To reinforce the reliability issue brought by excessive interfacial reaction with the dimensional scale-down of electronic device, an electroless Ni–P–ZrO2 (17.5 at.% of P) composite coating was developed as the under bump metallization (UBM) for lead-free solder interconnect. ZrO2 nanoparticles were proved to be homogeneously distributed and helped improve wetting ability of the layer. Both Sn–3.5Ag/Ni–P–ZrO2 and Sn–3.5Ag/Ni–P solder joints were prepared and aged at various conditions to study the interfacial reaction. Growth of intermetallic compounds (IMCs) without serious spalling in solder/Ni–P–ZrO2 joint was slowed down because of the barrier property of incorporation of ZrO2 nanoparticles, which blocked the diffusion of Ni and Cu atoms. Based on the IMC growth, the activation energy of solder/Ni–P–ZrO2 was estimated to be higher than that of plain solder joint. The top-view of IMCs demonstrated a much finer grain size compared with that of solder/Ni–P joint. A reactive diffusion-induced compound formation mechanism was proposed to address the microstructural evolution in detail. Moreover, solder/Ni–P–ZrO2 joint demonstrated higher shear strength than did solder/Ni–P joint for different aging durations. The fracture surface of solder/Ni–P joint after shear test showed ductile transition failure, with big dimples and plastic deformation.

This study demonstrates a highly sensitive humidity sensor based on treated multiwalled carbon nanotube (tr-MWCNT) and hydroxyethyl cellulose (HEC) composite films. Tr-MWCNTs are obtained by mixed acid treatment to enhance their hydrophilicity and improve their dispersion in distilled water. Compared to tr-MWCNT/silicone rubber (SR) composite film, the humidity sensitivity of tr-MWCNT/HEC film is much higher than tr-MWCNT/SR film with the same film thickness. The humidity sensing mechanisms of tr-MWCNT/HEC composites are explained by electron donation model and swelling mechanism. Speaking and blowing experiments were also carried out and the results show that tr-MWCNT/HEC composite film is sensitive to both speaking and blowing; furthermore, it can distinguish the small humidity level difference between speaking and blowing. Other sensing characteristics, including response and recovery time, stability, and temperature effect, are also investigated. The high humidity sensitivity of tr-MWCNT/HEC composite film indicates that it can be an excellent humidity sensitive material.

Nanoporous carbon membranes (NCMs) were fabricated by the blends of resorcinol–formaldehyde (RF) resin and Pluronic F-127 through the processes of assembly, membrane-casting, solidification, and pyrolysis. The effect of the catalyst type (i.e., NaOH and Na2CO3) on the structure and property of precursors and their derived NCMs was investigated. The as-obtained precursors and NCMs were characterized by thermogravimetry, differential scanning calorimetry, x-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, elemental analysis, nitrogen adsorption, and gas permeation techniques. The results have shown that defect-free NCMs can be easily procured by the NaOH and Na2CO3 catalysts. In contrast, the precursor made from the Na2CO3 catalyst exhibits higher char yield than that from NaOH after pyrolysis. NaOH-based NCMs are beneficial for the separation of H2/N2 and CO2/N2 gas pairs. Na2CO3-based NCMs are more favorable for the separation of O2/N2 with an ideal selectivity of 6.29 and an O2 permeability of 3.27 Barrer.

This study presents the optical properties of layered ZnO/Al/ZnO composite thin films that are being explored for potential applications in solar cells and light emitting devices. The composite thin films are explored as alternatives to ZnO thin films. They are produced via radio frequency magnetron sputtering. The study clarifies the role of the aluminum mid-layer in a ZnO (25 nm)/Al/ZnO (25 nm) film structure. Multilayers with low resistivity ∼362 µΩ cm and average transmittances between ∼85 and 90% (in the visible region of the solar spectrum) are produced. The highest Haacke figure of merit of 4.72 × 10−3 Ω−1 was obtained in a multilayer with mid-layer Al thickness of 8 nm. The combined optical band gap energy of the multilayered films increased by ∼0.60 eV for mid-layer Al thicknesses between ∼1 and 10 nm. The observed shifts in the optical absorption edges to shorter wave lengths of the spectrum are shown to be in agreement with the Moss–Burstein effect.

