Doug, I've been recommending clearances of 2mm (0.080") for over 20 years. I have also used 2mm for PCB's that are required to meet UL 1950. The creepage and clearance for Tip-GND, Ring to GND, Tip-GSELV and Ring-GSELV have never been a problem.
With one exception: Some unscrupulous PCB Mfgr's cut there materials costs on multilayer PCB's by purchasing board material for 6 layer, 10 layer and 16 layer PCB's. To makeup a 4 or 8 layer board they mix and match layer material to get the correct thickness. This has cost me and companies I worked for some tough problems to solve. That is to say if you are relying on a certain amount clerance or insulation between layers this maybe a problem. The problem's I experienced were caused by pin holes in the layers and arcing occured between traces that were on opposite sides of a layer and opposites sides of the barrier. This problem only occured when we changed to a new board vendor. My advice is not count on the clearances between layers. What passed today might not pass tomorrow. On last comment I'm using 3.5mm (0.140") of clearance for worldwide designs. Regards, Duane ___________________________________________ On Fri, 27 Sep 1996, Doug McKean wrote: > Hello Treggers, > > Our PCB house has given me a conundrum for T1 Ring/Tip/Ground clearances. > They declare FCC 68 and UL-1950 3rd edition conflict with clearance > recommendations. > > I'm not sure to what they refer - test voltages versus recommended > clearances(?). > > I have always recommended min. of 0.02" between R-T and min. of 0.03" > between R-G and T-G as I think may have been posted here before. > > Before I walk into a rat's nest, > does someone know what they are talking about specific with each standard? > > ******************************************************* > Doug McKean > [email protected] > ------------------------------------------------------- > The comments and opinions stated herein are mine alone, > and do not reflect those of my employer. > ------------------------------------------------------- > ******************************************************* >
