Summary of the soldering essentials for the electric soldering iron
1. The contact method between the soldering iron tip and the two parts to be welded
(1) Contact position
The soldering iron tip should contact two parts to be welded (such as solder legs and pads) at the same time. The soldering iron is generally tilted at 45 degrees to avoid contact with only one of the parts to be welded.
When the heat capacity of two parts to be welded is very different, the tilt angle of the soldering iron should be appropriately adjusted. The smaller the tilt angle between the soldering iron and the welding surface, the greater the contact area between the part to be welded and the soldering iron with the larger heat capacity, and the stronger the heat conduction capability.
For example, when welding LCD, the inclination angle is about 30 degrees, and when welding microphones, motors, speakers, etc., the inclination angle can be about 40 degrees. The two parts to be welded can reach the same temperature in the same time, which is considered an ideal heating state.
(2) Contact pressure
When the soldering iron tip is in contact with the workpiece to be welded, a slight pressure should be applied. The strength of the heat conduction is proportional to the amount of pressure applied, but it must be based on the principle of not causing damage to the surface of the workpiece to be welded.
2. Supply method of welding wire
The supply of welding wire requires mastering three key points, namely supply time, location and quantity.
(1) Supply time: In principle, the solder wire is supplied immediately when the temperature of the workpiece to be welded reaches the melting temperature of the solder.
(2) Supply position: It should be between the soldering iron and the parts to be soldered and as close to the soldering pad as possible.
(3) Supply quantity: It should depend on the size of the parts to be welded and the pad. After the solder covers the pad, the solder should be higher than 1/3 of the diameter of the pad.
3. Welding time and temperature settings
(1) The temperature is determined by actual use. It is most suitable to solder a tin point for 4 seconds, and the maximum should not exceed 8 seconds. Observe the soldering iron tip at ordinary times. When it turns purple, the temperature is set too high.
(2) For general direct-plug electronic materials, set the actual temperature of the soldering iron tip to (350~370 degrees); for surface mount materials (SMC) materials, set the actual temperature of the soldering iron tip to (330~350 degrees)
(3) Special materials require special setting of soldering iron temperature. FPC, LCD connectors, etc. must use silver-containing tin wire, and the temperature is generally between 290 degrees and 310 degrees.
(4) When soldering large component pins, the temperature should not exceed 380 degrees, but the power of the soldering iron can be increased.
4. Precautions for welding
(1) Before welding, observe whether each solder joint (copper skin) is smooth, oxidized, etc.
(2) When welding items, pay attention to the welding points to avoid short circuits caused by poor line welding.
The above are some operating tips when soldering with an electric soldering iron. I hope it will be helpful to everyone.
