Are vias in flexible circuits reliable

What is a flexible circuit board?

What types of electronic devices do you use? They could be a smartphone, computer, laptop, tablet, camera, and some other electronic device. Almost all of these devices used different types of circuit boards. Flexible printed circuit boards are one of the most popular types of printed circuit boards.

What is a flexible circuit board?

Flexible circuit board is also known as flex circuit, which is an incredible addition to electronic components. It is a special type of circuit board that can rotate and fold. Flexibility depends on your requirements and needs.

Flex Printed Circuits contain a thin polymer insulating film with conductive circuit patterns. They are typically thin, light, and small. Because of all these capabilities, you can quickly replace the conventional connection boards. It was the main purpose of designing these circuit boards.

Different types of flex circuit boards

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

  1. One-sided flexible circuits

It is one of the most widely used circuit designs. There are several reasons for its popularity. For example, they are the cheapest. They contain highly effective variants for various flex applications.

The building material for single sided circuits contains conductive inks. Another manufacturing material is metal etching. The ink and the etched metals create the desired circuit patterns on the surface of flexible boards.

  1. Double sided flexible circuits

It is the second most common flexible printed circuit design. It is useful for any application that requires high density circuit interconnection. Disconnect single sided circuit, it has two layers of metal connected with a plated through hole. A standard double-sided circuit contains successive layers of adhesive and cover sheet on either side of a base sheet.

  1. Multi-layer flex printing circuits

Likewise, the double sided circuit, it is useful for high density applications. It contains some properties that are similar to rigid circuits. however, due to its layered structure, it incorporates a refined design. It helps solve certain electrical and electronic problems.

A multilayer circuit is a combination of several single or double-sided flex circuits. Different individual circuits have several insulating and conductive layers between each connected device. Another option is to create a multilayer circuit. To do this, connect multiple circuit boards with a single center point.

  1. Rigid-Flex printing circuits

As the name suggests, it is a hybrid configuration that is a combination of rigid and flexible circuit boards. The rigid part carries all the components and strengthens the connectors. Meanwhile, the flexible section provides all of the connectivity for various rigid sections.
Initially, the ability to combine both rigid and flexible printed circuit boards developed for military design applications. The only purpose of developing a hybrid circuit is to make a reliable one. It helps to create a light connection structure.
It also involves a higher degree of technical complexity than rigid-flex printed circuits. A standard circuit can depend on integrated flexible wires with regulated impedance. The wires connect and join various rigid parts of the device to assemble the circuit body.

The thickness of the flexible circuit board

The thickness of the flexible circuit board varies depending on the material and type of the flexible circuit board. For example, the maximum 1 layer copper 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 are 12.6 and 4.7 respectively.

Different characteristics of a flexible printed circuit board

Here are some key features of flex circuit boards:

  • Flex circles have a short assembly time because they are not brittle. So engineers work fast. In addition, all lines are preconfigured. This also saves the connection work.
  • It reduces the weight of the products, which makes them easy to carry.
  • Flexibility makes it reliable and durable.
  • Polyamide reinforcements improve the strength of the circuit. This is because the connection areas of the board are strengthened.

The applications of the flexible printed circuit board

When it comes to reliability, maximum adaptability and flexibility, Flex PCB is extremely useful. When a circuit needs to be folded in the assembly process, it means you need a flexible printed circuit board. This circuit board is an ideal choice when warping and bending cannot be avoided.

In the past few years, the flexible circuit technology is very advanced. So you can use it in more compact and confined situations. The demand for flexible printed circuit boards is increasing day by day due to their great usage.

Here are some of the key uses for flexible printed circuit boards.

  1. Flexible printed circuit boards in computer electronics

Some major components of the computer rely on flexible circuitry to function properly. For example, to keep up with high speeds, the components in hard drives need to be flexible. While using hard drives for a long period of time, it may get hot. This means that printed circuit boards should be able to withstand high temperatures. In order to keep the hard drive working properly, credit goes to printed circuit boards.

Likewise computers, you can find flexible circuit boards in other electronic devices. For example, game systems, televisions, and printers.

  1. Flex circuit boards in automotive electronics

Automobiles are the most important 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 printed circuit boards. Dash systems, anti-lock braking systems, and instrument panels are some other useful uses.

