Novel Epoxy‐based Compositions for Microelectronics Packaging Applications: Part I

Abstract

Novel epoxy formulations have been developed for microelectronic packaging applications. The resin compositions are based on cycloaliphatic esters and proprietary epoxies, which possess excellent thermal and electrical stability. The key features of these materials are short cure cycle, long‐term stability at 25°C, very low cure volatile, low moisture absorption, low coefficient of thermal expansion (CTE), and excellent adhesion to various substrates. In addition, the change in CTE below and above the glass transition temperature of the polymers is minimal. This unique behaviour is attributed to the interpenetrating network‐like (IPN) structure of the base resin composition. Further evidence of the IPN structure is the broad loss modulus and tan δ observed between −150°C and +150°C in dynamic mechanical tests. The extensive curing reaction yields a high crosslink density polymer network, resulting in good moisture resistance (<0.2% after 14 days in 85°C/85%RH) and thermal stability (<0.3 wt % at 300 °C of the cured material). The extent of cure has been studied in a dynamic scanning calorimeter (DSC) by following the extent of post‐cure exotherm. Both in the accelerated and non‐accelerated systems, the curing is complete in a single step with no post curing required. Cure cycles used range from 1 hour at 140°C to about 1 minute at 170°C. Currently, cure stresses, fracture toughness (bulk and interfacial), fatigue life, and various reliability tests are being performed to characterise the underfill, glob top encapsulants, and die‐attach adhesives.

Citation

Ghoshal, R., Sambasivam, M. and Mukerji, P.K. (1997), "Novel Epoxy‐based Compositions for Microelectronics Packaging Applications: Part I", Microelectronics International, Vol. 14 No. 3, pp. 12-14(continued on page 18). https://doi.org/10.1108/13565369710195261