Hygrothermal Stability of Electrical Contacts Made from Silver and Graphite Electrically Conductive Pastes

The hygrothermal stability of electrical contacts made from silver and graphite electrically conductive pastes is comparatively evaluated by measurement of the increase in contact electrical resistance during immersion in water at 15°C and 40°C. The pastes are silver paint, silver paint with a nonconductive epoxy overcoat, silver epoxy, and graphite colloid. Each electrical contact is made between a seven-strand tin-coated copper wire and the surface of a carbon fiber epoxy-matrix composite. Silver paint and graphite colloid penetrate the spaces among the 130-μm-diameter strands, but silver epoxy does not. Partly due to its low penetrability and the silver flake (15 μm) preferred orientation, silver epoxy gives contacts of significantly higher resistance than silver paint. Graphite colloid is comparable to silver epoxy in the resistance. Among the four pastes, silver paint with an epoxy overcoat is most durable, though it gives slightly higher resistance than silver paint without epoxy. Silver epoxy is less durable than silver paint without an epoxy overcoat, particularly at 40°C, due to the low hygrothermal stability of epoxy. Graphite colloid is even less durable than silver epoxy, due to its being water based.     

Effects of Solvent Type on Low-Temperature Sintering of Silver Oxide Paste to Form Electrically Conductive Silver Film

Silver oxide pastes were formulated from silver oxide powder, silver α-neodecanoate, and solvents, which lowers the sintering temperature of printed silver films to 150°C. In this paper, solvent effects were investigated through the formulation of silver oxide pastes using various solvents with high boiling points such as glycol, ether, and terpineol. Solvent structures such as terminal methyl and alkoxyl groups affected the solubility of silver α-neodecanoate and the swelling of the polydimethylsiloxane (PDMS) blanket. Particularly, higher solubility induced uniform mixing of the silver oxide powder and silver α-neodecanoate, which resulted in higher conductivity after sintering. Glycols and monoalkyl ethers reacted with the silver oxide or silver salt, which deteriorated the pot life of the paste. Among the various candidates, α-terpineol satisfied all the requirements such as printability and stability, exhibiting a solubility of 47.8 g in 100 g of solvent, PDMS swelling of 4.6%, and conductivity of 1.8 × 10⁵ S/cm after sintering at 150°C for 30 min.     

Electrical Conductivity of Thick Films Made from Silver Methylcarbamate Paste

We have explored the electrical conductivity of thick films made from silver methylcarbamate paste using metallic silver as the electrically conductive phase. The paste was composed of 30 wt.% to 90 wt.% organic vehicle and 10 wt.% to 70 wt.% functional phase precursor (silver methylcarbamate). After the paste was sintered, films with thickness of 4.50 μm to 12.70 μm were obtained, in which the elemental percentage of silver varied from about 5 wt.% to above 99 wt.%. Experiments showed that both the electrical conductivity and the elemental percentage were mainly affected by the initial silver content in the paste and the parameters of the sintering process. For given sintering conditions, higher initial silver content led to higher elemental percentage of silver, improving the electrical conductivity of the thick film. The conditions of the sintering process had a significant influence on the evaporation and decomposition rates of the paste components, the elemental percentage of silver, and the microstructure of the thick film. Higher temperatures, longer times, lower heating rates, and more oxygen-rich sintering atmospheres were found to accelerate the evaporation and decomposition and increase the elemental percentage of silver, both of which served to enhance the electrical conductivity. For initial silver contents less than about 10 wt.%, the lowest electrical resistivity of the thick film only reached the order of 10^?4 Ω cm, irrespective of the sintering conditions. For contents between 10 wt.% and 25 wt.%, it was possible to attain lowest resistivity values on the order of 10^?5 Ω cm. Above 25 wt.%, the lowest resistivity could reach 10^?6 Ω cm, comparable to that of bulk silver.     

