How to check and prevent PCB circuit board short circuit?
PCB circuit board short circuit is the most common problem, there are generally two cases of short circuit, one is pcb circuit board has reached a certain useful life. The second situation is that pcb circuit board production inspection is not in place. However, these small mistakes in the production of the entire pcb circuit board damage is very great, it is likely to cause scrap situation. So how do we check and prevent circuit board short circuit, Sunsoar Circuit technology to tell you about.
1. A short circuit was found. Take a board to cut the line (especially suitable for single/double board cut lines and then power each part of the function block, part of the exclusion.
2, small-size surface mount capacitor welding must be careful, especially the power filter capacitor (103 or 104), a large number, it is easy to cause a short circuit between the power supply and the ground. Of course, sometimes bad luck, you will encounter the capacitor itself is a short circuit, so the best way is to test the capacitance before welding.
3, if it is artificial welding, to develop good habits.
(1) First, visually inspect PCB boards before welding, and use a multimeter to check if critical circuits (especially power and ground) are short-circuited;
(2) Use a multimeter to measure whether the power supply and the ground are short-circuited each time a chip is soldered.
(3) Do not whip the soldering iron during soldering. If the solder is thrown onto the solder fillet of the chip (especially the surface mount component), it is not easy to find.
4. Open the PCB diagram on the computer and light up the short circuit network to see where it is closest and the most likely to be connected to one. Pay special attention to IC internal short circuits.
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, since all the solder joints are covered by the chip and cannot be seen, and it is a multi-layer circuit board (4 layers or more), it is better to divide the power of each chip in the design process, using magnetic beads or 0 European resistance connection, so that when the power and ground short circuit, disconnect the magnetic bead detection, it is easy to locate a chip. Because BGA's welding is difficult, if it is not automatic welding of the machine, a little care will be taken to short circuit the adjacent power supply and the ground two solder balls.
The inspection of PCB circuit boards cannot be ignored. Each step must be well examined. Care must be taken to ensure that no suspicious points can be missed in the production process. This will reduce the rate of rework and product rejection, and avoid unnecessary loss.