銅－はんだ接合体のせん断試験FEAによるCu/Sn系IMCsの材料非線形性の検証

抄録

The intermetallic compounds (IMCs) layer consisting of Cu3Sn and Cu6Sn5 is generated at the interface between solder and copper wiring during a soldering process. The strength reliability of fine solder joints must be evaluated by conducting a finite element analysis (FEA) considering the presence of the Cu/Sn IMCs layer. To conduct such FEA accurately, the tensile stress-strain curves of the Cu/Sn IMCs are needed. Therefore, we proposed a method to estimate the stress-strain curve of the IMCs by conducting the tensile test using the miniature composite solder specimen with IMCs layer. The stress-strain curve estimated by the proposed method suggested that the both IMCs showed material nonlinearity. This finding should be verified in some way, because the Cu/Sn IMCs have been conventionally regarded as brittle materials which does not show plastic deformation. In this study, the shear tests using a copper-solder joint specimen, in which the solder joint has the IMCs layer, were conducted both experimentally and numerically. The numerical tests were conducted as FEAs, and the FEAs employed two different constitutive models of elastic model and elasto-plastic model to describe the deformation behavior of the Cu/Sn IMCs. Based on the experimental results and the results of FEAs, we discussed the presence or absence of the material nonlinearity of the Cu/Sn IMCs.