Formulation and characterization of electrolyte for decorative gold plating based on mercaptotriazole

Dimitrijević, Suzana; Rajčić-Vujasinović, Mirjana; Alagić, Slađana Č.; Grekulović, Vesna; Trujić, Vlastimir

doi:10.1016/j.electacta.2013.04.123

Cited by 35 publications

(35 citation statements)

References 18 publications

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“…[5][6][7] Numerous cyanide-free gold electroplating electrolytes have been developed to replace the cyanidebased electrolytes for gold electroplating. 13 More studies on the investigation of complexing agents are needed for the development of cyanidefree gold electroplating electrolytes. 13 More studies on the investigation of complexing agents are needed for the development of cyanidefree gold electroplating electrolytes.…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical studies of DMH as a complexing agent for a cyanide-free gold electroplating electrolyte

et al. 2015

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In this study, a cyanide-free gold electroplating electrolyte using 5,5-dimethylhydantoin (DMH) as a complexing agent was introduced. A golden bright gold electrodeposit with smooth and compact surface was obtained from the introduced cyanide-free gold electroplating electrolyte. The results of scanning electron microscopy (SEM) measurements confirmed that the golden bright gold electrodeposit possesses an excellent leveling capability as well as smooth and compact morphology.The crystalline structure of the gold electrodeposits was characterized by X-ray diffraction (XRD) analysis.Computational chemistry was employed to provide an insight view of the reason for selecting DMH among the various hydantoin derivatives as the complexing agent for the introduced cyanide-free gold electroplating electrolyte. Quantum chemical calculations were employed to study the electronic properties and orbital information of the investigated complexing agents. The adsorption interactions between these complexing agents and the metal surfaces were investigated by molecular dynamic (MD) simulations. Consequently, the results of these theoretical studies revealed that DMH was selected among the various hydantoin derivatives as the complexing agent for the introduced cyanide-free gold electroplating electrolyte due to its strong electron donating abilities and high adsorption energies on the metal surfaces. Fig. 2 SEM images of the top views of the gold electrodeposits obtained from the introduced cyanide-free gold electroplating electrolyte: (a) and (b) with additive, (c) and (d) without additive, and (e) and (f) from the HAuCl 4 electrolyte without DMH.This journal is

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Section: Introductionmentioning

confidence: 99%

Experimental and theoretical studies of DMH as a complexing agent for a cyanide-free gold electroplating electrolyte

et al. 2015

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Section: Introductionmentioning

confidence: 99%

“…9 As such, there have been cyanide free gold plating solutions developed, primarily based upon sulphite and thiosulfate complexes, however these are limited to electrolytic methodologies. 3 Galvanic (immersion) coatings are an important electrochemical process for the deposition of the thin gold coatings commonly used in the PCB and electronics industries. These coatings involve the galvanic exchange of a metal substrate with another from solution.…”

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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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“…One example regards the non-covalent interactions between the biocompatible TPN-AuNP and double stranded DNA, which in its self plays a role in many applications. 17 Although gold complexants of low toxicity, including a number of thiolates, have been applied in gold plating, 18 TPN would also be an attractive alternative for forming gold structures in devices for in vivo use.…”

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Direct Gold Plating Selectively on UV Modified Polymer Film Using Tiopronin-Gold

Endo

Tashiro

et al. 2015

J. Electrochem. Soc.

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An economic and low toxicity gold plating process for bio-compatible device fabrication was investigated. A tiopronin-gold complex altered by mercaptothiodiazole or mercaptotriazole derivatives gave a form of the complex that could be reduced autocatalytically to enable electroless gold plating. Catalytic ca. 5 nm gold particles were selectively grafted into cycloolefin polymer and polyethylenenaphthalate film surfaces by adsorption of tiopronin-gold complex from solution into 20-30 nm deep ultra-violet light modified surface layers followed by reduction with sodium borohydride. Exposure of the catalyst adsorbed surfaces to baths composed of tiopronin-gold complex, mercaptothiodiazole and ascorbic acid resulted in selective electroless plating on the modified surfaces. Observation of the interface cross-section by transmission electron microscopy revealed that the gold deposits were physically anchored to the substrate by nanometer scale octopus trap like structures. Bio-compatible electronics for in vivo application represent an innovative field of medicine, offering ailment for life quality debilitating health complications. In the applications, sensors and transducers read or relay electronic input or output directly to or from living biological systems, like the brain. In retinal and cochlear neuroprosthesis, neural array implants facilitate direct stimulation of optic nerves with signals from a miniature camera, or direct stimulation of cochlear nerves with signals from a microphone. Research involving conscious neural control to operate external devices like prosthetic robots has also been undertaken. Neural electrode arrays also serve in therapeutic stimulation, bypass or diagnosis of specific neural systems in stroke and head injury patients and in patients suffering from Parkinson's disease, epilepsy, dystonia and severe clinical depression.1-10 Another important application for in vivo electronics is sensors and MEMS on catheters, allowing sensory feedback to the operator or manipulation of a MEMS device internally.11,12 Micro in vivo electronic sensors also offer a means of less invasive direct monitoring by wireless transmission or aid efficient pharmaceutical release. 13Non-toxic, non-allergenic and inert gold and platinum can be used as electrode materials; however toxins and allergens should be avoided in fabrication. Economic plating techniques that rely on bath components and construction materials that are toxic or allergenic introduce health risks and are therefore difficult to implement in fabrication. One approach for deposition of biocompatible gold patterns on poly(dimethylsiloxane) has been described using chemical plating and electrochemical etching. 14 In medicine, tiopronin (TPN) has been used therapeutically as a treatment of cystine disulfide related ailments like cystinuria and prophylaxis of renal cystine calculi, functioning based on an increase in solubility. 15,16 Tiopronin capped gold nanoclusters/nanoparticles (TPN-AuNP) have also been a center of attention in a broad spectrum...

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Formulation and characterization of electrolyte for decorative gold plating based on mercaptotriazole

Cited by 35 publications

References 18 publications

Experimental and theoretical studies of DMH as a complexing agent for a cyanide-free gold electroplating electrolyte

Experimental and theoretical studies of DMH as a complexing agent for a cyanide-free gold electroplating electrolyte

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

Direct Gold Plating Selectively on UV Modified Polymer Film Using Tiopronin-Gold

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Formulation and characterization of electrolyte for decorative gold plating based on mercaptotriazole

Cited by 35 publications

References 18 publications

Experimental and theoretical studies of DMH as a complexing agent for a cyanide-free gold electroplating electrolyte

Experimental and theoretical studies of DMH as a complexing agent for a cyanide-free gold electroplating electrolyte

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

Direct Gold Plating Selectively on UV Modified Polymer Film Using Tiopronin-Gold

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