Microporous Low-Dielectric Constant Polymers for IC Packaging

Foster Miller proposes to apply a proprietary supermicrocellular foam technology to develop a nanoporous, low-dielectric constant polymer for use in a wide variety of IC packaging applications. Foster-Miller has demonstrated that closed cell foams with densities as low as 10% of the unfoamed polymer can be easily fabricated with this technology. The dielectric constant of a polymer such as a polyimide can be reduced from about 3.5 to a value as low as 1.25 with concomitant reductions in dielectric loss and mass density. Compared to other approaches which result in open cell structures, the closed cell foam minimizes entrapment of solvents and other chemicals used in the processing. In Phase I, Foster Miller will work with its commercialization partner, Axiomatics, Inc. to fabricate a polymer with good mechanical properties and a dielectric constant below 2.0 using the microcellular foam technology. The dielectric properties will be characterized from dc to 40 GHz. Techniques to convert the foamed polymer into useful product such as multilayer printed wiring boards, multichip modules and PCMCIA cards will be developed. In Phase II, we will fabricate and test prototype units and scale up the foaming process to produce continuous rolls of film. Most high speed and high density electronic systems will benefit from this development. Availability of a light weight polymer with a lower dielectric constant and better mechanical properties than Teflon will revolutionize the electronic packaging industry. Portable personal communication and computing devices, and avionics and space electronic systems will be the primary beneficiaries of this development.