Underfill Filler Settling Effect on the Die Backside Interfacial Stresses of Flip Chip Packages

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Cheng-fu Chen ◽  
Pramod C. Karulkar
Keyword(s):  
Flip Chip ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Local Concentration ◽  
Case Scenario ◽  
Interfacial Shearing Stress ◽  
Worst Case ◽  
Interfacial Stresses ◽  
Filler Volume Fraction ◽  
Filler Particles

Underfill is usually modeled as an isotropic medium containing uniformly distributed filler particles. However, filler particles tend to settle (or segregate) and thus alter the mechanical response of the flip chip die attachment package. The integrity of such flip chip attachment is different from that with an ideal, isotropic underfill with very uniform distribution of filler. We analyzed the thermomechanical implications of filler settling to the stresses along the die/underfill interface by considering different profiles for the local concentration of filler and calculating their effective material properties by employing the Mori–Tanaka method. As the worst-case scenario, direct silicon die attach with solder bumps was assumed to analyze the interfacial stresses, which were predicted in trend by a simplified multilayered stack model and calculated in detail by finite element simulation. The filler settling has a localized but strong influence on the interfacial peeling stress near the edge of the die. The extent of this influence is determined by the profile of filler settling: (1) if the filler is assumed to settle in the form of a bilayer, then the peeling stress near the die’s edge increases and it is directly proportional to the average volume fraction of the filler; (2) if the filler is assumed to settle gradually, then the magnitude of the peeling stress near the edge of the die becomes smaller as the local filler volume fraction near the die interface increases. The filler settling has no significant effect on the other components of the interfacial stresses. The edge fillet of underfill in pure resin can locally reverse the direction of the interfacial peeling stress and increase the interfacial shearing stress near the die’s edge.

scholarly journals A Thermally Conductive Pt/AAO Catalyst for Hydrogen Passive Autocatalytic Recombination

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 491
Author(s):  
Alina E. Kozhukhova ◽  
Stephanus P. du Preez ◽  
Aleksander A. Malakhov ◽  
Dmitri G. Bessarabov
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Combustion Temperature ◽  
Volume Fraction ◽  
Morphological Characteristics ◽  
Al Alloy ◽  
Impregnation Method ◽  
Case Scenario ◽  
Worst Case ◽  
Thermal Distribution

In this study, a Pt/anodized aluminum oxide (AAO) catalyst was prepared by the anodization of an Al alloy (Al6082, 97.5% Al), followed by the incorporation of Pt via an incipient wet impregnation method. Then, the Pt/AAO catalyst was evaluated for autocatalytic hydrogen recombination. The Pt/AAO catalyst’s morphological characteristics were determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The average Pt particle size was determined to be 3.0 ± 0.6 nm. This Pt/AAO catalyst was tested for the combustion of lean hydrogen (0.5–4 vol% H2 in the air) in a recombiner section testing station. The thermal distribution throughout the catalytic surface was investigated at 3 vol% hydrogen (H2) using an infrared camera. The Al/AAO system had a high thermal conductivity, which prevents the formation of hotspots (areas where localized surface temperature is higher than an average temperature across the entire catalyst surface). In turn, the Pt stability was enhanced during catalytic hydrogen combustion (CHC). A temperature gradient over 70 mm of the Pt/AAO catalyst was 23 °C and 42 °C for catalysts with uniform and nonuniform (worst-case scenario) Pt distributions. The commercial computational fluid dynamics (CFD) code STAR-CCM+ was used to compare the experimentally observed and numerically simulated thermal distribution of the Pt/AAO catalyst. The effect of the initial H2 volume fraction on the combustion temperature and conversion of H2 was investigated. The activation energy for CHC on the Pt/AAO catalyst was 19.2 kJ/mol. Prolonged CHC was performed to assess the durability (reactive metal stability and catalytic activity) of the Pt/AAO catalyst. A stable combustion temperature of 162.8 ± 8.0 °C was maintained over 530 h of CHC. To confirm that Pt aggregation was avoided, the Pt particle size and distribution were determined by TEM before and after prolonged CHC.

