Pub Date : 1900-01-01DOI: 10.1109/SEMI-THERM.2017.7896939
C. Nelson, J. Galloway, C. Henry, W. Kelley
Due to the differences in thermal expansion coefficients (CTE) of materials within a microelectronic package, a package can warp in convex and concave shapes during temperature excursions of assembly and end use conditions. In large flip chip ball grid array (FCBGA) style packages, warpage plays a major factor in the long term reliability and performance of the package. When fitted with a lid, FCBGA packages use a thermal interface material (TIM) between the die and lid surfaces. Due to package warpage and other mechanical stresses, a TIM can experience a range of compressive and tensile loads during package assembly, board mount, and end use conditions. High power applications using FCBGA style packages require accurate estimates for the resistance of the TIM layer to enable accurate prediction of junction temperatures and performance. Literature indicates that the TIM resistance is higher along the edge and corner regions of the die due in part to the larger bond line thickness (BLT) in these regions. Measurements reported in this study show that this increase cannot fully be explained by larger BLT. An alternative theory is proposed that suggests the thermal performance of a TIM in a package is also dependent on its stress state and stress history. The stress state of a TIM impacts the material's contact resistance, cohesive/adhesive bond behavior, and internal resistance between filler particles. The increase in resistance for the same BLT in compression versus tensile stress can be greater by over fifty percent. In addition, experimental testing has demonstrated that tensile stress in TIMs may contribute to voiding.
{"title":"Thermal performance of TIMs during compressive and tensile stress states","authors":"C. Nelson, J. Galloway, C. Henry, W. Kelley","doi":"10.1109/SEMI-THERM.2017.7896939","DOIUrl":"https://doi.org/10.1109/SEMI-THERM.2017.7896939","url":null,"abstract":"Due to the differences in thermal expansion coefficients (CTE) of materials within a microelectronic package, a package can warp in convex and concave shapes during temperature excursions of assembly and end use conditions. In large flip chip ball grid array (FCBGA) style packages, warpage plays a major factor in the long term reliability and performance of the package. When fitted with a lid, FCBGA packages use a thermal interface material (TIM) between the die and lid surfaces. Due to package warpage and other mechanical stresses, a TIM can experience a range of compressive and tensile loads during package assembly, board mount, and end use conditions. High power applications using FCBGA style packages require accurate estimates for the resistance of the TIM layer to enable accurate prediction of junction temperatures and performance. Literature indicates that the TIM resistance is higher along the edge and corner regions of the die due in part to the larger bond line thickness (BLT) in these regions. Measurements reported in this study show that this increase cannot fully be explained by larger BLT. An alternative theory is proposed that suggests the thermal performance of a TIM in a package is also dependent on its stress state and stress history. The stress state of a TIM impacts the material's contact resistance, cohesive/adhesive bond behavior, and internal resistance between filler particles. The increase in resistance for the same BLT in compression versus tensile stress can be greater by over fifty percent. In addition, experimental testing has demonstrated that tensile stress in TIMs may contribute to voiding.","PeriodicalId":442782,"journal":{"name":"2017 33rd Thermal Measurement, Modeling & Management Symposium (SEMI-THERM)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130802372","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 : 1900-01-01DOI: 10.1109/SEMI-THERM.2017.7896940
F. Streb, D. Schweitzer, M. Mengel, T. Lampke
The thermal contact between semiconductor component and heat sink has a strong influence on performance and lifetime of electrical devices. Thermal interface materials are used to improve this contact. In this methodology study we compare three common measurement methods used for the characterization of thermal interface materials: transient plane source, DynTIM (similar to the ASTM D5740 standard) and LaserFlash. We investigated a wide range of typical thermal interface materials in order to explore the limits of the different measurement systems. A guideline for the right usage and limits of the individual methods is given.
