TIM Selection for an IGBT Cold Plate Using Experimental and Numerical Modeling

2013 ◽  
Author(s):  
John F. Maddox ◽  
Roy W. Knight ◽  
Sushil H. Bhavnani
Keyword(s):  
Selection Procedure ◽  
Thermal Interface Material ◽  
Water Mixture ◽  
Cold Plate ◽  
Thermal Interface ◽  
Cooling Fluid ◽  
Selection For ◽  
Thermal Grease ◽  
Selection Of

Experimental measurements were used in conjunction with a numerical model to perform an in situ analysis of an IGBT cooling solution with a cold plate utilizing an 85–90°C ethylene glycol-water mixture as the cooling fluid. This process was used to aid in the selection of an appropriate thermal interface material (TIM) for the application. The effects of elevated temperature and thermal cycling on the performance of the TIM were investigated during the selection procedure. Applying the thermal grease with the cold plate at 70°C rather than 30°C caused a reduction in the junction to case resistance of 74% and 78% for the two thermal greases tested.

Identifying Measurement Invariant Item Sets in Cross-Cultural Settings Using an Automated Item Selection Procedure

Methodology ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 177-188 ◽  
Author(s):  
Martin Schultze ◽  
Michael Eid
Keyword(s):  
Measurement Invariance ◽  
Optimal Solution ◽  
Selection Procedure ◽  
Cross Cultural ◽  
Item Selection ◽  
Ant System ◽  
Item Quality ◽  
Ant System Algorithm ◽  
Selection For ◽  
Selection Of

Abstract. In the construction of scales intended for the use in cross-cultural studies, the selection of items needs to be guided not only by traditional criteria of item quality, but has to take information about the measurement invariance of the scale into account. We present an approach to automated item selection which depicts the process as a combinatorial optimization problem and aims at finding a scale which fulfils predefined target criteria – such as measurement invariance across cultures. The search for an optimal solution is performed using an adaptation of the [Formula: see text] Ant System algorithm. The approach is illustrated using an application to item selection for a personality scale assuming measurement invariance across multiple countries.

Development of High Thermally Conductive Die Attach for TIM Applications

2019 ◽  
Vol 2019 (1) ◽  
pp. 000312-000315
Author(s):  
Maciej Patelka ◽  
Sho Ikeda ◽  
Koji Sasaki ◽  
Hiroki Myodo ◽  
Nortisuka Mizumura
Keyword(s):  
Thermal Conductivity ◽  
High Power ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
Power Semiconductor ◽  
Die Attach ◽  
Industry Standards ◽  
Thermally Conductive ◽  
Low Modulus ◽  
Thermal Grease

Abstract High power semiconductor applications require a Thermal Interface Die Attach Material with high thermal conductivity to efficiently release the heat generated from these devices. Current Thermal Interface Material solutions such as thermal grease, thermal pads and silicones have been industry standards, however may fall short in performance for high temperature or high-power applications. This presentation will focus on development of a cutting-edge Die Attach Solution for Thermal Interface Management, focusing on Fusion Type epoxy-based Ag adhesive with an extremally low Storage Modulus and the Thermal Conductivity reaching up to 30W/mK, and also Very Low Modulus, Low-Temperature Pressureless Sintered Silver Die Attach with the Thermal Conductivity of 70W/mK.

Using In situ Capacitance Measurements to Monitor the Stability of Thermal Interface Materials in Complex PCB Assemblies

2010 ◽  
Vol 2010 (1) ◽  
pp. 000450-000457
Author(s):  
Michael Gaynes ◽  
Timothy Chainer ◽  
Edward Yarmchuk ◽  
John Torok ◽  
David Edwards ◽  
...  
Keyword(s):  
Thermal Cycle ◽  
Bond Line ◽  
Thermal Interface Material ◽  
Circuit Board ◽  
Large Area ◽  
Voltage Transformer ◽  
Heat Spreader ◽  
Thermal Interface ◽  
Thermal Solution

