TAB implementation: a military user´s viewpoint

The uses of tape automated bonding (TAB) at Hughes Aircraft Company are reviewed. It is noted that TAB design and manufacture is currently troubled by nonstandardization issues and technology issues. Hughes has learned that the existing ASIC and memory chips are not compatible with TAB standards. Reconciliation of ILB (inner lead bond) footprints is an IC design interface, OLB (outer lead bond) is where the preliminary JEDEC standardization has begun, and the testpad socket interfacing is a third independent variable not yet resolved. A liaison with TAB vendors led to the conclusion that single-chip packaging uses of TAB are being marginally served, but that multichip module (MCM) uses are handicapped by material and process shortcomings. Rework considerations caused Hughes to request a nickel barrier metal between copper and gold layers. Current experience in attempting to define and evaluate tools necessary to support development of high-density MCM is reported. A list of the Hughes recommendations for the use of TAB and the standards that Hughes believes to be necessary for making the TAB process acceptable is presented