Electrolytic capacitor assembly containing a resettable fuse
A fused electrolytic capacitor assembly that offers improved performance characteristics in a convenient and space-saving package is provided. More specifically, the fused electrolytic capacitor assembly contains an electrolytic capacitor element and a resettable fuse contained within a case. The capacitor assembly also contains a stress absorbing material that is positioned adjacent to and in contact with the resettable fuse. By selecting a stress absorbing material having a certain modulus and a certain degree of inherent flexibility, the present inventors believe the resettable fuse is better able to expand to its full capacity upon exposure to an excessive current. In this manner, the resettable fuse is able to better function during use.
1. A fused electrolytic capacitor assembly comprising:
an electrolytic capacitor element comprising an anode and solid electrolyte overlying the anode, wherein an anode lead extends from the anode;
a resettable fuse electrically connected to the electrolytic capacitor element, the resettable fuse containing a positive temperature coefficient (“PTC”) material;
a stress absorbing material covering at least a portion of the resettable fuse;
a cathode termination that is electrically connected to the solid electrolyte;
an anode termination that is electrically connected to the anode lead; and
a case that encapsulates the electrolytic capacitor element and the resettable fuse and leaves at least a portion of the anode and cathode terminations exposed.
2. The fused electrolytic capacitor assembly of claim 1 , wherein the electrolytic capacitor element contains an anode formed from a valve metal composition.
3. The fused electrolytic capacitor assembly of claim 2 , wherein the valve metal composition includes tantalum.
4. The fused electrolytic capacitor assembly of claim 2 , wherein the valve metal composition includes niobium oxide.
5. The fused electrolytic capacitor assembly of claim 1 , wherein the solid electrolyte contains manganese oxide.
6. The fused electrolytic capacitor assembly of claim 1 , wherein the solid electrolyte contains a conductive polymer.
7. The fused electrolytic capacitor assembly of claim 1 , further comprising a dielectric layer formed between the anode and the solid electrolyte.
8. The fused electrolytic capacitor assembly of claim 1 , wherein the PTC material contains an electrically conductive filler contained within a polymer matrix.
9. The fused electrolytic capacitor assembly of claim 1 , wherein the PTC material contains a ceramic.
10. The fused electrolytic capacitor assembly of claim 1 , wherein the resettable fuse further comprises one or more electrode members positioned adjacent to the PTC material.
11. The fused electrolytic capacitor assembly of claim 1 , wherein the stress absorbing material has a modulus of elasticity of about 1,000 Megapascals or less.
12. The fused electrolytic capacitor assembly of claim 1 , wherein the stress absorbing material has a modulus of elasticity of from about 50 to about 500 Megapascals.
13. The fused electrolytic capacitor assembly of claim 1 , wherein the stress absorbing material includes a polyorganosiloxane.
14. The fused electrolytic capacitor assembly of claim 1 , wherein the stress absorbing material includes a bis-maleimide resin.
15. The fused electrolytic capacitor assembly of claim 1 , wherein the stress absorbing material further includes a polymer and a filler.
16. The fused electrolytic capacitor assembly of claim 1 , further comprising a conductive adhesive layer that is positioned between and electrically connects the electrolytic capacitor element and the resettable fuse.
17. The fused electrolytic capacitor assembly of claim 1 , wherein the resettable fuse is electrically connected to the cathode termination.
18. The fused electrolytic capacity assembly of claim 17 , further comprising a conductive adhesive layer that is positioned between and electrically connects the resettable fuse and the cathode termination.
19. The fused electrolytic capacitor assembly of claim 17 , wherein the stress absorbing material covers at least a portion of the cathode termination.
20. The fused electrolytic capacitor assembly of claim 1 , wherein the stress absorbing material is positioned between the resettable fuse and at least a portion of the cathode termination or the anode termination.
21. The fused electrolytic capacitor assembly of claim 1 , wherein the resettable fuse is electrically connected to the anode termination.
22. A method of forming a fused electrolytic capacitor assembly, the method comprising:
providing an electrolytic capacitor element comprising an anode and solid electrolyte overlying the anode, wherein an anode lead extends from the anode;
electrically connecting the solid electrolyte to a cathode termination;
electrically connecting the anode lead to an anode termination;
electrically connecting a resettable fuse to the electrolytic capacitor element, the resettable fuse containing a positive temperature coefficient (“PTC”) material;
covering at least a portion of the resettable fuse with a stress absorbing material; and
encapsulating the electrolytic capacitor element and the resettable fuse so that at least a portion of the anode termination and the cathode termination remains exposed.
23. The method of claim 22 , wherein the valve metal composition includes tantalum or niobium oxide.
24. The method of claim 22 , wherein the PTC material contains an electrically conductive filler contained within a polymer matrix.
25. The method of claim 22 , wherein the stress absorbing material has a modulus of elasticity of about 1,000 Megapascals or less.
26. The method of claim 25 , wherein the stress absorbing material is applied as an emulsion.
27. The method of claim 22 , wherein the resettable fuse is connected to the electrolytic capacitor element with a conductive adhesive.
28. The method of claim 22 , further comprising electrically connecting the resettable fuse to the cathode termination or anode termination.
29. The method of claim 28 , wherein the resettable fuse is connected to the cathode termination or anode termination with a conductive adhesive.
30. The method of claim 28 , wherein the stress absorbing material covers at least a portion of the cathode termination or anode termination.