The aim of this study was to characterize two different copper grades, oxygen-free copper, and phosphorous deoxidized copper, with aminofunctional silane layers on them and to study these silane layers as coupling agents in the injection-molded thermoplastic urethane-copper hybrids. The copper surfaces were as-received and modified, i.e., polished and oxidized. The copper surfaces and silane layers which were grown from solution concentrations of 0.25 and 0.5 vol% were studied with reflection absorption infrared spectroscopy (RAIRS), atomic force microscope (AFM), scanning electron microscope (SEM), and transmission electron microscope (TEM). The adhesive strengths of the copper-polymer joints were measured with peel tests and peeled surfaces were further studied with RAIRS, AFM, and FESEM. On the as-received copper surface, the silane layer was irregular and existed mainly in the surface roughness sites. This was the reason why hybrids manufactured with the as-received copper failed mostly in the silane layer. Hybrids manufactured with the oxidized copper sheets had a uniform silane layer and the hybrids failed mostly cohesively in thermoplastic urethane and had excellent peel strength values. In all silane-treated copper samples, Si-O-Si groups were formed confirming the cross-linking in the silane layer.