Application of face centred cubic TiB powder as conductive filler for electrically conductive adhesives

Face centred cubic（FCC） TiB ceramic powder synthesized by Ti-boronizing method was used as conductive filler to make ceramic electrically conductive adhesives（ECAs） with the polymer matrix.Electrically conductive properties of the ceramic ECAs were studied.The bulk electrical resistivity varied with the powder content of the FCC-TiB in ECAs.The FCC-TiB filled ECAs also showed the percolation behavior that usually occurred for the metal-filled ECAs,the percolation threshold was located at the content of 60%FCC-TiB.A minimum value of 0.1 Ω·cm was obtained at a content of 75%FCC-TiB.In order to check the reliability of mechanical property,tensile test was done to measure the shear strength,and the shear strength dropped with increasing the content of FCC-TiB powders.It is about 12.26 MPa at the content of 70%TiB powders.The Cu filled ECAs were also prepared for comparison.The properties of the oxidation resistance of the two ECAs were evaluated.The results show that the ceramic ECAs have excellent oxidation resistance and better stability compared with the Cu filled ECAs.

Electrochemical migration behavior of Ag-plated Cu-filled electrically conductive adhesives

The electrochemical migration (ECM) behavior of the electrically conductive adhesives (ECAs) filled with pure Ag powder or Ag-plated Cu composite powder with varied Ag:Cu ratios was investigated under the condition of applying constant voltage and distilled water environment.ECM resistance was determined from the current-time curves.The microstructure and composition of ECM dendrite products were analyzed by SEM/EDS and XRD.It was found that the ECM resistance of Ag-plated Cu composite powder-filled ECAs was evidently higher than that of pure Ag powder-filled ECAs.The Ag:Cu ratio of composite powder in ECAs had notable influence on ECM resistance,which was enhanced with the decrease of Ag:Cu ratios.The composition of dendrites formed between cathode and anode during ECM process was not uniform for Ag-plated Cu-filled ECAs.An ECM inhibiting mechanism of Ag-plated Cu composite powder was proposed according to analysis of the electrochemical impedance spectroscopy,Tafel plot and dendrite composition.

Application of silver nanoparticles in electrically conductive adhesives with silver micro flakes

This study has been conducted to evaluate the application of silver nanoparticles(NPs)in Electrically Conductive Adhesives(ECAs),filled with hybrid silver flakes and NPs,and silver flakes as a control sample,at a filler loading of 78 wt.%,83 wt.%and 88 wt.%and cured at 150℃and 180℃,respectively.The results show that the electrical and thermal conductivities of ECAs were improved with the increasing of filler loading and curing temperature.Adding silver NPs in silver flakes negatively affected the electrical and thermal conductivities of ECAs at a low filler mass fraction of 78 wt.%,because the segregation of NPs enlarged the average distance of silver flakes;while it positively influenced the electrical and thermal conductivities of ECAs at a loading ratio of 88 wt.%,probably due to NPs filling in the gaps between silver flakes or even sintering together with each other or with silver flakes,especially when curing at high temperature of 180℃.

Thermoelectric Behavior of Isotropically Conductive Adhesive

The paper deals with unusual use of one kind of ECA （electrically conductive adhesive）---the ICA （isotropic conductive adhesive）. The main sphere of ECA application is electronic assembly, e.g., it is bonding of semiconductor microchips on printed circuits boards. In this sphere, the ECA compete with soft solder. In spite of this fact, the author utilized of two main ECA characteristics--good electrical conductivity and excellent adhesion to material surfaces to make the fiat thermocouples. Both the design of thermocouples and the measuring device and the measuring workplace arrangement are described. The measured data of thermoelectric voltages are plotted. The thermoelectric （Seebeck＇s） coefficients were calculated from obtained dependences of thermoelectric voltage versus the temperature differences.

Electrically Detaching Behavior and Mechanism of Ionic Conductive Adhesives

Design of rapidly detachable adhesives with high initial bonding strength is of great significance but it is full of great challenge. Here, we report the fast electrically detaching behavior (100% detaching efficiency in just 1 min under dozens of DC voltage) and high initial bonding strength (>12 MPa) of epoxy-based ionic conductive adhesives (ICAs). The epoxy-based ICAs are fabricated by introducing polyethylene glycol dimethyl ether (PEGDE) and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM]OTF) into epoxy. The combination of PEGDE and [EMIM]OTF enables the free ions to migrate directively in electric field, and the anchoring of PEG chains onto epoxy chains ensures the long-term reliability of ICAs. The investigation on the electrically detaching mechanism suggests that the enrichment and following rapid interfacial electrochemical reactions of [EMIM]OTF lead to formation of metal hydroxide (Me(OH)n) nanoparticles at the bonding interfaces, thus the strong interactions containing interlocked forces, van de Waals’ forces and hydrogen bonding interactions between ICAs and bonding substrates are destroyed. This work provides a promising direction for detachable adhesives with both high initial bonding strength and high detaching efficiency in short time.

