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AUGUST 2019 I DESIGN007 MAGAZINE 97 vices in vehicles. The internet of things (IoT) applies to a car as much as anything else these days. With medical, it's all about being small, thin, and flexible. There are lots of innovations with surgical devices, both single-use and re- usable. It's a great space to be in that's helping a lot of people. Creeden: Regarding printed electronic circuits (PEC), normally, you have copper, which has both a smooth and a rough side. All of those things play a part in the transmission of our signals. What can you tell me about printed electronics? Hunrath: It's a fully additive process. Instead of applying a sheet of foil to a dielectric and then selectively etching, you're printing your circuitry on a substrate of some sort—usually Mylar or polyester film, but not always—and you're building up your layers on that. Creeden: And what is that material that you're printing with? Hunrath: Typically, it's silver—at least there are silver conductors. DuPont has a whole range of conductors for various applications—every- thing from fired-on to in-mold and membrane touch switch. They have a broad range of prod- ucts with various binder systems for different applications, but most often, it's silver-based. However, DuPont does have other products as well. Creeden: Based on most people's understand- ing, a printed electronic is usually a single-lay- ered circuit; however, it can be a multilayered circuit, and it's not that difficult to achieve. Can you tell us about that? Bowles: Chris already touched on it with the low-temperature, co-fired ceramic (LTCC) ma- terial that DuPont offers; essentially, we print silver and then co-fire on ceramic. We can also print specific gold applications, but we use those in higher frequency applications, and it is a rigid material—not a flexible material like Pyralux. Creeden: So, it can serve as a way to encapsu- late and separate two traces? Hunrath: You can do many layers in one shot. Basically, you print the individual dielectric green layers all at once. You take unfired sub- strate, apply your conductors, stack them, squeeze them together, and then fire. You end up with a high-performing multilayer that is very low loss in a lot of cases. Creeden: And this can all be put into a 3D mod- el to be form-fitted to whatever you want. Hunrath: They are planar circuits, and they're very rigid when fired, but it is a 3D structure in terms of the layers and conductors. Creeden: Right. The point I'm trying to convey is that it's not the 2D world we think of for a regular or flex board. Hunrath: You can have cavities and other fea- tures in there. The material doesn't melt and flow like other materials. Creeden: Is there anything else you would like to add as a closing statement? Hunrath: We're here to help. We supply materi- als of all kinds, so let us know what you need. Creeden: Thank you both. And designers, as you consider doing flex or printed electron- ics, there's usually a support structure needed. Talk to your fabricator early as well as mate- rial suppliers, also if you get the chance, visit the DuPont Technology and Innovation Center. Hunrath: You're welcome. Bowles: Thank you. FLEX007 You can do many layers in one shot.