Pub Date : 2017-12-25DOI: 10.1109/THERMINIC.2017.8233827
K. Nwanoro, Hua Lu, C. Yin, C. Bailey
Aluminium wires are widely used in power electronics modules to connect power semiconductor devices and other parts of the module electrically. Recently, other interconnect techniques have been proposed such as ribbon bond to improve the reliability, performance and reduce costs of power modules. The reliability of ribbon bond technique for an IGBT power module under power cycling is compared with that of conventional wire bond in this study using electro-thermal nonlinear Finite Element Analysis. The results showed that a single ribbon of 2000μm × 200μm will replace three wire bonds of 400μm in diameter to achieve a similar module temperature distribution under same power load. Using the equivalent plastic strain increment per cycle, it is seen that the ribbon bond is more reliable than the wire bonds. The impact of neglecting joule heat in the wire/ribbon bonds during power cycling simulation has also been investigated.
{"title":"Computer simulation of the reliability of wire bonds and ribbon bonds in power electronics modules","authors":"K. Nwanoro, Hua Lu, C. Yin, C. Bailey","doi":"10.1109/THERMINIC.2017.8233827","DOIUrl":"https://doi.org/10.1109/THERMINIC.2017.8233827","url":null,"abstract":"Aluminium wires are widely used in power electronics modules to connect power semiconductor devices and other parts of the module electrically. Recently, other interconnect techniques have been proposed such as ribbon bond to improve the reliability, performance and reduce costs of power modules. The reliability of ribbon bond technique for an IGBT power module under power cycling is compared with that of conventional wire bond in this study using electro-thermal nonlinear Finite Element Analysis. The results showed that a single ribbon of 2000μm × 200μm will replace three wire bonds of 400μm in diameter to achieve a similar module temperature distribution under same power load. Using the equivalent plastic strain increment per cycle, it is seen that the ribbon bond is more reliable than the wire bonds. The impact of neglecting joule heat in the wire/ribbon bonds during power cycling simulation has also been investigated.","PeriodicalId":317847,"journal":{"name":"2017 23rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)","volume":"11653 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117248656","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 : 2017-12-25DOI: 10.1109/THERMINIC.2017.8233839
H. J. Lin, A. Assy, E. Lemaire, D. Briand, L. Billot, P. Gredin, M. Mortier, Z. Chen, L. Aigouy
We describe a scanning thermal microscope that uses a fluorescent nanocrystal as a temperature probe. The nanocrystal is made of an inorganic fluoride material doped with erbium ions. The temperature is determined by measuring the fluorescence intensity ratio between two adjacent fluorescence lines. We first visualized the heating of a Cr stripe, and observed two different heat transfer channels, by direct contact between the tip and the device and by conduction through the air gap. We then measured the temperature map of a Joule heated submicron wide Pt wire and observed that the temperature elevation is uniform all along the wire. The measured images are obtained with a submicron lateral resolution and demonstrate the good reliability of the technique for characterizing the thermal properties of nanoscale devices and structures.
{"title":"Nanoscale thermal imaging of active devices by fluorescent SThM","authors":"H. J. Lin, A. Assy, E. Lemaire, D. Briand, L. Billot, P. Gredin, M. Mortier, Z. Chen, L. Aigouy","doi":"10.1109/THERMINIC.2017.8233839","DOIUrl":"https://doi.org/10.1109/THERMINIC.2017.8233839","url":null,"abstract":"We describe a scanning thermal microscope that uses a fluorescent nanocrystal as a temperature probe. The nanocrystal is made of an inorganic fluoride material doped with erbium ions. The temperature is determined by measuring the fluorescence intensity ratio between two adjacent fluorescence lines. We first visualized the heating of a Cr stripe, and observed two different heat transfer channels, by direct contact between the tip and the device and by conduction through the air gap. We then measured the temperature map of a Joule heated submicron wide Pt wire and observed that the temperature elevation is uniform all along the wire. The measured images are obtained with a submicron lateral resolution and demonstrate the good reliability of the technique for characterizing the thermal properties of nanoscale devices and structures.","PeriodicalId":317847,"journal":{"name":"2017 23rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121997954","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 : 2017-12-21DOI: 10.1109/THERMINIC.2017.8233802
R. Chavez, D. Vakulov, S. Gazibegović, D. Car, D. Kendig, A. Tay, A. Shakouri, E. Bakkers
Increasing energy demand and depleting fossil fuels make it imperative to shift to more efficient energy sources. Thermoelectric materials can convert waste heat into electrical energy by means of the Thermopower or Seebeck effect. Nanowires are promising candidates to increase the efficiency of thermo-electric conversion because their low dimensionality is predicted to increase the Seebeck effect due to confinement of charge carriers and decrease thermal conductivity due to boundary scattering of phonons. The Seebeck effect is characterized by the Seebeck coefficient which describes the output voltage per degree Kelvin in a thermoelectric material. Hence, in order to obtain the Seebeck coefficient, it is crucial to accurately measure the temperature difference along the axial direction of the nanowire which has a length of a few micrometers, at the locations where voltage measurements are performed under a temperature gradient. Here we demonstrate an application of thermoreflectance to measure the temperature difference along the nanowire allowing bi-directional measurements of Seebeck coefficient.
