GB2077997A - Encapsulated capacitor - Google Patents
Encapsulated capacitor Download PDFInfo
- Publication number
- GB2077997A GB2077997A GB8106194A GB8106194A GB2077997A GB 2077997 A GB2077997 A GB 2077997A GB 8106194 A GB8106194 A GB 8106194A GB 8106194 A GB8106194 A GB 8106194A GB 2077997 A GB2077997 A GB 2077997A
- Authority
- GB
- United Kingdom
- Prior art keywords
- anode
- capacitor
- capacitor according
- termination means
- cathode
- 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.)
- Withdrawn
Links
- 239000003990 capacitor Substances 0.000 title claims abstract description 41
- 239000007787 solid Substances 0.000 claims abstract description 12
- 229910052751 metal Inorganic materials 0.000 claims abstract description 10
- 239000002184 metal Substances 0.000 claims abstract description 10
- 239000011241 protective layer Substances 0.000 claims abstract description 9
- 229920005989 resin Polymers 0.000 claims abstract description 9
- 239000011347 resin Substances 0.000 claims abstract description 9
- 241000219793 Trifolium Species 0.000 claims abstract 3
- 239000003792 electrolyte Substances 0.000 abstract description 5
- 229910052715 tantalum Inorganic materials 0.000 description 6
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 6
- 239000010410 layer Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 238000007598 dipping method Methods 0.000 description 3
- 239000003822 epoxy resin Substances 0.000 description 3
- 229920000647 polyepoxide Polymers 0.000 description 3
- 241000736305 Marsilea quadrifolia Species 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000008393 encapsulating agent Substances 0.000 description 2
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 230000001680 brushing effect Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 1
- 230000009931 harmful effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229920001568 phenolic resin Polymers 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 239000013034 phenoxy resin Substances 0.000 description 1
- 229920006287 phenoxy resin Polymers 0.000 description 1
- 239000011253 protective coating Substances 0.000 description 1
- 239000005060 rubber Substances 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 229920002050 silicone resin Polymers 0.000 description 1
- 229920002379 silicone rubber Polymers 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910052726 zirconium Inorganic materials 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
- H01G9/004—Details
- H01G9/04—Electrodes or formation of dielectric layers thereon
- H01G9/048—Electrodes or formation of dielectric layers thereon characterised by their structure
- H01G9/052—Sintered electrodes
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
Abstract
A electrolytic capacitor 10 includes a solid porous anode 20 having a channel 24 therein so as to reduce the quantity of metal in the anode and thereby minimise electrolyte resistance, the anode being encapsulated in a protective layer of resin 14. The channel may be a central hole or the external channels of a clover leaf cross-section. <IMAGE>
Description
SPECIFICATION
Encapsulated capacitor with minimum anode impedance
Generally speaking, the present invention pertains to a capacitor comprising a body including a solid porous anode of film forming metal characterized by a multiplicity of microscopic intercommunicating voids and permeated by at least one channel to reduce the quantity of metal in the anode, and cathode means substantially surrounding the anode; a protective layer of resin encapsulating the body; anode termination means extending from an internal portion of the anode; and cathode termination means extending from the cathode means at an outer surface of the body.
The present invention relates to an electrical capacitor of the electrolytic type having a porous sintered anode of a particular geometrical shape and wherein the anode as well as other elements of the capacitor are encapsulated in a protective layer of resin.
It is known in the tantalum capacitor art that superior electrical characteristics can be achieved when the anode is designed in such a manner as to reduce to a minimum the distance between any point within the anode and an external surface where contact to the electrolyte may be provided. In this way, the effects of electrolyte resistance within the anode are minimized resulting in an improved dissipation factor and a greater stability of capacitance over a wide range of frequencies. For example, there is described in U.S.
patent 3,345,545, issued October 3, 1967 a solid electrolytic tantalum capacitor having various anode shapes providing better electrical characteristics.
It is also known in the tantalum capacitor art to encapsulate the capacitor elements in a protective layer of resin helps protect the capacitor from harmful effects of the environment, including moisture and other contaminents and to help protect the capacitor from abusive handling. The encapsulant also provides a smooth regular appearance for the capacitor. For example, there is described in U.S. patent 3,049,904 issued
August 2, 1977 a tantalum capacitor that is encapsulated in an overcoating layer of resin.
Prior to the present invention, the two enumerated features have not been combined primarily because of the anticipated fabrication difficulties of covering the different anode configurations with the encapsulant.
