U.S. patent application number 09/877968 was filed with the patent office on 2002-03-07 for composite monolithic electronic component.
This patent application is currently assigned to Murata Manufacturing Co., Ltd.. Invention is credited to Kawakami, Hiromichi, Sunahara, Hirofumi.
Application Number | 20020027282 09/877968 |
Document ID | / |
Family ID | 18674638 |
Filed Date | 2002-03-07 |
United States Patent
Application |
20020027282 |
Kind Code |
A1 |
Kawakami, Hiromichi ; et
al. |
March 7, 2002 |
Composite monolithic electronic component
Abstract
A composite monolithic electronic component has a laminate
including a base layer having a relative dielectric coefficient of
about 10 or less and a functional layer which is at least one of a
high-dielectric-coeffic- ient layer having a relative dielectric
coefficient of about 15 or more and a magnetic layer. The base
layer contains a crystallized glass containing SiO.sub.2, MgO,
Al.sub.2O.sub.3 and B.sub.2O.sub.3, and a ceramic oxide having a
thermal expansion coefficient of about 6.0 ppm/.degree. C. or more.
The functional layer contains an amorphous glass having a softening
point of about 800.degree. C. or less.
Inventors: |
Kawakami, Hiromichi;
(Moriyama-shi, JP) ; Sunahara, Hirofumi;
(Moriyama-shi, JP) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
|
Assignee: |
Murata Manufacturing Co.,
Ltd.
|
Family ID: |
18674638 |
Appl. No.: |
09/877968 |
Filed: |
June 8, 2001 |
Current U.S.
Class: |
257/700 ;
257/E23.009; 257/E23.077 |
Current CPC
Class: |
C03C 3/062 20130101;
H05K 3/4611 20130101; H05K 1/165 20130101; H05K 1/162 20130101;
H01L 23/49894 20130101; H05K 2201/086 20130101; H05K 2201/09672
20130101; H01L 2924/00014 20130101; H05K 1/0306 20130101; H01L
2924/00014 20130101; H01L 2224/0401 20130101; Y10T 428/24926
20150115; H01L 23/15 20130101; H05K 3/4688 20130101; C03C 3/085
20130101; H01L 2224/16225 20130101; H01L 2924/09701 20130101; H05K
3/4629 20130101 |
Class at
Publication: |
257/700 |
International
Class: |
H01L 023/053; H01L
023/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 8, 2000 |
JP |
2000-172197 |
Claims
What is claimed is:
1. A composite monolithic electronic component which comprises a
fired laminate comprising a base layer which is a
low-dielectric-coefficient material layer having a relative
dielectric coefficient of about 10 or less and a functional
material layer which is at least one member of the group consisting
of a high-dielectric-coefficient material layer having a relative
dielectric coefficient of at least about 15 and a magnetic material
layer; and interconnecting conductors, wherein the base layer
comprises a crystallized glass comprising SiO.sub.2, MgO,
Al.sub.2O.sub.3 and B.sub.2O.sub.3, and a ceramic oxide having a
thermal expansion coefficient of at least about 6.0 ppm/.degree.
C.; and wherein the functional layer comprises an amorphous glass
having a softening point of about 800.degree. C. or less.
2. A composite monolithic electronic component according to claim
1, wherein the weight of the SiO.sub.2, MgO and Al.sub.2O.sub.3
contained in the crystallized glass lies in the region defined by
point A (44.0, 55.0, 1.0), point B (34.5, 64.5, 1.0), point C
(35.0, 30.0, 35.0), and point D (44.5, 30.0, 25.5) in a ternary
diagram, and wherein the crystallized glass contains about 2 to 20
parts by weight of B.sub.2O.sub.3 relative to 100 parts by weight
of the total of SiO.sub.2, MgO, and Al.sub.2O.sub.3.
3. A composite monolithic electronic component according to claim
2, wherein the weight of the SiO.sub.2, MgO and Al.sub.2O.sub.3
contained in the crystallized glass lies in the region defined by
point A (44.0, 55.0, 1.0), point B (34.5, 64.5, 1.0), point E
(35.0, 45.0, 20.0), and point F (44.5, 35.5, 20.0).
4. A composite monolithic electronic component according to claim
3, wherein the base layer comprises a precipitated crystal phase
which is at least one of forsterite and enstatite.
5. A composite monolithic electronic component according to claim
4, wherein the functional layer has a thermal expansion coefficient
of at least about 7 ppm/.degree. C.
6. A composite monolithic electronic component according to claim
2, wherein the base layer comprises a precipitated crystal phase
which is at least one of forsterite and enstatite.
7. A composite monolithic electronic component according to claim
6, wherein the functional layer has a thermal expansion coefficient
of at least about 7 ppm/.degree. C.
8. A composite monolithic electronic component according to claim
1, wherein the base layer comprises a precipitated crystal phase
which is at least one of forsterite and enstatite.
9. A composite monolithic electronic component according to claim
1, wherein the functional layer has a thermal expansion coefficient
of at least about 7 ppm/.degree. C.
