Large Plate Research Articles

Effects of cooling rate and joint size on Sn grain features in Cu/Sn–3.5Ag/Cu solder joints

In Sn-based micro solder joints for fine pitch flip chip or 3D packaging technologies, the number of Sn grains is always limited and sometimes only one Sn grain exists in a joint, which inevitably causes anisotropy in the performance and reliability of micro interconnection. It is known that the parameters of solder joint structure and reflow process, especially cooling stage, have a great significance for regulating the features of Sn grains after soldering. Hence, in the present paper, the Sn grain features of Cu/Sn–3.5Ag/Cu solder joints with different joint sizes (300 μm, 100 μm and 50 μm) solidified under different cooling rates (1.5 °C/s, 0.5 °C/s and 0.1 °C/s) were studied. Generally, the number of Sn grains decreased as the joint size decreased. When the joint size was 50 μm, the solder joints tended to contain only one or two Sn grains irrespective of the cooling rate. Furthermore, cooling rates greatly affected the number and orientation of Sn grains as well as the growth of large Ag3Sn intermetallic plates to varying degrees. The formation of Sn grains and Ag3Sn plates was discussed from the viewpoint of nucleation under different conditions.

Effect of temperature and reactant concentration on calcium phosphate precipitation

Calcium orthophosphates (CaP) constitute an important group of biomaterials used in bone repair and tooth remineralization. In some applications, controlling particle surface area and/or dimensions is important to fine-tune ion release kinetics. This study evaluated the interaction between synthesis temperature (22 °C or 45 °C) and reactant concentration (“Low”: 0.1 mol.L−1, “Medium”: 0.5 mol.L−1 or “High”: 1.0 mol.L−1) on phase formation, particle morphology, size and surface area. Calcium and phosphate precursor solutions (Ca/P = 1.0, initial pH: 7.9–8.1) were mixed and the precipitate was obtained after 24 h. DCPD (CaHPO4·2H2O) was the only phase identified by X-ray diffraction at 22 °C/Medium and 22 °C/High, with large plate crystal morphology, while DCPD/OCP (Ca4H(PO4)3·2.5H2O, as agglomerates of sub-micron crystals) mixtures were observed at 22 °C/Low, 45 °C/Medium and 45 °C/High. Small-plate, low-crystallinity HAP (Ca5OH(PO4)3) was obtained at 45 °C/Low. In spite of the different morphologies, particle hydrodynamic radius (as determined by laser light scattering) was not affected by the tested variables (median: 10–20 μm). Surface area, on the other hand, varied according to particle morphology (37–135 m2/g). In conclusion, temperature and reactant concentration interacted to define the precipitated phases, each of them with a characteristic morphology. Thermodynamically more stable phases (OCP or HAP) were found in syntheses conducted at 45 °C due to accelerated DCPD hydrolysis.

On the 3-D Shape of Interlaced Regions in Sn-3Ag-0.5Cu Solder Balls

The microstructure of Sn-Ag-Cu (SAC) solder joints plays an important role in the reliability of electronics, and interlaced twinning has been linked with improved performance. Here, we study the three-dimensional (3-D) shape of interlaced regions in Sn-3.0Ag-0.5Cu (SAC305) solder balls by combining serial sectioning with electron backscatter diffraction. In solder balls without large Ag3Sn plates, we show that the interlaced volume can be reasonably approximated as a hollow double cone with the common 〈100〉 twinning axis as the cone axis, and the 〈110〉 from all three twinned orientations making up the cone sides. This 3-D morphology can explain a range of partially interlaced morphologies in past work on 2-D cross-sections.

Bromine Precursor Mediated Synthesis of Shape Controlled Cesium Bromide Nanoplatelets and Their Mechanism Study by DFT Calculation.

