When to use Flex PCBs vs. Rigid-Flex PCBs.

The significant change in the modern electronic industry was made after the invention of printed circuit boards (PCBs) by Paul Eisler. Eisler wanted to eliminate the traditional printed wires on the boards and mounted elements on the boards. PCB is designed to support and connect electrical components and mechanically fasten them up. Since then the PCB industry has undergone continuous changes to meet the rising demands and needs of the consumers. Hence, many different PCBs were manufactured to fulfill the requirements of modern electronic devices. The most common types are single-layered PCBs, double-layered PCBs, rigid PCBs, flexible PCBs, and rigid-flex PCBs. In this article, we will discuss the two most popular PCBs, flex PCBs, and rigid-flex PCBs and when should we use them?
The demand for both flex and rigid-flex PCBs has witnessed exponential growth in the last few decades around the globe. Each of them has its unique features and properties and users need to buy one that matches their needs and requirements. Although consumers use both flex and rigid-flex PCBs in diverse fields like industrial machines, medical devices, automotive and aerospace industry, and military equipment, yet there is a rising trend for rigid-flex PCBs and many believe that it is better quality, cost-effective, reliable and long-lasting than a flexible PCB.
However, one cannot disregard the efficacy of flexible PCBs, and all your queries pertaining to when to use either of them will be removed after reading this article.
What are Rigid-flex PCBs

Rigid-flex PCBs, as the name implies, contains the characteristics of both rigid and flexible PCBs.  They are multi-layered and comprises of flexible circuits joined with rigid boards and are, therefore, designed for headboard as well as flexible circuits. The ends of rigid-flex PCBs are made of a flexible material to help fit wrap and fit into any electronic device. That is why they can be flexed, bent, and folded according to the area it needs to support. These PCBs are thin and light and ideal for fine technology for every almost circuit design. They can withstand high temperature, pressure, shocks, vibrations, and tough industrial and commercial conditions better than flexible PCBs.
However, it doesn?t nullify the importance of flexible PCBs.
What are Flexible PCBs

