The main hand soldering tools are electric soldering iron, heat gun, tin melting furnace, etc., which are shown below.
Soldering iron 1. Types of soldering ironsThe soldering iron is the most commonly used tool for manual soldering. According to the power, soldering irons can be divided into 15W, 20W, 35W, 60W, 300W, etc., which are suitable for welding parts of different sizes. It is recommended to weld general components using a 20 W internally heated electric soldering iron; for welding integrated circuits and vulnerable components, you can use an electric soldering iron with an energy storage device; can be used.
According to different heating methods, soldering irons can be divided into direct heating soldering irons, constant temperature soldering irons, induction soldering irons and energy storage soldering irons.
(1) Direct heating soldering iron
Direct heating electric soldering iron can be divided into external heating type (the soldering iron core is installed outside the soldering iron tip) and internal heating type (the soldering iron core is installed inside the soldering iron tip). A direct heating electric soldering iron is shown.
Figure 1-18 Electric direct heating soldering iron
Direct heating electric soldering iron is mainly composed of heating element, soldering iron head, handle, terminal and other parts. Among them, the heating element is commonly referred to as the soldering iron core, which is formed by winding nickel-chromium resistance wire on a heat-resistant and insulating material such as parent ceramic. The main difference between an internally heated soldering iron and an externally heated soldering iron is that the heating element of an externally heated soldering iron is outside the heat transfer limit, and an internally heated soldering iron is smaller in volume and weight than an externally heated soldering iron. .
A soldering iron tip is used to store and transfer heat and is usually made of copper. The shape of commonly used soldering iron tips is shown in fig. 1-19.
Fig. 1-19 Various soldering tip shapes
The handle is usually made of wood or Bakelite. If the handle is poorly designed, too high a temperature may affect operation. The mounting pin is the connection between the heating element and the power cord. Typically, a soldering iron has three connecting pins, one of which is connected to the metal case. When wiring, the sheath will be connected to the protective neutral line with a three-wire wire. When using a new soldering iron or replacing the soldering iron core, determine the ground terminal. The easiest way is to use a multimeter to measure the resistance between the case and the terminal. If the soldering iron does not heat up, you can also use a multimeter to quickly determine if the soldering iron core is damaged.
(2) Constant temperature electric soldering iron
The construction of a constant temperature electric soldering iron is shown in fig. 1-20. Because the temperature controller with magnet is installed in the head of the constant temperature electric soldering iron, constant temperature can be realized by controlling the on-time. When the electric soldering iron is energized, the temperature of the soldering iron rises. When the set temperature is reached, the magnetism disappears because the strong magnetic sensor reaches the Curie point, so that the contact of the magnetic core is disconnected and the power supply of the electric soldering iron stops; when the temperature is lower than that of the strong magnetic sensor When the Curie point is reached, the strong magnet returns to magnetism and attracts the permanent magnet in the magnetic core switch, so that the contact of the control switch is connected and continues to supply power to the electric soldering iron; this cycle achieves the purpose of temperature control.
Because the constant temperature electric soldering iron has the characteristics of constant temperature, it is especially suitable for soldering components requiring soldering temperature and time, such as integrated circuits, transistors, etc., and will not cause component damage due to high temperature soldering.
Figure 1-20 Constant temperature electric soldering iron
(3) Induction soldering iron
The induction soldering iron is also called the fast heating soldering iron, commonly known as the welding torch. Inside it is actually a transformer, the secondary winding of this transformer has only 1 to 3 turns, when the primary winding is energized, a large current induced by the secondary winding passes through the heating element, so that the soldering iron tip connected to it quickly reaches the required temperature for welding.
The characteristic of an induction soldering iron is that it heats up quickly. Generally, the soldering temperature can be reached within a few seconds after the power is turned on. Therefore, it does not need to be constantly turned on, like a direct-heated soldering iron. . During operation, you only need to press the switch on the handle for a few seconds to weld, which is especially suitable for intermittent work. However, since the soldering iron tip is actually the secondary side of the transformer, it cannot be used for some charge-sensitive devices such as IGMOS circuits.
(4) Electric soldering iron with energy storage
Energy storage electric soldering iron is especially suitable for soldering charge sensitive FET circuits. The characteristic of the energy storage electric soldering iron is that the electric soldering iron itself is not connected to a power source. When the electric soldering iron is connected to the auxiliary power supply, the electric soldering iron is in a state of energy storage, and the electric soldering iron is removed during welding, and several solder joints are simultaneously welded by the energy stored in the electric soldering iron.
