What is Flexible PCB

What types of electronic devices do you use? They could be a smartphone, computers, laptop, tablets, cameras and some other electronic gadgets. Almost all these devices used different types of Printed Circuits Boards. Flexible PCB is one of the most prominent types of printed circuit boards.

What is Flexible PCB?

Flexible PCB also referred to as the flex circuit, which is an incredible addition in electronic components. It is a special type of PCB that has the capability of twisting and folding. Its bending ability depends on your requirements and needs.

Flex Printed Circuits contain a thin insulating film of polymer with conductive circuit patterns. They are typically thin, lightweight and small in size. Due to all such capabilities, they are rapidly substituting the conventional connective boards. It was the main purpose to design these circuit boards.

Different Types of Flex circuit boards

There are 4 major types of flexible circuit boards available in the market. Here are as follows:

  1. Single-Sided Flexible Circuits

It is one of the most common designs of circuits. There are several reasons behind its popularity. For example, they are the least expensive. They contain high effective variants for different flex applications.

The construction material for single-sided circuitry includes conductive inks. Another manufacture material is etching metal. The ink and etched metals produce the desired circuit patterns on the surface of flexible boards.

  1. Double-Sided Flexible Circuits

It is the second most common design for flex printed circuits. It is useful for all those applications that require high-density interconnection of circuits. Unlink single-sided circuitry, it features two metal layers connected with a plated-through hole. A standard double-sided circuit contains successive layers of adhesive and cover film on both sides of a base film.

  1. Multilayer Flex Printed Circuits

Likewise, the double-sided circuit, it is useful for high density requiring applications. It contains some properties having resemblance with rigid circuits. However, due to its multilayer structure, it contains a sophisticated design. It helps to resolve specific electrical and electronic issues.

A multilayer circuit is a combination of several single or double-sided flex circuits. Different individual circuits have multiple insulating and conductive layers between each interconnected device. Another possibility is to create a multilayer circuit. Connect several circuit boards with an individual central point for this purpose.

  1. Rigid-Flex Printed Circuits

As the name suggests, it is a hybrid configuration that is a combination of both rigid and flexible printed circuit boards. The rigid portion supports all components and reinforces connectors. Meanwhile, the flexible section provides the whole connectivity for different rigid sections.
Initially, the way to combine both rigid and flexible PCB founded in military design applications. The sole purpose to develop hybrid circuit is to produce a reliable. It helps to create a lightweight interconnection structure.
It also includes a higher degree of engineering complexity as rigid-flex printed circuits. A standard circuit can depend on integral controlled-impedance flexible wires. The wires link different rigid portions of the device and connect them to assemble the circuit body.

The thickness of Flexible PCB

thickness of flexible pcb

The thickness of the flexible PCB varies depends on the material and types of the flexible circuit board. For example, a maximum 1 layer copper board thickness is 8.5 mm and the minimum thickness is 2.5 mm. The maximum and minimum board thickness of a 2 layers coper board is 12.6 and 4.7 respectively.

Different features of flexible PCB

Here are some important features of flex circuit boards:

  • Flex circuits have short assembly time because they are not brittle. So engineers work fast. Moreover, all lines have pre-configuration. So it saves the connection work as well.
  • It reduces the weight of the products that make them easy to carry.
  • Flexibility makes it reliable and durable.
  • Polyamide stiffeners improve the strength of the circuit. It is because it strengthens the connection areas of the board.

The Applications of Flexible PCB Board

When it comes to reliability, maximum adaptability and flexibility, flex PCB is extremely useful. If a circuit requires folding in the assembly process, it means you need a flexible PCB. This circuit board is an ideal choice when it is impossible to avoid warping and flexing.

In recent years, flexible circuit technology has become very advanced. So you can use it in more compact and limiting situations. The demand for the flexible printed circuit board is increasing day by day due to its lots of usage.

Here are some most important applications of flexible circuit boards.

Flexible pcb application

  1. Flexible PCBs in Computer Electronics

Several main components of the computer rely on flex circuitry for proper operation. For example, to keep up with the high speeds, the components in hard drives require to be flexible. While utilizing hard drives for a long time span, it can get hot. It means circuit boards should be capable to withstand high temperatures. To maintain the proper working of hard drive, credit goes to circuit boards.

Likewise computers, you can find flexible circuit boards in other electronic gadgets. For example, gaming systems, television, and printers.

  1. Flex Printed Boards in Automotive Electronics

Automobiles are the most significant consumers of flexible circuits. The majority of automotive electronic hardware uses flexible circuitry. For example, engine management units or computers (EMUs) and airbag controllers use Flexible PCBs. Dash systems, anti-lock braking systems, and instrument panels are some other useful applications.

