-bonding under the conditions of a temperature of
80.degree. C. and a pressure of 200 kg/cm.sup.2, for example, to
form a lamination pressure-bonded body. Hereupon, the glass-ceramic
green sheets 2a through 2e are bonded to the inorganic composition
layers 3a through 3d, owing to the anchor effects and so forth.
[0067] FIG. 8 shows the lamination pressure-bonded body formed as
described above. In this figure, reference numeral 10 designates
the lamination pressure-bonded body, in which the glass-ceramic
green sheets 2a through 2e and the inorganic composition layers 3a
through 3d are alternately arranged, and the conductor patterns 7
and 8 formed on the front and back sides thereof to function as
surface electrodes and the conductor patterns 5a through 5d
provided between the respective layers to function as internal
electrodes are connected to each other through viaholes 4a through
4e.
[0068] As to each of the glass-ceramic green sheets 2b through 2d
constituting the lamination pressure-bonded body 10, the opposite
sides thereof are coated with the inorganic composition layers 3a
through 3d. The glass-ceramic green sheet 2a constituting the
undermost layer of the lamination pressure-bonded body 10, and the
glass-ceramic green sheet 2e constituting the uppermost layer have
a smaller thickness than the glass-ceramic green sheets 2b through
2d of the other layers.
[0069] (7) Firing
[0070] The lamination pressure-bonded body 10 is fired in the air
or in the nitrogen atmosphere under the conditions of a temperature
of 900.degree. C. and 1 hour, for example. On this occasion, the
glass-ceramic green sheets constituting the lamination
pressure-bonded body 10 are allowed to heat-shrink in the x, y, and
z directions. However, the glass-ceramic green sheets are
"restrained" by the inorganic composition layers 3a through 3d,
which are arranged alternately with the glass-ceramic green sheets.
Accordingly, as shown in FIG. 9, the heat shrinkage in the plane
direction (x-y direction) is restrained, and the green sheets
considerably shrunk only in the thickness direction (2 direction).
That is, the glass-ceramic green sheets 2a through 2e as shown in
FIG. 8 considerably shrink in the thickness direction to become the
glass-ceramic bodies 2a' through 2e' in the sintered body (ceramic
multilayer substrate) 11 as shown in FIG. 9.
[0071] It is speculated that the restraint is brought about as
follows. First, the glass components of the glass-ceramic green
sheets 2a through 2e are diffused and permeated into the inorganic
composition layers 3a through 3d at firing. Thus, the glass-ceramic
green sheets 2a through 2e are strongly bonded to the inorganic
composition layers 3a through 3d before the glass-ceramic green
sheets 2a through 2e substantially start to shrink. Further, at the
time when the glass-ceramic green sheets 2a through 2e
substantially start to shrink, that is, under the firing conditions
of the glass-ceramic green sheets 2a through 2e, the sintering of
the inorganic composition layers 3a through 3d does not
proceed.
[0072] Not only the vicinities of the undermost and uppermost
layers of the lamination pressure-bonded body 10, but also the
glass-ceramic green sheets 2b through 2d constituting the internal
layers, are inhibited from heat shrinking in the plane direction
owing to the effects of the inorganic composition layers 3a through
3d. Accordingly, there is no danger that the lamination
pressure-bonded body 10 is distorted at firing, especially the side
faces thereof being distorted so as to be depressed toward the
inside thereof. Accordingly, the generation of cracks and the
peeling of the glass-ceramic green sheets 2a through 2e are
prevented. Thus, the production of a high precision ceramic
multilayer substrate 11 can be produced.
[0073] Further, the heat shrinkage restraining degrees of the
respective glass-ceramic green sheets 2a and 2e are small compared
with the glass-ceramic green sheets 2b, 2c and 2d since for each of
the glass-ceramic green sheets 2a and 2e, only one of the main
faces thereof is contacted with the inorganic composition layer.
However, since the thicknesses of the glass-ceramic green sheets 2a
and 2e are smaller than those of the glass-ceramic green sheets 2b,
2c and 2d, respectively, the amount of change caused by the heat
shrinkage are small. The thicknesses of the glass-ceramic green
sheets 2a and 2e are adjusted so that the amount of change caused
by heat shrinkage of the glass-ceramic green sheets 2a and 2e
become equal to those of the glass-ceramic green sheets 2b, 2c and
2d. From such a viewpoint, each thickness of the respective
glass-ceramic green sheets of the uppermost and undermost layers is
about 0.1-0.9 times, preferably about 0.3-0.7 times, that of the
other glass-ceramic green sheets.
