Electroplating Process Research Articles

High thermal conductive Cu-diamond composite sheets reinforced with single-layer diamond prepared by a three-step electroplating process

High thermal conductive Cu-diamond composite sheets reinforced with single-layer diamond prepared by a three-step electroplating process

Chiral Metal Coating to Enhance Water Electrolysis.

Producing hydrogen through water splitting often faces challenges of overpotential, stability, and expensive catalysts, which limit its efficiency and hinder the advancement of hydrogen production technologies. Nickel foam and nickel meshes have emerged as promising materials for electrolyzer electrodes due to their high surface area and the ability to produce electrolyzers with a very small gap between the anode and cathode. This study presents a simple method for coating Ni-based electrodes with a chiral Ni-Au film, using electroplating, thus enhancing its efficiency dramatically. We introduce chirality to the electroplating layer by incorporating an enantiopure chiral reagent into the electroplating solution. The chiral layer enhances the oxygen evolution reaction due to the chiral-induced spin selectivity effect. By optimizing the chiral electroplating process, we demonstrate the reduction of the overpotential and an increase in the reaction efficiency by 95% at 1 M KOH at room temperature.

Copper Metallization of Nano-through Silicon Vias for Backside Power Delivery Networks

I. Introduction Backside power delivery networks (BS-PDNs) represents an exciting technological concept that has been steadily advancing over the past few years, particularly in the integration of leading-edge nodes. With BS-PDN approaches, the entire power network is migrated to the backside of the wafer, eliminating interference, and allowing more area for signal routing on the frontside. In addition, the route for power delivery to transistor is shorter and more direct, resulting in reduction by 30% in IR drop1.Nano-Through Silicon Vias (n-TSVs) is one of the key enabling processes for BS-PDN integration1-4. The application of n-TSVs enhances the interconnect packing density, potentially increase the efficiency of power delivery up to 7 times compared to frontside power delivery, based on the simulation studies conducted by Arm and Imec5. The scaling down of TSV diameter to 200 nm brings challenges in fabrication process steps such as wafer thinning and metallization. To maintain the aspect ratio between 3 and 5 for reliable n-TSVs etch and filling processes, Si substrate must be thinned down to below 1µm6. Cu is one of the options for the filling of n-TSVs. However, significant challenges exist in Cu metallization of high aspect ratio n-TSVs (diameter <200 nm, aspect ratio 3-5). These include poor Cu seed sidewall coverage and overhang at via entrance with conventional physical vapor deposition (PVD) setups, as well as fill voids during electroplating (ECP) in structures with aspect ratio >3 due to limited additive diffusion into the nano features. In this paper, we will co-optimize PVD and ECP processes to achieve robust void-free Cu metallization of n-TSVs. II. Experimental 250x760 nm n-TSVs with pattern density approximately 1% were fabricated on 300mm silicon wafers. Immersion lithography was employed for pattern definition, followed by plasma dry etching on 760nm oxide/silicon/oxide stack, to mimic typical n-TSVs film structure. Subsequently, Al2O3 passivating dielectric and Ta barrier/Cu seed deposition by atomic layer deposition (ALD) and PVD, respectively. To enhance the Cu seed coverage, bias conditions during PVD process were investigated.Copper electroplating was conducted in AMAT-Nokota platform using a commercially available acidic copper electrolyte. To gain insights into copper filling mechanism of n-TSVs, ECP process was conducted at different conditions with varying current densities, agitation, and pulse current waveforms. The n-TSVs copper filling was characterized using cross-sectional focused ion beam transmission electron microscopy (FIB-TEM). III. Results Fig. 1 shows a cross-sectional TEM image illustrating n-TSVs filling under baseline condition. There are systematic voids at the center, throughout the top-half of the n-TSVs. These seam voids might be due to the poor diffusion of additives to nano scale features, leading to sub-conformal plating configuration, resulting in pinch off voids near the top of n-TSVs. To facilitate the diffusion and adsorption of appropriate additives towards n-TSVs, periodic pulse current waveforms are applied. Besides the enhancement of additive diffusion during pulse off-time, high peak current pulsing results in higher overpotential deposition which promotes copper nucleation. In addition, the average current density is reduced by 20% to allow sufficient replenishment of copper ions inside the n-TSVs.Apart from the center voids at the top region of the vias, there are voids along the sidewalls around the Si layer due to poor Cu seed coverage. To improve the Cu seed coverage, the wafer bias during PVD process is modulated. The increase in bias condition is beneficial not only for the continuous Cu seed at sidewalls, but also to reduce overhang at the top of the vias. With the approach of high bias PVD, via opening CD is larger, allowing better additive and copper ion diffusion during electroplating.Fig. 2 shows a cross-sectional TEM image representing n-TSVs filling under optimized condition. Void-free filling is achieved with the co-optimization of PVD and ECP processes. The details will be discussed in the full paper. IV. Novelty This work demonstrates a robust void-free Cu metallization for n-TSVs which is important for the integration and fabrication of backside power delivery networks. V. References Hafez et al., 2023 IEEE Symposium on VLSI Technology and Circuits, p. 1-2 (2023).Veloso et al., 2021 Symposium on VLSI Technology, p. 1-2 (2021).Veloso et al., IEEE Transactions on Electron Devices, 69, p. 7173–7179, (2022).Anne Jourdain et al., IEEE Electronic Components and Technology Conf., p. 1531-1538 (2022).Cline, D. Presaderic, E. Beyne, O. Zografos, “Next-Gen Chips Will Be Powered from Below,” IEEE Spectrum, (2021).Anne Jourdain et al., Proc. IEEE Electronic Components and Technology Conf., p. 42-48 (2020). Figure 1

