There is no reason why voids in non-conductive fills in PTVs are a problem. Kim's experience makes sense. Werner -----Original Message----- From: Haynes, Kim <[log in to unmask]> To: [log in to unmask] Sent: Wed, Oct 3 12:12 PM Subject: Re: [TN] Via plugging with LPI soldermask... I hve watched this plug/tent discussion thread with interest. I design and build boards for multi-gigabit transmission rates in a lab environment. When I use conductive filling, I seem to have via problems during thermal cycling device analysis. When I use a non-conductive epoxy, I do not have the problems. I have not been able to prove this hypothesis but I think the conductive fill has a different expansion rate than the board and the small vias tend to crack. The non-conductive epoxy expands at about the same rate as the boards and I do not seem to have the same failure rates from via cracking. One of my board fab shops is mil qual rated and they claim that the govt inspectors do not even want conductive epoxy in the buildings. It makes them nervous because it could be used instead of the non-conductive filler and they do not want any boards with silver epoxy. I have been searching to see if anyone has done controlled tests of conductive epoxy versus non-conductive epoxy fills for via in pad technology. Thanks, Kim Haynes Interface and Clock Products High-Speed Serial Link Applications Texas Instruments, Inc. 214-567-2057 Telephone -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Ted Tontis Sent: Wednesday, October 03, 2007 10:20 AM To: [log in to unmask] Subject: Re: [TN] Via plugging with LPI soldermask... Bill, I used to specify in my manufacturing notes 'vias must be plugged using LPI solder resist' I was told more then one once and from different suppliers that they could not guarantee the vias would be 100% 'plugged' using LPI. They would however guarantee that there would be LPI in the via hole or that the LPI would tent over the via, leaving a void in the center. If I required 100% via fill I would have to require that they fill the holes with some type of conductive filler. Thank you, Ted T -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Brooks,Bill Sent: Tuesday, October 02, 2007 3:44 PM To: [log in to unmask] Subject: [TN] Via plugging with LPI soldermask... Just a quick question... When specifying 'plugged' vias using LPI soldermask... what is the actual process used to accomplish this procedure? How do you make sure the vias are plugged and what is the proper acceptance criteria used to verify and inspect the finished results? What is an acceptable plugged via vs. a reject? Is there a spec or standard that spells this out process and inspection criteria and method for reference? Thanks in advance... Bill --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 847-615-7100 ext.2815 ----------------------------------------------------- ________________________________________________________________________ Email and AIM finally together. You've gotta check out free AOL Mail! - http://mail.aol.com --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 847-615-7100 ext.2815 -----------------------------------------------------