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Purpose: Individuals with reduced vision may rely on handheld magnifiers for near reading of texts on household items such as food packaging and far reading of information notices and signposts. Smartphones have become favoured magnification devices due to their pervasiveness. Users typically take a photo of the text, view the image with magnification and explore details by panning in two-dimensions. However, two-dimensional panning is cumbersome, confusing and slow. Materials and methods: To improve the magnification experience, we implemented a proof-of-concept magnifier that reflows text to fit the device's viewport width. The user navigates through the text by scrolling up/down. Our implementation relies on a novel pixel-based text reflow image analysis algorithm. Results: The prototype can successfully reflow text printed on sheets of paper such as notices. Initial tests showed that users preferred the smart digital magnifier over ordinary magnification. Conclusions: More work is needed to successfully handle other important use cases such as electronic information boards and household product packaging. We discuss open challenges and future directions for smart magnifiers. IMPLICATIONS FOR REHABILITATION: Magnifier users can more easily magnify small text on printed notices in public spaces. Cognitively and visually demanding two-dimensional panning of zoomed images is replaced by vertical up/down text scrolling. [ABSTRACT FROM AUTHOR]

Nanosoldering is a way of bottom-up manufacturing that can establish close, strong contact between individual nanoobjects. The reflow of nanosolder plays a vital role in achieving such reliable contact. Here, we propose an in situ reflow approach that uses Joule heating induced by electrical current flowing through the nanosolder as a heating source in scanning electron microscopy. This method facilitated the reflow of 97Sn3Cu nanosolder at approximately 2.9 μJ of Joule heat, without requiring flux. Additionally, we have performed other reflow approaches for reflow tests of 97Sn3Cu nanosolder. This paper eager to provide valuable approaches for nanosolders reflow, aiming at enhancing their application in nanosoldering. [ABSTRACT FROM AUTHOR]

A rework of electronic assemblies and the reuse of electronic components are the most effective ways to reduce electronic waste. Since neither components nor substrates were developed with the intention of multiple usage, the question of how the integrity of lead-free solder joints is affected by multiple reflow operations is crucial for the implementation of any reuse strategy. Therefore, various types of 1206 multilayer ceramic capacitors (MLCCs) differing in their capacitance value and dielectric type (X5R, X7R, Y5V, NP0) were soldered on test printed circuit boards (PCBs) having a pure Cu-metallization surface in order to investigate the intermetallic reactions during multiple reflows. The metallization system on the MLCC-component side consisted of a thick film of Ni covered by galvanic-deposited Sn. The reflow experiments were conducted using a hypoeutectic SnAgCu solder. The results show the formation of a Cu6Sn5 intermetallic phase on both metallizations, which grows homogeneously with the number of reflows. Moreover, an ongoing decomposition of the solder into Ag-enriched and depleted zones was observed. The effect of these microstructural changes on the functionality of the solder joint was investigated by mechanical shear experiments and electrical four-point capacitance measurements. [ABSTRACT FROM AUTHOR]

Multilayer ceramic capacitors (MLCCs) are critical components when thermal processes such as reflow desoldering are used during rework of electronic assemblies. The capacitor's ferroelectric BaTiO3 body is very brittle. Therefore, thermomechanical stresses can cause crack formation and create conductive paths that may short the capacitor. In order to assess the thermally induced mechanical stresses onto an MLCC during reflow desoldering, simulations were carried out, which make use of a framework of computational fluid dynamics and thermomechanical models within the ANSYS software package. In the first step, CFD simulations were conducted to calculate the transient temperature field in the surrounding of the MLCC component, which was then used as an input for FEM simulations to compute the arising mechanical stresses inside the MLCC. The results of the simulations show that the major contribution to mechanical stresses within the MLCC component comes from the mismatch in thermal expansion between the printed circuit board and the MLCC. The temperature gradients along the MLCC component are rather small and account only for moderate internal stresses within the brittle BaTiO3 body. [ABSTRACT FROM AUTHOR]