(Invited) Development of Novel Coatings on Stainless Steel based Bipolar Plates for Proton Exchange Membrane (PEM) Water Electrolyzer Application

Hydrogen is one of the most efficient energy carriers and can be produced by different methods. Among all the production methods, the proton exchange membrane water electrolyzer (PEMWE) is considered as the most promising technique to produce highly pure hydrogen from renewable energy sources with pure oxygen as by-products with no carbon emissions. The PEMWE technology has reached the early stages of commercial deployment while the mass production is tied to cost reduction. A PEMWE single cell comprises a membrane electrode assembly which considered as a core component where the electrochemical reactions take places in three phase boundaries. It also includes a titanium based porous transport layer (PTL) in anode side and carbon-based gas diffusion layer (GDL) in cathode side for the transportation of water and gas into and out of the cell. Additionally, bipolar plates (BPPs) with grooves provide mechanical support for the cell and distribute the water inside the cell and remove generated gases to the outlet trough flow field distribution channels. PTLs and BPPs, which are metallic components, are designed to endure the corrosive conditions present in the electrolyzer and they both needs protective coatings to stand at high voltage (<2 V), acidic media, temperature (60–80 °C) and oxygen saturated environment (anode).In this research, a modified electroplating process is used to deposit gold thin film as a protective film on both stainless steel (SS) and titanium based BPPs and PTLs, respectively. The electroplating of gold is a mature technology and easy to implement for large scale coating. This process will be impacted by many factors, such as the ingredient of plating solution, arrangement of electrodes, current distribution, and operating parameters. In addition, pre-treating the surface plays an important role to develop the durable thin films with proper adhesion. The gold striking underlayer on the SS substrate passivated the surface oxides and facilitated a dense electroplated chromium layer. Furthermore, a uniform gold protective layer was electroplated on the chromium coated substrate to achieve a promising anti-corrosive property. To evaluate the impact of pre-treatment and the anti-corrosion properties of the developed coating, different physical and electrochemical characterization techniques are conducted. As a result, The Au/Cr/Au coating on the SS substrate showed corrosion current density of 0.84 µA/cm2 and lower degradation as compared to without gold striking underlayer.The surface morphology and the crystallinity and phase analysis are investigated by scanning electron microscopy and X-ray diffraction (XRD), respectively. X-ray photoelectron spectroscopy (XPS) is used to study the surface properties and the bonds between the elements. The contact resistance also is studied under different pressures. In addition, traditional lab-scale durability analysis, using stagnant liquid electrolyte and three-electrode cell setups, might not provide such a precise information for PEM water electrolyzer. The three-electrode setup does not include crucial parameters relating to real cell-operating conditions or contributions to the PTL by other key cell components such as the membrane, catalyst layer, ionomer, and bipolar plates. Flow electrochemical setup is developed in our lab and is used to run the accelerate stress test to check the durability of the coated samples. Potentiodynamic, chronoamperometry and impedance also used to evaluate the samples. Figure 1. (a) Schematic of gold electroplating on the SS substrate, (b) SEM image and EDX analysis of Au/Cr/Au coating.We would like to acknowledge the support of the Natural Sciences and Engineering Research Council of Canada, Canada Research Chair and Mitacs Accelerate program and Intlvac Thin Film for their constant support. Figure 1

