【作者】 冯哲圣；

【导师】 杨邦朝；

【作者基本信息】 电子科技大学 ， 微电子学与固体电子学， 2003， 博士

【摘要】 高比容铝电极箔制造技术是实现铝电解电容器小型化的关键技术，本论文从提高铝电极箔电蚀扩面倍率及提高介质膜介电常数两个不同角度出发，对低压铝电极箔增容技术的机理及相关工艺进行了详细研究，大幅度地提高了国产铝电极箔比容水平，所取得的主要结论及创新性的结果如下：1、提出了高纯铝在腐蚀性介质体系中发生点蚀时，蚀核萌生机制和蚀孔生长机制：研究了高纯铝在不同条件下点蚀萌生时的恒电位下电化学电流噪声行为，结果表明：蚀核的萌生主要来自于高纯铝表面膜结构内部与表面的活性点；这些活性点主要与高纯铝表面膜结构与电化学条件相关，而与溶液组成并无直接关系；蚀核的萌生是高纯铝表面膜结构中活性点与侵蚀性离子的相互作用的结果。活性点能否萌生为蚀核受溶液中侵蚀性离子的攻击作用与缓蚀性离子的保护作用共同影响，因此也受溶液组成的影响；浓度的增加可提高蚀核的萌生几率，而离子的加入则大幅度降低了高纯铝在含溶液中蚀核萌生几率。 2、对高纯铝交流腐蚀机理进行了研究，首次提出了氧空位输运侵蚀机制，以及氧空位缓蚀作用机制：采用三角波动电位扫描法研究了高纯铝交流腐蚀机理，提出了通过存在于侵蚀膜内微晶晶界上的氧空位输运，从而对铝基体进行侵蚀的机制。并利用上述机制对相关实验现象进行了解释。 对在铝电极箔电蚀扩面工程中缓蚀作用机理进行了研究，指出的独特缓蚀作用为：在点蚀萌生时，通过氧空位阻断机制阻止蚀孔萌生，但一旦蚀孔生成，促进蚀孔迅速增大，同时蚀孔内发孔数量增加。因此一定量的添加有利于铝电极箔海绵层结构的生成。 3、建立了YF基元生长模型对铝电极箔理论扩面倍率进行了计算：针对已有的铝电极箔理论扩面倍率计算模型不能准确反映中低压铝电极箔的海绵状蚀孔特征的缺点，提出了YF基元生长模型对铝电极箔理论扩面倍率进行了较为准确地计算。结果表明：目前实际的扩面倍率在高压部分与理论扩面<WP=6>倍率很接近，但在中低压部分实际扩面倍率与理论扩面倍率相差较大。因此高压铝电极箔通过电蚀扩面提高比容的前景较小，而对于中低压铝电极箔，提高单位面积静电容量的余地还很大。 4、研究了交流发孔工艺：发孔工艺是铝电极箔电蚀扩面工程中的关键工艺，本文分析对比了低压铝电极箔交流发孔工艺与直流发孔工艺。对交流发孔工艺进行了工艺研究，优选出了一套较好的交流发孔工艺参数，该工艺与常规蚀孔生长工艺进行配套后，腐蚀箔比容在时可达到18.8。 5、研究了高介电常数的介质膜生长技术：提高铝电极箔介质膜的介电常数可大幅度地提高铝电极箔比容。本文研究了一系列与目前工业联动腐蚀、化成线具有良好兼容性的后处理增容技术，并对相关机制进行了研究。其中经过磷酸—铬酸处理或胺类溶液处理，提高铝氧化膜内或的含量，在合适的工艺条件下，国产铝电极箔比容在51下分别可增容37.5%和35%。首次提出并研究了通过无机盐水解的技术途径在铝介质膜内复合高介电常数阀金属氧化物，在实验室工艺条件下，铝电极箔比容在51下可增容45.6%。目前该技术已申请国家发明专利。6、将小波及小波包信号分解及重构引入测试信号的分析处理中，取得了良好效果：在高纯铝点蚀机理的研究方面，首次提出了电化学噪声小波包分解子带能量谱分析技术，该分析技术具有表现电化学噪声信号“指纹”特征的能力，对腐蚀体系、腐蚀类型及腐蚀状态都具有较强的敏感性。对高纯铝变频腐蚀机制所进行的研究中，采用小波包时频分解，证明了高纯铝变频腐蚀动力学机制仍服从Tafel关系。首次基于小波包分解与信号重构方法，给出了在进行变频腐蚀动力学机制研究中动力学参数的实时测量方法。更多还原

