Influence of Au film thickness on surface morphology and properties of substrate with Ni/Au microcones

Substrates with Ni/Au microcones has been proved to be beneficial for wire bonding. In this work, we discussed the influence of Au film thickness on surface morphology and properties of substrate with Ni/Au microcones. The morphology of the surface structure evolves from microcones to spheres by increasing the Au film thickness. Micro hardness test showed that thicker Au film makes the Ni/Au substrate softer, which increased wire bonding capability. Electrochemical analysis demonstrate that the anti-corrosion ability of the substrate improved as the increase of Au film thickness. Wire pull test showed that thicker Au film leads to lower pull and shear strength of 1st bonding. All considered, Ni/Au substrates with 0.05um Au film were the most appropriate for gold wire bonding.