Electroless Silver Plating Research Articles

Fabrication of glass fibers uniformly coated with metal films by magnetron sputtering by a two step process involving fixation by a photoresist

In this paper, glass fibers with high aspect ratio were used as inner-core templates to prepare core–shell functional particles by way of magnetron sputtering by a two step process involving fixation by a photoresist. The morphologies and constituents of the metal-coated glass fibers were characterized using a scanning electron microscopy and an energy dispersive spectrometer. The crystal structures were characterized by employing X-ray diffraction. The surface roughnesses of glass fibers before and after magnetron sputtering were measured by an atomic force microscope. The results show that the glass fibers after magnetron sputtering have smooth and compact surface coatings, which exhibit face-centered cubic (fcc) structures. The RMS values of the metal-coated glass fibers are 4.20 ± 0.5 nm and 5.74 ± 0.5 nm for aluminum and silver respectively, which are significantly higher than that (1.36 ± 0.2 nm) of original glass fibers. Furthermore, the surface coatings of the glass fibers after electroless silver plating are very poor and there are lots of tiny fragments on them, resulting in high surface roughness (47.70 ± 5 nm). By comparison, the coating qualities of magnetron sputtering are significantly superior to that of electroless plating, indicating that magnetron sputtering is an excellent preparation method of core–shell particles.

Acceleration of Electroless Silver Deposition from Solutions Containing Cobalt(II) as Reducing Agent

By using cobalt(II) complexes with ammonia or organic amines as reducing agents electroless silver plating solutions of high stability were developed; the deposition of high quality Ag layers with plating rate 1 – 3 μm/h are known [1-3].In this work, the possibilities to increase silver plating rate without changing of concentration of reactants and temperature were studied. The additives enhancing the partial electrochemical reactions of the electroless plating process – anodic Co(II) oxidation and cathodic Ag(I) reduction – were applied. The effect of chloride and bromide ions was studied by electrochemical and chemical kinetics methods, including electrochemical quartz crystal microgravimetry (EQCM).Electrochemical measurements showed that the Co(II) anodic oxidation on silver electrode is enhanced by the presence of halide ions. At 1 mM level, KCl additive change the rate of Co(II) oxidation only little, while KBr and KI increase the rate considerably. Accelerating effect of halides corresponds to the increase in adsorption ability of halides in the sequence Cl-<Br-<I-, the adsorbed halide ions could facilitate the electron transfer through the halide bridge. The electroless silver deposition was shown to increase by factor of 2-3 at chloride concentrations 20 – 50 mM at satisfactory solution stability. The enhancing effect is related to anodic cobalt(II) oxidation reaction. AFM images of the silver surface showed absence of considerable changes of real surface area, and the rate increase is obviously not caused by development of catalytic surface.

A high performance electromagnetic interference shielding epoxy composite with multiple conductive networks in the matrix

In this article, a high electromagnetic interference shielding effectiveness (EMI SE) polymer composite with multiple conductive networks was manufactured via combining a conductive foam, low loading multi-wall carbon nanotubes (MCNTs), bisphenol A-type epoxy resin NPEL-128, curing agent polyamide Versamid 140, and reactive diluent glycol diglycidyl ether. The conductive foam was prepared using melamine foam (BasotectW®) through an electroless silver plating process. The resistivity of the foam and each composite system were measured by a four-point probe resistivity determiner. The morphology of the composites was observed by scanning electron microscope and the silver contents on the foam skeletons were measured by thermal gravimetric analysis. Dynamic mechanical analysis was employed to studying the mechanical properties and structural changes of the composites. A very low minimum value of 0.06 Ω · cm was obtained by the foam. Due to its intrinsic structure, multiple networks composites exhibited a lower resistivity value which was nearly 5 ~ 8 orders of magnitude lower than that of CNTs/epoxy nanocomposite at the same CNTs loading. The EMI SE of each composite system was measured by a vector network analyzer in 0.2 ~ 18 GHz. The SE value of the multiple networks composites, only containing 2 wt % CNTs and 3.3 wt % silver, reached a maximum of 88 dB and an average of 68 dB. All results above showed that the synergistic effect from the multiple conductive networks was contributed to enhancing the conductivity and EMI SE of the composites.

