| 1. |
- Chen, Shujing, et al.
(författare)
-
Manufacturing Graphene-Encapsulated Copper Particles by Chemical Vapor Deposition in a Cold Wall Reactor
- 2019
-
Ingår i: ChemistryOpen. - : Wiley. - 2191-1363. ; 8:1, s. 58-63
-
Tidskriftsartikel (refereegranskat)abstract
- Functional fillers, such as Ag, are commonly employed for effectively improving the thermal or electrical conductivity in polymer composites. However, a disadvantage of such a strategy is that the cost and performance cannot be balanced simultaneously. Therefore, the drive to find a material with both a cost efficient fabrication process and excellent performance attracts intense research interest. In this work, inspired by the core-shell structure, we developed a facile manufacturing method to prepare graphene-encapsulated Cu nanoparticles (GCPs) through utilizing an improved chemical vapor deposition (CVD) system with a cold wall reactor. The obtained GCPs could retain their spherical shape and exhibited an outstanding thermal stability up to 179 degrees C. Owing to the superior thermal conductivity of graphene and excellent oxidation resistance of GCPs, the produced GCPs are practically used in a thermally conductive adhesive (TCA), which commonly consists of Ag as the functional filler. Measurement shows a substantial 74.6 % improvement by partial replacement of Ag with GCPs.
|
|
| 2. |
- Liu, Ya, 1991, et al.
(författare)
-
Effect of Boron Nitride Particle Geometry on the Thermal Conductivity of a Boron Nitride Enhanced Polymer Composite Film
- 2019
-
Ingår i: THERMINIC 2019 - 2019 25th International Workshop Thermal Investigations of ICs and Systems.
-
Konferensbidrag (refereegranskat)abstract
- Hexagonal Boron Nitride (h-BN) has been considered as a promising enhancement filler for thermal management due to its high thermal conductivity, structural stability, and super electrical resistivity. Numerus studies have reported using BN as an enhancement filler to achieve high thermally conductive polymer based thermal management materials. However, there are limited data regarding the influence of the flake size of BN sheets to the thermal management property of BN filled composites. In this work, three h-BN size geometries, including microscale h-BN powder, h-BN nanosheets, and a mixture of micro and nanoscale h-BN, were studied regarding its thermal transfer performance. The results show that h-BN nanosheets are able to achieve the highest in-plane thermal conductivity with loading from 0 - 5 wt% while for the through-plane thermal conductivity, all three geometries show similar thermal property when the filler loading less than 5 wt%. Through-plane thermal conductivity exhibits a sudden increase to 5.69 W m-1 K-1 at a loading of 5 wt%..
|
|
| 3. |
- Liu, Ya, 1991, et al.
(författare)
-
Surface modification of graphene for use as a structural Fortifier in water-borne epoxy coatings
- 2019
-
Ingår i: Coatings. - : MDPI AG. - 2079-6412. ; 9:11
-
Tidskriftsartikel (refereegranskat)abstract
- Graphene, the typical two-dimensional sp2 hybridized carbon allotrope, is widely used as a filler for improving the mechanical performance of polymers. However, its superhydrophobic surface makes it a big challenge to obtain stable graphene dispersions, especially in water-borne systems. On the contrary, graphene oxide (GO) shows excellent dispersibility in water, but strong oxidants and acids destroy its structure and degrade its mechanical properties. This largely limits its application in water-borne coatings. In this work, graphene from mechanical exfoliation was surface modified by p-aminophenol derived diazonium salt to achieve a homogenous dispersion. Moreover, the hydroxyl groups in p-aminophenol are able to combine with epoxy resins during the curing process to improve mechanical performance of the final coatings. The result shows that functionalized graphene shows a lower coefficient of friction and better abrasion resistance compared to GO.
|
|
| 4. |
- Liu, Ya, 1991, et al.
(författare)
-
Thermally Conductive and Electrically Insulating PVP/Boron Nitride Composite Films for Heat Spreader
- 2019
-
Ingår i: Proceedings - 2019 IMAPS Nordic Conference on Microelectronics Packaging, NORDPAC 2019. ; , s. 1-5
-
Konferensbidrag (refereegranskat)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.
|
|
| 5. |
- Liu, Ya, 1991, et al.
