Thank you Werner, I'm saving it in the right place now. But does the filling percentage play a role? Should I push my PCB suppliers to measure and guarantee something close to 100% filling? One supplier told me they are printing the solder mask in the vias and check with blotting paper if the stuff gets through. And if not, they make a second pass. For me this is an overkill and we must be paying something extra for it. By the way, our products are telecom, some for outdoors and high-rel, like 911 systems and power line protection. Best regards, Ioan > -----Original Message----- > From: Werner Engelmaier [SMTP:[log in to unmask]] > Sent: Friday, October 01, 2004 9:02 AM > To: [log in to unmask] > Subject: Re: [TN] Via filling > > Hi Ioan, > PTVs filled with solder mask/epoxy during the soldering processes will > experience less compressive loads on the copper barrel, and thus less > tensile > stresses which are part of the loading leading to innerlayer separation. > During > operationall use, this fill plys no significant reliability role. > PTVs filled with solder of course offer no advantage during the soldering > processes--they are filled during them. In operational use, fully filled > PTVs are > subjected to reduced loads on the copper barrel than empty ones, and PTVs > with voids in the solder fill will experience localized higher loads due > to the > stress concentrations---having said this, it needs to be emphasized that > this > is only significant if the operational conditions are severe, such > military and > automotive. > > Regards, > Werner Engelmaier > Engelmaier Associates, L.C. > Electronic Packaging, Interconnection and Reliability Consulting > 7 Jasmine Run > Ormond Beach, FL 32174 USA > Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904 > E-mail: [log in to unmask], Website: www.engelmaier.com > > > --------------------------------------------------- > 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 -----------------------------------------------------