Method of manufacturing low temperature sintered ceramic materials for use in solid dielectric capacitors or the like

Claim 2

A process for the fabrication of coherently bonded bodies of a low temperature sintered ceramic material, for particular use as the dielectric bodies of capacitors, which comprises: forming green bodies of desired shape and size from a mixture of 100 parts by weight of Ba k-x M x O k TiO 2 in finely divided form, where M is at least either of magnesium and zinc and where k is a numeral in the range of 1.00 to 1.04 and x a numeral in the range of 0.02 to 0.05, and 0.2 to 10.0 parts by weight of an additive in finely divided form consisting essentially of 25 to 50 mole percent lithium oxide and 50 to 75 mole percent silicon dioxide for providing upon firing coherently bonded dielectric bodies with a specific dielectric constant in excess of 2000, dielectric losses of less than 2.5 percent, resistivity of over 1×10 6 megohm-centimeters and capacitance temperature dependence of + or -10% in a temperature range of -25° to +85° C.; sintering the green bodies to maturity in a nonoxidative atmosphere at a temperature not to exceed 1300° C.; and reheating the sintered bodies in an oxidative atmosphere at a temperature lower than said preceding sintering temperature.

Claim 3

A process for the fabrication of coherently bonded bodies of a low temperature sintered ceramic material, for particular use as the dielectric bodies of capacitors, which comprises: forming green bodies of desired shape and size from a mixture of 100 parts by weight of Ba k-x M x O k TiO 2 in finely divided form, where M is at least either of magnesium and zinc and where k is a numeral in the range of 1.00 to 1.04 and x a numeral in the range of 0.02 to 0.05, and 0.2 to 10.0 parts by weight of an additive in finely divided form consisting essentially of lithium oxide and silicon dioxide and a metal oxide selected from the group consisting of barium oxide, calcium oxide, strontium oxide, and combinations thereof, wherein the range of the relative proportions of lithium oxide, silicon dioxide, and the selected metal oxide constituting the additive is in that region of the tenary diagram of FIG. 4 attached hereto which is bounded by the lines sequentially connecting: the point A where the additive consists of 5 mole percent lithium oxide, 70 mole percent silicon dioxide, and 25 mole percent metal oxide; the point B where the additive consists of 10 mole percent lithium oxide, 50 mole percent silicon dioxide, and 40 mole percent metal oxide; the point C where the additive consists of 49 mole percent lithium oxide, 50 mole percent silicon dioxide, and one mole percent metal oxide; and the point D where the additive consists of 24 mole percent lithium oxide, 75 mole percent silicon dioxide, and one mole percent metal oxide; for providing upon firing coherently bonded dielectric bodies with a specific dielectric constant in excess of 2000, dielectric losses of less than 2.5 percent, resistivity of over 1×10 6 megohm-centimeters and capacitance temperature dependence of + or -10% in a temperature range of -25° to +85° C.; sintering the green bodies to maturity in a nonoxidative atmosphere at a temperature not to exceed 1300° C.; and reheating the sintered bodies in an oxidative atmosphere at a temperature lower than said preceding sintering temperature.

Claim 4

A process for the fabrication of coherently bonded bodies of a low temperature sintered ceramic material, for particular use as the dielectric bodies of capacitors, which comprises: forming green bodies of desired shape and size from a mixture of 100 parts by weight of Ba k-x M x O k TiO 2 in finely divided form, where M is at least either of magnesium and zinc and where k is a numeral in the range of 1.00 to 1.04 and x a numeral in the range of 0.02 to 0.05, and 0.2 to 10.0 parts by weight of an additive in finely divided form consisting essentially of lithium oxide and silicon dioxide and a metal oxide selected from the group consisting of barium oxide, calcium oxide, strontium oxide, and combinations thereof, wherein the range of the relative proportions of lithium oxide, silicon dioxide, and the selected metal oxide constituting the additive is in that region of the tenary diagram of FIG. 4 attached hereto which is bounded by the lines sequentially connecting: the point A where the additive consists of 5 mole percent lithium oxide, 70 mole percent silicon dioxide, and 25 mole percent metal oxide; the point B where the additive consists of 10 mole percent lithium oxide, 50 mole percent silicon dioxide, and 40 mole percent metal oxide; the point C where the additive consists of 49 mole percent lithium oxide, 50 mole percent silicon dioxide, and one mole percent metal oxide; and the point D where the additive consists of 24 mole percent lithium oxide, 75 mole percent silicon dioxide, and one mole percent metal oxide; for providing upon firing coherently bonded dielectric bodies with a specific dielectric constant in excess of 2000, dielectric losses of less than 2.5 percent, resistivity of over 1×10 6 megohm-centimeters and capacitance temperature dependence of + or -10% in a temperature range of -25° to +85° C.; sintering the green bodies to maturity in a nonoxidative atmosphere at a temperature not to exceed 1300° C.; and reheating the sintered bodies in an oxidative atmosphere at a temperature lower than said preceding sintering temperature.

Claim 5

A process for the fabrication of coherently bonded bodies of a low temperature sintered ceramic material as set forth in claim 5 or claim 7, wherein the bodies are sintered in a temperature range of 1050° to 1200° C.

Claim 6

A process for the fabrication of coherently bonded bodies of a low temperature sintered ceramic material as set forth in claim 3, wherein the sintered bodies are reheated in a temperature range of 500° to 1000° C.