FPC substrates can be divided into two types: rolled copper and electrolytic copper. Rolled copper has good flexibility and resistance to bending, but it can withstand less overcurrent than electrolytic copper; Electrolytic copper has a harder texture and lower flexibility compared to rolled copper, but it can withstand high overcurrent and is generally used in power supply.

From the number of layers, it can be further divided into single-sided substrate and double-sided substrate. The single-sided substrate is composed of polyimide resin and PI, which are pressed onto copper foil on one side. If the pressed surface contains adhesive, it is called adhesive based rolling or adhesive based electrolysis. If there is no adhesive, it is called adhesive based rolling or adhesive based electrolysis. The main difference between adhesive and non adhesive is the different adsorption capacity and breakdown coefficient between copper foil and insulation PI.

As for the thickness, copper foil has 1oz (35um), 0.5oz (18um), 1./3oz (12.5um), and insulation PI thickness is generally 12.5um and 25um. The thickness of the substrate mainly includes three different thicknesses: 35/25, 18/12.5, and 12.5/12.5.