Design in triangle-profiles and T-profiles of a wirebond using a linkage-spring model

Different profiles of a wirebond utilizing a linkage-spring model are proposed in this paper, and loop heights are minimized in order to prevent wire sweep during molding. To analyze loop profiles, a nonquantitative, time-consuming, experimental statistical method was applied in previous studies. Although the finite element model is the most powerful tool in stress analysis, it is more complex in analyzing a large deformation as compared to the linkage-spring model. The purpose of this paper is to simulate the capillary trajectory from the first bond to the second bond stages by a linkage-spring model developed by Lo, and then to discover the proper wirebond trajectories. To meet with the gold wire properties, the transient temperature distribution along the gold wire during the bonding process is considered, Accordingly, the spring constants in a linkage-spring model are modified along the wire. Furthermore, the design rules in the looping process are defined and four examples of triangle- and T-profiles of a wirebond are also presented.