What is Electroless Nickel Immersion Gold (ENIG) PCB surface finish? What are the advantages and disadvantages of ENIG?
Editorial Team - PCB Directory
Jun 6, 2023
Immersion gold, also known as Electroless Nickel Immersion Gold (ENIG), is a common type of printed circuit board (PCB) surface finish. It involves depositing a thin layer of gold on the PCB's copper traces and pads using a chemical process that does not require an electrical current.
The thickness of an Electroless Nickel Immersion Gold (ENIG) coating on a printed circuit board (PCB) typically ranges from 0.05 to 0.2 microns for the nickel layer and 0.05 to 0.15 microns for the gold layer.
Immersion Gold (ENIG) PCB Coating
The thickness of the ENIG coating is critical to ensure optimal performance and reliability of the PCB. The nickel layer thickness is important for preventing the gold layer from diffusing into the copper, while the gold layer thickness is critical for ensuring good solderability and wire bonding. Immersion gold PCB surface finish is a popular choice for high-reliability PCB applications, such as aerospace, defense, medical, and telecommunications industries, where performance and reliability are critical.
PCB surface finishes protect exposed copper on a PCB from oxidation and ensure a reliable connection between components and the board. They are crucial for the performance, reliability, and lifespan of the PCB, and impact manufacturing quality. They also impact the manufacturing process, including the quality of the soldering and assembly.
In this article, we will explore the concept of Immersion Gold (ENIG) as a PCB surface finish, what is it, and the benefits and applications of using it in your PCB.
Steps Involved in Coating Immersion Gold
The process of coating immersion gold to a printed circuit board (PCB) involves several steps:
Layers of Gold and Nickel deposited over a PCB
Advantages/Disadvantages of ENIG Surface Finish
Here's some information on the advantages and disadvantages of using ENIG as a surface finish:
Advantages of ENIG:
Aluminium Wire Bond
One year or higher
Disadvantages of ENIG:
Applications of Immersion Gold (ENIG) PCB Surface Finish
Following are some applications of immersion gold surface finish in different industries:
In conclusion, PCB surface finishes are crucial for protecting exposed copper on a PCB from oxidation, ensuring a reliable connection between components and the board. Electroless Nickel Immersion Gold (ENIG) is a common and popular type of PCB surface finish in the electronics industry, widely used in high-reliability PCB applications, such as aerospace, defense, medical, and telecommunications industries. ENIG provides good corrosion resistance, and uniform thickness, and is an excellent surface finish for wire bonding applications because it provides a highly conductive surface that is easy to bond to.
However, ENIG is more expensive than other surface finishes and requires careful handling during the manufacturing process. It is also not suitable for high-temperature applications, and the nickel layer is difficult to inspect visually, which can make it challenging to detect defects during the manufacturing process.
Apr 13, 2020
ENIG (Electroless Nickel Immersion Gold) is a surface plating that is applied over the copper pads on a Printed Circuit Board to protect them from corrosion and other abnormalities. Initially, the copper pad is covered by a Nickel (Ni) layer followed by a thin immersion Gold (Au) layer. ENIG provides good oxidation resistance, excellent surface planarity and allows for easy soldering which results in excellent electrical performance of the PCB board.
ENIG is RoHS compliant and is, therefore, one of the most used PCB surface finishes even though it is more complex and expensive when compared to other PCB plating processes like HASL.
ENIG is a two-layer metallic coating – Nickle is the barrier to the copper pad and is also the material to which components are soldered. Gold on the other hand protects the Nickle during storage and also provides low contact resistance. Typical Nickle thickness varies from 4 – 7 µm and Gold thickness varies from 0.05 – 0 23 µm. ENIG requires a processing temperature of around 80 °C.
Advantages of ENIG Surface Finishes:
Limitations of ENIG Surface Finishes:
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