Electrochemical dissolution of tin in methanesulphonic acid solutions

High-rate electroplating of tin on a moving steel strip is generally carried out in cells with dimensionally stable anodes. To obtain a matt tin deposit a concentrated acidic tin methanesulphonate solution containing a small concentration of sulphuric acid is used. The concentrated tin methanesulphonate solution is prepared by dissolution of tin particles with oxygen in a special column. To describe this dissolution process electrode reactions (namely, reduction of oxygen, hydrogen peroxide and hydrogen ions on a tin electrode and oxidation of tin) were studied using electrochemical techniques. It was concluded that on tin, oxygen is almost entirely reduced to water and that H₂O₂ cannot corrode tin directly, but its decomposition products, for instance oxygen, can. The exchange current density and the charge transfer coefficient for the investigated electrode reactions are estimated. The dissolution of tin by oxygen is determined by the kinetic parameters of the oxygen reduction reaction and by the mass transfer of (i) dissolved oxygen to and (ii) Sn²⁺ ions from the tin electrode surface. Hydrogen evolution can be neglected during the dissolution of tin in the presence of oxygen. Moreover, it was found that the rate of tin corrosion increases with (i) increasing H⁺ concentration, (ii) oxygen concentration, (iii) convection intensity and (iv) temperature. It is likely that the tin surface is not covered with oxygen during corrosion in pure methanesulphonic acid solutions, but an oxide layer may be present on the tin surface during oxygen corrosion in pure sulphuric acid solutions. This oxide layer may hinder the oxygen corrosion of tin.     

The effect of foreign atoms on the properties of electrolytic zinc powders

Kinetic and morphological studies have been made of the deposition of zinc powder on steel substrate, from pure alkaline zincate electrolytes and with small amounts of lead and tin ions in the electrolyte. The rate of co-deposition of hydrogen has been followed volumetrically and the current efficiency of zinc deposition calculated as a function of potential.The addition of lead and tin was found to have a profound effect on the properties of the powder. The dendritic powder, obtained from pure zincate solutions, changes with the addition of lead into a mossy deposit consisting of very small crystallites. Both additives increase the specific surface area of the powder and the average lattice parameters. Hydrogen evolution per unit real surface area and hence the corrosion of the powder are somewhat inhibited by both additives.Reported at the Symposium on Electrocrystallization, 140th Meeting of the Electrochemical Society, Cleveland, Ohio, October 1971.     

Synergistic effects of benzalacetone and benzophenone on the electrocrystallization of tin from acid stannous sulphate solutions

The synergistic effects of two kinds of aromatic ketones (benzalacetone (BA), benzophenone(BP)) and N,N-bis(polyoxyethylene)octadecylamines (POOA) on the surface morphology and the crystal orientation of electrodeposited tin from acid stannous sulphate solutions have been studied by electrochemical methods, scanning electron microscopy and X-ray diffractometry. BA itself had no effect on the reduction of tin (II) ions, but the reduction product of BA had a strong inhibitory effect on the reduction of tin (II) ions. However, the inhibitory effect of BP was stronger than that of the reduction product of BP. POOA induced a uniform deposition of tin over the whole surface, but the crystal grain size and the surface roughness of electrodeposited tin were relatively large. On the other hand, fine-grained and smooth electrodeposited tin, which had a preferred orientation with the (10 0) plane parallel to the surface, were obtained from acid stannous sulphate solutions containing POOA, BA and BP due to the synergistic effects of the three kinds of adsorbed species. It was found that BA has a levelling action and BP has a grain refinement action.     

Cathodic syntheses of tin alkyls—I. Reduction of acrylonitrile in aqueous alkali

The electrochemical behaviour of a tin cathode in alkaline solutions of acrylonitrile has been investigated by studying polarisation curves and product analysis. The only interpretation which is consistent with these and earlier observations involves a mechanism for the reduction of acrylonitrile in which adsorbed cyanoethyl radicals are the key intermediates. At low acrylonitrile concentrations those radicals activate the surface towards hydrogen evolution, at intermediate concentrations inhibit it, and at high acrylonitrile concentrations enable tin atoms to be extracted from the surface with the formation of tetracyanoethyl tin. The yield of this product is favoured by using saturated solutions of acrylonitrile and low negative potentials.     

