Relevant bibliographies by topics / CTE mismatch

Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers
  5. Reports

Academic literature on the topic 'CTE mismatch'

Author: Grafiati
Published: 4 June 2021
Last updated: 8 February 2022

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Journal articles on the topic "CTE mismatch"

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YANG, CHEN, HUIQING FAN, SHAOJUN QIU, YINGXUE XI, and JIN CHEN. "EFFECTS OF THERMAL EXPANSION COEFFICIENT MISMATCH ON STRUCTURE AND ELECTRICAL PROPERTIES OF TiO2 FILM DEPOSITED ON Si SUBSTRATE." Surface Review and Letters 15, no. 04 (August 2008): 487–91. http://dx.doi.org/10.1142/s0218625x08011639.

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Effects of thermal expansion coefficient (CTE) mismatch on structure and electrical properties of TiO 2 film deposited on Si substrate by ion beam assistant electron beam evaporation have been investigated. Because of a high CTE mismatch between TiO 2 film and Si substrate, microcracks appeared in the TiO 2 film deposited directly on Si substrate after the as-deposited film was annealed at 600°C. In order to decrease the CTE mismatch, TiO 2 film was deposited on Si substrate which was covered by a ZrO 2 thin layer. As a result, crack–free TiO 2 film after annealed at the same temperature was obtained. Meanwhile, corresponding to the crack–free structure, the TiO 2 thin film has more stable dielectric properties and excellent I–V characteristics.
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Khaleque, Tasnuva, Xiaolong Zhang, Vijay Kumar Thakur, Adrianus Indrat Aria, and Hamed Yazdani Nezhad. "Tailoring of Thermo-Mechanical Properties of Hybrid Composite-Metal Bonded Joints." Polymers 13, no. 2 (January 6, 2021): 170. http://dx.doi.org/10.3390/polym13020170.

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Metallic substrates and polymer adhesive in composite-metal joints have a relatively large coefficient of thermal expansion (CTE) mismatch, which is a barrier in the growing market of electric vehicles and their battery structures. It is reported that adding carbon nanotubes (CNTs) to the adhesive reduces the CTE of the CNT-enhanced polymer adhesive multi-material system, and therefore when used in adhesively bonded joints it would, theoretically, result in low CTE mismatch in the joint system. The current article presents the influence of two specific mass ratios of CNTs on the CTE of the enhanced polymer. It was observed that the addition of 1.0 wt% and 2.68 wt% of multi-walled CNTs (MWCNTs) decreased the CTE of the polymer adhesive from 7.5×10−5 °C−1 (pristine level) to 5.87×10−5 °C−1 and 4.43×10−5 °C−1, respectively, by 22% and 41% reductions.
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Palmer, Michael J., R. Wayne Johnson, Mohammad Motalab, Jeffrey Suhling, and James D. Scofield. "Development of a Silicon Nitride High Temperature Power Module." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2011, HITEN (January 1, 2011): 000172–79. http://dx.doi.org/10.4071/hiten-paper7-rwjohnson.

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Silicon nitride (Si3N4) offer potential advantages as a substrate for high temperature power packaging. Si3N4 has higher fracture strength than alumina and aluminum nitride. The coefficient of thermal expansion (CTE) of Si3N4 is ~3 ppm/°C and the thermal conductivity ranges from 30–50W/m-K. Active metal brazed Cu-Si3N4 substrates are commercially available for power modules. However, the large mismatch in CTE between Si3N4 and Cu results in ceramic fracture and delamination with the wide temperature thermal cycling ranges encountered in high temperature applications. In this work Cu-Carbon and Cu-Mo metal matrix composites have been investigated to reduce the CTE mismatch. The process details are presented along with finite element modeling of the proposed structure. Ultimately, the proposed structure was unsuccessful.
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Chen, Cheng Gang, Kevin H. Hoos, and Ming Yung Chen. "Ceramic/Polymeric Hybrids with Reduced Coefficients of Thermal Expansion." Advances in Science and Technology 63 (October 2010): 120–25. http://dx.doi.org/10.4028/www.scientific.net/ast.63.120.

