Solid electrolytic capacitor with integrated fuse assembly
A solid electrolytic capacitor with an integrated fuse assembly is provided. The fuse can be secured in a recess formed in a face of the porous anode body of the capacitor. When the fuse is secured in the recess, the fuse can be substantially flush with the face of the porous anode body in which the recess is formed. Further, the equivalent series resistance (ESR) of the fuse is reduced because the length of the connection between the fuse and the porous anode body is reduced. Further, because the fuse is integrated into the porous anode body, the capacitor can be assembled onto a circuit board via standard pick and place equipment.
1. A solid tantalum capacitor comprising:
a capacitor body having a tantalum wire lead and a recess;
a fuse assembly that includes a fuse with two terminations and an adhesive material for securing the fuse in the recess;
a connection assembly that includes an electrically conductive material that connects one of the fuse terminations to the capacitor body;
a plating that coats the terminations and conductive material; and
a conformal coating that encases at least the capacitor body.
2. The solid electrolytic capacitor of claim 1 , further comprising an anode termination that is electrically connected to the tantalum wire lead and a cathode termination that is electrically connected to the electrically conductive material.
3. The solid electrolytic capacitor of claim 1 , wherein the adhesive material is insulative.
4. The solid electrolytic capacitor claim 1 , wherein the conductive material comprises a mass of conductive silver.
5. The solid electrolytic capacitor of claim 1 , wherein the plating comprises nickel.
6. The solid electrolytic capacitor of claim 1 , wherein the capacitor body comprises a sintered, porous anode body, a dielectric layer overlying at least a portion of the porous anode body, and a cathode overlying at least a portion of the dielectric layer, the cathode including a solid electrolyte.
7. The solid electrolytic capacitor of claim 6 , wherein the solid electrolyte comprises a conductive polymer, wherein the conductive polymer comprises a plurality of pre-polymerized conductive polymer particles applied as a dispersion.
8. The solid electrolytic capacitor of claim 6 , wherein the solid electrolyte comprises a conductive polymer, wherein the conductive polymer is applied through in situ polymerization.
9. The solid electrolytic capacitor of claim 6 , wherein the solid electrolyte includes manganese dioxide.
10. The solid electrolytic capacitor of claim 6 , wherein the capacitor body further comprises an external polymer coating that overlies the solid electrolyte, wherein the external polymer coating contains a plurality of pre-polymerized conductive polymer particles.
11. The solid electrolytic capacitor of claim 1 , wherein the capacitor body has a height, a width, and a depth and the recess has a height, a width, and a depth, wherein the ratio of the height of the porous anode body to the height of the recess is from about 1.25 to about 5, the ratio of the width of capacitor body to the width of the recess is from about 1.25 to about 5, or the ratio of the depth of the capacitor body to the depth of the recess is from about 2 to about 10.
12. A solid electrolytic capacitor comprising:
a capacitor body that comprises a sintered, porous anode body, a dielectric layer overlying at least a portion of the porous anode body, and a cathode overlying at least a portion of the dielectric layer, the cathode including a solid electrolyte, wherein a recess is formed in a face of the capacitor body;
an anode lead; and
a fuse, wherein the fuse is secured in the recess such that the fuse is substantially flush with the face of the capacitor body in which the recess is formed, wherein the capacitor body and fuse are coated in a nickel plating.
13. The solid electrolytic capacitor of claim 12 , wherein the porous anode body includes tantalum, niobium, or an electrically conductive oxide thereof.
14. The solid electrolytic capacitor of claim 12 , wherein an insulating adhesive material secures the fuse in the recess.
15. The solid electrolytic capacitor of claim 12 , wherein the fuse has a first termination and second termination.
16. The solid electrolytic capacitor of claim 15 , wherein a first mass of electrically conductive material electrically connects the first termination to the capacitor body.
17. The solid electrolytic capacitor of claim 15 , wherein the second termination is isolated from the capacitor body by an insulating adhesive material.
18. The solid electrolytic capacitor of claim 15 , wherein a second mass of electrically conductive material electrically connects the second fuse termination to a cathode termination.
19. The solid electrolytic capacitor of claim 12 , wherein the capacitor body and the fuse are coated with a conformal coating.
20. The solid electrolytic capacitor of claim 12 , further comprising an anode termination that is electrically connected to the anode lead.
21. A method for forming a solid electrolytic capacitor having an integrated fuse, the method comprising:
embedding an anode lead within a powder formed from a valve metal composition;
compacting the powder around the anode lead to form a pellet, wherein a portion of the anode lead extends from a surface of the pellet and a recess is formed in a face of the pellet;
sintering the pellet to form a porous anode body;
anodically oxidizing the sintered anode body to form a dielectric layer;
applying a solid electrolyte to the anodically oxidized sintered anode body to form a capacitor body;
securing a fuse in the recess, wherein the fuse is substantially flush with the face in which the recess is formed;
electrically connecting the fuse to the capacitor body using an electrically conductive material;
applying a plating over the solid electrolyte and fuse; and
applying a conformal coating over the plating.