U.S. patent application number 09/970713 was filed with the patent office on 2002-04-18 for dielectric composition and ceramic capacitor using the same.
This patent application is currently assigned to TDK CORPORATION. Invention is credited to Fujikawa, Yoshinori, Masumiya, Kaori, Nagai, Akiko, Satoh, Shigeki.
Application Number | 20020045533 09/970713 |
Document ID | / |
Family ID | 11682684 |
Filed Date | 2002-04-18 |
United States Patent
Application |
20020045533 |
Kind Code |
A1 |
Satoh, Shigeki ; et
al. |
April 18, 2002 |
Dielectric composition and ceramic capacitor using the same
Abstract
A dielectric composition containing at least calcium titanate,
strontium titanate, and barium titanate, wherein at least the molar
ratios of composition of the three are such that the molar ratio of
composition (P) of calcium titanate is 0.5 to 0.85, the molar ratio
of composition (Q) of strontium titanate is 0.05 to 0.4, and the
molar ratio of composition (R) of barium titanate is 0.1 to 0.2
(where, P+Q+R=1).
Inventors: |
Satoh, Shigeki; (Tokyo,
JP) ; Fujikawa, Yoshinori; (Tokyo, JP) ;
Nagai, Akiko; (Tokyo, JP) ; Masumiya, Kaori;
(Tokyo, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
TDK CORPORATION
Tokyo
JP
|
Family ID: |
11682684 |
Appl. No.: |
09/970713 |
Filed: |
October 5, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09970713 |
Oct 5, 2001 |
|
|
|
09481505 |
Jan 12, 2000 |
|
|
|
Current U.S.
Class: |
501/137 |
Current CPC
Class: |
C04B 35/468
20130101 |
Class at
Publication: |
501/137 |
International
Class: |
C04B 035/468; C04B
035/465; C04B 035/47 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 14, 1999 |
JP |
11-8056 |
Claims
What is claimed:
1. A dielectric composition containing at least calcium titanate,
strontium titanate, and barium titanate, wherein in the three molar
ratios of composition, at least the molar ratio of composition of
the barium titanate is not more than 0.3 and at least one crystal
structure of tetragonal crystal and orthorhombic crystal structures
is contained.
2. A dielectric composition containing at least calcium titanate,
strontium titanate, and barium titanate, where at least the three
molar ratios of composition of these are such that the molar ratio
of composition (P) of calcium titanate is 0.5 to 0.85, the molar
ratio of composition (Q) of strontium titanate is 0.05 to 0.4, and
the molar ratio of composition (R) of barium titanate is 0.05 to
0.2, however, P+Q+R=1.
3. A dielectric composition as set forth in claim 2, including at
least one crystal structure of tetragonal crystal and orthorhombic
crystal structures.
4. A dielectric composition as set forth in claim 1, wherein the
rate of change of electrostatic capacity with respect to
temperature is within .+-.15% at least in a temperature range of
-30.degree. C. to +85.degree. C. (reference temperature of
25.degree. C.).
5. A dielectric composition as set forth in claim 2, wherein the
rate of change of electrostatic capacity with respect to
temperature is within .+-.15% at least in a temperature range of
-30.degree. C. to +85.degree. C. (reference temperature of
25.degree. C.).
6. A dielectric composition as set forth in claim 1, further
containing a reduction resistance aid.
7. A dielectric composition as set forth in claim 2, further
containing a reduction resistance aid.
8. A dielectric composition as set forth in claim 1, further
containing a sintering aid.
9. A dielectric composition as set forth in claim 2, further
containing a sintering aid.
10. A dielectric composition as set forth in claim 8, wherein said
sintering aid is at least one type of glass composition selected
from the following G group, M group, and L group: G group:
SiO.sub.2 and Al.sub.2O.sub.3 M group: BaO, CaO, and SrO L group:
Li.sub.2O, Na.sub.2O, K.sub.2O, and B.sub.2O.sub.3
11. A dielectric composition as set forth in claim 9, wherein said
sintering aid is at least one type of glass composition selected
from the following G group, M group, and L group: G group:
SiO.sub.2 and Al.sub.2O.sub.3 M group: BaO, CaO, and SrO L group:
Li.sub.2O, Na.sub.2O, K.sub.2O, and B.sub.2O.sub.3
12. A dielectric composition as set forth in claim 8, containing
0.2 mol % to 5 mol % of said sintering aid.
13. A dielectric composition as set forth in claim 9, containing
0.2 mol % to 5 mol % of said sintering aid.
14. A dielectric composition as set forth in claim 10, wherein when
the ratios of composition of the G group, M group, and L group are
expressed by a triangular diagram (G, M, and L), the ratio of
composition of the sintering aid is in the area surrounded by the
following points X1 to X5 (including on lines):
6 X1: (0.0, 0.0, 1.0) X2: (0.0, 0.5, 0.5) X3: (0.1, 0.65, 0.25) X4:
(0.5, 0.0, 0.5) X5: (0.65, 0.05, 0.3).
15. A dielectric composition as set forth in claim 11, wherein when
the ratios of composition of the G group, M group, and L group are
expressed by a triangular diagram (G, M, and L), the ratio of
composition of the sintering aid is in the area surrounded by the
following points X1 to X5 (including on lines):
7 X1: (0.0, 0.0, 1.0) X2: (0.0, 0.5, 0.5) X3: (0.1, 0.65, 0.25) X4:
(0.5, 0.0, 0.5) X5: (0.65, 0.05, 0.3).
16. A dielectric composition as set forth in claim 10, wherein when
the ratios of composition of the G group, M group, and L group are
expressed by a triangular diagram (G, M, and L), the ratio of
composition of the sintering aid is in the area surrounded by the
following points X1, X6, X7, and X5
8 X1: (0.0, 0.0, 1.0) X6: (0.0, 0.2, 0.8) X7: (0.3, 0.4, 0.3) X5:
(0.5, 0.0, 0.5)
17. A dielectric composition as set forth in claim 11, wherein when
the ratios of composition of the G group, M group, and L group are
expressed by a triangular diagram (G, M, and L), the ratio of
composition of the sintering aid is in the area surrounded by the
following points X1, X6, X7, and X5 (including on lines):
9 X1: (0.0, 0.0, 1.0) X6: (0.0, 0.2, 0.8) X7: (0.3, 0.4, 0.3) X5:
(0.5, 0.0, 0.5).
18. A dielectric composition as set forth in claim 1, further
containing at least one oxide selected from V.sub.2O.sub.5,
MoO.sub.3, WO.sub.3, and CO.sub.3O.sub.4.
19. A dielectric composition as set forth in claim 2, further
containing at least one oxide selected from V.sub.2O.sub.5,
MoO.sub.3, WO.sub.3, and CO.sub.3O.sub.4.
20. A dielectric composition as set forth in claim 1, further
containing at least one oxide selected from Nb.sub.2O.sub.5,
Ta.sub.2O.sub.5, Y.sub.2O.sub.3, La.sub.2O.sub.3, CeO.sub.2,
Gd.sub.2O.sub.3, Dy.sub.2O.sub.3, and Ho.sub.2O.sub.3.
