Welding of Flexible Circuit Boards

How to solder flexible circuit boards? What problems might occur?

Steps of welding flexible circuit board  are as follows:

1. Before soldering, apply flux to the pad and process it with a soldering iron to avoid poor tin plating or oxidation of the pad that might result in poor soldering, and the chip generally does not need to be processed.

2. Use tweezers to carefully place the PQFP chip on the PCB board, pay attention not to damage the pins. Make it aligned with the pad and ensure that the chip is placed in the correct direction. Adjust the temperature of the soldering iron to above 300 degrees Celsius, dip a small amount of solder on the tip of the soldering iron, press down the aligned chip with a tool, and add a small amount of solder to the two diagonal pins. Hold down the chip and solder the pins on the two diagonal positions to make the chip fixed and unable to move. After soldering the opposite corners, recheck the alignment of the chip position. If necessary, adjust or remove and realign the position on the PCB board.

3. When starting to solder all the pins, add solder to the tip of the soldering iron, and apply flux to all the pins to keep the pins moist. Touch the end of each pin of the chip with the tip of a soldering iron until you see the solder flowing into the pin. When soldering, keep the tip of the soldering iron parallel to the soldered pin to prevent overlap due to excessive soldering.

4. After soldering all the pins, wet all the pins with flux to clean the solder. Suck off the excess solder where needed to eliminate any short circuits and overlaps. Finally, use tweezers to check whether there is a false soldering. After the inspection is completed, remove the solder from the circuit board, and soak the hard brush with alcohol and wipe it carefully along the pin direction until the solder disappears.

5. SMD RC components are relatively easy to solder. You can put tin on a solder joint first, then put one end of the component, clamp the component with tweezers, and then see if it is placed correctly after soldering one end; If it has been aligned, then solder the other end.

As a professional FPC soft board manufacturer, XPCB Limited is so honored to have worked together with many of you. At XPCB Limited we are always more than ready to assist our new customers in any way we can.  Please feel free to contact us at any time if you have any question.