Ipc4556 Pdf Info

Using the specification to audit and select PCB suppliers.

This article is for informational purposes only and does not replace the official IPC-4556 document. Always refer to the latest standard for legally binding requirements.

in) required for each of the three layers to balance protection and performance: 3.0 – 6.0 m (118.1 – 236.2

IPC-4556 establishes precise thickness ranges for each of the three metal layers. These specifications are designed to balance reliability, solderability, and cost. Plating Layer Thickness Range (µm) Thickness Range (µin) Primary Function 3.0 – 6.0 118.1 – 236.2 Diffusion barrier and structural support Electroless Palladium 0.05 – 0.15 2.0 – 12.0 Protects nickel from corrosion; enables wire bonding Immersion Gold 0.030 – 0.070 1.2 – 2.8 Prevents oxidation; maintains solderability Key Provisions and Amendments

Essential but Expensive. A mandatory standard for high-reliability PCB manufacturing, but access to the PDF is locked behind a high paywall. ipc4556 pdf

If you just need the technical requirements (not the full PDF), here are the critical points from the standard:

IPC-4556 also outlines testing criteria to verify the finish performance:

Deposited on top of the nickel layer. This acts as an anti-oxidation barrier, protecting the nickel from corroding during the subsequent gold immersion process.

Acts as a diffusion barrier to prevent copper from migrating into the solder joint. 2. Electroless Palladium (Pd) Thickness Requirement: 0.05 to 0.15 µm (2 to 6 µin). Using the specification to audit and select PCB suppliers

Suitable for use in membrane switches and steel dome contact applications. Go to product viewer dialog for this item. IPC-4556 - Amendment 1

Protects the nickel layer from hyper-corrosion during the immersion gold process. It enhances wire bondability and strengthens the intermetallic bond. 3. Immersion Gold (Au) Thickness Requirement: 0.03 to 0.09 µm (1.2 to 3.5 µin).

It supports standard surface mount technology (SMT), through-hole assembly, wire bonding, and press-fit connections on a single board.

Thick copper is often used to prevent corrosion and act as a final surface finish. The specification requires porosity testing to ensure no pinholes expose the underlying substrate. in) required for each of the three layers

ENEPIG resolves this by inserting a protective layer of electroless palladium between the nickel and gold. This combination earns ENEPIG its reputation as "the universal surface finish" because it performs flawlessly across multiple distinct vectors:

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."

is the foundational electronics industry standard that dictates the performance, quality, and thickness requirements for Electroless Nickel / Electroless Palladium / Immersion Gold (ENEPIG) surface finishes on printed circuit boards (PCBs). Managed by the Global Electronics Association (IPC) , downloading or reviewing the official IPC-4556 PDF is essential for original equipment manufacturers (OEMs), printed circuit board fabricators, and contract manufacturers operating in high-reliability sectors like aerospace, automotive, and telecommunications.