Nanoindentation properties of intermetallic compounds in lead-free solder joints

The growth of intermetallic compounds (IMC) at the Sn3.0Ag0.5Cu/Cu interface was investigated under isothermal aging temperature of 150℃ and aging time of 100,300, 500 and 1 000 h,respectively. The relationship between the thickness of the IMCs layer and aging time was fitted out,and the growth law of the IMCs layer at Sn3.0Ag0.5Cu/Cu interface under isothermal aging condition was obtained. Mechanical properties of the Cu₆Sn₅ and Cu₃Sn were obtained by a nanoindentation tester. It indicates that with the Cu₆Sn₅ thickness increasing, its Young's modulus and hardness have no significant change. The Young's modulus of Cu₃Sn is greater than that of Cu₆Sn₅,but the hardness of Cu₃Sn is lower than that of Cu₆Sn₅. The nanoindentation experiments of the Sn3.0Ag0.5Cu/Cu interfacial zone show that the hardness of Cu,Cu₃Sn,Cu₆Sn₅ and Sn3.0Ag0.5Cu has an order of magnitude that is in sequence Cu₆Sn₅ > Cu₃Sn > Cu > Sn3.0Ag0.5Cu.