Hi Dee, Thermal relief is not specified within IPC documents, because the need for them is an "It depends." As you note, the type of soldering process(es) used as has an impact, whether you solder SnPb or SAC makes a difference, whether you have BGAs or not, the thickness of the innerlayers, the drilled hole diameter—how would you specify all of this? Werner -----Original Message----- From: Dee Stover <[log in to unmask]> To: [log in to unmask] Sent: Mon, 6 Apr 2009 2:58 pm Subject: [TN] when do vias require a thermal relief Where in IPC does it specify when a via connected to a plane must have thermal relief as opposed to direct connect? I would think it would have more to do with the assembly process than the fabrication process. For instance - wave, dip or drag soldering. You input is appreciated. Thanks, :-) Dee Stover [log in to unmask] x8489 Tech Associate II National Optical Astronomy Observatories www.noao.edu --------------------------------------------------- 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 -----------------------------------------------------