Soldering is a fundamental skill for anyone involved with electronics, whether professionally or as a hobby. It is not difficult to master, but it does require some practice for you to become proficient. Before starting a soldering project for the first time, it's a good idea to practice by soldering some components of different types onto a piece of stripboard. This will provide some of the experience you will need to solder components onto printed circuit boards.
Instructions
1 Clean the circuit board to remove any oxidation or grease from the solder pads, which can repel molten solder and cause beading. A pencil eraser is abrasive enough to remove oxides, and it can be used on both the circuit board and the leads of components. All the connections should be shiny; if dull color, that indicates that the surface of the metal has oxidized.
2 Prepare the soldering iron. The soldering iron should be allowed to heat to full temperature, five minutes is usually adequate after turning it on. The tip should be wiped on a damp sponge to remove any residue. The tip should also be then tinned, which involves applying a fine coating of solder over the entire tip to aid with heat transfer from the soldering iron to the component being soldered.
3 Place the component to be soldered on the circuit board. Double-check that the component is the correct type and value before you start soldering. Unless it is a surface mount component, the component should be placed on the reverse side of the board to the soldering pads, with the leads passing through the holes provided. The component should be flush against the PCB, as this provides extra mechanical strength for the connection. Surface-mount components do not pass through the board, and they are soldered onto the same side as the solder pads.
4 Hold the soldering iron like a pen, and touch the tip to both the lead of the component and the solder pad. Both need to be heated together to allow the solder to flow evenly and to create a good electrical connection. Hold the soldering iron tip in place for one to two seconds.
5 Touch the junction between the component lead and the circuit board pad with the solder, keeping the soldering iron in place. The molten solder should flow evenly around the joint, and it should form a small volcano shape that is shiny when cool. When the pad is evenly covered, remove the solder and the soldering iron.
6 Inspect the joint. A magnifying glass can help with this, especially when working with small connections. There should be no holes or dips in the solder. If too much solder is used then it will ball and form small beads, or form a spike when the soldering iron is removed. If this is the case, reheat the joint and add a small amount of extra solder. While the solder is still molten, remove it with a solder sucker or solder wick. These can also be used to remove any solder bridges between pads. The joint can then be re-soldered.
7 Cut the leads on the component about 1/16 inch above the surface of the circuit board. This gives a neat appearance and stops the leads from shorting together, while providing enough lead to reheat if the component needs to be replaced in the future.
8 Repeat the procedure until all the components are soldered to the board.
