5-step method for correct soldering with electric soldering iron
1. One scrape
Scraping means that before welding, the surface of the metal to be welded should be cleaned as shown in Figure 3, and the oxide layer on the welding surface can be scraped off with a knife, scrap steel saw blade, etc. , oil or insulating paint until the new metal surface is exposed. The self-made printed circuit board also needs to carefully polish the side of the copper clad foil with fine sandpaper or water sandpaper before soldering. "Scraping" is a key step to ensure the quality of welding, but it is often ignored by beginners. If the scraping is not in place, the tinning and welding will not be good. It should be noted that some component leads have been plated with silver, gold or tinned. As long as they are not oxidized or peeled off, there is no need to scrape them. If there is dirt on the surface, it can be erased with a rough eraser. The choice of rough eraser works best with a large eraser for drawing. Some gold-plated crystal triode pin leads, etc., will be difficult to plate with tin after the coating is scraped off. No matter what kind of "scraping" is adopted, it is necessary to pay attention to constantly rotating the component pins to clean all around the pins.
2. Second plating
Plating is to enamell the parts to be soldered. After "scraping" the component pins, wire heads and other soldering parts, an appropriate amount of flux should be applied immediately, and a thin layer of tin should be plated with an electric soldering iron to prevent the surface from re-oxidizing and improve the solderability of the components. sex. The plated solder layer is required to be thin and uniform, so the amount of tin on the tip of the soldering iron should not be too much each time. For components such as crystal diodes and transistors that are afraid of heat, you must use tweezers or needle-nose pliers to clamp the root of the lead pin to help dissipate heat, and then tin-plate it. Tinning of components is an important process step to prevent hidden dangers such as false soldering and false soldering in soldering technology, and it must not be sloppy.
3. Three tests
The test is to check the components that have been tinned to see if the components have scalding, deformation, lap welding (short circuit), etc. under the high temperature of the electric soldering iron. For components such as capacitors, transistors, and integrated circuits, a multimeter should be used to check whether their quality is reliable, and components that are found to be of unreliable quality or damaged must not be used again.
Electric soldering iron is an essential tool for electronic production and electrical maintenance. Its main purpose is to weld components and wires. According to the mechanical structure, it can be divided into internal heat type electric soldering iron and external heat type electric soldering iron. Tin-type soldering irons are divided into high-power soldering irons and low-power soldering irons according to different uses. This article mainly introduces the 5-step method of correct soldering with electric soldering iron_Summary of key points of electric soldering iron welding technology and other aspects.
4. Four welding
Soldering is to solder the "test" qualified components to the printed circuit board or the designated position as required. When soldering, you must master the temperature of the electric soldering iron and the soldering time. If the temperature is too low and the time is too short, the soldered tin surface will have burr-like tails, the surface is not smooth, or even bean curd residue. After all evaporated, there is a certain amount of flux between the solder and the metal. After cooling, the solder and the metal surface are stuck by the flux (rosin), and can be pulled apart with a little force. This is the so-called false soldering.
5. Five checks
The inspection is to check the welding quality of the welded circuit. There should be no false welding, virtual welding, open circuit and short circuit in the solder joints, especially whether the pins of polar components such as electrolytic capacitors and transistors are welded correctly. The quality of welding can be judged by the color and gloss of the solder joints, the degree of diffusion, and the amount of solder. Good welding, the solder joints have a unique bright white luster, which can be seen at a glance based on experience; if the color and luster of the solder are stained or the surface is uneven, it indicates poor welding.