10. A composite monolithic electronic component according to claim
1, wherein the interconnecting conductors comprise at least one
member selected from the group consisting of elemental Ag, an
Ag--Pt alloy, an Ag--Pd alloy, elemental Au, elemental Ni and
elemental Cu.
11. A composite monolithic electronic component according to claim
1, wherein the base layer comprises a plurality of
low-dielectric-coefficien- t material layers and the functional
material layer comprises a plurality of the at least one member of
the group consisting of a high-dielectric-coefficient material
layer and magnetic material layer.
12. A composite monolithic electronic component according to claim
11, having at least one capacitor disposed in the interior of the
laminate and wherein the interconnection conductors electrically
connect the capacitor to an exterior surface of the laminate.
13. A composite monolithic electronic component according to claim
11, having at least one inductor disposed in the interior of the
laminate and wherein the interconnection conductors electrically
connect the inductor to an exterior surface of the laminate.
14. A composite monolithic electronic component according to claim
1, having at least one capacitor disposed in the interior of the
laminate and wherein the interconnection conductors electrically
connect the capacitor to an exterior surface of the laminate.
15. A composite monolithic electronic component according to claim
1, having at least one inductor disposed in the interior of the
laminate and wherein the interconnection conductors electrically
connect the inductor to an exterior surface of the laminate.
16. A composite monolithic electronic component according to claim
1, having a second low-dielectric-coefficient material layer having
a relative dielectric coefficient of about 10 or less disposed such
that the functional material layer is sandwiched between the two
low-dielectric-coefficient material layers.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to composite monolithic
electronic components comprising a sintered laminate formed by
stacking and baking unsintered material layers composed of various
types of materials. Specifically, the present invention relates to
a composite monolithic electronic component provided in its
interior with a passive device such as a capacitor and an
inductor.
[0003] 2. Description of the Related Art
[0004] Generally, insulative ceramic substrates are widely used for
mounting various electronic components constituting electronic
circuits in order to meet the demand for smaller electronic
devices.
[0005] In order to further increase the mounting density and to
withstand higher frequencies, a monolithic ceramic substrate
prepared by baking a green laminate comprising a plurality of
stacked ceramic green sheets, each of which is a
low-dielectric-coefficient insulative ceramic layer having the
relative dielectric coefficient of 15 or less, and interconnecting
conductors composed of a conductive paste containing a
low-resistance conductive substance such as Ag, Ag--Pd, Cu, Au or
the like, which are patterned into a predetermined shape and which
are provided on each of the ceramic green sheets, has been
developed.
[0006] In order to further increase the mounting density from that
of the substrate comprising the above-described
low-dielectric-coefficient insulative ceramic layers, a substrate
combining various types of materials, more particularly, a
substrate comprising a dielectric layer having a relatively high
dielectric coefficient and a functional layer, such as a magnetic
layer having different permeability or a resistance layer having a
different resistance, is desired since such a structure is capable
of accommodating a passive element such as a capacitor, an inductor
and/or a resistor, in an improved manner.
[0007] The aforementioned monolithic ceramic substrate comprising
the low-dielectric-coefficient ceramic layers are mainly used in
packages or circuit boards for mounting large-size IC chips
comprising Si or Ga--As. In order to prevent the interface between
the IC chip and the monolithic ceramic substrate from becoming
defective due to thermal stresses, the thermal expansion
coefficient of the low-dielectric-coefficient insulative material
constituting the ceramic layers is set to approximately the same
value as the thermal expansion coefficient of the IC chip (Si: 3.6
ppm/.degree. C., Ga--As: 6.8 ppm/.degree. C.).
[0008] In this respect, a composite material in which a glass such
as borosilicate glass, borosilicate lead glass, lead silicate glass
or the like, is added to a ceramic material such as alumina,
cordierite, mullite or the like, is used as the
low-dielectric-coefficient insulative material. Thus, it becomes
possible to set the thermal expansion coefficient of the
low-dielectric-coefficient insulative material to approximately the
same value as that of the IC chip and to sinter the material at a
temperature of 1,000.degree. C. or less.
[0009] A multichip-module-type mounting substrate, that is, the
circuit board (package) provided with a plurality of bare chips,
will be more widely used as a high-density mounting module in the
near future. Presently, when a flip chip is mounted on the mounting
substrate, solder is used as an I/O interface to provide bonding.
An interface portion (land portion) at which the flip chip contacts
the mounting substrate is formed into a slope by a material having
mechanical characteristics between that of the solder and that of
each material. Moreover, an underfill material is provided after
bonding in order to alleviate stresses. Alternatively, a conductive
adhesive may be used to form the I/O termination in order to
alleviate stresses.
[0010] In view of the above, the problem of defects due to thermal
stresses at the interface between the IC chip and the monolithic
ceramic substrate has been already solved.
