Hand soldering tips for surface mount components


一:The required tools and materials

Welding tools need 25v copper small soldering iron, conditional use temperature adjustable and soldering station with ESD protection, pay attention to the soldering iron tip to be fine, the width of the top can not be greater than 1mm. A pointed tweezers can be used to move and secure the chip and check the circuit. Also prepare fine wire and flux, isopropal alcohol, etc. The purpose of using flux is mainly to increase of the solder fluidity, so that the solder can be pulled with a soldering iron and smonthly wrapped on the leads and pads by the effect of surface tension. After welding, remove the flux from the plate with alcohol.


二:Welding method

1. Before soldering, apply soldering flux to the soldering pad and apply it to the soldering iron again to avoid bad tining or oxidation of the solder pad, resulting in poor soldering. The chip generally does not need to be processed.


2. Carefully place the PQFP chip on the PCB with tweezers, being careful not to damage the pins. Align it with the pad and ensure that the chip is placed in the correct orientation. Adjust the temperature of the soldering iron to more than 300 degrees Celsius, dip a small amount of solder on the tip of the soldering iron, use the tool to hold down the chip in the aligned position, and add a small amount of flux to the pins in two diagonal positions. Hold the chip down and solder the pins in two diagonal positions so that the chip is fixed and can not move. After checking the corners, recheck the position of the chip. If necessary, adjust or remove and reposition the PCB board.


3. When starting to solder all pins, add solder to the tip of the soldering iron. Applu solder to all pins to keep the pins wet. Use a soldering iron tip to touch the end of each pin of the chip until you see the solder flow into the pin. Keep the tip of the soldering iron in parallel with the soldering pin during soldering to prevent excessive soldering from overlapping.


4. After soldering all the pins, solder all the pins with solder to clean the solder. Remove excess solder where needed to eliminate any short circuit and overlap. Finally, use a tweezers to check whether ther is a false weld. After the inspection is completed, remove the solder from the circuit board. Dip the bristles with alcohol and carefully wipe it in the direction of the pin until the solder disappears.


5. Patch RC components are relatively easy to weld some, you can first point in a solder joint tin, and then put on one of the components,with tweezers clamping components, after welding one, and then see if it is up; if put it on, then weld another one. It takes a lot of practice to really master welding techniques.