Pub Date : 2016-05-01DOI: 10.1109/ITHERM.2016.7517714
Fanghao Yang, M. Schultz, P. Parida, E. Colgan, B. Dang, Gerard McVicker, T. Chainer
Thermal challenges in 3D ICs have driven the need for embedded chip cooling. In this paper, we measured the thermal performance of a two-phase system employing flow boiling in chip-embedded micro-channels utilizing the latent heat of vaporization of dielectric refrigerants (such as R-1234ze) In the present study, an investigation was performed on a 20 mm × 20 mm thermal test vehicle having a heater layer to simulate the heat generation from a state-of-the-art 8-core microprocessor chip and a sensor layer to measure temperature at key locations within the test vehicle. Fluidic channels in the form of radial expanding micro-scale cavities with micro-pin fields were etched into the test vehicle. The micro-pin fields represent the through-silicon-via (TSV) interconnects present in multi-die stacks. The heaters are used to simulate a background heat flux of 20 W/cm2 and individual core heat fluxes of up to 210 W/cm2. This heat generation capability corresponds anywhere from a processor low-power idle mode to a high-power super-turbo mode and beyond. Since the flow resistance in a microchannel for two-phase cooling depends on in-situ heat generation, asymmetric power dissipation due to different power levels in various cores and non-core areas may unbalance the overall flow distribution. Furthermore, it may reduce the local heat transfer rate and even lead to premature failure of working cores. This study aims at understanding the effects of asymmetric heat flux profiles on flow resistance and boiling heat transfer.
{"title":"Boiling sensitivity analysis of asymmetrically heated micro-scale devices","authors":"Fanghao Yang, M. Schultz, P. Parida, E. Colgan, B. Dang, Gerard McVicker, T. Chainer","doi":"10.1109/ITHERM.2016.7517714","DOIUrl":"https://doi.org/10.1109/ITHERM.2016.7517714","url":null,"abstract":"Thermal challenges in 3D ICs have driven the need for embedded chip cooling. In this paper, we measured the thermal performance of a two-phase system employing flow boiling in chip-embedded micro-channels utilizing the latent heat of vaporization of dielectric refrigerants (such as R-1234ze) In the present study, an investigation was performed on a 20 mm × 20 mm thermal test vehicle having a heater layer to simulate the heat generation from a state-of-the-art 8-core microprocessor chip and a sensor layer to measure temperature at key locations within the test vehicle. Fluidic channels in the form of radial expanding micro-scale cavities with micro-pin fields were etched into the test vehicle. The micro-pin fields represent the through-silicon-via (TSV) interconnects present in multi-die stacks. The heaters are used to simulate a background heat flux of 20 W/cm2 and individual core heat fluxes of up to 210 W/cm2. This heat generation capability corresponds anywhere from a processor low-power idle mode to a high-power super-turbo mode and beyond. Since the flow resistance in a microchannel for two-phase cooling depends on in-situ heat generation, asymmetric power dissipation due to different power levels in various cores and non-core areas may unbalance the overall flow distribution. Furthermore, it may reduce the local heat transfer rate and even lead to premature failure of working cores. This study aims at understanding the effects of asymmetric heat flux profiles on flow resistance and boiling heat transfer.","PeriodicalId":426908,"journal":{"name":"2016 15th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128655785","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}
Pub Date : 2016-05-01DOI: 10.1109/ITHERM.2016.7517534
Hongqing Zhang, C. Reynolds, Tuhin Sinha, J. Zitz, F. Pompeo
In this paper, we discuss the design of a four (4) chip Multi Component Carrier (MCC) package and feasibility for use in high-end server/mainframe applications. A new class of organic, Chip Scale Package (CSP) and associated design ground rules were created based on a low, coefficient of thermal expansion (CTE) organic material, in addition to the CSP form factor. Micro Ball Grid Array (BGA) is used to connect the CSP to a daughter card assembly to form the MCC package structure. The low CTE organic substrate significantly reduces the internal stress that arises from the chip to substrate bond and assembly process, which enhances the yield and reliability of the CSP and the entire MCC structure. Numerical simulation using the finite element method (FEM) has been conducted to evaluate and optimize the lid design of the MCC package in order to ensure reliable lid to package operation during assembly and field thermal excursions. Thermal and mechanical solutions with various combinations of geometric design are discussed.
