2022 21st IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (iTherm)最新文献

{"title":"Novel Test Device for Non-destructive Experimental Characterization of Void Evolution in Microscale Solder Joints subjected to Thermal Aging","authors":"S. Prasad, Chetan Jois, G. Subbarayan","doi":"10.1109/iTherm54085.2022.9899684","DOIUrl":"https://doi.org/10.1109/iTherm54085.2022.9899684","url":null,"abstract":"There is a trend towards reduction in micro-bump size and pitch in 2.5D/3D packaging driven by increased bandwidth and power efficiency requirements. One of the reliability challenges that arises is the void evolution in the solder joint volume of the micro-bump accompanied by the growth of Cu-Sn IMCs in the Cu pillar after thermal aging for long periods of time. In this study, we describe a methodology to fabricate test devices with multiple sub-30 µm pitch Cu-Sn-Cu junctions, with the capability to observe the growth of voids in the micro-bumps in a non-destructive manner. Typically used material and void characterization methods for microbump interconnects are destructive, requiring cross-sectioning and polishing of the samples before observation of voids in solder joints. The cross-sectioning is cumbersome, results in loss of data, and once cross-sectioned, the samples cannot be used for further thermal aging. A non-destructive method of characterization assures continuity in the experiments during the void evolution.The fabricated test device consists of multiple sub-30 µm pitch Cu-Sn-Cu junctions that are directly observable under a Scanning Electron Microscope(SEM). This setup can be used to do experiments ex-situ (by periodically pausing experiments, to measure void growth under SEM) or in-situ (with measurements of void growth in real-time under SEM). The test devices can also be subjected to current via a 4-wire Kelvin sensing probe setup attached to 3-axis piezo stages with a resolution of 50 nm. Multiple devices with varying sizes of solder bumps are fabricated on a single die. The dies are aged in an environmental chamber at a temperature of 175 ◦C for hundreds of hours. They were periodically taken out of the environmental chamber and the void evolution in the solder joint on the devices measured under both optical microscopes and under an SEM. Finally, the effect of different bump sizes on the reliability of the solder joints is reported in this study.","PeriodicalId":351706,"journal":{"name":"2022 21st IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (iTherm)","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116397475","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":"Analysis of Jet and Cross Flow Interaction with Application in Hotspot Electronics Cooling","authors":"Christian Corvera, S. Mahjoob","doi":"10.1109/iTherm54085.2022.9899675","DOIUrl":"https://doi.org/10.1109/iTherm54085.2022.9899675","url":null,"abstract":"The increased processing power offered by many modern computers has come at the cost of increased heat generation, which must be dealt with using appropriately designed cooling mechanisms. While simple convection cooling systems can be adequate for some applications, certain configurations of electronics cause centralized \"hotspots\" of increased heat flux that must be treated with more focused cooling techniques. In this study, air impingement cooling applied at a heated surface with a hotspot is studied and the jet and cross flow interaction in the channel is analyzed. The effects of square, streamwise rectangular, and spanwise rectangular jet cross sections are investigated and discussed for the same impinging jet velocity and mass flow rate. Grid resolution study is conducted to ensure mesh independency of results. Also, code validation study is performed against experimental data in literature. The results indicate that the combination of jet impingement and cross flow cooling provide more efficient cooling at the target surface subject to the applied heat flux and hotspot. Furthermore, the results show that streamwise rectangular jets provide better cooling, especially in streamwise direction. The square geometry provides the most uniformly cooled area. The spanwise rectangular jets are less efficient compared to other studied jet geometries.","PeriodicalId":351706,"journal":{"name":"2022 21st IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (iTherm)","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125245303","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":"Design Optimization of an Aluminum-Pentane Grooved Heat Pipe Embedded in a Device Wall","authors":"S. Saygan, Emre Esen, Yigit Akkus","doi":"10.1109/iTherm54085.2022.9899606","DOIUrl":"https://doi.org/10.1109/iTherm54085.2022.9899606","url":null,"abstract":"Two-phase passive heat spreaders are widely utilized in component-level thermal management. Among them, grooved heat pipes play a vital role especially in the applications where the waste heat needs to be transferred to the heat sinks positioned far away from the heat sources such as the thermal management of satellites. Capillary pumping scales with the extent of the variation of the edge