JPH0497502A - Electronic device - Google Patents

Abstract

PURPOSE:To provide an electronic device with a high breakdown voltage and improved reliability by carrying out heat treatment on the electronic device in the oxidizing atmosphere at a temperature below a baking temperature for semiconductor porcelain while by forming electrodes by sputtering. CONSTITUTION:After fabricating a low resistance barium titanate semiconductor porcelain raw body, heat treatment on an electronic device carried out in the oxidizing atmosphere at a temperature below a baking temperature for the semiconductor porcelain, and electrodes are formed by sputtering, thus obtaining a barium titanate semiconductor porcelain superior in less process variation and breakdown voltage characteristic. That is, the resistivity distribution inside the barium titanate semiconductor porcelain element is greatly uniformalized and a superior breakdown voltage characteristic can be obtained. Accordingly, an electronic device made of such barium titanate semiconductor porcelain has superior breakdown voltage characteristic and reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to electronic components, and particularly to electronic components using barium titanate-based semiconductor ceramics.

(Prior art) Conventionally, in order to form barium titanate-based semiconductor porcelain used in electronic components, a slurry is formed using a barium titanate-based semiconductor porcelain material, this slurry is passed through a filter, and the molding process is performed. There was a method of forming objects by firing them at a predetermined firing temperature. In this way, by passing the slurry through a filter, semiconductor porcelain with uniform crystal grain size can be produced.

An electronic component is formed by forming a Ni electrode on the obtained semiconductor ceramic by electroless plating and further applying an Ag electrode on the Ni electrode.

(Problems to be Solved by the Invention) However, when such barium titanate-based semiconductor porcelain was cut into small pieces and examined, as shown in Figure 2,
The resistivity distribution within the porcelain is non-uniform. Therefore, the withstand voltage characteristics deteriorate. Note that this resistivity distribution is expressed as a value obtained by dividing the individual resistivity values ρ by the average value Σρ=/n of all the resistance values, as shown in the following equation.

I wealth 1 X, = ρ, /(Σρ, /n) When an Ag[pole is provided on the electrode, the process change in resistance value becomes large and the voltage characteristics deteriorate.

Therefore, the main object of the present invention is to provide an electronic component with excellent withstand voltage characteristics and high reliability.

(Means for Solving the Problems) The present invention heat-treats semiconductor porcelain in an oxidizing atmosphere at a firing temperature of the semiconductor porcelain or a temperature lower than the firing temperature, and further, sputters Cr on the surface of the semiconductor porcelain. T1Ni, Aj! Or it is an electronic component with electrodes formed from these alloys.

(Function) By performing heat treatment in an oxidizing atmosphere at a temperature below the firing temperature of semiconductor porcelain, the resistivity distribution within the semiconductor element becomes uniform. Further, by forming the electrodes by sputtering, the process change in resistance value is reduced.

(Effects of the Invention) According to the present invention, an electronic component having excellent voltage resistance characteristics and high reliability can be obtained.

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

(Example) First, as a starting material, BaTie, which should be the main component,
, 5rTio, , CaTiOs, and PbTio, as well as semiconducting agents and additives to be added to them, were prepared. Then, the composition of the main component of the porcelain to be obtained is BaT
i0. 75 mol%, 5rTiOs 12 mol%, Ca
T i O3 is 6 mol%, PbTi0. It was blended so that it was 7 mol%. On the other hand, the semiconducting agent and the additives were made such that Y was 0.38 mol% and Mn was 0.038 mol%.
and Sin were blended to be 0.030 mol% to obtain a blended raw material.

Next, this mixed raw material was wet mixed, pulverized, and calcined at 1130°C to obtain a calcined product. This calcined product is granulated to obtain a granulated product, and an organic binder is added to the obtained granulated product to obtain a thickness of 3.
A molded product was obtained by molding into a 5 m disc shape. This molded product was fired in air at 1350° C. for 1 hour to obtain a barium titanate semiconductor ceramic body. Furthermore, this barium titanate-based semiconductor porcelain body was heat-treated under the conditions shown in Attached Table 1 to obtain barium titanate-based semiconductor porcelain.

In order to measure the electrical properties of the heat-treated barium titanate-based semiconductor porcelain, an In-Ga alloy was applied as an electrode to the barium titanate-based semiconductor porcelain.
The resistance value R1 (Ω) and withstand voltage (V) were measured, and the results are shown in Attached Table 2. In addition, those marked with * in the table are outside the scope of the present invention.

As shown in Attached Table 2, barium titanate-based semiconductor porcelain heat-treated at a temperature exceeding the firing temperature has a low withstand voltage.

On the other hand, barium titanate-based semiconductor ceramics heat-treated below the firing temperature have a high withstand voltage.

Furthermore, the following electrodes were formed on the barium titanate semiconductor ceramics shown in sample numbers 1 to 5.

First, a Ni electrode is applied using Ni electroless plating method, and then Ag! A pole was provided to give samples 1a to 5a.

Further, samples 1b to 5b were prepared by applying a Cr-Ni alloy as an electrode by sputtering.

Then, the resistance value R1 (Ω) and the withstand voltage (V
) was measured. Also, this resistance value R, (Ω) and In-
From the resistance value R, (Ω) at the Ga electrode, by the following formula,
The processing change rate ΔR (%) of the resistance value was determined.

ΔR= (1-(Rz /R,)) xi 00 (
%) These measurement results and calculation results are shown in Attached Table 3.

As is clear from Table 3, in the samples in which the electrodes were formed using the conventional Ni electroless plating method, the resistance value changed significantly due to processing, and the withstand voltage characteristics were significantly deteriorated compared to those of the In-Ga electrodes. In comparison, samples with electrodes formed by sputtering show little change in withstand voltage characteristics.

In this way, after producing a low-resistance barium titanate-based semiconductor ceramic body, it is heat-treated at a temperature below its firing temperature and in an oxidizing atmosphere, and electrodes are formed by sputtering, resulting in small processing changes and high voltage resistance. Barium titanate-based semiconductor porcelain with excellent properties can be obtained. That is, as shown in FIG. 1, the specific resistance distribution within the element of the barium titanate-based semiconductor ceramic used in the electronic component of the present invention becomes extremely uniform, and excellent withstand voltage characteristics are obtained.

Therefore, electronic components using such barium titanate-based semiconductor ceramics have excellent withstand voltage characteristics and high reliability.

This invention is particularly effective for systems containing Pb5iOz, but is not limited to systems containing Pb5iOz and may be applied to other systems.

Further, in this example, the electrode was formed by sputtering a Cr-Ni alloy, but the barium titanate-based semiconductor ceramic electrode may be made of Cr, Ti, Ni,
AI! The electrode may be formed by sputtering , or an alloy thereof, and similar results have been obtained with these.

[Brief explanation of the drawing]

FIG. 1 is a resistivity distribution diagram of a barium titanate semiconductor ceramic element used in an electronic component according to the present invention. FIG. 2 is a resistivity distribution diagram of a barium titanate semiconductor ceramic element used in a conventional electronic component, which is the background of the present invention. Patent Applicant Murata Manufacturing Co., Ltd. Representative Patent Attorney Oka 1) Zenkei Table 1 *marked is table outside the scope of this invention 3 *marked is table outside the scope of this invention 2 *marked is outside the scope of this invention Figure 1

Claims (1)

[Claims] The semiconductor porcelain is heat-treated in an oxidizing atmosphere at the firing temperature of the semiconductor porcelain or a temperature lower than the firing temperature, and further, electrodes are formed on the surface of the semiconductor porcelain by sputtering with Cr, Ti, Ni, Al, or an alloy thereof. formed, electronic components.