Substrate for use in semiconductor packaging

Abstract

A number of techniques and substrate arrangements are described that working individually and in common have been found to significantly improve the environmental resistance of the resulting package. In one aspect, conductive pads (referred to herein as landing pads) on the top surface of a substrate are slightly undercut. This permits molding material applied during later packaging to flow into the undercut regions to help improve adhesion between the substrate and the molding material. In another aspect, metallic die attach pads formed on the substrate are patterned to provide better adhesion between the substrate and a solder mask that covers the die attach pads. More specifically, the metallic die attach pads are patterned to have a number of opening defined therein that leave corresponding portions of the substrate exposed. In substrates where a solder mask is applied over the die attach pad, the openings permit the solder mask to adhere directly to the substrate panel in the openings thereby strengthening the attachment of the solder mask to the substrate. In still another aspect, elongated slots are provided in the solder mask such that the slots expose one or more rows of adjacent landing pads instead of simply the landing pads themselves. With this arrangement, some substrate material between adjacent landing pads is exposed which tends to improve the adhesion of molding material to the substrate.