(författare)
-
Thermally Conductive and Electrically Insulating PVP/Boron Nitride Composite Films for Heat Spreader
- 2019
-
Ingår i: Advancing Microelectronics. - 2222-8748. ; 2019:NOR, s. 1-5
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 6. |
- Wang, Nan, et al.
(författare)
-
Highly thermal conductive and electrically insulated graphene based thermal interface material with long-term reliability
- 2019
-
Ingår i: Proceedings - Electronic Components and Technology Conference. - 0569-5503. ; 2019-May, s. 1564-1568
-
Konferensbidrag (refereegranskat)abstract
- High density packaging in combination with increased transistor integration inevitably leads to challenging power densities in terms of thermal management. The conventional TIMs that are widely used in the microelectronic industry today are experiencing more and more stress due to their limited thermal performance and poor reliability. Composed by particle laden polymer matrix, thermal conductivity (K) of conventional TIMs is generally limited to 5 W/mK, and such values can be even lower for electrically insulated TIMs. Conventional TIMs also suffer from severe pump-out and dry-out failures, which brought great threat to the performance and lifetime of the electronic devices. Here, we solve these problems by applying a novel highly thermal conductive, electrically insulated and reliable graphene based TIMs (I-GTs). Composed by vertical graphene structures, I-GTs provide a continuous heat pathway from top to bottom, which enables superfast heat dissipation at through-plane direction. The highest bulk through-plane thermal conductivity of the conductive body can reach up to 1000 W/mK, which is orders of magnitude higher than conventional TIMs, and even outperforms the pure indium TIMs by over ten times. The highly flexible and foldable nature of I-GT enables at least 100% compressibility upon small applied pressures. As excellent gap fillers, I-GT can provide complete physical contact between two surfaces and thereby minimize the contact resistance to heat flow. The measured minimum thermal resistance for I-GTs reaches about 30 Kmm2/W. Such values are significantly higher than the randomly dispersed composites presented above. To ensure fully electrical insulation, a smooth and soft adhesive layer with a thickness of few microns was coated on the surface of I-GT. The breakdown voltage of I-GT reaches up to 950 V. Thermal cycling test shows the highly stable nature of I-GT. The good compressibility and elasticity of I-GT ensures continued proper TIM contact with substrates, which counteracts the effect of internal stress induced by the mismatch of coefficient of thermal expansion (CTE) during temperature cycling. In addition, the I-GTs have the advantages of low density and good maintainability. The resulting I-GTs thus opens new opportunities for addressing large heat dissipation issues for form-factor driven electronics and other high power driven systems.
|
|
| 7. |
- Wang, Nan, et al.
(författare)
-
Highly Thermal Conductive and Light -weight Craphene-based Heatsink
- 2019
-
Ingår i: 2019 22ND EUROPEAN MICROELECTRONICS AND PACKAGING CONFERENCE & EXHIBITION (EMPC). - 2165-2341. - 9780956808660
-
Konferensbidrag (refereegranskat)abstract
- With the developing trend ofminiaturization and integration of modem electronic devices, commercial hearsinks ivaterigh, like copper and ii iv are facing mare and mare challenges, such as inefficient cooling performance, large size turd heavy weight. Here, we salve the probletn by developing a novel highly thermal conductive and 11Mo-weight graphene heatsink. Cornposed by vertically-aligned and continUOUS graphene structures, heat transport was highly efficiero from the base 1o fin Ii: ininside the heatsink, The maximum through-platre thermal catuluctivity ofgraphene heatsink can be up to 1000 1500 Ward( which is over 7 times higher than aluminum, and even outperforms copper about 4 times_ Gmphene heatsink demonstrated outstanding cooling perffrmance which wm superior to copper heatsink with the same dimension and same power input. Noticeably, the graphene hearsink also has anportant advantagas of light-weight and high emissions,. The measured density (1 1 g cmli is only onroeighth of copper and lam than hoor of aluminum and emissivity is about ten times hiher than pure rapper and aluminum. The resulting graphene heatsink thus opertS rim opportunities for addressing large heat dissMatMn issues in weight' driven electronics and othm high power smions.
|
|
| 8. |
- Zhang, Maomao, et al.
