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106 DESIGN007 MAGAZINE I AUGUST 2020 Next-Generation Flex Circuits: Monocoque Printed Circuits Several weeks ago, I released a short column about monocoque printed circuits, a new 3D circuit technology using thermoplastic materi- als considered next-generation technology for printed circuits. The circuit traces are built on thermoplastic sheets and bent using a heating process. The new technology reduces wiring space in mobile electronic devices and elimi- nates flexible circuits and wire harnesses. I received many inquiries, specifically request- ing detailed technical information. A few com- panies commented about their success with this same circuit technology. There is much interest from design engineers looking for practical 3D wiring material for compact elec- tronic devices, such as smartphones and digi- tal cameras. Let's take a brief look at this new 3D circuit technology. More than 30 years ago, a flex circuit manu- facturer in New England developed bendable circuits and modified the standard technology for flex circuits. A plastic resin was introduced as a base layer for copper foil laminates. The laminates were chemically etched to gener- ate copper circuits, and these circuits could be bent to form 3D wiring. Unfortunately, the base material was not stiff enough, so 3D cir- cuits were eliminated in many applications. Almost the same time 30 years ago, the basic concept for molded interconnect device (MID) circuits was created to build 3D circuits on plastic parts. The process of creating 3D components was already established through molding or injection using traditional plastic resins. Component manufacturers found it dif- ficult to generate electronic circuits on plastic components. They tried with newer technolo- gies (metalizing and laser scribing) but were unsuccessful due to the limited capabilities of these technologies. EPTE Newsletter by Dominique K. Numakura, DKN Research LLC