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Electrical Test Probe Alignment Aid

IP.com Disclosure Number: IPCOM000060408D
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Allard, HC: AUTHOR [+3]

Abstract

Method of automatically sensing probe alignment errors so that corrections may be made on the fly as a tester steps across a wafer. The probe pattern illustrated is embedded in the design at opposite corners so that axis and rotational errors are sensed. If opposite corners are in registration, it is reasonable to assume that all other pads are in registration. Pad location #1 contains no metal, but is surrounded by metal lands "A", "B", "C" and "D" (captive sensing zone). If the probes are misaligned to the left, then probe #1 contacts metal land "A" which is tied to pad #3. Pad #3 is designed such that even if the probes are misaligned to the left, contact is still made to pad #3. When the probes are set down, the test program checks the continuity between pad #1 and pads #2, #3, #4 and #5.

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Electrical Test Probe Alignment Aid

Method of automatically sensing probe alignment errors so that corrections may be made on the fly as a tester steps across a wafer. The probe pattern illustrated is embedded in the design at opposite corners so that axis and rotational errors are sensed. If opposite corners are in registration, it is reasonable to assume that all other pads are in registration. Pad location #1 contains no metal, but is surrounded by metal lands "A", "B", "C" and "D" (captive sensing zone). If the probes are misaligned to the left, then probe #1 contacts metal land "A" which is tied to pad #3. Pad #3 is designed such that even if the probes are misaligned to the left, contact is still made to pad #3. When the probes are set down, the test program checks the continuity between pad #1 and pads #2, #3, #4 and #5. If there is continuity to pad #3, for example, the probes are raised and indexed one unit to the right and set down again. This technique allows on-the-fly adjustments. Because opposite corners are checked, a rotational error adjustment may also be incorporated in the tester alignment procedure. Also, the metal alignment pads need not be dedicated to probe registration alone, but may also be incorporated in the active circuit design as well.

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