High Efficiency Electroplating (220)-Orientation Nano-Twinned Copper in Methanesulfonic Acid System and Mechanism Analysis

Nano-twinned copper, distinguished by intricately arranged twin boundaries within each grain, manifests superior mechanical properties compared to commercial copper foil. The cohesive twin structure effectively impedes dislocation motion through intricate interactions between twin boundaries and slip bands. Consequently, copper endowed with a twinned structure achieves an ultrahigh tensile strength of approximately 1 GPa, surpassing the performance of coarse-grained polycrystalline copper, which attains only around 200 MPa under equivalent testing conditions. Furthermore, the resistivity of coherent twin boundaries is approximately half that of stacking faults and grain boundaries. This characteristic allows twinned copper to attain heightened tensile strength without significant compromises in conductivity. In the context of resistance to electromigration, the twinned structure significantly hampers copper's atomic diffusion by an order of magnitude at the triple points where twin and grain boundaries intersect, compared to commercial copper. Moreover, in certain instances, nano-twinned copper demonstrates exceptional thermal stability, maintaining elevated hardness levels even subsequent to annealing at 800 °C, in contrast to nanocrystalline copper. In a distinct scenario, annealing at 250 °C for a duration of 3 hours results in only a marginal reduction in tensile strength, stabilizing at approximately 700 MPa.Given the exemplary performance demonstrated by nano-twinned structures, the imperative is to devise efficient methodologies for the production of high-density nano-twinned copper films. High-speed electroplating emerges as a viable approach to achieve this objective, attributed to its one-step process and facile control.Mainly because the high current density induces the higher copper nucleation rate, making interfacial energy larger, so that copper films would easier to proceed twin formation reaction to lower the residual stress. Numerous scholarly works underscore the application of high-speed electroplating in producing nano-twinned copper films, particularly through the pulse electrodeposition mode. This mode, characterized by a clear nucleation mechanism and well-defined performance metrics, facilitates the systematic creation of nano-twinned structures. However, the incorporation of a pulse-off period resulted in a reduction of the average current density, which was suboptimal from an efficiency standpoint. Consequently, specific scholarly works explore the electroplating of a twin-crystal structure through DC electroplating, aiming for enhanced efficiency with higher average current density. Presently, the literature reports instances of achieving elevated current densities, reaching up to 40 ASD, to produce nano-twinned copper with a (111) orientation and an average twin spacing of approximately 100 nm. Nevertheless, the solubility of cupric ions serves as a limiting factor for the overall electroplating reaction rate efficiency. Consequently, an inherent upper limit to efficiency exists within the copper sulfate system, posing a challenging constraint to ameliorate through adjustments to temperature or additives.However, existing literature indicates that the cupric ions' solubility in copper sulfate is 1.35 M, while copper methanesulfonate demonstrates an impressive solubility of up to 2 M, as confirmed through vacuum filtration. The heightened ion solubility provides the opportunity to increase current density without inducing deleterious powdery deposition issues, thereby maintaining a uniformly conductive surface. Also, the higher current density would conduct better twin formation condition. Thus, the metal methanesulfonate solution, constituting an organic acid system designed to enhance the solubility of metal ions, involves the substitution of metal sulfate with metal methanesulfonate and the replacement of sulfuric acid with methanesulfonic acid, can be considered as a feasible optimization for efficiency issue and twin formation.In the copper sulfonate system, the induction of a nano-twinned structure involves adding organic additives to form an ionic complex with Cu+ in remediation and chloride ions, subsequently altering the deposition route and nucleating copper crystals through a stress relaxation process. Conversely, in the copper methanesulfonate system, chloride ions exhibit an antagonistic effect with organic additives. Moreover, the use of organic additives is associated with potential challenges related to aging, chain scission and cracking issues, potentially transforming the system into a batch manufacturing paradigm. Therefore, investigating the possibility of directly improving the electrochemical mechanism on the negative surface through chloride ions in this organic system to plate nano-twin crystals is a question worth exploring in order to create a sustainable electroplating process for commercial nano-twinned copper manufacture.Here presents a novel approach to the production of (220) orientation nano-twinned copper films, achieved through the incorporation of chloride ions as additives in a high-concentration methanesulfonate copper solution. The primary objective is to leverage chloride ions for the induction of numerous twin boundaries on the copper surface, enabling meticulous control of the average twin spacing at the nanoscale.The investigation herein provides a comprehensive analysis of the nuanced role played by chloride ion distribution in the formation of nano-twinned copper. Figure 1

