ANSI IPC-2221A PCB Trace Width Calculator |
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ANSI PCB Trace Width CalculatorHelp us improve these pages - If you have any comments about the content here or would like to see improvements or a different calculator added, please use the guest book. New features in this version include:
This page calculates approximations to the ANSI / IPC-2221/IPC-2221A design standards for PCB trace width - this is the replacement for IPC-D-275. The approximations and rationale are described in Trace Currents and Temperatures Revisited by Douglas Brooks, UltraCAD Design, Inc. The figures returned by this calculator are to be taken as a guide only. I will not be held responsible for any mishap or loss, either direct or consequential, that may occur as a result of relying on the figures herein. The trace width formulas are: Internal traces : I = 0.024 x dT0.44 x A0.725
External traces: I = 0.048 x dT0.44 x A0.725 where: I = maximum current in Amps
dT = temperature rise above ambient in °C A = cross-sectional area in mils² Please note that IPC-2221(A) equations are subtly different from those in IPC-D-275 in that they are typically slightly more conservative and are impicitly derated to compensate for manufacturing effects, i.e. they should be more reliable in practice. The values calculated here compare very closely with those derived by the UltraCAD PCBTEMP utility, and like the diagrams in the standards documents, are valid up to 35A for external traces and 17.5A for internal, 400mil widths and a maximum temperature rise of 100°C. I've added a recommended track clearance value based on the UL rule: clearance in inches = 0.023" + (0.0002" x V)
The formulae as it stands is simplistic, but is reasonable for V > 50. Note
that there are many international standard for this sort of thing, e.g.
EN60065:1994, which for European mains of 230V, allows for about 120mil
for Class I (protected by earthing) and 240mil for Class II (double isolated).
Note that if there is no conformal coating and the environment is dirty/humid/condensing
then all bets are off. Please read the standards documents yourself. Change a value in an input field, then press TAB to move to the next field. The results tables will be updated automatically. Back |
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© 2003-2023 Nick de Smith Webmaster Last edited: 1st February 2023 |