ENIG plating is essential for avionics reliability (Photo by Oskar Kadaksoo from Unsplash)
Aviation electronics, or avionics, are the electronic systems installed in aircraft. These systems handle navigation, communication, monitoring, and control. Avionics components require Electroless Nickel Immersion Gold (ENIG) plating due to its remarkable reliability and durability in harsh environments, especially those found in aerospace applications.
The growth of ENIG as a surface finish for avionics has allowed avionic systems to meet the high levels of performance and reliability needed when operating under extreme conditions. Here are a few ways that ENIG enables reliable avionics in demanding environments.
Corrosion Resistance
Avionics operating under widely varying climates must be able to function reliably under these conditions without being corroded and this is possible thanks to electroless nickel immersion gold plating.
When the avionic equipment is exposed to moisture, temperature fluctuations, and chemical contaminants during a flight for instance, the electroless nickel layer serves as a barrier, preventing the underlying metal substrate, often copper, from direct contact with these potentially corrosive environments.
The barrier effectively shields the substrate from oxidation and other forms of chemical degradation which preserves the integrity and functionality of the avionics components over their operational lifespan. This makes this plating solution ideal even for the most strict applications, such as those that must meet the ITAR requirements.
Solderability
ENIG also enables reliable avionics in demanding environments through its exceptional solderability properties. Here, the gold nickel plating provides a surface with the ability to form reliable and robust solder joints.
The nickel layer in ENIG serves as a diffusion barrier, preventing the migration of metals between the solder and the underlying substrate, while the gold layer provides a highly solderable surface. This combination ensures that the solder joints form uniformly and reliably during assembly. This becomes quite useful in maintaining electrical connections, preventing failures, and ensuring the overall safety and performance of the avionic systems.
Electrical Performance
ENIG plating serves as an important interface between the conductive traces on a printed circuit board and the components they connect.
Its electrical performance is defined by several key factors. Some of these are listed below:
- ENIG provides excellent conductivity, ensuring minimal signal loss and reliable transmission of electrical signals across the PCB.
- Its uniform thickness facilitates consistent electrical contacts. This reduces impedance variations and signal reflections that could degrade performance.
By combining nickel and gold layers in ENIG technology, the avionics get superior electrical conductivity, signal integrity, high-speed data transmission capabilities, minimal electromagnetic interference in densely populated electronic assemblies, and more.
Lead-Free Soldering
When combined with lead-free soldering methods, like SAC (tin-silver-copper) alloys, ENIG plating helps meet environmental regulations and supports sustainability by avoiding the use of highly toxic lead. This approach promotes eco-friendly practices and eliminates the harmful effects of lead.
Lead-free soldering also enhances the mechanical and thermal properties of solder joints which are crucial for avionics applications where reliability under harsh conditions is very important.
But lead-free soldering has some limitations.
Without electroless nickel immersion gold, lead-free soldering may present challenges such as higher melting points and increased susceptibility to certain defects like brittle fractures and tin whiskers. This is why it is important to have meticulous process controls and quality assurance measures to ensure the integrity and reliability of lead-free solder joints in avionic systems.
ENIG’s compatibility with lead-free solders addresses these limitations by offering reliable solder joints without the risk of solder joint embrittlement and other issues associated with lead-free soldering.
Fine-Pitch Components
Avionic systems often incorporate components with very small footprints and fine pitch leads. These components demand exceptional precision to ensure optimal performance in aviation applications. This means that the surface between the fine-pitch components and their substrate should ideally be smooth and uniform for their placement. The components should also be reliably soldered to their substrate for optimal performance.
Without uniform coverage, issues such as solder bridging and insufficient solder wetting can arise in the avionics systems. Thankfully, gold nickel plating solves these issues.
ENIG plating serves as a crucial interface between the fine-pitch components and their substrate, offering excellent corrosion resistance, solderability, and flatness while also providing the uniform coverage required to avoid the issues we spoke about in the paragraph above.
Longevity
Avionic systems operate in harsh environments of extreme temperatures, high vibration, and exposure to corrosive elements which places a significant strain on the components’ durability. By providing a protective barrier against oxidation and corrosion, ENIG plating safeguards sensitive electronic circuits from degradation over time.
From the excellent solderability that minimizes the risk of intermittent connections and other issues to the uniformity and stability of the gold nickel layer, the avionics are able to maintain signal integrity and electrical performance over extended periods thereby prolonging the service life of the plated components while minimizing the need for maintenance or expensive repairs.