Polymethylmethacrylate (PMMA) and polyimide (PI) samples are implanted by 40 keV Cu+ ions with high fluences to synthesize copper nanoparticles in shallow polymer layers. The produced metal/polymer nanocomposites are studied using atomic force and scanning electron microscopies as well as optical transmission spectroscopy. It is found that nucleation and growth of copper nanoparticles are strongly fluence-dependent as well as they are affected by the polymer properties, in particular, by radiation stability yielding different nanostructures for the implanted PI and PMMA. Shallow synthesized nanoparticles are observed to partly tower above the sample surface due to a side effect of high-fluence irradiation leading to considerable sputtering of polymers. Implantation and particle formation significantly change optical properties of both polymers reducing transmittance in the UV–visible range due to structural and compositional change as well as causing an absorption band related to localized surface plasmon resonance (LSPR) of the nanoparticles. The role of polymer type and its degradation under the implantation on LSPR is studied to optimize conditions for the formation of nanoplasmonic materials.

The effects of the different shot peening parameters on the 6061 alloy specimens' surface have been investigated. It is found that the compressive residual stresses and the surface roughness of the surface layer for all shot-peened specimens are improved greatly. The maximum stress value and the maximum roughness are obtained by the shot flow rate of 5.5 lbs/min and air pressure of 20 psi. The microstructure observation results indicate that a nanostructured layer with an average grain size below 100 nm has been created on the top surface layer of each specimen. In the top surface nanostructured layer, the microhardness is enhanced. It is resulted from the grain refinement and the strain hardening. The results of electrochemical measurements, surface corrosion morphology observation, and EDS analysis indicate that the corrosion susceptibility of the 6061 alloy could be significantly enhanced by means of the shot-peening-induced surface nanocrystallization.

The present investigation addressed the weldability of Super Ni 718 alloy and AISI 316L using gas tungsten arc (GTA) welding process using three different filler wires, such as ER2594, ERNiCrMo-4 and ERNiCrCoMo-1. Interface microstructures showed the formation of secondary phases at the heat-affected zone (HAZ) of Super Ni 718 alloy and delta ferrite colonies at the HAZ of AISI 316L. It was witnessed from the weld microstructures that the deleterious phases were suppressed or controlled while using these filler wires for joining the bimetals. Tensile results corroborated that the failure occurred at the parent metal of AISI 316L in all the cases. The presence of microvoids and dimples characterized for the ductile mode of fracture in these weldments. Charpy V-notch test results showed that the weldments using ERNiCrMo-4 filler exhibited higher impact energy. A detailed study has been made to investigate the structure–property relationships of these weldments using optical and scanning electron microscopic techniques.

Conjugated polymer films are of considerable current interest for functionalizing the surfaces of a wide variety of devices including implantable biomedical electronics. Toward these ends, copolymer films of 3,4-ethylenedioxythiophene (EDOT) with a carboxylic acid functional EDOT (EDOTacid) were electrochemically deposited and characterized as a systematic function of the EDOTacid content (0, 25, 50, 75, and 100%). Chemical surface characterization of the films confirmed the presence of both EDOT and EDOTacid units. Toluidene blue assays showed that the surface concentration of the carboxylic acid groups increased to a maximum of 2.75 nmoles/mm2, and the contact angle measurements confirmed the increased hydrophilicity of the films with increasing EDOTacid content (decreasing from 52.6 to 32.5 degrees). Cyclic voltammetry showed that the films had comparable charge storage capacities regardless of their composition. The morphology of the films varied depending on the monomer feed ratio. The addition of EDOTacid induced a transition from a nodular, porous surface to a more dense, pleated surface structure. These methods provide a facile means for synthesizing electrically active carboxylic acid functional poly(3,4-ethylenedioxythiophene) copolymer films with tunable hydrophilicity and surface morphologies.

