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I was working on a bunch of PC PSU organ donors and noticed that on lots of them through all the wires that lead the power to the outside there were wires soldered, and lots of solder added. This is probably to increase current capability.

I only today thought about it, so did not take any photos, but it looks similar to this: enter image description here

Now an ATX PSU looks quite crowded and there is probably not enough place for wider traces, so I was wondering if this is acceptable/good design or if I should avoid it and go for proper traces where I can; and why should I do what.

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  • \$\begingroup\$ Thicker traces are going to be much cheaper than adding that process. \$\endgroup\$
    – Matt Young
    Commented Dec 23, 2014 at 14:29
  • \$\begingroup\$ @MattYoung: Probably a language issue here, I meant to say wider. Also those wires are copper. \$\endgroup\$
    – PlasmaHH
    Commented Dec 23, 2014 at 14:30
  • \$\begingroup\$ My comment still stands either way. \$\endgroup\$
    – Matt Young
    Commented Dec 23, 2014 at 14:33
  • \$\begingroup\$ Another alternative: A 2-layer PCB of the size of the section shown on the picture may cost $2 in some volume. Make it 4-layer may cost around twice as much. ...If this is a production assembly, how do you even write the spec to say what is acceptable for something looking like the picture. \$\endgroup\$
    – rioraxe
    Commented Dec 23, 2014 at 22:41

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Soldering wires onto a PCB like that definitely increases current capability. Whether that's good design we can't of course answer without knowing the design criteria.

Downsides of this method are that it takes significant manual labor in production, therefore will reduce yield because people make mistakes, cause more unit to unit variation than othewise, and won't be as corrosion resistant because there won't be a layer of solder mask over the conductor.

Whether these tradeoffs are "good" or not depends on factors we can't know. For example, if this board will be manufactured in a part of the world where you can pay someone a bowl of rice and $.50 a day, then it makes a lot more sense than where you have to pay US minimum wage.

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    \$\begingroup\$ Also, even with manual labor costs (the solderers will get pretty good (and quick) with practice), it may well be cheaper to beef up a board with voltage drop problems than to replace the board entirely. This at the same time that the board is being revved to fix the problem in future units. \$\endgroup\$
    – WhatRoughBeast
    Commented Dec 23, 2014 at 15:03
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Adding solid copper bus wires to high current paths on a circuit board is more common than one would think. I've seen it done on power supply boards and even on a computer board or two. In the case of the computer board I believe it was done to solve a problem with too much voltage drop across an internal power plane segment. A later version of the computer board did not have the wire added so the problem was evidently corrected in artwork design.

In one TV power supply board that I recently looked at the copper was on a one sided circuit board and the added wires were installed as parallel jumpers from the opposite side of the board.

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    \$\begingroup\$ Parallel jumpers make me wonder if pcb stiffeners are (mis)used for that too \$\endgroup\$
    – PlasmaHH
    Commented Dec 23, 2014 at 15:14
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    \$\begingroup\$ @PlasmaHH - If you search around on the web for a component called a "PCB bus bar" you can find a solder in type component that can be used to handle large amount of current across a PC board. Many of the online web sites specifically also advertise their bus bars as also being PCB stiffeners!! \$\endgroup\$
    – Michael Karas
    Commented Dec 23, 2014 at 15:31

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