Experimental Study of a High Performance Aligned Graphite Thermal Interface Material

2012 ◽  
Author(s):  
Y. Zhao ◽  
D. Strauss ◽  
Y. C. Chen ◽  
T. Liao ◽  
C. L. Chen
Keyword(s):  
High Temperature ◽  
Thermal Cycling ◽  
Thermal Performance ◽  
Critical Role ◽  
Temperature Stability ◽  
Thermal Interface Material ◽  
Thermal Resistivity ◽  
High Temperature Stability ◽  
Thermal Interface ◽  
Copper Surfaces

Thermal interface materials (TIMs) play a critical role in microelectronics packaging. In this paper, a novel aligned-graphite/solder TIM is described. Unlike traditional TIMs infiltrated with randomly-oriented high-conductivity fillers, the aligned-graphite/solder TIMs provide both extraordinarily high thermal conductivity along the heat transport direction, and controllable stiffness to conform to surfaces with different roughness and hardness, greatly improving the overall heat transfer performance. In addition, vertically connected solder layers can lock the graphite layers in place and reinforce the strength of the entire package. Thermal performance of the graphite TIMs was determined experimentally based on the ASTM-D5470 method with comparison to two commercially available TIMs. The graphite TIMs also experienced a thermal cycling test and a high temperature stability test to establish its performance merit in practical applications. Experiments showed that the overall thermal resistivity of a 150-to-200-μm-thick graphite TIM film was less than 0.035 °C/(W/cm2) when bonding two smooth copper surfaces together at a processing pressure of 30 psi, which corresponds to an approximately 2–3X improvement over a Ag-Sn solder alloy (Indalloy 121). Preliminary thermal cycling and high temperature stability tests showed that the thermal performance of the graphite TIM was very stable, and did not degrade during these tests. The tests also indicated that the presence of surface roughness of 10 μm on one of the copper surfaces reduced the overall thermal resistivity by approximately 30%. A numerical simulation verified this trend.

scholarly journals Reliability Investigation of a Carbon Nanotube Array Thermal Interface Material

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2080 ◽  
Author(s):  
Andreas Nylander ◽  
Josef Hansson ◽  
Majid Kabiri Samani ◽  
Christian Chandra Darmawan ◽  
Ana Borta Boyon ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Thermal Performance ◽  
Photoelectron Spectroscopy ◽  
Thermal Contact ◽  
Thermal Interface Material ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Thermal Interface Resistance ◽  
Further Development ◽  
Interface Materials

As feature density increases within microelectronics, so does the dissipated power density, which puts an increased demand on thermal management. Thermal interface materials (TIMs) are used at the interface between contacting surfaces to reduce the thermal resistance, and is a critical component within many electronics systems. Arrays of carbon nanotubes (CNTs) have gained significant interest for application as TIMs, due to the high thermal conductivity, no internal thermal contact resistances and an excellent conformability. While studies show excellent thermal performance, there has to date been no investigation into the reliability of CNT array TIMs. In this study, CNT array TIMs bonded with polymer to close a Si-Cu interface were subjected to thermal cycling. Thermal interface resistance measurements showed a large degradation of the thermal performance of the interface within the first 100 cycles. More detailed thermal investigation of the interface components showed that the connection between CNTs and catalyst substrate degrades during thermal cycling even in the absence of thermal expansion mismatch, and the nature of this degradation was further analyzed using X-ray photoelectron spectroscopy. This study indicates that the reliability will be an important consideration for further development and commercialization of CNT array TIMs.

High temperature Au-based solder reliability in electronic packages for harsh environments

2011 ◽  
Vol 2011 (1) ◽  
pp. 000438-000445
Author(s):  
M.F. Sousa ◽  
S. Riches ◽  
C. Johnston ◽  
P.S. Grant
Keyword(s):  
High Temperature ◽  
Thermal Cycling ◽  
Thermal Shock ◽  
Microstructural Analysis ◽  
Temperature Stability ◽  
Acoustic Microscopy ◽  
Harsh Environments ◽  
Electronic Packages ◽  
High Temperature Stability ◽  
Die Attach

The operation of electronic packages in high temperature environments is a significant challenge for the microelectronics industry, and poses a challenge to the traditional temperature limit of 125°C for high electronic systems, such as those used in down-hole, well-logging and aero-engine applications. The present work aims to develop understanding of how and why attach materials for Si dies degrade/fail under harsh environments by investigating high temperature Au based solders. Au-2wt%Si eutectic melts at < 400°C and offers high temperature stability but high temperature processing and complex manufacturing steps are the major drawbacks. Changes in the die attach material were investigated by isothermal ageing at 350°C, thermal shock and thermal cycling treatments. Die attach reliability investigated by thermal shock and thermal cycling showed that the bonded area degraded. Nevertheless, most of the samples tested had high bonded area ranging from 92.5 to 97.5%. The failure behaviour of the die attach materials included cracking of die and/or attach material, delamination and voiding. Scanning acoustic microscopy images provided a rapid assessment of delamination and other defects and their location within the package. Microstructural analysis and die shear testing were also carried out, along with the high temperature endurance of a SOI test chip for signal conditioning and processing applications at 250°C. All functions evaluated have shown stable performance at 250°C for up to 9000 hours.

