Pub Date : 1994-02-01DOI: 10.1109/STHERM.1994.288988
F. McMaye
Cooling chip on board (COB) using TAB technology is sometimes tricky. Thermal vias with cooling copper planes are often used. This design may not be adequate when cooling high powered chips, therefore alternative designs will need to be investigated. In doing so it is necessary that performances be properly predicted especially when operating conditions are expected to be close to design limits. This study evaluates three cooling designs and three analytical methods of predicting the thermal performances of each design. The three designs are: 1. thermal vias connected to a cooling ground plane; 2. thermal vias connected to a cooling ground plane and a heatsink attached to the back side of the vias; and 3. a copper slug with a heatsink attached to the back side. The three methods of prediction are: 1. a one dimensional analysis; 2. a numerical analysis using FLOTHERM thermal and fluid analysis software; and 3. experimental analysis.<>
{"title":"Evaluation of alternative cooling techniques for TAB packages","authors":"F. McMaye","doi":"10.1109/STHERM.1994.288988","DOIUrl":"https://doi.org/10.1109/STHERM.1994.288988","url":null,"abstract":"Cooling chip on board (COB) using TAB technology is sometimes tricky. Thermal vias with cooling copper planes are often used. This design may not be adequate when cooling high powered chips, therefore alternative designs will need to be investigated. In doing so it is necessary that performances be properly predicted especially when operating conditions are expected to be close to design limits. This study evaluates three cooling designs and three analytical methods of predicting the thermal performances of each design. The three designs are: 1. thermal vias connected to a cooling ground plane; 2. thermal vias connected to a cooling ground plane and a heatsink attached to the back side of the vias; and 3. a copper slug with a heatsink attached to the back side. The three methods of prediction are: 1. a one dimensional analysis; 2. a numerical analysis using FLOTHERM thermal and fluid analysis software; and 3. experimental analysis.<<ETX>>","PeriodicalId":107140,"journal":{"name":"Proceedings of 1994 IEEE/CHMT 10th Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121973763","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 : 1994-02-01DOI: 10.1109/STHERM.1994.288985
J. Wilson, K. Decker
Detailed thermal modeling of a gallium arsenide (GaAs) power amplifier monolithic microwave integrated circuit (MMIC) yields operating channel temperatures that are used to correlate reliability life test results. The model includes temperature dependent material properties, surface metallization layers, and volumetric heat generation in the depletion region directly beneath the channels. Also included are chip-to-substrate and substrate-to-housing interface thermal resistances. Model predictions which include the top surface metallization layers indicate the hottest channel is not always the center channel as simpler methods would predict but in a location with partially unplated metallization. The finite difference meshing scheme is first verified by comparison to a simplified geometry that may be characterized by an analytical solution program. After the channel temperatures are established over a range of temperatures, model verification is accomplished by infrared (IR) imaging. The necessity of coating the GaAs MMIC with a uniform emissivity material to obtain accurate IR imaging results is demonstrated. A final confirmation of the techniques is by photographs taken during failure analysis indicating device failures occurred at the location predicted by the thermal model.<>
{"title":"GaAs MMIC thermal modeling for channel temperatures in accelerated life test fixtures and microwave modules","authors":"J. Wilson, K. Decker","doi":"10.1109/STHERM.1994.288985","DOIUrl":"https://doi.org/10.1109/STHERM.1994.288985","url":null,"abstract":"Detailed thermal modeling of a gallium arsenide (GaAs) power amplifier monolithic microwave integrated circuit (MMIC) yields operating channel temperatures that are used to correlate reliability life test results. The model includes temperature dependent material properties, surface metallization layers, and volumetric heat generation in the depletion region directly beneath the channels. Also included are chip-to-substrate and substrate-to-housing interface thermal resistances. Model predictions which include the top surface metallization layers indicate the hottest channel is not always the center channel as simpler methods would predict but in a location with partially unplated metallization. The finite difference meshing scheme is first verified by comparison to a simplified geometry that may be characterized by an analytical solution program. After the channel temperatures are established over a range of temperatures, model verification is accomplished by infrared (IR) imaging. The necessity of coating the GaAs MMIC with a uniform emissivity material to obtain accurate IR imaging results is demonstrated. A final confirmation of the techniques is by photographs taken during failure analysis indicating device failures occurred at the location predicted by the thermal model.<<ETX>>","PeriodicalId":107140,"journal":{"name":"Proceedings of 1994 IEEE/CHMT 10th Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115815281","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 : 1994-02-01DOI: 10.1109/STHERM.1994.288986
