Tin Electroplating Research Articles

A novel nanoporous bismuth electrode sensor for in situ heavy metal detection

A novel modified nanoporous bismuth electrode (modified-NPBiE) sensor was prepared by consecutive procedures which consist of bismuth (Bi) and tin (Sn) electroplating, thermal treatment for alloying Bi-Sn film, and selective chemical dealloying of Sn. The newly prepared modified-NPBiE sensor exhibited improved lifetime (2.7 times longer than a conventional nanoporous Bi-filmed electrode with over 40 repeated measurements) sensor with lower relative standard deviation (RSD), indicating enhanced stability and reproducibility for heavy metal detection. Using square wave anodic stripping voltammetry (SWASV), two noticeable peaks were observed at −0.65 V and −0.45 V associated with stripping currents of Cd2+ and Pb2+ in 0.1 M acetate buffer solution at pH 4.6, respectively. The calibration curves showed strong correlations with respect to various concentrations of Cd2+ and Pb2+ with the limit of detection (LOD) of 1.3 ppb for Cd2+ and 1.5 ppb for Pb2+. The newly modified-NPBiE sensor was then successfully applied for detecting Cd2+ and Pb2+ in a tap water environment and exhibited an acceptable performance for measuring heavy metals with a good reliability.

Mesoporous anodic tin oxide with two-dimensional macroporous network

Here, we report a single-step anodic oxidation process to form a micron-scale island array of mesoporous tin oxide without any template. The grain boundary of an electrodeposited tin metal layer proved to be diffuse with a width of a few hundred nanometers. Such a diffuse boundary with high-surface energy might be preferentially dissolved during anodic oxidation to form a two-dimensional macroporous network in the mesoporous tin oxide film. In a mixed anodization solution of oxalic acid and an etchant of tin metal (i.e., methanol), the removal of the diffuse grain boundary was significantly promoted and led to a clear island array of mesoporous tin oxide. The size and density of the mesoporous tin oxide islands were tunable by varying the current density applied during the tin electroplating.

Electrochemical and Structural Characterization of Electrodeposited Tin: Influence of the Additive Alkoxylated β-Napthol

Electrochemistry of tin has been studied for several decades. Nevertheless, the effect of the electrolyte additives on the electrochemical reaction and on the deposited structure is still an open field of research. Tin can be plated from both acidic and alkaline solution. Plating from the acidic electrolytes is more common and the electrochemical equivalent is twice that in alkaline solution. However, deposits plated from the acidic electrolyte without additives are often non-compact, porous and dendritic. Organic molecules are needed to add into the electrolyte in order to obtain homogeneous, compact tin coatings. One of the first additives introduced for this purpose in the tin electroplating is -naphthol. Despite of its main disadvantage, being relatively easily oxidized under plating conditions, it is used up to now. A more stable form of this additive would be akoxylated β-naphthol (ABN, C12H12O2). It influence on tin plating has not been described in literature yet. Within this work the influence of the ABN additive in the acidic electrolyte on the electrochemical reaction and deposited structure of tin has been studied. Electrochemical experiments were performed in tree electrode setup using Ag/AgCl as a reference electrode and pure tin as a counter electrode. Reaction kinetics was studied with the polarization measurements on rotating disc electrode and Tafel measurements. For this purpose chloride based (pH ~ 5) and methane sulfonic acid (MSA, pH ~ 0.5) electrolytes have been prepared. Electrodeposits of tin with the thicknesses of ca 7 µm and 25 µm were obtained on flat brass substrates. Surface morphology and preferred crystal orientation were studied and by Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). Comparison of the structural characterization of the thicker and thinner sample has been made. The average grain sizes were estimated and compared by two different methods. The Heyn lineal intercept method from the top view on unpolished samples was compared with the EBSD analysis from the fine polished samples. Results from the reaction kinetics showed a more pronounced inhibition effect of the ABN in the chloride electrolyte. In this solution suppression of H2 evolution and decrease in cathodic current density was detected with the increased additive concentration. In the case of MSA electrolyte, there was no difference in the measured cathodic current for the studied ABN concentration range. Further experiments showed that ABN inhibition effect in MSA solution was suppressed by the creation of tin- citrate complexes. Results from the exchange current density confirm the observation that the electron transport on the electrode-electrolyte interface is more influenced by the tin-citrate complexes than by the presence of ABN. In comparison to the chloride electrolyte, higher ABN concentrations are needed for blocking electrode active sites. An electrochemical quartz crystal microbalance was used in order to study the influence of the concentration of the ABN and the complexing agent in the electrolyte on the suppression of hydrogen evolution and thus the efficiency of the tin deposition. The EBSD analysis showed more complex structure and smaller grain size in comparison to the Heyn linear intercept method (HLIM) for the coatings deposited from the MSA electrolyte. According to HLIM, an increase of ABN concentration would lead to an increase in average grain size with no changes in the main crystal orientation. In the case of the coatings deposited from the chloride based electrolyte the results from both HLIM and EBSD analysis were in agreement. With the increased of the ABN concentration a grain refinement effect and changes of the main crystallographic orientation from (101) to (400) were detected. The addition of ABN influences the electrodepoition of tin differently in the two electrolytes investigated. In the chloride based electrolyte an inhibition effect is dominant while in the case of the MSA electrolyte this effect was overlaid by the presence of tin-citrate complexes.