Silver-coated glass fibers prepared by a simple electroless plating technique

Silver-coated glass fibers have been successfully fabricated using a simple electroless silver plating. The structures of the silver/glass fiber composites were characterized by X-ray diffraction, high-resolution transmission electron microscopy, and scanning electron microscopy, respectively. The morphology investigation showed that the silver coatings were compact and continuous. The minimum volume resistivity could reach 4.53 × 10−4 Ω cm, suggesting excellent electric conductivity. It was found that the quality of silver deposition was influenced by dosage of ammonia solution and plating temperature. Ammonia solution served as complexing reagent and supplied an alkaline media, and higher temperature easily led to metallic oxidation. The current method is simple-handle, inexpensive, large production, and the obtained silver/glass fibers can be used as fillers to fabricate electromagnetic wave shielding materials.

Electromagnetic shielding effectiveness and mechanical property of polymer–matrix composites containing metallized conductive porous flake-shaped diatomite

The porous flake-shaped diatomite particles with different micropores diameter were used as forming templates for the fabrication of the conductive core–shell functional fillers by electroless silver plating. The surface morphologies and phase structures of the surface coatings onto diatomite particles with different micropores diameter were evaluated. The effects of micropores diameter on electrical resistivity, electromagnetic shielding effectiveness and mechanical property of polymer–matrix composites containing silver-coated diatomite particles were also investigated in detail. The results show that the micropores onto initial diatomite particles after plating are completely covered with the coating, while the micropores onto diatomite particles with expanding pores are still visible. The expanding micropores onto diatomite particles in certain size range have less impact on the phase structures, electrical resistivity and electromagnetic shielding effectiveness. However, the mechanical properties of composites are improved significantly after expanding micropores by HF acid corrosion.

New Technology of Electroless Silver Plating on Fly Ash Cenospheres with Thermo-Alkaline Activation

Electroless silver plating on the surface of fly ash cenospheres was prepared by slowly adding the solution of AgNO3 into the mixed solution of D-glucose solution and alkaline solution after thermo-alkaline treatment. The morphology and composition of the silver-coated fly ash cenospheres composite powders were observed and analyzed by using SEM, EDS and XRD, and the influence of pH, loading quantity on silver plating was invested. The results revealed that, with the pH value of plating solution increasing, the precipitation of silver is improved, but led to self-accelerating decomposition if too high, and the influence of loading quantity on silver relative content and electro-conductivity of composite powders is very great. The silver shell of composite particles is even and compact when the pH value is 12.57 and the loading quantity is 4g/L, which resistivity can reach to 0.05Ω•cm.

Factors Affecting the Morphology of Pb-Based Glass Frit Coated with Ag Material Prepared by Electroless Silver Plating

Pb-based glass frit coated with nanosilver material for Si solar cell applications has been directly prepared by electroless silver plating. Activation of the glass frit was accomplished by using glycol, with the aim of reducing the silver ions to elemental silver on the surface of the glass frit. Electroless silver plating onto the glass frit was successfully realized using two kinds of electroless plating bath. However, the morphology of the composite powder greatly affected the modality, sheet resistance, series resistance, and photoelectric conversion efficiency of the conducting silver films. We found that the activation temperature affected the number and distribution of silver nanoparticles. Meanwhile, the average grain size of the silver particles and the silver content in the Pb-based glass frit coated with Ag material could be controlled by adjusting the pH value and loading capacity, respectively, during plating.

Synthesis and characterization of Ag/Fe3O4 electromagnetic shielding particles

Ag/Fe3O4 nano-composites are synthesized by electroless silver plating technique and characterized by X-ray diffraction, scanning/transmission electron microscope, magnetic measurement equipment and vector network analyzer. They show the silver layer coated on the surface of the particles successfully, and which can enhance the dielectricity and permeability properties of the ferromagnetic particles. The dielectric loss values of the composites are more than 1.0 in the almost whole test frequency range and the imaginary part of permeability of Ag/Fe3O4 is higher than real part in 2–5GHz. The value of Hc is increased to 165.2Oe due to the extended relaxation time of magnetic domain deflection of the magnetic powders which covered by silver layer. And the calculated microwave loss is more than 20dB in the whole frequency range. As a result, the Ag/Fe3O4 nano-composites are expected to be used as electromagnetic shielding particle material in multiband smoke agent.

Fluorescent microparticles fabricated through chemical coating of O/W emulsion droplets with a thin metallic film

We have developed a simple fabrication process for fluorescent silver-coated liquid particles. The synthesis involves the encapsulation of quasi-monodisperse micronic soybean oil-in-water emulsion droplets in a polydopamine shell followed by an electroless silver plating of the surface. Due to the presence of the thin silver layer, the droplets exhibit a broad range fluorescence that shows no photobleaching upon illumination. The method shows that multimodal colloidal microparticles can be produced via a high-yield method from sustainable, off-the-shelf products with mild synthesis routes in aqueous conditions.

