Polybutylene terephthalate (PBT) is a plastic that is used as an insulator in the electrical and electronics industries. It is a thermoplastic crystalline polymer, and a type of polyester. PBT is resistant to solvents, shrinks very little during forming, is mechanically strong, heat-resistant up to 150°C (or 200°C with glass-fibre reinforcement) and can be treated with flame retardants to make it noncombustible.