AOI testing machine, also known as AOI optical automatic testing equipment, has become an important testing tool and process quality control tool for electronic manufacturing industry to ensure product quality. Therefore, how to select and use AOI optical automatic testing equipment suitable for their own requirements from a large number of AOI brands has become a very concerned issue for electronic manufacturing workers.
Principle of AOI testing machine: when automatic testing, AOI testing machine automatically scans PCBA products through high-definition CCD camera, collects images, compares the tested testing points with the qualified parameters in the database, checks the defects on the target products through image processing, and displays / marks the defects through the display or automatic signs for repair and SMT engineering by maintenance personnel Personnel to improve the process.
The general process of AOI testing equipment is the same, mostly through the graphic recognition method. The standard digital image stored in the AOI system is compared with the actual detected image to obtain the detection results.
For example, when a solder joint is detected, a standard digital image is established according to a good solder joint, and compared with the measured image, whether the detection result is passed or not depends on the standard image, resolution and the detection program used. Various algorithms will be used in graphic recognition, such as finding the proportion of black to white, color, synthesis, average, sum, difference, plane and corner.
There are two kinds of equipment for AOI light irradiation: white light and color light. White light is 256 levels of gray. Color is red light, green light, blue light. Light irradiates to the surface of solder / components. After that, light is reflected into the lens to produce a three-dimensional display of two-dimensional image to reflect the height and color difference of solder joints / components. People see and recognize objects through the amount of light reflected back to judge, the amount of reflection is mostly bright, the amount of reflection is less dark. The principle of AOI is the same as that of human judgment.
AOI has single lens and multiple lenses in terms of lens number, which is just a choice of technical scheme implementation. It is difficult to say that that way is good, because single lens can get good detection image through different angles of multiple light sources. Especially for the rough surface of lead-free welding, it will produce different shapes of solder joints, easy to form bubbles, and prone to one end of the part is up, the new AOI equipment has also been updated with adaptive hardware and algorithm.
Location of AOI detection equipment: