Flip chip technology has attracted considerable attention due to its advantages in providing higher I/O interconnects and better electrical and thermal performances. Solder joint not only offers electrical connection between the silicon chip and the substrate, but also offers mechanical connection in electronics. The reliability of solder joint has been become an increasingly extrusive problem. Among the study of flip-chip solder joints reliability, the interfacial reaction between solder and UBM is a fundamental and crucial subject. Sn-Pb solder is still commonly utilized in many high reliability applications due to its excellent physical, mechanical and metallurgical performances. And this paper mainly introduces the growth and evolution of the IMC during solid-state annealing of Sn-Pb solder joints. This study showed that Ti-Cu-Ni UBM has a better performance compared with Ti-Cu-Cu UBM. And we also found that the tin content in the solders has a significant effect on the formation of the intermetallic compounds during interfacial reaction.

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