Flexible PCB

What is a flexible PCB board?

Flexible printed circuits, also known as flex circuits, are sometimes regarded as a printed circuit board (PCB) that can bend, when in reality there are significant differences between PCB’s and flex circuits when it comes to design, fabrication and functionality. One common mistake that designers make is to design a flexible circuit using the same rules as a PCB. Flex PCB require a unique set-up and have their own set of design rules that the Hitechpcb team has termed “flex-izing” and have worked hard to perfect over the last many years.

 Flexible PCB, which also called Flex PCB, Flexible circuit board or flex circuit, it consists of PI base material, adhesive layer, copper layer, coverlay and sometimes with stiffeners. Flexible PCBs are now being used widely to replace traditional FR4 PCB in various different applications due to the benefits from flex PCB specially. Although more expensive than a normal rigid PCB, the right design in the right application could save weight and time in assembly, coupled with the reliability which makes flexible circuit board a worthwhile consideration.

 A flexible printed circuit consists of a metallic layer of traces, usually copper, bonded to a dielectric layer, usually polyimide. Thickness of the metal layer can be very thin (<.0001″) to very thick (> .010″) and the dielectric thickness can vary from .0005″ to .010″. Often an adhesive is used to bond the metal to the substrate, but other types of bonding such as vapor deposition can be used to attach the metal.

What is Multilayer flex PCB?

This type of flexible printed wiring boards are multilayered (with three or more conductor layers) and require plated-through holes. We could use through vias, buried vias and blind vias.

 A multi layer flex circuit combine several single-sided or double-sided circuits with complex interconnections, shielding and/or surface mounted technologies in a multi layer design. The multi layers may or may not be continuously laminated together throughout the production process. If your design needs require maximum flexibility, continuous lamination may not be appropriate. Multi layer circuits are an effective solution when confronted with design challenges such as: unavoidable crossovers, specific impedance requirements, elimination of crosstalk, additional shielding and high component density. You can also link here to learn more about flex pcb bending radius.

Flex PCB Dynamic Flexing Applications

A situation where the flexible circuit itself is dynamically (repeatedly) flexed during the actual use of the final product. Common examples include flip-type cell phones, laptops, printer heads and robotic arms. A dynamic application will require the use of Rolled Annealed (RA) copper.

Advantages of Flexible PCB

Flexible PCB boards are printed circuits made of flexible insulating substrates, and have many advantages that rigid PCB boards do not have:

1. It can be bent, wound, and folded freely, can be arbitrarily arranged according to the space layout requirements, and can be moved and expanded in three-dimensional space, so as to achieve the integration of component assembly and wire connection;

2. The use of FPC board can greatly reduce the volume and weight of electronic products, which is suitable for the development of electronic products in the direction of high density, miniaturization and high reliability. Therefore, FPC has been widely used in aerospace, military, mobile communications, laptop computers, computer peripherals, PDAs, digital cameras and other fields or products;

3. Flexible pcb board also has the advantages of good heat dissipation and solderability, easy assembly and low overall cost, etc. The design of Rigid-flex PCB also makes up for the slight deficiency of the flexible substrate in the component carrying capacity to a certain extent.

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