GB2058735A - Solid electrolytic capacitors - Google Patents
Solid electrolytic capacitors Download PDFInfo
- Publication number
- GB2058735A GB2058735A GB8029900A GB8029900A GB2058735A GB 2058735 A GB2058735 A GB 2058735A GB 8029900 A GB8029900 A GB 8029900A GB 8029900 A GB8029900 A GB 8029900A GB 2058735 A GB2058735 A GB 2058735A
- Authority
- GB
- United Kingdom
- Prior art keywords
- anode
- solution
- layer
- oxide layer
- salt
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000003990 capacitor Substances 0.000 title claims abstract description 15
- 239000007787 solid Substances 0.000 title description 2
- 150000003839 salts Chemical class 0.000 claims abstract description 21
- 229910052751 metal Inorganic materials 0.000 claims abstract description 17
- 239000002184 metal Substances 0.000 claims abstract description 17
- 238000010438 heat treatment Methods 0.000 claims abstract description 11
- 230000001939 inductive effect Effects 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims description 40
- 239000000243 solution Substances 0.000 claims description 24
- 229910044991 metal oxide Inorganic materials 0.000 claims description 22
- 150000004706 metal oxides Chemical class 0.000 claims description 22
- 238000004519 manufacturing process Methods 0.000 claims description 10
- 239000012266 salt solution Substances 0.000 claims description 7
- 238000000576 coating method Methods 0.000 claims description 3
- 239000011248 coating agent Substances 0.000 claims description 2
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical compound [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 abstract description 14
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 abstract description 12
- 238000005979 thermal decomposition reaction Methods 0.000 abstract description 12
- 230000000694 effects Effects 0.000 abstract 1
- 238000000354 decomposition reaction Methods 0.000 description 12
- 238000009740 moulding (composite fabrication) Methods 0.000 description 7
- 239000007864 aqueous solution Substances 0.000 description 3
- 239000006227 byproduct Substances 0.000 description 3
- 230000006698 induction Effects 0.000 description 3
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 239000004411 aluminium Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000010924 continuous production Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- AMWRITDGCCNYAT-UHFFFAOYSA-L hydroxy(oxo)manganese;manganese Chemical compound [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 description 2
- 229910000464 lead oxide Inorganic materials 0.000 description 2
- YEXPOXQUZXUXJW-UHFFFAOYSA-N oxolead Chemical compound [Pb]=O YEXPOXQUZXUXJW-UHFFFAOYSA-N 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 230000035882 stress Effects 0.000 description 2
- 229910052715 tantalum Inorganic materials 0.000 description 2
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 2
- 230000008646 thermal stress Effects 0.000 description 2
- 238000009736 wetting Methods 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- IOVCWXUNBOPUCH-UHFFFAOYSA-N Nitrous acid Chemical compound ON=O IOVCWXUNBOPUCH-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- -1 lead oxide Chemical class 0.000 description 1
- 229940093474 manganese carbonate Drugs 0.000 description 1
- 235000006748 manganese carbonate Nutrition 0.000 description 1
- 239000011656 manganese carbonate Substances 0.000 description 1
- 229910000016 manganese(II) carbonate Inorganic materials 0.000 description 1
- XMWCXZJXESXBBY-UHFFFAOYSA-L manganese(ii) carbonate Chemical compound [Mn+2].[O-]C([O-])=O XMWCXZJXESXBBY-UHFFFAOYSA-L 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- GQPLMRYTRLFLPF-UHFFFAOYSA-N nitrous oxide Inorganic materials [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/0029—Processes of manufacture
- H01G9/0036—Formation of the solid electrolyte layer
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The dielectric oxide layer e.g. of manganese dioxide of a dry electrolytic capacitor anode is produced by inductive heating of the anode whilst immersed in a solution of the corresponding metal salt e.g. manganese nitrate to effect thermal decomposition on the anode surface.
Description
SPECIFICATION
Solid electrolytic capacitors
This invention relates to a process of manufacturing dry electrolytic capacitors and to capacitors made by the process.
