银纳米结构及其对导电胶电性能影响研究

发布时间：2019-06-19 05:21

【摘要】：导电胶是电子元器件封装、电极和互联的关键材料,主要用于表面封装技术和敏感元件等电子行业的各个领域。随着电子元器件向微型化、多功能化和柔性化等方向发展,国内外正在开展金属导电填料纳米化的研究。其中,纳米银填充导电胶成为该领域的研究热点。目前,纳米银作为导电填料对导电胶性能的影响是正面还是负面结论不统一,还有很多不完善的地方和不确定性有待研究和解决。本论文首先采用液相还原法和溶剂热法分别制备了类球形纳米银颗粒、纳米银线和纳米银片,然后采用自制不同形貌纳米银单独或与商用微米银片复合作为导电填料制备各向同性导电胶,研究纳米银形貌、填量、表面性质和烧结行为等对导电胶电性能的影响,并分析了纳米银填充导电胶的导电机理。首先,采用传统的液相还原法室温制备了30~50 nm的类球形纳米银颗粒,采用溶剂热法制备了平均直径450 nm、长度20~70μm的纳米银线和长度100~300 nm纳米银片;采用戊二酸乙醇溶液对纳米银进行表面处理;研究了表面处理前后纳米银的烧结特点。实验结果表明,经过戊二酸处理后,纳米银颗粒易于团聚,纳米银线尺寸变短,纳米银片未发生明显变化。表面吸附的羧酸基团与纳米银间存在物理和化学键合两种作用。三种纳米银表面处理后烧结温度均下降。其次,制备了商用微米银片填充导电胶,研究了固化工艺与导电胶体积电阻率间的关系。实验结果表明,低温长时间固化有利于提高银胶导电性。高固化温度有利于改善低银含量银胶的导电性。后固化热处理对已固化完全的样品的导电性和微观结构的影响不大。最后,研究了不同形貌的纳米银单独或者与微米银片复合作为导电填料对导电胶电性能的影响。纯纳米银线填充导电胶研究表明,纳米银线能够促进导电胶的固化,缩短内部导电通路的形成时间,降低固化温度。当纳米银线含量只有35wt%时,导电胶在168℃固化后的体积电阻率为9.48×10-4Ω·cm,300℃固化后的体积电阻率降低至8.21×10-5Ω·cm。在纳米银线中掺杂纳米银颗粒复合填充导电胶,不仅固化过程中导电网络形成时间延长,且电阻增加。当纳米银线和纳米银颗粒的含量为65 wt%时,导电胶180℃固化后的体积电阻率只有1.37×10-4Ω·cm,300℃固化体积电阻率也只有9.60×10-5Ω·cm。但高温烧结或者表面处理有利于改善纳米银线-纳米银颗粒复合填充导电胶的电性能。将纳米银线与微米银片复合作为导电填料制备导电胶,研究表明,引入纳米银线后,缩短了基体内导电网络的形成时间,而且也降低了固化温度。在较高的固化温度下能够明显降低体积电阻率。当银含量为75 wt%、固化温度为250℃时,电阻率为6.72×10-5Ω·cm,相对于75 wt%微米银片导电胶电阻率降低约2倍。将纳米银颗粒或纳米银片与微米银片复合作为导电填料制备导电胶,研究表明,纳米银颗粒或纳米银片的加入,在低温固化时体积电阻率明显增加,但表面经戊二酸处理后的纳米银颗粒可以减弱导电性降低的程度。高温固化时,由于纳米银的烧结行为使颗粒间连接起来形成导电通路,从而改善了导电性。
[Abstract]:The conductive adhesive is a key material for electronic component packaging, electrode and interconnection, and is mainly used in various fields of electronic industry such as surface packaging technology and sensitive element. With the development of electronic components in the direction of miniaturization, multi-function and flexibility, the research on the nano-scale of metal conductive filler is being carried out at home and abroad. In which, the nano-silver-filled conductive adhesive has become a hot spot in the field. At present, the influence of nano-silver as the conductive filler on the performance of the conductive adhesive is positive or negative, and there are many imperfections to be studied and solved. in that invention, the spherical nano-silver particle, the nano-silver wire and the nano-silver film are respectively prepared by adopting a liquid-phase reduction method and a solvothermal method, The influence of the filling amount, the surface property and the sintering behavior on the electrical properties of the conductive adhesive is analyzed, and the conductive mechanism of the nano-silver-filled conductive adhesive is also analyzed. firstly, a traditional liquid-phase reduction method is adopted to prepare the spherical nano-silver particles with the diameter of 30-50 nm, the nano-silver wire with the average diameter of 450 nm and the length of 20-70 & mu; m and the nano-silver film with the length of 100-300nm are prepared by a solvothermal method, and the nano-silver is subjected to surface treatment by adopting the glutaric acid ethanol solution; The sintering characteristics of nano-silver before and after surface treatment were studied. The experimental results show that the nano-silver particles are easy to agglomerate after the glutaric acid treatment, the size of the nano-silver wire is short, and the nano-silver film does not change obviously. There are two effects of physical and chemical bonding between the surface-adsorbed acid groups and the nano-silver. And the sintering temperature after the three nano-silver surface treatment is reduced. The relationship between the curing process and the volume resistivity of the conductive adhesive was studied. The experimental results show that the low-temperature long-time curing is beneficial to the improvement of the conductivity of the silver paste. The high curing temperature is favorable for improving the conductivity of the silver paste with low silver content. The post-curing heat treatment has little influence on the conductivity and microstructure of the cured complete sample. In the end, the effect of the nano-silver on the electrical properties of the conductive adhesive was studied by using the nano-silver as a conductive filler. The research shows that the nano-silver wire can promote the curing of the conductive adhesive, shorten the forming time of the internal conductive path and lower the curing temperature. When the content of the nano-silver wire is only 35% by weight, the volume resistivity of the conductive adhesive after curing at 168 DEG C is 9.48-10-4惟路 cm, and the volume resistivity after curing at 300 DEG C is reduced to 8.21-10-5惟路 cm. In that nano-silver wire, the nano-silver particle composite fil conductive adhesive is doped, so that the formation time of the conductive network in the curing process is prolonged, and the resistance is increased. When the content of the nano-silver wire and the nano-silver particles is 65% by weight, the volume resistivity of the conductive adhesive at the temperature of 180 DEG C is only 1.37-10-4惟路 cm, and the curing volume resistivity at the temperature of 300 DEG C is only 9.60-10-5惟路 cm. But the high-temperature sintering or surface treatment is beneficial to improving the electrical property of the nano-silver wire-nano-silver particle composite-filled conductive adhesive. The conductive adhesive is prepared by compounding the nano silver wire and the micron silver sheet as the conductive filler, and the research shows that after the nano silver wire is introduced, the forming time of the conductive network in the base body is shortened, and the curing temperature is also reduced. The bulk resistivity can be significantly reduced at higher curing temperatures. When the silver content is 75% by weight and the curing temperature is 250.degree. C., the resistivity is 6.72 to 10 to 5. O The conductive adhesive is prepared by compounding the nano-silver particles or the nano-silver film and the micron silver sheet as a conductive filler, But the nano-silver particles with the surface treated by the glutaric acid can reduce the conductivity and reduce the conductivity. In the case of high-temperature curing, the conductive path is formed between the particles due to the sintering behavior of the nano-silver, so that the conductivity is improved.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;TQ437.6

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