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The replacement of gold bonding wire with silver bonding wire can significantly reduce the cost of wire bonding. This paper provides a comprehensive overview of silver wire bonding technology. Firstly, it introduces various types of silver-based bonding wire currently being studied by researchers, including pure silver wire, alloy silver wire, and coated silver wire, and describes their respective characteristics and development statuses. Secondly, the development of silver-based bonding wire in manufacturing and bonding processes is analyzed, including common silver wire manufacturing processes and their impact on silver wire performance, as well as the impact of bonding parameters on silver wire bonding quality and reliability. Subsequently, the reliability of silver wire bonding is discussed, with a focus on analyzing the effects of corrosion, electromigration, and intermetallic compounds on bonding reliability, including the causes and forms of chlorination and sulfurization, the mechanism and path of electromigration, the formation and evolution of intermetallic compounds, and evaluating their impact on bonding strength and reliability. Finally, the development status of silver wire bonding technology is summarized and future research directions for silver wire are proposed. [ABSTRACT FROM AUTHOR]

Aiming to resolve the practical problem of brown rice kernels being easily broken due to overprocessing during processing (milling and polishing), brown rice kernels of Japonica rice, after hulling, were used as the research object in this study. Firstly, through a texture meter test, the discrete element bonding parameters (Kn is normal stiffness per unit area, Kτ is tangential stiffness per unit area, Cn is critical normal stiffness, Cτ is critical shear stiffness) were obtained. Secondly, a brown rice kernels' bonding particle model was established by EDEM, and then a second orthogonal rotational combination test was carried out to calibrate the discrete bonding parameters, Kn = 4.43 × 1012 N/m3, Kτ = 6.13 × 1011 N/m3, Cn = 2.55 × 107 Pa, and Cτ = 7.92 × 107 Pa. The error of parameter calibration was within 5%, and the results were able to reflect the actual situation more realistically. Finally, analysis of the crushing process of brown rice kernels showed that their ability to withstand shear damage was not as great as their pressure-bearing capacity. The design of the relevant mechanism and the setting of parameters should be based on the critical shear stiffness of brown rice kernels, and the actual shear force Fτ* set during the processing should be smaller than the theoretical critical shear force Fτ (Fτ* < Fτ = 9.11 N). This study can provide a theoretical basis for optimizing the key structure and operating parameters of rice milling machines and polishing machines to effectively solve the practical problem of increased crushing of brown rice kernels due to overprocessing. [ABSTRACT FROM AUTHOR]

There will be great damage in the process of harvesting, transporting, and storing after grain matures. The injury rate is as high as 8% to 12%. After damage, the germination rate of the grain becomes lower, the quality decreases, and it is easily infected with pests and molds. This study of the grain-crushing characteristics is of great significance to ensure grain quality, and an accurate crushing model is a prerequisite for effectively simulating crushing characteristics. This paper studies the shattering characteristics of wheat grains. Two-dimensional slices of wheat grain were obtained using X-ray tomography technology. Then, an accurate three-dimensional outer contour model of the wheat particle was constructed using image filtering and segmentation algorithms. The particle filling process was conducted using EDEM 2018 software to establish a wheat particle simulation model based on the Hertz–Mindlin with a Bonding contact model. Using the DOE experimental design method, single-factor experiments, Plackett–Burman experiments, steepest-climb experiments, and Box–Behnken were designed to study the fragmentation characteristics of wheat particles combined with parameter calibration and physical experiments. The test results show that the normal stiffness per unit area is 7.392 × 1010 N/m3, critical normal stress is 5.293 × 106 Pa, critical tangential stress is 5.001 × 106 Pa, and the relative error about 3%, which verifies the reliability of the simulation parameters in the discrete-element crushing model of wheat grain. This study focuses on two essential aspects: 1. establishing an accurate wheat-grain contour model; and 2. calibrating the bonding parameters of the discrete-element simulation model of wheat grain. The wheat grain discrete-element crushing model and the calibration of its bonding parameters are constructed to provide a foundation for the study of wheat-grain crushing characteristics. It is of great significance to study the situation of wheat grains and where cracks are produced. In this paper, an accurate model of the wheat-grain contour is established, and the bonding parameters of the discrete-element simulation model of the wheat grain are calibrated. The calibration of the model of the discrete elements of wheat-grain fragmentation and its bonding parameters will provide a basis for studying the crushing characteristics of wheat grain. Understanding the condition of wheat grains and the causes of cracks carries significant academic significance. [ABSTRACT FROM AUTHOR]

Owing to the complicated process of using the discrete element method (DEM) to simulate the interaction between straw and machinery, existing straw models do not exhibit failure properties. This affects simulation accuracy because some of the interaction processes are not being simulated. To solve these problems, a mechanical model of wheat straw with failure characteristics was developed based on the Hertz–Mindlin (no-slip) contact model and bonded-particle model (BPM). In this model, two types of bonding keys with different bonding parameters were used to bond straw stems. The bonding parameters of the straw model were calibrated using tension, compression, three-point bending, and shear tests, and response surface method. By calculating and solving the regression equation of the Box–Behnken design, the bond parameters (normal and tangential stiffness per unit area, and critical normal and tangential stresses) were calibrated as Bond1 and Bond2. The model can simulate the breaking, fracture, flexural, and shear behaviours of straw during tension, compression, bending, and shearing. The simulated tensile strength, compressive strength, modulus of elasticity, and shear strength of the model were 9.84%, 1.99%, 10.21% and 15.57% different from their respective experimental average values. The results show that the straw model can accurately reflect the mechanical properties of wheat straw with failure properties, which not only helps to improve the accuracy of straw simulation but also provides a reference for modelling the interaction between straw, or other crops, and mechanical equipment. • An innovative mechanical model of wheat straw with destructibility was constructed. • Two bonding keys with different parameters were newly used to bond the straw unit. • Bonding parameters were calibrated by tension, compression, bending and shear tests. • Tensile, compressive and shear strength, and modulus of elasticity were verified. • Model can reflect the mechanical properties while having destructive properties. [ABSTRACT FROM AUTHOR]

The effect of modifiers on the optical features and radiation defying ability of the Eu3+ ions doped multi constituent glasses was examined. XRD has established the amorphous nature of the specimen. The presence of various functional/fundamental groups in the present glasses was analyzed through FTIR spectra. The physical, structural and elastic traits of the glasses were explored. The variation in the structural compactness of the glass structure according to the incorporated modifier was enlightened to describe their suitability for a better shielding media. For the examined glasses, the metallization criterion value varied in the range 0.613–0.692, indicating the non-metallic character of the glasses with possible nonlinear optical applications. The computed elastic moduli expose the Li-containing glass (BTLi:Eu) to be tightly packed and rigid, which is a requirement for a better shielding channel. Furthermore, the optical bandgap and the Urbach energy values are calculated based on the optical absorption spectra. The evaluated bonding parameters revealed the nature of the fabricated glasses covalent. In addition, we investigated the radiation attenuation attributes of the prepared Eu3+ ions doped multi constituent glasses using Phy-X software. We determined the linear attenuation coefficient (LAC) and reported the influence of the five oxides Li2O3, CaO, BaO, SrO, and ZnO on the LAC values. The LAC varied between 0.433 and 0.549 cm−1 at 0.284 MeV. The 39B2O3−25TeO2−15Li2O3−10Na2O−10K2O −1Eu2O3 glass has a much smaller LAC than the other glasses.

