Matsushita Electric Industrial Co., Ltd.

Keiichi Noi

Akihiro Takami

Kazuhide Ebine

Kimiko Kumazawa

Tatsuya Inoue

Yasuo Wakahata

Iwao Ueno

Hideaki Tokunaga

Kaori Shiraishi

Riho Sasaki

Yoichi Ogoshi

A precipitate film having plating resistance may be formed on the surface of a varistor element during sintering process. Accordingly, the manufacturing process can be shortened, thereby improving the productivity. The manufacturing method comprises (a) a first process of forming the varistor element whose main component is zinc oxide; (b) a second process of sintering the varistor element and precipitating zinc compound having at least one of acid resistance and alkali resistance on the surface of the varistor. Preferably, the manufacturing method further comprises (c) a process of attaching an external electrode to the varistor element, and the external electrode attaching process is executed after finishing the varistor element sintering process.

Zinc oxide varistor and method of manufacturing same

Method for producing ceramic parts

It is a voltage-dependent non-linear resistance ceramic composition comprising SrTiO.sub.3 as host material, Dy.sub.2 O.sub.3 or Dy.sub.2 O.sub.3 and Nb.sub.2 O.sub.5 or Ta.sub.2 O.sub.5 or Ta.sub.2 O.sub.5 and Nb.sub.2 O.sub.5 as accelerating agent for semiconductorization, thereby changing crystal to a low resistance, and changing crystal boundary to a high resistance. In case Dy.sub.2 O.sub.3 or Dy.sub.2 O.sub.3 and Nb.sub.2 O.sub.5 are used as the accelerating agent for semiconductorization, one kind or more selected from the group consisting of Na, K, Ca, Cd, In, Ba, Pb, Ag, Ce, La, Sc, Y, Cs, Au, Mg, Zr, Sn, Sb, W, Bi, Ni, Fe, Ga, Pt, Tl, Al, Si, Be, Li, Eu, Gd, Tb, Tm, Lu, Th, Ir, Os, Hf and Ru. Alternatively, in case Ta.sub.2 O.sub.5 or Ta.sub.2 O.sub.5 and Nb.sub.2 O.sub.5 are used as the accelerating agent for semiconductorization, one kind or more selected from the group consisting of Na, K, Ca, Cd, In, Ba, Pb, Mg, Zr, Sn, Sb, W, Bi, Eu, Gd, Tb, Tm, Lu, Th, Ir, Os, Hf, Ru, Ga, Pt, Tl, La, Sc, Y, Cs, and Au. As a result, baristor characteristic is obtainable by means of the high resistance at crystal boundaries and capacitor between crystal granules--crystal boundary--crystal granule. From this matter, an element having both functions of the baristor characteristics and the capacitor characteristics are obtainable, and performs effect in surge absorption and noise elimination.

Voltage-dependent non-linear resistance ceramic composition

This is a voltage-dependent non-linear resistance ceramic composition wherein resistance of crystal is decreased by containing SrTiO.sub.3 as host material, and Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 as semiconductorization accelerating agent, and further by adding as additive one kind or more oxide of element selected from the group consisting of MnO.sub.2, Ga, Pt, Tl, Si, Ti, Li, La, Cu, Y, Cs, Au, Mo, S, Be, Al, Na, K, Ca, Cd, In, Ba, Pb, Eu, Gd, Tb, Tm, Lu, Th, Ir, Os, Hf, Ru, Mg, Zr, Sn, Sb and W, these additive is segregated at crystal granule boundaries, thereby making the crystal granule boundaries to high resistance. Accordingly, by the high resistance layer at the crystal boundaries the varistor characteristic is obtainable, and a capacitance characteristic is obtainable between the crystal granule-crystal granule boundary-crystal granule. From this, an element having both functions of the varistor characteristics and the capacitor characteristics are obtainable, and performs effect in surge absorption and noise elemination.

A voltage-dependent non-linear resistance ceramic composition comprises SrTiO.sub.3, Sr.sub.1-x Ba.sub.x TiO.sub.3 (0.001.ltoreq.x.ltoreq.0.300) or Sr.sub.1-x Ca.sub.x TiO.sub.3 (0.001.ltoreq.x.ltoreq.0.300) as host material and further includes 0.001-2.000 mol % of Y.sub.2 O.sub.3 as metal oxide for semiconductorization acceleration, 0.001-3.000 mol % of metal oxide(s) of at least one selected from the group consisting of Ca.sub.2 O.sub.3, CuO, Ag.sub.2 O, Al.sub.2 O.sub.3, ZrO.sub.2, Bao, SiO.sub.2, MgO, B.sub.2 O.sub.3, MnO.sub.2, NiO, MoO.sub.3 BeO, Fe.sub.2 O.sub.3, Li.sub.2 O, Cr.sub.2 O.sub.3, PbO, CaO, TiO.sub.2, P.sub.2 O.sub.5, Sb.sub.2 O.sub.3 and V.sub.2 O.sub.5, which segregates at grain boundary to make the grain boundary selectively to high resistances; an element made of the composition has both characteristics of capacitance and varistor, and is suitable for filter to remove noise or surge.

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Osaka, Japan

Keiichi Noi