I don't think it is an issue of what kind of deposition process you have, but more the rigidity and flexibility of the coating. Silicone conformal coatings (though a tool of the Devil) are generally quite flexible and elastic. Acrylics, urethanes and epoxies are in more common use and are more rigid. I would ask the question of why you want to coat the flex circuit in the first place? The conformal coating is not going to add any insulating characteristics to a polyimide based resin (Kapton), so you don't really gain anything and only set yourself up for failure. Even Parylene will crack and flake if the bending is great enough or repeated enough. When we have flex circuitry here at Rockwell that is soldered to rigid boards, we just coat the solder connections, which does not flex, and leave the rest of the flex alone. Doug Pauls James Mahoney <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 09/04/2008 07:30 AM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to James Mahoney <[log in to unmask]> To [log in to unmask] cc 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. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution, disclosure or copying of this e-mail and its contents is strictly prohibited. If you have received this e-mail in error, kindly notify the sender by replying to this message. In addition, please permanently delete the message and any attachments without copying or disclosing the contents. Thank you for your cooperation. 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