FTIR Method to Distinguish Mold Compound Types and Identify the Presence of Post-Mold-Cure (PMC) Treatment on Electronic Packaging

In electronic packaging, molding compounds have been widely used for encapsulation. Mold compound with different epoxy resin & hardener formulation will have different mechanical and chemical properties. Mold compounds reacts as a protection material by isolating the electronic devices from moisture and pollutants in order to achieve its robustness expectancy. In addition, enhancing proper polymerization through post mold cure (PMC) treatment is known to improve glass transition temperature and dielectric properties, volume resistivity increases and the electrical insulation capability of a cured compound improves during post cure. These improvements are principally due to the increased cross link density in the epoxy network as well as decreases of free dipoles and charge carriers. Hence it is vital to ensure that an appropriate mold compound type and sufficient PMC was applied to achieve desired package integrity and reliability. In this study, a range of cured compounds with various types of resin composition were analyzed using Fourier Transform Infrared Spectroscopy (FTIR). Unique Infrared signature at 1400-1650 wavenumber region is detected, corresponding to aromatic C=C absorption of mainly epoxy and hardener structures, that enables one to differentiate between mold compound types. Besides, the response of infrared bands with respect to PMC duration is discussed. The absolute relative peak area of the characteristic infrared bands at 1600 cm^-1 against 1500 cm^-1 is measured. The result showed that there is significant reduction in peak area ratio on 2 hours PMC sample compared to those without PMC. This finding is useful to distinguish presence of PMC treatment on Integrated Circuit (IC) package.