Surface morphology and crystal orientation of electrodeposited tin from acid stannous sulphate solutions containing various additives

The changes in surface morphology and crystal orientation of electrodeposited tin from acid stannous sulphate solutions containing 1 mm N,N-bis(tetraoxyethylene)octadecylamine (TOGA) and various concentration (0.2–2 mm) of benzalacetone (BA) have been studied as functions of electrolysis time or BA concentration by electrochemical methods, scanning electron microscopy and X-ray diffractometry. The inhibitory effect on the reduction of the tin (II) ion became stronger with increasing concentration of BA. In the presence of both TOOA and BA, when electrolyses were carried out at the more negative potentials than the reduction potential of BA, the reduction product of BA induced reticular crystals (network structure) of tin over the whole surface. This structure appeared in the early stage of electrolysis and exhibited an intense (200) diffraction peak. On the other hand, the crystal grain size and the surface roughness of electrodeposited tin became smaller with increasing concentration of BA from 0.2 to 2 mm. Further, fine-grained and smooth electrodeposits of tin were obtained from acid stannous sulphate solutions containing TOOA and high concentration of BA due to the synergistic effect of these adsorbed species.     

Synergistic effects of adsorbed species on the surface morphology and crystal orientation of electrodeposited tin

The synergistic effects of adsorbed species (polyoxyethylenealkylamine (POAA), diphenylamine-crotonaldehyde reaction product (RP) and benzalacetone (BA)) on the surface morphology and crystal orientation of electrodeposited tin from acid stannous sulfate solutions have been studied by means of various electrochemical methods, scanning electron microscopic observation and measurements of X-ray diffraction patterns. Needle-like or columnar electrodeposits of tin were obtained from acid stannous sulfate solution in the absence of adsorbed species. On the other hand, fine-grained, smooth and compact electrodeposits of tin, which had a preferred orientation with the (200) plane parallel to the surface, were obtained from acid stannous sulfate solutions containing POAA, RP and BA due to the synergistic effect of the three kinds of adsorbed species. It was found that POAA acts to produce a uniform tin deposition over the whole surface, RP acts as a grain refiner and BA has a leveling action.     

Stannous chloride—an effective reducing agent for the removal of selenium(IV) from acidic solution

BACKGROUND: Selenium removal from aqueous solutions can be a significant industrial problem, particularly in the metallurgical industry. In order to evaluate new reducing agents for this application, the reduction of selenious acid (H₂SeO₃) species with stannous ions (Sn²⁺) from weakly acidic sulfate solutions containing 300 mg L^?1 of selenium at 23 °C was studied. RESULTS: At initial pH values < 1.3 and molar ratio ≥ 2, less than 0.5 µg L^?1 of selenium(IV) remained in solution after reduction. The reductive precipitation reaction started as soon as the stannous ions were added to the selenium‐bearing solution and was completed in less than 5 min. The reaction products, characterized using X‐ray diffraction, electron microscopy, particle and surface area measurements, X‐ray photoelectron spectroscopy and chemical analysis, were composed of approximately equal amounts of tin selenide and tin dioxide. In addition to tin selenide a minor amount of selenium(IV) was found to be removed via adsorption on the tin dioxide formed in situ. Tests with a complex industrial solution also resulted in full and stable selenium precipitation. CONCLUSION: Stannous ions were found to be very effective in removing selenious ions from synthetic and industrial solutions, producing very stable precipitates. Copyright © 2012 Society of Chemical Industry     

钢铁浸镀铜锡合金工艺研究

采用硫酸铜、硫酸亚锡为主盐，加入络合剂、光亮剂、锡盐稳定剂，研究成功了一种新的浸镀铜锡合金工艺。探讨了主要成分的影响，检测了镀液镀层性能。所形成的浸镀层结晶细致、光亮，为银白色镀层，与钢铁基体结合力好，覆盖能力高，与其它镀层配套性好，是一种替代氰化镀铜锡合金的新工艺。     

Effects of additives on the electrodeposition of tin from an acidic Sn(II) bath

Additive effects of formaldehyde, propionaldehyde and benzaldehyde on the deposition of tin in acidic solution of tin(II) sulfate have been investigated. The effects of these additives on cathodic polarization and a.c. impedance was measured by galvanostatic or potentiostatic methods, respectively. The reduction products of the aldehyde during the deposition and the diffusion coefficient of Sn(II) in various solutions were also determined.     

