Hi, Franklin, The first answer I would ask myself is "Is conductive epoxy filing really necessary?". It's an axtra process, and not especially cheap, particularly if you're filling blind vias after laser drilling. Things to look at to determine the effectiveness of the process are: -epoxy type - most people seem to go for DuPont's CB101, as it has a small particle size, fills smaller holes well and doesn't suffer from out-gassing problems in a properly established process.. - hole diameter and aspect ration that you're intending to fill - 6:1 aspect ratio is about the limit, with the minimum diamter being around 12 mils. I have had 24 mils diameter holes filled that are only 7 mils deep, which is an aspect ratio of about 2:5. Bigger than that and the epoxy sags. Don't know what the upper diameter limit is, but I doubt you would want to be filling very large holes. - CTE relative to your board material, though I haven't encountered any problems with that so far. Regarding the process sequence offered to you, I would say "OK" only as long as you're not mounting anything on top of the holes (e.g. BGA via-in-pad) or don't need a flat surface on the side of the board that's opposite the squeegee. If you do, then you need one more process, so the whole thing would be: electroless copper flash copper 3 mil resist cleared 5 mils around the vias to be plugged squeegee the conductive epoxy (from one side till 'tails' form on the back side) tack cure final cure GRIND FLAT clean Final Image Copper II Done nicely, you would almost not know that there had been any holes there at all. We initially used conductive epoxy to help maximise a thermal path through the board, but actually a very small increase in hole plating thickness gives a much better result, and removes one process/cost. The grinding has to be done carefully so that the epoxy doesn't overheat and smear. Hope it works out for you. Peter Franklin D Asbell <[log in to unmask]> 09/01/2003 10:29 PM Sent by: TechNet <[log in to unmask]> Please respond to "TechNet E-Mail Forum."; Please respond to Franklin D Asbell To: [log in to unmask] cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group) Subject: [TN] Conductive Silver Epoxy We're about to begin developing a process for plugging vias with conductive silver epoxy. We've had the vendor's technicians here explainging the processes, providing material and literature, and our experimenting will begin later today...just wondering what all of your thoughts and/or experiences are/were on this topic??? What (they've) we've planned out is; electroless copper flash copper 3 mil resist cleared 5 mils around the vias to be plugged squeegee the conductive epoxy (from one side till 'tails' form on the back side) tack cure final cure clean Final Image Copper II etc etc Thanks, Franklin --------------------------------------------------- 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. If you are not the intended recipient, please delete it and notify us immediately; you should not copy or use it for any purpose, nor disclose its contents to any other person. Thank you.] --------------------------------------------------- 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 -----------------------------------------------------