scholarly journals Lossless WDM PON Photonic Integrated Receivers Including SOAs

2019 ◽  
Vol 9 (12) ◽  
pp. 2457 ◽  
Author(s):  
Goki ◽  
Imran ◽  
Porzi ◽  
Toccafondo ◽  
Fresi ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Wavelength Division Multiplexing ◽  
Flip Chip ◽  
Optical Network ◽  
Silicon On Insulator ◽  
Passive Optical Network ◽  
Case Scenario ◽  
Worst Case ◽  
The Impact ◽  
Wdm Transmission

The role of a semiconductor optical amplifier (SOA) for amplifying downstream traffic at optical network terminals (ONT) within a silicon-photonics integrated receiver in a high capacity passive optical network (PON) is investigated. The nearly traveling wave SOA effects are evaluated by considering fabrication and link loss constraints through numerical analysis and experimental validation. The impact of hybrid integration of a SOA chip on a silicon on insulator (SOI) photonic chip using the flip chip bonding technique on SOA design is evaluated through numerical analysis of a multi section cavity model. The performance of the proposed ONT receiver design employing twin parallel SOAs is evaluated experimentally on a 32 × 25 Gb/s OOK WDM transmission system considering cross gain modulation (XGM) and amplified spontaneous emission (ASE) constraints. The XGM impact is evaluated through 32 channel wavelength division multiplexing (WDM) transmission and a likely PON worst case scenario of high channel power difference (~10 dB) between adjacent channels. The impact of ASE is evaluated through the worst-case polarization condition, i.e., when all of the signal is coupled to only one. Successful transmission was achieved in both worst-case conditions with limited impact on performance. SOA results indicate that a maximum residual facet reflectivity of 4 × 10−4 for the chip-bonded device can lead to a power penalty below 2 dB in a polarization-diversity twin SOAs receiver.

Experimental and Numerical Simulation of Radiolysis Gas Detonations and Mechanical Response of BWR Exhaust Pipes

2010 ◽  
Author(s):  
M. Kuznetsov ◽  
R. Redlinger ◽  
W. Breitung ◽  
J. Grune ◽  
K. Sempert ◽  
...  
Keyword(s):  
High Pressure ◽  
Mechanical Response ◽  
Current Work ◽  
Maximum Pressure ◽  
Ambient Atmosphere ◽  
Exhaust Pipe ◽  
Case Scenario ◽  
Pressure System ◽  
Worst Case ◽  
Valve Opening

Radiolysis gas (2H2+O2) can accumulate in BWR steam piping in case of steam condensation. An ensuing detonation of the radiolysis gas is the likeliest cause of a pipe and/or valve damage. In the current work we investigate a typical BWR exhaust pipe, which connects the high pressure steam piping with the ambient atmosphere, under the following “worst case” scenario: (a) accumulation of radiolysis gas in an exhaust pipe, (b) fast valve opening to the high pressure system with steam at 70 bar, and (c) adiabatic pressurization of the radiolysis gas by the steam. Taking into account a water surface level of 6 m from the open end this leads to an equilibrium state of 20 bar pressure and 602 K temperature for the pressurized radiolysis gas. The main purpose of the current work was an experimental and numerical evaluation of the maximum pressure load and the integrity of the BWR exhaust pipe in case of a detonation of the pressurized radiolysis gas.

