Jim, this is the way it has worked for a recent projects I worked on with UL NBK.
The conformal coating is called out by supplier and material type in the recognition report description, along with a minimum and maximum thickness requirement. In practice the UL field inspector only looks at the can or drum stuff comes in, to confirm it matched the description in the report. This is necessary to confirm the dielectric strength and flammability will be within the limits described in the recognition report for the CC material you have selected. Take a look at the guide information (QMJU2) and this will become clear to you. BTW, in a case of a PWB where the spacings satisfy the standard without a CC, we have been able to use an ordinary RTV coating material (QMFZ2) which has been evaluated by UL according to the UL 94 flammability requirements, but has not been evaluated for dielectric strength. However this coating is described in the recognition report and the UL field inspector confirms that is what you are using. Best Regards, Lou Aiken, LaMer LLC 27109 Palmetto Drive Orange Beach, AL 36561 USA tel ++ 1 251 981 6786 fax ++ 1 251 981 3054 Cell ++ 1 251 979 4648 From: Sotherden, Jim (IndSys, GEFanuc, NA) <[email protected]> To: <[email protected]> Sent: Tuesday, December 16, 2003 8:23 AM Subject: question concerning conformal coating of PWB > > If we have some of our boards conformal coated, As long as we use a recognized conformal coating, does the process have to be under a follow-up service ? The boards are not coated because of spacing, but rather because of customer request. I tried to contact UL but could get no straight answer. > > > Thanks, > > Jim Sotherden > Agency Coordinator/Test Engineer > > gGE Fanuc Automation Americas > Route 29N & 606, Charlottesville, VA 22911 > PH: (434) 978-6224 Fax: (434) 978-5102 Dial Com *277-6224 > Email: [email protected] > Web: www.gefanuc.com > > > > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ieee-pses.org/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc > > This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
