Advanced surface protection for improved reliability PCB systems (ASPIS)

Ballantyne, Andrew D.; Forrest, Greg; Goosey, Martin; Grigucevičienė, Asta; Juodkazytė, Jurga; Kellner, Rod; Kosenko, Aleksandr; Ramanauskas, R.; Ryder, Karl S.; Selskis, A.; Tarozaitė, Rima; Veninga, E.P.

doi:10.1108/03056121211195021

Cited by 11 publications

(13 citation statements)

References 21 publications

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“…In order to determine the porosity of the IG coating quantitatively, the coating was chemically removed from the EN surface using a cyanide‐based solution and, after that, the voltammetric response of the sample in 0.1 M KOH was recorded again (Figure 10, curve 2). The percentage of the EN surface exposed to the testing solution through the pores of the IG coating can be calculated according to formula: P IG/Ni = Q IG/Ni /Q EN ×100 per cent, where P IG/Ni is the porosity of IG coating, reflecting the percentage of EN surface exposed to testing solution through the pores in the IG coating, Q EN is the reduction charge of Ni oxygen species on EN, Q IG/Ni is the charge of reduction of Ni oxygen species through the pores of the IG coating (Ballantyne et al , 2012). The porosity of the investigated ENIG coating on PCB sample C, according to the obtained data, was close to 22 per cent.…”

Section: High Porosity Of the Ig Layer (Pcb Sample C)mentioning

confidence: 99%

PCB failure analysis related to the ENIG black pad problem

et al. 2013

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Purpose -The purpose of this paper is to verify the principal conclusions, done during the implementation of FP7 ASPIS project objectives in fundamental research of ENIG-related failures by investigating real problematic PCB samples of different suppliers. Design/methodology/approach -SEM, EDS and XPS techniques were applied for morphology and composition studies of ENIG coatings of three PCB samples (A, B and C), while electrochemical measurements were used to determine the porosity of EN and IG layers. Findings -The surface morphology analysis of the un-soldered pads of PCB A disclosed the fact that the surface of substrate was not pre-treated in a proper manner before EN deposition, which generated structural defects such as cracks and opening pores in the EN layer, which in turn could produce the voids in the solder layer during the soldering process. The results of PCB B analysis confirmed the authors' observation that Au layers deposited on EN substrate from IG solution contaminated with Cu ions are highly porous and loosely adhering to EN coating, which, in addition, undergoes serious corrosion damages and may be the principal reason for the black pad defect occurrence. High porosity of IG deposit and the presence of the intermediate layer between Au and Ni-P, which was enriched in Cu and O, were the main reasons for the black pad issue in the case of PCB C. Originality/value -The gained knowledge on the mechanism of ENIG-related failures, which cause reliability problems in PCB manufacture, makes it possible to elaborate potential non-destructive techniques for detecting ENIG problems.

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Section: High Porosity Of the Ig Layer (Pcb Sample C)mentioning

confidence: 99%

PCB failure analysis related to the ENIG black pad problem

et al. 2013

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“…1 The key characteristic feature of these noble metal coatings is the lack of insulating surface oxides. 2 Electrolytic, 3 electroless, 4 and immersion plating 5 are the three common electrochemical methods used for the coating of conducting substrates with gold films. In each of these processes the conventional/ commercial plating bath chemistry is dominated by the choice of the dicyanidoaurate anion [Au(CN) 2 ] À as the gold source 6 due to its high stability 7 and the ability to yield fine grained deposits.…”

Section: Introductionmentioning

confidence: 99%

Electrochemistry and speciation of Au⁺in a deep eutectic solvent: growth and morphology of galvanic immersion coatings

Ballantyne

Forrest

Frisch

et al. 2015

Phys. Chem. Chem. Phys.

