bluuebunny/crossref_metadata_2025_split huggingface dataset:
Medium to High Strain-Rate Characterization of Lead Free Solder Alloys Through Metal Cutting Experiments
Authors: Singh Yuvraj , Udupa Anirudh , Chandrasekar Srinivasan , Subbarayan Ganesh 
Published: December 2019

Abstract
Studies on medium to high strain-rate characterization (≥ 0.1s−1) of lead-free solder are relatively few, primarily due to the lack of available methods for testing. Prior work in literature uses Split Hopkinson Bar (SPHB) experiments for high strain-rate characterization (≥ 300s−1) [1,2], while a modified micro-scale tester is used for medium strain-rate characterization (0.005s−1 to 300s−1) [3] and an impact hammer test setup for testing in a strain-rate regime from 1s−1 to 100s−1 [4]. However, there is still limited data in strain-rate regimes of relevance, specifically for drop shock applications. In this paper, we present orthogonal metal cutting as a novel method to characterize lead-free solder alloys. Experiments are carried out using a wedgelike tool that cuts through a work piece at a fixed depth and rake angle while maintaining a constant cutting velocity. These experiments are conducted at room temperature on Sn1.0Ag0.5Cu bulk test specimens with strain-rates varying from 0.32 to 48s−1. The range of strain-rates is only limited by the ball screw driven slide allowing higher strain-rates if needed. The strains and strain-rates are captured through Particle Image Velocimetry (PIV) using sequential images taken from a high-speed camera just ahead of the cutting tool. The PIV enables non-contact recording of high strain-rate deformations, while the dynamometer on the cutting head allows one to capture the forces exerted during the cutting process. Results for the stress-strain response obtained through the experiments are compared to prior work for validation. Orthogonal metal cutting is shown to be a potentially attractive method for characterization of solder at higher strain-rates.
Enabling Thermal Management of High-Powered Server Processors Using Passive Thermosiphon Heat Sink
Authors: Kulkarni Devdatta P. , Tunuguntla Priyanka , Tan Guixiang , Carte Casey 
Published: December 2019

Abstract
In recent years, rapid growth is seen in computer and server processors in terms of thermal design power (TDP) envelope. This is mainly due to increase in processor core count, increase in package thermal resistance, challenges in multi-chip integration and maintaining generational performance CAGR. At the same time, several other platform level components such as PCIe cards, graphics cards, SSDs and high power DIMMs are being added in the same chassis which increases the server level power density. To mitigate cooling challenges of high TDP processors, mainly two cooling technologies are deployed: Liquid cooling and advanced air cooling. To deploy liquid cooling technology for servers in data centers, huge initial capital investment is needed. Hence advanced air-cooling thermal solutions are being sought that can be used to cool higher TDP processors as well as high power non-CPU components using same server level airflow boundary conditions.
Current air-cooling solutions like heat pipe heat sinks, vapor chamber heat sinks are limited by the heat transfer area, heat carrying capacity and would need significantly more area to cool higher TDP than they could handle. Passive two-phase thermosiphon (gravity dependent) heat sinks may provide intermediate level cooling between traditional air-cooled heat pipe heat sinks and liquid cooling with higher reliability, lower weight and lower cost of maintenance. This paper illustrates the experimental results of a 2U thermosiphon heat sink used in Intel reference 2U, 2 node system and compare thermal performance using traditional heat sinks solutions. The objective of this study was to showcase the increased cooling capability of the CPU by at least 20% over traditional heat sinks while maintaining cooling capability of high-power non-CPU components such as Intel’s DIMMs. This paper will also describe the methodology that will be used for DIMMs serviceability without removing CPU thermal solution, which is critical requirement from data center use perspective.
Thermal Analysis of High Efficiency High Speed Drives
Authors: Khakpour Yasmin , Chen Weilun Warren , Channegowda Parikshith , Pearson Matthew R. , Lee Yongduk , Arnedo Luis 
Published: December 2019

