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In most power supply designs either it's a bench PSU or LED driver etc, manufacturers use solder to increase current tolerance of the PCB trace:

  • Is it a valid choice or it's just to save money?
  • What are the disadvantages of doing this?
  • How much current can solder tolerate?
  • Does the resistance of the solder affects the circuit?
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1 Answer 1

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  1. It's a perfectly valid choice. An even beefier way is to use a wire jumper on the board but that costs manufacture time. This is nice, it just happens when you flow solder.

  2. I suppose you might get the odd solder bridge if your manufacture setup isn't perfect. But easily found and fixed. Also the trace is now exposed, which will make arcing or shorting more of a risk - likely not an issue but should be considered.

  3. No idea - look up resistivity of solder, do a geometric estimate of how much you increase cross sectional area. The % increase depends a bit on how thick PCB copper is, but I would think that in general you will at least double the current capacity. (It also depends on how wide the underlying trace is, so there is no fixed answer anyway.)

  4. Well yes - it lowers the overall resistance which increases current which lowers voltage drop and hence power dissipated in the trace, all of which is good. That's the whole idea.

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    \$\begingroup\$ Adding to 2. It exposes your traces to so you need to take creepage into consideration. \$\endgroup\$
    – winny
    Dec 31, 2019 at 9:50
  • \$\begingroup\$ I've never seen that on any of our products, If we need a lower voltage drop, we'll specify a higher copper weight (1 oz, 2 oz). Also, most (all?) of our PCBs are multi-layered, and we provide power & return with copper planes, unless the current need is low. Finally, we usually have no tracks at all on the outer layers unless dictated by signal integrity concerns. \$\endgroup\$
    – SteveSh
    Dec 31, 2019 at 11:59
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    \$\begingroup\$ yes, this is something more typically seen on high-volume low cost consumer gear, often with 2 later boards. And obviously not high speed. \$\endgroup\$
    – danmcb
    Dec 31, 2019 at 12:22
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    \$\begingroup\$ Or even single layer boards. Things like LED drivers and other small SMPSs are common applications. \$\endgroup\$ Dec 31, 2019 at 12:54

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