A rework of electronic assemblies and the reuse of electronic components are the most effective ways to reduce electronic waste. Since neither components nor substrates were developed with the intention of multiple usage, the question of how the integrity of lead-free solder joints is affected by multiple reflow operations is crucial for the implementation of any reuse strategy. Therefore, various types of 1206 multilayer ceramic capacitors (MLCCs) differing in their capacitance value and dielectric type (X5R, X7R, Y5V, NP0) were soldered on test printed circuit boards (PCBs) having a pure Cu-metallization surface in order to investigate the intermetallic reactions during multiple reflows. The metallization system on the MLCC-component side consisted of a thick film of Ni covered by galvanic-deposited Sn. The reflow experiments were conducted using a hypoeutectic SnAgCu solder. The results show the formation of a Cu6Sn5 intermetallic phase on both metallizations, which grows homogeneously with the number of reflows. Moreover, an ongoing decomposition of the solder into Ag-enriched and depleted zones was observed. The effect of these microstructural changes on the functionality of the solder joint was investigated by mechanical shear experiments and electrical four-point capacitance measurements.

The automotive industry’s increasing dependence on compact electronic packages requires printed circuit boards with robust microvia interconnections. With a focus on minimizing failure rates and reducing costs, automotive manufacturers require that microvia reliability have zero failures. To achieve this, the automotive industry requires identification and understanding of the uncontrollable factors related to substrates that influence microvias during the reflow process. However, conventional studies not accounting for the non-uniform nature of substrates fail to capture the real-time impact of composite substrates on microvias during reflow, highlighting the need for comprehensive substrate analysis. In this paper, we present a detailed finite element model substrate layer to analyze the influence of the substrate material on microvia structures using the design of experiment technique using the Taguchi method. The results showed that the uneven distribution of fiber and resin ratios within the substrate layer affects the microvia structures. Microvias in resin-rich areas are more susceptible to failure with 33% higher stresses than those present in fiber-rich areas. Furthermore, printed circuit board substrate is characterized into different zones based on microvia failure risk levels.

Purpose: This paper aims to study the interfacial delamination found in the boundary of the copper/copper-epoxy layers of a multi-layer ceramic capacitor. Design/methodology/approach: The thermal reflow process of the capacitor assembly and the crack propagation from the initial micro voids presented in the boundary, and later manifested into delamination, were numerically simulated. Besides, the cross section of the capacitor assembly was inspected for delamination cracks and voids using a scanning electronic microscope. Findings: Interfacial delamination in the boundary of copper/copper-epoxy layers was caused by the thermal mismatch and growth of micro voids during the thermal reflow process. The maximum deformation on the capacitor during reflow was 2.370 µm. It was found that a larger void would induce higher vicinity stress, mode I stress intensity factor, and crack elongation rate. Moreover, the crack extension increased with the exerted deformation until 0.3 µm, before saturating at the peak crack extension of around 0.078 µm. Practical implications: The root cause of interfacial delamination issues in capacitors due to thermal reflow has been identified, and viable solutions proposed. These can eliminate the additional manufacturing cost and lead time incurred in identifying and tackling the issues; as well as benefit end-users, by promoting the electronic device reliability and performance. Originality/value: To the best of the authors' knowledge, the mechanism of delamination occurrence in a capacitor during has not been reported to date. The parametric variation analysis of the void size and deformation on the crack growth has never been conducted. [ABSTRACT FROM AUTHOR]

The influence of pulsed laser treatment mode parameters on ablation and modification processes of Si3N4–TiC ceramics is determined. A mode of pulsed laser processing using the revealed interrelations after diamond grinding of Si3N4–TiC ceramic parts is established and recommended for practical use to ensure defective-layer removal and defect-free structure formation in the surface layer. [ABSTRACT FROM AUTHOR]

High-frequency organic dielectric substrate materials have been widely applied in the fabrication of FCBGA (Flip Chip Ball Grid Array) substrates due to their excellent characteristics of high-speed signal transmission. However, their higher coefficient of thermal expansion (CTE) causes the CTE mismatch between the chip and substrate to increase. High-temperature heating during the reflow soldering process intensifies the thermal mismatch within packaging structure, causing severe warping of the substrate, thereby reducing the yield and subsequent reliability. This study adopted a flatness analyzer and scanning electron microscope (SEM) to characterize the package deformation and micromorphology, and found that the substrate warped after reflow soldering, which caused defects such as chip cracks and micro-bump delamination. A fine finite element simulation model was constructed based on the structure of the experimental sample, and the structure deformation during the soldering process was simulated. An accurate finite element simulation model was constructed based on the structure of the experimental sample to simulate the deformation process of substrate during reflow. Research results show that the constraint of the chip on the substrate during the soldering process is the main factor affecting the thermal deformation mechanism, and the deformation can be suppressed by adding stiffener. This research benefits to the design of FCBGA high-density packaging. • A fine model on the deformation behavior of high-density FCBGA packaging structure was built. • Substrate warpage leads to defects such as crack and delamination in the package during reflow. • The deformation mechanism of substrate during reflow was analyzed. • Adding stiffener improves the rigidity of the substrate and suppresses its warpage. [ABSTRACT FROM AUTHOR]

