| 1. |
- Chen, S., et al.
(author)
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An overview of carbon nanotubes based interconnects for microelectronic packaging
- 2017
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In: 2017 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2017, Goteborg, Sweden, 18-20 June 2017. - 9781538630556 ; , s. 113-119
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Conference paper (peer-reviewed)abstract
- Owing to the great demand in more functions and miniaturization in microelectronic packaging, the dimensions of interconnects has decreased extremely, which has resulted in electrical, thermal, and mechanical reliability issues. To address these issues, carbon nanotube (CNT) has been selected as a promising alternative material for the interconnects in packaging due to its large current density, high thermal conductivity, great flexibility, and low coefficient of thermal expansion (CTE). In this paper, the development of CNTs based vertical interconnects was reviewed. However, the resistivity of CNTs based interconnects was much higher than that of copper interconnects. Thus, this review focused on the resistivity of CNTs-based interconnects in different fabrication process and pointed out what improves the resistivity. In the future, CNTs-Cu nanocomposite with unique properties could be the suitable material for bumps to reduce the resistivity of CNTs based bumps further.
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| 2. |
- Darmawan, C. C., et al.
(author)
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Graphene-CNT hybrid material as potential thermal solution in electronics applications
- 2017
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In: 2017 IMAPS Nordic Conference on Microelectronics Packaging (NordPac). - 9781538630556 ; , s. 190-193
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Conference paper (peer-reviewed)abstract
- Graphene and CNT have great potential in electronics applications. This work explored the possibility of integrating 1D CNT and 2D graphene into a 3D covalently bonded structure, i.e. a graphene-CNT hybrid material for thermal management application. The graphene-CNT hybrid material was later investigated morphologically and thermally to observe its heat dissipation capability.
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| 3. |
- Huang, S., et al.
(author)
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Improved reliability of electrically conductive adhesives joints on Cu-Plated PCB substrate enhanced by graphene protection barrier
- 2017
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In: 2017 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2017, Goteborg, Sweden, 18-20 June 2017. - 9781538630556 ; , s. 143-146
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Conference paper (peer-reviewed)abstract
- Graphene protection barrier was introduced to the interface between the ECAs and Cu-plated wire to enhance the reliability of the ECAs joints on Cu-Plated PCB substrate due to its excellent properties of impermeability to all gases/salts as well as its thermal/chemical stability. The results of shear test indicated graphene protection barrier can improve the shear strength of the ECAs joints on Cu-plated PCB substrate by almost 22% after 500 hours high temperature and high humidity cyclic test. Characterizations by optical microscope and XPS were further performed to explain the mechanism. To sum up, it can be believed that the graphene protection barrier can dramatically enhance the reliability of the ECAs joints on Cu-Plated PCB substrate.
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| 4. |
- Jiang, Di, 1983, et al.
(author)
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A flexible and stackable 3D interconnect system using growth-engineered carbon nanotube scaffolds
- 2017
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In: Flexible and Printed Electronics. - : IOP Publishing. - 2058-8585. ; 2:2
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Journal article (peer-reviewed)abstract
- One of the critical challenges for realizing flexible electronic systems for a wide range of applications is the development of materials for flexible and stackable interconnects. We propose and demonstrate a three-dimensional (3D)interconnect structure embedded in a polymeric substrate using metal-coated carbon nanotube (CNT)scaffolds. By using two different underlayer materials for the catalyst, onestep synthesis of a dual-height CNT interconnect scaffold was realized. The CNT scaffolds serve as flexible cores for both annular metal through-substrate-vias and for horizontal metal interconnect. The 3D-CNT network was fabricated on a silicon substrate, and once the scaffolds were covered by metal, they were embedded in a polymer serving as a flexible substrate after peel-off from the silicon substrate. The 3D-CNT interconnect network was exposed to mechanical bending and stretching tests while monitoring its electrical properties. Even after 300 cycles no significant increase of resistances was found. Electrically there is a trade-off between flexibility and conductivity due to the surface roughness of the scaffold. However, this is to some extent alleviated by the metalized sidewalls giving the horizontal wires a cross-sectional area larger than indicated by their footprint. For gold wires 200 nm thick, measurements indicated a resistivity of 18 μΩ.cm, a value less than one order of magnitude larger than that of bulk gold, and a value that is expected to improve as technology improves. The mechanical properties of the metalized scaffolds were simulated using a finite element model. The potential scale-up capability of the proposed 3D-CNT network was demonstrated by the stacking of two such polymer-embedded interconnect systems.