[0011] In contrast, the thermal expansion coefficient of most of
the high-dielectric-coefficient material constituting the
dielectric layer having a relatively high dielectric coefficient in
the above-described substrate combining various materials, except
for PbO-based perovskite materials, is 8 ppm/.degree. C. or more.
The PbO-based perovskite material contains large amounts of PbO and
is hazardous to the environment. The thermal expansion coefficient
of most of the magnetic materials, i.e., ferrite, constituting the
magnetic layer having different permeability is also 8 ppm/.degree.
C. or more.
[0012] The problems caused by the thermal stresses created when a
passive element composed of a high-dielectric-coefficient material
or a magnetic material, such as a capacitor or an inductor, is
vertically or horizontally provided inside the monolithic substrate
is more serious than problem created by the thermal stress between
the IC chip and the mounting substrate. To be more specific, when
the monolithic ceramic substrate is composed of various types of
materials, the interface at which the different types of materials
come into contact with each other is large compared to the
interface between the IC chip and the substrate, and it is
difficult to release the thermal stresses since the interface is
located inside the monolithic ceramic substrate.
[0013] As a result, defects such as cracks which result from
differences in thermal expansion coefficients, are likely to occur
at the interfaces between the various different materials even when
there is no defect at the IC chip.
SUMMARY OF THE INVENTION
[0014] Accordingly, it is an object of the present invention to
provide a composite monolithic electronic component comprising a
combination of different types of materials which overcomes the
above-described problems.
[0015] This invention is directed to a composite monolithic
electronic component comprising: a laminate having a base layer
which is a low-dielectric-coefficient layer having a relative
dielectric coefficient of about 10 or less and a functional layer
which is a magnetic layer and/or a high-dielectric-coefficient
layer having a relative dielectric coefficient of about 15 or more;
and interconnecting conductors provided for the laminate. The
laminate and the interconnecting conductors are simultaneously
baked.
[0016] In order to solve the above-described technical problems, a
low-dielectric-coefficient material having a
high-thermal-expansion-coeff- icient is needed as the material of
the base layer in the composite monolithic electronic component.
The low-dielectric-coefficient material is also required to have
mechanical strength.
[0017] One way to meet these needs is to use a crystallized glass
having a relatively high mechanical strength in the base layer.
However, when the crystallized glass is used in the base layer,
dispersion from/to various types of materials, i.e., dispersion
between the base layer and the functional layer, and wetting
between the materials included in the base layers occurs, thereby
causing a failure to obtain the desired crystallized substances. A
crystallized glass which allows a desired crystal phase having a
high-thermal expansion-coefficient to precipitate efficiently is
needed.
[0018] Therefore, according to one aspect of the present invention,
the base layer contains a crystallized glass comprising SiO.sub.2,
MgO, Al.sub.2O.sub.3 and B.sub.2O.sub.3, and an oxide ceramic
having a thermal expansion coefficient of about 6.0 ppm/.degree. C.
or more. The functional layer contains an amorphous glass having a
softening point of about 800.degree. C. or less.
[0019] In this composite monolithic electronic component, a
bondability is obtained by the crystallized glass contained in the
base layer and the amorphous glass contained in the functional
layer. When bonding is achieved in this manner, not only can the
base layer and the functional layer be sintered at a low
temperature of about 1,000.degree. C. or less, but also residual
stresses can be disregarded above the glass distortion point. By
using a low-softening-point glass, the stresses occurring at the
bonding interfaces (residual stresses) can be significantly
decreased compared to a solid-state-reaction bonding if the thermal
expansion coefficients of these layers at the time of the bonding
are the same.
[0020] Preferably, the weight of SiO.sub.2, MgO and Al.sub.2O.sub.3
contained in the crystallized glass lies in the region defined by
point A (44.0, 55.0, 1.0), point B (34.5, 64.5, 1.0), point C
(35.0, 30.0, 35.0) and point D (44.5, 30.0, 25.5) in a ternary
diagram illustrated in FIG. 2. The crystallized glass preferably
contains about 2 to 20 parts by weight of B.sub.2O.sub.3 compared
to 100 parts by weight of SiO.sub.2, MgO and Al.sub.2O.sub.3 in
total.
[0021] More preferably, the weight of SiO.sub.2, MgO and
Al.sub.2O.sub.3 contained in the crystallized glass lies in the
region defined by point A (44.0, 55.0, 1.0), point B (34.5, 64.5,
1.0), point E (35.0, 45.0, 20.0) and point F (44.5, 35.5, 20.0) in
the ternary diagram of FIG. 2.
[0022] The relationship between residual stresses and the sintering
temperature during the sintering of the base layer and the
functional layer is primarily defined by the glass viscosity, which
is typically indicated by the glass softening point, and
wettability between the glass and the dielectric/magnetic material.
The glass viscosity, however, greatly affects interdiffusion and
the diffusion of the material constituting the interconnecting
conductors when the different types of materials are bonded by
sintering. Accordingly, when selecting a glass to be contained in
the composite material comprising ceramic and glass, it is
important to consider not only the residual stresses but also
interdiffusion distances and electrical characteristics. Moreover,
even if the temperature at which the residual stresses start to
work is lowered, the alleviation of the stress may be limited
depending on the combination of the thermal expansion coefficients
of the ceramic and the glass and the difference in the Young
coefficients thereof.
