The influence of Cr-based coating on the adhesion force between epoxy molding compounds and IC encapsulation mold

The surface properties of IC encapsulation molds such as anti-sticking, wear and corrosion resistances can be improved by hard surface coating. The unbalanced magnetron sputtering method is used to deposit Cr, Cr2N, and CrN phase individual. Of the three coatings, the Cr2N coating has the lowest surface energy and the highest contact angle of water, which reaches as high as 120°. High water-repellency of Cr2N coating is due to the CH groups on the film surface, and the N–H or O–H bonds are found to be the effective adsorption sites for carbon substances. The experimental results also show the correlation of coating's surface energy and its adhesion force with EMC. Performance evaluation showed that the Cr2N coating could increase the number of molding injections in the IC package production lines by 50%.