{"title":"Evaluation of characterization methods for solid thermal interface materials","authors":"F. Streb, D. Schweitzer, M. Mengel, T. Lampke","doi":"10.1109/SEMI-THERM.2017.7896940","DOIUrl":"https://doi.org/10.1109/SEMI-THERM.2017.7896940","url":null,"abstract":"The thermal contact between semiconductor component and heat sink has a strong influence on performance and lifetime of electrical devices. Thermal interface materials are used to improve this contact. In this methodology study we compare three common measurement methods used for the characterization of thermal interface materials: transient plane source, DynTIM (similar to the ASTM D5740 standard) and LaserFlash. We investigated a wide range of typical thermal interface materials in order to explore the limits of the different measurement systems. A guideline for the right usage and limits of the individual methods is given.","PeriodicalId":442782,"journal":{"name":"2017 33rd Thermal Measurement, Modeling & Management Symposium (SEMI-THERM)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122367675","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 : 1900-01-01DOI: 10.1109/SEMI-THERM.2017.7896913
A. Ortega, M. del Valle, Carol Caceres
Crossflow heat exchangers are key components of both centralized (e.g. CRACs) and decentralized (rear door, in-row) cooling equipment utilized in data center thermal management systems. Modeling of their behavior in steady state is well documented but transient or dynamic operation, whether by intent or as a result of a system failure, has not been well documented. In “smart cooling” scenarios, cooling should be modulated with heating (i.e. IT) load which can vary with time and space as IT load varies within a rack and within the data center room. Cooling is optimally utilized when the cooling load follows or even anticipates the heating (IT) load and as such the heat exchanger operates in a dynamically controlled mode. In data center operation, there is also interest in understanding their behavior in case of system malfunctions such as pump or chiller failures which results in transient operation. The MATLAB™ simulation code VHTX was developed in order to simulate the performance of crossflow heat exchangers in both steady and dynamic operation. It is a standalone code for simulation of heat exchanger networks and core code elements are also being embedded into or coupled with other simulation environments such as MATLAB SIMULINK™ for control investigations, VTAS for data center system thermodynamic and energy analysis, and CFD codes for room simulations. This paper describes the basic formulation of the VHTX solver and its validation against research quality data on heat exchanger cores. It is shown that the code can accurately predict the coolant flow distribution within the heat exchanger core and its dynamic response to temporal events such as modulation of the coolant flow rate or temperature to match the air side thermal load. A case study simulating a typical rear door heat exchanger is presented as an example of the use of the code in a data center simulation.
{"title":"VHTX: A code for simulation of steady state and dynamic response of single or multiple networked cross flow heat exchangers in data center thermal management systems","authors":"A. Ortega, M. del Valle, Carol Caceres","doi":"10.1109/SEMI-THERM.2017.7896913","DOIUrl":"https://doi.org/10.1109/SEMI-THERM.2017.7896913","url":null,"abstract":"Crossflow heat exchangers are key components of both centralized (e.g. CRACs) and decentralized (rear door, in-row) cooling equipment utilized in data center thermal management systems. Modeling of their behavior in steady state is well documented but transient or dynamic operation, whether by intent or as a result of a system failure, has not been well documented. In “smart cooling” scenarios, cooling should be modulated with heating (i.e. IT) load which can vary with time and space as IT load varies within a rack and within the data center room. Cooling is optimally utilized when the cooling load follows or even anticipates the heating (IT) load and as such the heat exchanger operates in a dynamically controlled mode. In data center operation, there is also interest in understanding their behavior in case of system malfunctions such as pump or chiller failures which results in transient operation. The MATLAB™ simulation code VHTX was developed in order to simulate the performance of crossflow heat exchangers in both steady and dynamic operation. It is a standalone code for simulation of heat exchanger networks and core