The fab should be able to support your request, if not Trace Labs can help you. All shops should have lab capabilities. The defect you have describe is hard to review from words but here's a couple of things to consider/review. First the material you have selected is very good material. How did they plate the PTH holes? There's only 2 methods panel/pattern plate which will plate all the outside copper and gives you ED copper where you don't want it or button plate where you only plate the PTH only leaving RA copper for flexibility. It's always good to know the bends/folds areas when creating your drawings so it gives the fab house a idea what the flexes requirements are in the product or identify the bend locations on the drawing. Check the copper grain direction of the part against the panel. Grain direction becomes very important when you are looking for many cycles. Of course you have the obvious situations when processing a flex in mechanical conveyors with etch bits, handling etc. It's not easy! If they are plating up the entire circuit surface maybe you are starving the adhesive when using 110 for coverlayers. Maybe going to 210 will help with better adhesive encapsulation. Without really seeing the problem it's hard to come up with root cause but these are some ideas for you. www.quickturnflex.com Thank you, Jim Mahoney Quick Turn Flex Circuits, LLC Applications Project Manager P# 603-821-7071 M# 603-305-6250 ** This email and all attachments have been scanned prior to being sent** Confidentiality Notice: This page and any accompanying documents contain information that is confidential, privileged or exempt from disclosure and is intended for the exclusive use of the addressee. If you are not the intended recipient, you are hereby notified that any disclosure, copying, distribution or use of the contents of this information in any manner is strictly prohibited. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of John Foster Sent: Thursday, May 14, 2009 8:52 PM To: [log in to unmask] Subject: [TN] FLEX question 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------