Search Results (23)

With the rapid advances of the electronics industry, a large amount of acidic etching waste solutions (AEWS) for etching Printed Circuit Board (PCB) are generated, which require complete remediation and sustainable recycling to avoid environmental pollution and wasting of resources. Herein, the novel purification technology for the acidic copper-containing etching waste solution was exploited via integrated alkali gradient pH control (3.0, 3.2, and 3.5). At pH 3.0, the system demonstrated selective metal removal with 94.02% efficiency for Fe and 82.60% for Mn. Elevating the pH to 3.2 enabled effective elimination of Zn (59.32%), Cr (59.46%), and Al (33.24%), while maintaining minimal copper loss (8.16%). Further pH adjustment to 3.5 achieved enhanced removal efficiencies of 97.86% (Fe), 91.30% (Mn), 59.38% (Zn), 62.10% (Cr), 21.66% (Ca), 34.05% (Al), and 26.66% (Co), with copper retention remaining high at 70.83% (29.17% loss). Furthermore, using the purified AEWS (pH 3.2) as precursor, high-purity nano-CuO was successfully synthesized through a Cu₂(OH)₃Cl conversion-calcination process, exhibiting 99.20% CuO purity with 0.0012% chlorine content and <0.1% metallic impurities. The development and application of the purification technology for AEWS containing copper, along with the production methodology for high-purity CuO, were significant to the fields of electronic information industry, environmental engineering, green industry and sustainable development of the ecological environment. Full article

This study reports the development of a highly sensitive electrochemical sensor for phosphate ion detection, utilizing silicon nanowires (SiNWs) as the transducing elements and a novel copper (II) phthalocyanine-acrylate polymer adduct (Cu (II) Pc-PAA) as the functional sensing layer. Silicon nanowires were fabricated via metal-assisted chemical etching (MACE) with etching durations of 15, 25, 35, 45, and 60 min. The SiNWs etched for 15 min exhibited the highest sensitivity, showing superior electrochemical performance. Functionalized SiNWs were systematically evaluated for phosphate ion (HPO₄²⁻) detection over a wide concentration range (10⁻¹⁰ to 10⁻⁶ M) using Mott–Schottky measurements. The surface morphology of the SiNWs was thoroughly characterized before and after Cu (II) Pc-PAA layer functionalization. The sensing material was analyzed using contact angle goniometry and scanning electron microscopy (SEM), confirming both its uniform distribution and effective immobilization. The sensor displayed a Nernstian behavior with a sensitivity of 28.25 mV/Decade and an exceptionally low limit of detection (LOD) of 1.5 nM. Furthermore, the capacitive sensor exhibited remarkable selectivity toward phosphate ions, even in the presence of potentially interfering anions such as Cl⁻, NO₃⁻, SO₄²⁻ and ClO₄⁻. These results confirm the sensor’s high sensitivity, selectivity, and fast response, underscoring its suitability for environmental phosphate ion monitoring. Full article

