Robert Boschgmbh

Herbert Zimmermann

Gunther Stecher

Kurt Spitzenberger

Guenther Stecher

Wolfgang Leibfried

Klaus Steinle

Heinz Walter

Manfred Nitsch

Fedor Modic

Alfred Grob

Karl Rampmaier

Method of producing a self-suporting thick-film structure

Cicuit and process of manufacturing the circuit

A free-standing, self-supporting layer of glass-ceramic or crystallized glass is applied by thick-film technology over a presintered layer made of a vaporizable or etchable material which, after sintering the thick-flim glass-ceramic or crystallized glass layer (3) to a substrate (1), is removed by heating or etching. The layer (2) to be removed is preferably applied in paste form with the glass-ceramic thick-film layer (3) thereover either in form of a crossing bridge, as a partially covering cantilever, or entirely surrounding the layer 2, in which latter case the thick-film layer (3) is of porous construction so that the volatile or vaporizable components of the underlying layer (2) can escape through the thick-film layer (3). A typical layer which is volatile or vaporizable includes carbon black, a resin binder and a solvent, applied to a substrate, for example of ceramic or enameled metal, over which the glass-ceramic layer is applied. Electrically conductive tracks can be applied directly on the substrate beneath the layer (2) to be removed, and to the thick-film layer, or in the form of strain or temperature-sensitive resistors, for connection to an external circuit evaluating deformation of the free-standing layer by capacitative or resistance change, to obtain pressure sensors, vibration sensors, acceleration sensors, and the like of minute construction. A typical dimension of the thick-film layer is in the order of tens of micrometers, with the free space after removal of the filler (2) being also about in the order of tens of micrometers.

Method of making an electrical thick-film, free-standing,

High pressure sensor

Very fine solder-coated conduction paths are made on ceramic, glass or enamel substrates by the combination of a first step in thick-film technology followed by the photo-masking and etching steps typical of thin-film technology, after which galvanic reinforcement of the initial calcined copper paste layer is performed in the locations where the initial layer is exposed by the developed mask. A lead-tin solder layer is then galvanically deposited, which is thicker than the mask, after which the mask is removed and the newly exposed portions of the initial copper layer are etched away. A reflow treatment of the solder layer pattern consolidates the solder layer by melting on top of the boundaries of the unetched initial copper layer. It is possible to obtain conduction path spacings down to 50 .mu.m with conduction paths coated with solder that have excellent adhesion to ceramic, glass or enamel substrates.

Process of producing galvanic layers of solder of precise contour on

A free-standing, self-supporting layer of glass-ceramic or crystallized glass is applied by thick-film technology over a presintered layer made of a vaporizable or etchable material which, after sintering the thick-film glass-ceramic or crystallized glass layer (3) to a substrate (1), is removed by heating or etching. The layer (2) to be removed is preferably applied in past form with the glass-ceramic thick-film layer (3) thereover either in form of a crossing bridge, as a partially covering cantilever, or entirely surrounding the layer 2, in which latter case the thick-vaporizable film layer (3) is of porous construction so that the volatile or components of the underlying layer (2) can escape through the thick-film layer (3). A typical layer which is volatile or vaporizable includes carbon black, a resin binder and a solvent, applied to a substrate, for example of ceramic or enameled metal, over which the glass-ceramic layer is applied. Electrically conductive tracks can be applied directly on the substrate beneath the layer (2) to be removed, and to the thick-film layer, or in the form of strain or temperature-sensitive resistors, for connection to an external circuit evaluating deformation of the free-standing layer by capacitative or resistance change, to obtain pressure sensors, vibration sensors, acceleration sensors, and the like, of minute construction. A typical dimension of the thick-film layer is in the order of tens of micrometers, with the free space after removal of the filler (2) being also about in the order of tens of micrometers.

Electrical thick-film, free-standing, self-supporting structure, and

Growing community of inventors

Freiberg, Germany

Herbert Zimmermann