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June 2017 • SMT Magazine 17 3D: TOWARDS BETTER INSPECTION CAPABILITY Making Smart Decisions The bottom line is that it's all about making smart deci- sions. "We are completely on the same page," said Peallat. "Vi TECHNOLOGY has devel- oped a direct communication between the SPI and the AOI. In fact, we trace boards with the serial number. When the SPI detects a defect, of course the board is tossed. The key is to get the right tolerances. One approach is to use warn- ings to define measurements close to the tolerances but still good. In that case, the board goes through the rest of the steps, and when the boards arrive at the AOI or the post reflow 3D equipment, then there's special attention to this warning. In fact, even if there is no de- fect on the 3D AOI, our system warns the oper- ators: 'Warning at the SPI.' Let's say your lim- it was 70% and the volume was at 72%, it was good at the SPI, of course. But we raised this to the attention of the operator and we provide, at the same time, the 3D AOI picture of that joint. In fact, the operator can analyze it and validate it. Then, all this information can be fed back to the SPI to tighten the tolerances. This live process, live information, is a way to improve directly and not through a cloud data analysis, which is most of the time after the fact and re- quires a lot of energy and a lot of analysis. This is clearly the direction Vi TECHNOLOGY is go- ing today. I was talking about this installation in Europe with an EMS company, but we believe that this short loop with clear, effective, action- able information will help our user to improve their process quickly. Based on what Peallat said, it sounds like the most important part of test and inspection to- day is around data management. "Yes, but not only that, you have pictures," he said. "You have gigabytes of data that you can analyze, but when you are effectively—and I think Mark mentioned that earlier—when you're effectively working on the line to de- cide the quality of your product, there is no bet- ter thing than a good picture of what the ma- chine has seen. Combining 3D pictures of solder paste and 3D pictures of post reflow analysis is the best information you can give to your operator to decide the quality of your product." On ROI When somebody's looking at making this capital investment, what should they take into con- sideration beyond perhaps the norms, like their return on in- vestment? "I would say that the most important, of course, is the qual- ity of the inspection," said Peal- lat. "But what does the quality of inspection mean? It's the capabilities of the tools to mea- sure key variables accurately and repeatably, but also the stability through the use of the equip- ment. Some technologies are very easy to im- plement and some competitors claim they just need one board to program the machine; but in the long run, this one is not stable and re- quest a lot of maintenance in the line due to components variation. So, stability and repeat- ability are very important. For solder paste, it is volume and accuracy. For years, we had people talking about repeatability, repeatability, repeat- ability, but you can be very repeatable and mea- sure something the wrong way. Volume and accuracy, especially when the components are getting smaller and smaller, are very, very im- portant. We see that is key for solder paste, and it's also key for AOI. When you talk about the criteria to select AOI equipment, I was mention- ing the ability to have a wide range of 3D recon- struction, from 0 to 20mm without losing your accuracy or your speed. A lot of vendors are do- ing 3D only up to 3mm, for example, in order to be able to run through a good cycle time and with good accuracy." There are a lot of variables as far as return on investment is concerned, according to Peal- lat, and that it is never easy to define with- in a quick answer. "We have developed some tools to calculate that, but it depends on your whole test strategy, of course, your defects spec- trum, and what you use on the backend to test Jean-Marc Peallat