Ipc4556 Pdf File

Excellent wetting for SAC305 and other lead-free solders.

, "Specification for Electroless Nickel/Electroless Palladium/Immersion Gold (ENEPIG) Plating for Printed Circuit Boards," is the definitive industry standard for the ENEPIG surface finish. Released in 2013 and subsequently updated to the IPC-4556A revision , this document defines the quality requirements, deposit thicknesses, and testing protocols for ENEPIG-finished PCBs.

), but tighter control is often preferred to avoid brittle joints. Superior Processing Performance & Quality Standards Which PCB Surface Finish is Better: ENIG or ENEPIG?

This is the defining layer that differentiates ENEPIG from ENIG (Electroless Nickel Immersion Gold). The palladium layer protects the underlying nickel from oxidation and hyper-corrosion during the gold plating process—a phenomenon commonly known as "black pad."

Enhanced requirements for XRF (X-ray Fluorescence) measurement repeatability, ensuring that the measured thickness is truly representative of the deposit. ipc4556 pdf

IPC-4556 establishes precise thickness ranges for each metal layer to ensure reliability and performance. Measurements are typically taken on a 1.5 mm x 1.5 mm pad at ±4plus or minus 4 sigma from the process mean. Plating Layer Thickness (μm) Thickness (μin) 3.0 – 6.0 118.1 – 236.2 Diffusion barrier and mechanical strength Electroless Palladium 0.05 – 0.15 2.0 – 12.0 Prevents nickel corrosion; enables wire bonding Immersion Gold 0.030 – 0.070 1.2 – 2.8 Protects palladium; preserves solderability

Here is the direct and most important information:

Utilizes tape tests and mechanical stress tests to ensure the plated layers do not peel away from the copper base under thermal cycling. Why Use ENEPIG? (Advantages over ENIG and HASL)

Boards finished to IPC-4556 specifications easily maintain their solderability for over 12 months in standard storage conditions, significantly outperforming OSP (Organic Solderability Preservatives) and Immersion Silver. Quality Control and Measurement Methods Excellent wetting for SAC305 and other lead-free solders

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Meets IPC-J-STD-003 Category 3 standards for at least 12 months. How to Obtain

To maintain statistical process control and guarantee uniform reliability, IPC-4556 establishes rigid limits for each layer. Thickness measurements must be evaluated on standard reference test pads using tightly calibrated equipment like X-ray Fluorescence (XRF) instruments. Layer Material Thickness Range (Metric) Thickness Range (Imperial) Primary Engineering Function Diffusion barrier & mechanical support Electroless Palladium Prevents black pad; enables wire bonding Immersion Gold Anti-oxidation, low contact resistance Statistical Process Control and Tolerance IPC 4556A - Accuris Standards Store

Implementing ENEPIG according to IPC-4556 guidelines offers distinct advantages for high-density interconnect (HDI) and high-frequency applications. ), but tighter control is often preferred to

X-ray Fluorescence (XRF) is the primary method for verification. Major Applications

A key technical aspect of the standard is the requirement to apply a

Tape tests verify that the plating layers adhere firmly to the copper substrate without peeling.