Prepeg is the abbreviation for Preimpregnated and means pre-impregnated. The term prepeg is used in PCB technology for pre-impregnated intermediate layers of multilayer PCBs and HDI PCBs
. Prepregs are flexible laminates
consistingof resin and glass fibre
. They arebetween 50 µm and 175 µm thick and act as a kind of adhesive between the solid core layers. After lamination, the adhesive hardens.printed circuit boards. The resin content of prepregs depends on the prepreg type and is between 75 % and approx. 50 %. To ensure that the characteristic HF properties of the PCBs are not impaired, prepregs must have the same flame resistance as the core boards.