碳纳米管对微胶囊铜复合浆料导电性能的影响

为提高铜浆料的导电性能,利用微胶囊技术对铜粉表面做改性处理,添加碳纳米管为导电增强相,制备碳纳米管-微胶囊铜复合浆料。利用四探针测试仪、扫描电子显微镜(SEM) 等研究了微胶囊铜粉的抗氧化性能及碳纳米管的参数、添加量对铜浆料导电性能的影响,分析其导电机理并建立导电相连接模型。研究结果表明:微胶囊化的铜粉具有较好的抗氧化性和导电性。当碳纳米管与铜粉的质量比为4∶[KG-2mm]96时,采用管径1~2 nm,长度5~30 nm的碳纳米管制备的复合浆料的电阻率达到最小值6.05 mΩ·cm,与纯铜浆料相比降低了89.39%。以碳纳米管-铜复合浆料与铜浆料分别制得导电膜,两者相比,前者更平坦、更致密,导电相间的接触更紧密,大量的碳纳米管覆盖在铜粉颗粒表面或填充铜粉颗粒间隙,同时碳纳米管之间相互“吸引”,形成致密的网状结构,在铜粉颗粒之间建立起大量的导电“桥梁”,从而改善了复合浆料的导电性能。     

石墨烯对微胶囊铜电子浆料导电性能的影响

以丙烯酸树脂作为微胶囊壁材溶液包覆铜粉,石墨烯作为导电增强相,制备了石墨烯-微胶囊铜复合电子浆料。利用金属电导率测试仪、X射线衍射仪、四探针测试仪和扫描电子显微镜分别研究了微胶囊铜粉的电导率及其抗氧化性能,分析了石墨烯对石墨烯-微胶囊铜复合电子浆料导电性能的影响。结果表明:微胶囊铜粉与未包覆铜粉相比,电导率明显提高,且当增重率为4%(wt,质量分数)时,电导率达到最大值41.30%IACS,且不存在CuO或Cu_2O;石墨烯的加入对铜复合电子浆料的导电性能有增强作用,但不同类型石墨烯的增强效果不同,导电性能主要与石墨烯的片径、厚度、纯度相关,其中片径约5μm,厚度为1～5nm的石墨烯纳米片作为导电增强相制备的铜复合电子浆料导电性能最优。     

石墨纳米片对铜电子浆料导电性的影响

为改善铜浆导电性,以表面改性的金属铜粉为主要导电相,通过添加少量导电性优异的石墨纳米片作为导电增强相制备复合电子浆料,并采用四探针测试仪、扫描电子显微镜(SEM)等分析测试方法研究了石墨纳米片的参数、添加量对铜电子浆料导电性能的影响.结果表明:选用厚度为3~5 nm,片径为5μm的石墨纳米片作为导电增强相,制得石墨纳米片—铜电子浆料,在460℃烧结后导电膜层的电阻率较小;石墨纳米片与铜粉质量比为2∶98时,测得浆料电阻率为17.14 mΩ·cm,相比纯铜浆料电阻率34.43 mΩ·cm降低了50.22%.分析电子浆料导电机理并建立导电相连接几何模型,在导电膜层中,部分折断的石墨纳米片会填充到铜颗粒之间的空隙中,较长石墨纳米片则会形成"搭桥"现象,增加导电相之间的连接,形成较紧密的微观组织和良好的导电网络,从而改善复合浆料的导电性.     

烧结温度对铜复合电子浆料烧结膜组织和性能的影响

烧结温度和玻璃粉熔点对铜复合电子浆料烧结膜的性能有重要影响。本文选用熔点为430℃的玻璃粉作为复合电子浆料的粘结相,采用四探针测试仪、扫描电镜(SEM)等方法研究了不同烧结温度下导电铜膜的电阻率及其微观结构。结果表明460℃烧结时,玻璃液粘度适中,能完全润湿、包覆铜粉,且铜粉能均匀悬浮在玻璃液中,制得的导电膜平整、致密,导电通道多,因而导电性能较好,同时玻璃液凝固、收缩使膜层与基体之间获得良好的附着力和抗老化性能。     

