Disassembly and welding skills of the hottest chip

Disassembly and welding skills of patch components

disassembly and welding skills of patch components

in the process of learning maintenance for the first time, you should master the disassembly and welding skills of patch components. For the disassembly and welding of chip mounted components, it is advisable to use 200 ~ 280 ℃ to adjust and test the depth of carburized layer or effective hardened layer. There are two methods: metallographic method and hardness method. Warm tip soldering iron

the substrates of chip mounted resistors and capacitors are mostly made of ceramic materials, which are easy to crack by collision. Therefore, during disassembly and welding, you should master the skills of temperature control, preheating, light touch and so on. Temperature control means that the welding temperature should be controlled at about 200 ~ 250 ℃. Preheating refers to preheating the components to be welded in an environment of about 100 ℃ for 1 ~ 2 minutes to prevent sudden thermal expansion and damage of the components. Light touch means that the soldering iron head should first heat the solder joint or guide belt of the printed board, and try not to touch the components. In addition, the welding time should be controlled at about 3 seconds each time, and the circuit board should be naturally cooled at room temperature after welding. The above methods and techniques are also applicable to the welding of SMD crystal diodes and triodes

the number of pins of SMD integrated circuits is large, the spacing is narrow, and the hardness is small. If the welding temperature is improper, it is very easy to cause the pin clamp 1 straight not to be well solved, such as solder short circuit, faulty soldering, or the copper foil of printed circuit is separated from the printed board. When disassembling the chip type integrated circuit, adjust the temperature of the temperature regulating soldering iron to about 260 ℃. After all the soldering tin of the integrated circuit pins are sucked with the soldering iron head and the tin suction device, gently insert the tip tweezers into the bottom of the integrated circuit, heat it with the soldering iron, and gently lift the integrated circuit pins one by one with tweezers, so that the integrated circuit pins are gradually separated from the printed board. When lifting the integrated circuit with tweezers, it must be carried out synchronously with the heated part of the soldering iron to prevent the circuit board from being damaged by being too hasty

before replacing with a new integrated circuit, remove all the solder left by the original integrated circuit to ensure the flatness and cleanness of the pad. Then polish and clean the pins of the integrated circuit to be welded with fine sandpaper, and evenly tin them. Then align the pins of the integrated circuit to be welded with the corresponding solder joints of the printed board. During welding, gently press them on the surface of the integrated circuit with your hand to prevent the integrated circuit from moving. With the other hand, operate an electric soldering iron dipped in an appropriate amount of solder to weld and fix the pins at the four corners of the integrated circuit with the circuit board. Then check again to confirm the model and direction of the integrated circuit, and formally weld them after they are correct, Adjust the temperature of the soldering iron to about 250 ℃. One hand holds the soldering iron to heat the IC pins, and the other hand sends the solder wire to the heating pins for welding until all the pins are heated and welded. Finally, carefully check and eliminate the short circuit and faulty soldering of the pins. After the solder joint cools naturally, clean the circuit board and solder joint again with a brush dipped in anhydrous alcohol to prevent welding slag

before troubleshooting the module circuit board, it is advisable to use a brush to dip and apply a small amount of lubricating oil and anhydrous alcohol to clean the printed board, select the appropriate gear, remove the dust, welding slag and other debris on the board, and observe whether there is faulty soldering or short circuit of welding slag on the original circuit board, and find the fault point early to save maintenance time