The practical summary of welding skills of electronic components has increased knowledge again

Date：2021-12-09 14:29:11Views：1172

In the production and manufacture of electronic products in the electronic industry, the joints of components need to be welded with solder wire, and the quality of welding has a great impact on the quality of production and manufacture. Therefore, learning electronic welding technology is the most basic and important skill in the solder industry.

Treatment before welding

Before welding, the welding parts of component terminals or circuit boards shall be welded, generally including "scraping", "plating" and "measuring".

"Scraping" is to clean the welding parts before welding. Generally, the tools used are knife and fine sandpaper. The terminals of integrated circuits are generally not cleaned before welding, but the terminals shall be kept clean. For self-made printed circuit boards, first polish the surface of copper foil with fine sandpaper, clean the dirt on the printed circuit board, and then apply rosin alcohol solution or flux before use. For the alloy lead wire plated with gold and silver, the coating cannot be scraped off, and the dirt on the surface can be removed with an eraser.

"Plating" refers to tin plating on the scraped parts of the components. The specific method is to dip rosin alcohol solution into the scraped parts of the components, press the hot soldering iron head with tin on the components, and rotate the components to evenly coat a thin tin layer. For multi strand wire conductors, they shall be screwed together after polishing, and then tinned.

After scraping, a small amount of flux shall be coated on the lead of components immediately, and then a thin tin layer shall be plated on the lead with an electric soldering iron to avoid reoxidation on its surface, so as to improve the solderability of components.

"Test" is to use a multimeter to test whether the quality of all tinned components is reliable after "plating". If there are components with unreliable quality or damaged components, they shall be replaced with components of the same specification.

Specific operation steps

After pre welding treatment, welding can be formally carried out. When welding, pay attention to different welding objects, and the working temperature of electric soldering iron is also different. When judging the temperature of the soldering iron head, touch the electric soldering iron with rosin. If there is a "squeak" sound when touching, it indicates that the temperature is appropriate; If there is no sound and the rosin can only melt reluctantly, it indicates that the temperature is low; If the soldering iron head smokes a lot when it touches rosin, it indicates that the temperature is too high.

Generally speaking, the welding steps mainly include the following three steps.

a. First melt a small amount of solder and rosin on the soldering iron head, and align the soldering iron head and solder wire with the solder joint at the same time.

b. When the flux on the soldering iron head is not volatilized, the soldering iron head and the solder wire are in contact with the solder joint at the same time to start melting the solder.

c. When the solder infiltrates the whole solder joint, remove the soldering iron head and solder wire at the same time.

The time of welding process is generally 2 ~ 3S. When welding integrated circuits, the amount of solder and flux should be strictly controlled. In order to avoid damage to the integrated circuit due to poor insulation of the electric soldering iron or the induced voltage of the internal heater to the shell, the method of unplugging the power plug of the electric soldering iron and welding while hot is often used in practical application.

False welding and welding quality

During welding, ensure that each welding point is firmly welded and in good contact. Qualified solder joints have bright, smooth and burr free solder spots, moderate amount of tin, solid fusion of tin and welded objects, and no false welding and false welding.

False soldering is a false soldering, which means that there is only a small amount of tin at the solder joint, which seems to be welded on the surface, but it is not welded in fact, resulting in poor contact, on and off. Sometimes the lead can be pulled out from the solder joint by pulling it out by hand. The faults caused by this kind of solder joint are sometimes absent and difficult to find.

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