I am trying to design a PCB which has high current traces on it.
PCB has 1 oz (35 um) trace thickness. Maximum current flow is going to be 12 Amps RMS.
I found this online PCB thickness calculator: https://www.eeweb.com/toolbox/external-pcb-trace-max-current
According to this calculator 5mm width is enough to hold 15 Amps current flow at 70 °C. However, due to some design limitations I need to get the PCB trace narrower as 2mm.
For 2mm width trace, the calculator points that it can hold 11.2 Amps current flow at 125 °C which is too high. To demonstrate the situation please look at the PCB layout below:
My question is, what happens if I put this PCB on work? I tried to keep narrow high current lines as short as possible but they are inevidable. I want to think that the thermal rise on narrow lines will be distributed over wide lines since they are conducted however, I am not really sure what will happen. Will those narrow lines burn out somehow? If so what are your practical advices?