Microcellular polysiloxane monoliths were prepared from the continuous phase of a concentrated inverse emulsion. The formulation of the material was adapted to obtain monoliths having structural properties similar to those of common poly(styrene‐co‐divinylbenzene) polyHIPEs. The network was generated by hydrosilylation reaction between a vinylsiloxane crosslinking agent and an oligomeric hydrogenosiloxane. The solids obtained were characterized by mercury porosimetry, nitrogen sorption, and SEM. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 21–32, 2008

Conventional inorganic adhesives such as silver-filled glass and Au-Si eutectic bonding are commonly used to attach Si chips to ceramic substrates in hermetic packages. One of the key requirements is low moisture content (less than 5 0 0 0 ppm) in order to prevent moisture-induced corrosion failures. Up to now, only the inorganic adhesives mentioned above have met this requirement. However, they also possess major drawbacks such as: * High temperature processing, typically * Lengthy cure for up to several hours * Au-Si eutectic is not suitable for high above 350 OC.for large die sizes. speed automation.A novel thermoset die-attach paste has been developed to meet this low moisture requirement. The paste is suitable for use on conventional dispensing equipment. This material can be cured in less than 60 seconds at 200 OC and does not generate any appreciable weight loss during cure. As a result, the same fast-cure profile can be used for a wide range of die sizes.In this paper, we will review the chemical and physical characteristics of the material along with its functional performance as a die-attach media. The combination of a glass transition temperature around 260 OC and high thermal stability up to 4 0 0 OC provides significant performance enhancement over conventional epoxies. In addition, the material exhibits high adhesive strength while imparting low stress on the die. Experimental results show that the moisture content in the cavity of a Au-Sn solder sealed ceramic package is less than 1000 ppm, well within Military Spec.. The low moisture characteristic is found to be an inherent property of the material. Reliability tests such as thermal cycling, high temperature storage have shown that the low moisture level is still maintained after 1000 cycles or 1000 hours at 150 OC.Results of thermal performance of the material on thermal test chips are discussed and compared to that of silver-filled glass.

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