The replacement of gold bonding wire with silver bonding wire can significantly reduce the cost of wire bonding. This paper provides a comprehensive overview of silver wire bonding technology. Firstly, it introduces various types of silver-based bonding wire currently being studied by researchers, including pure silver wire, alloy silver wire, and coated silver wire, and describes their respective characteristics and development statuses. Secondly, the development of silver-based bonding wire in manufacturing and bonding processes is analyzed, including common silver wire manufacturing processes and their impact on silver wire performance, as well as the impact of bonding parameters on silver wire bonding quality and reliability. Subsequently, the reliability of silver wire bonding is discussed, with a focus on analyzing the effects of corrosion, electromigration, and intermetallic compounds on bonding reliability, including the causes and forms of chlorination and sulfurization, the mechanism and path of electromigration, the formation and evolution of intermetallic compounds, and evaluating their impact on bonding strength and reliability. Finally, the development status of silver wire bonding technology is summarized and future research directions for silver wire are proposed.

There will be great damage in the process of harvesting, transporting, and storing after grain matures. The injury rate is as high as 8% to 12%. After damage, the germination rate of the grain becomes lower, the quality decreases, and it is easily infected with pests and molds. This study of the grain-crushing characteristics is of great significance to ensure grain quality, and an accurate crushing model is a prerequisite for effectively simulating crushing characteristics. This paper studies the shattering characteristics of wheat grains. Two-dimensional slices of wheat grain were obtained using X-ray tomography technology. Then, an accurate three-dimensional outer contour model of the wheat particle was constructed using image filtering and segmentation algorithms. The particle filling process was conducted using EDEM 2018 software to establish a wheat particle simulation model based on the Hertz–Mindlin with a Bonding contact model. Using the DOE experimental design method, single-factor experiments, Plackett–Burman experiments, steepest-climb experiments, and Box–Behnken were designed to study the fragmentation characteristics of wheat particles combined with parameter calibration and physical experiments. The test results show that the normal stiffness per unit area is 7.392 × 1010 N/m3, critical normal stress is 5.293 × 106 Pa, critical tangential stress is 5.001 × 106 Pa, and the relative error about 3%, which verifies the reliability of the simulation parameters in the discrete-element crushing model of wheat grain. This study focuses on two essential aspects: 1. establishing an accurate wheat-grain contour model; and 2. calibrating the bonding parameters of the discrete-element simulation model of wheat grain. The wheat grain discrete-element crushing model and the calibration of its bonding parameters are constructed to provide a foundation for the study of wheat-grain crushing characteristics. It is of great significance to study the situation of wheat grains and where cracks are produced. In this paper, an accurate model of the wheat-grain contour is established, and the bonding parameters of the discrete-element simulation model of the wheat grain are calibrated. The calibration of the model of the discrete elements of wheat-grain fragmentation and its bonding parameters will provide a basis for studying the crushing characteristics of wheat grain. Understanding the condition of wheat grains and the causes of cracks carries significant academic significance.

We report on the Sm3+ and Sm3+:Yb3+-doped barium fluorotellurite glasses prepared using the conventional melting and quenching method. The spectroscopic characterisations were investigated with Raman and FTIR to evaluate the glasses' structural and hydroxyl (-OH) content. The Raman analysis revealed a structural modification in the glass network upon adding and increasing the Yb3+ concentration from a TeO3 trigonal pyramid to a TeO4 trigonal bi-pyramid polyhedral. At the same time, the FTIR measurements showed the existence of -OH groups in the glass. Thus, under the current experimental conditions and nominal composition, the -OH group contents are too large to enable an effective removal. The near-infrared region of the absorption spectra is employed to determine the nephelauxetic ratio and bonding parameters. The average nephelauxetic ratio decreases, and the bonding parameter increases with the increasing Yb3+ content in the glasses. A room temperature visible and near-infrared photoluminescence ranging from 500 to 1500 nm in wavelength and decay properties were investigated for glasses doped with Sm3+ and Sm3+-Yb3+ by exciting them with 450 and 980 nm laser sources. Exciting the Sm3+- and Sm3+-Yb3+-doped glasses by 450 nm excitation reveals a new series of photoluminescence emissions at 1200, 1293, and 1418 nm, corresponding to the 6F11/2 state to the 6HJ (J = 7/2, 9/2, 11/2) transitions. Under the 976 nm laser excitation, a broad photoluminescence emission from 980 to 1200 nm was detected. A decay lifetime decreased from ~244 to ~43 μs by increasing the Yb3+ content, ascribing to concentration quenching and the OH content. [ABSTRACT FROM AUTHOR]

Oxyfluoride (P2O5-Bi2O3-Na2CO3-SrCO3-ZnF2-Eu2O3) glasses of different dopant (Eu3+) ion concentrations were synthesized by the traditional melt quenching method. Optical absorption, luminescence and lifetime measurements were performed with UV-Vis and PL techniques. A total of six absorption bands were observed in the wavelength range 200-800 nm, including one intense high band at 392 nm was assigned to 7F0→5L6 transition. The covalency between the host environment and Eu3+ ion was noticed with the measured nephelauxetic ratios (β) and bonding parameters (δ). The energies of the energy band gaps (Eg) and Urbach (ΔE) were estimated from the Tauc's plots, drawn from the absorption spectra. Luminescence spectra exhibited the prominent reddish-orange emission at 612 nm due to the 5D0→7F2 characteristic transition of Eu3+ ion. The lasing (radiative) parameters of f-f transitions of the Eu3+ ion was evaluated using the Judd-Ofelt intensity parameters (Ω2, Ω4, and Ω6). The higher magnitude of branching ratios (βexp) suggests the suitability of the present glass. The decay profile for the 5D0 level of europium was recorded by monitoring the emission and excitation wavelengths 612 & 392 nm, respectively. The color temperature and purity were calculated using CIE 1931 color coordinates. The emission color band spectra have also been recorded. [ABSTRACT FROM AUTHOR]

We report on the Sm3+ and Sm3+:Yb3+-doped barium fluorotellurite glasses prepared using the conventional melting and quenching method. The spectroscopic characterisations were investigated with Raman and FTIR to evaluate the glasses’ structural and hydroxyl (-OH) content. The Raman analysis revealed a structural modification in the glass network upon adding and increasing the Yb3+ concentration from a TeO3 trigonal pyramid to a TeO4 trigonal bi-pyramid polyhedral. At the same time, the FTIR measurements showed the existence of -OH groups in the glass. Thus, under the current experimental conditions and nominal composition, the -OH group contents are too large to enable an effective removal. The near-infrared region of the absorption spectra is employed to determine the nephelauxetic ratio and bonding parameters. The average nephelauxetic ratio decreases, and the bonding parameter increases with the increasing Yb3+ content in the glasses. A room temperature visible and near-infrared photoluminescence ranging from 500 to 1500 nm in wavelength and decay properties were investigated for glasses doped with Sm3+ and Sm3+-Yb3+ by exciting them with 450 and 980 nm laser sources. Exciting the Sm3+- and Sm3+-Yb3+-doped glasses by 450 nm excitation reveals a new series of photoluminescence emissions at 1200, 1293, and 1418 nm, corresponding to the 6F11/2 state to the 6HJ (J = 7/2, 9/2, 11/2) transitions. Under the 976 nm laser excitation, a broad photoluminescence emission from 980 to 1200 nm was detected. A decay lifetime decreased from ~244 to ~43 μs by increasing the Yb3+ content, ascribing to concentration quenching and the OH content.

