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Making a Matched Impedance Probe

IP.com Disclosure Number: IPCOM000078702D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Markewycz, Z: AUTHOR [+3]

Abstract

This is a precision matched impedance probe, fabricatable in multiple quantities at significantly lower cost than individually precise machined probes.

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Making a Matched Impedance Probe

This is a precision matched impedance probe, fabricatable in multiple quantities at significantly lower cost than individually precise machined probes.

As shown in Fig. 1, a mold 10 fabricated to the precise contour and dimensions of the desired probe assembly is used as a mandrel. This mandrel may be fabricated from stainless steel. As shown in Fig. 2, a suitable metal 12 such as nickel, copper, etc. is deposited preferably by electroplating techniques. It is also possible to deposit metal layer 12 by evaporation.

A coupling agent, not shown, is then applied to this deposited metal and a layer 14 consisting of a suitable polymer (high-temperature thermosetting resin) is then molded in place, as shown in Fig. 3. The polymer is cured and bonds to the deposited metal layer 12 utilizing the coupling agent. The part is then ejected from the mold, with the polymer 14 retaining the metal surface 12, thereby transferring the metal layer 12 from the mandrel 10 to the polymer. At this point the entire probe surface is formed in metal. Holes and other conductive areas can also be formed during this operation if so provided in the mold.

A 50 ohm impedance of the probe is established, by providing a tungsten probe wire 16 with a precisely deposited thickness of polymer insulator 18 directly on the tungsten probe wire, after which the tungsten wire 16 is bonded in place achieving the desired probe force. The precise thickness of the polymer in...