Trace Width

[Nikos A.]

Hi every one,

I design a PCB which power trace should be cable to carry 16A. I found two online calculators claims that their calculations based on IPC-2221 standard.
However inserting the same parameters in both calculators there is significant deviation between the results

Calculator 1
https://www.4pcb.com/trace-width-calculator.html

Calculator 2
https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-pcb-trace-width

I attach the screenshots from the results

Thanks in advance

[Moriambar]

Hi.
In your digikey screenshot you screwed up the unit of measure (mil vs mm). I tried with mms and the results are comparable

[Nikos A.]

What an idiot!!

Thank you Moriambar

[Moriambar]

What an idiot!!

Thank you Moriambar

It happens

[Nikos A.]

The PCB looks like the attached

It is correct the traces to be wider than the through hole plated pads?

[pix3l]

It is correct the traces to be wider than the through hole plated pads?

Yes that's fine! You could also consider using a GND plane (if appliccable)

[Nikos A.]

This board is intended to mound a DC/DC converter.

https://eu.mouser.com/ProductDetail/TDK-Lambda/PAH300S2428?qs=sGAEpiMZZMvGsmoEFRKS8PKj03Y0BBZ9U9Zmx%252b%2F9di4%3D

This is an isolated converter meaning that I cannot apply common ground in both input and output..I am not sure whether or not is preferable to create power and negative planes instead of traces..

[pelule]

I get same result for both calculators at the same conditions...
/PeLuLe

[T3sl4co1l]

A note, IPC-2221 is quite old, and known to be off by a good bit.  This one uses IPC-2152:
https://www.smps.us/pcb-calculator.html

More discussion here:
https://www.ourpcb.com/trace-width-calculator.html

Note that trace width doesn't mean much over short distances, where component pins act as heatsinks keeping the trace cool, or where current is still spreading out from the pins themselves (a trace width of say 200 mils is not even meaningful for a length of 100 mils), or for pours/polygons that have arbitrary shapes.

For polygons in particular, the area of the shape matters as much as the width of the current path through it.  Even if current doesn't spread out over the whole area, heat does.  It helps to have wide pours, even if the added area isn't carrying any current as such!

You can also get 2 and 3 (and even 4) ounce copper for not much added cost these days.  You can also use identical traces/pours routed on both copper layers (assuming no trace crossings are needed), in which case merely 1 or 2 ounce will do.

Tim

[Nikos A.]

Thank you for your answer Tim!! The guide is really informative!!