The glasses with the composition 20PbO-(10-x)CdO-10TeO -60B O -xCuO (0.5=x=2) were prepared by melt quenching technique. X-ray diffractograms revealed the amorphous nature of the glasses. Optical absorption spectra are recorded at room temperature. Optical band gap (E) and Urbach energies were determined. Electron Paramagnetic opt 2+ Resonance (EPR) studies were carried out by introducing Cu2+ as the spin probe. EPR spectra of all the glass samples were recorded at X-band (≈9.7 GHz) frequencies. From the EPR spectra spin-Hamiltonian parameters were evaluated. It -4 -1 -4 was observed that (g ≈2.360, g≈2.080) g >g >g (2.0023) and (A≈136x10 cm, A ≈30 x10-4 cm-1) A1 >A1. From these values it is concluded that the ground state of Cu2+ is (²Bfg) and the site symmetry around Cu ion was 1g tetragonally distorted in octahedral sites. It was observed that the intensity of the EPR spectra increases with increase of CuO concentration, which shows that more number of Cu ions are participating in the resonance. The optical absorption spectra revealed broad absorption band, which is assigned to transition. From the EPR and Optical 1g 2g data bonding coefficients were evaluated and discussed. [ABSTRACT FROM AUTHOR]

Abstract A glass series containing bio-silicate borotellurite (BSBT) doped with erbium oxide with composition of {[(TeO 2) 0.8 (B 2 O 3) 0.2 ] 0.8 (SiO 2) 0.2 } 1-y (Er 2 O 3) y , y = 0.01, 0.02, 0.03, 0.04, 0.05 mol fraction were fabricated using the melt quenching technique. In this glass composition, the bio-silicate was extracted from the rice husk. The X-ray fluorescence (XRF), X-ray diffraction (XRD), molar volume, density, optical absorption and luminescence properties and excitation of the glass sample were investigated. Result of x-ray diffraction (XRD) confirmed the amorphous nature of the glass. The X-ray fluorescence (XRF) verified the achievement of 98.6% of silicate from rice husk. The density is found to be increasing from 3.845 g/cm3 to 4.142 g/cm3 with the increase in the concentration of Er3+. The molar volume is also found to be increasing with concentration of Er3+, but later decreases at 0.04 and 0.05 mol fraction of erbium. The decrease may be due to the tightly packed atom giving rise to a denser glass. The obtained values of the Racah parameters are derived from the absorption spectra region with higher energy. The bonding parameters are found to increase with the increase in the concentration of Er3+ from 0.002789 to 0.002835 while the Racah parameters and nephelauxetic ratio decreased. The increase in crystal field strength also shows a strong field sites. The Judd-Ofelt (J-O) intensity parameters are derived from the UV–Vis spectra and the results showed Ω 2 > Ω 4 > Ω 6 trend with the exception of Erbium at 0.04 mol fraction which showed Ω 2 > Ω 6 > Ω 4 trend. The appearance of higher values of Ω 2 and Ω 6 indicate the presence of a stronger covalency and lower symmetry around Er3+ ions. MacCumber theory was used to determine the stimulated emission cross section from the calculated absorption cross section for 4I 13/2 to 4I 15/2 transition. The glass displayed intense green and a week red emission under 380 nm excitation. The width of the gain is found to shift towards the shorter wavelength which proves that this glass system is a good material for photonics and laser applications. [ABSTRACT FROM AUTHOR]

Abstract We investigate the influence of the ratio between carbon and boron on glass-forming ability, thermal stability and mechanical properties of the Co 65 Cr 13 Mo 22 ternary eutectic alloy modified by carbon and boron addition. Besides, the correlation between the extension of the supercooled liquid region (SCLR) and three bonding parameters, i.e. electronegativity, atomic size, and valence electron is investigated. The results reveal that carbon is more effective than boron to form a glassy phase in this system, and fully glassy alloys or metallic glass composites can be obtained when the metalloid contents are in the range of 20–25 at.%. Fully glassy alloys are only obtained when the carbon-to-boron ratio is 2:1. The glassy alloys and the glass composites exhibit high strength and extraordinarily wide SCLRs of >120 K. The width of the SCLR of the Co-based BMGs can be articulated as a function of three bonding parameters, which is different to the relationship previously observed for Fe-, Mg- and Pd-based BMGs. Based on these findings we propose the optimum C/B ratio for glass phase formation and the new criterion for predicting the width of the SCLR of Co-based BMGs by the three bonding parameters. Graphical abstract Unlabelled Image Highlights • Alloy design via adjusting ratio of carbon and boron based on the pseudo-ternary phase diagram • Unprecedentedly wide supercooled liquid regions of Co-based BMGs up to 122 K • Relationship between ΔT x and three bonding parameters • A new equation to express the ΔT x of Co-based BMGs [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Protonation changes the halogen bonding scheme in complexes N-Base:ClOH. • Traditional N⋯Cl halogen bonds become covalent N Cl bonds. • Covalent Cl O bonds become traditional Cl⋯O halogen bonds. • Proton affinity of ClOH increases dramatically in complexes N-Base:ClOH. • EOM-CCSD coupling constants show the evolution of halogen bonds upon protonation of N-Base:ClOH. Abstract Ab initio MP2/aug′-cc-pVTZ calculations demonstrate that protonation of N-Base:ClOH complexes at O leads to complexes (N-Base-Cl)+:OH 2 , as a traditional N⋯Cl halogen bond is replaced by a chlorine-transferred Cl⋯O bond. For a fixed base, the binding energies of the latter complexes are more than an order of magnitude greater than the former. As a function of the Cl N distance, EOM-CCSD Cl N coupling constants show the evolution of the traditional halogen bond in the N-Base:ClOH complexes, to a chlorine-shared halogen bond in N 2 :ClOH 2 +, to a covalent bond in (N-Base-Cl)+:OH 2. 1J(Cl N) values for these complexes resemble 1J(Cl N) for the ions (N-Base-Cl)+. [ABSTRACT FROM AUTHOR]

To simulate the bending behavior of wheat straw, a flexible straw model was developed based on the Hertz-Mindlin with bonding model using discrete element method. The proposed model was constructed by bonding straw units (filled by multi-spherical method) through parallel bonding keys. By means of a three-point bending test, single-factor sensitivity analysis and calibration of bonding parameters were performed. Results showed that elastic modulus of the flexible straw enhanced with the increase of bonded disk radius, normal stiffness per unit area and shear stiffness per unit area. The three bonding parameters were respectively calibrated to be 2.11 mm, 9.48×109 N/m³ and 4.67×109 N/m³ by solving the regression equation developed from Box-Behnken design. The simulated elastic modulus (in terms of those three calibrated parameters) exhibited 4.20% difference with the measured one. It proved that the flexible straw could accurately demonstrate bending property of the wheat straw. This would not only help to improve accuracy in simulating wheat straw, but also provide references for flexible straw modeling and parameters calibration of other crops. [ABSTRACT FROM AUTHOR]

