PCBA patch welding
Precautions for PCBA patch welding
Chip resistors and capacitors are mostly ceramic bases. This material is easy to crack due to collision. Therefore, temperature control, preheating, touch and other skills should be mastered when removing and soldering PCBA chips. Temperature control refers to controlling the welding temperature at about 200-250°C. Preheating refers to preheating the components to be welded in an environment of about 100°C for 1 to 2 minutes to prevent sudden damage to the components due to thermal expansion. When heading, heat the welding joints or conductive tape on the printing plate first, and try not to touch the parts. At the same time, the welding time is controlled at about 3 seconds, and the circuit board is allowed to cool down naturally at room temperature after welding. The above methods and techniques are also suitable for the welding of SMD crystal ii and triple diagram.
PCBA patch soldering pins have a large number, narrow spacing, and small chip integrated circuit hardness. If the soldering temperature is not appropriate, it is easy to cause pin solder short-circuit, virtual soldering, or printing line copper foil publishing. When removing the patch integration When circuiting, you can adjust the temperature of the soldering iron to about 260C, use an iron tip and a skimmer to remove all the solder on the integrated circuit, and use a pointed tweezers to gently insert the bottom of the integrated circuit, and use the soldering iron to heat it. At the same time, gently lift the integrated circuit pins one by one with tweezers to gradually separate the integrated circuit pins from the printing plate. When lifting the integrated circuit with tweezers, be sure to synchronize with the area heated by the iron to prevent premature damage to the circuit board.
Before switching to a new integrated circuit, all the solder left by the original integrated circuit should be removed to ensure smooth and clean pads. Then the pins of the soldered integrated circuit are polished with fine sandpaper and tinned evenly, and then the soldering feet of the soldered integrated circuit are aligned with the corresponding solder joints on the printed board, and the surface of the integrated circuit is lightly welded by hand to prevent the integrated circuit from being damaged. Move, on the other hand, operate integrated circuits. The soldering iron fixes the four-corner pins of the integrated circuit and the circuit board with an appropriate amount of soldering. Check again to confirm the type and direction of the integrated circuit. After the correct and formal soldering, the temperature of the soldering iron will be adjusted to about 250°C. A hand-held soldering iron will The integrated circuit pins are heated, and another hand-held soldering iron sends the solder wire to the heated pins for soldering until all pins are soldered. Finally, carefully check to eliminate pin short circuits and virtual soldering. After the solder joints, cool naturally and use a brush again. Anhydrous alcohol cleans the circuit board and solder joints to prevent residues.
Before repairing the circuit board of the module, it is best to clean the printed board with a brush. Do not use anhydrous alcohol to remove dust, solder slag and other debris on the circuit board. Observe whether the original circuit board has false soldering or short-circuit soldering. Solder, and find fault points early. Save maintenance time.