Development of crack-free plastic package: Evaluation of high reliability of CSS (chip side support) structure

Package cracking during reflow soldering is a critical issue for the reliability of plastic encapsulated semiconductor devices. In the case of a conventional package structure, the adhesion strength at the interface between the metal die-pad and the resin drops rapidly for high temperature and humidity. This is a major cause of package cracking. So, a new packaging structure, the chip side support (CSS) structure was introduced. The reliability of the CSS structure package was evaluated by executing the adhesion strength measurement of the interface in the packages, reflow soldering test, temperature cycle test (TCT) and high humidity storage test. The results of these tests indicated that the CSS structure package was superior to conventional packages. The CSS structure package realizes a crack-free package without moisture-proof packing by dispensing with the die-pad and adopting a thinner package thickness.