Creep mechanism in characteristic orientation of Sn and Sn-1.8Ag by nanoindentation

Creep properties of Sn, Sn-1.8Ag and their (100), (001) grain orientation were investigated by nanoindentation method, which could simulate the situation where solder joints suffered from stress. Also, the constant strain rate test was conducted to acquire hardness data in the steady state. The result shows that stress exponent (n) of Sn is 11.1 in (100) and 5.8 in (001); n of Sn-1.8Ag is 12 in (100) and 6.5 in (001). Increase of n represents that the content of Ag would greatly enhance the creep resistance in Sn matrix. Moreover, data of Sn (100) grain exhibit lower stain rate than (001) grain in the low stress region, which could indicate Sn (100) grain is more beneficial to be used in electronic package. As a result, combination of Ag addition and Sn (100) plane attached on the substrate would have better mechanical properties and prolong the creep life of solder joints.