Well basically what I've been asking is if silver solder has a lower resistance as I wish to load my PCB tracks carrying 20 amps with solder as the recomended current for the tracks without is 6 amps. I've been told that ordinary solder has a resistance 10 times higher than copper and with this increased resistance come reduced ability to dissipate heat so I just trying to not shoot my project before I've even begun
I think I understand what you mean, it sounds like you're making a pcb yourself and adding solder to certain tracks to thicken them for a higher current load. I don't think the small silver content in silver solder will make a difference over any other type for this application. You're still going to be dealing with almost the same
intermetallic resistance given that the vast majority of the solder (>90%) is either tin or tin and lead. This resistance is very small, and is not likely to be a problem even at the currents you describe. I believe the inherently higher resistance of the solder and intermetallics actually generates more heat as opposed to reducing the trace's naked dissipation
It sounds as though you're following instructions from somewhere. I'm assuming they recommend adding solder to the traces to improve it's current carrying capacity primarily because you're multiplying the cross section of the conductor. This may work, but it seems unlikely to help to the degree you reqire (6A to 20A). You might consider using blank board with a thicker copper layer. If you haven't found it yet in your travels, here's
a good pcb trace width calculator for current that's good to 35A according to the comments. By playing with it a bit you can see how much you benefit by increasing the copper coating on the board from 1oz to 3oz (above which it can be difficult to find). A word of warning: if you're etching the board yourself you will have to use caution with thick copper boards because they will undercut their traces much more easily than thinner boards. This makes it much easier to lift thin traces by accident, for example, and reduces the effective cross section.
If you have the time and materials to experiment, you may try soldering a wire along the trace as well to improve it's cross section. Keep in mind that anything you put over a wire or a trace will thermally insulate it somewhat and reduce it's ability to dissipate it's waste heat into the air. A more extreme example of this is in the calculator above, visible in the difference between the width requirement for an internal trace (buried between board layers) and an open air external trace.
This all assumes that you can't simply directly wire your high current connections. In short, the solder composition is not likely to noticeably matter in comparison to the method you choose.
I hope that helps some.
P.S. Is this for an HHO power generator project? I had a hunch and had to ask
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