CA1142611A - Meltable washer for anode protector - Google Patents
Meltable washer for anode protectorInfo
- Publication number
- CA1142611A CA1142611A CA000335157A CA335157A CA1142611A CA 1142611 A CA1142611 A CA 1142611A CA 000335157 A CA000335157 A CA 000335157A CA 335157 A CA335157 A CA 335157A CA 1142611 A CA1142611 A CA 1142611A
- Authority
- CA
- Canada
- Prior art keywords
- anode
- riser
- assembly
- polyhalogenated
- anode assembly
- 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.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-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
- H01G9/008—Terminals
- H01G9/012—Terminals specially adapted for solid capacitors
Abstract
ABSTRACT
An anode assembly for a capacitor including a sintered anode, an anode riser extending from the anode and a nodule adheringly bonded to both the anode riser and the pellet. The nodule comprises an electrically insulating polymeric polyhalo-genated hydrocarbon material, and a method of making the anode assembly.
An anode assembly for a capacitor including a sintered anode, an anode riser extending from the anode and a nodule adheringly bonded to both the anode riser and the pellet. The nodule comprises an electrically insulating polymeric polyhalo-genated hydrocarbon material, and a method of making the anode assembly.
Description
FIELD OF THE INVENT~ON
- The invention relates to an anode assembly for a capacitor, and more particularly to an anode assembly incorporating a nodule of an electrically insulating material comprising a polyhalogenated hydrocarbon capable of forming a melt at between about 150C and ~50C with repeating units having the formula:
~X~
~ xn~
wherein n is a whole number equal to or greater than 2 and wherein x represents substituents, a predominant portion of which within each repeating unit are fluorine and at least one of which in each repeating unit is a substituent selected from the group consisting of chlorine, bromine, hydrogen, -RYm, -ORYm~ and mixtures thereof, wherein Y represents halogen or hydrogen or a mixture thereof, R is a chain having 1~6 carbon atoms, and m represents the requisite number of hydrogen or halogen atoms necessary to complete the chain.
BACKGROUND OF THE INVENTION
Many capacitors, including solid tantalum capacitors, use a porous metal pellet as an anode. These pellets are manufactured by pressing and then sintering a metal powder into a rigid mass. The anode is usually manufactured from a film forming metal. Film forming metal powders such as tantalum, aluminum, titanium, zirconium or niobium, can be formed into a porous pellet for use as an anode by a sintering process employed with other metals.
Either before or after sintering, a wire riser is inserted into or attached to the anode to form an anode assembly. The wire riser conducts electricity to and from the anode during use.
~ 1 _ ;26~
After the attachment of the riser and the sintering of the pellet, the anode assembly is ready for further manufacturing steps, such as anodizing the anode, manganese dioxide (MnO2) deposition, riser-wire cut off, and welding of the riser wire to a terminal. The anode assembly is further processed by encapsulating it into an electronic device.
-la-z~
Some of the above enumerated manufacturing steps are severe and can cause the anode assembly to fail. More specifi-cally, failures occur because of physical damage to the junction of the wire riser and the anode. The physical damage can cause high direct current leakage and device shortin~. Electrical shorts can often be traced ~o the presence of solid electrolyte on the riser which causes the device to become shorted after a contact lead is attached to the riser.
Yarious washers, sleeves and similar means of protection have been used in the past to keep the riser wire clean and thus prevent shorting at the riser. But since these means of protec-tion did not adhere to the riser or to the anode, they could not completely protect the riser from the electrolyte, or the junction of the riser and anode from physical abuse. It has been found that a small quantity of epoxy resin applied ~o and cured around the egress or junction of the riser wire and anode after proces-sing, but before assembly and encapsulation, reduces the chances of physical damage and produces better direct current leakage distribution among the electrical devices. However, the appli-cation of an epoxy or similar cured coating requires additional manufacturing steps which increase the manufacturing costs and complexity of the electrical device.
M-649~
The ideal time to apply a protective coating is before anode anodization and the subsequent manufacturing steps. A
coating applied before anodization accomplishes the dual purpose of preventing physical damage to the riser e~ress and preventing solid electrolyte build up on the riser. In order to put the coating in place prior to anodization, the coating must be inert to anodization and to any subsequent manufacturing steps, especial-ly manganese dioxide (MnO2) deposition from manganese nitrate.
An additional requirement of the material used in the coating is that it should not cause ~he anode or other components of the electrical device to degrade, such as by reducing the wettability of the anode.
~ M-6498 THE INVENTION
It has now been discovered that anode assembly failures can be minimized by a novel process in which a pre~orm of an electrically insulative ma~erial comprising a spe~ific type of polymeric polyhalogenated hydrocarbon is placed in the proximity of the junction of the anode riser and the anode, and the polymer is heated to a temperature sufficient to permit it to flow into the area of the junction of the anode riser and anode. The heating îs then terminated and the polymer solidifies to form an electrically insulating nodule. The nodule is adheringly bonded to both the anode riser and to the anode. After these steps the anode can be anodized and further processed without serious consequences.
