Pub Date : 2011-03-20DOI: 10.1109/STHERM.2011.5767205
A. Ortega, K. S. H. Potluri, B. Hassel
In previous work, we have shown that in single phase flow, stacked multi-layer liquid cooled heat sinks with square or circular channels have advantages over traditional single layer designs with high aspect ratio channels. In particular, it has been found that the thermal performance per unit pressure drop, as characterized by cost effectiveness metric, can be superior when properly optimized. The primary benefits seem to be increased surface area per unit volume available for convective cooling and increased flow area without sacrificing heat conduction paths to the coolant channel surfaces. The principle drawback of stacked multi-layer heat sinks is the difficulty in conducting heat through the metal matrix to the coolant channels farthest from the surface where heat is applied. In previous work we used validated twoequation porous media formulations to model the behavior of these “deterministic” porous heat sinks with good success. Porous media formulations reduce the geometric complexity of the problem to two parameters, namely porosity and pore diameter. With this approach, it was shown that geometric scale variation, in which either the characteristic pore diameter of the channels in each layer or the layer porosity was allowed to vary from layer to layer, could result in lower thermal resistance and lower pressure drop, compared to heat sinks in which the pore diameter and porosity were uniform. Furthermore, the behavior of pore-diameter scaled compared to porosity-scaled heat sinks was quite distinct. In the present study, we examine the behavior of deterministic stacked mini-channel heat sinks with parallel channels of square cross section, where the porosity is varied from layer to layer, but the channel diameter is fixed. The scaling rules, developed in the porous media equivalent models, are based on biologically inspired constructal principles. Such scaling principles have lead to superior optimal designs in a number of engineering applications. Experimentally validated conjugate CFD simulations were used to characterize the heat sinks. It was found that when the porosity is allowed to increase away from the surface onto which heat is applied, the increased mass flow and advection counteracts the cumulative conduction resistance thereby producing a more isothermal heat sink and a lower overall thermal resistance. Increasing the porosity away from the heat source also increased the flow area thereby producing lower overall pressure drop, compared to a non-scaled heat sink, in which the first layer of channels is the same in both cases. The volumetric thermal performance of the porosity scaled heat sinks exceeded the performance of non scaled heat sinks over a wide range of porosity scaling ratios and the pressure drop was consistently lower.
{"title":"An investigation of multi-layer mini-channel heat sinks with channel geometric scale variation suggested by constructal scaling principles","authors":"A. Ortega, K. S. H. Potluri, B. Hassel","doi":"10.1109/STHERM.2011.5767205","DOIUrl":"https://doi.org/10.1109/STHERM.2011.5767205","url":null,"abstract":"In previous work, we have shown that in single phase flow, stacked multi-layer liquid cooled heat sinks with square or circular channels have advantages over traditional single layer designs with high aspect ratio channels. In particular, it has been found that the thermal performance per unit pressure drop, as characterized by cost effectiveness metric, can be superior when properly optimized. The primary benefits seem to be increased surface area per unit volume available for convective cooling and increased flow area without sacrificing heat conduction paths to the coolant channel surfaces. The principle drawback of stacked multi-layer heat sinks is the difficulty in conducting heat through the metal matrix to the coolant channels farthest from the surface where heat is applied. In previous work we used validated twoequation porous media formulations to model the behavior of these “deterministic” porous heat sinks with good success. Porous media formulations reduce the geometric complexity of the problem to two parameters, namely porosity and pore diameter. With this approach, it was shown that geometric scale variation, in which either the characteristic pore diameter of the channels in each layer or the layer porosity was allowed to vary from layer to layer, could result in lower thermal resistance and lower pressure drop, compared to heat sinks in which the pore diameter and porosity were uniform. Furthermore, the behavior of pore-diameter scaled compared to porosity-scaled heat sinks was quite distinct. In the present study, we examine the behavior of deterministic stacked mini-channel heat sinks with parallel channels of square cross section, where the porosity is varied from