FPC vs PCB: What Is The Difference?

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FPC vs PCB: What is the difference?

Image source: Thetech

Flexible printed circuit (FPC) and printed circuit board (PCB) are two types of circuit boards that are used in a wide range of applications. What do they stand for and what are the differences between them? In this article, we are going to break down the differences between FPC and PCB. We will also strive to answer all the questions that you may be having about these circuit boards, and give advice on which one you should use for your application.

What is FPC?

A flexible printed circuit board (FPC) is a highly flexible printed circuit board that is made of several layers that can be easily folded or bent-hence the name “flexible”. This type of circuit board is usually used in devices that are likely to be bent or folded when used. Polyester or polyamide is among the top materials that make up the flexible layers of the FPC.

It has an array of impressive features and characteristics such as bendability, and super-thin, and is also lightweight. A typical FPC also has a metal foil that serves as a conductive layer for the printed circuit board. All the layers that make up a flexible printed circuit can withstand the vigorous manufacturing process of the PCB.

Composition of FPC

A typical FPC is made of several layers that are made of different materials. These layers include:

Flexible copper sheet (FCCL): this layer mainly comprises copper plating films as well as polyester and polyamide films. Copper acts as a conductor while the polymers serve as insulators while at the same time enhancing the flexibility of the layer.

  • Coating film: This layer comprises an adhesive compound and resin. The main function of this layer is to retain the wiring or connectivity of the components on the printed circuit board.
  • Bond film:  As the name suggests, the purpose of this film is to bond two layers of the printed circuit.

Key features of FPC

Here are some of the key features or characteristics of FPC

  • Bendable: The flexibility of this circuit board allows it to be bent within a defined range. This is a key feature that makes it suitable for the target application areas
  • Supports electrical conductivity: The presence of a metal foil in the FPC makes it a good conductor of electric current and data signals.
  • Lightweight: From the FPC composition, it is clear that it has several thin layers. They are highly credited for the lightweight nature of the printed circuit.
  • Flexible design: The design and layout of the FPC is highly flexible such that it makes it easy to place electronic components at different positions on the circuit board.

Application areas

Where are FPCs used? Common application areas of flexible printed circuits include the following:

  • Wearable devices: These are devices that are designed to be worn on different body parts. They include smart watches, fitness devices, and a good number of portable devices.
  • Smartphones and tablets
  • Airbag systems in vehicles
  • Aerospace and avionics
  • Military electronics
  • Robotics

What is PCB?

Printed circuit board is a general term that is used to refer to a printed board into which several complete electric circuits and electronic components are laid. Although PCB is also made of several layers, it is quite rigid. You cannot bend it easily as this will cause physical, structural, and electrical damage.

PCB composition

A PCB is made of four layers with each player playing a specific role in the overall functionality of the circuit board: These layers include the following:

  • FR4 substrate: At the very base of the PCB is the FR-4 materialwhich is basically a glass that has been reinforced with epoxy material. This material cannot easily break.
  • Copper layer: This is the second layer from the base and it enhances the conductivity property of the PCB.
  • Solder mask: This material is at the top of the copper layer. It is mainly used for separating or isolating individual components on the PCB. It also defines the placement and positioning of the components.
  • Silkscreen: This is the topmost layer of the PCB. It is ultra-thin and helps in the identification of the PCB components.

Features of PCB

Here are some of the distinct properties of a typical printed circuit board:

  • Rigid: A typical PCB is designed to remain as it is. The materials that have been used on the circuit cannot change their design and structure.
  • Flexible designs: Despite being rigid, PCBs come in different designs and layouts. The design that you choose will depend on the intended use or application area.
  • Electrical conductivity:  PCBs have excellent electrical conductivity thanks to the presence of a copper layer and coating.
  • Heat management: PCBs are designed and constructed with thermal management in mind. They are embedded with various heat management elements whose purpose is to prevent overheating.

Differences between FPC vs PCB

At this point, you have vital information about both FPC and PCB.  Now it is time to analyze the differences between these two.

  • Composition: As we have seen, there is a slight difference in the composition of the two printed circuit boards. FPC has highly flexible components such as polymers while PCB’s composition comprises of rigid materials such as glass-fiber.
  • Flexibility: FPCs are super flexible as they can be easily bent. On the other hand, PCBs are quite rigid. You can not bend this type of PCB to fit into a device.
  • Application areas: FPCs are suitable for small and portable devices that are likely to be subjected to physical and structural movements. PCBs are perfect for rigid devices and applications.
  • Design and layout:Most PCBs come in fixed designs whereby they feature flat surfaces to accommodate components. On the other hand, FPCs come in different dimensions to achieve maximum flexibility
  • Cost: The cost of producing FPCs is higher than that of PCBs. This is mainly because PCBs can be more easily subjected to mass production than FPCs. Assembling materials and components on FPCs can be quite a challenging process.

Conclusion

In summary, FPC boards and PCBs have unique features and different application areas. Each is designed to achieve a specific goal in its respective application area.  Before you decide on which circuit board to use, it is important to conduct extensive research.  When it comes to buying printed circuit boards, ensure that you consult experts in this field.

Last Updated on October 26, 2023 by Kevin Chen

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