Investigating Analytical Tools for Testing Cleanliness with Foresite's Eric Camden

Estimated reading time: 16 minutes

Camden: Absolutely. Because you know there's only so many ways that you can solder a board. You still must have a component, whether it’s through-hole or surface mount, you’ve got to have solder, and you’ve got to have flux. In general, all these things have held true since day one. You must have these components and then there are a lot of ways to do that correctly and there are even more ways to do it incorrectly that will reduce that reliability. Whether we're working on an old PGA plated-through-hole or if we're working on a brand new QFN pattern that nobody's ever seen, we know that those same things that fail the older through-hole type components, those same issues will plague these finer pitched SMT low standoff type components. Like the QFN—especially the QFN we've seen so many problems with. When you see enough of these failures you end up fighting the same fires, just a different forest.

Goldman: Or you could say different customers and different configurations.

Camden: Right. Because they're all using solder paste, and they're printing it. Every line is basically the same. We've seen a lot of ways to do it wrong.

Goldman: Probably more wrong ways than right I would think. There's always more.

Camden: Yes, for sure. There's only a handful of ways to do it right.

Goldman: Getting back a little bit to about yourself. You've been 18 years with Foresite but before that were you in the industry?

Camden: I was not. I kind of came in blind as a bench tech 18 years ago. I got an entry level job and after about a year or so of just learning what these acronyms meant, I was doing ion chromatography. It was a whole different game 18 years ago than what we're doing today. We had two very small systems and it was all manual. But I worked around some very smart people who are still in the industry. And I just took an interest. I took notice of what they were doing. They were putting these boards under these microscopes all day every day and I was trying to figure out why. What are you looking for and how did it get there? I was around some good smart people who wanted to teach me, and I really took an interest to it.

Then I started looking at some of the IPC standards and how that applied to what we were doing. They’d say, does this pass? And I had no idea what a pass was versus a reject versus a process indicator. Once I started following up more and more on the visual side of things, that led to looking at the chemistry side of things and how we were testing with ion chromatography and how that related to failures or not. It really was just a natural interest for me because there are a lot of different things to branch out into. When you see a failure, it can come from 100 different things, and our job is to figure out exactly what that failure came from, what that material it came from.

At Foresite, we've always had a good library of chemistry signatures for flux types or PC fabs, things like that. It's doing something different almost every day when I'm looking at different customers but it's all under the same umbrella. So that helps because I know if it's flux related I know it's going to come from one of four different sources. Whether it's paste or spray flux, hand soldered or whatever it might be, it's going to be under that same umbrella. It was always very interesting to me to learn more and more about the assembly process. Looking at LEGOs, you need this piece, this piece, this piece for this whole thing to come together. But if you're not quite right it's going to fail, and I really liked the idea of digging into somebody else's process and determining how to optimize that to bring them back to making a good reliable product.

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