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The mismatch of the coefficient of the thermal expansion (CTE) is one of the main causes of crack initiation and delamination for carbon fiber-reinforced polymer hybrids and metal/polymer hybrid materials. In this research, a negative CTE ceramic material (zirconium tungstate) was incorporated with a thermoset polymer (bismaleimide) resulting in a ~40% reduction in CTE and a significant improvement in thermal stability. The morphology showed good dispersion of the zirconium tungstate particles within the bismaleimide. Comparisons of the experimental CTE values with the rule-of-mixture and the analytical micromechanical models will be discussed.
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Nomura, Shuhei, Shigeki Sawamura, Yu Hanawa, Yusuke Sakai, and Kazutaka Hayashi. "Novel glass substrates for minimizing thermal stress development during electronic device packaging process." International Symposium on Microelectronics 2016, no. 1 (October 1, 2016): 000607–11. http://dx.doi.org/10.4071/isom-2016-thp33.

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Abstract Glass can be utilized for support or career substrate in large size packaging process since it has excellent mechanical and optical properties. However, the thermal stress caused by a mismatch of coefficient of thermal expansion (CTE) causes an unneglectable warpage during a thermal process. In order to overcome this thermal stress issue, we have developed novel glasses that have finely tuned CTE characteristics to fit each packaging process. In this paper, we will report on a glass substrate whose CTE is perfectly matched with that of Si, and a series of glass substrates whose CTEs are controlled in sub-ppm order and within the range of 3.3 ~ 12.0 ppm/°C. To evaluate the effect of glass CTE on the thermal stress management, the warpage behavior of Si wafer after glass wafer bonding were investigated by both numerical simulation and experiment. Both results indicate that a small CTE mismatch can cause an unneglectable wafer warpage during the thermal process. Thus sub-ppm order control of glass CTE is essential for minimizing thermal stress development in large size packaging process. The glass substrate with Si matched CTE is suitable for the process where glass and Si are contact directly, e.g. Si back grinding process or through glass via (TGV) technology. The series of glass substrates whose CTEs are finely controlled in a high range are useful when the packaging process utilizes high amount of resins, such as Fan-Out wafer level packaging process.
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Bhatkal, Ravi M., Ranjit Pandher, Anna Lifton, Paul Koep, and Hafez Raeisi Fard. "Evaluating Thermal Cycling Fatigue Resistance for LED Chip-on-Board Applications." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2012, DPC (January 1, 2012): 000706–37. http://dx.doi.org/10.4071/2012dpc-ta43.

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LED chip-on-board applications typically involve assembling an LED die stack directly on to a high thermal conductivity substrate such as a Metal Core PCB. If solder is used for die-substrate attach for such chip-on-board applications, one needs to consider the CTE mismatch between the die stack and the MCPCB and its impact on thermal cycle-induced creep fatigue of the solder material. This paper presents a methodology to compare relative performance of different solder materials with varying thermo-mechanical properties, and compare the impact of CTE mismatch and temperature swings on transient thermal properties and relative reliability of the solder attach materials. Implications for LED chip-on-board applications are discussed.
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Park, Sang Hyun, Jin Ho Kang, Seoung Soo Lee, Yeon Gil Jung, and Ung Yu Paik. "Control of Shrinkage Behavior and Thermal Expansion Coefficient in BaTiO3-Added Ni Electrodes." Key Engineering Materials 336-338 (April 2007): 765–68. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.765.

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In this study, shrinkage behavior and coefficient of thermal expansion (CTE) of novel nickel (Ni) powder with an addition of dielectric material, BaTiO3, have been investigated to reduce the large shrinkage mismatch between Ni electrode and dielectric material and to control the thermal and/or residual stresses created by CTE mismatch in MLCCs (multilayer ceramic capacitors). For which two kinds of Ni powders were used. The component of Ni powders is analyzed by XRF, and the thermal behavior is measured by TG/DTA. The Ni and BaTiO3 powders were mixed with 9:1, 8:2, and 7:3 volume ratios. The BaTiO3-added Ni green bodies were fabricated through cold isostatic pressing, and then sintered to 1300°C in a reduction atmosphere. The shrinkage behavior with volume ratio was checked during sintering from 700 to 1300°C with 300°C interval. The CTE was measured in inert (argon) atmosphere with sintered samples. It is found that the shrinkage behavior and the CTE of Ni electrode are dependent on the volume of BaTiO3 added. The particle size of Ni powder also affects the microstructure and its sintering density, with less effect of its component.
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Sujan, D., X. B. Pang, M. E. Rahman, and M. M. Reddy. "Performance of Solder Bond on Thermal Mismatch Stresses in Electronic Packaging Assembly." Materials Science Forum 773-774 (November 2013): 242–49. http://dx.doi.org/10.4028/www.scientific.net/msf.773-774.242.

