| 摘要 |
<p>1,234,475. Etching. WESTERN ELECTRIC CO. Inc. 6 Aug., 1968 [11 Aug., 1967], No. 37435/68. Heading B6J. Chromium is etched with a solution comprising 1-4 parts sulphuric acid, 4-16 parts phosphoric acid and 4-16 parts deionized water, for example, 1 part sulphuric acid 95- 98% H 2 SO 4 , 4 parts phosphoric acid at least 85% H 3 PO 4 , 4 parts water, the etching being initiated by touching at least one point of the chromium surface with a wire of aluminium, tin, magnesium, zinc, cadmium or alloys thereof. The reaction is ended by immersion in ammonium hydroxide. The solution is heated to 140‹ F. The chromium may be a coating on a glass substrate for use as a photolithographic mask.</p> |