2. How to use an electric soldering ironSoldering technology is a basic technology that radio amateurs must master, and it takes a lot of practice to master it professionally. The following explains in detail how to use the soldering iron.
1) Polish pads and component leads with fine sandpaper and apply flux.
2) Heat up the soldering iron, apply the flux when the solder has just melted, and then spread the solder evenly on the soldering iron tip so that the soldering iron tip is evenly covered with a layer of tin.
3) Moisten the required amount of solder with the tip of the soldering iron and touch the soldering point.
4) After soldering, place the soldering iron on the soldering iron stand.
5) Then use alcohol to clean the residual flux on the PCB to prevent the charred flux from affecting the normal operation of the circuit.
When welding, pay attention to the following points:
1) It is necessary to select suitable solder and low melting point solder for welding electronic components.
2) As a flux, use 25% rosin dissolved in 75% alcohol (weight ratio).
3) The soldering time should not be too long, otherwise you can easily burn the components. If necessary, use tweezers to pinch the pins to help dissipate heat.
4) Solder joints should be in the form of sinusoidal peaks, the surface should be light and smooth, without tin spikes, and the amount of tin should be moderate.
5) The integrated circuit must be soldered last, and the soldering iron must be securely grounded during soldering, or it can be soldered with residual heat after power off. Or use a dedicated IC connector, and then connect the IC after soldering the connector.
6) Put the soldering iron back on the stand after soldering.
Heat gunThe heat gun is one of the important electronic equipment maintenance tools, mainly composed of main components such as air pump, air flow stabilizer, linear circuit board, handle and body. Its main function is to desolder small SMD components and SMD integrated circuits. On fig. Figure 1-21 shows the Model 850 heat gun.
Figure 1-21 Model 850 Heat Gun
1. How to use a heat gunThe method of using the heat gun is as follows:
1) First, set the temperature switch of the hair dryer to the appropriate gear (levels 1-5), then set the wind speed switch to the appropriate gear (levels 1-5), and then turn on the power switch. heat gun.
2) Next, moisten the component's pins with a small amount of solder paste.
3) Then place the components in the soldering position, and then direct the heat gun to vertically heat the SMD components.
4) After heating for 3 seconds, stop heating when the solder melts. Finally, use an electric soldering iron to re-solder the component pins and add enough solder.
5) Finally, turn off the hair dryer's power switch. Please note that if you need to unplug the power cord or turn off the power cord switch, you will need to wait for the hair dryer fan to stop cooling before unplugging the power cord.
2. Precautions when using a hair dryerWhen using a hair dryer, please note the following:
1) Read the instructions carefully before using the hair dryer for the first time.
2) The ground wire must be connected before using the hair dryer to prepare for the discharge of static electricity.
3) Do not put the metal conductor into the mesh at the front end of the soldering iron, which will damage the heating element and cause electric shock to a person.
4) After turning on the power, select a variety of air nozzles and tin suction needles (with accessories) according to needs, then adjust the hot air temperature adjustment button (HEATER) to the appropriate temperature, and at the same time turn the hot air volume adjustment button air according to needs (AIRCAPACITY). Adjust the required air volume and it can be used when the preheat temperature reaches the set temperature.
5) If it is not used for a short period of time, set the hot air volume adjustment button to the minimum position and the hot air temperature adjustment button to the middle position to keep the heater in a state of keeping warm, and then adjust the hot air volume adjustment button air temperature and hot air temperature adjustment when using the button.
6) There is an overheat protection circuit breaker inside the hair dryer. When the nozzle overheats, the protection circuit breaker is activated and the hair dryer stops working. The hot air volume adjustment button should be adjusted to the maximum, and the heater can work after a delay of about 2 minutes, and the machine returns to normal mode.
7) Pay attention to the cooling of the fuselage after use. After the power is turned off, the heatingThe air tube automatically releases cold air for a short time. Do not unplug the power plug during the cooling period.
8) To avoid accidents, place the pen on the stand when not in use.
Tin Smelting FurnaceThe tin furnace is a metal furnace with electric heating rods. After heating with electricity, the tin is placed in a furnace, and when heated, the tin melts into tin water. When removing a slot or interface with a large number of pins, properly immerse the slot or interface pins in tin water, move the slot or interface left and right with a little force, and then it can be disassembled. On fig. 1-22 shows a furnace for melting tin.
Figure 1-22 Tin Smelting Furnace