This article provides an assessment of the possibility of increasing the wear resistance of the alloyed surface layer for steel St3 during plasma and laser heating of the applied surface pre-coating of the mixture of CuSn/CrxCy alloys. Plasma is more suitable for reflow a pre-deposited layer of CuSn/CrxCy with a wide range of particle sizes than laser treatment. As a result, plasma coatings have a high hardness (460-700 HV) compared to laser coatings (250-500 HV). The tests carried out showed that the wear resistance increases in the following order: Steel St3

To obtain reliable and scalable cells in 3D cross‐point memory, endurance failures caused by voiding from etching damage to memory cells should be resolved to preserve the properties of GeSbTe (GST) phase‐change materials. Herein, the fabrication of a damascene cell without patterning, which relies on the bottom‐up fill of carbon‐doped GST layers into confined cells, is proposed as a promising solution. The reflow fill of the sputtered carbon‐doped GST films into confined cells at high‐temperature and low‐power conditions is demonstrated, and a mechanism in which Sb and Te transfer into the cell through vapor transfer and viscous flow due to capillary pressure is verified. The aspect ratio increases from 2 to 7.7 under enhanced vaporization of Sb and Te as well as the capillary force. The advanced reflow‐fill process using a laser can overcome the limit of the conventional reflow‐fill technology by increasing the atomic mobility above the melting temperature. Based on the proposed method, 19 nm cross‐point memory devices are successfully integrated together with the Ovonyx threshold switch and appropriate memory windows are secured. Furthermore, the 9 nm cells exhibit reliable endurance cycles over 108. [ABSTRACT FROM AUTHOR]

Structural colors are known for their tunability, fade resistance, and eco-friendliness. Recent advancements have shown that such colors can be efficiently produced using total internal reflection (TIR) on high-refractive-index convex microstructures without the need for periodic nanostructures. However, a reproducible, fast, and programmable production strategy for these microstructures is essential for commercial applications. Here, a single-step method is reported for creating multicolor patterns by transforming photolithographically-patterned micropillars into microdomes through thermal reflow. These micropillars, uniform in height but varying in diameter, are converted into microdomes that differ in diameter and height, which display a full spectrum of structural colors, creating a versatile color palette. This process enables the production of high-resolution multicolor graphics using a rainbow color set, with high reproducibility. Additionally, by mixing distinct microdomes and adjusting their densities, a rich variety of color presentations can be achieved, enabling the recreation of arbitrary color images with microdome arrays. The variable heights of the microdomes also allow for dynamic discoloration or color changes through mechanical compression. The high reproducibility and scalability of this method hold significant commercial promise for various optical applications., (© 2024 Wiley‐VCH GmbH.)

Copper–tin (Cu–Sn) transient liquid-phase (TLP) bonding has attractive advantages and has been widely used in three-dimensional (3-D) integration to establish electrical connections between stacked chips. However, TLP bonding has technical difficulties in bonding Cu–Sn bumps with small diameters and fine pitches due to the bonding pressure-induced lateral extrusion of the melted Sn layer. As bonding of micro bumps with diameters smaller than 5 $\mu \text{m}$ is highly desired in future applications, this article reports the TLP bonding of micro bumps using improved reflow and pre-bonding. Due to the large surface-to-volume ratio of micro bumps, the reflow conditions dramatically influence the reflow characteristics, and systematical investigations are performed such that an Sn layer with an optimal thickness has been obtained to avoid lateral extrusion. A new bonding scheme has been developed by combining a solid-state pre-bonding and a TLP final bonding. The new bonding method and the Sn thickness control reflow avoid liquid Sn extrusion under bonding pressure. Using these techniques, Cu–Sn bonding of bumps with a diameter down to 5 $\mu \text{m}$ has been successfully achieved with a high bonding yield. [ABSTRACT FROM AUTHOR]

