Method for manufacturing a high voltage tantalum anode

Patent metadata

Field	Value
Publication number	US-RE47560-E
Application number	US-201715596784-A
Country	US
Kind code	E1
Filing date	May 16, 2017
Priority date	Sep 6, 2013
Publication date	Aug 6, 2019
Grant date	Aug 6, 2019

Abstract

Tantalum powders produced using a tantalum fiber precursor are described. The tantalum fiber precursor is chopped or cut into short lengths having a uniform fiber thickness and favorable aspect ratio. The chopped fibers are formed into a primary powder having a controlled size and shape, narrow/tight particle size distribution, and low impurity level. The primary powder is then agglomerated into an agglomerated powder displaying suitable flowability and pressability such that pellets with good structural integrity and unifrom pellet porosity are manufacturable. The pellet is sintered and anodized to a desired formation voltage. The thusly created capacitor anode has a dual morphology or dual porosity provided by a primary porosity of the individual tantalum fibers making up the primary powder and a larger secondary porosity formed between the primary powders agglomerated into the agglomerated powder.

First claim

What is claimed is:

1. A method for providing an anode for a high voltage implantable electrolytic capacitor, the method comprising the steps of:
a) providing tantalum fibers having a diameter ranging from 0.5 μm to 2.5 μm and a length ranging from 5 μm to 50 μm; b) providing a primary tantalum powder as a loosely packed mass of the tantalum fibers; c) agglomerating the primary tantalum powder into a randomly oriented, substantially non-aligned, porous agglomerated tantalum powder; d) pressing the agglomerated tantalum powder into a tantalum pellet of a desired shape; e) sintering the tantalum pellet into a coalesced body of the tantalum fibers to thereby provide a sintered tantalum pellet; and f) anodizing the sintered tantalum pellet to a formation voltage of at least 300 V to form an anode having a dielectric oxide on the tantalum fibers.

2. The method of claim 1 including providing the tantalum fibers having an length:diameter aspect ratio of 10 to 40.

3. The method of claim 1 including providing the tantalum fibers having a length:diameter aspect ratio of 2 to 100.

4. The method of claim 1 including providing the agglomerated tantalum powder having an agglomerated density ranging from 1.5 g/cc to 4.5 g/cc.

5. The method of claim 1 including providing the agglomerated tantalum powder having a d50 agglomerated diameter distribution ranging from 200 μm to 500 μm.

6. The method of claim 1 including providing the agglomerated tantalum powder having an agglomerate diameter distribution at d10: of 74 μm to d90: of 1,000 μm.

7. The method of claim 1 including providing the agglomerated tantalum powder having a d50 agglomerate pore size ranging from 1 μm to 5 μm.

8. The method of claim 1 including providing agglomerated tantalum powder having an agglomerate pore distribution d10: of 0.5 μm and d90: of 20 μm.

9. The method of claim 1 including providing the tantalum pellet having a pressed density of 3 g/cc to 8 g/cc.

10. The method of claim 1 including sintering the tantalum pellet at a temperature ranging from 1,200° C. to 2,200° C.

11. The method of claim 1 including sintering the tantalum pellet for a time ranging from 0.1 minutes to 120 minutes.

12. The method of claim 1 including sintering the tantalum pellet at a vacuum of <1×10 −4 Torr (Argon).

13. The method of claim 1 including providing the sintered tantalum pellet having a sintered density ranging from 4 g/cc to 9 g/cc.

14. The method of claim 1 including providing the sintered tantalum pellet having a d50 inter-granule size distribution ranging from 1 μm to 5 μm.

15. The method of claim 1 including providing the sintered tantalum pellet having a d50 intra-granule size distribution ranging from 30 μm to 80 μm.

16. The method of claim 1 including providing the sintered tantalum pellet having a d10 inter-granular pore distribution ranging from 0.5 μm to 2 μm and a d90 inter-granular pore distribution ranging from 3 μm to 10 μm.

17. The method of claim 1 including providing the sintered tantalum pellet having a d10 intra granule pore distribution ranging 20 μm to 40 μm a d90 intra granule pore distribution ranging from 60 μm to 100 μm.

18. The method of claim 1 including anodizing the sintered tantalum pellet to a formation voltage ranging from 300 V to 550 V.

