U.S. patent application number 09/726512 was filed with the patent office on 2001-06-07 for semiconductor electronic part.
Invention is credited to Tanaka, Ryuichi.
Application Number | 20010002873 09/726512 |
Document ID | / |
Family ID | 18376965 |
Filed Date | 2001-06-07 |
United States Patent
Application |
20010002873 |
Kind Code |
A1 |
Tanaka, Ryuichi |
June 7, 2001 |
Semiconductor electronic part
Abstract
A semiconductor electronic part comprises a semiconductor
ceramic substrate and at least one internal electrode. The internal
electrode is disposed inside the semiconductor ceramic substrate
and includes an end led out to an end edge of the semiconductor
ceramic substrate and at least one cutout region. It is preferable
that the internal electrode has a plurality of the cutout regions.
Further preferably, the plurality of the cutout regions are
arranged to be distanced from one another in a direction of width
of the semiconductor ceramic substrate.
Inventors: |
Tanaka, Ryuichi; (Tokyo,
JP) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT PC
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Family ID: |
18376965 |
Appl. No.: |
09/726512 |
Filed: |
December 1, 2000 |
Current U.S.
Class: |
361/306.3 ;
257/532 |
Current CPC
Class: |
H01C 1/14 20130101; H01C
7/18 20130101; H01G 4/012 20130101; H01G 4/1272 20130101 |
Class at
Publication: |
361/306.3 ;
257/532 |
International
Class: |
H01L 029/00; H01G
004/228 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 3, 1999 |
JP |
P. HEI. 11-345493 |
Claims
What is claimed is:
1. A semiconductor electronic part comprising: a semiconductor
ceramic substrate; and at least one internal electrode disposed
inside said semiconductor ceramic substrate, and including an end
led out to an end edge of said semiconductor ceramic substrate and
at least one cutout region.
2. The semiconductor electronic part according to claim 1, wherein
said internal electrode has a plurality of cutout regions.
3. The semiconductor electronic part according to claim 2, wherein
the plurality of cutout regions are arranged to be distanced from
one another in a direction of width of said semiconductor ceramic
substrate.
4. The semiconductor electronic part according to claim 1, wherein:
said internal electrode includes a main electrode portion and a
pick-up electrode portion; and the pick-up electrode portion is
disposed on one end of the main electrode portion in a lengthwise
direction thereof and the pick-up electrode portion is larger in
width than the main electrode portion.
5. The semiconductor electronic part according to claim 1, the
cutout regions is shaped into a rectangle.
6. The semiconductor electronic part according to claim 1, the
cutout region is shaped into a half circle.
7. The semiconductor electronic part according to claim 4, the
cutout region is provided on the inside of an end edge of the
pick-up electrode portion.
8. A semiconductor electronic part comprising: a semiconductor
ceramic substrate; at least one first internal electrode disposed
inside said semiconductor ceramic substrate, and including a first
end led out to a first end edge of said semiconductor ceramic
substrate and at least one first cutout region; at least one second
internal electrode disposed inside said semiconductor ceramic
substrate, including a second end led out to a second end edge of
said semiconductor ceramic substrate, and at least one second
cutout region.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a semiconductor electronic
part. Examples of the semiconductor electronic part according to
the present invention include varistor, PTC thermistor, NTC
thermistor, semiconductor capacitor, etc.
[0003] 2. Description of the Related Art
[0004] Various kinds of semiconductor electronic parts are known
heretofore. Among these parts, there are known semiconductor
electronic parts each having an internal electrode buried in a
semiconductor ceramic substrate.
[0005] The semiconductor electronic part of this type obtains
semiconductor characteristic by utilizing contact between the
internal electrode and the semiconductor ceramic substrate. The
semiconductor ceramic substrate is selected in accordance with the
kind of the semiconductor electronic part to be obtained. A
material for constituting the internal electrode is selected so
that predetermined semiconductor characteristic is obtained between
the semiconductor ceramic substrate and the internal electrode.
[0006] As described above, in the semiconductor electronic part of
this type, the composition of the internal electrode is required to
be selected so that predetermined semiconductor characteristic can
be obtained in accordance with the semiconductor ceramic substrate.
