替代屏蔽罩金属盖的电磁屏蔽胶带性能研究

介绍一种填充了特殊导电粒子的电磁屏蔽胶带,试验结果表明,它具有优异的粘接性能、导电性能、从型性以及良好的屏蔽效能,并从电磁屏蔽原理和应用要求出发,探讨了电磁屏蔽胶带替代传统金属屏蔽罩金属盖的可能,从而实现电子产品轻薄化.     

纳米聚苯胺-镀镍碳纤维复合材料屏蔽/吸波性能

以T300碳纤维经超声波化学镀镍制成的导电镀镍碳纤维作为电磁屏蔽体,以在丁醇/水溶液体系中采用界面聚合法制备的纳米结构聚苯胺为吸波体,与环氧乙烯基酯树脂复合,制得兼具电磁屏蔽与吸波功能的电磁防护碳纤维复合材料,研究了它的力学性能、电磁屏蔽性能、吸波性能、微观形貌等。结果表明:控制碳纤维化学镀镍的施镀时间、纳米结构聚苯胺的用量,可得到具有良好力学性能、电磁屏蔽性能、吸波性能的电磁防护碳纤维复合材料。当化学镀镍的施镀时间为20 min、纳米结构聚苯胺的用量为3.5wt%时,复合材料的拉伸强度为894.3 MPa,屏蔽效能为43~72 d B(10 k Hz^4 GHz),在10.77~18 GHz范围内,反射率≤-10 d B,峰值-23.2 d B(13.62 GHz)。     

机柜布局对方舱屏蔽效能影响的研究

电磁屏蔽方舱作为机动式指挥系统的车载运行环境,内有多种电子设备。为了保障舱内的电磁环境满足电子设备正常工作的需要,方舱必须具有良好的电磁屏蔽性能。方舱内的机柜布局是影响电磁屏蔽方舱屏蔽效能的一个重要因素。通过对电磁屏蔽方舱屏蔽效能的测试分析和CST仿真分析,定量分析了机柜布局对电磁屏蔽方舱屏蔽效能的影响,并对机柜的布局...     

炭黑填充丁苯/天然橡胶的电磁屏蔽性能

研究炭黑分别填充丁苯橡胶和丁苯/天然（50：50）并用橡胶的力学性能、导电性能和电磁屏蔽效能。对比发现,单组分丁苯橡胶体系的硬度、拉伸和撕裂性能均小于丁苯/天然橡胶并用体系。由于炭黑在并用体系中分布偏聚,体系的导电渗流阈值降低,相同炭黑含量时并用体系样品的体电阻率变小,电磁屏蔽效能增大。采用并用橡胶体系是减小复合材料导电渗流阈值,改善其力学性能的有效方法。     

降低感性网栅膜表面电阻的方法

在线宽、周期不变(相同透光率)的前提下,增加网栅厚度才能降低网栅的表面电阻,从而进一步提高球面网栅的电磁屏蔽性能。首先推导了网栅厚度、表面电阻和电磁屏蔽效能之间的数学关系,接着开展了膜层增厚的化学镀镍工艺实验。实验结果表明:球面铜网栅上可以得到厚度均匀、结合力牢固的镍磷合金镀层,面电阻由50Ω降至15Ω。经天线法测试,在200 MHz～18 GHz波段,镀镍球面金属网栅膜屏蔽效能平均达到46 dB,比未镀镍前平均提高了8 dB,而球面网栅试件镀镍前后,在400～900 nm波段透过率均为88%。镀镍前后透过率基本相同时,镀后表面电阻迅速降低,电磁屏蔽效能得到了显著提高。     

紫外光固化电磁屏蔽涂料的特性研究

以镀银铜粉为导电填料,以聚氨酯丙烯酸酯UV光固化树脂为基体材料,研制了UV光固化电磁屏蔽导电涂料。测试结果表明:该涂料的导电性能不但与填料含量、引发剂种类和含量有关,而且随涂层厚度的增强其电磁屏蔽效能增大。     

电镀废液回收铜粉的化学镀银工艺及其电磁屏蔽性能

采用高频超声脉冲电解法从电镀铜废液中回收制备枝晶状的铜粉,并在铜粉表面进行化学镀银以制备电磁屏蔽用银包铜粉,采用SEM、EDS、XRD、TEM等对其进行形貌和组分分析,研究了银包铜粉复合涂层的导电性能和电磁屏蔽性能。结果表明,经过表面化学镀银可以有效地避免铜粉的氧化;涂层的电磁屏蔽性能与银包铜粉的添加量紧密相关,当涂层中银包铜粉质量分数为60%时,其电磁屏蔽效率高达52 dB。     

