The impact of high glass transition temperature of molding compounds on power package warpage and stress performance

High Glass Transition Temperature (Tg) Molding Compound (MCs) are preferred for power and automotive packages due to their suitability in high temperature applications. However, our recent study on high Tg MCs showed that their susceptibility for delamination risk increased especially at low temperature conditions. In this work, three types of Mold Compounds were intentionally selected for evaluation and comparison. There are two High Tg MCs and one normal Tg MC with multi-aromatic resin. Properties of MC samples, mainly their weight loss, Tg, CTE and Storage Modulus, were measured and recorded by means of TGA, Thermal Mechanical Analysis(TMA) and Dynamical Mechanical Analysis(DMA). TMA and DMA were used to characterise the viscoelastic behaviour of 3MCs over temperature. In this study, we evaluated with finite element analysis (FEA) the impact of mold compound on chip deformation and induced stresses at bi-material interfaces within the package for qualitative correlation & risk assessment of chip crack & interfacial delamination during assembly process steps & thermal cycling (TC) reliability test temperatures.