Wearables and Smart Watch Flexible PCB: All You Need To Know


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The wearables and smartwatch flexible PCB industry has come a long way and is changing for the better.

Gone are the days when all a watch could do was to tell time.

Nowadays, we have watches that can monitor your health status, help you during physical workouts, or even show you directions. 

Moreover, we have wearables to make your life easier and more exciting, including smart clothes, head-mounted displays, and smart glasses.

All these devices have in common that they use flexible circuit boards to function.

Therefore, the flex PCBs are responsible for the wearable’s compact design and high efficiency. 

Today’s article explores wearables and smartwatch flexible PCBs, including material selection, benefits, and mechanical constraints. Let’s get rolling. 

Table of Contents

Understanding Wearables and Smart Watch Flexible PCBs

Wearables are devices designed to be worn by users and might include smart glasses or smart watches.

Wearable technology has become helpful in keeping our health in check, informing directions, keeping in touch with friends, and checking time.

Funny enough, modern wearables can check health metrics like glucose level and heart rate. 

What’s surprising is that not all wearables require skin contact to function.

And although they’re very useful, these devices might present health concerns, including exposure to EMF and electro-sensitivity.

Some users have reported headaches, ringing ears, fatigue, body pain, and hives upon using these wearables. 

Also, you must be careful with the wearables since fault circuitry cases can translate into severe shocks.

But so far, wearables and smartwatches have not disappointed, and we can only expect their use and performance to improve over time. 

Mechanical Constraints

The main difference between wearable and standard electronic devices is the size.

Most wearable electronics are very light and small in size while maintaining the functionality and performance of standard electronics. 

However, manufacturers and engineers find it difficult to minimize the weight and size of wearables while maintaining a suitable shape and effective performance.

More specifically, a challenge arises with effective trace routing and optimizing component placement.

At all times, use manual routing instead of the auto-routing feature. 

Manufacturers should ensure that the circuit board adapts to the container shape.

Moreover, manufacturers should understand that humidity and moisture can damage the board or affect its performance.

And since the wearable is always in contact with the body, it might release sweat, potentially damaging the device. 

Therefore, the electronics and PCB design should be able to handle moisture and humidity.

This is only possible if you fix a conformal coating of the PCB or seal the device’s case hermetically to prevent moisture penetration. 

Finally, the leakage current must be suppressed by insulating the circuit board and the wearable device.

As a result, you’ll avoid issues like overheating, battery leakage, and electrocution. 

Smart Watch and Wearables Material Selection

Woman with an augmented reality wearable

(Woman with an augmented reality wearable)

Most manufacturers design flexible circuit boards using laminate materials like Rogers, polyimide, and FR-4.

But since wearables and smart watches require high-reliability degrees and commonly high-frequency and high-speed signals, you might need more advanced materials than the common FR-4. 

Generally, the FR-4 materials have a dielectric constant of 4.5, while the advanced Rogers has a dielectric constant of 3.55.

High-frequency applications require limited signal losses, thus forcing manufacturers to use Rogers instead of the FR-4 materials.

Moreover, FR-4 presents a higher dissipation factor, especially at high frequencies. 

Regarding cost, a circuit board designed by Rogers is more reliable and has higher performance at an acceptable cost than those with FR-4.

However, we recommend Rogers and epoxy-based FR-4 to create your wearable PCB for applications where you’re undecided on which option to use. 

Obstacles in Wearable Electronics PCB Design

A sports woman using a wearable device

(A sports woman using a wearable device)

Is it evident that you can only achieve a high-performance wearable device by implementing economical and clever PCB designs?

Therefore, we have certain factors to consider when handling wearables that are unique and different from other electronics. 

Moreover, wearables encounter certain challenges during development that you must fix to achieve great performance.

This section highlights these challenges.

Dimension and form: One main challenge is that you’ll be forced to limit the wearable size while maintaining the same performance as larger electronics.

The same thing applies to the form perfect for its application. 

Materials: Wearable electronics don’t use standard materials.

You might have to use discrete, sophisticated components and materials, including mesh and rigid-flex PCBs.

Therefore, manufacturers recommend Rogers instead of the standard FR-4 materials.

Also, involving an expert throughout the material selection process would be best. 

Power: Most electronic components use small battery cells due to their compact nature.

Remember, compact electronics are designed to reduce power consumption while increasing performance and efficiency.

However, most batteries last only a few hours. 

Connectivity: We have seen a rise in electronics that offer connections like WiFi and Bluetooth.

However, this can not be said of some wearables since they don’t have enough space to attach such components. 

Antenna design: Designing antennas in wearable devices is challenging because the human body can waste energy. 

Humidity: The human body produces high moisture in sweat, which damages wearables.

Therefore, designers have to think outside the box for ways to limit humidity and moisture effects on the circuit board. 

Benefits of Wearables and Smart Watch Flexible PCBs

A customer paying using a smartwatch

(A customer paying using a smartwatch)

Wearables and smart watches present the following benefits to users.

  • First, they offer a hands-free experience, allowing you to make calls while driving.
  • Secondly, wearables provide convenience and portability.
  • Thirdly, they offer enhanced accuracy, especially in the medical field, where they provide reliable patient health data. 
  • Their improved efficiency boosts output and optimizes processes. 
  • They are lightweight and consume less power. 
  • Finally, wearables store essential information and provide it anytime you need it.

What are wearables and smartwatch flex PCB applications?

A man sleeping with a wearable device

(A man sleeping with a wearable device)

We have countless wearable devices supporting the following applications:

Fitness and sports: We have wearables that can monitor sporting aspects like oxygen enrichment, blood pressure, and heart rate or even alert the relevant personnel of possible injuries.

And besides athletes, individuals are also adopting these devices to monitor their sleep patterns and physical activities. 

Military: In times of war, soldiers use wearables to monitor the environment and keep track of their fitness. Also, these devices might provide the live location of soldiers to make real-time recoveries easier. 

Gaming and entertainment: One common area under this category is smart to-wear, which uses thermal energy to recharge tablets and smartphones.

Also, we have augmented reality which lets people explore different landmarks from their wrists. 

Health and medical monitoring: This is perhaps one of the significant applications with sensors in gloves, eyeglasses, and clothes to monitor a person’s health.

Moreover, wearables record biometric data to monitor a person’s heart rate and blood pressure.

And most importantly, people are now using these devices to monitor their physical activities. 

Smart clothing: A good example is Levis’s denim trucker jacket, which has Google software to allow users to play music and respond to messages. 

Navigation tracking: Nowadays, we have smartwatches with GPS to allow you to navigate easily to any destination. 


What electronics wearables use flexible PCBs?

Check out some common electronics with flexible circuit boards below: 

  • Smart glasses
  • Fitness trackers
  • Smartwatches
  • Head-mounted displays
  • Smart clothing

How do wearables affect the world today?

Wearables have had an impact in the past and continue to impact the world differently.

For instance, they have completely changed how we monitor our health and fitness.

Also, they enable us to communicate and receive messages and updates from our wrists. 

Moreover, wearables contribute to developing and integrating the Internet of Things.

And finally, in the military and medical field, these electronics contribute highly to improved safety and efficiency. 

Final Remarks

Wearables and smartwatches are just a depiction of how fast the electronics industry is growing.

This growth has been possible thanks to the development of flexible circuit boards which folds easily to fit into tight areas. 

You’ll find wearables in applications like fitness & sports, military, entertainment, medical monitoring, and navigation.

Regardless of the application scenario, these products generally offer high reliability, excellent performance, and low power consumption.