Electrochemically Etched Tantalum Foils as Anode for Tantalum Electrolytic Capacitors

Embedded passives hold promising potential in electronic industry for its advantage of saving the surface area on integrated circuit boards and diminishing parasitic inductance. However, the current embedded capacitor structure can only offer low capacitance. Tantalum (Ta) capacitors have high specific capacitance, but its application as embedded capacitors is restricted by the huge thickness of Ta electrolytic capacitors, which is mainly caused by the sintering process of Ta anode. Therefore, we employ electrochemical etching as a new method to fabricate Ta anode, so as to reduce the thickness of Ta electrolytic capacitor, and to facilitate the application of Ta electrolytic capacitor as embedded capacitors. Besides, double-sided electrolytic capacitor structure can be designed based on electrochemically etched Ta anode, which can double its capacitance while lower the equivalent serial resistance.