Why Electroless Nickel Electroless Palladium Immersions (ENEPIG)?
ENEPIG’s key advantages include: “Black Nickel” free – no possibility of grain boundary corrosion of nickel surface by immersion gold; Palladium acts as an additional barrier layer to further reduce copper diffusion to surface, thus ensuring good solderability; Pd completely dissolves into solder, without leaving an excessively high P% rich interface, exposing anoxide-free nickel surface allowing reliable formation of Ni/Sn intermetallic; withstands multiple pb-free reflow soldering cycles; demonstrates excellent gold wire bondability; process costs substantially lower than ENIG and ENEG.
ENEPIG: A Final Finish That’s Time Has Come
The elimination of lead from electronic devices as mandated by RoHS (Restriction of Hazardous Substance) is changing the playing field for all those involved in the industry. On the PCB level, OEMs have the brunt of dealing with the change; designers are always pushing the limits of the industry capabilities to meet the requirements of their newer designs. Presently, the push back is on what the industry is capable of delivering under the new directive.
Solder Joint Reliability of Gold Surface Finishes (ENIG, ENEPIG, DIG) for Pb-free Assembly
As the efforts continue towards meeting RoHS requirements and the elimination of lead by mid 2006 for some countries, finding the ideal surface finish is on most manufacturers’ minds. The surface finish has to be lead free and more important should be able to produce a reliable solder joint when assembled at high temperature with a lead free solder. Presently there are a series of alternate surface finishes in use throughout the printed circuit industry. Some finishes are widely used and others are used for very specific applications. Gold based Finishes include the following: ENIG; ENEPIG; and Direct Immersion Gold (DIG). Additional Final Finishes include: Organic Solderabilty Preservatives (OSP); Immersion Silver (IAg); Immersion Tin (ISn); and Selective OSP / ENIG, DIG / ENIG.