Speciation Analysis of Au(I) Electroplating Baths Containing Sulfite and Thiosulfate

Green, T. A.; Roy, Sudipta

doi:10.1149/1.2164724

Cited by 49 publications

(61 citation statements)

References 32 publications

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“…The existence of the mixed ion complex was suggested in previous studies based on the deposition potential. It was also reported that the results from the sulfide-only bath are consistent with a higher stability constant (10 27 ), rather than the commonly assumed value of 10 10 [49].…”

Section: Noncyanide Bathsmentioning

confidence: 92%

Electrodeposition of Gold

Kohl¹

2010

Modern Electroplating

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While all that glitters may not be gold, it is the most beautiful of all the elements in their pure form. The name gold comes from the Old English Anglo-Saxon word for geolo meaning "yellow" while the symbol, Au, comes from the Latin word aurum, meaning "glowing dawn." Historically gold was one of the first metals known. Gold has been valuable throughout the ages chiefly because of its physical properties of softness, ductility, corrosion resistance, density, and scarcity. The first gold coin dates back to about 560 BC. Gold cups and jewelry predating 3500 BC have been found in Iraq. The ancient Egyptians knew how to hammer gold into leaf as thin as 66 nm. The importance of gold as a form of currency was at a high point in the 1900s when most countries were on the gold standard. The bullion price of gold over the past 21 years is shown in Figure 4.1.There have been about 160 metric kilotons of gold mined since it was first discovered, and it occupies about 0.005 ppm of the earth's crust. The world demand for gold in 2007 was approximately 80,000,000 troy ounces. Figure 4.2 shows the breakdown of the gold usage by industry. Jewelry comprises the largest fraction of the usage; however, much of that is not electroplated. For jewelry applications, gold is commonly alloyed with group IB or IIB metals, particularly copper, silver, platinum, and palladium, principally to improve its strength and wear resistance.The electrodeposition of gold is a relatively new process; it has been traced to the early work of Brugnatelli in 1805 [1]. The motives behind the use of electroplated gold changed dramatically in the mid-twentieth century when the emerging electronics industry required special-purpose electrical connections. The electronics industry consumed 5,330,000 troy ounces in 1994. Figure 4.3 shows the growth in the use of gold in the electronics industry by year. The use of electroplated gold in a variety of different functions in the electronics industry has led to (1) many advances in our fundamental understanding of the electrodeposition process and (2) new electroplating technologies over the past 25 years.Electrochemically deposited gold has satisfied many of the demands of the electronics industry. Gold has the third best electrical and thermal conductivity of all metals at room temperature. Also it has high ductility and excellent wear resistance, which are important for electrical contacts. The inertness of gold prevents the formation of insulating surface oxides (as compared to metals like aluminum). Group IIB metals (e.g., gold) are not good catalysts for other reactions, thus avoiding certain problems. For example, group IB metals (particularly platinum and palladium) can catalyze the polymerization of organic molecules forming insulating layers. In addition, gold is an excellent metal for wire bonding integrated circuits (ICs). Gold wires can be bonded to pure, soft gold pads by thermocompression bonding (300-400 C at high pressure to form a weld) or thermosonic bonding (150-200 C with ultrasonic energy to fo...

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Section: Noncyanide Bathsmentioning

confidence: 92%

Electrodeposition of Gold

Kohl¹

2010

Modern Electroplating

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“…Generally, the pH value of solution affects the co-deposition behavior frequently by altering the form of complexes. It was reported that the dominant electro-active in the gold sulfite bath species was the [Au(SO 3 ) 2 ] 3-complex with the pH value ranging from 2 to 12 [18][19][20] 3 -and Sn 2 (OH) 2 2? , formed in the developed alkaline electrolyte [21,22].…”

Section: Methodsmentioning

confidence: 99%

Composition control of co-electroplating Au–Sn deposits using experimental strategies

Huang

Pan

et al. 2014

J Mater Sci: Mater Electron

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The optimal electroplating parameters for a pulse-current co-electroplating system of Au-Sn deposits in a non-cyanide electrolyte were investigated using experimental strategies, including fractional factorial design (FFD) and central composite design (CCD) coupled with the response surface methodology. pH value, ethylene diamine tetraacetic acid (EDTA) concentration, catechol concentration and metallic ions molar ratio (i.e., [Au]/[Sn]) were identified as the key factors affecting the composition of Au-Sn deposits in the FFD study. A reliable model between the response variable and the key factors of pH value, EDTA concentration and catechol concentration was established for the composition control of Au-Sn alloys in the CCD study. The standard deviation of the response variable (tin content) was set at the minimum level to determine the optimal co-electroplating parameters for the predicted composition value of Au-Sn deposits. Pair T test was conducted to validate both predicted and observed composition values under the optimal electroplating parameters, and the composition of Au-Sn deposits can be precisely controlled based on the established model. Scanning electron microscope observation and X-ray diffractometer analysis revealed that the morphology and crystalline of the Au-Sn deposits were compositiondependent.

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“…1 Now, the beginning of the reduction changes to approximately -600 mV Ag/AgCl , possibly due to a different surface conditioning promoted by sulfite. Also, it is observed a cathodic peak, indicated by a dashed arrow at -950 mV Ag/AgCl .…”

Section: Voltammetry Measurementsmentioning

confidence: 99%

“…1 Non-cyanide baths have been developed to overcome the problem of toxicity, most of them based on Au(I)-sulfite complex. 2,[3][4][5][6][7] Different reducing agents are commonly add to the Au(I)-sulfite bath, as thiourea, 5,6 hypophosphite, 4,6 borohydride, 6 dimethylamine borane (DMAB), 6 hydrazine 6 and formaldehyde.…”

Section: Introductionmentioning

confidence: 99%

“…6,9 Au(I)-sulfite baths can be unstable, due the low stability constant of the Au(I)-sulfite complex ( ), which may cause a disproportional reaction from Au(I) to Au(III). 1,3 However, the increase of the pH makes Au(I)-sulfite baths more stable since the amount of free sulfite ions decreases. 1 Formaldehyde has been used as additive in baths for electroand electroless plating over the past decades 8,10,[11][12][13][14] because of its electrocatalytic oxidation effect on various metals, including Pd, Ag, Au, Ni, Pt, Cu, and Ir, described by the following chemical equations: 8,12 …”

Section: Introductionmentioning

confidence: 99%

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Electrodeposition of gold from formaldehyde-sulfite baths: bath stability and deposits characterization

Cardoso

Filho

2011

Quím. Nova

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Recebido em 29/7/10; aceito em 18/11/10; publicado na web em 18/2/11It was investigated Au(I)-sulfite baths containing formaldehyde. As a result, high stability was achieved for baths containing formaldehyde concentration close to 10 mL L -1 with a lifetime superior to 600 days. On the other hand, cyclic voltammograms indicated that the increase of formaldehyde concentration in the bath promotes decreasing of the maximum cathodic current, so that, if the formaldehyde concentration is high, the surface areal concentration of gold will be low. Also, the lowest surface roughness was obtained for 10 mL L -1 of formaldehyde.

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Speciation Analysis of Au(I) Electroplating Baths Containing Sulfite and Thiosulfate

Cited by 49 publications

References 32 publications

Electrodeposition of Gold

Electrodeposition of Gold

Composition control of co-electroplating Au–Sn deposits using experimental strategies

Electrodeposition of gold from formaldehyde-sulfite baths: bath stability and deposits characterization

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