(PBT) is a thermoplastic engineering polymer that is used as an insulator in the electrical and electronics industries. It is athermoplastic (semi-)crystalline polymer, and a type of polyester.PBT is resistant to solvents, shrinks very little during forming,is mechanically strong. Polybutylene terephthalate is used for housings in electrical engineering, but also in automotive construction as plug connectors and in households for example in showerheads or irons.