bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inelastic Thermal Stress Simulation for Si Chip and Insulator Around TSV in 3D SiP
Authors: Kinoshita Takahiro , Kawakami Takashi , Wakamatsu Takeshi , Shima Shunpei , Matsumoto Keiji , Kohara Sayuri , Yamada Fumiaki , Orii Yasumitsu 
Published: January 2014

Stresses and mechanical strength of brittle materials (Si chip and insulator) around TSV (Through Silicon Via) structures in 3D SiP (Three Dimensional System in Package) were discussed under device operation condition and reflow process condition by using a large scale simulator ADVENTURECluster®, which was based on FEM (Finite Element Method), for ensuring the reliability of 3D SiP.
In case of the device operation, the equivalent stress of TSV were lower than yield stress of copper, and the maximum principal stress of Si and insulator were also lower than its bending strength. In case of the reflow process, the equivalent stress of TSV were over the yield stress of copper, and the maximum principal stresses of Si and insulator were closed to its bending strength. In addition, steep stress elevations were shown at edge part of Si and insulator. It will be a singular stress field by stress concentration. Its stress singularity was evaluated and the local strength of Si chip and insulator was discussed.
Analysis of Single-Phase Multi-Layer Heat Sinks Using a Porous Media Approach: Influence of Spatially Varying Porosity
Authors: Podhiny John J. , Ortega Alfonso 
Published: January 2014

Prior analyses and experiments have demonstrated that varying or scaling the number of fluid channels in each layer of a stacked multi-layer heat sink yields distinct advantages over traditional single-layer designs which use channels with high aspect ratios. Specifically, a design which implements scaling in order to vary the porosity (or equivalently, the number of channels) from one layer to the next allows a given thermal performance to be realized at a lower pressure drop than the corresponding non-scaled design. While previous studies use porous media theory for their analytical foundation just as the current studies do, they also focused on heat exchangers with machined channels, and have consequently been limited to discrete variation of the porosity (or number of channels) in each layer. Extending this approach by allowing for continuous porosity variation provides a generalized and powerful design method for scaled multi-layer heat exchangers by mathematically modeling them using two-equation volume averaged quantities. This approach also yields insight into the fundamental design parameters which control the performance of this class of heat exchangers, and suggests that their performance-governing parameters are similar to those which govern fin performance.
This paper focuses primarily on the thermal behavior of these liquid cooled heat sinks which employ various scaling functions to define the spatial variation of porosity. Comparisons are made with available closed-form solutions as well as results available from prior studies of discretely-scaled designs. The results indicate that scaling laws which have not been investigated previously can likely yield further performance improvements relative to prior designs.
Impact of Cold Aisle Containment on Thermal Performance of Data Center
Authors: Muralidharan Bharathkrishnan , Shrivastava Saurabh K. , Ibrahim Mahmoud , Alkharabsheh Sami A. , Sammakia Bahgat G. 
Published: January 2014

The use of air containment systems has been a growing trend in the data center industry and is an important energy saving strategy for data center optimization. Cold Aisle Containment (CAC) is one of the most effective passive cooling solutions for high density heat load applications. Cold Aisle Containment provides a physical separation between the cold air and the hot exhaust air by enclosing the cold aisle, preventing hot air recirculation and cold air bypass. This separation provides uniform inlet air temperatures to the servers, which can further contribute to overall data center efficiency.
This paper includes the thermal test data for a data center lab with and without a CAC set up. The paper quantifies the thermal impact of implementing a CAC system over an open Hot Aisle/Cold Aisle (HA/CA) arrangement for three different cabinet heat load conditions at two different CRAC (Computer Room Air Conditioner) return air set point conditions. It studies the advantages of CAC over standard HA/CA arrangement. A case study has been presented showing a cooling energy savings of 22% with the use of a CAC system over a standard HA/CA arrangement.
Cooling Energy Reduction During Dynamically Controlled Data Center Operation
Authors: Parida Pritish R. , Chainer Timothy J. , Schultz Mark D. , David Milnes P. 
Published: January 2014

Data Center power usage has been growing rapidly as new internet applications are developed, requiring computing resources such as high-density cloud computing server farms. All of the electricity consumed by data centers is ultimately turned into heat. This heat is removed using fans, pumps, chillers and air conditioning equipment, which comprise roughly a quarter of the total data center power consumption.
As part of a US Department of Energy cost shared grant, a data center test facility was designed and constructed with the goal to demonstrate the potential to reduce cooling energy use to less than 5% of the total IT and facilities energy usage by utilizing liquid cooling of the electronics rack. The system was characterized to develop temperature-based energy-aware servo control algorithms for further cooling energy reductions. These algorithms were implemented to dynamically reduce the data center cooling power consumption while controlling to a specified temperature under varying outdoor temperature and workload conditions. This work illustrates the energy-centric controls that were implemented to achieve dynamic system control in the most energy efficient manner.
A Revised Anand Constitutive Model for Lead Free Solder That Includes Aging Effects
Authors: Motalab Mohammad , Basit Munshi , Suhling Jeffrey C. , Lall Pradeep 
Published: January 2014