[0074] As described above, the amount of change caused by heat
shrinkage in the method of producing a ceramic multilayer substrate
according to the first embodiment of the present invention, between
the glass-ceramic green sheets 2a and 2b, between the glass-ceramic
green sheets 2b and 2c, between the glass-ceramic green sheets 2c
and 2d, and between the glass-ceramic green sheets 2d and 2e are
essentially equal to each other. Accordingly, a high precision
ceramic multilayer substrate can be attained in which peeling
between the respective glass-ceramic green sheets and the
generation of cracks are prevented, and moreover warp and
distortion are reduced.
[0075] The ceramic multilayer substrate 11 as shown in FIG. 9 can
be used as a substrate for a ceramic multilayer module 20 as shown
in FIG. 10, for example. The ceramic multilayer module 20 contains
a coil pattern, a capacitor pattern or the like, which is formed by
internal electrodes 15, viaholes 14, or the like, and includes a
substrate produced by alternately laminating glass-ceramic green
sheets 12 and inorganic composition layers 13. On one of the main
sides, semiconductor devices 19a and 19b, a chip monolithic
capacitor 19c, and so forth are mounted. Land electrodes 18 are
formed on the other main side.
[0076] The thicknesses of the glass-ceramic green sheets of the
uppermost and undermost layers may be substantially equal to those
of the other glass-ceramic green sheets in the ceramic multilayer
module 20. However, preferably, the thicknesses of the
glass-ceramic green sheets as the uppermost and undermost layers
are smaller than those of the other glass-ceramic green sheets,
similarly to the above-described ceramic multilayer substrate
11.
Second Embodiment
[0077] Hereinafter, a method of producing a ceramic multilayer
substrate according to a second embodiment of the present invention
will be described.
[0078] Basically, according to the same points as those of the
first embodiment, (1) the formation of glass-ceramic green sheets,
(2) the formation of inorganic composition layers, (3) the filling
of viaholes and (4) the formation of conductor patterns are carried
out, whereby glass-ceramic green sheets 31a through 31h (FIG. 11)
having the surfaces coated with the inorganic composition layers
are formed.
[0079] Opening portions are formed in glass-ceramic green sheets
31e through 31h constituting the uppermost layer of the laminate
and its vicinities so as to perforate through the glass-ceramic
green sheets and the inorganic composition layers applied to or
overlaid on the glass-ceramic green sheets by use of a perforator.
The opening portions of the respective glass-ceramic green sheets
are formed at positions corresponding to each other. In this
embodiment, the opening portions are formed in the centers of the
glass-ceramic green sheets.
[0080] The glass-ceramic green sheets are laminated (5) to form a
laminate. FIG. 11 shows the laminate.
[0081] In this figure, the laminate 40 has the lamination structure
in which the glass-ceramic green sheets 31a through 31h and the
inorganic composition layers 32a through 32g are alternately
laminated. An external electrode 35a is provided on the surface on
the undermost layer side of the laminate 40, and external
electrodes 35b are formed on the surface on the uppermost layer
side. Further, inside of the laminate 40, a predetermined wiring
structure is formed by use of viaholes 33 and internal electrodes
34.
[0082] Opening portions are formed in the glass-ceramic green
sheets 31e, 31f, 31g and 31h arranged in the uppermost layer of the
laminate 40 and its vicinity. The opening portions are made
continuous to form a cavity 36. The bottom of the cavity 36 is
composed of the glass-ceramic green sheet 31d. The inorganic
composition layer 32d provided on the surface of the glass-ceramic
green sheet 31d is exposed as the bottom 37 of the cavity 36. A
surface electrode 35c is arranged on the inorganic composition
layer 32d so as to be connectable to mounted components, not
illustrated.
[0083] Next, the pressure-bonded (6) of the laminate 40 and firing
(7) are carried out. Hereupon, the bottom of the cavity 36 of the
laminate 40 is protected from heat shrinking by the inorganic
composition layer 32d, similarly to the other layers constituting
the laminate 40. Accordingly, the bottom has an excellent
flatness.
