Effect of Interval Aging Mode on IMC Growth between Low Ag Content Sn-0.3Ag-0.7Cu-0.5Bi-Ni and Cu Substrate

Abstract

Abstract-To simulate the application environment of a number of electronic products, the growth of Sn-0.3Ag-0.7Cu-0.5Bi-Ni/Cu solder joints with low content of Ag was investigated during aging in an interval mode. It shows that the intermetallic compound (IMC) (Cu,Ni) 6 Sn 5 layer becomes thicker with increasing aging time. The growth of IMC (Cu,Ni) 6 Sn 5 layer during aging follows the diffusion control mechanism. Furthermore, it is demonstrated that there is no IMC Cu3Sn layer appear whatever increasing the aging time. It is explained the phenomenon is mainly attribute to the interval aging mode. According to kinetics, the activation energy is not high enough to overcome the energy obstacle due to the interval aging mode and finally the Cu3Sn phase doesn't form. Hence, the reliability of solder joints is improved.