Copper-tin-iron ternary alloy plating solution formulation process

Characteristics: The described plating solution introduces iron elements on the basis of increasing the tin content, alleviating the deficiency of copper-tin alloys in terms of protection performance. The main difference with the single metal electroplating solution is that in addition to obtaining a finely crystalline coating in the alloy plating solution, each element in the alloy coating can be deposited in a certain proportion to obtain the predetermined performance. By adding an auxiliary complexing agent, the tin-iron alloy is co-deposited. The co-precipitation formed by tin and iron can effectively improve the wear resistance and corrosion resistance of the coating on the basis of ensuring the oxidation resistance of the coating.

Usage and usage: This product is suitable for electroplating of zinc, aluminum, zinc alloy or aluminum alloy.

So it also includes the treatment of zinc, aluminum, zinc alloy or aluminum alloy before electroplating. Such as activation of zinc or zinc alloy, alkali etching, acid etching, zinc immersion, dezincification and secondary zinc immersion treatment of aluminum or aluminum alloy.

The electroplating method of this product is to place the parts to be plated as the cathode in the plating solution of this product for electroplating, and the copper-tin alloy as the anode.

This product is generally suitable for electroplating of zinc, aluminum, zinc alloy or aluminum alloy. So it also includes the treatment of zinc, aluminum, zinc alloy or aluminum alloy before electroplating. Such as activation of zinc or zinc alloy, alkali etching, acid etching, zinc immersion, dezincification and secondary zinc immersion treatment of aluminum or aluminum alloy.

The activation process is used to remove the oxide film on the surface of the zinc alloy substrate, thereby improving the bonding force between the subsequent plating layer and the substrate. The activation method can be as follows: provide 1% to 2% (mass fraction) of sulfuric acid and 1% to 2% of sodium fluoride, and completely place the zinc alloy matrix in the above solution at 10 to 35°C. Soak for 0.5～1min.

The acid etching refers to that after the aluminum alloy is immersed in the prepreg solution for a period of time, the surface oxide and the enriched silicon element can be effectively removed to obtain a pure metal matrix. The prepreg solution is composed of 40～60g/L sodium hydroxide and 90～120g/L ammonium bifluoride. The purpose of sodium hydroxide is to further remove grease, remove the natural oxide film on the surface and slight scratches. The role of ammonium bifluoride is to remove Silicon on the surface of the substrate.

The acid etching refers to the pre-soaked aluminum alloy with a gray or black uneven film layer on the surface. The film layer can be removed by immersing the film removing solution to make the surface uniform. The etching solution consists of 30%-40% (volume fraction) of nitric acid, 50%-70% (volume fraction) of phosphoric acid and 5-30g/L of ammonium hydrogen fluoride. Phosphoric acid and ammonium hydrogen fluoride can more completely remove silicon close to the substrate. To enhance the bonding force of the subsequent electroplating layer, the treatment temperature is 20～35℃, and the treatment time is 20～40s.

The zinc immersion solution for the zinc immersion reaction is an aqueous solution of zinc oxide, sodium hydroxide, potassium sodium tartrate, ferric chloride and sodium nitrite. Among them, the content of zinc oxide is 20 to 60 g/L, and the content of sodium hydroxide is 100 to 130 g/L. L, the content of potassium and sodium tartrate is 40-60g/L, the content of ferric chloride is 0.5-2.5g/L, and the content of sodium nitrite is 0.5-4g/L. The temperature of the zinc immersion reaction is 20-28°C, and the time is 40-120s.

In some cases, local residual non-conductive impurities on the surface of the substrate affect the bonding force of subsequent electroplating. For example, cast aluminum and forged aluminum contain a large amount of silicon, and electroplating is difficult, and the residual silicon impurities need to be completely removed. In this way, we will perform secondary zinc immersion, which is to perform zinc immersion after the first zinc immersion. While removing zinc, the residual impurities are stripped together to obtain a better substrate surface, and then the secondary zinc immersion is performed. The zinc stripping solution for zinc stripping is: nitric acid 400～550mL/L nitric acid solution. The conditions for stripping are: working at room temperature for 5-10s. The zinc immersion liquid and temperature used in the second zinc immersion are the same as those used in the first zinc immersion, except that the time is 10-20 seconds. The solution used can be prepared by yourself, or a commercially available solution can be used.