1. External heating soldering iron
It is generally composed of a soldering iron head, a soldering iron core, a shell, a handle, a plug and other parts. The soldering iron tip is installed in the soldering iron core and is made of copper alloy material with copper as the base with good thermal conductivity. The length of the soldering iron head can be adjusted (the shorter the soldering iron head, the higher the temperature of the soldering iron head), and there are different shapes such as chisel, pointed cone, round surface, circle, pointed cone and semi-circular groove shape to adapt to The needs of different welding surfaces.

2. Internal heating soldering iron
It consists of five parts: connecting rod, handle, spring clip, soldering iron core, and soldering iron tip (also called copper tip). The soldering iron core is installed inside the soldering iron head (it heats up quickly, and the thermal efficiency is as high as 85% to more than %%). The soldering iron core is made of nickel-chromium resistance wire wound around a porcelain tube. Generally, the resistance of a 20W soldering iron is about 2.4kΩ, and that of a 35W soldering iron is about 1.6kΩ.

Generally speaking, the greater the power of the soldering iron, the greater the heat, and the higher the temperature of the soldering iron tip. A 20W internal heating soldering iron is generally used to solder integrated circuits, printed circuit boards, and CMOS circuits. If the power of the soldering iron is too high, it is easy to burn the components (generally, the junction temperature of the diode and triode will burn out when the junction temperature exceeds 200 degree ) and cause the printed wires to fall off the substrate; if the power of the soldering iron is too small, the solder cannot be fully melted. , the flux cannot evaporate, the solder joints are not smooth and firm, and it is easy to produce false soldering. If the welding time is too long, the device will also be burned out. Generally, each soldering point is completed within 1.5 to 4S.

3. Other soldering irons

1) Constant temperature soldering iron
The soldering iron head of a constant temperature electric soldering iron is equipped with a magnet-type temperature controller to control the power-on time and achieve constant temperature. When welding components whose temperature should not be too high and whose welding time should not be too long, a constant-temperature soldering iron should be used, but it is expensive.

2) Soldering iron

3) Steam soldering iron