Help! I am designing flexible circuits that seem to be over the IPC-D-275 charts. Or any of the current capacity charts being that they are all the same. I have circuits that utilize a ARINC 600 size 3 connector with insert A,D having 150 x #22 AWG, B,E 60 x #20 AWG, and C,F 100 x #22 AWG. My problem is with the "Input Current", The 22 AWG circuits are to carry a current of 3 AMPS and the 20 AWG are to carry 5 AMPS. The hole pattern for the 22 AWG is on 0.100" centers with a .035" hole and a .065" pad, leaving .035" spacing. The 20 AWG pattern is on 0.150" centers with a .043" hole and .073" pad, leaving a .077" spacing. First, a question with the charts, is a rigid flex considered an internal layer? Are any flexes considered internal becouse of a kapton cover coat, and/or a stiffener material? If considered internal, and I use a high TG material (Polyimide), could I not go higher than the 45 deg C rise above ambient? How? Also, in IPC-D-275 pg.10, note 5 states that for "groups of similar parallel..." isn't that really the same as note 4? I do NOT know how many of these circuits will be "on" at the same time and for how long in time. I would think that if I put even 3 amps into parallel circuits acording to the internal chart: 3 amp at 45 deg C rise, with 2 oz copper equals a .030" trace (I have room for a .020" trace) that my flex would heat up past that point. Now the 5 amp lines! Am I missing the boat? Is there another way? Dan *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************