We synthesized CsBr nanoplatelets and controlled their size and shape using HBr and tetrabutylammonium bromide (TBAB) as bromine precursors, obtaining hexagonal and rectangular plates, respectively. The phenomena were elucidated by density functional theory calculations, which indicated that the formation of the hexagonal shape was explained by comparing the relaxed surface free energy of oleate on the exposable surfaces of the CsBr plates. As the bromine precursor changed from HBr to TBAB, the formation of the rectangular shape was determined by comparing the surface free energy and attachment free energy between exposable surfaces due to its bulky surfactant tail. In addition, the TEM measurements indicated that the rectangles or hexagonal shapes are aligned precisely regardless of their size. The data mean that the large plates split into smaller plates as the temperature increases so that the nanoplatelets were formed by a top-down method in which a large plate was split by surfactants rather than through a bottom-up method in which a rectangle or a hexagon grew from smaller particles. The facts were explained by the surface chemical thermodynamics model which showed that the surface area (σ) and the crystal size decreased as the temperature increased.

Development and calibration of reduced-size plate thermometer for measuring incident heat flux

This study proposes a new reduced-size plate thermometer with a modified shape and improved insulation performance in order to resolve problems commonly found when using conventional plate thermometers to measure incident heat flux in fire environments, for example, a low spatial resolution caused by the large plate area and a non-uniform temperature distribution on the plate. The main results of this study showed that the new plate thermometer exhibits high spatial temperature uniformity, and that the plate thermometer can be reduced in size to 30 mm. Moreover, it was found that the relative error of the incident heat flux of the plate thermometer was substantially reduced compared to that of a heat flux meter using a conduction correction factor expressed as a third-order polynomial function of heat flux, rather than using an average empirical constant calculated from measurement over a wide range of heat fluxes. Finally, it was confirmed that the incident heat flux measured by the new reduced-size plate thermometer in a heptane pool fire was in good agreement with the heat flux meter measurements during the rapid-fire growth, fully developed and decay phases of a fire.

KARAKTERISTIK DAN PARAMETER SUBDUKSI SUMBER GEMPA PULAU JAWA

The movement of three large plates makes earthquakes frequent in Indonesia. The earthquake caused a lot of damage and casualties. One of the causes of the high risk of earthquake disasters is the large population. Java Island is the island that has the largest population in Indonesia. In addition, earthquakes often occur in Java and its surroundings, which cause a very high risk of earthquake. A further disaster that occurs after an earthquake is a tsunami if the earthquake originates from the ocean (earthquake originates from subduction). Therefore, this study examines the characteristics and parameters of earthquakes originating from subduction around Java Island which consists of 10 zones (5 of megathrust zone and 5 of benioff zone). The method used to determine these parameters is the Guternberg-Richter's law method and the maximum likely hood / characteristic method. The results of these two methods have differences due to earthquake uncertainty factors. In the application of earthquake hazard analysis, these two methods are used for calculations by increasing the percentage of use in the characteristic method. This is because geological evidence shows that characteristic earthquakes occur more frequently than earthquakes predicted from the gutenberg-richter model. In addition, it is also necessary to know the subduction zone dip angle for modeling 3D earthquake sources. Each subduction zone around the Java Island is divided into 5 areas. The megathrust zone is at a depth of up to 50 km and the benioff zone at a depth of more than 50 km. The result shows that the largest dip value is in the Java 3 megatrust zone with 14.667 and the Java 2 benioff zone with 53.667.

Modification of a Cylindrical Mirror Analyzer for High Efficiency Photoelectron Spectroscopy on Ion Beams

An existing cylindrical mirror analyzer (CMA) that was initially equipped with eight channeltrons detectors has been modified to install large micro-channel plate detectors to perform parallel detection of electrons on an energy range corresponding to ~12% of the mean pass energy. This analyzer is dedicated to photoelectron spectroscopy of ions ionized by synchrotron radiation. The overall detection efficiency is increased by a factor of ~20 compared to the original analyzer. A proof of principle of the efficiency of the analyzer has been done for Xe5+ and Si+ ions and will allow photoelectron spectroscopy on many other ionic species.

