Hello Technetters, I have a family of boards that to achieve 100% hole fill (I'm building to IPC-A-610C class 2 - yeah, I know 100% isn't required), I need to preheat the topside of the board to approximately 310F at about 1.75 ft/min (maybe a 6-7 second dwell). I usually follow the 180-220F rule-of-thumb, so I'm asking: What are the potential or real problems? Also, the flux is OA. The family of boards are .050-.070" made out of either FR4, GE TEK, or NELCO 4000-13. They are also waved in a selective soldering pallet with an aluminum plate on the topside over 90% of the components to hold them in place per a design specification. Will I damage the board or components (with immediate noticeable failures or latent field failures)? Or is the 180-220F guideline more from the old WS6536/Mil-Std-2000 days and todays fluxes, boards, and components can handle the temperatures? Thanks in advance for the help, Al Kreplick Sr. Mfg. Eng. Teradyne, Inc. 500 Riverpark Drive Mail Stop NR500 1-1 North Reading, MA 01864 Tel: 978-370-1726 Fax: 734-661-5352 Pager: 888-561-6485 --------------------------------------------------- Technet Mail List provided as a free 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------