Thermoset rigid laminates are composite materials in the "plastics" family. Generally speaking, plastic materials can be classified as either thermoset or thermoplastic. By definition, thermoset materials maintain their dimensional stability at elevated temperatures while most thermoplastic material melt (or lose dimensional stability) at elevated temperatures

Because thermoset materials maintain their dimensional stability at elevated temperatures, these materials have been used in electrical insulating applications. Electrical equipment tends to generate a tremendous amount of heat due to the concentration of moving electrons in a small space. The passage of electricity through electrical wires creates thermal energy or heat due to the resistance offered by copper or aluminium to the passage of electrons through their valence structures. Thus, the materials that insulate the copper or aluminium conductors must be able to withstand the thermal energy created without deforming or melting. For this reason, thermoset plastics find common application in electrical equipment and other applications where dimensional stability at elevated temperatures is required.

Thermoset rigid laminates are composite materials. By definition, composite materials consist of two or more materials. In the case of most thermoset rigid laminates, the primary materials include a substrate or base material such a paper, cotton cloth, or glass cloth along with a resin or adhesive such as epoxy, melamine, or silicone. To make a thermoset laminate, the base material is coated with the adhesive so that layers of material can be pressed into sheet form under heat and pressure.