21. A dielectric composition as set forth in claim 2, further
containing at least one oxide selected from Nb.sub.2O.sub.5,
Ta.sub.2O.sub.5, Y.sub.2O.sub.3, La.sub.2O.sub.3, CeO.sub.2,
Gd.sub.2O.sub.3, Dy.sub.2O.sub.3, and Ho.sub.2O.sub.3.
22. A ceramic capacitor having an internal electrode and a
dielectric layer, wherein the dielectric layer is comprised of a
composition as set forth in claim 1.
23. A ceramic capacitor having an internal electrode and a
dielectric layer, wherein the dielectric layer is comprised of a
composition as set forth in claim 2.
24. A ceramic capacitor as set forth in claim 22, wherein the
internal electrode is comprised of Ni or an Ni alloy.
25. A ceramic capacitor as set forth in claim 23, wherein the
internal electrode is comprised of Ni or an Ni alloy.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a dielectric composition
and a ceramic capacitor using the same, more particularly relates
to a dielectric composition superior in resistance to reduction at
the time of sintering, exhibiting a high dielectric constant and
low distortion factor, and superior in the temperature-dependence
of the capacity and to a ceramic capacitor having a high insulation
resistance, high capacity, and low distortion characteristic,
having a flat temperature-dependence of the capacity, and using a
base metal for the internal electrodes.
[0003] 2. Description of the Related Art
[0004] As a dielectric composition used for a ceramic capacitor,
one having a high dielectric constant comprised mainly of barium
titanate (BaTiO.sub.3) is known, but since it is a strong
dielectric, the nonlinear characteristic of the voltage is strong
and the distortion factor originate from D-E hysterisys loop is a
large -50 dB to -70 dB. Therefore, a BaTiO.sub.3 based capacitor
cannot be used for a capacitor for which a low distortion factor is
required-such as a coupling circuit capacity, audio circuit
capacitor, or image processing circuit capacitor. Film capacitors,
electrolytic capacitors, etc. are exclusively being used for these,
but such film capacitors or electrolytic capacitors are hard to
reduce in size and there are problems in surface mounting.
[0005] On the other hand, among the ceramic capacitors, ones
comprised of ordinary dielectrics such as CaTiO.sub.3, SrTiO.sub.3,
CaSrZrO.sub.3, and NdTiO.sub.3 are low in distortion factor and
therefore can be used for coupling circuits, audio circuits, etc.,
but since they are ordinary dielectrics, the dielectric constant
.epsilon.r is a low 30 to 200 and obtaining a high capacity
capacitor would be difficult.
[0006] Therefore, as a dielectric composition exhibiting both a
high dielectric constant and low distortion factor, ones comprised
mainly of SrTiO.sub.3, Bi.sub.2TiO.sub.3, CaTiO.sub.3, and
PbTiO.sub.3 have been proposed (for example, see Japanese
Unexamined Patent Publication (Kokai) No. 3-97669).
[0007] Internal electrodes of a ceramic capacitor, however, use a
precious metal such as platinum Pt, gold Au, Pd or silver Ag, and
their alloy for example, Pt--Au, Ag--Pd but from the viewpoint of
cost, nickel or another base metal is preferably used.
[0008] The above-mentioned dielectric composition contains bismuth
Bi or lead Pb which have a low vapor pressure, so when sintered in
a reducing atmosphere, these end up evaporating. Accordingly, while
predicated on sintering in an oxidizing atmosphere, if sintered in
an oxidizing atmosphere, when using a low cost base metal, for
example, nickel, for the internal electrodes, the nickel ends up
being oxidized. In the end, there is no choice but to use a
precious metal such as platinum, gold, or silver for the internal
electrodes.
SUMMARY OF THE INVENTION
[0009] An object of the present invention is to provide a
dielectric composition superior in resistance to reduction at the
time of sintering, exhibiting a high dielectric constant and low
distortion factor, and superior in temperature-dependence of the
capacity and a capacitor having a high insulation resistance, high
capacity, and low distortion characteristic, having a flat
temperature-dependence of the capacity, and using a base metal for
the internal electrodes.
[0010] (1) The present inventors et al. engaged in in-depth
research in order to obtain a balanced dielectric composition
having a large dielectric constant, a small distortion factor, and
a small rate of change of the capacity with respect to temperature
(hereinafter referred to as a flat temperature-dependence of the
capacity) and as a result obtained the following discoveries.
[0011] First, the distortion factor depends on the field dependency
and non-linearity of the dielectric constant (that is, a strong
dielectric property). As measures for suppressing the factor, it
may be considered effective to improve the linearity of the
dielectric constant or reduce the crystalline anistrophy so as to
reduce the strong dielectric property or to use an ordinary
dielectric phase. If the strong dielectric property is reduced,
however, the dielectric constant falls, so balancing these becomes
important. Further, an ordinary dielectric exhibits a negative
temperature-dependence of the capacity, while a strong dielectric
exhibits a positive temperature-dependence of the capacity, so
balancing the strong dielectric and the ordinary dielectric becomes
important for the temperature-dependence of the capacity as
well.
[0012] The balance of the dielectric constant, distortion factor,
and temperature-dependence of the capacity becomes suitable by
controlling the molar ratios of composition of the calcium
titanate, strontium titanate, and barium titanate. In the present
invention, by adding the strong dielectric barium titanate to the
ordinary dielectric calcium titanate (or strontium titanate), the
balance of the ordinary dielectric phase and strong dielectric
phase is promoted and it is possible to obtain a dielectric
composition having a large dielectric constant, a small distortion
factor, and a flat temperature-dependence of the capacity.
[0013] That is, if the molar ratio of composition of barium
titanate is increased, while the dielectric constant becomes
larger, the distortion factor and the rate of change of the
capacity with respect to the temperature also become larger. As
opposed to this, if the molar ratio of composition of strontium
titanate is increased, while the distortion factor becomes smaller,
the dielectric constant also becomes smaller. Further, when the
molar ratio of composition of calcium titanate is increased too,
while the distortion factor becomes small, the dielectric constant
also becomes small.
[0014] Further, comparing calcium titanate and strontium titanate,
if the molar ratio of composition of calcium titanate is increased,
the rate of change of capacity with respect to temperature becomes
smaller, but the dielectric constant also becomes smaller. As
opposed to this, if the molar ratio of composition of strontium
titanate is increased, the dielectric constant becomes larger, but
the rate of change of the capacity with respect to temperature also
becomes larger.
[0015] (2) Based on this discovery, the first aspect of the
invention provides a dielectric composition containing at least
calcium titanate, strontium titanate, and barium titanate, wherein
the molar ratios of composition of the three are such that at least
a molar ratio of composition of the barium titanate is not more
than 0.3 and wherein the composition comprised of the calcium
titanate, strontium titanate, and barium titanate contains at least
one crystal structure from among tetragonal and orthorhombic
crystal structures.
[0016] The composition comprising calcium titanate, strontium
titanate, and barium titanate exhibits an insoluble phase and cubic
crystal structure as well due to these three ratios of composition,
but ratios of composition exhibiting mainly an insoluble phase are
not desirable since the distortion factor is large, while ratios of
composition exhibiting mainly a cubic crystal structure is not
desirable since the distortion factor is large and the rate of
change of the capacity with respect to the temperature is also
large.