【Abstract】 Recent development of small electronic devices requires increase in capacitance of aluminum electrolytic capacitors. Higher capacitance can be obtained with enlarging surface area of aluminum foils and increasing the dielectric constant of dielectric films on aluminum foils. The main goal of this paper is to investigate the mechanism of corresponding processes for increasing capacitance of aluminum foils used for low-voltage aluminum electrolytic capacitors. The important results and innovations are as follows:1. The pit corrosion initiation and growth mechanism of high-purity aluminum in the corrosive media was studied.The galvanostat electrochemical current noises of high-purity aluminum in different corrosive media were studied. It was found that pit corrosion mostly initiates from the active spots in and on the passive film. These active spots mostly correlate with the surface structure and electrochemical environment of high-purity aluminum, not directly with the composition of solution. Pit initiation is the result of the interaction between active spots and corrosive ions such as Cl- and so on. Whether active spots become corrosion nuclei is influenced by impact from corrosive ions and protection from inhibitive ions, so, by the composition of solution. Increasing the concentration of Cl- enhances pits initiation probability, and addition of SO42- greatly decreases pits initiation probability of high-purity aluminum in the corrosive media.2. AC corrosion mechanism of high-purity aluminum was studied. The mechanism of Cl- penetrating through the passive film by oxygen-vacancy-chain and the inhibition mechanism of SO42- were first explained.AC corrosion mechanism of high-purity aluminum was studied by means of cyclic triangular wave potentiodynamic method. The mechanism was proposed that Cl- penetrates through the passive film by oxygen-vacancy-chain in the crystalline boundary, and impacts aluminum substrate. According to this mechanism, the corresponding experimental phenomena were explained. <WP=8>The inhibition mechanism of SO42- in the AC corrosion of high-purity aluminum was studied. Under the effect of local electric field, O2- that dissociated from SO42- captures the oxygen vacancy, decreases the concentration of oxygen vacancies, and modifies the network of Cl- penetrating ways in the passive film. So, a certain amount of SO42- addition is advantageous to the generation of the sponge structure on aluminum foils.3. The YF model was proposed, and the theoretical surface roughness factor of aluminum foils was calculated.A model for calculating the theoretical surface roughness factor K of aluminum foils was developed. The simulation results showed that the morphology of etched aluminum foils is similar to the actual one, and the surface roughness factor K obtained by calculating units trace is approximate to the practical one of aluminum foils for high-voltage use. However, the K value of aluminum foils for low-voltage use is larger than the practical one. This suggests that it is possible to further increase the capacitance of low-voltage aluminum capacitors. 4. The technologies of pits initiation process were studied. How to control the pits initiation is a very important problem in the surface enlarging processes of aluminum foils by electrochemical etching. This paper contrasted AC pits initiation process with DC pits initiation process. The technical parameters of AC pits initiation process were optimized. As the result, the capacitance of etched aluminum foils can be obtained up to 18.8 at the rated withstanding voltage of 51V by normal pit growth processes.5. The fabricating technologies of high dielectric constant oxide films were studied.To increasing the capacitance of Aluminum foils, increase in the dielectric constant of dielectric films is as important as increase in surface area. This paper studied a series technology, which are compatible with the current etching and formation linkage line, for fabricating high dielectric constant oxide films on aluminum更多还原