| Abstract: | Flip‐chip technology is a face‐down attachment of the active side of the silicon device onto the substrate. It is the ultimate packaging solution to integrated circuit devices used in 21st century electronic systems to meet the requirements of small size, high performance, and low cost. Underfill technology enhances the flip chip on board cycle fatigue life and thus dramatically extends the application of flip‐chip technology in electronics from high‐end to cost‐sensitive commodity products. Reworkable underfill is the key to addressing the nonreworkability of the underfill, so it is very important to electronic packaging. To meet the need for reworkable epoxy resins, four cycloaliphatic epoxides containing thermally cleavable carbonate linkages have been synthesized and characterized. These materials are shown to undergo curing reactions with cyclic anhydride similarly to a commercial cycloaliphatic diepoxide. Furthermore, these cured epoxides start to decompose at temperatures lower than 350 °C, the decomposition temperature for the cured sample of the commercial cycloaliphatic diepoxide. Two formulations based on two carbonate‐containing diepoxides start network breakdown around 220 °C, which is the targeted rework temperature. Moreover, these two formulations have similar properties, including the glass‐transition temperature, coefficient of thermal expansion, storage modulus, viscosity, and adhesion, compared to the standard commercial diepoxide formulation. As such, these two formulations are potential candidates for a successful reworkable underfill. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3771–3782, 2000 |