code elements are also being embedded into or coupled with other simulation environments such as MATLAB SIMULINK™ for control investigations, VTAS for data center system thermodynamic and energy analysis, and CFD codes for room simulations. This paper describes the basic formulation of the VHTX solver and its validation against research quality data on heat exchanger cores. It is shown that the code can accurately predict the coolant flow distribution within the heat exchanger core and its dynamic response to temporal events such as modulation of the coolant flow rate or temperature to match the air side thermal load. A case study simulating a typical rear door heat exchanger is presented as an example of the use of the code in a data center simulation.","PeriodicalId":442782,"journal":{"name":"2017 33rd Thermal Measurement, Modeling & Management Symposium (SEMI-THERM)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127939458","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 : 1900-01-01DOI: 10.1109/SEMI-THERM.2017.7896928
E. Chenelly
This paper presents a method to optimize surface temperature of a mobile device by varying the thickness of an air gap as a function of distance from a heat source. It is demonstrated that this type of design offers a higher power budget when compared to a uniform air gap. The paper provides: ● A derivation of the equation used to calculate a radially varying air gap. It is based on the equation for radial fin efficiency which has been used extensively in electronics cooling but has not yet been applied to this problem. ● A description of how to manufacture a curved heat spreader used to maintain the varying air gap for both an ideal circular shape and a realistic phablet. ● A comparison of performance to a flat plate in both cases (ideal and phablet). In the case of a phablet with a partial heat spreader, the curved heat spreader can increase system power budget by 13% and the SoC power budget by as much as 25% when compared to a flat version. ● A discussion of the next steps
{"title":"Radially varying air gap for near-ideal low cost passive heat spreaders","authors":"E. Chenelly","doi":"10.1109/SEMI-THERM.2017.7896928","DOIUrl":"https://doi.org/10.1109/SEMI-THERM.2017.7896928","url":null,"abstract":"This paper presents a method to optimize surface temperature of a mobile device by varying the thickness of an air gap as a function of distance from a heat source. It is demonstrated that this type of design offers a higher power budget when compared to a uniform air gap. The paper provides: ● A derivation of the equation used to calculate a radially varying air gap. It is based on the equation for radial fin efficiency which has been used extensively in electronics cooling but has not yet been applied to this problem. ● A description of how to manufacture a curved heat spreader used to maintain the varying air gap for both an ideal circular shape and a realistic phablet. ● A comparison of performance to a flat plate in both cases (ideal and phablet). In the case of a phablet with a partial heat spreader, the curved heat spreader can increase system power budget by 13% and the SoC power budget by as much as 25% when compared to a flat version. ● A discussion of the next steps","PeriodicalId":442782,"journal":{"name":"2017 33rd Thermal Measurement, Modeling & Management Symposium (SEMI-THERM)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121087842","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 : 1900-01-01DOI: 10.1109/SEMI-THERM.2017.7896930
Hong-Long Chen, Chi-Chuan Wang
The objective of this paper is to explore the technique for lowering the contraction and hydraulic developing region pressure drop, in order to gain more airflow for electronic cooling heat sink for the same footprint and fin number. By combining two different geometrical perimeter shapes of fins, odd number is rectangular shape, and even number is trapezoidal shape, this new fin module design gains extra 10% airflow with little loss or equivalent thermal performance. Current data center server is suffering from too little airflow to cool essential chips due to enormous flow impedance for packing too many components inside. This technology is the solution to resolve this bottleneck. The precious extra 10% more airflow not only cools CPU chip itself; but also quite beneficial to cool other heating components inside servers. Also, this new design excels in low velocity of 2 m/s for thermal performance compared to original design. Lower velocity is equal to lower RPM of fan that leads to the advantage of energy saving.