H. Kristiansen, T. Fallet, A. Bjorneklett
The cooling of a high power motor controller has been studied for more than two years. The total power dissipation in the controller is estimated to be in the order of 20 kW. We chose to use pool boiling inside a enclosed volume for thermal management. This paper is concerned with the evaporation part of the cooling system. The primary concern has been the cooling of the "hockey puk" GTO's having an expected power dissipation in the order of 1 kW. To increase the effective area for evaporation heat transfer, the components have been clamped between cooling "blocks". We found however that a notable part of the heat was transferred directly from the GTO capsule itself into the liquid. This was dependent on the degree of liquid subcooling and the total pressure. The thermal resistance in the cooling blocks contributed significantly to the total temperature loss. The temperature gradients depended heavily upon the local heat transfer from cooling block to liquid. FEM simulations have been used to model the temperature distribution in the cooling blocks as a function of heat transfer coefficients.<>
{"title":"A study on the evaporation heat transfer in the cooling of high power electronics","authors":"H. Kristiansen, T. Fallet, A. Bjorneklett","doi":"10.1109/STHERM.1994.288986","DOIUrl":"https://doi.org/10.1109/STHERM.1994.288986","url":null,"abstract":"The cooling of a high power motor controller has been studied for more than two years. The total power dissipation in the controller is estimated to be in the order of 20 kW. We chose to use pool boiling inside a enclosed volume for thermal management. This paper is concerned with the evaporation part of the cooling system. The primary concern has been the cooling of the \"hockey puk\" GTO's having an expected power dissipation in the order of 1 kW. To increase the effective area for evaporation heat transfer, the components have been clamped between cooling \"blocks\". We found however that a notable part of the heat was transferred directly from the GTO capsule itself into the liquid. This was dependent on the degree of liquid subcooling and the total pressure. The thermal resistance in the cooling blocks contributed significantly to the total temperature loss. The temperature gradients depended heavily upon the local heat transfer from cooling block to liquid. FEM simulations have been used to model the temperature distribution in the cooling blocks as a function of heat transfer coefficients.<<ETX>>","PeriodicalId":107140,"journal":{"name":"Proceedings of 1994 IEEE/CHMT 10th Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130283267","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 : 1994-02-01DOI: 10.1109/STHERM.1994.288993
L. Mok
Thermal characteristics of silicon-based multichip modules and their associated heat sinks are presented. The structure of the multichip modules allows the heat generated inside a chip to be conducted away to the heat sink through the solder balls between the chips and the silicon substrate. The internal thermal resistances thus depend on the number of solder balls as well as the number of layers of insulators on the chip and the substrate. A thermal test module which has dimensions 59/spl times/59 mm mounted with nine thermal chips has been tested. The module can dissipate about 43 W at a chip temperature rise of 60/spl deg/C when a heat sink with fin height of 25 mm is used at 1 m/s airflow. The heat sink has seven doubly folded fins which are thermally optimized to give the best cooling performance while keeping the lowest pressure drop across the heat sink at a given airflow rate.<>
{"title":"Thermal management of silicon-based multichip modules","authors":"L. Mok","doi":"10.1109/STHERM.1994.288993","DOIUrl":"https://doi.org/10.1109/STHERM.1994.288993","url":null,"abstract":"Thermal characteristics of silicon-based multichip modules and their associated heat sinks are presented. The structure of the multichip modules allows the heat generated inside a chip to be conducted away to the heat sink through the solder balls between the chips and the silicon substrate. The internal thermal resistances thus depend on the number of solder balls as well as the number of layers of insulators on the chip and the substrate. A thermal test module which has dimensions 59/spl times/59 mm mounted with nine thermal chips has been tested. The module can dissipate about 43 W at a chip temperature rise of 60/spl deg/C when a heat sink with fin height of 25 mm is used at 1 m/s airflow. The heat sink has seven doubly folded fins which are thermally optimized to give the best cooling performance while keeping the lowest pressure drop across the heat sink at a given airflow rate.<<ETX>>","PeriodicalId":107140,"journal":{"name":"Proceedings of 1994 IEEE/CHMT 10th Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133584079","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 : 1994-02-01DOI: 10.1109/STHERM.1994.288994