Accordingly, it is a feature of the present invention to provide a capacitor having a solid porous anode having a configuration which provides better electrical characteristics and which is encapsulated in a protective coating of a resin. Another feature of the invention is to provide such a capacitor wherein the anode is permeated by at least one channel to reduce the quantity of metal in the anode. Another feature of the invention is to provide such a capacitor wherein the anode is a cylinder having a central bore therein. Yet another feature of the invention is the provision of such a capacitor wherein the bore is at least partially filled with the resin. Another feature of the invention is the provision of such a capacitor wherein the anode has a cross section which is in the form of a four leaf clover.Still another feature of the invention is the provision of such a capacitor wherein the anode termination means extends from an internal portion of the anode and the cathode termination means extends along an outer most surface of the anode. These and other features of the invention will become apparent from the following description taken in conjunction with the accompanying drawings.
Figure lisa cross section of one embodiment of the invention illustrating its features.
Figure 2 is a cross section taken along the line 2-2 of Figure 1.
Figure 3 is a cross section of another embodiment of the invention.
Figure 4 is a cross section taken along the line 4-4 of Figure 3.
Referring now to Figures 1 and 2, which illustrate one embodiment of the invention, a capacitor 10 includes a body 12 that is encapsulated in a protective layer 14, anode termination means 16 and cathode termination means 18. Body 12 includes a sintered porous anode 20 fabricated of a film forming metal and having a multiplicity of inter-communicating voids. Although not shown in detail, but as is well known in the art, body 12 also includes an appropriate dielectric oxide film and a solid electrolyte or conducting layer which together act as a cathode means for the capacitor.
Suitable materials for anode 12 are generally selected from the metals aluminium, titanium, tantalum, niobum or zirconium, and preferably tantalum. The conducting layers generally comprise a layer of manganese dioxide film next to the dielectric oxide film and one or more layers of graphite, solder, silver or other conducting materials.
The protective layer 14 should be composed of a material that is electrically insulative, has good resistance to mechanical shock, is able to withstand elevated temperatures, is relatively impervious to moisture and other contaminants in the atmosphere, is relatively inexpensive, and is able to be applied to capacitors by techniques such as dipping, molding, brushing, spraying and the like. Examples of such materials are epoxy resins, silicone resins and rubbers, phenoxy resins and phenolic resins.
In accordance with the present invention, porous anode 20 of body 12 takes a form which provides a minimum distance between any point within the anode and the surface where contact with the electrolyte is made, which is generally accomplished by permeating the solid anode with a channel to reduce the quantity of metal in the anode and the body is then encapsulated in the protective layer 14. In Figures 1 and 2, the anode takes the shape of a cylinder 22 having a centrally disposed bore 24. Anode termination means 16 extends from the internal portion 26 of the anode in an area about midway between the bore 24 and the outer surface of the cylinder. Cathode termination means 18 is in electrical contact with the cathode means of the capacitor at the outer surface of body 12. As shown, bore 24 is at least partially filled with the material of protective layer 14.
In the embodiment of capacitor 10' shown in Figures 3 and 4, anode 20' takes on the form of a four leaf clover 21 as viewed in cross section in Figure 3. Such structure provides for greater quantities of removed metal so as to further minimize the effects of electrolyte resistance. In this embodiment, anode termination means 16' extends from the center of the anode while the cathode termination means 16' extends from the outer surface of body 12' at the body's greatest diameter.
A number of capacitors fabricated according to the embodiment of Figures 1 and 2 were tested and compared with capacitors fabricated with a solid rectangular anode. Both types of capacitors were encapsulated by dipping into an epoxy resin. The results are tabulated in Table 1.
TABLE I
120 Hz 1000 Hz 100K Hz
Cap % DF Cap % DF ERS in ohms
227 4.5 220 28.0 .106
Solid 231 4.0 225 26.9 .090
Anode 229 4.5 222 28.6 .098
231 4.0 224 26.2 .095
229 4.8 221 30.6 .107
234 1.5 233 9.2 .060
Anode of 227 1.7 ' 225 9.0 .058
Figures 238 1.7 237 9.4 .060
1 and 2 234 1.5 233 8.9 .058
223 1.5 222 7.9 .055
A number of capacitors fabricated in accordance with the embodiment of Figures 3 and 4 were tested and compared with capacitors with the solid rectangular anode of Table I. Again, both types of capacitors were encapsulated by dipping into an epoxy resin. The results are shown in Table II.
TABLE II
120 Hz 1000 Hz 100K Hz
Cap % DF Cap % DF ERS in ohms
218 1.5 217 9.5 .056
217 1.3 215 8.4 .044
216 1.3 214 8.3 .045
216 1.3 215 7.7 .045
221 1.9 218 8.4 .044
214 1.9 212 8.1 .044
212 1.3 211 8.2 .045
216 1.3 215 8.5 .053
Referring to both Tables, the term % DF stands for Dissipation Factor which is a measure of power loss due to internal resistance. The lower the number the better is the performance of the capacitor. The term ERS, which is a standard measurement at high frequencies, stands for Equivalent Series Resistance and is a measure of the resistance of the capacitor. Again, the lower the number the better is the performance of the capacitor.
