bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prediction of Failure at FCBGA Interfaces Under Thermo-Mechanical Loads Using a Competing Risk Cohesive Zone Model
Authors: Lall Pradeep , Pandurangan Aathi Raja Ram , Katsuri Madhu 
Published: November 2023

Abstract
Automotive under-the-hood electronics may reside on-engine, on-transmission, or in-wheel-well. Several high I/O advanced packaging architectures, including the flip-chip ball grid arrays (FCBGAs), enable much of the functionality. Underhood electronics in automobiles are an integral part of the critical and safety operations of the vehicle. Underfills significantly reduce the amount of plastic work during temperature excursions and offer mechanical support to the solder connections. One of the most common failure modes at chip/UF interfaces has been delamination. A critical characteristic in evaluating the chip/UF interfacial reliability is the interfacial fracture toughness of the chip/UF interfaces. The interfacial crack could rapidly spread to the solder joints, leading to system failure. The chip/UF interface properties may change over time in response to high-temperature exposure. In this study, bi-material specimens of Chip/UF interfaces have been fabricated and exposed to high temperatures of 100°C and 150°C for 30 days, 60 days, 90 days, 120 days, 180 days, 240 days, 300 days, and 360 days. The aged samples are subjected to four-point bend fatigue and monotonic loading. The interfacial fracture toughness values have been determined for each loading condition. The Paris constants (A, n) are computed from fatigue loading interfaces, which directly represent the evolution of interfacial properties with respect to sustained high-temperature exposure. A predictive finite element model of the FCBGA interfaces has been created.
A Comparative Data Center Energy Efficiency and TCO Analysis for Different Cooling Technologies
Authors: Heydari Ali , Eslami Bahareh , Chowdhury Uschas , Radmard Vahideh , Shahi Pardeep , Miyamura Harold , Tradat Mohammad , Chen Peter , Tuholski Drew , Gray Kevin , Buell Tyler , Stover Greg , Rodriguez Jeremy 
Published: November 2023

Abstract
Growth of data centers’ demand for electricity with respect to the energy cost emerges the need for more effective cooling solutions. This requirement necessitates a comprehensive assessment of each cooling technology in terms of their energy efficiency and economic performance. Here we developed a comparative analysis for four different cooling methods for a 1.7MW data center to indicate how the type and scale of the cooling technology impacts the total efficiency and costs. IT load is kept constant among all the four studies and only the cooling infrastructure configuration has been changed. Both air and hybrid (air-liquid) cooling are examined and for the liquid-cooled section, liquid-to-liquid (L2L), and liquid-to-air (L2A) coolant distribution units (CDU) are assessed at two levels of rack and row scale. Total Usage Effectiveness (TUE) and Total Cost of Ownership (TCO) results are presented for all different designs. The TCO calculations are divided into some subsections where costs for the primary and secondary side of the data center are specified. The capital cost for equipment, cooling units, preparation inside and outside of the data center, plumbing, installation, commissioning, and servicing etc. are considered while preparing the total cost for a particular cooling technology. Here, we considered N+1 redundancy for the cooling equipment on the secondary side and UPS system. The operation cost calculation includes the energy usage of the components inside and outside of the data center. Comprehensive analysis has been performed while transitioning from air cooling to hybrid cooling as efficiency of the components play an important role in determining the total power consumption. In this analysis, TCO modeling is facilitated with TUE number for cases being studied and power consumption from auxiliary components are included in the analysis. Results demonstrate a drop of 8.5% and 3.4% in total cooling energy usage and operating costs respectively due to the transition from air towards hybrid cooling. In the next step, the sensitivity of the TCO model to the type of coolant fluid and relevant thermohydraulic properties has been evaluated and presented. In the concluding phase, an optimization study was undertaken to illustrate the appropriate utilization of liquid cooling in order to achieve a design that is more economically efficient. This analysis aims to provide insights regarding the technological opportunities for further power and cost reductions for data center owners and highlight the most impactful parameters on both operational and capital costs. The outcome of this research demonstrates the actual cost per MW of IT which is a simple yet effective metric for each cooling architecture.
Impact of Component Interconnectivity on Mechanical and Electrical Properties of Flexible Hybrid Electronics with Printed Water-based Silver Ink Circuits
Authors: Lall Pradeep , Musa Fatahi , Soni Ved , Miller Scott 
Published: November 2023

