Easy and Large Scale Synthesis Silver Nanodendrites: Highly Effective Filler for Isotropic Conductive Adhesives

Dendritic silver (Ag) nanoparticles have been successfully prepared by an easy and large scale liquid-phase reduction method. Transmission electron microscope (TEM), scanning electron microscope (SEM), and x-ray diffraction (XRD) have shown that the Ag particles prepared by this method are pure and with uniform dendritic morphology. The bulk resistivity and bonding strength of isotropic conductive adhesives (ICAs) filled with Ag nanodendrite and micrometer-sized Ag have been measured. The results show that the dendritic morphology of Ag nanoparticles has a strong effect for improving the reinforcement of the composite electrical performance. ICA filled with small amounts of Ag nanodendrites exhibits lower bulk resistivity and higher bonding strength than ICA filled with micrometer-sized Ag. When ICA is filled with 50 wt.% micrometer-sized Ag and 10 wt.% Ag nanodendrites, the bulk resistivity is 1.3 × 10⁻⁴ Ω cm, and the bonding strength reaches 18.9 MPa.     

Research of silver plating nano-graphite filled conductive adhesive

In this paper, silver plating nano-graphite (Ag plating nano-G) was developed by electroless plating method using nano-graphite prepared from expanded graphite. The silver plating nano-graphite filled conductive adhesive prepared was composed of 66 wt% of epoxy resin E-51, 20 wt% of Ag plating nano-graphite as conductive filler, 9 wt% of triethanolamine as curing agent and 5 wt% of other additives. It took 180 min for the adhesive to be cured completely at 120 °C. The electrically conductive adhesives exhibited two percolation threshold values which were 7 wt% and 17 wt%, respectively. The electrical resistivity of the conductive adhesive decreased to 1.50 × 10^?3 Ω cm and the tensile lap strength remained at a high level (about 13.2 MPa) when the content of the conductive filler was 20 wt%. TGA indicated that the conductive adhesive exhibited good thermal stability.     

一维银线制备及其在导电胶中的应用

用不锈钢辅助醇热法高浓度、大规模制得低长径比(约为10～20)的一维银线,AgNO3浓度可达0.65 mol/L;该一维银线可作为导电胶的导电填料使用;一定范围内降低AgNO3浓度生成的一维银线其长度几乎保持不变,但平均直径略有减小;采用反应活性较低的不锈钢,提高初始反应温度对一维银线的形成有不利的影响。一维银线经球磨可制得类似带状的银粉;采用带状银粉制备的导电胶体积电阻率较一维银线更低,渗流阈值可以降至20%(质量分数)。     

不同形貌的银对导电胶性能的影响

银的形貌、银表面的润滑剂、树脂基体的成分、固化过程等都会影响导电胶的性能。其中，银的形貌是一个关键的因素。论文研究了在相同条件不同形貌的银对导电胶性能的影响。将银片、银球和银线用戊二酸处理以消除其他因素的影响，然后这些银粒子被用作导电填料与环氧树脂混合制备导电胶。研究了不同形貌银粉制备的导电胶热降解性能、导电性能、机械性能及贮存稳定性。结果表明在相同条件下银线制备的导电胶具有最低电阻率和渗流阈值、最好的机械性能、以及较好的贮存稳定性，银片制备的导电胶导电性能和贮存稳定性比用银球制备的导电胶好，但机械性能比用银球制备的导电胶差。     

Using nanoparticles as direct-injection printing ink to fabricate conductive silver features on a transparent flexible PET substrate at room temperature

Conductive metallic features that are flexible could have application in integrated circuits, ranging from large-area electronics to low-end applications. This paper shows the creation of conductive silver thin film and wire on the transparent flexible polyethylene terephthalate (PET) substrate by a room-temperature chemical reduction process. One-step synthesis and spectroscopic characterizations of size-controlled silver nanoparticles are also described. Transmission electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric-mass analysis, X-ray photoelectron spectroscopy and synchrotron radiation X-ray diffraction were used to characterize the dodecanoate-protected silver nanoparticles. Silver metal film and wire were produced by soaking the dodecanoate-protected silver nanoparticle film and wire, which were prepared, respectively, by spin-coating and by directly drawing with a commercial Epson T50 inkjet printer onto the flexible PET substrate using Ag nanoparticles suspended in cyclohexane (10 wt.%) as the ink, in an aqueous solution containing 80% N₂H₄. The resistivities of the Ag films are actually lower compared with the Ag thin films prepared by other conventional chemical routes, such as using silver salts as metallo-organic precursors. It is suggested that the use of nanoparticles as a precursor may be an explanation for the lower resistivity.     