Evaporation of highly wetting fluids on aluminum microporous coating

Waste heat dissipation, using evaporation heat transfer, is highly desirable in applications involving components that generate a persistent heat flux, due to the temperature uniformity experienced during evaporation. This form of heat transfer requires continuous feeding of liquid to the entire heated surface and mitigating the formation of dry spots. With complete liquid coverage, evaporation heat transfer results in a temperature uniformity across the heated surface due to phase change at the liquid-vapor interface. Aluminum High-Temperature Conductive Microporous Coating (Al-HTCMC) is highly effective in spreading liquid over a surface. It is fabricated by brazing aluminum particles (dp = 11, 24, 66, or 114 µm) onto a flat aluminum surface. This coating is applied on a large vertical aluminum plate (50.8 mm wide × 152.4 mm tall × 3.3 mm thick). Rate of rise experiments with highly wetting fluids (ethanol, acetone, and methanol) are performed, at room temperature and atmospheric pressure, where the bottom of the coated plate is submerged in a pool of liquid to investigate the effect of the particle size on permeability and effective meniscus radius within the Al-HTCMC. Evaporation experiments are also conducted using ethanol at saturated conditions, where a 50.8 × 127 mm2 heater is attached to the aluminum plate. The effects of particle size, coating thickness, and fluid properties on the evaporation performance are evaluated. The temperature distribution across the entire surface is found to remain uniform with nearly zero superheat until the dryout heat flux occurs. A theoretical model is developed to predict the dryout heat flux based on pressure drop through the microporous layer, and the experimental results are in good agreement with the theoretical model.

Comparative study on the effect of aerodynamic braking plates mounted at the inter-carriage region of a high-speed train with pantograph and air-conditioning unit for enhanced braking

In this study, we analyse the unsteady flow around a 1/8th-scaled uniform vehicle model with three configurations of aerodynamic braking plates mounted at the inter-carriage region. In addition, the study aims at determining an appropriate plate configuration to obtain an increasing effect of aerodynamic drag and analyses the effect of plates on the flow field at the top of the vehicle, where a pantograph and an air-conditioning unit are installed. Improved delayed detached eddy simulations are conducted with shear-stress transport κ–ω turbulence model, and the results are compared with the experimental data and grid independence to validate the reliability of the obtained solution. Furthermore, the aerodynamic drag of the vehicles is significantly increased when the plates are opened and the aerodynamic braking distance is significantly decreased, especially for the single large plate mounted downstream of the inter-carriage region, followed by the single large plate mounted at the upstream of the inter-carriage region. In addition, the flow field around the inter-carriage region is more sensitive to the size of plates than their location. Both the pantograph and air-conditioning unit restrict the development of airflow downstream of the plates, and should thus be located as far away from the inter-carriage region as possible. Although the pantograph–catenary system would be affected by the opening of plates, the effect is not very large. The findings of this study can also be conducive to help engineers design and operate an optimal aerodynamic braking system.

<p><strong><em>Muonabuntor</em> gen. nov., a new genus of false click beetles from mid-Cretaceous Burmese amber (Coleoptera: Elateroidea: Eucnemidae)</strong></p>

Eucnemidae is a relatively large beetle family belonging to the polyphagan superfamily Elateroidea. Numerous fossil eucnemids have been reported from Cenozoic deposits, but the Mesozoic record of Eucnemidae is much sparser. Here we describe and figure a new eucnemid beetle, Muonabuntor grandinotalis gen. et sp. nov., discovered from mid-Cretaceous Burmese amber (ca. 99 Ma). The new genus resembles extant Jenibuntor and Euryptychus in having simple hypomera and tubular antennomeres 9–11, but differs from the latter genera by its comparatively longer pronotum, weakly striate elytra, and large metacoxal plates. The fossil record and classification system of Eucnemidae are also reviewed.