Traditional finite element based predictions for solder joint reliability during thermal cycling accelerated life testing are based on solder constitutive equations (e.g. Anand viscoplastic model) and failure models (e.g. energy dissipation per cycle model) that do not evolve with material aging. Thus, there will be significant errors in the calculations with lead free SAC alloys that illustrate dramatic aging phenomena. In this study, we have developed a revised set of Anand viscoplastic stress-strain relations for solder that include material parameters that evolve with the thermal history of the solder material. The effects of aging on the nine Anand model parameters have been examined by performing stress-strain tests on SAC305 samples that were aged for various durations (0–6 months) at temperature of 100 C. The stress-strain data were measured at three strain rates (.001, .0001, and .00001 1/sec) and five temperatures (25, 50, 75, 100, and 125 C). The mechanical tests have been performed using both water quenched (WQ) and reflowed (RF) samples (two unique specimen microstructures). In the case of the water quenched samples, there is rapid microstructural transitioning during the brief time that occurs between placing molten solder into the glass tubes and immersing the tubes in water bath. On the other hand, the reflowed samples are first cooled by water quenching, and then sent through a reflow oven to re-melt the solder in the tubes and subject them to a desired temperature profile matching that used in PCB assembly.
As expected, the observed mechanical properties of water quenched samples were better (higher in magnitude) than the corresponding mechanical properties of the reflowed samples. Although the differences in elastic modulus between the water quenched and reflowed samples are small, significant differences are present for the yield and ultimate tensile stresses (for each aging condition). For both the water quenched and reflowed specimens, significant degradation of the mechanical properties has been observed with aging. Using the measured stress-strain and creep data, mathematical expressions have been developed for the evolution of the Anand model parameter with aging time. Our results show that 2 of the 9 constants remain essentially constant during aging, while the other 7 show large changes (30–70%) with up to 6 months of aging. The revised Anand constitutive equations for solder with aging effects have also been incorporated into commercial finite element codes (ANSYS and ABAQUS).
Aging Induced Mechanical Property Degradation and Microstructure Evolution of SAC+X Lead Free Solder Alloys
Authors: Cai Zijie , Suhling Jeffrey C. , Lall Pradeep , Bozack Michael J. 
Published: January 2014

The microstructure, mechanical response, and failure behavior of lead free solder joints in electronic assemblies are constantly evolving when exposed to isothermal aging and/or thermal cycling environments. In our prior work on aging effects, we have demonstrated that large degradations occur in the material properties (stiffness and strength) and creep behavior of Sn-Ag-Cu (SAC) lead free solders during aging. These effects are universally detrimental to reliability and are exacerbated as the aging temperature and aging time increases. Conversely, changes due to aging are relatively small in conventional Sn-Pb solders.
In our current work, we are exploring several doped SAC+X alloys in an attempt to reduce the aging induced degradation of the material behavior of SAC solders. The doped materials are lead free SAC solders that have been modified by the addition of small percentages of one or more additional elements (X). Using dopants (e.g. Bi, In, Ni, La, Mg, Mn, Ce, Co, Ti, Zn, etc.) has become widespread to enhance shock/drop reliability, wetting, and other properties; and we have extended this approach to examine the ability of dopants to reduce the effects of aging and extend thermal cycling reliability. In this paper, we concentrate on presenting the results for SAC+X (X = Zn, Co, Ni). The enhancement of aging resistance for the doped lead free solders was explored. Comparisons were made to the responses of non-doped SAC lead free solder alloys.
The effects of aging on mechanical behavior have been examined by performing stress-strain and creep tests on solder samples that were aged for various durations (0–6 months) at elevated temperature (100 °C). Variations of the mechanical and creep properties (elastic modulus, yield stress, ultimate strength, creep compliance, etc.) were observed and modeled as a function of aging time and aging temperature. Our findings show that the doped SAC+X alloys illustrate reduced degradations with aging for all of the aging temperatures considered. Also, the stress-strain and creep mechanical properties of doped solders are better than those of reference solders after short durations of aging. After long term aging, doped solder alloys were found to have more stable behaviors than those of the standard SAC alloys. A parallel microstructure study has shown that less degradation and coarsening of the phases occurs in doped solder materials relative to non-doped solders after severe aging.
Dynamic Modeling of a Two-Phase On-Chip Cooling System Applied on Parallel High Performance Microprocessors
Authors: Lamaison Nicolas , Marcinichen Jackson B. , Thome John R. 
Published: January 2014

