Soldering method of electric soldering iron
2.1 Soldering method of in-line pin type components
The tip of the soldering iron should be in contact with the two interconnected parts to be welded (such as solder feet and pads) at the same time. The soldering iron is generally inclined at 30-45 degrees. Avoid contact with only one of the welded parts when the heated area of the two welded components is very different. The angle of inclination of the soldering iron should be adjusted appropriately. Reduce the inclination angle between the soldering iron and the soldered components with a large welding area, increase the contact area between the soldered parts with a large soldering area and the soldering iron, and enhance the thermal conductivity. , motor, horn and other inclination angles can be around 40 degrees. The two parts to be welded can reach the same temperature in the same time. considered to be the ideal state of heating.
2.2 Welding method of chip components
Before soldering, apply flux on the pad and handle it with a soldering iron to avoid poor tinning or oxidation of the pad. Cause bad welding. Chips generally do not need to be processed. Carefully place the QFP chip on the PCB with tweezers, taking care not to damage the pins. Align it with the pad. Make sure 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, and press down on the aligned chip with a tool. Apply a small amount of solder to the two diagonally positioned pins, still pressing down on the chip. Solder the pins on two diagonal positions so that the chip is fixed and cannot be moved. After soldering the opposite corners, re-check whether the position of the chip is aligned. Adjust or remove and re-align on PCB if necessary. When starting to solder all the pins. Solder should be added to the tip of the soldering iron. Apply solder to all the pins to keep the pins wet. Touch the end of each pin of the chip with the tip of the soldering iron until you see the solder flow into the pins. When soldering, keep the tip of the soldering iron parallel to the pins being soldered to prevent excessive soldering lap. After all the pins are soldered, wet all the pins with flux to clean the solder Blot off the excess solder where needed to eliminate any possible shorts and laps Finally check with tweezers for weak soldering, after the inspection is complete , Remove flux from the board. Dip the hard-bristled brush in alcohol and wipe it carefully along the direction of the pin until the flux
until it disappears.
2-3 Welding method of SMD RC components
Dot tin on a solder joint first. Then put one end of the components. clip with tweezers
Hold the component, after soldering one end, check to see if it is placed correctly; if it has been placed correctly, then solder the other end. If the pins are very thin, you can add tin to the chip pins in step 2, and then use tweezers Clamp the core, tap lightly on the edge of the table to remove excess solder. The third step is to solder directly with a soldering iron without tinning the soldering iron.
Welding time and temperature setting: the temperature is determined by the actual use. It is most suitable to solder a tin point for 1-4 seconds, and the maximum is no more than 8 seconds. Usually observe the tip of the soldering iron, when it turns purple, the temperature setting is too high. General in-line electronic materials. Set the actual temperature of the soldering iron tip to (350-370 degrees); for surface mount materials (SMT), set the actual temperature of the soldering iron tip to (330-350 degrees), generally the melting point of the solder plus 100 degrees. When soldering large component feet, the temperature should not exceed 380 degrees, but you can increase the power of the soldering iron.
Welding precautions: Before welding, observe whether each solder joint (copper skin) is smooth, oxidized, etc. If there are sundries, clean them with a brush before welding. If there is oxidation, add an appropriate amount of flux to increase the welding strength. When welding items, be sure to spot the welding point. In order to avoid short circuit caused by poor welding of the line. If the components to be soldered are not heat-resistant packages such as plastic casings. Soldering can be carried out after coating absolute alcohol on the component body to prevent heat damage. After welding, carefully check the welding status of components, whether there are residual tin, tin beads, and tin slag in the surrounding solder joints.
