【作者】 赵青燕；

【导师】 吴松平；

【作者基本信息】 华南理工大学 ， 应用化学， 2011， 硕士

【摘要】 本文以内电极导电浆料为研究对象,采用掺杂氧化物及陶瓷材料的方式改善电极与基体之间的兼容性,提高导电层厚膜的致密度和附着力。用XRD、SEM、TMA等分析手段进行测试,对银厚膜相成分、微观结构及共烧后电性能进行了深入的研究,并探讨了体系微观结构的变化与导电性能之间的关系。主要内容如下:（1）研究了ZnO掺杂的银浆的性能。用掺杂ZnO的方法来调节银浆在与基体共烧时的收缩率,同时调节银晶粒的生长,得到完整均一的晶型,并研究了共烧后银厚膜的微观结构和电性能。实验发现,样品经过共烧试验后:在不掺杂任何助剂的情况下,银厚膜卷曲、分层,方阻高达1.14 m? /□;然而当加入2wt. % ZnO时,方阻减少到0.97 m?/□;当ZnO含量增至5wt. %时,方阻又开始变大至1.15m?/□。随着烧结温度的升高,银厚膜变得更加致密,方阻变小。当烧结温度为910°C时,银层对基体的附着力增加到0.85kgf·mm-2。在825-900℃烧结时,银晶粒的平均晶粒生长指数n为3.58,晶粒生长所需的平均活化能Q为47 kJ/mol,这表明银厚膜的晶粒生长机制为表面扩散机制。（2）研究了铁氧体掺杂及复合掺杂（ZnO-BaTiO₃、ZnO-SiTiO₃）银浆的性能,发现当掺杂4%铁氧体时,银层在900°C下具有好的烧结行为,其中铁氧体、BaTiO₃、SiTiO₃在银层的烧结收缩过程中均起到骨架作用。（3）开展了中试试验,在对氧化锌掺杂样品放大实验后存在的粘网、烧结不匹配问题进行了分析,优化了浆料配方、印刷工艺和烧结工艺等,进一步研究了复合掺杂氧化锌和钛酸钡的内电极浆料体系。通过复合掺杂制备的银浆样品经过丝网印刷、流延工艺后在880°C排胶烧结,获得了性能较好2012型磁珠器件,X-射线透射观察内电极引出端无内缩,电极附着良好。器件样品通过涂银封端、烘银烧银后,测得其电感量平均值为22.67μH（商用磁珠感量为19.5-32.5μH）。由此可知实验样品的电性能满足商用要求,自制银浆可以满足电感生产所需浆料性能要求。（4）研究了化学还原法制备银钯合金粉。探索了不同反应条件如反应温度、保护剂用量、银钯含量比等对银钯合金粉粒径、分散性的影响。实验发现,在55°C下还原的银钯合金粉为球形,具有好的单分散性;保护剂用量越高,获得的颗粒粒径越小;而钯含量越高,则容易造成团聚,难以获得分散性好的纳米颗粒,而且其浆料样品所需的共烧温度也较高。其中Ag95Pd05粉体配置成的浆料与陶瓷基体共烧,具有好的烧结匹配性,获得的电极层附着力好,厚膜致密。更多还原

【Abstract】 The inner electrode paste was selected as the research object. Doping oxides and ceramic materials is one of the ways to improve compatibility and increase the density and adhesive strength. The crystal microstructure and electrical properties of silver film were investigated by XRD, SEM and TMA. The relationship between the crystal microstructure and electrical properties was also discussed. Main contents of this paper were given as follows:（1） The property of ZnO-doped silver paste was investigated. ZnO could adjust the shrinkage of the paste during co-firing, regulate the growth of silver grains and get perfect crystal. We also discussed the microstructure and electrical properties of the silver thick film. It was found that the silver film cured without ZnO and the sheet resistivity was as high as1.14 m?/□; however, the sheet resistivity decreased to 0.97 m?/□as the content of ZnO increased to 2wt. %. When the content of ZnO increased to 5wt. %, the sheet resistivity increased to 1.15 m?/□. In addition, when the sintering temperature increased, we could get denser thick film, smaller sheet resistivity and high adhesive strength. The result showed that the adhesive strength was 0.85kgf·mm-2 at 910°C. From 825℃to 900℃, the grain growth exponent n was 3.58 and the average activation energy Q was 47 kJ/mol, which indicated that surface diffusion mass transportation was the main mechanism for grain growth.（2） The silver paste with different additives such as ferrite, ZnO-BaTiO₃, ZnO-SiTiO₃ was studied. The results showed that the thick film had good performance when 4wt. % ferrite was applied at 900℃. Ferrite, BaTiO₃ and SiTiO₃ played the role of skeleton during sintering.（3） The pilot tests were carried out. When ZnO-dopped silver paste was applied, the problems of sticking to nets and sintering mismatch were studied further. The formula of the silver paste, the printing technology and sintering technology were optimized. An excellent compatability between substrate and silver thick film was observed with X-ray radiochrometer. The silver layer with good attachment was confirmed. The samples of magnetic substrates were capped by brushing end silver paste, then dried and sintered. The average inductance of samples quantity was measured as 22.67μH, which could meet the commercial requirement. It showed that the silver paste could be used as inner electrode for MLCI.（4） The silver-palladium alloy powders were prepared by chemical reduction method. The influence of reaction conditions, such as temperature, the dosage of protective agent and the ratio of Ag-Pd, on Ag-Pd particle grain size and dispersibility was investigated. The result showed that we could obtain spherical silver-palladium alloy powder with good dispersibility at 55°C. The smaller size particles were obtained when the dosage of protective agent increased. When Ag95Pd05 paste was cofired with ceramic, denser film with good adhesive strength was obtained and the film had the same shrinkage to the ceramic substrate.更多还原