| 摘要 |
<p>UNITED STATES PATENT APPLICATION OF: Fritz Stahl FOR: IMPROVED METHOD OF PROVIDING PRINTED CIRCUITS There is provided an improvement in the method of preparing printed circuit boards by chemically catalyzing the surface of an insulating material, electrolessly depositing a layer of copper thereon, masking selected areas of the copper layer not corresponding to the desired pattern of conductor lines, electrolytically depositing additional copper on the unmasked areas, removing the masking material and etching away the copper from the previously masked areas. The improvement comprises the steps of forming an etch-resistant protective layer of oxide on the surface of the electrolytically deposited copper layer before removing the masking material then removing the masking material and etching away the electrolessly deposited copper from the previously masked areas.</p> |