Flexible boards don't usually take up much space, so you can mount them in any irregular shape. Therefore, it is helpful for engineers to use the flex board instead of bulky zip ties or connectors. Flex circuits are lightweight and smaller electronic components. All companies want to build light vehicles. By using lightweight flexible circuit boards, this can make a difference.

  1. Flexible circuit boards in the medical field

Flexible circuit boards play an important role in various medical and pharmaceutical applications. This is because circuits are sometimes exposed to various extreme conditions in the human body.

The most popular application for flex circuitry is in a swallowable camera, commonly known as a PillCam. This camera helps the doctor or healthcare professional to have an accurate view of the human body. So it is helpful for complaints. The pills have to be extremely small to swallow.

It helps create realistic prostheses. Researchers have introduced a technique to print circuits on flexible and organic material. This material is extremely smaller than typical flex circuit boards, so it can move naturally without damaging it.

Frequently used material made from flexible printed circuit board

These electronic devices consist of various. Here are four main materials:

  • The substrate and some other facing materials
  • Conductor materials
  • Isolators
  • Adhesives

Before choosing a material, you need to consider the following points:

  • capacity
  • Thermal conductivity
  • Degree of flexibility
  • Current conductivity and tolerance
  • Chemical and mechanical resistance

Overlay materials for substrates and covers

These are very helpful to cover the conductor material. This is because copper is the best conductor, but it oxidizes easily. The exposed copper surface therefore requires a masking material to prevent oxidation. Therefore, the substrate and coating material comes in handy in this situation. Gold and solder are good plating materials.

Conductor materials

Printed circuit boards are all about dealing with electricity. Therefore, a conductive material is a base material for FPCB. Copper is widely used in circuit boards because it is inexpensive. Another useful conductive material is:

  • Silver ink
  • Constantan
  • carbon
  • aluminum
  • Inconel


An insulator is a substance that prevents heat transfer. Flexible circuit board manufacturers therefore use it between different circuit board layers to prevent the emission of heat. It is the most important part of any circuit board. In fact, it improves the durability of printed circuit boards. Here are some suitable isolators:

  • Polyethylene
  • Solder mask
  • Polyimide
  • Flexible solder mask


It is another essential material in all types of printed circuit boards. It firmly attaches the conductor metal to the substrate. You have to be very picky about the choice of adhesive materials.

Most of the time, manufacturers choose adhesives based on customers' requirements and preferences. Various adhesives are available for printed circuit boards:

  • Epoxy
  • Pressure sensitive adhesives
  • acrylic

Advantages and disadvantages of flexible printed circuit boards

Likewise all other types of circuit boards, it also contains various advantages and disadvantages. Here are some pros and cons for flexible circuit boards.

Advantages of flexible printed circuit boards

There are several advantages of flex circuit boards compared to traditional electrical connections. Here are some of the pros at Flex Circuits:

  • Mechanical connections are completely eliminated.
  • The ability to create a strong and reliable signal.
  • It can withstand an enormous temperature.
  • Because of its flexibility, it is not easily breakable, which makes it reliable.
  • You can bend and fold it easily, resulting in a smaller size.
  • It covers a very small area due to its smaller size.
  • Flex circuits are lightweight.

Disadvantages of flexible printed circuit boards

This board has some drawbacks. Here are some disadvantages of flex circuits:

  • Although it is durable, the initial cost of this circuit board is quite high.
  • It is extremely difficult to make changes to this circuit board after it has been completed.
  • The rework and soldering require a professional team of engineers.

When is a flexible circuit board used?

Flexible circuit boards are made of polyimide or the like. They can withstand extreme temperatures between 200 and 400C. Therefore, it is important to use flexible circuitry when developing high temperature and density applications. For example, for logging wells in various gas and oil industries, they have a good use.

Since they can withstand heat, they also have good resistance to chemicals, radiation, and UV exposure. Therefore, it is extremely useful for all such applications dealing with chemicals, etc.

Why not make all PCBs flexible?

Flexible circuit boards have many advantages and take precedence over other types of circuit boards in several factors. however, for all its advantages, rigid circuit boards still cannot be completely replaced. Cost is one of the main obstacles to flexible printed circuit boards.

Many companies use flexible circuitry when needed. Otherwise, you use Rigid for manufacturing and assembly to keep costs down. MOKO-Technologie produces various types of printed circuit boards at an affordable price.

All applications require a reliable and durable printed circuit board. Hence, MOKO Technology is one of the best places to buy printed circuit boards.