Joule heating dominated fracture behavior change in micro-scale Cu/Sn-3.0Ag-0.5Cu/Cu(Ni) joints under electro-thermal coupled loads

Joule heating dominated fracture position transition from the interface between the solder and the intermetallic compound (IMC) layer to the solder matrix occurs in micro-scale Cu/Sn-3.0Ag-0.5Cu/Cu(Ni) joints under electro-thermal coupled loads with a high current density and increasing temperature. The interfacial fracture is triggered by localized-melting of the solder induced by current crowding at grooves of the interfacial IMC grains and driven by the strain mismatch between the solder and the interfacial IMC layer, while fracture in the solder matrix is caused by matrix bulk melting and the constraint effect from the interfacial IMC layer-substrates.