How to you get wrapped wire to solder to copper traces?

Question

I am having to do some trace rework on my PCB and I can't get trace repaired to I am just going to do a wire jumper but...I can't seem to get the solder to take to the copper traces and i also can't get the solder to take to the bare wire...what's the trick????? Thanks

Answer 1

Make sure the copper is clean and that you are using flux-cored solder. The copper trace may have a varnish coating, so sand it clean (carefully).

Answer 2

Use some flux if you have some, hold a piece of metal ontop of the two traces and solder both sides.

Answer 3

If possible, it's sometimes easier to go back to a through-hole pin or a via rather than trying to solder directly to a track.

In addition to ensuring that the track is clean and you're using rosin core solder, be sure to hold the wire on the track so that you can heat the wire and the track at the same time.

Answer 4

Soldering bonds solder to certain metals, such as copper. To solder, the copper surfaces must be bare metal and corrosion free.

The purpose of the flux is to wet the copper and lift off any corrosion. Rosin flux is used for electronics.  Manufactuerers often use acids such as HCl (hydrochloric or muriatic acid), for flux, as most electronics are washable under certain circumstances. However, acid can ruin the parts unless properly cleaned off, so unless you are an expert, better to stick with rosin flux.

First, pre-tin both the wire and the trace. Use rosin core flux, you can also get rosin flux in a can so you can add more if you need it. Stick the pre-heated iron on the bare metal of the wire or trace, and once it is hot, touch the solder to the wire or trace and let the solder reflow. If the solder isn't sticking when it melts, the surface is not bare metal, or inadequate flux. So, make sure you strip off the plastic insulation from the wire, and the plastic coating from the trace.

Once both surfaces are pre-tinned, soldering is easy. Hold the wire on the trace, heat the wire with a pre-heated iron, then add a small amount of solder. Remove the iron, holding the joint perfectly still until it cools. Use tweezers or hemostats to hold the wire in place and perfectly still until it's cooled. If the joint moves while the solder is pastey, it is ruined and visibly less shiny or comes across completey. Save the  joint by remelting the solder while holding the wire steady. Keep the heating time short, as long times can lift traces and even dissolve the copper into the solder.