Examination of the tables clearly shows the better results obtained when using the anodes of the invention as compared to a standard solid rectangular anode.
Claims (7)
1. A capacitor comprising:
a) a body including a solid porous anode of film forming metal characterized by a multiplicity of microscopic intercommunicating voids and permeated by at least one channel to reduce the quantity of metal in said anode, and cathode means substantially surrounding said anode,
b) a protective layer of resin encapsulating said body,
c) anode termination means extending from an internal portion of said anode, and
d) cathode termination means extending from said cathode means at an outer surface of said body.
2. A capacitor according to claim 1 wherein said solid porous anode is a cylinder having a central bore therein.
3. A capacitor according to claim 2 wherein said bore is at least partially filled with said resin.
4. A capacitor according to claim 2 wherein said anode termination means extends longitudinally from said cylinder in an area about midway between said bore and an outer surface of said anode.
5. A capacitor according to claim 1 wherein said solid porous anode has a cross-section which is in the form of a clover leaf.
6. A capacitor according to claim 5 wherein said anode termination means extends from the center of said cross section.
7. A capacitor according to claim 6 wherein said cathode termination means extends from an outermost surface of the clover leaf cross section.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US15963180A | 1980-06-16 | 1980-06-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2077997A true GB2077997A (en) | 1981-12-23 |
Family
ID=22573330
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8106194A Withdrawn GB2077997A (en) | 1980-06-16 | 1981-02-27 | Encapsulated capacitor |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5713733A (en) |
| CA (1) | CA1155189A (en) |
| DE (1) | DE3111580A1 (en) |
| GB (1) | GB2077997A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4672512A (en) * | 1985-06-03 | 1987-06-09 | U.S. Philips Corporation | Solid electrolytic capacitor |
| GB2498066A (en) * | 2011-12-20 | 2013-07-03 | Avx Corp | Wet electrolytic capacitor comprising a channel along the length of the anode |
| US9324503B2 (en) | 2013-03-15 | 2016-04-26 | Avx Corporation | Solid electrolytic capacitor |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59200411A (en) * | 1983-04-27 | 1984-11-13 | 日本電気株式会社 | Tantalum electrolytic condenser anode element |
| JPS60153461A (en) * | 1984-01-20 | 1985-08-12 | Yanmar Diesel Engine Co Ltd | Air-fuel ratio controller for gas engine |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1083632A (en) * | 1952-06-26 | 1955-01-11 | Heraeus Gmbh W C | Electrolytic capacitor |
| US4068291A (en) * | 1976-04-12 | 1978-01-10 | Sprague Electric Company | Solid electrolyte capacitor with improved cathode lead |
| DE2631776C3 (en) * | 1976-07-15 | 1979-06-13 | Standard Elektrik Lorenz Ag, 7000 Stuttgart | Electrolytic capacitor |
| US4107762A (en) * | 1977-05-16 | 1978-08-15 | Sprague Electric Company | Solid electrolyte capacitor package with an exothermically-alloyable fuse |
-
1981
- 1981-02-18 CA CA000371129A patent/CA1155189A/en not_active Expired
- 1981-02-27 GB GB8106194A patent/GB2077997A/en not_active Withdrawn
- 1981-03-24 DE DE19813111580 patent/DE3111580A1/en not_active Ceased
- 1981-04-10 JP JP5421581A patent/JPS5713733A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4672512A (en) * | 1985-06-03 | 1987-06-09 | U.S. Philips Corporation | Solid electrolytic capacitor |
| GB2498066A (en) * | 2011-12-20 | 2013-07-03 | Avx Corp | Wet electrolytic capacitor comprising a channel along the length of the anode |
| GB2498066B (en) * | 2011-12-20 | 2015-09-23 | Avx Corp | Wet electrolytic capacitor containing an improved anode |
| US9275799B2 (en) | 2011-12-20 | 2016-03-01 | Avx Corporation | Wet electrolytic capacitor containing an improved anode |
| US9324503B2 (en) | 2013-03-15 | 2016-04-26 | Avx Corporation | Solid electrolytic capacitor |
Also Published As
| Publication number | Publication date |
|---|---|
| CA1155189A (en) | 1983-10-11 |
| JPS5713733A (en) | 1982-01-23 |
| DE3111580A1 (en) | 1982-04-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |