Excessively large traces consume valuable PCB space while offering highly diminished returns. For low power signal traces it is generally advised to keep traces small to increase the available space available for routing. The downside of reducing board size is that it can limit the available space to route traces. The size of a PCB is directly connected to the cost of the PCB, so in general PCBs are kept as small as possible. For these low power signal traces, we must look at other characteristics of the PCB to determine the width. It is important to note that this value is a minimum width required to meet the design criteria inputs.ĭetermining the width of a trace based on the current demands is important for most power traces and high power signals, however, most traces on PCBs pass signals which draw negligible current. After entering these values you will be presented with a calculated trace width. PCB Trace Width Calculator from These trace width calculators will prompt you to enter design specifications such as the thickness of copper, the maximum amperage that will pass through the trace, the length of the trace, and the acceptable increase in temperature due to the resistance of the trace dissipating power. Luckily, there are a handful of trace width calculators available online that will help guide the choice of trace width when considering ampere capacity.įigure.
Knowing the resistance of a trace and the maximum current that will be passed through it will help inform which width to use.Ĭalculating the resistance of a trace is not trivial and can involve a lot of work. All traces will have resistance and it is important to consider this when selecting widths. Often we think of traces as zero resistance connecting wires between two components, but this is certainly not the case. Passing large currents through a trace will cause it to dissipate heat, and given enough current (and time) the trace will be destroyed by either burning through, or delaminating from the PCB and breaking the trace. The size and pitch of the pads that the trace will be connecting toįor any given trace on a PCB there is a maximum amount of current it can handle before failure.The current capacity of the trace (how much current will flow through it).The important characteristics to consider when selecting a trace width include: With the exception of special cases such as very high frequency signaling and high power applications these rules can be applied to every PCB. When picking trace widths to route a PCB, there are a few rules and guidelines that will help inform the value of the trace width.