[0023] In this respect, in this invention, the base layer
preferably has a crystal phase, such as forsterite and/or
enstatite, having a high thermal expansion coefficient which is
approximately the same as the thermal expansion coefficient of the
high-dielectric-coefficient material such as BaTiO.sub.3. In this
manner, the residual stresses can be reduced below the glass
distortion point.
[0024] Preferably, the functional layer has a thermal expansion
coefficient of about 7 ppm/.degree. C. or more, which is
approximately the same with the thermal expansion coefficient of
the base layer.
[0025] Furthermore, the interconnecting conductors may be made of
at least one material selected from the group consisting of
elemental Ag, an Ag--Pt alloy, an Ag--Pd alloy, elemental Au,
elemental Ni and elemental Cu, since the composite monolithic
electronic component of the present invention can be sintered at a
temperature of about 1,000.degree. C. or less.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a cross-sectional view illustrating a composite
monolithic electronic component 1 in accordance with an embodiment
of the present invention;
[0027] FIG. 2 is a ternary diagram showing ratio by weight of
SiO.sub.2 to MgO to Al.sub.2O.sub.3 contained in a crystallized
glass constituting the base layers 6 and 7 shown in FIG. 1; and
[0028] FIG. 3 is a cross-sectional view illustrating a laminate 24
according to an example of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] FIG. 1 is a cross-sectional view illustrating a composite
monolithic electronic component 1 in accordance with an aspect of
the present invention.
[0030] The composite monolithic electronic component 1 comprises a
laminate 2. Surface-mounting components 3, 4 and 5, such as
semiconductor devices or chip capacitors, are mounted on the
laminate 2 to form a ceramic composite module.
[0031] The laminate 2 comprises base layers 6 and 7, which are
low-dielectric-coefficient layers each having a relative dielectric
coefficient of about 10 or less, and a functional layer 8 which is
a high-dielectric-coefficient layer having a relative dielectric
coefficient of about 15 or more and is provided between the base
layers 6 and 7. Although each of the base layers 6 and 7 and the
functional layer 8 is illustrated as a single layer each in FIG. 1,
a plurality of low-dielectric-coefficient sublayers and a plurality
of high-dielectric-coefficient sublayers are generally provided to
constitute these layers.
[0032] The laminate 2 has internal conductor layers 9 and 10,
via-hole conductors 11, and external conductor layers 12. The
internal conductor layers 10 provided in the functional layer 8,
which is the high-dielectric-coefficient layer form capacitors C1
and C2. The internal conductor layers 9 and 10, the via-hole
conductors 11, and the external conductor layers 12 form
interconnecting conductors for providing electrical connection
between the surface-mounting components 3 to 5 and internal
capacitors C1 and C2.
[0033] The laminate 2 may be manufactured for example, by the
following process.
[0034] First, a crystallized glass containing
SiO.sub.2--MgO--Al.sub.2O.su- b.3--B.sub.2O.sub.3 as the main
component is prepared as the material of the base layers 6 and 7.
An oxide ceramic having a thermal expansion coefficient of 6.0
ppm/.degree. C. or more, such as alumina, is then added to the
crystallized glass and is mixed therewith. An organic binder, a
dispersing agent, a plasticizer, an organic solvent and the like,
are added to the resulting powder mixture and are mixed to obtain a
slurry for making the low-dielectric-coefficient layers. The
resulting slurry is then formed into sheets by the doctor blade
process to obtain ceramic green sheets for making
low-dielectric-coefficient layers.
[0035] Meanwhile, a BaO--TiO.sub.2-type dielectric material is
prepared as the material for the functional layer 8. The material
is calcined at 1,000.degree. C. for an hour and is then pulverized.
An amorphous glass having a softening point of 800.degree. C. or
less such as Me.sub.2O--MaO--SiO.sub.2--CuO-type glass (wherein Me
is alkali metal and Ma is alkaline earth metal) is added to the
calcined and pulverized material to prepare a material mixture. An
organic binder, a dispersing agent, a plasticizer, an organic
solvent and the like are added to the material mixture and are
mixed to make a slurry for making the high-dielectric-coefficient
layer. The resulting slurry is formed into sheets by the doctor
blade process to obtain ceramic green sheets for making the
high-dielectric-coefficient layer.
[0036] Next, through-holes are formed in the designated resulting
ceramic green sheets which are used for making the
low-dielectric-coefficient layers and the
high-dielectric-coefficient layer. The through-holes are filled
with a conductive paste or a conductive powder to form via-hole
conductors 11.
[0037] A conductive paste is then applied, by printing, on the
designated ceramic green sheets which are used for making the
low-dielectric-coefficient layers and the
high-dielectric-coefficient layer so as to form the internal
conductor layers 9 and 10 and the external conductors 12.
