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Electrodeposited tin is a crucial corrosion-resistant metal to protect electronic interconnection and copper circuits in the manufacturing process of electronic products. The corrosion-resistant properties of electrodeposited tin can be improved with the addition of additives in electrodeposition. Three benzaldehyde derivatives including vanillin, ethyl vanillin, and veratraldehyde as brighteners were investigated for tin electrodeposition. Computational and experimental analyses were conducted to investigate the relationship between coating properties and the chemical factors including the molecular structure, adsorption process, and electrochemical behavior of the brighteners. The computational work demonstrated that all three brighteners could hold high reactivity and spontaneously absorb on the tin surface. The results of linear sweep voltammetry tests (LSV) illustrated that all three brighteners effectively increased the cathode polarization but ethyl vanillin exhibited the best inhibiting performance in the tin deposition. Besides, the adsorption behavior of brighteners on the tin layer also affected the grain morphology and preferred growth orientation of the crystal surface. The corrosion rate and side erosion results both indicated that ethyl vanillin could benefit to form a tin coating with good corrosion performance to meet the requirement of copper circuit fabrication of printed circuit board.

Purpose The purpose of this paper is to establish an accurate model to quantify the effect of conductor roughness on insertion loss (IL) and provide improved measurements and suggestions for manufacturing good conductive copper lines of printed circuit board. Design/methodology/approach To practically investigates the modified model of conductor roughness, three different kinds of alternate oxidation treatments were used to provide transmission lines with different roughness. The IL results were measured by a vector net analyzer for comparisons with the modified model results. Findings An accurate model, with only a 1.8% deviation on average from the measured values, is established. Compared with other models, the modified model is more reliable in industrial manufacturing. Originality/value This paper introduces the influence of tiny roughness structures on IL. Besides, this paper discusses the effect of current distribution on IL.

Polyvinylpyrrolidone (PVP) is studied in this paper as an inhibitor of cobalt electrodeposition. The suppression effect of PVP was analyzed through electrochemical methods, including cyclic voltammetry (CV) and galvanostatic measurements (GM) tests. It is indicated that PVP effectively suppresses the electrodeposition of cobalt and chloride ion accelerates this suppression. Further experiments verify that PVP inhibits the deposition of cobalt through the adsorption on the electrode surface. Quantum chemical calculations were employed to calculate the molecular orbitals of PVP and the electrostatic potential (ESP) energy of the involved molecules. The simulation results imply that the amide group acts as the main electrophilic attack region and facilitates nucleophilic reactions to bond with cobalt. High aspect ratio trench filling on silicon wafer was achieved with the addition of PVP, which confirms that PVP is an applicable inhibitor for the practical electrodeposition of cobalt filling. The mechanism of cobalt trench filling was proposed to explain the role of PVP in the electroplating filling. Besides, crystalline and morphological characterizations reveal that PVP is able to inhibit the specific crystal growth of cobalt, especially the growth of 220 crystal plane, affect the crystal morphology of cobalt and improve surface compactness.

A novel additive system comprising bis-(sodium sulfopropyl)-disulfide, polyethylene glycol and hydroquinone (HQ) was developed and investigated to achieve high rate copper electrodeposition at high temperature. HQ, as the key additive compound in this system, refines the Cu grain, makes the coating surface bright and smooth at high current density. The underlying mechanism of the additive-assisted electroplating was investigated through electrochemical, morphological characterizations and molecular dynamics simulation. Nanocubical copper particles were found through chronoamperometry tests, which explains the fine crystalline Cu grains and the bright coating surface. Additionally, the formation of the nanocubical copper particles is caused by the different adsorption energies of HQ on (311), (111) and (220) crystal faces and further leads to a strong suppression on the (220) orient crystal faces. Moreover, the electroplating results of through-holes illustrate the feasibility of this additive system in practical applications.

