PCB Tech - PCB circuit board short circuit inspection and prevention

PCB circuit board short circuit inspection and prevention
One of the most common problems encountered in the maintenance of electronic products is short circuit. The short circuit causes considerable harm to PCBA, ranging from burning components to scrapping. We can only try to avoid short circuits, we must grasp every step of the production, and do not miss every suspicious point during inspection.

1. If it is manual soldering, develop a good habit. First, check the PCB board visually before soldering, and use a multimeter to check whether the key circuits (especially the power supply and ground) are short-circuited; secondly, each time a chip is soldered Use a multimeter to check 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 will not be easy to find.

2. 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.

3. A short circuit is found. Take a board to cut the line (especially suitable for single/double-layer boards), and power on each part of the functional block separately after cutting the line, and remove part of it.

4. Use short-circuit location analyzers, such as: Singapore PROTEQ CB2000 short-circuit tracker, Hong Kong Lingzhi Technology QT50 short-circuit tracker, British POLAR ToneOhm950 multi-layer board short-circuit detector, etc.

5. Be careful when soldering small-size surface-mount capacitors, especially power supply filter capacitors (103 or 104), which may easily cause a short circuit between the power supply and the ground. Of course, sometimes with bad luck, the capacitor itself is short-circuited, so the best way is to test the capacitor before welding.

6. If there is a BGA chip, since all the solder joints are covered by the chip and are invisible, and it is a multilayer 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.
At present, the country has higher and higher requirements for environmental protection and greater efforts in link governance. This is a challenge but also an opportunity for PCB factories. If PCB factories are determined to solve the problem of environmental pollution, then FPC flexible circuit board products can be at the forefront of the market, and PCB factories can get opportunities for further development.
The Internet era has broken the traditional marketing model, and a large number of resources have been gathered together to the greatest extent through the Internet, which has also accelerated the development speed of FPC flexible circuit boards, and then as the development speed accelerates, environmental problems will continue to appear in PCB factories. In front of him. However, with the development of the Internet, environmental protection and environmental informatization have also been developed by leaps and bounds. Environmental information data centers and green electronic procurement are gradually being applied to the actual production and operation fields. From this point of view, the environmental protection problems of PCB factories can be solved from the following two points.