[0017] Further, a cubic crystal structure is exhibited in the
region where the barium titanate is rich, but in this region, the
molar ratio of composition of the barium titanate is large, so the
dielectric constant becomes large, but the distortion factor also
becomes large and the balance between the dielectric constant and
the distortion factor is poor. Therefore, a tetragonal crystal
structure in the region where the molar ratio of composition of
barium titanate is not more than 0.3 is more preferable.
[0018] In the above aspect of the invention, the crystal structure
of the dielectric composition obtained is not one which is
completely comprised of at least one of a tetragonal crystal and
orthorhombic crystal structure. It means the main crystal structure
is at least one of a tetragonal crystal and orthorhombic crystal
structure. Therefore, inclusion of an insoluble phase or cubic
crystal structure etc. in part of it is also included in the
technical scope of the present invention.
[0019] In particular, when the calcium titanate, strontium
titanate, and barium titanate are in ratios of composition of an
area near the transition point between a tetragonal crystal
structure and orthorhombic crystal structure, the balance between
the dielectric constant and distortion factor of course and also
the temperature-dependence of the capacity (temperature
coefficient) become good.
[0020] (3) Further, a second aspect of the present invention
provides a dielectric composition containing at least calcium
titanate and barium titanate, wherein when the calcium titanate is
CT and the barium titanate is BT,
(CT).sub.x(BT).sub.y(F).sub.1-x-y (where F is any component)
0.4.ltoreq.x<1, 0<y.ltoreq.0.2
[0021] are satisfied (see FIG. 2). Note that the third component F
is not particularly limited.
[0022] By controlling the ratios of composition of the ordinary
dielectric calcium titanate and the strong dielectric barium
titanate, it is possible to promote the balance of the ordinary
dielectric phase and strong dielectric phase and obtain a
dielectric composition having a large dielectric constant, a small
distortion factor, and a flat temperature-dependence of the
capacity.
[0023] If the molar ratio of composition (y) of the barium titanate
is large, the dielectric constant becomes large, but the distortion
factor also becomes large, so to obtain a balance between the
dielectric constant and the distortion factor, it is more
preferable that 0<y.ltoreq.0.2. Further, if the molar ratio of
composition (x) of the calcium titanate is small, the dielectric
constant becomes large, but the rate of change of the capacity with
respect to the temperature also becomes large
(temperature-dependence of the capacity deteriorates), so to obtain
a balance between the dielectric constant and the
temperature-dependence of the capacity, it is more preferable that
0.4.ltoreq.x<1.
[0024] (4) A third aspect of the present invention provides a
dielectric composition containing at least calcium titanate,
strontium titanate, and barium titanate, where at least the three
molar ratios of composition are such that
[0025] the molar ratio of composition (P) of calcium titanate is
0.5 to 0.85, the molar ratio of composition (Q) of strontium
titanate is 0.05 to 0.4, and the molar ratio of composition (R) of
barium titanate is 0.1 to 0.2 (however, P+Q+R=1) (see FIG. 3).
[0026] By adding the strong dielectric barium titanate to the
ordinary dielectrics calcium titanate and strontium titanate, the
balance of the ordinary dielectric phase and strong dielectric
phase is promoted and it is possible to obtain a dielectric
composition having a large dielectric constant, a small distortion
factor, and a flat temperature-dependence of the capacity.
[0027] If the molar ratio of composition (P) of the calcium
titanate is small, the dielectric constant becomes large, but the
rate of change of capacity with respect to temperature also tends
to become large (temperature-dependence deteriorates). Further, if
the molar ratio of composition (Q) of the strontium titanate is
large, both the distortion factor and the rate of change of
capacity with respect to temperature tend to become large. Further,
if the molar ratio of composition (R) of the barium titanate is
large, the dielectric constant becomes large, but the distortion
factor also tends to become large. Therefore, to obtain a balance
of the dielectric constant, distortion factor, and
temperature-dependence of the capacity, it is preferable that
0.55.ltoreq.P.ltoreq.0.8, 0.2.ltoreq.Q.ltoreq.0.35, and
0.12.ltoreq.R.ltoreq.0.18, in particular that the region be near
the transition point between the tetragonal crystal and
orthorhombic crystal structures.
[0028] (5) Note that in the second and third aspects of the
invention, it is preferable that the dielectric composition include
at least one crystal structure from a tetragonal crystal and
orthorhombic crystal structure. Ratios of composition exhibiting
mainly an insoluble phase are not preferable since the distortion
factor becomes large, while ratios of composition exhibiting mainly
a cubic crystal structure is not preferable since the rate of
change of capacity with respect to temperature also becomes
large.
[0029] (6) The first to third aspects of the invention explained
above may also contain various additives.
[0030] (6-1) As the type of additives, MnO, CrO, and other
reduction resistance aids may be mentioned. These reduction
resistance aids have the effect of promoting sintering and the
effect of improving the insulation resistance (I.sub.R) but if
added in large amounts, the insulation resistance, dielectric loss
(tan .delta.), and distortion factor deteriorate, so the amount is
preferably made 0.1 to 1 mol %.
[0031] (6-2) Further, as other additives, a glass composition or
other sintering aid may be mentioned.
[0032] As a sintering aid preferably used in the present invention,
at least one type of glass composition selected from the G group of
SiO.sub.2 and Al.sub.2O.sub.3, M group of BaO, CaO, and SrO, and L
group of Li.sub.2O, Na.sub.2O, K.sub.2O, and B.sub.2O.sub.3 may be
mentioned.
[0033] In the dielectric composition of the present invention, if
the sintering temperature is not more than 1340.degree. C., a
sufficient sintered body cannot be obtained. If sintered at under
this temperature, a reduction in the dielectric constant and a
reduction in the insulation resistance IR occur and the distortion
factor increases. On the other hand, the additives SiO.sub.2,
Al.sub.2O.sub.3, V.sub.2O.sub.5, MoO.sub.3, WO.sub.3, and
Co.sub.3O.sub.4 have the side effect of causing a reduction in the
sintering temperature, but if the amounts added are increased, have
the defect of causing a reduction in the insulation resistance IR.
In general, lowering the sintering temperature has the effect of
improving the cover rate of the internal electrodes, the effect of
suppressing their becoming too thick, and other defects and the
effect of suppressing the oxidation and dispersion of the internal
electrodes. Therefore, by adding a sintering aid as in the present
invention, the state of the internal electrodes becomes good and
the reliability of the break down voltage etc. are improved.
Further, there is not that much of an effect on the
temperature-dependence of the capacity by the addition of the
sintering aid.
[0034] When added in a large amount, however, unevenness occurs in
the sintering ability and the insulation resistance and distortion
factor deteriorate, while when too little is added, the effect of
low temperature sintering is lost, so a range of 0.2 to 5 mol % is
preferable.
