Gold Plating Research Articles

Effect of double zincating on microstructures and bonding strength of coatings on aluminum alloy for pulse gold plating

Effect of double zincating on microstructures and bonding strength of coatings on aluminum alloy for pulse gold plating

Investigation on the microstructure, mechanical properties and chlorine resistance of fine aluminum alloy wires

Wire bonding is a fundamental and mature technology in semiconductor packaging process, primarily using materials such as gold, silver, aluminum, and copper for the wires. To address application limitations of aluminum wires, such as low electromigration resistance and limited ductility, techniques including to enhance alloying (with Zn and Si), heat treatment, and surface treatment are employed to enhance the performance of aluminum alloy wires and broaden their application value. This study selects Al-3Zn-0.3Si (AZS303) and Al-7Zn-0.3Si (AZS703), with AZS303 undergoing gold plating to produce AC-AZS303 wires. Various high-temperature heat treatments are applied, verifying that under 400 °C conditions, the AZS series aluminum alloy wires exhibit grain growth and form single-crystal equiaxed grain structures, resulting in stable mechanical properties and excellent electrical performance. Additionally, the AC-AZS303 wires optimize resistance values through gold layer diffusion induced by the electrothermal effect.Chlorine experiments indicates that the gold plating on AC-AZS303 can't enhance the aluminum wire's resistance to chlorine corrosion. However, the alloying effect of zine and silicon elements imparts excellent chlorine corrosion resistance to the Al-Zn-Si wires. This study of bonding properties examines the bond strength and observes the bonded area of Al-Zn-Si wires after bonding. It is noted that the H400-AZS303 wire exhibits the best bond strength and bonding area, demonstrating good bonding with the substrate.

Two-Dimensional Estrone-Imprinted System on a Self-Assembled Monolayer.

In this study, a thin poly (methyl methacrylate) coating was formed on a self-assembled monolayer formed on a gold plate after chemically binding estrone. Subsequently, the estrone molecules were hydrolyzed and extracted using a solvent to form a molecular-imprinted system. The estrone-imprinted gold plate was then used as a working electrode to measure the estrone recognition ability through electrochemical methods. The recognition ability of this working electrode was evaluated for similar compounds. The selectivity factors for the seven estrone analogs were measured, and these values ranged from 0.19 to 0.67. According to the experimental results, the estrone-imprinted system showed good differentiation of estrone from other estrone analogs. Comparing these selectivity factors with those of a previous study on a cholesterol-imprinted system, the relative molecular size difference between the target molecule and similar molecules had a significant impact on the selectivity factor.

In Situ Measurement of Urea Concentration With an In-Fiber SPR-MZI Sensor.

A fiber-optic urea sensor based on surface plasmon resonance (SPR) and Mach-Zehnder interference (MZI) combined principle was designed and implemented. By plating gold film on the single-mode-no-core-thin-core-single-mode fiber structure, we successfully excited both SPR and MZI, and constructed two parallel detection channels for simultaneously measurement of urea concentration and temperature. Urease was immobilized on the gold film by metal-organic zeolite skeleton (ZIF-8), which can not only fix a large number of urease to improve measurement sensitivity of urea, but also protect urease activity to ensure the sensor stability. Experimental results indicate that the designed urea sensor with temperature compensation function can detect urea solution with concentration of 1-9 mM, and the sensitivity is 1.4 nm/mM. The proposed measurement method provides a new choice for monitoring urea concentration in the field of medical diagnosis and human health monitoring.

DNA-Templated Nanofabrication of CdS-Au Nanoscale Schottky Contacts and Electrical Characterization.

DNA-templated nanofabrication presents an innovative approach to creating self-assembled nanoscale metal-semiconductor-based Schottky contacts, which can advance nanoelectronics. Herein, we report the successful fabrication of metal-semiconductor Schottky contacts using a DNA origami scaffold. The scaffold, consisting of DNA strands organized into a specific linear architecture, facilitates the competitive arrangement of Au and CdS nanorods, forming heterojunctions, and addresses previous limitations in low electrical conductance making DNA-templated electronics with semiconductor nanomaterials. Electroless gold plating extends the Au nanorods and makes the necessary electrical contacts. Tungsten electrical connection lines are further created by electron beam-induced deposition. Electrical characterization reveals nonlinear Schottky barrier behavior, with electrical conductance ranging from 0.5 × 10-4 to 1.7 × 10-4 S. The conductance of these DNA-templated junctions is several million times higher than with our prior Schottky contacts. Our research establishes an innovative self-assembly approach with applicable metal and semiconductor materials for making highly conductive nanoscale Schottky contacts, paving the way for the future development of DNA-based nanoscale electronics.

