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88 SMT007 MAGAZINE I MARCH 2021 It's Time to Broaden Our PCB Design Horizons Designing boards for these devices will take a lot of skill on the part of the PCB designer, as well as a willingness to learn new tricks. Device memory, CPU, and wireless circuitry can oen fit onto a system-on-a-chip (SoC) component in the assembly, but chip designs will have to accommodate other critical com- ponents packed into a small layout. Using the same old tech to design boards for IoT will get tougher and tougher. ere are packaging technologies available to help design- ers create boards small enough in thickness and diameter to accommodate the needs of smaller IoT devices. ree-dimensional integrated cir- cuits can help reduce power consumption on a smaller design footprint. Multi-chip modules allow multiple integrated circuits to function as one—potentially reducing the cost of the board while improving performance. Designing PCBs for IoT also requires think- ing about how the end-product is manufac- tured and put to use. For many IoT devices, PCBs are oen embedded in other materials and must be flexible. at means your board design will likely feature newer materials like plastic, mesh, and flexible copper. To move ahead, designers need to adhere to sound, established design methodology as well as tools that elevate their performance. Using more advanced PCB design tools will help designers respond to the demand for IoT devices. Best Practices for PCB Designers on IoT Projects John McMillian's 2017 white paper [1] remains the gold standard for IoT board design. Keep the seven design aspects laid out in that paper top of mind and it will help meet the challenges associated with IoT devices. We encourage you to download the paper and keep it on hand for reference. In the meantime, here is our take on McMillan's seven keys to IoT PCB design: 1. Know your design domains. IoT designs with multi-chip modules integrate analog-to- digital, micro-electrical mechanical systems (MEMS), and radio to make them function as one. e more experience you have with these types of circuit design, the more easily you can create a PCB for IoT that meets your function- ality requirements. 2. Stay focused on design constraints. Oen, the nature of IoT devices puts limits on size and weight that trickle down to your design. If you are adding connectivity to a well-established product, for example, that can really be a challenge for the PCB layout. New versions of established IoT devices need to do everything the last model did, plus more, without getting any larger or heavier. 3. Broaden your component vocabulary. Before you begin to design in earnest, make sure you are familiar with all the components that create functionality for data flow, device display, and Wi-Fi connectivity. You will be building your design around these compo- nents, so the more familiar you are with them, the better. 4. Your schematic needs to convey the design's intent. is includes issues such as physical constraints, cost considerations, and component availability. Keep this in mind as you create the bill of materials (BOM). Remember to verify part footprint sizes and height above the board as part of that investiga- tion, especially on a highly constrained design. 5. Test early and test oen using all the tools available to you. Model-based design and testing tools will allow you to test, simu- late, and verify the design's functionality. Use them. is is how you catch problems and make changes before a prototype build. 6. Learn the critical elements of board layout. Your CAD tool should allow you to visualize the board in its enclosure before you deal with routing and tracing. Using both 2D and 3D views for verification of things like

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