耐折高导电性银浆的制备

研究了银片粒径对折叠前后银浆电导率的影响。采用不同粒径的片状银制备了具有良好导电性能的低温固化耐折导电银浆料,将银浆网印在聚酰亚胺基板上,在140 ℃下烧结形成网印电路。用微欧姆计检测了印刷电路的电阻率,对印刷银电路折叠前后的电阻变化进行了检测,并用扫描电镜对其表面形貌进行了研究,分析了导电机理。结果表明,小片Ag作为未连接薄片之间的桥梁,在折叠后填补了空白,形成导电网络,提高了折叠后的银浆导电性能。     

LED封装用导电银胶的制备及性能研究

通过研究树脂体系、固化剂及片状银粉对导电银胶体系力学性能、导电性能及耐候性能的影响,制备出可常温储存的导电银胶。结果表明,银粉质量含量75%,环氧树脂(EP)与聚酰胺酰亚胺树脂(PAI)质量比为80/20,二氨基二苯甲烷/二氨基二苯醚质量比为60/40,所配制的导电银胶的性能能够达到技术指标。样品经封装企业进行上线测试,能够满足应用要求。     

Research on a New Synthesis Technology of La-Mg-Ni System Alloys and Microstructure of La0.67Mg0.33Ni3.0 Alloys

在常温条件下,以硬脂酸银为前驱体,受阻酚为还原剂,三苯基磷为还原促进剂,采用超声化学法制备了银纳米粒子.考察影响银纳米粒子形成的实验因素,并利用透射电子显微镜、紫外可见吸收光谱及X射线衍射仪对银纳米粒子进行了表征.结果表明,在一定条件下所得银纳米粒子的平均粒径为6.8 nm,尺寸分布为6.2 nm至7.4 nm,具有良好的稳定性和均一性.溶剂蒸发后,银纳米粒子可形成二维有序纳米阵列.探讨了银纳米粒子的形成机理.     

Conductivity and mechanical properties of conductive adhesive with silver nanowires

The aim of this study was to develop conductive adhesive using silver nanowires prepared via solvothermal method as conductive fillers and epoxymodified organosilicone resin as matrix resin. Effect of the addition of silver nanowires/flakes on the conductive adhesive's electrical and mechanical properties was investigated. Compared with conventional conductive adhesive with silver flakes fillers, the percolation threshold of conductive adhesive with silver nanowires fillers is 10 % lower approximately. However, further rise of the content of silver nanowires has no obvious influence on improvement of the electrical conductivity of conductive adhesive. Both conductive and mechanical properties of conductive adhesive can be compatible by adding silver nanowires, which traditional silver conductive adhesives cannot reach.     

Progress in application and preparation of silver nanowires

Silver nanowires have attracted wide research attention for their excellent optical, electrical and chemical properties. Many researches were performed toward synthesizing and application of silver nanowires. The application of silver nanowires such as transparent conductive film electrode, conductive silver adhesive and nanowelding technology was introduced herein. Principles and characteristics of different synthesizing methods of silver nanowires were reviewed in this paper, including template method, liquid polyol method, self-assembly method, ultrasonic reduction method and wet chemical method. The liquid polyol method was the most available one to achieve efficient large-scale production.     

Effect of heating cycle on the structure of Ag films deposited over porcelain substrates

Silver films were deposited over porcelain substrates by using flexible adhesive transfer layers. These films were produced in order to use porcelain utensils over household induction heating plates. Mixtures of different glass ceramic powders with silver powder are used to prepare the self-transfer patterns. These patterns are deposited over porcelain substrates and sintered using different heating cycles. One defect observed in such films is the presence of porosity either at the Ag/porcelain interface or inside the Ag film structure. While lower sintering temperatures produce less porosity, the microstructure of the Ag layer at lower temperatures is no longer composed of a contiguous network of large silver agglomerates. Consequently, the heating capability of the layer through electromagnetic induction is affected. Finally a sintering cycle is proposed for which the film properties are least modified with a minimum level of porosity.     

DTAB溶液中纳米银的制备

常温磁力搅拌下,在十二烷基三甲基溴化铵(DTAB)体系中用水合肼还原硝酸银制备了颗粒细小均匀的纳米银粉。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和紫外-可见光谱(UV-vis)对产品进行了分析表征。结果表明,纳米银并非是由水合肼直接还原Ag+生成,而是生成的溴化银逐渐被还原后的产物。随着反应时间的变化,体系中首先形成粒度均匀的类球形溴化银,随后转变为多面体的溴化银,最后转变为颗粒细小的纳米银。     

无颗粒型银基导电墨水的制备、性能及其应用研究

以离子交换法合成的草酸银前驱体为银源,乙二胺为络合剂,异丙醇为溶剂制备了MOD无颗粒银导电墨水。将该墨水喷墨打印于聚萘二甲酸乙二醇酯(PEN)柔性基板,并在加热板上150℃固化20 min,并通过DSC、FE-SEM、激光共聚焦、四探针测电阻率方法对合成的墨水进行表征。结果表明导电墨水的温度远低于银前驱体的分解温度;喷墨打印多层的银线在基板上表现出不同宽度、厚度和电阻率。其中,打印10层的银线电阻率可达3.22μ?·cm,接近块状纯银电阻率(1.65μ?·cm)。喷墨打印后的银图案表面平整光滑且微观组织致密,在柔性印刷方向有良好的应用前景。     

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.     

