How to Solder
Soldering is basically melting metal. Solder is a specially formulated metal with a relatively low melting point. For example the melting point of solder is typically about 370F(188C) to 428F(220C) where as the melting point of copper is 1984 F (1085C). With a soldering iron we can melt the solder in order to connect two pieces of metal. This connection is both mechanical (physically holds the parts together) and electrical (allows electricity to flow between them). If you look at the front of your PCB, you'll can see the copper traces that are run just under the surface and are exposed in the holes we are going to solder to.
A Tip About Tips
So, how do you solder? The goal is to heat the metal pads and the components and then let them melt the solder. Do not try to melt the solder and then wipe it where you want it as that will both cause bad joints and get pretty messy. Soldering irons come with many different tips. While finer points may work better for finer work, fatter tips hold heat better and therefore can be used more quickly and efficiently than finer points. Ultimately it is a personal choice, but the tip your iron comes with is a good place to start.
Position is Everything
When soldering you'll want to avoid trying to heat things with the point of the iron. Use the side near the tip for the most effective heat transfer. Place the iron next to the joint between the board and the component, wait about 1 second and then feed about 1/2in (about 1cm) of solder into the joint. It should melt immediately and make a nice shiny mountain of solder. Once you have enough solder remove the solder and then the iron. If you remove the iron first your roll of solder will be stuck to your joint. If this happens don't worry, just heat up the joint, remove the solder (and then the iron) and you are good to go. If it doesn't melt right away you may need to wait a bit longer, check your iron placement, clean your tip, or increase the temperature of your iron.
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Keep it Clean
Don't forget to clean your tip periodically! I usually try to do this every time I put the iron back in the stand. No matter what you do you, you are likely to end up with burnt on gunk on the end of your iron. A lot of that will be flux (a substance used to make the solder flow better that is actually part of a lot of solders you buy), or old burnt solder. Most soldering iron stands will have a spot for a sponge to wipe your tip on. You will need to use either a brass sponge or a regular sponge that is wet to wipe off your tip. For more soldering tips and info check out our soldering tutorial.
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