Open AccessA Numerical Study on Mitigation of Flying Dies in Compression Molding of Microelectronic Packages
Author(s) -
Marc Dreissigacker,
Ole Hoelck,
J. Bauer,
Tanja Braun,
KarlFriedrich Becker,
Martin Schneider-Ramelow,
KlausDieter Lang
Publication year - 2019
Publication title -
journal of microelectronics and electronic packaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.192
H-Index - 17
eISSN - 1555-8037
pISSN - 1551-4897
DOI - 10.4071/imaps.763387
Subject(s) - microelectronics , drag , molding (decorative) , compression molding , mechanical engineering , materials science , flip chip , transfer molding , dice , engineering drawing , engineering , composite material , adhesive , electrical engineering , aerospace engineering , mold , geometry , mathematics , layer (electronics)
Compression molding with liquid encapsulants is a crucial process in microelectronic packaging. Material properties of highly filled systems of reactive epoxy molding compounds depend on process conditions in a complex manner, such as shear-thinning behavior, which is superimposed by a time- and temperature-dependent conversion rate, both strongly affecting viscosity. The focus is set on forces exerted on individual dice during encapsulation in fan-out wafer-level packaging (FOWLP). The presented framework consists of an analytical approach to calculate the melt front velocity and simulations carried out to capture the nonlinear kinematics, chemorheology, and to extract forces exerted on individual dice. It offers separate evaluation of pressure and shear contributions for two cases, 0° and 45° between the dice' frontal area and the melt front. Process parameters, such as compression speed, thus cycle time, and process temperature, are determined to keep the forces on the dice below the critical level, where drag forces exceed adhesive forces. As a result, process parameters are determined to minimize flying dice and thereby maximize yield. The approach is easily transferable to arbitrary geometries and is therefore well suited to face the challenges that come with the current efforts toward the transition from FOWLP to larger substrates.