Basic principles of detection and control technology
1. Basic principles of real-time detection and control
The solder joint shape and the solder joint quality have a corresponding relationship. Through the observation and analysis of the solder joint shape, the quality of the solder joint and the solder joint assembly failure can be distinguished. The real-time detection and control method of the SMT solder joint based on the virtual forming of the solder joint is based on this principle. Design, its method is similar to automatic visual inspection. It uses the optical system and image processing measures to measure the shape of the formed solder joints online, and the computer compares the actual shape of the solder joints obtained with the reasonable shape formed by the virtual solder joint forming technology stocked by the analysis and evaluation expert system to quickly identify For the faulty solder joints that exceed the allowable range, the fault type and cause of the fault are automatically analyzed and evaluated, and then real-time control information for optimization and adjustment of process parameters is formed, real-time feedback control of solder joint quality, and analysis and evaluation information are recorded and statistically processed . The basic principle that reflects this idea is that the quality inspection and control method of solder joints based on virtual forming of solder joint morphology is better than automatic visual inspection, ultrasonic inspection, infrared laser inspection and other methods. There are three points: First, its comparison standard is based on theory. Reasonable form, which is scientific and deterministic; second, a computer can be used to build a standard library of solder joint morphology before actual production through technologies such as virtual solder joint formation, which is strong in advance and does not need to rely on actual system tests; third is Not only can it quickly detect the appearance quality failures of solder joints, but also can quickly analyze and identify most of the internal quality problems of solder joints based on the theory of solder joint morphology. Therefore, it has the characteristics of high practical value and suitable for real-time detection in the assembly process of SMT products.
The key technologies to realize the real-time detection of solder joint shape and the process of solder joint quality feedback control include: reasonable solder joint morphology generation and database construction technology, actual solder joint morphology image rapid acquisition and processing technology, solder joint quality analysis and evaluation expert system, etc.
2. The basic principle of fast acquisition and processing of solder joint images
Whether the image information of the actual solder joints can be efficiently acquired and processed, and the solder joint quality information can be extracted reliably, comprehensively and in a timely manner is an important factor that affects the realization and operating efficiency of the SMT solder joint quality real-time detection and feedback control system . In the SMT solder joint quality real-time detection and feedback control system, the rapid acquisition and processing technology of the actual solder joint shape image has relatively high requirements in terms of speed, accuracy, complexity and uncertainty, and generally requires the help of computer vision information Processing technology to complete.
The basic principle of SMT solder joint image quick acquisition and processing process using computer vision information processing technology. The idea is to apply video capture and digital image processing technology to collect and process SMT solder joint images, and extract relevant morphological parameters or contour features that can reflect the quality of the solder joint and can be compared with the ideal solder joint morphology. Subsequent comparison and analysis create basic conditions.