Solid state de-wetting of vapor deposited films on planar and fiber-shaped carbon substrates

In novel materials, the interface zone between their components is a point of crucial importance in respect to mechanical or thermal contact. Copper–Carbon composites are an example for this material class. They have a potential for an application as heat sinks in electronic components, but joining the two materials is difficult. Two critical processing steps determine the interfacial properties: first the deposition of Cu on the C surface at room temperature and second the heat treatment of the material during the compaction process. In this paper, we investigate the adhesive properties of Cu-films on planar C-substrates and the de-wetting of Cu from C during heat treatment. De-wetting occurs well below the melting point of copper. It starts with hole formation and ends with the decomposition of the Cu-Film into isolated droplets. A similar behavior is observed on Carbon-fibers. The above issues (interfacial adhesion and de-wetting) are investigated in dependence on several pre-treatment processes, which were applied to the C-surface such as plasma-modification or the deposition of intermediate layers. The basic mechanisms of adhesion promotion and de-wetting are identified and the consequences of the experimental findings for the manufacturing of Cu–C composite materials are briefly discussed.