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108 DESIGN007 MAGAZINE I AUGUST 2020 An easy solution came to light using silver ink printing for thick-film circuit technology. It looks like a Columbus egg. The process is very simple (Figure 1). Silver-based conductive ink is screen-printed on a thermoplastic sheet to create electronic circuits. Single-layer circuits are easy to make. Double-layer and multilayer circuits are practical as they are made on a film base substrate with via holes. Through- holes are easy to make using a traditional thick film process. The baking temperature should be relatively low to generate a higher yield. Appropriate ink materials are selected for the thermal process. The second step of the pro- cess is to place the work in a die set after pre- heating. A vacuumed forming could make a better shape for the thicker substrates. We are successful using PET sheets, PEN films, acrylic sheets, polycarbonate sheets, and more. There may be additional plastic resins available. 3D circuit technology is not universally avail- able because of mechanical stresses during the forming process. The forming on the corners requires a radius greater than 2 mm, and the silver traces should be wider than 0.3 mm. We are preparing a design guide for 3D circuits. The best feature of this 3D circuit technology is the wiring built-in plastic parts. The plastic parts will serve as mechanical framing and wiring—hence the name monocoque printed circuits. The use of supplemental flexible cir - cuits and wire harnesses are not required; the space required for wiring is reduced with- out an increase in cost. There are no special technologies or manufacturing equipment required, but experience using specific materi - als is necessary. FLEX007 Editor's note: Read Part 1, Part 2, Part 3, and Part 4 on monocoque printed circuits. Dominique K. Numakura is the managing director of DKN Research LLC. To read past columns or contact Numakura, click here. EHang Holdings Limited, the world's leading autono- mous aerial vehicle technology platform company, announces it will build a new AAV production facility in Yunfu city in Guangdong, China with a planned initial annual capacity of 600 units and an RMB42 million (US$6 million) investment supported by the local government in the facility. The EHang Yunfu facility is aimed to be established as an industry-leading AAV production center, including an R&D facility for air mobility solutions and a training center for operations and technical talents. The Deputy Mayor of Yunfu city, Donghong Shi attended the launch ceremony and commented that the Yunfu city government welcomes and fully supports the world's leading high-tech company EHang to establish its new production facility for the cutting- edge AAV products in Yunfu and it is expected to bring strong vitality to the local high-tech communi- ties and create hundreds of new jobs for local talents. (Source: Globe Newswire) EHang Expanding Facility for Autonomous Aerial Vehicles Figure 1: The basic manufacturing process of monocoque circuits (step 1: Screen print single-layer double-layer, and multilayer circuits with via holes; step 2: forming in the die set at the appropriate temperature and pressure).