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Die products provide the ultimate opportunity for size and weight reduction, electrical performance improvements, enhanced function integration and reduced costs in system design. A die product is simply a package-free semiconductor, thus allowing the system designer to take advantage of the true device performance not encumbered by the penalties resulting from the package.
National Semiconductor offers unpackaged die for Chip on Board (COB) wire bond applications.
The COB die implementation utilizes our standard bond pad metalization and die surface passivation. The interconnects are located on the periphery of the device. Exact location and size of the bondable surface along with the surface metallurgy are defined on the Die Product datasheet. Interconnect methods for COB wire bonding include gold-ball bonding and aluminum wedge bonding. Gold-ball bonding is a high throughput, high strength technology that allows for bonding of fine pitch bond pads. It does require an elevated temperature to bond and the gold wire results in higher material costs than aluminum wedge. Process consideration must be given to the set up conditions, wire diameter, wire length, metallurgy and surface conditions. Aluminum wedge bonding can be processed at room temperature and utilizes lower cost wire. Lower bond strength and lower throughput can be expected. Additional process consideration should be given to wire bond angles and forward/reverse bonding effects.
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