B. Gromoll
Future 3D electronics packaging systems will require micro cooling systems that can be integrated and permit the continued use of air as a coolant. To achieve this, new types of silicon micro heat exchangers were made using an anisotropic etching process. Various heat exchanger configurations and sizes were made using sandwich and stacking techniques. They can be used either as a heat exchanger for direct cooling with compressed air or as a heat pipe and thermosyphon for indirect cooling with fan-blown air. The performance characteristics of the various cooling systems are stated. The micro-heat-pipe can be used for power loss densities of up to 3 W/cm/sup 2/, the direct air cooling up to 15 W/cm/sup 2/ and the thermosyphon up to 25 W/cm/sup 2/. Cooling performances are achieved that are otherwise only possible with liquid cooling. The practical application of the micro cooling system is demonstrated using the example of the Pentium processor. With a power loss of 15 W, the micro cooling system is able to limit the increase in operating temperature to 15 K. The volume of the micro heat exchanger is 2.5 cm/sup 3/ and therefore considerably smaller than that of standard heat sinks.<>
{"title":"Advanced micro air-cooling systems for high density packaging","authors":"B. Gromoll","doi":"10.1109/STHERM.1994.288994","DOIUrl":"https://doi.org/10.1109/STHERM.1994.288994","url":null,"abstract":"Future 3D electronics packaging systems will require micro cooling systems that can be integrated and permit the continued use of air as a coolant. To achieve this, new types of silicon micro heat exchangers were made using an anisotropic etching process. Various heat exchanger configurations and sizes were made using sandwich and stacking techniques. They can be used either as a heat exchanger for direct cooling with compressed air or as a heat pipe and thermosyphon for indirect cooling with fan-blown air. The performance characteristics of the various cooling systems are stated. The micro-heat-pipe can be used for power loss densities of up to 3 W/cm/sup 2/, the direct air cooling up to 15 W/cm/sup 2/ and the thermosyphon up to 25 W/cm/sup 2/. Cooling performances are achieved that are otherwise only possible with liquid cooling. The practical application of the micro cooling system is demonstrated using the example of the Pentium processor. With a power loss of 15 W, the micro cooling system is able to limit the increase in operating temperature to 15 K. The volume of the micro heat exchanger is 2.5 cm/sup 3/ and therefore considerably smaller than that of standard heat sinks.<<ETX>>","PeriodicalId":107140,"journal":{"name":"Proceedings of 1994 IEEE/CHMT 10th Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115806401","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 : 1994-02-01DOI: 10.1109/STHERM.1994.289000
R. Simons
For the occasion of the 10th anniversary of the SEMI-THERM conference, this paper provides a look back at some of the developments that have taken place since its founding. Topics covered include thermal measurement, thermal characterization, thermal analysis and modeling, air cooling, water cooling, and immersion cooling.<>
{"title":"Microelectronics cooling and SEMI-THERM: a look back","authors":"R. Simons","doi":"10.1109/STHERM.1994.289000","DOIUrl":"https://doi.org/10.1109/STHERM.1994.289000","url":null,"abstract":"For the occasion of the 10th anniversary of the SEMI-THERM conference, this paper provides a look back at some of the developments that have taken place since its founding. Topics covered include thermal measurement, thermal characterization, thermal analysis and modeling, air cooling, water cooling, and immersion cooling.<<ETX>>","PeriodicalId":107140,"journal":{"name":"Proceedings of 1994 IEEE/CHMT 10th Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122358545","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 : 1994-02-01DOI: 10.1109/STHERM.1994.288998
C. L. Chapman, S. Lee, B. Schmidt