Archaeobotanical studies tend to concentrate on the evidence for specialised agricultural food production, with less attention directed towards the use of plant foods within hunter-gatherer contexts. Here, the authors present evidence for the exploitation of Canarium nuts from four late hunter-gatherer sites in southern China. Canarium nuts contributed to the inhabitants’ diets from as early as 9000 cal BP. They also identify new uses of Canarium, c. 4500–4400 cal BP, as ritual offerings in the context of the introduction of rice and millet farming. The results are examined in the context of Canarium use across the wider Asia-Pacific region.

Copper oxide (CuO) particles with loose agglomeration of porous flakes were treated by ultrasound in different solvents. CuO particles with completely discrete flakes were obtained with ultrasonic surface treatment in ethyl alcohol as a polar solvent while CuO particles with compacted flake agglomeration were found after ultrasonic treatment in diethyl ether as a non-polar solvent. CuO particles after ultrasonic treatment were characterized to investigate the effects of morphological appearance on size distribution, sedimentation velocity, specific surface area, ultraviolet-visible (UV–vis) absorption spectra, diffraction angle of X-ray diffraction (XRD) pattern, binding energy of X-ray photoelectron spectroscopy (XPS), Raman intensity and dissolution rate. CuO particles with completely discrete flakes exhibited a fastest dissolution rate of 7 s in 12.5 vol% H2SO4 for rapid complement of cupric ions so that the electrolyte for copper electrodepositon could meet the requirement of stable concentration of cupric ions to generate fine copper deposits in a plating system with insoluble anode.

Microstrip copper lines play an important role in high-speed printed circuit boards. It is necessary to perform appropriate surface finishing on the microstrip copper lines to avoid oxidation and reduce the loss of signal transmission. In this work, the microstrip copper lines after micro etching treatment were finished with immersion silver, immersion tin and electroless nickel immersion gold (ENIG), respectively. Surface microstructures, 3D features and surface contact angle were examined to find the effect of the copper finishing on signal transmission loss. The results indicated that the microstrip copper lines with micro-etching treatment exhibits low signal transmission loss as − 39.9 dB/m at 20 GHz. The tested microstrip copper lines showed that signal transmission loss follows an increasing trend successively with micro etching treatment, immersion silver treatment, immersion tin treatment and ENIG treatment.

Since the 19th century, leadership has always been a topic of common concern in the theoretical and practical circles. During this period, a large number of leadership theories have emerged, all of which have analyzed leadership from different perspectives. From the perspective of relationship management, this paper proposes the 5M model of leadership, which divides leadership into five dimensions: managing oneself, managing superiors, managing subordinates, managing colleagues, and managing external partners. Especially in the management of external partners, the 6P principles are proposed. This article provides guidance for holistic cognitive leadership theory, points out the importance of managing external partners and organizational leadership, and provides new perspectives for future leadership research and management practice.

Optoplasmonic materials comprising both photonic and plasmonic elements are of particular interest for the development of substrates for surface-enhanced Raman spectroscopy (SERS). In this work, a layer of analyte-carrying dielectric nano/microspheres is placed on top of a monolayer of gold nanoparticles to enhance the intensity of the electric (E-) field localization and to enrich the analyte close to the electromagnetic hot spots. Numerical simulations of the hybrid structure confirm an increased and spatially expanded E-field enhancement at the interface. Due to a decreasing filling fraction with increasing size of the dielectric spheres, simulations predict a saturated SERS enhancement for dielectric microspheres with a diameter larger than 4 μm, which is confirmed by experimental SERS measurements. The dielectric microsphere can be functionalized with surface ligands that facilitate the binding of target molecules in solution. The deposition of the analyte-loaded microspheres on the self-assembled gold nanoparticle ensures a high local concentration of analytes in the electromagnetic "hot" surface. The performance of the optoplasmonic SERS approach for detecting methamphetamine in saliva and urine is tested, and the detection of analytes at nanomolar (nM) concentrations is demonstrated.

