Abstract: A plastic pin grid array package is detailed. Where the semiconductor device is mounted within a cavity in the printed wiring board, it is surrounded by a ring of holes that extend completely through the board. When the plastic housing is transfer molded around the face of the board, plastic will enter the holes thereby forming plastic pillars that lock the encapsulant to the board mechanically. When the package is flexed, the pillars will prevent any motion between the encapsulant and the board or the semiconductor device mounted thereupon. The invention can be applied to single or multichip packages. It can be employed in any package that is based upon a printed wiring board substrate.