What is FPCB?
Flexible electronics are achieved by mounting electronic components onto flexible plastic substrates, such as polyimide, PEEK, and transparent conductive polyester. The printed circuit board made of a flexible substrate is called a flexible printed circuit board (FPCB or FPC). Thanks to their excellent flexibility, lightweight, and reduced thickness FPCBs are used extensively in nowadays electronics.
Structure of a flexible PCB （FPCB)
As happens for rigid PCBs, FPCs can be divided into single-layer, double-layer or multi-layer circuits. The main elements of a single-layer flexible printed circuit are the following:
- Dielectric substrate film: the base material of the PCB. The most commonly used material is polyimide (PI), characterized by high resistance to traction and temperature.
- Electrical conductors: made of copper, they represent the traces of the circuit.
- Protective finish, made with cover lay or cover coat.
- Adhesive material (polyethylene or epoxy resin): used for joining the various parts of the circuit together.
Does it mean we can make all the electronics flexible with FPCB?
The answer is, potentially.
Maybe you have seen a flexible display, and why has it yet to be widely adopted so far?
Designers have been investigating the novel idea of utilizing FPCB as a substrate for motherboards. However, there have been constraints due to the disadvantage of FPCBs.
- Cost increase over rigid PCBs
- Increased risk of damage during handling or use
- Difficult assembly process
- Repair and rework are difficult or impossible
- Generally worse panel utilization resulting in increased cost
Nowadays, FPCBs are often used as connectors in various applications of flexibility, space and production constraints. Many consumer electronics devices are making use of flexible circuits such as cell phones, cameras, personal entertainment devices and more. Flexible circuits are used in industrial and medical devices as well where many interconnections are required in a compact package.
The introduction of flexible PCBs has revolutionized the legacy electrical interconnection techniques. The flexible PCB technology has been continuously growing, driven by the spread of increasingly smaller and lighter electronic devices. In many applications, flexible PCBs eliminate the need for connectors and cables. It hence improves connection reliability while reducing assembly time, costs and the size of the whole device.
Granted, flexible PCBs have allowed the implementation of new and interesting applications that are not achievable with traditional rigid PCBs. However, the disadvantages of it will have to be carefully considered by designers. Surely, it will take time for scientists and designers to develop FPCB technology’s full potential.