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Thermo-mechanical stresses have been considered one of the major concerns in electronic Packaging assembly structural failure. The interfacial stresses are often caused by the thermal mismatch stresses induced by the coefficient of thermal expansion (CTE) difference between materials, typically during the high temperature change in the bonding process. This research work examined the effect of bond layer on thermal mismatch interfacial stresses in a bi-layered assembly. The paper verified the existing thermal mismatch solder bonded bi-layered analytical model using finite element method (FEM) simulation. The parametric studies were carried out on the effect of change of bond layer properties in order to provide useful references for interfacial stress evaluation and the electronic packaging assembly design. These parameters included CTE, temperature, thickness, and stiffness (compliant and stiff bond) of the bond layer. The recent development on lead free bonding material was being reviewed and found to have enormous potential and key role to address the future electronic packaging assembly reliability.
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Kitazono, Koichi, Eiichi Sato, and Kazuhiko Kuribayashi. "Unified Constitutive Equation of CTE-Mismatch Superplasticity Based on Continuum Micromechanics." Materials Science Forum 357-359 (January 2001): 289–94. http://dx.doi.org/10.4028/www.scientific.net/msf.357-359.289.

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Morelock, Cody R., Matthew R. Suchomel, and Angus P. Wilkinson. "A cautionary tale on the use of GE-7031 varnish: low-temperature thermal expansion studies of ScF3." Journal of Applied Crystallography 46, no. 3 (April 6, 2013): 823–25. http://dx.doi.org/10.1107/s0021889813005955.

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GE-7031 varnish, a commonly used low-temperature adhesive and electrical insulator owing to its high thermal conductivity and mechanical strength at low temperatures, was used as a sample matrix for low-temperature powder X-ray diffraction measurements of the negative thermal expansion (NTE) material ScF3. When ScF3powder was mixed with GE-7031 varnish, an unexpected cubic to rhombohedral phase transition in the ScF3sample was observed at ∼50 K, and it exhibited smaller low-temperature unit-cell volumes than samples without the varnish matrix. Experimental observations and quantitative estimates suggest that these anomalies are the result of stress induced by a thermal expansion mismatch between the varnish matrix (large positive coefficient of thermal expansion, CTE) and ScF3(quite large negative CTE). The use of GE-7031 varnish as a sample matrix for low-temperature measurements should be approached with caution if a large thermal expansion mismatch is expected.
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Dissertations / Theses on the topic "CTE mismatch"

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Peter, Geoffrey J. M. "Numerical simulation of CTE mismatch and thermal-structural stresses in the design of interconnects /." Full text open access at:, 2001. http://content.ohsu.edu/u?/etd,235.

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Qin, Xian. "Compliant copper microwire arrays for reliable interconnections between large low-CTE packages and printed wiring board." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53532.

