10 mils Al wire heavy wedge bond wire deformation thickness study

Power device that require Al wire to carry large currents are widely used in for automotive electronics. Al wire bonding is one of key process for these products. Al wire deformation thickness should be a challenge for Al wedge bonding. As the wedge lifetime increased, Al debris will build up as a sharp tip on the wedge surface. When it grows larger than wire deformation thickness, it can damage the die surface during wedge bonding resulting in potential risk of leakage. Wire deformation thickness should be controlled to be thick enough to protect the die surface. In this study, 10 mil Al wire wedge bonding was investigated with wire deformation thickness and wire shear on die as the key challenge. The Wafer technology used in the study is LFET with 3.6 um metal thickness. The die was packaged into a 32LD package. 10 mil Al wire was wedge bonded on the die surface. Al wedge bond process parameter optimization was discussed in the paper. Al debris shape were investigated. Wire Deformation and Wire Shear on Die were tested after parameter optimization. It was concluded that wire guider dimension caused the wire deformation thickness variation resulting in different damage on wire surface. The parameter optimization found that 2nd bond influences the 1st bond performance. The 1st bond deformation was separated into 2 parts. Cutting phase after 2nd bond phase formed a pre-deformation part. The cutting parameters were optimized to decrease the pre-deformation resulting in better wire deformation thickness consistency.