Effects of the Curing Properties and Viscosities of Non-Conductive Films (NCFs) on the Sn-Ag Solder Bump Joint Morphology and Reliability

In this study, solder bump flip chip assembly using NCFs was evaluated for Sn-Ag solder bumps. Flip chip bonding was performed using an isothermal Thermo-Compression (TC) bonding method for 5 seconds. Solder bump joints were evaluated by adjusting the curing properties such as curing onset, peak temperature, and degree of curing and viscosities of NCFs using curing agents and silica contents. And then, the degree of cure and viscosity approximations were conducted to define the precise viscosity of NCFs at the solder melting temperature using measured degree of cures at various bonding temperatures and viscosities. Finally, high temperature and humidity test (85RH%/85°C test) and temperature cycling (T/C) test were performed to evaluate the thermo-mechanical reliability performance depending on solder joint.