Low temperature sintered ceramic capacitor with high DC breakdown voltage, and method of manufacture

Claim 2

A solid dielectric capacitor comprising a dielectric ceramic body and at least two electrodes in contact therewith, the dielectric ceramic body consisting essentially of: 100 parts by weight of a major ingredient expressed by the formula, {(Ba.sub.1-x-y Ca.sub.x Sr.sub.y)O}.sub.k (Ti.sub.1-z Zr.sub.z)O.sub.2, where x is a numeral in the range of 0.02 to 0.27; y is a numeral greater than zero and not more than 0.37; z is a numeral greater than zero and not more than 0.26; k is a numeral in the range of 1.00 to 1.04; and (1-x-y) has a value not less than 0.60 and less than 0.98; and from 0.2 to 10.0 parts by weight of an additive mixture of B 2 O 3 , SiO 2 and MO, where MO is at least one metal oxide selected from the group consisting of BaO, SrO and CaO, the relative proportions of B 2 O 3 , SiO 2 and MO being in that region of the ternary diagram of the accompanying drawing which is bounded by lines sequentially connecting: the point A where the additive mixture consists of 15 mole percent B 2 O 3 , 25 mole percent SiO 2 , and 60 mole percent MO; the point B where the additive mixture consists of 30 mole percent B 2 O 3 , one mole percent SiO 2 , and 69 mole percent MO; the point C where the additive mixture consists of 90 mole percent B 2 O 3 , one mole percent SiO 2 , and nine mole percent MO; the point D where the additive mixture consists of 89 mole percent B 2 O 3 , 10 mole percent SiO 2 , and one mole percent MO; and the point E where the additive mixture consists of 24 mole percent B 2 O 3 , 75 mole percent SiO 2 , and one mole percent MO.

Claim 3

The solid dielectric capacitor as set forth in claim 1, wherein the electrodes are buried in the dielectric ceramic body.

Claim 4

The solid dielectric capacitor as set forth in claim 1, wherein the electrodes are of a base metal.

Claim 5

The solid dielectric capacitor as set forth in claim 3, wherein the base metal is nickel.

Claim 6

The solid dielectric capacitor as set forth in claim 1, wherein the dielectric ceramic body has a DC breakdown voltage of at least 25 volts per micron.

Claim 7

A process for the manufacture of a solid dielectric capacitor providing a mixture of: (a) 100 parts by weight of {(Ba 1-x-y Ca x Sr y )O} k (Ti 1-z Zr z )O 2 in finely divided form, where x is a numeral in the range of 0.02 to 0.27; y is a numeral greater than zero and not more than 0.37; z is a numeral greater than zero and not more than 0.26; k is a numeral in the range of 1.00 to 1.04; and (1-x-y) has a value not less than 0.60 and less than 0.98; and (b) from 0.2 to 10.0 parts by weight of an additive mixture of B 2 O 3 , SiO 2 and MO in finely divided form, where MO is at least one metal oxide selected from the group consisting of BaO, SrO and CaO, the relative proportions of B 2 O 3 , SiO 2 and MO being in that region of the ternary diagram of the accompanying drawing which is bounded by lines sequentially connecting: the point A where the additive mixture consists of 15 mole percent B 2 O 3 , 25 mole percent SiO 2 , and 60 mole percent MO; the point B where the additive mixture consists of 30 mole percent B 2 O 3 , one mole percent SiO 2 , and 69 mole percent MO; the point C where the additive mixture consists of 90 mole percent B 2 O 3 , one mole percent SiO 2 , and nine mole percent MO; the point D where the additive mixture consists of 89 mole percent B 2 O 3 , 10 mole percent SiO 2 , and one mole percent MO; and the point E where the additive mixture consists of 24 mole percent B 2 O 3 , 75 mole percent SiO 2 , and one mole percent MO; molding the mixture into desired shape and size, the molding having at least two electrode portions of an electroconductive material; cosintering the molding and the electrode portions to maturity in a nonoxidative atmosphere; and reheating the sintered molding and electrode portions in an oxidative atmosphere.

Claim 8

A process for the manufacture of a solid dielectric capacitor providing a mixture of: (a) 100 parts by weight of {(Ba 1-x-y Ca x Sr y )O} k (Ti 1-z Zr z )O 2 in finely divided form, where x is a numeral in the range of 0.02 to 0.27; y is a numeral greater than zero and not more than 0.37; z is a numeral greater than zero and not more than 0.26; k is a numeral in the range of 1.00 to 1.04; and (1-x-y) has a value not less than 0.60 and less than 0.98; and (b) from 0.2 to 10.0 parts by weight of an additive mixture of B 2 O 3 , SiO 2 and MO in finely divided form, where MO is at least one metal oxide selected from the group consisting of BaO, SrO and CaO, the relative proportions of B 2 O 3 , SiO 2 and MO being in that region of the ternary diagram of the accompanying drawing which is bounded by lines sequentially connecting: the point A where the additive mixture consists of 15 mole percent B 2 O 3 , 25 mole percent SiO 2 , and 60 mole percent MO; the point B where the additive mixture consists of 30 mole percent B 2 O 3 , one mole percent SiO 2 , and 69 mole percent MO; the point C where the additive mixture consists of 90 mole percent B 2 O 3 , one mole percent SiO 2 , and nine mole percent MO; the point D where the additive mixture consists of 89 mole percent B 2 O 3 , 10 mole percent SiO 2 , and one mole percent MO; and the point E where the additive mixture consists of 24 mole percent B 2 O 3 , 75 mole percent SiO 2 , and one mole percent MO; molding the mixture into desired shape and size, the molding having at least two electrode portions of an electroconductive material; cosintering the molding and the electrode portions to maturity in a nonoxidative atmosphere; and reheating the sintered molding and electrode portions in an oxidative atmosphere.

Claim 9

The process for the fabrication of a solid dielectric capacitor as set froth in claim 6, wherein the electrode portions are formed on the molding by coating a paste composed principally of a base metal.

Claim 10

The process for the fabrication of a solid dielectric capacitor as set forth in claim 7, wherein the base metal is nickel.

Claim 11

The process for the fabrication of a solid dielectric capacitor as set forth in claim 6, wherein the molding and the electrode portions are cosintered in a temperature range of 1000° to 1200° C.

Claim 12

The process for the fabrication of a solid dielectric capacitor as set forth in claim 9, wherein the sintered molding and electrode portions are reheated in a temperature range of 500° to 1000° C.