What type and characteristics of FPC flexible circuit board

Flexible Printed Circuit (FPC for short) is a highly reliable and excellent flexible printed circuit board made of polyimide or polyester film. It has the characteristics of high wiring density, light weight, thin thickness and good bendability. At present, there are several types of FPC flexible circuit boards in the mainstream market: single-sided, double-sided, multi-layer and soft-rigid combination boards. What characteristics are there in which neighborhoods are used for species separation?

1. Single-sided FPC is a circuit board with the lowest cost and low requirements for electrical functions . In single-sided wiring, single-sided FPC 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 rolled copper foil. Insulating substrates can be polyimide, polyethylene terephthalate, aramid and polyvinyl chloride.

2. Double-sided FPC is a conductive pattern formed 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 application function of flexibility. The cover film protects single and double-sided conductors and indicates where the components are placed.

3. Multi-layer FPC is to laminate 3 or more layers of single-sided or double-sided FPC together, and form metallized holes by drilling and electroplating, and form conductive paths between different layers. In this way, there is no need to choose a complicated welding process. Multilayer circuits have huge functional differences in terms of higher reliability, better thermal conductivity, and easier assembly capabilities. When planning the layout, the interaction of assembly size, number of layers and flexibility should be considered.

Fourth, the traditional rigid-flex board is composed of rigid and flexible substrates selectively laminated together. The structure is compact, and the conductive connection is formed by metallization. If a circuit board has positive and negative components, just FPC is a good choice. But if all components are on one side, it is more economical to use double-sided FPC and laminate a layer of FR4 reinforcement on the opposite side.

5. The FPC of the mixed 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 dielectric and polyimide as the outer dielectric, with leads extending from three different directions of the motherboard, each made of a different metal. Constantan, copper and gold are used as separate leads. This kind of hybrid structure is mostly used in low temperature situations where the relationship between electrical signal conversion and heat conversion and electrical functions are relatively harsh, and it is a specific and feasible solution.