Compatibilized Polypropylene Hybrid Composites: Influence of Elastomeric Interlayers on Mechanical Properties and Nucleation Behaviour

1996 ◽  
Vol 8 (1) ◽  
pp. 97-108 ◽  
Author(s):  
Florian Stricker ◽  
Rolf Mülhaupt
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Hybrid Composites ◽  
Polarized Light ◽  
Thermoplastic Elastomers ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Filler Volume Fraction ◽  
Filler Particles ◽  
Means Of Transmission

Two families of polypropylene hybrid composites were prepared by simultaneously compounding polypropylene at 240°C together with SEBS thermoplastic elastomers and filler particles, for example, anisotropic talc and isotropic glass beads. Addition of SEBS was compared with that of maleic-anhydride-grafted SEBS (SEBS-g-MA) to study the role of SEBS compatibility with fillers, especially formation of elastomeric interlayers, on mechanical properties, morphology and nucleation behaviour. At a constant filler volume fraction of 10 vol.%, SEBS and SEBS-g-MA addition were varied between 0 and 20 vol.%. Due to coupling of amino groups at the glass-bead surface with succinic anhydride side chains of SEBS-g-MA, filler particles were encapsulated in a SEBS shell. The improved interfacial adhesion of SEBS-g-MA with respect to SEBS was reflected by higher yield stresses of the compatibilized hybrid composites. Such interlayers were detected by means of transmission electron microscopic imaging of thin sections of talc-based hybrid composites. Investigation of crystallization by means of polarized light microscopy revealed that elastomeric interlayer formation via in situ filler encapsulation markedly reduced filler-induced nucleation of polypropylene crystallization.

Reducing Probabilistic Weather Forecasts to the Worst Case Scenario: Anchoring Effects

2008 ◽  
Author(s):  
Sonia Savelli ◽  
Susan Joslyn ◽  
Limor Nadav-Greenberg ◽  
Queena Chen
Keyword(s):  
Case Scenario ◽  
Worst Case ◽  
Weather Forecasts ◽  
Worst Case Scenario ◽  
Anchoring Effects

EXPEDITION TO MALI, 2020

2020 ◽  
pp. 12-28
Author(s):  
D. V. Vaniukova ◽  
◽  
P. A. Kutsenkov ◽  
Keyword(s):  
Mass Murder ◽  
The State ◽  
Case Scenario ◽  
Worst Case ◽  
Traditional Art ◽  
Peter The Great ◽  
State Museum ◽  
Bobo Dioulasso ◽  
Oriental Studies ◽  
The Village

The research expedition of the Institute of Oriental studies of the Russian Academy of Sciences has been working in Mali since 2015. Since 2017, it has been attended by employees of the State Museum of the East. The task of the expedition is to study the transformation of traditional Dogon culture in the context of globalization, as well as to collect ethnographic information (life, customs, features of the traditional social and political structure); to collect oral historical legends; to study the history, existence, and transformation of artistic tradition in the villages of the Dogon Country in modern conditions; collecting items of Ethnography and art to add to the collection of the African collection of the. Peter the Great Museum (Kunstkamera, Saint Petersburg) and the State Museum of Oriental Arts (Moscow). The plan of the expedition in January 2020 included additional items, namely, the study of the functioning of the antique market in Mali (the “path” of things from villages to cities, which is important for attributing works of traditional art). The geography of our research was significantly expanded to the regions of Sikasso and Koulikoro in Mali, as well as to the city of Bobo-Dioulasso and its surroundings in Burkina Faso, which is related to the study of migrations to the Bandiagara Highlands. In addition, the plan of the expedition included organization of a photo exhibition in the Museum of the village of Endé and some educational projects. Unfortunately, after the mass murder in March 2019 in the village of Ogossogou-Pel, where more than one hundred and seventy people were killed, events in the Dogon Country began to develop in the worst-case scenario: The incessant provocations after that revived the old feud between the Pel (Fulbe) pastoralists and the Dogon farmers. So far, this hostility and mutual distrust has not yet developed into a full-scale ethnic conflict, but, unfortunately, such a development now seems quite likely.