{"title":"A high performance Multi Component Carrier with Chip Scale Package","authors":"Hongqing Zhang, C. Reynolds, Tuhin Sinha, J. Zitz, F. Pompeo","doi":"10.1109/ITHERM.2016.7517534","DOIUrl":"https://doi.org/10.1109/ITHERM.2016.7517534","url":null,"abstract":"In this paper, we discuss the design of a four (4) chip Multi Component Carrier (MCC) package and feasibility for use in high-end server/mainframe applications. A new class of organic, Chip Scale Package (CSP) and associated design ground rules were created based on a low, coefficient of thermal expansion (CTE) organic material, in addition to the CSP form factor. Micro Ball Grid Array (BGA) is used to connect the CSP to a daughter card assembly to form the MCC package structure. The low CTE organic substrate significantly reduces the internal stress that arises from the chip to substrate bond and assembly process, which enhances the yield and reliability of the CSP and the entire MCC structure. Numerical simulation using the finite element method (FEM) has been conducted to evaluate and optimize the lid design of the MCC package in order to ensure reliable lid to package operation during assembly and field thermal excursions. Thermal and mechanical solutions with various combinations of geometric design are discussed.","PeriodicalId":426908,"journal":{"name":"2016 15th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"152 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133991356","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}
Pub Date : 2016-05-01DOI: 10.1109/ITHERM.2016.7517606
Kent Loong Khoo, Chuan Sun, Nuttawut Lewpiriyawong, P. Lee, S. Chou
Plate fin and tube heat exchangers (FTHX) are widely used in HVAC applications due to the high effectiveness to cost ratio for heat transfer between two fluids. For air-cooled residential air conditioning unit applications, the overall efficiency of the unit is limited by the air-side heat transfer coefficient, which is much lower than that of the refrigerant-side. In this paper, oblique-shaped tube with the same tube area is introduced to replace the circular tube in FTHX to enhance the overall thermal-hydraulic performance of the air-side heat transfer. Numerical investigations of plain FTHX with circular tube, elliptic tube and oblique-shaped tube are conducted to analyze and compare the thermal-hydraulic performance. The results show that, although the heat transfer amount is comparable between the three finned tube designs, the pressure drop of the finned oblique-shaped tube is significantly lower by 53.6 - 58.7% than the finned circular tube at the same air inlet velocity. The oblique-shaped tubes have smaller frontal area and is streamlined, resulting in much smaller wake and lower flow velocity, thus significantly reducing the pressure loss. For a particular heat exchanger size and heat capacity, the fan power requirement for the finned oblique-shaped tube heat exchanger is the lowest.
