Impact of Wearables on PCBA Design: Their Past and Future

For kids growing up in the 1960s, wearable technology was a fictional construct. Popular heroic figures like Batman and 007 (Bond…James Bond) used wearables to communicate, set traps, monitor their health, and more. 

But by the time the kids of the ‘60s grew up and sent their children off to college, Apple watches and other types of wearables had become mainstream. Wearables today are not only abundant and cost-effective, but they’re also so commonplace that we barely notice them. 

The future of wearable technology, though, depends on our PCB design capabilities. In fact, PCBA design and wearables are inextricably linked, as both sides influence the other. Demand for wearables is pushing electronics manufacturers to make their devices smaller, denser, and more flexible. 

Increasingly subtle wearables open up new sectors and find new applications, expanding their number of potential uses.  Understanding this relationship is crucial for modern electronics manufacturers.

In this whitepaper, we examine how wearables have evolved from concept to reality. We’ll cover how they have influenced PCBA design and where we can expect them to go from here. For those in the wearable and electronics industries, this is a critical and exciting time. 

The History of Wearable Technology

Most people's perception of wearable technology originates from the 1950s when the computer age began.  Early virtual reality setups, calculator wristwatches, portable radios, and portable calculators demonstrated the benefits of keeping modern technology near. 

But wearable technology has a much longer history. If 'wearables' refer to any knowledge application that empowers humans toward their goals, then they began during the 13th century when eyeglasses appeared in Italy. The wristwatch followed nearly 700 years later, providing easy access to timekeeping.  In today's world, high-tech watches get used for much more than just telling time.

Worldwide, portable music devices gained popularity in the late 1970s and exploded in the early 1980s. During that decade, digital hearing aids and fitness trackers became available. 

Things really took off in the 2000s with the release of the iPod and the development of Bluetooth technology.  Fitbit activity trackers pushed this tech even further by selling more than 120 million units between 2010 and 2022. Wearing electronic devices–even implanting them– is now acceptable, and perhaps on its way to becoming a necessity for everyday life. 

Future Wearable Applications

As underlying technology and PCB design processes improve, more wearable applications will become possible. The wearable computing devices market is predicted to grow nearly sixfold in value in the next ten years, according to a report by Future Market Insights. 

The next generation of wearables will include flexible memory storage and microprocessor components that will extend the possibilities for wearable computing devices. Wearables of this generation will be more energy and space efficient and will have wireless charging capabilities, all factors that currently impede some applications.

We’ll see more clothing infused with electronics and edge computing capabilities, ushering “smart clothing” into the mainstream. A wave of e-textiles is coming to market that put batteries, sensors, and circuits right up against the skin, giving individuals high-precision data about their body’s movements. 

These e-textiles extend into other areas as well. With knitted electronics, MIT researchers recently built a smart mat to go with a smart shoe that could predict motion and yoga poses. The wearables involved in these applications continue to become smaller and less bulky. 

Future wearable applications will bring together multiple cutting-edge technologies – like machine learning, IoT, 3D printing, and big data analytics – to give us richer information about every area of life. 

Challenges of Wearable Design 

We have compelling wearable technology today because of advancements in PCB design. PCBs have gotten more dense and flexible, while their capabilities have grown more powerful. Additionally, modular PCBA designs enable manufacturers to increase production as market demands rise. The use cases for wearables will continue to expand due to these reasons.

However, wearable design poses several challenges. These include: 

• To ensure that PCBs are highly efficient and built with low-cost, yet reliable components, engineers strive to balance functionality and size.
• Products must be lightweight and safe for extended use, so they can't generate much heat.
• High-stakes wearables, like heart monitors and fall prevention devices, require long-term reliability.

All these factors make PCB layout for this sort of design difficult. Increasingly, consumers expect wearable technology to keep pace with other advancements. 

How Wearables have Influenced Everyday PCBA Design

A new generation of PCBAs has been developed in part thanks to wearable technology design. There is a spillover effect between wearable technology and other applications as a result of these advances in technology.  Several new approaches to design are emerging, as well as innovative solutions to common problems, such as heat generation and component reliability.

The Rise of Rigid-Flex Design

Rigid-flex PCBAs have multiple advantages in wearables design, hence their increasing popularity. In addition to being durable, compact, and flexible, rigid-flex PCBAs can be folded into 3D shapes to fit specific enclosures. Rigid-flex PCBAs also offer high heat, moisture, and vibration resistance, making them useful for ruggedized and active applications.

But the hardest part of working with rigid-flex designs is that engineers must anticipate how the rigid and flexible components will be oriented. In narrow physical constraints, parts must be perfectly aligned and integrated with their final positions. Impedance control, in particular, can cause problems if components are not arranged well. Software tools can create clear visuals and make the design process easier.

Material Selection

Modern wearables are growing increasingly sophisticated, making proper material selection vital. Depending on the application, wearables may need to handle high speeds, hard impacts, and high-frequency signals. That’s why many electronics manufacturers upgrade from FR4 to Rogers materials, which can offer superior results when it comes to performance, power loss, coefficient of thermal expansions (CTE), and reliability.

On the structure front, PCBs for wearables tend to have between two and eight layers. Most have four layers. The advantage of having more layers is that engineers can utilize ground and power planes. More layers also give enough room for routing layers, minimizing crosstalk effects, and reducing electromagnetic interference (EMI) 

Mechanical Constraints

In wearable design, PCBs must yield to the eventual shape of the finished product, at least for goods with rigid containers. In these situations, electronics engineers have to optimize how components get positioned on the board and ensure ideal route tracing. To fit PCBs in tight spaces, it is necessary to select components carefully and plan around the final shape of the wearable.