Effect of Grain Structure of Gold Plating Layer on Environmental Reliability of Sintered Ag-Au Joints.

Gold-plated substrate is widely used in sintering with silver paste because of its high conductivity, stability, and corrosion resistance. However, due to massive interdiffusion between Ag and Au atoms, it is challenging for sintered Ag-Au joints to maintain high reliability. In order to study the effect of grain structure of gold plating layer on the environmental reliability of sintered Ag-Au joints, we prepared four substrates with different gold structures. In addition to the original gold structure (Au substrate), other gold structures were obtained by heat treatment at temperatures of 150 °C (Au-150 substrate), 250 °C (Au-250 substrate), and 350 °C (Au-350 substrate) for 1 h. Compared with the other three gold substrates, the sinter jointed on the Au-350 substrate obtained the highest shear strength. By analyzing the grain structure of the gold plating layer, it is found that the average grain size of the Au-350 substrate is the largest, and the proportion of low-angle grain boundaries is less. Few grain boundaries have a positive impact on inhibiting the excessive diffusion of Ag atoms and improving the bonding performance of the joint. Based on the above study, we further evaluated the environmental reliability of sintered joints. In 150 °C high-thermal storage, the interdiffusion of Ag and Au in the sintered joint on the Au-350 substrate was restricted, retaining stronger bonding until 200 h. In a hygrothermal environment of 85 °C/85% RH, the shear strength of the sintered Ag-Au joint with the Au-350 substrate maintained above 40.2 MPa during 100 h aging. The results indicated that the sintered Ag-Au joint on the Au-350 substrate with the largest grain size has superior high thermal reliability and hygrothermal reliability.

Impact of Concepts and Spatial Scales on Irrigation Efficiency for Sustainable Water Resources Management: A Review

This paper provides a review of different ‘irrigation efficiency’ concepts evolved over the time since the term was originally conceived, from an engineering perspective; the impact of scale, i.e., from field to basin, on savings in water demands through hightech irrigation—the efficiency paradox; the role of rice cultivation—water guzzler or recharge basin; and policies for transforming high-tech irrigation into water-conserving interventions. As these issues are interlinked, their synergetic resolution is necessary for establishing sustainable irrigated-agriculture at basin scale. There is a consensus on the utility of classical irrigation for designing the capacity of different components of an irrigation system; and also appreciation of the fact that it does not represent the true picture of water savings/losses at the basin scale. Consumed fraction-based water accounting makes a better representation of irrigation performance from field to basin scales. In literature, studies from different countries revealed the positive impact of hightech irrigation in improving land productivity and income at the field scale but without any significant water conservation for further use to other sectors/locations. Many studies also indicate that introduction of high-tech irrigation in water-scarce but abundant irrigable land regions led to increased water use, which resulted in further decline of water table and/or deterioration of groundwater quality. The increase in water demand on improving irrigation efficiency is known as the efficiency paradox or rebound effect. In water-scarce areas, high-tech irrigation should be promoted with caps on water withdrawals even if the water transfer to downstream areas or other uses is not required. High-tech irrigation is helpful in reducing transaction costs for achieving water conservation, but gold plating of irrigation infrastructure alone would not be sufficient. This study emphasizes on enactment and enforcement of policies for regulating total water withdrawal, limiting irrigated area, and adopting ecologically-compliant cropping patterns for establishing sustainable irrigated-agriculture without the rebound effect.

Seeing Things: Technologies of Vision and the Making of MormonismJoseph Smith’s Gold Plates: A Cultural HistoryVisions in a Seer Stone: Joseph Smith and the Making of the Book of Mormon

Seeing Things: Technologies of Vision and the Making of MormonismJoseph Smith’s Gold Plates: A Cultural HistoryVisions in a Seer Stone: Joseph Smith and the Making of the Book of Mormon

Absent Objects and the Study of Material Religion

Abstract This article explores how absent objects continue to work on religious communities using two case studies: the gold plates from which Joseph Smith said he translated the Book of Mormon, and the first 116 manuscript pages of that translation. Neither of these objects are available to believers now, but they played and continue to play an outsized role in the early history of the Mormon tradition, but in different ways. Based on these case studies, this article argues that scholars of material religion need to attend to the absence of objects in their explorations of how religious assemblages operate.

