First, thanks for all the inputs. Second, Russell made an excellent point concerning the board material. I just found out that the boards in question are polyimide, that has a Tg ~ 250C. I doubt that going to 125C would make a difference - am I wrong on this assumption? When I get my copy of IPC-7721, I'll read it. I am curious if you have to bake a polyimide board above the Tg (~ 250C), what temperature do you go to and for how long? What is the heating rate and cooling rate? Or is this a case of On The Job Learning (OTJL) better known as trial and error? Lee Whiteman, PMP Senior Member Engineering Staff L-3 Communications East Telephone: (856) 338-3508 FAX: (856) 338-2906 E-Mail: [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Nowland, Russell Howard (Russell) Sent: Monday, February 01, 2010 3:41 PM To: [log in to unmask] Subject: Re: [TN] IPC-7721 LESSONS LEARNED After reading the original question I had to pull the spec and read it. I could see doing this for bare boards but the spec eludes that you can also do this on a populated board. Since you are forcing a board flat with components on it is anyone concerned about cracking components or solder joints here? The spec also states the bake temperature is 125 C but what if you are using material with a Tg of 170C? I have never tried this and I am a little curious. Russell Nowland Alcatel-Lucent Advanced Manufacturing Engineer Address: 14000 Quail Spring Parkway, Suite 300 Oklahoma City, OK 73134 email: [log in to unmask] Desk: 405-302-1660 Cell: 405-203-0034 Fax: 405-302-1622 --------------------------------------------------- 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 -----------------------------------------------------