Introduction to PCB hole inspection machine
Like most AOI systems, PCB hole testing machine system mainly consists of the following parts: motion control unit, LED lighting unit, image acquisition unit, data processing unit, etc. The motion control unit relates to the transmission belt, PCB mobile platform, stepping motor, servo motor, synchronizing wheel, CIS focusing system and other precision mechanical systems. The main function of LED lighting unit is to provide appropriate lighting for the system to handle the accurate object image position relationship and ensure that the image has sufficient contrast and clarity. The image acquisition unit uses an image sensor to capture the image of the circuit board, and then collects the captured image through the image acquisition card to transfer the image data to the computer system. The data processing unit is used by the computer to perform algorithm analysis on the collected circuit image to determine whether the detected circuit board is qualified.
PCB quality defects are generally divided into drilling defects and in hole defects. Common defects and their causes are as follows: 1. Causes of large and small holes: the drill bit has problems, the cutting edge is excessively worn, the spindle shakes, and chip removal is poor. 2. Reasons for multi holes and few holes: the drilling procedure is defective; 5 3. The hole is blocked (there is debris in the hole) because the vacuum degree of the NC drilling machine is not enough; Improper setting of bit speed and down speed; There is a problem with the upper and lower base plates and circuit board substrate. Generally, the upper and lower base plates and circuit board substrate contain too much water, the epoxy resin in the circuit board substrate is not cured enough, or the resin content of the lower base plate is too high. 4. Reasons for burr, roughness and greasy dirt in the hole (adhesion after material dissolution): the drilling parameters are set improperly. The burr and roughness are generally caused by too slow drilling speed and too fast drilling speed, and too many drill bits are not replaced; The greasy dirt is that the speed is too fast and the speed is too slow. 5. Reasons for not drilling through: the machine table is not level; After CIS acquisition and imaging, these defective holes can be detected by comparing the image of the circuit board to be tested with the standard image through image processing.