Electron Paramagnetic Resonance (EPR) spectroscopic studies of VO 2+ ions as paramagnetic impurity in Lithium Sodium Acid Phthalate (LiNaP) single crystal have been done at room temperature on X-Band microwave frequency. The lattice parameter values are obtained for the chosen system from Single crystal X-ray diffraction study. Among the number of hyperfine lines in the EPR spectra only two sets are reported from EPR data. The principal values of g and A tensors are evaluated for the two different VO 2+ sites I and II. They possess the crystalline field around the VO 2+ as orthorhombic. Site II VO 2+ ion is identified as substitutional in place of Na 1 location and the other site I is identified as interstitial location. For both sites in LiNaP, VO 2+ are identified in octahedral coordination with tetragonal distortion as seen from the spin Hamiltonian parameter values. The ground state of vanadyl ion in the LiNaP single crystal is d xy . Using optical absorption data the octahedral and tetragonal parameters are calculated. By correlating EPR and optical data, the molecular orbital bonding parameters have been discussed for both sites. [ABSTRACT FROM AUTHOR]

The aim of this paper is to report the use of the anodic bonding technique to bond titanium alloy and two different bioactive glasses aiming the medical application of these biomaterials. Ti alloy and bioactive glasses 52S4.6 and 45S5 were successfully bonded using anodic bonding technique for range of temperature and applied potential. The effects of anodic bonding parameters over the total charge transferred and the bonding time were evaluated. The adhesion of Ti alloy and bioactive glasses was measured by shear test. Due to polishing process, titanium alloy samples shown a slightly rounding and consequently the bonding area was limited to part of the sample area. It was found the temperature and potential have effect with statistical significance over the total transferred charge and the bonding time. The results herein discussed suggest the viability of anodic bonding added to process versatility and material compatibility for the use of bioglass and Ti alloy bonded together on medical application. [ABSTRACT FROM AUTHOR]

In the present research some bonding parameters of hypersensitive transition of Pr(III) doped systems with three ligands having amide group have been done. For this research we have choose four parameters such as nephelauxetic ratio (β ), bonding parameter (b1/2), Sinha's covalency parameter (δ%) and covalency angular overlap parameter (η). From the observed data of these parameters, it concludes that in the bonding between Pr(III) ion and amide group of ligands, the involvement of 4f-orbital has very less as compared to transition metals. In the present study we have also investigated the antibacterial activity of various doped systems. This antibacterial activity is investigated against the Escherichia coli and Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

A blue colored Cu-doped lead zinc phosphate glass in the system 10 PbO-30 ZnO-59.9 PO-0.1 CuO was prepared by quenching of the melt and spectral properties of these glasses were studied. Optical absorption and electron paramagnetic resonance spectra of Cu ion in these glasses were measured. Polarization produced by uneven distribution of d-electron density on the inner core of s-electron was studied. The estimated results showed that the g > g because Cu ions had tetragonally elongated distortion. Optical absorption studies also supported the same property. The variation in crystal field caused the change in bonding nature. The Fourier transform infrared spectra had elucidated the bonding system of the constituent atoms and groups that shed light on the expected structure. Raman spectra were used to get information about the depolymerization of phosphate chains in the glasses with successive replacement of alkali content. [ABSTRACT FROM AUTHOR]

In this paper, in order to improve the reliability of anisotropic conductive film (ACF) interconnections, solder ACF joints were investigated in terms of solder joint morphology. ACFs are film-type interconnection adhesive materials that consist of polymer adhesive resins and randomly dispersed conductive particles. Recently, in order to obtain high reliability of ACF joints, solder ACFs that use solder particles as conductive particles of ACFs have been introduced combined with an ultrasonic bonding method. However, further researches are needed in the area of crack initiation and the propagation of solder ACF joints at high temperature and high humidity conditions due to the stress generated by hygroscopic expansion of ACF resin. Therefore, in order to solve the crack initiation of solder ACF joints, solder ACF joint morphology should be controlled and optimized to minimize the solder crack-related reliability problems. In this paper, solder ACF joint reliability was investigated depending on the solder morphologies of ACF joints bonded with various bonding pressures and temperatures. According to the results, as bonding pressure increased from 2 to 6 MPa, aspect ratio (joint diameter/joint gap) increased due to the increased joint area and decreased joint gap. In the pressure cooker test (PCT) reliability tests, as solder aspect ratio increased, electrical resistances were more stable after 60 h of the tests due to higher joint strength. In the target bonding temperature profile of 250 °C, solder joints showed a concave shape. However, joints bonded at in the target bonding temperature profile of 200 °C showed a convex shape. It is mainly due to the lower degree of cure of resin when ACF temperature reached to solder Melting Point (MP) in the target bonding temperature profile of 250 °C compared with that in the target bonding temperature profile of 200°, because ACF temperature reached to solder MP in shorter time in the target bonding temperature profile of 250 °C. Concave-shaped solder joints showed higher PCT reliability than the convex-shaped solder joints due to the lower stress concentration. These results indicate that solder ACF joint morphology was a significantly important factor for highly reliable solder ACF joints in high temperature and high humidity reliability conditions. [ABSTRACT FROM PUBLISHER]

A new series of Sm 3+ doped borophosphate glasses 50B 2 O 3 + 20Li 2 CO 3 + 10ZnO + 9SrCO 3 + (11 − x )P 2 O 5 + x Sm 2 O 3 ( x = 0.1, 0.25, 0.5, 1 and 2 in wt%) have been prepared by following melt quenching technique. The structural and optical properties of the prepared glasses were characterized through XRD, FTIR, absorption, luminescence and decay spectral measurements. The XRD spectrum exhibit broad diffusion at lower angles which reveal the amorphous nature and the presence of various functional groups such as P O P bonds, B O vibrations in BO 3 units and P OH and B OH bonds in the title glasses were confirmed through the FTIR spectra. The nature of the metal–ligand bonding and the electronic band structure has been investigated using the absorption spectra. The Judd–Ofelt (JO) intensity parameters ( Ω 2 , Ω 4 and Ω 6 ) were evaluated from the JO theory using the refractive index and the experimental oscillator strength values. The emission spectra exhibit four emission bands in the visible region corresponding to the 4 G 5/2 → 6 H 5/2 , 4 G 5/2 → 6 H 7/2 , 4 G 5/2 → 6 H 9/2 and 4 G 5/2 → 6 H 11/2 transitions by monitoring an excitation wavelength at 403 nm. The emission spectra have been characterized through Commission International de I’Eclairage (CIE) 1931 chromaticity diagram to explore the dominant emission from the studied glasses. The radiative parameters such as transition probability ( A R ), branching ratios ( β R ) and stimulated emission cross-section ( σ P E ) were obtained for the emission transitions using JO parameters and the results were discussed and compared with the reported literature. [ABSTRACT FROM AUTHOR]