Comparative thermal tests have been carried out using, aluminum heat sinks made with extruded fin, cross-cut rectangular pins, and elliptical shaped pins in low air flow environments. The elliptical pin heat sink was designed to minimize the pressure loss across the heat sink by reducing the vortex effects and to enhance the thermal performance by maintaining large exposed surface area available for heat transfer. The performance of the elliptical pin heat sink was compared with those of extruded straight and crosscut fin heat sinks, all designed for an ASIC chip. The results of the straight fin were also compared with those obtained by using Sauna, a commercially available heat sink modeling program developed based on empirical expressions. In addition to the thermal measurements, the effect of air flow bypass characteristics in open duct configuration was investigated. As expected, the straight fin experienced the lowest amount of flow bypass over the heat sink. For this particular application, where the heat source is localized at the center of the heat sink base plate, the overall thermal resistance of the straight fin was lower than the other two designs mainly due to the combined effect of enhanced lateral conduction along the fins and the lower flow bypass characteristics.<>
{"title":"Thermal performance of an elliptical pin fin heat sink","authors":"C. L. Chapman, S. Lee, B. Schmidt","doi":"10.1109/STHERM.1994.288998","DOIUrl":"https://doi.org/10.1109/STHERM.1994.288998","url":null,"abstract":"Comparative thermal tests have been carried out using, aluminum heat sinks made with extruded fin, cross-cut rectangular pins, and elliptical shaped pins in low air flow environments. The elliptical pin heat sink was designed to minimize the pressure loss across the heat sink by reducing the vortex effects and to enhance the thermal performance by maintaining large exposed surface area available for heat transfer. The performance of the elliptical pin heat sink was compared with those of extruded straight and crosscut fin heat sinks, all designed for an ASIC chip. The results of the straight fin were also compared with those obtained by using Sauna, a commercially available heat sink modeling program developed based on empirical expressions. In addition to the thermal measurements, the effect of air flow bypass characteristics in open duct configuration was investigated. As expected, the straight fin experienced the lowest amount of flow bypass over the heat sink. For this particular application, where the heat source is localized at the center of the heat sink base plate, the overall thermal resistance of the straight fin was lower than the other two designs mainly due to the combined effect of enhanced lateral conduction along the fins and the lower flow bypass characteristics.<<ETX>>","PeriodicalId":107140,"journal":{"name":"Proceedings of 1994 IEEE/CHMT 10th Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125896825","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/STHERM.1994.288990
J. Sofia
A technique for synthesizing dynamic models comprised of discrete thermal resistances and capacitances directly from thermal step-response data on packaged semiconductor devices has been developed. Such models reveal the effective internal-package thermal resistances which comprise the overall junction-to-ambient or junction-to-case thermal resistance. These models can discriminate lumped internal constituent resistances including die/die-attachment spreading, internal package spreading, and case-to-air dissipation. The thermal step-response has been experimentally and analytically studied using the electrical method of junction temperature measurement. The interpretation and accuracy of these synthetic models have been investigated on a collection of test-case devices. Overshoot anomalies exhibited by junction-to-case thermal step responses have been examined experimentally and explained with synthetic model analysis. The application of synthetic models to computing thermal impedance for non-constant or cyclic device-powering conditions is also presented.<>
{"title":"Analysis of thermal transient data with synthesized dynamic models for semiconductor devices","authors":"J. Sofia","doi":"10.1109/STHERM.1994.288990","DOIUrl":"https://doi.org/10.1109/STHERM.1994.288990","url":null,"abstract":"A technique for synthesizing dynamic models comprised of discrete thermal resistances and capacitances directly from thermal step-response data on packaged semiconductor devices has been developed. Such models reveal the effective internal-package thermal resistances which comprise the overall junction-to-ambient or junction-to-case thermal resistance. These models can discriminate lumped internal constituent resistances including die/die-attachment spreading, internal package spreading, and case-to-air dissipation. The thermal step-response has been experimentally and analytically studied using the electrical method of junction temperature measurement. The interpretation and accuracy of these synthetic models have been investigated on a collection of test-case devices. Overshoot anomalies exhibited by junction-to-case thermal step responses have been examined experimentally and explained with synthetic model analysis. The application of synthetic models to computing thermal impedance for non-constant or cyclic device-powering conditions is also presented.<<ETX>>","PeriodicalId":107140,"journal":{"name":"Proceedings of 1994 IEEE/CHMT 10th Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116929373","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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