{"title":"Numerical investigation of the thermal-hydraulic performance of finned oblique-shaped tube heat exchanger","authors":"Kent Loong Khoo, Chuan Sun, Nuttawut Lewpiriyawong, P. Lee, S. Chou","doi":"10.1109/ITHERM.2016.7517606","DOIUrl":"https://doi.org/10.1109/ITHERM.2016.7517606","url":null,"abstract":"Plate fin and tube heat exchangers (FTHX) are widely used in HVAC applications due to the high effectiveness to cost ratio for heat transfer between two fluids. For air-cooled residential air conditioning unit applications, the overall efficiency of the unit is limited by the air-side heat transfer coefficient, which is much lower than that of the refrigerant-side. In this paper, oblique-shaped tube with the same tube area is introduced to replace the circular tube in FTHX to enhance the overall thermal-hydraulic performance of the air-side heat transfer. Numerical investigations of plain FTHX with circular tube, elliptic tube and oblique-shaped tube are conducted to analyze and compare the thermal-hydraulic performance. The results show that, although the heat transfer amount is comparable between the three finned tube designs, the pressure drop of the finned oblique-shaped tube is significantly lower by 53.6 - 58.7% than the finned circular tube at the same air inlet velocity. The oblique-shaped tubes have smaller frontal area and is streamlined, resulting in much smaller wake and lower flow velocity, thus significantly reducing the pressure loss. For a particular heat exchanger size and heat capacity, the fan power requirement for the finned oblique-shaped tube heat exchanger is the lowest.","PeriodicalId":426908,"journal":{"name":"2016 15th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132959596","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}
Pub Date : 2016-05-01DOI: 10.1109/ITHERM.2016.7517643
Kenan Kocagoez
Increasing demand on wireless communication capabilities and device integration elevates thermal effects to a key boundary condition for future SoC designs. Questions arise like how long can the device be operated on certain radio conditions and for which ambient temperature regions, in a sustainable fashion. How fast will heat issues be perceived as inconvenient by the device user, how fast must device reliability be considered on high temperature and at which level needs a thermal runaway be prevented from kickoff by methods like autonomous shutdown? Wireless device performance management needs to deal with thermal challenges, understand radio communication hurdles and come up with an appropriate power throttling strategy.
{"title":"Wireless device performance management in temperature limited scenarios","authors":"Kenan Kocagoez","doi":"10.1109/ITHERM.2016.7517643","DOIUrl":"https://doi.org/10.1109/ITHERM.2016.7517643","url":null,"abstract":"Increasing demand on wireless communication capabilities and device integration elevates thermal effects to a key boundary condition for future SoC designs. Questions arise like how long can the device be operated on certain radio conditions and for which ambient temperature regions, in a sustainable fashion. How fast will heat issues be perceived as inconvenient by the device user, how fast must device reliability be considered on high temperature and at which level needs a thermal runaway be prevented from kickoff by methods like autonomous shutdown? Wireless device performance management needs to deal with thermal challenges, understand radio communication hurdles and come up with an appropriate power throttling strategy.","PeriodicalId":426908,"journal":{"name":"2016 15th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130543151","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}
Pub Date : 2016-05-01DOI: 10.1109/ITHERM.2016.7517716
H. Alissa, K. Nemati, Udaya L. N. Puvvadi, B. Sammakia, K. Ghose, M. Seymour, Russell Tipton, Ken Schneebeli
Data Centers are prone to power outages and cooling failures. During such events, complex transport interactions take place between the cooling system and the IT. Empirical data on this phenomenon is scarce in the current literature due to the complexity and size of such experiments. In this study, a facility level data center blowers cooling failure experiment is run and analyzed. Quantitative instrumentation includes pressure differentials, tile airflow, point air inlet temperature, contours air inlet temperature and IT IPMI data during failure-recovery. Qualitative measurements include IR imaging and airflow visualization via smoke trace. To our knowledge, this is the first experimental study in literature in which an actual multi aisle facility cooling failure is run with real IT (compute, Network and storage) load in the white space. This will enable a link between variations from the facility to the chip levels. Results show that by using external air inlet temperature sensors the containment configuration has a longer uptime during failure. However, the IPMI data shows the opposite. In fact, the RTT is reduced by ~70% when the external and internal sensors are compared. This occurs due external impedances formed by the containment during failure degrading IT airflow systems. The inconsistency between IT IPMI inlet sensors and externally placed IT or rack inlet sensors (based on best practices) are expected to increase as the airflow imbalances increase.