添加剂对甲基磺酸盐镀锡液性能的影响

甲基磺酸盐镀锡液是一种环保、稳定、性能优良的新型镀锡体系,选择适宜的添加剂并确定其质量浓度是保证镀锡层质量的关键.借助于电化学测试、赫尔槽实验、远近阴极法、内孔法和扫描电镜等方法,考察了几种添加剂单独和复合使用时对镀液性能和镀层表面质量的影响.结果表明:OP乳化剂和试剂A可显著提高Sn2+还原时的阴极过电位,试剂B对获...     

Hydrogen production from water by reduced tin oxide

The production of hydrogen from water by reduced tin oxide has been examined under various experimental conditions. It has been concluded that the reactive species decomposing water is metallic tin. The coexistence of SnO₂ with metallic tin enhances the rate of hydrogen production remarkably. The effect of SnO₂ has been ascribed to the enlargement of surface area of tin metal by its dispersion on the surface of SnO₂. Solid additives such as Pd, Pt, WO₃, CuO and CaO showed a large promoting effect for hydrogen production. The effect of the additives may be explained by increase in the surface area of tin metal or by the spill-over of the activated water by additives onto the surface of SnO₂ or tin metal.     

Codeposition of copper and tin from acid sulphate solutions containing polyether sintanol DS-10 and benzaldehyde

Cu(II) and Sn(II) reduction in acid sulphate solutions containing polyether laprol DS-10 and benzaldehyde (BA) was studied by means of impedance, voltammetric, XPS and XRD techniques. Both additives demonstrate weak surface activity on copper substrate in Cu(II) solutions in the absence of halide impurities. In contrast, their effect is overwhelmingly higher in the Sn|Sn(II) system. The additives induce a significant increase in Sn-electrode impedance and simultaneous strong inhibition of Sn(II) reduction over a wide range of cathodic polarizations. The effects of sintanol and BA in mixed Cu(II) and Sn(II) solutions demonstrate a kind of synergism. Underpotential deposition of tin on foreign (copper) substrate is observed at potentials more positive than the equilibrium potential of the Sn|Sn²⁺ system. Incorporation of tin into the Cu crystalline lattice results in the formation of multiphase material containing pure copper, α-CuSn phase, and intermediate hexagonal hcp phase. Formation of the pure tin phase occurs at more negative potentials and results in a strong inhibitive adsorption that manifests itself in the development of a deep voltammetric minimum. The tin content in the coatings depends on BA concentration and, particularly, on the electrode potential.     

Nucleation and growth of tin on low carbon steel

The nucleation and growth of tin from stannous sulfate and sulfuric acid with an organic additive of gelatin was studied on low carbon steel. Investigations were conducted by linear sweep voltammetry and current step methods. The agitation effect on the morphology of tin deposits was also studied. From the results, a mechanism of tin deposition on a steel substrate is suggested. Initially, 3D tin crystallites are formed preferentially on step edges, and this is followed by fast covering of neighboring sites with much smaller and densely packed crystallites of about 150-180 nm in size. Without gelatin, the coverage was poor and tri-modal structures were dominating. It is discovered that the synergy between hydrogen co-evolution and gelatin contributes to fast and complete coverage of the steel substrate and the bi-modal grain size distribution is observed. The diffusion coefficient of tin ion was determined according to the Sand equation.     

甲基磺酸亚锡与硫酸亚锡镀哑光锡的比较

从实验验证、成本分析两个方面对甲基磺酸亚锡和硫酸亚锡为主盐的镀哑光锡电解液在镀液性能和镀层性能进行比较,验证了甲基磺酸亚锡镀哑光锡在镀层和镀液方面的性能优势,在成本上,对甲基磺酸亚锡镀哑光锡和硫酸亚锡镀哑光锡做对比分析,发现二者成本接近,综合研究结论认为:甲基磺酸亚锡为主盐镀哑光锡在未来几年内,有取代硫酸亚锡的趋势。     

Comparison of platinum with IrO2–Ta2O5 system for the stannous ion consumption in methane sulfonic acid baths with and without catechol

The stannous ion consumption in methane sulfonic acid (MSA) baths with and without catechol was quantitatively evaluated using platinum and IrO₂–Ta₂O₅/Ti anodes. The stannous ion is consumed at the same rate with both anodes, accompanied by the generation of tin sludge on the anode surfaces in the bath without catechol, while these undesirable phenomena are significantly suppressed in the bath containing catechol. Spectroscopic measurements indicate that stannous ion and catechol form a complex at the mole ratio of 1:2, thus preventing the oxidation of stannous ions. This complexation effect is independent of the anode material at low current density, but depends on the anode material at high current density. The stannous ion consumption at high current density is sufficiently inhibited only with the IrO₂–Ta₂O₅/Ti anode due to the low oxygen evolution potential. Voltammetric measurements also suggest that the continuous oxidation of stannous ion in the catechol-containing bath is simultaneous with oxygen evolution.     

