Wet electrolytic capacitor for an implantable medical device
AssigneeAVX Corporation
InventorsJan Petrzilek, Ilja Michalin
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Abstract
A wet electrolytic capacitor that contains a cathode, fluidic working electrolyte, and anode that includes a sintered porous pellet is provided. A dielectric layer is also formed on a surface of the pellet and within its pores through anodic oxidation. The present inventors have discovered that through selective control over the anodic oxidation process, a substantially amorphous, low crystalline dielectric layer can be formed which, among other things, exhibits a leakage current that is smaller than previously thought possible for the high voltage capacitors employed in implantable medical devices.
Claims19
A wet electrolytic capacitor comprising:
- an anode that comprises a pellet formed from a pressed and sintered tantalum powder, the tantalum powder comprising primary particles having a median size (D50) of about 5 nm to about 250 nm, wherein a tantalum pentoxide dielectric layer is formed on the pellet that has no more than about 1,000 crystals per square millimeter or less;
- a cathode that comprises a metal substrate coated with a conductive coating;
- and
- a fluidic working electrolyte in communication with the anode and the cathode.
A method for forming a wet electrolytic capacitor, the method comprising forming an anode that comprises a pellet formed from a pressed and sintered tantalum powder, the tantalum powder comprising primary particles having a median size (D50) of about 5 nm to 250 nm, wherein a tantalum pentoxide dielectric layer is formed on the pellet that has no more than about 1,000 crystals per square millimeter or less by subjecting the sintered anode pellet to a formation profile, wherein the formation profile includes subjecting the pellet to an increasing current so that a target forming voltage is achieved in about 30 minutes or less, and positioning the anode and a fluidic working electrolyte within a casing,
- wherein the wet electrolytic capacitor further comprises a cathode that comprises a metal substrate coated with a conductive coating;
- and a fluidic working electrolyte in communication with the anode and the cathode.
Dependencies are inferred from the claim text.