JPH0310216B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a multilayer ceramic capacitor having base metal electrodes. In recent years, with the development of electronics, the miniaturization of electronic components has progressed significantly. In the case of ceramic capacitors, electrodes are printed on green sheets, and the green sheets are layered to form a laminate so that the electrodes are exposed alternately on the end faces and face each other, and this laminate is thermocompressed and placed in the air. There is a growing trend toward miniaturization of so-called multilayer capacitors, which are obtained by methods such as firing at 1,200 to 1,400 degrees Celsius. However, since the electrodes of multilayer capacitors are fired simultaneously with the dielectric ceramic,
It is necessary that the metal does not react with the porcelain material and does not oxidize at high temperatures of 1200-1400°C. Platinum, palladium, or an alloy of both have been used as metals that meet these conditions, but these metals are extremely expensive and have been a major obstacle to widespread use of multilayer capacitors. As an alternative to such expensive electrode materials,
A method has been proposed in which base metal electrodes are made of inexpensive materials such as nickel, but since these electrode metals oxidize when fired in air, they must be fired in a reducing atmosphere. However, the drawback of conventional dielectric ceramic materials mainly made of barium titanate is that they become semiconducting when fired in a reducing atmosphere, resulting in significant deterioration of electrical properties such as insulation resistance and dielectric loss, making them unusable as capacitors. It was hot. The present invention eliminates these drawbacks and provides a multilayer ceramic capacitor with base metal electrodes that has excellent electrical properties even when fired in a reducing atmosphere. The present invention will be explained below using examples. Barium carbonate, yttrium oxide, titanium oxide, zirconium oxide, magnesium oxide, chromium oxide, vanadium oxide, manganese oxide, tin oxide, tungsten oxide, indium oxide, etc. were mixed to have the composition shown in Table 1, and wet-processed for 16 hours. After mixing, it was dried. This mixed raw material is placed in the air.
The mixture was calcined at 1050 to 1200°C for 2 hours, wet-pulverized, and then dried. An organic binder was added to this powder, which was then granulated and molded to a size of 10 mm in diameter and 0.6 mm in thickness.
Ni electrode paste is applied to the molded body thus obtained using a screen diameter of 8.0 mmφ, and O ₂ partial pressure is very low (1000 ppm or less) and neutral (for example, in N ₂ ).
Or reducing atmosphere ( _N2 / _H2 =100/0~90/
10) The fired body was maintained at 1300 to 1400°C for 2 hours, allowed to cool naturally, and at 150°C or lower, the gas input was stopped and the fired body was taken out. The electrical characteristics of the dielectric ceramic having the Ni electrode thus obtained were measured, and the results are also shown in Table 1. Capacitance (Cap) and dielectric loss (tanδ) in Table 1
is the value at 1Vrms, 1KHz, and the insulation resistance (IR) is 50V.
The measured values after applying DC for 1 minute are shown. Note that the sample numbers marked with a circle in the table are outside the scope of the present invention, and all others are within the scope of the present invention. It can be seen that the product according to the present invention can obtain excellent electrical properties when fired in a neutral or reducing atmosphere.

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Claims (1)

[Claims] 1 General formula A (Ba _1-x Yx) O.B (Ti _1-y Zry)
A multilayer ceramic capacitor characterized in that a base metal electrode is formed on a dielectric ceramic containing Zwt% of at least one of the oxides of Mg, Cr, V, Mn, Sn, In, and W in O ₂ . 0.005≦x≦0.1 0≦y≦0.3 1.00＜A/B＜1.05 0＜z≦1.0