Aging Characteristics of Green Mold Compound for Use in Encapsulation of Microelectronic Devices

Epoxy mold compounds can exhibit changes in material properties with aging at high temperature, that can significantly affect reliability of interconnects. This study focuses on characterizing elastic modulus, coefficient of thermal expansion and glass transition temperature for epoxy 'green' mold compounds, on un-aged and devices that were aged at maximum dwell temperature of 185°C. This study involves using commercial devices unlike other studies presented in literature where lab cured specimen were used. Characterization of mold compound on commercially available packages molded in production line gives valuable information but is challenging due to geometrical constraints. Hence, conventional techniques, such as DMA, cannot be used to obtain properties of mold compound in packaged devices. Thus, majority of the work is done with nanoindentation and thermomechanical analyzer (TMA). Additionally, the mechanism of aging due to oxidation is discussed and growth constant and activation energies for oxidized layer are provided.