Abstract: A varistor having a plurality of spaced electrodes positioned on common surface thereof and a conductive layer positioned on the opposed major surface thereof.

Abstract: A varistor having opposed first and second major surfaces. A first electrode is disposed on at least a portion of both the first and second major surfaces, and a second electrode is disposed on at least a portion of both the first and second major surfaces. The first and second electrodes are symmetrically disposed on the varistor body about an axis lying midway between and parallel to the first and second major surfaces.

Abstract: A low varistor voltage, low leakage metal oxide varistor and especially a zinc oxide varistor is provided by adding a few percent of tetragonal antimony zinc oxide to the varistor mixture prior to sintering. A method for manufacturing the additive as well as a method for manufacturing a varistor including the additive are described.

Abstract: A low leakage varistor which is resistant to the high temperature, corrosive conditions encountered during assembly of such devices includes a protective layer disposed on the surface of the varistor body between first and second, spaced-apart electrodes. Both, varistors with electrodes on opposing major surfaces and varistors with laterally spaced electrodes on a single surface are described.

Abstract: Disclosed is a method of manufacturing a metal oxide varistor body. Conventional manufacturing techniques through sintering are utilized on any metal oxide varistor formulation which includes bismuth oxide. Following sintering, the devices are heat treated at a temperature between 750.degree. C. and 1200.degree. C. for a time in excess of about 10 hours. The heat treatment increases the alpha of the devices and substantially lowers the leakage current.

Abstract: Disclosed is a metal oxide varistor body and a method for manufacturing the same. Conventional manufacturing techniques through sintering are utilized on any metal oxide varistor formulation which includes bismuth oxide. Following sintering, the devices are heat treated at a temperature between 750.degree. C and 1200.degree. C for a time in excess of about 10 hours to cause the bismuth oxide to substantially completely convert to a body centered cubic phase. The presence of the body centered cubic bismuth oxide increases the alpha of the devices and substantially lowers the leakage current.

Abstract: Disclosed is a metal oxide varistor consisting primarily of metal oxide with a small percentage of preselected additives distributed substantially evenly therethrough. A grain growth inhibitor is combined with the metal oxide powder forming a final mix with peripheral regions having a high concentration of the inhibitor that surround and separate interior regions that have a low concentration of the inhibitor. Varistor bodies are formed from the final mix and the peripheral and interior regions retain their identities in the varistor bodies. The bodies can be pressed and sintered in the conventional manner. During sintering the grains within each interior region tend to combine and grow. However, growth is stopped at the peripheral regions due to the high concentration of inhibitor. Thus, the grain size in the processed pellet is dependent upon the size of the interior regions which can be controlled.

Abstract: Disclosed is an improved metal oxide varistor particularly suitable for varistor operation at low voltages such as 80 volts and less, and a method for the manufacture thereof. The varistor comprises a body portion compounded of a primary component and a plurality of additives. The additives are, before combination with the primary component, mixed thoroughly and reacted to form a crystalline reaction product. After grinding, the reaction product is mixed with the primary component and the body is further processed in the conventional manner.

Abstract: A metal oxide varistor comprising a body portion that is composed essentially of a metal oxide and a small percentage of a plurality of preselected additives. A passivating coating is applied to the body portion prior to the application of metallic contacts. The passivating coating includes at least some of the preselected additives in order to enhance device stability and insure compatibility therewith.