检测系统，往往更多的用于在实验室进行对元器件的失效分析检测。 At present, X-Ray inspection used in the electronics industry, often called offline X-ray tube inspection systems, is often used more for failure analysis and detection of components in the laboratory. It is not that offline X-ray systems are not a good tool for fault analysis, especially those with advanced high-end detection systems with CT functions. From the perspective of investigation and feedback and circuit test failures, they have a place. However, we live in a world of increased product yields, "real-time" process control and cost savings, so maybe offline X-rays have a new role and function.
The most modern offline X-ray inspection system integrates "real-time" imaging capabilities, "real-time" image improvement, fast CT imaging, and the most useful analysis tool-Inclined CT. This technique, also called local CT, can very quickly reconstruct many horizontal slices into one substrate. So it's a CT, but you don't need to break the substrate to make a sample, unless you have a more expensive use that requires a traditional CT. Tilt CT can quickly and accurately detect any solder joint interface, so it is very suitable for BGA hole detection and QFN hole detection and coplanarity detection. With the purchase of a software package, it can even reconstruct these images into three-dimensional images. Provide a good visualization of components, vias, etc.
This technique will become more important as the BOT (Bottom Terminated Components) components are placed on the bottom of the component. One study showed that by 2017, more than 40% of devices will be BTC. I've seen 01005 BTC in metric, which is a good layout design, but assembly does face challenges. High-end offline X-ray systems are capable of processing images of these components. In fact, this is not a matter of final magnification and pixel size, but of image processing resolution, speed, and repeatability.
The biggest problem is repeatability, because each X-ray system does not actually measure holes, it measures the gray levels of different levels in the image, which can be improved by adjusting the system settings. X-ray tube
temperature, target quality, and software monitoring all have an impact on repeatability. If customers have stringent hole detection requirements, a good system must have both stability and repeatability to ensure accurate and consistent results.
As I mentioned earlier, by adjusting the settings, you can get very different results. Therefore, the system needs to be set up properly to give consistent results. Now that thermal pads are common on QFNs, these measurements become even more critical, void = air = almost no heat transfer. This causes overheating and then premature component failure.
An oblique CT slice of the QFN solder joint interface is given. This system measures more than 29% of the voids in the thermal pad. Based on the preset void limit, this is a failed component because its thermal efficiency will be reduced by nearly 30%. This shows that X-rays with tilted CT are becoming more and more a must-have technology, which is the only non-destructive way to detect voids in assembled components.
If your X-ray system is mainly used for the above-mentioned offline fault analysis, then you have solved a non-destructive testing analysis method currently required by the laboratory, but this method will not help you monitor production in an effective way. In other words, before you discover a process or quality problem, you may have manufactured many components that are likely to be bad, wasting financial and material resources.
Therefore, a solution with a lower cost and faster response to process problems and a solution with higher yield is to let X-rays enter the production line more!