Etching soln. based on potassium ferricyanide and soda - for selective removal of photo:lacquer or metal films obtd. by vapour deposition, esp. in mfg. thin film circuits

摘要

The etchant consists of an aq. soin. contg. Na 2CO3; potassium ferricyanide; potassium peroxydisulphate; tri-potassium citrate; and aluminium hydroxyacetate or sodium acetate. The pref. soln. uses 1 litre of water in which are dissolved 0.5-1120 g Na 2CO3;0.5-420 g potassium ferricyanide; 0.5-50 g potassium peroxydisulphate; 0.5-45 g tri-potassium citrate; and 0.01-2 g aluminium hydroxyacetate of sodium acetate. The etchant is pref. used to create thin film structures, the etching temp. being varied to increase the selectivity of the etchant. Used for mfr. of resistance- or RC- networks; liq. crystal displays; thin film microcircuits etc.