What are the common test methods for PCB circuit board inspection? To

The automatic detection of the circuit board is not only basic, but also necessary. In complex PCB circuit board inspection, what are the common test methods? 1. The needle bed test method is connected to each detection point on the circuit board by a probe with a spring. The spring makes each probe have a pressure of 100-200g to ensure good contact between each detection point. Such probes are arranged together called a 'needle bed'. The needle bed tester is expensive and difficult to repair. According to the specific application of the needle, the probes in different arrangements are selected. 2. Using observation instruments The circuit board is small in size and complex in structure, so the observation of the circuit board must also use professional observation instruments. Generally, we use a portable video microscope to observe, using a video microscope camera, you can clearly see the very intuitive microstructure of the circuit board. In this way, it is easier for us to design and test the circuit board. Many circuit board manufacturers now use portable video microscopes MSA200 and VT101, which can realize 'observation, detection and discussion at any time3. Flying probe test The flying probe tester does not depend on the pin pattern installed on the fixture or bracket. Based on this system, two or more probes are mounted on tiny magnetic heads that can move back and forth on the x-y plane, and the test points are directly controlled by CADI Gerber data. The dual probes can move within a distance of 4 mils from each other. The flying probe tester is based on the measurement of capacitance. The circuit board is pressed tightly and placed on the insulating layer of a metal plate as another metal plate of the capacitor. If there is a short circuit between the lines, the capacitance will become larger; if there is an open circuit, the capacitance will become smaller. The above are the common test methods for PCB circuit board inspection. How much do you master?