Carbon nanotube (CNT)-reinforced aluminum composite powders were synthesized by cryogenic milling. The effects of different milling parameters and CNT contents on the structural characteristics and mechanical properties of the resulting composite powders were studied. Detailed information on powder morphology and the dispersion and structural integrity of the CNTs is crucial for many powder consolidation methods, particularly cold spray, which is increasingly utilized to fabricate metal-based nanocomposites. While all of the produced composite powders exhibited particle sizes suitable for spray applications, it was found that with increasing CNT content, the average particle size decreased and the size distribution became narrower. The dispersion of CNTs improved with milling time and helped to maintain a small Al grain size during cryogenic milling. Although extensive milling allowed for substantial grain size reduction, the process caused notable CNT degradation, leading to a deterioration of the mechanical properties of the resulting composite.

Modified MMT clay-doped PMMA composites have been prepared by solvent casting method for different weight percentages. The prepared composite films were characterized by FTIR and SEM. Also, the DC conductivity was carried out for PMMA and PMMA composite films. Among all composites, it was found that 30 wt% shows highest conductivity of 1.59 × 10−3 S/cm. The negative thermal coefficient behavior of these polymer composite films confirms that the increase in conductivity is due to the elongation of polymer chain which helps in charge transport mechanism. Dielectric study also shows that 30 wt% has the lowest dielectric constant and dielectric loss of 2.5 and 3.3, respectively, resulting in an increase in conductivity of 5 × 10−3 S/cm. The isotropic nature of 30 wt% composite film shows a high quality factor of 0.005 because of overdamping of electron at 104 Hz. Cole–cole plots show that the semi arc originated from a single point and its area decreases with filler concentration up to 30 wt% due to drop in the electrical resistance. Tensile modulus increases because of high MMT aspect ratio and distribution ratio. The 30 wt% of the composite shows high tensile strength at 55 MPa which induces 8% of strain in the PMMA–MMT clay composite films. Therefore, these composite films can be used in many sensor and solar technologies as encapsulation materials.

Operando energy-dispersive x-ray diffraction (EDXRD) was carried out on a newly formed 8 Ah lithium iron phosphate (LiFePO4) battery with the goal of elucidating the origin of asynchronous phase transformation commonly seen with in situ x-ray diffraction studies. The high-energy photons at the NSLS X17B1 beamline allow for penetration into a fully assembled battery and therefore negate any need for a specially designed in situ cell which often uses modified current collectors to minimize x-ray attenuation. Spatially-and-temporally resolved phase-mapping was conducted with a semiquantitative reference intensity ratio (RIR) analysis to estimate the relative abundance of the delithiated phase. The data show an asynchronous response in the stoichiometry versus the electrochemical profile and suggest limited diffusion in the electrode toward the end of discharge. Our results confirm that the asynchronous electrode response is not just limited to specially designed cells but occurs in fully assembled cells alike. We attribute this behavior to be a consequence of performing a local measurement over a wide-area heterogeneous reaction.

Creep and electromigration (EM) have been two reliability concerns in microelectronic devices for a long time. The related failure mechanisms have been widely investigated and comprehended individually. However, there is a lack of attention with regard to the interaction(s) between current density and creep, the coupling effect of which is more analogous to the real service conditions of lead-free solder joint. In this study, a series of experiments were carried out on the simple shear lap joint to investigate the effects of current density magnitude on the creep behavior of solder joints. The results indicated that dislocation creep was the main failure mechanism for low current density sample. For high current density sample, the failure mechanism was mainly dominated by copper atom migrating process which led the joint experience a higher risk of brittle fracture failure.