{"title":"Empirical analysis of blower cooling failure in containment: Effects on IT performance","authors":"H. Alissa, K. Nemati, Udaya L. N. Puvvadi, B. Sammakia, K. Ghose, M. Seymour, Russell Tipton, Ken Schneebeli","doi":"10.1109/ITHERM.2016.7517716","DOIUrl":"https://doi.org/10.1109/ITHERM.2016.7517716","url":null,"abstract":"Data Centers are prone to power outages and cooling failures. During such events, complex transport interactions take place between the cooling system and the IT. Empirical data on this phenomenon is scarce in the current literature due to the complexity and size of such experiments. In this study, a facility level data center blowers cooling failure experiment is run and analyzed. Quantitative instrumentation includes pressure differentials, tile airflow, point air inlet temperature, contours air inlet temperature and IT IPMI data during failure-recovery. Qualitative measurements include IR imaging and airflow visualization via smoke trace. To our knowledge, this is the first experimental study in literature in which an actual multi aisle facility cooling failure is run with real IT (compute, Network and storage) load in the white space. This will enable a link between variations from the facility to the chip levels. Results show that by using external air inlet temperature sensors the containment configuration has a longer uptime during failure. However, the IPMI data shows the opposite. In fact, the RTT is reduced by ~70% when the external and internal sensors are compared. This occurs due external impedances formed by the containment during failure degrading IT airflow systems. The inconsistency between IT IPMI inlet sensors and externally placed IT or rack inlet sensors (based on best practices) are expected to increase as the airflow imbalances increase.","PeriodicalId":426908,"journal":{"name":"2016 15th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125738374","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}
Pub Date : 2016-05-01DOI: 10.1109/ITHERM.2016.7517718
R. Khalid, Y. Joshi, A. Wemhoff
The data center industry currently focuses on initiatives to reduce its enormous energy consumption and minimize its adverse environmental impact. Modular data centers provide considerable operational flexibility in that they are mobile, and are manufactured using standard containers. This study aims at developing steady-state energy and exergy destruction models for modular data centers using EnergyPlus. Three different cooling approaches have been studied: direct expansion cooling, direct evaporative cooling, and free air cooling. This work shows that for hot and arid climates like those in South-West USA, augmenting DX cooling with evaporative and free-air cooling can result in energy savings of up to 38% and 36% respectively. Via exergy destruction calculations, it has been shown that the server inlet-outlet temperature difference is the biggest cause of exergy destruction and by using these passive cooling techniques, data centers can operate at lower temperatures to minimize wasted potential while maintaining PUE values.
{"title":"Rapid modeling tools for energy analysis of modular data centers","authors":"R. Khalid, Y. Joshi, A. Wemhoff","doi":"10.1109/ITHERM.2016.7517718","DOIUrl":"https://doi.org/10.1109/ITHERM.2016.7517718","url":null,"abstract":"The data center industry currently focuses on initiatives to reduce its enormous energy consumption and minimize its adverse environmental impact. Modular data centers provide considerable operational flexibility in that they are mobile, and are manufactured using standard containers. This study aims at developing steady-state energy and exergy destruction models for modular data centers using EnergyPlus. Three different cooling approaches have been studied: direct expansion cooling, direct evaporative cooling, and free air cooling. This work shows that for hot and arid climates like those in South-West USA, augmenting DX cooling with evaporative and free-air cooling can result in energy savings of up to 38% and 36% respectively. Via exergy destruction calculations, it has been shown that the server inlet-outlet temperature difference is the biggest cause of exergy destruction and by using these passive cooling techniques, data centers can operate at lower temperatures to minimize wasted potential while maintaining PUE values.","PeriodicalId":426908,"journal":{"name":"2016 15th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125766637","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}
Pub Date : 2016-05-01DOI: 10.1109/ITHERM.2016.7517647
E. Monier-Vinard, M. Nguyen, N. Laraqi, V. Bissuel, O. Daniel
The capability to efficiently transfer the heat away from high-powered electronic devices is a ceaseless challenge. More than ever, the aluminum or copper heat spreaders seem less suitable for maintaining the component sensitive temperature below manufacturer operating limits. Some emerging materials, such as Annealed Pyrolytic Graphite, are a new alternative to conventional solid conduction without the gravity dependence of a heat-pipe solution. Unfortunately, the ultrahigh performance rising of APG core is restricted to in-plane thermal conductivities which can be 200 times higher than its through-the-thickness conductivity. So a lower cross-plane thermal conductivity or a higher than anticipated interlayer thermal resistance would compromise APG-based materials as efficient heat spreaders. In order to analyze the sensitivity of these parameters on the effective thermal performances, an analytical model for predicting the temperature distribution over an APG flat-plate was developed. Its relevance was compared to numerical simulations and experiments for a set of boundary conditions.
