Ideas and Innovation Blog

In today’s rapidly-evolving tech landscape, design engineers face a significant challenge of fitting ever-increasing numbers of components and functions into smaller and smaller devices. This trend is only going to grow, leading to an escalation of form factor challenges that engineers must address. High-tech devices today are inherently complex and require engineers to coordinate and incorporate a range of materials. Engineers need to approach design from a flexible perspective to meet the ever-changing demands of modern electronics.

Printed circuit boards (PCBs) are a cornerstone of modern electronic design. PCBs are rigid boards that utilize a solid material with multiple layers connected by vias. The vias allow signals to travel between the layers and create electrical connections. However, with the rise of form factor challenges, design engineers are being forced to find innovative solutions that unconventional packaging can provide.

Enter the flexible PCB. By employing layers of materials that include a polyimide film, adhesive, copper and other alloys, flexible PCBs can bend and twist to fit the contours of any application, ensuring that new designs can incorporate new functionalities. By using layers of polyimide film, adhesives and copper to enable an electrical circuit, flexible PCBs can bend to meet the form factor requirements of an application while maintaining the circuit performance. The flexible PCB section of the rigid-flex board offers design freedom for three dimensional interconnections from two dimensional rigid boards. For example, a flexible PCB connects the rigid boards of a screen and the base panel of a laptop, allowing it to flip open and closed.

Flexible PCBs give engineers design freedom and enable innovation, and will be a crucial component within the next generation of electronics.

DUPONT’S FLEXIBLE PCB SUITE

When it comes to flexible PCB design, DuPont offers a comprehensive suite of circuit materials that can be used across a range of industries. This one-stop-shop includes metal-clad laminates, coverlay, bondply and sheet adhesive, streamlining the design process.

The thickness of and the materials used in flexible PCB layers will depend on the specific application and design requirements. For example, in certain designs engineers may want to use double sided copper clad laminate, where copper is laminated to both sides of the polyimide film in combination with coverlay, bondply and/or sheet adhesives. Other designs may require single-sided copper clad laminate.  

A SOLUTION WITH MANY BENEFITS

Form factor

Design engineers are constantly challenged to pack more into smaller spaces. One way to achieve this is by using flexible PCBs. Flexible PCBs allow engineers to accommodate trends in miniaturization and unique packaging designs that wouldn't be possible otherwise. When design engineers pack more features into electronics, using a rigid board to connect two components is often not possible. However, flexible PCBs’ ability to bend and twist makes it easier to fit into tight spaces without compromising the performance of the board. This flexibility provides a powerful electrical connection in tight spaces ranging from smartphone cameras to NASA’s Mars Exploration Rovers (MER).  

Weight Savings

Flexible PCBs are becoming an increasingly popular choice for designers who want to create lighter and more efficient electronic devices. The substrate (or base) layer of rigid PCBs is made from fiberglass while flexible PCBs use layers of polyimide films that are much thinner and lighter. This weight savings is particularly advantageous for applications where it is essential to maintain functionality without adding any unnecessary weight.

In consumer electronics applications, companies are always striving to make the next version of their device lighter than the last. This puts extra pressure on engineers to develop innovative solutions that meet strict weight requirements of the design while ensuring optimal functionality. Apart from designing within smaller spaces, engineers also must develop lighter designs in every aspect of a product.

Electric vehicle (EV) manufacturers are a prime example of an industry that must reduce the weight of their designs as much as possible to optimize the vehicle’s range. By replacing the battery management system (BMS) wiring harness with a flexible PCB, the weight of the BMS can be reduced by more than 70%. This reduction has a positive impact on the vehicle's range and battery efficiency while increasing the overall sustainability of the design.

Reliability

Flexible PCBs offer high reliability due to their thermal resistance, making them ideal for use in harsh environments. Made with DuPont™ Kapton® polyimide film, our flexible coppler clad laminate (FCCL) materials are suitable for applications in gas and oil, automotive, space, aerospace, and more, as well as in hypersonic applications. With flexible PCBs, design engineers can develop robust solutions that function optimally in extreme conditions.

Low Signal Loss

Flexible PCBs are integral in electronic design due to their low signal loss. As systems transition to 5G and are operating at higher frequencies, signals experience higher losses that can easily be blocked by objects. To increase the efficiency of electronics, more antennas are required, leading to assembly and form factor challenges in small space 5G designs.

For example, one smartphone manufacturer had to increase the coaxial cable from two pieces in the 4G design to five pieces in the 5G design, creating significant design challenges. To overcome this, design engineers used flexible PCBs to reduce the total volume while maintaining low signal loss performance.

A flexible PCB allows for an entire transmission line to be consolidated on one panel circuit board, solving form factor and assembly issues. With the use of flexible PCBs, design engineers can maintain optimal signal integrity while improving performance and reducing the overall size of the design.

FLEXIBILITY ACROSS APPLICATIONS

Flexible PCBs are an ideal solution for a range of electronic applications, offering numerous design and performance benefits. Flexible PCBs’ form factor is critical to joining components of electrical boxes in many aerospace and defense applications. Additionally, the weight savings, broad temperature range and form factor flexibility are ideal for specialized aircraft, spacecraft, missiles and guided munitions.  

Flexible circuits have also supported space exploration with DuPont™ Pyralux® flexible circuits playing a vital role in NASA’s MER. They connect the “brain” of the rover to various electrical components such as the robotic arm, camera, antenna, wheel and sensors. The flexible form factor of flexible circuits allow electrical connections without restricting movement or agility. Additionally, the innovative, lightweight design and high temperature resistance of these circuits played a crucial role in ensuring reliability on the MER during its critical mission.

In the automotive sector, the use of flexible PCBs will be crucial for further development of EVs and advanced driver assistance systems (ADAS). As electrical architectures continue to transition from distributed to zonal and centralized models to meet new demands for data throughput, lightweight design and enhanced signal integrity, flexible PCBs can be used to connect each module together in a seamless manner. This will help to ensure that domain controllers function effectively with other modules while enhancing safety, electrical Integrity and feature capabilities.

Flexible PCBs materials, such as DuPont™ Pyralux® AP copper-clad laminate, are driving innovation in EV charging. With their ability to handle high voltages and flexible form factor, flexible PCBs are a good option as design engineers explore the next generation of rapid charging systems, while also providing lightweighting to support increased battery life.

In medical devices, flexible circuits made from a combination of polyimide films and non-copper metals are becoming increasingly important for various diagnostic equipment. The ability to maintain a connection around a bend also makes flexible PCBs suitable for robotic devices, such as articulating arms.

THE FUTURE OF FLEXIBLE PCBS

DuPont continues to expand its flexible PCB suite and explore innovative solutions including lower loss material, metal alloys, thinner copper and dielectric material, and higher temperature performing circuits. These advancements will enable design engineers across industries to develop more reliable and powerful electronics. As a global innovation leader, DuPont has a robust “toolbox” and capabilities that enable us to address critical challenges faced by our customers today or in the future.

Flexible PCBs are enabling innovation today and will continue to be a valuable design option for future innovations. Improved coverlay material, designed to better enable high-speed data transfer, could also allow flexible PCBs to support high-speed and high-data applications, such as the transition to 6G. Additionally, with improved heat transfer, flexible PCBs could be used in supersonic applications to move heat away from critical components.

Whether incorporating them in today’s innovations or considering them for the next generation of electronics, flexible PCBs offer unparalleled design freedom. From lower weight to heat resistance to electrical performance, flexible PCBs provide benefits that address many common design challenges. And, most importantly, the form factor of these materials offers flexibility to meet the needs of the most demanding and unique applications.