In the case of a capacitor, or the like, strength of adhesion can
be improved by adding a third component such as glass frit or the
like to the constituent material for the electrode. However, if
such a means is applied to the semiconductor electronic part, the
semiconductor characteristic deteriorates. Hence, the semiconductor
electronic part basically has a problem that it is difficult to
improve strength of adhesion of the internal electrode to the
semiconductor ceramic substrate.
[0007] For example, in the case of a varistor, a titanium oxide
type substrate, a strontium titanate type substrate or a zinc oxide
type substrate is generally used as the semiconductor ceramic
substrate. Such a semiconductor ceramic substrate per se has
voltage nonlinearity. In order to extract the voltage nonlinearity
of the semiconductor ceramic substrate, the internal electrode must
be selected from materials which come into ohmic contact with the
semiconductor ceramic substrate. Specifically, the internal
electrode must contain silver as a main component and at least one
member selected from the group consisting of In, Ga, Sn, Sb, Cd, Zn
and Al as an additive component. If glass frit, or the like, is
added to improve strength of adhesion, ohmic contact characteristic
deteriorates and, accordingly, voltage nonlinearity
deteriorates.
[0008] As described above, in such a semiconductor electronic part,
strength of adhesion between the internal electrode and the
semiconductor ceramic substrate was generally insufficient, so that
various troubles occurred in production steps. Actually, in the
steps of producing the semiconductor electronic part, there are
several steps for acting physical stress such as thermal contact
bonding, cutting, separation, etc., on the semiconductor ceramic
substrate. Hence, there was a risk that the physical stress might
cause troubles such as electrode peeling etc. at an end edge of the
semiconductor ceramic substrate. As a result, failure in
characteristic occurred frequently. This caused lowering of the
yield of products.
[0009] An electrode shaped like an I-type pattern or a T-type
pattern is generally known as the internal electrode in the
semiconductor electronic part.
[0010] If the internal electrode is shaped like the I-type pattern,
the aforementioned problem appears more remarkably. Specifically,
if the internal electrode is shaped like the I-type pattern, the
internal electrode has a small portion exposed at the end edge of
the semiconductor ceramic substrate. Hence, when a terminal
electrode was applied onto the semiconductor ceramic substrate and
baked, strength of adhesion between the internal electrode and the
terminal electrode was so weak that failure in characteristic
occurred in the peeling test (easy adhesive strength test).
[0011] If the internal electrode is shaped like the T-type pattern,
the internal electrode has a large portion exposed at the end edge
of the semiconductor ceramic substrate in comparison with the
I-type internal electrode. Hence, strength of adhesion between the
T-type internal electrode and the terminal electrode is larger than
that between the I-type internal electrode and the terminal
electrode so that the occurrence of electrode peeling decreases. In
this case, however, chopping or cracking was easily caused by
physical stress because the internal electrode is exposed up to a
corner of the semiconductor ceramic substrate. As a result, failure
in characteristic occurred frequently. This caused lowering of the
yield of products.
SUMMARY OF THE INVENTION
[0012] An object of the present invention is to provide a
semiconductor electronic part in which strength of adhesion of an
internal electrode to a semiconductor ceramic substrate is so large
that troubles such as electrode peeling, chipping, cracking, etc.
can be prevented securely.
[0013] Another object of the present invention is to provide a
semiconductor electronic part which is high in reliability because
failure in characteristic little occurs.
[0014] To solve the aforementioned problem, the semiconductor
electronic part according to the present invention comprises a
semiconductor ceramic substrate, and at least one internal
electrode.
[0015] The internal electrode is provided inside the semiconductor
ceramic substrate. The internal electrode has one end side led out
to an end edge of the semiconductor ceramic substrate, and at least
one cutout region. The cutout region is provided inside the
internal electrode.
[0016] As described above, the internal electrode is protected by
the semiconductor ceramic substrate because it is provided inside
the semiconductor ceramic substrate. Hence, a semiconductor
electronic part excellent in corrosion resistance, oxidation
resistance, impact resistance, etc. is obtained.
[0017] The internal electrode has one end side led out to an end
edge of the semiconductor ceramic substrate. According to this
structure, the semiconductor electronic part can be used as a
chip-like electronic part by adding terminal electrodes to end
edges of the semiconductor ceramic substrate.
