The microstructure and mechanical stability of the interface Cu-C/C of a Plasma Facing Component designed by PLANSEE has been investigated. A method to determine the resistance against thermal shock by means of mechanical loading has been developed. The phases emerging during the fabrication process and their effect on the microstructure of the interface have been studied and the influence of the quantity of wetting agent employed during fabrication on the interface morphology has been determined. Especially the existence of brittle intermetallic phases was of utmost interest. The amount of wetting agent also influences the compounds resistance against thermal shock. The interrelationship between the microstructure and the mechanical properties of the joint has been investigated to allow a better understanding of the failure mechanisms in the interface region. For this purpose the fracture surfaces of tested samples have been studied and conclusions on the crack path have been drawn. By combining the results of the microstructure analysis with the found crack path and the mechanical properties an extensive comprehension of the components performance has been obtained.