(författare)
-
Effect of pressure during graphitization on mechanical properties of graphene films
- 2019
-
Ingår i: 2019 20th International Conference on Electronic Packaging Technology, ICEPT 2019.
-
Konferensbidrag (refereegranskat)abstract
- Graphene films (GFs) can be used in the field of electronics cooling, owing to many outstanding properties. In the present paper, GFs samples were graphitized at different pressures to study their effect on the mechanical properties. The elastic modulus and hardness of GFs were measured by nanoindentation and the tensile strength of GFs were obtained by stretching GFs in a tensile tester. Meanwhile, GFs were characterized by X-ray diffraction(XRD), Scanning electron microscopy (SEM) and Raman spectroscopy. The results show that the modulus, hardness and tensile strength of GFs were strongly influenced by the defect and wrinkles among other things.
|
|
| 9. |
- Zhang, Q., et al.
(författare)
-
Effect of sintering method on properties of nanosilver paste
- 2017
-
Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2017, Goteborg, Sweden, 18-20 June 2017. ; , s. 186-189
-
Konferensbidrag (refereegranskat)abstract
- Nanoscale silver paste has a good application prospect in heat dissipation of high-power chips due to the characteristics of low temperature sintering and high temperature service. The properties of the nanosilver paste including thermal conductivity, electrical conductivity, and shear strength are affected greatly by the sintering process. The influence of different sintering methods on the performance of the nanosilver paste was studied in this article. The nanosilver paste with 80.5 wt% nano-scale silver particles, 1.5 wt% submicron-scale SiC particles with Ag coating, 0.9 wt% dispersion agent, 10 wt% organic carrier and 7.1 wt% diluting agent was sintered at 260°C for 30 min with three different methods, heating table sintering, heating furnace sintering, and mixed sintering. The samples obtained by mixed sintering process have higher thermal conductivity than the ones obtained by heating furnace sintering method and heating table sintering method. The effect of sintering methods on shear strength of nanosilver paste was also investigated subsequently. Shear testing equipment was used to measure the shear strength of the samples gained by heating table sintering, heating furnace sintering, and air dry oven sintering. The maximum shear strength was obtained for the samples by heating table sintering method. The shear strength of samples by air dry oven sintering method was the minimum one.
|
|
| 10. |
- Zhang, Q., et al.
(författare)
-
Mechanical property and reliability of bimodal nano-silver paste with Ag-coated SiC particles
- 2019
-
Ingår i: Soldering and Surface Mount Technology. - 1758-6836 .- 0954-0911. ; 31:4, s. 193-202
-
Tidskriftsartikel (refereegranskat)abstract
- © 2019, Emerald Publishing Limited. Purpose: This study aims to develop a bimodal nano-silver paste with improved mechanical property and reliability. Silicon carbide (SiC) particles coated with Ag were introduced in nano-silver paste to improve bonding strength between SiC and Ag particles and enhance high-temperature stability of bimodal nano-silver paste. The effect of sintering parameters such as sintering temperature, sintering time and the proportion of SiC particles on mechanical property and reliability of sintered bimodal nano-silver structure were investigated. Design/methodology/approach: Sandwich structures consist of dummy chips and copper substrates with nickel and silver coating bonded by nano-silver paste were designed for shear testing. Shear strength testing was conducted to study the influence of SiC particles proportions on the mechanical property of sintered nano-silver joints. The reliability of the bimodal nano-silver paste was evaluated experimentally by means of shear test for samples subjected to thermal aging test at 150°C and humidity and temperature testing at 85°C and 85 per cent RH, respectively. Findings: Shear strength was enhanced obviously with the increase of sintering temperature and sintering time. The maximum shear strength was achieved for nano-silver paste sintered at 260°C for 10 min. There was a negative correlation between the proportion of SiC particles and shear strength. After thermal aging testing and humidity and temperature testing for 240 h, the shear strength decreased a little. High-temperature stability and high-hydrothermal stability were improved by the addition of SiC particles. Originality/value: Submicron-scale SiC particles coated with Ag were used as alternative materials to replace part of nano-silver particles to prepare bimodal nano-silver paste due to its high thermal conductivity and excellent mechanical property.
|
|