Plate waste of inpatients with diabetes mellitus

Background: The nutrition services of inpatient with diabetes mellitus is very important because dietary management is the key to controlling blood glucose level. Ensuring the patient to consume all the food served by the hospital or reduce the plate waste may help patients to meet their nutritional needs. This study aimed to investigate plate waste of inpatient with diabetes mellitus in hospitals and its contributing factors so the quality of food service in the hospital could be enhanced.Methods: The sample of the study was 22 inpatient with diabetes mellitus at Al Islam Hospital in Bandung, Indonesia from November 2014 to February 2015. The patient's plate waste at breakfast, lunch and dinner for 2 days was weighed using an electronic scale. Patients were also interviewed to find out the reasons for wasting food. Results: The overall mean of plate waste in this study was 13.26% of food served. Porridge was the type of food that had the highest mean percentage of plate waste (17.38%). Vegetables were the second-highest wasted food (17.05%). Loss of appetite, lack of knowledge, cold food temperature and large main plate portion were the reasons for food wastage.Conclusions: The type of food that wasted the most by inpatient with diabetes mellitus was porridge and vegetables. Improving the quality of food service and delivery as well as increasing the role of health workers to educate and encourage patients to eat while under treatment in hospitals are interventions that can be done to reduce the amount of inpatient plate waste.

Pharmacokinetics of Cefquinome on Single Intravenous Administration in Marathwadi Buffalo Calves by Microbiological Assay Technique

Experiment was performed on six healthy Marathwadi buffalo calves of either sex of age above 6 months and weighing between 80 to 120 kg to study the different pharmacokinetic parameters after single intravenous administration @ 2 mg/kg body weight by microbiological assay technique. After intravenous administration of the drug, blood samples (4 ml each) of buffalo calves were collected from external jugular vein using disposable needles in clot activator tubes at different time intervals. The schedule of blood collection for pharmacokinetic studies after intravenous administration was at 0, 5, 10, 15, 30 min and 1, 2, 4, 6, 8, 10, 12 and 24 hrs. The serum levels of cefquinome were estimated by microbiological assay technique using large glass plate. Different Pharmacokinetic parameters were calculated as described by different scientists. The peak serum concentration, elimination half life, volume of distribution, total body clearance, absorption half life and area under curve values found were 1.74 ± 0.151 mcg/ml at 2.5 min of sampling time, 1.97±0.14 h, 3.97 ± 0.83 L/kg (Vd(B)) and 2.86 ± 0.34L/kg (Vdss), 1.11 ± 0.13 L/kg.h−1, 0.10 ± 0.02 h, and 1.93 ± 0.23 μg/ml/hr respectively. The bioavailability of cefquinome in buffalo calves was found to be 100 %. It may be concluded that the elimination half life of cefquinome was 2.54 h in Marathwadi buffalo calves indicating the repeating of doses at 12 to 15 h intervals in Marathwadi buffalo calves and the loading dose would be double than the maintenance dose of cefquinome after intravenous administration.

Fabrication of high-performance YBa2Cu3Oy melt-textured bulks with selective grain growth

We developed a simple single-direction melt growth for the fabrication of high-performance REBa2Cu3Oy (RE: rare earth element) melt-textured bulks with selective grain growth. In this method, bulks were epitaxially melt-grown from a large plate cut from commercial melt-textured bulks by utilizing the different peritectic temperatures of REBa2Cu3Oy. Ag-added YBa2Cu3Oy bulks with three crystallographic orientations ([100], [110], and [001]) were successfully prepared. The whole c-grown bulk showed a higher trapped field (∼0.39 T) with more circular distributions than the conventional top-seeded bulk. The proposed method is promising for the fabrication of high-performance melt-textured bulks with high scalability and flexibility.

