What are FLEX PCBs?

What is a FLEX PCB and how does it improve product design today? A flexible printed circuit board, also called a flexible printed circuit board (FPC), has different properties than a rigid printed circuit board due to the different type of base material, which expands the number of applications where it can be used.

The biggest advantage is the flexibility of the base materials, and it is repeatable. A flexible board also resists vibration and general movement much better. Thanks to the miniaturized design, FLEX PCBs can reduce the weight of an electronic assembly by up to 75 %.

Another key feature comes from minimizing connection points, eliminating interconnect defects that are common in solder joints. They are significantly lighter than rigid circuit boards and can fit unusual shapes beyond what is typical for more rigid designs. They also save the work of wiring and testing wiring harnesses, especially for complex assemblies typically found in the aerospace industry. 

The increasing demands for performance and precision, along with the continuous push for miniaturization and portability of electronics, including the integration of electronics into almost all human activities, highlights the importance of having materials that can solve almost contradictory requirements.

FLEX PCBS

A flex board is a flexible printed circuit and component assembly that uses a flexible base material instead of fiberglass and resin. This definition, while basic, illustrates everything you would expect from a flexible printed circuit board – it is made of flexible film.

The general division corresponds to the basic characteristic, i.e. the number of bends of the flexible board. The boards are therefore divided into:

• Stable (they usually bend only once during installation),
• Flexible (up to twenty bending cycles),
• Dynamic (here, repeated bending of the flexible joint is expected).

However, Flex PCBs have become much more complex over the years as they have been applied in various industries. Below we will review some of the most common types of flexible PCBs in use today.

Single-sided flexible circuits

 The most common and simplest FLEX PCB on the market. They contain a single conductor layer on a flexible dielectric film and are printed on one side only. They are the most affordable FLEX PCBs on the market and are relatively easy to manufacture. These printed connections can be found in most calculators due to their simplicity and light weight.

Double-sided flexible circuits

By printing on both sides of the dielectric film coupled with plated through-holes, double-sided flexible PCBs offer improved power handling capabilities and circuit density. Although popular for their increased performance, they are somewhat more expensive to manufacture than single-sided FLEX PCBs.

Multilayer flexible circuits

Flexible circuits with three or more layers of conductors. Due to the complexity of their construction, multilayer FLEX PCBs are the most expensive. They are often used in aerospace and military applications that can justify the cost and capabilities of such a flexible circuit.

Rigid-Flex Circuits

A hybrid between standard flexible circuits and rigid PCBs, rigid-flex PCBs contain a network of rigid circuit boards that typically contain components with flexible substrates that connect them together. They are commonly found in commercial electronics such as laptops and smart devices, as well as in the military sector, which depends on their reliability, strength and flexibility to ensure consistent performance.

Using of FLEX PCB

Flexible printed circuit boards are suitable for various applications where rigid printed circuit boards cannot be placed

• Commercial Electronics – One third of the sales volume of flexible printed circuit boards comes from computing – everything from printers, scanners, smart devices and more. As the market pushes for smaller and more advanced handheld technologies, flexible printed circuit boards are essential for high computing power without weight constraints.

• Automotive – The second largest sector for FLEX PCBs is vehicles. The average car looks significantly different than it did at the beginning of the decade, and their hardware has advanced over time. As cars begin to include more sensors and electronics for everything from air conditioning and GPS software to dashboards and rear cameras, flexible PCBs are enabling both space allocation and thermal performance.

• Aerospace – With their remarkable ability to handle the stresses of extreme temperatures and vibrations, FLEX PCBs are uniquely suited for aerospace applications such as satellites. They can also take on unusual shapes that are well suited for spacecraft and replace connectors that are more prone to failure.

• Medical Devices – As medical technology evolves, wearable devices have become a key element over the past few decades. Flexible printed circuit boards offer greater durability because they can mirror product shapes. Hearing aids, vital sensors and electronic motors use flexible printed circuit boards for high performance that can withstand wear and tear.

Advantages and negatives of FLEX PCB

Flexible printed circuit boards have a number of advantages over a rigid printed circuit board. This makes them common in consumer electronics, but it brings some disadvantages. As a result, both rigid and flexible PCBs have their place and are often used in conjunction with each other in rigid-flex circuits.

Advantages

• Flexibility allows for widespread use in a variety of products across industries
• Less risk of wire connection failure increases overall reliability
• Reduced size and weight compared to rigid boards
• Good temperature range makes FLEX PCBs suitable for harsher environments
• High circuit density
• Easier installation and commissioning of equipment

Disadvantages

• Higher material cost than solid printed circuit boards
• Complex assembly process
• Sensitive to scratches and damage when unprotected
• Challenging to repair