Dongguan QiMao Electronics Co., Ltd.

Needle bed method

This method consists of spring-loaded probes connected to each detection point on the board. The springs apply 100 - 200g of pressure to each probe to ensure good contact at each test point, and such probes are called a "bed of needles". Under the control of the testing software, the testing points and testing signals can be programmed, and the inspector can obtain the information of all testing points. Only the probes for the test points that need to be tested are actually installed. Although it is possible to test on both sides of the board using the bed of needles method, when designing the board, all test points should be on the solder side of the board. Bed of needles tester equipment is expensive and difficult to maintain. The needles are selected in different arrangements of probes according to their specific application.

A basic general-purpose raster processor consists of a drilled board with pins 100, 75, or 50 mil center-to-center. The pins function as probes and make direct mechanical connections using electrical connectors or nodes on the circuit board. If the pads on the board mate with the test grid, a polyester film perforated to specification is placed between the grid and the board to facilitate 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 every net on the board is checked for continuity. In this way, an independent test is completed. However, the proximity of the probes limits the performance of the bed of needles test.

Observation

The circuit board is small in size and complex in structure, so the observation of the circuit board must also use a professional observation instrument. Generally, we use a portable video microscope to observe the structure of the circuit board. Through the video microscope camera, the microscopic structure of the circuit board can be clearly seen from the microscope. In this way, it is easier for us to design and test the circuit board. The portable video microscopes currently used in the factory, and the portable video microscopes MSA200 and VT101, are more convenient than traditional microscopes because they can realize "observation at any time, detection at any time, and discussions with multiple people"!