Size effect of the modulus of rupture in float glass plates

This paper investigates the modulus of rupture of float glass plates of different sizes aiming at determining the effect of the plate area on its flexural tensile strength. Currently, the Weibull statistical distribution expression, which is calibrated with test data, is used for estimating the area dependent size effect. The present investigation is based on a theoretical stochastic model that is independent of test data. The numerical analysis simulates large size samples of plates and is based on the glass plate geometry, the boundary conditions, the specific loading data and implements the glass properties through a flaw distribution model characterizing the glass plate material. Very large size samples are required to obtain a converged solution. The model analysis yields higher strengths for smaller plates and the predicted tensile strength depends on the loading method. To eliminate the effect of the loading system on the size effect it was hypothesized that the fracture origin area, rather than the entire plate area, dominates the behavior. The fracture origin area for typical loading systems was determined from the model analyses. Implementation of this hypothesis shows that all tensile strength results for large samples of plates subjected to different loading systems follow a single common size-effect curve, which depends on the fracture origin area and is independent of the loading system. The calculated nonlinear stress ratio spans over almost five orders of magnitude of the plate area, considerably beyond the limited range of plate areas appearing in the literature. Comparison of the theoretically based size effect function with the empirical Weibull based data in the literature, shows similar results for relatively large area plates but an increasing difference for smaller areas, where the extrapolated empirical stress ratio law considerably underpredicts the theoretical results. Comparison of the calculated stress ratio results with test data shows very good agreement.

Casimir energy and topological mass for a massive scalar field with Lorentz violation

A Lorentz symmetry violation aether-type theoretical model is considered to investigate the Casimir effect and the generation of topological mass associated with a self-interacting massive scalar fields obeying Dirichlet, Newman and mixed boundary conditions on two large and parallel plates. By adopting the path integral approach we found the effective potential at one- and two-loop corrections which provides both the energy density and topological mass when taken in the ground state of the scalar field. We then analyse how these quantities are affected by the Lorentz symmetry violation and compare the results with previous ones found in literature.

FPCB Masked One-Step Etching Large Aperture Mirror for LiDAR

This paper presents a Flexible Printed Circuit Board (FPCB) masked one-step etching large aperture mirror for Light Detection and Ranging (LiDAR). A FPCB structure is bonded on a thin silicon wafer ( $50\sim 200~\mu \text{m}$ thick) coated with a 100 nm thick metal film and one-step of DRIE is used to etch the wafer with the FPCB structure as the mask and the metal film as the stop layer. The simple fabrication process and 0.1 mm (instead of $ needed for microfabrication) resolution photolithography lead to a very low cost of a few dollars. Copper coils embedded in the FPCB structure are attached to the backside of the large aperture mirror plate, instead of beside the mirror plate as the case in MEMS magnetic mirrors, to generate a high magnetic force and achieve a relatively high frequency considering the large aperture and high thickness. Modeling and prototyping of two designs, Mirror_A and Mirror_B, are presented to verify the novel mirror technology. LiDAR applications of the novel mirror technology are demonstrated and tested. Achieved performances are: Mirror_A, aperture $12 \times 12$ mm, oscillation frequency of 510 Hz, field of view (FOV) of 30° and radius of curvature (ROC) of 10 m; Mirror_B aperture $24 \times 24$ mm, oscillation frequency of 160 Hz, FOV of 20° and ROC of 10 m. [2020-0085]

The earthquake hazard level of Makassar

An earthquake is a natural disaster that is often found in Indonesia because its geological area is a meeting between three large tectonic plates. Earthquakes have a high level of danger due to unpredictable events. In the Sulawesi region, especially Makassar, in 2017, there was an earthquake measuring 3 SR-6 SR, with a shallow epicenter. Epicenter distance calculation is used to determine the value of peak ground acceleration (PGA), which can then affect the intensity value in the hypocenter. This study aims to analyze the level of earthquake hazard using the PGA value as the basis for the initial reference of earthquake disaster mitigation. Variables used include rock type (geology), slope and the value of peak ground acceleration (PGA). Data on rock types were obtained from the Makassar City BPBD, and slope variables were processed from the SRTM DEM. Next, an overlay analysis was conducted to determine the level of earthquake hazard using a GIS application. The results showed that Makassar City had a majority of 94% of its area has a low level of earthquake hazard, while 6% of the area that had an earthquake hazard level was quite high in the east of Makassar. The frequency of earthquakes that were felt to be influential by the community (scale III MMI) was only two times in the last three decades (1996 and 2018).

