Flexible printed circuit boards have taken the industry by storm. Although they appeared suddenly, it didn’t take long to become extremely popular among the users.
In this article, we are discussing development opportunities and challenges of flexible PCBs. We will speak about the benefits of flex boards, as well as the materials and technologies used during the development process.
Keep reading to upgrade your knowledge, and learn how to handle different challenges effectively!
1、Why Are Flexible PCBs So Popular?
The statistics are clear, and they pinpoint that the production of flexible printed circuit boards increases every day. Intriguingly, they've become popular now, even though flexible circuits were first used in the 1950s. Have you ever thought about what the secret of their popularity is?
A large number of users considers them attractive for the following reasons:
• The ability to bend – the primary benefit is obvious, but it is also the most important.
• Improved reliability – the low number (or elimination) or connectors, solder joints, and other interface connections makes these boards more reliable.
• Thin and light – while ensuring flexibility, the manufacturers also found a way to reduce the size and weight of flexible PCBs. Thanks to that, it is easier to fit them in restricted spaces.
• Suitable for high temperatures – flexible materials can do a better job in dissipating heat than the materials used for rigid boards. Improved thermal management also occurs because of resistance to acids, oils, and UV exposure.
• Affordable cost – the math is simple, and it says that you will pay less for a smaller PCB. Even though many flex boards have high density, the overall cost is usually affordable.
• Durability – it always depends on the materials you choose, but flexible PCBs can be extremely durable. That is why some of them used in medical and military applications.
Image 1: A printed circuit board illustration with “flexible” written over it
2、The Challenges of Designing Flexible PCBs for Wearable Products
Have you ever wondered about the applications that utilize flexible boards? You can see these PCBs throughout various industries ranging from medical to entertainment. But there is one thing that brings all these industries together – wearable products!
It is wearable technology that caused a huge increase in demand for flex PCBs. The chances are you have at least one flexible board around you. It might be in your smartphone or the smartwatch you made yourself.
Printed circuit board designed for a wearable product has to be compact because the wearer shouldn’t be able to notice it. It can affect both design and performance. If you are wearing a smartwatch, you wouldn’t want its PCB to be visible, and that is quite logical.
Boards designed for wearable products often have specific designs. Some applications require the PCBs to be elliptical, and others need them to be round. More often than not, you will encounter a shape you can’t consider “usual.”
That is why the biggest challenge for designers is routing and placement. They need to be creative to ensure that they can place everything properly, even though they have limited space available.
Image 2: Electronic flexible circuitry
3、Materials and Technologies for Flexible PCBs
The performance of a printed circuit board always has a lot to do with the materials used when designing it. That is why identifying new and improving the existing materials is a way to enhance a flexible PCB.
The printed circuit board industry always works on implementing seemingly small innovations. Those may be enhancements in metal foils, or adhesives used improvements in cover layers or any other area.
It is important to note that the manufacturers do not consider the same things when choosing materials for flexible and rigid printed circuit boards. When it comes to flex PCBs, thermal management becomes integral, as well as the capability of bending the material.
Apart from using improved materials, another way to enhance flexible boards is to come up with new technologies for the design and assembly process. The micro via technology is one of the latest major innovations in the industry. At this point, you can’t find a better approach for plating, etching, and connecting.
Although it is a challenge to use the micro via approach, many manufacturers have perfected using it. It is the experience that makes them capable of handling all the challenges related to this part of the production process.
It is vital to note that there is plenty of room to improve flexible boards even further. Many applications are waiting to find a solution related to their specific issues. For example, LED light applications could benefit from finding a material that will have an even better thermal resistance.
Image 3: A flexible printed circuit board held by a human hand
4、Common Issues in Flexible PCB Design
It is not easy to design a flexible board, especially if you have been designing rigid PCBs for years. The lack of practice may lead to issues or errors in the process.
Here is an overview of some usual issues that happen during flexible PCB design:
• Not opening solder mask or overlay openings enough – different steps of the process might change how a flexible board looks. Etching and plating can adjust the shape of the PCB, which is why you should ensure that overlay openings are of suitable width.
• The proximity of solder joints and bending point – it is quite simple – the solder joint should be at the required distance of the bending location. If you put them too close, delamination or broken solder pad may occur.
• Solder pad spacing – the experts, recommend ensuring there is enough space between the pads and the conductive traces adjacent to them, or you may face lamination loss.
Image 4: Steps to solving a problem effectively
5、The Current Challenges in Flex-Rigid PCB Development
Everything started with rigid PCBs, but the industry started moving toward flexibility gradually. Today, you have boards that are completely bendy, but also those that combine the best of the two worlds. Those are the so-called flex-rigid printed circuit boards.
The truth is that these boards are facing similar problems and bring the same benefits as flexible PCBs. For example, they are usually thinner and lighter than rigid boards, and they also can bend. However, their bending capabilities are usually not that impressive, but they can promote the performance of the board in other ways.
As for flex-rigid PCBs, it is vital to choose the materials carefully. Since you will be connecting flexible and rigid layers, it is crucial to ensure they match properly. That is why the developers carefully pick the substrate materials when designing a flex-rigid board.
Those who design a rigid-flex PCB also need to consider other things, such as size, weight, and reliability of the board. But it’s not only about choosing the right materials. It is also vital to ensure that the manufacturer has the necessary equipment to turn the design into reality. You can design the best PCB in the world, but it will be worth little if no one has the technology needed to assemble it.
Currently, the designers are keen on using flexible CCL with or without adhesion as long as flex-rigid boards have up to eight layers. It is also imperative to focus on embedding the capacitor and resistor in the rigid section of the board. That is the best way of avoiding that they will affect the performance of the flexible section. The embedded structure can be a challenge during the design process, and the industry is constantly searching for better solutions in that area.
Image 5: A sign showing two lanes – rigid and flexible
6、What Are the Future Flexible PCB Trends?
Image 6: Electronic flexible PCB
It is always interesting to try and predict the future of a particular industry. While it is obvious that PCBs will continue to be an integral part of electronic products, what will happen with flexible boards?
Here are some predictions that we believe will come true:
• We will keep seeing smaller and thinner, flexible boards.
• The PCBs will be capable of working with improved data-processing speed.
• The boards will be able to achieve even higher density than right now.
• The ability to use the boards in even higher heat will be possible.
7、Why Do You Need a Reliable Flexible PCB Manufacturer?
Image 7: A detail from inside a PCB factory
If you want to ensure the assembly process goes smoothly, you need to find a manufacturer that can meet your flexible PCB requirements.
The first thing to ensure is that the company has the right equipment to assemble your board. Next, you need to check if the staff experienced enough to handle the challenge of manufacturing flexible boards.
OurPCB is a PCB manufacturer with years of experience in designing simple and complex printed circuit boards. The company has modern equipment and skillful engineers that have worked on hundreds of flexible PCB assembly projects.
The company guarantees:
• Following your instructions and desires to the smallest detail.
• Choose the best material for your application and budget.
• Assemble and deliver the board within the specified time frame.
• Provide support throughout the process and answer all your questions at any time.
If you need a flexible board, do not hesitate to contact OurPCB. You will receive a quote in a matter of hours, and working with the company will be a pleasant experience from the first moment!
The flexible PCBs have reached a high level of reliability and performance, and it is impressive that they have much more room to improve.
However, those looking for flex boards should be aware that there are many challenges on the road to designing and assembling a reliable PCB. That is why it is vital to look for a manufacturer that has adequate equipment and engineers capable of responding to the challenges of assembling the board your application needs!