Impact of pad finish on mechanical shock resistance of lead-free solder joints tested under shear and in pull mode

Fracture of Intermetallic Compounds (IMC) under mechanical shock is a major concern for soldered components. While most shock tests are performed under shear load, a specially designed sample setup is designed and fabricated allowing testing under axial pull direction. These samples are fabricated with two pad finish - NiAu and SAC HASL - and comparing solder mask versus non-solder-mask pad defined solder joints. A mini scale of the Charpy equipment setup measures the energy taken up by the solder joints before fracture. The impact of thermal ageing on the shock resistance is also investigated.