Copper Sulfate Plating Research Articles

硫酸銅めっき厚膜における残留応力の増加要因とその抑制

This study investigated the effect of current density and concentration of bis(3-sulfopropyl)disulfidedisodium(SPS)upon the residual stress of copper sulfate plating. The residual stress increased because of increasing lattice strain with current density. Moreover, the lattice strain increased with hydrogen entrapped in the grain boundary of Cu films. Results clarified that residual stress was suppressed concomitantly with increased SPS concentration. During self-annealing of small grains, the residual stress is reduced by electrodeposition of a high concentration of SPS.

Anodic Oxidation of SPS Resulting in PDS Formation and the Influence of PDS on Electrolytic Copper Via Filling Performance

Electrolytic copper via filling based on three additive component copper sulfate bath chemistry has been and currently is widely used in electronic packaging. Progression in copper sulfate plating chemistry continues to promote device densification, which is vital to development of smart phones among other devices. Bath maintenance is an important aspect of ensuring filling performance, where in addition to additive concentration, additive decomposition product concentrations also require management. In order to further elucidate bath chemistry and possibly methods to improve performance, degradation of the disodium 3,3'-dithiobis(1-propanesulfonate) (SPS) additive, which is employed as brightener, during copper via filling by electrodeposition and the influence of a byproduct on plating were investigated. Oxidative decomposition of SPS and formation of disodium 1,3-propanedisulfonate (PDS) at an IrO2 coated Ti insoluble anode during electrolysis were confirmed by NMR analysis. Furthermore, formation of PDS by chemical oxidation of SPS was also observed, suggesting anodic oxidation as the mechanism for PDS formation in the plating bath during electrolysis. By addition to a fresh bath, PDS was then shown to compromise via filling performance, where increase in PDS concentration resulted in a proportional performance decrease. This study clarified the anodic oxidation of SPS to PDS under electrolytic filling conditions and that the PDS concentration correlated to the filling ability of the copper plating bath.

Mechanical properties of Cu electroplated in supercritical CO2 emulsion evaluated by micro-compression test

This paper reports mechanical properties of Cu films fabricated by electroplating with supercritical CO2 emulsion (EP–SCE). Also, mechanical properties of Cu films fabricated by conventional electroplating (CONV) were evaluated to examine the effects of EP–SCE. The films were electroplated in an electrolyte composed of copper sulfate plating bath, supercritical CO2 and surfactant. Scanning ion microscopy images confirmed the supercritical CO2 emulsion refined microstructure of the plated Cu from about 1μm of grain size in CONV to about submicron order of grain size in EP–SCE. Non-tapered micro-sized Cu pillars were prepared by focused ion beam and used in the micro-compression test. Strengths of the Cu films fabricated by EP–SCE were 300MPa, which is higher than the CONV case. Impurity concentration in the films was evaluated by glow discharge optical emission spectroscopy, and no significant difference between EP–SCE and CONV was observed. The high strength in EP–SCE is believed to be mainly a result of grain refinement strengthening.

高速液体クロマトグラフィ法を用いた硫酸銅めっきの添加剤劣化挙動に関する評価

This study examined the influence of degradation of additive agents upon copper sulfate plating, i.e. polyethylene glycol (PEG) as a depressant, Janes green B (JGB) as a leveler, and bis(3-sulfopropyl) disulfide disodium salt (SPS) as a brightener. Trace analysis was conducted in a copper sulfate bath using high performance liquid chromatography (HPLC), which clarified the respective quantitative limits for measurement of PEG, JGB, and SPS as 10 mg/L, 0.01 mg/L, and 0.15 mg/L. The PEG molecule size and the SPS concentration decreased during electroplating. The value of throwing power was particularly lowered by the PEG degradation. Hydrogenation into N,N-dimethyl-p-phenylenediamine and methylene violet decomposed the JGB, thereby lowering the value of throwing power.