layer to layer, but the channel diameter is fixed. The scaling rules, developed in the porous media equivalent models, are based on biologically inspired constructal principles. Such scaling principles have lead to superior optimal designs in a number of engineering applications. Experimentally validated conjugate CFD simulations were used to characterize the heat sinks. It was found that when the porosity is allowed to increase away from the surface onto which heat is applied, the increased mass flow and advection counteracts the cumulative conduction resistance thereby producing a more isothermal heat sink and a lower overall thermal resistance. Increasing the porosity away from the heat source also increased the flow area thereby producing lower overall pressure drop, compared to a non-scaled heat sink, in which the first layer of channels is the same in both cases. The volumetric thermal performance of the porosity scaled heat sinks exceeded the performance of non scaled heat sinks over a wide range of porosity scaling ratios and the pressure drop was consistently lower.","PeriodicalId":128077,"journal":{"name":"2011 27th Annual IEEE Semiconductor Thermal Measurement and Management Symposium","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131127272","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 : 2011-03-20DOI: 10.1109/STHERM.2011.5767173
L. Klein, P. J. Singh, M. Schappert, Marc Griffel, H. Hamann
The recent interest in air-side cooling and the spread of data centers into geographies with higher levels of atmospheric contamination is requiring more attention towards air quality management in data centers. One concern of air side economization is an increase in contamination levels potentially leading to more failures and outages of the IT equipment. In this paper we describe a corrosion measurement and management technology that enables high accuracy and real time monitoring of the gaseous contamination. The synergistic effects of indoor air temperature and relative humidity on corrosion rates are investigated and the spatial and the temporal variations of the corrosivity are established. Filtering of the outside air, both for particulate and gaseous contamination can mitigate air contamination in data centers. Implementing a facility wide air quality monitoring system promises the safe use of air-side economizers and would establish appropriate filtering, which enable early prevention of critical situations for information technology (IT) equipment operations.
{"title":"Corrosion management for data centers","authors":"L. Klein, P. J. Singh, M. Schappert, Marc Griffel, H. Hamann","doi":"10.1109/STHERM.2011.5767173","DOIUrl":"https://doi.org/10.1109/STHERM.2011.5767173","url":null,"abstract":"The recent interest in air-side cooling and the spread of data centers into geographies with higher levels of atmospheric contamination is requiring more attention towards air quality management in data centers. One concern of air side economization is an increase in contamination levels potentially leading to more failures and outages of the IT equipment. In this paper we describe a corrosion measurement and management technology that enables high accuracy and real time monitoring of the gaseous contamination. The synergistic effects of indoor air temperature and relative humidity on corrosion rates are investigated and the spatial and the temporal variations of the corrosivity are established. Filtering of the outside air, both for particulate and gaseous contamination can mitigate air contamination in data centers. Implementing a facility wide air quality monitoring system promises the safe use of air-side economizers and would establish appropriate filtering, which enable early prevention of critical situations for information technology (IT) equipment operations.","PeriodicalId":128077,"journal":{"name":"2011 27th Annual IEEE Semiconductor Thermal Measurement and Management Symposium","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134213733","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 : 2011-03-20DOI: 10.1109/STHERM.2011.5767185
Travis Mikjaniec, A. Manning, Derrick Small, J. Vangilder
This paper will describe two recent advances in Computational Fluid Dynamics (CFD) modeling as it pertains to data center design. In particular, the paper will define the use of the Capture Index (CI) in data center analysis, and will discuss the importance of accurately modeling coolers. Secondly, the article will describe Mentor Graphics' own $30M data center project currently in development. Two new centralized data centers will consolidate the resources of more than 20 local data centers in Europe and North America. One will be built in Shannon, Ireland, and another in Wilsonville, Oregon. By consolidating data centers, Mentor will see gains in capacity, efficiency, and redundancy while reducing operational costs.
