Friends who know FPC flexible boards, especially those who have experience in FPC board factories, must know that the raw materials that make up FPC are more complex than PCB rigid boards. The selection of materials is also more cumbersome.
In addition to FCCL is the substrate of FPC, the raw materials of FPC also include many materials. Next, I will make a brief introduction to the other raw materials that make up FPC based on my personal knowledge and understanding.
1. coverlay
Coverlay: CVL for short, is a material formed by the combination of insulating material PI and adhesive glue (AD glue).
The thickness of AD glue of CVL is generally 15 50um
The PI thickness of CVL is generally 125um，25um，50um，75um，125um
There are different colors of CVL, and the actual selection needs to be selected according to customer requirements. In general, yellow CVL is less costly.
2.Reinforcing material stiffener
Reinforcing material stiffenerAbbreviated as STF, also known as reinforcing tablets.
Function: Strengthen the mechanical strength of FPC and facilitate the installation of surface components.
Common reinforcing materials: PI, PET, FR-4, aluminum sheet, steel sheet, etc.
Different reinforcing materials have their own advantages and disadvantages: high PI**, but good flame resistance. PET** is low, but not heat-tolerant. The reinforcing material of the metal also has the effect of heat dissipation.
Note: FPC with soldering or reflow soldering reflow needs, need to use PI, FR-4, aluminum sheet, steel sheet.
3.Pure rubber.
The materials used for interlayer lamination of multi-layer FPC boards are pure glue thermosetting glue.
Common pure rubber thickness: 10um, 15um, 20um, 25um, 30um, 40um, 50um
4.Electromagnetic shielding film EMI
Electromagnetic Interference (EMI) is a material used to suppress electromagnetic interference.