Electroless Nickel Immersion Gold (ENIG) is a sophisticated surface finish for 4-layer Printed Circuit Boards (PCBs). The process involves two key steps: electroless nickel deposition followed by immersion gold plating.
In 4-layer PCBs, ENIG’s immersion gold layer plays a crucial role:
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Oxidation Prevention: The thin gold layer (typically 0.05-0.1 µm) protects the underlying nickel from oxidation, ensuring long-term solderability.
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Uniform Surface: Immersion gold provides an exceptionally flat and uniform surface, critical for fine-pitch components in complex 4-layer designs.
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Thickness Consistency: Unlike electroplated finishes, immersion gold maintains consistent thickness across the board, vital for the intricate layouts of 4-layer PCBs.
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Enhanced Conductivity: Gold’s excellent conductivity improves signal transmission in high-frequency applications common in multi-layer boards.
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Wire Bonding Compatibility: The gold surface is ideal for both soldering and wire bonding, offering versatility in assembly techniques.
While more expensive than some alternatives, ENIG’s immersion gold finish provides superior protection and performance, making it a preferred choice for high-reliability 4-layer PCBs in demanding applications.
