Duane, My understanding of clause 2.9.5 was that it was for conformal type coatings and not solder resist type coatings. The test houses we use don't consider solder resist to be any form of insulation, although it must modify the CTI rating.
Has anyone done any electric strength testing between conductors with varying distances across the outer surface of PCB's and are willing to share their data. We had some special PCB's manufactured and the results were not what we expected, we have also performed air gap testing (not in a vaccum) also with unexpected results. I'm happy to discuss this outside of this forum if you prefer. Regards Richard Steele Equipment Engineering Group Fujitsu Telecommunications Europe Limited Duane J. Marcroft wrote: > > Richard, > > The PCB coating is silkscreened. Because it is a silkscreen, it is by its > very nature unreliable as an insulator. Silkscreening produces many voids > in the surface (air bubbles) and too much variation in coating thickness. > As a consequence it cannot be considered. > > To be an viable insulator (in calculating creepage and clearance) coating must > be at least 2 layers of film (sheet or tape of Kapton.. etc). In the > opinion of many in the industry a silkscreen coating is too unreliable to > be considered. > > Duane Marcroft > Telecom and Data Communications Consutant > > ___________________________________ >
