AOI full name automatic optical detection is a detection technology based on optical principle using machine vision instead of artificial eye inspection. AOI equipment is mainly used in industrial testing of PCB, FPD, semiconductor, photovoltaic, automotive electronics and other industries.
Basic principle of AOI detection
AOI technology is the process of artificial detection using machine vision as a whole, and its basic principle is similar to manual detection.
AOI by the artificial light instead of natural light, the optical lens to replace human lens, CCD, CMOS and other components instead of retinal image acquisition, image processing algorithms after standard image analysis after and before the acquisition of the comparison, the analysis process by the analysis method of image contrast + mode instead of the human brain results.
The AOI system is mainly composed of image acquisition system, motion control system, image processing system and data processing system. The hardware device is mainly divided into six parts: light source, camera, computer host, screw rod, motor and body. The light source is an important factor in determining the detection ability, and the industrial camera is the main bottleneck to realize the complete localization. In addition to the hardware, a matching algorithm is needed.
AOI Testing Market
Related research institutions are expected to Cell segment detection equipment space is 10-15 times Module; in the OLED field, 1.5-2 times a OLED line for the AOI device is about LCD line, the average price increase of 20-30% detection equipment.
The display panel and the touch screen production line inspector accounting for the overall production line staff 30-40%, is the future of the main field of production automation upgrade.
An online AOI device can replace the workload of 4-5 people, open the machine for 25 days a month and start for 23 hours, basically without interruption. In the SMT field, the AOI unit price is only 10-20 million, which is equivalent to the annual salary of 1-1.5 skilled workers.
The upstream of AOI mainly includes optical components suppliers, mechanical components and sports system providers. Mechanical equipment and other technologies have high versatility, which can be provided by general manufacturers.
There are different requirements for precision of optical components according to equipment requirements. But in addition to the high requirement of high-end equipment to industrial cameras, buyers can choose more overall, and upstream supply will not constitute constraints for device manufacturers.
The downstream mainly includes PCB, FPD, semiconductor and other industries.
AOI equipment in SMT production line in the position usually after printing, patch (furnace) and after reflow (oven), which is important) after printing position detection, data show that 60%-70% defects in the printing process, if we can discover in printing paste defects, just wash the plate that is printed again to regain the good product, the lowest maintenance cost;
Position may choose whether the patch is placed, if can detect the defects during reflow before the maintenance cost is low, the reflow soldering is not only high cost, is also likely to lead the entire PCB scrap, so the future will be to detect patch will also pay more attention to;
After reflow as the final detection products out before the position is the most popular AOI, can effectively improve the yield rate of the product. According to the sales data in 2000, 20.8% of AOI was applied to print, 21.3% used for patch, and 57.9% used for reflow soldering. It also basically confirmed that the distribution is a mainstream program approved by the market.
In addition to SMT testing, AOI equipment in the PCB industry can also be used for DIP detection, appearance testing, and so on. The detection of DIP and SMT is similar, the key position is placed after the detection of wave soldering; visual inspection for circuit board including HDI, flexible board.
For the PCB industry, the demand for AOI devices is on the rise in terms of processes, costs, and customer needs.
1. From the point of view of technology and technology, the miniaturization of PCB can not meet the requirements of the artificial eye inspection, and it is a big trend to use the machine detection.
2, from the perspective of production cost, product ASP is decreasing and labor cost is rising. Optimizing production process to control cost is the way for manufacturers to survive in fierce competition. It is necessary to introduce automatic inspection equipment.
3, the demand from the customer's point of view, the complexity of the various end products continue to improve, the stability requirements are also increasing, AOI can effectively detect the defects of Alice feet, weld, enhance the reliability of products, the introduction of AOI equipment is important for manufacturers to customer orders.
Common detection device category in FPD domain
Panel manufacturing can be divided into Array, Cell, and Module three processes. All three processes require the introduction of AOI testing equipment, and the test items required by each process are different, and the equipment needs to be specifically developed according to the application scenario.
The objects that can be applied automatically include substrate glass, CF, CG, LCM and so on, of which the market space of Array and Cell process is more than ten times as much as Module. There are certain differences between different processes for the technical requirements of the equipment. Every manufacturer offering panel inspection equipment has different market share in the three processes.
At present, the market of Array process detection equipment is mainly monopolized by Japanese enterprises, and Cell process is occupied by enterprises in Japan, Korea and Taiwan. China's test equipment manufacturers are trying to step into Array and Cell process market relying on Module technology accumulation.
OLED for the AOI equipment demand is higher than the ordinary LCD line LCD and OLED put forward different requirements for AOI devices, because the light-emitting principle is different, OLED without filter, so relative to the LCD does not require the CF AOI testing equipment, but OLED needs Mura special detecting equipment. The Mura of LCD occurs mainly in CF, and the Mura defects of various kinds of Mura are more serious because of the different process of OLED.
There is usually a subjective assessment for the defects of Mura, AOI equipment on the one hand can contribute to the detection of defects, it is important for the luminance signal detected by AOI, according to the detected Mura optical compensation to eliminate defects, namely Demura technology.
There are two main difficulties in this technology.
1. How to identify all kinds of Mura defects quickly and accurately;
2, how to improve the compensation speed as far as possible to reduce the loss of capacity.
At present, OLED Samsung and LG Demura technology is relatively advanced, more difficult because the OLED production yield is low, the technology can effectively improve the OLED yield rate, with the popularity of OLED and the yield of the increasingly high demand, with the function of Demura AOI devices will be a welcome.
The data shows that the AOI set required for a OLED line is about 3 times as much as that of LCD.
AOI equipment for glass, BM AOI equipment for detecting macro defects, and Film AOI, etc. According to OFweek prediction, the demand for AOI equipment in touch screen industry is about 1600 sets / sets in the CG field, 4000 sets / modules in the TP field, 2000 sets, modules and whole line, and the total industry will exceed 8000 sets / sets.
AOI devices are widely used in semiconductor industry for wafer appearance inspection, bumping detection, IC packaging detection and marking or logo detection. They are widely applied in semiconductor manufacturing.
In recent years, with the development of IC packaging technology gradually from the plane to the 3D, such as 3D, greatly enhance the package Fan-out wafer level packaging, SoC and SiP technology for automatic detection equipment needs, the future may also need X-ray detection AXI devices using X into the light.