| 1. |
- Liu, Ya, 1991, et al.
(author)
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Thermally Conductive and Electrically Insulating PVP/Boron Nitride Composite Films for Heat Spreader
- 2019
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In: Proceedings - 2019 IMAPS Nordic Conference on Microelectronics Packaging, NORDPAC 2019. ; , s. 1-5
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Conference paper (peer-reviewed)abstract
- Thermally conductive materials with electrically insulating properties have been extensively investigated for thermal management of electronic devices. The combined properties of high thermal conductivity, structural stability, corrosion resistance and electric resistivity make hexagonal boron nitride (h-BN) a promising candidate for this purpose. Theoretical studies have revealed that h-BN has a high in-plane thermal conductivity up to 400-800 W m-1 K-1 at room temperature. However, it is still a big challenge to achieve high thermally conductive h-BN thick films that are commercially feasible due to its poor mechanical properties. On the other hand, many polymers exhibit advantages for flexibility. Thus, combining the merits of polymer and the high thermal conductivity of h-BN particles is considered as a promising solution for this issue. In this work, orientated PVP/h-BN films were prepared by electrospinning and a subsequent mechanical pressing process. With the optimized h-BN loading, a PVP/h-BN composite film with up to 22 W m-1 K-1 and 0.485 W m-1 K-1 for in-plane and through-plane thermal conductivity can be achieved, respectively. We believe this work can help accelerate the development of h-BN for thermal management applications.
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| 2. |
- Liu, Ya, 1991, et al.
(author)
-
Thermally Conductive and Electrically Insulating PVP/Boron Nitride Composite Films for Heat Spreader
- 2019
-
In: Advancing Microelectronics. - 2222-8748. ; 2019:NOR, s. 1-5
-
Journal article (peer-reviewed)abstract
- Thermally conductive materials with electrically insulating properties have been extensively investigated for thermal management of electronic devices. The combined properties of high thermal conductivity, structural stability, corrosion resistance and electric resistivity make hexagonal boron nitride (h-BN) a promising candidate for this purpose. Theoretical studies have revealed that h-BN has a high in-plane thermal conductivity up to 400 - 800 W m−1 K−1 at room temperature. However, it is still a big challenge to achieve high thermally conductive h-BN thick films that are commercially feasible due to its poor mechanical properties. On the other hand, many polymers exhibit advantages for flexibility. Thus, combining the merits of polymer and the high thermal conductivity of h-BN particles is considered as a promising solution for this issue. In this work, orientated PVP/h-BN films were prepared by electrospinning and a subsequent mechanical pressing process. With the optimized h-BN loading, a PVP/h-BN composite film with up to 22 W m-1 K-1 and 0.485 W m-1 K-1 for in-plane and through-plane thermal conductivity can be achieved, respectively. We believe this work can help accelerate the development of h-BN for thermal management applications.
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| 3. |
- Enmark, Markus, 1991, et al.
(author)
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Reliability Characterization of Graphene Enhanced Thermal Interface Material for Electronics Cooling Applications
- 2022
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In: 2022 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2022.
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Conference paper (peer-reviewed)abstract
- Graphene-based products are gaining popularity in thermal management applications in high performance electronics systems. The ultra-high thermal conductivity of graphene together with its relatively low density makes it a suitable material for reaching high cooling capability in lightweight applications. An example of products that are starting to enter the market is graphene enhanced thermal interface materials (TIMs). Pristine graphene enhanced TIMs are well characterized and show high thermal conductivity and low thermal interface resistance. Before these TIMs can take the next step from being a niche product to reach high volume sales on the market, it needs to be proven that they have stable performance over time when conditioned and aged according to industry reliability standards. In this work, a set of customized test rigs was designed, and graphene enhanced TIMs of three different thicknesses were tested. The TIMs were compressed by 30% and then subjected to three different industry standard reliability tests; thermal aging, temperature cycling and damp heat. The thermal resistance was measured sequentially during each test to monitor change over time. The reliability tests are still ongoing and so far the tested graphene enhanced TIMs have stable performance over time with some observable trends for the different tests. At the current test time the maximum degradation in thermal resistance is 13%, measured after 511 cycles in the thermal cycling test. The used test method is deemed promising for reliability comparison and future requirement standardization on thermal pads.
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| 4. |
- Guo, Sihua, et al.
(author)
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Characterization of a Novel Cost-efficient and Environmentally Friendly Graphene-enhanced Thermal Interface Material
- 2023
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In: 24th European Microelectronics and Packaging Conference, EMPC 2023.
