Inputs:
Optional Inputs:
results for internal layers:
Results for External Layers in Air:
FAQs

Very cool PCB width tool! I would like to know its limits though. I entered a 65 amp current requirement and it returned a track width that must be incorrect.
The original graphs that this tool is based on (published in IPC2221) only cover up to 35 Amps, up to 0.4 inches of trace width, from 10 to 100 degrees C of temperature rise, and copper of 0.5 to 3 ounces per square foot. The formulas used here will simply extrapolate when the values are outside of these ranges.

I used your PCB trace width calculator. Intuitively I would say the required internal trace widthwould be less than the external case since the external trace can peal off; the opposite is true according to the calculator???? Why?
In air, the external layers have better heat transfer due to convection. A good heat insulator blankets the internal layers, so they get hotter for a given width and current. Since the Trace Width Calculator tries to control the temperature rise of the traces, it makes the internal traces wider. In vacuum, or in a potted assembly, you should use the internal layer guidelines even for the external layers.
How it works
The trace width is calculated as follows:
First, the Area is calculated:
Area[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c)
Then, the Width is calculated:
Width[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz])
For IPC2221 internal layers: k = 0.024, b = 0.44, c = 0.725
For IPC2221 external layers: k = 0.048, b = 0.44, c = 0.725
where k, b, and c are constants resulting from curve fitting to the IPC2221 curves
need help?
If you have any questions or problems about the calculator, please send us your queries at support@candorind.com