【作者】 沈腊珍；

【导师】 胡明；

【作者基本信息】 天津大学 ， 微电子学与固体电子学， 2007， 博士

【摘要】 电磁干扰（EMI）对全社会造成了危害,同时由于环氧模塑料（EMC）在电子封装上的广泛使用,使电磁干扰问题越来越严重。从电磁屏蔽材料的研究现状与发展趋势来看,导电聚吡咯（PPy）以电导率高、环境稳定性好、易于掺杂等特点可成为理想的电磁屏蔽材料。本课题以电子封装用电绝缘性环氧模塑料作为沉积PPy薄膜的基底,通过除油、粗化对基片表面的预处理和硅烷偶联剂对基片的表面改性,采用化学聚合的方法,在附有硅烷自组装膜的EMC基片表面制备得到了与基片紧密结合的均匀、连续、致密、具有良好导电性能、电磁屏蔽效能的导电PPy薄膜和兼具有磁性能和电性能的Fe₃O₄/PPy复合薄膜。使电子塑封材料具有电磁屏蔽效果,有很重要的理论和实际意义。研究了环氧模塑料表面除油和粗化处理的工艺条件,粗化温度为85℃,粗化30min可使环氧模塑料表面微观粗糙度达到最佳。硅烷偶联剂溶液中硅烷含量、pH值及基片在其中的浸渍时间等条件对硅烷自组装薄膜的质量有影响,一般浸渍时间为10s～20min。吡咯溶液和氧化剂FeCl₃溶液的初始浓度决定着吡咯聚合反应和过氧化反应的速率,对聚合时间及PPy薄膜的厚度、电导率、微观形貌有很大影响。探讨了PPy薄膜在EMC基片和硅烷自组装膜表面的形成机理。经过大量试验研究表明,吡咯溶液浓度和FeCl₃溶液浓度分别为4.82mol/L和1.8mol/L时,制得的PPy薄膜性能良好,电磁屏蔽效能实测值在30MHz～250MHz频率范围内为22dB左右,250MHz～1.5GHz范围内,约在17.5dB～20dB。掺杂阴离子存在最佳掺杂量（即饱和掺杂量）,在饱和掺杂量下掺杂离子能有效提高PPy分子链排列的规整性,使载流子浓度和迁移率都增大,得到较好电导率和致密性的PPy薄膜。如用I2、HClO₄、十二烷基苯磺酸钠、对甲苯磺酸钠掺杂后得到的PPy薄膜的导电率均达到了35S/cm以上,电磁屏蔽效能计算值在100K～1GHz的频率范围内均大于20dB,其中I2掺杂的PPy薄膜在低频下屏蔽效能达到了37dB,高频下约为26dB。合成出了Fe₃O₄粒子分散性好且粒径均匀的兼有磁性和导电性的Fe₃O₄/PPy复合薄膜,最大饱和磁化强度为10.59emu/g。不同电导率下复合膜呈现出不同的电磁屏蔽效果,低频下的SE计算值均大于25dB,频率达到10GHz时,Fe₃O₄含量为1.0g的复合膜的SE值接近100dB。更多还原

【Abstract】 The electromagnetic interference （EMI） brought a lot of harm to the world. And the broad use of epoxy molding compound （EMC） in electronic packaging materials produced more and more EMI problems. According to the status and development trend of EMI shielding materials, polypyrrole （PPy） shows a favorable application in EMI shielding because of its high electrical conductivity, outstanding stability and easy doping. In this study, insulating epoxy molding compound were used as the substrates for the depositing of PPy films. Conducting polypyrrole films with high electrical conducting and EMI shielding effectiveness and Fe₃O₄/PPy composite film with both magnetoconductivity and electrical conductivity were synthesized on the surface of EMC substrate attached with silane self-assembled monolayers （SAMs） by chemical polymerization, after the epoxy resin substrate surface being treated with contamination removing, coarsening and silane coupling agent modifying processes. The homogeneous, continuous and compact PPy film and Fe₃O₄/PPy composite film with EMI shielding effectiveness made the study have very important significance.Contamination removing and coarsening treatment condition were studied, the roughness degree of EMC substrates is the best at the coarsening temperature of 85℃for 30min. The silane content, pH value of silane coupling agent and dipping time of substrates in silane solution influence the quality of silane SAMs. Dipping time always is in the range of 10s～20min.The original concentration of pyrrole solution and oxidant FeCl₃ solution decide the rate of pyrrole polymerization and over oxidation reaction, and influence the polymerization time and the thickness, conductivity and morphology of PPy films greatly. The forming mechanism of PPy films on the surface of EMC substrates and silane self-assembled monolayers were discussed. Lots of experiments show that PPy films have favorite proerties when the concentration of pyrrole solution and FeCl₃ solution are 4.82mol/L and 1.8mol/L separately. And the measured EMI SE value of PPy film is about 22dB at the range of 30MHz～250MHz frequency and 17.5dB～20dB at the range of 250MHz～1.5GHz.There is the optimum doping concentration every dopant. Doping anion can make the PPy molecular chains arrange more regular, increase the concentration and move ratio of charge carrier in PPy chain at this saturation state. As a result, conductivity and compactness of PPy film have prominent increase. Such as, conductivity of PPy films doped by I2, HClO₄, SDBS and STS are all above 35S/cm, and calculated SE value is more than 20dB. Among them, the SE value of I2-doped PPy film get to 37dB at low frequency and 26dB at high frequency.Fe₃O₄/PPy composite films holding with magnetoconductivity and electrical conductivity were synthesized. Its saturation magnetization strength is 10.59emu/g. Particles of Fe₃O₄ with uniform size dispersed in the composite film. Fe₃O₄/PPy composite films with different conductivity show varied EMI shielding effectiveness. The SE values of composite films are more than 25dB at low frequency, and SE near to 100dB at 10GHz when the content of Fe₃O₄ is 1.0g.更多还原