[0018] The internal electrode has at least one cutout region at its
one end side. According to this structure, the cutout region of the
internal electrode is filled with the semiconductor ceramic
substrate as if the internal electrode is stitched by the
semiconductor ceramic substrate filled in the cutout region.
Accordingly, strength of adhesion between the internal electrode
and the semiconductor ceramic substrate increases. Hence, troubles
such as electrode peeling, chipping, cracking, etc. can be
prevented securely. As a result, a semiconductor electronic part
which is so high in reliability that the occurrence of failure in
characteristic can be reduced is obtained.
[0019] Preferably, a plurality of cutout regions are provided. In
this case, strength of adhesion between the internal electrode and
the semiconductor ceramic substrate can be increased more greatly
compared with the case where one cutout region is provided. Hence,
troubles such as electrode peeling etc. can be prevented securely.
As a result, the reliability of the semiconductor electronic part
is improved more greatly, so that the occurrence of failure in
characteristic is reduced more greatly.
[0020] Preferably, the cutout regions are provided to be distanced
from one another in a direction of the width of the semiconductor
ceramic substrate. In this case, strength of adhesion between the
internal electrode and the semiconductor ceramic substrate can be
increased more greatly compared with the case where one cutout
region is provided at one side of the internal electrode in the
direction of the width thereof. Hence, troubles such as electrode
peeling etc. can be prevented securely. As a result, the
reliability of the semiconductor electronic part is improved more
greatly, so that the occurrence of failure in characteristic is
reduced more greatly.
[0021] Other objects, configurations and advantages of the present
invention will be described more in detail with reference to the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a perspective view showing a semiconductor
electronic part according to the present invention.
[0023] FIG. 2 is an enlarged sectional view taken along the line
2-2 in FIG. 1.
[0024] FIG. 3 is a sectional view taken along the line 3-3 in FIG.
2.
[0025] FIG. 4 is a sectional view taken along the line 4-4 in FIG.
2.
[0026] FIG. 5 is a sectional view taken along the line 5-5 in FIG.
2.
[0027] FIG. 6 is a sectional view taken along the line 6-6 in FIG.
2.
[0028] FIG. 7 is a sectional view taken along the line 7-7 in FIG.
2.
[0029] FIG. 8 is a sectional view showing another embodiment of the
semiconductor electronic part according to the present
invention.
[0030] FIG. 9 is a sectional view showing another embodiment of the
semiconductor electronic part according to the present
invention.
[0031] FIG. 10 is a schematic view for explaining a step for
producing the semiconductor electronic part according to the
present invention.
[0032] FIGS. 11(a) and 11(b) are schematic views for explaining
production steps next to FIG. 10.
[0033] FIG. 12 is a plan view showing an intermediate product
obtained by the production step in FIGS. 11(a) and 11(b).
[0034] FIGS. 13(a) and 13(b) are schematic views for explaining
production steps next to FIGS. 11(a) and 11(b).
[0035] FIG. 14 is a partly cutaway sectional view showing an
intermediate product obtained by the production step in FIGS. 13(a)
and 13(b).
[0036] FIGS. 15(a) and 15(b) are schematic views for explaining a
production step next to FIGS. 13(a) and 13(b).
[0037] FIG. 16 is a schematic view for explaining a production step
next to FIGS. 15(a) and 15(b).
[0038] FIG. 17 is an enlarged sectional view showing an
intermediate product obtained by the production step in FIG.
16.
[0039] FIGS. 18(a) and 18(b) are schematic views for explaining
steps for producing the semiconductor electronic part according to
the present invention.
[0040] FIGS. 19(a) and 19(b) are schematic views for explaining a
production step next to FIGS. 18(a) and 18(b).
[0041] FIGS. 20(a), 20(b) and 20(c) are schematic views for
explaining production steps next to FIGS. 19(a) and 19(b).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] Semiconductor Electronic Part
[0043] FIG. 1 is a perspective view showing a semiconductor
electronic part according to the present invention. FIG. 2 is an
enlarged sectional view taken along the line 2-2 in FIG. 1. FIG. 3
is a sectional view taken along the line 3-3 in FIG. 2. FIG. 4 is a
sectional view taken along the line 4-4 in FIG. 2. FIG. 5 is a
sectional view taken along the line 5-5 in FIG. 2. An embodiment
shown in FIGS. 1 to 5 shows a varistor. The present invention is
not limited thereto but maybe applied also to semiconductor
electronic parts such as PTC thermistor, NTC thermistor,
semiconductor capacitor, etc.