Дундад зууны монголчуудын алтан эмээлийн тухай

The design and practical utilization of saddles dating to the Great Mongol Empire contain diverse cultural contexts. The adornment of the pommel displays motifs of vivid, free, spiritual, and mighty subject matters. The designs of intertwined floral patterns, twisted ropes, ‘horns,’ and scroll motifs, along with depictions of deer, rabbit, and horse, are the most favored themes for nomads but are rarely observed in other cultures. As the Mongols conquered and reigned by virtue of their horses, they worshipped these animals and adorned them with the best they had to offer. The extensive use of precious metals was meant to demonstrate their power and status. The origin of gold and silver-plated saddles dates back to the Khitan (Liao) Dynasty. According to researchers the smithery traditions and technology were sustained and advanced during the Great Mongol Empire. The saddles dating to this period were embellished with gold and silver plates on the pommel, cantle, saddle bars, gullet, and rear jockey, punctuated with precious stone inlays. Meanwhile, all the leather straps of the girth, breast collar, and cruppers were adorned with gold and silver plaques of the same design. Several 13th- and 14th-century gold and silver-plated saddles unearthed in Mongolia, Ukraine, Russia, and Inner Mongolia, China, were each distinct in design yet displayed the salient features and craftsmanship traditions of the Mongols. Dragon has been the symbol and insignia of prestige and the royal court in Oriental ideology. The embellishments on the pommel, gullet, and bars are symmetric with typical Mongolian decorative design. Judging from historical resources and archaeological finds, horse harness fittings made of gold and silver were of significance to the imperial Mongols. The relatively intact three saddles in Ayurzana Altangerel’s collection in Ulaanbaatar have been attributable to the imperial court of the Great Mongol Empire, considering their level of craftsmanship proficiency, production methods and techniques, as well as the frequency of dragon motifs with three and four claws and precious stone inlays, all of which exemplify the exotic taste of the steppe people. The gold and silver arts under the Great Mongol Empire initially employed the distinct nomadic taste, traditional customs, and material culture, and further developed into a cultural continuum of a world empire, articulating and acculturizing diverse religions and cultures of all the nations under its reign. Mongolia acquired more influences from foreign cultures in both material and intellectual development, yet the arts of nomadic Mongols manifested and served as the core and essence of this worldly phenomenon, reverberating in other parts of the world.

Highly efficient ZnO/WO3 nanocomposites towards photocatalytic gold recovery from industrial cyanide-based gold plating wastewater

Discharging the gold-contained wastewater is an economic loss. In this work, a set of ZnO/WO3 was facile synthesized by hydrothermal method in order to recover gold from the industrial cyanide-based gold plating wastewater by photocatalytic process. Effect of ZnO contents coupled with WO3 was first explored. Then, effects of operating condition including initial pH of wastewater, type of hole scavenger, concentration of the best hole scavenger and photocatalyst dose were explored. A series of experimental results demonstrated that the ZnO/WO3 nanocomposite with 5 wt% ZnO (Z5.0/WO3) depicted the highest photocatalytic activity for gold recovery due to the synergetic effect of oxygen vacancies, a well-constructed ZnO/WO3 heterostructure and an appropriate band position alignment with respect to the redox potentials of [Au(CN)2]− and hole scavengers. Via this ZnO/WO3 nanocomposite, approximately 99.5% of gold ions was recovered within 5 h using light intensity of 3.57 mW/cm2, catalyst dose of 2.0 g/L, ethanol concentration of 20 vol% and initial pH of wastewater of 11.2. In addition, high stability and reusability were observed with the best nanocomposite even at the 5th reuse. This work provides the guidance and pave the way for designing the ZnO/WO3 nanocomposite for precious metal recovery from a real industrial wastewater.

Toward Commercial Cylindrical Anode Free Li-Metal Batteries: Electrochemical Study and Improvement

Lithium-ion batteries (LIBs) are one of the favorite energy storage devices that are applied to mobile and stationary energy storage applications. The widespread use of Li-ion batteries requires an increase in the energy density of each battery cell. Anode-free Li-ion Batteries (AFLIBs) are new types of LIBs models that offer high energy density. However, there are still many challenges in fabricating AFLIBs toward commercial use, mainly improving the battery cycle and the efficiency of intercalation/deintercalation of Li-ion between two electrodes. In this research, the fabrication of AFLIBs is studied, optimized, and integrated with cathode materials to be commercial cylindrical full-cell LIBs. The comparison of an active cathode material between LiFePO4 (LFP) and NMC622 showed that NMC622 performed better than LFP. The optimum condition of cathode materials coating thickness is 200 microns achieving 2.75 mAh cm-2 of area capacity. Furthermore, the gold platting strategy is proposed to modify the Cu foil surface to improve the electrical performance and stability of AFLBs. As a result, the control gold plating with 5 nm thickness increases the full-cell capacity of AFLBs to 142.89 mAh g-1 with a capacity retention percentage of 95.41% after five cycles.