Understanding the Role of the Black Anodic Film in Copper Electrodeposition in Sulfuric Acid Medium: Organic Additives Free Electrolytes

In the process of copper electroplating from a sulfuric acid bath it is well known that the copper anodes must contain a small quantity of phosphorous (CuP) (0.04 to 0.06 %). In the other hand, the electrolyte must contain a small amount of chloride ions (50 to 100 mg/L). The result is the formation on an anodic black film. The latter is essential in the proper functioning of the copper electroplating process. The presence of this black film prevents the formation of anodic sludge which compromises the quality of the copper deposits. The anodic behavior of copper is of great interest not only from the theoretical point of view but also as an important practical problem. The anodic sludge is formed by one of the following mechanisms [1], [2], Eq. (1) which is the disproportionation reaction of the cuprous ions, mechanism 1:2 Cu+ ↔ Cu2+ + Cu (1)Eq. (1) is responsible for the formation of anodic sludges. The mechanism 2 is the preferential dissolution along the intergrain boundaries and the consequent detachment of complete crystal grains from the crystalline structure. The addition of phosphorus as an alloying element during the manufacture of the anodes and the presence of chloride ions in the plating bath result in the formation of the anodic black film which eliminates the possibility of copper anode grains detachment and the alteration of the anodic dissolution mechanism. Copper anode dissolution proceeds under a two steps mechanism described by Eq. (2) and (3):Cu ↔ Cu+ + e- (2)Cu+ -> Cu2+ + e- (3)Both of these reactions take place in the anodic film. In order to move from a bath with additives to a bath without additives, it is essential to answer the following questions: What is the effect of organic additives on the anodic side? What is the optimal concentration range for chloride ions? What is the influence of the grain size of Copper-Phosphorus anodes?The present work deals with a extended characterization of the black anodic film and relevant insights about its formation mechanisms.[1] : ST. RASHKOV and L. VUCHKOV, The Kinetics and Mechanism of The Anodic Dissolution of Phosphorus-Containing Copper in Bright Copper Plating Electrolytes, Surface Technology, 14 (1981) 309 – 321.[2] : G. S. Frankel, A. G. Schrott, H. S. lsaacs, J. Horkans, and P. C. Andricacos, Behavior of CuP and OFHC Cu Anodes under EIectrodeposition Conditions, United States. Department of Energy, Brookhaven National Lab., Upton, NY (United States), 1992. Figure 1

Laser Direct Structuring of Millable BN‐AlN Ceramic for Three‐Dimensional (3D) Components

This research introduces a novel process for the direct metallization of the composite ceramic BN‐AlN, a millable, high‐temperature resistant material, using laser direct structuring (LDS). LDS is, for example, used for molded interconnect devices (MIDs), to integrate mechanical and electronic functions into a single 3D structure. Traditionally, MIDs have relied on polymers, but increasing thermal demands in electronics are shifting focus toward ceramic substrates like BN‐AlN, which offer superior thermal stability and mechanical strength. Herein, electronic infrastructures are applied onto milled BN‐AlN 3D components through a parameter study on laser activation and electroless copper deposition, followed by the development of a sequential copper–nickel–gold (CuNiAu) deposition process. The laser structuring reveals small grains of elemental aluminum on the surface, which directly catalyzes metal reduction in the electroless copper deposition. The duration and temperature of the copper electroplating process are found to influence the nuclei size and layer thickness. A palladium chloride treatment, as well as additional etching steps during the CuNiAu layer deposition, shows promising results. The metallized BN‐AlN substrates are characterized for adhesion, contact reliability, resistivity, and thermal stability. The findings demonstrate the process's suitability for high‐temperature applications, highlighting its potential for advancing electronic system integration.

