:: PCB copper current loading
general relation of current loading for PCB (based on IPC-2221, aka IPC-D-275/MIL-STD-275)
Width = (Current[Amps]/(k * (Temp_Rise[deg. C])b))(1/c))/ Thickness , in mils
(for multilayer) internal layers: k = 0.024, b = 0.44, c = 0.725
(top/bottom side) external layers: k = 0.048, b = 0.44, c = 0.725
for common copper clad PCBs, each ounce copper grade PCB clad is suppose to give a thickness of 1.37mils. However, as we all know all sellers boasts that their boards are of the standard cladding, nobody could really tell if that 1 ounce PCB was really truly fully done up with 1.37mils. so based on PCB product standard uncertainties, i will round down the thickness to 1.3mils and tabulate the below table based on a 10 degree celcius temperature rise. tracks widths required are the numbers in RED.
|PCB oz.||mils (thick)||1A||2A||5A||10A|
based on the above, it would be good to consider using bridging wires to carry extra current capacity where copper space is limited. this is a very nice resource list from ALTERA, on additional aspects of complexities of powering and PCB plane couplings (http://www.altera.com/technology/signal/board-design-guidelines/sgl-bdg-index.html)
as temperature rises, resistance increases, so it can be quite a domino effect if heat dissipation has not been considered carefully in high power situations. based on 60 degree celcius derating of cables (PVC jacket), even small cables can add a ton of additional current loading when compared to tiny 10mil PCB tracks.
|AWG||Diameter / mm||max amps|
commonly used PCB jump wires are AWG18-24. slapping on AWG18, saves much of copper "real estate" hands down.
however at high frequencies, skin effect happens. (http://en.wikipedia.org/wiki/Skin_effect) very very cool physics in that, it is also why inductive cookers are possible.