Safe use of electric soldering iron
Simply put, the following three points should be noted
1. Before soldering, the excess part of the lead wire of the component should be cut off and tinned. If the surface of the component is oxidized and not easy to tin, you can use fine sandpaper or a knife to clean the surface of the lead, and use a soldering iron tip to dip an appropriate amount of rosin core solder to tin the lead. If you still can't hang tin, you can put the component lead on the rosin block, then touch the lead lightly with the tip of the soldering iron, and turn the lead at the same time, so that the surface of the lead can be evenly tinned. The tinning time of each lead wire should not be too long, generally 2~3 seconds is appropriate, so as not to burn the inside of the component, especially when tinning the pins of diodes and triodes, it is best to use metal tweezers to clamp the lead wires against the shell part, so as to dissipate part of the heat. In addition, the pins of various components should not be cut too short, otherwise it is not conducive to heat dissipation and soldering.
2. When soldering, place the lead wire of the component that has been hung with tin in the position to be soldered, such as in the pad hole of the printed board or in the small hole of the solder piece of various joints, sockets and switches, and use a soldering iron tip with an appropriate amount of tin on it. The soldering part stays for about 3 seconds, and after the soldering iron is removed, a smooth solder joint is formed at the soldering part. In order to ensure the quality of welding, it is best to hang tin in advance at the position of the lead wire of the welding component. When welding, make sure that the position of the lead wire does not change, otherwise it is very easy to cause false welding. The soldering iron tip should not stay for too long, otherwise it will burn the components, and if it is too short, it will cause false welding due to insufficient welding melting.
3. After welding, carefully observe the shape and appearance of the solder joints. The solder joints should be hemispherical and the height is slightly smaller than the radius. They should not be too bulging or flat. The appearance should be smooth and uniform without obvious pores or depressions, otherwise it will easily cause false or false welding. When welding the leads of several components at the same time, more attention should be paid to the quality of the solder joints.