Fabrication of highly electrically conducting fine patterns via substrate-independent inkjet printing of mussel-inspired organic nano-material

We report the inkjet printing of an aqueous suspension of synthesized mussel-inspired poly(dopamine) nanoparticles and the subsequent site-selective silver electroless plating process.

Study on Chemical Plating and Shielding Effectiveness for Electromagnetic Shielding Fabric

For the purpose of investigating the influence of different process condition on alkali reduce rate and mass increase rate, the techniques of polyester fiber pretreatment, electroless copper plating, and electroless silver plating were carefully analyzed and compared. It was found that the best coursing condition was: 5.5 mol/L concentration, 65°C temperature, 30 minutes reaction time, 1:200 bath ratio. Under these conditions, the alkali reduction rate was 11.38%. As for copper plating liquid concentration of 0.08 mol/L, pH value 9.5, 80°C temperature, liquid silver plated concentration 0.02 mol/L, the coating weight gain rate was 52.1%. Microcosmic morphology on coating surface and surface resistance test show that the fabric was evenly coated with Cu, Ag, metal ions, which resulting in excellent electric conductivity and good electromagnetic shielding performance.

Electroless Silver Plating Process on Al-Ag Alloy Powder

The Ag coating was deposited on the surface of Al-Ag alloy powder by electroless plating process. 10 wt% of AgNO3 was put in the powder for precursor replacement reaction, and then added the powder into electroless plating bath which contained glucose solution, solution of silver ammonia, thiourea solution, tartaric acid solution and absolute ethanol. The effects of formula components were analyzed. The surface morphology of the prepared composite particles was studied with SEM and their chemical compositions were confirmed by XRD. With the chemical etching method, silver content of the powder was determined. The studies have shown that an uniform, complete and dense silver coating for the Al-Ag composite powders was generated by this method, with the silver content being 20wt%, and the conductivity was favorable.

Optimization of Electroless Silver Plating Process on Fabric Surface without Activation and Sensitization

Optimization of Electroless Silver Plating Process on Fabric Surface without Activation and Sensitization

Electroless silver plating on Pb-based glass frits by a one-step activation method without stannum and palladium

Abstract In this paper, a new activation method—taking ethylene glycol as reducing agent for the formation of metallic silver (Ag 0 ) from silver ions (Ag + )—has been introduced to form silver nuclei on Pb-based glass frits for silver paste. Electroless silver plating on glass frits is successfully realized by adding the activated glass frits into two kinds of electroless plating baths. The result shows that the silver particles with an average grain size around 100 nm are well distributed on the glass frits. Compared with the traditional electroless plating method, this process avoids the interference of chloride ions which may cause AgC1 precipitation as well as the tin ions which are harmful to human health. Furthermore, roughening treatment is not involved in the activation, so composition change will not happen to glass frits and front silver paste in the follow-up process.

One-step syntheses and properties of carbon microspheres with amino groups

This paper proposes a method that can be used to synthesize carbon microspheres with controllable sizes, rich amino groups and oxygen-containing groups. The synthesized materials are portrayed by various methods including SEM, FT-IR, XRD, and EDX. The resulting carbon spheres presented an amorphous characteristic, which displayed a broad range in diameter, high degree of sphericity, and smoothness with amino groups and oxygen-containing groups. Pyknotic and smooth silver shells were deposited on carbon spheres by electroless silver plating. Moreover, it could directly reduce Ag+ to Ag in aqueous silver nitrate. These materials can potentially be used as adsorbents for heavy-metal removal from aqueous solutions.

Surface Silverized Meta-Aramid Fibers Prepared by Bio-inspired Poly(dopamine) Functionalization

A facile method was developed to fabricate highly electrically conductive aramid fibers. The immobilization of silver nanoparticles on the surface of polymetaphenylene isophthamide (PMIA) fibers was carried out by the functionalization of the PMIA fibers with poly(dopamine), followed by electroless silver plating. The poly(dopamine) (PDA) layer was deposited on the PMIA surface by simply dipping the PMIA substrate into an alkaline dopamine solution. The silver ions can be chemically bound to the catechol and indole functional groups in PDA. The silver ions were reduced into silver nanoparticles by using glucose as the reducing agent, resulting in a distinct silver layer on the PMIA surface. The obtained silver deposit was homogeneous and compact. The chemical composition of the modified PMIA fibers was studied by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS), and the crystalline structure of the silver-coated PMIA fibers was characterized by powder X-ray diffraction (XRD). The topography of the modified PMIA fibers was investigated by scanning electron microscopy (SEM). The four-point probe resistivity meter was used to study the electrical resistivity of the silver-coated PMIA fibers, the results indicated that the electrical resistivity could be as low as 0.61 mΩ·cm, with a controllable silver content, and a satisfactory stability by ultrasonic treatment.

