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Card Extension for High Speed Logic Testing

IP.com Disclosure Number: IPCOM000035315D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Kolias, JT: AUTHOR [+2]

Abstract

Computer system designers require some form of card extension that would allow easy testing or probing of sensitive locations (circuits) on a printed circuit card. Any method of card probe must be reliable, provide easy access, have good electrical contact with the component pins under test, yet not disturb or alter machine operational characteristics so that troubleshooting/testing can be facilitated.

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Card Extension for High Speed Logic Testing

Computer system designers require some form of card extension that would allow easy testing or probing of sensitive locations (circuits) on a printed circuit card. Any method of card probe must be reliable, provide easy access, have good electrical contact with the component pins under test, yet not disturb or alter machine operational characteristics so that troubleshooting/testing can be facilitated.

Described is an approach to provide for reliable card troubleshooting/testing product by minimizing extender introduced circuit delay, giving the card designer closer to "real time testing." This design ensures a reliable and repeatable method of card probing that introduces the least possible amount of signal distortion and delay penalties due to impedance mismatches, cross-talk, time of flight (propagational delays) and high resistance (lossy) wiring.

The card extender concept consists of the following (see the figure):

A short transposer block that would mount onto planar zero- insertion-force (ZIF) pins representing the location of the card under test. The subject card is then removed from the cage and secured to the transposer block. Electrical connection from the ZIF I/Os at the opposite end of the test card to the second planar (if necessary), is made through a group of coaxial or Tri-Lead cable. At the ends of the cables is another transposer block that provides correct mating of I/Os (opposite card edge and secon...