印制线路板中化学镀锡研究现状与发展

综述了PC B化学镀锡的发展现状及历史。介绍了现阶段化学镀锡工艺的优点及硫酸盐体系与烷基磺酸盐体系2种化学镀锡液的组成。分别介绍了主盐、硫脲、络合剂、还原剂及其它添加剂的作用。对化学镀锡的机理做了探讨。提出了比较合理的改进化学镀锡液的方案,尤其是在提高镀速和改善镀厚性等方面。同时提出了防止镀锡层表面变色和锡须生成的一些有效方法。     

电子电镀添加剂的分子设计

提出了电镀添加剂设计的概念,给出了锡基电子电镀添加剂设计的基本方法。由于电镀添加剂作用的复杂性,要得到性能优异的添加剂,必须从分子水平上对添加剂进行设计,而添加剂在镀层中的夹杂是通过化学夹杂和物理夹杂引起,从分子水平上设计的低吸附型镀锡添加剂可以减少有机分子的夹杂。     

Effect of brighteners on hydrogen evolution during zinc electroplating from zincate electrolytes

Hydrogen evolution during zinc electrodeposition on a steel substrate from zincate electrolytes containing different additives was studied using various experimental techniques.The hydrogen evolution reaction is limited by the electron transfer step. Hydrogen evolution is most intensive during the first seconds from the beginning of electrodeposition due to the lower overpotential of hydrogen on steel as compared with that on zinc. The evolved hydrogen is dissipated in three ways. Most is dissipated to the atmosphere via gas bubbles at a constant rate. Some is dispersed in the electrolyte some diffuses into the steel substrate, predominantly at the commencement of deposition. The additives affect both the total amount of evolved hydrogen and its distribution. The highest amount of hydrogen is evolved in the presence of the anisaldehyde bisulphite containing composite additive. The highest amount of hydrogen included in the substrate and remaining in the electrolyte corresponds to the use of the Na–N-benzylnicotinate containing additive. In this case blistering is observed.     

Leaching behaviour of tin with oxygen in recycled phenolsulfonic acid tin plating solutions

The dissolution characteristics of metallic tin with oxygen in recycled phenolsulfonic acid (PSA) tin plating bath to compensate tin consumed during the previous plating operation were investigated using electrochemical methods and leaching experiments at 30 °C. Electrochemical polarization data indicate that the diffusion of dissolved oxygen is the rate determining step and this is confirmed by leaching experiments. The sludge formed due to further oxidation of stannous ions during leaching in PSA tin plating solutions contains approximately 40 wt % Sn.     

Electrochemical study of the activating solution for electroless plating of polymers

This paper presents an electrochemical study about the activating solutions of the electroless plating of polymers, containing Pd(II), Sn(II) and Sn(IV) mixtures in HCl as main components. The objective of the study is the voltammetric characterization of these solutions by cyclic and linear voltammetry in order to study the recovery of tin and palladium from these solutions. The effect of concentration and rotation rate on the current−potential curves was studied using the RDE technique. The electrochemical behaviour of solutions prepared in the laboratory was performed as a prior step to the further study of real activating rinsing solutions. The electrochemical reduction of Pd(II) takes place in two one-electron transfer steps which are mass transport controlled. The electrochemical reduction of Sn(II) and Sn(IV) is also mass transport controlled and takes place with direct formation of metallic tin, although the electrochemical reduction of Sn(IV) only takes place in solutions with HCl concentrations higher than 1 M. The presence of additives in the real solutions prevent the chemical reduction of Pd(II) and the formation of Sn(IV) hydroxylated complexes. This causes the appearance of well defined diffusion waves attributable to the electrochemical reduction of Pd(II) and Sn(IV). Hence, the recovery of both species simultaneously as well as separately could be carried out, if appropriate conditions are selected.