Conductive microsphere monolayers enabling highly conductive pressure-sensitive adhesive tapes for electromagnetic interference shielding

Conductive adhesive tape is one kind of electromagnetic interference(EMI)shielding materials for electronic packaging.However,the inferior conductivity of the pressure-sensitive adhesive(PSA)layer results in serious electromagnetic leakage at the conjunctions between the conductive tapes and target objects.Adding conductive fillers is a traditional method for highly conductive adhesive tapes.However,the content of conductive fillers is needed to reach the percolation threshold,which is usually as high as tens of percent.High-content fillers result in significant loss of adhesive property and high fabrication cost.Herein,we introduce a rational architecture of conductive microsphere monolayer(CMM)in the PSA layer.The CMM connects the top and bottom surfaces of the PSA layer and improves its conductivity in the z-direction.Importantly,low contents of conductive microspheres(≤5%(mass fraction,w))can achieve the target of conductivity improvement,but not result in the serious loss of the adhesive property.Therefore,the strategy of CMMs can balance the tradeoff between the conductivity and the adhesive property of conductive PSA tapes.Finally,we demonstrate the superior EMI shielding performance of as-made conductive adhesive tapes,indicating their potential applications as the advanced EMI shielding materials in the electronic packaging.

Design and Characterization of Electrical Connections for Conductive Yarns

The development of flexible and stretchable electronics has attracted much attention.As an important part of wearable electronic systems,the connection between conductive yarns and electronic components affects the stability and accuracy of their electrical reliability.In this paper,three different connections were attempted to electrically and mechanically link two conductive yarns,including soldering followed by waterborne polyurethane(WPU)encapsulation,coating of conductive silver adhesive with WPU encapsulation,as well as coating of conductive silver adhesive with polydimethylsiloxane(PDMS)encapsulation.The surface morphologies and electro-mechanical behaviors of the three created connected conductive yarns were characterized.Compared with their electro-mechanical behaviors of the established three connections,the connection with soldering remained electrically conductive to around 200%,which mainly came from the stress concentration between the stiff soldering and soft conductive yarns.However,the coating of conductive silver adhesive and encapsulated protection of PDMS can make the connected conductive yarns stretchable up to 300%with almost constant electrical resistance.

基于无颗粒银导电墨水在不锈钢表面镀银工艺研究

目的采用无颗粒银导电墨水对不锈钢表面进行镀银研究,以绿色环保工艺替代传统电镀银技术。方法主要研究适用于不锈钢基材的前驱体银源、络合剂种类、不锈钢前处理方法、烧结固化温度对不锈钢表面银层微观结构及性能的影响,获得不锈钢基材上微观结构致密、性能良好的银层。采用X射线衍射仪、扫描电子显微镜、激光共聚焦显微镜、数字兆欧表对在不锈钢表面银膜层进行表征。结果不锈钢通过1,2丙二胺溶液处理后,采用银源草酸银为前驱体,此时银层微观结构最致密,具有最佳的附着力等级(5B)和最低的粗糙度(1.237μm),与1,2-丙二胺络合,乙醇为溶剂时,制备出的银层有机物挥发完全,微观结构致密,并且具有最低的接触电阻0.7Ω和粗糙度0.80μm。烧结固化温度为200℃时银层导电性最好。结论采用无颗粒银导电墨水对不锈钢表面进行镀银的新型工艺银层性能良好,可以简化传统电镀技术复杂的操作流程,减少传统电镀工艺所使用氰化物对人体造成的危害,并弥补应用受限的缺点。

一种无溶剂型电子封装用导电胶的研制

为了解决导电胶黏剂因综合性能不足而导致大规模应用的受限,本文以酚醛环氧、多官能环氧为导电胶树脂基体,选用了4,4′-二氨基二苯砜(DDS)作为固化剂,片状银粉作为导电填料,通过调节银粉和固化剂的用量,制备了有良好流变性、导电性、力学性能的导电胶。通过分析测试,得到导电胶的黏度为32 800 mPa·s,触变指数为4.0,体积电阻率为4.34×10^(-4)Ω·cm,剪切强度为17 MPa,热导率为3.96 W/(m·K),Cl^(-)、Na^(+)和K^(+)分别仅为6.79×10^(-5)、6.31×10^(-5)和<10^(-5)。该导电胶综合性能优异,可应用于电子元器件及其他导电导热功能性材料的粘接。