[0038] Preferably, the conductive paste or the conductive powder
used for forming the internal conductor layers 9 and 10 and the
external conductor layers 12 contains at least one selected from
elemental Ag, an Ag--Pt alloy, an Ag--Pd alloy, elemental Au,
elemental Ni and elemental Cu as the main conductive component.
[0039] Next, a predetermined number of ceramic green sheets for
making the low-dielectric-coefficient layers and the
high-dielectric-coefficient layer are stacked in a predetermined
order and are then pressed in the stacked direction so as to form a
laminate block which will be used to form the laminate 2. If
necessary, the laminate block may be cut to an appropriate
size.
[0040] The resulting laminate block is sintered at a temperature in
the range of about 800 to 1,000.degree. C. to obtain the laminate 2
shown in FIG. 1.
[0041] Finally, the surface-mounting components 3, 4 and 5 are
mounted on one main surface of the laminate 2 to complete the
composite monolithic electronic component 1, which is a ceramic
monolithic module.
[0042] In the composite monolithic electronic component 1 having
the above-described configuration, because the capacitors C1 and C2
are formed in the functional layer 8 which is the
high-dielectric-coefficient layer, the capacitance of the
capacitors C1 and C2 can be easily increased. In other words, the
volume of the capacitors C1 and C2 can be easily decreased. As a
result, the performance of the composite monolithic electronic
component 1 as the ceramic monolithic module can be easily improved
and the size thereof can be easily reduced.
[0043] It is to be understood that the multi-layer configuration of
the laminate 2 of the composite monolithic electronic component 1
shown in FIG. 1 is merely an example. Alternatively, the number of
the base layers 6 and 7 and the functional layer 8 can be any
number and the order for stacking the layers can be altered.
Moreover, the functional layer 8 may be replaced with a magnetic
material layer. In such a case, the interconnecting conductors
formed in the functional layer 8 constitute, for example, an
inductor. Furthermore, both the high-dielectric-coefficie- nt layer
and the magnetic material layer may be provided as the functional
layers 8.
[0044] As described above, the base layers 6 and 7 contain the
crystallized glass containing
SiO.sub.2--MgO--Al.sub.2O.sub.3-B.sub.2O.su- b.3 as the main
component, and a ceramic oxide, such as alumina, having a thermal
expansion coefficient of about 6.0 ppm/.degree. C. or more. The
ratio of the components in the crystallized glass is preferably as
follows.
[0045] FIG. 2 is a ternary diagram showing the amounts of
SiO.sub.2, MgO and Al.sub.2O.sub.3, on a weight basis, contained in
the crystallized glass.
[0046] The amounts by weight of SiO.sub.2, MgO and Al.sub.2O.sub.3
contained in the crystallized glass preferably lies in the region
defined by point A (44.0, 55.0, 1.0), point B (34.5, 64.5, 1.0),
point C (35.0, 30.0, 35.0) and point D (44.5, 30.0, 25.5) in the
ternary diagram in FIG. 2. Preferably, the B.sub.2O.sub.3 content
in the crystallized glass is about 2 to 20 parts by weight compared
to the total content of SiO.sub.2, MgO and Al.sub.2O.sub.3 which is
100 parts by weight.
[0047] More preferably, the weight of SiO.sub.2, MgO and
Al.sub.2O.sub.3 lies in the region defined by point A (44.0, 55.0,
1.0), point B (34.5, 64.5, 1.0), point E (35.0, 45.0, 20.0) and
point F (44.5, 35.5, 20.0) in the ternary diagram in FIG. 2.
[0048] At least one forsterite crystal phase or enstatite crystal
phase is preferably precipitated in the base layers 6 and 7. Since
these crystal phases have high thermal expansion coefficients,
residual stresses in the base layers 6 and 7 below the
glass-distortion point can be reduced.
[0049] The thermal expansion coefficient of the functional layer 8
is preferably about 7 ppm/.degree. C. or more.
EXAMPLES
[0050] 1. Base Layers
[0051] The low-dielectric-coefficient layers constituting the base
layers were examined.
[0052] First, SiO.sub.2, MgCO.sub.3, Al.sub.2O.sub.3 and
H.sub.3BO.sub.3 were prepared as the starting material of the
crystallized glass. The SiO.sub.2, MgCO.sub.3, Al.sub.2O.sub.3 and
H.sub.3BO.sub.3 were then mixed at the weight ratios shown in Table
1. The resulting mixtures were melted to make glass melts. The
glass melts were rapidly cooled by placing them into deionized
water, and were then pulverized to obtain crystallized glass
powders.
