| 摘要 |
Provided are a multilayer chip ZnO varistor with base metal inner electrodes and a preparation method thereof. The varistor is formed by ceramic sheets and inner electrodes which were alternately laminated. Wherein the main material of inner electrodes is the base metal nickel(Ni), both ends of the varistor are coated with silver electrodes. The present invention has the following beneficial effects: (1) the material formula of ZnO varistor is suitable for the preparation process of reduction and reoxidation; (2) the base metal Ni is used as inner electrodes which can sharply reduce the preparation cost of a multilayer chip ZnO varistor; (3) using a conventional solid-phase sintering method, it can complete the burning of silver and the oxidation of the ceramic simultaneously which is suitable for mass production; (4) the nonlinear coefficient of the ZnO multilayer chip varistor produced by the method of this invention can reach 30 or more, the varistor breakdown voltage is less than 20V and the size can be standard chip package size 0805,0603,0402 and 0201. |
| 主权项 |
1. A method for preparing a ZnO multilayer chip varistor with base metal inner electrodes, comprising the steps of:
(1) adding oxides of manganese (Mn) and cobalt (Co) into a mixture of zinc oxide (ZnO) and bismuth oxide (Bi2O3), adding deionized water thereto for ball-mill mixing, drying and sieving to generate a slurry, thereby obtaining powders, with a molar fraction of ZnO is of 93% to 98.7%, a molar fraction of Bi2O3 is of 0.2% to 5%, and molar fractions of the Mn oxide and the Co oxide of 0.01% to 5% each; (2) mixing a dispersing agent, defoaming agent, solvent and binder with the powder, and then ball-milling to obtain a slurry; (3) tape-casting the slurry and cutting it, thereby obtaining green sheets, using the base metal nickel (Ni) as the main material for inner electrodes, laminating, pressing and cutting into rectangles to obtain molded samples; (4) sintering the molded samples at a temperature of 850-1150° C. in a protective atmosphere, thereby obtaining a ceramic chip varistor; (5) performing heat treatment thereon in oxygen or air at a temperature of 500-800 ° C., coating silver electrodes on both ends, and burning Ag electrodes, thereby obtaining ZnO multilayer chip varistors with the base metal inner electrodes. |
