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Solder Not Wetting


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Welcome new member!

Your copper pads are oxidized (or the pins are oxidized). Polish them up with a pencil eraser, scotchbrite pad, 400 to 1200 grit sand paper (pencil eraser works best).

Also, you need to heat the pad and the solder, not just the solder.


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Also put a small amount of rosin flux on the pins before you try to solder them.
Solder not wetting at all.
Not knowing your soldering experience:
Remember that the items being soldered must be hot enough for solder to flow on them & that the iron is to heat those, not to directly melt the solder.

A tiny amount of flux cored solder on the iron first helps thermal contact to get heat into the items being joined.

Hold the iron tip in the angle between the PCB pad and pin.
After a second, apply cored solder to the pin/pad - it should melt easily, without needing to touch the iron tip.

If it does not flow properly and just blobs, lift the blob with the iron and wipe or flick it off the tip.
The solder should have left a layer of flux on the joint parts, which will help remove any slight surface oxidation or tarnish in the next attempt.

Just try it again.

If the parts are obviously tarnished, clean them first - but that is quite a rare thing to have to do.


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If the parts are obviously tarnished, clean them first - but that is quite a rare thing to have to do.
Flux is just a chemical way of removing tarnish from the parts being soldered. Most people do not have rosin based flux in their toolbox so using physical methods to brighten up the copper or tinned component leads will let most people get their part soldered today with the tools at hand instead of running out to Radio Shack to get s pot of flux. Oh wait, have to wait a couple days for amazon to deliver it - no more radio shack.
Most people do not have rosin based flux in their toolbox
Er... It's in the flux-cored solder, or they have a serious problem trying to do any electronic soldering!

I've not used separate flux for any electrical work in decades.. Various ones for Plumbing, or for white metal in modelmaking, yes - but not electronics! Z_GN3xfo5oy.JPG
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It's one that does not leave a harmful residue, so it should be OK.

Note that surface mount soldering often uses very different techniques to manually soldering conventional (wire leaded or pin type) components.

This is a good example of how to solder conventional components:


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I'm with rjenkinsgb on this one - rosin-core solder is really the best way to go for a hobbyist learning to solder. It's very easy to use and just works - no need to apply external flux, which means you don't have to go through the process of finding the best flux to match your application and the solder you plan to use. Just buy a spool of 0.015" rosin-core solder and that'll work for a wide variety of electronics projects.


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Do they even make rosin cored solder any more?, obviously all electronics solder is flux cored, but wasn't rosin removed on health grounds?.
Oh, I'm not sure. The solder I use at home is labeled as "rosin core", but maybe the name just carried through. I don't recall off the top of my head exactly what type of flux is in it.
Thread starter #19
Called Kester and he said these Pocket Packs are 44 solder.

I soldered wires with a Weller soldering gun and paste flux it comes with and solder soaked into wires.

It is not happening soldering these pins headers.


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I wonder if "rosin" when referring to solder flux cores is like saying "pencil lead". It used to be made out of a certain material but due to health and safety reasons, it was changed to something else. Regardless, a lot of people still call it by the old name.

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