后段无压力约束硫化工艺对导电橡胶性能的影响

导电橡胶硫化工艺会影响其性能。为了进一步优化导电橡胶的性能,系统研究了后段无压力约束硫化工艺对导电橡胶导电性能、交联密度、电磁屏蔽效能和力学性能的影响。结果表明:后段无压力约束硫化工艺可明显增加导电橡胶交联密度,从而减缓硅橡胶基体的老化,由此提高其导电和电磁屏蔽的稳定性,使其电磁屏蔽效能在750 kHz~3 GHz频段内较长时间保持在100 dB以上;尽管该工艺会使导电橡胶的硬度明显增加,柔性降低,但其仍可满足使用要求。     

电子设备的电磁屏蔽技术

本文详细讨论了电子设备的电磁屏蔽技术。系统地分析了电子设备电磁屏蔽的技术原理,屏蔽效能的计算方法,各种屏蔽材料的性能和应用场合,屏蔽的各种注意事项,孔眼的屏蔽效能的计算,屏蔽效能的检测以及特殊部位的特殊屏蔽措施。我们应不断地总结经验,以便逐步提高电子设备的电磁屏蔽能力。     

电子设备的电磁屏蔽技术

本文详细讨论了电子设备的电磁屏蔽技术 ,系统地分析了电子设备电磁屏蔽的技术原理 ,屏蔽效能的计算方法 ,各种屏蔽材料的性能和应用场合 ,屏蔽的各种注意事项 ,孔眼的屏蔽效能的计算 ,屏蔽效能的检测以及特殊部位的特殊屏蔽措施。我们应不断地总结经验 ,以便逐步提高电子设备的电磁屏蔽能力。     

Effect of Powder Morphologies on the Property of Conductive Silicone Rubber Filled with Carbonyl Nickel Powder

Conductive silicone rubbers filled with the spherical, flaky, and chain-spherical carbonyl nickel powder were prepared. The effects of powder morphologies on their electromagnetic and mechanical properties were analyzed. The electromagnetic shielding effectiveness (SE) and tensile strength of the rubbers varies with their powder morphologies: the SE values increase from the spherical and the chain-spherical to the flaky morphology in the frequency range of 100–400 MHz. In the range of 500–1500 MHz, the SE rises from the spherical and the flaky to the chain-spherical morphologies. In addition, the tensile strength increases from the spherical and the flaky to the chain-spherical morphologies. These variations are related to the differences in the conductive network structure and the powder distribution in the rubber.     

Characterization of copper precipitates on aluminum copper bond pads formed after plasma clean and de-ionized water exposure

Semiconductor bond pads made from aluminum and small percentages of copper is susceptible to galvanic corrosion. In galvanic corrosion, the cathode (copper precipitate) is usually protected by the aluminum oxide that covers the surface of aluminum which acts as the anode. However, when the aluminum oxide thickness is reduced by plasma cleaning, the precipitates can be exposed. When exposed precipitates come in contact with de-ionized water, galvanic corrosion takes place. Therefore, though plasma cleaning in general is supposed to improve semiconductor bond pad surface in preparation for package level interconnection, adding the plasma clean step just before a process with de-ionized water can cause bond pad corrosion through the galvanic reaction between the exposed precipitate (cathode) and the surrounding aluminum (anode). This paper aims to investigate the mechanism of corrosion and characterize corroded bond pads by using wire bond ball shear method.     

RF Shielding Effectiveness and Light Transmission of Copper or Silver Film Coating on Plastic Substrate

RF shielding effectiveness and light transmittance of acopper or silver film coating on a plastic substrate is investigated. The dependence of the RF shielding effectiveness upon the surface resistance or thickness of a copper or silver film coating on a plastic substrate is calculated numerically by means of multireflection transmission-line theory over the frequency range of 100 MHz to 30 GHz. The light transmansmittance is determined by using the optical properties of the copper or silver film and plastic substrate. An optimum condition between the RF shielding effectiveness and the light transmittance is established for the copper or silver film coating on a plastic substrate.     

Effect of 1,2,4-triazole on galvanic corrosion between cobalt and copper in CMP based alkaline slurry

Cobalt has become a new type of barrier material with its unique advantages since the copper-interconnects in the great-large scale integrated circuits (GLSI) into 10 nm and below technical nodes,but cobalt and copper have severe galvanic corrosion during chemical-mechanical flattening.The effect of 1,2,4-triazole on Co/Cu galvanic corrosion in alkaline slurry and the control of rate selectivity of copper and cobalt were investigated in this work.The results of electrochemical experiments and polishing experiments had indicated that a certain concentration of 1,2,4-triazole could form a layer of insoluble and dense passive film on the surface of cobalt and copper,which reduced the corrosion potential difference between cobalt and copper.Meantime,the removal rate of cobalt and copper could be effectively controlled according to demand during the CMP process.When the study optimized slurry was composed of 0.5 wt％ colloidal silica,0.1％vol.hydrogen peroxide,0.05 wt％ FA/O,345 ppm 1,2,4-triazole,cobalt had higher corrosion potential than copper and the galvanic corrosion could be reduced effectively when the corrosion potential difference between them decreased to 1 mV and the galvanic corrosion current density reached 0.02 nA/cm2.Meanwhile,the removal rate of Co was 62.396 nrn/min,the removal rate of Cu was 47.328 nm/min,so that the removal rate ratio of cobalt and copper was 1.32:1,which was a good amendment to the dishing pits.The contact potential corrosion of Co/Cu was very weak,which could be better for meeting the requirements of the barrier CMP.     

