There are generally two cases of short circuit, one is that the pcb has reached a certain service life. The second situation is that the inspection work in the production of pcb circuit boards is not in

place. However, these small mistakes in production are very harmful to the entire pcb board, and it is likely to cause scrapping. So how do we check and prevent circuit board short circuit, Youliang

to introduce to you.

1. Short circuit is found. Take a board to cut the line (especially suitable for single/double board cut line after each part of the function block is energized, a part of the part is excluded.

2. small size of the surface capacitor welding must be careful, especially the power filter capacitor (103 or 104), the number is large, it is easy to cause short circuit between the power supply and the

ground. Of course, sometimes bad luck will encounter that the capacitor itself is short-circuited, so the best way is to detect the capacitor before welding.

3. if it is manual welding, to develop good habits.

(1) First of all, visually check the PCB board before welding, and check whether the key circuit (especially the power supply and ground) is short circuit with a multimeter;

(2) After each welding of a chip, use a multimeter to test whether the power supply and the ground are short circuit;

(3) Do not toss the soldering iron when welding, if the solder is thrown to the welding foot of the chip (especially the sticker component), it is not easy to find.

4. Open the PCB diagram on the computer, light the short-circuit network, and see where it is closest and most easily connected to a piece. Pay special attention to the IC internal short circuit.

5. the use of short-circuit positioning analyzer, such as: CB2000 short-circuit tracker, QT50 short-circuit tracker, ToneOhm950 multi-layer circuit short-circuit detector.

6. if there is a BGA chip, because all the solder joints are covered by the chip can not be seen, but also multi-layer circuit board (more than 4 layers),

Therefore, it is best to split the power supply of each chip at the time of design, and connect it with magnetic beads or 0 ohm resistance, so that when there is a short circuit between the power supply

and the ground, disconnect the magnetic bead detection, and it is easy to locate a chip. Due to the difficulty of BGA welding, if it is not automatically welded by the machine, a little attention will

short-circuit the adjacent power supply and the two welding balls. PCB inspection work can not be ignored, each step must do a good job of inspection work, must be carefully treated, the production

process can not let go of any point of doubt, which can reduce the rework rate and product scrap rate, can avoid unnecessary losses.