{"title":"Steady-state temperature solution for early design of Annealed Pyrolytic Graphite heat spreader: Full results","authors":"E. Monier-Vinard, M. Nguyen, N. Laraqi, V. Bissuel, O. Daniel","doi":"10.1109/ITHERM.2016.7517647","DOIUrl":"https://doi.org/10.1109/ITHERM.2016.7517647","url":null,"abstract":"The capability to efficiently transfer the heat away from high-powered electronic devices is a ceaseless challenge. More than ever, the aluminum or copper heat spreaders seem less suitable for maintaining the component sensitive temperature below manufacturer operating limits. Some emerging materials, such as Annealed Pyrolytic Graphite, are a new alternative to conventional solid conduction without the gravity dependence of a heat-pipe solution. Unfortunately, the ultrahigh performance rising of APG core is restricted to in-plane thermal conductivities which can be 200 times higher than its through-the-thickness conductivity. So a lower cross-plane thermal conductivity or a higher than anticipated interlayer thermal resistance would compromise APG-based materials as efficient heat spreaders. In order to analyze the sensitivity of these parameters on the effective thermal performances, an analytical model for predicting the temperature distribution over an APG flat-plate was developed. Its relevance was compared to numerical simulations and experiments for a set of boundary conditions.","PeriodicalId":426908,"journal":{"name":"2016 15th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125121623","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}
Pub Date : 2016-05-01DOI: 10.1109/ITHERM.2016.7517582
Munshi M. Basit, Sudan Ahmed, M. Motalab, J. Roberts, J. Suhling, P. Lall
The mechanical behavior of lead free solder materials is often represented using the Anand viscoplastic constitutive model. This nine parameter model is built into popular commercial finite element codes, and is widely used in the electronic packaging industry. Reliability prediction results are often highly sensitive to the specified Anand parameters, and there are great variations in the available literature values for common solder alloys. In this work, we have explored the range of Anand parameters possible for four common SAC (Sn-Ag-Cu) alloys by testing samples with a wide range of microstructures. The lead free solder materials tested include 98.5Sn1.0Ag0.5Cu (SAC105), 97.5Sn2.0Ag0.5Cu (SAC205), 96.5Sn3.0Ag0.5Cu (SAC305), 95.5Sn4.0Ag0.5Cu (SAC405). These SACN05 solders have various Ag contents from N = 1.0 to 4.0%, and all contain 0.5% Cu. For each lead free solder alloy, four different cooling profiles and resultant microstructures have been investigated that yielded vastly different mechanical behaviors. These included water quenched (WQ), reflowed (RF), reflowed + 6 months of aging at 100°C, and reflowed + 12 months of aging at 100°C. The nine Anand parameters were determined for each unique solder alloy and microstructure from a set of stress strain tests performed at three different strain rates and five different temperatures (15 sets of conditions). After deriving the Anand parameters for each alloy and microstructure, the stress-strain curves have been calculated for various temperatures and strain rates, and excellent agreement was found between the predicted results and experimental stress-strain curves. The large range of microstructures examined has allowed us to explore the extreme values of the material properties and Anand parameters possible for a given SACN05 alloy. The WQ microstructures are extremely fine, and yield high mechanical properties at the upper limits possible for the solder alloys. The RF + 6 months of aging and RF + 12 months of aging microstructures are highly coarsened, and yield similar and highly degraded mechanical properties. After such a long durations of aging, any further changes in the microstructure, mechanical response, and mechanical properties will be rather small. Thus, the results for these “extreme aging” cases can be regarded as approaching the highest level of mechanical behavior degradation possible for a lead free solder material. Such limiting values found for a severely aged SAC alloy can be used by designers as a conservative set of constitutive parameters in finite element simulations.
