Effects of Twin Boundary and Precipitates on Board Level Reliability in Sn-Ag-Cu(SAC) Solder Joints through EBSD Analysis

In order to improve the high board level reliability characteristics of electronic packages, a solder joint composed of a three-component composition of Sn-Ag-Cu (SAC) is has been studied. IMC thickness and the mechanical strength of the solder are controlled by changing the content of Ag and Cu in the SAC solder and by adding additives. However, since more than 95% of the solder joint is Sn, it is necessary to study the Sn microstructure behavior in board level reliability environments. In this study, the effect of the Sn microstructure characteristics of the solder joint on the failure of board level reliability test using the solder containing Ni and Bi additives. Twin by Ni and Bi precipitate were defined as effective factors for decreasing failure occurrence. Finally, the effect of twin by Ni and Bi precipitates on crack propagation will be discussed in detail through electron backscatter diffraction (EBSD) analysis.