Standards for checking for surface defects like pitting, corrosion, or contamination 1.2.3.
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By introducing a layer of between the nickel and gold, ENEPIG completely mitigates this risk. The palladium acts as a barrier, preventing the gold chemistry from aggressively corroding the nickel. Core Advantages of ENEPIG:
It forms a highly reliable nickel-tin intermetallic compound (IMC) during reflow, which withstands thermal shock and vibration better than many competing finishes.
Achieving the correct layer distribution is a tight balancing act. If a layer is too thin, it fails to protect; if it is too thick, it can compromise the structural integrity of a solder joint.
ENEPIG works exceptionally well for both tin-lead (SnPb) and lead-free (SAC) soldering, as well as gold and aluminum wire bonding.
When you search for the , you are likely looking for a definitive source of truth. While summaries are helpful, the actual standard is required for:
To underscore the importance of having and using the , consider these real-world failure modes:
Before ENEPIG was standardized, ENIG was widely used for its flat profile and excellent solderability. However, ENIG is susceptible to a notorious defect known as —a corrosion phenomenon that occurs when the immersion gold bath attacks the underlying nickel layer, leading to mechanical joint failures.
| | Release Date | Key Changes | Impact | | :--- | :--- | :--- | :--- | | IPC-4556 (Base) | January 2013 | Initial release of ENEPIG specification. | Established foundational requirements. | | IPC-4556-AM1 | March 2016 | Introduced a maximum gold thickness of 0.070 µm (2.8 µin). | Prevented over-thick gold that could cause brittle joints and corrosion. | | IPC-4556A | June 1, 2025 | Aligned with IPC-4552B (ENIG). Strengthened corrosion resistance and stricter process control. | Significantly tighter requirements for corrosion resistance and gold thickness control. |
) minimum. This thin immersion layer provides a solderable and wire-bondable surface while protecting the palladium. Sharretts Plating Why Choose ENEPIG?
The palladium layer acts as a barrier, preventing the immersion gold chemistry from aggressively attacking and oxidizing the underlying nickel.
Specific tests for gold, aluminum, and copper wire bonding compatibility 1.2.3. ENEPIG Layer Thickness (IPC-4556 Summary) Thickness Range (Micrometers) Thickness Range (Microinches) Nickel (Ni) 3.0 - 6.0 μm 118.1 - 236.2 μin Barrier & Structure 1.2.2 Palladium (Pd) 0.05 - 0.30 μm 2.0 - 11.8 μin Corrosion Resistance 1.2.3 Gold (Au) 0.03 - 0.12 μm 1.2 - 4.7 μin Soldering & Protection 1.2.3 Benefits of Following IPC-4556
To accurately specify manufacturing terms in Request for Quotes (RFQs) to prevent counterfeit or sub-standard plating finishes. Conclusion: Securing Your Copy of IPC-4556
Electroless Palladium/ Immersion Gold (ENEPIG) Plating for Printed Circuit. Tel 847 615.7100. Fax 847 615.7105. electronics.org IPC-4556 -ENEPIG Plating for PCB - Saturn Flex Systems