Attention should be paid to silver plating in copper parts machining.

The metal structure of copper parts is more loose than that of rolled copper, and its appearance is rough and porous,in addition, the surface of copper parts is often left with a part of molding sand, paraffin wax and silicate substances. If the cleaning is not clean, it is often caused by partial plating, therefore, the surface cleaning of copper parts Machining and strengthening the appropriate process steps are the key to solve the silver plating quality of copper parts.

The general copper parts can be machined as follows:

alkaline chemical degreasing → hot water wash → water washing → dip 25% hydrofluoric acid → water washing → mixed acid corrosion → water washing → dip 5% lye → water washing → pre-plating copper → water washing → silver plating → water washing → passivation → water washing → remove the film → water washing → dip → water washing → hot water washing → drying → test.

Because of the loose and porous metal structure in the machining of copper parts, the process requirements must be strictly controlled:

(1) the cleaning of each process shall be thorough, and the solution remaining in the pores shall be prevented from affecting the next process;

(2) the actual surface area of copper parts is much larger than the calculated surface area. When electroplating, the impact current density is about 3 times higher than that of ordinary parts, and the time of pre plating is longer than that of general parts;

(3) when pre-plating, hanging parts connected together to often shake, to ensure the uniformity of coating color, appearance quality spots phenomenon affecting the coating prevent silver plating;

(4) when plating silver, the lower groove must be charged, and the impact current density is applied to electroplate the 5min under the premise of rocking the workpiece, and then change to the normal current density;

(5) silver plating after the passivation treatment to enhance the cleaning, the water flow in 10 ~ 20min, and then the hot water washing, drying oven immediately, control the temperature of 100 to 150 ℃, and a little longer, produce to prevent mildew.