A new series of white light emitting Dy 3+ doped Lead tellurofluoroborate glasses have been prepared and their spectroscopic and energy transfer behavior were explored through analyzing XRD, FTIR, Raman, SEM, EDAX, optical absorption, photoluminescence and lifetime measurements. The fundamental stretching of the various borate and tellurite networks were identified using FTIR and Raman spectral analysis. The bonding parameter studies reveal the ionic nature of the Dy O bond in the present glasses. The Judd–Ofelt (JO) intensity parameters determined from the absorption spectra have been used to investigate the nature of bonding and symmetry orientation of the Dy–ligand field environment. The luminescence intensity increases with increasing Dy 3+ ion concentration up to 0.5 wt%, beyond that luminescence quenching is observed. The JO parameters have been used to determine the transition probability ( A ), stimulated emission cross-section ( σ P E ), radiative lifetime ( τ R ) and branching ratios ( β R ) for the different emission transitions from the 4 F 9/2 excited level. The higher σ P E and β R values of the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions suggest the possible laser action in the visible region. The Y/B ratio, CIE chromaticity color coordinates ( x , y ) and Color correlated temperature (CCT) were also estimated from the luminescence spectra for different concentration as well as pumping wavelengths. The x , y chromaticity color coordinates fall within the white light region and the white light can be tuned by varying the excitation wavelengths. The lifetime of the 4 F 9/2 excited state were measured and is found to decrease with increasing Dy 3+ ion content. The non-exponential behavior is predominant in higher Dy 3+ ion content glasses and is due to the efficient energy transfer between Dy 3+ Dy 3+ ions. The decay curves were fitted to the Inokuti–Hirayama (IH) model to understand the nature of energy transfer. Among the prepared glasses, 0.5DPTFB glass possesses higher A , β R , σ P E , η values and is suggested for lasers and WLED applications. [ABSTRACT FROM AUTHOR]

Cu(II) ion-doped NaCaAlPO4F3 phosphor has been synthesized using a solid state reaction method. The prepared sample is characterized by powder X-ray diffraction, scanning electron microscope, optical absorption, electron paramagnetic resonance photoluminescence and Fourier transform infrared spectroscopy techniques. The crystallite size evaluated from x-ray diffraction data is in nanometers. Scanning electron microscopy micrographs showed the presence of several irregular shaped particles. From optical absorption and electron paramagnetic resonance spectral data the doped Cu(II) ions are ascribed to distorted octahedral site symmetry. The synthesized phosphor exhibits emission bands in ultraviolet, blue and green regions under the excitation wavelength of 335 nm. The CIE chromaticity coordinates (x = 0.159, y = 0.204) also calculated for the prepared sample from the emission spectrum. The Fourier transform infrared spectroscopy spectrum revealed the characteristic vibrational bands of the prepared phosphor material. [ABSTRACT FROM AUTHOR]

In the present study, an exclusive set of modifiers incorporated Dy3+ activated alkali boro-tellurite glasses is fabricated via classic melt-quenching process. The structural and molecular studies are made through XRD, FTIR and Raman analyses. The spectroscopic and radiative characteristics of the prepared glasses are explored through absorption, luminescence and decay spectral studies. The bonding nature between dopant and ligand field is analysed with the bonding parameters which detected the nature of the glasses to be ionic. The computed JO parameters trail the course Ω 2 > Ω 4 > Ω 6 consistently for all the samples that depicts their asymmetric nature. Among the three observed transitions, a strong yellow emission is detected due to the increase in population density of the 6H 13/2 level (4F 9/2 → 6H 13/2). The evaluated radiative features of the glasses prove their lasing capability. The zinc containing glass (BTZNKD) owns higher stimulated emission cross-section (σ sec) which makes it applicable for lasing actions and w−LED application in medical diagnosis. The stimulation of white light for the prepared glasses is examined through colorimetric investigations including CCT, color purity and Y/B ratio. The radiative lifetime is calculated for all the glasses through the non-exponential decay and the estimated luminescence efficiency is higher for the BTZNKD (78%) glass. In summary, the BTZNKD glass is more suitable for white light generation and lasing applications. [ABSTRACT FROM AUTHOR]

VO2+ ions doped chlorocadmiumphosphate, CdHPO4Cl·[H3N(CH2)6NH3]0.5 crystals were synthesized at room temperature by using an organic amine, Hexa Methylene Di Amine as a templating molecule. The prepared crystals were characterized by powder XRD and several spectroscopic techniques. The powder XRD data was indexed to monoclinic crystal system with the lattice parameters, a=0.429, b=0.772, c=1.622nm and β=114.3°. The nature of doped VO2+ ions in the framework material has been identified by optical absorption and electron paramagnetic resonance techniques. FT-IR spectrum exhibited the characteristic vibrations of phosphate anions and hexane diammonium cations. Thermal studies revealed that the prepared crystals withstand its state up to 307°C. EPR and optical absorption spectrum confirmed that the doped VO2+ ions entered the complex material as distorted octahedral site symmetry. The evaluated bonding parameters revealed a partial covalent bonding between the doped metal ions and ligands. [ABSTRACT FROM AUTHOR]

Thermosonic flip-chip (TSFC) bonding is a flexible and rapidly developing package technology, in which ultrasonic energy is used to reduce bonding temperature, time, and force. In this paper, a laboratory TSFC bonder with a smooth end tool and without vacuum or a die collet was developed to bond a gold bump to a silver pad in order to understand the effect of ultrasonic energy on flip-chip bonding strength. With a laser Doppler vibrometer, the ultrasonic vibration of the tool and flip chip were measured during the bonding process. In addition, the energy loss between the tool and chip was observed. The relationship between energy loss, ultrasonic propagation, bump deformation, and bonding parameters was discussed. The effects of bonding parameters on bonding strength and vibration transferred from the tool to chip were experimentally investigated. Results show that energy losses prevent over-bonding phenomenon caused by an excess of ultrasonic power. Good bonding strength can be achieved by optimizing bonding parameters using a tool without a vacuum or collet. Compared to vacuum-based or groove tools, smooth-end tools are able to automatically control the ultrasonic energy applied at the bonding interface. [ABSTRACT FROM AUTHOR]

Abstract: Structural and spectroscopic dependence of Sm3+ ions in B2O3–TeO2–ZnO–Li2O glasses were studied and reported. The presence of asymmetric stretching vibration of B–O bonds in trigonal BO3 units, Te–O bond in TeO3 (tbp) and TeO4 (tp) units and the hydroxyl groups in the prepared glasses were explored through the FTIR spectral studies. The bonding parameters (β and δ) were calculated from the absorption spectral measurements. The Judd–Ofelt intensity parameters (Ω λ , λ =2, 4, and 6) have been derived from the absorption spectra and are used to predict the radiative parameters for the excited levels 4G5/2 → 6H5/2, 4G5/2 → 6H7/2 and 4G5/2 → 6H9/2 of the Sm3+ ions. The lifetime spectra corresponding to the 4G5/2 level of the Sm3+ ion is found to be single exponential at lower concentration whereas it becomes non-exponential at higher concentration which is due to the energy transfer taking place among the neighboring Sm3+ ions. [Copyright &y& Elsevier]

Abstract: Single crystal EPR, optical, FT-IR and powder XRD studies of VO(II) ion doped diaqua(2,2′-bipyridine) malonato zinc complex were carried out at room temperature to ascertain the structural properties. In EPR, the angular variation of vanadium hyperfine lines indicated a single site, with spin Hamiltonian parameters as: gxx =1.968, gyy =1.964, gzz =1.928, Axx =7.54mT, Ayy =6.36mT and Azz =18.81mT. In addition, the dopant had entered the lattice in an interstitial position and the position had been identified with the help of atom positions of the host lattice. The EPR and optical data was corroborated to obtain various bonding parameters, from which the nature of the bonding in the complex was discussed. FT-IR and powder XRD studies were used to observe the effect of dopant on structural parameters of the host lattice. [Copyright &y& Elsevier]

