I have in my possession a 5mm thick printed circuit board. It comes from a 2000-era Sun Blade server, where it connected 4 redundant 70A power supplies.

5mm thick PCB

I also have a need to assemble some high current electronics - carrying currents of 140A or more. Currently, this is accomplished with laser-cut bus bars.

None of the PCB price calculators I've tried offer 5mm thickness, and none of the trace current calculators will go beyond the 35A performance figures offered by IPC 2221.

What should I expect to spend making such a thick, high-current PCB? And is there guidance available on how to design such a thing, besides extrapolating design rules from other sources that don't address such thick and high-current designs?

I'm aware you can solder bus bars atop your PCB but I'm particularly interested in understanding the design Sun went for.

Thanks for taking the time to read my question!

  • 4
    \$\begingroup\$ How much of that 5mm is copper, and how much is PCB? \$\endgroup\$
    – pjc50
    Jun 3 '19 at 7:28
  • 3
    \$\begingroup\$ If you shine a light at the right angle, can you tell how many inner layers there are in the PCB? \$\endgroup\$
    – winny
    Jun 3 '19 at 7:40
  • \$\begingroup\$ Is this a single voltage power supply? (server sounds like a computer and in current computers you have multiple voltages from a PSU, so I'm wondering if that might have played a role in the decision to go down a PCB route) \$\endgroup\$
    – Arsenal
    Jun 3 '19 at 9:28
  • \$\begingroup\$ @winny I can't tell, sorry. \$\endgroup\$
    – mjt
    Jun 3 '19 at 19:04
  • \$\begingroup\$ @pjc50 The edges feel like FR4, but due to the current the board carries I assume there's a lot of copper there too. \$\endgroup\$
    – mjt
    Jun 3 '19 at 19:04

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