{"title":"Analytical and experimental verification of interleaved trapezoidal heat sink","authors":"Hong-Long Chen, Chi-Chuan Wang","doi":"10.1109/SEMI-THERM.2017.7896930","DOIUrl":"https://doi.org/10.1109/SEMI-THERM.2017.7896930","url":null,"abstract":"The objective of this paper is to explore the technique for lowering the contraction and hydraulic developing region pressure drop, in order to gain more airflow for electronic cooling heat sink for the same footprint and fin number. By combining two different geometrical perimeter shapes of fins, odd number is rectangular shape, and even number is trapezoidal shape, this new fin module design gains extra 10% airflow with little loss or equivalent thermal performance. Current data center server is suffering from too little airflow to cool essential chips due to enormous flow impedance for packing too many components inside. This technology is the solution to resolve this bottleneck. The precious extra 10% more airflow not only cools CPU chip itself; but also quite beneficial to cool other heating components inside servers. Also, this new design excels in low velocity of 2 m/s for thermal performance compared to original design. Lower velocity is equal to lower RPM of fan that leads to the advantage of energy saving.","PeriodicalId":442782,"journal":{"name":"2017 33rd Thermal Measurement, Modeling & Management Symposium (SEMI-THERM)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117044859","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 : 1900-01-01DOI: 10.1109/SEMI-THERM.2017.7896923
Chuan Song, Yanbing Sun, N. Ahuja, Xiaogang Sun, Litrin Jiang, Abishai Daniel, R. Khanna, T. Zhou, Xiaoping Zhou, Lifei Zhang
This paper introduced one optimized proactive cooling management approach based on power variation trend analysis. Through analyzing the data center historical power telemetries, the power predictor is able to predicate power variation with 5– 15 minutes granularity. The cooling controller uses the observed heat information and estimated thermal variation trend to drive CRAC to manage temperature situation at prediction window. To validate cooling results from different cooling parameters, one risk level evaluation method is proposed and the experiments for different prediction window are conducted and the result is presented.
{"title":"Using power trend predicator to improve datacenter thermal management efficiency","authors":"Chuan Song, Yanbing Sun, N. Ahuja, Xiaogang Sun, Litrin Jiang, Abishai Daniel, R. Khanna, T. Zhou, Xiaoping Zhou, Lifei Zhang","doi":"10.1109/SEMI-THERM.2017.7896923","DOIUrl":"https://doi.org/10.1109/SEMI-THERM.2017.7896923","url":null,"abstract":"This paper introduced one optimized proactive cooling management approach based on power variation trend analysis. Through analyzing the data center historical power telemetries, the power predictor is able to predicate power variation with 5– 15 minutes granularity. The cooling controller uses the observed heat information and estimated thermal variation trend to drive CRAC to manage temperature situation at prediction window. To validate cooling results from different cooling parameters, one risk level evaluation method is proposed and the experiments for different prediction window are conducted and the result is presented.","PeriodicalId":442782,"journal":{"name":"2017 33rd Thermal Measurement, Modeling & Management Symposium (SEMI-THERM)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129943794","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 : 1900-01-01DOI: 10.1109/SEMI-THERM.2017.7896934
Mei-chien Lu
Driven by technology trends towards 2.5D and 3D IC integration for higher bandwidth and small form factor, the demand for high thermal conductivity materials is growing in order to facilitate thermal management. At the same time, constraints in critical dimensions at the bondline set new challenges for materials and processing. This study analyzes both advancement in high thermal conductivity materials and improvements in integration for thermal management. Polymeric matrix materials often used as underfill in advanced packaging currently was forced to the use of small fillers for 3D IC integration. This reduction of filler size in polymer composite tends to reduce its ability to improve thermal conductivity. Presently, however, the increasing development and adoption of wafer level packaging offers new processing capability and cost reduction. Nonconductive film has evolved as a new form for underfill materials associated with laminating processes. Thermal conductivity improvement in underfill can therefore be categorized into two categories, the improvement of composite materials and the consideration of new alternative materials. This study uses mathematical models to explain the evolution of anisotropic properties of high thermal conductivity nonconductive film materials. Finite element analysis is conducted to assess the ability of hot spot reduction in a 3D IC system with the innovative anisotropic thin film composite underfill. The high bandwidth memory JEDEC standard 3D IC structure (HBM2) integrated with anisotropic thin film composite underfill is used as an example for this study. Discussions are expanded to cost analysis due to the needs of additional process steps to integrate the new materials into advanced packaging for 3D IC integration.
