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Solder joints are the main weak points of power modules used in harsh environments. For the power module of electric vehicles, the maximum operating temperature of a chip can reach 175 • C under driving conditions. Therefore, it is necessary to study the high-temperature reliability of solder joints. This study investigated the creep properties of Sn-3.0Ag-0.5Cu (SAC305) and Sn-8.0Sb-3.0Ag (SSA8030) solder joints. The creep test was conducted at 175 and 190 • C with the application of 2.45 MPa. The SAC305 solder had superior creep properties to those of SSA8030 solder at 175 • C and at largely the same homologous temperature (T H~0 .91 for SAC305 and T H~0 .92 for SSA8030). Both solders had primary β-Sn and a eutectic mixture of β-Sn and Ag 3 Sn. Compared to SSA8030, the SAC305 solder contained~10% more eutectic structure and contained Ag 3 Sn that was 3 times smaller and more round in shape. Furthermore, the SSA8030 solder precipitated SnSb in an elongated fiber shape (1-50 µm in size) after the creep test. Coarse and elongated Ag 3 Sn and SnSb of the SSA8030 solder negatively affected crack propagation in the dislocation creep region and decreased the creep resistance.

Due to ELV banning, automotive electronics cannot use four kinds of heavy metal element (Pb, Hg, Cd, Cr 6+) from 2016. Therefore, this study was focused on degradation characteristics of Sn-3.0Ag-0.5Cu Leadfree solder joint with OSP and ENIG finsh under various reliability assessment method, as like to thermal shock test and high temeprature/high humidity test with test duration for cabin electronics. Also, we compared bonding strength degradation to other advanced research results of electronic control unit for engine room because of difference service temperature with mount location in automotive. Whisker growth phenomenon and mitigation method which were essentially consideration items for Pb-free car electronics were examined. Conformal coating is a strong candidate for mitigating whisker growth in automotive electronics. Necessary condition to adapt Pb-free in car electronics was shown.

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