Least lead addition to mitigate tin whisker for ambient storage

Long term surface evolution of matte tin electroplating has been investigated under room temperature to understand the tin whisker mitigation by a trace amount of lead addition. No whisker growth has been observed on all the Sn–xPb samples (1 ≤ x ≤ 10 wt%), while at least 3 wt% of Pb addition is required to alter the columnar grain structure of pure Sn plating to equiaxed grains. The mitigation mechanism by such a trace amount of Pb is not caused by the grain texture control, but is due to the less inter-metallic composite (IMC) growth; the segregated Pb at the columnar grain boundaries disrupts the IMC growth, and releases Sn grain boundary migrations to relax the internal stress. This mechanism of stress relaxation and whisker growth suppression suggests that lead-free Sn plating without whisker growth can be realized by co-plating Sn with a Pb-like metal element that precipitates at the grain boundary to interfere with the IMC growth.

Study of Tin Electroplating Process Using Electrochemical Impedance and Noise Techniques

The tin electroplating process was studied by means of electrochemical impedance and noise (EN) technique. Scanning electron microscopy (SEM) was used to investigate the morphology of tin electrodeposits. Electrochemical impedance results reveal that charge transfer resistance of tin electroplating decreases with the potential bias η exponentially at this experimental condition. It is found that the EN generated at high current density has large potential oscillation amplitude and positive potential drift, while the EN show small noise amplitude at low current density. With the decrease of current density, the corresponding deposit changes from large conglomerate particles to compact. New parameters are proposed to cultivate the relationship between the EN feature and the structure of tin deposits. The variation trend of Parameter n2 was found to be in accordance with the crystallite size. For different Sn2+ concentrations, the oscillation amplitude of the potential noise at low concentrations are much larger than that of high concentrations, which may be correlated with that tin electroplating process is coupled with hydrogen evolution at low Sn2+ concentrations.

Snめっき皮膜へのレーザ溶融処理

Snめっき皮膜へのレーザ溶融処理

Electroless Nickel Plating and Electroplating on FBG Temperature Sensor

Abstract Metal-coated fiber Bragg grating(FBG) temperature sensors were prepared via electroless nickel(EN) plating and tin electroplating methods on the surface of normal bare FBG. The surface morphologies of the metal-coated layers were observed under a metallographic microscope. The effects of pretreatment sequence, pH value of EN plating solution and current density of electroplating on the performance of the metal-coated layers were analyzed. Meanwhile, the Bragg wavelength shift induced by temperature was monitored by an optical spectrum analyzer. Sensitivity of the metal-coated FBG(MFBG) sensor was almost two times that of normal bare FBG sensor. The measuring temperature of the MFBG sensor could be up to 280 °C, which was much better than that of conventional FBG sensor.

