Recyclable glass fiber-reinforced epoxy copper clad laminates for printed circuit board

Epoxy-based copper-clad laminates (CCLs) comprise >60% of the rigid CCL market, yet such CCLs are rarely recyclable at present. This paper describes the first industrialization of recyclable epoxy systems prepared with acetal-functionalized methylenebis(oxy)dianilines (MDAs) degradable curing agents, which make the corresponding CCLs recyclable and reuseable. We systematically studied the curing behaviors as well as the thermal and mechanical properties of these recyclable epoxy systems. All epoxy/MDA systems thermally decomposed at >288 °C, enabling their CCLs to pass the thermal stress test—currently unachieved with vitrimers. The cured networks degraded in acid via acetal hydrolysis to linear polymers. FR-4-type CCLs cured with the three MDAs met all IPC-4101/128 requirements, and their degradation products were reused to prepare Composite Epoxy Material (CEM)-3–type CCLs: a circular life cycle. We industrialized 2,2’-MDA-cured FR-4, including printed circuit board application testing and qualification, scaled-up degradation and recycling in CEM-3, Underwriters Laboratories certification, and standardization. Despite the significant increase in the demand for epoxy-based copper-clad laminates (CCLs), the implementation of recycling strategies remains underexplored. Here, the authors report on the curing behaviour and thermal and mechanical properties of epoxy systems prepared with acetal-functionalized methylenebis(oxy)dianilines degradable curing agents, demonstrating an industrialization-ready solution for recyclable epoxy systems for printed circuit board applications.