Microstructural Evolution of GdZ and DySZ Based EB-PVD TBC Systems After Thermal Cycling at High Temperature

2013 ◽  
Author(s):  
Ahmed Umar Munawar ◽  
Uwe Schulz
Keyword(s):  
High Temperature ◽  
Thermal Cycling ◽  
Physical Vapor Deposition ◽  
Temperature Stability ◽  
Life Time ◽  
Double Layers ◽  
Inlet Temperature ◽  
High Temperature Stability ◽  
Turbine Inlet Temperature ◽  
Tbc Systems

Lower thermal conductivity and high temperature stability are the two properties which are highly desired from ceramic top coat materials in TBC systems. Gadolinium Zirconate, Gd2Zr2O7, (GdZ) and Dyprosia Stabilized Zirconia (DySZ) are two of the candidate materials with such properties and consequently the TBC system would be able to work at higher turbine inlet temperature (TIT) or the lifetime can be increased. In the present study, life time measurements are done for single and double layered Electron Beam Physical Vapor Deposition (EB-PVD) GdZ and DySZ samples by thermal-cycling tests. The double layered TBCs consisted of a thin 7YSZ layer and, on top, the new candidate material. Both single and double layered samples of GdZ and DySZ have shown similar or better lifetimes than the standard 7YSZ samples. However, single layered TBCs showed better lifetime results than the respective double layers. In this study, changes in the microstructure, diffusion of elements and sintering of the TBC materials with aging are observed.

Microstructural Evolution of GdZ and DySZ Based EB-PVD TBC Systems After Thermal Cycling at High Temperature

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Ahmed Umar Munawar ◽  
Uwe Schulz ◽  
Giovanni Cerri
Keyword(s):  
High Temperature ◽  
Thermal Cycling ◽  
Physical Vapor Deposition ◽  
Temperature Stability ◽  
Double Layers ◽  
Inlet Temperature ◽  
High Temperature Stability ◽  
Turbine Inlet Temperature ◽  
Barrier Coating ◽  
Tbc Systems

Lower thermal conductivity and high temperature stability are the two properties which are highly desired from ceramic top coat materials in thermal barrier coating (TBC) systems. Gadolinium zirconate, Gd2Zr2O7 (GdZ) and dyprosia stabilized zirconia (DySZ) are two of the candidate materials with such properties and consequently the TBC system would be able to work at higher turbine inlet temperature (TIT) or the lifetime can be increased. In the present study, lifetime measurements are done for single and double layered electron beam physical vapor deposition (EB-PVD) GdZ and DySZ samples by thermal-cycling tests. The double layered TBCs consisted of a thin 7YSZ layer and, on top, the new candidate material. Both single and double layered samples of GdZ and DySZ have shown similar or better lifetimes than the standard 7YSZ samples. However, single layered TBCs showed better lifetime results than the respective double layers. In this study, changes in the microstructure, diffusion of elements and sintering of the TBC materials with aging are observed.

UNS N06455

Alloy Digest ◽  
1989 ◽  
Vol 38 (1) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Stress Corrosion Cracking ◽  
Temperature Stability ◽  
Heat Treating ◽  
High Ductility ◽  
High Temperature Stability ◽  
Nickel Chromium ◽  
Long Time ◽  
Resistance To Stress

Abstract UNS NO6455 is a nickel-chromium-molybdenum alloy with outstanding high-temperature stability as shown by high ductility and corrosion resistance even after long-time aging in the range 1200-1900 F. The alloy also has excellent resistance to stress-corrosion cracking and to oxidizing atmospheres up to 1900 F. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ni-367. Producer or source: Nickel and nickel alloy producers.

UNS R54620

Alloy Digest ◽  
1987 ◽  
Vol 36 (7) ◽  
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Time Use ◽  
Temperature Stability ◽  
High Strength ◽  
Heat Treating ◽  
High Temperature Stability ◽  
Beta Titanium Alloy ◽  
Beta Titanium ◽  
Long Time

Abstract UNS No. R54620 is an alpha-beta titanium alloy. It has an excellent combination of tensile strength, creep strength, toughness and high-temperature stability that makes it suitable for service to 1050 F. It is recommended for use where high strength is required. It has outstanding advantages for long-time use at temperatures to 800 F. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and bend strength as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ti-86. Producer or source: Titanium alloy mills.

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