Novel dentin bonding pretreatment using copper sulfate (CuSO₄) and dipotassium hydrogen phosphate (K₂HPO₄) may create a more hydrophobic environment for dentin bonding. Thus, this study aims to investigate the impact of a CuSO₄ + K₂HPO₄ pretreatment on dentin μTBS when bonded with a universal adhesive to conventional and CAD/CAM resin composites. Eighty recently extracted human molars (n = 80) were chosen and placed in transparent acrylic blocks to expose the crowns entirely. Nano-filled resin composite and CAD/CAM resin blocks were selected. Based on the dentin pretreatment, type of resin composite, and adhesion strategy, the teeth were randomly allocated into eight equal groups (n = 10). The microtensile bond strength (μTBS) and fracture mode were determined. A three-way analysis of variance (ANOVA) was used to analyze the μTBS data, followed by Tukey’s post hoc test. The μTBS values were not significantly affected by either the resin composite type (p > 0.05) or the adhesive strategy (p > 0.05) according to the three-way ANOVA results. Conversely, significant differences were detected between no dentin pretreatment (24.20 ± 4.54 MPa) and CuSO₄ + K₂HPO₄ pretreatment (33.66 ± 5.22 MPa) using an etch-and-rinse adhesive strategy for nano-filled composites (p < 0.001). Additionally, significant differences were detected between no dentin pretreatment (24.71 ± 4.33 MPa) and CuSO₄ + K₂HPO₄ pretreatment (32.49 ± 4.92 MPa) using an etch-and-rinse adhesive strategy for CAD/CAM resin blocks (p < 0.001). Moreover, significant differences were detected between no dentin pretreatment (21.20 ± 3.40 MPa) and CuSO₄ + K₂HPO₄ pretreatment (30.31 ± 3.87 MPa) using a self-etching adhesive strategy for nano-filled composites (p < 0.001). Also, significant differences were detected between no dentin pretreatment (23.89 ± 3.89 MPa) and CuSO₄ + K₂HPO₄ pretreatment (31.22 ± 4.71 MPa) using a self-etching adhesive strategy for CAD/CAM resin blocks (p < 0.001). In conclusion, dentin μTBS was enhanced by a copper-based treatment when used with nano-filled and CAD/CAM resin blocks. Full article

A surface treatment of amorphous alloy was conducted using reciprocating friction, and precursors with varying degrees of surface roughness were selectively etched to form a three-dimensional nanoporous structure with interconnected networks. The wear behavior induced by friction facilitates dealloying to different extents. While altering the surface roughness of the amorphous alloy, this method preserves its unique structure and maintains the advantages of the precursor in preparing nanoporous materials (NPMs). Under identical dealloying conditions, the thickness of the nanoporous copper layer on the rougher surface (with a surface roughness of approximately 0.808) is significantly greater than that on the smoother surface (with a surface roughness of approximately 0.002), and this disparity increases over time. The findings indicate that friction-induced changes in surface roughness play a crucial role in the preparation of nanoporous copper via dealloying. Modifying the surface roughness through friction can enhance the dealloying process, improve the adhesion between the nanoporous copper (NP-Cu) layer and the amorphous matrix, and mitigate crack propagation during NP-Cu formation and under stress. Selecting an appropriate level of roughness can enhance the long-term stability of NP-Cu. Full article

Etching methods of aluminum foils used in electrolytic capacitors are selected based on the operating voltages, with DC and AC etching typically used for the anode foils of high- and low-voltage capacitors, respectively. The initial pits continue to grow and eventually form tunnels or cubic pits by DC or AC etching, respectively. This paper describes the pit formation and growth process, focusing on the involvement of passive film inside the pit and facet dissolution. In particular, it is found that high-purity aluminum foil containing Ti promotes the formation of passive film (etch film) inside pits during the cathodic half cycle of AC etching, and Cu promotes facet dissolution. These behaviors significantly affect the surface area expansion by electrolytic etching. In addition, the effects of crystal orientation, surface defects associated with oxide film crystallization, and a trace element, Pb, as factors affecting the pit initiation sites will be discussed. Full article

This study aimed to prepare a facile hierarchical aluminium surface using a two-step process consisting of chemical etching in selected concentrations of CuCl₂ solution and surface grafting through immersion in an ethanol solution containing 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane. The goal was to achieve superhydrophobic characteristics on the aluminium surface, including enhanced corrosion resistance, efficient self-cleaning ability, and improved anti-icing performance. The surface characterisation of the untreated aluminium and treated in CuCl₂ solutions of different concentrations was performed using contact profilometry, optical tensiometry, and scanning electron microscopy coupled with energy dispersive spectroscopy to determine the surface topography, wettability, morphology, and surface composition. The corrosion properties were evaluated using potentiodynamic measurements in simulated acid rain solution and salt-spray test according to ASTM B117-22. In addition, self-cleaning and anti-icing tests were performed on superhydrophobic surfaces prepared under optimal conditions. The results showed that the nano-/micro-structured etched aluminium surface with an optimal 0.5 M concentration of CuCl₂ grafted with a perfluoroalkyl silane film achieved superhydrophobic characteristics, with water droplets exhibiting efficient corrosion protection, self-cleaning ability, and improved anti-icing performance with decreased ice nucleation temperature and up to 545% increased freezing delay. Full article