基于先进厚膜技术的多芯片组件

介绍了应用低温共烧陶瓷技术 ,扩散成图技术以及 Fodel光刻成图技术等先进厚膜技术所研制的MCM。应用这些先进的厚膜技术制造出来的 MCM成本低、可靠性高、集成度高 ,研制期短、应用前景广阔。     

厚膜应变电阻的导电机理研究

制备了不同表面电阻率的Ｒｕ基厚膜应变电阻浆料,研究了厚膜应变电阻的表面电阻率与电阻应变系数之间的关系,并对其导电机理与特性进行了分析。     

低成本银基厚膜多层基板的研制

介绍低成本银基厚膜多层基板的材料系统，工艺流程，工艺特性以及基板的性能。     

Laser Direct Writing of Conductive Silver Film on Polyimide Surface from Decomposition of Organometallic Ink

Laser direct writing of organometallic ink to manufacture silver films was investigated by using a continuous-wave, Yb-doped fiber laser beam at a wavelength of 1071 nm. The organometallic ink consisted of an organometallic silver complex and a carrier vehicle, which was prepared by reaction of silver oxide with ammonium carbamates in methanol. The organometallic silver decomposed at a laser power of 0.1 W. The electrical resistivity values of silver conductors that were fabricated at a laser power of 0.5 W were about four times that of bulk silver. The morphology and electrical properties of the silver film were observed to be controllable as a function of laser processing parameters. The fabricated silver film exhibited excellent adherence to the polyimide substrate surface according to evaluation using the peel-off testing method.     

Electrically Conductive Carbon-Nanotube Framework Materials

Semiconductors - Conductive materials based on carbon and its modifications are most promising for creating biointerfaces. Such materials can be used for the targeted stimulation of cells and...     

一种氧化石墨烯-银纳米线可拉伸透明导电薄膜

柔性电子器件主要应用于折叠手机、医疗健康监测、人工智能和太阳能电池等方面,是当前研究的热点。针对银纳米线(AgNW)与衬底之间存在的粘附性较弱、易剥落、在空气中易氧化而使阻值变大等问题,文章设计了一种以PDMS为柔性衬底的三层透明导电薄膜,探究了曝光次数和氧化石墨烯不同涂覆方式对薄膜光电特性的影响。结果表明,该导电薄膜达到了12 Ω/□的方块电阻,透过率超过80%。在48%的拉伸情况下仍然保持着较好的导电性。     

钌基厚膜电阻导电机理的国内外研究状况

较全面的对国内外厚膜电阻导电机理的研究状况进行了综述，介绍了均匀分布模型，均匀通道模型。非隧道势垒模型，隧道势垒模型及其优缺点。对隧道壁垒模型进行深入的分析和讨论。并运用这些理论解释了厚膜电阻的温度特性、电场特性和热电效应。     

各向异性导电膜

概述日立化成工业(株)开发的各种各向异性导电膜,适用于显示器、TV、笔记本电脑和移动电话用的平板显示、等离子显示板和有机电荧光等的安装用途。     

导电胶的研究进展

导电胶作为无铅连接材料的一种,近年来在电子封装中得到越来越多的重视。导电机理、组成及老化性能的研究成为导电胶实用化的关键因素。各向异性导电胶是连接用Pb/Sn合金的理想替代材料。     

导体性薄膜制造工艺

概述了导电性薄膜制造工艺,适用于制造挠性覆铜板、挠性印制板和电磁干扰(EMI)屏蔽滤波器等用途的导电性薄膜。     

Electrically Conductive Metal Polymer Nanocomposites for Electronics Applications

An electrically conductive nanocomposite composed of thermoplastic elastomer and nanosized silver particles was developed. Nanosized silver particles were produced by the liquid flame spraying method. Nanocomposites were produced employing a batch mixing process in the melt state. The percolation curve and the minimum resistivity as a function of silver content were defined. A plasticized styrene block-copolymer was used as the matrix polymer. The results showed that the agglomeration of the silver particles has a major influence on the percolation threshold and the resistivity of the compound. With slightly agglomerated silver particles a percolation threshold with a silver content of 13–16 vol.% was achieved. The corresponding resistivity was 2.0 × 10⁻¹ Ω cm. With heavily agglomerated particles the resistivity is high (2.9 × 10³ Ω cm), even with a silver content of 20 vol.%. With a low primary silver particle size (under 100 nm), the resistivity of the compound was high (5.6 × 10⁵ Ω cm).     

