| 1. |
- Chen, S., et al.
(författare)
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An overview of carbon nanotubes based interconnects for microelectronic packaging
- 2017
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Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2017, Goteborg, Sweden, 18-20 June 2017. - 9781538630556 ; , s. 113-119
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Konferensbidrag (refereegranskat)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.
(författare)
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Graphene-CNT hybrid material as potential thermal solution in electronics applications
- 2017
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Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging (NordPac). - 9781538630556 ; , s. 190-193
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Konferensbidrag (refereegranskat)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. |
- Gutierrez, Martí, 1993, et al.
(författare)
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Sintering of SiC enhanced copper paste for high power applications
- 2017
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Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging (NordPac). - 9781538630556 ; , s. 151-156
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Konferensbidrag (refereegranskat)abstract
- In this work a Cu paste consisting in both micro and nanoparticles was produced. The copper paste was produced with different additive weight percentages of Ag coated SiC and sintered for 30min at 500°C under 6,5MPa in N2 atmosphere. The thermal resistance and composition of the resulting joints was studied. XPS and EDX measurements show no significant oxidation of the Cu after sintering, which is attributed to the combination of reductive agents in the paste and the inert atmosphere. SEM images of cross sections show contacts with no voids between the SiC particles and the copper matrix. Thermal conductivity measurements with laser flash analysis (LFA) show that the additive increases the effective thermal conductivity to more than double of that of the pure copper paste at 2% additive weight percentage, but bigger amounts yield smaller improvements and presumably would eventually worsen it.
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| 4. |
- Hansson, Josef, 1991, et al.
(författare)
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Fabrication and characterization of a carbon fiber solder composite thermal interface material
- 2017
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Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging (NordPac). - 9781538630556 ; , s. 97-100
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Konferensbidrag (refereegranskat)abstract
- One of the significant bottlenecks in thermal management is to develop thermal interface materials (TIMs) with lower thermal interface resistance while retaining good reliability, mechanical properties and handling capabilities. Recently, the combination of electrospun polymer fibers and solder matrix has gathered interest, combining the excellent thermal properties of metal with the mechanical properties of polymers. Carbon fibers are increasingly common as reinforcement in composites, owing to their high strength and thermal conductivity. Utilizing carbon fibers in a similar composite could allow for the fabrication of TIMs with so far unexplored properties such as increased thermal conductivity, strength and tunable CTE. In this work, we have fabricated and characterized a TIM based on a carbon fiber network infiltrated by an alloy of Sn-Ag-Cu, (CF-TIM). Commercially available carbon fibers are coated with a thin layer of Ag and infiltrated by molten alloy under high pressure. The result is a preform TIM, easy to handle and compatible with standard SMT assembly. A thermal interface resistance lower than 2 Kmm2/W between two ENIG coated Cu substrates was measured with laser flash. Comparing total thermal interface resistance to bond line thickness indicates a very low contact resistance consistent with good metallurgical bonding and a bulk thermal conductivity of 24 W/mK for the TIM. X-ray inspection and SEM of cross section of the assembled structure indicates good adhesion between fiber and matrix, and a very low degree of voiding. To demonstrate the handling capabilities of CF-TIM, a variety of reflow conditions were investigated. A consistent bond line thickness (BLT) of 45±5μm was achieved independent on applied pressure during reflow, and decreased less than 20% after 10 additional reflow cycles, without additional material leakage. This demonstrates the possibility of CF-TIM use in assembly line processes requiring additional reflow steps. Solder preforms are common in industry, and due to similar handling characteristics of the CF-TIM, it should be easily integrated into existing electronics assembly lines. The usage of commercial fibers not reliant on slow and expensive processes such as electrospinning further opens up the potential for mass production.
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| 5. |
- Hassona, Ahmed Adel, 1988, et al.
(författare)
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D-band Waveguide Transition Based on Linearly Tapered Slot Antenna
- 2017
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Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging (NordPac). - 9781538630556 ; , s. 64-67
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Konferensbidrag (refereegranskat)abstract
- In this work, an on-chip Monolithic Microwave Integrated Circuit (MMIC) to waveguide transition is realized based on Linearly Tapered Slot antenna (LTSA) structure. The antenna is implemented on a 50-um-thick Gallium Arsenide (GaAs) substrate and placed in the E-plane of an air-filled D-band waveguide. The transition shows a maximum insertion loss of 1 dB across the frequency range 110-170 GHz. The average return loss of the transition is -15 dB and the minimum is -9 dB. The structure occupies an area of 0.82x0.6 mm2. The transition provides low-loss wide-band connectivity for millimeter-wave systems and addresses integration challenges facing systems operating beyond 100 GHz.
