The use of conductive epoxy is solely to provide a flat (plated) surface for the probes to impinge upon, rather than a pad and hole. By filling the hole with epoxy, you prevent the probes from damaging the plating at the edge of the hole, while the conductivity of the test pad is largely unaffected (actually improved slightly) since the copper plating inside the hole does what it would normally do anyway, with or without epoxy filling. Epoxy filling does not replace the copper plating as it's applied after the plating process. A number of fab houses do fill holes very successfully within certain bounds - hole diameter and aspect ratio are the two critical parameters in determining if a hole can be filled or not. I can give you the names of 3 or 4 fab shops I've used for epoxy filling if you want to contact me off-line. Peter Collins Graham <[log in to unmask]> 15/04/2003 07:32 PM Sent by: TechNet <[log in to unmask]> Please respond to "TechNet E-Mail Forum."; Please respond to Collins Graham To: [log in to unmask] cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group) Subject: Re: [TN] Neither a question, or a response... Hi Dave Whenever I hear of issues like this I usually go hound the test guys to change the probes on the ICT tester. We do a fair bit of partial wave here, so lots of via surfaces don't get touched by the wave. To manually fill these would be a pain in the wallet, and I'm not getting into screen printing paste on to vias if I can avoid it. Thus far the test guys have been able to get good results with different probes. If you are going to use a conductive epoxy, is it as conductive as copper? I'd be worried about throwing off the test results. E.G. my ICT is looking for a 500k resistor, but my conductive epoxy is adding 10k to the reading - I might replace parts as being out of tolerance when they are actually just on the edge... Just a thought. Good luck! regards, Graham Collins Process Engineer, Northrop Grumman Canada Corporation Halifax (902) 873-2000 ext 6215 >>> [log in to unmask] 04/15/03 08:09AM >>> I do have a question and would like a response offline please. I have 2000 vias on the bottomside of a wave soldered board and vias (not all) will be used by test. Problem is operators spend way too long inspecting to see the vias are filled by the wave. I want to fill the vias with conductive epoxy, Methode or Dupont material. I hear it is done but can find none of our board houses who have ever done it. Is this a fantasy? A good theory no one is doing? Why not? I got a response that it is "very very expensive" what does that mean? $1 a board more $10 a board more? And yes I have searched the archives. This is a high volume job I may be able to eliminate 3 shifts worth of inspection vs. whatever the increased board cost is. Thank you. I promise to post results to Steve's website complete with pictures whether it works or not. Dave Chapman Manufacturing Engineer Circuit Service Inc. --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- [This e-mail is confidential and may also be privileged. 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