JPS6283365A - 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 high dielectric constant dielectric ceramic composition which is fired at a firing temperature of 1100° C. or less, and particularly relates to one in which the change in dielectric constant per grade is small.

Conventional technology In recent years, ceramic capacitors have become smaller and smaller.
Due to the demand for larger capacity! PtPt top ceramic capacitors are becoming increasingly popular. Multilayer ceramic capacitors are typically manufactured by a process of integrally firing internal electrodes and ceramics. Barium titanate-based materials have traditionally been used as high-permittivity ceramic capacitor materials, but because the firing temperature is as high as 1,300°C, it is necessary to use expensive metals such as PiXPd as internal electrode materials. there were.

On the other hand, a lead composite perovskite material has been developed that can be fired at 1100° C. or lower and can use a cheaper Ag-based material as the internal electrode. For example, PbZr
Among those containing O3 as a main component, JP-A-55-2
The material described in Japanese Patent No. 1850 is known.

Problems to be Solved by the Invention Materials containing PbZr03 as the main component include a dense sintered body of 110% to obtain high reliability as a multilayer capacitor element.
Although some can be obtained at a firing temperature of 0'C or lower, PbZ
The Curie point of rO3 is at 220°C, and the dielectric constant at 20°C is as small as 200 or less.

An object of the present invention is to provide a dielectric porcelain composition that has a low porcelain firing temperature, has a Curie point near room temperature, and exhibits a high dielectric constant at room temperature.

Means for solving the problem Pb (Znt, 2V
i'l, 2) The composition is such that 03 is added.

Effect Pb (Znxt2Wl/2) 03 as PbZrO3
By adding 1::, it is possible to obtain a dense sintered body that can provide high reliability as a multilayer capacitor element at a firing temperature of 1100°C or less, and has a large dielectric constant at room temperature, making it suitable for use in multilayer capacitor elements. In this case, an Ag-based material can be used for the internal electrodes, and a large-capacity device can be obtained.

Examples Starting materials include chemically highly pure PbO1ZrO2, Zn
O,WOs were used. After correcting the purity of these, a predetermined amount was weighed, and mixed using an agate cobblestone and pure water as a solvent in a ball mill for 17 hours. This is filtered by suction to remove most of the water, dried, and then thoroughly crushed in a Raikai machine. After adding 5wt% of water to the powder, it is shaped into a cylinder with a diameter of 60mm and a height of about 50mm. pressure 500k
Molded with g/c+++2. This was placed in an alumina crucible, covered with a homogeneous lid, and calcined at 750°C to 810°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 under suction to remove most of the moisture, and then dried. After repeating the above calcining, crushing, and drying several times,
A 6 wt % aqueous solution of polyvinyl alcohol was added to this powder in an amount of 6 wt % based on the powder amount, and the mixture was granulated through a 32 mesh sieve and molded into a cylinder having a diameter of 13 M and a height of about 51 m 1 at a molding pressure of 1000 kg/cm 2 . The molded product is placed in the air at 7
By raising the temperature to 00℃ and holding it for 1 hour, the polyvinyl alcohol content is burnt out.After cooling, it is transferred to a Magnesia porcelain container, covered with a similar lid, and heated in air to a specified temperature at 400℃/hr. 400℃ after holding for 2 hours
The temperature decreased at /hr.

The fired product was cut into a disk shape with a thickness of 1 m, and both sides were coated with Cr-Au.
was deposited, and the dielectric constant and tan δ were measured at 1 kHz and under an electric field of IV/mm.

The firing temperature was determined to be the temperature at which the tone of the fired product was the highest.

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

(Left below) For compositions outside the scope of the invention, samples marked with * in Table 1 are listed as examples, but the optimum firing temperature is 1100°C.
The problem is that the dielectric constant becomes smaller and the temperature change rate of the dielectric constant increases.The composition within the scope of the invention overcomes all of the problems mentioned in @. has been done.

Effects of the Invention According to the present invention, it is possible to obtain a dense sintered body for obtaining high reliability as a multilayer capacitor element at a temperature of 1100° C. or lower, and it is possible to use Ag-based materials as internal electrodes. In addition, it is possible to obtain an excellent dielectric ceramic composition that has a high dielectric constant and a small rate of change in dielectric constant with temperature.

Claims (1)

[Claims] PbZrO_3, Pb(Zn_1_/_2W_1_/_
2) PbZr_x(Zn_1_/_2W_1_/_2)_y
When expressed as O_3 (however, x+y=1.00) 0
．． A dielectric ceramic composition characterized by having a composition within the range of 52≦x≦0.84.