Gold Plating Bath Research Articles

Zinc Oxide Nanomaterial‐Based Dispersive Solid Phase Extraction for the Trace Determination of Gold in Flash Gold Plating Solution Samples using Flame Atomic Absorption Spectrophotometry

AbstractThe noble metal Au is extensively used in jewelry, industry, and medicine. In order to mitigate the low sensitivity of the flame module atomic absorption spectrometer (FAAS) to determine the gold, zinc oxide (ZnO) nanomaterial were synthesized and used to pretreatment of the sample and preconcentrate gold ions in dispersive solid phase extraction (DSPE) process. Enrichment factor of the extraction method was enhanced by performing buffer solution type/volume, nanomaterial amount, mixing type/period, and desorption solvent concentration/volume optimizations. Calibration plot displayed good linearity and percent relative standard deviation recorded for the lowest concentration of the plot was adequately low (<7.0 %). Dynamic dynamic range for the proposed method was calculated between 30–400 μg/L. Regression coefficient (R2) of proposed method was found to be 0.9956. With an enrichment factor of 44.5‐folds, method recorded a detection limit (LOD) of 7.4 μg L−1 and quantification limit (LOQ) of 24.8 μg L−1. Flash gold plating bath solution was used to certify the quantification accuracy/applicability in complex matrix of the method. The obtained results (1.86±0.08 g L−1) were compatible with the results of the reference method (ICP‐OES) (1.87±0.08 g L−1). This is the first study for the extraction/preconcentration of gold using ZnO nanomaterial.

A Novel Analytical Method of Thallium Determination in Gold Electrodeposition

Thallium is used in both cyanide and sulfite-based gold plating bath solutions as an additive that modulates how gold deposits on the target substrate. The level of Tl in the plating solutions has a large effect on the properties of the gold being deposited, including its microstructure and hardness. Thus, especially in commercial process applications, it is critical to be able to measure the Tl content of plating solutions accurately, quickly, and facilely in order to ensure proper quality of the products being manufactured. The cyclic voltametric behavior of Tl-containing gold plating bath solutions has been investigated, but quantification of its Tl content is unsatisfactory, either expensive and time consuming, or not accurate in complexed matrices. Here, we present a proprietary, electroanalytical method of Tl measurement that is fast and gives excellent accuracy and sensitivity, even in the presence of common bath breakdown products.

Electroless deposition of Ni-P/Au coating on Cu substrate with improved corrosion resistance from Au(iii)-DMH based cyanide-free plating bath using hypophosphite as a reducing agent.

The green cyanide-free gold deposition is an important development direction in electroless gold plating. However, the commonly Au(i) based cyanide-free gold plating bath always suffers from severe corrosion to the Ni–P layer and unsatisfactory service life of the bath. In this work, a green and environmentally friendly cyanide-free gold plating bath was developed with hypophosphite added as a reducing agent into the Au(iii)–DMH (5,5-dimethylhydantoin) based plating bath to retard the corrosion of the Ni–P layer. SEM micrographs combined with XRD and XPS analysis indicated that the electroless deposited gold was pure and compact. And XRD also revealed that the oriented deposition of gold was growing preferentially on Au (111). Corrosion tests, including salt spray tests, potentiodynamic polarization tests, and electrochemical impedance spectroscopy tests, indicated that the obtained Cu/Ni–P/Au coatings had significantly improved corrosion resistance performance with the loading of hypophosphite as the reducing agent. The baths remained transparent and no turbidity or precipitates were detected for 210 days, reflecting good stability. The detection for the Ni2+ concentration in the bath showed that adding hypophosphite could retard the replacement reaction between Au3+ and the Ni–P layer in part and this is important for decreasing the severe corrosion of the Ni–P layer. Moreover, Au was inactive for catalyzing the oxidation of hypophosphite during the deposition process which was confirmed furthermore via quantum chemical calculations. Therefore, our developed green cyanide-free electroless gold deposition process can beneficially provide research value and application prospects in microelectronic industry.

Investigation of Au-Ag-Cu Alloy Electrodeposition to Electromechanical Systems

Electromechanical systems, which provide electrical power and data connection between moving terminals require high conduction and erosion resistant surfaces. Transfers of electrical power and data are accomplished by the contact of drum and brush wires. The simultaneous electrochemical deposition of desired Au-Ag-Cu alloy compositions, which can be used to coat the brush wires, was investigated in this study. In the scope of the study, the static potential and cyclic voltammetry behaviours of gold, silver and copper cyanide plating baths, as well as the mixtures of binary and ternary baths were investigated to obtain suitable amount of KCN and working potential values. SEM and EDS analyses were conducted in the characterization of coated samples.