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The trend to high I/O density, performance and miniaturization at low cost is driving the industry towards shrinking interposer design rules, requiring a new set of packaging technologies. Low-CTE packages from silicon, glass and low-CTE organic substrates enable high interconnection density, high reliability and integration of system components. However, the large CTE mismatch between the package and the board presents reliability challenges for the board-level interconnections. Novel stress-relief structures that can meet reliability requirements along with electrical performance while meeting the cost constraints are needed to address these challenges. This thesis focuses on a comprehensive methodology starting with modeling, design, fabrication and characterization to validate such stress-relief structures. This study specifically explores SMT-compatible stress-relief microwire arrays in thin polymer carriers as a unique and low-cost solution for reliable board-level interconnections between large low-CTE packages and printed wiring boards. The microwire arrays are pre-fabricated in ultra-thin carriers using low-cost manufacturing processes such as laser vias and copper electroplating, which are then assembled in between the interposer and printed wiring board (PWB) as stress-relief interlayers. The microwire array results in dramatic reduction in solder stresses and strains, even with larger interposer sizes (20 mm × 20 mm), at finer pitch (400 microns), without the need for underfill. The parallel wire arrays result in low resistance and inductance, and therefore do not degrade the electrical performance. The scalability of the structures and the unique processes, from micro to nanowires, provides extendibility to finer pitch and larger package sizes. Finite element method (FEM) was used to study the reliability of the interconnections to provide guidelines for the test vehicle design. The models were built in 2.5D geometries to study the reliability of 400 µm-pitch interconnections with a 100 µm thick, 20 mm × 20 mm silicon package that was SMT-assembled onto an organic printed wiring board. The performance of the microwire array interconnection is compared to that of ball grid array (BGA) interconnections, in warpage, equivalent plastic strain and projected fatigue life. A unique set of materials and processes was used to demonstrate the low-cost fabrication of microwire arrays. Copper microwires with 12 µm diameter and 50 µm height were fabricated on both sides of a 50 µm thick, thermoplastic polymer carrier using dryfilm based photolithography and bottom-up electrolytic plating. The copper microwire interconnections were assembled between silicon interposer and FR-4 PWB through SMT-compatible process. Thermal mechanical reliability of the interconnections was characterized by thermal cycling test from -40°C to 125°C. The initial fatigue failure in the interconnections was identified at 700 cycles in the solder on the silicon package side, which is consistent with the modeling results. This study therefore demonstrated a highly-reliable and SMT-compatible solution for board-level interconnections between large low-CTE packages and printed wiring board.
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LeMasters, Jason Augustine. "Thermal Stress Analysis of LCA-based Solid Oxide Fuel Cells." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5220.

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This research characterizes the thermal stress resulting from temperature gradients in hybrid solid oxide fuel cells that are processed using a novel oxide powder slurry technology developed at Georgia Tech. The hybrid solid oxide fuel cell is composed of metallic interconnect and ceramic electrolyte constituents with integral mechanical bonds formed during high temperature processing steps. A combined thermo-mechanical analysis approach must be implemented to evaluate a range of designs for power output and structural integrity. As an alternative to costly CFD analysis, approximate finite difference techniques that are more useful in preliminary design are developed to analyze the temperature distributions resulting from a range of fuel cell geometries and materials. The corresponding thermal stresses are then calculated from the temperature fields using ABAQUS. This model analyzes the manufacturing, start-up, and steady state operating conditions of the hybrid solid oxide fuel cell.
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Zhang, Bochun. "Failure Mechanism Analysis and Life Prediction Based on Atmospheric Plasma-Sprayed and Electron Beam-Physical Vapor Deposition Thermal Barrier Coatings." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35709.

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Using experimentally measured temperature-process-dependent model parameters, the failure analysis and life prediction were conducted for Atmospheric Plasma Sprayed Thermal Barrier Coatings (APS-TBCs) and electron beam physical vapor deposition thermal barrier coatings (EB-PVD TBCs) with Pt-modified -NiAl bond coats deposited on Ni-base single crystal superalloys. For APS-TBC system, a residual stress model for the top coat of APS-TBC was proposed and then applied to life prediction. The capability of the life model was demonstrated using temperature-dependent model parameters. Using existing life data, a comparison of fitting approaches of life model parameters was performed. The role of the residual stresses distributed at each individual coating layer was explored and their interplay on the coating’s delamination was analyzed. For EB-PVD TBCs, based on failure mechanism analysis, two newly analytical stress models from the valley position of top coat and ridge of bond coat were proposed describing stress levels generated as consequence of the coefficient of thermal expansion (CTE) mismatch between each layers. The thermal stress within TGO was evaluated based on composite material theory, where effective parameters were calculated. The lifetime prediction of EB-PVD TBCs was conducted given that the failure analysis and life model were applied to two failure modes A and B identified experimentally for thermal cyclic process. The global wavelength related to interface rumpling and its radius curvature were identified as essential parameters in life evaluation, and the life results for failure mode A were verified by existing burner rig test data. For failure mode B, the crack growth rate along the topcoat/TGO interface was calculated using the experimentally measured average interfacial fracture toughness.
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Liu, An-Chan, and 劉安展. "The Effect of CTE Mismatch on Solder Ball in Optoelectronic Packaging." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/78891579405074011963.

