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

{"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":"Air-water hybrid cooling for computer servers: A case study for optimum cooling energy allocation","authors":"Xiaojin Wei, G. Goth, P. Kelly, R. Zoodsma, A. VanDeventer","doi":"10.1109/ITHERM.2014.6892331","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892331","url":null,"abstract":"Air-water hybrid cooling offers flexible design choices for computer systems with components of different thermal management needs. On one hand, water cooling enables the continuous growth of CPU performance and increasing packaging density. High performance cold plates such as microchannels have been successfully implemented for water cooling in previous high-end systems. When coupled with an air-water heat exchanger or radiator, the water loop becomes a closed one with no need for facility chilled water. This significantly reduces the complexity to deploy the server in the data center. On the other hand, for components with less thermal demand, traditional air-cooling technology is adequate with low cost, high availability and better serviceability. For the computer system as a whole, an air-water hybrid cooling system may be optimized. Such a hybrid system typically requires pumps to drive the water loops, air-movers to drive air through the radiator and blowers or fans to drive the air flow for component cooling. It is the focus of this paper to study the optimum allocation of energy between the pumps and air-movers for a given total cooling energy budget and overall load. The goals are to achieve better overall thermal performance and to reduce the cooling energy consumption. To this end models for each cooling block are established based on test data. These include the air-water heat exchanger, pumps, blowers, and cold plates. These models are linked together to predict the overall thermal system operating points for different application scenarios. A parametric study is then conducted to define the near optimum allocation of cooling energy for these scenarios that meets the thermal design objectives. Additionally, sub-threshold leakage for the CPU is taken into account to enhance the model since temperature provides positive feedback. It is shown through modeling that additional performance enhancement is possible with judicious allocation of cooling energy for a given overall energy budget. It is argued in this paper that overall energy efficiency can be improved significantly through intelligent data driven energy allocation.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"33 1","pages":"568-573"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81533493","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":"Improving cooling efficiency of servers by replacing smaller chassis enclosed fans with larger rack-mount fans","authors":"Bharath Nagendran, S. Nagaraj, J. Fernandes, R. Eiland, D. Agonafer, V. Mulay","doi":"10.1109/ITHERM.2014.6892332","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892332","url":null,"abstract":"As a common practice in the data center industry, chassis fans are used to direct air flow independent from neighboring servers. In general, smaller fans are less efficient compared to geometrically similar larger fans. In this study, a novel approach is proposed whereby chassis enclosed fans are replaced with a smaller number of larger fans installed behind a stacked array of servers which share airflow. As a baseline study, a CPU dominated 1.5U Open Compute server with four 60mm fans installed within its chassis is characterized experimentally for its flow impedance, fan speed dependent flow rate, effect on die temperature and power consumption at various compute utilization levels. Larger fans with a square frame size of 80mm and 120mm are selected and individually characterized for their air moving capacity and power consumption. Primary emphasis is placed on the 80mm fan case, with discussion of the 120mm fans included. CFD is used to simulate a system of stacked servers serviced by larger fans to obtain its flow characteristics and operating points. The fan power consumption of the larger fans is determined experimentally at these operating points replicated in an air flow bench. Comparing with the base line experiments, replacing smaller fans with larger units results in a significant decrease in fan power consumption without conceding flow rate and static pressure requirements.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"21 1","pages":"574-582"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82868650","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":"Assessing solder interconnect reliability of control boards in power electronic systems using Physics-of-Failure models","authors":"D. Squiller, E. Mengotti, P. McCluskey","doi":"10.1109/ITHERM.2014.6892410","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892410","url":null,"abstract":"The demand for power electronic systems to operate in harsh environmental conditions has increased over the past 20 years. These environments include those relating to deep oil-well drilling, automotive and aerospace applications. The miniaturization of the power module along with higher power densities have created elevated stress levels on ancillary subsystems, specifically the control circuitry. This study develops first-order methods and models to assess the solder interconnect reliability of critical components on the control circuitry in power electronic systems. Thermal and reliability simulations based upon Physics-of-Failure modeling techniques were conducted on a 2.2 kW variable-frequency drive to evaluate the susceptibility of component level failure mechanisms. CalcePWA, an interconnect reliability modeling software tool, was used as the primary vehicle to conduct these simulation models. A power cycling apparatus was constructed in order to calibrate the reliability models through accelerated testing of the drive.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"35 1","pages":"1154-1163"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75418126","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 ASHRAE environmental classes on data centers","authors":"M. David, R. Schmidt","doi":"10.1109/ITHERM.2014.6892403","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892403","url":null,"abstract":"Data centers consume a significant amount of energy in the US and worldwide, much of which is consumed by the cooling infrastructure, particularly the chiller plant and computer room air conditioners and air handlers. To enable energy efficient data center designs, ASHRAE added two new IT environmental classes, A3 and A4, with associated allowable inlet air temperatures of 40C and 45C respectively. IT equipment that meet these new allowable environmental envelopes can operate in data centers with minimal refrigeration cooling and instead rely on ambient free cooling. In this paper we investigate the impact of allowing a data center to operate up to the A3 limit of 40C on total data center energy use for 3 different types of servers in a chiller-less data center located in a variety of locations. The study finds that though facility power reduces as the demand for cold air reduces, the increase in IT power consumption, due to fan speed-up, can offset these savings and in some cases result in an overall increase in data center power. Thus the most energy efficient operating point is dependant on the specific energy use profiles of the infrastructure and the IT equipment. The higher allowable temperature can also result in higher failure rates and an increased risk of equipment or service loss due to data center cooling failures. This paper also presents a study on the potential for chiller elimination and chiller use reduction across the US, Europe and in India by operating in the various ASHRAE envelopes. For wet, water side economized data centers, A2 and A3 equipment is sufficient to almost completely remove the need for chillers in many geographic locations.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"11 1","pages":"1092-1099"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75313844","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":"Modal control of unstable boiling states in three-dimensional nonlinear pool-boiling","authors":"Van Gils, M. Speetjens, H. Zwart, H. Nijmeijer","doi":"10.1109/ITHERM.2014.6892367","DOIUrl":"https://doi.org/10.1109/ITHERM.2014.6892367","url":null,"abstract":"Topic is feedback stabilisation of a nonlinear pool-boiling system in three spatial dimensions (3D). Regulation of its unstable (non-uniform) equilibria has great potential for application in micro-electronics cooling and thermal-management systems. Here, as a first step, stabilisation of such 3D equilibria is considered. A control law is designed that regulates the heat supply to the heater as a function of the Fourier-Chebyshev modes of its internal temperature distribution. This admits a controller that is tailored to the system dynamics, as these modes intimately relate to the physical eigenmodes. The internal temperature distribution is, similar to practical situations, estimated from a finite number of measurement positions on the heater surface by an observer. Performance of this output-based modal controller is demonstrated and analysed by simulations of the nonlinear closed-loop system. This provides first proof of principle of the proposed control strategy for the regulation of 3D boiling states.","PeriodicalId":12453,"journal":{"name":"Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"255 1","pages":"833-839"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78986159","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}