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34 The PCB Design Magazine • June 2017 McCurdy: We have very little experience with buried resistors, mostly because our customer base isn't asking for this. However, as product miniaturization continues, I'm certain that in- dustry will have to embrace the use of embed- ded resistor technologies. It's another method of freeing up surface space and increasing per- formance and reliability. Some of the CAD de- sign vendors have software tools for designing embedded resistor layers. Ticer Technologies and Ohmega Technologies make great materials for this. Shaughnessy: You all have done some really cool planar magnetic boards. Can you shed a little light on that? Does this entail literally placing magnets on the board to act as inductors? McCurdy: We've done some designs where we have routed a spiral of circuits on the inner lay- ers to create the windings of a transformer. We design cut-outs in the board where low profile magnets are placed to bridge over these coils. You end up with a much shorter transformer be- cause it's actually "in the board" rather than sol- der on top of it. Also, this technology provides improved heat distribution. Shaughnessy: Do you ever design boards with actual components inside the board? McCurdy: One project we did last year was designed with a cavity in the board. We put circuity in the bottom of the cavity where components were placed and soldered on. It was a challenging design solution for this unique application, and was expensive to fabricate and assemble. Shaughnessy: What do you think are the biggest pros and cons of embedded technol- ogy? McCurdy: There are a lot more positive ben- efits as board density increases. There are the physical benefits of freeing up surface real estate by embedding the caps and resis- tors. You can reduce the overall thickness of the boards, which helps your drill aspect ra- tio. There are improvements in quality and reliability. Embedded passives will also im- prove the electrical characteristics of the design with improvements to signal integrity, power delivery and noise resonance. The downside had always been cost, but there has been a huge increase in the usage of embedded passive tech- nology in smartphones, which has tremendous- ly increased the volumes of scale, and that has made the pricing more attractive. The trend to embedded passives will only increase from now on out. Shaughnessy: Is there anything else you'd like to add? McCurdy: I would suggest that designers and en- gineers investigate embedded passive solutions. Visit the websites of the companies that make and supply these materials to learn more about it. Contact your board fabricators and have a good discussion with their technical people. Find out what experiences your design house can share with you. The solutions are there and these are the people who can help you take that next step for advancing the technology to im- prove or make your next product possible. Or you can call me if you have any questions. Shaughnessy: Thanks for your time, Scott. McCurdy: Thank you, Andy. PCBDESIGN EMBEDDED TECHNOLOGY: A USEFUL TOOL IN FREEDOM CAD'S TOOLBOX Scott McCurdy