Summary of welding essentials for electric soldering iron
1. Contact mode between soldering iron head and two welded parts
(1) Contact position
The soldering iron head should be in contact with two connected parts (such as solder legs and pads) at the same time. The soldering iron is generally tilted 45 degrees to avoid contact with only one of the welded parts.
When the Heat capacity of the two weldments is greatly different, the tilt angle of the soldering iron should be properly adjusted. The smaller the tilt angle between the soldering iron and the welding surface, the larger the contact area between the weldment with larger Heat capacity and the soldering iron, and the stronger the thermal conductivity.
For example, when welding LCD, the tilt angle is around 30 degrees, and when welding microphones, motors, speakers, etc., the tilt angle can be around 40 degrees. The ability of two welded components to reach the same temperature at the same time is considered an ideal state for heating.
(2) Contact pressure
When the soldering iron head comes into contact with the welded part, slight pressure should be applied. The strength of 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 welded part.
2. Supply method of welding wire
The supply of welding wire requires mastering three key points, namely supply time, position, and quantity.
(1) Supply time: In principle, the solder wire is immediately sent when the temperature of the welded part reaches the melting temperature of the solder.
(2) Supply position: It should be between the soldering iron and the welded part and as close as possible to the solder pad.
(3) Supply quantity: It should depend on the size of the soldered parts and pads. After covering the pads with solder, the solder should be higher than 1/3 of the pad diameter.
3. Welding time and temperature settings
(1) The temperature is determined by actual use, and it is most suitable to weld a tin point for 4 seconds, with a maximum of 8 seconds. Usually, observe the soldering iron head, and when it turns purple, the temperature is set too high.
(2) Generally, insert electronic materials directly and set the actual temperature of the soldering iron head to (350~370 degrees); Surface Mount Material (SMC) material, set the actual temperature of the soldering iron head to (330-350 degrees)
(3) Special materials require special setting of soldering iron temperature. FPC, LCD connectors, etc. need to use silver containing tin wire, with a temperature generally between 290 degrees and 310 degrees.
(4) Welding large component feet should not exceed 380 degrees Celsius, but it can increase the power of the soldering iron.
4. Welding precautions
(1) Before welding, observe whether each welding point (copper sheet) is smooth, clean, oxidized, etc.
(2) When welding items, pay attention to the welding points to avoid short circuits caused by poor wiring.
