| 摘要 |
<p>Ammonium chloride and/or nitrate are used in a solution containing chloride and NH4OH. Pref. concentrations are chloride : 0.1 mol/l to saturation (specf. 0.375 mol/l); NH4 salt: 0.2 mol/l to saturation (spec. 1.5 mol/l); NH4OH: to pH 9.0 or above (spec. 3.0 mol/l). Alternatively the total chloride and/or nitrate concentration may be 1.0 mol/l and NH4HCO3 added to give 0.75 mol/l. The solution is pref. used (for etching printed circuits) at room temp. and as the copper in the solution builds up the temp. is gradually increased to 55 degrees C, with periodic NH4OH addition to maintain pH. When the amount of copper exceeds 45 g/l the solution may be aerated.</p> |
