JPS58125665A - Manufacture of high-dielectric constant porcelain dielectric - 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 The present invention provides a method for manufacturing a high-permittivity ceramic dielectric material having a high dielectric constant, a small change in dielectric constant with respect to temperature, and good AC voltage characteristics.

Conventionally, porcelain containing barium titanate as a main component has been used as a porcelain dielectric material with a high dielectric constant.
The higher the dielectric constant, the greater the change in dielectric constant with temperature.
When the dielectric constant was 4000 or more (at 25°C), the rate of change was a factor of 60 or more (at 25°C to 85°C). Furthermore, if the temperature change is relatively small, the dielectric constant will be less than 1600, making it impossible to obtain a sufficient capacity.

The present inventors have already reported BaT10. -C2LT103-Nb205-C02
We proposed a high permittivity ceramic dielectric composition based on the 03 (MnO2) - (Cub) component system, which has a high permittivity, a small temperature change rate of permittivity over a wide temperature range, and good AC voltage characteristics. It was revealed that the following characteristics can be obtained.

That is, barium titanate (BaTi03) 87.6
~96.1 weight, carunium titanate (CaTi03
) 1.6-9.7 Heavy-duty Section, Niobium Pentoxide (Nb20s)
The solid solution shown by the ratio of 1.9 to 3.7 is made into basic silk, and cobalt oxide (cobalt oxide (17%) is added to the main component as a subcomponent in kneading.
At least one of G(ho3)-manganese dioxide (MnO2) is added in a total amount of 0.3 to 0.5%, copper oxide (
This is a high permittivity ceramic dielectric composition containing CuO) added in a weight ratio of 0 to 0.6.

Here, BaTiO3, CaTiO3, Nb2O5, C
The range of each component of O203°CuO was limited as follows. If CaTiO3 is less than 1.6 parts by weight, the effect of improving AC voltage characteristics is weak, and the C
When aTi0 exceeds 97% by weight, the dielectric constant at room temperature decreases, the dielectric constant at high temperature (near 125° C.+1) also decreases, and the temperature characteristics of the dielectric constant deteriorate. If Nb2O5 is less than 1.9 parts by weight, the AC voltage characteristics deteriorate, and if Nb2O5 exceeds 3.7 parts by weight, the dielectric constant at room temperature decreases. Also, BaTiO31i
CaTiOs トNb205K YOP) 'c (D
Range f! 4hM is determined. Furthermore, CO2O3 is 0.3
If the amount is less than 1 part by weight, the dielectric constant is large on the low temperature side (around -66°C) and decreases on the high temperature side (around 126°C), resulting in poor temperature characteristics of the dielectric constant. When CO203 exceeds 0.5%, AC voltage characteristics deteriorate. However, the addition of CuO causes a slight decrease in the dielectric constant, but has the effect of improving AC voltage characteristics and improving the dielectric constant at high temperatures (125° C.). When GuO exceeds 0.5 fold ratio, the dielectric constant decreases significantly. Indeed, MnO2 has the same effect as CO2O3.

That is, BaTi within the composition range described in 1.
O3-CaTi03-Nb2o5-CO203(Mn0
2)=The dielectric constant is high for the first time due to the (Cuo) component system,
The capacitance temperature change rate is small over a wide temperature range, and good AC voltage characteristics are obtained. However, even with this, the AC voltage characteristics were still insufficient. In other words, the thickness of one layer of porcelain is several 1 opm, such as in multilayer capacitors.
As it becomes thinner, the electric field applied to the porcelain increases, so even if the applied AC voltage increases, the dielectric constant and dielectric loss (ta,
In order to prevent nδ) from becoming large, a porcelain dielectric with good AC voltage characteristics is desired4.
05-CO203Nb205-C0203 (In the composition system, the main component BaTiO3 is replaced with BaCO3 and Tl
It was discovered that by appropriately selecting the generation temperature when generating from O2, the AC voltage characteristics of the high permittivity porcelain dielectric material based on the above-mentioned components could be greatly improved. The fluctuation was large, and manufacturing problems remained.

The present invention aims to stabilize the characteristics of the ceramic dielectric by correcting the fluctuations in the characteristics of the ceramic dielectric due to the fluctuations in the BaTiO3 formation temperature by increasing or decreasing l of Nb2O5.

