PCB Assembly

The Ultimate Guide to Flex PCB Assembly Process: Everything You Need to Know

Flexible PCB Assembly

PCBs may look like a small component present inside electric and electronic appliances but the world of PCBs is quite vast. Printed Circuit Boards come in different types depending upon the material used in their manufacturing and the number of layers present in the board. They can also be customised in various shapes and sizes as per the gadget’s requirement. Flex PCB is one special type of circuit board that can be bent and twisted and is widely used in many areas, such as consumer electronics, medical electronics, industrial devices, portable devices, robotics, aerospace applications., etc. Therefore, it is necessary to understand flex PCB and flex PCB assembly before manufacturing any device.

Viasion Technology Co. Ltd. is an established manufacturer of PCB boards in China that offers a one-stop solution for all your PCB-related needs, including flex PCB and flex PCB assembly. So, with our experience and expertise, here is a detailed guide describing the Flex PCB assembly process and everything related you need to know. So, why wait, keep reading to explore!

Flex PCB with Components

Flex PCB: An Introduction

Before starting with the Flex PCB Assembly process, it is crucial that you understand the basics of a flex PCB board, i.e. what a flex PCB is and how it is different from other types of PCBs. Printed Circuit Boards come in three major types depending upon the material they are made of. This includes rigid, flex and flex-rigid PCBs. As the name suggests, rigid PCBs are made of 100% inflexible material. They help provide strength, support and structure to the device. On the other hand, flex and rigid-flex PCBs are flexible i.e. they can bend to some extent and prove to be of immense use in small-in-size and light-weight devices. While flex and rigid-flex PCBs are usually pricier than traditionally used rigid PCBs, the former may help reduce the overall cost of the device in other ways. Consult the experts at Viasion to find the right PCB solutions in your budget today!

Flex PCB boards are usually made of polyimide, a type of polyester film, that provides the characteristic flexibility to this type of PCB. This base material is an ideal substrate because of its mechanical flexibility, high chemical stability and heat resistance. Continue reading to learn about the flex PCB assembly process.

Properties of Flex PCBs

Besides flexibility, flex PCBs have many more properties unique to them. Flex PCBs usually have relatively low circuit density because they are used for some module connections only. The components used in a flex PCB assembly must be of superior quality and must meet the specific requirements of the device. This is because such PCBs are generally used in devices with high accuracy. Therefore, the assembly must be manufactured with utmost precision so that it has high reliability and strong solder bonds. The flex PCB assembly process is a costlier affair as compared to that of rigid PCBs. The base material, equipment requirements and the process employed increase the cost of flex PCBs. However, one must note that a well-designed flex PCB can reduce the overall price in other ways. The advantages that a flex PCB brings to the table are immensely beneficial and turn out to be quite cost-effective in the long run.

Consult the team at Viasion Technology Co. Ltd. to make the most out of your budget. Our experts help you tweak your design in a way that proves to be the most economical. Our advanced technologies, state-of-the-art testing facilities, precise and reliable procedures, and experienced staff ensure the delivery of the perfect PCBs at the best prices.

Benefits of Flex PCBs over Rigid PCBs

Flex PCBs are in huge demand lately due to their flexible and lightweight structure. Electronics and devices that have a shape-changing or movable functionality, require flexible internal components, including PCBs. Wearables, like smartwatches and health trackers, are one of the most common examples of devices that employ flex PCBs. The dynamic nature, thinner body, enhanced heat dissipation and improved signal integrity are some other features that make flex PCBs superior to rigid PCBs.

In the PCB assembly stage, the flex PCB assembly process is quite similar to the rigid PCB assembly process, but some tools and supportive tools may be needed to keep the flex PCB flat and stiff.

Applications of Flex PCBs

The demand for flex PCBs is growing rapidly. Their multiple benefits and dynamic nature make them one of the most integral components of futuristic devices. Besides wearables, flex PCBs are widely used in the automotive and healthcare industries. Movable subsystems like the mirrors, doors and seats in hybrid cars utilise the benefits of flex PCBs. With the emergence of implantable health monitoring devices, flex PCBs entered the healthcare and medical industry. Internet of Things (IoT) also utilises these tiny multi-utility components as the sensor-enabled applications need dynamic circuits. No matter what your requirements may be, contact Viasion for custom-designed PCB-related services.

