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MARCH 2021 I PCB007 MAGAZINE 13 We need a robust technology, which is cost efficient and very powerful. lecting technologies that can be produced at a cost level so that customers will buy it. On the other hand, the solutions have to be very ro- bust, therefore we cannot always use sophisti- cated cutting-edge technology. As for materials and suppliers, you must have the right PCB supplier who can handle differ- ent materials. With the PCB suppliers we dis- cuss together which kind of material will meet the requirements. For example, referring to the two use cas- es: One of which is a very high temperature for power electronics. If you want to assemble a silicon carbide device on PCB and want to run it at 160°C or higher, then you need specif- ic PCB materials; you cannot use the standard FR-4 materials. If you use a high-frequency computer in your car, then you need low Df materials for low loss. ese materials are on the market, but until now, they were not fully qualified for automotive. We are looking into these mate- rials together with the base material suppliers and reviewing our findings together with our PCB suppliers. As you see, we do the material choice together with our supply chain. Holden: My last job before retiring was with Gentex, a very large automotive supplier. And matching the quality requirements of BMW, Audi, Mercedes, Toyota, and Nissan—it's much tougher than the military market in terms of the focus on quality. And yet it also has to be low cost. In the military market, with the high qual- ity also goes high prices, but automotive is high volume. I once got a call to work on the F-22 fighter and I asked them, "Why are you calling me? I don't work with military HDI boards." ey said, "No, we've heard and seen your pa- pers on automotive HDI. We're going to base the F-22 on automotive requirements and qual- ity, not military." I said, "Okay, if your focus is using automotive quality, then I can help out." Klein: I have heard about that. Automotive of- ten has the most severe requirements in the market, due to a long lifetime and the different environmental conditions, including temper- ature and humidity. Imagine, especially in the Far East, the conditions there in a parking lot. e most important concern is temperature cycling, temperature storage, and humidity. Matties: Interesting. When you're looking for a PCB supplier, what is most important to you? Klein: Most important is that the PCB suppli- er can deliver the technology at the required quality at a reasonable cost level. e long- term strategy between Bosch and the supplier has to fit. Due to the long product life cycle in automotive the suppliers have to work with us together for several years. From a technology point of view, PCB suppliers have to be excel- lent in quality, processes, and long-term stabil- ity. ey must have excellent quality measur- ing tools, their whole processes have to be re- ally well developed and documented, so that we can trust in them and that we will get the same quality today, next year, or in five years. is longevity is a reason we do not go into the most sophisticated technologies. We need a robust technology, which is cost efficient and very powerful. Johnson: Christian, it would seem to me that materials and techniques are adequate but not ideal. Is that a fair summary? Klein: I would say at the moment the materials are okay, but we are facing a lot of technology changes during these next years. Nobody real- ly can evaluate what comes next because the