The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 14, 1998
Filed:
Aug. 29, 1996
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
A zinc oxide ceramic and a method for producing the zinc oxide ceramics are provided wherein a zinc oxide varistor for a high voltage which has excellent electric characteristics and great reliability for DC loading and surge can be produced in high yield by performing sintering at a temperature of 750.degree. to 1050.degree. C. At least one of B.sub.2 O.sub.3, Cr.sub.2 O.sub.3, GeO.sub.2, LaO.sub.3, MgO, Nb.sub.2 O.sub.5, Nd.sub.2 O.sub.3, PbO, PrO, Sb.sub.2 O.sub.3, SiO.sub.2, SnO.sub.2, Ta.sub.2 O.sub.5, WO.sub.3 and Y.sub.2 O.sub.3 powders and a Bi.sub.2 O.sub.3 powder are mixed. A mixture thus obtained is heat treated at a temperature of 400.degree. to 700.degree. C. and ground to prepare a synthetic powder. 0.5 to 20 parts by weight of the synthetic powder and 0.1 to 5.0 parts by weight of at least one of CoO, MnO.sub.2 and NiO powders are added and ground for 100 parts by weight of a zinc oxide powder. A binder is added to the ground powder to form a sheet. A silver paste is applied to the surface of the sheet to laminate four sheets. A lamination is integrally sintered at a temperature of 840.degree. C. A zinc oxide varistor of a lamination type comprises an internal silver electrode, an internal silver counter electrode, an effective layer, a noneffective layer, and an external silver electrode.