[0035] When using at least one type of glass composition selected
from the above G group, M group, and L group as the sintering aid,
preferably, when the ratios of composition of the G group, M group,
and L group are expressed by a triangular diagram (G, M, and L),
the ratio of composition of the sintering aid is in the area
surrounded by the following points X1 to X5 (including on
lines):
1 X1: (0.0, 0.0, 1.0) X2: (0.0, 0.5, 0.5) X3: (0.1, 0.65, 0.25) X4:
(0.5, 0.0, 0.5) X5: (0.65, 0.05, 0.3)
[0036] Further, more preferably, when the ratios of composition of
the G group, M group, and L group are expressed by a triangular
diagram, the ratio of composition of the sintering aid is in the
area surrounded by the following points X1, X6, X7, and X5
(including on lines):
2 X1: (0.0, 0.0, 1.0) X6: (0.0, 0.2, 0.8) X7: (0.3, 0.4, 0.3) X5:
(0.5, 0.0, 0.5)
[0037] (6-3) As other additives, it is possible to mention at least
one oxide selected from V.sub.2O.sub.5, MoO.sub.3, WO.sub.3, and
Co.sub.3O.sub.4. These have the effect of lowering the sintering
temperature and lowering the distortion factor. Among these,
V.sub.2O.sub.5 is most preferable. If these are added in large
amounts, the insulation resistance and the dielectric loss
remarkably deteriorate, so it is preferable to add them in the
range of 0.01 to 0.5 mol %.
[0038] (6-4) Further, as other additives, it is possible to mention
at least one oxide selected from Nb.sub.2O.sub.5, Ta.sub.2O.sub.5,
Y.sub.2O.sub.3, La.sub.2O.sub.3, CeO.sub.2, Gd.sub.2O.sub.3,
Dy.sub.2O.sub.3, and Ho.sub.2O.sub.3 These have the effect of
improving the dielectric loss and reducing the distortion factor.
These are preferably added in the range of 0.01 to 0.2 mol %.
[0039] (7) The dielectric composition according to the above
present invention is preferably used as a material of the
dielectric layer of a ceramic capacitor having internal electrodes
and the dielectric layer.
[0040] In this case, the internal electrodes are more preferably
comprised by Ni or an Ni alloy. A dielectric composition according
to the present invention is superior in reduction resistance, so
can be sintered in a reducing atmosphere, can use Ni or an Ni alloy
for the internal electrodes, and can be reduced in cost.
[0041] Note that the structure of the ceramic capacitor etc. is not
particularly limited and includes not only a stacked type
capacitor, but also a single sheet type capacitor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] Embodiments of the present invention will be explained below
based on the drawings.
[0043] FIG. 1 is a view of the three-way composition of the main
ingredients of a dielectric composition of the present
invention,
[0044] FIG. 2 is a view of the three-way composition of the main
ingredients of a dielectric composition of the present
invention,
[0045] FIG. 3 is a view of the three-way composition of the main
ingredients of a dielectric composition of the present
invention,
[0046] FIG. 4 is a partially cutaway perspective view of an
embodiment of a capacitor of the present invention,
[0047] FIG. 5 is a view of the three-way composition showing the
ratios of composition of samples 1 to 31 in the examples,
[0048] FIG. 6 is a graph of the temperature-dependence of the
capacity (Y5R) in the examples, and
[0049] FIG. 7 is a triangular diagram of the ratios of composition
of samples 42 to 60 in the examples.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0050] The stacked type ceramic capacitor 1 shown in FIG. 4 is
comprised of internal electrodes 11 and dielectric layers 12
alternately stacked and a pair of external electrodes 13 connected
to the internal electrodes.
[0051] In this example, the internal electrodes 11 are formed from
nickel or a nickel alloy. While not particularly limited, as the
nickel alloy, an alloy of at least 95 wt % of nickel with at least
one of manganese, chrome, cobalt, aluminum, etc. is preferable.
Further, the nickel or nickel alloy may contain as trace
ingredients not more than 0.1 wt % of phosphorus etc.
[0052] The thickness and other conditions of the internal
electrodes 11 should be suitably determined in accordance with the
object and application, but ordinarily the thickness is 1 to 5
.mu.m, particularly 2 to 3 .mu.m.
[0053] The material of the dielectric layer 12 contains calcium
titanate, strontium titanate, and barium titanate. The molar ratios
of composition of these three are as explained above. Such a
composition has a perovskite (ABO.sub.3) structure. The A/B (molar
ratio) depends on the quality of the material, but the
characteristics are sufficiently satisfied if the ratio is in the
range of 0.99 to 1.02.
[0054] Further, the dielectric composition preferably has added to
it 0.1 to 1 mol % of a reduction resistance aid such as MnO or
Cr.sub.2O.sub.3, 0.2 to 5 mol % of a sintering aid of at least one
type of glass composition selected from a G group of SiO.sub.2 and
Al.sub.2O.sub.3, an M group of BaO, CaO, and SrO, and an L group of
Li.sub.2O, Na.sub.2O, K.sub.2O, and B.sub.2O.sub.3, 0.01 to 0.5 mol
% of at least one type of oxide selected from V.sub.2O.sub.5,
MoO.sub.3, WO.sub.3, and Co.sub.3O.sub.4, and 0.01 to 0.2 mol % of
at least one type of oxide selected from Nb.sub.2O.sub.5,
Ta.sub.2O.sub.5, Y.sub.2O.sub.3, La.sub.2O.sub.3. CeO.sub.2,
Gd.sub.2O.sub.3, Dy.sub.2O.sub.3, and Ho.sub.2O.sub.3.
[0055] Note that for the external electrodes 13, ordinary copper or
copper alloy, nickel or a nickel alloy, etc. may be used, but it is
also possible to use silver, an alloy of silver and palladium, etc.
The external electrodes 13 may be of any thickness. This should be
suitably determined in accordance with the object and application,
but ordinarily is 10 to 50 .mu.m.
[0056] Further, the shape and size of the stacked type ceramic
capacitor 1 should be suitably determined in accordance with the
object and application. For example, in the case of a
parallelopiped, the dimensions are ordinarily 1.6 to 3.2
mm.times.0.8 to 1.6 mm.times.0.6 to 1.2 mm.
[0057] The stacked type ceramic capacitor 1 of the present
embodiment may be fabricated as follows:
[0058] First, a dielectric layer paste, internal electrode paste,
and external electrode paste are produced.
[0059] The dielectric layer paste is produced by kneading a
dielectric material in accordance with the composition of the above
dielectric composition with an organic vehicle or by making a water
soluble coating agent. The dielectric material may be suitably
selected from various compounds comprised of the above composite
oxides or oxides, for example, carbonates, nitrates, hydroxides,
organic metal compounds, etc. and mixed for use. The content of the
compounds in the dielectric material should be determined to give
the above composition of the dielectric layer after sintering. The
dielectric material is ordinarily used as a powder of an average
particle size of 0.1 to 3.0 .mu.m or so.
[0060] The organic vehicle comprises a binder dissolved in an
organic solvent. The binder used for the organic vehicle is not
particularly limited and may be suitably selected from various
types of ordinary binders such as ethyl cellulose and polyvinyl
butyral. Further, the organic solvent used at this time is not
particularly limited either and should be suitably selected from
organic solvents such as terpineol, butyl carbitol, acetone, and
toluene in accordance with the method of use such as a printing
method or sheet method.
[0061] Further, the Aqueous binder system is comprised of water in
which a water soluble binder, dispersant, etc. are dissolved. The
water soluble binder is not particularly limited and should be
suitably selected from polyvinyl alcohol, cellulose, a water
soluble acrylic resin, an emulsion, etc.
