By Suresh Patel, Sales Engineer, Mer-Mar Electronics
One of the mega tech trends revolutionizing today’s digital world is the ubiquitous Internet of Things (IoT). The significant factors pushing the IoT market are the decreased cost of CPU memory and storage, abundant availability of sensor devices, and accessibility of expandable repositories for storing data (like cloud services). The IoT devices can track, monitor, control, and optimize the information about a product features that are particularly useful in applications such as smart farming, connected vehicles, smart grids, and many more.
The design of an IoT device depends on the precise selection of the sensors, wireless connecting network, and power management. The traditional PCB design methods may not support the functionalities offered by an IoT product. Wearable IoT devices like fitness trackers or smartwatches are supposed to be smaller in size but with maximum packed features. For example, a smartwatch includes a clear display, multiple sensors, a microcontroller, a Bluetooth chip for communication, and a battery. A PCB in such an application is expected to be very tiny yet reliable in operation.
In industrial IoT applications, the requirements are even more stringent as most of these devices are expected to be online and transmit information with no downtime. The PCB design in these applications should focus on effective power management.
Most IoT devices are designed to operate in a moving environment with resistance from the external setting. Conventional routing techniques are not suitable for this application. Flex and HDI PCB are used to develop tiny, lighter, and faster IoT devices.
Fabricating flex PCBs for IoT is quite different and demands accurate measurement of bend ratio, signal trace thickness, copper weight, heat generation of the components, and lifecycle repetitions. Thus, the PCB development and fabrication processes continuously upgrade to meet the IoT market requirements.
Design requirements
The substrate material of an IoT PCB should be flexible and lightweight. Flex PCBs and HDI PCBs are extensively used in this application. Flexible PCBs are best suited for wearable devices as more components can be placed in a small area. HDI PCBs simplify the wiring along with minimal mechanical stress.
The compact design requirements demand a thorough simulation and virtual prototyping to incorporate the design shape in the intended form of the IoT device. The necessity for miniaturized components has increased dramatically. Many latest sensors are manufactured using MEMS (Micro electro-mechanical systems) technology to offer small footprints with high reliability. Future IoT designs may favor a new approach where mechanical and electrical circuit changes can be done concurrently.
IoT applications have eliminated the luxury of space for designers in component placement and routing. Multilayer PCBs are designed with strict EMC regulations. The peak component density and an increased count of vias in the circuit are achieved using HDI PCBs. The integrity of the sensor signals must be ensured by eliminating any possible coupling and interference issues in the design.
The component packages cannot be through-hole or surface-mount types in an IoT design so there’s no possibility for through-hole or SMT PCB Assembly. The miniature gadget size has resulted in the development of new package technologies like multi-chip modules (MCM), system-in-package (SiP), and integrated three-dimensional circuits (3D-ICs).
One of the critical requirements of an IoT device is the extended battery life. Designers should choose the right power management integrated circuits (PMIC) and calculate the power budget for each functional block. Power consumption varies according to the device’s operating device’s state; hence, analyzing all corner cases is important during power estimation. The battery life drains faster in applications like health care monitoring devices, wireless transceivers, etc, which involve continuous activity. Techniques such as energy harvesting and design compliance with wireless standards can improve power efficiency and battery life.
As the IoT devices are connected to a shared network, a security breach is an apparent possibility. There are applications involving sensitive data like medical details or financial information which can be misused. Along with the software security updates, there is an increasing need for hardware protection in IoT devices.
Another vital feature required in IoT devices is their adaptability to end-user interaction. The human body temperature, moisture, and mobility can affect the performance of an IoT device, especially in wearable products. In an IoT PCB design, simulating these conditions and implementing suitable compensation circuits are important.
Manufacturing requirements for IoT PCB
Involving the contract manufacturer from the design stage is recommended for an effective PCB fabrication for your IoT device. Flexible PCBs, and components in SiP packages can simplify the fabrication process. Preventing the usage of counterfeit components, and adding identification codes in each layer of the PCB can improve the security of the IoT circuit.
It is necessary to consider the potential issues during the design to avoid failures after deployment. Generally, IoT devices are classified as consumer, industrial and enterprise devices. The DFM requirements of a consumer IoT device (like smart TV, or wearable devices) are a balanced stack-up, managing connector constraints, and selecting the PCB material with the required bend ratio.
Industrial IoT devices (like motors and construction vehicles) are supposed to have high board strength, thermal capacity, and high voltage. Including enough thermal relief during layout design is recommended for better PCB performance.
Enterprise IoT devices (like security systems, and computing devices) demand high power reliability, high-frequency/RF connectivity, etc. The ease of depanelization and enough spacing for component rework can improve the manufacturability.
We can collect data and use this information to build customized products with IoT devices. Combining IoT with 3D electronic printing technology has a tremendous potential to speed up the manufacturing process and can also build 3D PCBs. An optimized IoT PCB can be used in healthcare, aeronautics, defense, and more. The PCB design for IoT applications may become more specific as the business expands. New features can bring new challenges, but a common set of requirements indicate a possibility of using similar design procedures frequently.
About the author
Suresh Patel has worked as a Sales Engineer and in other management roles at Mer-Mar Electronics. He brings 25 years of experience in printed-circuit-board sales, technical client service, and business management.