Microstructural Study of the Magnesium Alloy (Az31) Galvanostatically Etched for Different Periods Followed by Copper Electrodeposition in the Alkaline Copper-Sulfate Bath

A well adherent copper deposit on the Mg alloy (AZ31) can be obtained with a pretreatment with galvanostatic etching then followed by copper electrodeposition in an alkaline copper-sulfate plating bath. Experimental results show that the effect of galvanostatic etching on copper electrodeposition depends strongly on potential variation during anodic etching period. Oxygen-rich Cu and Mg layers were observed in the initial stage of galvanostatic etching. However, increasing the gavanostatic etching period to the potential plateau of its anodic polarization curve, the oxygen-rich Cu and Mg layers were almost removed and an activated surface of AZ31 can be achieved, which is suitable for Cu electrodeposition in the alkaline Cu-sulfate plating bath. The above-mentioned results were evidenced from the microstructure study with scanning transmission electron microscope.

Fabrication of Porous Copper Layers by Two-Steps Process: Electrodeposition and Combustion

Porous materials have been widely used since long ago because they possess important applications: acoustic, thermal insulation, building constructions, biomaterials, aeronautical application, etc. [. The development of porous materials is based on many materials. In a topic are develop the layer of materials by copper electroplating process. It is one of the oldest protective and decorative metallic coatings for steel and other basis metals [. Therefore, intensive studies were carried out to render copper electroplating suitable for different purposes. One of the most important baths used for electroplating copper was the electrolyte bath. The organic (PEG) additives are added copper sulphate plating bath to improve the quality of the porous layer. The electrolyte bath consists of the copper sulphate and PEG particle. Colloidal suspensions are often used as templates to fabricate porous layer material [. So an increment in porosity reduces the mechanical strength of porous materials. The polymer must have good adhesion with the polymer are determine the particle size and amount in electrolyte. Based on this process electroplating was used because the atomic are orderly arrangement and the atomic are packing than other process of porous materials. In the present study we report the preparation of porous layers materials on copper substrate by the electroplating process. The electrolyte solution system used as 35 g·l-1 Cu from CuSO4·5H2O in different conditions (current density and amount of PEG) and characterization of porous layer materials which process the appropriate morphology and chemical properties to be considered as feasible candidates for developing materials.

흑색 황산3가크롬을 이용한 태양열 흡열판 선택흡수막 도금기술

One of the most important factors that have a large influence on performance of the solar water heater system is performance of the solar collector, more detailedly, coating technology on the surface of the solar collector, which can provide high solar absorptance and low emittance. The core of the coating technology is to coat solar selective surfaces. In this study, various performance experiments are carried out using coating technology. Here, IGBT(Insulated Gate Bipolar Transistor) of 5000A-15V was used as the surface processing rectifier which can stably output power and also can control voltage and current. The plating solution mainly contains black chrome concentration, H-y Conductivity, N-u Complex, NF Additive and NC-2 Wetter. Before applying the black chrome coating on the copper plate, optimal conditions are provided by using various preprocessing methods such as removal of fat, activation, electrolytic polishing, nickel strike, copper sulfate plating and bright neckel plating, and then the automatic continuous coating experiment are performed according to plating time and cathode current density. In the experiment, after the removal of fat, chemical polishing, nickel strike and activation processes as the preprocessing methods, the black chrome coating was performed in a plate solution temperature of and a cathode current density of for 90 seconds. The thickness of chrome and nickel on the coated plate is , respectively. As a result of the coating experiment, it showed the most excellent performance having a high solar absorptance of 98% and a low emittance of when the black chrome surface had a thickness of .

Material Analysis of Lead Free Solder Deposited by Electrochemical Deposition

Lead-free solders have essentially replaced lead-tin solders for new microelectronic applications. At the same time, many products are continuing to go through miniaturization, so the behavior of the solder material is changing as a function of the connection size. As lead-tin solder has been replaced by lead-free alloys, electrodeposited SnAg has become the standard solder alloy used on wafers. Tin-based solders exhibit a complex material structure in the deposit, as recrystallization occurs in the deposit, and as intermetallic compounds form. Understanding the complex nature of these materials is becoming increasingly important to the performance of our electronic products. We have characterized ECD SnAg solder alloy deposits in terms of composition, grain size, phase, microstructure, and texture using EBSD analysis. We will discuss the effects of modifying the process parameters on the microstructure which could implications on the performance of the solder bump as a chip-level interconnect. We have seen that the metals deposit as β-tin with finely dispersed intermetallic grains. We have also seen evidence of recrystallization of the deposit subsequent to deposition, although the recrystallization behaviour is significantly different than the well-characterized copper recrystallization. Finally, the metal at the interface below the solder reacts with Sn to form intermetallic compounds, the compositions of which are dependent on the materials present. The effects of the process parameters on the deposit properties are becoming increasingly important to understand in order to control the properties of the interconnection, and how it changes over its lifetime. We have characterized the incorporation of trace organic materials in the deposit as a function of plating parameters. The deposition of SnAg from an MSA-based plating bath is very different from the deposition of copper from a copper sulfate plating bath. We have noticed that the incorporation of organic additive materials, as well as the grain size, increases as the deposition rate is increased in the deposition of SnAg.