The paper presents a study of the effect of adding Mo and MoS2 on the microstructure and properties of a powder coating based on austenitic steels. The coatings have been studied using X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), a Vickers hardness tester, and abrasion wear resistance has been determined by the Pin on disk method. The results show that a coating that does not contain Mo and MoS2 consists of the phases g(Fe), M7(C, B)3 and (Fe, Cr)2B. The addition of Mo and MoS2 leads to the formation of phases M23(C, B)6, Mo2(B, C) and Fe3Mo3(C, B), where M = Fe, Cr, Mo. The main goal of these studies was to study characteristics of Mo and MoS2 distribution and the effect of their addition on the microstructure, hardness, and abrasion wear resistance of an alloy coating based on austenitic steels. Composite materials based on austenitic steels obtained by diffusion alloying (Aus0Mo), which has a nearly spherical shape with a diameter of 50–100 μm, have been used for deposition. 3–7 wt. % of Mo powder and 1.0–1.5 wt. % of MoS2 powder with a diameter less than 50 μm have been added in the powder of the composite material based on austenitic steels (Aus3Mo, Aus5Mo, Aus7Mo). Surfacing methods, including gas arc welding with a tungsten electrode, arc welding in shielding gas, plasma surfacing (PTA) and laser surfacing are widely used in industry to increase wear resistance of surfaces. The most important differences between these methods are deposition rate, applicability of materials, substrate dilution, microstructure and hardness stability after exposure to high temperatures, as well as manufacturing cost. Among the methods described above, plasma spraying followed by fusion is a good alternative to other surfacing processes. The coating should not be overheated until it is completely melted, since in this case the primary crystals of chromium carbides and borides pass into a liquid solution and upon subsequent crystallization, form a coarser structure, worsening the quality of the coating. This is precisely what does not occur during plasma spraying followed by reflow; in addition, the method is cheap, coatings are of high quality, competitive wear resistance and high stability of properties at high temperature.

Ionic residues resulting from the soldering process is an important parameter in connection with humidity robustness of Printed Circuit Board Assemblies (PCBAs) due to their ability to enhance moisture absorption and surface conductivity. For reflow process, residues are trapped under the components, and the morphology of the residues can change with humidity exposure resulting in the release of ionic components. In this work, trapped residues below the components from reflow process of several commercial PCBAs were characterized before and after exposure to humidity conditions. PCBAs used for the analysis had undergone multiple reflow heating profiles by single and double reflow plus additional passes to understand heating effects. The morphology change of the trapped residues under components upon humidity exposure was observed using optical and scanning electron microscopy. The conductivity of the localized extracted solutions was measured and NaCl equivalency was determined. The solder paste materials were analysed for their water sorption property, while the effect of humidity on electrical property was assessed using electrochemical impedance spectroscopy using test PCBs. The results show that the change in morphology and level of activator release of residues were a function of the flux type, PCBA characteristics such as component standoff height and number of reflow cycles. Water layer formation upon humidity exposure and electrical properties on test PCBs are correlated with water sorption of the flux part. [ABSTRACT FROM AUTHOR]

The results of metallographic studies into the structure of plasma coatings obtained from a mixture of high-chromium alloy cast irons and nickel-chromium alloys are presented. It is established that the structure of these high hardness coatings consists of carbides and chromium borides having a ledeburite-austenite base. When plasma spraying is followed by reflow melting, the structure of reflowed coatings becomes homogeneous and finely dispersed, resembling that of the initial powder. In plasma coatings, the distribution of elements is uniform; however, when self-fluxing coatings melt, they are redistributed. The highest wear resistance was achieved in coatings obtained via plasma spraying followed by the reflow melting of powder compositions PR-Ni70Cr17Si4B4 (23%) + PG-FBYu 1–4 (73%) + Al (4%) and plasma surfacing with the use of powder compositions PG-FBYu 1–4 (70%) + PR-Ni70Cr17Si4B4 (27%) + Ti (3%). [ABSTRACT FROM AUTHOR]

