A flexible printed circuit board (FPC or flex PCB) is a type of PCB that is designed to be flexible, allowing it to be bent, folded, or twisted. A FPC features a combination of several printed circuits as well as components that are positioned on a flexible substrate. Typically made from a polyimide film material, which guarantees high flexibility and thermal stability. Thanks to their miniaturized design that increases innovations and applications in main electronics sectors, such as consumer, automotive, medical devices, wearables, telecommunications, and aerospace.
A flexible circuit board requires less space and is more reliable. You can bend it up to 360 degrees, most of which are designed for 500 million flex cycles. The technology has been used for interconnecting electronic devices since the 1950s in one form or another. It is now one of the most important interconnection technologies in use for the manufacture of many of today's most advanced electronic products.
The single-sided flexible circuit board is the most basic among the types of flex PCBs. It consists of a substrate layer, conductive copper layer, overlay, and silkscreen.
It only has a single layer of flexible polyimide or polymer film, and the conductive copper layer is only accessible on one side of the PCB. As a result, the other side can be used to put various electronic components. Its simple design makes it suitable for various applications and more affordable. Hence, it is also the main reason why it is the most widely used flex circuit.
Unlike the single-sided flex circuit, a double-sided flexible circuit board allows the creation of trace patterns on both the top and bottom copper layers. You can connect each side using the copper-plated through-holes wherever you want. It also permits electrical connections via the layers.
One advantage of the double-sided flexible circuit board is that it can be used in more complex electronic products to achieve more functions. Manufacturers have found it useful in making dashboard components, lighting, and other industrial areas.
Several copper layers in multi-layered flexible PCB boards are joined together by plated through holes, similar to those in double-sided boards. Multilayered flexible PCBs contain a number of individual copper layers and dielectric layers.
One of the benefits of using a multi-layered flexible circuit board is freedom in design with multiple functions. Manufacturers can use it for those with complex design requirements. It is utilized to make components for mobile phones, satellites, cameras, and hearing aids.
For now, the services at JLCPCB fabrication manufacturing unit are capable of designing up to 2-layer Flex PCB with high precision and quality control.
The question of “How much can you bend a PCB?” may seem like an easy one to answer, but it is not as simple as that. Bending a PCB can compromise the strength of the circuit board, copper tracks, and solder pads. The maximum bend radius for a PCB depends on the design material and thickness of the PCB. A 0.4mm is enough to bend a PCB 90 degrees. Some PCBs can be bent up to 20 times, but it is best not to bend the circuit board more than once. The formula for the maximum bending angle of a PCB based on the thickness of the substrate is given here:
For example, performing a 90-degree bend increases the chance of circuit damage. Lastly, make sure the bending radius does not exceed one millimeter. You can bend PCBs up to 180 degrees with a flex material. However, if you try to bend it past its recommended limits, you could end up destroying your circuit board.
The three Flexible PCBs include; single-layer, double, and multi-layer circuits. The major element of a single-layer Flex PCB are:
A stiffener in a flexible printed circuit (FPC) is a rigid layer, typically made of materials like polyimide or FR4, added to specific areas of the flexible PCB. It provides mechanical support and reinforcement to prevent bending or flexing in delicate regions, such as connector areas or mounting points. Stiffeners improve durability, enhance reliability in high-stress areas, and help maintain the overall form factor of the FPC in critical sections.
Flexible circuit boards offer many benefits, which is why they have become a popular choice among electronics product manufacturers regarding PCBs. Here are some key advantages of using flex circuits in your electronics components:
Although flexible circuit boards offer numerous advantages in modern electronics, there are some concerns to consider:
Flexible PCBs are used in various sectors due to their versatility, reliability, and space-saving features:
Flexible PCBs, while offering advantages like design versatility and space savings, aren't ideal for every application due to their higher cost compared to traditional rigid PCBs. They are also more complex to manufacture and can be prone to damage if not handled carefully. Flexible PCBs may not be necessary for simpler designs that don't require bending or folding, making rigid PCBs a more economical and durable choice in such cases. Additionally, flex circuits often have limitations in terms of high-power handling and mechanical stability.
Undoubtedly, flexible circuit boards have become essential in making products that are more powerful but portable in many industries. Other conventional options cannot compare with the flexibility and accuracy of flex circuits. Components for aircraft, medical devices, cars, and even those used in daily life rely on flexible circuit boards to become lightweight without compromising capabilities. As technology improves and products continue to innovate, flex PCBs will remain the primary choice in making circuit boards for products created by various industries.
