What is Gold Plating?

Gold plating is a decorative technique and one of the commonly used words. Originally, the surface of the utensil was plated with a thin layer of gold. Later, it was also used as a metaphor for people going to a certain environment for further study or exercise just to obtain a false name.

Tang Dynasty

Gold plating is divided into two categories, one is gold plating of homogeneous materials, and the other is gold plating of heterogeneous materials.

The quality of gold plating depends on the thickness of the gold plating layer and the brightness and darkness. Now internationally accepted

According to the characteristics of its gold plating, there are two types: cyan-free gold plating and cyan-gold plating. The cyanide bath is divided into high cyanide and low cyanide bath. The cyanide-free plating solution is more commonly used as a sulfite plating solution.

According to its concentration, the gold plating solution is generally acidic, and its gold content is low, which can reach 0.4 to 0.5 g / L. The cost of this plating solution is low, so the loss caused by the solution is small. The color of the gold layer obtained by this plating solution is cyan-gold, which is especially suitable for large plating batches and low processing costs. It also requires gold-plated hardware such as buttons and belt buckles.

According to the function of the gold plating solution, the presence of pre-plating means that the pre-plating is performed in a specific gold plating solution before the gold plating, and then the normal gold plating process is transferred. There are several major benefits of re-plating after pre-plating:

1) Ensure the bonding force of the gold-plated layer.

1. Gold potassium cyanide: supply electroplated gold ions.

2. Potassium cyanide: Generates free cyanide, decomposes gold cyanide compounds, increases electrical conductivity, and prevents the deposition of copper and nickel.

3. Potassium carbonate: It increases the conductivity and is used as a buffer.

4. Dipotassium bicarbonate: It acts like potassium carbonate.

The appearance of the gold-plated layer is golden yellow, which has high chemical stability. It is only soluble in aqua regia and other super strong acids, and insoluble in other acids. The atomic valence of gold is monovalent and trivalent. The standard potential ° Au + / Au of monovalent gold is + 1.68V, and the standard potential ° Au3 + / Au of trivalent gold is + 1.50V. For steel, copper, silver and their alloy substrates, the gold coating is

The advantage of electroless gold plating is that the part to be plated does not require electrical connection, and the plating is uniform, which is more suitable for surface mounting. The disadvantage is that the solution is difficult to maintain. The chemical nickel used for the bottoming must be washed regularly to remove the nickel deposited on the surface of the groove, which causes discontinuity in production. Operating costs are also higher. The hardness and abrasion resistance of the electroless gold plating layer is worse than that of electroplated hard gold, and the thickness that can be achieved is limited, which is not suitable for some surface mount welding methods. To compensate for this shortcoming, electroless nickel-plated palladium is also used instead of electroless nickel-gold to suit various surface-mount soldering methods.

The advantages and disadvantages of electroplated gold are the opposite. Electroplated gold (hard gold) has better hardness and abrasion resistance than chemical gold plating, and the solution is easy to maintain. It does not require washing tanks and can be used for various surface mounting welding methods. The main disadvantage is that the thickness is not uniform and the parts to be plated need electrical connection.

Chemical gold and electroplated gold each have their uses, depending on which customers they serve.