W.c. Heraeus Gmbh

Rudolf Schnabl

Helmut Becker

Heinrich Wolf

Dieter Feldmer

Dieter Poss

Karin Witting

Intermediate material in the form of a metal strip with a contact area is provided with a projection on the bottom surface of its core area, i.e., on the surface to be joined to a contact carrier strip of copper or a copper alloy. The bottom surface of the strip facing the contact carrier strip is plated with a material which consists essentially of silver, and the melting point of the core area of the metal strip is above the melting point of silver. For the production of a semifinished product for electrical contacts, the metal strip is welded by its silver-coated bottom surface to the contact carrier strip, consisting essentially of copper. The silver from the coating on the core area of the metal strip and the copper from the contact carrier strip mix with each other and thus form an alloy which corresponds or is very close to the eutectic alloy with 28 wt. % of copper and the remainder of silver.

Welding process

Disclosed is a laminated material for electrical contacts having a support of base metal or of a base metal alloy, a contact layer of titanium nitride which in turn is covered with a mixed layer of titanium nitride and at least one noble metal. Also disclosed is a method for making the laminated material in a single step in a vacuum apparatus with reactive formation of the titanium nitride.

Laminated material for electrical contacts and method of manufacturing

To measure contact resistance between a probe and a terminal sample, and to insure gentle engagement of the probe on the sample, a scale beam is used which has an adjustable engagement weight, and which is lowered under control of a cam disk with an interposed magnetic system in which two magnets of equal polarity are placed adjacent each other so that, due to the repelling force of the two magnets, jolt-free, vibration-free engagement is possible, providing in effect a magnetic buffer. Preferably, the probe is a test wheel which, upon lowering from a raised position, can be disengaged from the drive motor which, when the test probe is off the sample terminal, rotates the wheel so that a fresh wheel surface is available for subsequent measurement. Engagement force can be controlled by suitable positioning of a counter weight, for example by a servo motor.

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Rodenbach, Germany

Rudolf Schnabl