Arjen - Check the Conditions of Acceptability on the coatings you're interested in using. UL Recognized conformal coatings are, for the most part, are tested for use on the bare board (base laminate) and are not tested for use on solder masks.
Regards, Peter L. Tarver Nortel Networks ptar...@nortelnetworks.com > -----Original Message----- > From: pe...@itl.co.il [SMTP:pe...@itl.co.il] > Sent: Sunday, March 07, 1999 9:38 AM > > Dear Arjen, > > Solder mask is not considered as a conformal coating. You may > find UL Recognized conformal coating manufacturers in the UL > Recognized Component Directory under Coatings for Printed > Wiring Boards. To be able to use it on your boards, you must > obtain a copy of the UL "Conditions of Acceptability" (COAs) to > ensure that the coating is suitable for the ANSI grade (FR4, etc.) of > the board base material. > > For ITE (UL1950/CSA C22.2 950), you can use a UL Recognized > conformal coating or alternatively must subject the the PWB with > coating to all the applicable construction and tests in UL1950/CSA > C22.2 950 for coated PWBs. > > For ITE built for Europe, a US/Canadian Recognized/Certified > coating is usually not acceptable and the PWB with coating must > be subjected to all applicable tests in EN 60950 for coated PWBs. > > Best Regards, > > > From: "Arjen Dragt" <adr...@inverpower.com> > Date sent: Thu, 4 Mar 1999 14:59:16 -0500 > > > In looking at meeting CSA and UL spacing requirements for some of our > PCB's > > (in power supplies up to 600 V) some questions concerning the use of > > conformal coatings (allowing reduction of spacing) have come up. The > > information that I am seeking is for both CSA and UL; the wording that > they > > use concerning "coatings" on boards is similar, but not the same. > > > > "Coatings" on a PCB could include both a solder mask, and a strict > conformal > > coating. Does anybody have real-world knowledge as to whether or not a > > solder mask is accepted by UL/CSA as a "coating", and if so, under what > > conditions? > > > > Also, the method by which a coating is applied to a board could have > > considerable impact on the effectiveness of that coating. For instance, > > spraying a board will not get at any traces that are buried underneath > > components, whereas dipping will have a better chance of accessing those > > "hidden" areas. The standards that I am looking at say nothing about > method > > of applying a coating (the process). I assume that the decision as to > how a > > coating will be applied is left up to the manufacturer and board > supplier. > > Does anybody out there have best practices that are worth considering > when > > looking at our options for coating methods? > > > > Arjen Dragt > > > > > PETER S. MERGUERIAN > I.T.L. (PRODUCT TESTING) LTD. --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
