低压铝电解电容器用腐蚀箔结构模型探讨

Structural model of low-voltage etched foil for aluminum electrolytic capacitor

分析了日本高性能低压腐蚀箔结构-性能特征,在此基础上讨论了腐蚀箔结构模型,并采用压汞仪测试和固态铝电解电容器性能测试进行模型验证。结果表明,规格为U179H和LT23B腐蚀箔的性能差异主要是由于孔喉结构差异导致的。为了维持电荷中性,Cl^-离子倾向于聚集在蚀坑拐角处,促使拐角附近的薄弱点发生点蚀。而高浓度的Cl^-离子利于与Al^3+形成AlCl3盐膜,导致起蚀点附近的侧壁保持钝化状态,内部蚀坑呈现立方结构。立方蚀坑连接口处形成一个窄小的通道,影响腐蚀箔比容和固态铝电解电容器引出率。因此,降低低压箔的孔喉比参数是提升腐蚀箔性能的一个策略。

The structure-property characteristics of high-performance low-voltage etched foils of Japan were analyzed and the structural model was discussed in detail.The mercury porosimeter measurements and electrical performance test of solid-state aluminum electrolytic capacitor were adopted to verify the model.The results show that the performance difference between U179 H and LT23 B etched foils is mainly due to their different pore-throat structures.To maintain electrical neutrality,Cl-ions tend to accumulate at the corners of the pits,leading to pit initiation at weak points near the corners.Moreover,Cl-ions with high concentration facilitate the formation of AlCl3 salt film,which makes the sidewalls near the pitting point passivated and the internal pits structure kept the cubic structure.Consequently,a narrow channel is formed at the junction of the cubic etched cell,which affects the specific capacitance of the etched foil and the rate of capacitance withdrawing of the solid aluminum electrolytic capacitor.Therefore,it is a strategy to improve the performance of low-voltage etched foil by reducing the pore-throat ratio.