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碩士
國立中山大學
機械與機電工程學系研究所
91
Two subjects are included in this thesis; one is to construct the Coffin-Manson equation of the unleaded SnAgCu solder according to the experimental results provided by the Metal Research Laboratory (MRL) of Industrial Technologies Research Institute (ITRI). The results of CSP thermal cycle fatigue and SOJ pull tests and the corresponding stress and strain distributions solved from FEM analyses have been used to derive the Coffin-Manson equation for the SnAgCu solder. The other subject is to investigate the effect of CTE mismatch on the fatigue life of solder balls in the opto-electronic packaging. The solidified shapes of the different solder balls after undergoing the re-flow process are predicted by employing the Surface Evolver package program. The FEA meshes of the solidified solder balls in opto-electronic packaging are built according to the output results of the Surface Evolver program. The maximum equivalent plastic shear strain range of the solder after under one thermal cycle process is calculated by employing the MARC finite element package. The fatigue lives of solder balls under different arrangements are estimated according to the proposed Coffin-Manson equation. The effect of solder ball parameters, i.e. solder volume, solder offset distance, solder DNP and solder material on the reliability of different solder balls has also been explored in this thesis.
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CHEN, LUNG-KAI, and 陳隆凱. "The Investigation of Delamination Caused by CTE Mismatch in Semiconductor IC Package." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/chw485.

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碩士
國立高雄大學
電機工程學系碩博士班
105
This research investigated the delamination of IC package caused by the coefficient of thermal expansion (CTE) of assembly material mismatch. In order to find a suitable material combination, leadframe products distributed by six assembly material combination were used in this study and the results were confirmed by the reliability test. Numerical analysis and experimental results show that the less stress differs at low and high temperatures between materials, the lower probability of delamination occurs. The results also exhibits that one set of the epoxy and film and compound resulted in the least delamination. This investigation shows that the match of CTE is a key factor to choose the assembled material in IC package.
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Book chapters on the topic "CTE mismatch"

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Utrilla Fernández-Bermejo, Dolores. "The Council of Europe as a Source of General Principles of Good Administration in Spain." In Good Administration and the Council of Europe, 403–28. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198861539.003.0016.

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This chapter discusses the impact on Spanish administrative law of the pan-European principles of good administration developed by the Council of Europe (CoE). It reveals the prominent role of the CoE in Spain’s transition to democracy after Franco’s death on 20 November 1975. Today, while there is generally no conceptual mismatch between Spanish administrative law and the said principles, their impact is fragmentary and sector-based, rather than comprehensive and systematic. Whereas in areas such as local self-government this impact appears to be high, elsewhere it has been either overshadowed by EU law or the already existing comprehensive domestic legal framework and, hence, very indirect.
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Ernits, Madis, and Karmen Pähkla. "Europeanization through Constitutionalism." In Good Administration and the Council of Europe, 536–59. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198861539.003.0021.

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This chapter discusses the impact on Estonian administrative law of the pan-European principles of good administration developed by the Council of Europe (CoE). It argues that there is no conceptual mismatch between Estonian law and the administrative law of the CoE. This is attested by the fact that the European Convention on Human Rights was one of the main models for the constitutional rights chapter of the Estonian Constitution and remains widely discussed in the case law of Estonian courts. Moreover, the laws on the general part of Estonian administrative law—the Administrative Procedure Act and State Liability Act of 2001—among other things, have been guided by the pan-European principles of good administration. At the same time the chapter expresses doubts regarding the significance of the soft law sources of the CoE because of the principle of legality prevalent in Estonian law, which presents a hindrance to their permeation.
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Zhu, Shenglong, and Fuhui Wang. "Nanocrystalline, Enamel and Composite Coatings for Superalloys." In Production, Properties, and Applications of High Temperature Coatings, 160–86. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-4194-3.ch007.

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This chapter describes several innovations for improving the performance of high-temperature coatings. Nanocrystallization has been demonstrated to be a practical way to prolong the lifetime of high temperature coatings by decreasing the minimum Al concentration for sustaining the growth of thermally grown oxide (TGO) scales, and increasing the resistance against scale cracks and spallation. Enamel coatings with enhanced strength, toughness and thermophysical properties were developed for improving the hot corrosion resistance of superalloys. Low expansion nanocomposite coatings minimize the mismatch between coefficients of thermal expansion (CTEs) of the TGO scales and the underlying coatings, so allow growth of thicker TGO scales free of cracks and spallation and then prolong the lifetime.
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Morgan, Oliver. "Conclusion." In Turn-taking in Shakespeare, 249–60. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198836353.003.0009.