Electrochemical Processes in Sulfite Gold Plating Solutions and Some Properties of Gold Coatings

The kinetics of gold electrodeposition from Au(I) sulfite solutions have been studied by impedance spectroscopy and polarization measurements on a rotating disk electrode. Two solutions were used: a Na3Au(SO3)2-based electrolyte with 2,2-bipyridine as stabilizing additive and an electrolyte containing (NH4)3Au(SO3)2. The polarization curves show a rise in current with increasing rotation speed of the electrode up to 300 rpm. It was found that contributions to the impedance spectra come from the steps of charge transfer and gold ad atom incorporation into the crystal lattice, as well as from the relaxation of surface coverage with adsorbed species in an inhibiting layer. An equivalent electrical circuit was suggested to describe the impedance spectra. This circuit provides good approximation of impedance plots for both electrolytes at all electrode potentials. The overall cathodic reaction in both electrolytes appears to consist of the steps of the same nature. Some properties of the Au coatings (micro hardness, size of crystallites) were also determined. Soft gold coatings with micro hardness of 0.66 GPa are obtained from the electrolyte based on (NH4)3Au(SO3)2, the coatings with a higher micro hardness (~0.85 GPa) are deposited from the electrolyte containing 2,2-bipyridine.

Photocatalytic Gold Recovery from Industrial Gold Plating Effluent by ZnO Nanoparticles: Optimum Condition and Possible Applications.

The comparative study of photocatalytic gold recovery from cyanide-based gold plating solution was explored via commercial and hydrothermally synthesized ZnO nanoparticles (NPs). The effects of hydrothermal temperatures on the properties and photocatalytic activities of synthesized ZnO NPs were investigated. In addition, the effects of operating parameters including types of hole scavenger, concentrations of the best hole scavenger, the initial pH of wastewater, and photocatalyst dosages were examined. The obtained results demonstrated that the commercial ZnO NPs exhibited a higher photocatalytic activity for gold recovery than that of the synthesized ones owing to their good crystal quality and the presence of non-lattice zinc ions and appropriate non-lattice oxygen ions. Via the commercial ZnO NPs, the gold ions were almost completely recovered from the cyanide-based gold plating effluent within 7 h at an initial pH of 11.0 in the presence of 10 vol % C2H5OH and 1.0 g/L of photocatalyst loading with a pseudo-first-order rate constant of 0.2637 h-1. Finally, the resultant gold-decorated ZnO NPs exhibited a higher photocatalytic property for color reduction from industrial wastewater and antibacterial activity than that of fresh ZnO NPs. The results obtained in this study possess benefits and pave the way for waste remediation and management for the plating industries.

Bimetallic metasurface broadband perfect absorber for high-efficiency thermal photovoltaics

We theoretically propose and demonstrate that broadband polarization-insensitive perfect visible light absorption can be realized in a periodic bimetallic nanotriangle structure with a thick gold plate. The average absorption is 95.79% from 400 nm to 800 nm. The multiple localized surface plasmon resonances of the bimetallic nanostructure are the major contributions to this broadband perfect absorption in the visible region. Meanwhile, the physical mechanism of the broadband perfect absorption of the bimetallic nanostructure can be well interpreted by impedance matching theory. Moreover, the average photo-thermal conversion efficiency is up to 93% over a wide temperature range.

Infrared BRDF measurement based on projection reconstruction with attenuated aperture filter effects

The Bidirectional Reflectance Distribution Function (BRDF) is a basic function that describes the spatial reflectivity of an opaque surface. Existing BRDF measurements are related to the size of the detector aperture because the values are not the true BRDF but an average over the aperture, and high spatial resolution and high SNR cannot be achieved simultaneously. In addition, the detection positions of the aperture cannot perfectly cover the entire hemisphere, and the measurement is not complete. In this paper, BRDF measurements were combined with projection reconstruction, and the mapping between the detected signals and the BRDF over a discrete hemispherical mesh was constructed. The spatial resolution of the reconstruction was the same as that of the discrete mesh, rather than the aperture size, and the aperture filter effect was attenuated. Simulations and a frosted gold plate measurement experiment were performed to verify the effectiveness of the proposed reconstruction method.