Abstract
The thermal management of the PCB based power electronics is a key element to ensure safe operating conditions and to meet lifetime, reliability and safety requirements. This is challenging for applications above 1 kW because the substrate material used in a PCB such as FR-4 has very low heat conducting properties. Hence, there is a limit on how much loss can be dissipated from the board and for that reason this approach has only been adopted in the industry for very low power applications. With the proposed multilevel topology, WBG devices, and innovative thermal management strategies it is possible to expand the PCB based power electronics approach to power ratings between 1kW and 10 kW. For instance, an improvement in the thermal resistance of the PCB can be obtained by soldering a discrete WBG device with a TO-263 package directly on a PCB with about one inch square copper area around the device which will act as a heat spreader. Then, a further substantial reduction in the thermal resistance of a PCB is possible by the application of electrical vias. In principle each via is a copper sleeve through the board or through a part of the board. Where, instead of using its electrical function, a via can also be used as a thermal conductor. In this work, the thermal analysis of the PCB and the effect of number of vias as well as the effect of filling the vias with a thermally conductive material has been studied. The design has been optimized for the number of vias and the modeling results have been verified with experimental tests.
Addressing the Challenges in Laser Micro-Machining and Bonding of Silicon Microchannel Cold-Plate and 3D-Manifold for Embedded Cooling Applications: Perfect Debris Removal
Authors: Hazra Sougata , Jung Ki Wook , Iyengar Madhusudan , Malone Chris , Asheghi Mehdi , Goodson Kenneth E. 
Published: December 2019

Abstract
Laser machining is an inexpensive and fast alternative to conventional microfabrication techniques that produce complicated three-dimensional, hierarchical structures. One of the major issues plaguing the use of laser micromachining to manufacture commercially usable devices is the formation of debris during cutting and the difficulty in removing these debris efficiently after the machining process. For silicon substrates, this debris can interfere with surrounding components and cause problems during bonding with other substrates by preventing uniform conformal contact.
This study summarizes several post-process techniques that can be employed for complete debris removal during etching of Silicon samples using an Nd/YVO4 pulsed (∼ 1–3 kW) UV laser, detailing the advantages and drawbacks of each approach. A method that was found to be particularly promising to achieve very smooth surfaces with almost complete debris removal was the use of PDMS as a high rigidity protective coating. In the process, a novel technique to strip PDMS from Silicon surface was developed and a study was carried out to optimize the process. The result of this study is very valuable to the microfabrication industry where smooth and clean substrate surfaces are highly desirable. This work could facilitate adoption and significant improvements to the process of using UV lasers to create microstructures for commercial applications as well as in a research environment.
Stress Evaluation of Flexible Displays With Multiple-Laminations Architecture Enabled by Experimental Measurement and Simulation Based Factorial Design
Authors: Lee Chang-Chun , Huang Pei-Chen , Wang Chi-Wei , Chuang Oscar 
Published: December 2019

Abstract
Fatigue behavior of multiple-stacked film-type flexible displays under flexural load has received considerable research attention, whereas the requirement of a considerably thin and flexible packaging structure with single/multiple neutral axis has not been systemically explored. Consequently, this study evaluated the flexural load induced strain and corresponding resistance change in flexible display architecture by both experimental and simulation works. The relationship between mechanical strains and the relevant resistance change in a touch panel module is estimated by both nonlinear finite element analysis and actual experiments. The aforementioned results revealed that the simulated strain and the resistance change of indium tin oxide (ITO) film were increased as the bending radius becomes narrow. Moreover, the influences of several mechanical parameters within an entire organic light-emitting diode device package with multiple coatings were estimated by a simulation-based parametric study. It should be noted that the structure design would lead the single/multiple neutral axis (N.A.) occurred in the concerned flexible displays. Among all the designed structural and material properties, the Young’s modulus of the adhesive is the most dominant factor to determine the bending strain of ITO film and the phenomenon occurrence of multiple N.A. The analytic results indicated that the multiple N.A. design is contributed to decrease the flexural strain and corresponding resistance change of ITO film. Therefore, the design rules of single/multiple N.A. and its influences on stress-induced electric variation in flexible display are revealed.
Effects of Thermal Cycling on the Mechanical and Microstructural Evolution of SAC305 Lead-Free Solder
Authors: Hasan S. M. Kamrul , Fahim Abdullah , Suhling Jeffrey C. , Hamasha Sa’d , Lall Pradeep 
Published: December 2019