Relatively little information is available on the growth patterns of gold aluminide compound in accurate 3D measurement as compared with 2D images of the projected surface. A 3D surface imaging technique by using infinite focus microscope (IFM) was proposed in this study to observe and explain the effects of bonding parameters on growth pattern of gold aluminide compound formed between a 25.48 μm 4N gold wire and an aluminum pad metallization. Two bonding factors, which were varied, were ball bonding force and ultrasonic current while bonding time and temperature were kept constant. The 3D surface measurement provides topographical and color information of the bonded region, which indicates that optimum bonding condition has a significant effect on uniform growth and wide coverage area of gold aluminide compound. Results illustrated by this technique were used as additional information to the results produce by the conventional methods such as cross section optical image and scanning electron microscope (SEM) micrographs, to gain a better understanding on the physical behavior of gold aluminide compound. [ABSTRACT FROM AUTHOR]

Abstract: Single crystal EPR studies of Mn(II) doped hexaaquazincdiaquabis(malonato) zincate [Zn(H2O)6][Zn(mal)2(H2O)2] have been carried out at room temperature using X-band spectrometer to identify the location of the dopant. Single crystal rotations along the three orthogonal axes show more than 30 line pattern EPR spectra indicating the presence of two types of dopant ions in the host lattice, with intensity ratio of 6:1. However, the latter could not be followed due to its low intensity during crystal rotations. The spin-Hamiltonian parameters, estimated from the three mutually orthogonal crystal rotations are: gxx =1.972, gyy =2.000, gzz =2.023, Axx =8.95, Ayy =9.48, Azz =9.93mT, Dxx =−34.49, Dyy =−3.26, Dzz =37.74mT and E =15.6mT. The direction cosines of one of the principal values of g match with that of Zn–O bond in the host lattice, suggesting that the Mn(II) ion entered the lattice substitutionally. The large value of E is indicative of low symmetry of the substitutional site, in accordance with the crystal structure of the isomorphous [Zn(H2O)6][Cu(mal)2(H2O)2]. Covalency of Mn–O bond, estimated from Matamura’s plot, is 9%. Various admixture coefficients, bonding and optical parameters have also been calculated. [Copyright &y& Elsevier]

Abstract: Electron paramagnetic resonance (EPR) study of Cu2+ doped bis (glycinato) Mg (II) monohydrate single crystals is carried out at room temperature. Copper enters the lattice substitutionally and is trapped at two magnetically inequivalent sites. The observed spectra are fitted to a spin-Hamiltonian of rhombic symmetry with the following values of the parameters: Cu2+ (I), g x =2.1577±0.0002, g y =2.2018±0.0002, g z =2.3259±0.0002, A x =(87±2)×10−4 cm−1, A y =(107±2)×10−4 cm−1, A z =(141±2)×10−4 cm−1; Cu 2+ (II), g x =2.1108±0.0002, g y =2.1622±0.0002, g z =2.2971±0.0002, A x =(69±2)×10−4 cm−1, A y =(117±2)×10−4 cm−1and A z =(134±2)×10−4 cm−1. The ground state wave function of the Cu2+ ion in this lattice is evaluated to be predominantly |x 2 − y 2 :italic>g-factor anisotropy is also calculated and compared with the experimental value. With the help of the optical absorption study, the nature of bonding in the complex is discussed. [Copyright &y& Elsevier]

Abstract: X-Band electron paramagnetic resonance (EPR) studies of Gd3+ ions in ammonium hydrogen malonate single crystals have been done at room temperature. Detailed EPR analysis indicates the presence of four physically equivalent but magnetically inequivalent sites. The zero-field splitting parameters and g factor are determined. The Gd3+ ion is in 8S state; its levels are split by the action of the crystalline electric field of monoclinic symmetry. The optical absorption spectra of Gd3+ ions in single crystals of ammonium hydrogen malonate are also recorded at room temperature. The energy levels of the 4f7 configuration are calculated and compared with those observed experimentally. The values of E 1=5854±11, E 2=31±0.36, E 3=592±3.3 and ζ4f=1595±25cm−1 are found to give the best over-all agreement between experimentally observed and calculated levels. [Copyright &y& Elsevier]

Abstract: Electron paramagnetic resonance (EPR) study of VO2+ doped zinc potassium phosphate hexahydrate single crystal is carried out. The angular variation of the spectra is studied in the three crystallographic planes. The principal value of spin Hamiltonian parameters g and A and the direction cosines which principal axes make with the crystallographic axes are determined. The observed values are site I: g ∥=1.9664±0.0002, g ⊥=1.9973±0.0002, A ∥=150±2×10−4, A ⊥=60±2×10−4 cm−1; site II: g ∥=1.9276±0.0002, g ⊥=1.9921±0.0002, A ∥=155±2×10−4 and A ⊥=62±2×10−4 cm−1. By comparison of direction cosines of g from EPR with the direction cosines of different bonds obtained from crystal structure data it is ascertained that the VO2+ ion occupies Zn2+ substitutional sites. The optical absorption study of the crystal at room temperature is also carried out. The bands observed in the optical absorption spectrum are attributed to d–d transitions. The EPR results together with the optical data are employed to estimate the molecular orbital (MO) coefficients. These MO coefficients (also called bonding coefficients) are further used to discuss the nature of bonding of VO2+ ion with different ligands in the crystal. [Copyright &y& Elsevier]

Abstract: The local structure around Cu2+ ion has been examined by means of electron paramagnetic resonance and optical absorption measurements in xK2O–(40−x)Na2O–50B2O3–10As2O3 (0⩽x⩽40) glasses. The site symmetry around Cu2+ ions is found to be tetragonally distorted octahedral and the ground state of Cu2+ is . The spin-Hamiltonian parameter g || goes through a minima whereas goes through a maxima around R K=0.5, showing the mixed alkali effect. The glass exhibited broad absorption band centred 12,239cm−1 corresponding to the transition 2B1g→2B2g. By correlating the EPR and optical absorption data, the molecular orbital coefficients α2 and are evaluated for the present glass system. The IR studies show that the glass system contains BO3 and BO4 units in the disordered manner. [Copyright &y& Elsevier]

Abstract: Electron paramagnetic resonance (EPR) and optical absorption studies of VO2+ doped lithium potassium sulphate single crystals are carried out at room temperature. The angular variation of the spectra is studied in the crystallographic a*b, bc and ca* plane. Vanadyl is found to have fixed orientations in the lattice and there are two magnetically inequivalent complexes in the lattice. The spin Hamiltonian parameters obtained from single crystal data for the two sites are, Site I: gxx =2.0015±0.0002, gyy =1.9835±0.0002, gzz =1.9211±0.0002, Axx =(48±2)×10−4 cm−1, Ayy =(64±2)×10−4 cm−1, Azz =(169±2)×10−4 cm−1, Site II: gxx =2.0019±0.0002, gyy =1.9796±0.0002, g zz =1.9225±0.0002, Axx =(48±2)×10−4 cm−1, Ayy =(83±2)×10−4 cm−1, Azz =(178±2)×10−4 cm−1. The first three bands observed in optical absorption spectrum are attributed to d–d transitions and the last band is probably charge transfer band. The band positions are calculated using energy expressions and compared with the observed values to confirm the transitions. Crystal field parameter (D q) and tetragonal parameters (D s and D t) are also evaluated. Using EPR and optical results, the molecular orbital parameters of VO2+ ions in the lattice are evaluated with a tetragonal symmetry approximation (because the rhombic part is small) and the nature of bonding in the complex is discussed. [Copyright &y& Elsevier]

Abstract: X-band electron paramagnetic resonance (EPR) studies of VO2+ ions in sodium citrate single crystals have been done at room temperature. Detailed EPR analysis indicates the presence of two magnetically inequivalent VO2+ sites. Both the vanadyl complexes are found to take up substitutional position. The angular variation of the EPR spectra in three planes ba*, bc and ca* are used to determine principal g and A tensors. For the two sites the spin Hamiltonian parameters are, Site I: g x =1.9680, g y =2.0053, g z =1.9124, A x =79, A y =76, A z =185; Site II: g x =1.9650, g y =2.0067, g z =1.9418, A x =78, A y =70, A z =186×10−4 cm−1. The optical absorption study is also carried out at room temperature and absorption bands are assigned to various transitions. The theoretical band positions are obtained using energy expressions and a good agreement is found with the experimental values. By correlating EPR and optical data different molecular orbital coefficients are evaluated and the nature of bonding in the crystal is discussed. [Copyright &y& Elsevier]

Abstract: EPR study of copper ions in diglycine calcium chloride tetrahydrate (DGCCT), [(NH2CH2COOH)2·CaCl2·4H2O] single crystals at room temperature is carried out. The spin Hamiltonian parameters of copper ions are determined as: g x =2.0238±0.0002, g y =2.1122±0.0002, g z =2.2250±0.0002, A x =(83±2)×10−4 cm−1, A y =(86±2)×10−4 cm−1 and A z =(118±2)×10−4 cm−1. The optical study of the single crystals at room temperature is also done and the bands are assigned to d-d and charge transfer transitions. Using above data, the nature of bonding in the complex is discussed. [Copyright &y& Elsevier]

Abstract: X-Band electron paramagnetic resonance (EPR) studies of VO2+ ions in l-asparagine monohydrate single crystals have been done at room temperature. Detailed EPR analysis indicates the presence of two magnetically inequivalent VO2+ sites. Both the vanadyl complexes are found to take up interstitial position. The angular variation of the EPR spectra in three planes ab, bc and ca are used to determine principal g and A tensors. For the two sites the spin Hamiltonian parameters are, site I: g x =1.9633, g y =2.0274, g z =1.9797, A x =88, A y =61, A z =161×10−4 cm−1; site II: g x =1.9627, g y =1.9880, g z =1.9425, A x =90, A y =66, A z =167×10−4 cm−1. The optical absorption study is also carried out at room temperature and absorption bands are assigned to various transitions. The theoretical band positions are obtained using energy expressions and a good agreement is found with the experimental values. By correlating EPR and optical data different molecular orbital coefficients are evaluated and the nature of bonding in the crystal is discussed. [Copyright &y& Elsevier]

Abstract: EPR study of Cr3+-doped ammonium lithium sulphate single crystals is carried out at room temperature. The crystal field and spin Hamiltonian parameters are evaluated from the resonance line positions of different lines observed in the EPR spectra. The spin Hamiltonian parameters are found to be g=2.0003±0.0002, D=(269±2)×10−4 cm−1 and E=(82±2)×10−4 cm−1 for site I and g=1.9904±0.0002, D=(251±2)×10−4 cm−1 and E=(79±2)×10−4 cm−1 for site II, respectively. EPR data indicate that the site symmetry of Cr3+ ion in the crystal is distorted octahedron and it enters the lattice substitutionally replacing sites and bind to the neighbouring extra Li+ vacancies necessary for charge compensation. From optical study, the energy values of different orbital levels are estimated. Further, the bonding parameters are obtained by correlating optical and EPR data and the nature of bonding in the crystal is discussed. The values of Racah parameters (B and C), crystal field parameter (Dq) and nephelauxetic parameters (h and k) are obtained to be B=908, C=3553, Dq=1974cm−1, h=0.052 and k=0.21. [Copyright &y& Elsevier]

Abstract: Studies of fine and hyperfine structures of paramagnetic resonance spectra in single crystals of Mn2+: tetramethylammoniumtetrachlorozincate are reported. As sufficient numbers of lines were not obtained at room temperature, measurements were done at liquid nitrogen temperature (77K). The Mn2+ spin Hamiltonian parameters are evaluated employing a large number of resonant line positions observed for various orientations of the external magnetic field. The values of the zero field parameters that give good fit to the observed EPR spectra are obtained. The values of different parameters are: g =1.9834±0.0002, =(105±2)×10−4 cm−1, =(100±2)×10−4 cm−1, D =(349±2)×10−4 cm−1, E =(106±2)×10−4 cm−1 and a =(21±1)×10−4 cm−1. The percentage of covalency of the metal–ligand bond has also been determined. From the optical absorption study, the lattice distortion is suggested. The observed bands are assigned as transitions from the 6A1g(S) ground state to various excited quartet levels of Mn2+ ion in a cubic crystalline field. The electron repulsion parameters (B and C) and crystal field parameters (D q and α) providing a good fit to the observed optical spectra are evaluated and the values are: B =737cm−1, C =2322cm−1, D q =670cm−1 and α =76cm−1. The considerable decrease in the values of B and C parameters from free ion values (B =960cm−1, C =3325cm−1) has indicated that there exists a fair amount of covalent bonding between the central metal ion and the ligand. On the basis of deviations Δg = g −2.0023 it has been ascertained whether electrons are transferred to or from the central ion by the action of bonding. [Copyright &y& Elsevier]

Abstract: EPR and optical absorption studies of VO2+-doped zinc lactate trihydrate single crystals are done at room temperature. The EPR spectra of VO2+ are characteristic of tetragonally compressed octahedral site. The angular variation of the EPR spectra shows single site occupying interstitial position in the lattice. The spin Hamiltonian parameters are evaluated as gx =1.9771, gy =2.0229, gz =1.9236 and Ax =76, Ay =104, Az =197 (×10−4)cm−1. Using these parameters and optical absorption data various bonding parameters are determined and the nature of bonding in the complex is discussed. [Copyright &y& Elsevier]

Abstract: EPR study of Cr3+-doped tetramethyl cadmium chloride (TMCC) single crystals is carried out at room temperature. The crystal field and spin-Hamiltonian parameters are evaluated from the resonance line positions of different lines observed in the EPR spectra. The g and D parameter values are found to be g=1.9741±0.0002 and D=553±2×10−4 cm−1, respectively. EPR data indicate that the site symmetry of Cr3+ ion in the crystal is distorted octahedron. Cr3+ ions enter the lattice substitutionally replacing Cd2+ sites and bind to the neighboring extra Cd vacancies necessary for charge compensation. The optical absorption spectra are measured in 195–925nm wavelength range at room temperature. From optical study the energy values of different orbital levels are estimated. Further, the bonding parameters are obtained by correlating optical and EPR data and the nature of bonding in the crystal is discussed. The values of Racah parameters (B and C), crystal field parameter (Dq) and nephelauxetic parameters (h and k) are obtained to be B=722, C=2845, Dq=2043cm−1, h=1.015 and k=0.21. [Copyright &y& Elsevier]