[0084] In this embodiment, as described above, the inorganic
composition layer 32d for inhibiting the heat shrinkage at firing
is exposed on the bottom of the cavity 36 formed in the laminate
40. Accordingly, it is unnecessary newly to provide a ceramic green
sheet or the like on the bottom of the cavity 36 after the cavity
36 is formed, and the bottom of the cavity 36 can be simply
protected from heat shrinking at firing. However, it should be
noted that the bottom of the cavity 36 may be formed in such a
manner that the glass-ceramic green sheet is exposed.
Third Embodiment
[0085] Next, a method of producing a ceramic multilayer substrate
according to a third embodiment of the present invention will be
described.
[0086] The method of producing a ceramic multilayer substrate of
this embodiment will be described sequentially in the order of the
working items by use of the drawings.
[0087] (1) Formation of Inorganic Composition Layer
[0088] First, a paste (slurry) is prepared by adding alumina powder
to an organic binder comprising polyvinylbutyral, a plasticizer
comprising di-n-butylphthalate, and a solvent produced by mixing
toluene and isopropyl alcohol at a ratio by weight of 30:70, and
mixing them. Subsequently, as shown in FIG. 12, with the paste, a
sheet is formed on a carrier film 51 by the doctor blade method or
the like, and dried whereby an inorganic composition layer (ceramic
green sheet) 52c is formed.
[0089] The alumina has a higher sintering temperature than the
respective glass-ceramic green sheets described later. An inorganic
composition layer 52c containing the alumina as a major component
has a higher sintering temperature than the respective
glass-ceramic green sheets. That is, the inorganic composition
layer 52c can not be sintered under the sintering conditions for
the glass-ceramic green sheets. Similarly to the above-described
case, zirconium oxide, aluminum nitride, boron nitride, mullite,
magnesium oxide, silicon carbide or the like can be substituted for
alumina used as a material for the inorganic composition layer
52c.
[0090] (2) Formation of Glass-Ceramic Green Sheet
[0091] As shown in FIG. 13, a glass-ceramic green sheet
(glass-ceramic layer) 53c is formed on an inorganic composition
layer 52c which is formed on the carrier film 51. The glass-ceramic
layer 53c is produced by shaping a slurry on the inorganic
composition layer 52c by the doctor blade method, and drying. The
slurry is produced by adding to an organic binder comprising
polyvinylbutyral or the like, a plasticizer comprising
di-n-butylphthalate or the like, and a solvent produced e.g. by
mixing toluene and isopropyl alcohol at a ratio by weight of 30:70,
a glass-ceramic which is a composition comprising lead borosilicate
glass powder and alumina powder at a ratio by weight of 50:50, and
mixing them.
[0092] (3) Formation of Viahole
[0093] Next, formed are perforations through each of the carrier
film 51, the inorganic composition layer 52c and the glass-ceramic
layer 53c by means of a perforator. Into the perforations, a
conductor material (conductor paste) is filled by a screen printing
method or the like, whereby a viahole 54c is formed through each of
the carrier film 51, the inorganic composition layer 52c and the
glass-ceramic layer 53c, as shown in FIG. 14.
[0094] Hereupon, for use as the conductor paste, similarly to the
above-described case, a vehicle comprising ethyl cellulose as an
organic binder dissolved in terpineol is added to an inorganic
component comprising 5 parts by weight of glass frit and 100 parts
silver powder. Powder of copper, silver/palladium, silver/platinum
or the like can be substituted for the silver powder used as an
inorganic component of the conductor paste.
[0095] (4) Formation of Conductor Pattern
[0096] As shown in FIG. 15, the glass-ceramic layer 53c formed on
the inorganic composition layer 52c is printed with a conductor
paste by a screen printing method, whereby a conductor pattern 55c
connected to the viahole 54c is formed.
[0097] The conductor pattern 55c may be formed by use of metal foil
or a metallic wire, similarly to the above-described embodiments.
In this case, available are a method of hot pressing a punched
metal foil or a metal wire against a ceramic green sheet, or a
method of forming a pattern on a resin film by vapor deposition,
sputtering, plating, or the like, and heat transferring the pattern
onto a ceramic green sheet.