Microcontinents and Continental Fragments Associated With Subduction Systems

AbstractMicrocontinents and continental fragments are small pieces of continental crust that are surrounded by oceanic lithosphere. Although classically associated with passive margin formation, here we present several preserved microcontinents and continental fragments associated with subduction systems. They are located in the Coral Sea, South China Sea, central Mediterranean and Scotia Sea regions, and a “proto‐microcontinent,” in the Gulf of California. Reviewing the tectonic history of each region and interpreting a variety of geophysical data allows us to identify parameters controlling the formation of microcontinents and continental fragments in subduction settings. All these tectonic blocks experienced long, complex tectonic histories with an important role for developing inherited structures. They tend to form in back‐arc locations and separate from their parent continent by oblique or rotational kinematics. The separated continental pieces and associated marginal basins are generally small and their formation is quick (<50 Myr). Microcontinents and continental fragments formed close to large continental masses tend to form faster than those created in systems bordered by large oceanic plates. A common triggering mechanism for their formation is difficult to identify, but seems to be linked with rapid changes of complex subduction dynamics. The young ages of all contemporary pieces found in situ suggest that microcontinents and continental fragments in these settings are short lived. Although presently the amount of in‐situ subduction‐related microcontinents is meager (an area of 0.56% and 0.28% of global, non‐cratonic, continental crustal area and crustal volume, respectively), through time microcontinents contributed to terrane amalgamation and larger continent formation.

Manufacturing of ultra-large plate forgings by unfolding and flattening of thick cylinders

Ultra-large plate forgings are foundation of heavy machinery, but many parts of the type cannot be made by conventional technologies due to the characters of extreme manufacturing in terms of size and quality requirements. This paper introduced a systematically method called cylinder unfolding method (CUM) for producing large plate forgings, by using a serial of operations including “splitting”, “unfolding”, and “flattening” of a thick cylinder obtained from saddle forging. The technological route of CUM was presented in detail with an example of plate forging with the horizontal sizes of 6100 mm and thickness of 300 mm. The deformation features of saddle forging for fabricating transitional cylinders were analyzed, and then the subsequent handling steps including splitting, unfolding and flattening of the cylinder, as well as the auxiliary processing, were addressed. The practice proved that CUM can provide an efficient way for manufacturing ultra-large plate forgings and meet the strict requirements in geometry and mechanical performance, without highly increasing the investments of forming equipment and tooling.

Online electrochemical behavior analysis on the negative plate of lead-acid batteries during the high-rate partial-state-of-charge cycle

Transient electrochemical behavior study on the negative plate during the high-rate partial-state-of-charge (HRPSoC) cycle is of significance yet challenging to understand the health management and failure diagnosis of lead-acid batteries. Herein, we demonstrate a non-destructive monitoring method based on the charging-discharging curves and online electrochemical impedance spectrum (EIS) of the negative plate during the HRPSoC cycle. These investigations show that the potential change in the charging period (ΔVcharge) and some EIS parameters can be used to evaluate the health status of lead-acid batteries during the HRPSoC cycle. Generally, low ΔVcharge, large plate capacitance, and small plate resistance indicate a low polarization degree, a slow growth rate of PbSO4 crystals, slight H2 evolution on the negative plate, and therefore, a health battery state. These investigations introduce an online technique to evaluate the electrochemical behaviors and monitor the health state of lead-acid batteries, which may provide some valuable supports for the health management and performance improvement of lead-acid batteries.