With the rapid development of modern information industry and electronics industry, the printed circuit board industry is developing rapidly. The copper circuit surface of the printed circuit board is easy to oxidize and has poor solderability. The most reliable method is to plate the printed circuit board with gold, thus giving birth to Gold-Plated PCB.

Because the atoms at the interface between copper and gold are easily interpenetrated, the hardness of gold is low. The general process is to plate the copper matrix with a layer of nickel and then plate with gold. Nickel is harder than copper and can provide a harder layer for the gold plating. The substrate can improve the wear resistance of the gold plating layer. In addition, the standard electrode potential of nickel is lower than that of copper. Therefore, the nickel coating is an anodic coating for copper and has an electrochemical protective effect on the copper substrate. Nickel is a reliable barrier layer that can prevent the diffusion of the base copper to the gold plating layer, thereby improving the corrosion resistance of gold.

Nowadays, the Gold-Plated PCB process generally includes the following steps between the image transfer to the copper foil and the nickel plating process: pattern plating of tin-lead alloy to form patterned circuit protection layer, film removal, etching, tin-lead alloy, Then the copper surface is activated. The existing method is used to plate the printed circuit board with gold. Since the printed circuit board is only partially activated, the process conditions are quite harsh and difficult to control.

Gold-Plated PCB can be roughly divided into two types of gold plating methods and applications. One is terminal plating, which is mainly used for products that require frequent insertion and removal of electronic products. For example: Gold finger plating of adapter cards is a typical example. This type of gold plating uses alloy electroplating for surface treatment. The content of gold is not pure but contains some impurities, so as to improve the wear resistance of the plating layer.

But a kind of gold electroplating belongs to soft gold electroplating. The main purpose of this kind of electroplating is wire bonding. Therefore, the purity of gold plating should be high, and the general requirement of thickness is also high, and the unit price is relatively high. In addition, the chemical gold is divided into two types: replacement gold and reduced gold. The method of replacing gold is to perform redox replacement of gold ions with the surface metal of the circuit board, so the surface metal will precipitate. As for reduced gold, the reducing agent in the chemical solution is used to directly reduce the gold to precipitate the gold to the surface of the circuit board. Reduced gold will not be affected by the gradual sealing of the surface of the circuit board that is difficult to react, so the thickness of gold that can be produced is wider. Whether it is electroplated gold or reduced gold, it is basically an electrochemical reaction.

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