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How are PCBs that handle ultra-high current designed?

For example, there are IGBTs on Digi-Key that are rated at > 200 A and can be soldered onto a PCB.

How do those parts get utilized? Wouldn't the traces have to be incredibly large?

ocrdu
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RGB Engineer
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1 Answers1

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To manage the current you need to manage the heat. You do this by:

  1. Reducing the amount of heat produced and
  2. Getting rid of the heat you do make

You accomplish (1) by making your current handling traces as thick as possible. This includes width and thickness. Once you run out of width, you need to start making the traces thicker: 2, 3, 4 oz or even more but soldering/rework gets trickier. Some designs will leave solder mask off of the traces and coat them in a layer of solder (cheap and easy, but solder is about 1/10th as conductive as copper). You can also get busbars to solder or press-fit into the board.

(2) is accomplished by putting traces on multiple layers and connecting them with vias, especially for heat produced in-package. Conduction is also a viable method of heat management if you have big heatsinked packages or off-board connectors. For specialized applications like LED boards, metal-core PCBs are also useful at spreading heat out.

vir
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  • I was reading that there are also these things called "Bus Bars" that are made to carry very large amounts of current > 100A. – RGB Engineer Feb 15 '23 at 19:30
  • Yes, they're just big lumps of copper or aluminium. You can also just use wire. But 100A isn't actually that much on a multilayer board with thickened copper layers; modern motherboards and graphics cards have core voltages around 1V and can use 200-300W, so that's hundreds of amps. – Polynomial Feb 16 '23 at 00:37