John: Two reasons for overcoating a flex/solder joint interface: 1. Insulation 2. Strain relief Two considerations: 1. Adhesion to the flex dielectric 2. Stress concentration Most flex is polyimide-based; polyimides are very difficult to adhere. Surface must be extremely clean and receptive to the overcoating material. Pay considerable attention to the strain relief/stress concentration issue---be sure that the added material doesn't worsen the situation! A slightly flexiblized system is likely to be your best choice both because these systems tend to show higher adhesion because slightly forgiving, and because they tend to spread stress. Tom Stearns 3 Brander Court Nashua NH 03063 603 889 2522 --------------------------------------------------- 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 -----------------------------------------------------