Effect of reflow conditions on the die shear strength in flip chip on board with SAC305 solder joints

Solder bump joint has been accepted as a main FCOB interconnection method so far. To optimize the process conditions for achieving SAC305 solder bumped FCOB assembly with maximum die shear strength and allowable void rate, an orthogonal experimental design of four factors and three levels was carried out. The optimal process conditions are: 100 seconds for preheating time, 245 °C for peak temperature, 60 seconds for time above liquidus, flux paste as the auxiliary material. Three fracture modes were observed and categorized for samples after shear test based on the fracture interface location. The most frequently occurring fracture mode is the ductile.