To understand Flexible PCB Thickness, the first thing to know is the structure of flexible circuit PCBs.
FPC is composed of substrate, copper foil, adhesive, covering film/solder mask, so the thickness of FPC is basically determined by these factors.
When there is a coverlay, Solder Mask is generally not used. Solder Mask is mainly aimed at FPCs with higher accuracy requirements, because of their photosensitivity, better accuracy and finer graphics can be obtained through exposure and development. However, due to the bending performance of FPC, the material requirements for Solder Mask are particularly high. Otherwise, Solder Mask can easily crack and affect product reliability. It can be said that the cost of Solder Mask is much higher than that of coverlay.
When calculating the thickness of FPC, the substrate+copper foil thickness (only one layer of copper foil for a single panel, and two layers of copper foil for a double-sided FPC)+coating film/solder mask are usually used.
With the most conventional method of using coating film, we can conclude that the thickness of a single-sided FPC is generally between 0.1mm and 0.2mm (substrate thickness+one layer of copper foil thickness+adhesive+one side of coating film thickness).
The thickness of double-sided FPC is generally between 0.15mm-0.25mm (substrate thickness+thickness of two layers of copper foil+two adhesive+thickness of two sides of covering film)
When you know how to calculate the thickness of FPC, if you want to reduce the thickness, you should correspondingly reduce the thickness of each material. If you can use a PI of 0.025mm and a covering film of 0.0125mm, or sometimes you can choose not to use the coverlay, which requires careful consideration.
SEEKPCB is one of the flexible circuit manufacturers in China Committed to Challenge the manufacturing of various difficult PCBs and FPCs , The thinest FPC made by SEEKPCB is 0.058mm，More importantly, SEEKPCB is capable of ultra thin rigid PCB, This provides a more flexible solution for the design of electronic products.
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