Abstract
Flexible Hybrid Electronics (FHE) have the potential to revolutionize the electronics industry by providing sustainable and efficient devices. However, the reliable interconnectivity between printed traces and surface-mount devices (SMD) remains a critical challenge for FHE. There is a need for more research on the use of printed water-based silver ink traces and bonding materials for component attachment in FHE, as the literature on this subject is limited. This study was conducted to compare the effects of different bonding materials on component attachment. The bonding materials investigated were electrically conductive adhesive (ECA) and low-temperature solder (LTS). The study used the direct write method to print silver pads, which were then used to attach components such as resistors, inductors, and capacitors using the bonding materials. Electrically conducted adhesive (ECA) results were compared to those of Low Temperature Solder (LTS). The interconnectivity of the attached components was evaluated by measuring their rating values before and after attachment. The findings of this study provide insights into the performance of different bonding materials for component attachment in FHE. Such insights can aid in the development of reliable and efficient interconnectivity methods for FHE, which can contribute to the widespread adoption of FHE in various industries.
Effects of Grain to Sample Volume Ratio on the Deformation Behavior of Polycrystal SAC Samples Subjected to Shear Loads
Authors: Mondal Debabrata , Suhling Jeffrey C. , Mirkoohi Elham , Lall Pradeep 
Published: November 2023

Abstract
The study of size effects in electronic structural components and solders is important when dimensions are being continually downsized. It is crucial to obtain a constitutive model that describes material behavior of electronic package solders at small scales. Ample studies are available to describe the deformation behavior of SAC alloys at bulk level. For instance, stress-strain, creep, and shear behaviors have been investigated for bulk SAC samples. Although solder joints are very small in dimensions, most researchers have not explained the solder deformation considering size effects. With further miniaturization of solder joints in high density packaging, the localized material behavior can influence significantly the overall system. For instance, knowledge of individual grain properties of a crystalline materials is essential in determining material behavior of miniaturized products.
Sn-Ag-Cu (SAC) alloys are the most widely used lead-free materials to fabricate solder interconnects in microelectronic packaging. For most of the SAC alloys, more than 95% weight percentage is β-Sn which is a highly anisotropic material in terms of elastic modulus (E) and coefficient of thermal expansion (CTE). Moreover, due to the crystalline nature of β-Sn material, plastic deformation beyond the elastic limit is described by various atomic planes and directions, which are termed as slip systems. Ten different slip families with 32 slip systems have been recognized for β-Sn body-centered tetragonal (BCT) crystals. When external loads are applied on solder joints, plastic deformation is dictated by the movement of dislocations and direction of deformation is defined by slip systems.
When structural components are miniature in dimensions, crystal plasticity theory can accurately predict the material response considering crystallographic deformation mechanisms. In this study, a crystal plasticity-based DAMASK code was used to explain the mesoscale deformation behavior of polycrystal beta-tin samples. Polycrystalline beta-tin samples were obtained using Voronoi tessellation in NEPER with random grain orientations, which is the case for real samples. Shear simulations were performed for a sample with reasonably large number of grains. The model was then calibrated with experimental stress-strain data for a reflowed SAC305 alloy to determine a set of beta-tin slip properties. Subsequently, multiple polycrystalline models were generated with varying number of Sn grains, and a spectral solver was used to determine the sample responses under shear loads on three orthogonal planes. Samples with large number of grains exhibited isotropic deformation behavior. However, samples with fewer number of grains demonstrated anisotropic behavior. This study determined the overall average grain size to sample size ratio at which isotropic behavior breaks down under the application of shear loads.
Assessment of Effect of Operating Temperature on SAC-R Solders at High Strain Rates After Prolonged Storage
Authors: Lall Pradeep , Saha Mrinmoy , Suhling Jeff , Locker David 
Published: November 2023

Abstract
Electronic components may be used continuously under high strain-rate loads, high ambient temperatures, and other conditions in the aerospace, military, automobile, space, and offshore oil industries. In addition, these components may be kept in uncontrolled climate enclosures before deployment. A long duration of storage has been found to cause the material characteristics of undoped SAC alloys to change, even at mild temperatures. To reduce the effects of aging, a number of dopants have been added to the compositions of SAC alloys. In this investigation, SAC-R, a doped SAC solder, has been stored at 50°C for a year before being put through high strain rate testing. Uniaxial tensile tests have been performed to determine the mechanical characteristics of SAC-R in samples that have aged for no aging and samples that have aged for up to 360 days. The experiment’s High and Low operating temperatures ranged from −65°C to 200°C. After computing the constants for the Anand Visco-Plasticity model using the experimental material data, the model’s predictions for the uniaxial tensile test were compared to the experimental data. In order to simulate the drop events using the Anand constitutive model, the material constitutive behavior has been implemented in a finite element framework. In order to track the course of damage in the solder interconnects, the plastic work per shock event has also been calculated. The shock event of a ball-grid array package on PCB assembly has been simulated using the constitutive model.
Evaluation of Additive Circuits Printed With Sustainable Aqueous Silver Inks Using Aerosol Jet Printing and Gravure Offset Printing and Investigation of Circuit Repairability
Authors: Lall Pradeep , Soni Ved , Miller Scott 
Published: November 2023

