共查询到20条相似文献,搜索用时 9 毫秒
1.
A novel structure of woven continuous-carbon fiber composites with high electromagnetic shielding 总被引:5,自引:0,他引:5
Wern Shiarng Jou 《Journal of Electronic Materials》2004,33(3):162-170
A novel structure employing the woven continuous-carbon fiber (CCF) epoxy composite with high electromagnetic (EM) shielding
is presented experimentally and theoretically. The influences of weave type, number, and angle of overlapped plates upon the
shielding effectiveness (SE) of the woven CCF-epoxy composite are investigated. The minimum SE of the single, double, and
triple-plain or balanced-twill woven CCF-composite plates was measured to be as high as 50 dB, 60 dB, and 70 dB, respectively.
More than 100 dB in SE was obtained for the triple-overlapped, plain-weave CCF composite at a frequency of 0.9 GHz. The weight
percentage of the single CCF-composite plate required for electronic application is 4.8% only, which is less than one quarter
of the CF content, and the performance in SE is 10 dB higher in comparison with long, CF-filled, liquid-crystal polymer (LCP)
composites. The SE calculated theoretically is consistent with that measured by the experiment. 相似文献
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Lingbo Zhu Jianwen Xu Yonghao Xiu Dennis W. Hess C. P. Wong 《Journal of Electronic Materials》2006,35(2):195-199
The remarkable properties of carbon nanotubes (CNTs) make them attractive for microelectronic applications, especially for
interconnects and nanoscale devices. In this paper, we report an efficient process to grow well-aligned CNT films and high-aspect-ratio
CNT arrays with very high area distribution density (>1600 μm−2). Chemical vapor deposition (CVD) was invoked to deposit highly aligned CNTs on Al2O3/Fe coated silicon substrates of several square centimeter area using ethylene as the carbon source, and argon and hydrogen
as carrier gases. The nanotubes grew at a high rate of ∼100 μm/min. for nanotube films at 800°C, while the nanotube arrays
grew at ∼140 μm/min. even at 750°C, due to the base growth mode. The CNTs were characterized by transmission electron microscopy
(TEM), scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS). The results demonstrated that the CNTs
are of high purity and form densely aligned arrays with controllable size and height. The as-grown CNT structures have considerable
potential for thermal management and electrical interconnects for microelectronic devices. 相似文献
4.
Nickel filament polymer-matrix composites with low surface impedance and high electromagnetic interference shielding effectiveness 总被引:1,自引:0,他引:1
The processing of nickel filaments of 0.4 Μm diameter gives polyethersulfone-matrix composites with high electromagnetic interference
shielding effectiveness, high reflection coefficient and low surface impedance at 1-2 GHz. With 7 vol.% nickel filaments,
the composite exhibited shielding effectiveness 87 dB (compared to 90 dB for solid copper), surface impedance 1.2 Ω (same
as for solid copper), tensile strength 52 MPa, modulus 5 GPa, ductility 1.0%, and density 1.87 g/cm3. 相似文献
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通过光刻掩膜技术、电阻热蒸发沉积技术制备电磁屏蔽窗口金属网栅薄膜,研究金属网栅的红外透射率和电磁屏蔽效能。为了能有效地屏蔽电磁波,使用CST Studio Suite电磁仿真软件设计不同周期、线宽的金属网栅,采用光刻掩膜技术、电阻热蒸发技术在双面抛光单晶硅基片上完成线宽为30μm,周期分别为350μm、450μm、550μm、650μm、750μm的金属网栅薄膜的制备。采用真空型傅立叶红外光谱仪和矢量网络分析仪分别对不同结构参数金属网栅薄膜的光谱特性和电磁屏蔽效能进行测试。结果:实现在双面抛光单晶硅基底上制备的网栅在12~18 GHz频段内,网栅的电磁屏蔽效能均达到12 dB以上。在3~5μm波段的透射率损失仅为8%。为了得到既具有高透光率,又具有强电磁屏蔽效能金属网栅薄膜需要合理设计金属网栅的线宽和周期。制备过程中网栅的光学-电学特性不仅受周期和线宽影响,掩膜板的加工精度、金属网栅的加工缺陷等也会造成不同程度的影响。 相似文献
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Electromagnetic shielding of nylon-66 composites applied to laser modules was studied experimentally and theoretically. The
effects of conductive carbon fiber length and weight percentage upon the shielding effectiveness (SE) of nylon composites
were investigated. The SE of long carbon fiber filled nylon-66 composites was found to be higher than short carbon fiber composites
under the same weight percentage of carbon fibers. In addition, higher electromagnetic shielding was obtained for the composite
with higher carbon fibers contents at the same length. The SE of conductive carbon fiber filled nylon-66 composites was measured
to be 42 dB at a low frequency of 30 MHz and 50 dB at a high frequency of 1 GHz. The SE predicted by theoretical models and
measured by experiments were in good agreement for filled nylon-66 composites with different length fiber. 相似文献
9.
