Disassembly Techniques for Chip Components on PCBs
Disassembly Techniques for Chip Components on PCBs
Chip components on printed circuit boards (PCBs) are new types of miniature components with no or short leads. They are directly mounted on the PCB and are specialized devices for surface mount technology. Chip components have advantages such as small size, light weight, high mounting density, high reliability, strong vibration resistance, good high-frequency characteristics, and strong anti-interference ability. They are currently widely used in computer equipment, mobile communication equipment, camcorders, color TV tuners, VCDs, and other products, and their development is rapid.
Common chip components include: (1) Chip resistors (2) Chip capacitors (3) Chip inductors (4) Chip diodes (5) Chip transistors (6) Chip miniature integrated circuits. These chip components are very small, sensitive to heat and impact, and some have many leads, making disassembly difficult and causing significant challenges to maintenance. Therefore, scientific disassembly methods are very important. Common disassembly methods are as follows.
1. Dedicated Soldering Iron Tip Removal Method Purchase a dedicated "∏-shaped" soldering iron tip. The width and length of the notch on the "∏-shaped" tip can be determined according to the size of the component being removed. A dedicated soldering iron tip can melt the solder on both sides of the leads of the component simultaneously, thus facilitating the removal of the component. Alternatively, a homemade soldering iron tip can be used for removal.
Homemade Method:Select a section of copper tubing with an inner diameter matching the outer diameter of the soldering iron tip. Flatten one end with pliers or a hammer, and drill a small hole, as shown in Figure (a). Then, longitudinally cut two copper plates or copper tubing, flatten them to the same length as the component being removed, and drill small holes, as shown in Figure (b). Flatten the end faces, grind them clean, and finally assemble them with bolts into the shape shown in Figure (c). Place the tip on the soldering iron tip, heat it, and tin it. It is then ready for use. For rectangular chip components with two solder joints, simply flatten the soldering iron tip so that the width of the end face equals the length of the component. This allows for simultaneous heating and melting of both solder joints, enabling the removal of the chip component.
2. Solder Absorbing Copper Mesh Method Soldering copper mesh is a mesh strip woven from fine copper wire. Metal shielding wire from cable or multi-strand flexible wire can also be used. To use, cover the multi-pin lead with the mesh, apply rosin-alcohol flux, heat with a soldering iron, and pull the mesh. The solder on each pin will be absorbed by the mesh. Cut off the solder-adsorbed mesh, repeating several times until the solder on the pins gradually decreases until the pins separate from the printed circuit board.
3. Melted Solder Cleaning Method When the solder on a multi-pin component is melted using an anti-static soldering iron, use a toothbrush, paintbrush, or similar brush to clean the solder. This also allows for quick component removal. After removing the component, clean the printed circuit board promptly to prevent residual solder from causing short circuits in other parts of the circuit.
4. Lead Pull Method This method is suitable for removing chip-mounted integrated circuits. Use a piece of appropriately thick, strong enameled wire, threaded through the gap inside the pins of the integrated circuit. Fix one end of the wire in a suitable position, and hold the other end by hand. When the solder melts, pull the wire to "cut" the solder joint, separating the integrated circuit pin from the printed circuit board.
5. Desoldering Pump Method There are two types of desoldering pumps: ordinary desoldering pumps and desoldering soldering irons. With an ordinary desoldering pump, press down the piston rod. When the soldering iron melts the solder joint of the component to be removed, place the desoldering pump nozzle close to the melting point and press the release button. As the piston rod springs back, it sucks away the molten solder. Repeat several times to separate the component from the printed circuit board.
A desoldering soldering iron is a specialized tool that combines an ordinary desoldering pump and a soldering iron. Its usage is the same as an ordinary desoldering pump. It is important to note that static electricity must be prevented during localized heating, and the power of the soldering iron and the size of the soldering tip should be appropriate.
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