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In this study we compare the electrochemical and structural properties of three gold salts AuCl, AuCN and KAu(CN)2 in a Deep Eutectic Solvent (DES) electrolyte (Ethaline 200) in order to elucidate factors affecting the galvanic deposition of gold coatings on nickel substrates. A chemically reversible diffusion limited response was observed for AuCl, whereas AuCN and KAu(CN)2 showed much more complicated, kinetically limited responses. Galvanic exchange reactions were performed on nickel substrates from DES solutions of the three gold salts; the AuCN gave a bright gold coating, the KAu(CN)2 solution give a visibly thin coating, whilst the coating from AuCl was dull, friable and poorly adhesive. This behaviour was rationalised by the differing speciation for each of these compounds, as evidenced by EXAFS methods. Analysis of EXAFS data shows that AuCl forms the chlorido-complex [AuCl2] − , AuCN forms a mixed [AuCl(CN)] − species, whereas KAu(CN)2 maintains its [Au(CN)2] − structure. The more labile Cl − enables easier reduction of Au when compared to the tightly bound cyanide species, hence leading to slower kinetics of deposition and differing electrochemical behaviour. We conclude that metal speciation in DESs is a function of the initial metal salt and that this has a strong influence on the mechanism and rate of growth, as well as on the morphology of the metal deposit obtained. In addition, these coatings are also extremely promising from a technological perspective as Electroless Nickel Immersion Gold (ENIG) finishes in the printed circuit board (PCB) industry, where the elimination of acid in gold plating formulation could potentially lead to more reliable coatings. Consequently, these results are both significant and timely. IntroductionGold plating processes are widely used in the materials finishing, decorative and electronics industries due to their high reliability, electrical conductivity and corrosion resistance. 1 The key characteristic feature of these noble metal coatings is the lack of insulating surface oxides. 2 Electrolytic, 3 electroless, 4 and immersion plating 5 are the three common electrochemical methods used for the coating of conducting substrates with gold films. In each of these processes the conventional/commercial plating bath chemistry is dominated by the choice of the dicyanidoaurate anion [Au(CN) 2 ] − as the gold source 6 due to its high stability 7 and the ability to yield fine grained deposits. 8 In electroplating experiments, acidic plating baths around pH 5 are used to produce soft gold coatings, whilst alkaline and neutral baths are used to produce hard gold. 8 However, there are significant safety concerns, as well as issues regarding the disposal of waste, where cyanide based processes are present. In addition, the requirement of large negative reduction potentials can also lead to the coreduction of hydrogen ions. 9 As such, there have been cyanide free gold plating solutions developed, primarily based upon sulphite and thiosulfate complexes, however these are limited to...

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“…Figure 5 represents a PCB treated with immersion silver deposition. ENIG-like processes have been developed as well, with gold deposited on nickel-plated contacts [94,95]. The neutral nature of the DES can help avoiding the "black pads" effect, induced by an excessive corrosion of Ni in the Au electrolyte.…”

Section: Industrial Applicability Of Electroless and Displacement Depmentioning

confidence: 99%

Electrodeposition from Deep Eutectic Solvents

Bernasconi¹,

Panzeri²,

Accogli³

et al. 2017

Progress and Developments in Ionic Liquids

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Deep eutectic solvents constitute a class of compounds sharing many similarities with properly named ionic liquids. The accepted deinition of ionic liquid is a luid liquid for T< °C) consisting of ions, while DES are eutectic mixtures of Lewis or "rønsted acids and bases. Their most atractive properties are the wide potential windows and the chemical properties largely diferent from aqueous solutions. In the last few decades, the possibility to electrodeposit decorative and functional coatings employing deep eutectic solvents as electrolytes has been widely investigated. " large number of the deposition procedures described in literature, however, cannot ind application in the industrial practice due to competition with existing processes, cost or diicult scalability. From one side, there is the real potential to replace existing plating protocols and to ind niche applications for high added-value productions to the other one, this paves the path towards the electrodeposition of metals and alloys thermodynamically impossible to be obtained via usual aqueous solution processes. The main aim of this chapter is therefore the critical discussion of the applicability of deep eutectic solvents to the electrodeposition of metals and alloys, with a particular atention to the industrial and applicative point of view.Keywords: electrodeposition, deep eutectic solvents, metals, alloys . IntroductionThe electrodeposition of metals for industrial surface inishing is nowadays a well-established industrial practice. Many processes are available to obtain a wide variety of coatings on most of © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.© 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. the substrates used in manufacturing. There are however some important limitations, as not all the metal/substrate combinations are possible in the current state of the art. This is connected to the nature of the electrolytes used for the vast majority of the plating processes, which are water based. Water is the most obvious choice to formulate a plating electrolyte, and in the majority of the cases, it is also the most convenient from the point of view of the results obtained. This solvent however presents some limitations: narrow potential window, reactivity towards speciic metals, high hydrogen evolution in speciic conditions, etc. If metal plating is limited to aqueous solutions, many possibilities are therefore precluded." possible way to extend the range of coating/substrate combinations is the use of non-aqueous solvents, characterized by ext...

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Advanced surface protection for improved reliability PCB systems (ASPIS)

Cited by 11 publications

References 21 publications

PCB failure analysis related to the ENIG black pad problem

PCB failure analysis related to the ENIG black pad problem

Electrochemistry and speciation of Au⁺in a deep eutectic solvent: growth and morphology of galvanic immersion coatings

Electrodeposition from Deep Eutectic Solvents

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Advanced surface protection for improved reliability PCB systems (ASPIS)

Cited by 11 publications

References 21 publications

PCB failure analysis related to the ENIG black pad problem

PCB failure analysis related to the ENIG black pad problem

Electrochemistry and speciation of Au+in a deep eutectic solvent: growth and morphology of galvanic immersion coatings

Electrodeposition from Deep Eutectic Solvents

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Electrochemistry and speciation of Au⁺in a deep eutectic solvent: growth and morphology of galvanic immersion coatings