{"title":"Data center design using improved CFD modeling and cost reduction analysis","authors":"Travis Mikjaniec, A. Manning, Derrick Small, J. Vangilder","doi":"10.1109/STHERM.2011.5767185","DOIUrl":"https://doi.org/10.1109/STHERM.2011.5767185","url":null,"abstract":"This paper will describe two recent advances in Computational Fluid Dynamics (CFD) modeling as it pertains to data center design. In particular, the paper will define the use of the Capture Index (CI) in data center analysis, and will discuss the importance of accurately modeling coolers. Secondly, the article will describe Mentor Graphics' own $30M data center project currently in development. Two new centralized data centers will consolidate the resources of more than 20 local data centers in Europe and North America. One will be built in Shannon, Ireland, and another in Wilsonville, Oregon. By consolidating data centers, Mentor will see gains in capacity, efficiency, and redundancy while reducing operational costs.","PeriodicalId":128077,"journal":{"name":"2011 27th Annual IEEE Semiconductor Thermal Measurement and Management Symposium","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114297798","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 : 2011-03-20DOI: 10.1109/STHERM.2011.5767178
S. Roy
Surface temperatures of electronic equipment and other machinery are an important design constraint since excessively high temperatures can be a safety hazard. Thus, government and industry standards have been established for maximum acceptable temperatures of hot surfaces that may be touched. Unfortunately, their recommendations are often limited to a few broad classes of materials, and appear to differ substantially from each other. They also do not adequately account for the unique properties of many advanced materials that have been developed recently. In order to address these issues, this paper presents explicit equations that can be used to set thermal safety criteria depending on the material and time of contact. They have been developed using data that are the basis for previous standards and are meant to supplement them in modeling, product design and testing.
{"title":"An equation for estimating the maximum allowable surface temperatures of electronic equipment","authors":"S. Roy","doi":"10.1109/STHERM.2011.5767178","DOIUrl":"https://doi.org/10.1109/STHERM.2011.5767178","url":null,"abstract":"Surface temperatures of electronic equipment and other machinery are an important design constraint since excessively high temperatures can be a safety hazard. Thus, government and industry standards have been established for maximum acceptable temperatures of hot surfaces that may be touched. Unfortunately, their recommendations are often limited to a few broad classes of materials, and appear to differ substantially from each other. They also do not adequately account for the unique properties of many advanced materials that have been developed recently. In order to address these issues, this paper presents explicit equations that can be used to set thermal safety criteria depending on the material and time of contact. They have been developed using data that are the basis for previous standards and are meant to supplement them in modeling, product design and testing.","PeriodicalId":128077,"journal":{"name":"2011 27th Annual IEEE Semiconductor Thermal Measurement and Management Symposium","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126868186","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 : 2011-03-20DOI: 10.1109/STHERM.2011.5767171
J. Ousten, Zoubir Khatir, Ludovic Menager
This paper presents new investigations on the aging of Thermal Interface Materials (TIM) subjected to thermal cycling conditions. The challenge was to design a specific and original set-up in order to not only undergo avionic temperature mission profile (-50°C/150°C) but also to perform standardized thermal characterization at always same conditions. Thermal conductivity is used as aging indicator. Several TIM materials (change phase, graphite and polymer based) have undergone more than 850 of such cycles. As a result, only the phase change material thermal interface has been affected with a 30% decrease of initial thermal resistance.
{"title":"Study of thermal interfaces aging for power electronics applications","authors":"J. Ousten, Zoubir Khatir, Ludovic Menager","doi":"10.1109/STHERM.2011.5767171","DOIUrl":"https://doi.org/10.1109/STHERM.2011.5767171","url":null,"abstract":"This paper presents new investigations on the aging of Thermal Interface Materials (TIM) subjected to thermal cycling conditions. The challenge was to design a specific and original set-up in order to not only undergo avionic temperature mission profile (-50°C/150°C) but also to perform standardized thermal characterization at always same conditions. Thermal conductivity is used as aging indicator. Several TIM materials (change phase, graphite and polymer based) have undergone more than 850 of such cycles. As a result, only the phase change material thermal interface has been affected with a 30% decrease of initial thermal resistance.","PeriodicalId":128077,"journal":{"name":"2011 27th Annual IEEE Semiconductor Thermal Measurement and Management Symposium","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131732173","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 : 2011-03-20DOI: 10.1109/STHERM.2011.5767216
D. Kendig, K. Yazawa, A. Shakouri
Thermoreflectance imaging is used to obtain 2D temperature maps of encapsulated LED arrays and elements with sub-micron spatial resolution. Typical LED encapsulation is opaque for infrared light, which prevents direct measurement of the semiconductor die with infrared cameras and thermocouples. A lock-in transient imaging technique with a megapixel silicon CCD is used to obtain the thermoreflectance and electroluminescence signals simultaneously. Transient thermal response in different locations of the die is characterized. Different thermal time constants are observed which correspond to various heat transfer mechanisms.
