초록 열기/닫기 버튼
In this study, a new lead-free solder, Sn-0.7Cu-0.2Cr (wt.%) alloy, was developed. The mother alloy of Sn- 0.7Cu-0.2Cr solder, which has melting temperature of about 231℃, was fabricated and then made by 300 um solder balls. To evaluate the thermo-mechanical reliability of the new solder alloy for automobile electronics, multiple reflows test was performed. As a result of the microstructure analysis, grain size increased with increasing reflow test. And microstructure of Sn-3.0Ag-0.5Cu solder was finest. It was also confirmed that the microstructure of Sn-0.7Cu-0.2Cr solder was finer than Sn-0.7Cu solder by Cr addition. The IMC thickness results show that the presence of Cr in solder inhibits the growth of interfacial Cu6Sn5 layer and Cu3Sn layer. Specifically, the shear strength of the Sn-0.7Cu-0.2Cr/Cu solder joints increases by 9% and 22% than that of Sn-3.0Ag-0.5Cu and Sn-0.7Cu solder joints after 10 reflows test at 1m/s shear speed. And brittle fracture rate (%) of Sn-0.7Cu-0.2Cr was lower than Sn-3.0Ag-0.5Cu and Sn-0.7Cu solder after 10 reflows test at 1m/s shear speed.