Risk-Based Robust Bidding Strategies for EVs’ Aggregators in Day-ahead Markets with Uncertainty

2020 ◽  
Author(s):  
Ahmed Abdelmoaty ◽  
Wessam Mesbah ◽  
Mohammad A. M. Abdel-Aal ◽  
Ali T. Alawami
Keyword(s):  
Robust Optimization ◽  
Electricity Market ◽  
Real Life ◽  
Optimization Approach ◽  
Case Scenario ◽  
Worst Case ◽  
Bidding Strategies ◽  
Wind Generators ◽  
Proposed Model ◽  
Optimal Bidding

In the recent electricity market framework, the profit of the generation companies depends on the decision of the operator on the schedule of its units, the energy price, and the optimal bidding strategies. Due to the expanded integration of uncertain renewable generators which is highly intermittent such as wind plants, the coordination with other facilities to mitigate the risks of imbalances is mandatory. Accordingly, coordination of wind generators with the evolutionary Electric Vehicles (EVs) is expected to boost the performance of the grid. In this paper, we propose a robust optimization approach for the coordination between the wind-thermal generators and the EVs in a virtual<br>power plant (VPP) environment. The objective of maximizing the profit of the VPP Operator (VPPO) is studied. The optimal bidding strategy of the VPPO in the day-ahead market under uncertainties of wind power, energy<br>prices, imbalance prices, and demand is obtained for the worst case scenario. A case study is conducted to assess the e?effectiveness of the proposed model in terms of the VPPO's profit. A comparison between the proposed model and the scenario-based optimization was introduced. Our results confirmed that, although the conservative behavior of the worst-case robust optimization model, it helps the decision maker from the fluctuations of the uncertain parameters involved in the production and bidding processes. In addition, robust optimization is a more tractable problem and does not suffer from<br>the high computation burden associated with scenario-based stochastic programming. This makes it more practical for real-life scenarios.<br>

scholarly journals Modelling the Molecular Permeation through Mixed-Matrix Membranes Incorporating Tubular Fillers

Membranes ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 58
Author(s):  
Ali Zamani ◽  
F. Handan Tezel ◽  
Jules Thibault
Keyword(s):  
Aspect Ratio ◽  
Relative Permeability ◽  
Polymer Matrix ◽  
Volume Fraction ◽  
Mixed Matrix Membranes ◽  
Analytical Prediction ◽  
Mixed Matrix ◽  
Permeability Ratio ◽  
Filler Volume Fraction ◽  
Matrix Membranes

Membrane-based processes are considered a promising separation method for many chemical and environmental applications such as pervaporation and gas separation. Numerous polymeric membranes have been used for these processes due to their good transport properties, ease of fabrication, and relatively low fabrication cost per unit membrane area. However, these types of membranes are suffering from the trade-off between permeability and selectivity. Mixed-matrix membranes, comprising a filler phase embedded into a polymer matrix, have emerged in an attempt to partly overcome some of the limitations of conventional polymer and inorganic membranes. Among them, membranes incorporating tubular fillers are new nanomaterials having the potential to transcend Robeson’s upper bound. Aligning nanotubes in the host polymer matrix in the permeation direction could lead to a significant improvement in membrane permeability. However, although much effort has been devoted to experimentally evaluating nanotube mixed-matrix membranes, their modelling is mostly based on early theories for mass transport in composite membranes. In this study, the effective permeability of mixed-matrix membranes with tubular fillers was estimated from the steady-state concentration profile within the membrane, calculated by solving the Fick diffusion equation numerically. Using this approach, the effects of various structural parameters, including the tubular filler volume fraction, orientation, length-to-diameter aspect ratio, and permeability ratio were assessed. Enhanced relative permeability was obtained with vertically aligned nanotubes. The relative permeability increased with the filler-polymer permeability ratio, filler volume fraction, and the length-to-diameter aspect ratio. For water-butanol separation, mixed-matrix membranes using polydimethylsiloxane with nanotubes did not lead to performance enhancement in terms of permeability and selectivity. The results were then compared with analytical prediction models such as the Maxwell, Hamilton-Crosser and Kang-Jones-Nair (KJN) models. Overall, this work presents a useful tool for understanding and designing mixed-matrix membranes with tubular fillers.

