Mar. 12, 2019
1. If it is artificial soldering, such as Green Solder Mask PCB. To develop good habits, first, visually inspect the PCB board before soldering, and use a multimeter to check whether the critical circuit (especially the power supply and the ground) is short-circuited. Secondly, use a multimeter to measure the power and ground each time one chip is soldered. Whether it is short-circuited; in addition, do not smash the soldering iron during soldering. If the solder is soldered to the soldering legs of the chip (especially surface-mount components), it is not easy to find.
2. Care must be taken when soldering small-sized surface-mount capacitors, especially power supply filter capacitors (103 or 104), which can easily cause short-circuit between power supply and ground. Of course, sometimes the luck is not good, the capacitor itself is short-circuited, so the best way is to check the capacitance before soldering.
3. If there is a BGA chip, since all the solder joints are invisible by the chip cover, and it is a Multilayer PCB (more than 4 layers), it is best to separate the power of each chip at the time of design, using magnetic beads or 0 ohms. The resistor is connected so that when the power supply is shorted to the ground, the magnetic bead is detected and it is easy to locate a certain chip. Because the BGA is difficult to solder, if it is not the machine's automatic soldering, the adjacent power supply and ground solder balls will be short-circuited with a little care.
4. Open the PCB on the computer, illuminate the short-circuited network, and see where it is closest to it, the easiest to connect. Pay special attention to the internal short circuit of the IC.
5. A short circuit was found. Take a board to cut the line (especially suitable for single/double board secant, each part of the function block is energized separately, part of which is excluded.
6. Use short-circuit positioning analyzer, such as: Singapore PROTEQ CB2000 short-circuit tracker, Hong Kong Lingzhi QT50 short-circuit tracker, UK POLAR ToneOhm950 multi-layer circuit short-circuit detector.