Investigation of Au-Ag-Cu Alloy Electrodeposition to Electromechanical Systems

Electromechanical systems, which provide electrical power and data connection between moving terminals, require high conduction and errosion resistant surfaces. Transference of electrical power and data are carried out by the contact of drum and brush wires. The electrochemical deposition of desired Au-Ag-Cu alloy compositions was investigated in this study. In the scope of the study, the static potential and cyclic voltammetry behaviours of gold, silver and copper cyanide plating baths, as well as the mixtures of binary and ternary baths were investigated to obtain suitable amount of KCN and working potential values. Beside SEM and EDS analyses, hardness and friction measurements were conducted in the characterization of coated samples.

Experimental and DFT study of the effect of mercaptosuccinic acid on cyanide-free immersion gold deposition.

In order to search for an effective alternative to cyanide for gold plating, mercaptosuccinic acid (MSA) was selected as the complexing agent of Au+ by open circuit potential tests and gold plating compared with 1-hydroxyethylidene-1,1-diphosphonic acid and aminomethylphosphonic acid. For the first time, a novel, stable, slightly acidic and cyanide-free gold plating bath was prepared. Scanning electron microscopy, Tafel tests, and tin dipping tests showed that the Cu/Ni–P/Au coating had a fine and even grain size, no black pad, good corrosion resistance, and good weldability. Quantum chemical calculations based on density functional theory were used to further study complexants and complexes. Molecular electrostatic potential indicates that Au+ approaches MSA in the direction of C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> O. Frontier molecular orbital theory, atomic contribution to orbital composition, condensed local softness, and average local ionization energy indicate that the coordination capacity of the S atom in MSA is much stronger than that of other atoms. Fuzzy bond order analysis shows that the S–Au–S coordination structure is the most stable form in the plating solution. UV-visible absorption spectroscopy clarifies that the wavelength is redshifted when MSA–Au(i) ions form.

Accurate and Precise Determination of Gold in Plating Bath Solution: Deep Eutectic Solvent Based Liquid Phase Microextraction – Slotted Quartz Tube – Flame Atomic Absorption Spectrometry

A sensitive, simple and green deep eutectic solvent based liquid phase microextraction (DES-LPME) method is described for the quantification of trace gold by flame atomic absorption spectrometry with a slotted quartz tube (SQT-FAAS). A 1:2 choline chloride:phenol mixture was utilized as the DES for the extraction of gold from the aqueous solution. All of the parameters affecting the extraction efficiency were optimized to increase the detection power of the FAAS. Under the optimum conditions, the presented method provided a linear range between 15 and 400 µg/L with limits of detection and quantification of 5.1 and 16.9 µg/L, respectively. An approximate 58-fold improvement was obtained in the detection power of the FAAS based on the limit of detection using the optimized DES-LPME-SQT-FAAS method. In order to check the validity/applicability of the method, recovery measurements were performed for spiked gold plating bath samples and the resulting recoveries were between 105.3% and 107.6%. The presented method was employed for real sample analysis.

Current Developments in Precious Metal Plating for the Semi - Conductor/Micro - Electronics Markets

How the metal finishing (plating) industry is meeting the technical demands of the Microelectronic market as the demand of smaller, lighter, faster, cheaper moves on relentlessly. This paper will focus in particular on Pure Gold Plating, Silver Plating and Palladium Plating for this market. Electrolytic, electroless and immersion processes will be covered outlining the operating parameters and defining applications in particular to the rapidly changing electronic packaging market within microelectronics. In this market the effects of contamination on the deposit compositions, e.g. comparing a Modern Pure Gold Plating bath with traditional Pure Gold Plating processes, can be significant and will be discussed in detail. Details on silver plating for LED applications will also be covered in this paper. How these products are moving towards more Environmentally Friendly low and non-cyanide systems will also be shown.

Development of alternative environment friendly nickel and gold plating baths

In the metal plating industry, nickel and gold plating baths are used, which contain toxic materials and cause wastewater problems. Despite these disadvantages, there is a strong need for both these types of metal plating because of their aesthetic properties. However, until now, nickel plating has not been used in conjunction with gold plating because nickel plating baths contain sulphates. In this study, gold plating on a nickel plated surface is investigated using baths containing acetylacetonate salts. The physical parameters of the plated materials, which were favourable, were determined by hydrogen embrittlement tests, visible region spectrophotometry and the Charpy impact test.

