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Indexed by:会议论文

Date of Publication:2012-08-13

Included Journals:EI、CPCI-S、Scopus

Page Number:498-501

Abstract:Short time interfacial reactions between Sn-3Ag-0.5Cu solder balls and ENEPIG pads at 250 degrees C were investigated. Transitions in morphology and type of the interfacial intermetallic compounds (IMCs) with reaction time were revealed. It was found that the transition rate of the interfacial IMCs in smaller solder joints was faster than that of larger ones. For 200 mu m solder joint, dodecahedron type (Cu, Ni)(6)Sn-5 grains together with brick type (Ni, Cu)(3)Sn-4 particles first formed at the interface. Then (Ni, Cu)(3)Sn-4 grew up rapidly with (Cu, Ni)(6)Sn-5 particles submerged and even disappeared in the weed shape (Ni, Cu)(3)Sn-4. For 300 mu m solder joint, hexagonal prism (Cu, Ni)(6)Sn-5 particles with pointed tips firstly formed at the interface. Then the particles quickly transformed to polyhedron type IMC within the following few seconds. Thereafter, with the interfacial reaction kept going, (Ni, Cu)(3)Sn-4 needles grew up from the interspaces of (Cu, Ni)(3)Sn-5 particles. It is convinced that the change of Cu concentration in the solder balls is the main reason causing the IMCs transformations.