[0044] The semiconductor electronic part shown in the drawings
comprises a semiconductor ceramic substrate 1, and internal
electrodes 21 to 24. For example, the semiconductor ceramic
substrate 1 is shaped like a rectangle about 1.0 mm long, about 0.5
mm wide and about 0.5 mm thick.
[0045] The semiconductor ceramic substrate 1 is selected in
accordance with the kind of the semiconductor electronic part to be
obtained. Because a varistor is shown in this embodiment, it will
go well if the semiconductor ceramic substrate 1 is made of
voltage-nonlinearity semiconductor ceramics as described above.
[0046] The internal electrodes 21 to 24 are provided inside the
semiconductor ceramic substrate 1 so as to be distanced from one
another in a thicknesswise direction Z. Each of the internal
electrodes 21 and 23 has one end led out to one end edge of the
semiconductor ceramic substrate 1 in the lengthwise direction X.
Each of the internal electrodes 22 and 24 has the other end led out
to the other end edge of the semiconductor ceramic substrate 1 in
the lengthwise direction X.
[0047] The internal electrode 21 has cutout regions 31 and 32. The
internal electrode 22 has cutout regions 33 and 34. The internal
electrode 23 has cutout regions 35 and 36. The internal electrode
24 has cutout regions 37 and 38. In this embodiment, as shown in
FIGS. 3 and 4, each of the cutout regions 31 to 38 is shaped like a
rectangle.
[0048] The cutout regions 31 and 32 are provided at one end edge of
the internal electrode 21 in the lengthwise direction X so as to be
separated by a distance from each other in a widthwise direction Y.
The cutout regions 33 and 34 are provided at the other end edge of
the internal electrode 22 in the lengthwise direction X so as to be
separated by a distance from each other in the widthwise direction
Y. The cutout regions 35 and 36 are provided at one end edge of the
internal electrode 23 in the lengthwise direction X so as to be
separated by a distance from each other in the widthwise direction
Y. The cutout regions 37 and 38 are provided at the other end edge
of the internal electrode 24 in the lengthwise direction X so as to
be separated by a distance from each other in the widthwise
direction Y.
[0049] In this embodiment, the internal electrodes 21 to 24 are of
the so-called T-type. The internal electrodes 21 and 22 will be
described below by way of example.
[0050] As shown in FIGS. 3, 5 and 7, the internal electrode 21 has
a main electrode portion 211, and a pick-up electrode portion 212.
As shown in FIG. 3, the pick-up electrode portion 212 is provided
on one end side of the main electrode portion 211 in the lengthwise
direction X. The pick-up electrode portion 212 has a width W2
approximately equal to the width of the semiconductor ceramic
substrate 1. The main electrode portion 211 has a width W1 smaller
than the width W2 of the pick-up electrode portion 212.
[0051] As shown in FIGS. 4, 6 and 7, the internal electrode 22 has
a main electrode portion 221, and a pick-up electrode portion 222.
As shown in FIG. 4, the pick-up electrode portion 222 is provided
on the other end side of the main electrode portion 221 in the
lengthwise direction X. The pick-up electrode portion 222 has a
width W2 approximately equal to the width of the semiconductor
ceramic substrate 1. The main electrode portion 221 has a width W1
smaller than the width W2 of the pick-up electrode portion 222.
[0052] Because a varistor is shown in this embodiment, it will go
well if each of the internal electrodes 21 to 24 is made of a
material that comes into ohmic contact with the aforementioned
semiconductor ceramic substrate. Although this embodiment has shown
the case where four internal electrodes 21 to 24 are provided, the
number of internal electrodes can be changed at option. Though not
shown, each of the internal electrodes 21 to 24 may be shaped like
any figure other than the T-type such as an I-type.