The surface roughening process of substrates plays a critical role in the pre-treatment of industrial metal deposition. In this work, five different coarsening treatments were applied to coarsen the surface of carbon fiber/cyanate ester composite for improving the quality of subsequent electroless copper plating. The particular effects of coarsening treatments on carbon fiber/cyanate ester are characterized with morphological, chemical and surface tension-based measurements. The results show that coarsening treatments lead to different surface hydrophilicity and morphology for the composites, thus affecting the adhesion, surface roughness and surface morphology of the deposited copper layer. Compared with the other tested coarsening treatments (including sand-grinding, oxidation, air plasma, the combined action involving sand-grinding and air plasma), the combined action involving sand-grinding and oxidation yields the promoted coarsening of the composite and then results in optimized adhesion for the following electroless copper plating as conductive patterns.

Polyethylene glycol (PEG) is widely used in copper plating as an inhibitor. The PEG-Cu+-Cl structure is recognized as the dominant factor in the inhibition mechanism of PEG. In this work, we investigated the influence of temperature on the PEG-Cl inhibition system. Molecular dynamic (MD) simulations based on Density Functional Theory (DFT) were employed to examine the influence of temperature on the adsorption of Cl− on copper surface and the structure of PEG-Cu+-Cl. According to the MD results, it is assumed that there is a negative correlation between the inhibition effect of PEG and the working temperature. The results of corresponding electrochemical measurements are in good agreement with this assumption and the surface morphology analysis of plated copper films confirms this correlation.

In this work, air plasma was employed to modify the surface of epoxy resin substrate for subsequent electroless copper plating. The influence of plasma modification on the interface performance of epoxy resin substrate was analyzed by multiple characterizations including morphological, chemical and surface tension-based measurements. The results show that the wettability and roughness of epoxy resin substrate are substantially increased after air plasma modification. The roughened shape and the oxidized chemical groups at surface are the major causes of modified interface properties of epoxy resin substrate. Subsequent electroless copper plating tests demonstrate that this air plasma treatment significantly improves the quality of copper deposition for printed circuit board manufacture.

The micron-size anisotropic growth of electroless nickel‑phosphorus plating was realized on the fine sliver lines with the width of ≤15 μm. Growth of nickel‑phosphorus alloy occurred preferentially in the width direction at a growth rate approximately twice than that in the thickness direction during electroless plating in a bath with periodical positive and negative rotation. The growth rate in the width direction reaches 15–18 μm in 30 min. The dominant nickel‑phosphorus growth in the width direction is attributed to the enhancement of mass transfer rate for solution at the edge of silver lines or nickel‑phosphorus layer, as a result of the better wettability of ceramic than Pd-activated silver and nickel‑phosphorus layer. The suppression of lead acetate at the layer edge is enhanced by nonlinear diffusion instead of wettability difference. A possible mechanism for the formation of nickel‑phosphorus layer morphology as functions of mass transfer and lead distribution was proposed to explain the growth behavior of anisotropic electroless nickel‑phosphorus plating. Furthermore, this anisotropic electroless nickel‑phosphorus plating process was employed to form a novel L-shape terminal electrode structure of chip inductor.

In an orthotopic model of metastatic colon carcinoma established in the liver of mice, we have previously shown that the natural killer (NK) cells were the major effectors after intratumoral delivery of a recombinant adenovirus expressing the murine IL-12 gene. However, tumor cure and long-term survival were achieved only in a minority of animals. In the present study, we generated an effective antitumoral CD8(+ ) T-cell response by the combination of IL-12 gene therapy and systemic delivery of an agonistic monoclonal antibody against 4-1BB, a costimulatory molecule expressed on activated T cells. In the IL-12 plus anti-4-1BB combination treatment, the effective dose of IL-12 could even be reduced even up to 18-fold and still achieved a better efficacy than the maximal dose of either treatment alone. We further demonstrate that the innate and the adaptive antitumoral immune responses were synergistic, as animals bearing hepatic as well as multiple pulmonary metastases were quantitatively cured of their diseases after IL-12 gene therapy + anti-4-1BB combination treatment. Both NK and CD8(+) T cells were necessary in maintaining the long-term antitumor immunity, as depletion of either cell type in the cured animals abolished their abilities to reject tumor cells implanted at distal sites. These results indicate that synergism between innate and adaptive immune responses may be effectively exploited to treat patients with metastatic diseases.