The influence of fiber orientation on electromagnetic shielding in liquid-crystal polymers 总被引:3,自引:0,他引:3
The influence of conductive carbon-fiber orientation and weight percentage on the electromagnetic (EM) shielding effectiveness
(SE) in liquid-crystal polymer (LCP) composites was investigated experimentally and theoretically. The experimental results
show that the SE of LCP composites with longitudinal fiber orientation is higher than random fiber orientation under the same
weight percentage of carbon fibers filled. This is because longitudinal fiber orientation is parallel to the electric field
of the incident EM wave, and most of the energy of the incident wave is reflected by the longitudinal fiber. In comparison
with nylon66 composites, the SEs of LCP composites with longitudinal fiber orientation are also higher than nylon66 composites
with the same content of carbon fibers. Furthermore, the SE of 20% conductive carbon-fiber-filled LCP composites was measured
to be 50 dB at a frequency of 0.3 GHz and 53 dB at 1 GHz, which is at least 10 dB higher than that of nylon66 composites.
The SE predicted by theoretical models and measured by experiments was in good agreement for carbon-fiber-filled LCP composites
of longitudinal and random fiber orientations. 相似文献
10.
近年来,随着电力电子技术与电气自动化技术的迅速发展,电磁环境日渐复杂,电子设备间的相互干扰日益严重,电磁兼容问题成为不容忽视的重要课题。为保证设备不受外界的电磁干扰,通常对设备外部加上金属屏蔽机箱,而由于需要散热、通风等因素的存在,不可避免需要在机箱上开孔开缝。外部的电磁干扰信号通过这些孔缝进入机箱内部,影响机箱正常工作。利用波导等效电路,计算了带有中心孔的矩形金属屏蔽体的屏蔽效能,并对孔的形状、矩形孔的长宽比以及入射波极化方向等参数对屏蔽效能的影响进行了讨论。另外,进一步研究了含有孔阵矩形金属机箱的屏蔽效能,并对电子机箱的电磁兼容性设计提出改进措施。最后利用Ansoft HFSS仿真软件验证模型的有效性和算法的正确性。 相似文献
11.
L. Chico 《Microelectronics Journal》2004,35(1):3-5
We have investigated the properties of purely metallic carbon nanotube systems made of a nanometer-size metallic island connected to another two metallic carbon nanotubes by means of topological defects. These structures present discrete energy levels, thus behaving as metallic quantum dots. When there is a symmetry gap between the matched tubes around the Fermi energy, the states are strongly localized in the central metallic section and completely uncoupled from the external nanotubes. Interestingly, we also find discrete states in structures made of metallic nanotubes without a common symmetry. In this case the states are actually resonances coupled to the leads continua. 相似文献
12.
