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ENEPIG Researched Information – PCB Final Finishes

Researched Information

Here you will find the latest presentations, articles, white papers and more.

PRESENTATIONS

ENEPIG: The “Universal” Finish
Dr. Pericles Kondos grounding presentation examining a “new” pad finish that provides the solderability advantages of Ni / Au while being more cost effective than thick-Au finishes like ENEG. Furthermore, unlike ENIG, ENEPIG is not only a great choice for wire bonding with Gold as well as Aluminum but is also not susceptible to black pad thanks to protection palladium provides nickel from Au attacks. Finally, unlike electrolytic Au (and like ENIG) thin Au layer has no risk of eventually forming brittle intermetallic layer.
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ARTICLES

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.
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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.
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Solder Joint Reliability of Gold Surface Finishes (ENIG, ENEPIG, DIG) for PWB Assembled with Lead Free SAC Alloy
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.
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WHITE PAPERS

Electroless Nickel / Electroless Palladium / Immersion Gold Plating Process for Gold-and Aluminum-Wire Bonding Designed for High Temperature Applications
This paper summarizes the results of qualification testing of the Electroless Nickel / Electroless Palladium / Immersion Gold (Ni/Pd/Au) process as it may be applied for use in high-temperature functional applications. The effects of exposure to heated, high humidity environments were also examined, in addition to the impact of extended thermal cycling. The survivability of the Ni/Pd/Au deposit was studied for both gold wire (30-?m gauge) and aluminum wire (32-?m gauge) bonding under the following test parameters: Dry heat aging at 125°C and 150°C; relative humidity up to 85% at 85°C; exposure times up to 2000 hours; thermo cycling (- 40°C / +125 °C) for 2000 cycles.
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Study of Suitable Palladium and Gold Thickness in ENEPIG Deposits for Lead Free Soldering and Gold Wire Bonding
Nowadays, Electroless Nickel/Immersion Gold (ENIG) is commonly used for substrates that require soldering and mechanical contacting. Although ENIG with increased gold thickness (electroless gold) is a viable finish for gold wire bonding, presently electrolytic Ni/Au is still a widely used finish for this application since concerns still remain about issues with ENIG nickel corrosion and impact resistance. However, electrolytic plating has its own challenges in meeting today’s requirements of weight and form factor that require finer lines and smaller pitch. Electroless plating is a more suitable finish for electronic parts as they continue down the path of smaller and lighter.
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