For a 14A current path, is it acceptable to route through vias, or is it better to split the current across wider traces on multiple layers (for example, 120 mil on top and 120 mil on bottom)?
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I have done parallel copper layers in projects in order to minimize current path width limitations. This can also improve thermal dissapation.
Vias can also be done however you need to make sure the vias can support the current. Paralleled vias may not equally split current so you should be sure to add a derating value when deciding the number of vias to be used.
As far as which is better - that likely depends on specific project limitations that you are required to design within. In any case, be sure to add a much copper as practical to keep the assembly as cool as possible.
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Vias do add resistance, so their current-carrying capability depends on their size and quantity. Another important factor is the current path, whether the current stays on one layer or has to transition between layers (for example, source on top and load on bottom). If the current has to pass through vias, they become part of the current bottleneck, so they need to be sized and distributed accordingly.
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Current won’t split evenly between parallel paths. In practice, some imbalance always exists due to small resistance differences, whether from trace geometry, via plating variation, or layout asymmetry.
A common approach is to apply a derating factor when sizing parallel conductors. Adding 20-30% margin helps ensure no single path is overloaded. This principle applies equally to multiple traces across layers and parallel via arrays.
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Copper weight plays a big role here, a 120 mil trace at 2 oz handles significantly more current than the same width at 1 oz, so your stackup choice directly affects whether splitting across layers is even necessary. Also, if you do go with parallel traces or vias, keep the layout symmetrical. Asymmetric placement creates unequal path lengths, which worsens current imbalance regardless of how well you’ve sized the conductors.
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One more thing to consider is thermal concentration at transitions, especially around vias. Even if the average current is within limits, vias can create localized hot spots due to their smaller cross-sectional area and poorer heat spreading compared to wide traces. If the current must transition layers, it’s often better to use via arrays spread over a larger area rather than a tight cluster. This helps distribute both current and heat more evenly and improves reliability over time.
If you split current across layers, make sure the corresponding return current has a clear, low-impedance path nearby. Spreading current without considering the return path can increase loop area, which leads to higher inductance, noise, and potential EMI issues. So when using multiple layers, think in terms of current loops, not just individual traces, keep forward and return paths closely coupled to maintain good electrical performance.
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Another aspect to watch is assembly and solderability at high-current nodes. If the component (connector, terminal, etc.) only connects on one side, the current still has to funnel through a limited copper area at that interface, regardless of how well the traces and vias are sized.
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Also, pay attention to connection points. Even with wide traces and multiple layers, current often bottlenecks at pads or terminals. It’s good practice to locally widen copper (using pours or teardrops) at these points to reduce resistance and improve reliability.