JPS6226807A - Ceramic composition for reducing/reoxidizing type semiconductor ceramic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field 1) This invention relates to an improvement of a ceramic composition for a reduction-reoxidation type semiconductor ceramic capacitor, which is formed by forming an insulating layer on the outer periphery of a semiconductor ceramic by reoxidation.

[Prior Art] Reduction and reoxidation semiconductor capacitors using barium titanate-based or strontium titanate-based ceramic compositions have been known. Reduction-reoxidation semiconductor capacitors are obtained by firing a ceramic composition in a reducing atmosphere to make it a semiconductor, then reoxidizing the surface to form an insulating layer on the surface, and then adding electrodes for taking out the capacitance. It will be done.

In this case, as cue point chic, La, Ce, Nd
.

Rare earth elements such as 8111 are used.

For example, in barium titanate-based porcelain compositions, the particle size is 2.
~3 μl 1 g, as small as the bottom, and the dielectric constant ε2° is 12
000 or more, and thus a large capacity semiconductor capacitor has been realized.

[Problems to be Solved by the Invention] However, the barium titanate semiconductor ceramic capacitor described above has a problem in that the temperature characteristics of the obtained semiconductor capacitor vary greatly depending on the calcination temperature and sintering temperature. For example, when the sintering temperature is increased to increase density to improve breakdown voltage or insulation resistance, or when the calcination temperature is too low, the temperature change rate of the dielectric constant tends to fluctuate greatly. Ta. For example, there is a problem in that the dielectric constant ε8s at 85° C. does not exceed -80% of the dielectric constant ε2o at 20° C., making it impossible to obtain stable temperature characteristics.

Therefore, an object of the present invention is to make it possible to create a reduction-reoxidation semiconductor capacitor with stable temperature characteristics.
! The purpose is to provide a porcelain composition.

Means for Solving Problems] The ceramic composition of the present invention has (Ba + - %Ax) (Ti
I-7Zry), 0. are the main components, (where x, y
and turtle are numerical values selected from the following range, and △ is selected from at least one of La, Ce, Pr, Nd, Pl, Sya, and Eu: 0.01
≦X≦0.07, O≦y≦0.10.0.95≦−≦1
．． This is a ceramic composition for a reduction and reoxidation type semiconductor ceramic capacitor, in which 51o2@ is added in an amount of 0.05 to 5.0% by weight based on the main component.

As a result of various studies on the composition of barium titanate-based porcelain compositions, the inventors of the present application found that the above-mentioned main components have a content of 0.05 to 5.
It has been shown that by adding O, mFm% of SiO2, a semiconductor capacitor with stable temperature characteristics can be obtained (9).

In the above formula of the main components, △ represents rare earth elements such as La, Ce, Pr, Nd,
At least one of Pm, S1m, and El is selected, and these elements play the role υj of moving the cue point and setting it near room temperature. It also functions to make oxygen into a defective structure and facilitate the diffusion of oxygen. That is, it plays the role of facilitating reduction and reoxidation.

In addition to these elements, substitution with Ca or 3r is also considered. However, Ca does not move the cue point very much, and because it has the same valence as 3rG and tea, it does not contribute to oxygen vacancies for semiconductor formation, so substitution with these elements is difficult. is not desirable.

The reason why the E conversion amount of each element mentioned above was set to 0.01 to 0°07 is that if it is less than 0.01, it will not be very effective as a shifter to move the cue point, whereas if it exceeds 0.07, it will not be effective as a shifter. This is because the cue point continues to shift to the low temperature side and the dielectric constant decreases.

Also yfl, that is Zr! ! The reason why t is O ~ 0.10 is that while sufficient electrical characteristics can be obtained without replacing part of Ti with Zr, by replacing part of Ti with 2' up to 0.10. This is because the effect of improving the degree of sintering can be seen without impairing the electrical properties.In addition to replacing a portion of T1 with 7r, it is also possible to replace a portion of T1 with Sn″c. However, it is not preferable because it becomes metallized in the reduction step.

Furthermore, the amount of II is set to 0.95 to 1.05, because even if the molar ratio is changed within this range, sintered porcelain can be obtained without impairing the electrical properties.

