Tape automated bonding technology developments at MCC

Summary form only given. MCC´s research achievements in TAB (tape automated bonding) focus on TAB for high-lead-count/high-performance applications. Recent developments are in the areas of wafer bumping, tape design, inner- and outer-lead gang bonding, chip-on-tape testing, encapsulation, and burn-in techniques. MCC has developed a `flip-TAB´ or face-down TAB technology for an inner-lead bonding (ILB) minimum pitch of 100 μm. Wafers are bumped with straight wall gold bumps 25-μm high and 50-μm wide on 100-μm (4-mil) centers. A thick resist plating process is used to produce a wall 85° to 87°, and 20-μm thick. For ILB, thermosonic bonding is used for connecting gold-plated tape to the gold bumps. Eutectic bonding of tin-plated tape to the gold bump has also been investigated. In the area of outer-lead bonding, developments include a mass bonding method using solder reflow. Both tin- and gold-plated tapes and various solder and flux types have been investigated. Investigations of wafer passivation have been conducted, and an encapsulation process for coating ILB devices in tape form has been developed. A resin coating with improved wafer passivation has been found to provide a good alternative to plastic molded package devices