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Indexed by:会议论文

Date of Publication:2013-08-11

Included Journals:EI、CPCI-S、Scopus

Page Number:1090-1093

Key Words:Cu/Sn-9Zn/Cu solder joint; liquid-solid electromigration; interfacial reaction; reverse polarity effect; effective charge number

Abstract:The diffusion behavior of Zn atoms and the interfacial reactions in line-type Cu/Sn-9Zn/Cu solder joints undergoing liquid-solid electromigration (L-S EM) were investigated under a current density of 5.0x10(3) A/cm(2) at 230 degrees C. Liquid-solid (L-S) reaction without current at 230 degrees C was also conducted for comparison. It was clearly observed that there existed a reverse polarity effect induced by the Zn atoms migration towards the cathode undergoing L-S EM, i. e., the interfacial intermetallic compounds (IMCs) at the cathode grew continuously and were significantly thicker than those at the anode. At the anode, dissolution and massive spalling of the interfacial Cu-Zn IMCs occurred and the depletion of Zn resulted in the formation of Cu6Sn5 IMC. At the cathode, the interfacial IMCs remained as Cu5Zn8. It was deduced that the effective charge number (Z*) of Zn atoms in both liquid Sn-Zn solder and interfacial Cu-Zn IMCs turned into positive, resulting in the abnormal diffusion behavior of Zn atoms undergoing L-S EM.