How to use electric soldering iron (suitable for LED welding)
1. Introduction of electric soldering iron
1. External heating electric soldering iron 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 good thermal conductivity copper as the matrix. The length of the soldering iron tip can be adjusted (the shorter the soldering iron tip, the higher the temperature of the soldering iron tip), and there are different shapes such as chisel, pointed cone, round surface, circle, pointed cone and semi-circular groove to suit The need for different welding surfaces.
2. Internal heating electric soldering iron consists of five parts: connecting rod, handle, spring clip, soldering iron core, and soldering iron tip (also called copper head). The soldering iron core is installed inside the soldering iron head (heats quickly, and the thermal efficiency is as high as 85%~%%). The soldering iron core is made of nickel-chromium resistance wire wound on a porcelain tube. Generally, the resistance of a 20W electric soldering iron is about 2.4kΩ, and that of a 35W electric soldering iron is about 1.6kΩ. The working temperature of the commonly used internal heating electric soldering iron is listed in the following table: Soldering iron power/W20, 25, 45, 75, 100 Terminal temperature/°C350, 400, 420, 440, 455 Generally speaking, the greater the power of the electric soldering iron, The more heat, the hotter the tip of the soldering iron. Welding integrated circuits, printed circuit boards, and CMOS circuits generally use 20W internal heating electric soldering iron. The power of the soldering iron used is too high, it is easy to scald the components (generally, when the junction temperature of the diode and triode exceeds 200°C, it will burn out) and the printed wires will fall off the substrate; the power of the soldering iron used is too small, and the solder cannot be fully melted , The flux cannot be volatilized, the solder joints are not smooth and firm, and it is easy to produce false welding. If the welding time is too long, the device will also be burned out. Generally, each solder joint is completed within 1.5 to 4S.
3. Other soldering irons
1) Constant temperature electric soldering iron The iron head of the constant temperature electric soldering iron is equipped with a magnet-type temperature controller to control the power-on time and achieve the purpose of constant temperature. When the soldering temperature should not be too high and the soldering time should not be too long, a constant temperature electric soldering iron should be used, but it is expensive.
2) Tin-absorbing electric soldering iron Tin-absorbing electric soldering iron is a desoldering tool that integrates a piston-type tin absorber and an electric soldering iron. It has the characteristics of convenient use, flexibility, and wide application range. The disadvantage is that only one solder joint can be desoldered at a time.
3) Steam soldering iron A soldering iron that burns flammable gases such as liquefied petroleum gas and methane to heat the soldering iron tip. It is suitable for occasions where the power supply is inconvenient or cannot supply AC power.
Second, the choice of electric soldering iron
1. The selection of electric soldering iron generally follows the following principles:
① The shape of the soldering iron tip should adapt to the surface requirements of the weldment and the assembly density of the product.
② The temperature of the tip of the soldering iron tip should be compatible with the melting point of the solder, which is generally 30-80°C higher than the melting point of the solder (excluding the temperature drop when the soldering iron tip touches the soldering point).
③ The heat capacity of the soldering iron should be appropriate. The temperature recovery time of the soldering iron tip should be adapted to the requirements of the surface of the weldment. The temperature recovery time refers to the time required for the temperature at the tip of the soldering iron tip to return to the highest temperature after the temperature of the tip of the soldering iron decreases due to heat loss during the soldering cycle. It is related to the power of the electric soldering iron, heat capacity, and the shape and length of the soldering iron tip.