1 TABLE 1 Glass Contents Sample No. SiO.sub.2 MgO Al.sub.2O.sub.3
B.sub.2O.sub.3 Reference G1 44.0 55.0 1.0 10.0 A G2 34.5 65.4 1.0
10.0 B G3 35.0 30.0 35.0 10.0 C G4 44.5 30.0 25.5 10.0 D G5 35.0
45.0 20.0 10.0 E G6 45.5 35.5 20.0 10.0 F G7 40.0 50.0 10.0 10.0 G8
40.0 35.0 25.0 10.0 G9 30.0 60.0 10.0 10.0 G10 20.0 40.0 40.0 10.0
G11 40.0 20.0 40.0 10.0 G12 55.0 40.0 5.0 10.0 G13 34.5 64.5 1.0
0.0 G14 34.5 64.5 1.0 2.0 G15 34.5 64.5 1.0 20.0 G16 34.5 64.5 1.0
30.0 G17 40.0 50.0 10.0 0.0 G18 40.0 50.0 10.0 2.0 G19 40.0 50.0
10.0 20.0 G20 40.0 50.0 10.0 30.0 G21 35.0 30.0 35.0 0.0 G22 35.0
30.0 35.0 2.0 G23 35.0 30.0 35.0 20.0 G24 35.0 30.0 35.0 30.0 G25
40.0 60.0 0.0 0.0 G26 35.0 30.0 35.0 20.0
[0053] An oxide ceramic powder, described below, was added to the
crystallized glass powders in an amount of 10 parts by weight. An
organic binder and a solvent were also added. The mixtures were
then thoroughly mixed in a ball mill so as to obtain evenly
dispersed mixtures and were deaerated under a reduced pressure to
make slurries.
[0054] In Samples G1 to G25, an alumina powder having a thermal
expansion coefficient of about 6.0 ppm/.degree. C. or more, more
specifically, approximately 7.5 ppm/.degree. C., was employed as
the oxide ceramic powder. In Sample G26, cordierite having the
thermal expansion coefficient of less than about 6.0 ppm/.degree.
C., more specifically, approximately 5.5 ppm/.degree. C., was
employed as the oxide ceramic powder.
[0055] The weights of SiO.sub.2, MgO and Al.sub.2O.sub.3 in each of
the Samples G1 to G12 and G25 in Table 1 is indicated by the dots
in the ternary diagram in FIG. 2. The numbers given to the dots in
the diagram correspond to the numerals following the letter G of
the Samples.
[0056] The numbers 13 to 24 and 26 corresponding to the Samples G13
to G24 and G26 do not appear in FIG. 2. The weight of SiO.sub.2,
MgO and Al.sub.2O.sub.3 in each of the Samples G13 to G16 is the
same as in the Sample G2. The weight in each of the Samples 17 to
20 is the same as in the sample G7, and the weight in each of the
samples G21 to G24 is the same as in the Sample G3.
[0057] Samples G1 to G6 are given the reference symbols A to F as
shown in the reference column in Table 1 and the above-described
weight combinations in each of the samples G1 to G6 is indicated by
dots A to F in the ternary diagram in FIG. 2.
[0058] Ceramic green sheets each having thickness of 0.2 mm were
formed on carrier films from the above-described slurries
containing the crystallized glass powders G1 to G26 shown in Table
1 by a casting method using a doctor blade. The ceramic green
sheets were then dried, were separated from the carrier films and
were punched to obtain ceramic green sheets having a predetermined
size. A plurality of the ceramic green sheets were stacked and
press-molded to obtain green ceramic compacts.
[0059] The green ceramic compacts were heated to 950.degree. C. at
a rate of 200.degree. C. per hour and the temperature was
maintained thereat for two hours to form sintered ceramic
compacts.
[0060] The relative dielectric coefficient, insulation resistance,
thermal expansion coefficient, sinterability and crystal phase of
each of the resulting sintered ceramic compacts made from the
sample crystallized glasses were examined.
[0061] The relative dielectric coefficient and insulation
resistance were examined as follows. Square electrodes, 8.times.8
mm, were formed by applying and sintering an Ag-based material on
two main surfaces of a sample compact whose size was
10.times.10.times.0.5 mm. Electrostatic capacitance was measured
through these electrodes using an LCR meter under the conditions of
frequency 1 MHZ, voltage 1 Vrms and a temperature of 25.degree. C.
The relative dielectric coefficient was calculated from the
determined capacitance. The insulation resistance was measured 60
seconds after the application of a 50 V DC voltage.
[0062] In order to determine the thermal expansion coefficient, the
sample compacts whose size was 2.times.2.times.10 mm were used and
the average thermal expansion coefficient in the temperature range
from 30.degree. C. to 400.degree. C. was measured.
[0063] The crystal phase was examined by X-ray diffraction in order
to identify the X-ray diffraction pattern in the surfaces of the
sample compacts.
[0064] The results are shown in Table 2.
