A Model for Deformation of Solder Bumps From Ramp Loading

A simple model is presented to predict the mechanical squashing or stretching of an axisymmetric solder joint when subjected to a ramp loading. This is a situation which can frequently arise, accidentally or by design, in the processing of flip chip solder bumps, or in surface mounted Ball Grid Array modules. Excessive squashing can have ramifications for subsequent processing or for joint reliability. The proposed method, while involving an extremely simple algorithm, has been found to agree well with experimental data, and is very general in its applicability.