1. Visual inspection method
This is the most basic detection method. It directly observes the appearance of the PCB Circuit Board with the naked eye to find possible open circuit and short circuit problems. For open circuit faults, you can check whether the circuit is broken, incompletely etched, or the solder joints are detached. For example, on some hand-soldered circuit boards, there may be too little solder due to poor welding technology, which interrupts the circuit connection. For short circuit faults, pay attention to whether there is a tin bridge, that is, too much solder between adjacent circuits, connecting circuits that should not be connected. At the same time, it is also necessary to check whether the component pins are connected or the package is damaged, which may cause short circuits. Although visual inspection is simple, some minor faults hidden under the components or in the inner layer may not be found.
2. Multimeter detection method
Multimeter is a common tool for detecting electrical faults in PCB Circuit Board. When detecting open circuit faults, set the multimeter to the resistance range and measure the resistance at both ends of the suspected open circuit. If the resistance value is infinite, it indicates that the circuit has an open circuit problem. For example, when testing a power line, if the multimeter shows that the resistance is extremely large, there may be a break in the line or the connecting component is damaged. For short-circuit faults, the beeping range of the multimeter can be used. When a beep is emitted between two points and the resistance is close to zero, it means that there is a short circuit between the two points. When testing complex circuit boards, it is necessary to check each branch and node one by one against the circuit diagram. Although this method is accurate, it is time-consuming, especially for circuit boards with a large number of components and circuits.
3. Automatic Optical Inspection (AOI)
The AOI system uses optical imaging technology to detect PCB Circuit Board. It uses a camera to capture an image of the circuit board and then compares and analyzes it with a pre-set standard image. For open circuit faults, AOI can detect missing or discontinuous parts of the line, and its accuracy can reach very small lines. In terms of short circuit detection, AOI can identify whether there is conduction between lines that should not be connected. The advantages of AOI are fast detection speed and high accuracy. It can detect many minor faults that are difficult to detect with the naked eye, but the equipment cost is high, and there may be misjudgments for some special fault types.
4. Flying Probe Test
Flying probe test is a high-precision electrical test method for PCB Circuit Board. It uses movable test probes to contact the test points on the circuit board. When detecting an open circuit, the flying probe test system inputs a signal to one end and then detects whether the signal is received at the other end. If not, it means there is an open circuit. For short circuits, the flying probe can measure the insulation resistance of different networks. When the resistance value is found to be too low, it is judged as a short circuit. Flying probe test is highly flexible and can test circuit boards of different types and sizes. However, the test speed is relatively slow and is suitable for small-batch, high-complexity circuit board detection.