Flexible PCBs have base material made up of a flexible material that is movable and bendable just like plastic. This flexible material can be added to one or both sides of the PCB. They can offer 360-degree bendability and can be twisted or folded to fit into any final product. Flexible PCBs are made up of single, double, or multi-layers format depending on the needs of the users. The fabrication cost is more as they are printed on a flexible material. Flexible PCBs are preferred because they are typically made up of polyamide that dissipates heat without affecting the performance of the product. They prove to be a cost-effective solution for many industries in the long term as they can outlast traditional PCBs.
When to use flexible PCBs
The flexible PCBs should be used when the high adaptability is needed without compromising on performance. If the product is designed in a way that requires some bending to be made during PCB assembly or if the wrapping is necessary, then flexible PCB is the one you are looking for. That is why there are a lot of applications in which flexible PCBs are employed to increase efficiency and working performance.  Some of these applications are discussed below where the majority of consumers use flex PCBs.
1. Use Flexible PCBs in Automotive Electronics
The era of modern automobiles is highly dependent on flexible printed circuits boards including an anti-lock braking system, airbag controllers, dash system and instrumental panels, and other parts. They are used because it can be fit into any small part as they provide flexibility to engineer. These circuits are smart and portable without the need for bulky cable connectors and wires. It is also light weighted and smaller than conventional parts. They are designed in a way that it can withstand extreme conditions as cars are exposed to extend heat and cold and experience vibration during use.  That is why you need to use a flexible PCB for automobile components.
2. Use Flexible PCBs in Aerospace Components
Flexible PCBs are used in different parts of the aviation industry to read critical operational data during flight. It is used in holographic waveguide helmet-mounted display providing high-resolution 3D images to make it effective for avionics. You can use these PCBs where higher standards and efficiency are required for the aerospace industry.
3. Flexible PCBs in computer electronics
Computer operations rely on flexible circuit boards as they keep up the high speed and store all of the data in a small place. They are resistant to heat and so the extreme heat emitted from the computer doesn't harm it. They allow the computer to last long. Flexible PCBs are also used in televisions, games, microwaves, and printers.
4. Flexible PCBs are Used in Smartphones
Smartphones are the need and obsession of the young generation and hence, they need to be really smart, light-weighted, and portable to use. So, a single thin layered flexible PCB is used to connect up with all the components to reduce the size and weight of smartphones. This PCB is fit in a very small place since mobile devices are not big. They are resistant to heat and environment so they keep out smartphones safe. They are now made waterproof and the phone is safe even if it is in contact with a liquid. Waterproof phones are now part of modern technology and it is made possible because of flex PCBs.
5. Flexible PCBs Use in the Medical Field
The flexible PCBs are extensively used in medical and pharmaceutical appliances. The circuits are employed in internal miniature components of swallowable pill cameras and can easily survive in temperature changes in the human body. They fit in an extraordinary small pill, owing to 360-degree transformation, that goes inside the patient's body. Moreover, a new glass hearing device is launched that uses flexible PCBs in which photoreceptors in which microactuators are placed inside the ear to get in contact with the eardrum. Then, the digital signals are sent to the ear causing the eardrum to vibrate and doctors are able to analyze the root problem.
6. Flexible PCBs in Latest Applications
It would not be wrong to say that the introduction of flex PCBs has revolutionized many aspects of modern electronic designs. Countless electronic products manufactured recently are largely dependent on flexible printed circuits boards that must process electrical signals quickly, perform excellently in extreme temperature, manage heat and power distribution, reduce dangerous crashes, and especially fulfill the need for a miniaturized design which is a prerequisite for the majority of modern and smart devices.
Similarly, the advanced flexible circuits have made advancements in automotive, medical, industrial, consumer, military products. The latest developments include medical quick diagnose devices, rapid scan devices. Downhole oil and measurement equipment that process information extracted thousands of feet below the earth's surface. Mini cameras have been launched that is used in medical purpose to scan the human body.
Hence, we can use multilayer PCBs when we need flexibility in design, reliability, reduced weight, and size and all of the above applications use these features to boost functional capacity. If you are wondering why such complex and sophisticated applications use flex PCBs then you are not alone. That is why I will expound various advantages of flexible PCBs in the next paragraph.
Advantages of flexible circuit boards
Numerous advantages answer the question: when to use flexible PCBs?  It is specifically designed to save the room and improve flexibility. It reduces the complicated processes used in technologies and has become the solution for miniaturizing and improving the electronic products. They are best for the products that require an electrical signal in a small package providing excellent electric performance. It keeps operating perfectly no matter how high temperature it is. The foremost advantages of flex PCBs are:
1. Reduced space
2. Reduced weight
3. Easy installment
4. Better service
5. Increase reliability
6. Eliminate connectors
7. High-speed performance
8. Reduce assembly cost
9. Improve aesthetics
So, if you are looking for above mentioned features in the final product, go for flex PCBs.
When to Use Rigid-Flex PCBs
As mentioned earlier, Rigid-flex PCBs are almost similar to flexible PCBs with the only exception that they have both rigid and flexible layers stacked over each other. These PCBs should be used when the industries require both static and flexible properties on board. In other words, they offer a significant advantage over flex PCBs. Their use has been increasing day by day and in the last decade or so, the numbers are through the roof.
The consumers use rigid-flex PCBs when durability and precision dominate the price consideration of the PCBs; when you require the highest levels of workability and performance; when you cannot compromise on adaptability; when you need compactness and rigidity while providing a certain amount of motion. Because of their design versatility, they are a bit expensive than flexible PCBs but with the multitude of high-density functions they offer, users can easily make up for every penny they spent. These remarkable properties make them an ideal solution for many applications and prove to be a cost-effective solution for complex industries. The following paragraphs will discuss the applications of rigid-flex PCBs in various fields of electronics.
1. Rigid-flex PCBs in Industrial Applications
We use rigid-flex PCBs in industrial equipment to work consistently under stressful conditions. Their ability to withstand high temperature, pressure and tough environmental disruptions makes them a perfect choice for complex industrial processes. Moreover, they can be fixed flexibly according to the machine design as their ends are flexible to wrap around devices.
They are used in various areas of the industrial sector like radio frequency communication technology and power distribution control circuits. Rigid-flex PCB allows the sensor to be small and thin that opens up the opportunity for these sensors to be used in industrial space. Rigid-flex PCBs add reliability and disability to the control circuit. These PCBs allow the industrial machines to remain operational for longer. It contains a flexible design that enables the manufacturers to use innovative solutions for better performance of the equipment.
You cannot achieve these advantages using a traditional rigid or flexible PCB.
2. Rigid-flex PCBs in eCommerce
The rigid-flex PCBs are considered ideal for many industries with a growing need for advanced and portable tools. With the trend of online retail businesses, these PCBs have become the tool for scanning, tracking, and reporting the shipping process. It helps these businesses to send the goods through proper procedures to reach the hand of customers. The portable device is launched for the workers to track and record the products to be used in the warehouse. That is why more and more eCommerce industries are embracing rigid-flex technology.
3. We Use Rigid-flex PCBs in Smart and Modern Medical Wearables
The devices that have captured the medical market recently are medical wearables that include fitness trackers, smartwatches, smart clothes, rings, and jewelry. It has made it convenient for doctors to remain informed about their patients. They can monitor heart rate and breathing patterns. These wearables are made of rigid-flex PCBs. The rigid layers allow the devices to keep going on demanding situations. Simply put, the evolution of the latest medical equipment compels us to use rigid-flex PCBs.
4. Rigid-flex PCBs Applications in Daily Lives
The usage of rigid-flex PCBs apart from commercial and industrial applications can range into many smart electronic devices. Smart innovations are made by engineers to satisfy the luxurious need of customers. People nowadays demand portable, light-weighted products, and enhanced performance. Examples are cellphones, digital cameras, computer servers, automotive, telecommunications, medical equipment, wearables, and much more.
Needless to say, we can use rigid-flex PCBs is almost every electronic device, from the simplest to the most complex and sophisticated ones.
Closing Remarks
To conclude, both the flex and rigid-flex PCBs have their unique features and purposes. This article has discussed the foremost characteristics of both types of PCBs and when to use them. We also concluded that the use of rigid-flex PCBs is increasing significantly and they may offer sufficient advantages over flexible PCBs, but it really depends on the choice and needs of the users.
However, it is safe to say that the remarkable technological advancements in the field of electronics and the introduction of even smaller and multi-functional electronic devices have made life much easier and convenient.


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