Flexible boards don’t usually take much space so you can fit them in any irregular shape. So it is helpful for engineers to use the flex board instead of using bulky cable ties or connectors. Flex circuits are lightweight and smaller electronic components. All companies want to build lightweight vehicles. So by utilizing lightweight flexible circuit boards can make a difference.

  1. Flexible PCBs in the Medical Field

Flexible printed circuit boards have significant importance in different medical and pharmaceutical applications. It is because sometimes circuits have to face different extreme conditions inside the human body.

The most popular application of flex circuits is a swallowable camera, commonly known as PillCam. This camera helps the doctor or medical professionals to have an accurate view of the human body. So it is helpful for ailments. The pills need to be enormously small to swallow.

It helps to create realistic prosthetic limbs. Researchers have introduced a technique to print circuitry onto flexible and organic material. This material is extremely smaller than typical flex printed boards so it can move naturally without damaging.

Commonly used material of flex PCB

These electronic devices consist of different. Here are four major materials:

  • The substrate and some other cover overlay materials
  • Conductor materials
  • Insulators
  • Adhesives

Before you choose any material, you need to consider the following points:

  • Capacitance
  • Thermal conductivity
  • Degree of flexibility
  • Current conductivity and tolerance
  • Chemical and mechanical resistivity

Substrate and Cover Overlay Materials

These are very helpful to cover the conductor material. It is because copper is the best conductor but it oxidizes easy. So exposed copper surface requires a covering material to prevent oxidation. Therefore, the substrate and overlay material is handy in this situation. Gold and solder are good overlay materials.

Conductor Materials

Circuit board is all about dealing with electricity. Therefore, a conductive material is a basic material for FPCB. Copper has extensive usage in circuit boards because it is cost-effective. Some other useful conductive material is:

  • Silver Ink
  • Constantan
  • Carbon
  • Aluminum
  • Inconel

Insulators

An insulator is a substance that prevents heat transmission. So Flexible PCB manufacturers use it between different boards layer to prevent the emission of heat. It is the most important part of any circuit board. In fact, it enhances the durability of circuit boards. Here are some suitable insulators:

  • Polyethylene
  • Solder mask
  • Polyimide
  • Flexible solder mask

Adhesives

It is another most essential material of all types of circuit boards. It firmly attaches the conductor metal onto the substrate. You will have to be very choosy while selecting adhesive materials.

Mostly, manufacturers choose adhesives as per the requirements and preferences of the customers. There are different adhesives material available for circuit boards that include:

  • Epoxy
  • Pressure Sensitive Adhesives
  • Acrylic

Pros and cons of flexible PCBs

Likewise all other types of printed circuit boards, It also contains different pros and cons. Here are some pros and cons for flex PCB.

Advantages of Flexible PCBs

There are several pros of flex circuit boards as compared to conventional electrical connections. Here are some pros of flex-circuits:

  • It completely eliminates mechanical connections.
  • Having the capability to produce a strong and reliable signal.
  • It tolerates a huge temperature.
  • Due to its flexibility, it is not breakable easily that makes it reliable.
  • You can easily bend and fold it, resulting in a smaller size.
  • It covers a very small area due to its smaller size.
  • Flex circuits are lightweight.

Disadvantages of flex circuit boards

There are a few disadvantages to this board. Here are some cons of flex-circuits:

  • Although it is durable, the initial cost of this circuit board is quite high.
  • It is extremely difficult to make any change in this circuit board after finalizing it.
  • Its rework and soldering require a professional team of engineers.

When to use flexible Printed Circuit Board?

Flexible printed circuit boards consist of polyimide or something similar. They can tolerate extreme temperatures even between 200 and 400C. So it is important to use a flex circuit when developing a high temperature and density applications. For example, for borehole measurements in different gas and oil industries, they have good usage.

As they can withstand heats, they have also good resistance for chemicals, radiation and UV exposure. So it is extremely useful for all such applications dealing with chemicals and so on.

Why not make all circuit boards flexible?

Flexible circuit boards have many benefits and have priority in several factors from other PCB types. However, in spite of all benefits, it still can’t replace rigid circuit boards entirely. Cost is one of the main obstacles in the way of flexible PCBs.

Many companies use flexible circuitry when required. Otherwise, they use rigid for manufacturing and assembling to keep the cost down. MOKO Technology produces different types of printed circuit boards at an affordable price.

All applications require a reliable and durable PCB. So MOKO Technology is one of the best sites to purchase circuit boards.

 

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