W.c. Heraeus Gmbh

Walter G Reichelt

Nils Harmsen

Gunther Herklotz

Horst Thiede

Gunter Sauer

Horst Markhof

Klaus-Ludwig Schiff

To provide low contact resistance, long life, and resistance against tarnishing under corrosive, particularly sulfur atmospheres, a substrate carrier has a layer of palladium applied thereto, of a thickness between 0.5 and 5 .mu.m, preferably between 1 and 3 .mu.m, to which a coating of gold is applied which is porous and has a thickness of only between 0.05 .mu.m and 0.1 .mu.m; the porous gold coating forms islands of gold on the palladium which, in use and as the terminal is wiped against a counter element, smears over the palladium, thus effectively covering the palladium, preventing tarnishing, and maintaining low contact resistance throughout the useful life of the terminal element.

Electrical plug-type connector

The present invention provides low-current carrying rem-reed switch contacts, preferably for operation under vacuum or under a protective gas. The contacts comprise a medium-hard magnetic material substrate which may contain anomalies on the surface. These are covered by an intermediate layer from 1 to 20 .mu.m of at least one metal selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium and tantalum. This intermediate layer is then covered with a noble metal layer, for example alloys of gold or silver, and preferably by ruthenium.

Electrical switching contact

A substrate carrier of electrically non-conductive material has a strip of resistance platinum applied thereto; in order to avoid the use of an intermediate temperature coefficient of expansion matching layer, the substrate carrier, for example of aluminum oxide, beryllium oxide, or a magnesium silicate, has less than thirty parts per million (ppm) Fe, less than 15 ppm Cr, less than 45 ppm Pb and less than 70 ppm Si in a form capable of reacting with platinum, the sum of the impurities by these metals, if all, or more than one are present, not exceeding 20 ppm; the average thermal coefficient of expansion of the substrate does not deviate from the mean thermal coefficient of expansion of the thermometer grade platinum by more than .+-. 30%; the platinum layer has a thickness of from 0.1 to 10 .mu.m, and is applied at a temperature in the range of between about 1000.degree. C to 1400.degree. C during 60 minutes in an atmosphere containing oxygen, for example free air.

Electrical temperature measuring resistor structure, particularly for

On an aluminum oxide or high-alumina ceramic substrate an intermediate layer of a rare earth, titanium or iron oxide or a mixture of such oxides is provided for matching the thermal expansion coefficient of the substrate to that of a platinum layer between 0.1 and 10 .mu. m thick applied in a resistor pattern configuration on the surface of the intermediate layer. The intermediate layer, unlike a glass embedding layer, allows heat treatment of the platinum layer by heating the entire structure makes it possible to avoid the embedding to heal local defects, without impairing the integrity of the structure (which occur when glass melt) and without co-crystallizing with aluminum oxide. The platinum layer thickness is consistent with stability of the specific resistance and the temperature coefficient of resistance.

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Hanau, Germany

Walter G Reichelt