Phil Neudeck, Electronics Engineer, NASA’s John Glenn Research Center, Cleveland, OH

Neudeck: It absolutely is an inherently radiation-hard technology. That is another potential application. To put it in perspective, it’s my opinion that our advancement hasn’t really helped radiation hardness that much because as long as you weren’t operating in a really hot thermal environment, people could’ve made silicon carbide chips five years ago that would’ve been extremely radiation-hard. So we’ve pushed the thermal end of things, in my opinion.

NTB: Just to give our readers some perspective, what’s the projected cost differential between the silicon carbide components and your average silicon components?

Neudeck: I would say right now it’s a factor of about a hundred probably, just for the starting semiconductor wafer material. For finished parts, like room-temperature power diodes, the cost difference is much less, but still significant.

You have to need that special capability in order to justify the extra cost of silicon carbide over silicon. I have a review article on our Web site about the role of silicon carbide in high-temperature electronics and one of the statements I make in this paper is that a hundred dollars worth of high-temperature electronic component parts enables a system capability that’s worth millions of dollars to some people. So this is a very leveraged technology. In other words, the person that’s manufacturing the silicon carbide part may only make a few hundred dollars on it, but to the industry person, the new capability that it brings can be worth an awful lot over the lifetime of their product.

So even though the silicon carbide may be more expensive by a factor of a hundred, it’s a pretty good investment when you consider what the chip is doing in a big million-dollar or larger system.

NTB: Your test sample ran continuously for more than 1,700 hours at a temperature of 500°C. Do you think that’s the limit, or do you think you can improve on that with some design modifications based on what you’ve learned to date?

Neudeck: Well, I definitely think we have some improvements to make in terms of the density of the circuitry and whatnot. In terms of the thermal performance, this thing is still cranking today. We’re at hour 1,800 and it’s still going. This is actually part of the test where we’re trying to learn what the limits are for this part. So far the device has been operating continuously. It’s basically in the lab, in an oven, and the computer keeps collecting data, and everything is performing well. I don’t know how long it’s going to go, and I don’t know where the limits are on this device.

We’re kind of in a hurry to try and get some more parts packaged and hooked up and tested so that we can find those limits. If we can get another set of parts packaged, we’ll probably throw one in the oven, crank it up to a higher temperature, and see if we can accelerate failure a little bit. In the meantime, with this one at 500°C, we’re just going to let it run and see how long it lasts.