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Aim: The aim of this study was to investigate the relationship between no-reflow (no-RF), reflow (RF), and the P-wave time index in patients undergoing percutaneous coronary intervention (PCI) with a diagnosis of acute myocardial infarction (AMI) due to total occlusion. Methods: This study included a total of 272 AMI patients with no-RF (110 patients) and RF (162 patients). Results: The no-RF group had higher values of mean maxPWTpostPCI(94.95 ± 15.61 vs. 117.86 ± 12.06, P < 0.001), minPWTpostPCI(54.21 ± 12.13 vs. 67.31 ± 11.79, P < 0.001), and PWDpostPCI(39.14 ± 12.55 vs. 50.91 ± 11.9, P < 0.001) during the post-PCI period. According to multivariate logistic regression analysis, maxPWTpostPCI(odds ratio [OR]: 1.103, 95% confidence interval [CI]: 1.049–1.160, P < 0.001), minPWTpostPCI(OR: 1.055, 95% CI: 1.011–1.101, P = 0.0014), and PWDpostPCI(OR: 1.107, 95% CI: 1.037–1.181, P = 0.002) were the independent predictors of RF after PCI. ROC curve analyses demonstrated that the optimal cutoff values for maxPWTpostPCI, minPWTpostPCI, and PWDpostPCIfor predicting no-RF were 112.95 ms (area under the curve [AUC]: 0.852, 95% CI: 0.807–0.898, P < 0.001, sensitivity 70%, specificity 85.2%), 62.66 ms (AUC: 0.650, 95% CI: 0.585–0.716, P < 0.001, sensitivity 54.5%, specificity 72.8%), and 43.43 ms (AUC: 0.782, 95% CI: 0.727–0.837, P < 0.001, sensitivity 75.5%, specificity 60.5%), respectively. Conclusions: Prolonged maxPWTpostPCI, maxPWTpostPCI,and PWDpostPCIare independent predictors that differentiate no-RF from RF in patients with AMI after PCI and can be used in the follow-up of no-RF patients during the post-PCI period.

Achieved system level heterogeneous integration involving 130 nm tech node active Si interposer, two 65 nm tech node I/O chips and one 28 nm tech node FPGA die. Chip on Chip on Substrate packaging methodology was demonstrated for handling active Si interposer die as thin as 40 μm. Different packaging approaches were evaluated and the results are benchmarked. In addition, active Si interposer concept is introduced to provide Analog to Digital Converter (ADC), Digital to Analog Converter (DAC) and Power Management Unit (PMU) functions to support high-performance logic. Furthermore, benefits of active Si approach such as system scaling and cost-effectiveness have been demonstrated. “Via Last” TSV approach is used for the fabrication of 130 nm tech node active Si interposer. It was confirmed that appropriate selection of temporary bonding material plays a critical role in device wafer warpages in via last TSV process flow. Functionality checks were carried out on all samples subjected to preand post-reliability assessments, which include thermal cycling (TC), moisture sensitivity tests (MSL) and highly accelerated stress tests (HAST). All samples were found to be functional with no deterioration in performance despite being subjected to reliability tests and high-voltage stress tests.

Ball grid array (BGA) architectures are being widely used in the semiconductor industry in surface mount technology (SMT) applications to satisfy the miniaturization needs of emerging microelectronics systems. However, these architectures are not compatible with socketing applications as the mechanical contact between the gold paddle and the solder sphere leads to undesired reactions, increasing the contact resistance and degrading the reworkability overtime. To address this challenge, surface modification of BGA spheres with multilayered thin-film metallic coatings such as Ni-Au is proposed to maintain a nonreactive noble metal interface when used in a socket. This article focuses on the process of attaching the surface-modified spheres on a package using two solder pastes—Sn57.6Bi0.4Ag (SBA) and Sn3.0Ag0.5Cu (SAC305) with liquidus temperatures of 138 °C and 219 °C, respectively. The challenge of solder paste wicking on the entire surface of the Au-coated sphere was addressed by controlling the volume of the solder paste, and the joint shear strength was optimized by controlling the time above liquidus (TAL) during reflow. A 30–40-s window for TAL was established to achieve a strong solder joint with controlled paste wicking for both solder pastes. The strength of the joint was measured by a single-ball shear test, followed by microstructural analysis to identify the failure modes. Brittle fractures were observed for both solder pastes with an optimum joint shear strength ranging from 55 to 70 MPa for the SBA paste, and 72 to 75 MPa for the SAC305 paste. [ABSTRACT FROM AUTHOR]

