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42 DESIGN007 MAGAZINE I JANUARY 2020 Shaughnessy: What are some of the unique problems that are associated with doing circuit boards for LED applications? Beerhalter: There are two challenges, depend- ing on the market you are serving. Most of the LED products go into the mass market, so the primary design target is cost-effectiveness. How do we bring down the cost? One of the biggest numbers I always talk about is that 22% of an LED system's costs go into PCBs. That's significant because if you imagine the type of problem, the screen size determines the amount of PCBs you use. Behind every LED you see in the front, shining up and light- ing everything, there's a space on the PCB. The second challenge is design for manufac- turing and bringing down the cost, and design ideas to bring down the design time because you want to avoid designing 50 square meters of LEDs. You want to design a small tile and replicate it. This can be a good challenge to figure out how to do more than copy and paste to get systems to designs. Shaughnessy: I heard an engineer recently say that the trick is not how high-tech you can make the board, but how dirty you can make the signal and have it still work. Beerhalter: That's absolutely right. Let's say the prime objective in every design job is function- ality, so you design for function at the lowest cost possible. This is the objective we have in common with the car industry. But there's a second objective we have in common, and this is harder to achieve, and sometimes our com- petition disregards it. We design not only for function and signal integrity but also for EMI compliance. You don't have the chance to test that on a small scale; you have to test that at big scale. The whole display must be okay. Most designers have challenges bringing one small board to life. Imagine my situation: I have to bring 1,000 boards into the EMC chamber and have them pass EMC in one measurement. Shaughnessy: You can't run one prototype and see if it fails the smoke test.

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