The flying needle tester does not depend on the insert pattern installed on a fixture or bracket. Based on this system, two or more probes are installed on the small magnetic head that can be moved freely on the X-Y plane, and the test point is directly controlled by Cadi Gerber data. The dual probe can move within the range of 4mil. The probe can move independently and does not really limit their degree of approaching each other. Tester with two back -and -forth arm -shaped objects is based on the measurement of capacitors. Press the circuit board on the insulating layer on a metal plate as another metal board of the capacitor. If there is a short circuit between the lines, the capacitor will be larger than a certain point. If there is a disconnection, the capacitor will become smaller.

Test speed is an important criterion for choosing a tester. The needle bed tester can accurately test thousands of test points at one time, and the flying needle tester can only test two or four test points at a time. In addition, when the needle bed tester is performed by single -sided testing, it may only cost 20-305, which depends on the complexity of the board, and the flying needle tester requires IH or more time to complete the same evaluation. SHIPLEY (1991) explained that even if the manufacturer of high -yield printed circuit boards believes that the mobile flying needle testing technology is slow, this method is still a good choice for manufacturers of lower -yield complex circuit boards.

For bare board tests, there are special test instruments (Lea, 0). A more optimized method is to use a universal instrument. Although such instruments are initially more expensive than dedicated instruments, its initial high costs will be offset by the reduction of individual configuration costs. For general grids, the standard grid of the board and surface paste device with a pins device is 2.5mm. At this time, the test pad should be greater than or equal to 1.3mm. For IMM's grid, the test pad is designed to be designed greater than 0.7mm. If the grid is small, the test needle is small and crispy, and it is easy to damage. Therefore, it is best to choose a grid greater than 2.5mm. CRUM (1994B) states that the general tester (standard grid tester) and flying needle tester can make the detection of high -density circuit boards accurate and economical. Another method he suggested is to use conductive rubber tester, which can be used to detect points that deviate from grid. However, the height of the pads that use the calibration of the hot air will be different, and there will be a connection that hinders the test point.