{"title":"Thermal imaging of encapsulated LEDs","authors":"D. Kendig, K. Yazawa, A. Shakouri","doi":"10.1109/STHERM.2011.5767216","DOIUrl":"https://doi.org/10.1109/STHERM.2011.5767216","url":null,"abstract":"Thermoreflectance imaging is used to obtain 2D temperature maps of encapsulated LED arrays and elements with sub-micron spatial resolution. Typical LED encapsulation is opaque for infrared light, which prevents direct measurement of the semiconductor die with infrared cameras and thermocouples. A lock-in transient imaging technique with a megapixel silicon CCD is used to obtain the thermoreflectance and electroluminescence signals simultaneously. Transient thermal response in different locations of the die is characterized. Different thermal time constants are observed which correspond to various heat transfer mechanisms.","PeriodicalId":128077,"journal":{"name":"2011 27th Annual IEEE Semiconductor Thermal Measurement and Management Symposium","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127605855","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 : 2011-03-20DOI: 10.1109/STHERM.2011.5767199
R. Bonner, T. Desai, F. Gao, Xudong Tang, T. Palacios, Seunghan Shin, M. Kaviany
In many communications applications semiconductor devices operate in a pulsed mode, where rapid temperature transients are continuously experienced within the die. We proposed a novel junction-level cooling technology where a metallic phase change material (PCM) was embedded in close proximity to the active transistor channels without interfering with the device's electrical response. Here we present multiscale simulations that were performed to determine the thermal performance improvement and electrical performance impact under pulsed operating conditions. The modeling effort was focused on Gallium Nitride (GaN) on Silicon (Si) chips with Indium (In) as the PCM. To accurately capture the microscale transient melting process, a hierarchical multiscale model was developed that includes linking of atomistic-level molecular dynamics simulations and macroscale finite element analysis simulations. Macroscale physics, including the melting process, were captured with a transient two-dimensional finite element analysis (FEA) model. The FEA model also includes interfacial and contact resistances between the semiconductor materials and PCM. Non-equilibrium Molecular Dynamic (MD) simulations were performed to estimate the value of the interfacial resistances between the Si substrate and the In PCM, which included a new interatomic potential between In and Si that was developed from experimental scattering results available in the literature. The thermal modeling results indicate 26% more heat can be dissipated through the PCM enhanced transistor while maintain a safe operating temperature. A separate electrical modeling effort showed that the metallic PCM layer did not create appreciable parasitic capacitances as long as the PCM was farther than 1μm from the active channel. The lower, more constant temperatures achieved by this technology can help improve the reliability and performance of future communication devices.
