What are the precautions and techniques for using the soldering iron?

What are the precautions and techniques for using the soldering iron?

Why can maintenance personnel repair the machine without the circuit diagram? And some maintenance staffs can judge the fault problem only by the appearance of the components? Therefore, it is very important for friends who are first contacted with maintenance to understand the circuit diagram when repairing the motherboard. Next, I will give you a detailed introduction to the problems and precautions in the soldering process of the electric soldering iron, hoping to improve your maintenance technical ability.

Problems in welding:

1. Excessive force;
2. The temperature is too high;
3. Unsuitable soldering iron tip;
4. Transfer welding;
5. Improper use of flux solder paste;
6. Improper maintenance of the soldering iron tip and no tinning.

Welding strength:

1. The function of the electric soldering iron is to melt the solder and solder the parts together;
2. Excessive force will cause the chip pins to be broken. The circuit board is damaged, the soldering iron is damaged, etc.;
3. Using intensity: experience the feeling of touching and pushing.

Welding temperature:

1. Excessive temperature causes problems: the soldering iron tip burns black, serious bulging of the circuit board, the flux solder paste evaporates immediately, and the soldering is not smooth;

2. Because the temperature of each soldering station is not very accurate, even the same manufacturer has this problem;
3. The temperature is about 350 degrees, use the solder paste to touch the tip of  the electric soldering iron, and watch the smoke time of the tip of the electric soldering iron;
4. Normally, between 10-15 seconds, the temperature is too high when the time is short, and the temperature is not enough when extended.

Inappropriate soldering iron tip

1. Most of the parts we welded use pointed soldering iron tips;
2. Pay attention to protect the parts from being taken away when the peripheral parts are very dense;
3. The head is too large, which is not conducive to the welding of small parts, and the pointed head is more conducive to improving the accuracy of welding.

Transfer welding

1. Wrong approach: first touch the solder paste to the soldering iron tip and then heat the soldering iron back and forth on the soldered parts. Since the soldering iron tip has not touched the soldering parts, most of the flux has evaporated, resulting in soldering failure.

2. The correct method: Put the solder paste on the pins of the parts to be soldered, and put the soldering iron on the solder paste. After the solder paste melts, immediately wrap the pins of the parts, and continue to add solder paste when necessary.

Improper use of flux

1. Flux can make the solder paste better melt and fuse with the pins of the part during soldering.
2. Everything has a degree. When a large amount of flux is added, the evaporated flux residue becomes a solder resist, making soldering more difficult.

Improper maintenance of the soldering iron

1. When the soldering iron tip is improperly maintained, it will cause many problems.
2. The soldering iron tip is not tinned: A layer of oxide on the soldering iron tip prevents the heat from passing out. At this time, many people think that the temperature is not enough, so they increase the temperature of the soldering iron. Although the solder paste melts, the flux evaporates immediately. If there is no way to complete the drag soldering, many soldering pastes will be added. The soldering paste will continue to erode the soldering iron tip and make the soldering iron tip more oxidized.
3. There is also a situation where the soldering iron is left on for a long time and burns dry, causing the soldering iron tip, handle, and even the central unit to be scrapped, so turn it off when not needed.

Capacitor resistance welding skills:

1. General welding specifications are 0805 and 0603, and a protable desoldering gun is recommended for smaller ones.

2. Pay attention to the welding posture: the board must be placed on the table, and your elbows should not leave during welding to prevent handshaking.
3. As the current boards use lead-free solder, which has a relatively high melting point, lead solder is added to make soldering more convenient.
4. After the two ends of the component are heated simultaneously, use solder paste and tweezers when soldering to prevent the component from being stained.