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PCB plating – layers that ensures solderability and protects circuits from corrosion

PCB-plating---ensures-solderability-and-protects-circuits-from-corrosion

In general, PCBs or printed circuit boards are a hub of electrical tracks and traces that connect several electronic components embedded in the PCB. It is important to note that the operations of different electronic devices depend significantly on PCBs. But why are PCB plating in the first place? Let’s discuss why.

What is PCB plating?

What-is-PCB-PlatingWhen it comes to PCB plating, one can comprehend it as a process that involves the deposition of a metal on the PCB. This deposition of metal helps in protecting it from oxidation. There are different metals that are used for PCB plating such as copper, tin, and nickel among others. However, the choice rests in the hands of the user because different metals have their own unique properties and characteristics.

What is meant by copper plating?

In simple words, copper plating refers to the process of depositing copper on a board to make sure that it is protected from corrosion and deterioration. At the same time, it is performed to offer an accurate soldering surface and improved electrical connectivity.

Why are PCBs plated?

Typically, printed circuit boards are plated or coated for their protection. Moreover, a preferred material’s surface finish is considered for the process of plating. It should be noted that it facilitates component soldering and also secures exposed metal on the board. Not to mention, it even prevents corrosion.

PBC is generally quite sensitive to moisture. In fact, it can corrode easily. Without plating, the board can lose its functionality. Therefore, plating is used to ensure that the board is protected from these problems. At the same time, it even serves to make it more visually appealing.

Usually, when the process of plating is carried out, it plays an important role in decreasing downtime and even the boards’ overall costs.

How PCB plating is done?

Typically, a PCB involves a combination of different non-conductive and conductive materials. These materials are often arranged in several layers to offer electrical connectivity.

Out all other metals, copper is quite common and from the pairs of inner layers, it will be etched. When inner layers are completed, their lamination is performed. Then, necessary holes are drilled into the board for components. After that, the board will be prepared for PCB plating.

How-PCB-Plating-is-DoneFor coating a layer of the preferred metal to PCB chemically, it should be noted that an electroless procedure will be carried out. It includes the interior of drilled holes as well. After that, the board is prepared so that electroplating can be carried out without experiencing any difficulties. For instance, the holes will be cleaned of residues and contaminants, micro etching will be used in the interior of holes, and pliable photoresist will be washed off.

After cleaning, the PCB will be completely prepared for electroplating to be performed on not only the holes but also the external layers. The board will be linked to a cathode and it will obviously have a negative charge. Then, the board will be placed in a bath to make sure that the process of electroplating can be performed.

As soon as it is placed in the bath, copper will begin deposition on all the exposed circuitry of the board. In order to perform or carry out electroplating, it is essential for the board to be placed in a chemical bath. Otherwise, it will not work.

To secure the circuitry, tin will be used and considered for plating and once the photoresist has been removed, tin will also be eliminated or removed.

What is PCB plating thickness?

PCB plating thickness generally indicates the thickness of the coating. It is important because the durability of a coating relies on its thickness. For instance, more protection is offered by thicker coatings. In contrast, uneven or thinner coatings cause the material to be exposed to deterioration and corrosion, which can result in premature failure.

The normal values of PCB plating thickness are around 100 micro-inches and for OSP and immersion silver, it can even lower to 10 micro-inches. You can just convey the plating thickness you require and the PCB manufacturer will deliver it.

What are the different methods of plating?

What-are-the-Different-Methods-of-PlatingReel Linkage Selective Plating, Finger-Plated Plating, Brush Plating, and Through-Hole Plating are generally the four primary techniques or methods considered for PCB plating.

Reel-Linkage Plating: When it comes to reel-linkage method, it should be noted that allows selective deposition. For instance, if you want to focus on the plating of certain components like ICs and connectors, you can definitely consider this technique.

These components are plated specifically for high corrosion resistance and contact resistance. It is possible for this method to be either automatic or manual. Batch welding is often considered because it can be rather costly to select a specific pin.

Finger-Plating: On the other hand, this technique is completely different and it has another name of protruding partial plating. In this method, different rare metals are considered and utilized for plating specific parts such as connectors and gold fingers among others.

Brush Plating: Brush plating is a portable technique and it is utilized widely for the application of the anodized coating and electroplated deposits on PCBs. It is important to note that in this process, immersion tanks are not really used. During the process of plating, not all parts are generally dipped in the electrolyte.

Through-Hole Plating: In order to facilitate the process of drilling, you need to consider this method. It involves the use of electroless plating to make sure that inner walls of all the holes on the board are made conducive.

How to choose PCB plating for your finished board?

Actually, there exist several plating options and you can select the most suitable one from them. However, there are some specific factors you need to consider such as your budget, the scope of your project, and even the size of your project. Depending on these factors, you can select the PCB plating that suits your finished board the best.

What are the common plating metals in PCB manufacturing?

Some common plating metals that are used for plating boards include copper, tin, nickel, and silver among others. Mostly, copper is used for the plating of PCBs because it prevents corrosion and ensures better connections.
PCB-Plating

Conclusion

Overall, there is no doubt that PCB plating is more than just a little important. If it is not performed, it can expose the PCB to deterioration and corrosion. Out of all other metals, copper is the most common for plating boards.

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