Issue link: https://iconnect007.uberflip.com/i/1367446
68 SMT007 MAGAZINE I MAY 2021 manufacturer is trying to monitor or keep track of. A big challenge for us was to come up with something that a fixture can do; run it through the process, get preheat topside temperatures, ramp rates, make sure you're activat- ing the flux, and then capture some wave data as far as dwell time and parallelism with the fixture. But now what do you do during production? With a board going through a pot of liquid solder with a wave pumping and trying to have sensors and data collected so you can actually capture that data and do something in real time, this was our challenge. e answer to that challenge was the WPI or Wave Process Inspection. It matches what our capability is on reflow with our RPI sys- tem, but it takes into account certain aspects of what the customer needs to measure when the board is going over the wave, which is dwell time. We have come up with a way, during pro- duction, to not only get the entire temperature profile of the product going through the pre- heat and the wave, but also a real-time dwell calculation for each and every production board. at's been a big challenge, and we've got it nailed down now. Johnson: For those who may not be particularly familiar with the importance of dwell time and why it's a challenge, could you give us a quick primer? Moreau: When it comes to the wave itself, the flux activation part is in the preheat coming up to that wave. Proper activation facilitates the soldering and cleans the surfaces. e dwell time is going to affect or impact the quality of the solder joint. It's how long the board is going through, and in, the wave. Most impor- tant is getting the metallized surfaces up to sol- dering temperature for proper wetting. Dwell is what facilitates this part of the process. Johnson: KIC has been working on some ongo- ing R&D throughout 2019-2020 that is just starting to roll out; tell me about it. Moreau: We've had good solutions and a rep- utation for great reflow-related solutions around profile setup, optimization, and mon- itoring or inspection during production. at has been KIC's forte, and we do that across SMT assembly and semiconductor packaging. We've always had requests from our customers for other thermal processes, with wave being one in particular that's handled on the profiling side. We have some good solutions that help them set up and do a check on the machine, but it's always been a challenge during produc- tion. Wave is a multifaceted process of fluxing, preheating, and then soldering, as opposed to the oven being continuous where it all happens during the same process and flow. How do you adapt? Because the machines can be config- ured a lot differently—some have convection, some have IR heat, different ways of applying the heat, top and bottom zones, sometimes only bottom, two waves vs. one wave, all sorts of different things—that makes it really chal- lenging. ere are some aspects around the mechanics of the wave that are part of what the KIC WPI—wave process inspection. Click here to learn more.