{"title":"Thermopower characterization of InSb nanowires using thermoreflectance","authors":"R. Chavez, D. Vakulov, S. Gazibegović, D. Car, D. Kendig, A. Tay, A. Shakouri, E. Bakkers","doi":"10.1109/THERMINIC.2017.8233802","DOIUrl":"https://doi.org/10.1109/THERMINIC.2017.8233802","url":null,"abstract":"Increasing energy demand and depleting fossil fuels make it imperative to shift to more efficient energy sources. Thermoelectric materials can convert waste heat into electrical energy by means of the Thermopower or Seebeck effect. Nanowires are promising candidates to increase the efficiency of thermo-electric conversion because their low dimensionality is predicted to increase the Seebeck effect due to confinement of charge carriers and decrease thermal conductivity due to boundary scattering of phonons. The Seebeck effect is characterized by the Seebeck coefficient which describes the output voltage per degree Kelvin in a thermoelectric material. Hence, in order to obtain the Seebeck coefficient, it is crucial to accurately measure the temperature difference along the axial direction of the nanowire which has a length of a few micrometers, at the locations where voltage measurements are performed under a temperature gradient. Here we demonstrate an application of thermoreflectance to measure the temperature difference along the nanowire allowing bi-directional measurements of Seebeck coefficient.","PeriodicalId":317847,"journal":{"name":"2017 23rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114536180","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 : 2017-12-21DOI: 10.1109/THERMINIC.2017.8233789
G. Groeneveld, H. V. van Gerner, W. Wits
The thermal performance of a flat-plate closed-loop pulsating heat pipe (PHP) is experimentally obtained. The PHP is manufactured by means of CNC-milling and vacuum brazing of a stainless steel 316L bottom plate and lid. Each channel of the PHP has a 2∗2 mm2 square cross section. In total 12 channels (6 turns) fit in the 50∗200 mm2 effective area of the PHP. During the experimental investigation, the power input is increased from 20W to 100W through a 50∗50 mm2 evaporator section, while cooling is performed through a 50∗50 mm2 condenser section with the use of a Thermo-Electric Cooler (TEC). The PHP is charged with methanol with 40% filling ratio. The thermal resistance is obtained for different inclination angles. It is observed that the 6-turn device operates well in vertical orientation. It however does not operate horizontally. Moreover, experiments have shown that the operating orientation is between 15–30°. The overall thermal resistance was determined at 0.48 K/W for a 100 Wpower input in the vertical evaporator-down orientation.
{"title":"An experimental study towards the practical application of closed-loop flat-plate pulsating heat pipes","authors":"G. Groeneveld, H. V. van Gerner, W. Wits","doi":"10.1109/THERMINIC.2017.8233789","DOIUrl":"https://doi.org/10.1109/THERMINIC.2017.8233789","url":null,"abstract":"The thermal performance of a flat-plate closed-loop pulsating heat pipe (PHP) is experimentally obtained. The PHP is manufactured by means of CNC-milling and vacuum brazing of a stainless steel 316L bottom plate and lid. Each channel of the PHP has a 2∗2 mm2 square cross section. In total 12 channels (6 turns) fit in the 50∗200 mm2 effective area of the PHP. During the experimental investigation, the power input is increased from 20W to 100W through a 50∗50 mm2 evaporator section, while cooling is performed through a 50∗50 mm2 condenser section with the use of a Thermo-Electric Cooler (TEC). The PHP is charged with methanol with 40% filling ratio. The thermal resistance is obtained for different inclination angles. It is observed that the 6-turn device operates well in vertical orientation. It however does not operate horizontally. Moreover, experiments have shown that the operating orientation is between 15–30°. The overall thermal resistance was determined at 0.48 K/W for a 100 Wpower input in the vertical evaporator-down orientation.","PeriodicalId":317847,"journal":{"name":"2017 23rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127817860","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 : 2017-12-21DOI: 10.1109/THERMINIC.2017.8233797
Josephine Sari, T. Mérelle, A. Di Bucchianico, D. Breton
The main objective of the Delphi4LED project (funded by the Ecsel European joint undertaking) is to develop a standardized method to create multidomain LED based design and simulation flow for the solid-state lighting industry. Tools and standards will be developed at various levels to enable design and manufacturing of more reliable and cost effective LED based lighting solutions which can be brought to the market much faster than today. Beyond the modelling of thermal, electrical and optical behaviour of LEDs, modelling ofprocess variability has been identified as an important feature that should be implemented in the final tool. Sources of process variability during LED manufacturing, measurements, as well as their impact on colorimetry are currently investigated in the Solid State Lighting industry. In the context of Delphi4LED, some preliminary electrical and optical measurements have been conducted on blue pump white Chip Scale Package (CSP) LEDs and the measurement data have been analysed statistically.
