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

 What are the benefits of gold, silver and other precious metals used on PCB?


The PCB surface needs to be welded, and a part of the copper layer is required to be exposed for welding. These exposed layers of copper are called pads, which are generally rectangular or circular and have a small area. We know that the copper used in the PCB is easily oxidized, so after brushing the solder resistance paint, the only thing exposed to the air is the copper on the pad.

If the copper on the pad is oxidized, it is not only difficult to weld, but also the resistivity is greatly increased, which seriously affects the performance of the final product. So engineers have come up with a variety of ways to protect the pad. For example, an inert metal is plated with gold, or the surface is covered with a layer of silver through a chemical process, or the copper layer is covered with a special chemical film to prevent contact between the pad and the air.

The exposed pad on the PCB, the copper layer is directly exposed. This part needs to be protected to prevent it from being oxidized. From this point of view, whether it is gold or silver, the purpose of the process itself is to prevent oxidation, protect the pad, so that it can ensure the yield in the following welding process.

However, the use of different metals will require the storage time and storage conditions of the PCB used in the production plant. Therefore, PCB factories generally use vacuum plastic sealing machines to pack PCBS before PCB production is completed and delivered to customers to maximize the protection of PCB oxidation damage.

Before the final component is welded on the machine, the board manufacturer must also detect the oxidation degree of a PCB, remove the oxidized PCB, and ensure the yield. The board that the final consumer gets has gone through various tests, and the oxidation even after a long time of use will almost only occur in the insertion and removal of the connection part, and it has no effect on the welding pad and the components that have been welded.

Since the resistance of silver and gold is lower, will the heat generated during PCB use be reduced after the use of special metals such as silver and gold?

We know that the biggest factor affecting the amount of heat generated is resistance. The resistance is also 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 pad is even far less than 0.01 mm, and if the pad is treated with OST (organic protective film), there will be no excess thickness at all. Such a small thickness shows that the resistance is almost equal to zero, and it can not even be calculated, and of course it will not affect the heat.

If you’re interested in PCB&PCBA products, pls kindly email to Sandy: sales9@hitechpcb.com


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