Abstract: An aqueous copper etching solution is disclosed, containing customary acid etching means based upon iron chloride, copper chloride or peroxide compounds, characterized by an additional content of halogen compounds, preferably of the formula AX, in which A is hydrogen, ammonium or a univalent metal equivalent, and X is a halogen atom, and also a process for the adhesive application of contacts onto conductor plates having one or more metal cores, in particular iron-nickel or iron-cobalt cores, including the steps of etching the conductor plates with the mentioned copper etching solution, with or without an addition of organic compounds based upon aliphatic amines or alcohols, thioureas, aromatic thio-compounds, pyridinium compounds, pyrimidinium compounds, alkoxylated alcohols or phenols, at room temperature, then rinsing, activating and chemically metallizing the conductor plates. The contacted conductor plates prepared in this manner are employed in electronics and electrical engineering.