The effect of thermal aging on the mechanical properties of molding compounds and the reliability of electronic packages

Epoxy Molding Compounds are widely used in electronic packaging as encapsulants of electronic devices. Previous research has indicated that thermal aging has great influence on the material properties of molding compounds. The thermal aging effects will certainly influence the reliability performance of the packages. It is very necessary to study the effect of thermal aging on the mechanical properties of molding compounds and the reliability of electronic packages. In this paper the effect of thermal aging on the mechanical properties of molding compounds and the reliability of electronic packages is presented. Experimental study of the aging effect on the mechanical properties of the molding compounds was performed. The samples were aged at various levels of temperature and aging times. DMA and TMA were used to measure the moduli, coefficients of thermal expansion (CTE), and the glass transition temperature (Tg). It is found that thermal aging has significant influence on the rubbery modulus and the glass transition temperature (Tg). Oxidation is believed to be one of the main mechanisms for the degradation of the material properties. A numerical model was used to estimate the modulus of the oxidized layer. 3D finite element models were established to simulate the impact of the aging effect on the stress/strain of the package. The modeling results indicate that the aging of the compounds have a significant impact on the stress/strain status in the package.