S i O2 ratio 0, 05~5
The reason for setting Oiim% is that if it is less than 0.05 tffi%, the dielectric constant will fluctuate greatly depending on the firing temperature, and the effect of addition will not be sufficient.On the other hand, if it exceeds 5 wt%, not only will the dielectric constant decrease, This is because porcelain M-dish occurs and the yield decreases. Furthermore, as evidenced by the examples mentioned above, it can be seen that when the amount of 5iOz added is in the range of 0.05 to 5.0% by weight, the variation in the temperature change rate of the dielectric constant due to changes in the calcination temperature is small. .

Therefore, it can be seen that in this invention, 5i02 must be added in the above ratio.

[Description of Examples] A predetermined amount of barium carbonate and titanium oxide were weighed and mixed, and the resulting mixed powder was calcined for 2 hours at a temperature of 1050'C to 1200C, and then pulverized. For barium titanate obtained by pulverization, La2():+, Ce0z, P
rzOa, Nd2O5, pm20s N SIN 20
s, EIJ 20a and Zr○.

D Using each original family, ig1 to have the composition shown in Table 1.
Combined and mixed. At this time, as shown in Table 1, 0, 0.01, 0.05, 0.3, 5.0 or 6.0% by weight of 5iOz was mixed with the main component to prepare samples 1...63. I got it. Next, a binder was added to each sample and formed into a pellet shape.

The formed pellets were fired at various temperatures ranging from 1350°C to 1400°C for 2 hours, and then heat treated in a reducing atmosphere for 1 hour. Furthermore, after performing heat treatment in an air atmosphere, an AC+ electrode was applied and baked to produce a semiconductor ceramic capacitor.

Table 1 also shows the temperature change C (%) of the M electrical constant ε of the obtained semiconductor ceramic capacitor. In addition, T
C is dielectric constant (85℃)/dielectric constant (20℃)xloo(
TC values in Table 1, which are expressed as
Comparison with .

In addition, it can be seen that in samples 16 to 18, the dielectric constant ε (20° C.) becomes too low because the amount of s+02 added is large.

Furthermore, by comparing sample 19.20, which is a comparative example, and sample 21.22, which is an example, it was found that even when the calcination temperature was changed,
It can be seen that according to this invention, the variation in TC is considerably reduced.

Also, from the results of samples 23...27 when Zr02 was not added to adjust the torque ratio, 3i02 was similarly added to 0.
．． It can be seen that in Samples 24...26 in which 05 to 5.0% by weight was added, the fluctuations in TC were also small.

In addition, sample 30 had a large molar ratio on the Ti side and fusion of the porcelain was observed, so it was excluded from the scope of the invention. In sample 31, the e ratio on the Ti side is small, and the dielectric constant is. Since the sinterability deteriorates as the temperature decreases, it is excluded from the scope of the invention. Sample 32 is Ce
Sample 33 contained a large amount of Ce mtfi, and both had low M electric rates and were therefore outside the scope of the invention. Sample 34 has a large amount of Zrff1, and as the dielectric constant decreases and the sinterability deteriorates, it was excluded from the scope of the invention.

Roughly, as a rare earth element, instead of Ce, 1-a.

It can be seen that similar results are obtained for Samples 35...63 using Pr, Nd, Pm, Ss and EIJ.

In addition, in order to improve insulation resistance and sinterability, manganese oxide is added to the porcelain composition by 0.05 in terms of Mll 02.
It may be contained in an amount of up to 1 mol%.

(Margins below) [Effect of the invention] This invention has the following advantages: (f3a + -% Av) (
TI + −y Zr, ), 0. 0.05 to 5.0% by weight of sr 02 is added to the main component consisting of.

Therefore, it is possible to produce 1q of re-oxidized semiconductor ceramic capacitors whose temperature characteristics are subject to extremely small fluctuations due to fluctuations in calcination temperature, firing temperature, or loft.

Therefore, the yield can be improved in manufacturing semiconductor ceramic capacitors, and products of uniform quality can be stably produced.

It should be noted that even if 5102 is added within the composition range of the present invention, there is almost no effect on breakdown voltage, insulation resistance, and CVfa (capacity x breakdown voltage).

Claims (1)

[Claims] The main component is a material represented by the general formula shown below, (Ba_1_-_xA_x)(Ti_1_-_yZr_
y)_mO_3 However, 0.01≦x≦0.07 0≦y≦0.10 0.95≦m≦1.05 A is at least one of La, Ce, Pr, Nd, Pm, Sm, and Eu 0.05 to 5.0% by weight of SiO_ with respect to the main component
A ceramic composition for a reduction and reoxidation type semiconductor ceramic capacitor, which is made by adding 2.