Immersion Silver finish with Methode 212 via fill material. Have not done these ourselves but the Methode is another filler material. Dave Chapman CSI -----Original Message----- From: Steve Gregory [mailto:[log in to unmask]] Sent: Monday, March 22, 2004 8:44 AM To: [log in to unmask] Subject: Re: [TN] Plugged Via bubble Mornin' All! I'd be interested in an opinion as well about the reliability of voiding in vias filled with silver epoxy. I got some pictures as well up on my page of voids in vias. Go to: http://www.stevezeva.homestead.com and look at "Voids and Voids 2" as well as Douglas's pictures. I was wondering about class-3 reliability, if you saw voids like in my pictures, would you reject the fabs? A little bit about my pictures. The vendor who made the boards from where these these cross sections came from, was fired. Not primarily for the voiding, bu t we actually had a cross section that showed vias with huge copper voids in the barrel walls. The only reason the boards passed bare board test is because they were silver filled...to make matters even worse, we had assemblies built and shipped that had fabs that came from the lot where the cross sections came from. Everything we built we recalled, and fired the fab shop, because they could not provide us with any objective evidence that they had done any process monitoring building these fabs. The cross sections that these pictures came from were ones that I had done...and it's a long story, but it was just a fluke that I had them done. Up to that point, we thought everything was going along okay. We had no reason to doubt anything was wrong. A little more info about my pictures. The epoxy that was used was a Dupont CB-100 I believe, I have heard stories that particular epoxy can sometimes be difficult to work with. Is that true? If so, is there another brand to specify? It was difficult to find somebody to build this fab. I'm not saying that this was a easy fab to build either. As you can see in the cross sections, this is a 10-layer fab, blind vias, via-in-pad, and all vias are silver filled. The 10th layer of the board was sequentially laminated after the vias were epoxy filled and planarized. As you can also see, that 10th layer is nothing but a solid copper plane. Laminate material is Polyimide. The board is HASL'ed as well...try to build that without it becoming a taco. To make things fun for me, there's 20-mil pitch devices on the board as well as 0603's. Ahhhhhh! Such is the life in a contract shop... -Steve Gregory- > Technetters, > > Do any of you have reliability data or other experience with plugged vias > that are subsequently plated over? > > Steve has been kind enough to agree to post pictures of the "defect" on his > website. > > The micro section photos of the voids in the plug-and-cap vias. These were > taken at 10X magnification. The voids/bubbles average .005" in diameter, > almost round. Looking at the photos you can determine approximately how > large they are by noting that the drill hole diameter is .010 inches drilled > with a 10-mil drill size. > > What potential long-term reliability concerns are there, and is this > considered acceptable for Class 2 product. > > > Douglas Corbett > L-3 Communications / Communication Systems - West > Senior Manufacturing Engineer - Printed Circuit Boards > (801) 594-3153 > --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------