angle, which is the angle of the three-phase contact line with the groove wall. Consequently, the contact angle of the working fluid with the heat pipe material determines the overall performance of the heat pipe. In this work, we first measure the contact angle of n-pentane on Al6063-T6 substrates with varying surface roughness values, which are all relevant to engineering applications as well as common surface finishes of various machining processes. Selection of the working fluid and container material is made based on the reported compatibility of the solid-fluid couple as well as the non-toxicity of the fluid. After the measurement of the contact angles, a recently developed heat pipe performance evaluation software Heat-Pipe Analysis Toolbox (H-PAT) is utilized to generate the performance curves corresponding to different groove geometries. Investigated groove geometries are selected based on the criteria of lightness, machin-ability, and mechanical strength. Finally, optimum geometries are determined for the application of interest.","PeriodicalId":351706,"journal":{"name":"2022 21st IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (iTherm)","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123774260","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":"Vapor-Chamber Performance Evaluation: The Challenge of Impartial Cross-Platform Comparison","authors":"G. Damoulakis, M. J. Gukeh, C. Megaridis","doi":"10.1109/iTherm54085.2022.9899605","DOIUrl":"https://doi.org/10.1109/iTherm54085.2022.9899605","url":null,"abstract":"The worldwide power electronics market is expected to expand at an annual growth rate of 4.7% from USD 35.1 billion in 2020 to USD 44.2 billion by 2025 [1]. This rise is fueled by the use of renewable energy sources throughout the world, and the increasing utilization of power electronics in the production of electric vehicles. The expanding implementation of power electronics in consumer products is another key driver of the market's growth. The most significant impediment in the electronic systems is their thermal management. Two-phase cooling is currently the standard thermal-management solution in all its forms, including heat pipes, vapor chambers, thermosyphons, and so on. But comparing the performance of different systems poses many challenges, thus making decision making difficult in the absence of complete information for each device.In this study, a list of ten critical elements or parameters required to unambiguously characterize the design and performance of a promising two-phase heat-transfer system for future deployment and development, namely the vapor chamber, is presented. This \"Decalogue\" is inspired by three main factors. First, the rising demand for better and more effective vapor chamber assemblies, which has prompted both industry and academia to invest substantially in related R&D. Second, this investment has resulted in a plethora of new systems (i.e. [2] –[6] etc.) where each design has been accompanied with insufficient description, making it difficult, if not impossible, to perform detailed comparisons across different designs/approaches. Third, the need to develop a common set of standards for describing such systems so that similar designs/philosophies may be compared successfully by researchers and developers seeking to duplicate results and improve on previous performance, especially in commercialized systems.We seek to gather all criteria needed to characterize each vapor chamber system, while exhibiting all benefits and limitations of its design, and illustrating what type of technical application the design may be helpful for, using a simple tabular method. The suggested approach might serve as a reference point or a standard way of accurately representing this type of heat transfer component. This description should benefit researchers in the area by clearly stating what the actual measurements/attributes of each system are, while also emphasizing the relevance/importance of each design by simply comparing it to others. The ten (deca) points presented here merely illustrate the most essential aspects of the design and performance of any vapor chamber.","PeriodicalId":351706,"journal":{"name":"2022 21st IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (iTherm)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124084220","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":"Richard Chu ITherm Award","authors":"","doi":"10.1109/itherm54085.2022.9899602","DOIUrl":"https://doi.org/10.1109/itherm54085.2022.9899602","url":null,"abstract":"","PeriodicalId":351706,"journal":{"name":"2022 21st IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (iTherm)","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128975914","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":"Compact Thermal Modelling of Magnetic Components via Real Coded Genetic Algorithm","authors":"Anshuman Dey, N. Shafiei, Rahul Khandekhar, W. Eberle, Ri Li","doi":"10.1109/iTherm54085.2022.9899579","DOIUrl":"https://doi.org/10.1109/iTherm54085.2022.9899579","url":null,"abstract":"The trend of increasing power densities in modern day power