In manufacturing dry electrolytic capacitors there are used anodes of a valve metal, such as of aluminium, tantalum, niobium, or any similar metal, which may have the shape of a foil or of a sintered body. These anodes are provided with a dielectric oxide layer by an electrolytic forming process. On this dielectric oxide layer of dry electrolytic capacitors there is then produced a cathode layer consisting of a semiconducting metal oxide, such as of manganese dioxide or lead oxide. This layer of semiconducting metal oxide is obtained, as a rule, by wetting the anode with the solution of a corresponding metallic salt, which is followed by a thermal decomposition of the metallic salt way of heating, for resulting in the metal oxide. The wetting may be carried out in such a way that the anode is dipped into the corresponding metallic-salt solution.For producing a manganese dioxide layer, for example, there is used an aqueous solution of manganese nitrate or else of a permanganate which the, when heated up to 200 to 4000C, decomposes to manganese oxide. During the decomposition of the usually employed aqueous manganese nitrate, there are formed besides the manganese dioxide, still nitric oxides and hydrogen.
When employing this conventional process it is not possible, without further processing, to obtain a continuous layer of the semiconducting metal oxide because during the decomposition of the salt there are formed gaseous byproducts preventing the precipitation of a continuous layer.
Moreover, during the heating, thermal stresses occur in the dielectric oxide layer which lead to cracks in this layer, thus becoming the cause of an inadmissible increase of the residual current of the capacitor. Therefore, one is compelled, after the thermal decomposition of the metallic salt, to reform the dielectric oxide layer and to supplement the semiconducting layer by repeating the impregnating and decomposition process.
Repeating these alternating re-forming and coating processes several times involves a considerable expense particularly as after each forming process the forming electrolyte must be completely removed from the anode before a further step of the process for producing a semiconducting oxide layer can be carried out.
Such a cleaning involves a considerable additional cost especially in the case of anodes consisting of porous sintered bodies. Also, in the laminated layer system on the anode, owing to the alternating heating and cooling, there are always produced new stresses which not only favour the formation of faults in these layers, but also decrease the mutual adherence of the layers to one another which, in turn, leads to an increased loss angle of the capacitor.
Normally, the thermal decomposition is carried out in an oven heated to the respective temperature and in which, for achieving a favourable decomposition product, is provided with a special atmosphere, for example, there must exist a predetermined water-vapour concentration. In the course of this, gaseous aggressive decomposition products, such as the nitric oxides, must be removed from the oven and neutralized in order to avoid damage to the operating persons and the environment. This, however, renders it more difficult to maintain a constant decomposition temperature inside the oven.
Attempts have also already been made for achieving an improved saturation of anodes of porous sintered bodies in such a way that the anodes, prior to the immersion into the manganese nitrate solution, are heated. Such a process is disclosed in DE-AS 1,108,811 and 1,216,434. This, however, does not basically change the process of manufacturing the semiconducting metal oxide, because the thus saturated anodes are then heated in the usual way inside an oven up to 400 or 5000C for achieving the decomposition of the manganese nitrate.
Finally, it is known to carry out the thermal decomposition of the manganese nitrate on the anode in such a way that the anode is heated inside an induction heater up to a temperature ranging between 300 and 3500C. Such a process is disclosed in the German Patent No. 1,127,480.
This, however, does not basically change anything of the process for manufacturing the semiconducting metal oxide layer, so that also in this case the anodic treatment and the decomposition must still be carried out several times running.
It is the object of the present invention to improve the process of manufacturing the semiconducting metal oxide layer by way of thermal decomposition of a corresponding metallic salt.
According to one aspect of the invention, there is provided a process for manufacturing dry electrolytic capacitors, wherein on the anode of valve metal provided with a dielectric oxide layer, there is produced a layer of a semiconducting metal oxide, wherein the anode is immersed into a solution of a corresponding metallic salt, with the metallic salt being decomposed by inductive heating of the anode, whilst so immersed, so as to form the metal oxide thereon.
According to another aspect of the invention there is provided a process for coating a dielectric oxide coated valve metal body with a layer of a metal oxide, the process including heating the body in a solution of a corresponding metallic salt to a temperature at which the salt decomposes to form the oxide.
