Exceptional performance from the development, qualification and implementation of a silicone adhesive for bonding heatsinks to semiconductor packages

The stress induced by the Coefficient of Thermal Expansion (CTE) mismatch of ceramic semiconductor packages bonded to aluminum heatsinks created a high risk of cracking. As packages increase in size and power, the need for an advanced adhesive with compliant properties, reliable bond strengths and high thermal performance is required. The demand for high speed semiconductor CPU's in today's marketplace created a requirement for an effective, low-cost thermal management solution for packaging. This paper describes the methodology and analysis used to develop, qualify, and implement a new heatsink adhesive attach strategy into manufacturing. Included are the resultant benefits and potential applications for future product designs using this Low Modulus Adhesive (LMA). The project goal was to "Implement LMA into manufacturing for all permanent heatsink attach products". This included both current and future products, with the heatsink attach strategy of "low volume, high mix" product capability. As a result of the work reported here, heatsink attach capabilities have been enhanced significantly with attractive cost benefits. Concurrent engineering was emphasized to deliver a high quality and low-cost process to production in a timely manner. The material, process, and equipment has been running in a low volume production facility with 100% yield. This technology is planned for transfer to a high volume production facility.<
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