纳米银/环氧树脂复合电介质的电导特性

研究了纳米银(Ag)/环氧树脂(EP)复合材料的直流体积电阻率和强场电导。结果表明,在环氧树脂中微量添加小尺寸的银纳米粒子后,复合材料的体积电阻率比纯环氧树脂有明显提高,并且电阻率的增加与银粒子尺寸、含量,以及基体聚合物的特性有关。对复合材料强场电导的研究表明,小尺寸的银粒子在聚合物中分散良好时,复合物的强场电导表现出库仑阻塞特性,即纳米粒子可限制载流子的迁移。而当纳米粒子的粒径过大或添加较多时,复合材料在强电场下表现出对电荷的捕获与脱陷,具有明显的空间电荷限制电流特性。热刺激电流特性反映出纳米粒子与聚合物在界面处形成深陷阱是产生空间电荷限制电流的原因     

EFFECTS OF DIFFERENT FUNCTIONAL GROUP-CONTAINING ORGANICS ON MORPHOLOGY-CONTROLLED SYNTHESIS OF SILVER NANOPARTICLES AT ROOM TEMPERATURE

Silver nanoparticles with average particles sizes ranging from 2 to 131nm were manipulatively synthesized starting from silver nitrate using different functional group-containing organic modifiers at room temperature. The effects of the organic modifiers on the morphology of the resulting silver nanoparticles were strongly dependent on the intrinsic properties of the functional groups and the reducibility of the reductant. Numerous ether bonds （-0-）present in polyethylene glycol and Tween-80 were beneficial to the formation of silver nanoparticles with particle sizes of several nanometers in a narrow size distribution in both weak and strong reducing environments. Cetyltrimethylammonium bromide induced the formation of nanosized silver triangle plates in a weak reducing environment. The crystal growth of the silver nanoparticles with particle sizes of more than lOnm was postulated through an adhesion process of small-sized particles followed by a subsequent coalescence process under the present reaction conditions.     

超细银包覆BaTiO3粉体的制备

讨论了金属-陶瓷复合材料超细银包覆BaTiO3粉体的制备条件，采用扫描电镜，激光粒度分布仪，比表面积分析仪及X射线荧光光谱仪表征了复合粉末颗粒的形貌和粉体的团聚状态。讨论了银在钛酸钡粉末表面的包覆形式。采用化学镀的方法在BaTiO3表面沉积金属银。在天然高分子表面活性剂的保护下，Ag(NH3)2^ 被水合肼还原得到分散性良好的不同含银量的复合粉体。最佳的反应条件是：银含量0．1％～0．5％，Sodium Alginate／Ag(质量比)20％，粉末中Ag含量小于80％，反应时间120min，水合肼浓度0．8％。实验表明所得颗粒是银包覆在BaTiO3表面的形成一定银层厚度的复合体系。     

金属表面硅烷化预处理制备聚乙烯涂层的研究

研究了KH 560硅烷偶联剂的水解工艺，采用不对硅烷水解平衡体系带来干扰和破坏的电导率测定法，在线检测硅烷的水解程度.利用水解后的KH 560硅烷溶液对低碳钢试件表面进行预处理，制备了聚乙烯（PE）涂层，对比了不同表面预处理工艺制备的PE涂层的结合强度.结果表明：由硅烷进行试件表面处理所得涂层的结合强度比用传统的砂纸打磨、酸洗、磷化、喷沙处理法分别高出了40.3%、46%、17.6%和13.2%，而涂层的断裂形式也有别于传统的处理方法，为内聚断裂；且PE涂层结合强度随着KH 560硅烷溶液浓度的增大反而下降.对于PE涂层的硅烷化处理，适宜的KH 560的浓度为5％左右，其水解时间为48 h.     

纳米银导电墨水的制备及电极性能研究

用硝酸银、己二酸二酰肼和葡萄糖为主要原料,通过化学还原法制备出粒径为30~50 nm的纳米银颗粒;将其分散于特殊配制比例的溶剂中,制备得到纳米银导电墨水。将纳米银导电墨水高精度图案化喷墨打印,分析了纳米银的形貌及其导电性能;研究了烧结温度和烧结时间对打印电极电阻率的影响,结果表明,200℃烧结40 min,电阻率为0.34 m?·cm的较低值。     

类银镜法高产量制备高稳定纳米银

以AgNO3为前躯体,葡萄糖为还原剂,十六烷基三甲基溴化铵(CTAB)为络合剂和分散剂,一步法制备纳米银溶胶。利用紫外-可见光分光光度计(UV-Vis)、透射电子显微镜(TEM)和X射线衍射仪(XRD)对银溶胶的形成、颗粒尺寸形貌、稳定性和晶体结构进行了表征。结果表明,CTAB与Ag+和H+发生络合反应,稳定了H+,促进了葡萄糖对Ag+的还原;所制备银纳米粒子以球形为主,分散性良好,粒径分布范围为10～40nm,银浓度高达0.025mol/L,室温条件下能够稳定5个月以上。