Ipc-4556 — Pdf
The standard provides the performance and technical requirements for Electroless Nickel / Electroless Palladium / Immersion Gold (ENEPIG) plating for printed circuit boards (PCBs) . ENEPIG is often called the "Universal Finish" because it works for soldering, gold wire bonding, and contact surfaces. Key Plating Thickness Requirements
ENIG per IPC-4556 is typically required for Class 3 and high-reliability Class 2 applications.
ENEPIG provides excellent resistance to oxidation, protecting the PCB during long-term storage 1.2.3. How to Obtain and Use the IPC-4556 Standard
Adhering to the measurement guidelines in IPC-4556 is crucial for certification. The standard mandates XRF for thickness measurement. To ensure accuracy: ipc-4556 pdf
The standard provides precise thickness requirements and performance criteria for the three metallic layers: Circuit Insight Electroless Nickel (EN):
Visual and mechanical inspection against IPC-4556 standards ensures the finished boards are reliable for assembly 1.2.4. Conclusion
The IPC-4556 standard is a foundational document for modern high-reliability PCB manufacturing. By downloading, referencing, and implementing the protocols found within the official , design engineers and fabrication facilities can guarantee that their ENEPIG surface finishes are applied with the precision required to prevent field failures. While ENEPIG carries a higher material cost due to the inclusion of palladium and gold, its unmatched multi-functional capabilities make it an indispensable choice for the world's most critical electronic assemblies. To ensure accuracy: The standard provides precise thickness
Typically ranges from 0.05 to 0.30 μm (2 to 12 μin) . 3. Immersion Gold (Au) Layer
+------------------------------------------+ | Immersion Gold (AG / RAIG) | <- Tarnish protection / Solder wettability +------------------------------------------+ | Electroless Palladium | <- Prevents nickel corrosion / Supports wire bonding +------------------------------------------+ | Electroless Nickel (Mid/High P) | <- Copper diffusion barrier / Mechanical strength +------------------------------------------+ | Copper Pad | <- Basis substrate metal +------------------------------------------+
The nickel layer provides a stable base and wear resistance. The palladium acts as a diffusion barrier. The gold layer is the final protective coating, ensuring optimal shelf life, solderability, and wire bondability. ensuring optimal shelf life
The IPC-4556 standard is part of a family of specifications, each covering a different PCB surface finish.
standard is the definitive specification for the performance and use of
: Supporting modern, lower-cost bonding alternatives.
The standard defines the precise thickness ranges for each of the three metallic layers to ensure reliability and prevent defects like "black pad". Recommended Thickness (µm) 3.0 – 6.0 µm Provides structural support and a copper diffusion barrier. Electroless Palladium 0.05 – 0.15 µm
Electroless Nickel/Electroless Palladium/Immersion Gold (ENEPIG)