Patent ID: 7153724

Claim:
A process of fabricating semiconductor packages comprising: providing a metal sheet; forming a first mask layer on a first surface of the metal sheet; patterning the first mask layer to form a plurality of first openings and a plurality of second openings; forming a second mask layer on a second surface of the metal sheet; patterning the second mask layer to form a plurality of third openings and a plurality of fourth openings, wherein each of the second openings is vertically aligned with one of the fourth openings, a vertical projection of each second opening lying entirely within one of the fourth openings, the edges of said each second opening being laterally offset with respect to the edges of said one of said fourth openings; etching the metal sheet through the first, second, third and fourth openings simultaneously to form a plurality of locking grooves aligned with the first openings, a plurality of first separation grooves aligned with the second openings, a plurality of singulation grooves aligned with the third openings, and a plurality of second separation grooves aligned with the fourth openings, the first separation grooves being aligned with the second separation grooves such that during the etching the first and second separation grooves merge and thereby form a plurality of die pads and a plurality of contact elements, the locking grooves being located in the contact elements; removing remaining portions of the first and second mask layers; attaching a semiconductor die to each of the die pads; forming a layer of molding compound on the dice and the metal sheet, the molding compound flowing into the locking grooves and the singulation grooves; and sawing the metal sheet and the molding compound so as to form a plurality of semiconductor packages, the sawing comprising making a series of saw cuts, each of the saw cuts being made at a location such that a kerf of the saw cut extends into at least a portion of one or more of the singulation grooves, the saw cuts separating each of the contact elements into a pair of contacts.