Transient modeling and control of two-phase on-chip microevaporator cold plates of a liquid pump cooling cycle is studied. The purpose is to cool down multiple micro-processors in parallel and their auxiliary electronics (memories, DC/DC converters, etc.) in series. The cooling system is composed of multiple on-chip microevaporators in parallel, a condenser, a liquid accumulator, a liquid pump and all piping joining these components. In order to achieve high heat transfer and chip temperature uniformity, two-phase flow of HFC134a is considered for the coolant. The dynamics of the system are relevant aspects to be studied since the heat dissipated by the microprocessors is changing continuously. Thus, a new simulation code has been developed here to emulate the operation during transients. Such transient simulations allow us to verify whether critical heat flux (CHF) conditions are reached during heat load disturbances and to track the available heat at the condenser for energy recovery purposes.
Presently, a case study with four microprocessors cooled in parallel flow is simulated considering different levels of uniform heat flux (36, 30, 25 and 10 Wcm−2), which showed the robustness of the predictive-corrective solver used. For a desired exit mixing vapor quality of 30%, at an inlet pressure and subcooling of respectively 16 bar (saturation temperature of 57.9 °C) and 2 K, the resulting distribution of the mass flow rates in the microevaporators were 3.6, 4.0, 4.5 and 7.4 kg/h (largest flow rate for lowest heat load) and the total pressure drop over the entire section was 0.6 kPa. The CHF and maximum chip temperature remained below of the critical limits. Preliminary comparisons with experimental tests showed errors in the predictions of mean chip temperature and mixing vapor quality to be within ±10%.
Improved Cooling of Electromagnetics by Directed Airflow
Authors: Downing Scott , Fain Adam , Majumdar Pradip 
Published: January 2014

The transformers in aircraft power conversion are often very heavy and represent a significant fuel or range penalty. Being thermally sized, improved cooling methods would allow downsizing and thereby reduced weight. Since the conductive paths in these metal “dense” devices are good, the controlling thermal resistance is typically the convective coefficient. The goal of this study was to optimize the convective air cooling across transformers by parametrically testing candidate shroud geometries to minimize average and hot spot surface temperatures with minimal fan power. Experimental results from a low velocity wind tunnel were well correlated by CFD modeling, providing confidence in continued shroud development with only CFD or experimentally. A simple cubic test block was selected as surrogate to generalize and simplify both test methods and results. A new “goodness” parameter was developed that included both the heat transfer performance and pressure penalty for a comparative index of shroud designs.
The work was divided into two phases. Phase-A used numerical modeling to study a variety of different shapes to select the best for experimental testing. Phase-B included the testing and further parametric evaluation with CFD studies. A parameter was developed that quantified the effect of conductive spreading on the test article surface.
Presented here are the results of these studies, where several general shroud shapes emerged as high performance in comparative evaluation. Following the down select, specific geometrical dimensions relative to the duct and mock transformer sizes were further optimized.
Highly Manufacturable and Reliable CZT Detectors
Authors: Burdick Bill , Erlbaum Jeff , Nagarkar Kaustubh , Yanoff Brian , Yin Liang , Bahadur Raj , Heidari Esmaeil , Sherman Donna , Simpson James E. 
Published: January 2014

Cadmium Zinc Telluride (CZT) based radiation detectors have been developed over the past decade and are, increasingly, being used in security and healthcare applications. Improvements in radiation detector performance, size, and cost have been achieved; however, the manufacturability and reliability of the individual CZT detector package continues to limit widespread use and new applications.
To date, most CZT detector packages are designed, manufactured, and tested to requirements defined by manufacturers, rather than military, commercial, or industry standards, as is common for semiconductor packages. The lack of test standards has led to use restrictions and/or complex detector system design, as required to mitigate unknown or low detector package reliability. CZT detector packaging, as was the case for semiconductor packaging, has reached the point in technology maturation where a focus on optimizing detector design for manufacturability and reliability is appropriate and necessary.
This paper reviews the systematic approach, including design, process development, and testing, utilized in the development and demonstration of a highly manufacturable and reliable (95% reliability at 1000 cycles) CZT detector package. Finite Element Model (FEM) based design and material trade-off studies, development of highly manufacturable and reliable commercial electronic assembly processes, failure mode identification and mitigation, selection and use of reliability test standards, and analyses are detailed for a flip-chip-CZT-on-ceramic substrate, detector package targeted for field deployment. As well, the next steps in package and system design, manufacturing, and reliability testing are proposed.
Geohazard Prevention and Pipeline Deformation Monitoring Using Distributed Optical Fiber Sensing
Authors: Ravet Fabien , Borda Carlos , Rochat Etienne , Niklès Marc 
Published: January 2014

