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I have here two different pieces of copper that are from a standard [inaudible 00:09]
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power supply. One common soldering job might be to put a connector on something like this.
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This piece of wire has been stripped and sitting out in the air for a long time and I wanted
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you to see how it looks when compared with something that's just recently stripped. And
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holding them side by side, you can see that the one in my right hand is much, much cleaner
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and shinier. It has a pinkish appearance of nice, clean copper whereas, the one on the
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left not as copper colored.
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The copper that has been exposed to air for a long times forms an oxide layer on its surface
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and that oxide layer tends to disrupt the alloying process of soldering. So it's important
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to be able to get rid of that oxide layer before you begin soldering.
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There are two ways to do that. The first is to mechanically remove it. You can do that
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by using sand paper to abrade away the oxide. And the other way is to chemically remove
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it and for that, we would use our rosin core.
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So let me show you how it looks when we tin solder to the clean copper wire. Begin by
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adding some rosin, placing it in our vice, and heating it with our iron. See the smoke
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forming as the flux burns off and we have a nicely tinned piece of copper.
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Now, if we try to do the same process with the oxidized copper, we're going to run into
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trouble. Add our flux. Okay, here we go. Now, as we heat the joint see that our solder is
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still tries to find its way in there. It doesn't make quite the same contact that we had with
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the other. Just for comparison, I'll hold them side by side. You see little bits of
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brown left over? That's copper that hasn't been properly soldered and the reason for
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that is the oxides that have formed on its surface tend to disrupt that alloying process.
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So in order to make a better solder joint, what we need to do is we need to remove that
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oxide layer.
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What we'll do is we'll cut a new piece of wire. Strip and use our sand paper. Twisting
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the wire. Adding our flux. Applying heat and our solder wicks its way between the wires
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for a nice, clean tinned copper wire. And there you have it.
