Teach you to understand the difference between various inspections in PCB boards

The pin bed method is a common PCB board inspection method.probe test system It uses probes with springs attached to each inspection point on the board, and the pressure of the springs ensures that each inspection point makes good contact. These probes are arranged together in what is called a "bed of pins". The test points and tests can be programmed under the control of the test software. Needle bed testers are expensive and difficult to maintain. Needles are arranged in different probes depending on the specific application.

Another basic general-purpose grid processor consists of a drilled board with pins spaced on centers of 100, 75, or 50 mil. the pins act as probes and make direct mechanical connections using electrical connectors or nodes on the circuit board. If the pads on the board are mated to the test grid, a polyvinyl acetate film punched to specification is placed between the grid and the board for design-specific probing. Continuity detection is achieved by accessing the end points of the grid (which have been defined as the x-y coordinates of the pads). Since continuity detection is performed for every network on the board, this completes the detection of a single point.RF probes However, the proximity of the probes limits the efficacy of the bed-of-pins test method.

Observation is a method of looking at the structure of a circuit board. Due to the small size and complex structure of circuit boards, specialized observation instruments are required. Usually, we use a portable video microscope to observe the structure of the board. Through the video microscope camera, the microscopic structure of the circuit board can be clearly seen very intuitively from the microscope. In this way,probe card we can more easily carry out the design and inspection of circuit boards. At present, the factory site used portable video microscope MSA200 and VT101, because they can realize "anytime observation, anytime inspection, multi-person discussion", more convenient than the traditional microscope!

Flying probe test is a test method that does not depend on the pin pattern mounted on the fixture or bracket. Based on this system, two or more probes are mounted on tiny magnetic heads that move in the x-y plane and the test point is directly controlled by CADI Gerber data. The dual probes are able to move within 4 mils of each other. The probes move freely and there is no real limit to how close they can be to each other. The tester with two arms that move back and forth is based on capacitance measurements. A circuit board is placed firmly pressed against an insulating layer on a metal plate that serves as the other metal plate for the capacitor. If there is a short circuit between the lines, the capacitance will be greater than at a definite point. If there is a broken circuit, the capacitance will be smaller.