Flexible printed circuit boards consist of various electronic components that are soldered in order to form a complete circuit. However, sometimes one or more of these components may get damaged or start malfunctioning because of any technical issue. In such cases, damaged components can render the entire flex PCB of no use. To rectify this issue, you will need to desolder the malfunctioning component from the circuit board and replace it with a new one. Desoldering is not as easy process as soldering, because if you are not careful enough, you might end up causing damage to the neighboring components as well. Here we will learn about the safe techniques involved in removal of the electronic components from flexible circuit boards.
1. Preheat the soldering iron. In order to melt the solder, preheat a soldering iron (25W or 30W capacity, not more that that) for approximately five to ten minutes.
2. Clean the tip of your soldering iron. While the iron is heating, clean its tip with the help of a wet sponge. Wipe the sponge two or three times in order to thoroughly clean the tip.
3. Locate the terminals of the components to be removed. In this step, you will need to locate or roughly mark the components that you need to take off the flex PCB and identify their terminals.
4. Place the desoldering braid on flexible circuit board. From a spool of desoldering braid, unroll approximately 1 inch (2.5 cm) and place it on the board in such a way that its tip is pressed over the solder and one leg of the electronic component on the PCB.
5. Melt the solder using heated iron. Place the tip of the heated solder iron on top of the desoldering braid in such a way that it will cause melting of the solder around the electronic component that is to be removed. The melted solder will get wicked into the braid and the leg of component will come off of the circuit board.
6. Remove the solder iron and desolder braid. As soon as the solder gets absorbed in the desoldering braid, you need to take the iron and braid away from the flexible circuit board to avoid undesired melting of solder surrounding other components.
7. Take off other legs of the electronic component. In order to remove the component completely, repeat steps 5 and 6 and take off other legs of the component. Once the component is completely free, let it cool for some time and then lift it off the board. If the electronic component is very small in size, then you can use a fork or tweezers (forceps) to pick it off the board.