| 摘要 |
1502975 Etching PERSTORP AB 5 Sept 1975 [27 Sept 1974] 36747/75 Heading B6J [Also in Division H1] A metal, e.g. copper and zinc, coated insulant printed circuit laminate is coated with an adherent protective layer of plastics or metal, e.g. aluminium, nickel, chromium, tin, lead or their alloys, chemically different from the metal coating, and the laminate is drilled or punched for through holes, the protective layer reducing burr formation and enabling any burrs to be etched off; after which the protective layer is removed. The etchant attacks the burrs but not the protective layer, and may be ammonium persulphate + dilute nitric acid, or dilute hydrogen peroxide and dilute sulphuric acid, or dilute sulphuric acid and chloride ions with electrolysis. The laminate may be formed by applying a film conductor metal formed on a temporary base of aluminium, nickel, chromium, tin or lead, or an alloy thereof, with an intervening adhesive layer, the temporary base being later removed, e.g. by etching and serving as a protective layer during drilling or punching the through holes. The prepared laminate may then be etched and plated to provide the circuit tracks and plated through holes. The protective layer may be applied by adhesion or by vacuum evaporation, chemical plating, or electroplating. The insulant base may be GRP, polyester resins, or polyamide resin. Practical examples are quoted. |