The technological route for the production of radio electronic printed units is considered. Determined that he most critical operation is reflow soldering in the vapor-gas phase. The most significant factors of this operation are revealed by the method of expert evaluation. To construct a mathematical model a fractional factor experiment was carried out. The regression equation is obtained and carried out its verification for adequacy. A motion was made along the response surface in the direction of the gradient of the linear approximation until the area of the extremum was reached. In this case, an increase in the quality criterion has been achieved.

In the current study, the influence of thermal ageing on evolution of microstructures in the interfacial region between solders (Sn–37Pb, Sn–3.5Ag–0.5Cu) and copper substrates was investigated. Pb-containing and Pb-free solders were reflowed on Cu substrates at 230 °C for 15 min and were isothermally aged at 100 °C for 24 h. As-reflowed Sn–Pb solder/Cu substrate interfacial region exhibited continuous and layered type of IMC at the interface, and this IMC morphology changed to scallop type with isothermal ageing. SAC solder/Cu as-reflowed samples showed continuous and needle-shaped Cu6Sn5 and Ag3Sn IMCs at the interface. However, in an isothermally aged condition, plate-shaped Cu6Sn5 and flower-shaped Ag3Sn IMCs were found inside the solder matrix. Scanning electron microscopic (SEM) study showed that the thickness of Cu6Sn5 IMC was higher in reflowed Sn–Pb/Cu region than in SAC/Cu region. [ABSTRACT FROM AUTHOR]

Co–Sn–Co multi-layer films with various Sn-layer thicknesses have been deposited by using the electrodeposition technique. The deposition was performed at room temperature on gold coated silicon substrates. The thickness of Sn layer was kept ∼ 4.5, 2.5, 1.5 and 1 μ m, while the thickness of each Co layer was fixed to ∼ 0.75 μ m. The Sn layer was sandwiched between two Co layers. The total thickness of the films was ∼ 6, 4, 3, 2.5 μ m, respectively. The intended ratio of Sn was about 25 at.% while Co was about 75 at.%. The separation inside the Sn-layer has been observed at higher Sn-layer thicknesses with increasing reflow temperature. It may be due to the combined effect of thermal stress arising during cooling from elevated reflow temperatures and solidification shrinkage in the thick Sn layer due to the formation of IMC CoSn2. However, 1 μ m has been found to be a critical thickness, which remains intact when sandwiched between two cobalt layers. The structure of these multi-layer films was studied as a function of temperature. It has been observed from X-ray diffraction (XRD) that the as-deposited films exhibit strong peaks belonging to elemental Co and Sn. At temperatures of 270–290∘C, CoSn2 begins to appear and grow at the interfaces and in the middle of Sn layer with the decrease in elemental Sn. However, sufficient amount of Co is still present in pure form as is evident by the XRD and field emission scanning electron microscopy images at all temperatures. This study confirms that only one reaction product, viz. CoSn2, formed in as-deposited during reflow at temperatures 270–290∘C for a fixed time of 10 min, although several other stable IMCs, e.g. Co3Sn2, CoSn, CoSn2, CoSn3 exist in the Co–Sn system at 250∘C according to phase diagram. It is not uncommon that all the thermodynamically stable IMCs do not form in the system due to kinetic reasons. Accordingly, the formation of IMCs through interfacial reaction has been discussed in this paper. [ABSTRACT FROM AUTHOR]

• Low vision users often rely on built in browser magnification and responsive content that reflows to fit the viewport widths. • Consent notices and sticky web element can obstruct access to content when users use browser magnification. • Developers should also design for, and test with, narrow viewports and consider alternatives to sticky contents. The practice of using consent notices on websites has received much criticism and attention among researchers. Much of the research has addressed unethical aspects of consent notices while less attention has been devoted to implications for accessibility. This study thus set out to explore implications of such elements for low vision users who rely on browser magnification to access information on the web. A selection of the 100 most frequently used or formally important websites in Norway was manually studied with heuristic evaluation to assess their accessibility with high magnification. The results show that a large portion of the websites contained blocking consent notices that make the websites inaccessible while magnified. Also, most of the websites employed sticky permanent elements such as navigation menus that obstruct much, in some cases all, of the screen real estate in the magnified view. The study also uncovered patterns that preserve accessibility. A key implication of this study is that web developers should consider narrow use cases explicitly. Recommendations are provided on how to avoid inaccessibility for users relying on magnification in narrow viewports. [ABSTRACT FROM AUTHOR]

