A 3-DIMENSIONAL MODELING OF WIRE SWEEP INCORPORATING RESIN CURE

In this paper, a fully three-dimensional (3-D) model is introduced for the simulation of wire sweep during cavity filling in transfer moldin g of integrated circuit (TC) packages, This includes the composite-seg ment-functions method for defining spatial wirebond geometry, a singul arity numerical integration procedure for calculating flow-induced for ces on general 3-D wirebonds and a penalty finite element technique fo r simulating 3-D flow of molding compound in the mold cavity. The wire sweep of a 26-leaded IC package under various processing conditions w as investigated, The wirebond deformation was studied in terms of wire bond orientation, local velocity field, local temperature, degree of c ure, molding compound viscosity, etc, The effects of the process condi tions, such as curing time, transfer rate and molding temperature, on wire sweep were also investigated, The effect of the location of the g ate of the cavity was also studied and found to have a profound effect on the pattern of wire sweep.