导电性胶膜在导电泡棉衬垫中的应用

对比分析了导电胶膜和导电布基双面导电胶带在平滑型不锈钢表面和粗糙的导电布基表面的粘接性和导电性。结果表明,导电胶膜可提供更好的表面粘接特性和更低的垂直阻抗,更适合用作导电泡棉衬垫的粘接和安装解决方案。     

导电胶的力学性能研究

导电胶主要是由环氧树脂基体和导电粒子组成的复合导电聚合物,其力学性能主要是由聚合物基体决定,基体是粘弹性材料,具有时间和温度依赖性。文章建立了一个基于时间-温度、时间-固化度的宏观粘弹性本构关系来描述导电胶在固化过程中的粘弹性行为,通过动态力学试验（DMA）表征导电胶的粘弹性行为,测定导电胶的粘弹性参数。通过对导电胶粘弹性行为表征,能更好的优化固化工艺参数。     

电大尺寸导体柱电磁散射问题的快速算法

引入Ｍｕｒ边界条件建立有限差分方法,结合快速算法计算电大尺寸导体柱的电磁散射问题,避免了计算ＭＥＩ系数的计算瓶颈,且差分方程系数矩阵的生成、求解时间以及占用内存均与柱体表面剖分点数呈线性关系,极大的缩短了总的计算时间。所得结果与其他方法相比具有较好的一致性。     

半空间电大导体目标散射的高频分析方法

该文研究了半空间电大尺寸导体目标散射的高频求解方法。将半空间并矢格林函数引入物理光学方法中,对半空间环境影响进行考虑,推导出半空间物理光学分析方法,并结合图形电磁学(GRECO),对半空间电大导体目标进行消隐判断,提取像素面元法矢量和深度缓存等有效信息,快速有效地计算了半空间导体目标的雷达散射截面(RCS),数值结果证明该文方法的有效性和准确性。     

汽车用厚膜电路

概述了国内外汽车电子的现状和市场前景，近十余年来，汽车电子产品在整车中的比重不断上升。厚膜混合集成电路在汽车严酷部位和恶劣环境下运行中具有很好的适应性，为此，作者提出了发展我国汽车用厚膜电路的建议。     

Ohmic Curing of Printed Silver Conductive Traces

Ohmic heating was demonstrated as a novel curing method (or curing enhancement) useful in decreasing the resistivity of conductive traces printed with both micro- and nanoparticle-loaded inks while (1) only locally heating the substrate and (2) curing in a matter of seconds compared with the range of 30?min to 1?h required by traditional oven-curing. In one experiment using traces composed of microparticle ink, which required initial air-drying as a preprocess step, application of an ohmic curing cycle resulted in resistivity of 80?n???m, roughly six times that of bulk silver. In a second experiment employing nanoparticle inks, which required an initial thermal cure as a preprocess, a resistivity of 43?n???m, roughly three times that of bulk silver, was attained after the application of an ohmic curing cycle. Electrical characterization of the ohmic curing process was performed in real time to understand the impact of cycling and duration on the resulting conductivity. Finally, the effect of printed trace length on the ohmic curing process was explored and found to have a near-linear relationship with the reduction in resistance when the applied electrical current was normalized to measured resistance. The microstructural changes which occurred as a result of ohmic curing such as particle sintering and grain growth were characterized by scanning electron microscopy. The results presented in this work demonstrate the use of ohmic heating to overcome temperature limitations imposed on a thermal curing process by substrate material properties or other sources.