Flexible circuit and Rigid flex circuit are used extensively in applications and industries including:

General specification for flexible & Rigid-flex printed circuit board

Layer count: 1-6L(Flex) & 2-10L(Rigid-flex)
Board thickness: 0.05-3.0mm
Base polyimide film thickness: 0.5 mil (12.5µ), 1 mil (25µ), 2 mils (50µ).
Copper thickness: 1/3oz (12µ), 1/2oz (18µ), 1oz (35µ), 2oz (70µ)
Stiffeners: Polyimide, FR4, Metal
Min trace width/spacing: 3/3mil(0.075/0.075mm)
Min drill size: 0.2mm
Surface treatment: Immersion Gold/Tin, Gold/Tin Plating, OSP

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1. Single-sided flexible circuit board

Single-sided flexible circuits are the simplest and there for cheapest, consisting of a single conductor layer on a flexible dielectric film with the option of a coverlay or semi flexible liquid photo imagable solder resist (for some flex & stay applications). Parts of the flexible can be made more rigid by the use of additional stiffeners.

2. Double-sided flexible PCB

Double sided flexible pcb consist of two copper layers with a dielectric layer in between ，Normally connected with plated through holes, with the option of coverlay's or semi flexible liquid photo imagable solder resist (for some flex & stay applications). Parts of the flexible can be made more rigid by the use of additional stiffeners.

3. Multilayer flex PCB

Multilayer flex pcb consist of three or more copper layers with a dielectric layer in between, normally connected with plated through holes, with the option of coverlay's or semi flexible liquid photo imagable solder resist (for some flex & stay applications). Parts of the flexible can be made more rigid by the use of additional stiffeners.

4. Rigid-flex PCB

Rigid-flex PCB consist of a mixture of flexible copper conductor layers on dielectric film & rigid copper material， normally connected with plated through holes. Coverlay's are applied to the flexible copper conductor layer & liquid photo imagable solder resist applied to the rigid areas.