A tin based TAB assembly process

The feasibility of using a TinCap TAB (tape automated bonding) ILB (inner lead bond) structure to provide a strong ILB connection has been demonstrated. The project investigated placing a pad of tin on top of a gold TAB bump as part of the wafer fabrication process. The tin is then used to form a reflowed ILB joint with a gold-plated tape lead. This gold/tin bond should provide a strong joint while avoiding some of the problems associated with tin-plated TAB tape. This TAB bond is referred to as the TinCap ILB structure. The process development work included modifications to the current TAB photoresist imaging process, development of a tin plating capability, and formulation of a suitable etch chemistry for a tin/gold bump. An inner lead bonding process was developed through evaluating and testing of two separate bonding systems. A substantial reliability evaluation involving over 200 live devices was carried out to determine the suitability of this interconnect for future products.<
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