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| 5. |
- NYLANDER, ANDREAS, 1988, et al.
(author)
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Current status and progress of organic functionalization of CNT based thermal interface materials for electronics cooling applications
- 2017
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In: 2017 IMAPS Nordic Conference on Microelectronics Packaging (NordPac). - 9781538630556 ; , s. 175-181
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Conference paper (peer-reviewed)abstract
- The development of integrated circuitry has resulted in cheaper and more efficient computers being available every year. Unfortunately, this development comes at the expense of an exponential increase of power density that scales with miniaturisation of transistors. To counteract the hot spot issue that arises and results in poor reliability and reduced lifetime of microsystems, thermal interface materials (TIMs) can be used. TIMs play a key role in thermal management of microsystems by providing efficient thermal pathways between surfaces. Vertically aligned carbon nanotubes (CNT) have been suggested as a potential material for such TIM applications due to the combination of their high thermal conductivity, which has been reported to reach over 3000 W/mK, and unique mechanical properties. However, due to the poor interaction between individual CNT strands and the contact surface, large contact resistances are commonly measured in these interfaces. One solution to this issue is to anchor the CNT by covalent bonding using chemical functionalization which allows phonon propagation through the interface. In this paper various chemical functionalization solutions from recent literature for CNT in TIM applications will be summarized. By comparing the results from these studies to other TIM systems, CNT array based TIM hold some promise with thermal interface resistance values reaching as low as 0.6mm2K/W. However, experimental results regarding the reliability of these solutions are still uncommon and should be a suitable area for further investigations.
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| 6. |
- Sun, Jie, 1977, et al.
(author)
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Synthesis Methods of Two-Dimensional MoS2: A Brief Review
- 2017
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In: Crystals. - : MDPI AG. - 2073-4352. ; 7:7, s. Article no 198 -
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Research review (peer-reviewed)abstract
- Molybdenum disulfide (MoS2) is one of the most important two-dimensional materials after graphene. Monolayer MoS2 has a direct bandgap (1.9 eV) and is potentially suitable for post-silicon electronics. Among all atomically thin semiconductors, MoS2's synthesis techniques are more developed. Here, we review the recent developments in the synthesis of hexagonal MoS2, where they are categorized into top-down and bottom-up approaches. Micromechanical exfoliation is convenient for beginners and basic research. Liquid phase exfoliation and solutions for chemical processes are cheap and suitable for large-scale production; yielding materials mostly in powders with different shapes, sizes and layer numbers. MoS2 films on a substrate targeting high-end nanoelectronic applications can be produced by chemical vapor deposition, compatible with the semiconductor industry. Usually, metal catalysts are unnecessary. Unlike graphene, the transfer of atomic layers is omitted. We especially emphasize the recent advances in metalorganic chemical vapor deposition and atomic layer deposition, where gaseous precursors are used. These processes grow MoS2 with the smallest building-blocks, naturally promising higher quality and controllability. Most likely, this will be an important direction in the field. Nevertheless, today none of those methods reproducibly produces MoS2 with competitive quality. There is a long way to go for MoS2 in real-life electronic device applications.
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| 7. |
- Zhang, Yong, 1982, et al.
(author)
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Chemical vapor deposition grown graphene on Cu-Pt alloys
- 2017
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In: Materials Letters. - : Elsevier BV. - 1873-4979 .- 0167-577X. ; 193, s. 255-258
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Journal article (peer-reviewed)abstract
- In this letter, the results from a series of experiments where graphene was grown on copper-platinum (Cu-Pt) alloy foils by chemical vapor deposition (CVD) are presented. By using Raman spectroscopy to analyze graphene films grown on Pt-Cu alloy foils with different Cu/Pt weight ratios (75/25, 50/50 and 25/75), we could show how the Cu/Pt weight ratio affected both the quality and the number of layers in the as-synthesized graphene films. Furthermore, graphene growth was shown to occur at temperatures as low as 750 °C due to what we believe is the strong catalytic ability of the Cu-Pt alloy foils. By keeping the flow rate of the CH4 precursor gas as low as 1.5 sccm, a low growth rate was obtained where the growth rates of monolayer and bilayer graphene could be controlled by simply adjusting the growth time.
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