Preh-werke Gmbh Co. Kg

Preh Elektrofeinmechanische Werke Jakob Preh Nachf Gmbh & Co.

Preh, Elektrofeinmechanische Werke

Jacob Preh Nachf. Gmbh & Co.

Peter Ambros

Walter Budig

Gisela Westermeir

Erich Gatzke

Hugo Johannes

Franz Kissner

Gottfried Berthold

Heinz-Jurgen Siede

Walter Muller

Kurt Berger

Rudolf Limpert

Hans-Peter Koch

Hermann Geyer

The invention relates to a method for producing powdery, vitreous carbon, and a paste made therefrom for producing resistive films having predetermined electrical conductivity. In production methods known in the art, pyrolysis of acrylamides is performed in mixture with water-soluble salts and, following pyrolysis, the powdered portion of the vitreous carbon is recovered by dissolving the salt component in water. The vitreous carbon is then dried, and the powder obtained in this manner is pulverized once again, as needed. A disadvantage of this method is that it is very time-consuming. In the solution now recommended, a preferably aromatic polymer is cured into a resin that is cross-linked in three dimensions, and in this state is ground to a powder prior to pyrolysis. Pyrolysis of the resulting powder is performed in a nitrogen atmosphere, so that powdered, vitreous carbons having different resistivities are obtained by using different final pyrolysis temperatures in each pyrolysis process. The vitreous carbon having a specific electrical resistivity obtained through pyrolysis is then dispersed into a binding agent and is ground in a mill together with the binding agent to a grain size of <10 &mgr;m. Then the viscosity of the paste with the vitreous carbon obtained in this manner for producing a resistive film is established by addition of a quantity of solvent for thinning. It is then possible to produce various resistive films from the paste produced in this manner, with a set but constant packing density of the vitreous carbon, having maximum mechanical and electrical stability that is very sturdy and abrasion-resistant in comparison to the surrounding area.

Method for manufacturing powdery, vitreous carbon useful for making pastes having predetermined electrical conductivity

The invention relates to a method for producing powdery, vitreous carbon, and a paste made therefrom for producing resistive films having predetermined electrical conductivity. In production methods known in the art, pyrolysis of acrylamides is performed in mixture with water-soluble salts and, following pyrolysis, the powdered portion of the vitreous carbon is recovered by dissolving the salt component in water. The vitreous carbon is then dried, and the powder obtained in this manner is pulverized once again, as needed. A disadvantage of this method is that it is very time-consuming. In the solution now recommended, a preferably aromatic polymer is cured into a resin that is cross-linked in three dimensions, and in this state is ground to a powder prior to pyrolysis. Pyrolysis of the resulting powder is performed in a nitrogen atmosphere, so that powdered, vitreous carbons having different resistivities are obtained by using different final pyrolysis temperatures in each pyrolysis process. The vitreous carbon having a specific electrical resistivity obtained through pyrolysis is then dispersed into a binding agent and is ground in a mill together with the binding agent to a grain size of &lt;10 .mu.m. Then the viscosity of the paste with the vitreous carbon obtained in this manner for producing a resistive film is established by addition of a quantity of solvent for thinning. It is then possible to produce various resistive films from the paste produced in this manner, with a set but constant packing density of the vitreous carbon, having maximum mechanical and electrical stability that is very sturdy and abrasion-resistant in comparison to the surrounding area.

Paste having predetermined electrical conductivity, and resistive film

A paste composition for preparation of electrically resistive layers is described comprising a curable polymer binder in which electrically conductive pigments are dispersed, wherein the composition contains as the electrically conductive pigments a glass-like carbon with a highly unoriented tri-dimensionally cross-linked coil structure.

Resistor paste composition and resistor layers produced therefrom

In a resistance paste for the production of electric resistors consisting of a polymer binding there are dispersed electrically conductive particles, solvents and additives; in order to produce resistance layers which are electrically stable and resistant to organic substances such as fuels and oils within a temperature range of from -55.degree. C. to +160.degree. C., more than half of the solids contained in the polymer binder consists of a mixture of

Resistance paste and resistance layer produced therefrom

A data input board for the electrical detection of the coordinates of a writing tip includes a rigid plate and an elastic plate with electrically conductive surfaces facing each other at a small distance which contact point by point under the effect of a writing tip. The elastic plate is formed as a stretched, coated sieve tissue in order to avoid the requirement of spacers within the input surface.

Data input board

The present invention describes an improved reverse lamination process for reparing printed circuits with resistors, conductor strips and/or contacts integrated in the circuit. A separating layer is applied on a metallic intermediate carrier. The intermediate carrier thus coated is then printed with a conductive paste in a desired. mirror-inverted layout to provide the resistors, conductor strips and/or contacts. This is followed by the lamination which is carried out under temperature effect and under pressure, the thus laminated package comprising the intermediate carrier, an intermediate layer and the final substrate. The intermediate carrier is subsequently removed, and the separating layer is etched off. The separating layer acts as a parting agent to permit easy mechanical separation and reuse of the metallic intermediate carrier.

Process for preparing printed circuits

An x-y position detector is shown which comprises a pen and contact plate with a resistive layer formed thereon. Point electrodes are provided on the four sides of the resistive layer. The materials of the resistive layer and the pen are selected such that the pen is in reliable galvanic contact with the resistive layer. The resistive layer is hard and smooth, and permits easy motion of the pen. The resistive layer consists of carrier particles with a hardness of between 5 and 9 on the Mohs hardness scale, pyrolytically coated with carbon and embedded in a binder whereby the resistive layer is hard and enables easy motion of the pen. The surface on which the pen moves is formed by molding the resistive material on a smooth intermediate substrate.

X-Y Position detector

A bonding assistant for a support material consists of an organic binder ch comprises a mixture of a saturated polyester and an isophorone diisocyanate containing masked isocyanate groups apart from OH groups, said mixture being present in a proportion of from 50 to 80 percent by weight of the total mixture, the binder having filler particles of a particle size less than 15 .mu.m dispersed therein in a proportion of from 10 to 50 percent by weight.

Bonding assistant for a support material

The invention concerns a printed circuit with electrically conductive, solderable conductors and integrated resistance layers upon a nonconductive substrate, in certain surface patterns.

Printed circuit

The disclosure is of a substrate or supporting board for supporting printed ircuits and the method of its manufacture. The boards of the invention are preferably made of a high-temperature resistant thermoplastic, sensitized to receive a printed circuit element by the dispersion of coated iron or copper particles in the thermoplastic matrix. The coating is a bonding assistant.

Growing community of inventors

Leutershausen, Germany

Peter Ambros