[0098] (5) Lamination
[0099] As shown in FIG. 16, a plurality of the glass-ceramic layer
53c formed by the procedures (1) through (4) are peeled from the
carrier films 51, and are laminated sequentially, together with the
glass-ceramic layers 53a, 53b, 53d and 53e which are prepared by a
technique similar to the above-described one with the surface side
thereof where the conductor pattern 55c is formed being the upper
side thereof.
[0100] That is, the inorganic composition layers 52b, 52d and 52e
are formed on the one-side main face of the respective
glass-ceramic layers 53b, 53d and 53e, similarly to the
glass-ceramic layer 53c. Further, formed are viaholes 54b, 54d and
54e perforating through each of the glass-ceramic layers and the
inorganic composition layers, to conductor patterns 55b, 55d and
55e.
[0101] The glass-ceramic layer 53a constituting the undermost layer
of the ceramic multilayer substrate, and the glass-ceramic layer
53e constituting the uppermost layer of the ceramic multilayer
substrate have a smaller thickness as compared with the
glass-ceramic layers 53b, 53c and 53d constituting the other
layers. Further, the glass-ceramic layer 53a, having no inorganic
composition layer formed thereon, is produced in compliance with
the preparation procedures for ordinary glass-ceramic green sheets.
A conductor pattern 55a to function as an internal electrode and a
conductor pattern 57 as an external electrode are printed on the
opposite sides and connected by viahole 54a.
[0102] (6) Pressure-Bonded
[0103] The glass-ceramic layer 53a, and the glass-ceramic layers
52b through 53e provided with the inorganic composition layers 52a
through 52d are heat pressure-bonded under the conditions of a
temperature of 80.degree. C. and a pressure of 200 kg/cm.sup.2, for
example, to form a lamination pressure-bonded body. Hereupon, the
glass-ceramic layers 53a through 53e and the inorganic composition
layers 52a through 52d are bonded to each other, attributed to an
anchor effect or the like.
[0104] FIG. 17 shows a lamination pressure-bonded body formed as
described above. In this figure, reference numeral 60 designates
the lamination pressure-bonded body in which the glass-ceramic
layers 53a through 53e and the inorganic composition layers 52a
through 52d are alternately arranged, and conductor patterns 57 and
55e formed on the front side and the back side function as surface
electrodes, and the conductor patterns 55a through 55d provided
between the respective layers to function as internal electrodes
are connected to each other through the viaholes 54a through
54e.
[0105] The opposite sides of the respective glass-ceramic layers
53b through 53d constituting the lamination pressure-bonded body 60
are coated with the inorganic composition layers 52a through 52d.
Further, the glass-ceramic layer 53a constituting the undermost
layer of the lamination pressure-bonded body 60, and the
glass-ceramic layer 53e constituting the uppermost layer, have a
smaller thickness as compared with the other layers, than is, the
glass-ceramic layers 53b through 53d.
[0106] (7) Firing
[0107] The lamination pressure-bonded body 60 is fired in the air
or in a nitrogen atmosphere under the conditions of a temperature
of 900.degree. C. and 1 hour, for example. On this occasion, the
glass-ceramic layers constituting the lamination pressure-bonded
body 60 are about to heat-shrink in the x, y, and z directions,
respectively. However, the glass-ceramic layers are "restrained" by
the inorganic composition layers 52a through 52d which are arranged
alternately with the glass-ceramic layers. Accordingly, the heat
shrinkage in the plane direction (x-y direction) is restrained, and
the green sheets considerably shrink only in the thickness
direction (z direction).
[0108] The heat shrinkage in the plane direction is prevented not
only in the vicinities of the undermost and uppermost layers of the
lamination pressure-bonded body 60 but also in the glass-ceramic
layers 53b through 53d constituting the internal layers because of
the effects of the inorganic composition layers 52a through 52d.
Accordingly, there is no danger that the distortion occurs at
firing, and especially, the side faces of the lamination
pressure-bonded body 60 being distorted so as to be depressed
toward the inside. Accordingly, the generation of cracks and the
peeling of the glass-ceramic layers 53a through 53e are prevented.
Thus, the production of a high precision ceramic multilayer
substrate is enabled.