无铅玻璃粘结相对铜导电浆料性能的影响

研究了无铅玻璃粘结相的熔点和含量对铜导电浆料性能的影响。采用四探针法测定铜膜的导电性,采用X射线衍射和显微组织分析对样品进行表征,并测定了铜膜的附着力。结果表明,低熔点无铅玻璃粉有利于防止铜粉高温氧化,且在较低烧结温度时,残余有机载体可以包覆铜粉,防止铜粉在低温烧结时氧化,制得的导电铜膜样品表面平整,微观组织致密,导电性好。当低熔点无铅玻璃粉含量为8%时,方阻为47.78mΩ/□,附着力为10N/cm~2左右,符合行业要求。     

硼硅酸凝胶包覆层对铜粉抗氧化性和导电性的影响

铜电子浆料作为银电子浆料最为理想的替代材料,其越来越受到人们青睐,但铜的性质活泼,极易被氧化.为解决铜电子浆料在高温烧结时铜粉易被氧化的问题,以无水乙醇、正硅酸乙酯、硼酸三丁酯为原料制作SiO_2-B_2O_3溶胶,用SiO_2-B_2O_3溶胶对经过盐酸酸洗过的铜粉进行包覆,将包覆后的铜粉制成浆料并印刷到陶瓷模板上,600℃烧结制备得到铜导电膜层.通过四探针测试仪测试铜导电膜层的电导率,利用扫描电子显微镜(SEM)观察不同量溶胶包覆的铜粉的表面形貌,采用X射线衍射仪(XRD)及热重分析仪(TGA)考察溶胶包覆铜粉700℃烧结后的氧化情况.结果表明,在m(SiO_2-B_2O_3)∶m(Cu)=10%时,硼硅酸溶胶恰好均匀包覆铜粉而无多余溶胶堆积铜粉之间,此时铜导电膜层导电性能最好,其相对电导率为57%;铜粉700℃高温烧结后几乎没有被氧化,铜粉表面仅有极少量的氧化亚铜生成.实验结果证明,在合适的硼硅酸溶胶包覆率下,铜粉在700℃以下具有良好的抗氧化性,铜导电膜层也具有良好的导电性能.     

低温铜电子浆料的制备及性能研究

以铜粉、环氧树脂及固化剂、偶联剂为原料,经过铜粉表面的改性处理、均匀混合和涂覆工艺,制备了低温铜电子浆料。用XRD、SEM、TG、金相显微镜和LCR电桥测试仪对制备的铜电子浆料进行了微观组织的表征和性能测定。结果表明:经偶联剂处理过的粉体与树脂的相容性提高;铜粉含量小于90%时,浆料能获得较好的附着力;有机物包覆使铜粉的抗氧化性提升;当铜粉含量为80%~90%时,表现较低的电阻,可形成良好的导电通路;250℃以下时,铜粉电子浆料的热稳定性较好。     

铜电子浆料的制备及性能

本文采用微米级铜粉为导电填料,抗坏血酸为还原剂,聚乙烯吡咯烷酮为分散剂,环氧树脂为基料,聚酰胺树脂为固化剂,制备获得空气中低温固化铜电子浆料。利用X射线衍射仪、金相显微镜、四探针电阻测试仪、粘度测试仪等对电子浆料各性能进行了表征。实验结果表明,当铜粉与有机载体的比例为85∶15时,在烘箱中75℃烘干得到的导电铜膜性能最佳,电阻率为3.627×10-3Ω·cm,空隙较少,样品表面较为平整,导电性较稳定。     

铜粉电子浆料的老化性能

为了研究铜电子浆料的老化性能,本文以铜粉、环氧树脂、固化剂及偶联剂为原料,采用共混法制备了低温固化类铜粉电子浆料,借助XRD、SEM和LCR数字电桥对其进行表征和性能测定。结果表明:经偶联剂包覆处理后铜粉的分散性得到提高,导电浆料在自然老化条件下放置180天时电阻值最大为33.8Ω,室温氧化60天后质量仅增重1.32%×10-3。因此,制备的低温铜粉电子浆料具有较好的热稳定性、抗氧化性及可靠性。     

