Flex PCB material is composed of insulating film, conductor and adhesive.
The insulating film is the basic layer in the circuit. The copper foil is bonded to the insulating layer by adhesive. In a multi-layer design, it is then bonded to the inner layer. They are also used as protective coverings to insulate the circuit from dust and moisture and to reduce stress during bending, and the copper foil forms a conductive layer.
In some flexible circuits, rigid components made of aluminum or stainless steel are used, which can provide dimensional stability, provide physical support for the placement of components and wires, and release stress. The adhesive is used to bond rigid components to flexible circuits.
In addition, the adhesive layer is a kind of flex PCB material, which provides environmental protection and electronic insulation functions, and can eliminate a layer of film, and has the ability to bond a few layers of multilayer materials.
Copper foil is suitable for use in flexible circuits. It can be electrodeposited. The surface of copper foil by electrodeposition is glossy on one side and dull on the other side. It is a flexible material and can be made into many different thicknesses and widths. The matte side of ED copper foil is often improved by special treatment. In addition to its flexibility, forged copper foil has the characteristics of hardness and smoothness. It is suitable for applications where dynamic bending is required.
In addition to bonding insulating film to conductive materials, it can also be used as covering layer, protective coating and covering coating. The main difference between the two lies in the application mode used. The bonding of the covering layer and the insulating film is to form a circuit with laminated structure.
Not all the stacked structures contain adhesives, the laminates without adhesives can form thinner circuits and have greater flexibility. Compared with the laminated structure based on adhesive, the laminates without adhesives have better thermal conductivity.