Video narration
If your solder joint keeps failing, you may be melting solder on the iron instead of heating the joint. A hot glue gun works that way; soldering does not. Start by placing the flat edge of the soldering iron tip against both parts: the component lead and the copper pad. Keep both touching the tip. Wait a few seconds for the joint to get hot enough. Then bring the solder wire in from the side opposite the iron, and touch it to the heated joint. It should melt there, against the metals-not on the tip. Once enough solder has flowed, remove the solder first. Then lift away the soldering iron. Finally, leave the connection still for a few seconds while it cools naturally. Remember: heat both metals, let the joint melt the solder, remove solder before iron, and keep the cooling joint still.