FPC, also known as flexible printed circuit board, is a printed circuit made of flexible insulating substrates (polyester film or polyimide). It has many advantages that printed circuit boards do not have. FPC flexible circuit boards can not only bend freely, but also Folding and winding, it also has the characteristics of light weight, small size and good heat dissipation. The design of soft and hard structure also compensates for the slight lack of component carrying capacity of the flexible substrate to a certain extent. At the same time, the FPC flexible circuit board can also Arrange arbitrarily in accordance with the requirements of the space layout, and move and expand at will in the three-dimensional space, so as to achieve the integration of component assembly and wire connection.
The use of FPC flexible printed circuit boards can reduce the volume of electronic products to a large extent, and meet the needs of electronic products to develop in the direction of high density, miniaturization and high reliability. Therefore, FPC flexible printed circuit boards are mainly used in mobile phones, laptops or liquid crystals. In relatively thin and light electronic products such as display screens. In the structure of the flexible circuit, the material is composed of flexible copper clad laminate (FCCL), cover film, adhesive film, etc.
Flexible copper clad laminate (FCCL): The common sheet films of flexible copper clad laminates are polyimide film (PI), polyester (PET), polyethylene 2,6 naphthalate (PEN:), high liquid crystal display Polymer (LCP) and other polymer material plastic films. Copper clad laminates are mainly responsible for three levels of conductivity, insulation and support points in all pcb circuit boards.
Cover film: It is composed of organic chemical plastic film and adhesive. The function of the cover film is to maintain the part of the electric conductor of the flexible power circuit. Adhesive films have different types of sheet films and adhesives, and thin and thick specifications.
Adhesive film: It is formed by pouring adhesive on both sides or one side of a substrate film. There are also adhesive films without a substrate without a pure adhesive layer. The adhesive films have different adhesive types and thickness specifications. Adhesive film is used for interlayer adhesion and insulation of multilayer boards.
FPC flexible printed circuit boards can be divided into single-sided FPC, double-sided FPC, and multi-layer FPC according to the number of circuit layers. There are also differences in the production process of different circuit layers. Single-sided FPC flexible printed circuit boards and double-sided FPC flexible Take the printed circuit board as an example.
Single-sided FPC flexible printed circuit board production process: cutting, drilling and sticking dry film, counter-exposure, developing, etching, stripping, surface treatment, covering film, pressing, curing surface treatment, Immersion nickel gold, printed characters, shearing, punching, final inspection, packaging, shipment
Double-sided FPC flexible printed circuit board production process: cutting, drilling, PTH, electroplating, pre-treatment, dry film, alignment, exposure, development, graphics, electroplating, pre-treatment, dry film, alignment, development, etching, peeling, surface treatment, covering film, pressing, curing sink Nickel-gold-printed character cutting, electrical testing, punching and final inspection packaging and shipment
In order to better guarantee the effect and quality requirements of FPC flexible printed circuit boards, it is necessary to strictly follow the production process to ensure that the operating methods of cutting and drilling are processed in accordance with its standard mode, and fundamentally improve FPC Board quality, strict quality screening system is an effective way to ensure the maximum quality of FPC products. Good R&D and design capabilities can ensure better production capacity and provide more reliable quality.