Adhesion and adhesion changes at the copper metal–(acrylonitrile–butadiene–styrene) polymer interface

It is known that the adhesive strength of metallic films on polymer substrates often changes in the course of time. To study this effect in more detail, the adhesion energy of sputtered and galvanically strengthened copper coatings on acrylonitrile–butadiene–styrene polymer substrate was determined as a function of storage time. The adhesion energy is initially only about 6 J/m2, because of water introduced to the interface during the galvanic deposition process. Within about 48 hours most of the water disappears leading to a relatively rapid increase of the adhesion energy to a value of approximately 23 J/m2. Thereafter, an increase, albeit at a lower rate, was still measured and at the end of the study (1008 hours) adhesion energy of about 54 J/m2 was found. The increase during the latter period is attributed to structural rearrangements taking place near the interface.