有机载体对石墨烯-铜复合浆料性能的影响

为提高铜浆的导电性,选用松油醇-乙基纤维素系列有机载体,粒径为10μm的铜粉为主导电相,添加少量石墨烯为导电增强相,熔点为430℃的玻璃粉为粘结剂,按一定质量分数配合比混合制备石墨烯-铜复合浆料。并利用四探针测试仪、扫描电子显微镜(SEM)等分析测试研究有机载体对石墨烯-铜复合浆料性能的影响。结果表明:乙基纤维素、松油醇、消泡剂、硅烷偶联剂、乙酸乙酯的质量分数配合比为4.75∶82.18∶2.57∶5.37∶5.13条件下制得的有机载体性能较好;有机载体用量为20%(wt,质量分数)条件下,制得的石墨烯-铜复合浆料在丝网印刷过程中能够获得平整的印刷结构,具有较小的电阻率,为17.14mΩ·cm;添加少量石墨烯后复合铜浆电阻率比纯铜浆料降低了50.22%。     

High copper loading metal organic decomposition paste for printed electronics

A screen-printable metal organic decomposition (MOD) paste with a high copper loading has been developed. Copper precursor (copper hydroxide and copper formate) and copper flasks are used as copper sources in the paste. The copper precursor is reduced to copper nanoparticles during sintering at a temperature of 200 °C for 3 min and forms a conductive film, whereas the copper flakes are added to increase the conductivity of the printed film. The optimal formulation of the screen-printing MOD paste was obtained with a copper hydroxide to formic acid ratio of 0.875 and by adding copper flakes to reach a total copper loading of 30 wt%. The printed film after sintering had a sheet resistance of 39 mΩ/sq and a volume resistivity of 21 μΩ cm.     

镀铜CF/ABS树脂复合材料的导电性能

通过在中间相沥青基炭纤维表面化学镀铜以提高纤维导电性能,并以热压法制备了短切镀铜炭纤维(Cu-CF)增强ABS树脂导电复合材料。采用SEM、EDS、XRD等表征方法研究了Cu-CF的镀层厚度、Cu-CF界面结构,以及镀铜厚度和Cu-CF的含量对复合材料导电性能的影响。研究表明,化学镀铜是铜晶粒不断长大与晶体结构更加致密的过程。Cu-CF的界面粘结受镀层厚度的影响,随着镀层厚度的增加,镀层与纤维之间出现间隙。Cu-CF的电阻率随镀层厚度的增加急剧降低,当镀层厚度增大至695nm后电阻率趋于稳定。采用镀层厚度为632nm的Cu-CF为增强相,当其体积含量为20%时,Cu-CF/ABS复合材料的电阻率为5.87×10-4Ω·cm,在导电功能材料领域具有很好的应用前景。     

Effect of size and shape of metal particles to improve hardness and electrical properties of carbon nanotube reinforced copper and copper alloy composites

Utilizing the extra-ordinary properties of carbon nanotube (CNT) in metal matrix composite (MMC) for macroscopic applications is still a big challenge for science and technology. Very few successful attempts have been made for commercial applications due to the difficulties incorporating CNTs in metals with up-scalable processes. CNT reinforced copper and copper alloy (bronze) composites have been fabricated by well-established hot-press sintering method of powder metallurgy. The parameters of CNT–metal powder mixing and hot-press sintering have been optimized and the matrix materials of the mixed powders and composites have been evaluated. However, the effect of shape and size of metal particles as well as selection of carbon nanotubes has significant influence on the mechanical and electrical properties of the composites. The hardness of copper matrix composite has improved up to 47% compared to that of pure copper, while the electrical conductivity of bronze composite has improved up to 20% compared to that of the pure alloy. Thus carbon nanotube can improve the mechanical properties of highly-conductive low-strength copper metals, whereas in low-conductivity high-strength copper alloys the electrical conductivity can be improved.     

Preparation of ultra-fine copper powder and its lead-free conductive thick film

In this paper, non-agglomerated monodispersed ultra-fine copper metallic powders have been synthesized with chemical reduction method. Fine lead-free glass powders were also prepared by solid synthesis process. Thick film paste prepared by above-mentioned copper metallic powders and lead-free glass powders was applied as conductive paste of MLCC. Mixture of glass and zinc oxide give the thick film a high adhesion strength which is attributed to the rough interface from interfacial reaction between glass and chip, and a good densification. Diffusion of metal between copper thick film and nickel thick film is clear. Ni-Cu solid solution appears under high temperature firing.     