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Conference paper (peer-reviewed)abstract
- With the continuous development of electronic devices, effective heat dissipation has become a major factor affecting service life. Thermal interface materials (TIM) play a key role in controlling heat dissipation of electronic devices and have thus attracted widespread attention. In this study, we used graphene flakes (GF) derived from graphene film that is wasted during the preparation of commercial large-scale graphene-enhanced TIMs as thermally conductive fillers to formulate a new TIM. The thermal conductivity of the developed TIM is 50% higher with GFs than without. Furthermore, the TIM has a tensile strength of 0.46 MPa with an elongation at break of 1225%, a maximum compression strength of 0.64 MPa at 50% compression, and high mechanical cycle stability. This report provides a cost-efficient and environmentally friendly approach to producing high-performance TIMs for electronic cooling applications.
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| 5. |
- Guo, Sihua, et al.
(author)
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Toward ultrahigh thermal conductivity graphene films
- 2023
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In: 2D Materials. - : IOP Publishing. - 2053-1583. ; 10:1
-
Journal article (peer-reviewed)abstract
- With increasing demands of high-performance and functionality, electronics devices generate a great amount of heat. Thus, efficient heat dissipation is crucially needed. Owing to its extremely good thermal conductivity, graphene is an interesting candidate for this purpose. In this paper, a two-step temperature-annealing process to fabricate ultrahigh thermal conductive graphene assembled films (GFs) is proposed. The thermal conductivity of the obtained GFs was as high as 3826 +/- 47 W m(-1) K-1. Extending the time of high-temperature annealing significantly improved the thermal performance of the GF. Structural analyses confirmed that the high thermal conductivity is caused by the large grain size, defect-free stacking, and high flatness, which are beneficial for phonon transmission in the carbon lattice. The turbostratic stacking degree decreased with increasing heat treatment time. However, the increase in the grain size after long heat treatment had a more pronounced effect on the phonon transfer of the GF than that of turbostratic stacking. The developed GFs show great potential for efficient thermal management in electronics devices.
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| 6. |
- Nkansah, Amos, et al.
(author)
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Reliability study on high thermally conductive graphene film as heat spreader in electronics cooling applications
- 2018
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In: IMAPS Nordic Annual Conference, NordPack 2018. ; 2018, s. 126-130
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Conference paper (peer-reviewed)abstract
- ―Graphene films (GFs) were fabricated and can be applied for dissipating heat from electronics such as portable electronics, laptops, light emitting diodes (LEDs) and other power electronics. These GFs are capable of transporting heat from electronic components. Due to its high thermal conductivity, these GFs are capable to transfer the heat efficiently from electronic component to the heat spreader or heat sink. The cooling failure of the GFs may lead to irreversible damage to the electronic system, hence it is necessary to investigate the long-term reliability of the film under certain harsh conditions. To evaluate the reliability of the GFs, the thermal cycles and moisture test are performed. The effect of temperature cycling (500 cycle) is tested by using an environmental oven with extreme temperatures. The effect of moisture penetration of the GFs is tested for 1024 hours. The thermal conductivity after these two test conditions does not change too much comparing to material before subjecting to test. The electrical conductivity value under the temperature cycling declined by 30% after 500 cycles and that of moisture test was improved by 20%. The result shows that the thermal conductivity of the GFs is quite stable under temperature cycle (500 cycles) and moisture test (1024 hours).
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| 7. |
- Shen, Zhiyang, et al.
(author)
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A Critical Assessment of graphene based heat pipes for electronics and power module cooling applications
- 2023
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In: 2023 24th International Conference on Electronic Packaging Technology, ICEPT 2023.
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Conference paper (peer-reviewed)abstract
- As the most effective heat transfer device, heat pipes have received widespread attention, but traditional heat pipes may be difficult to meet heat dissipation requirements in the near future. Since graphene was discovered, its ultra-high thermal conductivity has been the focus of people's research and application. Therefore, the combination of graphene and heat pipes is a method to improve the performance of existing heat pipes. This paper is a critical assessment of recent advances in graphene-based heat pipes. In the paper, we conducted a simple theoretical analysis of the operation of the heat pipe, and also summarized the research status, enhancement mechanism, and enhancement method of graphene-enhanced heat pipes, and predicted the future development direction. The results show that depositing graphene-based materials on wicks, using graphene-based nanofluids, and application of graphene composites are effective ways to enhance the performance of heat pipes.
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| 8. |
- Wang, Nan, et al.