{"title":"Delphi4LED: LED measurements and variability analysis","authors":"Josephine Sari, T. Mérelle, A. Di Bucchianico, D. Breton","doi":"10.1109/THERMINIC.2017.8233797","DOIUrl":"https://doi.org/10.1109/THERMINIC.2017.8233797","url":null,"abstract":"The main objective of the Delphi4LED project (funded by the Ecsel European joint undertaking) is to develop a standardized method to create multidomain LED based design and simulation flow for the solid-state lighting industry. Tools and standards will be developed at various levels to enable design and manufacturing of more reliable and cost effective LED based lighting solutions which can be brought to the market much faster than today. Beyond the modelling of thermal, electrical and optical behaviour of LEDs, modelling ofprocess variability has been identified as an important feature that should be implemented in the final tool. Sources of process variability during LED manufacturing, measurements, as well as their impact on colorimetry are currently investigated in the Solid State Lighting industry. In the context of Delphi4LED, some preliminary electrical and optical measurements have been conducted on blue pump white Chip Scale Package (CSP) LEDs and the measurement data have been analysed statistically.","PeriodicalId":317847,"journal":{"name":"2017 23rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)","volume":"95 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124618005","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 : 2017-12-21DOI: 10.1109/THERMINIC.2017.8233841
D. Jafari, W. Wits, B. Geurts
Specific properties of porous media such as thermal conductivity and wicking of liquid into the porous structure are of great importance to many applications. Typically, such porous structures are found in two-phase devices, such as heat pipes (HPs). In this study, we have experimentally analysed the effective thermal conductivity and the wicking of different liquids into a stainless steel 316L porous structure fabricated through selective laser melting (SLM) technology. The sample was rectangular shaped with a porosity of 46.5% and outer dimensions of 20×40×1 mm3. An experimental apparatus and related procedures for the determination of the effective thermal conductivity of the porous structure saturated with distilled water and Ethylene glycol are discussed. The experimentally measured values of effective thermal conductivity are compared with correlations available in the literature. The standard Washburn wicking model is taken into account for the analysis. We describe the application of the Washburn equation to measure the contact angle of a printed porous sample with three test liquids; n-Hexane, water and Ethylene glycol are used to measure contact angles. The experimental results verify that SLM technology can be used to fabricate porous structures for HP technology. The results show an effective thermal conductivity in the range of 1.8–6.0 W/mK for different working fluids.