scholarly journals A Comparison of Match Demands Using Ball-in-Play versus Whole Match Data in Professional Soccer Players of the English Championship

Sports ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 76
Author(s):  
Dylan Mernagh ◽  
Anthony Weldon ◽  
Josh Wass ◽  
John Phillips ◽  
Nimai Parmar ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Soccer Players ◽  
Training Methods ◽  
Case Scenario ◽  
Worst Case ◽  
Repeated Measures Design ◽  
Worst Case Scenario ◽  
Professional Soccer ◽  
Peak Match ◽  
Playing Time

This is the first study to report the whole match, ball-in-play (BiP), ball-out-of-play (BoP), and Max BiP (worst case scenario phases of play) demands of professional soccer players competing in the English Championship. Effective playing time per soccer game is typically <60 min. When the ball is out of play, players spend time repositioning themselves, which is likely less physically demanding. Consequently, reporting whole match demands may under-report the physical requirements of soccer players. Twenty professional soccer players, categorized by position (defenders, midfielders, and forwards), participated in this study. A repeated measures design was used to collect Global Positioning System (GPS) data over eight professional soccer matches in the English Championship. Data were divided into whole match and BiP data, and BiP data were further sub-divided into different time points (30–60 s, 60–90 s, and >90 s), providing peak match demands. Whole match demands recorded were compared to BiP and Max BiP, with BiP data excluding all match stoppages, providing a more precise analysis of match demands. Whole match metrics were significantly lower than BiP metrics (p < 0.05), and Max BiP for 30–60 s was significantly higher than periods between 60–90 s and >90 s. No significant differences were found between positions. BiP analysis allows for a more accurate representation of the game and physical demands imposed on professional soccer players. Through having a clearer understanding of maximum game demands in professional soccer, practitioners can design more specific training methods to better prepare players for worst case scenario passages of play.

scholarly journals Trissolcus japonicus (Hymenoptera: Scelionidae) Causes Low Levels of Parasitism in Three North American Pentatomids Under Field Conditions

2019 ◽  
Vol 19 (4) ◽  
Author(s):  
Joshua M Milnes ◽  
Elizabeth H Beers
Keyword(s):  
North American ◽  
Native Species ◽  
Classical Biological Control ◽  
The United States ◽  
Host Finding ◽  
Pest Species ◽  
Case Scenario ◽  
Worst Case ◽  
Egg Masses ◽  
Trissolcus Japonicus

Abstract Trissolcus japonicus (Ashmead), an Asian parasitoid of Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), was first detected in North America in 2014. Although testing in quarantine facilities as a candidate for classical biological control is ongoing, adventive populations have appeared in multiple sites in the United States, Canada, and Europe. Extensive laboratory testing of T. japonicus against other North American pentatomids and H. halys has revealed a higher rate of parasitism of H. halys, but not complete host specificity. However, laboratory tests are necessarily artificial, in which many host finding and acceptance cues may be circumvented. We offered sentinel egg masses of three native pentatomid (Hemiptera: Pentatomidae) pest species (Chinavia hilaris (Say), Euschistus conspersus Uhler, and Chlorochroa ligata (Say)) in a field paired-host assay in an area with a well-established adventive population of T. japonicus near Vancouver, WA. Overall, 67% of the H. halys egg masses were parasitized by T. japonicus during the 2-yr study. Despite the ‘worst case’ scenario for a field test (close proximity of the paired egg masses), the rate of parasitism (% eggs producing adult wasps) on all three native species was significantly less (0.4–8%) than that on H. halys eggs (77%). The levels of successful parasitism of T. japonicus of the three species are C. hilaris > E. conspersus > C. ligata. The potential impact of T. japonicus on these pentatomids is probably minimal.

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