Effect of the polymer on the joint strength of polymer/copper hybrids produced by nano-injection molding: Comparison of polybutylene terephthalate and polyphenylene sulfide via experimental and computational methods

Nano-injection molding is used in the automotive and mobile phone manufacturing industries to mass-produce polymer/metal hybrids with high joint strength. However, the polymer's effect on the joint strength of such hybrids has not been fully elucidated. In the present study, we selected polybutylene terephthalate (PBT) and polyphenylene sulfide (PPS) to investigate the polymers' effects on the joint strengths of polymer/metal hybrids, via experimental and computational methods. Scanning electron microscopy indicates that the interlocking effect that resulted from the flow of the polymer into the nanocavities ensured high tensile strength. Molecular dynamics simulations indicate that compared with the PPS/copper interface, the PBT/copper interface had a higher interfacial interaction energy and a higher maximum force in pull-out tests because of stronger van der Waals forces between the PBT and copper. The difference in joint strength between the two polymers was attributable to the rigidity of the polymer chains, which ensured greater detachment resistance. Therefore, this study offers insight into enhancing the joint strength of polymer/metal hybrids with a rigidity-driven joint.