{"title":"An investigation of porous structure characteristics of heat pipes made by additive manufacturing","authors":"D. Jafari, W. Wits, B. Geurts","doi":"10.1109/THERMINIC.2017.8233841","DOIUrl":"https://doi.org/10.1109/THERMINIC.2017.8233841","url":null,"abstract":"Specific properties of porous media such as thermal conductivity and wicking of liquid into the porous structure are of great importance to many applications. Typically, such porous structures are found in two-phase devices, such as heat pipes (HPs). In this study, we have experimentally analysed the effective thermal conductivity and the wicking of different liquids into a stainless steel 316L porous structure fabricated through selective laser melting (SLM) technology. The sample was rectangular shaped with a porosity of 46.5% and outer dimensions of 20×40×1 mm3. An experimental apparatus and related procedures for the determination of the effective thermal conductivity of the porous structure saturated with distilled water and Ethylene glycol are discussed. The experimentally measured values of effective thermal conductivity are compared with correlations available in the literature. The standard Washburn wicking model is taken into account for the analysis. We describe the application of the Washburn equation to measure the contact angle of a printed porous sample with three test liquids; n-Hexane, water and Ethylene glycol are used to measure contact angles. The experimental results verify that SLM technology can be used to fabricate porous structures for HP technology. The results show an effective thermal conductivity in the range of 1.8–6.0 W/mK for different working fluids.","PeriodicalId":317847,"journal":{"name":"2017 23rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133569756","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 : 2017-09-01DOI: 10.1109/THERMINIC.2017.8233784
Younis Osama Abdelsalam, S. Alimohammadi, Quentin Pelletier, T. Persoons
Traditional plate-fin heatsinks are used in abundance in data centres and telecommunication systems for electronic integrated circuit and component cooling, without much regard for geometric shape optimisation. Any improvements in the effectiveness of the heatsinks impacts the energy consumed by the information communication and technology (ICT) centres and promote a more sustainable use of raw materials. This paper investigates the optimisation of plate-fin heatsinks in a forced cross-flow using a multi-objective genetic algorithm (MOGA) combined with CFD simulations, by varying the fin angles. The main objective is to improve the heat dissipation rate by modifying geometric parameters (i.e., number, arrangement, and orientation offins). For a generic heat sink test case, the optimised performance is examined in terms of thermal resistance, turbulence intensity, pumping power, coefficient of performance and j-factors. An increase in the effectiveness of heat dissipation is reported ranging from 11.2% to 18.1%.
{"title":"A multi-objective genetic algorithm optimisation of plate-fin heatsinks","authors":"Younis Osama Abdelsalam, S. Alimohammadi, Quentin Pelletier, T. Persoons","doi":"10.1109/THERMINIC.2017.8233784","DOIUrl":"https://doi.org/10.1109/THERMINIC.2017.8233784","url":null,"abstract":"Traditional plate-fin heatsinks are used in abundance in data centres and telecommunication systems for electronic integrated circuit and component cooling, without much regard for geometric shape optimisation. Any improvements in the effectiveness of the heatsinks impacts the energy consumed by the information communication and technology (ICT) centres and promote a more sustainable use of raw materials. This paper investigates the optimisation of plate-fin heatsinks in a forced cross-flow using a multi-objective genetic algorithm (MOGA) combined with CFD simulations, by varying the fin angles. The main objective is to improve the heat dissipation rate by modifying geometric parameters (i.e., number, arrangement, and orientation offins). For a generic heat sink test case, the optimised performance is examined in terms of thermal resistance, turbulence intensity, pumping power, coefficient of performance and j-factors. An increase in the effectiveness of heat dissipation is reported ranging from 11.2% to 18.1%.","PeriodicalId":317847,"journal":{"name":"2017 23rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123056096","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 : 2017-09-01DOI: 10.1109/THERMINIC.2017.8233844
M. Shahjalal, H. Lu, C. Bailey
In this paper it is shown how Finite Element Analysis can be exploited for the calibration of detailed compact thermal models of the components in the power converter topology. Parameters extracted from Finite Element transient thermal response are used to build the thermal network in conjunction with an electrical model of the converter for the prediction ofpower losses in the components. Results show that use of the thermal model parameters that are derived from Finite Element Analysis method can predict the temperature accurately and can also take into account of the thermal interaction between components, an issue that has not been fully investigated in this area of research.
{"title":"An investigation of component interaction and analysis of its impact on electro-thermal behaviour in a power dense boost converter topology","authors":"M. Shahjalal, H. Lu, C. Bailey","doi":"10.1109/THERMINIC.2017.8233844","DOIUrl":"https://doi.org/10.1109/THERMINIC.2017.8233844","url":null,"abstract":"In this paper it is shown how Finite Element Analysis can be exploited for the calibration of detailed compact thermal models of the components in the power converter topology. Parameters extracted from Finite Element transient thermal response are used to build the thermal network in conjunction with an electrical model of the converter for the prediction ofpower losses in the components. Results show that use of the thermal model parameters that are derived from Finite Element Analysis method can predict the temperature accurately and can also take into account of the thermal interaction between components, an issue that has not been fully investigated in this area of research.","PeriodicalId":317847,"journal":{"name":"2017 23rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125154533","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 : 2017-09-01DOI: 10.1109/THERMINIC.2017.8233842
L. Mitterhuber, S. Defregger, J. Magnien, J. Rose, F. Schrank, Stefan Hörth, L. Goullon, M. Hutter, E. Kraker
The solid lighting industry comply with costumer's requirements of high light output and a higher grade of functionality, especially in the automotive sector. The integration of multiple LED-chips on one illuminant has the advantage of weight and size reduction. However, multiple LED-chips lead to increased power density; to get rid of their produced heat, an energy strategy is necessary. The key term is Thermal Management, to understand the thermal behavior of a LED lighting system. In this paper, the investigation of the thermal interdependencies of a 4-chip-matrix was presented. The thermal characterization was done by thermal transient measurements of each chip and their structure functions, followed by the study of its thermal resistance (Rth) matrix. The Rth-matrix represented the thermal properties of each LED-chip and its interdependency. As supplement of the thermal characterization, thermal simulations were carried out. Moreover, the Rth-matrix was used to analyze the LED-matrix in terms of their temperature dependency. The heat path investigation via Rth-matrix showed different behaviors of the 4-chip-matrix by using different heat sink temperatures. The method was used as an evaluation tool for thermal management of LED-matrix systems.