The process uses a solution of a corresponding metallic salt which, during thermal decomposition, is changed into a semiconducting metal oxide. For example, an aqueous solution of manganese nitrate can be used for producing a layer of manganese dioxide. Apart from manganese
nitrate, also other metallic salts, such as permanganates can be used for producing a manganese dioxide layer. For producing layers of other metal oxides, such as lead oxide, there are used correspondingly other metallic salts. It is also not absolutely necessary to use aqueous solutions, as also suitable solvents may be used.
The capacitor anodes are dipped in a cold state into the respective metallic-salt solution and inductively heated in this solution, so that in the course of this, the metallic salt on the anode decomposes thermally within the solution and forms the desired semiconducting metal oxide layer.
Moreover, the process offers the added advantage that gaseous byproducts resulting from the thermal decomposition, are immediately absorbed by the solution so that they, on one hand, do not prevent fresh metallic-salt solution from having access to the anode, and, on the other hand, the removal of these often detrimental gases is without any problem. Thus, for example, during the decomposition of manganese nitrate, there are produced nitric oxides, the removal of which gives rise to industrial safety and environmental-protection problems.
In the process described herein these nitric oxides are absorbed by the solution and converted to either nitrous or nitric acid. By adding
manganese carbonate such a solution may be reconditioned, so that again manganese nitrate is formed. The carbon-dioxide resulting as a byproduct, is completely harmless.
Another feature of the process is that the anode is not heated to such an extent that the metallicsalt solution on the surface of the anode forms vapour bubbles which would prevent the solution from having access to the surface of the anode.
The thermal stress, in particular of the dielectric oxide layer, in the present process therefore is substantially smaller than that experienced in prior art processes, so that there will also not occur any damage to or cracks in the dielectric oxide layer. In this way, a re-forming of the dielectric oxide layer is rendered superfluous.
The process distinguishes from the conventional processes as disclosed in DE-AS 1,108,81 according to which heated anodes are dipped into an aqueous manganese-nitrate solution. Apart from the fact that in this conventional process, there is subsequently carried out a thermal decomposition at 5100C, hence outside the manganese-nitrate solution, the anodes as heated to 51 00C, when dipped into the manganese nitrate solution, are subjected to a considerable sudden cooling again causing stresses in the dielectric oxide layer.Moreover, vapour bubbles are formed in the course of this on the surface of the anode preventing the manganese-nitrate solution from having access to the anode; until the anode is cooled down to a temperature below 10000. Considering that no further energy is supplied to the dipped anode, it continues to cool down, so that practically no thermal decomposition will take place on the surface of the anode. The same also applies to the process disclosed in DE-AS 1,216,434.
In the present process, in order to avoid an excessive heating of the anodes in the solution of the metallic salt, the energy applied to the anode by way of induction, must be dimensioned and controlled accordingly. It has proved to be particularly advantageous to apply the inductive energy not permanently to the anode, but in the form of more or less long energy pulses with interruptions inbetween. Thus, it is possible in a simple way to control the energy supply accordingly.
While the conventional process for producing the semiconducting metal oxide layer can only be carried out under great difficulties in the course of a continuous process, because between the individual decomposition processes, re-formings and cleanings are always again required, the present process can be carried out continuously in a very simple way. For example, a tape of valve metal, such as aluminium or tantalum, provided with a dielectric oxide layer, is passed continuously through the metallic-sait solution, and with the aid of a suitably arranged induction coil, this tape is inductively heated within a solution. In this way it is possible to produce continuously a semiconducting metal oxide layer on such a tape.
The continuous process, however is not only suitable for tapes of valve metal, as sintered bodies of electro-chemical valve metal may be used equally well for this purpose, which are then connected with their anode terminal wires in the way known per se, to a corresponding transporting tape (of the conveyor-belt type).
In the present process the heating and, consequently, also the thermal decomposition of the metallic-salt solution on the anode can be locally restricted. It is therefore possible to attach to the anode lead wire of valve metal, prior to the electrical forming, a terminal wire of non-valve metal. This was not possible with the conventional methods used hitherto, because during the thermal decomposition for producing the semiconducting oxide layer, it was unavoidable that in the decomposition space also metal oxide would precipitate on the terminal wire of nonvalve metal, thus ncessarily causing an electric short circuit between the anode and the cathode.