A thermal solution for an array of voltage transformer modules which are cooled by a large area, common aluminum heat spreader for a high end server was evaluated using an in situ, capacitive bond line thermal measurement technique. The method measures the capacitance of a non-electrically conducting thermal interface material (TIM) between the electronic module and heat spreader to quantify the TIM bond line effective thickness during assembly and operation. The thermal resistance of the TIM has the same geometric dependence as the inverse of capacitance, therefore, the capacitive technique also provided a monitor of the thermal performance of the interface. This technique was applied to measure the bond line in real time during the assembly of the heat spreader to an array of 37 modules mounted on a printed circuit board. The results showed that the target bond lines were not achieved by application of a constant force alone on the heat spreader, and guided an improved assembly process. The mechanical motion of the TIM was monitored in situ during thermal cycling and found to fluctuate systematically from the hot to cold portions of the thermal cycle, either compressing or stretching the TIM respectively. The capacitive bond line trend showed thermal interface degradation vs. cycle count for several modules which was confirmed by disassembly and visual inspection. Areas of depleted TIM ranged as high as 25% of the module area. Several design and material changes were shown to improve the TIM stability. Power cycling tests were run in parallel to the thermal cycle tests to help relate the results to field performance. The capacitance technique enabled the development and verification of a thermal solution for a complex mechanical system early in the development cycle.

Selection practices in dairy herds. 1. First lactation performance and survival to the second lactation

1966 ◽  
Vol 8 (3) ◽  
pp. 467-480 ◽  
Author(s):  
C. J. M. Hinks
Keyword(s):  
Milk Yield ◽  
Selection Procedure ◽  
Dairy Herds ◽  
Productive Capacity ◽  
Lactation Performance ◽  
Selection For ◽  
Calving Season ◽  
Main Determinants ◽  
The Relationship ◽  
Selection Of

1. The relationship between first lactation performance and the ability of individual animals to survive to the second lactation has been examined in Friesian and Ayrshire populations in an attempt to isolate the main determinants of survival, and to rationalise an apparently complicated selection procedure.2. Low milk yield was the most important single cause of culling in the first lactation, though the two breeds differed considerably in the relative importance of milk yield in the selection programme. Natural wastage, caused by factors beyond the control of the farmer, accounted for the disposal of 5·7% of the population during the first lactation. Selection for butterfat was marginal in both populations, and could only be detected at extreme butterfat percentages, where high butterfat tended to compensate for a poor milk yield, and low butterfat to confirm a decision to cull an average yielding animal. Survival was not significantly affected either by the size of the herd or by the age at calving.3. The proportion culled, and the intensity and effectiveness of selection for milk yield, were inversely related to the level of herd performance, and were greater in summer calving animals than in winter calvers.4. The analysis indicated that selection for milk yield in different environments could be adequately described in terms of the Normal Curve. Yield-survival curves were computed and compared for groups of animals in different herd and calving season environments. When milk yield was expressed in terms of the deviation from the herd-year average, it was found that summer calvers, and animals in low yielding herds, had to demonstrate a productive capacity of far greater individual merit, if their chances of survival were to match those of their winter calving herdmates, and those of their contemporaries in higher yielding herds. When milk yield was expressed in absolute terms the survival of individual animals of similar yield was comparable in all herd and season environments. It was concluded that all the herds included in the analysis had been subject to the same absolute standards of milk yield in the selection of first calvers.

Analytical Model of Heat Conduction in a Tubular Geometry With Application to a Nano-Structured Thermal Interface

2005 ◽  
Author(s):  
Anand Desai ◽  
James Geer ◽  
Bahgat Sammakia
Keyword(s):  
Thermal Conductivity ◽  
Power Dissipation ◽  
High Performance ◽  
Analytical Study ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
Inner Diameter ◽  
Parametric Analyses ◽  
Interface Materials

