Esca and Sims Study of the Tetrabromobisphenol A Flame Retardant Diffusion to the Metal-Encapsulating Resin Interface

Epoxy resins of novolac type were molded to real copper and nickel plated copper framesin plant conditions. Three resins, formulated with different amount of tetrabromobisphenol A flame retardant, were used. The samples were stored at 200°C and then mechanically fractured at given time intervals. The surfaces obtained in the fracture have been analyzed by ESCA and Ga+ excited static and imaging SIMS. The kinetics of migration of the flame retardant to the resinmetal interfacial zone have been followed. The process was found to be diffusion controlled. Evidence of a redox reaction between the copper oxides found on the surface of the copper frame and the tetrabromobisphenol A was obtained. A copper diffusion through the Ni plating was observed in the case of the nickel plated frames. This phenomenon is most important at the point on the frame where the bromine concentration is higher.