A comparative study on the erosion behavior and mechanism of chrome-coated 25Cr3Mo2WNiV steel and QPQ 25Cr3Mo2WNiV steel

Chromium electroplating and QPQ (quench-polish-quench) process are widely used methods for gun steel surface treatment. This study aims to compare the erosion behavior and mechanism of chrome-coated 25Cr3Mo2WNiV steel (Cr MPS700V) and QPQ MPS700V using promoted ignition combustion tests. By studying erosion behavior, it was found that the erosion threshold pressure and temperature of the Cr MPS700V were determined to be 0.52 MPa and 277 K higher than those of QPQ MPS700V. The surface morphology after erosion shows that the equivalent erosion depth of QPQ MPS700V is 8.2 μm deeper than that of Cr MPS700V. The superior resistance to erosion of the Cr MPS700V was ascribed to the inhibition of the Kirkendall effect at the interface between the coating and matrix. Small-sized atoms C and N in the QPQ coating were more easily diffused into matrix than large-sized atom Cr before erosion. Moreover, the oxidation heat release of Mo2C precipitated at the QPQ coating/steel interface is higher than that of Cr23C6 precipitated at the Cr coating/steel interface, which reduced the erosion performance of QPQ MPS700V.

Characterization of Ni-Cu multilayers deposition on low carbon steel substrate using electroplating technique

Abstract Low carbon steel is widely used in oil and gas applications. In this research, multilayers of Nickel (Ni) and Copper (Cu) were deposited on a low carbon steel substrate using the electroplating process (ELP). Initially, a layer of Ni was coated, followed by a layer of Cu. ELP was implemented using water bath containing (300 g/l) of NiSO4.6H2O, (30 g/l) of (NiCl2.6H2O), (40 g/l) of H3BO3 and (30 g/l) of (NaCN), (30 g/l) of (CuCN), (10 g/l) of (NaOH.6H2O). First bath parameters were temperature is (59 - 60 °C), current density in the range of (3-5 A/dcm2), voltage was holed at (8 V) for Ni, and temperature was between (50-51 °C), current density in the range of (1-2 A/dcm2), voltage was holed at (4 V), while the plating time (10 minutes) for both Ni and Cu. The results refer to Ni, Cu, and Ni &amp; Cu ELP thicknesses 3, 4.77 and 6.75 μm respectively. Metallurgical tests were achieve including the micro hardness of ELP, Vickers micro hardness results showed improvement in hardness values compared, with steel substrate, and in the presence of Ni, Cu, Ni+Cu layers, 322, 581, 479, and 562 Hv respectively. The roughness was measured using surface roughness measurement device. The average surface roughness (Ra) depicted satisfying values as a result of Ni layer coating, which gave uniform surface distribution with Ra 0.363 μm. X-ray diffraction (XRD) test examinations serve as strong evidence for the presence of Ni and Cu in the internal and external finish layers, respectively. Corrosion examinations were carried out in seawater solution (3.5 g NaCl) the corrosion behavior tends to be more resistance, with layers of Ni, and Cu in sea water environment, which is considered an important criterion to increase the part life.

Temperature Effects in Packaged RF MEMS Switches with Optimized Gold Electroplating Process.

Due to its excellent electrical performance, mechanical reliability, and thermal stability, electroplated gold is still the most commonly used material for movable beams in RF MEMS switches. This paper investigates the influence of process conditions on the quality and growth rate of gold electroplating, and the optimized process parameters for the gold electroplating process are obtained. The characterization of the optimized electroplated gold layer shows that it has small surface roughness and excellent thermal stability. With this optimized gold electroplating process, the RF MEMS switches are fabricated and hermetic packaged. In order to obtain the temperature environment adaptability of the packaged switch, the influence of working temperature is studied. The temperature effects on mechanical performance (includes pull-in voltage and lifetime) and RF performance (includes insertion loss and isolation) are revealed.

