Gold Plating for PCBs
Gold is a durable material that resists everyday wear and tear. It is also resistant to corrosion from chemicals and rust. This makes it ideal for metal contacts and high-wear areas on a circuit board.
When it comes to PCB gold plating, it is important to remember that there are certain spacing measurements that must be kept in mind. Any deviation from these standards may lead to a weak or malfunctioning card.
Durability
Gold’s strong conductivity and resistance to corrosion make it a great choice for PCBs. It can also be alloyed with nickel or cobalt for additional strength. Its tolerance of heat also safeguards underlying metals. This makes it an ideal choice for printed circuit boards that require high-speed signal transmission. Today’s computer and mobile devices have many gold-plated contacts that transmit signals. As such, they need to be durable and able to withstand the elements.
Choosing the right surface finish is crucial for PCB production. A thin gold layer can corrode, while a thick one can damage the board. It’s also important to ensure that the gold surface is smooth enough to accept solder masks and silk screens. This helps improve the yield rate and ensures that the copper traces are correctly spaced.
Hard gold is an excellent option for PCBs that need to withstand high levels of friction. It’s also an excellent choice for military applications, which may be exposed to extreme conditions like temperature changes, humidity and salt. However, this requires careful consideration of the PCB’s design. It should include copper etching to leave only the required regions bare, as well as careful gold plating pcb selection of the nickel underplating to prevent pad blackening (also known as Nickel corrosion). Additionally, a quality control process is necessary to avoid any contamination in the nickel plating that could cause the PCB to fail.
Resistance to Corrosion
Gold PCBs are used in aerospace applications because of their exceptional durability and resistance to corrosion. They also have excellent conductivity and provide good shielding of electromagnetic interference (EMI). The IPC recommends that all PCB manufacturers use nickel underplates to prevent the copper from corroding. Nickel also helps the copper to retain its electrical properties under tough conditions for a longer time.
The PCB hard gold surface finish is a layer of gold mixed with hardeners that gets plated over a barrier coat of nickel via an electrolytic process. This type of gold finish is highly durable, but it can be costly. It also has poor solderability. It is therefore rarely used on solderable areas of the board. Instead, manufacturers often choose the more cost-effective ENIG for solderable areas.
The first step of the hard gold plating process is to prepare the substrate by using etchants and conditioners. Then, it’s dipped in a metal ion bath. The solution may contain metallic brighteners, chelated or complexed, as well as range extenders, surfactants and depolarizing agents. It’s also possible to use thiosulfate and thiocyanate, both of which are effective at increasing the nucleation rate of crystallites. This allows the deposit to grow at higher current densities. However, excessive cleaning can wear down the coating. For this reason, it’s best to use a soft brush to clean the board, rather than a wire or abrasive tool.
Aesthetics
Gold is considered a premium surface finish for PCBs due to its exceptional conductivity and resistance to corrosion. It is often paired with nickel and copper for additional durability. Moreover, it is also available in various alloys for added strength and ductility. These characteristics make it ideal for use in a wide variety of applications and environments.
Aside from its electrical properties, gold is attractive to the eye and enhances the aesthetics of a circuit board. Its ability to resist oxidation is also an important factor. However, if the gold plating is too thin, it may degrade or even flake off. In order to avoid these problems, a visual test should be conducted to ensure that the layer is thick enough and smooth.
The metallization process used for gold plating PCBs involves several steps. First, a nickel layer of between three and six microns is applied to the connector edges of gold fingers. Then, a layer of hard gold is deposited over the Gold Plating PCB Supplier nickel and alloyed with cobalt for enhanced surface resistance. Lastly, the connector edges are beveled at specified angles to facilitate insertion into corresponding slots.
Another option for PCBs is ENIG, or electroless nickel immersion gold. This finish protects copper traces from corrosion and offers several advantages over traditional surface finishes, including compatibility with wire bonding and a longer shelf life. ENIG also has the benefit of being environmentally friendly, as it does not require the use of toxic chemicals such as potassium cyanide.
Cost
Gold is a precious metal that needs to be carefully used in PCB production. It is expensive and can easily deteriorate or lose its properties, especially if it is plated too thin. A thin layer of gold will be vulnerable to corrosion, while a thick one will be too heavy and can cause the circuit board to fail due to strain. It is also important to balance the use of gold with other materials, as excess can result in significant waste and lost resources.
The PCB gold plating process is a complex and rigorous procedure that requires strict quality control and inspections. The IPC recommends performing a tape test to assess the quality of the gold plating. This test involves placing a strip of tape on the contact edge and inspecting it for signs of gold. If any traces of gold are visible, the PCB is likely to be prone to failure and should not be sold.
Gold is often used as an alloy with other metals to improve its durability. It is a good choice for high-wear areas such as the edge connectors of a PCB because it provides a durable surface and resists friction. It is also resistant to corrosion because it has a lower porosity than other metals. It is best combined with nickel, which protects the gold against oxidation.