At present, tin wire welding of electronic components mainly adopts tin soldering technology. Soldering technology uses tin-based tin alloy material as solder. The tin wire melts at a certain temperature, and the metal weldment and tin atoms attract, diffuse, and combine with each other to form an infiltrated bonding layer. It seems that the copper platinum of the printed board and the lead wires of the components are very smooth. In fact, their surfaces have many small concave-convex gaps. The molten tin solder diffuses along the surface of the weldment with the help of capillary suction to form solder and solder joints. The infiltration of the components, the components and the printed board are firmly bonded together, and it has good electrical conductivity.

The conditions for tin welding are: the surface of the weldment should be clean, and oil stains and rust spots will affect the welding; only metals that can be wetted by tin solder have solderability. For materials such as brass that are easy to form oxide films on the surface, you can use Soldering flux, tin-plated and infiltrated the surface of the weldment before welding; there must be an appropriate heating temperature to make the solder material have a certain fluidity, so that the purpose of soldering can be achieved, but the temperature should not be too high or too high. When it is high, it is easy to form an oxide film and affect the welding quality.

The main tool for manual soldering is a soldering iron. There are many types of electric soldering irons, including direct heating type, induction type, energy storage type and temperature adjustment type. The electric power is 15W, 2OW, 35w...300W, which is mainly determined according to the size of the weldment. 2OW internal heating electric soldering iron is suitable for welding general components; energy storage electric soldering iron can be used when welding integrated circuits and vulnerable components; 150W~300W high-power external heating electric soldering iron can be used when welding large weldments. The temperature of the soldering iron tip of a low-power electric soldering iron is generally between 300 and 400 °C.

Solder is the main material used for welding. Solder for soldering electronic components is actually a tin-lead alloy. The melting point temperature of solder with different tin-lead ratios is different, generally 180~230 ℃. There are high-quality rosin and activator in the middle of the solder wire, which is very convenient to use. Tubular solder wire has various specifications such as 0.5, 0.8, 1.0, 1.5, etc., which can be conveniently selected.

Flux, also known as flux, is a material that can clean and protect the surface of the welded metal after being heated. The metal surface in the air is easy to form an oxide film, which can prevent the solder from infiltrating the soldering metal. Proper use of flux can remove the oxide film, making the welding quality more reliable, and the surface of the solder joints smoother and rounder.

Manual soldering is a traditional soldering method. Although manual soldering is rarely used in mass production of electronic products, manual soldering is inevitably used in the maintenance and debugging of electronic products. The quality of welding also directly affects the maintenance effect. Manual welding is a very practical skill. After understanding the general methods, you need to practice more; practice more to have better welding quality.

There are three ways to hold the soldering iron in manual welding: forward grip and pen grip. It is more convenient to hold a pen when soldering components and maintaining circuit boards.

Manual soldering is generally carried out in four steps. ①Preparation for welding: Clean the dust and oil stains on the components to be welded, and then break the components around the components to be welded left and right, so that the soldering iron tip can touch the solder of the soldered components to prevent the soldering iron tip from extending to the Burning other components during welding. When soldering new components, the leads of the components should be tinned. ②Heating welding: Touch the tip of the electric soldering iron with a little solder and rosin to the component to be welded for about a few seconds. If you want to remove the components on the printed board, after the tip of the soldering iron is heated, gently pull the components with your hands or silver to see if they can be removed. ③Clean up the soldering surface: If there is too much solder on the soldered part, you can shake off the solder on the tip of the soldering iron (be careful not to burn your skin, and don’t throw it on the printed circuit board!), and use the soldering tip to "dip" some solder out . If there is too little solder in the solder joint and it is not smooth, you can use the tip of the electric soldering iron to "dip" some solder to repair the solder joint. ④ Check the solder joints: Check whether the solder joints are round, bright and firm, and whether they are connected to the surrounding components.