Pure and copper doped glasses with composition, xLi2O-(40-x)Na2O-50B2O3 -10Bi2O3, have been prepared over the range 0 ≤ x ≤ 40. The electron paramagnetic resonance (EPR) spectra of Cu2+ ions of these glasses have been recorded in the X-band at room temperature. Spin Hamiltonian parameters have been calculated. The molecular bonding coefficients, α2+ and β2+, have been calculated by recording the optical absorption spectra in the wavelength range 200--1200 nm. It has been observed that the site symmetry around Cu2+ ions is tetragonally distorted octahedral. The density and glass transition temperature variation with alkali content shows non-linear behaviour. The IR studies show that the glassy system contains BO3 and BO4 units in the disordered manner. [ABSTRACT FROM AUTHOR]

A reliable copper wafer bonding process condition, which provides strong bonding at low bonding temperature with a short bonding duration and does not affect the device structure, is desirable for future three-dimensional (3-D) integration applications. In this review paper, the effects of different process parameters on the quality of blanket copper wafer bonding are reviewed and summarized. An overall view of copper wafer bonding for different bonding parameters, including pressure, temperature, duration, clean techniques, and anneal option, can be established. To achieve excellent copper wafer bonding results, 400°C bonding for 30 min. followed by 30 min. nitrogen anneal or 350°C bonding for 30 rein. followed by 60 min. anneal bonding is necessary. In addition, by meeting the process requirements of future integrated circuit (IC) processes, the best bonding condition for 3-D integration can be determined. [ABSTRACT FROM AUTHOR]

Aluminium metal matrix composites (AlMMCs) offer several advantages relative to monolithic aluminium alloys such as high stiffness, strength, wear resistance, low thermal expansion coefficient, etc. However, despite considerable improvements in developing AlMMCs, the lack of reliable joining methods restrict their greater application. Fusion welding of AlMMCs has not proved successful because high temperature nature of the process normally causes unfavorable reactions between the reinforcement and the matrix, leading to the formation of a variety of defects. On the other hand, solid-state welding and diffusion bonding may not be suitable due to the presence of chemically stable surface layer of aluminium oxide, which, being insoluble in aluminium, inhibits metal-to-metal contact during diffusion bonding. Furthermore, diffusion bonding requires a very smooth and clean contact surface, which is difficult to obtain in industrial applications. As an alternative, transient liquid phase (TLP) diffusion bonding, which operates at a lower temperature, can be used to circumvent the problems associated with the oxide layer. The formation of liquid phase (eutectic) can assist the disruption of the oxide layer and promote metallic contact. The composite material used in the present study consisted of 6061 alloy containing 15 volume % of SiC particulates of 23 μm diameter. TLP bonding was carried out at 560 C in argon atmosphere using copper as an interlayer with different pressures and holding times. TLP-bonded AlMMCs were characterized by optical and scanning electron microscopy, microhardness survey, and shear tests. The results indicated that adequate bond strength could be achieved with suitable bonding parameters such as holding time and initial pressure. [ABSTRACT FROM AUTHOR]

Abstract: Optical and EPR investigations of chromium and nickel doped zinc phosphate glasses are carried out at room temperature to evaluate crystal field, spin-Hamiltonian and bonding parameters. For Cr3+ ion, the site symmetry is ascribed to a distorted octahedron, whereas the Ni2+ ion is located in a near octahedral site. In addition, the bonding parameters suggest covalent nature for Cr3+ and a moderate covalent nature for Ni2+ in the zinc phosphate glasses. [Copyright &y& Elsevier]

Staining of tissues by dyes is accomplished through various types of bonds, some of which have been poorly defined in traditional biological literature. Here, basic principles of bonding are reviewed to establish uniform terminology and definitions consistent with the field of chemistry. The concept of charge – its presence or absence, magnitude, extent of delocalization and potential for being displaced by outside forces – underlies all bonding phenomena. These same attributes influence solubility and resistance to extraction during dehydration of tissue sections. Covalent bonds involve shared electrons; they are very strong and essentially irreversible under conditions encountered during staining. Polar covalent bonds within dye molecules generate partial atomic charges that create the potential for hydrogen bonding. This is measured by the hydrogen bonding parameter ( h ), the number of groups bearing charges within the ranges -0.15 to -0.50 eV or +0.15 to +0.30 eV. The potential for ionic bonding is indicated by net charge ( Z ), while the strength of such bonds is a function of charge site geometry on both bonding partners. Charge delocalization owing to conjugation, electron influencing groups, and resonance creates soft charge sites in which the ionic charge is spread over a large volume. Poorly delocalized charges or point charges are hard (small in volume). Firm bonds result from hard-hard or soft-soft pairs. Hard-soft combinations are weak, readily displaced in competitive interactions, and disrupted by solvents. Coordinate bonds with certain metals are involved with mordant staining and metal chelation dyes. Three different van der Waals attractions comprise the remainder of bonding types, all involving dipoles: Keesom (dipole-dipole) forces, Debye (dipole-induced dipole) forces and London (induced dipole-induced dipole) forces. Potentials for engaging in any of these is quantified by measures of polarity (dipole moment, d ), polarizability (crudely with π atoms describing the size of the conjugated system, or more directly with α ), hydrophobicity (with the octanol-water partition coefficient, log P or the more convenient Hydrophobic Index, HI ), and the number of halogen atoms ( X ). By using molecular modeling software, quantitative measures of bonding potential (bonding parameters) have been determined for over 400 dyes. [ABSTRACT FROM AUTHOR]

Optical absorption and EPR spectra of Co2+ and Ni2+ doped sodium phosphate glasses have been investigated. Crystal field parameters and g values are determined. For Co2+ doped glass Dq=890, B=700, C=4125 cm-1 and g values of 4.23 and 2.04 at 20 K, for Ni2+ doped glass Dq=890, B=770, C=3700 cm-1 and a g value of 2.28 at room temperature were found. Correlating the optical and electron paramagnetic resonance data suggests the bonding between transition metal ions and ligands as ionic in nature. [Copyright &y& Elsevier]

A copper-doped LiRbB4O7 crystal was grown by the Czochralski technique. Powder X-ray, EPR and optical absorption studies were carried out. The results and discussion of the copper doped LiRbB4O7 crystal indicate that the copper ions enter the host lattice by replacing Li ions. The Cu(II) ion spectrum is characteristic of a tetragonally elongated octahedral site. Lattice and spin-Hamiltonian parameters were evaluated. The bonding parameters indicate that the bonding between copper and the ligands is partly covalent. [Copyright &y& Elsevier]

Vanadium and copper doped sodium phosphate glasses are prepared. EPR and optical absorption investigations are carried out. The results and analysis of the copper doped glass indicate that the copper ions enter the glass matrix as Cu2+ ions. The Cu2+ ion spectra are characteristic of tetragonally elongated octahedral site. The spectra of vanadium doped glass are characteristic of VO2+ and because of the short V&z.dbnd6;O band the distortion appears to be a tetragonally compressed one. Crystal field and spin-Hamiltonian parameters are evaluated. The bonding parameters indicate that bonding between the metal ions and ligands is partially covalent. [Copyright &y& Elsevier]