Hollow silica spheres have been widely studied for drug delivery because of their excellent biosecurity and high porosity. However, difficulties with degradation in the tumor microenvironment (TME) and premature leaking during drug delivery limit their clinical applications. To alleviate these problems, herein, hollow organosilica spheres (HOS) were initially prepared using a “selective etching strategy” and loaded with a photothermal drug: new indocyanine green (IR820). Then, the Cu²⁺–tannic acid complex (Cu-TA) was deposited on the surface of the HOS, and a new nanoplatform named HOS@IR820@Cu-TA (HICT) was finally obtained. The deposition of Cu-TA can gate the pores of HOS completely to prevent the leakage of IR820 and significantly enhance the loading capacity of HOS. Once in the mildly acidic TME, the HOS and outer Cu-TA decompose quickly in response, resulting in the release of Cu²⁺ and IR820. The released Cu²⁺ can react with the endogenous glutathione (GSH) to consume it and produce Cu⁺, leading to the enhanced production of highly toxic ·OH through a Fenton-like reaction due to the overexpressed H₂O₂ in the TME. Meanwhile, the ·OH generation was remarkably enhanced by the NIR light-responsive photothermal effect of IR820. These collective properties of HICT enable it to be a smart nanomedicine for dually enhanced chemodynamic therapy through GSH depletions and NIR light-triggered photothermal effects. Full article

Bilayer graphene is a contender of interest for functional electronic applications because of its variable band gap due to interlayer interactions. Graphene growth on Cu is self-limiting, thus despite the fact that chemical vapor deposition (CVD) has made substantial strides in the production of monolayer and single-crystal graphene on Cu substrates, the direct synthesizing of high-quality, large-area bilayer graphene remains an enormous challenge. In order to tackle this issue, we present a simple technique using typical CVD graphene growth followed by a repetitive wrinkling-etching-regrowth procedure. The key element of our approach is the rapid cooling process that causes high-density wrinkles to form in the monolayer area rather than the bilayer area. Next, wrinkled sites are selectively etched with hydrogen, exposing a significant portion of the active Cu surface, and leaving the remaining bilayer areas, which enhance the nucleation and growth of the second graphene layer. A fully covered graphene with 78 ± 2.8% bilayer coverage and a bilayer transmittance of 95.6% at room temperature can be achieved by modifying the process settings. Bilayer graphene samples are examined using optical microscopy (OM), scanning electron microscopy (SEM), Raman spectroscopy, and an atomic force microscope (AFM) during this process. The outcomes of our research are beneficial in clarifying the growth processes and future commercial applications of bilayer graphene. Full article

Levels of lead (Pb) in tap water that are well below established guidelines are now considered harmful, so the detection of sub-parts-per-billion (ppb) Pb levels is crucial. In this work, we developed a two-step, facile, and inexpensive fabrication approach that involves direct bonding of copper (Cu) and liquid crystal polymer (LCP) followed by polyester resin printing for masking onto Cu/LCP to fabricate Cu thin-film-based Pb sensors. The oxygen plasma-treated surfaces resulted in strongly bonded Cu/LCP with a high peel strength of 500 N/m due to the highly hydrophilic nature of both surfaces. The bonded specimen can withstand wet etching of the electrode and can address delamination of the electrode for prolonged use in application environments. The Cu-foil-based electrochemical sensor showed sensitivity of ~11 nA/ppb/cm² and a limit of detection (LOD) of 0.2 ppb (0.2 µg/L) Pb ions in water. The sensor required only 30 s and a 100 µL sample to detect Pb. To date, this is the most rapid detection of Pb performed using an all-Cu-based sensor. The selectivity test of Cu to Pb with interferences from cadmium and zinc showed that their peaks were separated by a few hundred millivolts. This approach has strong potential towards realizing low-cost, highly reliable integrated water quality monitoring systems. Full article

