It is typically done using a fixture made of Durostone. This prevents the selective solder process, whether wave-soldering or selective fountain/jet soldering, from filling other holes or pads where solder is not desired. Some examples of these types of fixtures can be seen at www.dmipallet.com. These people make these fixtures and are the best in the world at it. Believe me, I know, I've tried them all. Another method would be to use a temporary solder maskant that is available in peelable or soluble form (peelable, low ammonia is best). Both will contaminate your wash process, the peelable less so depending on how diligent the operator is at removing it prior to wash. Even when peeled some residue will remain on the pwb. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer Sent: Tuesday, April 18, 2006 8:46 AM To: [log in to unmask] Subject: [TN] Selective Soldering While inspecting a board produced by mass manufacturing techniques, I noticed the backside had been selectively soldered. The areas where through hole components are located appear to have been gasketed off (as detected by observing the no-clean flux residue) by either the fluxing or wave-like processing. Any ideas as to how that was done? Its clear that the board wasn't wave soldered as there are open PTH's in the areas not soldered. A multi-nozzle solder fountain? --------------------------------------------------- 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 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- 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 847-615-7100 ext.2815 -----------------------------------------------------