What are the common types of FPC flexible circuit boards?

FPC flexible circuit boards are common types

At present, FPC flexible circuit boards are: single-sided, double-sided, multi-layer flexible circuit boards and rigid flexible combined circuit boards four kinds.

1. Single-side flexible circuit board is the lowest cost, when the electrical performance requirements are not high printed board. In single-side wiring, single-side flexible circuit board should be selected. It has a chemically etched conductive pattern layer, and the conductive pattern layer on the flexible insulating substrate is calendered copper foil. The insulating substrate may be polyimide, polyethylene terephthalate, arylamide fiber ester and polyvinyl chloride.

2. Double-sided flexible circuit board is a conductive graph etched on both sides of the insulating substrate film. The metallization hole connects the two sides of the insulating material to form a conductive path to meet the flexural design and use function. The covering film can protect the single and double-sided wire and indicate the position of the element.

3. Multi-layer flexible circuit board is the single or double-sided FPC flexible circuit board of 3 or more layers laminated together, through drilling and electroplating to form a metallized hole, forming a conductive path between different layers. In this way, there is no need to use complex welding process. Multilayer circuits have great functional differences in terms of higher reliability, better thermal conductivity and more convenient assembly performance. The interaction of assembly size, number of layers and flexibility should be taken into account when designing layout.

4. The traditional rigid-flexible circuit board is composed of rigid and flexible substrate pressed together. The structure is tight and metallized to form conductive connection. If a printed board has both front and back components, rigid flexible circuit board is a good choice. But if all the components are on one side, it is more economical to use a double-sided flexible circuit board and layer FR4 reinforcement on the back.

5. FPC flexible circuit board with mixed structure is a kind of multi-layer board, the conductive layer is composed of different metals. An 8-layer board uses FR-4 as the medium for the inner layer and polyimide as the medium for the outer layer, with leads extending from three different directions of the motherboard, each of which is made of a different metal. Copper alloy, copper and gold are used as independent leads. This kind of hybrid structure is the only feasible solution when the relationship between electric signal conversion and heat conversion and electrical properties are harsh. It can be evaluated by the convenience of the interconnecting design and the total cost to achieve the best performance-price ratio.