Reducing Top-of-Die Plastic Delamination by Assuring Pre-Mold Cleanliness of Die Surfaces

Delamination of mold compound from top-of-die surfaces in plastic encapsulated microcircuits (PEMs) can alter overall package stresses and cause wire bond or other types of mechanical failure. Liquid water may collect in these delaminated regions and cause metal corrosion. Exceedingly small quantities, even fractions of a monolayer, of adsorbed contamination on die may hinder intimate adhesion of the mold compound to the die surface and cause plastic to delaminate. This paper discusses the consequences of top-of-die delamination (TODD), surface contamination derived from wafer tape mounting that can cause it, and cleaning chemistry to remove surface contaminants in order to minimize it.