What are the differences between gold-plated and silver-plated processes on PCB boards?

 Let's first clarify the colors and then move on to the precious metals used on PCBs. Some manufacturers will specifically mention that their products adopt special processes such as gold - plating and silver - plating when promoting their products. So, what are the uses of such processes?

The surface of a PCB needs to have components soldered on it, which requires a part of the copper layer to be exposed for soldering. These exposed copper layers are called solder pads. Solder pads are generally rectangular or circular and have a small area. As we know, the copper used in PCBs is extremely prone to oxidation. Therefore, after applying the solder mask, the only copper exposed to the air is on the solder pads.

If the copper on the solder pads is oxidized, it will not only be difficult to solder but also have a significantly increased resistivity, seriously affecting the performance of the final product. So, engineers have come up with various ways to protect the solder pads. For example, plating them with the inert metal gold, covering the surface with a layer of silver through a chemical process, or using a special chemical film to cover the copper layer to prevent the solder pads from contacting the air.

The exposed solder pads on the PCB have the copper layer directly exposed. This part needs protection to prevent it from being oxidized. From this perspective, the purpose of both the gold - plating and silver - plating processes is to prevent oxidation and protect the solder pads, ensuring a high yield rate in the subsequent soldering process.

However, using different metals will impose requirements on the storage time and storage conditions of the PCBs used by the production factory. Therefore, PCB manufacturers generally use a vacuum packaging machine to package the PCBs before delivering them to customers, to maximize the prevention of oxidation damage to the PCBs.

Before the final component mounting and soldering, the board card manufacturers also need to detect the oxidation degree of the PCBs and eliminate the oxidized ones to ensure the yield rate. The board cards that end - consumers receive have undergone various tests. Even after long - term use, oxidation will almost only occur at the plug - in connection parts and will have little impact on the solder pads and the soldered components.

Since silver and gold have lower resistances, will the use of special metals such as silver and gold reduce the heat generation of the PCB during use?

We know that the biggest factor affecting heat generation is resistance. Resistance is related to the material of the conductor itself, the cross - sectional area, and the length of the conductor. The thickness of the metal material on the surface of the solder pads is even less than 0.01 millimeters. If the solder pads are treated with the OST (Organic Solderability Preservative) method, there will be no additional thickness at all. The resistance shown by such a tiny thickness is almost equal to 0 and even cannot be calculated, so it will certainly not affect the heat generation.

For furhter information, pls feel free to contact us: sales9@hitechpcb.com Website: www.hitechpcb.com



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