In a message dated 2/1/2002, John Juhasz writes:
> In short, they noted that while possible, it is difficult to maintain the > pollution degree 1 in a printed circuit. Typically the pollution degree > is applied to 'potted' items. > Hi John: In the first edition of EN 60950 there was little guidance on how to treat internal layers of a multilayer board. This led to the kind of discussions that you describe, with each NRTL developing their own interpretation of what requirements to impose. In the current (third) edition, clause 2.10.5.3 explicitly addresses internal layers and eliminates most of the ambiguity. Depending on the construction and compliance method chosen, it is not always necessary to perform routine tests or some of the other onerous tests that used to be imposed. If a manufacturer wants to qualify a solder mask per clause 2.10.6, however, there are still many additional tests that will be required. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 http://www.randolph-telecom.com
