Arjen, Board with only solder mask is considered as non coated.
Conformal coating is the type accepted to be allowed to reduce the spacing between trace. However be aware that your safety agency will have to test that coating. The test is described in UL1950 (I do not remember the section and do not have the standard at hand now). Also an audit of your process for applying the coating will be performed periodically. This is in addition to the normal safety audit. Daniel Sicard Compliance Engineer / Ingénieur Certification Transport Systems Business Unit RELTEC Corporation Tel: 514-685-1737 Ext. 4631 Fax: 514-822-4054 Web: http://www.relteccorp.com E-mail: mailto:dsic...@positronfiber.com > -----Original Message----- > From: Arjen Dragt [SMTP:adr...@inverpower.com] > Sent: Thursday, March 04, 1999 2:59 PM > To: EMC-PSTC Listserv > Subject: PCB coating questions > > 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 --------- 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).