[0062] The internal electrode paste is prepared by mixing
conductive materials comprised of the above various types of
conductive metals or alloys or various oxides forming the above
conductive materials after sintering, organic metal compounds,
resinates, etc., and the above organic vehicles. Further, the
external electrode paste can also be prepared in the same way as
the internal electrode paste.
[0063] The content of the organic vehicle of the above pastes is
not particularly limited, but may be made the ordinary content, for
example, about 1 to 5 wt % of a binder and about 10 to 50 wt % of a
solvent. Further, the pastes may contain, in accordance with need,
additives selected from various dispersants, plasticizers,
dielectrics, insulators, etc.
[0064] When using the printing method, the dielectric paste and the
internal electrode paste are screen printed on a substrate of
polyethylene terephthalate. The substrate is cut to predetermined
shapes, then the pastes peeled off from the substrate pieces to
obtain green chips. As opposed to this, when using the sheet
method, a dielectric paste is used to form a green sheet, the
internal electrode paste is printed on it, then these are stacked
to obtain green chips.
[0065] Next, the green chips are processed to remove the binder and
sintered. The processing for removing the binder is performed
before the sintering and may be performed under ordinary
conditions, but when using nickel or a nickel alloy or other base
metal as the conductive material of the internal electrode layer,
the conditions may be made an air atmosphere, a rate of temperature
rise of 5 to 300.degree. C./hour, more preferably 10 to 100.degree.
C./hour, a holding temperature of 180 to 400.degree. C., more
preferably 200 to 300.degree. C., and a temperature holding time of
0.5 to 24 hours, more preferably 5 to 20 hours.
[0066] The sintering atmosphere of the green chips should be
suitably determined in accordance with the type of the conductive
material in the internal electrode paste, but when using nickel or
a nickel alloy or other base metal as the conductive material, the
oxygen partial pressure in the sintering atmosphere is preferably
made 1.times.10.sup.-8 to 1.times.10.sup.-12. If the oxygen partial
pressure is too low, the conductive material of the internal
electrodes causes abnormal sintering and ends up breaking, while if
the oxygen partial pressure is too high, the internal electrodes
end up being oxidized. Further, the holding temperature during
sintering is 1100 to 1400.degree. C., more preferably 1200 to
1380.degree. C. If the holding temperature is too low, the
densification is insufficient, while if the holding temperature is
too high, the electrodes break due to the abnormal sintering of the
internal electrodes and the temperature-dependence of the capacity
deteriorates due to the dispersion of the material of the internal
electrodes.
[0067] As the other sintering conditions, the rate of temperature
rise is preferably made 50 to 500.degree. C./hour, more preferably
200 to 300.degree. C./hour, the temperature holding time is
preferably made 0.5 to 8 hours, more preferably 1 to 3 hours, the
cooling rate is made 50 to 500.degree. C./hour, more preferably 200
to 300.degree. C./hour, and the sintering atmosphere is made a
reducing atmosphere. As the atmospheric gas, it is preferable to
use a wet mixed gas of for example nitrogen gas and hydrogen
gas.
[0068] When sintering in a reducing atmosphere, it is preferable to
anneal the sintered capacitor chips. The annealing is processing
for reoxidizing the dielectric layer. This enables the insulation
resistance to be increased. The oxygen partial pressure of the
annealing atmosphere is preferably made at least 1.times.10.sup.-6
atmospheres, more preferably 1.times.10.sup.-5 to 1.times.10.sup.-4
atmospheres. If the oxygen partial pressure is too low, reoxidation
of the dielectric layer becomes difficult, while if the oxygen
partial pressure is too high, the internal electrodes are liable to
be oxidized. The holding temperature at the time of annealing is
not more than 1100.degree. C., more preferably 500 to 1100.degree.
C. If the holding temperature is too low, reoxidation of the
dielectric layer becomes insufficient, the insulation resistance
deteriorates, and the accelerated life also becomes shorter.
Further, if the holding temperature is too high, not only will the
internal electrodes oxidize and the capacity fall, but also the
dielectric base material will end up being reacted with and the
temperature-dependence of the capacity, insulation resistance, and
accelerated life will deteriorate. Note that the annealing may also
be comprised of only a temperature raising process and a
temperature lowering process. In this case, the temperature holding
time becomes zero and the holding temperature becomes synonymous
with the maximum temperature.
[0069] The other annealing conditions are a temperature holding
time of 0 to 20 hours, more preferably 6 to 10 hours, a cooling
rate of 50 to 500.degree. C./hour, more preferably 100 to
300.degree. C./hours, and an atmospheric gas of the annealing of
for example wet nitrogen gas.
[0070] Note that in the processing for removal of the binder, the
sintering, and the annealing process, it is for example possible to
use a wetter etc. to wet the nitrogen gas or mixed gas. The water
temperature in this case is preferably made 5 to 75.degree. C.
[0071] The processing for removing the binder, sintering, and
annealing may be performed consecutively or independently. When
performing these consecutively, preferably, after the processing
for removing the binder, the atmosphere is changed without cooling,
then the temperature is raised to the holding temperature for the
sintering, the sintering performed, then the chips are cooled, the
atmosphere is changed when the holding temperature of the annealing
is reached, and then annealing is performed.
[0072] On the other hand, when performing these independently, at
the time of sintering, preferably the temperature is raised to the
holding temperature at the time of the processing for removing the
binder in a nitrogen gas or wet nitrogen gas atmosphere, then the
atmosphere is changed and the temperature is further raised.
Preferably, the chips are cooled to the holding temperature of the
annealing, then the atmosphere changed again to a nitrogen gas or
wet nitrogen gas atmosphere and the cooling continued. Further, at
the time of annealing, the temperature may be raised to the holding
temperature in a nitrogen gas atmosphere, then the atmosphere
changed or the entire annealing process may be performed in a wet
nitrogen gas atmosphere.
[0073] The thus obtained sintered capacitors are for example end
polished by barrel polishing or sandblasting etc., then printed or
transferred with an external electrode paste and sintered to form
the external electrodes. The sintering conditions of the external
electrode paste are for example preferably 600 to 800.degree. C.
for 10 minutes to 1 hour or so in a wet mixed gas of nitrogen and
hydrogen. Further, in accordance with need, the surfaces of the
external electrodes may be formed with a covering layer by plating
etc.
[0074] A thus produced ceramic capacitor 1 of the present
embodiment is mounted by soldering on to a printed circuit board
for use for various types of electronic equipment.
[0075] Specific embodiments of the present invention will be given
below to explain the present invention in further detail. In the
following embodiments, the characteristics of the dielectric
composition of the present invention itself and the characteristics
of a stacked type ceramic capacitor having this as a dielectric
layer were evaluated.
[0076] Fabrication of Dielectric Composition
[0077] Powdered materials of a particle size of 0.1 to 1 .mu.m
comprised of barium titanate BaTiO.sub.3, strontium titanate
SrTiO.sub.3, calcium titanate CaTiO.sub.3, manganese oxide MnO,
silicon dioxide SiO.sub.2 vanadium oxide V.sub.2O.sub.5, and, in
accordance with need, rare earth oxides (at least one type of oxide
selected from Nb.sub.2O.sub.5, Ta.sub.2O.sub.5, Y.sub.2O.sub.3,
La.sub.2O.sub.3, CeO.sub.2, Gd.sub.2O.sub.3, Dy.sub.2O.sub.3, and
Ho.sub.2O.sub.3) were wet-mixed for 16 hours by a ball mill. The
result was then dried to obtain the dielectric material.
