1998 Volume 41 Issue 4 Pages 532-538
In the case of ball bonding process in LSI packaging, complex non-steady-state metal flow occurs in a wire ball during the process, and solid-phase bonding is accomplished between the wire ball and an electrode pad. We proposed a physical simulation method to analyze the above ball bonding process. The physical ball bonding simulation and detailed numerical analyses, using enlarged plane-strain models of a capillary tool made of SKD-61 steel and the wire ball and the electrode pad made of 1050 aluminum, were carried out. The outer profile change of the wire ball and the changes in and distributions of flow velocity, strain rate and strain in the wire ball during the process were revealed quantitatively. The simulation method will aid in the optimization procedures for tool configuration and other operating conditions, in order to achieve sound bonding with narrow electrode pad pitch spacing.