Highly thermal conductive EMCs (Exopy Molding Compounds) should be considered for the alleviation of thermal stress-related problems caused by low thermal conductivity, and high elastic modulus of EMCs and by a mismatch of CTE (Coefficient of Thermal Expansion) between EMCs and the Si-wafer. Compared to crystalline silica-filled EMCs, alumina filed EMC improved the value of thermal conductivity by 100% and lowered the value of CTE by 50%. As a result, compared to typical crystalline silica-filled EMCs, the thermal fatigue resistance of alumina-filled EMC was improved by sixfold.