The Effects of Silica Fillers on the Properties of Encapsulation Molding Compounds

Encapsulation molding compounds (EMCs) are commonly used to protect integrated circuit (IC) chips. Their composition always contains fillers of a large amount (about 70%) and will affect the properties of the compounds. Thus, in order to clarify the filler effects, in this study, three types of silica fillers including crystal silica, edgeless silica, and fused silica were studied experimentally to explore their effects on the compounds. The results show that all of the flow spiral length, glass transition temperature (Tg), coefficient of thermal expansion (CTE), and water absorption rate of the encapsulation molding compounds decrease as the filler amount increases, irrespective of the filler type. In contrast, both thermal conductivity and flexural strength of the compounds increase as the filler amount increases, but also irrespective of the filler type. For the three fillers, the edgeless silica filler has the advantage of a large flow spiral length and can be molded better. It also has a larger thermal conductivity, larger flexural strength, and lower water absorption rate. Hence, for low stress industrial applications, the edgeless silica should be adopted as the filler of the encapsulation molding compounds.