carbide diamond graphite beryllium oxide magnesia silica alumina zirconium silicate and the like preferably the particle size of these fillers will be about 20 microns if aluminum nitride is used as a filler it is preferred that it be passivated via an adherent conformal coating e g silica or the like thermally conductive fillers are optionally and preferably rendered substantially free of catalytically active metal ions by treatment with chelating agents reducing agents nonionic lubricating agents or mixtures of such agents such treatment is described in u s pat no 5 447 988 which is incorporated by reference herein in its entirety optionally a filler may be used that is not a thermal conductor such fillers may be desirable to impart some other property to the adhesive formulation such as for example reduced thermal expansion of the cured adhesive reduced dielectric constant improved toughness increased hydrophobicity and the like examples of such fillers include perfluorinated hydrocarbon polymers i e teflon u2122 thermoplastic polymers thermoplastic elastomers mica fumed silica fused silica glass powder and the like invention compositions optionally include one or more additional components such as flexibilizers anti oxidants dyes pigments surfactants defoamers silane coupling agents dispersing agents thixotropic agents processing aids flow modifiers cure accelerators strength enhancers toughening agents.