[0109] Further, the heat shrinkage restraining degrees of the
respective glass-ceramic layers 53a and 53e are lower as compared
with the glass-ceramic layers 53b, 53c and 53d since each of the
glass-ceramic layers 53a and 53e is contacted with the inorganic
composition layer only on one main side thereof. However, the
change caused by the heat shrinkage are small since the thicknesses
of the glass-ceramic layers 53a and 53e are smaller than those of
the glass-ceramic layers 53b, 53c and 53d, respectively. That is,
the thicknesses of the glass-ceramic layers 53a and 53e are
adjusted so that the change by heat shrinkage of the glass-ceramic
layers 53a and 53e become equal to those of the glass-ceramic
layers 53b, 53c and 53d, respectively. From such a viewpoint, each
thickness of the glass-ceramic layer of the uppermost or undermost
layer, is about 0.1-0.9 times, preferably, about 0.3-0.7 times that
of the other glass-ceramic layers.
[0110] In the method of producing a ceramic multilayer substrate
according to the third embodiment of the present invention, the
change caused by heat shrinkage between glass-ceramic layers 53a
and 53b, between glass-ceramic layers 53b and 53c, between
glass-ceramic layers 53c and 53d, and between glass-ceramic layers
53d and 53e are essentially equal to each other. Accordingly, a
high precision ceramic multilayer substrate can be attained in
which peeling between the respective glass-ceramic layers, and the
deformation and the crack generation by heat shrinkage, are
prevented, and warp and distortion are reduced.
Fourth Embodiment
[0111] FIG. 18 shows a ceramic multilayer substrate of this
embodiment. The ceramic multilayer substrate 70 has the structure
in which glass-ceramic layers 71a through 71f and inorganic
composition layers 72a through 72g are alternately laminated.
Inside thereof, a capacitor pattern, a wiring pattern or the like
are formed by viaholes 73 and internal conductors 74, and on the
surface thereof, surface electrodes 75 are formed.
[0112] According to the method of producing a ceramic multilayer
substrate of the present invention, a ceramic multilayer substrate
having a layer configuration containing the inorganic composition
layers 72a and 72g as the upper side and underside surface layers
can be realized similarly to the ceramic multilayer substrate 20.
When the thicknesses of the glass-ceramic layers 71a through 71f
are the same, and the materials are the same as in the ceramic
multilayer substrate 20, each thickness of the inorganic
composition layers 72a and 72g as the upper side and underside
surface layers is preferably about the half of that of the other
inorganic composition layers 72b through 72f.
Fifth Embodiment
[0113] In this embodiment, as shown in FIG. 19, glass-ceramic green
sheets 81a, 81b, 81c, provided with viaholes 83a, 83b, 83c, and
conductor patterns 84a, 84b, 84c, and ceramic green sheets 82a,
82b, each containing the above-described inorganic composition as a
major component are alternately laminated, and fired under the
firing conditions for the glass-ceramic green sheets, whereby a
ceramic multilayer substrate is produced.
[0114] Hereupon, perforations 85a, 85b are formed in the ceramic
green sheets 82a, 82b containing the inorganic composition as a
major component. No conductor material is filled into the
perforations. That is, the thicknesses of the ceramic green sheets
82a, 82b are about 1-20 .mu.m, or preferably 1-10 .mu.m, and are
extremely small as compared with those of the glass-ceramic green
sheets 81a, 81b, 81c. Therefore, the viaholes 83a, 83b, 83c formed
in the glass-ceramic green sheets 81a, 81b, 81c enter the
perforations 85a, 85b upon pressure-bonded or firing, so that the
conductor patterns on the respective glass-ceramic green sheets are
connected to each other.
[0115] Hereinafter, the experimental results of the methods of
producing a ceramic multilayer substrate according to the
respective embodiments will be described.
[0116] TABLE 1 shows the first experimental results. The experiment
was carried out to investigate how different the heat shrinkage
ratios in the plane direction at firing of the laminates are,
depending on the thicknesses of the inorganic composition layers.