[0053] The semiconductor electronic part shown in this embodiment
further comprises terminal electrodes 41 and 42. The terminal
electrode 41 is provided at one end of the semiconductor ceramic
substrate 1 in the lengthwise direction X and connected to end
portions of the internal electrodes 21 and 23. The terminal
electrode 42 is provided at the other end of the semiconductor
ceramic substrate 1 in the lengthwise direction X and connected to
end portions of the internal electrodes 22 and 24.
[0054] As described above, because the internal electrodes 21 to 24
are disposed inside the semiconductor ceramic substrate 1, the
internal electrodes 21 to 24 are protected by the semiconductor
ceramic substrate 1. Hence, a semiconductor electronic part
excellent in corrosion resistance, oxidation resistance, impact
resistance, etc. is obtained.
[0055] Each of the internal electrodes 21 and 23 has one end led
out to one end edge of the semiconductor ceramic substrate 1 in the
lengthwise direction X. Each of the internal electrodes 22 and 24
has the other end led out to the other end edge of the
semiconductor ceramic substrate 1 in the lengthwise direction X.
According to this structure, the semiconductor electronic part can
be used as a chip-like electronic part by provision of the terminal
electrodes 41 and 42 in end edges of the semiconductor ceramic
substrate 1.
[0056] The one-end sides of the internal electrodes 21 to 24 have
cutout regions (31, 32) to (37, 38) respectively. According to this
structure, the cutout regions (31, 32) to (37, 38) of the internal
electrodes 21 to 24 are filled with the semiconductor ceramic
substrate 1 as if the internal electrodes 21 to 24 are stitched by
the semiconductor ceramic substrate 1 filled in the cutout regions
(31, 32) to (37, 38) . Hence, strength of adhesion between the
internal electrodes 21 to 24 and the semiconductor ceramic
substrate 1 increases. Hence, troubles such as electrode peeling,
chipping, cracking, etc., can be securely prevented. As a result,
it is possible to obtain a semiconductor electronic part which is
so high in reliability that any failure in characteristic does not
occur.
[0057] In this embodiment, the internal electrodes 21 to 24 have
the cutout regions (31, 32) to (37, 38) respectively. In this case,
because strength of adhesion between the internal electrodes 21 to
24 and the semiconductor ceramic substrate 1 can be increased more
greatly in comparison with the case where one cutout region is
provided, troubles such as electrode peeling, etc., can be
prevented more securely. As a result, the reliability of the
semiconductor electronic part is improved more greatly.
[0058] Further, in this embodiment, the cutout regions 31 and 32
are provided at one end edge of the internal electrode 21 in the
lengthwise direction X so as to be separated by a distance from
each other in the widthwise direction Y. The cutout regions 33 and
34 are provided at the other end edge of the internal electrode 22
in the lengthwise direction X so as to be separated by a distance
from each other in the widthwise direction Y. The cutout regions 35
and 36 are provided at one end edge of the internal electrode 23 in
the lengthwise direction X so as to be separated by a distance from
each other in the widthwise direction Y. The cutout regions 37 and
38 are provided at one end edge of the internal electrode 24 in the
lengthwise direction X so as to be separated by a distance from
each other in the widthwise direction Y. In this case, because
strength of adhesion between the internal electrodes 21 to 24 and
the semiconductor ceramic substrate 1 can be increased more greatly
compared with the case where one cutout region is provided at one
side of the internal electrodes 21 to 24 in the widthwise
direction, troubles such as electrode peeling, etc., can be
prevented more securely. As a result, the reliability of the
semiconductor electronic part is improved more greatly.
[0059] Further, in this embodiment, each of the internal electrodes
21 to 24 is shaped like the so-called T-type pattern. In this case,
troubles such as electrode peeling, etc., can be prevented
securely. Moreover, because of the positions where the cutout
regions are provided, troubles such as chipping, cracking, etc.
caused by physical stress can be prevented from occurring.
[0060] The effect of the embodiment shown in FIGS. 1 to 7 will be
described below more specifically with reference to actually
measured data.
[0061] Sample number #1 shows a conventional product having I-type
internal electrodes. Sample number #2 shows a conventional product
having T-type internal electrodes.