{"title":"Effects of anisotropic nonconductive film properties on 3D IC integration","authors":"Mei-chien Lu","doi":"10.1109/SEMI-THERM.2017.7896934","DOIUrl":"https://doi.org/10.1109/SEMI-THERM.2017.7896934","url":null,"abstract":"Driven by technology trends towards 2.5D and 3D IC integration for higher bandwidth and small form factor, the demand for high thermal conductivity materials is growing in order to facilitate thermal management. At the same time, constraints in critical dimensions at the bondline set new challenges for materials and processing. This study analyzes both advancement in high thermal conductivity materials and improvements in integration for thermal management. Polymeric matrix materials often used as underfill in advanced packaging currently was forced to the use of small fillers for 3D IC integration. This reduction of filler size in polymer composite tends to reduce its ability to improve thermal conductivity. Presently, however, the increasing development and adoption of wafer level packaging offers new processing capability and cost reduction. Nonconductive film has evolved as a new form for underfill materials associated with laminating processes. Thermal conductivity improvement in underfill can therefore be categorized into two categories, the improvement of composite materials and the consideration of new alternative materials. This study uses mathematical models to explain the evolution of anisotropic properties of high thermal conductivity nonconductive film materials. Finite element analysis is conducted to assess the ability of hot spot reduction in a 3D IC system with the innovative anisotropic thin film composite underfill. The high bandwidth memory JEDEC standard 3D IC structure (HBM2) integrated with anisotropic thin film composite underfill is used as an example for this study. Discussions are expanded to cost analysis due to the needs of additional process steps to integrate the new materials into advanced packaging for 3D IC integration.","PeriodicalId":442782,"journal":{"name":"2017 33rd Thermal Measurement, Modeling & Management Symposium (SEMI-THERM)","volume":"58 27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134104551","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 : 1900-01-01DOI: 10.1109/SEMI-THERM.2017.7896944
Mian Tao, S. Lee
The non-uniform junction temperature may exist in the high-power light-emitting diode (LED) of flip-chip architecture. Detecting the local hot area on the chip is of great importance to the LED thermal management. Most of the common LEDs exhibit a lower forward voltage when its junction temperature is elevated. The local forward voltage deviation will lead to non-uniform current distribution and consequently affect the light distribution. In this paper, a hotspot detection method is proposed utilizing this intrinsic thermal-electrical property. The transient light emission distribution on the chip is measured by a system consists of a common microscope and an optical sensor. The spatial solution is high enough for practical application. The experiments are conducted on different LED chips. Various junction temperature distributions are generated by different patterns of the chip bonding pads. The measurement results suggest that the local hot area has a higher light intensity. The proposed method can be used to detect the location of the local hot area in the LED chip.
{"title":"Transient light emission microscopy for detecting the non-uniform junction temperature in flip-chip light emitting diodes","authors":"Mian Tao, S. Lee","doi":"10.1109/SEMI-THERM.2017.7896944","DOIUrl":"https://doi.org/10.1109/SEMI-THERM.2017.7896944","url":null,"abstract":"The non-uniform junction temperature may exist in the high-power light-emitting diode (LED) of flip-chip architecture. Detecting the local hot area on the chip is of great importance to the LED thermal management. Most of the common LEDs exhibit a lower forward voltage when its junction temperature is elevated. The local forward voltage deviation will lead to non-uniform current distribution and consequently affect the light distribution. In this paper, a hotspot detection method is proposed utilizing this intrinsic thermal-electrical property. The transient light emission distribution on the chip is measured by a system consists of a common microscope and an optical sensor. The spatial solution is high enough for practical application. The experiments are conducted on different LED chips. Various junction temperature distributions are generated by different patterns of the chip bonding pads. The measurement results suggest that the local hot area has a higher light intensity. The proposed method can be used to detect the location of the local hot area in the LED chip.","PeriodicalId":442782,"journal":{"name":"2017 33rd Thermal Measurement, Modeling & Management Symposium (SEMI-THERM)","volume":"280 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126908211","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 : 1900-01-01DOI: 10.1109/SEMI-THERM.2017.7896914
Jared A. Shipman, S. Chigullapalli, J. Mata, Thomas A. Martin
IoT space is very dynamic and there is a multidimensional matrix of end-customer use-cases possible with the same module. A simple spec of Tcasemax and Thermal Design Power (TDP) will no longer suffice for an accurate design of the system complexity. The basic principle in this paper is to create a standard temperature and power envelope based on two broad classification of use cases: Application Processing Only (AP) and Application + Communication Processing (AP+CP). The final curves will change based on the thermal limiters, the type of thermal solution used, stack-up details, etc. All analysis is done using a systematic system engineering approach.