Effect of Carbon Nanotube (CNT) Size on Wear Properties of Cu-Based CNT Composite Electrodes in Electrical Discharge Machining

The effect of carbon nanotube (CNT) size on the wear properties of Cu-based CNT composite electrode in electrical discharge machining (EDM) was studied. Cu-based CNT electrodes were fabricated by electroplating using a copper sulfate plating bath containing three kinds of CNTs. EDM was performed on stainless steel to evaluate the wear properties of the electrodes. Single pulse discharge was performed to evaluate the craters generated on the electrode surface. The wear ratios of Cu-based CNT composite electrodes decreased by 50-72% in relation to those of electrolytic Cu electrodes. The wear resistance of the composite electrodes was dependent on CNT size. It increased as the length and thickness of CNTs increased. The mechanisms of wear resistance in Cu-based CNT composite electrodes are discussed through observation and analysis of craters formed by single pulse discharge. The diameters of the craters are almost identical and largely independent of the size and presence of CNTs, indicating that CNT addition does not improve the thermal conductivities of the electrodes. Hence, the increase in wear resistance is independent of thermal conductivity. Exposed CNTs observed in craters on electrodes containing large CNTs with high wear-resistance properties do not decrease in diameter via electrical discharge, indicating that large CNTs can be resistant to pyrolysis at the melting points for Cu and Fe. It is suggested that the carbon layer with exposed CNTs on the electrode surface prevents the electrode from spark erosion in a manner identical to that of turbostratic carbon.

Modelling for fabrication of microelectrodes by localized electrochemical deposition for micro-electrodischarge machining

This paper presents the theoretical modelling and experimental investigation on the effect of different localized electrochemical deposition (LECD) parameters for fabricating a variety of microstructures. In order to estimate the rate of the deposition and the condition of the deposited structure, a set of mathematical relations is developed with the help of Faraday's laws of electrolysis and the Butler–Volmer equation. Mathematical simulation results are validated by experimental results. In this experimental process copper was deposited on the cathode surface. The variation in structure of the deposited electrode is achieved by changing the shape of a non-conductive mask. This mask is fabricated by an on-machine micromilling process and it is kept in contact with the cathode surface. The whole system is immersed in an acidified copper sulphate plating solution. This study gives a clear indication of the optimized operating range for the LECD process in order to fabricate high aspect ratio microstructures. Futhermore, the performance of the LECD electrode is evaluated by the fabrication of microholes on high-melting-point material such as a stainless steel workpiece.

Effect of Reverse Pulse on Copper Fill

Copper electroplating was performed in an acid copper sulfate plating bath with polyethylene glycol, sulfopropyl disulfide, and (HCl). In order to remove accelerator from the plating surface, reverse pulses were applied during the electroplating. After reverse pulse, suppression recovery was obtained with solution agitation while significant acceleration was observed in a stagnant bath. It was found that accumulated accelerator could be removed by reverse pulses with solution agitation, and leveling of copper deposit on a patterned chip was demonstrated by applying reverse pulses during the electroplating. In a stagnant accelerator free bath, suppression weakening was observed after reverse pulse. It was suggested that copper chloride, which may be formed by the reverse pulse, attracts accelerator adsorption. Therefore, it is conceivable that significant acceleration in the stagnant bath is caused by mixed effect of the suppression weakening and the attraction of accelerator by the copper chloride.

