Studies of underfill formulation effects using molecular dynamics and discrete element modeling

The underfill phenomenon is driven by many dynamic interactions which can be studied from a fundamental standpoint. Although capillary action generally drives the filling phenomenon, it is the underlying principles that govern the underfill performance properties which must be understood. For instance, flow speed, filler settling, filler striation and voiding are all properties that require mechanistic understanding. Although binder and filler effects are expected from a combination of surface energy and particle dynamics drivers, the simple identification of the problem does not instruct on how to control these effects; and for the formulator or the end-use engineer, such understanding must be reduced to controllable variables. In order to address these issues, both molecular modeling and discrete element modeling have been used to understand the formulation constituent effects