Thermally and Electrically Conductive Adhesives for the F-22 Subarray Assembly

The issue to be addressed by the proposed effort is adhesive failure in critical components of the Air Force's F-22 radar system. The high density of these subarrays creates very demanding thermal swings, which challenge the integrity of the adhesivesbeing used currently. Failures are occurring at unacceptably high rates. TRI/Austin, working with Auburn University, proposes to correct this problem by developing an adhesive that exhibits very high thermal stability that is filled with a material thatexhibits both high thermal and high electrical conductivity. We will use a combination of theoretical and practical modeling to predict and enhance adhesive performance. Systematic experimental designs will be used to cost effectively obtain an optimumcomposition. This will be based upon iterative tests of adhesive strength and durability after exposure to extreme thermal cycles. At the same time Auburn University will measure thermal conductivity and design and construct a laminated, multi-materialmodel to mimic thermal performance in the subarray. A number of instrumental methods will be used at both facilities including microscopy, infrared spectroscopy, and differential scanning calorimetry to characterize adhesive failure modes. We believe theproposed approach and assembled research team will to solve the F-22's radar problem quickly and efficiently.The immediate benefit of this development work to the Air Force will be the delivery of a high performance adhesive that eliminates bondingfailures in the F-22 radar subarrays. The electronics, telecommunications and aerospace industries all have need for adhesives that exhibit performance beyond the best epoxies, urethanes and acrylics. Demanding swings in temperature in space can causepremature failures in critical or expensive systems. At the very least, they can become a limiting factor in the life of a satellite, transport vehicle or space station. The ability to tailor adhesives for significant improvements in thermal orelectrical conductivity, or both, takes the adhesive beyond just a structural material. It now becomes integral to circuit performance and heat dissipation. The state of the art in microprocessor spped and density is limited by the issue of heat removal.If this can be adequately addressed, computing power will continue to improve at reduced cost.