Abstract
Additive printed electronics, in particular, has been a rapidly advancing field, with applications that span from smart packaging to energy harvesting systems to healthcare devices to intelligent textiles. The basic building block of any flexible circuit created by these technologies is conductive ink. This ink typically comprises metal nanoparticles and several solvents. However, many of the solvents used in these inks are toxic substances or include volatile organic compounds (VOCs) that have a variety of negative effects on the environment and human health, including air pollution, smog, respiratory problems, health risks, and reduced air quality. Consequently, there is a strong push toward developing sustainable materials for use in products, including ink formulations with fewer toxic solvents. In this study, researchers investigate the use of two printing techniques, aerosol jet printing and gravure offset printing, to print full-wave rectifiers (AC to DC conversion) and Voltage bridge oscillators (DC to AC conversion) using commercially available aqueous silver ink. The performance of the additively printed circuits is compared to both theoretical values and to the same circuits printed using non-aqueous inks. Additionally, a switch-mode battery charging circuit has also been printed with a sustainable ink and its performance has been investigated.
Evaluation of Thermoformability of Additively Printed Circuits Printed Using Gravure Offset Printing Technique and Investigation of In-Mold Electronic Circuits
Authors: Lall Pradeep , Soni Ved , Narangaparambil Jinesh , Miller Scott 
Published: November 2023

Abstract
Throughout the past decade, the field of printed electronics has gained increased research impetus and has started to make entryways into the consumer electronics product market. The applications of additive printed electronics are numerous and range from healthcare devices and smart packaging to energy harvesting systems and intelligent textiles. Another novel application area for printed electronics is in-mold electronics (IME) which is a process that involves the integration of printed electronic circuits into injection-molded parts. In this process, electronic circuits are printed onto a thin, flexible substrate, such as polyethylene terephthalate glycol (PETG) or polycarbonate (PC), which is then thermoformed using a mold. The thermoformed sample is then overmolded with another thermoplastic which results is a single, integrated part that combines the functionality of the electronic circuit with the mechanical properties of the plastic part. Using IMEs offers several benefits such as weight and bulk minimization along with maintaining ergonomic design, which are important concerns in automotive design. In this study, additively printed lines have been printed using gravure offset printing technique on different substrates such as PETG and PC have been subjected to vacuum thermoforming wherein the substrates are heated to their heat deflection temperature and vacuum formed on an aluminum mold. The change in resistance of the lines pre- and post-thermoforming, as well as the effect of degree of material stretching of the substrate with different thermoforming parameters such as thermoforming temperature and thermoforming time has been studied. Finally, a component attachment study has been conducted for thermoformed circuits with a functional thermoformed full wave rectifier circuit demonstrator.
Development of Thermal Interface Materials Tape Using Vertically Aligned Copper Nanowire-PDMS Composites
Authors: Qiao Hansen , Jiang Katherine , Wei Tiwei , Lin Yujui , Perez Chris , Asheghi Mehdi , Goodson Kenneth 
Published: November 2023

Abstract
High-performance thermal interface materials (TIMs) are essential in reducing thermal resistances while accommodating thermal expansion mismatch between heat sources and heat sinks. Here, we utilize copper nanowires (CuNWs) to form an intrinsically conductive and mechanically compliant nanostructure infiltrated with polydimethylsiloxane (PDMS) \for additional protection and compliance. We previously fabricated the CuNWs TIMs by direct electroplating on a silicon substrate with severe limitations on application and cost for largescale manufacturing. Thus, it is desirable to develop a cost-effective process for the fabrication of CuNWs TIMs in a “tape” or “coupon” form factor that can be easily inserted and bonded between two substrates. In this work, we developed a novel fabrication process to produce a Sn (20μm)-Cu/Au(20μm)/CuNWs-PDMS(30μm)/Cu(20μm)-Sn (20μm) TIM in a tape form factor. This innovative process involves producing an ultra-smooth (20 nm RMS) sacrificial Au/Cu foil that is used to electroplate CuNWs, PDMS infiltration, and finally, Cu and Sn film overplating to form the final TIM “tape”.
Artificial Intelligence for Active Vibration Control Optimization on Smart Structures
Authors: Febvre Maryne , Rodriguez Jonathan , Chesne Simon , Collet Manuel 
Published: November 2023