Hereinafter, the present invention will be described in detail based on specific examples.

First, high-purity B with a purity of 99.8% or more is used as a starting material.
Equal moles of aC03 and TiO2 were blended, mixed in a ball mill, dried, and baked on a powder board at a predetermined temperature for 2 hours.
aTiOx was produced. The generation temperature of BaTi03 at this time was very high at the set temperature of the electric furnace, and the temperature of the sample was measured at several points with a platinum-rhodium thermocouple. Next, the above BaTiO3, CaTiO3, Nb2O
5, 94.4% by weight, 2.8% by weight, respectively.
2.8 parts by weight and 0 CO203 for these main components.
．． 46% by weight, 0.2% by weight of cuo added,
After mixing in a ball mill and drying, 9 parts by weight of 5 parts by weight of PVA (polyvinyl alcohol) aqueous solution was added and granulated, and the mixture was molded into a disk with a diameter of 1.3m7ffi and a thickness of about 0.3mm at 11°C.
m/c? The resulting device was molded at a pressure of Then, the dielectric constant was determined from the capacitance. Also, the temperature change rate of the dielectric constant and AC voltage characteristics were determined. The measurement results are shown in the table below.

(Left below) In this case, the target formation temperature of BaTiOx is 114
00C (confirmed that it can actually be carried out at 1110 to 11600C), and the -4 diode generation temperature is 1100C.
The dielectric constant, dielectric loss, and temperature change rate of dielectric constant (-66 to +126°
C525°C standard), AC voltage characteristics (tan δ, atl
1]z, 50vshio m) for each sample m1 in the above table.
．． It is shown in m4. In this way, when the formation temperature of BaTj-03 deviates from the target value, the dielectric characteristics change,
This is a manufacturing problem. Therefore, if the formation temperature of BaTi03 is too low at 1100°C, if Nb2O5 is added a little more than 17% from the normal amount during compounding, and if BaTiO3 is
When the formation temperature of No. 3 was too high at 1170°C, the results when Nb2O5 was added 26 times more than the normal amount during compounding are shown in Sample No. 2 and No. 2 in the -J table, respectively. No. 5 is shown. At this time, the it characteristics of sample No.
The characteristics shown in No. 3 are close to those obtained when the BaTiO3 formation temperature is 1140°C.

In this way, if the formation temperature of BaTi03 is too low, N
By reducing the blending amount of b2O5 by an appropriate amount from the normal blending amount, and conversely, if the BzTiOs formation temperature is too high, by increasing the blending amount of Nb2O5 by an appropriate amount, the deviation in dielectric properties due to the deviation in BaTiO3 formation temperature can be corrected. can. However, due to the increase/decrease in the total amount of Nb2O5 needed to correct the deviation in characteristics, the blended amount of Nb2O5 ended up being as high as 1 or 9 as described above.
Of course, if the content is outside the range of 3.7% by weight, the properties are unfavorable.

According to the production method of the present invention, BaTi03 is produced from BIGO3 and TiO2 at a predetermined production temperature, and this BaT
BaTiO3-CaTiO3-Nb2O using i03
In 5-CO20v (MnO2) -(Cub) based high permittivity ceramic dielectrics, fluctuations in characteristics due to deviations in BaTiO3 formation temperature from a predetermined temperature can be easily corrected by increasing or decreasing the amount of Nb2O5. , which is suitable for mass production.

Claims (1)

[Claims] BaTiO3 is produced from equimolar numbers of BaCO3 and TlO2 at a predetermined production temperature, and using this BaTi03, B
zTiOx 8%, 6-96.1% by weight, CaT
iO31,5~9.7 weight ratio, Nb2O51,9~3
．． 7 The basic composition is a solid solution shown by the weight ratio, and this 11 contains CO20x and MnO2 as subcomponents relative to the main component.
The total amount of at least one of the following is 0.3 to 0.5 weight i7
t%, cuo by weight of O-0.5, and the fluctuation of the characteristics due to the deviation of the formation temperature of BaTiO3 from the predetermined temperature.
1. A method for producing a high permittivity ceramic dielectric material, which comprises making corrections by increasing or decreasing the amount of .