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I'm designing a 150Amp controlled rectifier and I'd like to know how to distribute the current using a multilayer design.

Currently, I have a 4 layer design containing: Top Layer: 6oz, Vdc+ and Vdc- Internal Layer 1: 1 oz, Vcc and some control traces. Internal Layer 2: 1 oz, GND and some control traces. Top Layer: 6oz, Vdc+ and Vdc-

I have used online calculators to know the minimum width of the traces, and for physical restrictions, there are some cases that I'm close to the minimum. Then, I have to go to a thicker board (which is not an option because our provider works up to 6oz). Then, I was thinking of using the internal planes to distribute some power current too:

Top Layer: 6oz, Vdc+ and Vdc- Internal Layer 1: 1 oz, Vdc+ and Vdc-, Vcc and some control traces. Internal Layer 2: 1 oz, Vdc+ and Vdc-, GND and some control traces. Top Layer: 6oz, Vdc+ and Vdc-

Vdc+ and Vdc- will be connected in the four layers through capacitors-IGBTs vias. The internal planes will have a bigger resistance but lower current, but I'm not sure about the heat dissipation and/or other technical problems that might arise.

I'd like to know if some of you have some experience in this subject and can provide me with the pros and cons and/or providing some references that deal with similar problems...

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  • \$\begingroup\$ I wouldn't call myself a professional but I did do something similar at work and got paid for it. 4 layers, 2.5oz outer, 2oz inner, and at 40A no detectable heating above ambient using the thermal camera. The narrowest trace was about 1cm and no heating there. Often I had the same current running in the "same trace" in multiple layers, sometimes internal layers, and I stitched them together with vias. \$\endgroup\$ – DKNguyen Mar 6 at 22:59
  • \$\begingroup\$ You know, if you're really worried you should see if they can't just provide you with a small blank sample (if they just have some blank scraps laying around, although I think they have to plate up to 6oz rather than use 6oz stock). Cut some lines into it with a knife or dremel and run some current through it and see how much it heats up. Even if they have no stock, it helps to get an idea if you just do the same with 1oz. \$\endgroup\$ – DKNguyen Mar 6 at 23:01
  • \$\begingroup\$ I should add that even at 2.5oz I needed a preheater to solder the PCB. I use a JBC iron and that was still not enough. You would definitely need one. \$\endgroup\$ – DKNguyen Mar 6 at 23:04
  • \$\begingroup\$ Or see if they have some rejects. \$\endgroup\$ – TimWescott Mar 6 at 23:24
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    \$\begingroup\$ You could add bus bars (one company's page shown -- they're not the only one, and it's something you could have made locally if it made sense) -- e-fab.com/products/pcb-stiffeners \$\endgroup\$ – TimWescott Mar 6 at 23:28

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