Developments in fine pitch copper wire bonding production

Abstract

Copper wire bonding has huge cost advantages over gold wire bonding. Wire bonding and materials companies have invested heavily in R&D in the last 2 or 3 years and are starting to see the fruits of their labor. Low pin count, heavy wire packages have already been converted to copper wire and many companies are in high volume production. An extensive amount of development activity has targeted high pin count (>200 I/O) and high performance applications. Recently this work has paid off, as there has been an increase in this market segment that has drastically exceeded earlier predictions by market analysts. What the recent research & development has done is to actually fill in the knowledge gaps for copper wire bonding. This knowledge has fueled technology development, which, in turn, has enabled the current transition to high volume fine pitch production. In this paper I will discuss some of the technology developments that have overcome the challenges and make recommendations for implementing copper wire bonding as a replacement for gold in high volume manufacturing of high pin count packages. Specific areas of technology development that I will cover are advancements in stable free air ball formation, designs and techniques to eliminate or control pad damage, developments in molding compounds, and copper reliability fundamentals.