The electronic industry also knows the Internet of Things or IoT as the fourth industrial revolution. According to PCB Trace Technologies Inc, since the beginning of the digital era, IoT has grown into one of the most significant movements. So much so that users feel its effects more deeply, not only within the frameworks of technology, but also in daily life.
Acting as the crossover between the physical world and digital electronics, devices connected to IP networks make up the IoT infrastructure. Although one of the prominent examples of IoT in everyday life is the smartphone, IoT devices now control home appliances and utilities through apps. The vast potential of IoT is evident from the introduction of wearables and autonomous vehicles with data accessibility.
Unknown to most consumers, PCBs or printed circuit boards are at the core of the IoT revolution. In fact, PCBs and IoT are both mutually contributing to the development and engineering of their individual technologies. While IoT devices are infiltrating into everyday life and technology because they are assembled on PCBs, the industry had to develop special types of PCBs to meet exclusive needs of IoT devices. It is important that designers understand this interdependence of IoT and PCBs.
For instance, the IoT revolution dominates the manufacturing, transportation, and healthcare industries, going far beyond the innovations taking place in the consumer electronics industry. Interestingly, these industries are also demanding enough to enable innovative PCB designs that are not only highly flexible and offer small form-factors, but also offer high-speed connectivity for streamlining process.
Every new idea in electronics needs a PCB to support it. The idea may be optimizing personal GPS navigation on car dashboards, tracking health conditions by wearables, or monitoring train arrival times. Medical devices and wearables require special PCB form design and the flexibility to make them fit body parts, while offering high-power capabilities.
Earlier, the structure of necessary inner components often defined the shape and size of a computer. That is no longer true now; the industry can now create optimal IoT solutions that, irrespective of its form, offers the same functionality. Therefore, engineers must reimagine internal circuitry that can successfully reflect this change. Innovative PCB designs make it possible.
For maintaining the design freedom necessary for IoT devices, and to sustain the functionality of new form aspects, PCB manufacturers now offer flexible PCBs and high density interconnect or HDI PCBs. These innovative PCB design technologies not only cater to the increasingly tightening space for circuit boards, but are also suitable for functioning in harsh environments, including constant device stress.
Traditional rigid PCBs have tremendous design limitations. Flexible circuit boards not only overcome these limitations, but also offer achievement of revolutionary forms and shapes for improved fitment and functionality. Apart from new forms and shapes, flex PCBs also reduce costs and assembly errors. For instance, flex PCBs offer many advantages for designs focussing on IoT devices:
Reduced Size — While rigid PCBs limit design freedom, they also require more space within the product. The use of flex PCBs, on the other hand, can allow complex designs to fit small packages, while providing the same or enhanced performance.
Denser Circuitry — Thin, flex PCBs can also support highly dense circuitry.
Weight Reduction — Lower space occupancy of the PCB leads to weight reduction, and this can lower the weight by up to 95%. Add to this the option for smaller internal components, and IoT devices can be more versatile for all applications, whether for wearable hearing aids or for lightweight surgical implants.
Improved Durability — Using flex materials leads to an improved level of durability, and an increase in the device’s resistance to stress from vibration and impacts. This is helpful in industrial scenarios, where IoT devices with flex PCBs can withstand harsher operating conditions. Wearables with flex PCBs can resist performance degradation from regular movement, and body humidity, sweat, and heat.
Simplified Wiring — By eliminating interconnecting cables and connectors, flex PCBs offer simplified wiring methods for IoT devices. This reduces assembly errors while improving the reliability.
Personal electronics today require small-packaged designs, which is made possible by using high density interconnect or HDI boards. While small spaces require small-form flexible PCBs, their smaller size requires high-density packaging that only HDI boards can provide. For IoT devices, HDI PCBs offer specific advantages:
Weight and Size Reduction — Special design and manufacturing methodologies for HDI boards makes them capable of very dense component placement. Manufacturers achieve this by having thinner trace widths, closer spacing between adjacent traces, and the use of microvias that they stack to reduce board space. This makes HDI boards ideal for use in IoT applications.
Improved Signal Integrity — The use of blind, buried, and stacked microvias in HDI boards offer versatile routing options for extremely dense parts of the circuit, The shorter distance achieved by the use of microvias improves signal integrity. This feature allows HDI boards to function at high speeds necessary for IoT applications.
More Cost-Effective — Dense circuitry of HDI boards leads to a requirement for a lower number of layers, reducing the cost of the board. The product is therefore simpler to manufacture and more reliable. A reduction in the form of the board also means a reduction in the material use, additionally reducing the cost of the board.
OEMs use HDI boards extensively for their advantage of miniaturization and higher reliability, essential in smart IoT devices. However, the high density of the circuits implies only high-caliber assemblers can assemble HDI board assemblies, as it necessitates extra vigilance towards the assembly processes.
The latest trend in IoT devices is to make them interconnect without wires. This requires the IoT devices to have wireless communication capabilities embedded in these smart objects. Adding RF technology to a product imposes rather strict design rules on the entire system, including the design of the printed circuit board as well. Additionally, it calls for specific test and validation processes during the manufacturing process.
Irrespective of the product being a wearable device, an industrial sensor, or a location tracker, including components dedicated to wireless connectivity puts up additional challenges for the design team:
Density and Integration — Adding RF capability means fitting more components into an already compact form factor.
RF Design — A product with RF capabilities involves following stringent design rules for the maximization of radio performance, avoiding EMI, achieving EMC, and satisfying any applicable standard or regulation.
RF signal routing involves matching impedance along the way. Without impedance matching, the circuit will generate significant power loss, and create dangerous signal reflections that can disrupt circuit functioning. Designers prefer to use microstrips and striplines on PCBs for impedance matching. Designers typically place the signal line either above a ground plane or sandwich it between two ground planes.
The choice of the stack-up also affects the RF routing. Although RF PCBs typically have two or 4 layers, but some boards may use as many as 8 layers. With a 4-layer board, it is easy to complete the routing as more space is available for components, while it is possible to create both power and ground planes.
Designers must also take care to isolate the RF signals, and prevent them from unwanted coupling to other signals. Typically, designers place components and transmission lines on the upper layer, followed immediately by an uninterrupted solid ground plane just below. RF circuits may also require adequate shielding to prevent them interfering with other signals.
The process of miniaturization of IoT devices is reaching a stage where even the usual SMT technology is no longer adequate. The trend is towards development of new package technologies for components like system-in-package or SiP, multi-chip modules or MCM, and three-dimensional integrated circuit or 3D ICs.
To avoid failures after deployment, designers must consider the potential issues during the design phase. Typically, it is customary to classify IoT devices as consumer, industrial, and enterprise devices.
Consumer IoT devices, like wearable devices and smart TV, require a balanced stack-up, proper selection of PCB materials for the required bend ratio, and managing connector constraints.
Industrial IoT devices, like those used in construction vehicles and motors, require high board strength, high voltage withstanding capability, and high thermal capacity. A high thermal relief is also necessary during the layout design to improve the PCB performance.
Enterprise IoT devices, like those used in computing devices and security systems, require high power reliability and RF or high-frequency connectivity. They also need adequate spacing for component rework, and ease of depanelization for improving their manufacturability.
IoT devices help in collecting data, which is necessary to build customized products. Optimized IoT PCBs are a tremendous help in defense, aeronautics, healthcare, and many other applications. According to PCB Trace Technologies Inc, the trend for PCBs in IoT devices is becoming more specific as businesses expand. Although new features bring newer challenges, a common set of requirements is always present and requires using similar design procedures.