A simple model for the Mode I popcorn effect for IC packages with copper leadframe

A simple model for the Mode I popcorn effect is presented here for packages with rectangular die pads (P-DSO). A package "stability parameter," relating to its moisture sensitivity, is derived from the popcorn model. It describes the critical factors for a robust package-molding compound properties and package, leadframe design for a given preconditioning and soldering process. Furthermore, nomograms generated from the model facilitate an easy estimation of moisture sensitivity levels (between 1 and 5) of packages with different die pad sizes and molding compound underpad thicknesses and for different soldering temperatures ranging from 220/spl deg/C to 260/spl deg/C (lead-free soldering).