[0078] The matrix barium titanate BaTiO.sub.3, strontium titanate
SrTiO.sub.3, and calcium titanate CaTiO.sub.3 were prepared by
respectively weighing BaCO.sub.3, CaCO.sub.3, SrCO.sub.3, and
TiO.sub.2, wet-mixing them for 16 hours using a ball mill, drying
them, then sintering in air at a temperature of 1150.degree. C. and
wet pulverizing the result by a ball mill for 50 hours.
[0079] Note that the barium titanate BaTiO.sub.3, strontium
titanate SrTiO.sub.3, and calcium titanate CaTiO.sub.3 give similar
characteristics even when using materials prepared by
hydrothermally synthesized powder, the oxalate method, etc.
[0080] The samples used for measurement were obtained by adding
0.05 wt % of polyvinyl alcohol as a binder to the above dielectric
composition and mixing the binder and the dielectric composition to
form granules. Next, 0.3 g of the granular dielectric composition
was weighed and press formed to a disk of an outer diameter of 12
mm and a thickness of 0.5 mm.
[0081] The shaped article was processed to remove the binder under
conditions of a rate of temperature rise of 300.degree. C./hour, a
holding temperature of 800.degree. C., a holding time of 2 hours,
and an air and wet nitrogen gas atmosphere (1.times.10.sup.-5
atm).
[0082] Next, the shaped article was sintered under conditions of a
rate of temperature rise of 200.degree. C./hour, a holding
temperature of 1380.degree. C., a holding time of 2 hours, a
cooling rate of 300.degree. C./hour, and a mixed gas atmosphere of
wet nitrogen gas and hydrogen gas (1.times.10.sup.-9 atm) to obtain
a sintered body of an outer diameter of about 10 mm and a thickness
of 0.5 mm. Further, the sintered body was annealed under conditions
of a holding temperature of 900.degree. C., a holding time of 9
hours, a cooling rate of 300.degree. C./hour, and a wet nitrogen
gas atmosphere (1.times.10.sup.-5 atm). Note that the atmospheric
gases may be wet using a wetter and a water temperature of
35.degree. C.
[0083] In--Ga is coated on the two sides of the disk shaped
sintered body obtained in this way to form electrodes of .o
slashed.6 mm. This was used as the sample of the dielectric
composition (hereinafter also referred to as the "disk-shaped
sample") and was measured for ceramic characteristics, dielectric
constant, dielectric loss, and temperature-dependence of the
capacity.
[0084] Fabrication of Multilayer Ceramic Capacitor
[0085] In parallel with this, a multilayer ceramic capacitor was
fabricated.
[0086] First, for the dielectric layer paste, 100 wt % of various
dielectric materials, 4.8 wt % of acrylic resin, 40 wt % of
methylene chloride, 20 wt % of ethyl acetate, 6 wt % of mineral
spirits, and 4 wt % of acetone were mixed by a ball mill to make a
paste.
[0087] For the internal electrode paste, 100 wt % of nickel
particles of an average particle size of 0.2 to 0.8 .mu.m, 40 wt %
of an organic vehicle (8 wt % of ethyl cellulose resin dissolved in
92 wt % of butyl carbitol), and 10 wt % of butyl carbitol were
kneaded by a triple roll to form a paste.
[0088] For the external electrode paste, 100 wt % of copper
particles of an average particle size of 0.5 .mu.m, 35 wt % of an
organic vehicle (8 wt % of ethyl cellulose dissolved in 92 wt % of
butyl carbitol), and 7 wt % of butyl carbitol were kneaded to make
a paste.
[0089] Next, green sheets of thicknesses of 4.5 am and 15 .mu.m
were formed on PET films using the doctor brade casting method, the
internal electrode paste was printed on the sheets, then the green
sheets were peeled off from the PET films. Next, a plurality of
green sheets obtained in this way were stacked and pressed to
obtain a green chip. Four green sheets having internal electrodes
were stacked.
[0090] Next, the green chip was cut to a predetermined size and was
processed to remove the binder, sintered, and annealed to obtain
the stacked ceramic sintered body.
[0091] The processing for removing the binder was performed under
conditions of a rate of temperature rise of 15.degree. C./hour, a
holding temperature of 280.degree. C., a holding time of 8 hours,
and an air atmosphere. Further, the sintering was performed under
conditions of a rate of temperature rise of 200.degree. C./hour, a
holding temperature of 1380.degree. C., a holding time of 2 hours,
a cooling rate of 300.degree. C./hour, and a mixed gas atmosphere
(1.times.10.sup.-5 atm) of wet nitrogen gas and hydrogen gas. The
annealing was performed under conditions of a holding temperature
of 900.degree. C., a holding time of 9 hours, a cooling rate of
300.degree. C./hour, and a wet nitrogen gas atmosphere
(1.times.10.sup.-5 atm). Note that the atmospheres were wet using a
water and a water temperature of 35.degree. C.
[0092] Next, the end faces of the stacked ceramic sintered body
were polished by sandblasting, then external electrode paste was
transferred to the end faces and the assembly was sintered in a wet
nitrogen gas and hydrogen gas atmosphere at 800.degree. C. for 10
minutes to form external electrodes and obtain samples of stacked
ceramic capacitors (hereinafter also called capacitor samples). The
samples were of a size of 3.2 mm.times.1.6 mm.times.0.6 mm. The
thickness of the dielectric layer was 10 .mu.m and 3 .mu.m and the
thickness of the internal electrodes was 2.0 .mu.m.
[0093] The samples of the multilayer ceramic capacitors thus
obtained were measured for the temperature-dependence of the
capacity and tertiary harmonic distortion (THD).
[0094] Evaluation Items and Evaluation Methods
[0095] For the ceramic characteristics, the shrinkage during
sintering and the ceramic density were calculated from the
dimensions and mass of the disk-shaped samples obtained by forming
and sintering disk shapes. The sintering ability was evaluated from
the results.
[0096] Further, the disk-shaped samples were measured for the
electrostatic capacity and dielectric loss (tan .delta.) under the
conditions of 1 kHz and 1 Vrms using an LCR meter. The dielectric
constant was calculated from the obtained electrostatic capacity,
electrode dimensions, and thickness of the samples.
[0097] For the temperature-dependence of the capacitance, the
disk-shaped samples and capacitor samples were measured for the
electrostatic capacity at a voltage of 1V in the temperature range
of -30.degree. C. to +85.degree. C. using an LCR meter and it was
investigated if the ratio of change of the capacity when the
reference temperature was made 25.degree. C. was within .+-.15%
(Y5R characteristic of EIA standard of Electronic Industries
Association of Japan). Samples satisfying this were graded as
"good", while samples not satisfying this were graded as "poor".
Further, the representative sample 1 satisfying this Y5R
characteristic was measured for the rate of change of the capacity
in the temperature range of -30.degree. C. to +85.degree. C. The
results are shown in FIG. 6. A good temperature-dependence was
exhibited.
[0098] The tertiary harmonic distortion (THD) of capacitor samples
was measured in accordance with the procedure of the nonlinear
measurement method of a fixed resistor of the standard EIAJ RC2111.