{"title":"Thermal power envelope for IoT modules","authors":"Jared A. Shipman, S. Chigullapalli, J. Mata, Thomas A. Martin","doi":"10.1109/SEMI-THERM.2017.7896914","DOIUrl":"https://doi.org/10.1109/SEMI-THERM.2017.7896914","url":null,"abstract":"IoT space is very dynamic and there is a multidimensional matrix of end-customer use-cases possible with the same module. A simple spec of Tcasemax and Thermal Design Power (TDP) will no longer suffice for an accurate design of the system complexity. The basic principle in this paper is to create a standard temperature and power envelope based on two broad classification of use cases: Application Processing Only (AP) and Application + Communication Processing (AP+CP). The final curves will change based on the thermal limiters, the type of thermal solution used, stack-up details, etc. All analysis is done using a systematic system engineering approach.","PeriodicalId":442782,"journal":{"name":"2017 33rd Thermal Measurement, Modeling & Management Symposium (SEMI-THERM)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114259582","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 : 1900-01-01DOI: 10.1109/SEMI-THERM.2017.7896919
Yiwu Kuang, W. Wang, Rui Zhuan
The performance of two phase heat sinks can be greatly affected by the coolant flow instabilities. For the applications in electronic cooling system, the micro-channel heat sink usually consists of some parallel channels and common header or manifold, the flow instabilities can be an especially noticeable problem. Flow instabilities will cause a severe reverse flow and subsequent maldistribution of cooling medium in the header. In addition, the instabilities degrade the total heat transfer performance of the heat sink and lead to a remarkable variation of pressure drop. As the cooling medium coming from the upstream pipe is always in two-phase flow state, the common header filled with this coming vapor will serve as a buffer tank. This tank provides significant compressible volume to the downstream heated channels and may lead to sustained pressure and temperature oscillations in the system. In this paper, the periodic reversed flow and maldistribution of fluid in a heat sink with parallel micro channels are studied experimentally. Visualization results are presented simultaneously. The effects of channel size, surface tension and fluid viscosity are considered. The results show that the micro-channel heat sinks are especially susceptible to flow instabilities and fluid maldistribution. The channel size and the surface tension effect on the reverse flow as well. And the heat transfer performance deteriorates when the ammonia reverse flow occurs.
{"title":"Oscillating flow in a heat sink with parallel micro channels","authors":"Yiwu Kuang, W. Wang, Rui Zhuan","doi":"10.1109/SEMI-THERM.2017.7896919","DOIUrl":"https://doi.org/10.1109/SEMI-THERM.2017.7896919","url":null,"abstract":"The performance of two phase heat sinks can be greatly affected by the coolant flow instabilities. For the applications in electronic cooling system, the micro-channel heat sink usually consists of some parallel channels and common header or manifold, the flow instabilities can be an especially noticeable problem. Flow instabilities will cause a severe reverse flow and subsequent maldistribution of cooling medium in the header. In addition, the instabilities degrade the total heat transfer performance of the heat sink and lead to a remarkable variation of pressure drop. As the cooling medium coming from the upstream pipe is always in two-phase flow state, the common header filled with this coming vapor will serve as a buffer tank. This tank provides significant compressible volume to the downstream heated channels and may lead to sustained pressure and temperature oscillations in the system. In this paper, the periodic reversed flow and maldistribution of fluid in a heat sink with parallel micro channels are studied experimentally. Visualization results are presented simultaneously. The effects of channel size, surface tension and fluid viscosity are considered. The results show that the micro-channel heat sinks are especially susceptible to flow instabilities and fluid maldistribution. The channel size and the surface tension effect on the reverse flow as well. And the heat transfer performance deteriorates when the ammonia reverse flow occurs.","PeriodicalId":442782,"journal":{"name":"2017 33rd Thermal Measurement, Modeling & Management Symposium (SEMI-THERM)","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124948350","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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