JPS63166105A - Dielectric ceramic composition - 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 Field of Industrial Application The present invention relates to a temperature-compensating dielectric ceramic composition that can be fired at a temperature of 1150° C. or lower.

Conventional technology Temperature compensation materials used in ceramic capacitors include MgO-CaO-TiO2-based materials (for example, Japanese Patent Application Laid-Open No. 48-86097), La203-TiO2, etc.
2-based materials (for example, Japanese Patent Application Laid-Open No. 51-30400) have been used, but since the firing temperature of these materials is as high as 1250 to 1400°C, when used in multilayer ceramic capacitors, internal Expensive platinum or palladium electrodes are required.

On the other hand, among high dielectric constant materials, it has recently been discovered that composite perovskite materials mainly composed of PbO exhibit low firing temperatures of around 1000°C and excellent dielectric properties.
Since cheaper silver thread electrodes can be used as electrodes, many compositions have been proposed.
PbTi0 a − disclosed in Publication No. 21857
In the Pb(Mgxz2W1,2)03 system, the firing temperature is 1
It is a material with a high dielectric constant at around 000°C.

Problems to be Solved by the Invention Conventionally used temperature-compensating ceramic capacitor materials require expensive electrodes due to the high firing temperature. There is a strong need for dielectric materials that can be fired. Composite perovskite materials mainly composed of PbO have a large temperature change in dielectric constant, and there are no known materials that can be used in temperature compensation capacitors.

In view of the current situation, an object of the present invention is to provide a dielectric ceramic composition having a low firing temperature and a small rate of temperature change.

Means for Solving the Problem Part of Pb in the solid solution represented by PbTi, (Mgxt2W1za)yOC1 is replaced with Ca.

Action P'bTil-V (Mgt, 2Wl/11), OC
By partially replacing Pb in No. 1 with Ca, characteristics for temperature compensation can be obtained without impairing low-temperature sinterability.

Examples As starting materials, chemically high purity PbO, CaCo3
, TiO2, MgO, and WO3 were used. After correcting the purity of these, a predetermined amount was weighed and mixed in a ball mill for 17 hours using agate cobblestones and pure water as a solvent. This is suction filtered to remove most of the moisture, dried, and then thoroughly crushed using a Raikai machine.
It was soaked in t% moisture and molded into a cylinder with a diameter of 60 m and a height of about 50 m at a molding pressure of 500 kg/cd. Place this in an aluminum crucible, cover with the same quality lid, and heat to 750℃~
It was calcined at 880°C for 2 hours. Next, the calcined product was roughly crushed in an alumina mortar, and further crushed in a ball mill using agate cobblestones and pure water as a solvent for 17 hours, filtered with suction to remove most of the moisture, and then dried. After repeating the above steps of calcination, crushing, and drying several times, this powder was mixed with polyvinyl alcohol 6
A wt% aqueous solution was added at 6 wt% of the powder amount, and the mixture was granulated through a 32-mesh sieve, and molded into a cylindrical shape with a diameter of 13 m and a height of about 5 m at a molding pressure of 1000 +r/cj. The molded product was heated to 700°C in the air and held for 1 hour to burn out the polyvinyl alcohol, and after cooling, it was transferred to a Magnesia porcelain container, covered with a similar lid, and heated to a specified temperature in the air for 400°C. The temperature was raised at a rate of 400° C./hr, held for 2 hours, and then lowered at a rate of 400° C./hr.

The fired product was cut into a disk shape with a thickness of lllll11, and both sides were coated with C.
r-Au was evaporated and the dielectric constant and Q were set to I MHz, IV/
Measurements were made under an electric field of ms. Also, the resistivity is 1kV at 20℃
The voltage of /1llI was determined from the value 1 minute after application.

The firing temperature was determined to be the temperature at which the density of the fired product was as high as possible.

Table 1 shows the composition range of the present invention, peripheral composition components, firing temperature, dielectric constant, temperature change rate of Q% dielectric constant, and resistivity.

(Leaving space below) Table 1: Comparative examples outside the scope of the invention Compositions outside the scope of the invention are samples marked with an asterisk (*) in No. of Table 1, and the cat is 0.6. If the temperature exceeds 1,150℃, the optimum firing temperature will exceed 1150℃, if the temperature is 0℃ or less, the rate of change in dielectric constant will be 3000ppm/'C or more, or if the Ti amount is 0.6 or less, Q will be 1000 or less. have.

Effects of the Invention According to the dielectric ceramic composition of the present invention, characteristics such as a temperature change rate of dielectric constant of 3000 ppm/°C or less and a Q of 1000 or more can be obtained, and furthermore, since it can be fired at a temperature of 1150°C or less, it can be used for multilayer capacitors. It is possible to use Ag-Pd-based materials as the internal electrodes of the element, and an inexpensive multilayer capacitor can be realized, which is of great industrial value.

Claims (1)

[Claims] (PbCa)TiO_3 and (PbCa)(Mg_1
_/_2W_1_/_2)O_3, Pb_1_-_xCa_xTi_1_-_y(Mg_
When expressed as 1_/_2W_1_/_2)_yO_3,
A dielectric ceramic composition characterized in that x and y are in the range of 0.4≦x≦0.6 and 0.2≦y≦0.5, respectively.