摘要
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.
To improve the conductivity of the copper pastes,the surface-treated copper powders were used as the main conductive phases,and a small amount of graphene flakes was used as the conductive reinforced phases to prepare the composite electronic pastes. The effect of the specifications and additions of graphene flakes on conductivity were characterized by four-point probe,scanning electron microscopy(SEM) and other testing methods. The results show the pastes with the graphene flakes with a thickness of 3 ~ 5 nm and a flake size of 5 μm has a smaller resistivity after sintered at 460 ℃. When the mass ratio of graphene flakes and copper powders is 2.98,the resistivity of the pastes is measured to be 17.14 mΩ·cm,50.22% lower than that of the copper pastes(34. 43 mΩ ·cm). The conductive mechanism of the electronic pastes is revealed and geometric model of connection of the conductive phases is established. In the conductive film,the gaps between copper powders are filled by the broken graphene flakes and bridges are jointed between copper powders by longer graphenehe flakes,causing the formation of a compact microstructure and excellent conductive network. Thus the conductivity of the pastes is dramatically improved.
引文
[1]史泰冈,祁红璋,严彪.电子浆料材料的研究进展及其在印刷电路板方面的应用[J].上海有色金属,2012,33(3):145-147.SHI Taigang,QI Hongzhang,YAN Biao.Research progress of electronic paste and its application in printed circle board industry[J].Shanghai Nonferrous Metals,2012,33(3):145-147.
[2]MIR I,KUMAR D.Recent advances in isotropic conductive adhesives for electronics packaging applications[J].International Journal of Adhesion and Adhesives,2008,28(7):362-371.
[3]罗世永,庞远燕,郝燕萍,等.电子浆料用有机载体的挥发性能[J].电子元件与材料,2006,25(8):49-51.LUO Shiyong,PANG Yuanyan,HAO Yanping,et al.Volatility of organic vehicle for electronic paste[J].Electronic Components&Materials,2006,25(8):49-51.
[4]陆广广,宣天鹏.电子浆料的研究进展与发展趋势[J].金属功能材料,2008,15(1):48-52.LU Guangguang,XUAN Tianpeng.Development tendency and research progress of the electronic paste[J].Metallic Functional Materials,2008,15(1):48-52.
[5]刘新峰,屈银虎,郑红梅,等.铜电子浆料的抗氧化研究和进展[J].应用化工,2014,43(8):1493-1496.LIU Xinfeng,QU Yinhu,ZHENG Hongmei,et al.Progress on oxidation resistance of copper paste[J].Applied Chemical Industry,2014,43(8):1493-1496.DOI:10.16581/j.cnki.issn1671-3206.2014.08.052
[6]王晓霞,叶红齐,苏周,等.超细铜粉的制备与应用[J].材料导报,2004,18(专辑III):140-142.WANG Xiaoxia,YE Hongqi,SU Zhou,et al.The preparation and application of ultrafine copper powder[J].Materials Review,2004,18(Special III):140-142.
[7]刘晓琴,苏晓磊.铜电子浆料的研究发展现状[J].硅酸盐通报,2013,32(12):2502-2513.LIU Xiaoqin,SU Xiaolei.Research progress and developments of conductive copper paste[J].Bulletin of the Chinese Ceramic Society,2013,32(12):2502-2513.DOI:10.16552/j.cnki.issn1001-1625.2013.12.047
[8]彭舒,唐振方,吉锐.电子浆料中微米级铜粉的抗氧化研究[J].表面技术,2008,37(3):6-8.PENG Shu,TANG Zhenfang,JI Rui.Study on the antioxidation capability of micro copper powder in organic medium[J].Surface Technology,2008,37(3):6-8.DOI:10.16490/j.cnki.issn.1001-3660.2008.03.011
[9]徐磊,张宏亮,刘显杰.电子浆料研究进展[J].船电技术,2012,32(增刊2):141-144.XU Lei,ZHANG Hongliang,LIU Xianjie.Reviews on electronic paste[J].Marine Electric&Electronic,2012,32(suppl 2):141-145.DOI:10.3969/j.issn.1003-4862.2012.z2.043
[10]SULKA G D,JASKULA M.Study of the kinetics of silver ionscementation on to copper from sulphuricacid solution[J].Hydrometallugy,2005,77(1/2):131-137.
[11]卢雪琼,王军,王亚平,等.铜及其合金高温氧化的影响因素研究[J].材料导报,2012,26(增刊2):371-374.LU Xueqiong,WANG Jun,WANG Yaping,et al.Influence factors on high temperature oxidation study for Cu and Cu-based alloys[J].Materials Review,2012,26(Suppl 2):371-374.
[12]ZHANG Rongwei,MOON K,LIN Wei,et al.Preparation of highly conductive polymer nanocomposites by low temperature sintering of silver nanoparticles[J].Journal of Materials Chemistry,2010,20(10):2018-2023.
[13]MIZUNO M,SAKA M,ABE H.Mechanism of electrical conduction though anisotropically conductive adhesive films[J].IEEE Transactions on Components,Packaging and Manufacturing Technology Part A,1996,19(4):546-553.
[14]廖辉伟,李翔,彭汝芳,等.包覆型纳米铜-银双金属粉研究[J].无机化学学报,2003,19(12):1327-1330.LIAO Huiwei,LI Xiang,PENG Rufang,et al.Study on Ag coating Cu nano bimetallic powders[J].Chinese Journal of Inorganic Chemistry,2003,19(12):1327-1330.
[15]罗艳,周康根,肖妍艳.导电浆料用铜粉的表面改性及其性能[J].材料与冶金学报,2006,5(2):119-124.LUO Yan,ZHOU Kanggen,XIAO Yanyan.Surface modification and properties of copper powder for conductive paste[J].Journal of Materials and Metallurgy,2006,5(2):119-124.
[16]LEONG C K,CHUNG D D L.Carbon black dispersions as thermal pastes that surpass solder in providing high thermal contact conductance[J].Carbon,2003,41(13):2459-2469.
[17]RANE S,PURI V,AMALNERKAR D.A study on sintering and micro-structure development of fritless silver thick film conductors[J].Journal of Materials Science,2000,11(9):667-674.
[18]曹海华,康坚.石墨烯片的性能及应用研究[J].内蒙古石油化工,2015(2):16-18.