PCB News - main features of flexible PCB boards

At present, there are four types of flexible circuits: single-sided, double-sided, multilayer flexible PCB boards and rigid flexible boards. To

1. Single-sided flexible boards are the lowest cost printed boards that do not require high electrical performance. In single-sided wiring, a single-sided flexible board should be used. It has a layer of chemically etched conductive patterns, and the conductive pattern layer on the surface of the flexible insulating substrate is a rolled copper foil. The insulating substrate can be polyimide, polyethylene terephthalate, aramid cellulose ester and polyvinyl chloride. To

2. The double-sided flexible board is a conductive pattern made by etching on both sides of the insulating base film. The metallized hole connects the patterns on both sides of the insulating material to form a conductive path to meet the design and use function of flexibility. The cover film can protect single and double-sided wires and indicate where the components are placed. To

3. Multilayer flexible board is to laminate 3 or more layers of single-sided or double-sided flexible circuits together, and form metallized holes by drilling and electroplating to form conductive paths between different layers. In this way, there is no need to use a complicated welding process. Multilayer circuits have huge functional differences in terms of higher reliability, better thermal conductivity and more convenient assembly performance. When designing the layout, the mutual influence of assembly size, number of layers and flexibility should be considered. To

4. The traditional rigid-flex board is composed of rigid and flexible substrates selectively laminated together. The structure is compact, and the metallization hole L forms a conductive connection. If there are components on the front and back of a printed board, a rigid-flex board is a good choice. But if all the components are on one side, it will be more economical to choose a double-sided flexible PCB board and laminate a layer of FR4 reinforced material on its back. To

5. The flexible circuit of the hybrid structure is a multi-layer board, and the conductive layer is composed of different metals. An 8-layer board uses FR-4 as the inner layer medium and polyimide as the outer layer medium. Leads extend from three different directions of the main board, and each lead is made of a different metal. Constantan alloy, copper and gold are used as independent leads. This kind of hybrid structure is mostly used in the low temperature conditions where the relationship between electrical signal conversion and heat conversion and the electrical performance are relatively harsh, and it is the only feasible solution. To
It can be evaluated by the convenience and total cost of the internal connection design to achieve the best performance-price ratio.