The effects of die thickness and bond height on wire sweep in multi-chip module and 3-Dimennsional packages

In order to lower costs and improve functionality in a quick turn-around time, the module-in-systems, such as the multi-chip module (MCM) and 3-D packages, have been applied in the integrated circuits (ICs) industry. The wire bonding technology, providing versatile and reliable chip-connection method, is usually adopted for MCM and 3-D packages. Wire sweep, denotes visible wire deformation, typically a lateral movement in the direction of the compound flow through the cavity, is usually a main concern in the semiconductor packaging industry. Wire sweep can cause device shorting and/or current leakage leading to IC failure. Thus the influence of wire sweep becomes critical on semiconductor package. Wire sweep has been proved to be closely related to bond span and bond height of a wire bond. However, die thickness and bond height vary from chip to chip within MCM and 3-D packages. In the paper, an attempt is made to investigate the effects of die thickness and bond height of a wire bond on their wire sweep. The concept of sweep stiffness defined by the slope of the load-transverse displacement curves is employed in representing the sweep resistance of a wire bond. At the MCM level, four die thicknesses, 160, 200, 250 and 550mum, are tested and their sweep stiffness are then compared with numerical results.