[0062] Sample number #3 shows a semiconductor electronic part
according to the present invention having the structure shown in
FIGS. 1 to 7. Table 1 shows the rate of occurrence of defects
(chipping, cracking) in external appearance and the rate of
occurrence of electrode peeling with respect to the semiconductor
electronic parts shown as sample numbers #1 to #3. In the electrode
peeling test, electrode peeling between the internal electrodes and
the terminal electrodes is detected in the condition that adhesive
double coated tapes are first stuck onto surfaces of the terminal
electrodes and then peeled therefrom.
1 TABLE 1 Electrode Defect in External Appearance Peeling Test
Chipping Cracking Peeling Rate (the number of (the number of (the
number of defectives/ defectives/ defectives/ the number of the
number of the number of Sample Number samples) samples) samples) #1
9/1000 2/10000 3/1000 (Comparative Example 1) #2 43/1000 7/10000
0/1000 (Comparative Example 2) #3 0/1000 0/10000 0/1000
(Example)
[0063] As shown in Table 1, electrode peeling is observed in 3 in
1000 samples in the semiconductor electronic part shown as sample
number #1 whereas all 1000 samples are good products in the
semiconductor electronic part shown as sample number #3.
[0064] Further, chipping is observed in 43 in 1000 samples in the
semiconductor electronic part shown as sample number #2 whereas all
1000 samples are good products in the semiconductor electronic part
shown as sample number #3. Further, cracking is observed in 7 in
10000 samples in the semiconductor electronic part shown as sample
number #2 whereas all 10000 samples are good products in the
semiconductor electronic part shown as sample number #3. It is
apparent from these results that the semiconductor electronic part
according to the present invention can prevent troubles such as
electrode peeling, chipping, cracking, etc. securely.
[0065] FIGS. 8 and 9 are sectional views showing other embodiments
of the semiconductor electronic part according to the present
invention. In the drawings, constituent parts the same as those
shown in FIGS. 1 to 7 are referenced correspondingly. Although the
drawings show the internal electrode 22, they can be applied to the
other electrodes 21, 23 and 24.
[0066] The embodiment shown in FIG. 8 is characterized in that each
of the cutout regions 31 to 38 is shaped like a half circle. The
embodiment shown in FIG. 9 is characterized in that the cutout
regions 31 to 38 are provided on the inside of an end edge of
pick-up electrode portions 212 to 242. Each of the embodiments
fulfills the same operation and effect as those in the embodiment
shown in FIGS. 1 to 7.
[0067] Method of Producing Semiconductor Electronic Part
[0068] A sheet lamination method, a printing method, or the like,
is known as a method of producing the semiconductor electronic part
according to the present invention. The producing method will be
described below with reference to the drawings, taking the
semiconductor electronic part shown in FIGS. 1 to 7 as an
example.
[0069] FIGS. 10 to 17 are schematic views for explaining the sheet
lamination method. First, as shown in FIG. 10, a semiconductor
ceramic paste 51, which is prepared by weighing and mixing
semiconductor ceramic powder, an organic binder and a solvent in a
predetermined proportion, is applied onto a flexible support film
50 by a method such as a doctor blade method, an extrusion method,
or the like. Thus, a ceramic film is obtained. The doctor blade
method will be described below.
[0070] As shown in FIG. 10, a coating apparatus 52 includes a feed
roller 521, a take-up roller 522, a doctor blade 523, and auxiliary
rollers 524 and 525. The feed roller 521 and the take-up roller 522
are arranged so as to be separated by a distance from each other.
The feed roller 521 is wound with one end side of the flexible
support film 50, while the take-up roller 522 is wound with the
other end side of the flexible support film 50. The doctorblade 523
applies the semiconductor ceramic paste 51 onto one surface side of
the flexible support film 50 which is running in one direction a.
The auxiliary rollers 524 and 525 are arranged so as to come into
contact with the opposite surface of the flexible support film 50
to the surface of the flexible support film 50 onto which the
semiconductor ceramic paste 51 is applied. In this manner, a
required number of semiconductor ceramic sheets each having a
thickness of from about 0.05 mm to about 0.5 mm are produced.
[0071] Then, as shown in FIGS. 11(b) and 12, a conductor paste 20
is applied onto the semiconductor ceramic sheet 11 to thereby form
an electrically conductive coating film set Q. The electrically
conductive coating film set Q is constituted by a matrix of three
rows and three columns of electrically conductive coating films Q11
to Q33, and an electrically conductive coating film Q00. Although
the arrangement of the electrically conductive coating films Q11 to
Q33 is expressed as a matrix of three rows and three columns, the
number of rows and the number of columns can be changed at option.
