Polyimide (sometimes abbreviated PI) is a polymer of imide monomers. Polyimides have been in mass production since 1955. With their high heat-resistance, polyimides enjoy diverse applications in applications demanding rugged organic materials, e.g. high temperature fuel cells, displays, and various military roles. In PCB industry, polyimide provides a solution for printed circuit board designs that require increased thermal performance, higher operating temperatures and severe environment capability, and Kapton is a classic polyimide which is used frequently. However, there are some technical issues with Polyimide that EPCB wants you to be mindful of. Most of these laminates and prepregs are available in Brominated and Non-Brominated blends. An issue to be careful about is the moisture absorption characteristics, as Polyimide can exhibit higher leakage as compared to FR-4 resin systems.