G-Eco-AAc/OTF复合层导电水凝胶的制备及在柔性传感领域的应用

导电水凝胶作为一种高性能聚合物材料,被广泛应用于柔性传感器与储能设备等领域。然而,大多数导电水凝胶均为单层结构,且力学性能较弱。而复合层水凝胶可以通过各层之间的结合,进行力学性能上的互补。因此,需要从水凝胶的结构上进行设计,使其具有优异的力学性能,并具有更多功能。在此,通过原位聚合的方式,将石墨烯层、Ecoflex弹性体和AAc/OTF水凝胶进行聚合,制备了一款兼具黏附性能、力学拉伸性能和导电性能的复合层水凝胶G-Eco-AAc/OTF。由于水凝胶表面羧基、羟基和磺酸基团的存在,该水凝胶材料展示了良好的黏附性。将G-Eco-AAc/OTF复合层导电水凝胶应用于运动传感领域,可对手指、手腕、肘部和膝盖处进行信号的监测,并且测试结果稳定。这为下一代可穿戴柔性传感设备奠定了基础。

太阳能叠瓦组件用导电胶黏剂的研制

针对叠瓦组件对导电胶黏剂的要求,研制了基于丙烯酸基体树脂的单组分导电胶。对导电胶的粘度和触变性能,存储期和可操作时间,固化速度,黏结性能,导电性能等进行了全面表征。结果表明研制的导电胶具有杰出的综合性能。将导电胶用于叠瓦组件的粘接,并验证组件的功率,组件功率接近理论功率。制备的导电胶在商业化的叠瓦组件上具有较为广阔的应用前景。

耐400℃高温氰酸酯导电胶的制备与性能

为了解决芯片密封封装时管壳高温焊接导致的芯片脱粘、封装内产气等问题,本工作首次以耐高温氰酸酯树脂为基体、高纯片状Ag粉为填料,制备了耐400℃高温的氰酸酯导电胶。微观结构分析结果表明,片状Ag颗粒在氰酸酯基体中随机分布,形成了较好的导热导电网络,且去除Ag粉表面有机物可以有效抑制氰酸酯导电胶粘接固化后气泡和裂纹的产生。热性能分析表明氰酸酯导电胶具有优异的热稳定性,其在300℃下的失重率仅有0.06%,400℃下的失重率小于0.3%,远低于目前公开报道的导电胶在相同温度下的失重率。氰酸酯导电胶的玻璃化温度(Tg)为240℃,低于和高于Tg时的热膨胀系数分别为51.2×10^(-6)/℃和162.2×10^(-6)/℃,具有较宽的使用温度范围。环境实验和力学性能测试表明,氰酸酯导电胶具有优异的粘接性能和环境适应性,330℃固化后的导电胶在环境测试后平均芯片剪切强度高达18.4 MPa。本工作制备的氰酸酯导电胶具备优异的综合性能,对电子封装用高温导电胶的研发和应用具有重要的参考价值。

树枝状银粉及表面处理对导电银胶的性能影响

针对导电胶电导率较低,接触电阻不稳定,冲击强度差等问题,研究树枝状银粉作为导电填料对导电胶性能的影响,结果表明,与片状银粉制备的导电胶相比,掺杂树枝状银粉的导电胶表现出更好的导电性能,其体积电阻率降低了0.8×10^(-3)Ω·cm。在此基础上,探索了油酸和KI等表面处理剂对导电胶的导电性、力学特性等影响,并分析了导电胶导电性能的提升机制。结果表明,表面处理剂种类对导电胶性能具有选择性的改善作用,KI处理后的导电胶具有较好的导电性能,且树枝状银粉为填料的导电胶表现出最低的电阻(0.9Ω)。油酸处理后的导电胶表现出较好的力学性能,且片状银粉为填料的导电胶具有较好的剪切力(570 N),为导电胶产品研发提供技术支撑。