Abstract
Lead free electronic assemblies are often subjected to thermal cycling during qualification testing or during actual use. The dwell periods at the high temperature extreme during thermal cycling cause thermal aging phenomena in the solder material, including microstructural evolution and material property degradation. In addition, lead free solders can also experience aging effects during the ramp periods between the low and high temperature extremes of the cycling.
In this study, the mechanical behavior evolution occurring in SAC305 lead free solder subjected to various thermal cycling exposures has been investigated. Uniaxial test specimens were prepared by reflowing solder in rectangular cross-section glass tubes with a controlled temperature profile. After reflow solidification, the samples were placed into the environmental chamber and thermally cycled from −40 C to +125 C under a stress-free condition (no load). Several thermal cycling profiles were examined including: (1) 90 minute cycles with 15 minutes ramps and 30 minutes dwells, (2) air-to-air thermal shock exposures with 30 minutes dwells and near instantaneous ramps, (3) 30 minute cycles with 15 minutes ramps and no dwells (saw tooth profile), (4) 150 minute cycles with 45 minutes ramps and 30 minutes dwells, and (5) no cycling (simple aging at the high temperature extreme). For each profile, 10–15 samples were cycled for various durations of cycling (e.g. 48, 96, and 240 cycles), which were equivalent to various aging times at the high temperature extreme of T = 125 C.
After cycling, the stress-strain curves and mechanical properties including effective elastic modulus and Ultimate Tensile Strength (UTS) of all the cycled samples were measured. For each cycling profile, the evolutions of the mechanical properties were characterized as a function of the cycling duration, as well as the net aging time at the high temperature extreme. Comparison of the results of various thermal cycling profiles showed that the detrimental effects of aging are accelerated in a thermal cycling environment. Furthermore, microstructure evolution during thermal cycling has also been investigated to validate the observed mechanical properties degradation. The test results revealed that the mechanical properties degradation of SAC305 are higher in thermal cycling compared to simple equivalent aging. For example, the elastic modulus and UTS of SAC305 reduced by 41%, and 38%, respectively after 5 days aging whereas these properties reduced by 69%, and 51%, respectively after 5 days equivalent aging using thermal cycling profile #4 (240 cycles).
High Strain Rate Mechanical Properties of SAC-Q With Sustained Elevated Temperature Storage at 100°C
Authors: Lall Pradeep , Mehta Vishal , Suhling Jeff , Locker David 
Published: December 2019

Abstract
Leadfree electronics in harsh environments may often be exposed to elevated temperature for the duration of storage, process and usage in addition to high strain rate triggering loads during drop-impact, vibration and shock. These electronic components may get exposed to high strain rates of 1 to 100 per seconds and operating temperature up to 200°C in the critical surroundings. SAC solder alloys (e.g. SAC-Q (CYCLOMAX), and Innolot) are being considered for use in fine-pitch electronic components. SAC-Q consists of Sn-Ag-Cu alloy in addition to Bi (SAC+Bi). The data presented till date for lead-free solders like SAC-Q alloy at high aging temperature and at high strain rate are for 50°C sustained exposure. In this paper, effect of sustained exposure of 100°C on high strain rate properties of SAC-Q is studied. Thermally aged SAC-Q samples at 100°C have been tested at a range of strain rates including 10, 35, 50, and 75 per second and operating temperatures starting from 25°C up to 200°C. Stress-strain curves are established for the given range of strain rates and operating temperatures. Also, the computed experimental results and data have been fit to the Anand Viscoplasticity model for SAC-Q for comparison.
Flexure and Twist Test Reliability Assurance of Flexible Electronics
Authors: Lall Pradeep , Narangaparambil Jinesh , Leever Ben , Miller Scott 
Published: December 2019