The electrically conductive coating film Q00 plays the role of a
marker at the time of cutting thereafter. A screen printing method
using a screen 61 and a squeegee 62 as shown in FIG. 11(a) is
suitable for a method of applying the conductor paste 20. The
reference numeral 60 designates a support table on which the
semiconductor ceramic sheet 11 is mounted.
[0072] Then, the semiconductor ceramic sheets 11 to 15 obtained in
the aforementioned steps are piled up as shown in FIG. 13(a). Then,
as shown in FIGS. 13(b) and 14, the semiconductor ceramic sheets 11
to 15 are hot-pressed to thereby obtain a green sheet 10 made from
the semiconductor ceramic sheets 11 to 15. The temperature and
pressure for hot-pressing are preferably in a range of from 40 to
120.degree. C. and in a range of from about
50.times.9.8.times.10.sup.4 Pa to about
1000.times.9.8.times.10.sup.4 Pa, respectively.
[0073] Then, the green sheet 10 is divided individually in the X
and Y directions (see FIG. 14) in accordance with the arrangement
of the electrically conductive coating films Q11 to Q33 to thereby
obtain green chips. A dicing method in which a disk-like blade 71
is rotated to perform cutting as shown in FIG. 15(a), a
force-cutting method in which a V-shaped blade 72 is moved up and
down to perform cutting as shown in FIG. 15(b), or the like, is
known as the dividing method.
[0074] The green chips 100 obtained thus are subjected to a binder
removing step as shown in FIG. 16, so that a binder contained in
each green chip 100 is removed by heating. The green chips 100 are
further kept in the temperature condition of about 1000.degree. C.
for about 10 minutes to thereby fire the green chips 100. The
reference numeral 8 designates a firing furnace.
[0075] In this manner, a sintered body in which the internal
electrodes 21 to 24 are provided inside the semiconductor ceramic
substrate 1 so as to be distanced from one another in the
thicknesswise direction is obtained as shown in FIG. 17. Then, the
terminal electrodes 41 and 42 each containing silver or copper as a
main component are added. Then, the terminal electrodes 41 and 42
are electroplated with Ni, Sn and solder. Thus, the semiconductor
electronic part which is a final product shown in FIGS. 1 to 7 is
completed.
[0076] FIGS. 18(a) to 20(c) are schematic views for explaining a
printing method. In the drawings, constituent parts the same as
those shown in FIGS. 10 to 17 are referenced correspondingly.
[0077] First, as shown in FIG. 18(a), application of a
semiconductor ceramic paste 51 onto a support table 60 is repeated
by a required number of times by use of a screen 61 and a squeegee
62. Thus, a semiconductor ceramic sheet 11 is obtained as shown in
FIG. 18(b).
[0078] Then, as shown in FIG. 19(a), a conductor paste 20 is
applied onto the semiconductor ceramic sheet 11 by use of the
screen 61 and the squeegee 62. Thus, as shown in FIG. 19(b), an
arrangement of electrically conductive coating films Q11 to Q33 and
Q00 is formed on the semiconductor ceramic sheet 11.
[0079] Further, as shown in FIGS. 20(a) and 20(b), the
semiconductor ceramic paste 51 and the conductor paste 20 are
alternately applied by use of the screen 61 and the squeegee 62 to
thereby obtain a green sheet 10 shown in FIG. 20(c).
[0080] The green sheet 10 obtained thus is subjected to the
individually dividing step, the binder removing step and the firing
step and then the terminal electrodes 41 and 42 are added to the
green sheet, in the same manner as that in the sheet lamination
method. Thus, the semiconductor electronic part which is a final
product is obtained.
[0081] As described above, according to the present invention, the
following effects can be obtained.
[0082] (a) There can be provided a semiconductor electronic part in
which strength of adhesion of the internal electrode to a
semiconductor ceramic substrate is so large that troubles such as
electrode peeling, chipping, cracking, etc. can be prevented
securely.
[0083] (b) There can be provided a semiconductor electronic part
which is high in reliability because failure in characteristic
little occurs.
* * * * *