| Abstract |
| The microstructural investigation and thermo-mechanical reliability evaluation of the Sn-3.0Ag0.5Cu solder bumped flip chip package were carried out during the thermal shock test of the package. In the initial reaction, the reaction product between the solder and Cu mini bump of chip side was Cu6Sn5 IMC layer which has the same composition with that of Sn-37Pb case, while the two phases which were (Cu,Ni)6Sn5 and (Ni,CuhSn1 were formed between the solder and electroless Ni-P layer of the package side. The cracks were observed at the corner solder joints after the thermal shocks of 400 cycles. The primary failure mechanism of the Pb-free Sn-3.0Ag-0.5Cu solder joints in this type of package was also conftrmed to be thermally activated solder fatigue failure. The finite element analyses were conducted to interpret the failure mechanisms of the packages. The finite element analyses revealed that the cracks were induced by the accumulation of the plastic work and viscoplastic shear strains. |
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| Key Words |
| Pb-free solder, Flip chip, Reliability, Finite element analysis |
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