Issue link: https://iconnect007.uberflip.com/i/1108006
78 FLEX007 MAGAZINE I APRIL 2019 way, they have to have these properties. And how steep can you make the slope? And will it stick to this material?" I have to deal with all of those problems and make their part before they buy the equipment. Also, we have to do R&D to come up with new ways to do printing, such as shuttering. Historically, we've had a mechanical shutter. I was involved in the development of an internal shutter that sucks the mist to the side so that there's no buildup on a mechanical shutter. I'm a part of the applications group that does those kinds of advances. Matties: That's fun. Christenson: On any given day, you could be doing chemistry or fluid dynamics. It's pretty amazing. Matties: And geometry of shape is not an issue whatsoever? Christenson: Well, it's an issue in that the more 3D it is, the more axes you need. I have a pic- ture of a globe on a small plastic ball where we printed the continents. It takes five axes to do that, and the issue is programming those five axes. We have machine tool software that came from the five-axis mill industry, and we're working with a company that makes the software. One of the big problems is, let's say you're going around a corner, it's all right for a mill to slow down and just creep along the cor- ner and then come back up to speed. We have to hold a constant speed, and they're looking at us and going, "What?" Matties: Do you have to hold a constant speed because of volume? Christenson: Yes, because of what's coming out. Matties: Could you adjust for volume? Christenson: We're working on that. We can adjust it. Matties: It seems like the simple solution. Christenson: It is, but if it's a sharp corner, it basically has to go to zero while it prints around. Typically, if you want to do a sharp corner, the first thing I do is try to talk you out of it. Give me some radius. The second thing I do is print off one edge, print up the horizontal plane, and print up the vertical plane and let it connect. Or better yet, let me come in at 45 degrees; I'll hit them both and go through it both directions. And if you saw the picture of printing wrap- around circuits on one-half-millimeter glass, that's how that was done—twice at 45 degrees. We've spent a lot of time figuring out how to do stuff, so we can get you pretty close on what ink and hardware you need, and the program- ming techniques. We have a lot of expertise that was very expensive to acquire, and you don't have time to acquire it. Matties: Nor do we want to spend the time, right? Christenson: Correct. You want to buy a solu- tion. Matties: Is there anything we haven't men- tioned that you feel we should cover? Christenson: The only other thing is we're work- ing with passives, making capacitors, resistors, and inductors. That's a work in progress. We're doing okay on resistors. Inductors are three- dimensional and a little tougher. But we can even print transistors. We work with Dr. Frisbie at the University of Minnesota, who's the chair of the material science department, printing MoS transistors. When that material set gets done, that's going to be very valuable. Then, for very large area things like signage, you can just put the drive transistors locally. Matties: Well, it's fast-moving, and we're going to see a lot of changes. Electronics are every- where. Thank you for your time, Kurt. Christenson: Thank you very much. I'm glad you came by. FLEX007