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Indexed by:会议论文

Date of Publication:2011-08-08

Included Journals:EI、CPCI-S、Scopus

Page Number:316-320

Abstract:The Cu/Sn3.0Ag0.5Cu/Ni (Cu/SAC305/Ni) solder joints were designed to investigate the Cu, Ni atoms diffusion behavior and the interfacial reaction during electromigration (EM) at 180 degrees C under a current density of 1.0x10(4) A/cm(2). For comparison, the Cu/Sn3.0Ag0.5Cu/Ni solder joints were aged at 180 degrees C for the same durations. In as-soldered state, the (Cu0.55Ni0.45)(6)Sn-5 and (Cu0.92Ni0.08)(6)Sn-5 IMCs formed at the SAC305/Ni and SAC305/Cu interfaces, respectively. The interfacial IMC thickness increased with increasing aging time. During EM, the current direction played an important role on Cu consumption. When electrons flowed from PCB side to chip side, the Cu pad dissolved into the solder and microcrack formed at the solder/Cu interface. The dissolved Cu atoms were driven toward the anode side and precipitated as large Cu6Sn5 IMCs in the solder matrix along the flowing direction of electrons. While when electrons flowed from chip side to PCB side, no Cu pad consumption was observed and a thick layer-type Cu6Sn5 IMC formed at the SAC305/Cu interface; the thickness of the interfacial IMCs increased with increasing EM time and increased to 15.90 mu m after EM for 100 h. As to Ni UBM, no significant consumption of Ni was observed even electrons flowed from chip side to PCB side. Ni UBM was more resistant than Cu UBM during EM. After EM for 143 h, the solder joint failed due to the melting of the SAC305 solder bump.