1. Static design

Static design refers to the bending or folding that a product only encounters during the assembly process, or the bending or folding that rarely occurs during use. Single sided, double-sided, and multi-layer circuit boards can all successfully achieve folded static design. Usually, for most double-sided and multi substrate designs, the bending radius of the fold should be ten times the thickness of the entire circuit. Circuits with more layers (eight or more) will become very hard and difficult to bend, so there will be no problems. Therefore, for double-sided circuits that require strict bending radius, all copper wires should be set on the same side of the substrate film in the folding area. By removing the film covering on the opposite side, the folded area is approximated as a single sided circuit.

2. Dynamic design

The design of dynamic circuits is aimed at the repeated bending that occurs throughout the entire lifecycle of the product, such as the cables of printed machines and disk drives. In order to achieve a long bending life cycle for dynamic circuits, the relevant parts should be designed as a single sided circuit with copper on the central axis. The central axis refers to a theoretical plane located in the central layer of the material that makes up the circuit. By using the same thickness of substrate film and lamination on both sides of copper, the copper foil will be accurately positioned in the center and subjected to minimal pressure during bending or bending.

Multilayer complex designs that require high dynamic bending cycles and high density can now be achieved by connecting double-sided or multi-layer circuits to single-sided circuits using anisotropic (z-axis) adhesives. Bending occurs in a single-sided assembly area, and outside the dynamic bending area, it belongs to a multi-layer area, which is not endangered by bending and can install complex wiring and required components.