What are the three major types of FPC?
Times：May 4,2019 Hits：1048
PCBs are used in electronic products, and the market trend of PCBs is almost the vane of the electronics industry. With the development of high-end, miniaturized electronic products such as mobile phones, notebook computers and PDAs.
PCBs are used in electronic products, and the market trend of PCBs is almost the vane of the electronics industry. With the development of high-end, miniaturized electronic products such as mobile phones, notebook computers and PDAs, the demand for flexible PCBs (FPC) is increasing, and PCB manufacturers are accelerating the development of thinner, lighter and denser FPCs. Edited to introduce you to the types of FPC.
First, single-layer FPC
There is a layer of chemically etched conductive pattern, and the conductive pattern layer on the surface of the flexible insulating substrate is a rolled copper foil. The insulating substrate may be polyimide, polyethylene terephthalate, aramid fiber ester and polyvinyl chloride. Single-layer FPCs can be divided into the following four subcategories:
1. No overlay single-sided connection
The conductor pattern is on an insulating substrate, the surface of the conductor is uncovered, and the interconnection is achieved by soldering, welding or pressure welding, which is commonly used in early telephones.
2. Covered single-sided connection
Compared with the previous class, it only has a layer of cover on the surface of the wire. The pad needs to be exposed when covering, and it can be easily covered in the end area. It is the most widely used and widely used one-sided flexible PCB, and is used in automotive instruments and electronic instruments.
3. No overlay double-sided connection
The land interface can be connected to the front and back of the wire, and a via hole is formed in the insulating substrate at the pad. The via hole can be punched, etched or otherwise mechanically prepared at a desired position of the insulating substrate. to make.
4. Covered double-sided connection
Different from the former category, the surface has a cover layer, the cover layer has access holes, allowing both sides to be terminated, and still maintain the cover layer, made of two layers of insulating material and a layer of metal conductor
Second, double-sided FPC
The double-sided FPC has a conductive pattern formed by etching on both sides of the insulating base film, which increases the wiring density per unit area. The metallized holes connect the patterns on both sides of the insulating material to form a conductive path to meet the design and use functions of the flexibility. The cover film protects the single and double-sided wires and indicates where the components are placed. Metallized holes and overlays are optional, as required, and there are fewer FPC applications.
Third, multi-layer FPC
The multi-layer FPC laminates three or more layers of single-sided or double-sided flexible circuits together, and forms a metallized hole through the drill collar L and electroplating to form a conductive path between the different layers. This eliminates the need for complex welding processes. Multilayer circuits have tremendous functional differences in terms of higher reliability, better thermal conductivity, and more convenient assembly performance.
This has the advantage that the substrate film is lightweight and has excellent electrical properties such as a low dielectric constant. Multilayer flexible PCB board made of polyimide film is about 1/3 lighter than rigid epoxy glass cloth. However, it loses single-sided, double-sided flexible PCB. Flexibility, most of these products are not required for flexibility. Multi-layer FPCs can be further divided into the following types:
1. Flexible insulation substrate finished product
This type is manufactured on a flexible insulating substrate and the finished product is specified to be flexible. This construction typically bonds the two ends of a plurality of single-sided or double-sided microstrip flexible PCBs together, but the central portions are bonded together to provide a high degree of flexibility. For a high degree of flexibility, a thin, suitable coating, such as polyimide, can be used on the wire layer instead of a thicker laminate overlay.
2. Soft insulating substrate finished product
This type is manufactured on a soft insulating substrate, and the finished product is specified to be flexible. Such multilayer FPCs are laminated to a multilayer board using a soft insulating material such as a polyimide film, which loses its inherent flexibility after lamination.