Use of nickel(II) acetylacetonate and dimethylgold(III) acetylacetonate in gold on nickel plating

This study investigates the use of non-toxic materials in nickel and gold plating baths that are used to plate gold on nickel plated stainless steel surfaces. The physical and mechanical stability and adhesion of the plating obtained using such compositions are investigated. The thickness, colour and adhesion of the plating have been studied using X-ray measurements, visible spectrometry and hydrogen embrittlement tests respectively. The plating baths employed in this study, which contained nickel(II) acetylacetonate and dimethylgold(III) acetylacetonate, were found to be good alternatives to conventional nickel and gold plating baths because they contain toxic nickel sulphate and cyanide salts.

Research on Improving the Gilding Quality for Electric Connector Contacts Made by Copper Alloy

The paper summarized the causes of influencing the gilding quality of electric connector contact bodies made by copper alloy.We put forward realiable and effective ways to solve the problems of the gilding quality,Chosing the optimum technological parametars of gold plating bath,achieving optimum structure desig of contact bodies ,improving the process of gilding are the best solutions.

DMH镀金体系在ICF空腔靶中的应用

Gold plating using DMH as complexing agent has been applied to hohlraum target. The effects of bath compositions and operating conditions on gold plating quality were investigated by scanning electron microscopy and coulometric measurement. The results show that the gold plating bath is stable. Uniform and compact gold deposits are formed in the bath containing 8 g/L gold salt and 80 g/L DMH at the cathode current density of 1.5 A/dm2, pH level of 9-10 and bath temperature of 45 ℃.

Impact of Specifically Adsorbing Anions on the Electroless Growth of Gold Nanotubes

Electroless metal deposition on nanochannel‐containing templates is a versatile route towards metal nanotubes and nanowires if the plating reaction can be sufficiently controlled. In this study, disulfitoaurate‐formaldehyde‐based gold plating baths were modified by the addition of halides, pseudohalides, and EDTA. The introduction of specifically adsorbing anions strongly affected the heterogeneously autocatalyzed plating reaction and allowed the regulation of the reaction rate and the product morphology. The new plating baths showed enhanced stability and allowed the synthesis of homogeneous nanotubes of high aspect ratios (>150) in 30 μm thick ion track‐etched polymer templates. Depending on the reaction conditions, solid and porous structures consisting of gold nanoparticles of differing size and shape were accessible. The presented strategy offers adapted gold thin films, nanotubes, and nanowires for applications in catalysis or sensing.

Gold‐gold junction electrodes:the disconnection method

The formation of gold-gold junction electrodes for application in electroanalysis is described here based on electro-deposition from a non-cyanide gold plating bath. Converging growth of two hemispherical gold deposits on two adjacent platinum microelectrodes (both 100 µm diameter in glass, ca. 45 µm gap) followed by careful etching in aqueous chloride solution was employed. During growth both gold hemispheres "connect" and during etching "disconnection" is evident in a drop in current. Gold-gold junctions with sub-micron gaps are formed and applied for the electroanalytical detection of sub-micromolar concentrations of hydroquinone in 0.1 M phosphate buffer pH 7 (E(rev) = 0.04 V vs. SCE) and sub-micromolar concentration of dopamine in 0.1 M phosphate buffer pH 7 (E(rev) = 0.14 V vs. SCE). The potential future uses in analysis and limitations of gold-gold junction electrodes are discussed.

The effect of Tl(I) on the hard gold alloy electrodeposition of Au–Co from acid baths

The mechanism of gold alloy electrodeposition from acid baths in the presence of a trace amount of Tl + was investigated using cyclic voltammetry, chronoamperometry and chronopotentiometry. Analysis of chronoamperometric measurements showed a progressive and instantaneous nucleation and growth mechanism at low and high cathodic potentials, respectively. The current time transients of hard gold baths containing Tl + showed underpotential deposition (UPD) features. The surface morphology of the resultant deposits was studied by scanning electron microscopy (SEM). The SEM studies showed that addition of cobalt leads to the formation of fine sized grains. Also with addition of thallium to the solution, enhancement and inhibition of the gold deposition were observed at low and high cathodic potentials, respectively. A bright, grain refined, coherent deposit with high hardness resulted from hard gold plating bath by addition of Tl +.

