Nanoindentation analysis of interfacial IMCs in electronic solder joints

To evaluate the behavior of intermetallic compounds (IMCs) at different loading conditions, this study examined the hardeness and modulus of the IMCs formed at the interfaces between potential Pbfree solders (Sn-Ag-Cu and Sn-Zn) and the substrates of Cu and Ag. Compared to Ag based IMCs, Cu based IMCs are harder, stiffer, but less strain rate sensitive. It is also found that the morphology of the indent impression depends on the ratio of the modulus to hardness, and the crystal structure of the IMCs.