Integrated Taguchi method and neural network analysis of physical profiling in the wirebonding process

In this paper, an analytical linkage-spring model has been modified to determine the design rules for reducing the loop height and the sagging altitude of gold wirebonding process of the integrated circuit (IC) package. New model enables to simulate the profile of capillary trajectory from the first to the second bond stages. Traditionally, the finite element model is the most powerful tool in stress analysis, however, it could be very sophisticated in analyzing the large deformation and large displacement problems. In contrast, the modified linkage-spring model is more convenient and simple to implement for characterizing multiple parameters in defining the looping profile using the integrated Taguchi method and the neural network analysis. According to the factors and levels of complexity in the wirebonding process, an optimum design of the low loop height and the low sagging altitude in terms of the triangle-shaped or T-shaped of profiles can be manipulated by the Taguchi method. Analysis results have predicted that the reverse position and the reverse angle play an important role on the loop height control, and the trajectory path is a key factor to defining the sagging altitude. The artificial neural network (ANN) model is also applied in this study to identify the proper parameters setting for the wirebond profiles. These forward and inverse network models can be trained for predicting the profiles. The accuracy of the analysis can be controlled in terms of root mean square (RMS) in the range less than 5%.