X-ray analysis of the package cracking during reflow soldering

Abstract

A new X-ray system tests cracking in QFP (quad flat pack) and SOJ, (small outline J-leaded pack) packages. It has been found that package cracking starts in two regions of delamination: (1) between the die pad and the chip, in the case of newly developed resins; and (2) between the die pad and the resin, in the case of older forms of resin. During experimentation, it was found that cracking in SOJ related to the newer resin is caused by vaporization of moisture in the materials attached to the die pad. This was verified through simulation.<>