Polymeric compositions having a temperature-stable dielectric constant

A polymeric composition having a temperature-stable dielectric constant, consisting essentially of:

• (a) a polymer having a dielectric constant K' in the range of about 1.5 to about 3.5 and a temperature coefficient of dielectric constant TCK' less than 0 but greater than about -300 ppm/degree C., wherein said polymer is selected from the group consisting of poly(phenylene sulfide), cycloolefinic copolymer, and mixtures thereof,
• (b) a first ceramic, consisting of one or more ceramics selected from the group consisting of calcium zirconate, strontium zirconate, CaTiSiO.sub.5,PbZrO.sub.3. zirconia and mixtures thereof, each having a dielectric constant in the range of about 15 to about 200 and a TCK' greater than zero up to about 3000 ppm/degree C.;
• and
• (c) an optional second ceramic, consisting of one or more ceramics selected from the group consisting of aluminum oxide, magnesium titanate, mica, silicon dioxide, beryllia, spinel, and thoria, each having a dielectric constant in the range of about 3 to about 15 and a TCK' greater than zero up to about 300 ppm/degree C.;
• wherein the amounts of said polymer and said first and second ceramics are balanced so that the dielectric constant of the composition is greater than 4 and the dielectric constant of said composition varies by no more than 2% above or below the mean value of the dielectric constant in the temperature range from -50.degree. C. to a higher temperature that is the lesser of 80.degree. C. and 10.degree. C. less than the glass transition temperature of said polymeric composition;
• wherein said values of K' and TCK are measured at 2.0 GHz frequency, and said value of K' is measured at 20.degree. C.