Electrodeposited Ni microcones with a thin Au film bonded with Au wire

In wire bonding, the bonding quality between the substrate Au film and metal wire has an effect on productivity and reliability. Au film thickness is important for substrate bondability. It is required to reduce the Au film thickness as thin as possible without deteriorating the level of bondability to cut down extremely high cost of Au consumption. In this study, electrodeposited Ni/Au microcones were fabricated and thermosonic bonded with Au wire. The thickness of Au film was only 0.05 mu m. Bonded with Au wire 17.5 mu m in diameter, the 0.4 mu m-height microcones showed excellent and stable bondability with average pull strength 6.29 gf and small standard deviation. Microscopic observation showed that Ni/Au microcones inserted into Au wire effectively, thus insertion weld between microcones and Au wire was formed. Pull fracture scanning electron microscopy (SEM) images showed an improvement of stitch bonding quality when using Ni/Au microcones. Mechanism of bonding process between the Ni/Au microcones and Au wire was put forward by three stages. (C) 2013 Elsevier B.V. All rights reserved.