Short circuit of PCB board is the most common problem. There are generally two situations for short circuit. One is that PCB board has reached a certain service life. The second situation is that the inspection work in the production of PCB boards is not in place. But these small mistakes in production are very harmful to the whole PCB boards, and they are likely to cause scrap. So how do we check and prevent short circuits on the circuit board, the following article will introduce to you.
1. A short circuit is found. Take a board to cut the line (especially suitable for single/double-layer board cut lines after each part of the functional block is energized separately, and part of it is excluded.
2. You must be careful when welding small-size surface mount capacitors, especially the power supply filter capacitors (103 or 104), which are large in number, 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 welding.
3. If it is manual welding, develop a good habit.
(1) First, check the PCB board visually before soldering, and use a multimeter to check whether the key circuits (especially the power supply and the ground) are short-circuited.
(2) Every time a chip is soldered, use a multimeter to test whether the power supply and the ground are short-circuited.
(3) Don’t throw the soldering iron randomly when soldering. If you throw the solder onto the solder feet of the chip (especially surface mount components), it will not be easy to find.
4. Open the PCB diagram on the computer, light up the short-circuited network, and see which place is closest to it. It is most likely to be connected. Pay special attention to the short circuit inside the IC.
5. Use a short-circuit location analyzer, such as CB2000 short-circuit tracker, QT50 short-circuit tracker, ToneOhm950 multi-layer circuit short-circuit detector, etc.
6. If there is a BGA chip, since all the solder joints are covered by the chip and cannot be seen, and it is a multi-layer board (above 4 layers), it is best to separate the power supply of each chip during the design, using 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. Because the welding of BGA is very difficult, if it is not automatically welded by the machine, a little carelessness will short-circuit the adjacent power supply and the ground two solder balls.
The inspection of pcb circuit boards should not be ignored. Every step must be inspected carefully, and no suspicious points should be overlooked during the production process. This can reduce the rework rate and product scrap rate and avoid unnecessary loss.
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