Influence of Transfer Molding Process on the Reliability of High Mass Epoxy Mold Compound Molded Package

Inhalt:
Overmolding power modules consumes more epoxy molding compound (EMC) than molding discrete devices. The increased EMC mass affects the heating of the EMC, which in turn affects flow viscosity. In this study, the effects of the number of EMC pellets and their pretreatment on flow temperature evolution were investigated using an experimental melting test rig. Additionally, dummy plastic leaded chip carrier (PLCC) leadframes were overmolded with (non-)preheated pellets at temperatures of 175 °C and 165 °C. The molded products were subsequently aged at 200 °C for 600 hours. Pellet preheating plays a more essential role than molding temperature in the encapsulation reliability, providing the lowest porosity and thinnest thermal oxide layer over the thermal exposure.