Every electronic device is made up of one or more Printed Circuit Boards, or PCBs. As technology is improving and component sizes are getting smaller, the complexity of these PCBs is increasing. To make these boards smaller, Surface Mount Devices, or SMDs, are now commonly used in place of larger parts. The SMD LEDs are very small light emitting diodes and populating PCBs with them requires some practice and special tools.
1 Place the PCB on a flat and dry surface with the component side facing up.
2 Identify the places where the LEDs are to be soldered on the PCB using the circuit diagram. Make special note of the polarity of the pads: the positive and negative terminals of the LED pads should correspond to the positive and negative terminals of the LED.
3 Place the first LED between the respective pads on the PCB with the help of tweezers. Make sure that about half of the pads remain visible after placing the LED between the two pads and the polarity is right.
4 Turn the soldering iron on and set it to 450 degrees Celsius. Wait until the temperature reaches this value before moving on to the next step.
5 Briefly touch the tip of the solder wire with the tip of the soldering iron. Some of the solder will melt and accumulate on the tip of the iron. While gently pressing the LED with the tip of tweezers, touch the interface of one end of the LED terminal and the corresponding pad with the tip of the soldering iron. The solder flux will flow to the pad and will cover a part of the LED terminal as well. Repeat this process on the other end of the LED.
6 Solder the next LED using the same method. Place the soldering iron tip back into its holder and turn off the soldering iron.