BACKGROUND

The present invention is related to an improved method of packaging a solid electrolyte capacitor and an improved capacitor formed thereby. More specifically, the present invention is related to improving the volumetric efficiency of a hermetically sealed capacitor by conformal hermetic elements.

Significant efforts are focused on increasing the volumetric efficiency of solid electrolytic capacitors. The volumetric efficiency of an electrolytic capacitor is typically defined as the ratio of the active capacitor volume to the volume of the entire encapsulated capacitor package. The anode lead wire typically extends axially from the anode to a lead frame and ultimately to an external termination. The wire, and connections thereto, occupy a significant non-contributory volume inside the capacitor package which is difficult to eliminate without creating other issues such as close approach of anodic and cathodic components of the capacitor.

U.S. Pat. No. 8,576,544, which is incorporated by reference, describes a method for increasing volumetric efficiency. The method involves the use of a ceramic housing. The ceramic housing itself leads to significant decrease in volumetric efficiency as the ceramic housing provides no capacitance yet does occupy a significant volume. Other prior art methods of hermetically sealing solid electrolytic capacitors involve placing capacitive elements inside one part of a preformed hermetic package such as a can, housing, sleeve, or flat substrate, and hermetically closing the package by attaching a preformed lid, seal, top, or housing. These methods have inherently low volumetric efficiency.

U.S. Pat. No. 3,343,047, which is incorporate herein by reference, is somewhat beneficial yet the entirety of the capacitor body is conductive which leads to mounting issues. Encasing the capacitor in polymeric resin is typically done yet this decreases volumetric efficiency as the polymeric resin occupies additional space without contribution to capacitance.

In spite of the ongoing efforts there is still a need for improvements in hermetically sealed capacitors.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a solid hermetically encased electrolytic capacitor with high volumetric efficiency.

A particular feature of the instant invention is the ability to manufacture the solid hermetically encased electrolytic capacitor without significant alterations to the manufacturing process.

These, and other advantages, as will be realized, are provided in a method of forming a capacitor. The method comprises forming an anode with an anode lead extending therefrom, forming a dielectric on the anode, forming a solid cathode layer on the dielectric and forming a hermetic encasement on the capacitor wherein the hermetic encasement comprises a conformal non-conductive layer.

Yet another embodiment is provided in a method of forming a hermetically encased capacitor. The method comprises forming an anode with an anode wire extending therefrom, forming a dielectric on the anode, inserting the anode wire through a cap, hermetically sealing the anode wire to the cap, forming a solid cathode layer on at least a portion of the dielectric and forming a conformal metal coating wherein the conformal metal coating is hermetically sealed to the cap.

Yet another embodiment is provided in a capacitor comprising an anode with an anode lead extending therefrom. A dielectric is on the anode and a solid cathode layer is on the dielectric. A hermetic encasement is on the capacitor wherein the hermetic encasement comprises a conformal non-conductive layer.

Yet another embodiment is provided in a hermetically encased capacitor. The capacitor comprises an anode with an anode wire extending therefrom wherein the anode wire extends through a cap and the anode wire is hermetically sealed to the cap. A dielectric is on the anode. A solid cathode layer is on at least a portion of the dielectric. A conformal metal coating is hermetically sealed to said cap.

