Abstract
A practical method for predicting gold-wire deformation during the transfer molding process of semiconductor devices has been developed. In this study, common parameters for estimating values of wire deformation of the BGA (Ball Grid Array) package and the QFP (Quad Flat Package) used in previous reports were investigated. First, we examined the parameter λ, which was already derived as a function of resin velocity component perpendicular to the center of each wire, resin flow time at the center of each wire, apparent resin viscosity in the mold cavity, gold wire dimensions such as loop height, actual length and diameter, and Young's modulus for the gold wire. In the case of the BGA package, the maximum horizontal displacement, δmax, was found to be a linear function of λ up to around δmax=0.4mm with an intersection at the origin of the coordinate axes, On the other hand, for the QFP, a deviation from linearing was found for δmax exceeding 0.16mm. Next, both δmax and λ were divided by the actual length of each gold wire, and these values were defined as new parameters ζ and φ, respectively. By introducing these parameters, all the data were found to fit well by a straight line up to around ζ=8% with a subsequent a saturation curve. Three empirical models to represent the relationship between ζ and φ were obtained. Using these models, values of ζ were accurately calculated.
