Robert Boschgmbh

Heraeus Electro-Nite International N.v.

Heraeus Sensor-Nite Gmbh

Eva Soll

Karlheinz Wienand

Karl-Hermann Friese

Hans-Martin Wiedenmann

Stefan Dietmann

Matthias Muziol

A process is provided for producing a sensor arrangement for measuring temperature with a temperature-sensitive measuring resistance element which has a thin, metallic resistance layer electrically-insulated toward the outside on a ceramic substrate and free-lying contact surfaces, which are connected electrically-conducting and directly mechanically fast with high-temperature-resistant conductor strips, electrically insulated from one another, on a ceramic board. The measuring resistance element is bonded and fastened on one end of the board by laying it on a still moist thick-film conducting paste printed on immediately before outfitting on the board and subsequently burning it in. On the end of the board away from the measuring resistance element, contact surfaces for connection of a plug or cable are arranged. The temperature sensor, a standard component in the form of a flat measuring resistance element, is applied wirelessly as an SMD component on the ceramic board. The sensor arrangement manufactured with the process is suited for temperature measurements above 400.degree. C. as well. The process is economical in using only a few standardized components and easily automatable process steps.

Process for producing a sensor arrangement for measuring temperature

A resistance thermometer has a measuring resistor in the form of a resistance layer essentially made of a metal of the platinum group, preferably of platinum, laid on an electrically insulating surface of a carrier having a thermal expansion coefficient in the range 8.5 to 10.5 ppm/K range, and is provided with an electrically insulating cover layer. The carrier for the resistance layer can be constructed in the following manner: (a) as a substrate of a material containing a magnesium compound, preferably magnesium titanate; (b) as an intermediate layer mounted on a substrate, wherein the material of the substrate contains at least one magnesium compound; or (c) as an intermediate layer mounted on a substrate, wherein the substrate comprises aluminum oxide. With the resistance thermometer it is possible to attain a high long-term stability in the upper temperature range (above 500.degree. C.).

Resistance thermometer

An electrochemical measurement sensor for determining the oxygen content in gases, in particular in exhaust gases from internal combustion engines, having a solid electrolyte of stabilized zirconium dioxide and/or other oxygen ion-conductive oxides and at least one electrode on the side of the solid electrolyte exposed to the gas which is to be measured, is proposed, the electrode or electrodes containing, if desired, a ceramic support structure, and the electrode or electrodes exposed to the gas, which is to be measured, being covered by a porous ceramic protective layer of an Al.sub.2 O.sub.3 and/or Mg spinel (MgO.Al.sub.2 O.sub.3) matrix with preferably metastable ZrO.sub.2 particles incorporated therein. The use of an Al.sub.2 O.sub.3 ZrO.sub.2 mixed oxide, which is preferably obtained by coprecipitation or by combination of suspensions of separately precipitated components or by spray-calcination of a combined solution of salts of the components and which may, if desired, contain a stabilizer for the ZrO.sub.2, such as, for example, Y.sub.2 O.sub.3, for forming the protective layer makes it possible, surprisingly, to form a firmly adhering, sintering-on protective layer which has a relatively narrow pore size distribution and which allows the best possible gas access to the outer electrode of the measurement sensor. The use of the Al.sub.2 O.sub.3 /ZrO.sub.2 mixed-oxide powder also achieves very extensive balancing of the hitherto observed mismatch of mechanical stresses and layer strengths on the one hand and the desired porosity and sensor control position on the other hand.

Method of making a porous ceramic protective layer on an electrode of an

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Frankfurt-am-Main, Germany

Eva Soll