Wipe the soldering iron on the sponge and hold it so it’s touching both the solder pad and the lead that protrudes through. Avoid using the soldering iron to melt the solder. Instead, heat up both the lead and the pad so that the solder melts when you touch it to them.
This must all be done quickly: within a second of touching the iron to the joint, push a small amount of solder into the joint, and let it flow around the joint as shown. Give it a second to flow, take the solder away, then wait a second, and take the iron away. With practice, you should be able to do all of this in three to four seconds per joint. Figure 2-9 shows how you’d solder the pin to the skill badge. Figure 2-10 shows an LED being soldered.
If you hold the iron to the component too long, you run the risk of damaging either the component or the solder trace on the PCB.