Abstract
Additively Printed Flexible electronics in wearable application may be subjected to twisting or flexing depending on the form factor and the location of use. There is a dearth of standards for testing and reliability assurance of flexible electronics and reliability data for various use conditions. In this paper, a test protocol has been developed for twisting and flexing on aerosol-jet additively printed flexible circuits. Test patterns with commonly used traces geometries have been developed, aerosol-jet printed, and thermally sintered at various conditions. Reliability data has been acquired under both twist and flex using resistance monitoring. Failure mechanisms have been studied for both deformation modes.
Parametric and Sensitivity Analysis of Power Module Design
Authors: Boteler L. M. , Fish M. C. , Berman M. S. 
Published: December 2019

Abstract
As technology becomes more electrified, thermal and power engineers need to know how to improve power modules to realize their full potential. Current power module technology involves planar ceramic-based substrates with wirebond interconnects and a detached heat sink. There are a number of well-known challenges with the current configuration including heat removal, reliability due to coefficient of thermal expansion (CTE) mismatch, and parasitic inductance. Various solutions have been proposed in literature to help solve many of these issues: alternate substrates, advanced thermal interface materials, compliant die attach, thermal ground planes, high performing heat sinks, superconducting copper, wirebondless configurations, etc. While each of these technologies have their merits, this paper will perform a holistic analysis on a power module and identify the impact of improving various technologies on the device temperature. Parametric simulations were performed to assess the impact of many aspects of power module design including material selection, device layout, and heat sink choice. Materials that have been investigated include die attach, substrate, heat spreader, and thermal interface materials. In all cases, the industry standard was compared to the state of the art to quantify the advantages and/or disadvantages of adopting the new technologies. A sensitivity analysis is also performed which shows how and where the biggest benefits could be realized when redesigning power modules and determining whether to integrate novel technologies.
Computational Form Factor Study of a 3rd Generation Open Compute Server for Single-Phase Immersion Cooling
Authors: Shah Jimil M. , Bhatt Chinmay , Rachamreddy Pranavi , Dandamudi Ravya , Saini Satyam , Agonafer Dereje 
Published: December 2019

Abstract
Networking and computing dependency has been increasing in the modern world, thus, boosting the growth of data centers in leading business domains like banking, education, transportation, social media etc. Data center is a facility that incorporates an organization’s IT operations and equipment, as well as where it stores, processes and manages the data. To fulfill the increasing demands of data storage and data processing, a corresponding increase in server performance is needed. This causes a subsequent increment in power consumption and heat generation in the servers due to high performance processing units. Currently, air cooling is the most widely used thermal management technique in data centers, but it has started to reach its limitations in cooling high packaging densities. Therefore, industries are looking for single-phase immersion cooling using various dielectric fluids to reduce the operational and cooling costs by enhancing the thermal management of servers. This research work aims at increasing the rack density by reducing the form factor of a 3rd Generation Open Compute Server using single-phase immersion cooling. A computational study is conducted in the operational range of temperatures and the thermal efficiency is optimized. A parametric study is conducted by changing the inlet velocities and inlet temperatures of cooling liquid for different heights of the open compute 3rd generation server. A comparative study is then carried out for white mineral oil and synthetic fluid (EC100).
Extensional tectonics rooted in orogenic collapse: Long-lived disintegration of the Semail Ophiolite, Oman
Authors: Braathen Alvar , Osmundsen Per Terje 
Published: December 2019

