Potentiometer welding technology sharing

Since the solder tabs or leads of the potentiometer terminal are relatively short, it is necessary to pay attention to the heating temperature not to be too high when soldering in the miniaturized printed circuit board or hybrid integrated circuit. 350. C, time 35, 270. C, time 5s). otherwise. Radiant heat generated by solder baking, solder spatter, printed circuit board bending, or substrate deformation, etc., may all be the cause of potentiometer failure. If the wiring is wrong, you should be more careful when removing the wiring, especially when wiping the wiring from the printed circuit board or the substrate of the hybrid integrated circuit.

1. Wipe frequently to keep the tip of the soldering iron clean. Because the energized electric soldering iron tip is in a high temperature state for a long time, its surface is easily oxidized or burned to death, which makes the thermal conductivity of the soldering iron tip worse and affects the welding quality. Therefore, you can wipe the impurities on the soldering iron tip with a damp cloth or a damp sponge. When the temperature is too high, you can temporarily unplug the plug or dip rosin to cool down, so that the soldering iron tip can be properly tinned at any time.

2. Precautions for tinning: If the surface of the welding parts and solder joints has rust stains, dirt or oxides, they should be cleaned before welding, so that the surface of the welding parts or solder joints can be tinned.

3. The welding temperature should be appropriate, not too high or too low. In order to make the temperature appropriate, an electric soldering iron with appropriate power should be selected according to the size of the potentiometer. When the power of the selected electric soldering iron is constant, attention should be paid to controlling the length of the heating time. When the solder is automatically scattered from the tip of the soldering iron to the object to be soldered, it indicates that the heating time is sufficient. At this time, quickly remove the tip of the soldering iron, leaving a smooth solder joint at the soldered area. If after removing the soldering iron, there is little or no tin left in the soldered area, it means that the heating time is too short, the temperature is not enough, or the soldered object is too dirty; if the soldering tin flows down before the soldering iron is removed, it means The heating time is too long and the temperature is too high. Generally, the temperature control of the soldering iron tip is the best soldering temperature when the flux melts faster and does not emit smoke.

4. The amount of tin applied should be moderate. The amount of dipping tin of the electric soldering iron can be determined according to the size of the required solder joints, so that the solder is enough to cover the toughness of the solder and form a suitable and smooth solder joint. The solder joints are not too much tin, tin is better, on the contrary, this kind of solder joints is more likely to be soldered, and it may be that the solder is accumulated on it instead of soldering on it. If the amount of tin applied at one time is not enough, it can be repaired again, but the soldering iron must be removed after the tin applied last time is melted together; if the amount of tin applied at one time is too much, the soldering iron head can take away an appropriate amount.

5. The welding time should be controlled well and not too long. The proper use of welding time is also an important part of welding skills. If it is soldering of printed circuit boards, 2~3S is generally appropriate. If the soldering time is too long, the flux in the solder will completely volatilize, and the flux will be lost, and the surface of the solder joint will be oxidized, causing the solder joint surface to be rough, black, not shiny, burr or flowing. At the same time, the soldering time is too long and the temperature is too high, and it is easy to burn the components or the copper foil of the printed circuit board. If the soldering time is too short and the soldering temperature cannot be reached, the solder will not be fully melted, which will affect the wetting of the flux and easily cause false soldering.

6. During the solidification of the solder joints, remember not to touch the solder joints with your hands. Before the welding point is completely solidified, even a small vibration will cause the welding point to deform and cause false welding. Therefore, the soldering parts should be fixed before the soldering iron tip is withdrawn, such as clamping with tweezers, or blowing quickly with the mouth after the soldering iron tip is withdrawn. The purpose of these methods is to shorten the time for the solder joint to solidify.

7. When a welding point is finished welding, the selection of the withdrawal angle of the soldering iron tip is also particularly important. When the soldering iron tip is evacuated diagonally upward, a small amount of tin bead is taken away from the soldering iron tip, which can form a smooth solder joint; when the soldering iron tip is withdrawn vertically upwards, it can form a solder joint with sharp burrs; when the soldering iron tip is horizontally oriented When evacuating, the soldering iron tip can take away most of the tin beads.

In summary, the most direct and fundamental way to avoid false soldering is to do a good job of cleaning before soldering. It is best not to use solder paste for cleaning, because it contains acidic materials, which may corrode the potentiometer pins in the future and cause false weld. After removing the oxides, tin the soldering surface first, and then soldering is easy, and it is not easy to produce false soldering. You should also hang tin on the potentiometer pins, and master the soldering time, so as to ensure the quality of soldering, thus ensuring the quality of the entire potentiometer.