PCB surface technology_Shenzhen StarLight Industrial Development Co., Ltd.

PCB surface technology

source:Other information release time:2023-06-02 Hits: Popular:PCB Assembly company: Share:

　　Electroplated nickel gold

　　Electroplating nickel gold is the ancestor of PCB surface treatment technology, which has emerged since the emergence of PCBs and gradually evolved into other processes. Electroplating nickel gold refers to electroplating a layer of nickel on the surface conductor of a PCB before electroplating a layer of gold. Nickel plating mainly prevents the diffusion between gold and copper. There are two types of nickel gold electroplating: soft gold plating (pure gold, the gold surface does not look bright) and hard gold plating (the surface is smooth and hard, wear-resistant, contains cobalt and other elements, and the surface looks brighter). Soft gold is mainly used for making gold wires during chip packaging; Hard gold is mainly used for electrical interconnections in non welded areas (such as gold fingers).

　　Under normal circumstances, welding can cause embrittlement of electroplated gold, which will shorten its service life. Therefore, it is necessary to avoid welding on electroplated gold; However, due to the thin and consistent nature of gold, the phenomenon of embrittlement rarely occurs in electroless nickel plating/gold immersion.

　　Electroless palladium plating

　　The process of electroless palladium plating is similar to that of electroless nickel plating. The main process is to use a reducing agent (such as sodium dihydrogen hypophosphate) to reduce palladium ions on the catalytic surface to palladium. The newly formed palladium can be called the catalyst driving the reaction, thus obtaining any thickness of palladium plating layer. The advantages of electroless palladium plating are good welding reliability, thermal stability, and surface smoothness. The disadvantage is that palladium is a relatively rare precious metal, which increases its cost.

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