Development of conductive silver paste for ZnO varistor chip withstanding the impact of high current

Abstract

Conductive silver paste for ZnO varistor chip withstanding the impact of high current has been prepared in this paper. The results show that the combination of BL-01 and BL-02 and the ratio of conductive phase have great influence on the microstructure, conductivity and adhesion of sintered silver paste. The self-made glass powders BL-01 and BL-02 are the most important factors affecting the adhesion of sintered silver paste. The densification of silver film after sintering also significantly improves the adhesion. A small amount of nano-silver powder is doped in the micron silver powder, resulting in a closer connection between conductive particles in the sintered body, which leads to the improvement of electrical conductivity and adhesion of the sintered silver paste. The current density of the developed sample reached 7.5 kA/cm2, more than 25 % of the industry standard value, and the adhesion reached 18.02 N/mm2.