Flexible printed circuit (FPC) has excellent bending resistance, lightness and flexibility. Let's talk about raw materials of FPC in detail.

 

Substrate

 

Substrate is composed of resin and reinforcing material. Among them, the resin includes polyimide (PI), polyester (PET) and polyvinyl chloride (PVC). The reinforcing material includes glass fiber cloth and polyimide film. The thickness of FPC is generally between 0.03mm-0.2mm. The processing has high requirement of accuracy. The bending radius is usually not more than 0.05mm.

 

Bonding parts

 

The bonding parts include pads, insulating layers and circuit connections. Pads are metallized areas used to connect circuit boards and other components. They are made of copper or nickel. The insulating layer isolates signal interference between different circuit layers to ensure the reliability of circuit. Circuit connections connect things between different circuit layers.

 

Insulation materials

 

The insulating materials in FPC mainly include thermosetting insulating materials and high temperature resistant insulating materials. Thermosetting insulating materials have high electrical insulation performance and high temperature resistance. Polyimide film and melamine film are popular.

 

High temperature resistant insulating materials can maintain good electrical insulation at high temperatures. The common ones are silicone and PET films.

 

Adhesives

 

Adhesives in FPC are mainly used to bond the various layers. There are some popular adhesives, heat-curing adhesives and UV-curing adhesives.

 

Heat-curing adhesives have high bonding strength and temperature resistance. They can maintain stable performance at high temperatures. UV-curing adhesives have features of fast curing and environmental friendliness. They are suitable for high-precision and micro-circuit boards.

 

Shielding materials

 

Shielding materials prevent electromagnetic interference and signal leakage. Common materials are conductive cloth and conductive adhesive.

 

Conductive cloth has good electromagnetic shielding performance and mechanical strength. It can be used to make electromagnetic shielding covers and circuit boards.

 

Conductive adhesive can bond electromagnetic shielding materials and circuit boards together to achieve electromagnetic shielding and circuit conduction.

 

Protective film

 

Protective films help to protect circuit from the external environment. Insulating protective films and surface protective films are good.

 

Insulating protective films can effectively isolate the electrical connection between the circuit board and other components to ensure reliability of the circuit.

 

Surface protective films can prevent the circuit board from mechanical damage and contamination during transportation and use.

 

Conductive silver glue

 

Conductive silver glue is used to make electrical connection between circuit boards and other components. Common glues are single-component silver glue and two-component silver glue.

 

Single-component silver glue can be quickly cured at room temperature. It is suitable for bonding various metal and non-metal materials.

 

Two-component silver glue needs to be mixed. It has high bonding strength and temperature resistance, which is suitable for electrical connection in special occasions.

 

Special sizing material for FPC

 

Sizing protects FPC, and improve reliability. The common materials are resin, diluent and initiator.

 

Resin is the main component of sizing. It has high bonding strength and insulation properties. Diluent can reduce the viscosity of resin, which is conducive to the coating and penetration of sizing. Initiator can promote the curing reaction of resin, and improve the curing speed and reliability of sizing.

 

As advanced electronic components, FPC has excellent performance and use value. It is widely applied in electronics, communications, medical care, aerospace, etc..