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Browse Prior Art Database

Electrical Probe

IP.com Disclosure Number: IPCOM000094039D
Original Publication Date: 1966-May-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 3 page(s) / 88K

Publishing Venue

IBM

Related People

Graner, FL: AUTHOR [+2]

Abstract

The electrical probe is suitable for making electrical resistivity measurements on a planar surface of microminiature circuitry.

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Electrical Probe

The electrical probe is suitable for making electrical resistivity measurements on a planar surface of microminiature circuitry.

This probe has many contacts, e.g., 20 to 60, but is not limited to this number. The contacts are individually adjustable to test a very small sampling area, e.g., 0.030 in. x 0.030 in. in a 20-contact probe. There is a relatively small spacing between contact points, e.g., 0.0005 in., with relatively small tolerances, e.g., 0.0002 in. The probe is relatively small in size. Jewel bearings are used to position each contact point to provide precision alignment, low friction, springless contact force. All contacts are viewable simultaneously with a microscope for adjustment purposes while the probe is being used. This construction permits very fine adjustment of the contacts, use of machined parts with considerable tolerances, and use of jewel bearings which also provide electrical insulation of the contacts from the housing. Axial movement of each probe is perpendicular to the sampling area plane. Relatively large, rigid elements are used to maintain precision alignment of the probe contacts. A completely adjustable set of contacts is provided.

Drawing A is a sectional elevation view of the electrical probe considering one probe contact 2C. Drawing B is a cross-sectional view through probe arm 2D of drawing A. Drawing C is a cross-sectional view through main housing 1 and bearing housing 10A along adjusting screw 9 of drawing A.

The probe has main housing 1 with a plurality of slots 1A equally spaced around the circumference of the housing for adjustment purposes. Axial opening 1B is presented through the center of housing 1 for viewing contact probe points 2C. A tapered outer perimeter of housing 1 engages tapered outer housing 12. Each slot 1A contains bearing housing 10A. This positions probe shaft 2A of probe 2 which is held by two sapphire bearings 10B. Shaft 2A is precision positioned in the bearings but is free to turn and move axially. The bearings also provide electrical insulation between the shaft and housing 10A.

Housing 10A and shaft 2A are adjustable radially from the center of housing 1 by taper gib 11A located in slot 1A between housing 10A ad housing 12. Gib 11A is moved axially by adjusting screw 11B via adjusting knob 11C. Force from springs 3 between housing 1 and housing 10A press the latter against gib 11A. Shaft 2A has probe arm 2D connected to its lower extremity in approximately a radial position from the center of the electrical probe and has contact point 2C near the center of the probe. Arm 2D and a point 2C are tapered to permit close packing of the points on relatively small test ar...