A novel multilevel resistive switching was observed in epoxy methacrylate resin (EMAR) and carbon nanotubes (CNTs) composite films fabricated by spin coating method. The fabricated devices demonstrated the rewritable nonvolatile memory characteristics. More significantly, the memory device based on EMAR+CNTs composite exhibits multilevel stable conductivity states with stable intermediate resistance states in response to the applied voltage. By setting different compliance current and content of CNTs in composite film, the multilevel ON-states and even the multilevel OFF-states have been observed in our memory device. As fabricated devices exhibited multilevel resistive switching with stable resistance ratio between different resistance states having good data retention and endurance characteristics. It offers a novel design strategy for solution processable multilevel data storage. 相似文献
13.
Zhijiang Ye Dongjin Lee Stephen A. CampbellTianhong Cui 《Microelectronic Engineering》2011,88(9):2919-2923
We present thermally enhanced single-walled carbon nanotube (SWCNT) horizontal alignment on a wafer scale level that enhances the device performance with a possibility of mass production. The SWCNT dispersion is evaporated on the heated and tilted open microfluidic channel template of photoresist. Scanning electron microscopy demonstrates well-aligned SWCNTs qualitatively and G-band to D-band (G/D) ratio in Raman spectra indicates the degree of alignment quantitatively. The effect of temperature, fluidic channel dimension, concentration of SWCNT dispersion and wetting properties on the alignment is investigated, resulting in G/D ratio of up to 30. 相似文献
14.
A procedure for producing arrays of self-aligned carbon nanotubes (CNTs) using standard chemical vapor deposition (CVD) is
reported. Using UV photolithography, silicon substrates are patterned with a thin layer of thermally evaporated iron as a
CNT catalyst. The CVD synthesis was carried out over a small temperature range (700°C–800°C) using acetylene and methane gasses,
producing aligned CNT towers. Scanning electron microscopy (SEM) analysis shows a relationship between CNT tower height and
synthesis time. Additionally, results show that impurity particles dramatically effect CNT tower growth. These results indicate
that aligned CNTs can be produced in a desired pattern with height control. 相似文献
15.
Feng Xu Wen Qing Zhu Long YanHong Xu Ling Hao Xiong Jia Heng Li 《Organic Electronics》2012,13(2):302-308
Commercially-available single walled carbon nanotubes (SWCNTs) were used to fabricate SWCNT sheets for anodes of organic light-emitting diodes (OLEDs) by spray-coating process without any use of surfactant or acid treatment. A layer of DMSO doped PEDOT:PSS was spray-coated on the SWCNT sheets to not only lessen the surface roughness to an acceptable level, but also improve the conductivity by more than three orders of magnitude. For our SWCNT-based OLEDs of tris-(8-hydroxquinoline) aluminum (Alq3) emission layers, a maximum luminance 4224 cd/m2 and current efficiency 3.12 cd/A were achieved, which is close to the efficiency of ITO-based OLEDs. We further found out that our OLEDs based on the PEDOT:PSS covered SWCNT anodes tripled the contrast ratio of the conventional indium tin oxide (ITO) based OLEDs. 相似文献
16.
Kunmo Chu Dong-Jin YunDongouk Kim Hyokeun ParkSung-Hoon Park 《Organic Electronics》2014,15(11):2734-2741
Carbon nanotube (CNT) composites are ideal materials for electric heating (E-heating) components owing to their lightweight, rapid heating ability, and easy processability for microscale patterns. However, careful consideration of their thermal stability and the effect of E-heating on CNT composites is necessary to ensure safety and long-term durability. Thermal degradation of CNT composites as a result of E-heating was found to be much more severe than air convection heating (C-heating). Enhanced mechanical properties of CNT composite were observed after 40 h C-heating, while E-heating composites became fragile that the matrix was severely damaged at the same temperature/hours. Consequently, the electrical resistance of the CNT composite for E-heating was dramatically increased. To avoid thermal degradation and a dramatic increase in resistance, the E-heating temperature should be much lower than the temperature limit of thermally stable polymer. In addition, thermal degradation of the polymer matrix could be relieved through the addition of CNTs, which can be understood as parallel resistor model, by spreading thermal concentration throughout the polymer matrix. 相似文献
17.
