Due to the singulation and soldering processes required during package assembly, device warpage after molding is a critical issue for array packages. Warpage is greatly affected by package geometries, such as dimensions of the matrix block, pad, die, and passive components, as well as the molding compound properties. One set of molding compound properties may generate very low warpage in one array package, but unacceptable warpage in another. To achieve minimum warpage in all geometry variations, molding compound properties have to be tuned for each package. For this paper, modifications to a successful molding compound A (MC A) were performed systematically. The curing shrinkage and Tg of the molding compounds were adjusted, while other major properties kept consistent. Warpage of array blocks/strips built with modified molding compounds was measured by a shadow Moiré method to correlate warpage with molding compound properties. Finite element analysis (FEA) was performed to predict and correlate the effects of mold compound properties on warpage. Read the full article (PDF)...

This article was taken from Global SMT & Packaging Vol. 7 No. 1 - January 2007