Wire bonding-towards 6- sigma yield and fine pitch

The problems as well as the solutions required to wire bond high lead count chips to their packages at the required high yields are described. The elements for achieving 6- sigma wire bond yields are the choice of metallization on the chip as well as on the package; an appropriate cleaning procedure (which in some circumstances may be at the wafer level) and/or special storage and shipping containers; factorial bonder setup and proper bond test methods uniform, reproducible wire and bonding machine characteristics; and both the chip bond pads and the package pads designed with full awareness of the limitations and tolerances of the chosen bonder and its bonding method. Wafer testing probe cards currently limit the minimum wire bond pad pitch on high end devices to about 100 mu m. However, 75- mu m pitch wedge bonding can be performed with current (modified) autobonders, and 40- mu m pitch bonding has been reported.<
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