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38 The PCB Magazine • January 2015 ing launches of two new PCB printers. Voltera is a U.S.-based start-up that is about to launch a printer that prints conductive traces onto stan- dard FR-4 substrates. Voltera's system can print 10-mil traces on both sides of pre-cut FR-4. Similarly, an Australian start-up, Cartesian Co., having completed a successful Kickstarter cam- paign, is preparing to launch a printer that also prints two-sided PCBs with similar trace specification to Voltera. Both of these com- panies aim to support a wide range of substrates including paper, textiles and plastics. So there certainly are companies launching PCB printers. It is important to point out that printed electronics does not equal 3D printed electron- ics. By 3D printing standards, however, the world of proper multi-layer PCBs is a complex one. To 3D print electronics requires additional materi- als and different equipment. High-quality conductive trac- es are a must but so are three- axis capable printers and insu- lating structural ink. On one hand PCBs are multilayered, which implies they are well suited to additive manufacturing. On the other hand, the multiple materi- als, conductivity requirements and exacting precision required present serious technological chal- lenges. What is the current state of truly 3D PCB printing? There are two types of 3D printing technology that can be expected to rise to the challenge. Optomec of Minnesota uses aerosol jet technology which is a bit like a super precise spray can. This approach allows for very precise printing of conductive inks, such as that for cell phone antennas. It is an approach that can print onto any geometry/shape but isn't cur- rently being extensively used for printing the substrate itself. Inkjet deposition is likely to be the first truly 3D printing process to provide profes- sional multi-layered PCBs. To rise to the chal- lenge of making proper multi-layer PCBs the conductive traces clearly have to be printed in such a way that they are precise enough, conductive enough and robust enough to do the job reliably. Having solved the printing of ad- vanced inks to give precise con- ductive traces, the next step in order to 3D print a PCB is to print the substrate. For tradi- tional rigid boards the sub- strate ink material needs to be inkjet printable as well as an excellent insulator and of- fer rigidity that is comparable to standard FR-4. Flexible boards are another field and require a different combina- tion of substrate and conduc- tive ink formulations. Each substrate requires its own ink specifications to ensure adhe- sion, precision and compat- ibility with the relevant ink curing stage. If nano-materials can be engineered to meet the re- quirements of a PCB, the next challenge is how to manage the printer. The software has to be able to process Gerber files which are intended for a 2D manufacturing environ- ment. This would allow the 3D printer to print the substrate to the required thickness, leave and fill holes where vias are required, and so on. The only company currently dedicated to 3D printing complete multi-layer rigid PCBs is NanoDimension. Listed on the Tel Aviv stock exchange, the company is developing a 3D ink- jet printer that will offer in-house rapid-proto- typing of professional multi-layer PCBs. To this end, the company has formulated and makes its own nano-inks for the conductive trace and another proprietary nano-epoxy ink for the in- sulating layer. The company promises a trace width of 3–4 mils. 3D PRINTING PCBS continues it is important to point out that printed electronics does not equal 3D printed electronics. By 3D printing standards, how- ever, the world of proper multi-layer PCBs is a complex one. to 3D print electronics requires additional materials and different equipment. high-quality conductive traces are a must but so are three-axis capable printers and insulating structural ink. " " FEaturE