{"title":"Study on the temperature-dependent thermal resistance matrix of a multi-chip LED-matrix","authors":"L. Mitterhuber, S. Defregger, J. Magnien, J. Rose, F. Schrank, Stefan Hörth, L. Goullon, M. Hutter, E. Kraker","doi":"10.1109/THERMINIC.2017.8233842","DOIUrl":"https://doi.org/10.1109/THERMINIC.2017.8233842","url":null,"abstract":"The solid lighting industry comply with costumer's requirements of high light output and a higher grade of functionality, especially in the automotive sector. The integration of multiple LED-chips on one illuminant has the advantage of weight and size reduction. However, multiple LED-chips lead to increased power density; to get rid of their produced heat, an energy strategy is necessary. The key term is Thermal Management, to understand the thermal behavior of a LED lighting system. In this paper, the investigation of the thermal interdependencies of a 4-chip-matrix was presented. The thermal characterization was done by thermal transient measurements of each chip and their structure functions, followed by the study of its thermal resistance (Rth) matrix. The Rth-matrix represented the thermal properties of each LED-chip and its interdependency. As supplement of the thermal characterization, thermal simulations were carried out. Moreover, the Rth-matrix was used to analyze the LED-matrix in terms of their temperature dependency. The heat path investigation via Rth-matrix showed different behaviors of the 4-chip-matrix by using different heat sink temperatures. The method was used as an evaluation tool for thermal management of LED-matrix systems.","PeriodicalId":317847,"journal":{"name":"2017 23rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115353502","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 : 2017-09-01DOI: 10.1109/THERMINIC.2017.8233821
L. Pohl, Z. Kohári, A. Poppe
Organic LEDs can be used not only in displays but also in intelligent light sources. Unlike inorganic LEDs, OLEDs do not function as point-like but as surface light sources since manufacturing of large area light sources is more feasible with OLED technologies. Despite their lower luminous efficacy this makes OLEDs still an attractive option especially in high end indoor applications, The major issue in such applications is the homegenity of the luminance of the large OLED panels. In natural convection environment the temperature difference in the same device can reach 20–30°C which can result in up to 30–40% difference in current density and thus in the luminance. CFD simulation is the obvious way to handle this problem but integration of a CFD solver in an OLED simulator may be difficult and the solution times are high. This paper presents the application of three natural convection models for vertical plates in an electro-thermal field solver based OLED simulator as thermal boundary condition. Simulation results of a free-standing 50∗50 mm2 active surface OLED, surrounded by still air, are compared with measurement results.
{"title":"Fast electro-thermal simulation of large area OLEDs in natural convection environment","authors":"L. Pohl, Z. Kohári, A. Poppe","doi":"10.1109/THERMINIC.2017.8233821","DOIUrl":"https://doi.org/10.1109/THERMINIC.2017.8233821","url":null,"abstract":"Organic LEDs can be used not only in displays but also in intelligent light sources. Unlike inorganic LEDs, OLEDs do not function as point-like but as surface light sources since manufacturing of large area light sources is more feasible with OLED technologies. Despite their lower luminous efficacy this makes OLEDs still an attractive option especially in high end indoor applications, The major issue in such applications is the homegenity of the luminance of the large OLED panels. In natural convection environment the temperature difference in the same device can reach 20–30°C which can result in up to 30–40% difference in current density and thus in the luminance. CFD simulation is the obvious way to handle this problem but integration of a CFD solver in an OLED simulator may be difficult and the solution times are high. This paper presents the application of three natural convection models for vertical plates in an electro-thermal field solver based OLED simulator as thermal boundary condition. Simulation results of a free-standing 50∗50 mm2 active surface OLED, surrounded by still air, are compared with measurement results.","PeriodicalId":317847,"journal":{"name":"2017 23rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116569441","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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