What are the Main Materials of FPC

FPC is the abbreviation of Flexible Printed Circuit, which is widely popular for its lightness, thinness and flexibility and other characteristics. It uses various materials are used in the production process. The materials that make up the flexible PCB include insulating base material, adhesive, metal conductor layer (copper foil) and covering layer. The difference in materials also determines the performance of FPC. Next, I will introduce you to these materials.

1. Insulating Base Material

Insulating base material is a flexible insulating film. As an insulating carrier for circuit boards, it is required to have good mechanical and electrical properties. Nowadays, polyimide (PI) film and polyester (PET) film are commonly used in FPC. Generally, the film thickness is selected within the range of 0.0127~0.127 (0.5mil~5mil).

2. Adhesive

The adhesive acts as a bond between the film base material and the metal foil, or the film base material and the cover film. FPC can use different types of adhesives for different film base materials. For example, the adhesives for polyester and polyimide are different. Adhesives for polyimide base materials are divided into epoxy and acrylic types. There are also adhesive-free polyimide copper-clad laminates, which have better chemical resistance and electrical properties.

3. Metal Foil

Metal foil is a conductive layer that covers and is bonded to an insulating base material, and is later selectively etched to form conductive lines. Most of this metal foil is pressed rolled copper foil (RA) or electrolytic copper foil (ED). Relatively speaking, the ductility and bending resistance of rolled copper foil are better than those of electrolytic copper foil. The elongation of rolled copper foil is 20% to 45%, and the elongation of electrolytic copper foil is 4% to 40%. The most commonly used copper foil thickness is 35μm (1oz), and there are also thin 18μm (0.5oz) or thick 70μm (2oz), or even 105μm (3oz).

4. Cover Film

Covering film refers to the insulating protective layer on the surface of FPC, which plays the role of protecting surface wires and increasing the strength of the base material. A common cover film is an insulating film made of the same material as the base material, such as a polyester or polyimide film coated with an adhesive. In order to save costs, some consumer electronic products can use solder mask coating instead of covering film, which also plays a role in protecting wires.

5. Stiffener

Stiffener is a board bonded to a local position of the flexible PCB, which supports and strengthens the flexible film base material to facilitate the connection, fixation or other functions of the printed board. FPC stiffener materials are selected according to different uses. Commonly used stiffener materials include polyester, polyimide film sheets, epoxy glass cloth boards, phenolic paper or steel boards, aluminum boards, etc. The thickness is also selected according to strength requirements.

Therefore, each process in the production process must be implemented strictly in accordance with the production process. For FPC manufacturing and production, you need to find a reliable and high-quality FPC manufacturer.

HoYoGo is an international, professional and reliable FPC factory with 2 factories production bases and monthly production capacity is 500,000sqm. We can provide with you one-stop PCB product supply. We have a management team with an average of 25 years of industry experience and reliable quality assurance.