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Rolling Ball Contact Probe

IP.com Disclosure Number: IPCOM000040329D
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Lavin, MA: AUTHOR [+2]

Abstract

Rolling ball contact probes, with appropriate supporting electronics, make effective and inexpensive probes for manufacturing and testing of planar devices. Many manufacturing processes require repeated placement of electrical probes, to contact features of a planar workpiece. The canonical "job cycle" for automating such processes is as follows: 1. Move probe to point over feature 2. Wait for motion to null out 3. Lower probe to contact 4. Do the manufacturing operation 5. Raise probe 6. Repeat until done. The time required for steps 2, 3, and 5 can significantly degrade overall application throughput. Repeated impact of the probe on surface features can cause wear to the probe tip or damage to the parts.

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Rolling Ball Contact Probe

Rolling ball contact probes, with appropriate supporting electronics, make effective and inexpensive probes for manufacturing and testing of planar devices. Many manufacturing processes require repeated placement of electrical probes, to contact features of a planar workpiece. The canonical "job cycle" for automating such processes is as follows: 1. Move probe to point over feature 2. Wait for motion to null out

3. Lower probe to contact

4. Do the manufacturing operation

5. Raise probe

6. Repeat until done. The time required for steps 2, 3, and 5 can significantly degrade overall application throughput. Repeated impact of the probe on surface features can cause wear to the probe tip or damage to the parts. Similar difficulties can be introduced by "scrubbing" if the gross motion has not completely nulled out when contact is made. The probing method features a captive conductive ball which rolls over the surface of the workpiece and contacts the feature to be probed. Electrical contact between the ball and utilization electronics is made inside the probe, in one of several ways. Fig. 1 shows ball 1, held in cup 2, and contacted by spring brush 3. The cup 2 is made of polyester or other suitable low-friction material. The detailed design of the brush, ball, and cup depend on parameters of the particular application, such as how much current must be carried and what other electrical properties are needed to make contact with device feature...