Technical Library | 2013-01-17 15:37:21.0
A problem exists with electroless nickel / immersion gold (ENIG) surface finish on some pads, on some boards, that causes the solder joint to separate from the nickel surface, causing an open. The solder has wet and dissolved the gold. A weak tin to nickel intermetallic bond initially occurs, but the intermetallic bond cracks and separates when put under stress. Since the electroless nickel / immersion gold finish performs satisfactory in most applications, there had to be some area within the current chemistry process window that was satisfactory. The problem has been described as a 'BGA Black Pad Problem' or by HP as an 'Interfacial Fracture of BGA Packages…'[1]. A 24 variable experiment using three different chemistries was conducted during the ITRI (Interconnect Technology Research Institute) ENIG Project, Round 1, to investigate what process parameters of the chemical matrix were potentially satisfactory to use and which process parameters of the chemical matrix need to be avoided. The ITRI ENIG Project has completed Round 1 of testing and is now in the process of Round 2 TV (Test Vehicle) build.
Technical Library | 2023-01-06 16:18:23.0
PCB/Substrate Finishing Overview - iNEMI - PCB Surface Finish Overview. Surface Finish deployment ranked by surface area. OSP greatest. Imm Tin. ENIG. Silver. ENEPIG.
Technical Library | 2021-07-06 21:20:38.0
The evolution of internet-enabled mobile devices has driven innovation in the manufacturing and design of technology capable of high-frequency electronic signal transfer. Among the primary factors affecting the integrity of high-frequency signals is the surface finish applied on PCB copper pads – a need commonly met through the electroless nickel immersion gold process, ENIG. However, there are well-documented limitations of ENIG due to the presence of nickel, the properties of which result in an overall reduced performance in high-frequency data transfer rate for ENIG-applied electronics, compared to bare copper.
Technical Library | 2021-07-06 21:18:02.0
A new PCB surface finish has been developed that offers outstanding performance and excellent environmental protection. This finish has the potential to replace more common finishes such as ENIG, ImAg, ImSn, ENEPIG, or OSP with a chemically resistant plasma deposited coating. The substitution of the wet processes with this dry plasma process offers significant advantages e.g. lower quantities of chemicals used, environmental benefits and improved operator safety.
Technical Library | 2020-08-05 18:49:32.0
The evolution of internet-enabled mobile devices has driven innovation in the manufacturing and design of technology capable of high-frequency electronic signal transfer. Among the primary factors affecting the integrity of high-frequency signals is the surface finish applied on PCB copper pads – a need commonly met through the electroless nickel immersion gold process, ENIG. However, there are well-documented limitations of ENIG due to the presence of nickel, the properties of which result in an overall reduced performance in high-frequency data transfer rate for ENIG-applied electronics, compared to bare copper. An innovation over traditional ENIG is a nickel-less approach involving a special nano-engineered barrier designed to coat copper contacts, finished with an outermost gold layer. In this paper, assemblies involving this nickel-less novel surface finish have been subjected to extended thermal exposure, then intermetallics analyses, contact/sheet resistance comparison after every reflow cycle (up to 6 reflow cycles) to assess the prevention of copper atoms diffusion into gold layer, solder ball pull and shear tests to evaluate the aging and long-term reliability of solder joints, and insertion loss testing to gauge whether this surface finish can be used for high-frequency, high density interconnect (HDI) applications.
Technical Library | 2015-11-25 14:15:12.0
In this study various printed circuit board surface finishes were evaluated, including: organic solderability preservative (OSP), plasma finish (PF), immersion silver (IAg), electroless nickel / immersion silver (ENIS), electroless nickel / immersion gold hi-phosphorus (ENIG Hi-P), and electroless nickel / electroless palladium / immersion gold (ENEPIG). To verify the performance of PF as a post-treatment option, it was added to IAg, ENIG Hi-P, and ENEPIG to compare with non-treated. A total of nine groups of PCB were evaluated. Each group contains 30 boards, with the exception on ENIS where only 8 boards were available.
Technical Library | 2020-11-15 21:01:24.0
ENIG, electroless nickel immersion gold is now a well-regarded finish used to enhance and preserve the solder-ability of copper circuits. EPIG, electroless palladium immersion gold, is a new surface finish also for enhancing and preserving solder-ability but with the advantage of eliminating Electroless Nickel from the deposit layer. This feature has become increasingly important with the increasing use of high frequeny PWB designs whereby nickel's magnetic properties are detrimental. We examine these two finishes and their respective soldering characteristics as plated and after steam aging and offer an explanation for the performance deviation.
Technical Library | 2023-01-06 16:09:03.0
The 4-14 IPC Standards Committee recently created a revision to the IPC4552 specification for Electroless Nickel/Immersion Gold (ENIG) finished Printed Circuit Boards (PCB). Revision A brings a more comprehensive evaluation of metal layer thicknesses measurement, composition and introduces, for the first time, a quality aspect for nickel corrosion which has been historically connected to a defect called black line nickel or black pad.
Technical Library | 2023-01-10 20:15:42.0
Over the past years there has been consistent growth in the use of electroless nickel / immersion gold (ENIG) as a final finish. The finish is now frequently being used for PBGA, CSP, QFP and COB and more recently gathered considerable interest as a low cost under-bump metallization for flip chip bumping application. One of the largest users for this finish has been the telecommunication industry, were millions of square meters of PCBs with ENIG have been successfully used. The nickel layer offers advantages such as multiple soldering cycles and hand reworks without copper dissolution being a factor. The nickel also acts as a reinforcement to improve through-hole and blind micro via thermal integrity. In addition the nickel layer offers advantages such as co-planarity, Al-wire bondability and the use as contact surface for keypads or contact switching. Especially those pads, which are not covered by solder need a protective coating in corrosive environment – such as high humidity or pollutant gas.
Technical Library | 2017-09-07 13:56:11.0
As a surface finish for PCBs, Electroless Nickel/Electroless Palladium/Immersion Gold (ENEPIG) was selected over Electroless Nickel/Immersion Gold (ENIG) for CMOS image sensor applications with both surface mount technology (SMT) and gold ball bonding processes in mind based on the research available on-line. Challenges in the wire bonding process on ENEPIG with regards to bondability and other plating related issues are summarized.
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