JPS63170804A - Manufacture of non-reducing dielectric ceramic - 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) The present invention relates to a method for manufacturing non-reducible dielectric ceramics, and particularly relates to a method for manufacturing non-reducible dielectric ceramics used as dielectric materials such as multilayer capacitors. .

(Prior art) Conventionally, when manufacturing a multilayer capacitor, a plurality of dielectric green sheets, each of which has a metal powder layer that will become an internal electrode by printing on its top surface, are stacked, crimped, and integrated. , a process of firing the integrated product is adopted.

(Problems to be Solved by the Invention) Conventional dielectric ceramics have the property that when fired under low oxygen partial pressure, they are reduced and their specific resistance deteriorates significantly. For this reason, the firing is performed under high oxygen partial pressure such as in air.
For example, it was carried out at a high temperature of 1,300°C or higher.

Therefore, noble metals such as palladium and platinum must be used as materials for the internal electrodes that can withstand such heat treatment conditions, which is a major hindrance to increasing the capacity and lowering the price of manufactured multilayer capacitors. was.

Therefore, in order to solve the above-mentioned problem, the present inventors
For example, we created dielectric porcelain that does not reduce even when fired under low oxygen partial pressure and has a high specific resistance so that base metals such as nickel can be used as materials for internal electrodes. This dielectric ceramic is disclosed in Japanese Patent Publication No. 56-46641 and Japanese Patent Application Laid-open No. 61-19005.

However, in the dielectric porcelain manufactured by the manufacturing method disclosed in these publications, the porcelain composition forms a uniform solid solution during the sintering process, so the Curie point is single, and therefore the dielectric The rate of change in temperature was large.

As a result of diligent efforts, the inventors of the present invention have discovered that the rate of temperature change in dielectric constant can be reduced by not completely dissolving ZrO□, CaO, etc. in BaTiO3 during the sintering process.

Therefore, the main object of the present invention is to exhibit a high resistivity without being reduced and turned into a semiconductor even when fired in a non-oxidizing atmosphere, and to have a high dielectric constant, and also to It is an object of the present invention to provide a method for manufacturing non-reducible dielectric ceramics that can manufacture non-reducible dielectric ceramics with a small rate of change.

(Means for Solving the Problems) The present invention provides calcined and pulverized BaTiQ,
, CaTiOs and CaZrOs, BaTi0.
is 82.0 to 93.0 mol%, CaTi0. is 6.0~
14.0 mol%, and 1.0 to 8.0 CaZrO3
M
n0z+ Converted to MgO and Sin, MnO,
was added in the range of 0.1 to 4.0 mol parts, MgO was added in the range of 0.62 to 4.0 mol parts, and Sin was added in the range of 0.1 to 3.0 mol parts, and further, subcomponents were added to the main component. This is a method for producing non-reducible dielectric porcelain by firing something.

(Effect of the invention) According to the invention, for example, 1, 2
Even when fired at a temperature of 70 to 1,360°C, it does not reduce and turn into a semiconductor, exhibiting a high specific resistance of 10"Ω or more, and a high dielectric constant of 3,000 or more, and -55
It is possible to produce a non-reducible dielectric ceramic whose temperature change rate of dielectric constant is as small as 115% to +15% over a wide temperature range of 125°C to 125°C.

Further, according to the embodiment of the present invention, the dielectric loss is as small as less than 1.00%, and the dielectric constant in the temperature range of -25°C to +85°C is based on the dielectric constant at +20°C. Excellent characteristics were obtained with a small temperature change rate of less than ±10%.

Therefore, it is possible to produce a non-reducible dielectric ceramic that satisfies all of high permittivity, low dielectric loss, and good permittivity-temperature characteristics, and is extremely useful as a dielectric material for small, large-capacity capacitors. . Moreover, if this non-reducible dielectric ceramic is used as a dielectric material for a multilayer ceramic capacitor, for example, an inexpensive multilayer ceramic capacitor can be obtained in which internal electrodes are made of a base metal such as nickel.

The above objects, other objects, features and advantages of the present invention will become more apparent from the detailed description of the following embodiments.

(Example) First, BaC0 and TiO2 were weighed in a ratio to form BaTiOs, and they were thoroughly mixed in a ball mill. After calcining this mixture at 1200°C for 1 hour, it was finely pulverized. .

Similarly, CaTiOs powder calcined and pulverized from CaC0+ and TiO□ and CaZrOs powder calcined and pulverized from CaC01 and ZrOz were obtained, respectively.

The X-ray diffraction images of these powders confirmed that these powders had uniform crystallinity.

The BaTi0. , CaTiO3
and CaZrO3 powder, and Mn01. MgO and Sing were weighed so as to obtain a dielectric having the composition ratio shown in Attached Table 1. In Table 1, numerical values of composition ratios outside the scope of the present invention are underlined.

Furthermore, 5% by weight of a vinyl acetate organic binder was added to this weighed raw material, wet mixed, and then evaporated.

A powder was obtained through drying and sizing steps. This powder was then heated to a diameter of 10 fi at a pressure of 2000 kg/aa.

A molded product was obtained by molding to a thickness of 1 fl.

This molded product was placed in an alumina box with zirconia powder as a bed powder, and heated at 1°270°C to 1.400°C in a reducing gas atmosphere with a volume ratio of Hz/Nt of 3/100.
An element was obtained by firing at a temperature of .degree.