{"title":"Die level thermal storage for improved cooling of pulsed devices","authors":"R. Bonner, T. Desai, F. Gao, Xudong Tang, T. Palacios, Seunghan Shin, M. Kaviany","doi":"10.1109/STHERM.2011.5767199","DOIUrl":"https://doi.org/10.1109/STHERM.2011.5767199","url":null,"abstract":"In many communications applications semiconductor devices operate in a pulsed mode, where rapid temperature transients are continuously experienced within the die. We proposed a novel junction-level cooling technology where a metallic phase change material (PCM) was embedded in close proximity to the active transistor channels without interfering with the device's electrical response. Here we present multiscale simulations that were performed to determine the thermal performance improvement and electrical performance impact under pulsed operating conditions. The modeling effort was focused on Gallium Nitride (GaN) on Silicon (Si) chips with Indium (In) as the PCM. To accurately capture the microscale transient melting process, a hierarchical multiscale model was developed that includes linking of atomistic-level molecular dynamics simulations and macroscale finite element analysis simulations. Macroscale physics, including the melting process, were captured with a transient two-dimensional finite element analysis (FEA) model. The FEA model also includes interfacial and contact resistances between the semiconductor materials and PCM. Non-equilibrium Molecular Dynamic (MD) simulations were performed to estimate the value of the interfacial resistances between the Si substrate and the In PCM, which included a new interatomic potential between In and Si that was developed from experimental scattering results available in the literature. The thermal modeling results indicate 26% more heat can be dissipated through the PCM enhanced transistor while maintain a safe operating temperature. A separate electrical modeling effort showed that the metallic PCM layer did not create appreciable parasitic capacitances as long as the PCM was farther than 1μm from the active channel. The lower, more constant temperatures achieved by this technology can help improve the reliability and performance of future communication devices.","PeriodicalId":128077,"journal":{"name":"2011 27th Annual IEEE Semiconductor Thermal Measurement and Management Symposium","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130278931","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 : 2011-03-20DOI: 10.1109/STHERM.2011.5767186
N. Ahuja, C. Rego, S. Ahuja, Matt Warner, Akhil Docca
Advances in server technology have resulted in the cost of acquiring server equipment trending down, while economies of scale in data centers have significantly reduced the cost of labor. This leaves the cost of the energy as the next target for optimization. Energy costs are driven by operating the IT equipment, the switchgear that provides uninterrupted power to the equipment, and in cooling the IT equipment. In a typical datacenter, almost 40% of the total power consumption is spent on cooling. In addition, cooling effectiveness is a first order factor in determining the lifespan of the data center. One of the emerging trends in the industry is to move datacenter operations to higher ambient temperatures with some Operators wanting to set supply air temperatures as high as 40°C while improving cooling system efficiency. This study will show that with optimized cooling control one could reduce the total cost of ownership at the datacenter level by optimizing the datacenter cooling budget while ensuring no performance loss at increased ambient temperature conditions. This paper describes a platform-assisted thermal management approach that uses new sensors providing server airflow and server outlet temperature to improve control of the data centers cooling solution. This data is also used as input to a computational fluid dynamics (CFD) model for accurate predictive analysis and optimization of future change scenarios, thus increasing the data center efficiency and reducing power consumption. A key component of the study will be the use of computational fluid dynamics CFD analysis for optimizing the data center cooling system.
{"title":"Data center efficiency with higher ambient temperatures and optimized cooling control","authors":"N. Ahuja, C. Rego, S. Ahuja, Matt Warner, Akhil Docca","doi":"10.1109/STHERM.2011.5767186","DOIUrl":"https://doi.org/10.1109/STHERM.2011.5767186","url":null,"abstract":"Advances in server technology have resulted in the cost of acquiring server equipment trending down, while economies of scale in data centers have significantly reduced the cost of labor. This leaves the cost of the energy as the next target for optimization. Energy costs are driven by operating the IT equipment, the switchgear that provides uninterrupted power to the equipment, and in cooling the IT equipment. In a typical datacenter, almost 40% of the total power consumption is spent on cooling. In addition, cooling effectiveness is a first order factor in determining the lifespan of the data center. One of the emerging trends in the industry is to move datacenter operations to higher ambient temperatures with some Operators wanting to set supply air temperatures as high as 40°C while improving cooling system efficiency. This study will show that with optimized cooling control one could reduce the total cost of ownership at the datacenter level by optimizing the datacenter cooling budget while ensuring no performance loss at increased ambient temperature conditions. This paper describes a platform-assisted thermal management approach that uses new sensors providing server airflow and server outlet temperature to improve control of the data centers cooling solution. This data is also used as input to a computational fluid dynamics (CFD) model for accurate predictive analysis and optimization of future change scenarios, thus increasing the data center efficiency and reducing power consumption. A key component of the study will be the use of computational fluid dynamics CFD analysis for optimizing the data center cooling system.","PeriodicalId":128077,"journal":{"name":"2011 27th Annual IEEE Semiconductor Thermal Measurement and Management Symposium","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114659932","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 : 2011-03-20DOI: 10.1109/STHERM.2011.5767212
Q. He, Shane Smith, G. Xiong
Thermocouples have been widely used in electronics thermal measurement. Although there are many ways to attach a thermocouple to an electronic component, epoxy especially rapid bonding epoxy material has been the favorable choice due to its convenience of use. However there remains lack of comprehensive understanding of the accuracy of the measurement results and what should be done to minimize the error introduced by the thermocouple and epoxy. In this study two parameters were introduced to describe the causes of error in thermocouple measurement using epoxy. A total of eight variables that may occur in the epoxy attachment were investigated based upon a numerical experiment setup, which consisted of a detailed replication of an actual thermocouple and a typical electronic component thermal model. Different combinations along with their measurement errors were provided for side by side comparison. The measurement error could be as high as 25 ∼ 40% in some cases and even for the best case scenario it was still above 4% in this study. The quick-dry epoxy is practically good enough for most electronic thermal measurements, but attentions must be paid to control several variables that can be commonly neglected in order to assure results are acceptable. The findings from this study can be applied by thermal engineers to achieve the best practice during thermal design and measurement.
