Inspection method for short circuit of PCB board
1. If it is manual soldiering, it is necessary to form a good habit. First, it is necessary to visually check the PCB board before solding, and check whether the key circuit (especially the power supply and ground) is short circuit with the multimeter;Second, each time it is necessary to measure with a multimeter after soldering a chip whether the power and ground short circuit;In addition, do not throw the soldering iron when soldering, if the solder to the chip soldering feet (especially the table stick elements), it is not easy to check.
2. Open the PCB diagram on the computer, light up the short-circuit network, and see where is nearest and most easily connected together.Pay special attention to IC internal short circuit.
3. When short circuit is found.Take a board to cut the line (especially suitable for single/double board). After cutting the line, electrify each part of the functional block separately and exclude some parts.
4. Use short-circuit positioning analyzer, such as PROTEQ CB2000 short-circuit tracker from Singapore, QT50 short-circuit tracker from Hong Kong, POLAR ToneOhm950 multi-layer short-circuit detector from Britain, etc.
5. If there is a BGA chip, it is better to divide the power supply of each chip and connect it with magnetic beads or 0 ohm resistance during design, because all soldering spots are covered by the chip and cannot be seen, and it is multilayer (more than 4 layers). In this way, when there is a short circuit between the power supply and the ground, disconnect the magnetic beads and detect it, so that it is easy to locate a chip.Because BGA is difficult to weld, if it is not automatically soldered by the machine, it will short-circuit the adjacent power supply and the two soldering balls on the ground.
6. Be careful when soldering the small size surface capacitor, especially the power filter capacitor (103 or 104), the number is large, it is easy to cause a short circuit between the power and the ground.Of course, it will encounter the capacitor itself short circuit.