Region-selective electroless gold plating on polycarbonate sheets by UV-patterning in combination with silver activating

Abstract A simple, time- and cost-effective approach for region-selective metalization of polycarbonate (PC) surface has been established by combining photoresist-free UV-patterning with tin- and amine-free silver activating and electroless gold plating. The surface of PC sheets was exposed to the UV lights emitted from a low-pressure mercury lamp through a photomask, the micro pattern on the mask being transferred to the PC surface due to the photochemical generation of carboxyl groups on the UV-exposed region. The UV-exposed PC sheets were then treated with an ammoniacal AgNO 3 solution, so that the silver ions were chemisorbed by the photochemically generated carboxyl groups. When the Ag + -adsorbed PC sheet was immersed into an electroless gold plating bath, shiny gold film quickly deposited on the UV-exposed region, resulting in the formation of a micro gold devices on the PC surface. The whole plating process including UV-exposure, surface activating and gold plating can be completed in about 3–4 h. Attenuated total reflection Fourier transformation infrared spectrometer (ATR-FT-IR), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) and scanning electron microscope (SEM) were employed to trace the surface change during the plating process. Cyclic voltammetry (CV) and Scotch ® -tape test were employed to characterize the electrochemical properties and adhesion strength of the prepared micro gold devices, respectively. The prepared micro gold electrodes were demonstrated for amperometric detection of hydrogen peroxide.

Fabrication of gold microelectrodes on polystyrene sheets by UV-directed electroless plating and its application in electrochemical detection

Abstract A novel method for the fabrication of micro gold electrodes on polystyrene (PS) sheets by UV-directed electroless plating was developed. The microelectrode pattern was transferred onto the surface of PS sheets by exposure of the surface to UV-lights emitted from a low-pressure mercury lamp through a photo-mask. The carboxyl moieties photo-chemically generated on the UV-exposed region were used as the scaffold for further surface modifications. After amination of the carboxyl groups with ethylenediamine, adsorption of Au(III) ions by the tethered free amine groups, and reduction of the adsorbed Au(III) with NaBH 4 , a layer of gold nano-particles that served as seeds to catalyze the electroless plating was formed on the UV-exposed region (so-called being activated). Gold microelectrodes were then selectively plated onto the activated area by using an electroless gold plating bath. Water contact angle, attenuated total reflection fourier transformation infrared (ATR-FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and chemical mapping were employed to trace the surface changes during the activation process. The prepared microelectrodes showed strong adhesion to the substrates, good stability in strong acidic and alkaline solutions, and good electrochemical properties similar to standard gold-disk electrodes. The fabricated gold microelectrodes were used as the electrode bases of the three-electrode system for amperometric detection in a full PS micro electrophoresis chip, which was demonstrated for separation and detection of model analytes of dopamine (DA) and catechol (CA).

Electroplating of gold from a solution containing tri-ammonium citrate and sodium sulphite

In this work, a simple non-cyanide gold plating bath has been developed. The slightly acidic electrolyte containing tri-ammonium citrate, KAuCl4 and Na2SO3 has been utilized as the stable gold solution. It is environmentally benign, easy to prepare, easy to control and electrodeposition can be done at room temperature. Plating rates of about 10 μm/h at a current density of 4 mA/cm2 are attainable from a bath (pH 5.5) with 0.411 mol/L (100 g/L) of tri-ammonium citrate, 0.066 mol/L (25 g/L) of KAuCl4 and 0.543 mol/L (68.5 g/L) of Na2SO3. The resultant deposits are dense, with smooth morphology on both blank wafers and patterned wafers.

Gold electrodeposition for microelectronic, optoelectronic and microsystem applications

The electrodeposition of gold is a key technology in the fabrication of many microelectronic, optoelectronic and microsystem devices. In this review, we examine some recent applications, and consider the suitability of various gold plating systems for device fabrication. The properties of gold cyanide and sulfite baths and their limitations are considered first. This is followed by an analysis of the latest generation of non-cyanide baths, including the thiosulfate, sulfite-thiosulfate and ammonium gold systems. Plating baths containing mercaptoalkylsulfonic acid and hydantoin ligands are also briefly discussed. Finally an analysis of the stability of gold plating baths is presented.

A Simple Photomask with Photoresist Mask Layer for Ultraviolet-Photolithography and Its Application for Selectively Photochemical Surface Modification of Polymers

According to ultraviolet (UV) spectroscopic studies, a positive AZ photoresist film thicker than 10 (m can hardly transmit UV lights of wavelengths 200–285 nm. A simple photomask for UV photolithography was prepared using a quartz glass plate coated with a light-obstructing film of positive AZ photoresist, and the quality of the photomask and fidelity of the pattern transferred by the photomask were evaluated. The developed AZ photoresist photomask was used for fabrication of gold microelectrode on polycarbonate (PC) sheets. PC sheetswere exposed to the UV lights emitted from a low-pressure mercury lamp and passed through the photomask. The PC sheets were subjected to selective surface photolysis in the exposed area. After a series of wet chemical reactions, nano gold particles serving as the catalyst for electroless plating were deposited on the irradiated area. Gold microelectrodes were then generated by immersing the selectively activated PC sheet in an electroless gold plating bath for a specific time. Without need for a clean room, the photomasks can be prepared by a chemist in a common chemical laboratory with low-cost materials and simple procedures.