Adhesion of metal/polymer bonds using PBT, PC, PS and copper

The extension of the functional features of electronic devices leads to the growing application of new materials especially compound materials. Polymers stand for an innovative potential due to their favorable properties for packaging. The MID technology represents a new growing potential in packaging (Forschungsvereinigung and Feldmann, 2004) and Weiss 2005). Metal/polymer bonds are the basis of this technology. The adhesive strength is a critical factor for the quality and reliability of these bonds. For the adhesion improvement the plasma treatment of the polymer surface wins a key position (Friedrich et al., 2002). Polybutylene terephthalate (PBT), polystyrene (PS) and polycarbonate (PC) were chosen as substrate materials in this work. The metallization of these polymers was realized after oxygen plasma treatment and by thermal evaporation in a high vacuum. The polymer surface composition was analyzed by X-ray photoelectron spectroscopy (XPS). A modified cross hatch tape test was used to determine the adhesion strength of the copper coating as function of different plasma treatment times. Results show that a different amount of polar groups on the polymer surface are the reason for the high copper adhesion