Electroless silver plating on through-glass via (TGV) as an adhesive and conducting layer

The proposed method presents a scheme to modify the surface of the glass substrate using the piranha solution and to fabricate the conducting layer of the Through-glass Via (TGV) by the glucose-Ag electroless plating to achieve TGV metallization. The arithmetic mean deviation of the surface contours (Ra) for the substrates increases from 0.001 to 0.135. The contact angle of the substrates (unmodified and modified) is reduced to 6.4° and 12.2°, respectively. The sensitization process with SnCl2 and the activation process with silver ammonia solution are conducted using the glucose as the reducing agent to prepare the silver seed layer covered in the TGV through-vias with a high aspect ratio (9:1). The adhesion between the metal coating and the surface is measured by the 3M tape and chemical mechanical polishing (CMP). The metal coating adheres well to the surface-modified substrate without peeling off, which can satisfy the demands for the electroplating and CMP processes.

Effect of the Saccharin Concentration on Electrodeposition of the Fe-Ni Alloy

The FMM (Fine Metal Mask) used in the OLED display manufacturing process is a metal sheet with holes formed to allow the deposition of diode material only in the sub-pixel area. To prevent deformation and misalignment of the FMM (Fine Metal Mask) caused by heat during the RGB organic deposition process, an Invar plate with a thermal expansion coefficient (CTE) close to 0 is used. The Invar sheet applied to the current FMM is manufactured through a metallurgical process, and its final thickness after rolling is 20 micron. However, due to limitations in reducing thickness with the rolling process, for manufacturing FMM with a thickness of under 10 micron for next-generation high-resolution (UHD-level) displays, the bottom-up electroplating process is suitable. However, to maintain the shape of the electroplated Invar sheet while ensuring commercial-grade low CTE, heat treatment at temperatures exceeding 600℃ for an extended period is required, utilizing thermo-mechanical processing methods. If uniformity in the microstructure composed of nano-grains is ensured in the electroplated Invar alloy in the As-deposited, it is possible to increase the efficiency of the process by reducing the heat-treatment processing cost.Therefore, in this study, we investigated the microstructural evolution in the Invar alloy by controlling the surface stress of the electroplated layer during pre-plating. We controlled the key additive, saccharin, in the Fe-Ni alloy electrolyte to assist the diffusion of iron and nickel ions. By examining the relation between microstructural uniformity, determined by the plated layer, and CTE, we propose optimized process conditions for the pre-plated Invar sheet.

Analysis of Opaque, Peel-Off and Flex Rejects in the Electro Plating Process Using the Six Sigma Dmaic Method

The modern manufacturing industry is faced with increasing pressure to achieve high levels of quality while remaining efficient in its production processes. One of the challenges faced by PT. Plating services in electroplating production have a high reject rate, which can cause increased costs and have a negative impact on the company's reputation. PT. Jasa Plating in the production process still has a high number of rejects, the rejects are dominated by opaque, peel-off and spots. PT. Plating services for each production contribute a high average of 2% defects per day, DPMO 20,000 and Sigma value 3.55. Quite a few rejections resulted in a decrease in turnover and increased production costs. The costs incurred due to these rejects are an average of Rp. 1,268,593 per day and an average of Rp. 35,698,907 per month as a result of data collection from January – September 2023. In this business process, this is very detrimental for the company. The aim of this research is to suppress blurry rejects, peel-offs and spots in the electro plating process at PT. Plating Services. The steps taken in conducting research include: identification stage, data collection and processing, analysis and recommendations for improvement, and conclusions. The method used in this research is the Six Sigma DMAIC (Define, Measure, Analysis, Improvement, Control) method. Through analysis, you can find several factors that cause high reject rates, including operational errors, discrepancies in the production process, or raw material quality problems. After implementing the improvement plan, then evaluate the results. This can include re- measuring the DPMO, analysis of the resulting products to see a decrease in reject rates, and comparisons between before and after implementing improvements. From the comparison results after the repairs were carried out, the data before the repairs were carried out, the NG amount was 1.99%, the DPMO was 6,646 and the Sigma value was 3.98. After improvements to NG 0.84%, DPMO 2,791 sigma value 4.28. Factors causing high levels of blurring, peel-off and spots, namely insufficient or excessive cleaning of the metal surface before the electroplating process, can cause problems such as peel-off. Contamination of the electroplating solution by foreign materials can cause blurring and flecks in the final layer. Machinery or equipment that is not properly calibrated, or experiences wear and tear, can produce products that do not meet standards. Variations in temperature, time, or electric current in the electroplating process can produce inconsistent coatings. Carefully monitor and control process-parameters to ensure stability.

