Halogen free flame retardants for Epoxy substrate in electronic applications

Abstract

Epoxy resins together with glass fibers had been extensively used as the core substrate in electronic applications due to its superior mechanical properties and chemical resistance. Due to its application in high heat environment, flame retardants became a required additive for the epoxy resins to prevent any flame mishaps. In this paper, intumescent and nitrogen based flame retardants, specifically the ammonium polyphosphate (APP) and melamine cyanurate (MC) are utilized in the epoxy/glass fiber composite system. The main purpose is to achieve sufficient flammability properties without harming their mechanical properties and the environment. The flame retardant/epoxy/glass fibers composites were prepared using hand-lay up, followed by vacuum bagging process. For the APP, even as low as 5% is sufficient to achieve good rating under the UL-94 and limiting oxygen index (LOI) test, while MC required up to 20% to achieve similar results. Meanwhile, it was observed that the flame retardants also have some effect on the flexural strength and modulus. In conclusion, both flame retardants ammonium polyphosphate and melamine cyanurate are environmental friendly and can achieve similar or better results in terms of flammability properties compared to the halogenated flame retardants.