The polymeric polyhalogenated hydrocarbon can also be applied in a molten state, but in order to avoid additional manufacturing steps it is preferably applied in a solid form, usually as a preform having a definite shape. Most preferably the preform is in the form of a washer or sleeve placed around the riser wire. Because the polymer flows on heating, the washer or sleeve can have an aperture two to three times larger than the anode riser. This permits the use of automated equip-ment to place the washer around the riser and on the anode. The compatibility of the solid polymeric polyhalogenated hydrocarbon with automated equipment helps to reduce the manufacturing costs of the anode assembly.
~ 126~
M-6~98 The only materials known to be capable of being used in accordance with this invention are th~se with repeating units having the formula:
_~X~
~ Cln ~
wherein n is a whole number equal to or greater than 2 and where-in x represents substituents, a predominant portion of which within each repeating unit are fluorine and at least one of which in each repeating unit is a substituent other than fluorine. By "predominant portion" it is meant that at least fifty percent of the substituents are fluorine when only one other type of substi-tuent is present, and that, in other cases, there is an excess of fluorine oVer any other substituent present. These polyhalo-genated hydrocarbons are inert to the anodization process and are capable of withstanding subsequent manufacturing steps to which the anode assembly is subjected. These hydrocarbons are adherent to both the anode and the riser and do not degrade or adversely affect the anode by way of reaction of the anode with degradation by-products as may be the case with other polymers. Further, these polyhalogenated hydrocarbons do not shrink or separate from the riser during anodization or manufacture. A completely coated riser is desirable since the coating prevents shorting within the electrical de~ice during use.
6~
Preferably those substituents in the repeating units which are not fluorine are selected from the group consisting of chlorine, bromine, hydrogen, ~RYm~ ~ORYm~ and mixtures thereof, wherein Y represents halogen or hydrogen or a mixture thereof, R is a chain having 1-6 carbon ato~s, and m represents the requisite number of hydrogen and/or halogen atoms necessary to complete the chain. Suitable polymeric polyhalogenated hydrocarbons for use in the present invention include copolymers of fluorinated ethylene and propylene, one such copolymer being sold under the trademark Teflon FEP by E. I. DuPont de Nemours and Co., Wilmington, Delaware; copolymers of ethylene and tetrafluoro-ethylene sold under the trademark of TEFZEL by E. I. DuPont de Nemours and Co., chlorotrifluoroethylene resins such as available under the trademark KEL-F from 3M Co. or such as sold by Allied Chemical Corp under the trademark PLASKOH; the copolymers of ethylene and chloro-trifluoroethylene one of which is sold under the trademark HALAR by Allied Chemical Corporation, Morristown, New Jersey, polymers having a fluorocarbon backbone and a perfluoro alkoxy side chain, one of which is sold under the trademark of TEFLON PFA by E. I. DuPont de Nemours and Co., homopolymers of vinylidene fluoride, one such polymer being marketed under the trademark KYNAR by Pennwalt Corp., Philadelphia, Pennsylvania.
Polymeric polyhalogenated hydrocarbons other than those cited above, such as polytetrafluoroethylene, cannot be used in the present invention since they will not flow well when heated, having a very high melt viscosity and will not adhere to the anode or anode riser on solidification. Without the ability to flow and adhere, such materials cannot form the required adherent nodule at the junction of the riser and anode.
~ `~
- The invention relates to an anode assembly for a capacitor, and more particularly to an anode assembly incorporating a nodule of an electrically insulating material comprising a polyhalogenated hydrocarbon capable of forming a melt at between about 150C and ~50C with repeating units having the formula:
~X~
~ xn~
wherein n is a whole number equal to or greater than 2 and wherein x represents substituents, a predominant portion of which within each repeating unit are fluorine and at least one of which in each repeating unit is a substituent selected from the group consisting of chlorine, bromine, hydrogen, -RYm, -ORYm~ and mixtures thereof, wherein Y represents halogen or hydrogen or a mixture thereof, R is a chain having 1~6 carbon atoms, and m represents the requisite number of hydrogen or halogen atoms necessary to complete the chain.
BACKGROUND OF THE INVENTION
Many capacitors, including solid tantalum capacitors, use a porous metal pellet as an anode. These pellets are manufactured by pressing and then sintering a metal powder into a rigid mass. The anode is usually manufactured from a film forming metal. Film forming metal powders such as tantalum, aluminum, titanium, zirconium or niobium, can be formed into a porous pellet for use as an anode by a sintering process employed with other metals.
Either before or after sintering, a wire riser is inserted into or attached to the anode to form an anode assembly. The wire riser conducts electricity to and from the anode during use.
~ 1 _ ;26~
After the attachment of the riser and the sintering of the pellet, the anode assembly is ready for further manufacturing steps, such as anodizing the anode, manganese dioxide (MnO2) deposition, riser-wire cut off, and welding of the riser wire to a terminal. The anode assembly is further processed by encapsulating it into an electronic device.
