How do I calculate PCB trace max current? Traces on PCBs are small and therefore have small inductance levels.Ħ. Using the example numbers: L = 20 x 10^-3 * 12 x 10^-12 = 240 x 10^-15 henries or 0.24 pH, where pH is units of picohenries. How is PCB trace inductance calculated?Ĭalculate the PCB trace inductance, or "L," using the formula L = Zo * DLY. However, little if any reference material exists beyond this threshold, either in current or frequency.ĥ. Printed-circuit-board (PCB) design textbooks and IPC standards do a good job of discussing a PCB trace's dc current-carrying capability up to about 30 A. Under the same temperature rise that is 10☌, a 10mil-trace with 1oz copper weight is capable of withstanding current of 1amp at most and we rest assured that a 50mil-trace is capable of withstanding current larger than 1amp.Ĥ. How much current can a 10 mil trace carry? Each trace consists of a flat, narrow part of the copper foil that remains after etching.ģ. In electronics, a signal trace on a printed circuit board (PCB) is the equivalent of a wire for conducting signals. Nevertheless, the table above has been gradually replaced by IPC-2221 Generic Standard on Printed Board Design as a reference based on which a printed circuit board is accurately designed. How much current can a PCB trace carry?Īccording to MIL-STD-275, we are told that the maximum current a 50mil-trace can stand is 2.6amps. ( Note: the table above has been gradually replaced by IPC-2221 Generic Standard on Printed Board Design as a reference based on which a printed circuit board is accurately designed.)ġ. The following is a table of PCB carrying capacity. In short, the maximum amperage capacity of a PCB trace is a function of its width and its operational temperature.
![pcb trace width calculation pcb trace width calculation](https://www.allaboutcircuits.com/uploads/thumbnails/copper_trace_thickness_IA_AAPCB.jpg)
Maximum allowed difference in temperature between the PCB trace and the ambient temperature. The vertical height of the trace in the typical (textbook) PCB orientation As a result, as soon as power starts or order modification is implemented on trace, it's possible to cause a super large transient surge or even burning down of a trace between pads. The reason for such tragedy lies in too much solder paste on components or pins leads to an increased cross-sectional area while no modification occurs to trace between pads. It's not a rare condition in which engineers meet circuit boards on which some trace between pads is burned down as a large current is flowing through.
![pcb trace width calculation pcb trace width calculation](https://www.nwengineeringllc.com/article/img/width-1.png)
That's because apart from cross-sectional area and temperature rise, trace current carrying capacity also depends on other elements such as number of components, pad and vias.įor traces with many pads distributed, the tinning trace will perform an extremely higher capacity than ordinary traces. Although a simple formula can be directly employed to calculate maximum current carrying capacity of external PCB trace, cases in reality are not that simple and direct.