Mechanism of Generation and Growth of Whiskers on Tin Electroplating

Generation and growth of whiskers on tin electroplating was studied by scanning electron microscopy and X-ray diffraction. When the surface of the plating, whose thickness was 1 mm, was etched by argon ion beam to remove native oxide scale and kept in a vacuum, whiskers were rarely observed but many nodules were formed. While residual stress of tin plating (1 mm) and the number of whiskers increased with the amount of Cu6Sn5 formed between the tin plating and copper substrate, the 10 mm thickness specimen showed no meaningful change and no whiskers were found. The orientation of whiskers was shown to be identical throughout a crystal by electron backscattering diffraction even when kinked. The mechanism of generation and growth of whiskers is considered to be due to diffusion of tin atoms induced by inhomogeneous strain field, formation of vacancies, and the resulting increase in volume of the grain receiving the tin atoms. Energy change in the growth of whiskers was modelled and calculated, and the main factor determining the growth was found to be the formation enthalpy of a vacancy and the entropy of configuration. [doi:10.2320/matertrans.MRA2008236]

すずめっき皮膜からのウィスカ発生・成長機構

Generation and growth of whiskers on tin electroplating was studied by scanning electron microscopy and X-ray diffraction. When the surface of the plating whose thickness was 1 μm was etched by argon ion beam to remove oxide film and kept in a vacuum, whiskers were rarely observed but many nodules were formed. While residual stress of tin plating (1 μm) and the number of whiskers increased with the amount of Cu6Sn5 formed between the tin plating and the substrate of copper, that of the specimen whose thickness was 10 μm showed no meaningful change and no whiskers were found. The orientation of a whisker was shown to be identical throughout the crystal even in a kinked one by electron backscattering diffraction. The mechanism of generation and growth of whiskers is considered to be due to diffusion of tin atoms induced by inhomogeneous strain field, formation of vacancies, and its resulting increase in volume of the grain which received the tin atoms. Energy change in the growth of whisker was modelled and calculated, and the main factor which determines the growth was shown to be the formation enthalpy of a vacancy and the entropy of configuration.

A unique electroplating tin chemistry

A novel tin electrodeposition chemistry and process has been developed at Bell Laboratories, Lucent Technologies, New Jersey, USA. This process produces smooth, satin bright tin deposits which have stable, large grain structures. The deposits contain very low organic content and, as a consequence, exhibit excellent ductility, solderability and reflowability. The chemistry is capable of operating at elevated temperatures over a wide range of current densities, and is, thus, applicable to rack, barrel and reel‐to‐reel operations. All chemical components, including breakdown products are fully analyzable with conventional analytical methods. Extensive bath life studies show that the deposit appearance and material properties, including grain structures, are stable in relation to the age of the electroplating chemistry. In addition, the grain refiners used are highly stable, and have few breakdown products as the chemistry ages. All these features imply a robust process which has been confirmed in various manufacturing environments. This tin electroplating process has been utilized in plating coatings for connectors, solder bumps, PWBs and components for semiconductor applications.

貴金属床義歯フィニッシングライン部漏洩防止に関する研究 表面改質法とフィニッシングライン部形態について

The adhesion between 4-META resin and two kinds of precious metal alloy (Au-Ag-Pd alloy, Type IV gold alloy) treated by six kinds of surface modification methods, Adlloy, M-primer, V-primer, Silicoater, Type I Tin electroplating, and Type II Tin electroplating, was examined in order to find a way to prevent marginal leakage at the finishing line area of precious metal alloy base denture. The adhesiveness was evaluated by the percolation test and the shear bond strength. Two kinds of finishing line type, the buttjoint type and the slope type, were studied by the percolation test after applying these adhesion systems to removable partial denture with precious metal alloy base.The results were as follows:1. Precious metal surface modifications by Adlloy surface modification method and Type II Tin electroplating method improved the adhesiveness.2. Precious metal surface modifications by Adlloy surface modification method and Type II Tin electroplating method were improved the shear bond strength.3. By Adlloy surface modification method or Type II Tin electroplating method and the slope type finishing line, marginal leakage was prevented.From the results, it was suggested that marginal leakage in the finishing line area of precious metal alloy base denture could be prevented by the Adlloy surface modification method or Type II Tin electroplating method and the slope type finishing line.