The high-quality and controllable preparation of molybdenum nitrides (Mo_xN_y) will significantly advance the fields of heterogeneous catalysis, energy storage, and superconductivity. However, the complex structure of Mo_xN_y, which contains multiple phases, makes exploring the structure-property relationship challenging. The selective preparation of Mo_xN_y with distinct phases is undoubtedly an effective method for addressing this issue, but it is lacking experimental cases and theoretical reports. Here we demonstrate a feasible chemical vapor deposition (CVD) strategy for selectively producing γ-Mo₂N or δ-MoN through modulating the mass quantity of N precursors. A liquid Cu-Mo alloy was used as a Mo precursor and catalyst in this system. The resulting γ-Mo₂N was systematically characterized and found to be of high quality. Furthermore, the morphology evolutions of γ-Mo₂N and δ-MoN with growth time were summarized in detail, as a result of growth and etching dynamics. This work promotes the phase modulation of Mo_xN_y and provides a framework for future research on the structure-property relationship. Full article

Molten fluorides of alkali metals are considered a technological medium for molten salt reactors (MSRs). However, these media are known to be extremely corrosive. The successful implementation of high-temperature technological devices using molten alkali metal fluorides requires the selection of such structural materials that have high corrosion resistance in melts with compositional characteristic of MSRs. In this research, the corrosion behavior of 12Cr18Ni10Ti steel, the alloy Ni60Cr20Mo15, and the alloy Monel 404 (Ni50Cu50) was investigated in the LiF–NaF–KF eutectic melt, containing additions of CeF₃ and NdF₃ from 0 to 5 wt.% as imitator fluorides of actinides in an inert argon atmosphere at 550 °C for 100 h. Gravimetry, energy-dispersive X-ray (EDX) microanalysis of surfaces and cross-section of samples, and ICP-MS were used to establish the corrosion behavior of the investigated alloys. Corrosion resistance of the studied materials was found to decrease in a row from Monel 404 > Hastelloy C2000 > 12Cr18Ni10Ti. The addition of cerium fluoride into the melt resulted in the additional etching of the alloy surface. The addition of neodymium fluoride resulted in the formation of the point/inter-crystalline corrosion damages in the sample bulk. The samples of steel 12Cr18Ni10Ti were subjected to local cracking corrosion. The austenitic nickel-based alloys suffered specific local corrosion with formation of subsurface voids. Excellent corrosion resistance of the Monel alloy under the test conditions was found. Full article

The electrical performance of the back-channel etched Indium–Gallium–Zinc–Oxide (IGZO) thin-film transistors (TFTs) with copper (Cu) source and drain (S/D) which are patterned by a selective etchant was investigated. The Cu S/D were fabricated on a molybdenum (Mo) layer to prevent the Cu diffusion to the active layer (IGZO). We deposited the Cu layer using thermal evaporation and performed the selective wet etching of Cu using a non-acidic special etchant without damaging the IGZO active layer. We fabricated the IGZO TFTs and compared the performance in terms of linear and saturation region mobility, threshold voltage and ON current (I_ON). The IGZO TFTs with Mo/Cu S/D exhibit good electrical properties, as the linear region mobility is 12.3 cm²/V-s, saturation region mobility is 11 cm²/V-s, threshold voltage is 1.2 V and I_ON is 3.16 × 10⁻⁶ A. We patterned all the layers by a photolithography process. Finally, we introduced a SiO₂-ESL layer to protect the device from external influence. The results show that the prevention of Cu and the introduced ESL layer enhances the electrical properties of IGZO TFTs. Full article

