Abstract: The disclosure relates to insulated metal substrates and to a process for producing these substrates. These substrates have an aluminium base, an insulant constituted by an alumina film obtained by anodizing at least one of the faces of said base and at least one metal film which is to be transformed by chemical etching into a network of conductors. The alumina film is formed by a uniform compact zone adhering to the aluminium and having a thickness in excess of 500 nm and a porous layer with a rough outer surface. The process of making these substrates includes a step during which at least one of the faces of the aluminium base undergoes a treatment in a porous anodization layer forming bath and then in a barrier anodization layer forming bath. The invention is used in the production of substrates for single face, double face, with metallized holes, and multilayer conductive circuits. The substrates produced have a planar or non-planar configuration, and may also have resistive networks.

Abstract: The disclosure relates to insulated metal substrates and to a process for producing these substrates. These substrates have an aluminium base, an insulant constituted by an alumina film obtained by anodizing at least one of the faces of said base and at least one metal film which is to be transformed by chemical etching into a network of conductors. The alumina film is formed by a uniform compact zone adhering to the aluminium and having a thickness in excess of 500 nm and a porous layer with a rough outer surface. The process of making these substrates includes a step during which at least one of the faces of the aluminium base undergoes a treatment in a porous anodization layer forming bath and then in a barrier anodization layer forming bath. The invention is used in the production of substrates for single face, double face, with metallized holes, and multilayer conductive circuits. The substrates produced have a planar or non-planar configuration, and may also have resistive networks.

Abstract: This invention relates to a process for identifying the external surface or surfaces of an Al alloy of a homogeneous or composite material by electrochemical means. This method involves forming an anodic layer, in situ, on the products to be identified, by electrolysis under predetermined conditions and following or plotting the development of the voltage U at the terminals of the electrolyzer as a function of time t during an intentiostatic test. The shape and relative position of curves U=f(t), thus obtained, allows the various alloys tested to be identified from a comparison of the derived curve from a curve U=f(t) derived from a known sample. The present method has advantages over the earlier methods of marking in that it provides: non-destructive method employable in situ on products which may have large dimensions (coils, plates, sheets, etc.); almost instantaneous identification; high reliability; and is simple and economic to use.