Fine pitch wire bonding development using statistical design of experiment

Response Surface Methodology was used to characterize a wire bond system for fine pad pitch application. Ball shear stress, defined as ball shear force per unit area, was proposed as a better parameter over ball shear force for wire bond optimization. 3D chart arrays were presented for overall visualization of the characteristics of the response surfaces. Contour chart arrays were used for quantifying each response in terms of bond parameters. To optimize for the “ideal” fine pitch wire bond, it is recommended to use contour charts to locate bonding windows that can produce the best ball shear stress, or the best possible ball shear stress when under additional dimensional, material, or process constraints