Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)最新文献

{"title":"CHF enhancement of Al2O3, TiO2 and Ag nanofluids and effect of nucleate pool boiling time","authors":"M. S. Ulcay","doi":"10.1109/ITHERM.2014.6892357","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892357","url":null,"abstract":"Nanofluids are nanometer sized suspended particles in water or other base fluids. They are used for their increased nucleate boiling critical heat flux (CHF) values far beyond compared to pure water or base fluid. Therefore pool boiling heat transfer tests are performed to understand increase in CHF. The pool boiling characteristics and critical heat flux enhancement using nanofluids of dilute dispersions of alumina, titania and silver are studied. High heat transfer rates with high critical heat flux achieved with modest nanoparticle concentrations (<;0.1% by volume). Heater wire used in CHF tests were only on 50μm in diameter. Change in surface structure of heater wire causes increase in CHF. Surface of the heater is covered with porous layer of nanoparticles during nucleate boiling. It is determined to investigate the effects of nucleate boiling time (coating time) during which the heater wire is exposed to deposition of nanoparticles. Results of this study presented that there is a non-linear relationship between the coating time and CHF for short periods of coating times, up to 30 seconds; however this effect loses its impact if the coating duration is elongated. It was also showed that longer periods of coating time increased the CHF but not drastically and the relationship between coating time and CHF is no longer non-linear and can be approximated by a linear line. This study represents an important step in understanding the relationship between CHF and the optimum amount of nanoparticle deposition or amount of porous layer of nanoparticles formed on heater surface with respect to nucleate boiling (coating)/time dependency.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"35 1 1","pages":"756-764"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88072659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Novel power electronics three-dimensional heat exchanger","authors":"K. Bennion, J. Cousineau, J. Lustbader, S. Narumanchi","doi":"10.1109/ITHERM.2014.6892398","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892398","url":null,"abstract":"Electric-drive systems, which include electric machines and power electronics, are a key enabling technology to meet increasing automotive fuel economy standards, improve energy security, address environmental concerns, and support economic development. Enabling cost-effective electric-drive systems requires reductions in inverter power semiconductor area, which increases challenges associated with heat removal. In this paper, we demonstrate an integrated approach to the design of thermal management systems for power semiconductors that matches the passive thermal resistance of the packaging with the active convective cooling performance of the heat exchanger. The heat exchanger concept builds on existing semiconductor thermal management improvements described in literature and patents, which include improved bonded interface materials, direct cooling of the semiconductor packages, and double-sided cooling. The key difference in the described concept is the achievement of high heat transfer performance with less aggressive cooling techniques by optimizing the passive and active heat transfer paths. An extruded aluminum design was selected because of its lower tooling cost, higher performance, and scalability in comparison to cast aluminum. Results demonstrated a 102% heat flux improvement and a package heat density improvement over 30%, which achieved the thermal performance targets.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"99 1","pages":"1055-1063"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85815950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benefits of properly sealing a cold aisle containment system","authors":"Yasin U. Makwana, Andrew R. Calder, S. Shrivastava","doi":"10.1109/ITHERM.2014.6892362","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892362","url":null,"abstract":"Data centers are mission-critical facilities and the nerve center of successful business operations. Surging demand for processing power, work load virtualization and consolidation is increasing data center heat loads, making the thermal management of data centers challenging. Containing the air in a data center is an important energy savings strategy towards data center optimization. Most of the modern, energy efficient, data centers deploy some kind of containment system. This paper discusses test data for a Cold Aisle Containment (CAC) system and compares it with a standard Hot Aisle/Cold Aisle (HA/CA) configuration. The HA/CA configuration is shown to support a heat load of 14.6kW/cabinet while the CAC system was tested up to 25.2 kW/cabinet. In addition, the test data demonstrated the cooling energy savings with the CAC system. Furthermore, we quantified the importance and effectiveness of sealing accessories (i.e. grommets for cable openings and blanking panels) when deployed in a CAC environment.