不同形貌镀银铜粉导电胶的制备及表征

采用凝胶法制备了高导电率导电胶,其导电填料为基于铜粉的树枝状、片状和球状镀银铜粉。通过四探针测试仪,测量了导电胶的体积电阻率,表征了导电胶的导电性能。采用旋转流变仪和万能拉力机得到导电胶的黏度和剪切强度,分析了导电胶的流变特性和力学性能。结果表明:三种形貌中,由于树枝状粒子的接触点最多且导电通道数量大,使得相同含量下,树枝状镀银铜粉导电胶的导电性能最优。在180℃下添加量为70%的树枝状镀银铜粉导电胶,固化时间2 h,拉拔附着力和黏度为19 MPa和1.08×10^(6) mPa·s,最佳体积电阻率为3.5×10^(-4)Ω·cm。研究结果为制备高性能导电胶提供了可行的方案。

高性能环氧树脂基ECA的制备及机理分析

电子设备对小型化、高功率密度等要求越来越高,无铅化的提出使人们摒弃了传统的锡铅合金焊料,逐渐将目光转向新型的封装结构和材料,聚合物导电粘合剂又称导电胶(Electrically Conductive Adhesive,ECA),便是其中之一。本文系统地讨论对比了两大类环氧树脂作为基体的ECA性能,制备了一种高强度高导电的环氧树脂基导电银胶作为一种新的封装连接材料并解释了其性能优异的原因,传统聚合物在固化过程中形成的大量孔洞得到有效降低,ECA的电导率和强度从而得到大幅度提高。所制备出的高性能环氧树脂基ECA能够更好的适应封装材料的强度和导电导热需求。

天线罩表面导电涂层的制备工艺及性能研究

为解决由碳纤维复合材料制备的雷达天线罩自身导电性能差、反射能力弱和空间防护能力不高的问题,先通过电弧喷涂技术在Q235钢模具表面制备铝涂层,然后在碳纤维复合材料固化的过程中将其转移至天线罩表面。研究了电弧喷涂时的主要工艺参数对铝涂层孔隙率的影响,得到最佳的工艺参数为:空气压力0.6 MPa,喷涂距离300 mm,喷涂电压28 V。扫描电镜表征和热淬法测试表明,通过上述方法在天线罩表面制备的导电涂层均匀连续,表面致密,无裂纹、空腔和外来夹杂物,结合力良好。

导电胶粘剂的研究进展

导电胶粘剂的发展对电子技术的发展有着极其重要的意义。介绍了导电胶粘剂的分类、组成、导电机理和研究现状,并指出了导电胶粘剂在实际应用中需要解决的问题。

碳纳米管导电防腐涂料微观形貌及性能研究

为制备1种接地网用碳纳米管改性导电防腐涂料,采用球磨工艺将填料分别分散在有机硅树脂和环氧树脂内制得了导电防腐涂料。将涂料喷涂固化,研究了涂层形貌和碳纳米管质量分数对涂层电导率、附着力以及耐蚀性能的影响。结果表明:碳纳米管在有机硅中分散均匀,在环氧内则存在团聚;2种涂层的渗流阈值均<1%,当碳纳米管质量分数为8%时,有机硅和环氧涂层电导率分别为1.3 S/cm和1.7×10^(-2) S/cm;少量的碳纳米管有助于提高涂层的内聚力,当碳纳米管质量分数>6%时,有机硅涂层的附着力与耐蚀性能都呈下降趋势,这种现象在环氧涂层中更为明显。与环氧树脂相比,有机硅树脂更适合作为碳纳米管改性导电防腐涂料的成膜剂,当碳纳米管质量分数为5%时,有机硅树脂涂层具有较好的综合性能。

国外微电子组装用导电胶的研究进展

介绍导电胶的组成、分类、较之于传统共晶锡铅焊料的优点以及导电胶的研究现状。重点阐述国外在导电胶导电机理研究、可靠性研究及新型高性能导电胶研制方面的现状和进展。

树脂基体对导电胶体积电阻率的影响

以环氧树脂、胺类固化剂Aradur9506和片状银粉为原料制配导电胶,通过红外光谱(FT-IR)、扫描电镜(SEM)等方法进行测试,研究等温固化过程中环氧树脂的官能团数量以及固化剂添加量对导电胶体积电阻率的影响,并探讨其影响机理。研究结果表明:随着环氧树脂官能团数目的增加,体积电阻率逐渐降低,其中四官能团的环氧树脂时体积电阻率最低,为1.299×10 4.cm;随着固化剂质量的增加,体积电阻率呈现先下降后上升的趋势,当环氧树脂与固化剂质量比为25:5时,体积电阻率最低,为3.112×10 4.cm;体积电阻率与树脂基体的固化收缩率呈反比例关系,固化收缩率越大,体积电阻率越低。