Abstract
New meta-materials are developed with the usage of piezoelectric transducers’ networks. Within the number of controlling strategies for vibration mitigation, this study uses the classical derivative control law as a basis. As a preliminary study in optimization with AI, an automatic algorithm using Reinforcement Learning (RL) approached with Trust Region Policy Optimization (TRPO) tunes a controller on an experimental cantilever beam. The control law is a simple derivative feedback between two collocated piezoelectric transducers close to the beam-clamped end. The RL algorithm runs offline on an estimated model of the experimental setup. The study compares control tuning methods between Reinforcement Learning results and a classical published approach.
An Embedded System for Data-Based Self-Sensing in Shape Memory Alloy Wire Actuators
Authors: Koshiya Krunal Jagdishbhai , Rizzello Gianluca , Motzki Paul 
Published: November 2023

Abstract
Estimation of displacement of a Shape Memory Alloy (SMA) actuator from electrical properties, is one of the attractive attributes of SMA. To utilize this feature, it is necessary to model the correlation between electrical properties and strain of the wire. Identification of the relationship between resistance and displacement is not always straightforward in SMA actuators, as the complexity of the resistance-displacement characteristics may vary depending upon various factors, e.g., biasing mechanism, additional external loads, actuation frequency, as well as the electrical activation strategy for heating SMA wires. In this paper, we present an experimental setup that incorporates a spring-loaded SMA wire mechanism. Resistance across the SMA wire has been measured for different actuation frequencies. In general resistance behavior has been observed and analyzed, which motivates the use of data-based approaches for estimation of the displacement. Recurrent neural networks represent a possible solution for identifying the complex correlation between electrical input and displacement for different configurations of SMA-actuated systems. The displacement estimated by the trained model is then compared against the displacement measured by a laser displacement sensor, for validation purpose.
Directed Particle Motion Driven by Superimposed Two-Dimensional Traveling Waves
Authors: Rogers William C. , Albakri Mohammad I. , Tarazaga Pablo 
Published: November 2023

Abstract
Structure-borne traveling waves (SBTW) have been observed in nature as a source of propulsion and have been under study in recent years to drive particle motion. Experimental studies have found that steady-state SBTW can be excited in finite structures which are capable of driving propulsion. These SBTW have also been shown to provide the forces needed to drive the motion of particulates along the surface of the excited structure. The interest of this work is the trajectory of particulates when acted on by a novel combination of SBTW active in a thin plate. In previous work, individual traveling waves have been generated such that particulates were driven along an active material surface. But these studies have been focused on particulates reacting to individual SBTW. It has been shown that when two-dimensional traveling waves that propagate orthogonal to one another are superimposed, the resultant wave moves in a direction between that of the constituent waves. In addition to this, the direction of the resultant wave can be tuned by adjusting the relative amplitude and phase of the constituent SBTW. This work numerically examines the trajectory of particulates when acted upon by superimposed OTW. For this purpose, the Finite Element Method (FEM) is used to develop a model of a thin square plate with traveling waves generated using a two-mode excitation is developed. The particulates are then introduced to the system and assumed to have a mass sufficiently small so as not to influence the wave envelope. When different SBTW and superimposed OTW are generated in the plate, it is shown that the particulate can be made to move along the active surface with trajectories, depending on the excitation conditions and the friction coefficient between the particle and the plate. From this, it can be concluded that combinations of SBTW of this type can be tuned to drive controlled particle motion on an active surface.
Simulation and Parametric Analysis of Transducer Locations in a Realistic, Compartmental Force Sensing Total Knee Replacement
Authors: Hines Brandon D. , Anton Steven R. 
Published: November 2023

Abstract
Total knee arthroplasty is one of the most common orthopedic procedures performed in the United States. Though the success rate of the procedure is considerably high, a number of patients report some level of post-operative pain. A lack of an in vivo method for tracking forces and alignment presents the challenge of non-invasive, early diagnosis of potential failure mechanisms in total knee replacements (TKR). Our research group seeks to solve this problem by developing an in vivo sensing system which includes piezoelectric transducers to measure the location and magnitude of compartmental forces in a TKR. A challenge presented by this task is identifying transducer locations that minimize error in the sensed compartmental force locations over the duration of the total gait cycle. This study presents a parametric analysis to evaluate the performance of six piezoelectric transducers embedded in the polyethylene component of a TKR. The main phases of the gait cycle are the stance phase, in which the foot is in contact with the ground, and the swing phase, in which the foot has broken contact with the ground. We seek to simulate the behavior of a relevant point during the stance phase of the gait cycle, so the proposed parametric analysis simulates an axial force applied to the femoral component rotated at 14° which corresponds to the point of max load. The applied load is determined by a biomechanics model previously developed by our research group in OpenSim. The analysis computes the forces transmitted to each transducer which are used to calculate the location of compartmental forces applied through the femoral component to the polyethylene component. The parametric analysis aided in determining a transducer arrangement that minimized the deviation between “sensed” contact point location and true location with simulation number 26 demonstrating a minimum deviation of less than half a millimeter.