With the rapid development of PCB industry, the testing equipment is constantly updated, and the market demand for the stability and efficiency of testing equipment is getting higher and higher. In order to make the test equipment more stable, people play an important role in ensuring the stability, reliability and efficiency of the test equipment. In the process of testing, the phenomenon of false open circuit will inevitably occur, especially when there are more than 10 false open circuits. Operators and technicians should pay attention to it, and should analyze and solve it from the aspects of equipment, process data and printed circuit board products. In the practical work of equipment maintenance and related equipment process feedback analysis, this paper takes the Italian Seica series PCB flying needle test as an example, and summarizes the reason analysis and solution strategy for the phenomenon of false opening of PCB flying needle test equipment. One of the easiest ways to judge whether the equipment is working properly due to instability of the equipment is to use the old document data and the corresponding qualified PCB board (removal of surface oxides, etc.) for testing, and if the open circuit still occurs, it should belong to the equipment fault, otherwise it should belong to the process data or to be tested and printed. The problem of making circuit boards is checked and analyzed in the following ways when the device asks questions. 1. Software overhaul first, use the equipment overhaul (also called self-inspection) software to run according to the prompt to see if there are damaged parts or errors: if there are damaged parts or errors, the corresponding parts should be replaced and corrected according to the error prompt. Secondly, DMC software is used to check whether the feedback system of each axis is working properly. The correct operation steps are: minimizing the test system opening the DMC (TEST interface of DMC) under the Start DMC program or on the desktop pressing the stop switch manually moving the axes, observing the digital changes and ingenuity of the grating feedback system of each axis. Sensitivity, whether the number varies within a specified range; TESTXY. DMC and TESTZ. DMC RUN are then activated to see if the axes return to zero (the corresponding axes read'0'). 2. Hardware faults are more likely to occur in all faults, because the quality of the test system is closely related to the working environment (temperature, humidity, etc.), working time, maintenance and other factors. According to my own summary, hardware faults are Z-axis linear motor, grating ruler, grating feedback data. Line adapter and L type fly (Probe). (1) Z-axis linear motor: because of long-term, high-frequency operation of the linear motor, easy to make the motor moving parts blackened and produce black dirt, resulting in up and down inflexibility, motor load increased and so on. Therefore, the linear motor should be removed regularly (about 6 months) with anhydrous alcohol cleaning, removal and cleaning must be careful when the guide ball sliding. (2) grating ruler: grating is the core component of all high-precision equipment positioning, the quality of grating is directly related to the accuracy and stability of the equipment. But most of the gratings are caused by bad environment or poor gas source, workshop environment may make the grating ruler surface area too much dust, dust directly affects the feedback signal, resulting in more open circuit phenomenon. In order to remove the dust on the grating ruler should be cleaned with absolute ethanol, pay attention to the use of yarn gloves (dipped in a little anhydrous alcohol) one-way gentle cleaning, can not be scrubbed back and forth and too much force (to prevent scratching grating); at the same time, require the air source to be dried, filtered oil, filtered water into the equipment, otherwise it will affect the equipment. Its service life and measurement accuracy. (3) grating data feedback line adapter: PCB flying needle testing equipment moves faster, once the equipment is in working condition, the whole opportunity has a strong jitter. Therefore, the raster data line connector may be due to inertia, after a period of time in use between the socket and bad contact, in order to avoid this situation, the plugs should be checked before starting the machine every day and then turn on. (4) L-probe: the quality of the needle is also one of the important factors causing open circuit, the needle mainly for the passivation of the needle tip, needle and plug contact is not good and regular needle calibration (at least once a week). When the needle passivation must be replaced needle, after needle change remember to its use of zero, always check whether the needle and needle between loose, to ensure that the needle automatically corrected at least once a week. Second, the process data conversion new file process data in the first generation error, which is also the cause of open circuit, many process personnel in the CAM data conversion, the network diagram file generated errors, most of the cases belong to each layer, surface hole or pad properties are inconsistent. Therefore, once it occurs, it requires the process personnel to review the data files repeatedly. 3. PCB product problems if excluding test equipment and process data, another situation should belong to the PCB product itself problems, mainly manifested in warping, soldering resistance, character is not standardized. (1) Warpage: Some production planners in order to rush, often omit the hot air leveling this process, directly sent to the final inspection, if not through thermal leveling, product warpage greater than the test equipment allowed warpage range. Therefore, the thermal leveling process can not be less, but also requires the test personnel to add warpage measurement before testing. (2) Resistance welding: Often the products with severe open circuit will be unsatisfactory because part of the through hole is blocked by the resistance welding layer, and the test results should be avoided as far as possible in the test of switching hole (or to ensure that the through hole is correct). (3) character: a lot of PCB manufacturers will print the characters first and then measure the electricity, as long as the position of the character is printed.

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