Hello,

For those who have sort of experience making PCBs, how do you handle the width of the traces? Do you do the math for it or just put a width by yourself? I know that factors as current, temperature, and others, affect in the selection of the trace width and the placement of copper pour. I'm designing a board in which the high power side would need to handle (the worst case) a current of 30A.

Also, is there a standard width for low power? That is, when it comes to microcontrollers signals.

 

Here are a couple of trace width calculators. The limiting factor is heat. Thus, a smaller trace will carry more current if it is intermittent than if it is continuous. Signals are rarely a concern.

http://www.circuitcalculator.com/wordpress/2006/01/31/pcb-trace-width-calculator/
http://www.saturnpcb.com/pcb_toolkit.htm

 

When working with RF or high speed digital signals, the trace width is an important parameter for the trace impedance, which is crucial for a succesfull high frequency/speed design.
Most of the time using a simple calculator like the one mentioned above is sufficient as the heat is the major limiting factor. The power(heat) is ofcourse caused by the simple fact that: P=I^2*R

 

For high DC currents, consider multiple traces on different layers to reduce the width compared to a single trace. Note that traces on internal layers get hotter than external traces. Use multiple vias to ensure current sharing all along the route.

ak

 

AnalogKid beat me to it... another option to consider is using thicker copper (4oz per square ft)