Lubricant reflow for 10 Å Z-Tetraol film is characterized for heat-assisted magnetic recording by numerical simulation using the experimentally determined thickness-dependent diffusion equation. The competition between laser-induced lubricant depletion (troughs) and subsequent healing by reflow is investigated as a function of lubricant depletion rate, trough width, trough depth, and duty cycle (reflow time between successive laser exposures). The simulations include 1, 5, 9 and 13 adjacent troughs. Trough width of 50 nm with an edge-to-edge separation distance of 50 nm and laser depletion rates of 1.0, 0.1 and 0.001 Å/cycle are simulated. Reflow kinetics on 13 troughs with a trough width of 20 nm and an edge-to-edge separation distance of 20 nm is also included to probe the effects in the limit of very small laser spots. Duty cycles of 10 and 100 millisec are used in the simulations. The results of the numerical simulations indicate that trough recovery by reflow increases with increasing duty cycle or decreasing number of adjacent troughs, trough separation distance and laser depletion rate. Conclusions based upon single trough studies are misleading for HAMR interfaces.

Lubricant reflow for Z-Tetraol is characterized for heat-assisted magnetic recording (HAMR). The thickness-dependent diffusion constant, D(h), is determined from flow experiments for submonolayer Z-Tetraol films between 2.5 and 13 Å. Fickian diffusion using experimental D(h) values are used to numerically simulate lubricant reflow into HAMR laser-depleted troughs as a function of trough number, trough depth, trough distance and trough width. Reflow is computed to be slower for multiple, wider and deeper troughs. Reflow kinetics as a function of trough separation distance is complicated by adjacent trough interactions. Two major kinetic regimes are identified. Multiple troughs that have not coalesced recover more quickly. Once multiple troughs coalesce into a single larger trough, reflow kinetics is drastically slowed. The crossover time between the two kinetic regimes is computed to be approximately 400 millisec for the system under investigation here, but will be a strong function of trough number, width, depth and separation distances. The simulation of multiple troughs provides significant insight into HAMR conditions. Single trough lubricant studies may be misleading for HAMR systems.

In lead-free reflow soldering, the presence of voids should be taken into account. For this reason, the effect of the applied heating profiles was examined via the characterization of voids in galvanic and immersion Sn coatings. According to EU Directive 2002/95/EC, the screening of Pb element of reflow soldering (i.e. of electrical and electronic equipment) is necessary; and the practical implementation of this measurement is largely affected by the characteristics of the solder (i.e. the presence of voids and the inhomogeneity of the solder). Comparing the results of the above two coating methods, it was found that by chemical coating more voids were formed and the detected lead content was higher than for galvanic Sn. The standard deviation of Ag and Cu concentrations was mainly influenced by the appearance of large compounds in the second case, while with chemical coating, no large compounds were formed due to the elevated number of voids.

In the starved lubrication regime, the film thickness can be much less than the fully flooded film thickness. The film thickness reduction is related to the inlet meniscus distance. The inlet meniscus and the film thickness can be computed for a given inlet film thickness distribution which is generally non-uniform. The inlet film thickness distribution, which is essentially the outlet film thickness distribution of the previous contact, is affected by the surface tension. In this paper, a modified Coyne-Elrod boundary condition is used to calculate the inlet film thickness distribution, taking the surface tension into account. A numerical analysis of EHL point contacts is carried out and solutions of the inlet meniscus and the film thickness are presented. At lower capillary numbers, side bands formed by reflow in the outlet region can replenish the contact owing to reflow in the inlet region. At higher capillary numbers, the side bands move away from the center of the track and the inlet distance decreases. This is a main cause of starvation in EHL point contacts. A good agreement is found between the numerical solutions and experimental results.