19. A method for providing an anode for a high voltage implantable electrolytic capacitor, the method comprising the steps of:
a) providing tantalum fibers having a diameter ranging from 0.5 μm to 2.5 μm and a length ranging from 5 μm to 50 μm to thereby provide the tantalum fibers having a length:diameter aspect ratio ranging from 2 to 100; b) loosely packing the tantalum fibers to provide a tantalum powder; c) agglomerating the tantalum powder into a randomly oriented, substantially non-aligned agglomerated tantalum powder having a primary density ranging from 1.5 g/cc to 4.5 g/cc, the agglomerated tantalum powder comprising:
i) a d50 agglomerate diameter distribution ranging from 200 μm to 500 μm;
ii) a d50 agglomerate pore size ranging from 1 μm to 5 μm;
iii) an agglomerate diameter distribution at d10 of 74 μm and at d90 of 1,000 μm; and
iv) an agglomerate pore size distribution at d10 of 0.5 μm and at d90 of 20 μm;
d) pressing the agglomerated tantalum powder into a tantalum pellet having a secondary density ranging from 4 g/cc to 6.5 g/cc; e) sintering the tantalum pellet to thereby provide a sintered tantalum pellet having a sintered density ranging from 4 g/cc to 9 g/cc, the sintered tantalum pellet comprising:
i) an inter-granule pore size distribution attributed to the sintered density at:
d10 ranging from 0.5 μm to 2 μm;
d50 ranging from 1 μm to 5 μm; and
d90 ranging from 3 μm to 10 μm; and

ii) an intra-granule pore size distribution attributed to the sintered density at:
d10 ranging from 20 μm to 40 μm;
d50 ranging from 30 μm to 80 μm; and
d90 ranging from 60 μm to 100 μm; and

f) anodizing the sintered tantalum pellet to a formation voltage of at least 300 V up to 550 V to thereby provide the tantalum anode.

20. The method of claim 19, including providing the tantalum fibers having a length:diameter aspect ratio ranging from 10 to 40.

21. The method of claim 19, wherein, prior to being pressed into the tantalum pellet, including the step of providing the agglomerated tantalum powder having an agglomerated density ranging from 2.5 g/cc to 3.5 g/cc.

22. The method of claim 19, including the step of sintering the tantalum pellet at a temperature ranging from 1,200° C. to 2,200° C.

23. The method of claim 19, including the step of sintering the tantalum pellet for a period ranging from 0.1 minutes to 120 minutes.

24. The method of claim 19, including the step of sintering the tantalum pellet at a vacuum of <1×10 −4 Torr (Argon).

25. The method of claim 19, wherein, prior to anodizing to form the tantalum anode, including the step of providing the tantalum pellet having a sintered density ranging from 5 g/cc to 8 g/cc.

26. The method of claim 19, wherein, prior to anodizing to form the tantalum anode, including the step of providing the sintered tantalum pellet having a d50 intra-granule pore size attributed to the secondary porosity ranging from 30 μm to 80 μm.

27. A method for providing an anode for a high voltage implantable electrolytic capacitor, the method comprising the steps of:
a) providing tantalum fibers having a length:diameter aspect ratio ranging from 2 to 100; b) loosely packing the tantalum fibers to provide a tantalum powder; c) agglomerating the tantalum powder into a randomly oriented, substantially non-aligned agglomerated tantalum powder having a primary density ranging from 2.5 g/cc to 3.5 g/cc, the agglomerated tantalum powder comprising:
i) a d50 agglomerate diameter distribution ranging from 200 μm to 500 μm;
ii) a d50 agglomerate pore size ranging from 2 μm to 3 μm;
iii) an agglomerate diameter distribution at d10 of 74 μm and at d90 of 1,000 μm; and
iv) an agglomerate pore size distribution at d10 of 0.5 μm and at d90 of 20 μm;
d) pressing the agglomerated tantalum powder into a tantalum pellet having a secondary density ranging from 4 g/cc to 6.5 g/cc; e) sintering the tantalum pellet to thereby provide a sintered tantalum pellet having a sintered density ranging from 5 g/cc to 8 g/cc, the sintered tantalum pellet comprising:
i) an inter-granule pore size distribution attr

Assignees

• Greatbatch Ltd

Inventors

• Liu Yanming
• Muffoletto Barry C
• Hahl Jason T

Classifications

• B22F1/148

  Agglomerating · CPC title

• B22F3/02

  Compacting only · CPC title

• B22F3/24

  After-treatment of workpieces or articles {(B22F3/1146 takes precedence)} · CPC title

• B22F1/0096

  Operations & Transport · mapped topic

• H01G9/02

  Diaphragms; Separators · CPC title