{"title":"The Anand parameters for SAC solders after extreme aging","authors":"Munshi M. Basit, Sudan Ahmed, M. Motalab, J. Roberts, J. Suhling, P. Lall","doi":"10.1109/ITHERM.2016.7517582","DOIUrl":"https://doi.org/10.1109/ITHERM.2016.7517582","url":null,"abstract":"The mechanical behavior of lead free solder materials is often represented using the Anand viscoplastic constitutive model. This nine parameter model is built into popular commercial finite element codes, and is widely used in the electronic packaging industry. Reliability prediction results are often highly sensitive to the specified Anand parameters, and there are great variations in the available literature values for common solder alloys. In this work, we have explored the range of Anand parameters possible for four common SAC (Sn-Ag-Cu) alloys by testing samples with a wide range of microstructures. The lead free solder materials tested include 98.5Sn1.0Ag0.5Cu (SAC105), 97.5Sn2.0Ag0.5Cu (SAC205), 96.5Sn3.0Ag0.5Cu (SAC305), 95.5Sn4.0Ag0.5Cu (SAC405). These SACN05 solders have various Ag contents from N = 1.0 to 4.0%, and all contain 0.5% Cu. For each lead free solder alloy, four different cooling profiles and resultant microstructures have been investigated that yielded vastly different mechanical behaviors. These included water quenched (WQ), reflowed (RF), reflowed + 6 months of aging at 100°C, and reflowed + 12 months of aging at 100°C. The nine Anand parameters were determined for each unique solder alloy and microstructure from a set of stress strain tests performed at three different strain rates and five different temperatures (15 sets of conditions). After deriving the Anand parameters for each alloy and microstructure, the stress-strain curves have been calculated for various temperatures and strain rates, and excellent agreement was found between the predicted results and experimental stress-strain curves. The large range of microstructures examined has allowed us to explore the extreme values of the material properties and Anand parameters possible for a given SACN05 alloy. The WQ microstructures are extremely fine, and yield high mechanical properties at the upper limits possible for the solder alloys. The RF + 6 months of aging and RF + 12 months of aging microstructures are highly coarsened, and yield similar and highly degraded mechanical properties. After such a long durations of aging, any further changes in the microstructure, mechanical response, and mechanical properties will be rather small. Thus, the results for these “extreme aging” cases can be regarded as approaching the highest level of mechanical behavior degradation possible for a lead free solder material. Such limiting values found for a severely aged SAC alloy can be used by designers as a conservative set of constitutive parameters in finite element simulations.","PeriodicalId":426908,"journal":{"name":"2016 15th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129239913","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}
Pub Date : 2016-05-01DOI: 10.1109/ITHERM.2016.7517639
G. Arakere, M. Vujosevic, T. Embree
A modeling based methodology for prediction of the performance of board level interconnects of Ball Grid Array (BGA) components in board flexure tests is presented. Detailed work has been done to comprehend the physics of the problem so that sound theoretical framework is employed. A step-by-step validation of the developed computational model is conducted using a set of carefully designed tests. The model reproduces extremely well all the mechanical parameters measured in testing. The validated model is utilized to understand the impact of various package and board design parameters on BGA performance and risk. The developed modeling methodology is a key part in achieving the larger objective of replacing costly and time-consuming board flexure tests with modeling for BGA risk assessment. This methodology will also be a key enabler in providing comprehensive guidance to customers for board-level performance of Intel BGA components in manufacturing, assembly and test.