Copper electrodeposition from an acidic plating bath containing accelerating and inhibiting organic additives

Copper electrodeposition on copper from still plating solutions of different compositions was investigated utilising electrochemical impedance spectroscopy (EIS), cyclic voltammetry, and scanning electron microscopy (SEM). An acid copper sulphate plating base solution was employed either with or without sodium chloride in the presence of a single additive, either polyethylene glycol (PEG) or 3-mercapto-2-propanesulphonic acid (MPSA), and their mixture. Thallium underpotential deposition/anodic stripping was employed to determine the adsorption capability of additives on copper. In the absence of chloride ions, MPSA shows a moderate adsorption on copper, whereas PEG is slightly adsorbed. At low cathodic overpotentials, the simultaneous presence of MPSA and chloride ions accelerates copper electrodeposition through the formation of an MPSA-chloride ion complex in the solution, particularly for about 220 μM sodium chloride. The reverse effect occurs in PEG-sodium chloride plating solutions. In this case, from EIS data the formation of a film that interferes with copper electrodeposition can be inferred. At higher cathodic overpotentials, when copper electrodeposition is under mass transport control, the cathode coverage by a PEG-copper chloride-mediated film becomes either partially or completely detached as the concentration of chloride ions at the negatively charged copper surface diminishes. The copper cathode grain topography at the μm scale depends on the cathodic overpotential, plating solution composition and average current density. Available data about the solution constituents and their adsorption on copper make it possible to propose a likely complex mechanism to understand copper electrodeposition from these media, including the accelerating effect of MPSA and the dynamics of PEG-copper chloride complex adsorbate interfering with the surface mobility of depositing copper ad-ions/ad-atoms.

Seed layer corrosion of Damascene structures in copper sulfate electrolytes

The influence of sulfuric acid concentration in copper sulfate plating solutions on the stability of a 1000 Å seed layer in Damascene structures is presented. Immersion of a seeded wafer into the plating solutions results in chemical dissolution, thinning the copper seed layer. Anodic current density steps initiate seed layer corrosion resulting in exposure of the underlying TaN barrier layer. Large applied current density steps (>300 μA/cm 2) or high free sulfuric acid concentration causes very rapid dissolution of the seed layer. The anodic dissolution efficiency is greater than 100% indicating that chemical dissolution of copper is contributing to the disappearance of the copper seed layer.

はんだボール接合信頼性に優れたＢＧＡパッケージ用ビアホール内銅めっき充てんテープ材

The deterioration of ball solderability is indicated with the narrower pitch of solder balls of BGA package. Accordingly, the tape carrier that the via-holes for the ball soldering were buried with copper plating was developed for the prevention. In order to deposit of the copper plating in minute blind via-holes of the polyimide tape, suitable copper sulfate plating bath at the thickness over 40μm was found. And, the analysis and control technique of additives as dispersing agent and brightener, etc. was also established. Uniformity of the current distribution in the plating tank was necessary for the small deviation of the copper plating thickness. In order to solve the problem, based on the computer simulation, the optimum current shielding board was installed in the tank, and the equalizing of the thickness was achieved. On the bases of these results, it was established the mass-production technology of uniformly and high-speed copper plating in minute via-holes which were formed on tape carrier of long length. And the continuous copper plating machine for tape carrier was constructed. For further miniaturization of the LSI package, the developed technology has been widely applied to the tape substrate.

An electrochemical approach to total organic carbon control in printed circuit board copper sulfate plating baths Part II: Overall system

An electrochemical system for oxidative removal of high levels of total organic carbon (TOC) in printed circuit board (PCB) copper sulfate plating baths has been developed. These organic contaminants build-up over the course of pattern plating of PCBs, and at high concentrations they interfere with the quality of the plated copper. The chemistry of the electrochemical oxidation of the plating bath contaminants was qualitatively followed using high performance liquid chromatography (HPLC) and chemical oxygen demand (COD) measurements. A complete treatment system is described and rough calculations are given showing, for a given set of conditions, how the proper choice of electrode material and current density can minimize the system cost.

