Release time:2019-12-12 Browse:1843
When the AOI optical detector automatically detects it, the AOI machine automatically scans the PCB through the camera, collects the images, and compares the tested solder joints to the qualified parameters in the database. After image processing, defects on the PCB will be detected and defects will be automatically marked on the display. Defects are displayed / marked for maintenance personnel to perform repairs.
What is AOI test technology?
AOI automatic inspection technology is an emerging PCB quality inspection technology, which has only appeared in recent years, but has developed rapidly. Currently, many manufacturers have introduced AOI test equipment.
First; @ # and implementation goals: There are two main goals for implementing AOI:
(1) Final quality. Monitor the final state of the product as it exits the production line. This goal is preferred when production issues are clear, product mix is high, and quantity and speed are key factors. AOI inspections are usually located at the end of the production line. From here, the device can generate a wide range of process control information.
(2) Process tracking. Use inspection equipment to monitor the production process. This usually includes detailed defect classification and component placement offset information. When product reliability is important, low-volume, high-volume production, and stable component supply, manufacturers will prioritize this goal. This usually requires placing inspection equipment at multiple locations on the production line, monitoring specific production conditions online, and providing the necessary foundation for adjusting the production process.
There are three inspection positions:
(1) After solder paste printing. If the solder paste printing process meets the requirements, the number of defects found by ICT can be greatly reduced. Typical printing defects include:
A. AOI detected insufficient solder on the pad.
B. AOI detected excessive solder on the pads.
C.AOI detected poor positioning of solder on the pad.
D. AOI detects solder bridges between pads.
In ICT, the likelihood of defects relative to these situations is directly proportional to the severity of the situation. Small amounts of tin rarely cause defects, and severe conditions (such as Wuxi at all) almost always cause defects in ICT. Insufficient solder may be the cause of missing components or broken solder joints. However, when deciding where to place an AOI, you need to recognize that components may be lost for other reasons, which must be part of the inspection plan. Inspection of this location most directly supports process tracking and characterization. The quantitative process control data at this stage includes information on offset printing and solder volume, as well as qualitative information on printed solder.
(2) Before reflow. Inspect components after placing them in solder paste on the board and before sending the PCB to the reflow oven. This is a typical location for inspecting machines, as most defects in solder paste printing and machine placement can be found here. The quantitative process control information generated at this location provides information on the calibration of high-speed chippers and close-pitch component placement equipment. This information can be used to modify component placement or to indicate that the placement machine needs calibration. Checking at this location meets the goals of the process trace.
(3) After reflow. The inspection is performed in the last step of the SMT process. This is currently the most popular choice for AOI, as all assembly errors can be found here. Post-reflow inspection provides a high level of security because it can identify errors caused by solder paste printing, component placement, and reflow processes.