Polyimide on copper: The role of solvent in the formation of copper precipitates

The interaction at the polyimide-copper (oxide) interface has been investigated by means of cross-sectional transmission electron microscopy. By using a solventless molecular beam epitaxy growth technique, the role of solvent in the aggregation and diffusion of copper-rich particles into the polyimide film and away from the interface was unambiguously demonstrated. The polyimide on copper growth sequence is contrasted to the copper on polyimide growth sequence, and the reasons for the differences between the two growth interfaces are discussed.