Chemical and structural changes at the ABS polymer-copper metal interface

Creating oxygen containing moieties (hydroxyl or carbonyl) on polymer substrate surfaces is known to increase the adhesion strength of polymers to metals. However, we noticed adhesion increase with time even though no pre- or post-treatment of the polymer substrate was done. In the case of sputtered and galvanically strengthened copper coatings on acrylonitrile-butadiene-styrene polymer (ABS) substrate, the adhesion strength increased from approximately 6 J/m2 to 53 J/m2 during a 1008-h period. During this period structural and chemical changes of the polymer near the interface take place. Carbonyl functionalities developed on the ABS surface are most likely responsible for the large increase in the adhesion strength. Chemical changes of the polymer are probably a consequence of the galvanic deposition and a close contact of ABS with copper which is known to facilitate the oxidation of ABS.