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This chapter examines the implications the turn-taking approach for our understanding of early modern performance practices. On the one hand, Shakespearean dialogue is full of subtle effects of timing and sequence that would seem to call for careful rehearsal and a detailed knowledge of the script. On the other hand, everything we know about early modern theatre suggests it was performed with minimal rehearsal by actors who did not necessarily know when, or from where, their next cue would arrive. This apparent mismatch I call ‘the performability gap’. The question is how it can be bridged. The explanation provided by Simon Palfrey and Tiffany Stern—that Shakespeare’s plays are designed to make artistic capital from their own under-rehearsal—does not entirely solve the problem. The second half of the chapter speculates about how else we might account for the gap.
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Conference papers on the topic "CTE mismatch"

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Swank, W. D., R. A. Gavalya, J. K. Wright, and R. N. Wright. "Residual Stress Determination from a Laser-Based Curvature Measurement." In ITSC 2000, edited by Christopher C. Berndt. ASM International, 2000. http://dx.doi.org/10.31399/asm.cp.itsc2000p0363.

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Abstract Thermally sprayed coating characteristics and mechanical properties are in part a result of the residual stress developed during the fabrication process. The total stress state in a coating/substrate is comprised of the quench stress and the coefficient of thermal expansion (CTE) mismatch stress. The quench stress is developed when molten particles impact the substrate and rapidly cool and solidify. The CTE mismatch stress results from a large difference in the thermal expansion coefficients of the coating and substrate material. It comes into effect when the substrate/coating combination cools from the equilibrated deposit temperature to room temperature. This paper describes a laser-based technique for measuring the curvature of a coated substrate and the analysis required to determine residual stress from curvature measurements. Quench stresses were determined by heating the specimen back to the deposit temperature thus removing the CTE mismatch stress. By subtracting the quench stress from the total residual stress at room temperature, the CTE mismatch stress was estimated. Residual stress measurements for thick (>1mm) spinel coatings with a Ni-Al bond coat on 304 stainless steel substrates were made. It was determined that a significant portion of the residual stress results from the quenching stress of the bond coat and that the spinel coating produces a larger CTE mismatch stress than quench stress.
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Wen, Edward, Ever Barbero, and Philip Tygielski. "Autofrettage to Offset CTE Mismatch in Metal-Lined Composite Cryogenic Feed Lines." In 43rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2002. http://dx.doi.org/10.2514/6.2002-1524.

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Nakamura, Yukio, Kenichi Oohashi, Koji Morita, Shuji Nomoto, Takayuki Suzuki, Shin Takanezawa, Shinji Tsuchikawa, and Masaaki Takekoshi. "New Super-Low CTE (0.7 ppm/K) Core Material for Next Generation Thin CSP." In ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ipack2015-48836.

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The thinner and higher density PKG (package) is being required strongly for the growth of smaller mobile devices. Especially, package on package technology (PoP) has become a mainstream for application processors which are installed in smartphones and tablets. However, the warpage of thinner PKG often causes a problem at the chip mounting process. The main factor of warpage is the mismatch of CTE (coefficient of thermal expansion) between substrate and chip. Therefore, the lower CTE core materials are needed for the thinner PKG. Recently, Hitachi Chemical has developed the super-low CTE material, core and prepreg, applying our new resin system and filler treatment technology, and placed it on the market. Furthermore, a super-low CTE material of 0.7 ppm/K is currently under development. The super-low CTE material shows the best warpage performance in our low CTE core material lineups, maintaining its higher Tg, high modulus and low Dk/Df values.
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Mori, Hiroyuki, Sayuri Kohara, Keishi Okamoto, Hirokazu Noma, and Kazushige Toriyama. "Effects of Low CTE Materials on Thermal Deformation of Organic Substrates in Flip Chip Package Application." In ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ipack2015-48741.