Nicolo’ Chiodarelli Yunlong LiDaire J. Cott Sofie MertensNick Peys Marc Heyns Stefan De Gendt Guido Groeseneken Philippe M. Vereecken 《Microelectronic Engineering》2011,88(5):837-843
Carbon nanotubes (CNTs) are considered a promising material for interconnects in the future generations of microchips because of their low electrical resistance and excellent mechanical stability. In particular, CNT-based contacts appear advantageous when compared with current tungsten or copper technologies and could therefore find an application as metal contacts interconnecting the transistors with the back end of line of the microchip. In this work, the integration of vertical CNT bundles in sub-micron contact holes is evaluated at wafer scale and the major integration challenges encountered in the practical realization of the process are discussed. Nickel PVD films were used to selectively grow CNT into the contact holes at temperatures as low as 400 °C, which is the thermal budget available for contacts. The height of the contacts and the length of the CNT are controlled by a chemical mechanical polishing step (CMP) after embedding the CNT into SiO2. Ti/Au metal pads are then formed onto the CNT bundles by PVD and lift-off. The integrated CNT are electrically characterized and an annealing treatment was found to improve the CNT-via resistance. As the electrical properties of the CNT can be evaluated, the structure and the process presented constitute a test vehicle for the development of high-quality CNT-contacts. 相似文献
18.
为了提高设备中电子元件抵御来自外界和内部其他元件的电磁干扰,根据传输线理论,将双层加载电路板屏蔽腔体模型转换为电路图,利用电路图推导出腔体中心屏蔽效能的等效公式。利用Matlab生成传输线法屏蔽效能曲线,并通过仿真软件CST建模仿真,仿真结果与Matlab输出曲线良好吻合,验证了公式的正确性。运用CST研究了一些因素如电路板大小、数量、放置方式以及距孔缝的距离对屏蔽效能的影响。为了更加贴合实际,采用加载集成运算放大电路的印制电路板来研究腔体屏蔽效能以及腔体对电路板功能的影响,最后提出了一些提高屏蔽效能的方法。 相似文献
19.
Flexible electrodes of ternary composites, in which highly conductive carbon nanotube films (CNFs) are coated with carbon nanotube-doped graphene oxide/polypyrrole (CNT-GO/PPy), have been fabricated via facile electrochemical synthesis. Long and short CNTs are separately doped into the composites (lCNT-GO/PPy and sCNT-GO/PPy) and their electrochemical performances are compared. Electrochemical measurements indicate that the doping of CNTs in the composites significantly improves the electrochemical behaviors of the GO/PPy electrodes. Notably, the lCNT-GO/PPy electrodes show superior electrochemical properties with respect to the sCNT-GO/PPy electrodes, which is related to the introduction of abundant CNTs in the former electrodes and their special microstructures. Two symmetric electrodes with the lCNT-GO/PPy composites coated on CNFs are assembled to fabricate a solid-state supercapacitor device, which features lightweight, ultrathinness, and high flexibility. The device achieves a high areal and volumetric specific capacitance of 70.0 mF cm−2 at 10 mV s−1 and 6.3 F cm−3 at 0.043 A cm−3, respectively. It also shows superior rate performance and cycle stability, with a capacitance retention rate of 87.7% for 10,000 cycles. The supercapacitor device fabricated is promising for the use in lightweight and flexible integrated electronics. 相似文献
20.
Short nickel filaments of diam 0.4 μm and containing 94 vol% Ni and 6 vol% C were fabricated by electroplating with nickel
0.1 μm diam catalytically grown carbon filaments. The use of these filaments in polyether sulfone in amounts of 3, 7,13, and
19 vol% gave composites with electromagnetic interference shielding effectiveness at 1–2 GHz of 42,87,84, and 92 dB, respectively,
compared to a value of 90 dB for solid copper. Less shielding was attained when 0.1 μm diam carbon filaments or 2 or 20 μm
diam nickel fibers were used instead. 相似文献