碱性抛光液中表面活性剂对铜钽的电偶腐蚀

在阻挡层化学机械抛光(CMP)过程中,阻挡层材料钽(Ta)易与铜(Cu)发生电偶腐蚀.针对这一问题,通过电化学分析方法研究了碱性抛光液中非离子表面活性剂对铜钽腐蚀电位的影响;通过CMP实验研究了非离子表面活性剂对铜钽去除速率的影响.结果表明,随着非离子表面活性剂体积分数增加至9％,铜钽的腐蚀电位均降低.最终确定最佳非离子表面活性剂的体积分数为6％.此时,在静态条件下,铜钽电极之间的电位差为1 mV;在动态条件下,铜钽电极之间的电位差为40 mV,可极大地减弱铜钽电偶腐蚀.同时,铜钽的去除速率分别为47 nm·min-1和39 nm·min-1,铜钽去除速率选择比满足阻挡层CMP要求.     

两种炭黑导电橡胶复合材料的电磁屏蔽性能

采用炭黑分别填充丁苯和丁腈橡胶,研究两种不同橡胶基体对炭黑的分散性能及复合材料导电性能、电磁屏蔽性能的影响。对比发现,丁苯橡胶基体中炭黑分散性能随炭黑含量增多而变差,而在丁腈橡胶中炭黑的分散性能呈相反趋势,随炭黑含量增多而变好。丁腈导电橡胶的导电性能以及电磁屏蔽性能要好于相同炭黑含量的丁苯导电橡胶。     

Antioxidant High-Conductivity Copper Pastes Based on Core–Shell Copper Nanoparticles for Flexible Printed Electronics

As a nontoxic and cost-effective material, copper pastes have attracted great attention in both academia and industry. However, achieving the long-term stability of copper pastes remains challenging due to their susceptibility to oxidation. Therefore, stable copper nanoparticles with a Cu(0)–Cu(I) core–shell structure containing a surface passivation layer of formate ions-involved Cu(I) coordination polymers are developed. Based on the self-reducing nature of the passivation layer, the nanoparticle-based copper pastes can be sintered in <1 min, showing high electrical conductivity (220 000 S cm⁻¹), mechanical flexibility, and long-term stability after sintering. The excellent properties of the developed copper pastes are even comparable with the ones of silver pastes. These stable copper pastes have broad applications in printed electronics (e.g., glucose sensors, RFID tags, and electromagnetic shielding films), showing great potential in the fabrication of flexible printed electronics.     

Low-cost and low-electromagnetic-interference packaging of optical transceiver modules

The low-cost and low-electromagnetic-interference (EMI) packaging of optical transceiver modules employing housings of plastic composites are developed and fabricated. Optical transceiver modules fabricated by the plastic composites with transmission rates of 1.25 and 2.5 Gb/s are tested to evaluate the electromagnetic (EM) shielding against emitted radiation from the plastic packaging. The results show that these packaged optical transceiver modules with their high shielding effectiveness (SE) are suitable for use in low-cost and low-EMI Gigabit Ethernet lightwave transmission systems. By comparison of cost, weight, and shielding performance for optical transceiver modules fabricated by the housings of nylon and liquid-crystal polymer with carbon fiber filler composites, woven continuous carbon fiber (WCCF), and nanoscale hollow carbon nanocapulses (HCNCs) epoxy composites, the WCCF composite shows lower cost, lighter weight, and higher EM shielding than the other types of composites. Future studies may develop the low-cost and low-EMI optical transceiver modules using nanoscale HCNCs that have the combination of excellent physical and mechanical properties, light weight, and thinness compared with the conventional fabrication techniques.     

Ultrathin Flexible Graphene Film: An Excellent Thermal Conducting Material with Efficient EMI Shielding

As the portable device hardware has been increasing at a noticeable rate, ultrathin thermal conducting materials (TCMs) with the combination of high thermal conductivity and excellent electromagnetic interface (EMI) shielding performance, which are used to efficiently dissipate heat and minimize EMI problems generated from electronic components (such as high speed processors), are urgently needed. In this work, graphene oxide (GO) films are fabricated by direct evaporation of GO suspension under mild heating, and ultrathin graphite‐like graphene films are produced by graphitizing GO films. Further investigation demonstrates that the resulting graphene film with only ≈8.4 μm in thickness not only possesses excellent EMI shielding effectiveness of ≈20 dB and high in‐plane thermal conductivity of ≈1100 W m^‐1 K^‐1, but also shows excellent mechanical flexibility and structure integrity during bending, indicating that the graphitization of GO film could be considered as a new alternative way to produce excellent TCMs with efficient EMI shielding.