The thickness of traditional PCB is mainly determined by the substrate, while the thickness of FPC is more complicated. It is determined by the thickness of substrate, copper foil, cover film and reinforcement material. Generally speaking, according to different application requirements, the thickness of FPC is usually between **0.05mm and 0.4mm**, and the specific thickness depends on the following main components:
1. Substrate (sheet):
There are usually two types of substrates for FPC: polyimide (PI) and polyester (PET), and their thickness ranges from 0.0125mm to 0.1mm, of which 0.025mm and 0.05mm are the most common thicknesses.
2. Copper foil (conductive layer):
Copper foil is the conductive layer in FPC, and its thickness usually ranges from 12µm to 70µm, while the conventional thickness is 35µm (about 1oz). The thickness of copper foil directly affects the conductive performance of the circuit and the overall thickness of the sheet.
3. Cover film:
FPC cover film is used to protect the circuit from oxidation, moisture and mechanical damage. The thickness of the cover film is relatively thin and has little effect on the overall thickness of the FPC. It is generally between **12.5µm~50µm**, and the most common is 25µm.
4. Reinforcement material:
FPC reinforcement material is the thickest and strongest part of the FPC, used to enhance the mechanical strength and durability of the flexible circuit board. Common reinforcement materials include FR4, PI and stainless steel. The thickness of the reinforcement material is usually between 0.1mm~1mm**, and sometimes even thicker depending on the demand.
