Hi, Tajudeen. I'm glad to hear from you.
It will make some difference, whether the traces are on the same layer or on different layers. I either circumstance, since we're dealing with internal board layers, the distance being measured is considered a through insulation distance. For Basic Insulation, there are no through insulation distance requirements and the insulation is evaluated on the basis of the Electric Strength Test. For cases where Supplementary Insulation or Reinforced Insulation is required between traces on the same layer, 0.4 mm is required. For cases where Supplementary Insulation or Reinforced Insulation is required between traces on the different layers is evaluated using Table 2M, relating to the specific board stackup. For some stackups, routine production line testing is necessary. BTW, Pollution Degree has no impact on internal layers of a board. Regards, Peter L. Tarver, PE [email protected] > From: Tajudeen Oladele > Sent: Saturday, March 20, 2004 11:32 AM > > I have been asked to explain how to measure the > Creepage between two > traces and the correct interpretation of UL > creepage requirements (Table > 2L) for secondary circuits. > > I will appreciate your well respected explanation > on how to measure the > creepage distance between two circuits, my > interpretation according to > UL60950 figure 2F is: > (1) Earthed Hazardous Voltage to Ground (Basic > insulation). > (2) Earthed Hazarous Voltage to TNVs (Reinforced > for TNV1, TNV2 or > TNV3). > (2) TNV2 to earthed SELV (basic insulation) > (3) TNV3 to earthed SELV or logic Ground (basic > insulation). > > Assumptions > - Each pair of traces are located in the inner > layer of a PCB. > - 10 layers board powered from dc source > - Working Voltages: Up to 100Vdc 90Vrms ringing voltage. > - PCB material group IIIa or IIIb. > - Pollution Degree 2 This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
