Does putting solder on high current PCB tracks help?
Why Electrical Engineering Stack Exchange recommends it
Electronics Stack Exchange answerers point people to it as empirical evidence when asked whether adding solder to PCB tracks increases current capacity.
Recommended by 1 people across 1 different months, 2014 to 2021.
What it is
A short 4-minute test by Mike of mikeselectricstuff measuring how much resistance drops when solder is added on top of a PCB copper track. It is a hands-on bench measurement made as a companion to a related EEVblog discussion on tinning traces.
What people said
Recommends bigjosh · 2015-10 · Electrical Engineering Stack Exchange · on “Adding solder to PCB traces to increase current flow”
It does work, but it is hard to model reliably and you should use empirical testing to see how well it works for your boards, process, environment, solder. There can be a lot of variance from little things that are hard to predict and measure. For example, are you soldering by hand or running though a wave machine? The resulting solder profile cross sectional area can be off by 50% or more depending on which process you use- and neither of them resemble a half circle :) . EEVBlog feauted a video where he tests exactly this question... EEVblog #317 - PCB Tinning Myth Busting [LINK] And a similar video... Does putting solder on high current PCB tracks help? [this video]
Cites Daniel · 2014-07 · Electrical Engineering Stack Exchange · on “PCB Track Width for High Current”
What matters is your total copper cross section and the trace length. Both of these numbers contribute to the total resistance of the trace (if that's important) and the resistance per unit length which contributes to temperature rise (if that's important). If it's a DC current, there are no issues that I can see. For higher frequencies, you might be generating magnetic noise if your return trace is farther away. (Magnetic noise is proportional to current x current path loop area) Here is a website that can help you calculate the total amount of copper based on the target temperature rise: [LINK] Edit: Another way to go on the cheap side is investigated by Dave Jones and Mike: EEVblog #317 -
Cites Armandas · 2015-04 · Electrical Engineering Stack Exchange · on “Designing a high-power PCB”
I've worked on PCB-based bus bars before (over 1kW total power) and we were able to get by with just a PCB, no external bus bars. Here are some of the things to consider: Copper thickness: use 2oz / 70um (or greater) copper for your PCB. Add solder islands to further increase current carrying capability. [ 1 [this video] ] [ 2 [LINK] ] Calculate the temperature rise and add forced cooling if necessary. Here's a quick example calculation using the Saturn PCB Toolkit:
Cites Spehro 'speff' Pefhany · 2021-04 · Electrical Engineering Stack Exchange · on “How to add solder traces on PCB surface”
They removed the solder mask and the board was wave soldered. Dave Jones [LINK] found it reduces the resistance of 1oz copper by 50%, so the equivalent of 2oz copper in resistance (and higher in thermal capacity, which might come into play for surge currents). His methods were good. He depended on looking up the copper thickness. Mike of mikeselectricstuff [this video] found a 30% reduction. His methods were a bit less good than Dave's but good enough (verified when Dave removed the solder and it was verified that the thin remaining layer did not significantly affect the resistance). I did not see him attempt to find the thickness of the copper- he assumed it was 1oz. If it was actually 2oz then