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SMT-June2019

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36 SMT007 MAGAZINE I JUNE 2019 ware can give a customer an in-spec profile without even running a trial PCB. These two functions alone provide solutions for fast pro- filing for a high-quality product and within the specifications of the factory's requirements, which include faster throughput, lower energy costs, and, of course, difficult and challenging assemblies with a variety of process windows between components and solder paste." Phil Kazmierowicz explained the details. "Once the specification was defined mathe- matically, we invented the process window index, or PWI, which represents profile quality with a single number. In this way, oven recipes could be compared, allowing us to develop a software tool that we called Auto-Predict (now known as Navigator). This completely elimi- nates the guesswork as the software automati- cally finds an oven recipe that will process the board in spec. "Our next group of products is used once you're ready to start production," said Kazmi- erowicz. "How do you know boards or parts were processed correctly? We monitor the temperature and speed along the oven con- veyor during production. We can say, 'Based on these inputs, your output is still within the range that is going to work, and your boards are being processed in spec.' Or we can iden- tify problems, such as if zone eight and nine changed significantly. Our setup tools help the customer find the correct oven recipe and our automatic systems continuously monitor pro- duction. Simply trusting that no changes to the oven have occurred since you last attached thermocouples to your board or silicon—how- ever long ago—is just not enough. Now, more customers want our monitoring capabilities." Less Downtime Allen summarized downtime as follows. "We all know that one of the worst things to hear in a factory is 'downtime' because this has a direct link to lost money/profits, delay in delivery, unhappy managers, owners, and most importantly, customers. With so much automation, there still tends to be the possi- bility of downtime in the reflow process. A reflow-related defect found by an AOI machine requires immediate action, for example. One of the investigative steps may be to run a pro- file to determine if there was any change in the reflow oven to determine if the fault is due to a process change, human intervention, or some- thing else entirely." "This downtime may be significantly reduced if a reflow process inspection (RPI) system is in use," explained Allen. "This RPI system will continuously monitor the conditions at the product level, provide the customer with data for each reflowed PCB, and notify the cus- tomer if a change is taking place and to what degree. If the current conditions are changing to a point where product entering the oven would not be in spec, a notification will take place and be automatically documented, and defective assemblies may be avoided. If there's a defect found at AOI, you can rule out the oven. Allen further detailed, "Planning for change- over downtime plays a role in optimization. With the knowledge of what products will be run on a given day, shift, oven, and their related profiles, the software can assist with the optimized plan to limit this changeover time in the reflow oven. An example is starting with SnPb assemblies and/or lower temper- ature profiles and working up to higher tem- peratures rather than the reverse, which takes time for oven cool down." Kazmierowicz added a few numbers. "Talk- ing about automatic systems that monitor every board, our last estimate was that 7–8% of all of the ovens out there have one of these sys- tems. There are a lot of upsides." This makes Our setup tools help the customer find the correct oven recipe and our automatic systems continuously monitor production.

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