Flex PCB Assembly

The Detailed Flex PCB Assembly Process

While flex PCBs work on the same principle as rigid PCBs, their fabrication and assembly processes are somehow different due to their unique structure and functionality. So, without further ado, let’s get started on with the flex PCB assembly process.

Designing the flex PCB board:

Before anything else, it is crucial to design the flex PCB with utmost detail. CAD (computer-aided design) software programs are usually used for this purpose. In addition to such software, experienced designers should also be on board to keep monitoring the design at every level. This ensures that it is the best suited as per the project requirements. The number of layers in the PCB, thickness, component placement, flexibility requirement, and all other such details should be laid down well before starting the manufacturing process. This helps exponentially reduce the chances of error and increases the performance of the final product.

Fabrication of the flex PCB board:

Before beginning with the flex PCB assembly process, here is a brief overview of the fabrication process. Similar to the fabrication of a rigid PCB, this process also begins with the preparation of a substrate. However, the material used is different in this case. A flexible material, like polyimide, is used for the substrate preparation of a flex PCB. The further steps of copper plating and etching are similar to that of a rigid PCB. Solder masking and final testing of the PCB board also take place in the usual manner. The major difference lies in the material used for the preparation of the PCB board.

Component Sourcing:

As you already know by now the process of PCB assembly involves the mounting of required components on the PCB bare board. No matter how flawless the PCB board design is or how precisely the PCB fabrication process is carried out, if the components are of poor quality, the entire circuit may fail. A lot of uncertified, poor-quality components are available in the market. While these may seem pocket-friendly options initially, they may end up costing you a lot by negatively affecting the performance of the final product. Therefore, make sure you select trusted suppliers only for component sourcing. Do not forget to check the supplier’s certifications, clientele and testimonials before making any purchase.

Flex PCB Assembly Process:

The mounting of the components on the flex PCB bare board or the flex PCB assembly process may be carried out by one of the two techniques – SMT or Through Hole. As the name suggests, SMT or Surface Mount Technology is the process where all the components are directly mounted on the surface of the PCB bare board. This technique is usually preferred in cases where small-in-size components are to be assembled. For larger components, a combination of the Through-hole technology and manual assembly is preferred. There are various methods to carry out component attachment. For example, pressure-sensitive adhesives, mechanical fasteners, conductive epoxy and solder joints. All these methods have their own applications. PCB assembly teams select the right component attachment method depending on the type of component and the requirements of the final flex PCB.

Testing and Inspection:

No PCB fabrication and assembly process is complete without several rounds of testing and inspection. Both human-led and machine-automated testing rounds are carried out at Viasion to ensure that only the best, error-free PCB assembly is produced ultimately. AOI or automatic optical inspection, is one of the techniques that helps us deliver error-free PCBs always. Contact our experts today if you are looking for a fool-proof flex PCB assembly process and other PCB-related services.

Factors Designers Must Consider While Working with Flex PCBs

As you have already understood, the design of a flex PCB plays a significant role in its performance, quality and durability. Since flex PCBs are more expensive than rigid PCBs, they must be designed with further care and precision to avoid the cost of redoing the entire fabrication and assembly process. So, there are a few factors that the designers should always take into consideration while working on a Flex PCB circuit layout.

Firstly, the selection of the PCB substrate material should be done very carefully. Fabricators must consider the board stiffness and flexibility requirements to select the right raw materials. Additionally, one should keep in mind that while making the board flexible, its durability should not be compromised.

Bend radius is the next aspect that designers should make considerations for. By using optimal materials and stack up, various bend radii can be achieved. This further helps determine the durability and flexibility of the board.

Next, the designers should keep in mind the component requirements. This is also required to determine the right assembly technique for the project. Attachment methods should also be chosen carefully keeping in mind their pros and cons.

Other factors to take into consideration include high-frequency layout and thermal management. Viasion Technology Co. Ltd. holds unmatched expertise in the category of designing, fabrication and flex PCB assembly processes. Get in touch today to get a quote.


Flex PCBs have immense advantages and applications. They can increase the functionality of a device by multiple folds. However, their fabrication is not a child’s play. Their performance is directly proportional to the skills of the designer and fabricator. Therefore, avoid taking any chances when it comes to outsourcing the flex PCB assembly process of your project and trust Viasion!

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