High frequency conductive material and resonator and method for making
AssigneeTDK Corporation
InventorsKeizou Kawamura, Makoto Kobayashi
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Abstract
Glass, an oxide aggregate with a positive .tau..epsilon. and an oxide aggregate with a negative .tau..epsilon. are mixed in a prescribed ratio by volume so as to bring the .tau..epsilon. of a high-frequency dielectric material close to -12 ppm/.degree.C. and bring the resonant frequency temperature coefficient .tau.f of a high-frequency resonator near zero.
Claims11
A high-frequency dielectric material comprising 50-80% by volume glass, and 50-20% by volume of a mixture of an oxide with a positive dielectric constant temperature coefficient .tau..epsilon. and an oxide with a negative dielectric constant temperature coefficient .tau..epsilon., wherein said glass has the following composition:
- SiO.sub.2 :
- 50-70 mol %
- Al.sub.2 O.sub.3 :
- 5-20 mol %
- B.sub.2 O.sub.3 :
- 0-10 mol %
- one or more alkaline earth metal oxides:
- 25-45 mol %
- and wherein the oxide with a positive .tau..epsilon. is one or both of aluminum oxide and magnesium titanate and the oxide with a negative .tau..epsilon. is one or more of calcium titanate, strontium titanate and titanium oxide, but wherein aluminum oxide and titanium oxide are not both present in said material.
A method of producing a resonator comprising the steps of:
- providing glass having a dielectric constant temperature coefficient .tau..epsilon. at 2 GHz, -40.degree.-125.degree. C. of 150-170 ppm/.degree.C. and a mean coefficient of thermal expansion at 40.degree.-290.degree. C. of 5.5-6.5.times.10.sup.-6 deg.sup.-1, aluminum oxide and titanium oxide,
- mixing said glass, aluminum oxide and titanium oxide together to obtain a high-frequency dielectric material wherein the amount of glass/(glass+oxide) is 50-80% by volume and the amount of titanium oxide/(titanium oxide+aluminum oxide) is 40-60% by volume, and
- forming a laminate of dielectric layers having a dielectric constant temperature coefficient .tau..epsilon. of -40-+20 ppm/.degree.C. with said high-frequency dielectric material, forming a strip line of conductive material in the laminate, and sintering the result to obtain a resonator.
Dependencies are inferred from the claim text.