Solid electrolytic capacitor containing a multi-layered adhesion coating
A solid electrolytic capacitor that contains an anode body, dielectric located over and/or within the anode body, an adhesion coating overlying the dielectric, and a solid electrolyte overlying the dielectric and adhesion coating that contains a conductive polymer. The adhesion coating is multi-layered and employs a resinous layer in combination with a discontinuous layer containing a plurality of discrete nanoprojections of a manganese oxide (e.g., manganese dioxide).
1. A solid electrolytic capacitor comprising:
an anode body;
a dielectric that overlies the anode body;
an adhesion coating that overlies the dielectric, wherein the adhesion coating contains a discontinuous precoat layer and a resinous layer, wherein the discontinuous precoat layer contains a plurality of discrete nanoprojections of a manganese oxide; and
a solid electrolyte that overlies the dielectric and the adhesion coating, wherein the solid electrolyte includes a conductive polymer layer, and wherein one or more discrete manganese oxide nanoprojections are embedded in the solid electrolyte.
2. The solid electrolytic capacitor of claim 1 , wherein the anode body includes tantalum and the dielectric includes tantalum pentoxide.
3. The solid electrolytic capacitor of claim 1 , wherein the nanoprojections have an average size of from about 5 nanometers to about 500 nanometers.
4. The solid electrolytic capacitor of claim 1 , wherein about 50% or more of the nanoprojections have an average size of from about 10 nanometers to about 110 nanometers.
5. The solid electrolytic capacitor of claim 1 , wherein the surface coverage of the nanoprojections is from about 0.1% to about 40%.
6. The solid electrolytic capacitor of claim 1 , wherein the manganese oxide is manganese dioxide.
7. The solid electrolytic capacitor of claim 1 , wherein the precoat layer overlies the dielectric and the resinous layer overlies the precoat layer.
8. The solid electrolytic capacitor of claim 1 , wherein the resinous layer overlies the dielectric and the precoat layer overlies the resinous layer.
9. The solid electrolytic capacitor of claim 1 , wherein the resinous layer includes a natural or synthetic resin.
10. The solid electrolytic capacitor of claim 9 , wherein the resin is formed from shellac.
11. The solid electrolytic capacitor of claim 1 , wherein the conductive polymer layer includes poly(3,4-ethylenedioxythiophene).
12. The solid electrolytic capacitor of claim 1 , wherein the capacitor exhibits an ESR of about 300 milliohms or less as determined at a frequency of 100 kHz and a normalized leakage current of about 0.2 μA/μF*V or less.