I have found PSA materials tend to be hydroscopic and can blister during the reflow process. I have worked with two different assemblies that required baking prior to the SMT process in order to avoid opens and pillowing. Regards, Ted T. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Dan Skweres Sent: Friday, November 20, 2009 9:22 AM To: [log in to unmask] Subject: Re: [TN] Stiffener on Flex Circuit Depending on the type of adhesive process (thermal set or PSA tape) they could be applied at different stages. Typically they're done in panel form using external tooling holes for registration. If however, PSA tape is being used to apply then they could be applied in pc form and aligned by eye. As far as the size of clearance in the stiffeners normally they're slightly larger than the underlying pad that you plan on wicking solder to. If you're wanting a S/S flex without pads on the side your applying the stiffener to, then you could go smaller. It's best to contact the potential supplier and seeing what they recommend that will best fit their processes and get you what you need. Dan S. --------------------------------------------------- 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 -----------------------------------------------------