VISCOPLASTIC-DAMAGE CONSTITUTIVE MODEL COUPLED WITH VOID EFFECTS FOR Pb/Sn SOLDER ALLOYS

Sn-Pb eutectic solder alloy is extensively used in microelectronics packaging interconnects.Due to the high homologous temperature eutectic Sn-Pb solder exhibits creep-plasticty interaction and significant time,temperature and rate dependent material characteristics.Such complex behavior makes the constitutive modeling an extremely difficult and important task.A viscoplastic-damage constitutive model with void effects is proposed.Based on the Gurson-Tvergaard-Needleman plastic potential equation and the orthogonal rules,the effect of void volume fraction was introduced into the material constitutive law to document the mechanics behavior of eutectic solder alloy.The model is verified against various test date,and shows strong application potential for reliability of solder joints in electronic packaging.