Large Area Encapsulation: Solid Type Epoxy Molding Compound

A Liquid epoxy molding compound (LMC) is a main package material in Fan Out Wafer Level Package due to liquid's powderless property which fits to a clean room environment. As the trend of FOWLP is moving toward the larger panel size to increase the number of packages and reduce the cost, the limitations of LMCs become concerned, however [1-4]. The first limit of LMCs is the molding inhomogeneity and surface un-uniformity caused by materials dispensing and a long flow distance. Various dispensing patterns including center dotting, spiral dotting, and multi dotting, have been devised, but none of all the methods are appropriate to cover up large panel encapsulation. The second limit is a warpage control. Warpage control in large area encapsulation has generally been accepted as more difficult because of higher sensitivity toward the shrinkage difference between a carrier wafer and LMC. Higher filler loading is necessary to achieve low shrinkage and warpage. But, the filler loading of LMCs is relatively lower than that of solid type epoxy molding compounds due to maintaining their liquid state. As a result, there have been many research efforts to seek an alternative encapsulation material to overcome LMCs' limitation [4]. Herein, we present an alternative solid type epoxy molding compound which is suitable for a large area panel package. This epoxy molding compound resolves the dispersion problem in the large area encapsulation. Additionally, implementation of new resin and hardener system enables to achieve both high filler loading up to 95% and low temperature mold cure at below 110°C. High filler loading leads to modulus and CTE drop. In addition, low curing temperature reduces shrinkage and thermal stress. Both factors help to control the warpage for large area encapsulation [5].