Electronic – How to solder a wire to a massive copper busbar

interconnectsoldering

I need to solder a wire (tinned coper) to a massive copper busbar, I tried two approaches but to no avail.

I tried heating up the busbar with a heat plate to 300 °F (150 °C) and then tried to solder the wire to the busbar a) with a soldering iron or b) with a heat fan but it didn't work: The solder (we use SAC) doesn't melt properly (it doens'ntbecome fluid, only some small balls are formed) and the copper in the busbar started to change color, which I gather is oxidation in the copper.

Do you guys have any idea how to accomplish this?

Best Answer

My idea of massive may be different from what your idea of massive is, but if you use a propane or MAPP torch you should be able to solder to the bus bar. I have this set for small jobs that require a bit of oomph (but not so much that an oxyacetylene torch is called for):

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You want to heat the copper away from where the joint is to be, so that the solder melts onto the copper, rather than directing the heat at the solder and having it turn into nasty little balls.

You can even silver solder (hard solder) to get a physically strong joint, though that requires a higher temperature and will tend to destroy any insulation on the wire you're attaching.

Copper has very high thermal conductivity (which typically goes hand-in-glove with electrical conductivity for physics reasons) so it's always going to be difficult to solder to if there's a lot of it. You also need to make the copper clean and bright before attempting (and use a good flux).