Improving orthodontic bonding to gold alloy

Flat tabs of cast gold alloy (n = 156) were subjected to either of three surface treatments: (1) roughening with diamond bur, (2) aluminum oxide sandblasting, and (3) sandblasting plus tin electroplating. Mandibular incisor edgewise brackets were bonded with Concise (BIS-GMA resin) (Unitek, Monrovia, Calif.) or Superbond C&B (4-META metal bonding resin) (Sun Medical Co. Ltd., Kyoto, Japan), or with Concise after application of an intermediate resin. All-Bond 2 Primers A and B (Bisco Dental Products, Itasca, III.), or B alone. All specimens were stored in water at 37° C for 24 hours, and 60 were then thermocycled 1000 times from 5° C to 55° C and back. The tensile bond strength testing was performed in a Lloyd 1000R machine (Fareham, Hants, England). Alignment and uniform loading during testing were secured by engaging a hook in a circular ring soldered onto the bracket slot before bonding. Similar control brackets ( n = 24) were bonded with Concise to extracted human premolars and lower incisors according to a routine procedure. Bond failure sites were classified by a modified ARI system. The results showed that sandblasting produced significantly stronger bonds to gold alloy than roughening with diamond bur. Superbond C&B provided significantly stronger bonds to gold alloy than Concise. There were generally insignificant differences in bond strengths between the water stored and the thermocycled specimens. Bond failures of Concise to sandblasted plus tin-plated gold alloy invariably occurred at the gold/adhesive interface, whereas those of Superbond C&B occurred within the adhesive or in the adhesive/bracket interface. The bond strengths obtained with Superbond C&B and sandblasted gold alloy surfaces were comparable to those of the brackets bonded to conventionally etched human teeth with Concise. Tin-plating improved the orthodontic bond strengths to sandblasted gold alloy only marginally. The bond strength of Concise to sandblasted gold alloy was significantly improved with the intermediate application of All-Bond 2 primers A and B. It is concluded that successful bonding to gold alloys is feasible with several combinations and clinical recommendations for bonding brackets and lingual retainer wires to high-noble alloy surfaces are discussed. (A M J O RTHOD D ENTOFAC O RTHOP 1995;108:510-8.)

接着性レジンの貴金属合金床への応用 Ｇａ‐Ｓｎ合金（Ａｄｌｌｏｙ）による被着金属表面改質法とＳｎ電析法の接着性の比較

A new simple modification method for adherend metals surface by using liquid Ga-Sn alloy (Adlloy) was investigated to applicate for the precious metal alloy denture. Surface of silver based alloy containing 12 wt% gold was modified by Adlloy and applied 4-META resin. The adhesive ability was studied by percolation tests and shearing bond strength, and compared with the results of tin electroplating method.The surface modification by Adlloy showed lower percolation ratio and higher shearing bond strength than tin electroplation method, suggesting that the method is effective for application to precious metal denture and would prevent percolation of salivary and food debris at the finishing line of denture.

Laboratory scale electroplating and processing of long lengths of in situ Cu3Sn superconductors

Abstract The high temperature gradient solidification (HTGS) system for continuous casting of 12.7 mm diameter rods of in situ Cu-Nb is briefly reviewed. A laboratory scale continuous tin electroplating system is described and used to evaluate the effect of various parameters of the alkaline and acid baths plating process. Tin electroplating is shown to be simple and reliable. With an 8 m immersion length production speeds of ∼ 1 m min −1 are possible in an alkaline bath at 80°C. An acid bath gives satisfactory tinning deposits with a production speed of up to 3 m min −1 at room temperature.