2TABLE 2 Rela- tive Die- Insu- Thermal lec- lation Expan- tric Re-
sion Coef- sis- Coeffi- fici- tance cient Presence of Sam- ent log
ppm/ Crystal Phase ple .epsilon..sub.r IR .degree. C. Sinterability
Forsterite Enstatite G1 6.7 >9 13.1 Satisfactory Precipitated
Precipitated G2 6.8 >9 14.0 Satisfactory Precipitated
Precipitated G3 6.7 >9 6.5 Satisfactory Precipitated
Precipitated G4 6.6 >9 6.7 Satisfactory Precipitated
Precipitated G5 6.6 >9 7.9 Satisfactory Precipitated
Precipitated G6 6.6 >9 7.8 Satisfactory Precipitated
Precipitated G7 6.7 >9 8.6 Satisfactory Precipitated
Precipitated G8 6.8 >9 6.8 Satisfactory Precipitated
Precipitated G9 -- -- -- Not -- -- satisfactory G10 7.1 >9 5.3
Satisfactory Not Precipitated Precipitated G11 6.7 >9 4.9
Satisfactory Precipitated Precipitated G12 -- -- -- Not -- --
satisfactory G13 -- -- -- Not -- -- satisfactory G14 6.9 >9 14.5
Satisfactory Precipitated Precipitated G15 6.5 >9 12.0
Satisfactory Precipitated Precipitated G16 6.3 >9 9.9
Satisfactory Precipitated Precipitated G17 -- -- -- Not -- --
satisfactory G18 6.8 >9 9.1 Satisfactory Precipitated
Precipitated G19 6.5 >9 8.0 Satisfactory Precipitated
Precipitated G20 6.2 >9 7.8 Satisfactory Precipitated
Precipitated G21 -- -- -- Not -- -- satisfactory G22 6.8 >9 6.7
Satisfactory Precipitated Precipitated G23 6.3 >9 6.1
Satisfactory Precipitated Precipitated G24 6.3 >9 5.8
Satisfactory Precipitated Precipitated G25 -- -- -- Not -- --
satisfactory G26 6.0 >9 4.0 Satisfactory Precipitated
[0065] Referring to Table 2, the Samples G1 to G8, G14 to G16, G18
to G20, G22 and G23 exhibited satisfactory sinterability, low
dielectric coefficient, high insulation resistance and high thermal
expansion coefficient even when baked at a relatively low
temperature of 950.degree. C. Moreover, crystal phases of
forsterite and enstatite were both precipitated.
[0066] In contrast, the Samples G9 to G12 whose the amounts of
SiO.sub.2, MgO and Al.sub.2O.sub.3 lie outside the region
surrounded by points A to D in the ternary diagram in FIG. 2 had
unsatisfactory sinterability and did not precipitate the forsterite
crystal phase. The thermal expansion coefficient was also low.
[0067] Samples G13, G17 and G21 did not exhibit satisfactory
sinterability because the crystallized glass used therein did not
contain B.sub.2O.sub.3. Sample G25 also did not exhibit
satisfactory sinterability because the crystallized glass used
therein contained neither Al.sub.2O.sub.3 nor B.sub.2O.sub.3.
[0068] 2. Functional Layer
[0069] The high-dielectric-coefficient layer and the magnetic layer
constituting the functional layer were examined.
[0070] A BaTiO.sub.3-type material was used as the dielectric
material having a dielectric coefficient of about 15 or more, for
forming the high-dielectric-coefficient layer. A
Li.sub.2O--BaO--CaO--SrO--SiO.sub.2-- -CuO type amorphous glass
having a softening point of 670.degree. C. was used as the
crystallized glass added to the BaTiO.sub.3-type material.
[0071] A Ni--Zn ferrite material was used as the magnetic material
for forming the magnetic layer. The same above--described amorphous
glass was added to the Ni--Zn ferrite material as in the case of
above-described dielectric material.
[0072] The above-described amorphous glass was added to the
BaTiO.sub.3 type material at the weight parts shown in Table 3. An
organic binder and a solvent were further added. The mixture was
then thoroughly mixed in a ball mill to obtain an evenly dispersed
mixture, and was deaerated under reduced pressure so as to obtain
slurries.
3TABLE 3 Sample No. BaTiO.sub.3-type material
Me.sub.2O-MaO-SiO.sub.2-CuO-type glass B1 90 10 B2 80 20 B3 70 30
B4 65 35
[0073] The amorphous glass was added to the Ni--Zn-type ferrite
materials at the weight parts shown in Table 4 and underwent the
same treatment as the above so as to obtain slurries.
4TABLE 4 Sample No. Ni-Zn-type material
Me.sub.2O-MaO-SiO.sub.2-CuO-type glass F1 95 5 F2 90 10 F3 80 20 F4
70 30
[0074] Ceramic green sheets of 0.2 mm in thickness were formed on
film surfaces using the above-described slurries by a casting
method using a doctor blade. The ceramic green sheets were then
dried, were separated from films and were punched to obtain the
ceramic green sheets of predetermined size. A plurality of the
ceramic green sheets was stacked and then press-molded to obtain
green ceramic compacts.
[0075] The green ceramic compacts were heated to 950.degree. C. at
a rate of 200.degree. C. per hour and the temperature was
maintained for two hours in order to form sintered ceramic
compacts.
