Abstract: A method of manufacturing an aluminum substrate for printed circuits, comprises an oxide layer forming step and a heat-drying step. At the oxide layer forming step, an anodic oxide layer is formed on at least one surface of an aluminum plate by anodizing the aluminum plate in an electrolytic solution of phosphoric acid concentration: 3 to 20 mass % and bath temperature: not less than 25° C. but less than 40° C. At the heat-drying step, the anodic oxide layer is dried by heating it at 150 to 300° C. for 0.5 hour or more. According to this method, a proper oxide layer can be formed, resulting in an aluminum substrate for printed circuits capable of enhancing adhesiveness to a resin plate.

Abstract: Magnetic disk substrates are produced by subjecting glass substrates to at least steps of degreasing, etching, sensitization with tin chloride, activation and sensitivity-enhancing treatment in that order, then plating the pretreated substrates with a nickel/phosphorus film, and thereafter polishing the plated substrates. In the process, the substrates being processed are washed with hot pure water at a temperature of not lower than 50° C. for a period of from 20 to 90 seconds, after the sensitization step but before the activation step, and heated at a temperature of not lower than 70° C. for a period of from 5 to 100 minutes, after the sensitization step but before the nickel/phosphorus-plating step.

Abstract: A provision of a magnetic disk substrate using, as a plated substrate, glass with high hardness in place of aluminum. The magnetic disk substrate is small-sized, can stand against an impact when it is carried, and avoids leaving struck damages (head snap) even if it is used for recent note- or mobile-type computers having a head which is located as closely as possible to the substrate. The magnetic disk substrate comprises forming a nickel/phosphorus coating with a film thickness of 8 &mgr;m-20 &mgr;m or less on crystallized glass with a roughness Ra of 0.05 to 0.5 &mgr;m, the roughness being measured by a tracer and contact type roughness meter after the glass is ground (lapped) and polishing the nickel/phosphorus coating to a depth of 3 &mgr;m or more in a polishing process with the thickness of the plating film left unremoved being 5 &mgr;m or more.