纳米铜修饰多壁碳纳米管/石蜡相变驱动复合材料的制备及热性能

以油胺为分散稳定剂,在石蜡中热分解甲酸铜-碳纳米管复合物前驱体,单步制备了纳米铜修饰多壁碳纳米管(Cu-MWCNTs)/石蜡复合材料。通过XRD、TEM和DSC对Cu-MWCNTs/石蜡复合材料的物相、微观形貌及相变行为进行了表征和分析,并对其热敏性、热膨胀性和热稳定性及影响因素进行了分析研究。结果表明:纳米Cu原位沉积在MWCNTs外壁上,粒径为2~35nm。与纯石蜡相比,Cu-MWCNTs/石蜡复合材料的相变温度和相变潜热均明显降低。Cu-MWCNTs含量为0.2wt%的Cu-MWCNTs/石蜡复合材料具有较短的升温时间,体膨胀率降低较小,且多次加热后稳定性较好,可作为此类热敏微驱动器的理想材料。     

填充碳纳米管各向同性导电胶的性能

制备了以碳纳米管(CNTs) 和镀银碳纳米管(SCCNTs) 为导电填料的各向同性导电胶, 研究了它们的电学性能、力学性能及抗老化性能, 并与传统的以微米量级的银粒子作为导电填料的导电胶的性能进行比较。研究发现: CNTs 作为导电填料时, 在填料体积分数为31 %时出现体积电阻率的最低值2. 4 ×10-3Ω·cm; 在填料体积分数为23 %时导电胶表现出最好的抗剪切性能。在填料体积分数同为28 %时, 填充SCCNTs 导电胶具有最低的体积电阻率2. 2 ×10-4Ω·cm; 填充CNTs 和SCCNTs 显示出比填充微米量级银粒子导电胶高的抗剪切强度(19. 6 MPa) 。在85 ℃、RH 85 %环境下经过1000h 老化测试结果表明: 填充SCCNTs 或CNTs 导电胶体积电阻率的变化和剪切强度的变化均不超过10 %; 而填充微米量级银粒子导电胶在老化后体积电阻率的变化和抗剪切强度的变化分别达到350 %和120 %。      

Electrical conductivity of copper nanoparticle thin films annealed at low temperature

Copper nanoparticles with a mean diameter of 20 nm were used to prepare electrical conductive films at low temperature. After dispersal in an organic solvent, the copper nanoparticle pastes were coated onto a glass substrate, which was then annealed under various conditions to investigate the effects of various atmospheric conditions, such as air, nitrogen gas or hydrogen gas, as well as different annealing temperatures. Two-step annealing, which first involves oxidation in air followed by reduction, is effective in the preparation of high electrical conductive copper nanoparticle films. The copper nanoparticle films that were calcined in air for 1 h and then hydrogen gas for 1 h at a low temperature of 200 °C showed a low resistivity of 2 × 10^-5 Ω cm.     

膨胀石墨/石蜡相变复合材料有效导热系数的数值计算

通过膨胀石墨粉与石蜡混合制备相变复合材料可有效提高该储能材料的传热性能。为研究膨胀石墨/石蜡相变复合材料的导热机制,提出了膨胀石墨粉与石蜡混合后的3尺度层次固体有效导热系数计算方法。然后,通过数值模拟计算得到了具有不同体积分数和不同导热系数的膨胀石墨导热颗粒的膨胀石墨/石蜡相变复合材料的有效导热系数。结果表明:膨胀石墨能够有效地提高石蜡的导热性能,当膨胀石墨的体积分数为10%时,膨胀石墨/石蜡相变复合材料的有效导热系数是纯石蜡的9倍。此外,提高底层尺度的石墨片与石蜡的混合程度及降低底层尺度石墨的体积分数都能有效提高膨胀石墨/石蜡相变复合材料的有效导热系数。所得结论为探究膨胀石墨粉提高相变复合材料导热系数的机理奠定了基础。