In the present process it is possible to dip the anodes provided with the lead wire, only to such an extent into the metallic-salt solution, that the connecting point between the anode wire of valve metal and the lead wire of non-valve metal remains outside the solution, thus preventing a semiconducting metal oxide layer from precipitating or depositing at this point.
Accordingly, it is possible to restrict the precipitation (deposition) of the semiconducting metal oxide layer clearly to those points of the anode which are coated with the dielectric oxide layer. From this there results a further simplification of the process of manufacturing dry electrolytic capacitors.
By suitably selecting the metallic salt to be decomposed, as well as the concentration of the metallic salt in the solution, and by selecting a suitable solvent, it is possible to select the boiling point of the metallic-salt solution and, consequently, the upper limit of the decomposition temperature in a suitable way.
Claims (7)
1. A process for manufacturing dry electrolytic capacitors, wherein on the anode of valve metal provided with a dielectric oxide layer, there is produced a layer of a semiconducting metal oxide, wherein the anode is immersed into a solution of a corresponding metallic salt, with the metallic salt being decomposed by inductive heating of the anode, whilst so immersed, so as to form the metal oxide thereon.
2. A process as claimed in claim 1 , wherein said inductive heating is carried out discontinuously.
3. A process as claimed in claims 1 or 2, wherein a tape of valve metal provided with a dielectric oxide layer, is continuously passed through said metallic-salt solution, and is heated on its way within the solution.
4. A process as claimed in any one of claims 1 to 3, wherein the anodes, prior to the production of the semiconducting metal oxide layer, are provided with terminals of a non-valve metal.
5. A process for coating a dielectric oxide coated valve metal body with a layer of a metal oxide, the process including heating the body in a solution of a corresponding metallic salt to a temperature at which the salt decomposes to form the oxide.
6. A process for manufacturing a dry electrolytic capacitor substantially as described herein.
7. A dry electrolytic capacitor manufactured by a method as claimed in any one of the preceding claims.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19792938340 DE2938340C2 (en) | 1979-09-21 | 1979-09-21 | Process for the production of solid electrolytic capacitors |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2058735A true GB2058735A (en) | 1981-04-15 |
| GB2058735B GB2058735B (en) | 1983-02-16 |
Family
ID=6081540
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8029900A Expired GB2058735B (en) | 1979-09-21 | 1980-09-16 | Solid electrolytic capacitors |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS5655030A (en) |
| DE (1) | DE2938340C2 (en) |
| GB (1) | GB2058735B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6893572B2 (en) | 2001-07-12 | 2005-05-17 | Western Environmental Engineering Company | Solids accumulating flotation separator |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3127660A (en) * | 1964-04-07 | gerondeau | ||
| DE1103104B (en) * | 1957-05-18 | 1961-03-23 | Philips Nv | Method and device for the electrolytic formation of a strip of film-forming metal, in particular of electrode foils for electrolytic capacitors |
| DE1108811B (en) * | 1958-04-02 | 1961-06-15 | Western Electric Co | Method of manufacturing a tantalum electrolytic capacitor |
| DE1216434B (en) * | 1963-12-26 | 1966-05-12 | Union Carbide Corp | Method for manufacturing an electrolytic capacitor with solid electrolyte |
| JPS5143617A (en) * | 1974-10-11 | 1976-04-14 | Mitsubishi Electric Corp | |
| JPS52133403A (en) * | 1976-05-04 | 1977-11-08 | Hitachi Ltd | Grand steam condenser safeguard |
-
1979
- 1979-09-21 DE DE19792938340 patent/DE2938340C2/en not_active Expired
-
1980
- 1980-09-16 GB GB8029900A patent/GB2058735B/en not_active Expired
- 1980-09-19 JP JP13055780A patent/JPS5655030A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6893572B2 (en) | 2001-07-12 | 2005-05-17 | Western Environmental Engineering Company | Solids accumulating flotation separator |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2058735B (en) | 1983-02-16 |
| DE2938340A1 (en) | 1981-03-26 |
| DE2938340C2 (en) | 1982-12-09 |
| JPS5655030A (en) | 1981-05-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |