Selection of electric soldering iron and welding method
The choice of soldering iron
Electric soldering irons are roughly divided into two types: external heating type and internal heating type.
When we choose an electric soldering iron, it is generally determined by the size of the soldering point. If the area of the soldering point is large, the heat dissipation speed is also fast, so the selected electric soldering iron has a faster heating speed and higher power. The power of our common electric soldering iron is 20W 25W 30W 35W 50W and so on. It is more appropriate to choose a power of about 30W. Here, the editor uses a soldering iron table, which is the one in Figure 1. The heating temperature can be adjusted at any time, which is convenient, but it is inconvenient to carry. The one in Figure 2 is easy to carry, but the heating is unstable.
2. Soldering iron tip
When the soldering iron is used for a long time, a layer of oxide will be formed on the tip of the soldering iron, which is not easy to tin. We can file off the oxide layer or use a knife to scrape it off. Then turn on the soldering iron and heat it slightly. You can apply rosin, and then apply solder.
3. Solder and Flux
When we choose solder, we should use solder wire with low melting point and non-corrosive flux, such as rosin. Industrial solder and corrosive acid solder oil should not be used. Of course, there is also a solder wire containing rosin on the market. We are very convenient to use.
Note: Rosin must be applied to the new electric soldering iron when it is used for the first time.
4. Solder absorber and decontamination sponge
The purpose of the tin suction device: it is used to suck off excess solder wire and remove electronic components.
Use of decontamination sponge: When using it, soak it with clean water. It is mainly used to remove the dirt on the soldering iron tip, making the soldering iron easier to tin. After the soldering iron is used, use it to clean the soldering iron tip.
5. Welding method
Action essentials: first heat and then send tin, first remove tin and then remove soldering iron.
During the preservation of electronic components, due to the effect of air oxidation, a layer of oxide film is attached to the component pins, and there are other dirt. Before welding, we must clean up the components and plate them with a layer of tin. In this way, the solder joints we welded are less likely to have virtual soldering.
Soldering temperature and soldering time
We should choose an appropriate temperature when soldering. The temperature should be higher than the soldering tin temperature. If it is too high, it is not good. If it is serious, the pad will fall off directly.
If the soldering time is too short, the temperature of the solder joints is too low, the solder joints are not fully melted, and the solder joints are rough and easy to cause false soldering. On the contrary, the soldering time is too long, the solder is easy to flow, and it is easy to cause the components to overheat and damage the components.
The amount of tin on the solder joint
We must master the amount of tin on the solder joints. The amount of solder on the solder joints should not be too small. If it is too small, the soldering will not be strong, and the solder joints will be flat, and the mechanical strength will be too poor. If there are too many, it is easy to cause a lot of appearance but the inside is not connected, and it becomes a bucket shape, which is extremely ugly. The solder should just submerge all the component leads on the soldering point, and the outline should be faintly visible.
6. Final work
After the soldering is finished, we must do the final inspection to check for missing soldering, virtual soldering, and component short circuits caused by solder flow. False soldering is difficult to find, you can use tweezers to clamp the component pins and pull it gently, if you find shaking, you should repair the soldering immediately.