{"title":"Board level interconnect risk assessment in spherical bend","authors":"G. Arakere, M. Vujosevic, T. Embree","doi":"10.1109/ITHERM.2016.7517639","DOIUrl":"https://doi.org/10.1109/ITHERM.2016.7517639","url":null,"abstract":"A modeling based methodology for prediction of the performance of board level interconnects of Ball Grid Array (BGA) components in board flexure tests is presented. Detailed work has been done to comprehend the physics of the problem so that sound theoretical framework is employed. A step-by-step validation of the developed computational model is conducted using a set of carefully designed tests. The model reproduces extremely well all the mechanical parameters measured in testing. The validated model is utilized to understand the impact of various package and board design parameters on BGA performance and risk. The developed modeling methodology is a key part in achieving the larger objective of replacing costly and time-consuming board flexure tests with modeling for BGA risk assessment. This methodology will also be a key enabler in providing comprehensive guidance to customers for board-level performance of Intel BGA components in manufacturing, assembly and test.","PeriodicalId":426908,"journal":{"name":"2016 15th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127622097","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}
Pub Date : 2016-05-01DOI: 10.1109/ITHERM.2016.7517532
Xuchen Zhang, Mohamed H. Nasr, David C. Woodrum, C. Green, P. Kottke, Thomas E. Sarvey, Y. Joshi, S. Sitaraman, A. Fedorov, M. Bakir
In this work, we designed, fabricated and characterized a novel hotspot testbed to dissipate ultra-high power density by two-phase convective boiling of refrigerant in a microgap with integrated micropin-fins and isolation air trenches around resistance heaters. The 300 μm long, 200 μm wide, and 10 μm tall microgap with 4 μm diameter micropin-fins was batch micro-fabricated in silicon. The 40 μm wide and 180 μm deep isolation air trenches around the heater and a SiO2 passivation layer were used to provide thermal isolation. The testbed dissipates a power density of up to 4.75 kW/cm2 using R134a refrigerant as the coolant. Thermal resistance and pumping power were compared between the micropin-fin device of interest and a reference `empty microgap' device to assess tradeoffs in performance. Micropin-fins were found to slightly reduce thermal resistance at the cost of a large increase in pumping power. In addition to experimental work, thermomechanical simulations were implemented to analyze the reliability of the device for high pressure conditions.
{"title":"Design, microfabrication and thermal characterization of a hotspot cooler testbed for convective boiling experiments in extreme-microgap with integrated micropin-fins","authors":"Xuchen Zhang, Mohamed H. Nasr, David C. Woodrum, C. Green, P. Kottke, Thomas E. Sarvey, Y. Joshi, S. Sitaraman, A. Fedorov, M. Bakir","doi":"10.1109/ITHERM.2016.7517532","DOIUrl":"https://doi.org/10.1109/ITHERM.2016.7517532","url":null,"abstract":"In this work, we designed, fabricated and characterized a novel hotspot testbed to dissipate ultra-high power density by two-phase convective boiling of refrigerant in a microgap with integrated micropin-fins and isolation air trenches around resistance heaters. The 300 μm long, 200 μm wide, and 10 μm tall microgap with 4 μm diameter micropin-fins was batch micro-fabricated in silicon. The 40 μm wide and 180 μm deep isolation air trenches around the heater and a SiO2 passivation layer were used to provide thermal isolation. The testbed dissipates a power density of up to 4.75 kW/cm2 using R134a refrigerant as the coolant. Thermal resistance and pumping power were compared between the micropin-fin device of interest and a reference `empty microgap' device to assess tradeoffs in performance. Micropin-fins were found to slightly reduce thermal resistance at the cost of a large increase in pumping power. In addition to experimental work, thermomechanical simulations were implemented to analyze the reliability of the device for high pressure conditions.","PeriodicalId":426908,"journal":{"name":"2016 15th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127857997","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}
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