PU nylon coated glovesIndustry description is neat and convenient for welding. We need sticky pads or sticky rollers for dust removal
1. It is not difficult to master the soldering with a manual soldering iron, but it requires certain technical skills. People who have been engaged in the production of electronic products for a long time have summarized the four elements of soldering: materials, tools, methods, methods and operators.
2. Correct posture for welding operation:
Mastering the correct operating posture can ensure the physical and mental health of the operator and reduce labor injuries. In order to reduce the harm of chemical substances volatilized during welding heating to people and reduce the inhalation of harmful gases, under normal circumstances, the distance from the soldering iron to the nose should be no less than 20CM, usually 30CM is appropriate.
3. Basic steps of welding operation:
(1) Prepare for welding; hold the welding wire in your left hand and the soldering iron in your right hand to prepare for welding. The soldering iron tip should be kept clean, free of oxides such as welding slag, and coated with a layer of solder on the surface.
(2) Heat the weldment; place the tip of the soldering iron against the joint between the two weldments and heat the entire weldment for about 1 to 2 seconds. For weldments on a printed circuit board, be sure to make the soldering iron contact the leads of the components on the pad at the same time.
(3) Feed the solder wire; when the soldering surface is heated to a certain temperature, the solder wire contacts the workpiece from the opposite side of the soldering iron.
(4) Remove the solder wire; when the solder wire melts a certain amount, immediately move the solder wire to the upper left 450 direction.
(5) Remove the soldering iron; after the solder soaks the soldering part of the pad, move the soldering iron 450 degrees to the upper right to end the soldering. From the third step to the end of the fifth step, it takes about 1 to 3 seconds.
4. Welding temperature and heating time Appropriate temperature is essential for forming a good solder joint. After testing, it was found that the time the soldering iron tip stays on the weldment is proportional to the increase in the temperature of the weldment. When the same soldering iron heats weldments of different heat capacities, if you want to achieve the same welding temperature, you can control the heating time. But in practice, the heating time cannot be determined solely based on this relationship. For example, when a low-power soldering iron is used to heat a larger weldment, no matter how long the soldering iron stays, the temperature of the weldment will not rise, because the heat supply capacity of the soldering iron is less than the heat lost by the weldment and the soldering iron in the air. In addition, to prevent internal overheating damage, some components are not allowed to be heated for a long time. Excessive heating may cause damage to the components and has the following hazards and external characteristics:
(1) Poor appearance of solder joints. If excessive heating continues after the solder has soaked the workpiece, the flux will evaporate completely, causing the molten solder to overheat; when the soldering iron is removed, the solder tip is easily pulled, and the surface of the solder joint turns white, rough particles appear, and it loses its luster.
(2) High temperature causes the added rosin flux to decompose and carbonize. Rosin generally begins to decompose at 210°C, not only losing its flux function, but also causing slag inclusions in the solder joints and forming defects. If the rosin is found to be black during welding, it must be caused by too long heating time.
(3) Excessive heating will damage the adhesive layer of the copper foil on the printed circuit board, causing the copper foil pad to peel off. Therefore, accurately controlling the heating temperature during the appropriate heating time is the key to high-quality welding.
5. Specific techniques of welding operation
(1) Keep the soldering iron tip clean.
(2) Increase the contact area to transfer heat quickly.
(3) Heating depends on the solder bridge
(4) There are some rules for soldering iron withdrawal
(5) The amount of solder should be moderate
When bending components, sticky pads or sticky rollers should be used to remove dust
(1) Bending components In order to make the components neatly arranged on the printed circuit board and easy to solder, we A sticky pad is required to remove dust. Before installation, the component leads are usually bent into a certain shape by hand or special machinery. In order to avoid damage to components and components, the following points should be noted when shaping components: 1. The minimum radius of the lead when bending shall not be less than 2 times the lead diameter, and "dead bends" are not allowed; 2. The distance between the lead bending point and the component body shall be at least 2mm, and the lead must not be bent from the root. For glass-encapsulated components that are prone to cracking, a sticky roller is required to remove dust during lead forming.
3. The appearance of the components cut into shape must be beautiful and free of burrs. If necessary, use a sticky roller or sticky pad to remove dust.
(2) Component insertion When components are installed on the printed circuit board, whether it is horizontal or vertical installation, the leads of the components should be as short as possible. When assembling horizontally on a single-sided printed circuit board, low-power components are always parallel and close to the board surface; on a double-sided board, the components can be about 1-2mm away from the board surface to avoid reducing the adhesion of copper foil to the substrate due to the heating of the components, and prevent the exposed parts of the components from short-circuiting with the printed wires. The following principles should be observed when installing components:
1. When assembling, components that need mechanical fixation should be installed first, such as heat sinks, brackets, clips, etc. of power devices, and then components that are fixed by welding should be installed. Otherwise, when mechanically fastened, the printed circuit board will be deformed by force and other components will be damaged.
2. When installing various components, their markings (values, precision, etc. marked with color codes or characters) should face left and down, and pay attention to the consistency of the marking reading direction (from left to right); for horizontally installed components, try to make the lengths of the leads at both ends equal and symmetrical, and place the components in the center of the two holes and arrange them neatly. For components with polarity, ensure the correct direction.
3. When components are installed vertically on the printed circuit board, more components are accommodated per unit area, which is suitable for products with small space in the casing and compact and dense components. However, the mechanical properties of vertical assembly are poor and the vibration resistance is weak. If the components are tilted, they may contact adjacent components and cause short circuits.