For the measuring equipment, a CLT-1 made by RE TECNOLOGY AS was
used. All of the capacitor samples were measured for the tertiary
harmonic distortion when an AC voltage of 10 kHz was applied at a
field intensity of 0.3 V/.mu.F.
[0099] Ratios of Composition of Samples
[0100] The ratios of composition of calcium titanate (CT),
strontium titanate (ST), and barium titanate (BT) and the amounts
of the various additives added were changed as in Table 1 and Table
2 to fabricate the above disk-shaped samples and capacitor
samples.
[0101] Table 1 shows examples where the MnO, V.sub.2O.sub.5,
SiO.sub.2, and other additives were fixed (specifically, to 0.5 mol
% of MnO, 0.05 mol % of V.sub.2O.sub.5, and 0.2 mol % of SiO.sub.2)
and only the ratios of composition of the CT, ST, and BT were
changed. Sample 1 to sample 26 are examples of the present
invention, while sample 27 to sample 37 are comparative examples of
the present invention. The sample numbers corresponding to the
ratios of composition are shown in FIG. 5.
[0102] As opposed to this, Table 2 shows examples where the ratios
of composition of the CT, ST, and BT were fixed (specifically, 0.6
mol % of CT, 0.25 mol % of ST, and 0.15 mol % of BT) and the types
and amounts of the additives were changed. Sample 32 to sample 36
are examples of the present invention, while sample 37 to sample 41
are comparative examples of the present invention.
[0103] Further, to confirm the effectiveness of the sintering aid,
the ratios of composition of the G group of SiO.sub.2 and
Al.sub.2O.sub.3, the M group of BaO, CaO, and SrO, and the L group
of Li.sub.2O, Na.sub.2O, K.sub.2O.sub.3, and B.sub.2O.sub.3 were
changed as shown in Table 3 to prepare the above stacked capacitor
samples. Table 3 shows examples where the ratios of composition of
the CT, ST, and BT and the amounts of the additives other than the
sintering aid were fixed (specifically, 0.55 mol % of CT, 0.33 mol
% of ST, 0.12 mol % of BT, 0.5 mol % of MnO, and 0.05 mol % of
V.sub.2O.sub.5) and only the ratios of composition G, M, and L of
the sintering aid were changed. Sample 42 to sample 55 are examples
of the present invention, while sample 56 to sample 60 are
comparative examples of the present invention. @
3TABLE 1 Diel ectric THD Y5R- tan.delta. IR CT ST BT constant (dB)
(% -) (%) (.OMEGA. cm) Ex. Sample 1 0.55 0.3 0.15 384 -99 -15 0.03
3.88E + 1 2 Sample 2 0.55 0.33 0.12 400 -82 -14 0.12 4.50E + 1 2
Sample 3 0.63 0.25 0.12 356 -87 -14 0.08 6.50E + 1 2 Sample 4 0.8
0.07 0.12 340 -89 -13 0.12 6.66E + 1 5 5 2 Sample 5 0.77 0.07 0.15
302 -78 -14 0.07 6.25E + 1 5 5 2 Sample 6 0.72 0.12 0.15 331 -81
-13 0.13 6.55E + 1 5 5 2 Sample 7 0.7 0.12 0.17 382 -80 -13 0.17
8.38E + 1 5 5 2 Sample 8 0.61 0.22 0.16 405 -80 -13 0.15 6.73E + 1
5 5 2 Sample 9 0.67 0.17 0.16 365 -81 -11 0.13 67.3E + 1 2 Sample
10 0.7 0.17 0.12 307 -92 -14 0.06 1.04E + 1 5 5 2 Sample 11 0.75
0.12 0.12 302 -94 -12 0.07 7.43E + 1 5 5 2 Sample 12 0.52 0.30 0.17
403 -70 -13 0.18 8.80E + 1 5 5 2 Sample 13 0.57 0.25 0.17 400 -75
-14 0.20 1.29E + 1 5 5 2 Sample 14 0.62 0.2 0.17 421 -72 -14 0.17
1.40E + 1 5 5 2 Sample 15 0.65 0.15 0.2 453 -67 -12 0.23 8.03E + 1
2 Sample 16 0.7 0.1 0.2 463 -63 -10 0.25 7.45E + 1 2 Sample 17 0.72
0.1 0.17 384 -73 -14 0.16 6.56E + 1 5 5 Sample 18 0.77 0.05 0.18
360 -71 -12 0.11 4.56E + 1 2 Sample 19 0.53 0.37 0.12 298 -98 -14
0.07 4.55E + 1 2 Sample 20 0.6 0.3 0.1 255 -99 -13 0.09 5.30E + 1 2
Sample 21 0.7 0.2 0.1 260 -101 -14 0.08 6.20E + 1 2 Sample 22 0.85
0.05 0.1 250 -110 -14 0.09 6.40E + 1 2 Sample 23 0.6 0.2 0.2 291
-76 -12 0.13 6.45E + 1 2 Sample 24 0.9 0.05 0.05 180 -100 -13 0.34
4.50E + 1 2 Sample 25 0.7 0.25 0.05 200 -105 -13 0.52 3.20E + 1 2
Sample 26 0.45 0.45 0.1 350 -110 -15 0.64 3.05E + 1 2 Cmp Sample 27
0.52 0.25 0.23 529 -61 -5 0.26 6.80E + 1 Ex. 2 Sample 28 0.54 0.2
0.26 504 -56 +3 0.32 7.40E + 1 2 Sample 29 0.58 0.15 0.27 561 -56
+7 0.34 8.20E + 1 2 Sample 30 0.35 0.45 0.2 462 -70 -21 0.40 8.10E
+ 1 2 Sample 31 0.7 0.05 0.25 400 -58 +6 2.80 3.15E + 1 2 Samples 1
to 31 contain, as additives, 0.5 mol % of MnO, 0.05 mol % of
V.sub.2O.sub.5, and 0.2 mol % of SiO.sub.2.
[0104]
4TABLE 2 Diel ectric THD Y5R tan.delta. IR MnO V.sub.2O.sub.5
SiO.sub.2 constant (dB) (%) (%) (.OMEGA. cm) Ex. Sample 32 0.1 0.05
0.2 341 -82 -15 0.13 7.74E + 1 2 Sample 33 1 0.05 0.2 355 -81 -15
1.83 3.76E + 1 1 Sample 34 0.5 0.05 0.2 344 -81 -15 0.14 8.56E + 1
2 Sample 35 0.5 0.05 1 390 -93 -15 0.03 1.12E + 1 3 Sample 36 0.5
0.2 0.2 362 -81 -14 0.20 4.20E + 1 2 Cmp Sample 37 2 0.05 0.2 361
-78 -14 2.24 8.89E + 1 Ex. 0 Sample 38 0.5 0.05 0.1 311 -71 -17
1.12 4.95E + 1 0 Sample 39 0.5 0.05 2 422 -98 -17 2.24 5.92E + 1 0
Sample 40 0.5 0.01 0.2 312 -73 -12 1.34 1.29E + 1 0 Sample 41 0.5
0.3 0.2 382 -78 -13 0.34 3.42E + 1 0 Samples 32 to 41 all are
comprised of 0.6 mol % of CT, 0.25 mol % of ST, and 0.15 mol % of
BT.
