This method is connected to each detection point on the circuit board by a probe with a spring. The spring gives each probe a 100-200g pressure to ensure that each detection point is in good contact, and such probes are arranged together and are called "needle beds ". Under the control of the detection software, the detection point and the detection signal can be programmed, figure 14-3 is a typical needle-bed tester structure, the detector can be informed of all the test points of the information. In fact, only the probes of the test points that need to be tested are installed. Although the needle bed test method may be used to detect both sides of the circuit board at the same time, when designing the circuit board, it is still necessary to make all the detection points on the weld surface of the circuit board. Needle Bed tester equipment is expensive and difficult to repair.
Needles Select different arranged probes according to their specific application. A basic universal raster processor consists of a drilled board with a center spacing of 100, 75, or 50mil on the pins. The pin acts as a probe and uses an electrical connector or node on the circuit board for Direct mechanical connection. If the pads on the circuit board match the test raster, the polyvinyl vinegar film that is punched according to the specification is placed between the raster and the circuit board to facilitate the design of specific probes. Continuity detection is achieved by accessing the end point of the grid, which has been defined as the X-y coordinates of the pads. Since each network on the circuit board is tested for continuity. In this way, an independent test is complete. However, the proximity of the probe limits the effectiveness of the needle-bed test method.