Soldering iron - in-line pin type component welding method
1 The contact mode between the soldering iron tip and the two parts to be welded. Contact position: The tip of the soldering iron should touch 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, and should avoid contact with only one of the parts to be welded. When the heating area of the two components to be welded is very different, the inclination angle of the soldering iron should be adjusted appropriately to reduce the inclination angle between the soldering iron and the component to be welded with a large welding area, and to increase the contact area between the welded part with a large welding area and the soldering iron , enhanced thermal conductivity. For example, the inclination angle of LCD pull welding is about 30 degrees, and the inclination angle of welding microphones, motors, speakers, etc. can be about 40 degrees. Two parts to be welded can reach the same temperature in the same time, which is considered as plus
Hot ideal state.
Contact pressure: When the soldering iron tip is in contact with the weldment, a slight pressure should be applied. The strength of heat conduction is proportional to the applied pressure, but the principle is that it does not cause damage to the surface of the weldment.
2 How to supply solder wire. The supply of solder wire should be mastered in three ways, namely supply time, location and quantity.
Supply time: In principle, the solder wire is sent immediately when the temperature of the weldment reaches the melting temperature of the solder.
Supply position: It should be between the soldering iron and the welded part and as close to the pad as possible.
Supply quantity: It depends on the size of the weldment and the pad. After the solder covers the pad, the solder can be higher than 1/3 of the diameter of the pad, and the solder joint should be conical.
3 Welding time and temperature settings.
3.1 The temperature is determined by the actual use. It is most suitable to solder a solder 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.
3.2 Generally, for 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
(33o~350 degrees), generally the melting point of solder plus 100 degrees.
3.3 For special materials, the temperature of the soldering iron needs to be specially set. LCD connectors, etc. should use silver-containing tin wire, and the temperature is generally between 290 and 310 degrees.
3.4 When soldering large component feet, the temperature should not exceed 380 degrees, but the power of the soldering iron can be increased.
4 Precautions for welding.
4.1 Before welding, observe whether each solder joint (copper skin) is smooth and oxidized. If there are sundries, use a brush to clean them before welding. If there is oxidation, add an appropriate amount of flux to increase the welding strength.
4.2 When welding items, watch the welding point to avoid short circuit caused by poor welding of the line
4.3 If the component to be welded is a non-heat-resistant package such as a plastic case, you can apply absolute alcohol to the component body before welding to prevent heat damage.
4.4 After welding, carefully check the welding status of the components, whether there are residual tin, tin beads, and tin slag in the surrounding solder joints.
