Thermal and Rheological Characterization of Nonconductive Adhesive Epoxy for Process Parameter Definition of Air Cavity Mold Package Encapsulation

Abstract

A new formulated nonconductive epoxy adhesive for air cavity mold encapsulation is characterized using thermal and rheological analysis to arrive with optimized processing parameters. Based from the results, heating the epoxy under low b-stage temperature for 91 to 120 minutes showed no significant difference with mid b-stage temperature for 31 to 60 minutes in terms of physical condition, mold adhesion strength and percent cure which implies that B-staging condition can be done in an hour or less through increasing the temperature slightly higher but below the glass transition of the epoxy. Moreover, shortest possible cap-sealing cycle time was determined by gross leak test and percent cure in which heating the B-staged glue at high cap sealing temperature for 1 to 5 minutes yielded same percent cure with low cap sealing temperature for 16 to 20 minutes with no gross leaks. The C-stage curing step can be done at a temperature similar to the cap-sealing temperature but soaked for 31 to 60 minutes to achieve 100% degree of curing denoting that polymeric matrix have completely crosslinked for a reliable encapsulant.