I was hoping I could get some input on a problem we are having with a flex circuit. I have a 2 layer flex circuit that is shaped like a L. one leg is about 5 inches long the other leg is about 4 inches long At the corner of the L is a stiffener on both sides. The stiffener extends into both L sections a very small amount about .3 inches. Both ends of the flex have Omnetics connectors which are designed to be soldered onto flex circuits. The A28300 series. Some of the traces are 17 mils wide and some are 8 mils wide. The traces are spaced fairly evenly across the flex and are spaced like the omnetics connector which means you can't see through the circuit as the traces overlap from side to side. One section of the L flexs the other section is stationary. The bend radius for the flexible section is approximately .35 inches ( I am not positive of this number and will find out tomorrow but I know it is far more the 6X of the thickness). The flex is constructed as follows The core is AP-9121 with 1 oz copper on both sides. The coverlays are LF-0110 The adhesive for the stiffener is LF-0200 And the stiffeners are .028 FR-4 The edges of the stiffeners are beaded with emerson & cummings ecobond. I have spoken with the fabricator and they assure me that the copper is roll annealed and not electro deposited. The flex circuit has failed after less than 1000 cycles. The cycles are very slow and maybe 10 or 20 per day. The current going through the traces is very low on the order of 10 mA. We have had two circuits fail and they both have failed on the 8 mil traces. I have scraped the coverlay off of the flex and have concluded that the open is about in the middle of the flexible section but I can't see it. I would have expected to see an open at the end of the coverlay as I have seen this before. We have been potting the connectors to move the stress point from the omnetics connector pins to further down the flex past the end of the coverlay. I have a couple of questions. 1. Is there a way to remove the coverlay without using mechanical means I fear that I could screw up the sample by scraping it with a razor. 2. Does this surprise anyone that it would fail this soon with a bend radius that I know is large and only a 2 mil core? The flex has been removed many times from the system and reinstalled and I am still having a hard time convincing people that flex circuits must be treated with care. i.e. can't be laid on benches and smashed. Tomorrow I will get to get into the system and see the mechanicals but the mechys assure me that at no time is the flex stretched to the point of pulling the bend radius down. I soldered a wire onto the connector and ran a needle up and down the scraped flex and it sure seems as though it opens about in the middle of the flexible section. Anyway any input will be appreciated Thank you --------------------------------------------------- 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 -----------------------------------------------------