PCB Tech - How to check the short circuit of the PCB circuit board

During the manufacturing process of the PCB circuit board, how do we check the short circuit of the PCB circuit board? One of the shortcomings that is simply presented is the short circuit. In order to prevent the short circuit of the circuit board from affecting the performance, it is necessary to check the PCB circuit board and deal with it in time. So how to check the short circuit of the PCB circuit board? Let’s find out below.

1. If it is manual soldering, develop a good habit. First, check the PCB circuit board visually before soldering, and use a multimeter to check whether the key circuits (especially the power supply and ground) are short-circuited; secondly, solder one chip at a time Just use a multimeter to test whether the power supply and ground are short-circuited; in addition, do not throw the soldering iron randomly when soldering. If you throw the solder onto the solder feet of the chip (especially surface mount components), it is not easy to find out.

2. Open the PCB circuit board diagram on the computer, light up the short-circuited network, and see which place is closest to it. It is the easiest to connect to one. Pay special attention to the short circuit inside the IC.

3. A short circuit is found. Take a board to cut the line (especially suitable for single/double-layer boards). After the line is cut, each part of the functional block is energized, and part of it is wiped out.

4. Use the PCB circuit board of the short circuit locating analyzer

5. If there is a BGA chip, because all the solder joints are hidden by the chip and are invisible, and it is a multilayer board (4 layers or more), the power supply of each chip is divided during the design and connected with magnetic beads or 0 ohm resistors. In this way, when the power supply and the ground are short-circuited, the magnetic bead detection is disconnected, and it is easy to locate a certain chip. Because the welding of BGA is difficult, if it is not automatic welding by the machine, a little carelessness will short-circuit the adjacent power supply and the ground two solder balls.

6. Be careful when welding small-scale surface-mount capacitors, especially 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 the capacitor itself is short-circuited, so it is a good way to check the PCB circuit board capacitance before soldering.