PCB circuit board short circuit inspection and prevention:
One of the most common problems encountered in the maintenance of electronic products is short circuit. We can only try to avoid short circuits, we must grasp every step of production, and not miss every suspicious point during inspection.
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.
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 was 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 short circuit location analyzer, such as: Singapore PROTEQ CB2000 short circuit tracker, Hong Kong Lingzhi Technology QT50 short circuit tracker, British POLAR ToneOhm950 multi-layer board short circuit detector, etc.
5. 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 the power supply and the ground. Of course, sometimes with bad luck, the capacitor is short-circuited, so the best way is to test the capacitor before soldering.
6. 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 there is a short circuit between the power supply and the ground, the magnetic bead detection is disconnected, and it is easy to locate a certain chip. Due to the difficulty of soldering BGA, if it is not automatically soldered by machine, it will short-circuit the two adjacent power supply and ground solder balls if you are not careful.
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