Patterning of thin films with lithography techniques for making semiconductor devices has been facing increasing difficulties with feature sizes shrinking to the sub-10 nm range, and alternatives have been actively sought from area-selective thin film deposition processes. Here, an entirely new method is introduced to self-aligned thin-film patterning: area-selective gas-phase etching of polymers. The etching reactions are selective to the materials underneath the polymers. Either O₂ or H₂ can be used as an etchant gas. After diffusing through the polymer film to the catalytic surfaces, the etchant gas molecules are dissociated into their respective atoms, which then readily react with the polymer, etching it away. On noncatalytic surfaces, the polymer film remains. For example, polyimide and poly(methyl methacrylate) (PMMA) were selectively oxidatively removed at 300 °C from Pt and Ru, while on SiO₂ they stayed. CeO₂ also showed a clear catalytic effect for the oxidative removal of PMMA. In H₂, the most active surfaces catalysing the hydrogenolysis of PMMA were Cu and Ti. The area-selective etching of polyimide from Pt was followed by area-selective atomic layer deposition of iridium using the patterned polymer as a growth-inhibiting layer on SiO₂, eventually resulting in dual side-by-side self-aligned formation of metal-on-metal and insulator (polymer)-on-insulator. This demonstrates that when innovatively combined with area-selective thin film deposition and, for example, lift-off patterning processes, self-aligned etching processes will open entirely new possibilities for the fabrication of the most advanced and challenging semiconductor devices. Full article

Advancements in production techniques in PCB manufacturing industries are still required as compared to silicon-ICs fabrications. One of the concerned areas in PCBs fabrication is the use of conventional methodologies for metallization. Most of the manufacturers are still using the traditional Copper (Cu) laminates on the base substrate and patterning the structures using lithography processes. As a result, significant amounts of metallic parts are etched away during any mass production process, causing unnecessary disposables leading to pollution. In this work, a new approach for Cu metallization is demonstrated with considerable step-reducing pattern-transfer mechanism. In the fabrication steps, a seed layer of covalent bonded metallization (CBM) chemistry on top of a dielectric epoxy resin is polymerized using actinic radiation intensity of a 375 nm UV laser source. The proposed method is capable of patterning any desirable geometries using the above-mentioned surface modification followed by metallization. To metallize the patterns, a proprietary electroless bath has been used. The metallic layer grows only on the selective polymer-activated locations and thus is called selective metallization. The highlight of this production technique is its occurrence at a low temperature (20–45 °C). In this paper, FR-4 as a base substrate and polyurethane (PU) as epoxy resin were used to achieve various geometries, useful in electronics packaging. In addition, analysis of the process parameters and some challenges witnessed during the process development are also outlined. As a use case, a planar inductor is fabricated to demonstrate the application of the proposed technique. Full article

We present a novel method of surface processing of complex polymer-metal composite substrates. Atmospheric-pressure plasma etching in pure H₂, N₂, H₂/N₂ and air plasmas was used to fabricate flexible transparent composite poly(methyl methacrylate) (PMMA)-based polymer film/Ag-coated Cu metal wire mesh substrates with conductive connection sites by the selective removal of the thin (~10–100 nm) surface PMMA layer. To mimic large-area roll-to-roll processing, we used an advanced alumina-based concavely curved electrode generating a thin and high-power density cold plasma layer by the diffuse coplanar surface barrier discharge. A short 1 s exposure to pure hydrogen plasma, led to successful highly-selective etching of the surface PMMA film without any destruction of the Ag-coated Cu metal wires embedded in the PMMA polymer. On the other hand, the use of ambient air, pure nitrogen and H₂/N₂ plasmas resulted in undesired degradation both of the polymer and the metal wires surfaces. Since it was found that the etching efficiency strongly depends on the process parameters, such as treatment time and the distance from the electrode surface, we studied the effect and performance of these parameters. Full article