The palladium layer acts as a barrier that prevents the aggressive immersion gold process from corroding the underlying nickel, a common failure point in standard ENIG finishes.
As PCB designs grow denser and more difficult to register, standards like IPC-4556 ensure that the "universal finish" of ENEPIG remains a viable, high-quality solution for aerospace, medical, and automotive sectors. For engineers and quality managers, maintaining a copy of the IPC-4556 PDF is essential for navigating the complexities of modern surface finishes. Conforming to IPC-4556 with XRF | ENEPIG Surface Finish ipc4556 pdf
Many designers mistakenly assume that any thick copper plating will suffice. However, without adherence to IPC-4556, you risk: The palladium layer acts as a barrier that