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| 6. |
- Huang, S., et al.
(författare)
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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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Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2017, Goteborg, Sweden, 18-20 June 2017. - 9781538630556 ; , s. 143-146
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Konferensbidrag (refereegranskat)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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| 7. |
- NYLANDER, ANDREAS, 1988, et al.
(författare)
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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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Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging (NordPac). - 9781538630556 ; , s. 175-181
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Konferensbidrag (refereegranskat)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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| 8. |
- Satwara, Maulik, 1990, et al.
(författare)
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Finite element analysis of bond line thickness and fiber distribution in solder based thermal interface materials
- 2017
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Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2017, Goteborg, Sweden, 18-20 June 2017. - 9781538630556 ; , s. 167-171
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Konferensbidrag (refereegranskat)abstract
- As microelectronic devices continue to decrease in size, failure of these devices is commonly attributed to ineffectual thermal management. Hence, increased thermal failures at elevated temperature has accounted for some of their reliability concerns and expected to be a major bottleneck for future development of microelectronics. For the thermal management, solder based materials give a better performance as thermal interface materials (TIM). However, these materials have a marginal reliability due to their higher Young's modulus. Therefore new type of solder based nano polymer composite (SMNPC) material is introduced. The SMNPC is composed of Sn-Ag-Cu (SAC) infiltrated through a silver coated PA6, 6 polymer fiber mesh to address electrical, thermal and mechanical challenges. In this work, finite element modeling was employed to investigate the thermal and mechanical properties of the composite material by varying polymer distribution, total volume of polymer and bond fine thickness (BLT). The composite is demonstrated to possess high heat transfer capability and lower elastic modulus as shown in Figure 1. All the results demonstrate that the developed SMNPC is proved a good alternative for conventional TIMs to improve thermal and mechanical properties.
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| 9. |
- Shi, Yuqing, et al.
(författare)
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Fabrication and characterization of graphene based film
- 2017
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Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2017, Goteborg, Sweden, 18-20 June 2017. - 9781538630556 ; , s. 162-166
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Konferensbidrag (refereegranskat)abstract
- Large area, freestanding graphene papers fabricated from 2D graphene nanosheets with optimized microstructure, graphene sheet alignment and superior properties have a wide range of functional applications. In this paper, we propose a novel approach to fabricate graphene film by Electro-spray deposition (ESD), which is considered as the preparation for a roll-to-roll industrial production of the further. Expanded graphite, as the raw materials, was dispersed into N-Methyl-2-pyrrolidone (NMP) which is used as the feeding solution for ESD. It is also shown that high-shear mixing and high ultra-sonication of graphite powder in NMP solvent result in large-scale exfoliation, giving good dispersions of graphene nanosheets. The fabrication of the film with different thicknesses is based on ESD onto the surface of a heated aluminum foil at around 140°C. Brunauer-Emmett-Teller method is used to test the surface area of raw material, which has been reported to reach 1200 m2/g. Raman spectroscopy and scanning electron microscope (SEM) are used to characterize the microstructure and morphology of the film, contributing to the optimization of electrospray's parameters. Joule heating was utilized to quantify thermal conductivity of the film.
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| 10. |
- Yang, Y., et al.
(författare)
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Heat dissipation performance of graphene enhanced electrically conductive adhesive for electronic packaging
- 2017
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Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2017, Goteborg, Sweden, 18-20 June 2017. - 9781538630556 ; , s. 125-128
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Konferensbidrag (refereegranskat)abstract
- Electrically conductive adhesive is a new type of environmentally interconnect material which can be used in electronic packaging to replace the traditional solders due to its advantages of simple applying process and low curing temperature. Silver coated graphene is employed in this work to enhance the thermal conductivity of the current commercial electrically conductive adhesive with very low thermal conductivity. Thermal conductivity of the electrically conductive adhesive was measured by laser flash thermal analyzer. The infrared thermal imager was utilized to obtain the temperature distribution of chip surface. The results indicated that the developed graphene enhanced electrically conductive adhesive has perfect heat performances. It can be believed that this new kind of electrically conductive adhesive possesses promising application in electronic packaging in the future.
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