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Coefficient of thermal expansion (CTE) characteristic of organic materials for substrates in flip chip package application demanded by semiconductor package requirements is becoming lower than ever. In general, height restrictions are imposed on package-on-package (PoP) devices in mobile applications. One should hence establish a tight budget on the height variation in manufacturing of the devices. Given such background, a lowering of the CTE characteristic of package substrates is an attractive solution for reducing package deformation upon manufacturing, since it contributes to minimize CTE mismatch of the substrates with silicon chips. In large-die flip chip applications such as high-end processors, a lower CTE substrate can mitigate mechanical stress not only on low-k layers in back end of the line (BEOL) underneath the chip bumps, but also on underfill layers during thermal cycling. Therefore an introduction of lower CTE materials in organic substrates is becoming essential for future applications of electronic devices. In this paper, thermal deformation behaviors of organic substrates associated with lowering of the CTEs of their constituent materials are analyzed by finite element analysis (FEA). The analyses are done on a 3-2-3 build-up layer structure substrate in order to focus onto typical application specific integrated circuit (ASIC) products. A finite element model for a test substrate is constructed by a method in which the substrate is divided into sections according to its circuitry patterns so that the lateral inhomogeneity of mechanical property is taken into account. The finite element analyses using the model showed that the package warpage decreases with lowering of the effective CTE of the substrate, but the warpage of the substrate itself increases and its surface profile changes from a concave shape to a convex shape. The analysis result of substrate warpage variation with the build-up material’s CTE showed that the selection of build-up materials with appropriate material properties can contribute to reduce the substrate warpage. The analysis also showed that the adverse impact to the substrate’s CTE reduction by such material selection is limited.
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Davis, Taryn J., Tuhin Sinha, Ken Marston, and Sushumna Iruvanti. "Effect of Temperature Cycling and High Temperature Aging on the Elastic Properties and Failure Modes of Thermal Interface Materials." In ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ipack2015-48712.

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Highly filled thermally conductive silicone gels are routinely used as first level thermal interface materials (TIMs) between the die and lid, in flip-chip organic packages. The main challenge for these TIMs is overcoming the Coefficient of Thermal Expansion (CTE) mismatch between the die and lid materials. The TIMs must maintain excellent adhesion to both the die and lid surfaces in order to achieve and maintain optimal thermal performance. The CTE mismatch leads to increased mechanical stress and degradation of the TIM, which in turn degrades the thermal performance. In this work, the effective modulus of several TIMs was calculated by finite element modeling (FEM) in concert with mechanical testing of thin bond-line aluminum-TIM sandwiches subjected to varied stress conditions. These results are correlated to the corresponding stress die shear testing and the impact on package performance is analyzed.
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6

Wang, Cun, Tao Zhang, Cheng Zhao, and Jian Pu. "Numerical Study of Thermal Stresses in a Planar Solid Oxide Fuel Cell Stack." In ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology collocated with the ASME 2017 Power Conference Joint With ICOPE-17, the ASME 2017 11th International Conference on Energy Sustainability, and the ASME 2017 Nuclear Forum. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/fuelcell2017-3176.

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A three dimensional numerical model of a practical planar solid oxide fuel cell (SOFC) stack based on the finite element method is constructed to analyze the thermal stress generated at different uniform temperatures. Effects of cell positions, different compressive loads, and coefficient of thermal expansion (CTE) mismatch of different SOFC components on the thermal stress distribution are investigated in this work. Numerical results indicate that the maximum thermal stress appears at the corner of the interface between ceramic sealants and cells. Meanwhile the maximum thermal stress at high temperature is significantly larger than that at room temperature (RT) and presents linear growth with the increase of operating temperature. Since the SOFC stack is under the combined action of mechanical and thermal loads, the distribution of thermal stress in the components such as interconnects and ceramic sealants are greatly controlled by the CTE mismatch and scarcely influenced by the compressive loads.
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Hong, Jupyo, Shan Gao, Job Ha, Sijoong Yang, Ingoo Kang, Taehoon Kim, Seogmoon Choi, and Sung Yi. "Design Optimization of a Wafer Level Package for Surface Acoustic Wave Filters." In ASME 2007 InterPACK Conference collocated with the ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ipack2007-33031.

