Jim and Gary, I forgot to mention in my first email that the product was only to have the two rigid boards (assemblies) coated. The vendor over sprayed the AR conformal coating onto and between layers of the flex. The flex purposely made up of separate layers to make more flexible. The assembly drawing states the flex be "generally free of coating". I was trying to find out in the design spec (IPC 2223 paragraph 4.4.2) the meaning of "debonding of the flex coating". What coating is one of my question. Another question is can or will the AR coating actually cause issue with the flex as Gary Ferrari stated "If it is not compatible, then it could very possibly break down the material, exposing the circuits beneath and increasing the risk of adhesion breakdown of the copper to the flexible substrate." We are changing the drawing to indicate not to conformal coat the flex but we have a significant number of assemblies where the coating on the outside was removed but still have some coating trapped in between the layers. We can bend the flex and the coating will start to flake off. Assembly goes into a small box and has not moving parts where the flaking coating can cause mechanical issues. I am wording but trying to seek as much information from this forum which is the best. Thanks, Jon -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of James Mahoney Sent: Thursday, September 04, 2008 7:31 AM To: [log in to unmask] Subject: Re: [TN] FLEX CIRCUIT AND CONFORMAL COATING I would not recommend any conformal coating that is spray deposit but I would consider pyraline coating process after installation. Repeated flexing will cause cracking and peeling off from the Kapton. Also may consider some type of surface prep to rough up the flex material to enhance the bond strength. Thank you, Jim Mahoney Quick Turn Flex Circuits, LLC Applications Project Manager P# 603-821-6571 F# 603-821-5723 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 Roberts, Jon Sent: Wednesday, September 03, 2008 5:42 PM To: [log in to unmask] Subject: [TN] FLEX CIRCUIT AND CONFORMAL COATING Does anyone know what IPC spec that addresses if flex circuit between two rigid boards can or cannot have conformal coating? I found Design spec IPC 2223 that addresses in paragraph 4.4 that it generally should be free of conformal coating due to make it stiff or debonding of the coating. Not sure what coating that is referring. Any ideas, thanks in advance, Jon This communication is intended only for use by the addressee(s) named herein and may contain business confidential and/or legally privileged information. 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