In this experiment, the compositions and the layer structures of
the glass-ceramic green sheets and the inorganic composition layers
are the same as described in the above first embodiment. The
sintering temperatures of the glass-ceramic green sheets is
1000.degree. C., and the sintering temperature of the ceramic green
sheets is 1500.degree. C. The thickness of the glass-ceramic green
sheets is 100 .mu.m. The number of layers is 10. The heat shrinkage
ratios are calculated as follows:
[0117] heat shrinkage ratio (%)=100 (longitudinal or lateral size
of the bottom of the laminate after firing)/(longitudinal or
lateral size of the bottom of the laminate before firing)
1TABLE 1 thickness of 0.0 0.5 1.0 5.0 10 15 20 25 inorganic
composition layer (.mu.m) shrinkage 83 95 97 98 98 98 98 NG ratio
(%)
[0118] The designation "NG" signifies that peeling or cracking was
generated, caused by the differences between the thermal expansion
ratios of the ceramic green sheets and those of the glass-ceramic
green sheets.
[0119] As seen in the experimental results, it can be suggested
that the thicknesses of the inorganic composition layers (or the
ceramic green sheets containing the inorganic composition as a
major component) are preferably set to be in the range of about 1
to 20 .mu.m.
[0120] TABLE 2 shows the second experimental results. This
experiment was carried out to investigate how different the heat
shrinkage ratios in the plane direction of the laminates caused
when the glass-ceramic green sheets are fired depend on sintering
temperatures. In this experiment, as the glass-ceramic green
sheets, those having a sintering temperature of 1000.degree. C.
were used, and the heat shrinkage ratios were calculated.
2TABLE 2 temperature (.degree. C.) 700 800 900 925 950 975 1000
shrinkage ratio (%) 99.0 98.0 96.5 94.0 91.0 88.0 83.0
[0121] As seen in TABLE 2, for the glass-ceramic green sheets
having a sintering temperature of 1000.degree. C., the heat
shrinkage ratios steeply decrease when the temperature becomes
900.degree. C. or higher. The heat shrinkage of the glass-ceramic
green sheets progresses steeply when the temperature is about
100.degree. C. lower than the sintering temperature of 1000.degree.
C. or higher, that is, about 900.degree. C. or higher. Accordingly
the heat shrinkage in the plane direction of the glass-ceramic
green sheets is inhibited if the ceramic green sheets are not heat
shrunk in the range of 900.degree. C. to 1000.degree. C.
Accordingly, it can be said that the object of the present
invention can be achieved when the difference between the sintering
temperatures of the glass-ceramic green sheets and the inorganic
composition layers (or the ceramic green sheets containing the
inorganic composition as a major component) is at least 100.degree.
C.
[0122] In the respective above-described embodiments, described is
the case where the glass-ceramic green sheets each having the
inorganic composition (ceramic green sheet) overlaid thereon are
laminated in such a manner that the glass-ceramic green sheets and
the inorganic compositions are alternately arranged to form the
whole configuration of the laminate. However, for a part of the
laminate, only the glass-ceramic green sheets, without the
inorganic composition being interposed, may be laminated for the
configuration. In brief, it is important to form such a layer
configuration that the ceramic multilayer substrate is inhibited
from shrinking in the plane direction with the warp and distortion
of the substrate being reduced.
[0123] In the first and second embodiments, described is the case
where a paste (slurry) is coated onto the front and back sides of
the glass-ceramic green sheets and dried to form the inorganic
composition layers. However, the glass-ceramic green sheets and the
inorganic composition layers may be formed separately, and the
glass-ceramic green sheets and the ceramic green sheets each
containing the inorganic composition as a major component may be
laminated to form a laminate. Likewise, a glass-ceramic green sheet
having an inorganic composition on both faces but of different
thicknesses can be employed as the undermost layer.
[0124] In the above-described respective embodiments, described is
the case where conductor patterns and viaholes are formed in the
respective layers constituting the laminate. A layer having no
conductor pattern and or no viahole may be provided as a part of
the laminate.
[0125] In the above-described embodiments, described is the case
where a conductor is filled into the viaholes formed in the
laminate. However, a conductor material may be provided only on the
inner walls of the viaholes. Further, a cavity may be formed in the
laminate described in the third embodiment according to the points
of the above-described second embodiment.
[0126] While the invention has been particularly shown and
described with reference to preferred embodiments thereof, it will
be understood by those skilled in the art that the forgoing and
other changes in form and details may be made therein without
departing from the spirit of the invention.
* * * * *