Moisture diffusion in epoxy molding compounds filled with particles

Mechanical reliability of epoxy molding compounds in plastic packages of integrated circuits (IC) is greatly affected by the compound ability to absorb moisture. Accordingly, the objective of the study is to evaluate the effect of moisture sorption on the mechanical properties of the compound. Experimental studies were conducted to evaluate the moisture diffusion in compounds with different, from moderate to high, concentration of silica and alumina nitride fillers. The weight-gained analysis indicated that the moisture diffusion was of non-Fickian type and depended mainly on the specimen's relative humidity and the filler concentration. We found that although the hygro-thermal stresses, caused by moisture diffusion, were relatively low, such diffusion led to an appreciable decrease in the compound's strength. Moisture diffusion can result also in a substantial increase in the material's plasticity. The obtained results can be helpful in the analysis of the mechanical behavior of molding molding compounds employed in electronic packaging. These results can be used to better understand and to improve the reliability of plastic packages of IC devices.