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20 The PCB Design Magazine • September 2016 cenary, and have moved on to a new project by the time something has launched. I'm one of 20 JPL engineers listed on a patent (USD487715) for the "ornamental design" of the MER. Shaughnessy: It's interesting that you designed ev- erything inside the Rover body, and your patent is for "ornamental design." Do you have any other patents? Cardone: I managed the rover interior design, meaning that I took the designs of others and configured them within the rover. The electron- ic packaging concept was in a large part mine, but I did not do the detail design of the PWBs, chassis, RF components etc. The only detail de- sign I did inside the rover was the wiring, flex cables, a few pieces of secondary structure, and the cable tunnels. I'm not a lawyer, so don't know the ins and out of patent law, but I think a partial reason for the patent was so that it could be licensed to LEGO. I'm a co-author of one other patent for a novel electronic packaging method (US 6206705 B1) which I helped develop for a mi- cro-spacecraft study at JPL, and that I used on the JASON spacecraft. There was some interest in it, but I don't think it was ever licensed. At least I never received any checks in the mail. It used AMP elastomeric connectors, which were a piece of flex with parallel conductors on it, which was wrapped around a piece of silicon. All connectors are composed of a spring and a contact. With these the flex was the contact, and the silicon is the spring. Shaughnessy: You mentioned a "bias" against flex. It was like that until recently, but now we're seeing flex everywhere. Why do you think flex has become so popular lately? Cardone: Projects have review hurdles they all have to cross (early peer reviews, preliminary design review, critical design review, and detail design review), and without fail someone will submit an action item to justify the schedule impaction, cost, etc., of using flex over tradi- tional cabling. The fabrication cycle of a typical JPL PFC is about six months. And on the surface this is longer than a typical round wire harness, but it doesn't account for the downstream time savings. Another weak link for us is the limit- ed vendor pool for fabrication. Because of the panel size needed we get a lot of no-bids. We have one vendor that's been working with us since Pathfinder (that >30 layer rigid-flex I men- tioned before), and they have been great. So the bias I mentioned is at a project level where they are looking solely at project risk. I've been using flex, rigid-flex throughout my career, and I consider it just one tool in the box. If I think it's the right tool I push for it, and if not I don't. If it is becoming more popu- lar then this would have to be due to improve- ments in fabrication, and resulting cost reduc- tions. Some of it may also be due to reduced end-item assembly costs. Perhaps skilled labor, for end-item assembly, is less available or more expensive. Shaughnessy: What were the smallest and larg- est flex designs you've done? What was the most interesting? Cardone: The smallest flex I've designed was an R&D project to interconnect 4 MEMS accel- erometers. The line widths were 0.025mm, leg widths are 3mm, and the overall size is about 9mm x 8mm. The three legs allowed the unit to fold up in to a pyramid shape so that it could measure acceleration in all three axes. The largest flex designs I've done are proba- bly the robotic arm cable for the MSL rover. They are on the order of 10m in overall length, and they are three cables designed to 24" x 85" fab- rication panels (limitation of the lamination JOHN CARDONE ON DESIGNING FLEX FOR SPACECRAFT