Bio-based resins for the manufacture of printed wiring boards

Printed wiring boards (PWB) are epoxy/fiberglass laminates onto which electrical components are mounted. Laminates used in PWB's must meet a wide range of requirements for performance and reliability, including a glass transition temperature (Tg)≥110°C, low water absorption, high thermal stability, flame retardancy and good dielectric properties. Replacement of the currently used petroleum based epoxy resin components with bio-based materials would reduce the environmental concerns with the fabrication, assembly, and disposal of PWB's. Lignin, a by-product of paper manufacturing, is the only common phenolic-based biopolymer. It is naturally hydrophobic and has good thermal stability. Initial resin formulations which contain at least 50% lignin exhibit acceptable thermal and electrical properties for PWB applications. Laminates formed from lignin based resins can be processed in a similar fashion to current laminates, minimizing the financial considerations of converting to this resin system.