Studies on the quantitative analysis of an electrochemical solution via the Schlieren method

A quantitative schlieren technique has been applied to measure the change of copper sulfate concentration in an electrochemical cell during the copper electroplating process. We constructed a mathematical model that correlates the grayscale values of schlieren images with the concentration of copper sulfate and analyzed the impact of refraction, reflection, and absorption of light during its passage through the solution on the precision of a schlieren quantitative analysis. Ultimately, by examining the temporal and spatial changes in the distribution of the copper sulfate concentration, we ascertained the impacts of convection, diffusion, and electromigration on the concentration distribution. The impact of the current studies would be greatly expanded in important electrochemical practices such as renewable energy conversions and rechargeable batteries.

Effect of complexing agent on iron base zinc-nickel alloy coating

The influence of four complexing agents on corrosion resistance of Zinc-Nickel (Zn-Ni) alloy coating was investigated. The current density and plating time were determined by Hull and rectangular tank experiments. The effects of triethanolamine, potassium sodium tartrate, tetraethylenepentamine and sodium citrate on the properties of iron-based Zn-Ni alloy coatings were studied under the same electroplating process. The surface morphology, structure, elemental composition and corrosion resistance of Fe-base Zn-Ni alloy coatings with different complexing agents were analyzed. The surface and morphology of the coating were analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The anticorrosive properties of the coating were evaluated by electrochemical electrode and electrochemical impedance spectroscopy (EIS). The self-corrosion current density of triethanolamine is 2.927e-005A·cm−2, the rate of corrosion is minimal, rendering the material highly resistant to corrosion; the surface remains flat and exhibits a dense texture. The content of potassium, sodium, Zn and Ni in tartrate increased, thus reducing the corrosion resistance and flatness of the coating. The self-corrosion current density was 9.400e-005A·cm−2. The surface was rough and uneven, and there were a large number of large concave and convex defects. The complexing agent enhances the adhesion and corrosion resistance of the coating, improves the optical and mechanical properties of the coating, adjusts the durability and stability of the coating, increases the crystal packing density, increases the coating thickness, improves the adhesion with the substrate interface, and optimizes the uniformity of grain distribution. These factors are the key factors that determine the corrosion behavior of Zn-Ni coatings. In the process of electroplating, the addition of complexing agent can improve the quality of the coating, and suitable complexing agent can obtain smooth and bright coating at the same time, make the corrosion resistance of the coating higher.

Electroplating Additively Manufactured Honeycomb Structures to Increase Energy Absorption Under Quasi-Static Crush

Honeycomb (HC) has been used in energy absorption applications due to its high stiffness and low density. Metallic HC are used for energy absorption applications, however, these metallic structures can be challenging to manufacture if complex geometric features designed to improve energy absorption are used, which motivates the use of additive manufacturing (AM). Metal AM methods include powder bed fusion (PBF) and direct energy deposition (DED). In addition to capital equipment cost, these processes possess challenges that include a required inert environment, powder handling, final part porosity, residual stresses, and nonuniform surface finish. These concerns can be alleviated through the use of polymer AM, however, polymeric parts exhibit brittle failure and have a lower stiffness than metallic HC structures. In this study, a low-cost 3D polymer printing method, stereolithography (SLA), is combined with a conventional electroplating process to fabricate a metal-plastic composite HC structure with energy absorption capability much greater than of a plastic HC structures of the same nominal volume. SLA parts have a smooth surface, so that the surface finish is at least as uniform after electroplating as the SLA part. The energy absorption characteristics of the electroplated HC is studied to determine how these energy absorbing materials can be manufactured at reduced cost. Our study confirms that the metal-plastic composite HC increases both the crush strain range and the mean crush stress of these samples, resulting in metal-plastic composite HC structures with substantially increased energy absorption. This study also examines how buckling initiators (BIs), or diamond shaped holes located at 50, 75, and 100% of the height of the hexagonal cell vertices, can influence energy absorption performance. This study shows that it is feasible to fabricate electroplated HCs, using an SLA preform, to achieve a substantial increase in energy absorption over using SLA alone.