electronic systems is pushing components to their thermal limits, warranting the need for accurate thermal modelling. Unlike the thermal modelling approach for semiconductor devices, thermal modelling of magnetic components has not been standardised. Due to this lack of standardisation in the academic community, most magnetic component thermal models have not been evaluated for Boundary Condition Independence (BCI) and hence cannot be classified as compact thermal models (CTMs). In this paper we develop a CTM of an inductor using real coded genetic algorithm (GA) based on the DELPHI approach. First, a Detailed Thermal Model (DTM) of the inductor under DC excitation is developed and validated using experimental test results. Following which resistance network values were deduced from the DTM results for varied boundary conditions via optimisation by the real coded GA. A fully connected resistance network was observed to be the best representation of the inductor DTM. The resulting CTM is able to predict junction (winding) temperature within 5 % of the DTM results for a varied set of boundary conditions. The inductor CTM developed is a low computational cost alternative to the DTM and can be used in system level simulations to evaluate thermal performance for varied applications.","PeriodicalId":351706,"journal":{"name":"2022 21st IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (iTherm)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130372214","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":"iTherm 2022 Cover Page","authors":"","doi":"10.1109/itherm54085.2022.9899651","DOIUrl":"https://doi.org/10.1109/itherm54085.2022.9899651","url":null,"abstract":"","PeriodicalId":351706,"journal":{"name":"2022 21st IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (iTherm)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132709780","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":"Remaining Useful Life Estimation using a combined Physics of Failure and Deep Learning-based approach on SAC305 Solder PCBs subjected to Thermo-Mechanical Vibration Loads","authors":"P. Lall, Tony Thomas, J. Suhling, K. Blecker","doi":"10.1109/iTherm54085.2022.9899547","DOIUrl":"https://doi.org/10.1109/iTherm54085.2022.9899547","url":null,"abstract":"This paper focuses on the real-time remaining useful life (RUL) estimation of SAC305, SAC105 and SnPb solder alloy PCBs subjected to combined temperature and vibration loads. The RUL estimation of the packages on the PCB were carried out using a combined physics of failure and deep learning approaches for different operating conditions. The test boards used in this study are of same configuration for all the three solder materials and it consists of a multilayer FR4 configuration with JEDEC standard dimensions. The failure predictions and feature vector identifications are carried out using the strain gauge signals attached at the back of the PCB. The strain signals are analyzed both in the time and frequency domain to identify the different feature vectors that can predict failure of the packages as the number of drop increases. Principal component analysis is used as the pattern recognition and data reduction technique for the time and frequency domain data of the strain signals. Frequency components including and excluding the natural frequency of the test boards were used to identify the different patterns of before and after failure strain signals. The remaining useful life estimations are very useful in improving the efficiency and proactively helps to schedule maintenance effectively. The use of deep learning helps to models complex systems with multiple parameters involving nonlinear behaviors. In this paper the feature vectors identified from different operating conditions are modelled using a combined physics of failure and deep learning-based approach to estimate the remaining useful life of the packages. The changes in the material characteristics of the solders with different operating conditions are also modelled to the Long Short-term Memory (LSTM) deep learning model with the feature vectors to predict the failure of the packages. A regression model to predict the failure is also modelled to predict the failure based on the loading and material characteristics of the solders. LSTM models for each solder materials for multiple use-cases are modeled, and combined models involving different acceleration levels are also modeled.","PeriodicalId":351706,"journal":{"name":"2022 21st IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (iTherm)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124327739","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":"Copper Trace Failures in Ball Grid Array (BGA) Packages under Sequential Harmonic Vibration and Temperature Cycling","authors":"A. Deshpande, Idowu Olatunji, Manuel Bascolo, A. Dasgupta, U. Becker, Jokai Gabor","doi":"10.1109/iTherm54085.2022.9899525","DOIUrl":"https://doi.org/10.1109/iTherm54085.2022.9899525","url":null,"abstract":"Solder interconnects in ball grid array (BGA) packages can present substantial fatigue degradation risk under combinations of mechanical (vibration) and thermo-mechanical cyclic loading. Durability tests to investigate such risks typically use either sequential or simultaneous combinations of vibration loading and temperature cycling. The interconnect system consists of not just the solder joint itself but also the associated features, such as the interfacial IMC layer, the copper pads on the substrates and the copper traces and vias connected to the copper pads. The copper traces are known to be particularly vulnerable to mechanical flexural loads, such as those experienced due to vibration loading. Recent studies have shown a combined failure mode consisting of cracks in both the solder and copper pad. However, there is limited information in the literature on the vulnerability of copper traces under sequential vibration and temperature cycling loads. Therefore, this work examines the influence of loading sequence (harmonic vibration followed by temperature cycling and vice versa) on copper trace cracks in a Printed Wiring Assemble (PWA) that consists of a centrally located BGA component on a multilayered organic printed wiring board (PWB). In addition, the width of Copper traces connected to the copper pad was varied (45µm, 100µm and 200µm) to determine how the fatigue degradation risks scale with trace width.In order to understand the loading conditions that lead to copper trace cracks, the test matrix consists of (i) room-temperature harmonic vibration tests close to the fundamental mode of the PWA at 150g’s and 175g’s; (ii) temperature cycling (TC) tests (-40°C to 125°C) and (iii) sequential application of items (i) and (ii). Failure analysis conducted on the tested specimens revealed that copper trace cracks were highly likely to occur during the harmonic vibration segment of individual and sequential tests. In contrast, temperature cycling loads did not lead to copper trace failures, although it did show evidence of accelerating the propagation and growth of cracks that had already initiated during any prior vibration exposure.","PeriodicalId":351706,"journal":{"name":"2022 21st IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (iTherm)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129220354","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 Effect of Bismuth Content on Mechanical Property Evolution of SAC+Bi Lead Free Solders Subjected to Long Term Thermal Exposures","authors":"Mohammad Al Ahsan, S. Hasan, J. Suhling, P. Lall","doi":"10.1109/iTherm54085.2022.9899562","DOIUrl":"https://doi.org/10.1109/iTherm54085.2022.9899562","url":null,"abstract":"Solder joints in electronic assemblies are frequently exposed to thermal cycling environments in their service life or during accelerated life testing where temperature variations occur from very low to high temperature. In our recent papers, the mechanical behavior evolutions occurring in SAC305 and SAC+3%Bi (SAC_Q) lead free solders have been characterized for up to 20 days of exposure to four different thermal profiles including isothermal aging, slow thermal cycling, thermal shock, and thermal ramping. In the current investigation, we have extended our prior study to examine several different SAC+Bi solder alloys with various bismuth contents. In particular, a family of SAC+Bi alloys with 1%, 2%, and 3% Bi were studied with four different thermal exposure profiles (isothermal aging, slow thermal cycling, thermal shock, and thermal ramping). The primary objective of this study was to determine how much bismuth is needed in the lead-free alloy to mitigate microstructure and material property evolutions during thermal exposuresUniaxial miniature bulk specimens were prepared for the three SAC+Bi alloys using a controlled reflow profile. After fabrication, the samples were then preconditioned by thermal exposure under stress-free conditions for various durations up to 100 days. After preconditioning via thermal exposures, the samples were subjected to stress-strain testing to measure their mechanical properties including effective elastic modulus, and Ultimate Tensile Strength (UTS).For the miniature bulk solder samples of each SAC+Bi alloy, the evolutions of the mechanical properties for each thermal exposure profile were characterized as a function of the duration of thermal exposure. For all of the alloys, the degradations for the slow thermal cycling exposure were the largest, while those for isothermal aging were surprisingly the smallest. Increasing the Bi content of the SAC+Bi alloy led to increased mitigation of thermal degradation effects for all of the exposure profiles. Reduced microstructural evolution in the SAC+Bi alloy samples was found to be the major reason for the improved resistance to mechanical behavior changes. The tensile strength results for samples with 2% Bi and 3% were nearly the same, suggesting that lower bismuth content could be sufficient for many applications.","PeriodicalId":351706,"journal":{"name":"2022 21st IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (iTherm)","volume":"100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114405311","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}