[0076] The thermal expansion coefficient of each sample ceramic
compact was examined. Using 2.times.2.times.10 mm ceramic compact
samples, the average thermal expansion coefficient within the
temperature range of 30.degree. C. to 400.degree. C. was
measured.
[0077] The results are shown in Tables 5 and 6 below.
5 TABLE 5 Sample No. Thermal Expansion Coefficient ppm/.degree. C.
B1 13.0 B2 11.0 B3 9.0 B4 7.0
[0078]
6 TABLE 6 Sample No. Thermal Expansion Coefficient ppm/.degree. C.
F1 13.0 F2 11.0 F3 9.0 F4 7.0
[0079] 3. Laminate
[0080] Referring to FIG. 3, a laminate 24 comprising
low-dielectric-coefficient layers 21, a high-dielectric-coefficient
layer 22 and a magnetic material layer 23 were fabricated in the
following manner.
[0081] In order to form the low-dielectric-coefficient layer 21,
the low-dielectric-coefficient green sheets of Samples G1 to G26
shown in Tables 1 and 2 were used.
[0082] In order to form the high-dielectric-coefficient layer 22,
the high-dielectric-coefficient green sheets of Samples B1 to B4
shown in Tables 3 and 5 were used. In order to form the magnetic
material layer 23, the magnetic green sheets of Samples F1 to F4
shown in Tables 4 and 6 were used.
[0083] These green sheets were separated from film substrates on
which they had been prepared and were punched to obtain green
sheets of 12 mm in width and 12 mm in length.
[0084] The low-dielectric-coefficient green sheets, the
high-dielectric-coefficient green sheets and the magnetic green
sheets were stacked and then press-bonded in the combinations shown
in Table 7 and in the order shown in FIG. 3, so as to obtain the
laminates 24 having a thickness of 3 mm, each comprising the
low-dielectric-coefficient layers 21, the
high-dielectric-coefficient layer 22 and the magnetic material
layer 23.
[0085] The resulting laminate blocks were heated to 950.degree. C.
for 30 minutes to obtain the laminates 24, one of which is shown in
FIG. 3.
[0086] Sinterability and bondability of each of the laminate blocks
and the presence of cracks at the bonding interfaces thereof were
examined. The results are shown in Table 7.
7TABLE 7 Low- High- dielec- dielec- tric- tric- Pre- Sam- coeffi-
coeffi- Mag- sence ple cient cient netic of No. layer layer layer
Sinterability Bondability cracks 1 G1 B1 F1 Excellent Excellent
None 2 G2 B1 F1 Excellent Excellent None 3 G3 B4 F4 Excellent
Excellent None 4 G4 B4 F4 Excellent Excellent None 5 G5 B4 F4
Excellent Excellent None 6 G6 B4 F4 Excellent Excellent None 7 G7
B3 F3 Excellent Excellent None 8 G8 B4 F4 Excellent Excellent None
9 G9 B1 F1 Not Not Few Satisfactory Satisfactory 10 G10 B4 F4
Excellent Excellent Few 11 G11 B4 F4 Excellent Not Few Satisfactory
12 G12 B1 F1 Not Not Few Satisfactory Satisfactory 13 G13 B1 F1 Not
Not Few Satisfactory Satisfactory 14 G14 B1 F1 Excellent Excellent
None 15 G15 B2 F2 Excellent Excellent None 16 G16 B3 F3 Excellent
Excellent None 17 G17 B4 F4 Not Not Few Satisfactory Satisfactory
18 G18 B3 F3 Excellent Excellent None 19 G19 B3 F3 Excellent
Excellent None 20 G20 B4 F4 Excellent Excellent None 21 G21 B4 F4
Not Not Few Satisfactory Satisfactory 22 G22 B4 F4 Excellent
Excellent None 23 G23 B4 F4 Excellent Excellent None 24 G24 B4 F4
Excellent Excellent Few 25 G25 B1 F1 Not Not Few Satisfactory
Satisfactory 26 G26 B1 F1 Excellent Poor --
[0087] Referring to Table 7, the laminate 24 using any one of
Samples 1 to 8, 14, 15, 18, 19, 22 and 23 exhibited superior
sinterability and bondability and no cracks were found in the
bonding interfaces.
[0088] In contrast, the laminates using Samples 10, 11 and 24 had
small cracks at the bonding interfaces.
[0089] The laminates 24 using Samples 9, 12, 13, 17, 21 and 25
exhibited degraded sinterability and bondability and small cracks
were found at the bonding interfaces thereof.
[0090] The plies of laminate 24 using Sample 26 did not bond.
[0091] Samples 16 and 20, having an increased amount of
B.sub.2O.sub.3, were likely to have degraded weather resistance
(moisture resistance).
[0092] As apparent from the above, the composite monolithic
electronic component in accordance with the present invention when
fabricated by sintering at a temperature below about 1,000.degree.
C., exhibits superior bondability between the base layers and
functional layers composed of different materials, and resists the
occurrence of failure such as cracks, and is thus highly
reliable.
* * * * *