Seven core considerations will help you implement IoT PCB more effectively. IoT has had a profound impact. New connected products are being launched. Existing products are becoming smarter. Read this article to understand the relationship between IoT and PCB circuit boards!
1. IoT PCB Design Areas
IoT products typically collect information from the real world, covert it into the digital world, and then transmit the data to the cloud. Some analysis may be performed and the results are then sent back. Therefore, there are four main IoT design areas:
(a) Analog
(b) Digital
(c) MEMS
(d) RF
To reiterate the previous paragraph, MEMS sensors collect data, perform analog-to-digital conversion for input to a microcontroller, and the results are transmitted via standards such as WiFi, Bluetooth, and 3G/4G. Reverse path digital-to-analog conversion is also possible depending on the response as part of the device's functionality.
2. Form and Fit of IoT PCBs
Wearable devices illustrate many of the form factor challenges facing IoT PCB design. A company developing a smartwatch wants it to be the same size and weight as a traditional “dumb” timepiece. IoT innovators typically approach this problem from two starting points:
(a) Potential functionality is identified, and then developers explore whether it can be put into a suitable marketable enclosure.
(b) Developers see an opportunity to add functionality to an existing product, and then explore whether that functionality can be accomplished with as little impact as possible on the original product. Either way, complex functionality may need to fit into a cramped living space.
3. IoT Design Components
The main impact on “form and fit” is correctly identifying the components to populate your PCB. However, these parts are only what is needed for operation. Your design may require a fingerprint reader, different types of MEMS sensors, or different RF standards. You need to lock them down early - and don't forget the external interfaces (buttons, switches, charging ports, etc.).
4. Capture IoT PCB Design Intent in Schematics
You have the component types. Now you have to determine how to put them together and assign the right part numbers for the specs and target dollar cost. Developing schematics starts to show you how to get there. In addition, the right tools will allow you to do analog/mixed-signal circuit analysis and identify some of the signal integrity challenges you may encounter before you do the actual layout.
5. Simulation, Verification, Power, and Memory in IoT PCB Design.
IoT designs look simple in function, but they prove to be more difficult than that. The old adage is that you should catch as many problems as possible early in the process. Consider just three of these challenges (there are many more):
(a) IoT designs are small and must often provide long battery life. As a result, they may need to operate in a variety of power states and perform different tasks. Each must be functionally verified.
(b) Similarly, what about the risk of failure due to voltage loss on critical nets? Will certain areas of the board be prone to excessive current density? Again, catch these issues early.
(c) Connections between microcontrollers and memories are also troublesome and are affected by many factors, including transmission line losses, crosstalk, and timing delays. Accurately limiting these connections before layout will reduce debugging time later, especially if DDR standards are used.
6. IoT PCB Layout
If you have followed the principles listed, it should be much easier. The outline of the board will now go into the layout and should also be known by two-way cross-probing between the layout tool and the schematic. But there are other considerations:
(a) Component placement. Layout tools that allow you to switch between 2D and 3D views are particularly useful for IoT design, given the possible form factor constraints.
(b) Constraint management. Being able to propagate predefined electrical constraints through the process will help you control net categories and groups, define pin pairs, etc. The results will be even better if you can use layering rules in the tool.
(c) 2D/3D layout. This feature is more than just dropping components. Is the overall structure correct? Can you import the proposed mechanical enclosure and check it against the specs? The ability to switch views will help a lot in these and other areas.
(d) Rigid-flex boards. As mentioned earlier, rigid-flex boards are particularly useful for IoT design only if your layout tool allows you to properly check its curvature, the placement of parts on their layers, its routing and plane shape filling. If, as such, you can take this rigid-flex design and export it as a solid model to an MCAD system, you can greatly mitigate potential manufacturability and assembly issues on the production line.
(e) Test IoT designs. Good DFT always pays off. For IoT, it is particularly relevant for metrics such as RF range, battery life, interoperability, and response time. Operation over a wide temperature range and in multiple power states, possibly, should also be checked.
7. Fabrication and Assembly of IoT PCB Designs
Software that performs design for manufacturability and assembly (DFMA) analysis before sending a design to manufacturing can encounter issues such as resist fragmentation and copper exposure. Panelization considerations and using database standards can make the transfer of design files to manufacturers smoother, which should also be part of your design process. IoT designs often have to work within extremely tight margins to be profitable. Any kind of delay or re-spin can turn such a project into the red.