Through glass via (TGV) copper metallization and its microstructure modification

The microstructure and uniformity of Cu metallization in the through glass via (TGV) structure were investigated through electron backscatter diffraction (EBSD) analysis system and finite element analysis (FEA) method. Two different direct current (DC) electroplating methods were employed for the TGV metallization, including single- and multiple-step electroplating methods. We found that the multiple-step electroplating process with appropriate current density (j)/plating time (t) can efficiently enhance the throwing power (TP) value (uniformity) of electroplated Cu in the TGV metallization. Moreover, the Cu electrodeposition via the multiple-step electroplating process possessed larger grain sizes and high fraction of high angle grain boundaries (HAGBs), including twin boundaries (TBs), which are very beneficial to the mechanical and electrical properties of Cu interconnects. Detailed analyses of the uniformity (i.e., TP), crystallographic microstructure (e.g., grain size), and mechanical characteristics (e.g., ductility) of electroplated Cu derived from single- and multiple-step electroplating process were discussed in this paper.

A Novel Model for Copper Electroplating Process Simulation Minimizing Chemical Additives

A Novel Model for Copper Electroplating Process Simulation Minimizing Chemical Additives

Ti-coated diamond micro-powder for the manufacture of the electroplated diamond wire saw

The electroplated diamond wire saw has been widely used in the production of semiconductors, photovoltaic devices, etc. Composite electroplating is an important process in the production of electroplated diamond wire saws. The utilization of nickel (Ni)-coated diamonds is a widely adopted approach to enhance the efficiency of the composite electroplating process employed in the manufacturing of wire saws. However, the pristine diamond does not chemically react with Ni, and the interfacial bonding strength between the Ni coating and the diamond is relatively weak. This frequently results in the detachment of diamonds from the Ni coating during the cutting process. To solve this problem, titanium (Ti)-coated diamonds were used in the preparation of wire saws. We had specially developed a vacuum slow evaporation technology to produce diamond micro-powder (8 μm) with uniform conductive Ti coatings that were firmly bonded with diamond through the interfacial product TiC. A series of electrochemical test results were used to demonstrate the effect of Ti coating on the composite electroplating process. The linear scanning voltammetry curves showed that the addition of Ti-coated diamond shifted the overpotential of composite electroplating in a positive direction, so it promoted the electrodeposition reaction more than diamond powder. The electrochemical impedance spectroscopy revealed that the conductive Ti-coated diamond reduced the charge transfer resistance during composite electroplating. The Ti-coated diamond micro-powder was completely enveloped by an electroplated Ni layer, and TiC formed between the Ti coating and the diamond provided a stronger interfacial bonding force compared to that of the Ni-coated diamond micro-powder. After cutting, the Ti-coated diamond was found not to fall off the wire saw. The use of Ti-coated diamond micro-powder as an abrasive will significantly improve the product quality of mass-produced electroplating diamond wire saws.

Quantifying thiolated chemical additives for copper electroplating process

BackgroundCopper foil, a thin layer of high-purity metallic copper, having excellent conductivity, ductility, and corrosion resistance, is extensively applied in various electronic applications. Thiolated (SH-containing) chemical additives (i.e., accelerator and inhibitor) in copper electroplating solution are known to be critical for optimizing the copper foil manufacturing processes. Due to the high ionic strength and acidity of copper electroplating solution, proper and accurate characterization of the thiolated chemical additives is a critical concern. ResultsIn this study, a facile, accurate approach is developed for quantitative characterization of thiolated additives in the copper electroplating solution. Firstly, gold nanoparticles (AuNPs) were employed as an adsorbent for separating the thiolated chemical additives, namely, poly(ethylene glycol) methyl ether thiol (PEG-SH) as inhibitor, and 3-mercaptopropionic acid (MPA) as accelerator from other interfering chemicals present in the copper electroplating solution. Subsequently, quantitative analysis of the AuNPs in the form of thin particle film was performed using attenuated total reflection-Fourier transform infrared spectroscopy. Electrospray-differential mobility analyzer was employed orthogonally for the quantitative analysis of the amount of thiolated additives adsorbed on AuNP. Interestingly, the results indicated that the detection concentration ranges of 5 μM–100 μM for PEG-SH and 10 μM–200 μM for MPA, respectively. SignificanceOverall, this work demonstrates a successful separation and analysis methodology for the thiolated chemical additives in copper electroplating solution which enables the precise control over the copper foil manufacturing process.