{"title":"Thermocouple attachment using epoxy in electronic system thermal measurements — A numerical experiment","authors":"Q. He, Shane Smith, G. Xiong","doi":"10.1109/STHERM.2011.5767212","DOIUrl":"https://doi.org/10.1109/STHERM.2011.5767212","url":null,"abstract":"Thermocouples have been widely used in electronics thermal measurement. Although there are many ways to attach a thermocouple to an electronic component, epoxy especially rapid bonding epoxy material has been the favorable choice due to its convenience of use. However there remains lack of comprehensive understanding of the accuracy of the measurement results and what should be done to minimize the error introduced by the thermocouple and epoxy. In this study two parameters were introduced to describe the causes of error in thermocouple measurement using epoxy. A total of eight variables that may occur in the epoxy attachment were investigated based upon a numerical experiment setup, which consisted of a detailed replication of an actual thermocouple and a typical electronic component thermal model. Different combinations along with their measurement errors were provided for side by side comparison. The measurement error could be as high as 25 ∼ 40% in some cases and even for the best case scenario it was still above 4% in this study. The quick-dry epoxy is practically good enough for most electronic thermal measurements, but attentions must be paid to control several variables that can be commonly neglected in order to assure results are acceptable. The findings from this study can be applied by thermal engineers to achieve the best practice during thermal design and measurement.","PeriodicalId":128077,"journal":{"name":"2011 27th Annual IEEE Semiconductor Thermal Measurement and Management Symposium","volume":"357 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133069879","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 : 2011-03-20DOI: 10.1109/STHERM.2011.5767214
A. Poppe, B. Siegal, G. Farkas
In this paper we aim at highlighting different aspects of thermal testing of AC LEDs, especially of retrofit LED lamps which are directly driven from the AC mains supply. The main focus is the concept of thermal impedance applied for AC driven LEDs and the AC heating power. The paper gives an overview of the different representations of the thermal impedance then provides estimates of the AC power of LEDs for one of the extreme cases (ideal AC voltage generator driven situation) together with spectra of harmonics of the AC heating power. Definitions and test procedures for the AC thermal impedance of LEDs are suggested along with test environments for AC LED modules as well as for complete retrofit LED lamps.
{"title":"Issues of thermal testing of AC LEDs","authors":"A. Poppe, B. Siegal, G. Farkas","doi":"10.1109/STHERM.2011.5767214","DOIUrl":"https://doi.org/10.1109/STHERM.2011.5767214","url":null,"abstract":"In this paper we aim at highlighting different aspects of thermal testing of AC LEDs, especially of retrofit LED lamps which are directly driven from the AC mains supply. The main focus is the concept of thermal impedance applied for AC driven LEDs and the AC heating power. The paper gives an overview of the different representations of the thermal impedance then provides estimates of the AC power of LEDs for one of the extreme cases (ideal AC voltage generator driven situation) together with spectra of harmonics of the AC heating power. Definitions and test procedures for the AC thermal impedance of LEDs are suggested along with test environments for AC LED modules as well as for complete retrofit LED lamps.","PeriodicalId":128077,"journal":{"name":"2011 27th Annual IEEE Semiconductor Thermal Measurement and Management Symposium","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116148245","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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