Methods for plastic injection molding, with particular applicability in facilitating use of high density lead frames

Abstract

A lead frame assembly includes one or more lead frames each defining a plurality of package locations organized in rows and columns. An injection molding system includes a plurality of culls, each cull being connected to the frame(s) through a plurality of subrunners. Each subrunner delivers molding compound from one of the culls to a respective column of package locations. A plurality of through gates are disposed between adjacent package locations within each column, each through gate supplying molding compound from one package location to a next adjacent package location within the column, each package location being filled with molding compound in turn from the preceding package location. The need for subrunners between adjacent columns of package locations is eliminated, allowing a higher density of package locations within the lead frame(s), reducing materials and labor costs, and increasing manufacturing productivity.

Dependencies are inferred from the claim text.