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October 1999

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From:
Cyrus Ringle <[log in to unmask]>
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TechNet E-Mail Forum.
Date:
Mon, 11 Oct 1999 15:03:04 -0700
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   Hope this is helpful,

   Test Pads: ( Minimum or Maximum)
   1) Bottom-side test pads should be at least 0.035


? (.025) in diameter.       ?Bottom-side? means the main side on which test pads are located, It will       be oriented toward the bottom of the fixture.    2) Top-side test pads should be at least 0.045? (.035) in diameter. There is       a tolerance stack-up that results from the tooling holes, tooling pins,       the angle of the tooling pins, the angle of the probe, probe straightness,       and perpendicularity of the holes for the probes and tooling pins that       requires larger pads for top-side access. ?Top-side? means the side on       which the fewest test pads are located. It will be oriented toward the top       of the fixture and will be accessed via a mechanical clamp.    3) There should be a clearance area of 0.018? around test pads so that larger       probe head styles do not short out adjacent test pads.    4) When there are components on the side of the boards being probed, keep a       0.040? clearance from the edge of the test pad to an adjacent component so       the probe does not come in contact with nearby components.    5) there should be a clearance of 0.200? around test pads adjacent to       components taller than 0.250?. This allows for milling out clearance for       the taller component, and there must be sufficient material left for the       insertion of the probe receptacle.    6) Test pads should have 100-mil or 75-mil center-to-center spacing. If at       all possible, avoid 50-mil spacing since 50-mil probes are much more       fragile, cost more, are more expensive to install, wear out faster, and       are less reliable than the larger 100 and 75-mil probes.    7) Clearance from board edges should be a minimum of 0.125? in order to       assure good vacuum sealing.    8) Identification: If you intend to use a via as a test pad, the via must       conform to the test pad requirements, and you should make that particular       via a square shape. In future layout changes, do not move this particular       via, and the test fixture will not be affected.       Cyrus Ringle       Sr. CAD Specialist       Inter-Tel, Inc. http://www.inter-tel.com       7300 West Boston Street       Chandler, AZ 85226       Voice: (480) 961-2263       Email: [log in to unmask] Dave Hoover <[log in to unmask]> on 10/11/99 01:47:26 PM Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond to       Dave Hoover <[log in to unmask]> To: [log in to unmask] cc: (bcc: Cyrus Ringle/Inter-Tel) Subject: [TN] ICT Test Pin Attributes
Curious about what designers are using now for ICT test pin location access pad size (S/M also) along with closest distance between two test points. (Of course those flying probe ICT 's can bend major rules but I'm thinking standard fixture/high volume.) David Hoover ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################

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