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"76 1","pages":"793-797"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82356560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal characterization of nanostructured superlattices of TiN/TaN: Applications as electrodes in Phase Change Memory","authors":"A. Sood, S. Eryilmaz, R. Jeyasingh, Jungwan Cho, M. Asheghi, H. Wong, K. Goodson","doi":"10.1109/ITHERM.2014.6892358","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892358","url":null,"abstract":"Phase Change Memory (PCM) technology relies on the contrast in electrical resistance between the amorphous and crystalline states of a chalcogenide active material. Electrical PCM devices use Joule heating by short pulses of current to induce phase change, such that the amount of heat injected into the active material and the rate of cooling determine the final state of material formed. In this paper, we explore the possibility of replacing commonly used TiN electrodes by nanostructured superlattices of TiN/TaN that have lower through-plane thermal conductivity, in order to improve the confinement of heat within the phase change material and achieve a reduction in the device programming current. TiN(m)/TaN(n) superlattices were grown on Si substrates using physical vapor deposition, m and n representing the intra-period thicknesses of TiN and TaN layers respectively (m, n: 5 - 25 nm). The through-plane thermal conductivity of these superlattices was measured using time-domain thermoreflectance (TDTR), and was found to be in the range 1.5 - 2 W/m-K, a reduction from the bulk conductivity of TiN (~ 19 W/m-K) by up to a factor of 10. Transmission Electron Microscopy (TEM) was used to characterize film morphology, pointing to additional sources of carrier scattering that might lead to this reduction in conductivity, and suggesting avenues for optimization of growth parameters. The low thermal conductivity of the superlattice films opens up the possibility of using them as bottom electrodes in PCM, towards the goal of reducing power consumption and improving device packing density. A simplified 1D thermal model predicts that reductions in programming current b y ~75% are possible.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"7 1","pages":"765-770"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84253680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Graphene-enhanced phase change materials for thermal management of battery packs","authors":"P. Goli, A. Balandin","doi":"10.1109/ITHERM.2014.6892442","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892442","url":null,"abstract":"Graphene and few-layer graphene reveal exceptionally high thermal conduction properties, which can be used for thermal management. Here we show that incorporation of graphene and few-layer graphene to the hydrocarbon-based phase change material allows one to increase its thermal conductivity by more than two orders of magnitude while preserving its latent heat storage ability. A combination of the sensible and latent heat storage together with the improved heat conduction results in a composite material with the exceptional thermal management capabilities. We show that the graphene-enhanced phase change material can substantially improve the thermal management of Li-ion and other advanced types o f batteries.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"21 1","pages":"1390-1393"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87544180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of moisture exposure on the mechanical behavior of flip chip underfills in microelectronic packaging","authors":"N. Chhanda, J. Suhling, P. Lall","doi":"10.1109/ITHERM.2014.6892300","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892300","url":null,"abstract":"Reliable, consistent, and comprehensive material property data are needed for microelectronics encapsulants for the purpose of mechanical design, reliability assessment, and process optimization of electronic packages. Since the vast majority of contemporary underfills are epoxy based, they have the propensity to absorb moisture, which can lead to undesirable changes in their mechanical and adhesion behaviors. In this study, the effects of moisture adsorption on the stress-strain behavior of an underfill encapsulant were evaluated experimentally and theoretically. A novel specimen preparation procedure has been used to manufacture 60 × 3 mm uniaxial tension test samples, with a specified thickness of 0.5 mm. The test specimens were dispensed and cured with production equipment using the same conditions as those used in actual flip chip assembly, and no release agent was required to extract them from the mold. The fabricated uniaxial test specimens were then exposed in an adjustable thermal and humidity chamber to combined hygrothermal exposures at 85 C and 85% RH for various durations. After moisture preconditioning, a microscale tension-torsion testing machine was used to evaluate the complete stress-strain behavior of the material at several temperatures (T = 25, 50, 75, 100 and 125 C). The viscoelastic mechanical response of the underfill encapsulant has also been characterized via creep testing for a large range of applied stress levels and temperatures before moisture exposure. From the recorded results, it was found that the moisture exposures strongly affected the mechanical properties of the tested underfill including the initial elastic modulus and ultimate tensile stress. With the obtained mechanical property data, a three-dimensional linear viscoelastic model based on Prony series response functions has been applied to fit the stress-strain and creep data, and excellent correlation had been obtained for samples with and without moisture exposure. The effects of moisture were built into the model using the observed changes in the glass transition temperature within the WLF Shift Function.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"6 1","pages":"333-345"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85478356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The study of vibrational performance on different doped low creep lead free solder paste and solder ball grid array packages","authors":"S. Thirugnanasambandam, T. Sanders, A. Raj, D. Stone, John L. Evans, G. Flowers, J. Suhling","doi":"10.1109/ITHERM.2014.6892379","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892379","url":null,"abstract":"Relatively little is known about the performance of the doped Ball Grid Array (BGA) packages used in semiconductor industries, even though newer products are widely being introduced to the market. This work experimentally investigates the doping effects of the BGA packages with SAC 305 alloys, caused by the vibration loading. This experiment focuses on the vibration fatigue life of 15 mm CABGA packages with 208 perimeter solder balls on a 0.8 mm pitch. The test boards were built to withstand JEDEC JESD22-B103B standards