The painted, base material of a motherboard is composed of fiberglass yarn strands that have been woven together and coated with a liquid resin, and then set to dry. This combination of woven fiberglass and resin is sent through an oven at a high temperature. When it comes out, it hardens and becomes stronger than it was before. This finished, very-hard, lightweight material, called pre-preg, is layered together and then painted, typically green. It forms what is the base material of the motherboard. This material acts as an electrical insulator and holds everything in place.