Ball grid array semiconductor package

Claim 1

A ball grid array semiconductor package, consisting of: an insulative base material in the form of a flexible film or sheet; circuitry metallizations formed on a first surface of the insulative base material, each circuitry metallization having a grid pad electrode on said first surface of the base material, wherein the metallizations are in the form of a single-sided copper clad laminate on the insulative base material and said grid pad electrodes are patterned-etched grid pad electrodes; a semiconductor chip mounted on said first surface of the insulative base material juxtaposed to said circuitry metallizations and in substantially the same plane as said circuitry metallizations and electrically connected to said circuitry metallizations; a rigid, resin envelope molded over substantially all of said first surface of said insulative base material and encapsulating said semiconductor chip such that no flexible portion of said base material is left peripherally exposed thereby; wherein the insulative base material is open from an opposite second surface of the insulative base material to the first surface of the insulative base material to form an opening through said insulative base material and at a location under each grid pad electrode; a solder ball in each of said openings in a melt-fixed connection to a back side of each grid pad electrode; and wherein each opening without the need of a solder mask confines a portion of each solder ball which is in the melt-fixed connection to a back side of each grid pad electrode facing the second surface of the insulative base material.