An electrochemical approach to total organic carbon control in printed circuit board copper sulfate plating baths Part I: Anode performances

An electrochemical approach to decreasing high levels of total organic carbon (TOC) in printed circuit board (PCB) copper sulfate plating baths has been investigated. The organic contaminants build-up over the course of pattern plating of PCBs, and at high concentrations they interfere with the quality of the plated copper. The electrochemical approach involves destroying the organic contaminants using electrochemical oxidation. Various anode materials (glassy carbon, lead, lead dioxide, platinum, iridium dioxide and doped tin dioxide) were screened for this application. Some corrosion data is presented for these anodes and their performance for TOC removal at various current densities has been roughly quantified using an apparent first order rate constant. The three best performing anode materials gave increasing oxidation rates going from platinum to doped tin dioxide to lead dioxide, unfortunately anode stability decreased in the same order.

Via-filling using electroplating for build-up PCBs

The requirement of miniaturization of printed circuit boards has been increased with downsizing of electronic devices. However, the conventional multi-layered printed circuit boards are now facing the limitation for high mounting densities. Therefore, a newly developed build-up process has emerged as a new multi-layered printed circuit board manufacturing process. This new technology has adopted the micro-vias for connection between each conductive layer. If the micro-vias can be filled with copper metal, signal propagation is enhanced by via-on-via connection. Therefore, effective circuitry can be achieved. However, filling the conductive layer with the micro-vias is becoming difficult using the conventional plating process or the electrical conductive paste. Filling of the micro-vias by electroplating is studied. It was confirmed that copper sulfate concentration in copper sulfate plating bath is one of the key factors to fill the micro-vias, and the vias can be filled using a high copper concentration bath.

Corrosion study of copper composite coating by impedance spectroscopy method

This paper investigates the corrosion behaviour of copper and copper-matrix composite coatings, with zirconium oxide particles embedded during electrodeposition from an acid copper sulphate plating bath. The corrosion studies were carried out on the basis of the polarisation resistance measurements by means of the impedance diagrams plotted in the complex plane, and Faradaic distortion method in the following acrated solution: 0.5M sulphuric acid, The results are discussed by taking into account the possible influence of disperse phase in the mechanism of electrodeposited copper corrosion. The zirconium oxide particles embedded in the electroplated copper increase the polarisation resistance and decrease the corrosion rates with three times in sulphuric acid as compared with electrodeposited pure copper.

Corrosion study of copper composite coating by impedance spectroscopy method

This paper investigates the corrosion behaviour of copper and copper-matrix composite coatings, with zirconium oxide particles embedded during electrodeposition from an acid copper sulphate plating bath. The corrosion studies were carried out on the basis of the polarisation resistance measurements by means of the impedance diagrams plotted in the complex plane, and Faradaic distortion method in the following aerated solution: 0.5M sulphuric acid. The results are discussed by taking into account the possible influence of disperse phase in the mechanism of electrodeposited copper corrosion. The zirconium oxide particles embedded in the electroplated copper increase the polarisation resistance and decrease the corrosion rates with three times in sulphuric acid as compared with electrodeposited pure copper.

Behavior of aluminum nitride ceramic surfaces under hydrothermal oxidation treatments

Aluminum nitride (AlN) ceramics were subjected to various hydrothermal oxidation treatments, such as high-temperature oxidation in air at 1000 degrees C, water and high-pressure steam treatments, and copper sulfate plating solution at 70 degrees C for 8 h. The resulting physical and chemical changes of these surfaces were characterized using various analytical techniques, such as surface profilometry, scanning electron microscopy (SEM), thermogravimetric analysis, and X-ray photoelectron spectroscopy (XPS). These studies indicate that the AlN ceramic surfaces are altered significantly by the surface treatments. The interaction of water as well as steam with the AlN ceramic surfaces resulted in the formation of AlOOH and Al(OH)/sub 3/. The thermally grown oxide layer (Al/sub 2/O/sub 3/) on AlN is more stable and offers protection from subsequent wet treatments. Surface treatment using a copper sulfate additive plating solution revealed significant alteration in the surface roughness value, from an initial value of 0.5 mu m to a final value of 25.0 mu m during 8 h of treatment at 70 degrees C. SEM studies revealed the alteration of AlN surface morphology. The chemical change occurring on the AlN was analyzed using the XPS method, and results are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>