A surface-treated copper foil which maintains peel strength against the resin substrate of the surface-treated copper foil and achieves desired low transmission loss even at high frequencies includes an electrolytic copper foil, at least one roughened layer that covers one surface of the electrolytic copper foil, an anti-rust layer that covers the at least one roughened layer, and a silane coupling agent-treated layer that covers the anti-rust layer, in which a surface of the surface-treated copper foil on a side of the layers has a developed interfacial area ratio Sdr of 40% or less, an arithmetic mean peak curvature Spc of 200 mm-1 or less and a root mean square gradient Sdq of 0.30 to 0.90, or particles on the surface to be bonded of the surface-treated copper foil have an average particle size of 0.50 m or less and an average particle length of 0.40 to 0.70 m.

A load-bearing structure is disclosed and configured to, during operation of the structure, transfer load from a first part of the structure to a second part of the structure via a load path. The component includes a matrix material, a plurality of longitudinal first reinforcing elements embedded in the matrix material, and a plurality of longitudinal second reinforcing elements embedded in the matrix material. The long axis of each first reinforcing element is substantially aligned with a first direction and the long axis of each second reinforcing element is substantially aligned with a second direction, the second direction being substantially perpendicular to the first direction. The structure has a predefined crack-propagation region configured to control the propagation of a crack in the structure. The crack-propagation region either comprises multiple first reinforcing elements and does not comprise any second reinforcing elements; or comprises multiple second reinforcing elements and does not comprise any first reinforcing elements.

Disclosed are surface-treated copper foils having at least one treated surface that exhibit high conductivity and a set of surface properties. Also provided are flexible copper-clad laminates and printed circuits made therefrom. The present printed circuits exhibit low insertion loss and are suitable for use in high speed/high frequency applications.

Disclosed are surface-treated copper foils having at least one treated surface that exhibit high conductivity and a set of surface properties. Also provided are flexible copper-clad laminates and printed circuits made therefrom. The present printed circuits exhibit low insertion loss and are suitable for use in high speed/high frequency applications.