Plasma considerations prior to wire bonding in advanced packaging

Today's packaging engineers are faced with many challenges, including cost-saving strategies, yield-enhancing process steps, and damage-free preparation of intricate, small geometry devices such as multi-chip modules, stacked packages and hybrids. In order to ensure high device reliability and minimize manufacturing costs, a well-prepared surface for wire bonding plays a very important role in successful advanced packaging since it can significantly improve the quality and reliability of the bond. Gas plasma technology can be used to clean pads prior to wire bonding to improve bond strengths and yields. It is a powerful, efficient resource for surface preparation that can dramatically improve the manufacturability, reliability, and yield of advanced packages. In this paper, the types of plasma technologies and consideration for their use prior to wire bonding are discussed, and experimental results are reviewed. Examples specific to epoxy bleed-out contamination and considerations regarding substrate material and device characteristics are also addressed.