In--Ga alloy was applied to both surfaces of the obtained element to form electrodes, and each sample was obtained.

Then, the dielectric constant ε and dielectric loss tan δ of each sample.

The electrical characteristics of the temperature change rate of dielectric constant and specific resistance were measured under the following conditions.

The dielectric constant ε and the dielectric loss tan δ were measured at a frequency of 1 kHz and a temperature of 25°C.

The temperature change rate of the dielectric constant is the temperature change rate of the dielectric constant (ΔC/Czs) in the temperature range of -55℃ to +125℃ based on the dielectric constant at a temperature of +25℃, and the dielectric constant at a temperature of +20℃. The temperature change rate (ΔC/C, .) of the dielectric constant in the temperature range of −25° C. to +85° C. as a reference was measured.

The specific resistance is DC, 500V at 25°C.
Measurements were taken after applying the voltage for a minute.

The above measurement results are shown in Attached Table 2. In Table 2, numerical values with poor characteristics are underlined. In this case, the dielectric constant ε is less than 3.000, and the temperature change rate of the dielectric constant (
Δc/czs) is outside the range of -15 to +15%, temperature change rate of dielectric constant (ΔC/C,.) is outside the range of -10 to +10%, and resistivity is 10%. ``Those below Ω·C11 were shown as having poor characteristics.

In other words, as in sample number 4, BaTtO is 82 mol%
If the dielectric constant is less than
If TiOs exceeds 93 mol %, the temperature characteristics of the dielectric constant deteriorate.

In addition, when CaTiO3 is less than 6 mol% as in sample numbers 1 and 6, the temperature change rate of dielectric constant exceeds 115%, and as in sample number 3, when CaTiO3 is less than 6 mol%, as in sample number 3, CaTiO3 is less than 6 mol%. If it exceeds 14 mol%, the dielectric constant becomes small.

When CaZrO1 is less than 1 mol% as in Sample No. 2, the temperature change rate of the dielectric constant exceeds 115%, and when CaZrO3 exceeds 8 mol% as in Sample No. 5, the dielectric constant becomes small.

On the other hand, if MnO is less than 0.1 mol part as in sample number 15, the temperature characteristics of the dielectric constant deteriorate;
When Mn0z exceeds 4 molar parts, the dielectric constant decreases.

In addition, when MgO is less than 0.2 mol part as in sample number 19, the specific resistance decreases due to reduction firing, and the temperature change rate of dielectric constant increases (as in sample number 22, MgO
When gO exceeds 4 parts by mole, the dielectric constant becomes small and sinterability deteriorates.

When Sing is less than 0.1 molar part as in sample number 23, the sinterability decreases, the dielectric constant decreases, and the temperature change rate of the dielectric constant increases, and as in sample number 26, 5 int becomes 3 If it exceeds the molar part, the dielectric constant becomes small and the rate of change of the dielectric constant with temperature becomes large.

Moreover, as disclosed in Japanese Patent Application Laid-Open No. 61-19005 as a reference example, BaTi0. , CaTi0. and CaZrO3 without going through each component ((
Ba, Ca, Mg)O) m ・(Ti+ Zr
) The composition of the solid solution consisting of Oz, its dielectric constant, dielectric loss, temperature change rate of dielectric constant, and specific resistance are shown as sample number 28 in Attached Tables 1 and 2, respectively. The composition and electrical characteristics of an example of the present invention corresponding to sample number 28 are shown as sample number 27 in Attached Tables 1 and 2.

As is clear from comparing the results of sample numbers 27 and 28, sample number 28 is a single solid solution and has a high dielectric constant, but it has a single Curie point, so it has the disadvantage that the rate of change in dielectric constant with temperature is large. However, on the other hand, it can be seen that sample number 27 within the scope of the present invention exhibits a high dielectric constant and a flat temperature change rate of the dielectric constant.

Furthermore, as is clear from Attached Table 2, according to the present invention,
The dielectric constant is 3.000 or more, the dielectric loss is less than 1.00%, and the temperature change rate of the dielectric constant in the temperature range of -55℃ to +125℃ based on the dielectric constant at +25℃ is ± 15%, and the temperature change rate of the dielectric constant in the temperature range of -25°C to +85°C is less than ±10% based on the dielectric constant at +20°C. I understand.

Patent applicant Murata Manufacturing Co., Ltd. Agent: Patent Attorney Oka 1) Zenhiro (1 idiot)

Claims (1)

[Claims] BaTiO_3 and CaTi each calcined and pulverized
O_3 and CaZrO_3, BaTiO_3 is 82.0 to 93.0 mol%, CaTi
O_3 is 6.0 to 14.0 mol%, and CaZrO_
3 was blended in a range of 1.0 to 8.0 mol% as the main component, and to 100 mol parts of the main component, manganese oxide, magnesium oxide, and silicon dioxide were added as subcomponents, respectively. Mn
In terms of O_2, MgO and SiO_2, MnO_2 is added in the range of 0.1 to 4.0 mol parts, MgO is 0.2 to 4.0 mol parts, and SiO_2 is added in the range of 0.1 to 3.0 mol parts. A method for producing non-reducible dielectric porcelain, which further comprises firing a mixture of the main component and the subcomponent added thereto.