The XRF spot size should not exceed 30% of the feature size being measured.
on the same board where surface mount soldering occurs, making it indispensable for high-density and high-frequency applications. Enhanced Shelf Life: ipc4556 pdf
Before the standardization of ENIPIG, the industry relied heavily on ENIG (Electroless Nickel/Immersion Gold). However, ENIG suffered from a defect known as "black pad," where corrosion of the nickel layer resulted in brittle solder joints that could crack under stress or vibration. The XRF spot size should not exceed 30%
Provides a stable barrier against copper diffusion and offers wear resistance for contact applications. Electroless Palladium (EP): ipc4556 pdf