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In this paper, wafer level packaging of a surface acoustic wave (SAW) filter is considered. Numerical studies based on a three-dimensional finite element method (FEM) have been conducted in order to evaluate the reliability of a wafer level SAW package. The effects of package geometric parameters, such as the diameter of via hole and wafer thickness, on the reliability of the wafer level SAW package have been studied. The results show that the diameter of via hole for interconnection plays a key role in the reliability of the SAW package because the CTE mismatch between the filling materials of via holes (copper) and surrounding cap wafer martial (LiTiO3) is the highest among the material pairs in the package. Such CTE mismatch leads to the maximum stresses and warpages. The optimal thermo-mechanical properties of packaging materials have been proposed to achieve the minimum thermal stress during reflow process. Moreover, numerical results have also been compared with the experimental ones to validate the FEM model.
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Klein, Kevin M., and Suresh K. Sitaraman. "Compliant Stress-Engineered Interconnects for Next-Generation Packaging." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-61990.

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Future demands of microelectronic packing include increasing input/output (I/O) densities, providing high frequency capabilities, and maintaining sufficient reliability while keeping costs minimal. Organic materials with Coefficients of Thermal Expansions (CTE) over four times greater than silicon will continue to be used as future substrate materials because of their low cost. Consistent with the International Technology Roadmap for Semiconductors (ITRS, 2003), chip-to-substrate interconnects will need to have a pitch approximately equal to 40μm by the year 2012 and be able to accommodate the silicon and organic CTE mismatch without resorting to expensive reliability solutions. The demand for fine pitch chip-to-substrate interconnects combined with the CTE mismatch, creates significant demands for overall interconnect compliance as means to ensure reliability, through increasing fatigue life. Stress-engineered compliant off-chip interconnects are capable meeting future interconnect demands. Such interconnects are fabricated from stress-engineered metal thin-films using traditional IC fabrication methods and can be integrated with wafer level packing. A systematic design approach has been used to optimize interconnect geometry for use with estimated operational conditions. Finite Element Analysis (FEA) and Regression modeling have been used to create macro-models of interconnect behavior to assist in the optimization of the geometric design. Copper and Copper-Molybdenum are considered as interconnect material and the development intrinsic stress within copper is investigated via sputter deposition.
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Tooley, Wes W., Shirin Feghhi, Sangyoon J. Han, Junlan Wang, and Nathan J. Sniadecki. "Thermal Fracture of Oxidized Polydimethylsiloxane and its Implications in Soft Lithography." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64477.

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During the fabrication of nanopost arrays for measuring cellular forces, we have observed surface cracks in the negative molds used to replicate the arrays from a silicon master. These cracks become more numerous and severe with each replication such that repeated castings lead to arrays with missing or broken posts. This loss in pattern fidelity from the silicon master undermines the spatial resolution of the nanopost arrays in measuring cellular forces. We hypothesized that these cracks are formed because of a mismatch in the coefficient of thermal expansion (CTE) of PDMS and its oxidized surface layer. To study the fracture of PDMS due to thermal effects, we treated circular test samples of PDMS with oxidizing plasma and then heated them to cause surface cracks. These cracks were found to be more abundant at 180 °C than at lower temperatures. Finite element analysis of a bilayer material with a CTE mismatch was used to validate that thermal stresses are sufficient to overcome the fracture toughness of oxidized PDMS when heated to a curing temperature for PDMS. As a consequence, we have ascertained that elevated temperatures are a significant detriment to the reproducibility of nanoscale features in PDMS during replica molding.
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Zanardi, Heloisa, and Ricardo Afonso Angélico. "Study of the CTE mismatch effect in the fracture behaviour of composite materials using lattice models." In 25th International Congress of Mechanical Engineering. ABCM, 2019. http://dx.doi.org/10.26678/abcm.cobem2019.cob2019-2192.

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Reports on the topic "CTE mismatch"

1

Lanfranfo, Giobatta, and James Fast. Displacements and stress distribution in D0 Run IIb stave due to CTE mismatches. Office of Scientific and Technical Information (OSTI), July 2001. http://dx.doi.org/10.2172/15011729.

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2

Lanfranco, Giobatta, James Fast, and /Fermilab. Displacements and stress distribution in D0 Run IIb stave due to CTE mismatches. Office of Scientific and Technical Information (OSTI), July 2001. http://dx.doi.org/10.2172/15017254.

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You might also be interested in the extended bibliographies on the topic 'CTE mismatch' for particular source types:
Journal articles
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