Alkaline matte cyanide-free silver plating solution and preparation method thereof

The invention discloses an alkaline matte cyanide-free silver plating solution and a preparation method thereof. The solution comprises the following components and conditions: 25-30 g/L of silver nitrate, 55-75 g/L of dimethyl hydantoin, 55-75 g/L of potassium pyrophosphate, 50-70 g/L of potassium carbonate and 30-45 g/L of boric acid, and the pH value is 9-10. The preparation method comprises the following steps: dissolving dimethyl hydantoin with water according to the volume concentration, neutralizing the solution with industrial pure potassium hydroxide with the mass fraction of 30-40% until the pH value is 8.5 or above, and sequentially adding other components according to the volume concentration to obtain the alkaline matte cyanide-free silver plating solution. The solution is simple in component, low in chemical raw material cost, wide in chemical raw material source, good in coating combination, stable in solution performance, simple in waste liquid treatment and capable of being stored for a long