PCB Tech - PCB circuit board short circuit inspection method

1. Open the PCB design drawing on the computer, light up the short-circuit network, and see where it is closest and most easily connected. Pay special attention to the short circuit inside the IC.

2. In case of manual welding, develop good habits:

1. Before welding, visually check the PCB board, and use a multimeter to check whether the key circuits (especially the power supply and ground) are short circuited;

2. After each chip is welded, use a multimeter to measure whether the power supply and ground are short circuited;

3. Don't throw the soldering iron randomly during welding. If the soldering tin is thrown on the welding foot of the chip (especially the surface pasted components), it is not easy to find it.

3. A short circuit is found. Take a board to cut the line (especially suitable for single / double-layer boards). After cutting, power on each part of the functional blocks respectively and eliminate them step by step.

4. Make use of short-circuit positioning analyzer.

5. If there is a BGA chip, because all solder joints are covered by the chip and cannot be seen, and it is a multilayer board (more than 4 layers), it is best to separate the power supply of each chip and connect it with magnetic beads or 0 ohm resistance in the design. In this way, when there is a short circuit between the power supply and the ground, disconnect the magnetic beads for detection, and it is easy to locate a chip. Due to the difficulty of BGA welding, if the machine does not weld automatically, the adjacent power supply and two welding balls to the ground will be short circuited if you pay little attention.

6. Be careful when welding small surface mount capacitors, especially the power filter capacitors (103 or 104), which are in large quantity, it is easy to cause short circuit between power supply and ground. Of course, sometimes with bad luck, the capacitor itself will be short circuited, so the best way is to test the capacitor before welding.