How's FR4 Made ? STD PCB Laminate

How's FR4 Made:-

FR4 is made from sheets of Prepreg, which is itself constructed from fibre glass matting which has been impregnated with the epoxy resin. A standard 1.6mm circuit board is made up from 8 layers of Prepreg and the outer copper layers. The Prepreg and outer copper foil layer are stacked up together and placed into a large press which bonds all the layers into the final laminate. The copper foil is made on a slowly rotating stainless steel drum dipped into a copper plating solution. As the drum turns copper is electroplated onto the drum, which is then stripped off as the plated section leaves the solution. The glass cloth is literally made by weaving fine strands of fibre glass yarn together. The yarn is in turn made from small threads of glass twisted together. Its the toughness of the glass in the cloth that give the laminate it's strength, and also the ability to take the edge off a steel drill bit in seconds. The epoxy resin is normally made from ethylene chlorohydrin [epichlorohydrin] and bisphenol-A. Once made the resin almost indestructible apart from high temperatures or strong oxidising solutions.




FR4 Laminate	Technical Main