Rapid degradation of hexachlorobenzene by micron Ag/Fe bimetal particles

The feasibility of the rapid degradation of hexachlorobenzene (HCB) by micron-size silver (Ag)/iron (Fe) particles was investigated. Ag/Fe particles with different ratios (0, 0.05%, 0.09%, 0.20%, and 0.45%) were prepared by electroless silver plating on 300 mesh Fe powder, and were used to degrade HCB at different pH values and temperatures. The dechlorination ability of Fe greatly increased with small Ag addition, whereas too much added Ag would cover the Fe surface and reduce the effective reaction surface, thereby decreasing the extent of dechlorination. The optimal Ag/Fe ratio was 0.09%. Tafel polarization curves showed that HCB was rapidly degraded at neutral or acidic pH, whereas low pH levels severely intensified H2 production, which consumed the reducing electrons needed for the HCB degradation. HCB degradation was more sensitive to temperature than pH. The rate constant of HCB dechlorination was 0.452 min−1 at 85°C, 50 times higher than that at 31°C. HCB was degraded in a successive dechlorination pathway, yielding the main products 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene within 2 hr.

Polyester metallisation with electroless silver plating process

In this paper, electroless silver plating process for polyester was reported. The electroless silver plating is basically divided into four stages including pre-cleaning, sensitisation, electroless silver deposition and post-treatment. As the electroless silver plating stage is the key stage in affecting the brilliant appearance and various functional properties such as conductivity and ultra-violet protection, we will study the effect of process variables, i.e. amount of silver nitrate (AgNO3), concentration of ammonium hydroxide (NH4OH), concentration of sodium hydroxide (NaOH) and process temperature, using increased amount of silver in fabric surface as an indicator, for optimising the electroless silver plating process for possible industrial application. Experimental results revealed that amount of silver nitrate (AgNO3)=1.77×10−3 mole; concentration of ammonium hydroxide (NH4OH)=6.25 %; concentration of sodium hydroxide (NaOH)=0.008 g/ml and process temperature=25 °C can give the best electroless silver plating for polyester fabric. The surface characteristics of the electroless silver-plated polyester fabric were evaluated by scanning electron microscope, X-ray photoelectron spectroscopy and X-ray diffraction analysis. Meanwhile, the performance properties of the electroless silver-plated polyester fabric were measured by CIE L*, a* and b* values, conductivity as well as ultraviolet protection. The experimental results would be discussed thoroughly in this paper.

Preparation and Characterization of Electroless Silver Plating on PAN Fiber with Chelating Agent of APTES/MPTES

Modified by silane coupling agents APTES and MPTES, PAN fiber was provided with multi-chelating-group on it. Through the chelating effect, it can be directly used to eletroless silver plating without roughening, sensitization and activation. The molecule structure, morphology and thermal stability were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and therm-gravimetric (TG) analysis. In addition, electrical conductivity, and washing performance were also tested respectively. The results indicated that silver-coated PAN fiber based on APTES/MPTES modification had high conductivity with a compact and homogeneous silver layer, as well as good washing fastness performance.

Selective electroless plating of silver nanograting patterns with no lateral growth for the fabrication of polarizers

Metal patterning has been useful for fabricating many optical and electronic devices. Among all the patterning methods, selective electroless plating in combination with micro-contact printing (μCP) is a simple process compatible with roll-to-roll processing. However, this process suffers from the difficulty to avoid lateral growth during the electroless plating of metal. That will place a limitation on the fabrication of nanoscale patterns, such as the metal wire grid polarizer. In this study, we launch a new approach to restrict the lateral growth of metal by depositing metal selectively in the grooves of a three-dimensional template. The template was first treated with a self-assembled monolayer (SAM) of octadecyltrichlorosilane (OTS) only on the protrusion surface using μCP, and then treated in SnCl2 solution to activate the surface of the trenches for the selective electroless plating (ELP) of silver inside the trenches. A wire-grid polarizer was thus fabricated by selectively depositing 70nm-thick silver in the trenches of a nanograting template with a trench width of 100nm and a pitch of 180nm. The maximum extinction ratio of the polarizer thus obtained was about 130 in the wavelength range of 635–650nm.