(author)
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Highly Thermally Conductive and Light Weight Copper/Graphene Film Laminated composites for Cooling Applications
- 2018
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In: 2018 19TH INTERNATIONAL CONFERENCE ON ELECTRONIC PACKAGING TECHNOLOGY (ICEPT). - 9781538663868 - 9781538663868 ; , s. 1588-1592
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Conference paper (peer-reviewed)abstract
- A light-weight, robust and highly thermal conductive copper/graphene film laminated structure was developed as novel heat spreading materials for thermal management applications. The advantages of the copper/graphene film laminated structure lie in its ability to combine both good mechanical properties of metals and excellent thermal properties of graphene film. Graphene films (GFs) were fabricated via self-assembly of graphene oxide (GO) sheets and post-treated by high temperature graphitization and mechanical pressing. The resulted GFs show excellent flexibility and greatly improved tensile strength which is over 3 times higher than commercial PGS. The successful lamination between copper and GFs was realized by indium bonding. Thin indium layers can provide complete physical contact between copper and GFs, and thereby, minimize the contact resistance induced by surface roughness. The measured contact thermal resistance between copper and GFs bonded by indium is in the range of 2-5 Kmm(2)/W for a working temperature between 20 degrees C to 100 degrees C. This value is orders magnitude lower than other bonding methods, including direct hot pressing of copper and GFs, tape bonding and thermal conductive adhesive (TCA) bonding. By tailoring the thickness of GFs, desirable laminated composites with optimized thermal conductivity can be obtained, which offers an efficient heat dissipation solution for power driven systems.
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| 9. |
- Wang, Nan, et al.
(author)
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Light-weight Compressible and Highly Thermal Conductive Graphene-based Thermal Interface Material
- 2018
-
In: 2018 7th Electronic System-Integration Technology Conference (ESTC). - 9781538668146
-
Conference paper (peer-reviewed)abstract
- High density packaging in combination with increased transistor integration inevitably leads to challenging power densities in terms of thermal management. Thermal interface materials (TIMs) play a key role in thermal management by transferring heat from the surface of power devices. The conventional TIMs used in the microelectronics industry today basically are particle laden polymer matrix composites, which have the advantages of good reliability and ease of use. However, the thermal conductivity (K) of these composites is generally limited to 10 W/mK, which is hard to meet the goal for efficient thermal management in power devices. Here, we solve the problem by applying a novel highly thermal conductive and compressible graphene based TIMs (GTs). Composed by vertical graphene structures, GTs provide a continuous high thermal conductivity phase along the path of thermal transport, which lead to outstanding thermal properties. By tailoring ratios of graphene in the polymer binder, bulk thermal conductivity of GTs can be varied from 50 to 1000 W/mK. This result isorders of magnitude higher than conventional TIMs, and even outperforms the pure indium TIMs by over ten times. Meanwhile, the highly flexible and foldable nature of vertical graphene enables at least 20% compressibility of the GTs upon small applied pressures (≤ 400 KPa). As excellent gap fillers, GT can provide complete physical contact between two surfaces and thereby minimize the contact resistance to heat flow. The measured minimum thermal resistance and maximum effective thermal conductivity for GTs reaches to ∼ Kmm2/W and ∼ W/mK, respectively. Such values are significantly higher than the randomly dispersed composites presented above, and show almost comparable thermal performance as pure indium bonding. In addition, the GTs has more advantages than indium/solder bonding, including low weight (density <2g/cm3), low complexity during assembly and maintainability. The resulting GTs thus opens new opportunities for addressing large heat dissipation issues both in through-plane and in-plane directions for form-factor driven electronics and other high power driven systems.
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| 10. |
- Wang, Nan, et al.
(author)
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Vertically Aligned Graphene-based Thermal Interface Material with High Thermal Conductivity
- 2018
-
In: THERMINIC 2018 - 24th International Workshop on Thermal Investigations of ICs and Systems, Proceedings. - 9781538667590 ; , s. 285-288
-
Conference paper (peer-reviewed)abstract
- High density packaging in combination with increased transistor integration inevitably leads to challenging power densities in terms of thermal management. Here, a novel highly thermal conductive and lightweight graphene based thermal interface materials (GT) was developed for thermal management in power devices. Composed by vertically graphene structures, GTs provide a continuous high thermal conductivity phase along the path of thermal transport, which lead to outstanding thermal properties. The highest through-plane thermal conductivity GTs reaches to 1000 W/mK, which is orders of magnitude higher than conventional TIMs, and even outperforms the pure indium by over ten times. In addition, a thin layer of indium metal that coated on the surface of GTs can easily form alloys with many other metals at a relatively low reflow temperature. Therefore, GTs, as an excellent TIM, can provide complete physical contact between two surfaces with minimized the contact resistance. The measured total thermal resistance and effective thermal conductivity by using 300 mu m thick GTs as TIM between two copper blocks reaches to similar to 3.7 Kmm(2)/W and similar to 90 W/mK, respectively. Such values are significantly higher than the randomly dispersed composites presented above, and show even better thermal performance than pure indium bonding. In addition, GTs has more advantages than pure indium bonding, including low weight (density < 2 g/cm(3)), low complexity during assembly and maintainability. The resulting GTs thus opens new opportunities for addressing large heat dissipation issues in form-factor driven electronics and other high power driven systems.
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