Humidity is another variable that electronics engineers have to keep in mind on the mechanical side. Wearables that are meant to be worn close to the skin must be able to withstand a certain amount of moisture. If a device is not encased in a hard casing, it should be hermetically sealed or coated with a conformal coating.

Moreover, electronics engineers have to guard against electrical current leaks. To prevent electrocutions, battery spills, and other human-harming issues, components must be properly insulated. This is no easy task.

Thermal Management

As alluded to above, good thermal management is essential. With so many components packed into such small areas, electronics engineers have to think about thermal management at the outset of any project. 

With many wearables, there is little exchange with external air, so substrate materials and components have to be highly efficient. It is essential to strategically place thermal vias to help transfer heat away from the source components. Heat sinks and metal plates are also important for capturing heat from components that consume a lot of power.   

Further, consider using a dielectric material that is technologically more advanced than FR4. For high-frequency or power applications like those often seen in wearables, advanced materials with lower dielectric constants (Dk) are generally preferred because they minimize electric power loss. 

Power Restrictions

The design of wearables inevitably relies on batteries or energy harvesting for power. These designs adhere to strict power budgets with little room for overconsumption.  Prepare a power consumption plan by categorizing tasks by circuit block, then search for components that may require alternates to stay within your energy budget.  Your CM can often make suggestions. 

NASA’s Flexible Printed Circuits

Flexible printed circuits are now on the horizon, and organizations like NASA are taking full advantage, showcasing the potential for this design approach. NASA is considering 3D printing electronic sheets that can collect, store, and process meteorological data. The sheets would include antennas, microcontrollers, solar cells, batteries, and much more. A low-weight, cost-effective flexible printed circuit would be needed to make these sheets feasible.

However, not all of NASA's desired components are available in a flexible format. Despite this, the organization's investment in this area shows how wearable PCB design is on the rise. 

Wearables: Beyond the Fitness Tracker  

Thanks to the latest PCBA design best practices, wearables can now function as much more than fitness trackers. While the fitness tracker business is still booming, wearables are spreading quickly into other sports.

In swimming, smart goggles enable swimmers to follow training programs and track progress mid-workout. Wearable technology products with GPS and advanced monitoring capabilities now allow coaches to better understand body positions, speed, distance, and injury risk.

In addition to the sports industry, wearables are transforming a wide range of other industries. Healthcare, safety, manufacturing engineering, and on-demand training – are sectors in which wearable technology is having a massive impact. 

Healthcare

The healthcare industry will see even more wearable adoption in the future. Wearables give physicians more insight into their patients’ lives and add a constant layer of protection. For example, some devices prevent devastating events, like sudden falls, that can change a person’s quality of life forever. Companies now even sell smart insoles that can predict fall risk, analyze balance, and evaluate walking patterns. 

On a related note, previously mentioned e-textiles have the potential to support physical rehabilitation and therapy. Physicians use the data sent by smart clothing to analyze patient progress and give better feedback. In the future, senior citizens will increasingly use wearables for both health monitoring and fashion, giving them more confidence in their everyday lives.

Safety

The use of wearable technology enhances safety in many different environments. One clear example of this is an exosuit that gives wearers an extra set of “back muscles” for heavy lifting, thus preventing potential injuries. As another example, wearables fitted with geofencing sensors alert workers and their supervisors when employees step outside of designated safe areas.

The COVID-19 pandemic revealed another potential safety use case for wearables – encouraging individuals to maintain social distancing.  During the height of the pandemic, Amazon was among the first companies to test wearable devices to keep fulfillment center employees safe.  In another case, real-time haptic feedback wearables can monitor bend angle and twist speed in real-time, allowing supervisors to catch risky behavior in advance. 

Manufacturing Engineering

In the manufacturing sector, industrial wearable tech is enhancing onsite safety, improving supply chain accuracy, and more. In 2023, more manufacturers will purchase millions more augmented reality glasses to boost workforce performance. Wearable AR glasses have the ability to inform workers where to be and when, promote compliant practices, guide complex processes, and deliver remote technical support.  

Wearables can enhance the manufacturing engineering process, specifically, by making it quicker for engineering teams to visualize designs and make adjustments while on the factory floor. AR glasses are remarkably effective at showing simulations and animations that help teams think through complex engineering challenges. 

On-demand Training

Wearable technology also has implications for on-demand training. AR glasses give wearers the opportunity to learn in the field through simulated training programs. For example, power and utility workers can follow step-by-step instructions on how to navigate real-world roadside cabinets while on site. Factory workers can learn how to use complicated machines without human oversight, and medical students can work through simulations of high-stakes procedures outside of the classroom. 

With wearables-enabled training, individuals are much closer to the tasks at hand and experience training in a much more visceral manner. Plus, people can tap into the training they need when they need it. Used in this way, wearables remove the asynchronous nature of legacy training approaches.

Wearables and PCB Design Go Hand-in-Hand

This is an exciting moment in history for wearable technology. Wearables have already proven their value for countless use cases. Millions of people rely on wearables today to track fitness progress, listen to music, monitor health goals, and more. Workers are now wearing wearables to increase productivity and safety on the job site.  

Going forward, wearable technology will continue to change everyday life. As electronics companies develop new applications for wearables, PCBA design will follow suit. 

Endnotes–For More Reading

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