Enhanced repulsive Casimir forces between gold and thin magnetodielectric plates

Enhanced repulsive Casimir forces between gold and thin magnetodielectric plates

Energy-efficient electrochemical recovery of gold enabled by a thiourea-based electrolyte system

The application of non-cyanide baths in electroplating for gold recovery has drawn significant attention due to their clear benefits on the environment and human health. Among these alternatives, thiourea has emerged as a promising non-cyanide bath, and yet high energy and reagent consumption has impeded its widespread adoption. Herein, an energy-efficient gold recovery process via electroplating was developed to reduce bath depletion. The redox potentials of gold deposition using thiourea electrolyte were examined through linear sweep voltammetry, and the consumed energy during the electrochemical plating of gold was quantified. The gold deposition was achieved in the two-electrode system enabling a 97% recovery under 0.3 V of the cell voltage. The proposed system exhibited a significant reduction in energy consumption to 0.129 kWh∙kg−1, implying that the oxidation of free thiourea on the anode mainly contributed to the decrease in the applied voltage and energy. Furthermore, the suppression of the bath consumption was evaluated compared with electroless plating, another reliable deposition process, throughout monitoring gold desorption and deposition efficiencies during the cyclic use of thiourea. The retardation of the sorbent consumption was observed in the electroplating during the consecutive cycles, which inferred that the reduction of its oxidized form, formamidine disulfide, led to the regeneration of the agent on the cathode. Thus, the suggested electroplating process with a gold-thiourea bath shows great potential as a workable means of gold recovery from an economic standpoint with its low energy and sorbent consumption to realize the commercialization of urban mining in the electronic industry.

Preserving the Asante cultural craft of traditional goldplating: Lessons from Asante goldsmiths

Various techniques are used by jewellers in Ghana in depositing a film of gold on surfaces of jewellery items. Although traditional goldplating has and continues to chalk a high level of excellence in jewellery making in Ghana, little documentation has been done on it. While traditional goldplating has been practiced for decades in Ghana, the introduction of electroplating into jewellery in Ghana is downplaying its relevance. Therefore, the purpose of the study was to find out how indigenous Asante goldplating technique is done in Ghana. The study adopted the use of an art-based research design under the qualitative research approach where personal interviews, photographs, and participatory observation were used for collecting qualitative data from 19 purposively sampled Asante’s goldsmiths at Manhyia and Ayeduase in Kumasi, Ghana using expert sampling. The findings of the study have shown that traditional gold plating is an aesthetically pleasing, low cost and efficient technique used by the Asante goldsmiths that has not lost its worth. The study contends that skills and knowledge in traditional goldplating should be passed on from goldsmiths to jewellers and other apprentices who are interested in learning the craft. This would help preserve and promote this rich cultural craft for posterity

A study on ancient casting method via microstructures of impurities and copper found in bronze excavated from the Unified Silla Period (7th to 10th centuries)

At the Hwangnyongsa temple site, which was founded in 633, at Dongdaebong Mountain in Korea, a large number of gilt-bronze artefacts have been excavated. Optical microscopy, X-ray fluorescence, scanning electron microscopy, energy dispersive X-ray spectroscopy, focused ion beam and transmission electron microscopy were used to identify the structure of specimen and impurities. This article investigated the impurities and copper grains in bronze Buddha robes from the Hwangnyongsa temple site to determine the ancient bronze craft technology in the Unified Silla period (seventh–tenth). The XRF results of the specimens indicated that they were made using an alloy of copper and tin, and gold plating was only added on the front side. The microstructure of the specimen was confirmed to be a recrystallized equiaxed hexagonal structure with twins and impurities. The EDS results of the impurities indicated the molar ratio of Cu:S was 2:1, and the electron diffraction pattern substantiated this result by indicating Cu2S (JCPDF 33-0490). The surface of the specimen consisted of a highlead layer and copper grains. It was hypothesized that the copper grains were formed by the reaction of Pb with the matte (Cu2S) during casting. Lead with black gas would aid in the production of high-quality bronze. The copper grains used were found in Silla, as they have been detected in Koryo bronze artefacts. Hence, it is plausible that the ancient artisans knew that lead provided good bronze quality during the casting process.