Electric soldering iron specifications and selection criteria
1. The shape of the soldering iron head adapts to the requirements of the surface of the soldered object
The heads of commonly used external heating electric soldering irons are mostly made of chisel style, and according to the requirements of the surface to be soldered, the angle of the chisel-type soldering iron head is 45°, 10°-25°, etc., and the width of the chisel mouth is also different. The same, as shown in Figure 1(a), (b).
For products with high welding density, soldering iron tips can be used as shown in Figure 1(c), (d). Internally heated electric soldering irons often use round beveled soldering iron tips, which are suitable for soldering printed circuit boards and general solder joints, as shown in Figure 1(e).
In the soldering of printed circuit boards, it is sometimes more convenient to use the notch soldering iron tip shown in Figure 1(f) and the hollow core iron tip shown in Figure 1(g), but the repair of these two soldering iron tips is relatively difficult. trouble.
2) The temperature at the tip of the soldering iron tip adapts to the melting point of the solder
Usually this temperature should be 30-80°C higher than the melting point of the solder, and should not include the temperature dropped when the soldering iron tip touches the solder joint.
3) The heat capacity of the electric soldering iron meets the requirements of the welded parts
If the heat capacity is too small, the temperature will drop rapidly, resulting in insufficient solder melting, low solder joint strength, dark and dull surface, rough solder particles, and even virtual soldering.
If the heat capacity is too large, the temperature of components and solder will be too high, which will not only damage the insulation layer of components and wires, but also cause the copper foil of the printed circuit board to bubble, and the fluidity of solder is too large to be controlled.
4) The temperature recovery time of the soldering iron tip can meet the thermal requirements of the welded parts
The so-called temperature recovery time refers to the time required for the soldering iron tip to return to the original maximum temperature after the temperature of the soldering point is lowered. To make this recovery time appropriate, it is necessary to select a suitable electric soldering iron with power, heat capacity, tip shape, and length.
5) Selection of the power of the electric soldering iron
① For welding more precise components and small components, it is advisable to use a 20W internal heating type electric soldering iron or a 25~45W external heating type electric soldering iron.
② To weld continuous solder joints, an electric soldering iron with relatively high power should be selected.
③ For large solder joints and the grounding lugs of the metal base plate, it is advisable to use an externally heated electric soldering iron of 100W or above.
