<p>Free-standing copper (Cu) nanowire (NW) arrays have potential applications in batteries, sensors, and electrical and thermal management systems. However, the effects of geometric factors, such as the length, diameter, and growth filling ratio of Cu NWs, on their collective mechanical properties and bonding strength to substrates have not been thoroughly examined. In this study, it was found that the maximum effective modulus of the Cu NW arrays decreased from 23.8 ± 0.7 GPa to 8.6 ± 0.1 GPa as their length increased from 6.21 to 22.35&#xa0;<i>µ</i>m. Moreover, the interfacial energy per unit area between the Cu NWs and the Cu substrate was measured to be as high as 544.87&#xa0;J/m², which is significantly higher than that of other one-dimensional nanomaterial arrays. The findings from this study provide fundamental insights and references for the design, fabrication, and failure analysis of components in devices based on Cu NW arrays.</p> Graphical abstract <p></p>