Power dissipation in electronic devices is projected to increase significantly over the next ten years to the range of 50-150 Watts per cm2 for high performance applications [1]. This increase in power represents a major challenge to systems integration since the maximum device temperature needs to be around 100 C. One of the primary obstacles to the thermal management of devices operating at such high powers is the thermal resistance between the device and the heat spreader or heat sink that it is attached to. Typically the in situ thermal conductivity of interface materials is in the range of 1 to 4 W/mK, even though the bulk thermal conductivity of the material may be significantly higher. In order to improve the effective in-situ thermal conductivity of interface materials nanotubes are being considered as a possible addition to such interfaces. The primary approach taken in the current study is to analyze the enhancement of the thermal interface by adding carbon nano tubular cylinders that are oriented in the direction of transport. This paper presents the results of an analytical study of transport in a thermal interface material that is enhanced with carbon nanotubes. A variety of parametric analyses are carried out, such as by varying the inner diameter of the nanotube and the power dissipation, and the effect on spreading resistance is calculated. The results indicate that for high thermal conductivity nanotubes there is a significant increase in the effective thermal conductivity of the thermal interface material.

A Numerical Study of Transport in a Thermal Interface Material Enhanced With Carbon Nanotubes

2005 ◽  
Vol 128 (1) ◽  
pp. 92-97 ◽  
Author(s):  
Anand Desai ◽  
Sanket Mahajan ◽  
Ganesh Subbarayan ◽  
Wayne Jones ◽  
James Geer ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
High Performance ◽  
Numerical Study ◽  
Temperature Drop ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
The Impact ◽  
Interface Materials

Power dissipation in electronic devices is projected to increase over the next 10years to the range of 150-250W per chip for high performance applications. One of the primary obstacles to the thermal management of devices operating at such high powers is the thermal resistance between the device and the heat spreader or heat sink that it is attached to. Typically the in situ thermal conductivity of interface materials is in the range of 1-4W∕mK, even though the bulk thermal conductivity of the material may be significantly higher. In an attempt to improve the effective in situ thermal conductivity of interface materials nanoparticles and nanotubes are being considered as a possible addition to such interfaces. This paper presents the results of a numerical study of transport in a thermal interface material that is enhanced with carbon nanotubes. The results from the numerical solution are in excellent agreement with an analytical model (Desai, A., Geer, J., and Sammakia, B., “Models of Steady Heat Conduction in Multiple Cylindrical Domains,” J. Electron. Packaging (to be published)) of the same geometry. Wide ranges of parametric studies were conducted to examine the effects of the thermal conductivity of the different materials, the geometry, and the size of the nanotubes. An estimate of the effective thermal conductivity of the carbon nanotubes was used, obtained from a molecular dynamics analysis (Mahajan, S., Subbarayan, G., Sammakia, B. G., and Jones, W., 2003, Proceedings of the 2003 ASME International Mechanical Engineering Congress and Exposition, Washington, D.C., Nov. 15–21). The numerical analysis was used to estimate the impact of imperfections in the nanotubes upon the overall system performance. Overall the nanotubes are found to significantly improve the thermal performance of the thermal interface material. The results show that varying the diameter of the nanotube and the percentage of area occupied by the nanotubes does not have any significant effect on the total temperature drop.

scholarly journals Development of High Thermally Conductive Die Attach for TIM Applications

2020 ◽  
Vol 17 (3) ◽  
pp. 106-109
Author(s):  
Maciej Patelka ◽  
Sho Ikeda ◽  
Koji Sasaki ◽  
Hiroki Myodo ◽  
Nortisuka Mizumura
Keyword(s):  
Thermal Conductivity ◽  
High Power ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
Power Semiconductor ◽  
Die Attach ◽  
Industry Standards ◽  
Thermally Conductive ◽  
Low Modulus ◽  
Thermal Grease

Abstract High-power semiconductor applications require a thermal interface die attach material with high thermal conductivity to efficiently release the heat generated from these devices. Current thermal interface material solutions such as thermal grease, thermal pads, and silicones have been industry standards, however may fall short in performance for high-temperature or high-power applications. This article focuses on development of a cutting-edge die attach solution for thermal interface management, focusing on fusion-type epoxy-based Ag adhesive with an extremely low storage modulus and the thermal conductivity reaching up to 30 W/mK, and also very low-modulus, low-temperature pressureless sintering silver die attach with a thermal conductivity of 70 W/mK.