of high stress test in vibrational shaker table to assess the solder joint performance. The test boards are built with three different reflow profiles and two different stencil thicknesses 8 mil (6 mil with overprint) and 4 mil to study the differences in doping effect of the new doped alloys. The WLCSP assembly was subjected to accelerated life test of severe random vibration per board. The reliability of the component is determined by the ability of the components to withstand vibration as a result of motion produced by field operations. The deleterious effect of the mechanical loading of BGA's on the characteristic fatigue lifetime is reported. The results show that the material characteristics has a direct impact on the total time to failure. The results show that the Time-To-Failure (TTF) of the solder joint decreases with doping. The effectiveness of this characteristics was demonstrated with promising results through vibration testing of different lead free low creep alloys. This paper concludes with discussion of the deterioration intensity aging has on SAC alloys and the change in reliability due to doping.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"19 1","pages":"920-923"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82164740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of surface enhancements upon boiling heat transfer in a liquid immersion cooled high performance small form factor server model","authors":"J. Gess, S. Bhavnani, Bharath Ramakrishnan, R. Johnson, D. Harris, R. Knight, M. Hamilton, C. Ellis, J. Gess","doi":"10.1109/ITHERM.2014.6892314","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892314","url":null,"abstract":"The impact of increasing power consumption trends on a global economy with limited resources to sustain them cannot be understated. As worldwide communication requirements expand, data centers will need to be designed more efficiently to not only keep operation costs down for a business' bottom line, but also to be mindful of the world's power availability and resource supply. Therefore, the importance of designing data centers efficiently, but also compactly grows in step with society's power demands. To integrate into this new smarter data center, work has been completed on a small form factor, modular, high performance liquid immersion cooled server model with heat dissipations of over 700 Watts. These high power dissipations were achieved by the integration of enhanced surfaces affixed to the bare silicon die to promote increased boiling performance. The two surfaces tested were a sintered copper microporous heat sink and one that contained a dense array of microscale fins.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"65 6 1","pages":"435-443"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87533758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Double-sided cooling and transient thermo-electrical management of Silicon on DCB assemblies for power converter modules: Design, technology and test","authors":"B. Wunderle, M. Springborn, D. May, C. Manier, M. Abo Ras, R. Mrossko, H. Oppermann, T. Xhonneux, T. Caroff, W. Maurer, R. Mitova","doi":"10.1109/ITHERM.2014.6892370","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892370","url":null,"abstract":"This paper deals with the system design, technology and test of a novel concept of integrating Silicon power dies along with thermo-electric coolers and a phase change heat buffer in order to thermally manage transients occurring during operation. The concept features double-sided cooling as well as new materials and joining technologies to integrate the dies such as transient liquid phase bonding/soldering and sintering. Coupled-field simulations are used to predict thermal performance and are verified by especially designed test stands to very good agreement.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"8 1","pages":"851-861"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84701309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of underfill design parameters on die cracking in flip chip on flexible substrates","authors":"M. Sabale, Kiran Vinerkar, S. Thakur, S. Tonapi","doi":"10.1109/ITHERM.2014.6892336","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892336","url":null,"abstract":"The trends towards miniaturization in the electronics industry coupled with advances in flip chip technology have increased the use of flip chip on board or direct chip attach technology in many products. This is especially true for products where re-work is not an option. Reliability issues were overcome by the use of underfill to couple the chip to the substrate and subsequently significant advances were made in underfill technology to give options like traditional capillary flow underfills to no-flow and wafer level underfill materials and processes. While significant research has been conducted and published in the area of flip chip on organic substrates as well as on underfill technology, there is still a lot that needs to be done in the area of flip chip on flexible substrates. There is significant potential for flip chip on flexible substrates as it is demonstrated in many applications like implantable medical devices, hard disk drives etc. As we move from rigid to flexible substrates the thickness reduces from the standard 62 mil - 31 mil range to 10 mil - 4 mil range. The change in thickness also changes the reliability issues and failure modes as compared to flip chip on rigid organic substrates. In this paper, we have investigated the effect of underfill geometry (height and width of fillet) on die cracking during thermal cycling. Package is subjected to the -55°C to 125°C accelerated thermal cycling. A 3 Dimensional Finite Element Analysis model is created and used to computationally evaluate the effect of various parameters and draw inferences on die cracking in flip chip on flexible substrates.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"17 1","pages":"605-608"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84984156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}