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34 SMT007 MAGAZINE I NOVEMBER 2020 mix, low-to-medium volume manufacturing with a separate subset of challenges. Lot sizes may range from 1–100 PCBs, so there is a sense of urgency to quickly dial in the manufacturing process and eliminate defects. Furthermore, products manufactured in the U.S. and in Europe are typically higher dollar value, which makes rework an extremely costly endeavor. Considering the fact that the cost of rework increases dramatically as the product advances through the manufacturing line, it becomes clear that high-mix, low-to-medium volume manufacturing is the ideal environment for inspection at each phase of production. For example, let's say we have an SPI system that detects an insufficient solder defect. Since the defect has been flagged post-solder deposition, we can either add solder to the pad or simply clean the PCB off and start over again. This is a relatively low-cost solution. A post-placement AOI system may perhaps flag a polarity issue with a certain device. Under these circumstances, the operator can simply use a tweezer to rotate the device and resolve the issue. This is also a fairly low-cost solu- tion. Any defects that are caught by the post- reflow AOI, however, will most likely require rework, which may either damage the com- ponent or the PCB. The bottom line is that it simply makes sense to catch the defect before reflow to avoid costly rework. Johnson: Smart factory implementation helps relieve the pressures faced by large-volume production facilities because they can keep the line running, teach it to self-adjust to main- tain process windows as much as possible, and keep product flowing. But those same features also work well for a higher-mix, lower-volume, more technical line by providing more accu- racy in the retooling process during the setup for the next job. D'Amico: Exactly. In Asia, you're talking about high-volume applications and a very low mix- ture of products. Once the line is set up, it may produce tens of thousands of PCBs or more. In this environment, it is very important to monitor each phase of the production line in real-time so as to maintain maximum quality and efficiency. When dealing with high-mix, low-to-medium manufacturing, it becomes even more important to have the proper setup parameters at the inception of production as there is little time to dial in the line for maxi- mum quality and efficiency. Johnson: What's the key to making this all work? D'Amico: There is really no substitute for a good process engineer as they have the expe- rience and know-how to make a production line "sing." In setting up the screen printer, a good engineer may recognize that a step-down stencil may require a certain squeegee speed and pressure for optimal solder deposition. He or she may also know how to tune the pick- and-place machine for optimal performance as well. For example, there may be certain devices which require a bit more pressure or dwell time during placement. The same is true for the optimal reflow profile as well. The key here is that this requires a level of expertise as a result of having spent a lot of time working with a given production line and knowing the nuances of each machine. The whole purpose of having machine-to- machine connectivity and communication is to collect and analyze process data and provide optimal parameters for each machine within the line, thereby removing some of the "art" in the manufacturing process. Furthermore, a complete Industry 4.0 solution will monitor each phase of the production line in real-time so as to maintain maximum quality and effi- ciency throughout the manufacturing process. Johnson: That's a great point that it's a little bit more science and a little bit less art. D'Amico: Exactly. Johnson: Great. Brian, thank you for the time. D'Amico: My pleasure Nolan. Thank you for the opportunity! SMT007

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