The present work introduces the technology background at the origin of FOPIMS (Fiber Optic Pipeline Integrity Monitoring Systems) with an emphasis on geotechnical monitoring. It shows how temperature sensing can be implemented to control soil erosion or dune migration through event localization and spatial quantification. Arctic pipeline monitoring project illustrates the application of soil erosion detection. Direct measurement of strain in soil also enhances environmental threat detection. Combined with temperature sensing, strain sensing composes the geotechnical monitoring system. Transandean pipeline monitoring examples are presented where the DITEST AIM was implemented for geohazard prevention. These study cases concern new pipeline installation as well as retrofit of existing lines. The technique successfully evidenced early events and allowed preventive measures to be taken.
In some applications actual pipeline deformation need to be monitored. Such operation is achieved by measuring distributed strain along sensing cables attached to the structure. We show how such measurements complement the geotechnical measurements. We also describe a real implementation in seismic active area.
As a whole, the work focuses on the technique principles, the installation and how the system is being implemented for pipeline preventive maintenance. We intend to present a comprehensive set of design guidelines based on real results and lessons learned from the various projects in what concerns geohazard detection and pipeline deformation monitoring.
Emergency Actions for Containing Side Slope to the Pipeline Range
Authors: Varanda Erica , Soares José Pereira , Leite Roberta Amorim 
Published: January 2014

After a period of heavy rainfall, the landslide of a mass of residual soil in the side slope to the Pipeline Range of PETROBRAS occurred, in which two oil pipelines and gas pipeline connecting a terminal to a refinery.
On the day following the event in field inspection performed by the TRANSPETRO team, it was found that due to the landslide, the gas pipeline was exposed, with a Section of approximately 8.0 meters apparent in a slope at risk of undergoing deformations with the movement of unstable soil.
In the course of the inspection several indications soil movement were observed, such as cracks in the ground, breaks and located cracks in reinforced concrete structures of the drainage system. Surge flow of water or soil saturation was not found, despite the high rate of rainfall during the period. Thus one ruled out the possibility of the presence of a high water table which could have caused sliding. It is assumed that this may have begun on lower slopes due to deficiencies in the surface drainage system, which caused the accumulation of rainwater and its collapse. Hence, ruptures allegedly have occurred progressively upstream until it reaches the side of the pipeline range.
To ensure the integrity of the gas pipeline and operational safety and prevent the evolution of the incidents with more serious consequences, a contingency group responsible for coordinating emergency actions to contain the slope and protecting the pipeline exposed was called.
The first actions consisted of protecting the slope using a plastic tarpaulin to prevent the infiltration of more rainwater, metal profile riveting to contain side soil movement to the pipelines and finally to the implementation of contention with soil nailing technique with shotcrete on the surface of the slope where the pipeline was exposed found. Repairs to the surface drainage system of the range and slopes, which had been damaged during landslide were made.
In parallel to emergency actions, a campaign of geotechnical surveys using Standard Penetration Test (SPT) aiming at providing grounds for stability studies for the preparation of final stabilization project of the slope.
Integral Management of Risk: From a Corrective to a Preventive Approach
Authors: Oliveros Montes Edward Francisco , Leynaud Favian Gustavo Luis 
Published: January 2014

The Camisea Pipeline Transmission System (PTS) in Peru consists of two parallel pipelines, a Natural Gas (NG) pipeline and a Natural Gas Liquids (NGL) pipeline. The NG pipeline is 834 km long, including a 105 km loop. The NGL pipeline is 557 km long.
Since 8 years ago and as a part of the current operation of the system, maintenance activities are being carried which, within its objectives for improvement, seek to establish a preventive approach instead a corrective approach. The involved areas in this new Management approach are geo-technics, pipelines, environment, communities and integrity.
This paper describes the process named Integral Plan for Operating Risks. This process is a result of the updating of the geological-geotechnical base-line, in relation to the environmental and social context, allowing a comprehensive analysis of the status of the relation between the works and its environment, as well as planning prevention tasks able to guarantee the stability of the right of way (RoW) and the pipeline Integrity. This job is performed by both desk work (remote interpretation) and field work conducted by multidisciplinary teams, which ensures a transverse communication flow. All of this is backed by a digital database and a geographical information system (GIS). A Technical Atlas is constructed as a graphic document containing a series of cartographic and text cards regarding the sector under study as a useful instrument of preventive management for intervention in a given area.
To date, a comprehensive remote analysis of the RoW has been completed and an in-site field analysis has started, upon which strategies are being developed in order to control items such as geological hazards, geological architecture, vegetation architecture, RoW stability, etc. Jobs were competed along the first 12 km as a pilot experience, which is being replicated all along the RoW.