Development of Liquid Compression Molding (LCM) Material for Low Warpage

This paper reports on the study of flexible epoxy resin which lowers modulus to minimize warpage while maintaining high filler content. Liquid Compression Molding (LCM) material is an encapsulation material applied at the wafer level. LCM requires high reliability and minimized warpage after curing. The flexible epoxy resin was studied to determine if it could be technically feasible to meet the requirements. Three epoxy resins with different structures, Conventional epoxy, and Flexible epoxy A and B, were examined. Both samples with Flexible epoxy A and B resulted in lower warpage than Conventional resin. Especially, Flexible epoxy B showed the minimal warpage with the lowest modulus. The sample with Epoxy B performs the best at 260 degree Celsius with the minimal warpage. A reliability test of LCM with Epoxy B was also conducted assuming the application for Fan-out packaging. Epoxy B showed no delamination or cracks under a thermal cycling test up to 1,000 cycles after MSL1 moisture exposure.