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Indexed by:会议论文

Date of Publication:2007-01-01

Included Journals:CPCI-S

Page Number:145-148

Abstract:Sn-0.7Cu, Sn-3.5Ag, Sn-4Ag-0.5Cu lead-free solder bumps were produced by stencil printing of solder pastes on wafers having electroless Ni-P immersion An (ENIG) under bump metallization (UBM). The diameter of the solder bumps was 45 similar to 47 mu m. Shear tests were carried out to evaluate the bonding quality of the solder bumps after multiple reflows and thermal aging at 150 degrees C. The fracture surface, cross section microstructure and interfacial intermetallic compounds (IMCs) growth kinetics were investigated to identify the correlation between failure mode and the metallurgical characteristics of the UBM/solder interface IMC layers. The interfacial IMC phase was mainly (CuNi)(6)Sn-5 for Sn-4Ag-0.5Cu and Sn-0.7Cu solders and Ni3Sn4 for Sn-3.5Ag solder. The coarsening of Ni3Sn4 IMC phase for Sn-3.5Ag solder was much greater than that of (CuNi)(6)Sn-5 for Sn-0.7Cu and Sn-4Ag-0.5Cu solders with increasing reflow times. Even if only a small amount of Cu is presented at the interface during reaction, the type, size, morphology and evolution of the interfacial IMCs are greatly different.