AbstractSignificant post-orogenic extension of the renowned Semail Ophiolite and substrata in Oman resulted in the formation of metamorphic core complexes juxtaposed with an array of Maastrichtian-Paleogene extensional basins. During this evolution, basins became progressively localized. The geometry of the large-scale and long-lived extensional system changes laterally across the core complexes and reveals several generations of domes and detachments, some of which were progressively exhumed. Progressive excision and dismemberment of the ophiolite link to major fabrics in the core complexes and gradual focusing of extensional basins.
Does general anesthesia affect neurodevelopment in infants and children?
Authors: McCann Mary Ellen , Soriano Sulpicio G 
Published: December 2019

AbstractGeneral anesthesia has been unequivocally linked to abnormal development of the central nervous system, leading to neurocognitive impairments in laboratory models. In vitro and in vivo studies have consistently shown that exposure to GABA agonists (eg, volatile anesthetics, midazolam, and propofol) or NMDA antagonists (eg, ketamine, isoflurane, and nitrous oxide) produces dose dependent and developmental age dependent effects on various neuronal transmission systems. Exposure to these drugs increases neuronal cell death in juvenile animals including rats, mice, and non-human primates. The possibility of anesthetic induced neurotoxicity occurring in children has led to concerns about the safety of pediatric anesthesia. A spectrum of behavioral changes has been documented after general anesthetic exposure in young children, including emergence delirium, which may be evidence of toxicity. Most clinical studies are retrospective; specifics about medications or monitoring are unavailable and many of the outcomes may not be sensitive to detect small neurocognitive deficits. Some of these retrospective studies have shown an association between anesthesia exposure at a young age and neurocognitive deficits, but others have not. Practitioners and families should be reassured that although general anesthetics have the potential to induce neurotoxicity, very little clinical evidence exists to support this.
Improved well-being and decreased disease burden after 1-year use of flash glucose monitoring (FLARE-NL4)
Authors: Fokkert Marion , van Dijk Peter , Edens Mireille , Barents Eglantine , Mollema Jeanine , Slingerland Robbert , Gans Reinold , Bilo Henk 
Published: December 2019

IntroductionThe FreeStyle Libre is a flash glucose monitoring (FSL-FGM) system. Compared with finger-prick based self-monitoring of blood glucose, FSL-FGM may provide benefits in terms of improved glycemic control and decreased disease burden.MethodsProspective nationwide registry. Participants with diabetes mellitus (DM) used the FSL-FGM system for a period of 12 months. End points included changes in HbA1c, hypoglycemia, health-related quality of life (12-Item Short Form Health Surveyv2(SF-12v2) and 3-level version of EuroQol 5D (EQ-5D-3L)), a specifically developed patient-reported outcome measures (PROMs) questionnaire, diabetes-related hospital admission rate and work absenteeism. Measurements were performed at baseline, and after 6 months and 12 months.Results1365 persons (55% male) were included. Mean age was 46 (16) years, 77% of participants had type 1 DM, 16% type 2 DM and 7% other forms. HbA1c decreased from 64 (95%CI 63 to 65) mmol/mol to 60 (95%CI 60 to 61) mmol/mol with a difference of −4 (95% CI −6 to 3) mmol/mol. Persons with a baseline HbA1c >70 mmol/mol had the most profound HbA1c decrease: −9 (95% CI −12 to to 5) mmol/mol. EQ-5D tariff (0.03 (95%CI 0.01 to 0.05)), EQ-VAS (4.4 (95%CI 2.1 to 6.7)) and SF-12v2mental component score (3.3 (95%CI 2.1 to 4.4)) improved. For most, PROMs improved. Work absenteeism rate (/6 months) and diabetes-related hospital admission rate (/year) decreased significantly, from 18.5% to 7.7% and 13.7% to 2.3%, respectively.ConclusionsReal world data demonstrate that use of FSL-FGM results in improved well-being and decreased disease burden, as well as improvement of glycemic control.