[0105]
5TABLE 3 Insulation Glass Firing Diel- breakage G Group M group L
group component temp ectric THD Y5R tan.delta. IR voltage SiO.sub.2
Al.sub.2O.sub.3 CaO SrO BaO Li.sub.2O B.sub.2O.sub.3 (mol %)
(.degree. C.) constant (dB) (%) (%) (.OMEGA. cm) (V) Ex. Sample 42
0 0 0 0 0 1 0 0.5 1200 420 -82 -- 0.12 6.80E + 1 684 14.8 2 Sample
43 0 0 0.2 0.16 0.0 0.5 0 0.5 1280 410 -79 -- 0.18 3.20E + 1 480 8
5 6 13.2 2 Sample 44 0.1 0 0.3 0.21 0.0 0.25 0 0.5 1280 403 -80 --
0.15 3.30E + 1 475 6 5 8 13.3 2 Sample 45 0.5 0 0 0 0 0.5 0 0.5
1200 405 -81 -- 0.16 6.60E + 1 587 14.3 2 Sample 46 0.65 0 0.0 0.03
0.0 0.25 0 0.5 1280 389 -78 -- 0.19 4.10E + 1 490 6 3 1 14.0 2
Sample 47 0 0 0.1 0.06 0.0 0.8 0 0.5 1200 400 -81 -- 0.13 6.90E + 1
691 1 6 2 14.1 2 Sample 48 0.2 0 0 0 0 0.8 0 0.5 1200 411 -80 --
0.15 6.80E + 1 652 14.0 2 Sample 49 0.4 0 0.1 0.06 0.0 0.4 0 0.5
1220 409 -80 -- 0.15 4.80E + 1 659 1 6 2 14.6 2 Sample 50 0.3 0 0.1
0.09 0.0 0.4 0 0.5 1220 408 -81 -- 0.14 5.60E + 1 655 7 9 4 14.2 2
Sample 51 0.2 0 0.1 0.09 0.0 0.5 0 0.5 1220 400 -80 -- 0.13 6.10E +
1 638 7 9 4 15.4 2 Sample 52 0.3 0 0.2 0.14 0.0 0.3 0 0.5 1220 393
-80 -- 0.13 4.70E + 1 615 2 9 5 14.2 2 Sample 53 0.3 0 0.2 0.14 0.0
0.25 0 0.5 1280 370 -79 -- 0.20 4.40E + 1 555 5 9 5 13.5 2 Sample
54 0 0.05 0.0 0.03 0.0 0.85 0 0.5 1200 400 -79 -- 0.19 4.10E + 1
505 6 3 1 14.0 2 Sample 55 0.3 0 0.1 0.09 0.0 0 0.4 0.5 1200 403
-81 -- 0.18 5.50E + 1 531 7 9 4 14.3 2 Cmp Sample 56 0.8 0 0.0 0.33
0.0 0.1 0 0.5 1280 -- -- -- -- -- -- Ex. 6 1 Sample 57 0.4 0 0.3
0.18 0.0 0.05 0 0.5 1280 -- -- -- -- -- -- 2 7 Sample 58 0.1 0 0.4
0.26 0.1 0.1 0 0.5 1280 -- -- -- -- -- -- 4 4 Sample 59 0.05 0 0 0
0 0 0 0.05 1280 -- -- -- -- -- -- Sample 60 0.05 0 0 0 0 0 0 0.05
1340 410 -80 -- 0.22 3.50E + 1 489 13.6 2 Samples 42 to 60 are all
comprised of 0.55 mol % of CT, 0.33 mol % of ST, 0.12 mol % of BT,
0.5 mol % of MnO, and 0.05 mol % of V.sub.2O.sub.5. The values of
the G group, M group, and L group are the molar ratio of
composition of the glass component (G + M + L = 1). Samples 56 to
59 were not able to give dense sintered bodies.
[0106] Considerations
[0107] (1) The above results are shown in Table 1 to Table 3. In
the table, in the figures for the insulation resistance IR, "mE+n"
means "m.times.10.sup.+n". Note that regarding the results of
evaluation of the fireability, while not shown in these tables, in
the results of Table 1 and Table 2, there was no problem at all for
the samples other than sample 38. For sample 38, however, since the
amount of SiO.sub.2 added was small, the sintering ability was poor
and the strength insufficient.
[0108] From the results of Table 1, first, the balance of the
dielectric constant, distortion factor, and temperature-dependence
of the capacity was best in sample 1 to sample 11. After these,
sample 12 to sample 18 had a somewhat larger tertiary harmonic
distortion THD compared with sample 1 to sample 11, but were
extremely good in other characteristics. Further, sample 19 to
sample 22 were somewhat lower in dielectric constant compared with
sample 1 to sample 11, but were extremely good in other
characteristics.
[0109] As opposed to this, sample 27 to sample 29 of the
comparative examples have large dielectric constants, but the
tertiary harmonic distortion THD remarkably deteriorates. Further,
sample 30 does not satisfy the temperature-dependence of the
capacity Y5R, while the sample 31 has a remarkably large dielectric
loss tans.
[0110] Further, the following can be understood about the additives
from the results of Table 2. First, from a comparison of samples 32
and 33 and sample 37, it is learned that if the amount of MnO added
is too great, both of the dielectric loss tan .delta. and
insulation resistance IR deteriorate.
[0111] Further, from a comparison of samples 34 and 35 and samples
38 and 39, it is learned that both if the amount of SiO.sub.2 added
is increased or decreased, both of the dielectric loss tan .delta.
and insulation resistance IR deteriorate.
[0112] Further, from a comparison of samples 35 and 36 and samples
40 and 41, it is learned that if the amount of V.sub.2O.sub.5 added
is reduced, both of the dielectric loss tan .delta. and insulation
resistance IR deteriorate.
[0113] Note that CrO was added instead of MnO or Al.sub.2O.sub.3
was added instead of SiO.sub.2 and the results evaluated under the
same conditions as the above, but the same results were obtained in
both cases. Further, MoO.sub.3, WO.sub.3, and Co.sub.3O.sub.4 were
added respectively instead of V.sub.2O.sub.5 or mNb.sub.2O.sub.5,
Ta.sub.2O.sub.5, Y.sub.2O.sub.3, La.sub.2O.sub.3, CeO.sub.2,
Gd.sub.2O.sub.3, Dy.sub.2O.sub.3, and Ho.sub.2O.sub.3 were added as
other additives and the results evaluated under the same conditions
as the above, but the same results were obtained in all cases.
[0114] (2) Further, regarding the results of Table 3, in the
triangular diagram shown in FIG. 7, the samples in the area
surrounded by the samples 42, 47, 43, 44, 53, 46, 45, and 48, more
preferably, the area surrounded by the samples 42, 47, 52, 49, 45,
and 48, are good in all characteristics. Note that the samples 56
to 59 of the comparative examples could not give dense sintered
bodies even if sintered.
[0115] Note that the examples explained above were given for
facilitating the understanding of the present invention and were
not given for limiting the present invention. Therefore, the
elements disclosed in the above examples include all design
modifications and equivalents belonging to the technical scope of
the present invention.
* * * * *