Design and evaluation of bioepoxy-flax composites for printed circuit boards

Printed circuit boards (PCBs) pose considerable occupational health risks during manufacturing and are a potential source of toxic hazards if improperly disposed at the end of their useful life. Indeed, base materials in current PCBs include epoxy resins, fiberglass, and brominated flame retardants. To improve the environmental performance of PCB manufacturing and disposal, we developed composite designs using a thermosetting matrix based on epoxidized linseed oil, melamine polyphosphate for flame retardance, and woven flax fiber for reinforcement. Analyses of our prototypes using IPC 4101A/24 specification for thick PCB laminates gave acceptable results for thermal, mechanical, and electrical properties, except for wet conditioning or water submersion. To improve moisture resistance, we treated flax fibers with sodium hydroxide and octadecyltrichlorosilane. We find that the improved bioepoxy-flax PCB design is a viable alternative to current PCBs; it has potentially lower environmental impacts, it is cheaper, and it has satisfactory thermal, electrical, and mechanical properties. However, additional improvements in moisture absorption properties may remain needed for commercial applications.