Reliability of Interview in Selecting Students for Postgraduate Study in Clinical Psychology

1974 ◽  
Vol 34 (3) ◽  
pp. 819-825 ◽  
Author(s):  
Anne Broadhurst
Keyword(s):  
Clinical Psychology ◽  
Postgraduate Training ◽  
High Reliability ◽  
Reliability And Validity ◽  
Selection Procedure ◽  
Postgraduate Study ◽  
Selection For ◽  
Selection Of

Reliability of screening for selection for postgraduate training in clinical psychology was assessed by correlating ratings by four readers of the application papers. Correlations for the 128 applicants were reasonably high. Reliability of the interview procedure used with 29 of the shortlisted applicants was assessed by correlating ratings from four interviewers who worked in pairs. Those who interviewed together correlated significantly but other correlations were disappointingly low. It was shown also that the selection of preferred candidates from the total interviewed did not differ from chance. The results are discussed in terms of the quality of the candidates applying for training and of the reliability and validity of the selection procedure.

Thermal Conductivity of Diamond-Containing Grease

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Hung-En Chou ◽  
Shang-Ray Yang ◽  
Sea-Fue Wang ◽  
James C. Sung
Keyword(s):  
Thermal Conductivity ◽  
Heat Dissipation ◽  
Filler Content ◽  
Electronic Devices ◽  
Terminal Group ◽  
Thermal Interface Material ◽  
Particle Sizes ◽  
Thermal Interface ◽  
Thermal Grease ◽  
Single Filler

As a thermal interface material, thermal grease (TG) has been extensively applied to facilitate heat dissipation in electronic devices. Despite the superior thermal conductivity of diamond, researches on diamond-containing TGs remain rare. In this study, four kinds of TGs in which diamond served as essential filler were prepared and hot disk technique was applied to measure their thermal conductivity k(TG). After two unoverlapped particle sizes were selected, the volumetric filler content, terminal group, and viscosity of a polydimethylsiloxane (PDMS) matrix were modified in sequence. Based on the preferred recipe of a single-filler TG, two double-filler TG series were prepared by retaining the large diamonds and replacing the small ones by Al2O3 or ZnO, respectively. Depending on the content, it was found that diamond was not always the best choice for small filler. The highest k(TG), which was 23 times greater than the original k(PDMS), appeared in a ZnO-containing double-filler grease (=3.52 W/mK). The prediction for the maximum attainable thermal conductivity was preliminarily supported.

Durability of Low Melt Alloys as Thermal Interface Materials

2015 ◽  
Author(s):  
Chandan K. Roy ◽  
Daniel K. Harris ◽  
Sushil Bhavnani ◽  
Michael C. Hamilton ◽  
Wayne Johnson ◽  
...  
Keyword(s):  
Thermal Performance ◽  
Performance Testing ◽  
Thermal Interface Material ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Accelerated Life ◽  
Extended Aging ◽  
Interface Materials ◽  
Substrate Alloy

This paper focuses on developing a reliable thermal interface material (TIM) using low melt alloys (LMAs) containing gallium (Ga), indium (In), bismuth (Bi), and tin (Sn). The investigation described herein involved the in situ thermal performance of the LMAs as well as performance evaluation after accelerated life cycle testing, which included isothermal aging at 130°C and thermal cycling from −40°C to 80°C. Three alloys (75.5Ga &24.5In, 100Ga, and 51In, 32.5Bi &16.5Sn) were chosen for testing the thermal performance. Testing methodologies used follow ASTM D5470 protocols and the results are compared with some commercially available TIMs. The LMAs-substrate interaction was investigated by applying the alloys using different surface treatments (copper and tungsten). Measurements show that the alloys did survive extended aging and cycling depending upon the substrate-alloy combinations.

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