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PCB circuit board short circuit inspection method
摘要：If it is manual welding, it is necessary to develop a good habit. First, check the PCB board visually before welding, and use a multimeter to check whether the key circuits (especially the power supply and ground) are short-circuited; Use a multimeter to test whether the power supply and the ground are short-circuited; in addition, do not throw the soldering iron randomly when soldering, if the solder is thrown on the solder pins of the chip (especially the surface mount components), it is not easy to find.
1. If it is manual welding, it is necessary to develop a good habit. First, check the PCB board visually before welding, and use a multimeter to check whether the key circuits (especially the power supply and ground) are short-circuited; Use a multimeter to test whether the power supply and the ground are short-circuited; in addition, do not throw the soldering iron randomly when soldering, if the solder is thrown on the solder pins of the chip (especially the surface mount components), it is not easy to find.
3. A short circuit is found. Take a board to cut the line (especially suitable for single/double-layer board), after cutting the line, energize each part of the functional block separately, and remove some of them.
4. Use a short-circuit positioning analyzer.
5. If there is a BGA chip, since all the solder joints are covered by the chip and invisible, and it is a multi-layer board (more than 4 layers), it is best to separate the power supply of each chip during design, and use magnetic beads or 0 ohms. Resistor connection, so that when the power supply and the ground are short-circuited, the magnetic bead detection is disconnected, and it is easy to locate a certain chip. Due to the difficulty of soldering the BGA, if it is not automatically soldered by the machine, it will short-circuit the adjacent power supply and the two solder balls of the ground if you are not careful.
2. Open the PCB diagram on the computer, light up the short-circuited network, and see where the closest one is, which is most likely to be connected to one piece. Pay special attention to the short circuit inside the IC.
3. A short circuit is found. Take a board to cut the line (especially suitable for single/double-layer board), after cutting the line, energize each part of the functional block separately, and remove some of them.
4. Use a short-circuit positioning analyzer.
5. If there is a BGA chip, since all the solder joints are covered by the chip and invisible, and it is a multi-layer board (more than 4 layers), it is best to separate the power supply of each chip during design, and use magnetic beads or 0 ohms. Resistor connection, so that when the power supply and the ground are short-circuited, the magnetic bead detection is disconnected, and it is easy to locate a certain chip. Due to the difficulty of soldering the BGA, if it is not automatically soldered by the machine, it will short-circuit the adjacent power supply and the two solder balls of the ground if you are not careful.
6. Be careful when welding small-sized surface mount capacitors, especially the power filter capacitors (103 or 104), which can easily cause a short circuit between power and ground. So the best way is to check the capacitors before soldering.
