Copper wire interconnect is gaining momentum in mass production at rapid speed as the industry continue to mature into more robust copper wire bond process capability and at the same time has realized its cost benefits over gold wire interconnect. QFN has been in mass production for longer period in industry to support trend towards smaller packaging technologies, replacing other lead frame base or even substrate base packaging solution at rapid speed. This paper discusses the holistic packaging solution approach towards developing copper wire bond on QFN, including the issues and challenges encountered during the development and implementation phases. It covers the process optimization based on various popular wafer fabrication metal structures in the industry, special consideration on factors affecting bond pad integrity, and impact of various lead frame surface finishes, and the implementation of process control to provide robust wire bond, and higher packaging reliability requirement for copper wire bond.
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