-la-z~
Some of the above enumerated manufacturing steps are severe and can cause the anode assembly to fail. More specifi-cally, failures occur because of physical damage to the junction of the wire riser and the anode. The physical damage can cause high direct current leakage and device shortin~. Electrical shorts can often be traced ~o the presence of solid electrolyte on the riser which causes the device to become shorted after a contact lead is attached to the riser.
Yarious washers, sleeves and similar means of protection have been used in the past to keep the riser wire clean and thus prevent shorting at the riser. But since these means of protec-tion did not adhere to the riser or to the anode, they could not completely protect the riser from the electrolyte, or the junction of the riser and anode from physical abuse. It has been found that a small quantity of epoxy resin applied ~o and cured around the egress or junction of the riser wire and anode after proces-sing, but before assembly and encapsulation, reduces the chances of physical damage and produces better direct current leakage distribution among the electrical devices. However, the appli-cation of an epoxy or similar cured coating requires additional manufacturing steps which increase the manufacturing costs and complexity of the electrical device.
M-649~
The ideal time to apply a protective coating is before anode anodization and the subsequent manufacturing steps. A
coating applied before anodization accomplishes the dual purpose of preventing physical damage to the riser e~ress and preventing solid electrolyte build up on the riser. In order to put the coating in place prior to anodization, the coating must be inert to anodization and to any subsequent manufacturing steps, especial-ly manganese dioxide (MnO2) deposition from manganese nitrate.
An additional requirement of the material used in the coating is that it should not cause ~he anode or other components of the electrical device to degrade, such as by reducing the wettability of the anode.
~ M-6498 THE INVENTION
It has now been discovered that anode assembly failures can be minimized by a novel process in which a pre~orm of an electrically insulative ma~erial comprising a spe~ific type of polymeric polyhalogenated hydrocarbon is placed in the proximity of the junction of the anode riser and the anode, and the polymer is heated to a temperature sufficient to permit it to flow into the area of the junction of the anode riser and anode. The heating îs then terminated and the polymer solidifies to form an electrically insulating nodule. The nodule is adheringly bonded to both the anode riser and to the anode. After these steps the anode can be anodized and further processed without serious consequences.
The polymeric polyhalogenated hydrocarbon can also be applied in a molten state, but in order to avoid additional manufacturing steps it is preferably applied in a solid form, usually as a preform having a definite shape. Most preferably the preform is in the form of a washer or sleeve placed around the riser wire. Because the polymer flows on heating, the washer or sleeve can have an aperture two to three times larger than the anode riser. This permits the use of automated equip-ment to place the washer around the riser and on the anode. The compatibility of the solid polymeric polyhalogenated hydrocarbon with automated equipment helps to reduce the manufacturing costs of the anode assembly.
~ 126~
M-6~98 The only materials known to be capable of being used in accordance with this invention are th~se with repeating units having the formula:
_~X~
~ Cln ~
wherein n is a whole number equal to or greater than 2 and where-in x represents substituents, a predominant portion of which within each repeating unit are fluorine and at least one of which in each repeating unit is a substituent other than fluorine. By "predominant portion" it is meant that at least fifty percent of the substituents are fluorine when only one other type of substi-tuent is present, and that, in other cases, there is an excess of fluorine oVer any other substituent present. These polyhalo-genated hydrocarbons are inert to the anodization process and are capable of withstanding subsequent manufacturing steps to which the anode assembly is subjected. These hydrocarbons are adherent to both the anode and the riser and do not degrade or adversely affect the anode by way of reaction of the anode with degradation by-products as may be the case with other polymers. Further, these polyhalogenated hydrocarbons do not shrink or separate from the riser during anodization or manufacture. A completely coated riser is desirable since the coating prevents shorting within the electrical de~ice during use.
6~
Preferably those substituents in the repeating units which are not fluorine are selected from the group consisting of chlorine, bromine, hydrogen, ~RYm~ ~ORYm~ and mixtures thereof, wherein Y represents halogen or hydrogen or a mixture thereof, R is a chain having 1-6 carbon ato~s, and m represents the requisite number of hydrogen and/or halogen atoms necessary to complete the chain. Suitable polymeric polyhalogenated hydrocarbons for use in the present invention include copolymers of fluorinated ethylene and propylene, one such copolymer being sold under the trademark Teflon FEP by E. I. DuPont de Nemours and Co., Wilmington, Delaware; copolymers of ethylene and tetrafluoro-ethylene sold under the trademark of TEFZEL by E. I. DuPont de Nemours and Co., chlorotrifluoroethylene resins such as available under the trademark KEL-F from 3M Co. or such as sold by Allied Chemical Corp under the trademark PLASKOH; the copolymers of ethylene and chloro-trifluoroethylene one of which is sold under the trademark HALAR by Allied Chemical Corporation, Morristown, New Jersey, polymers having a fluorocarbon backbone and a perfluoro alkoxy side chain, one of which is sold under the trademark of TEFLON PFA by E. I. DuPont de Nemours and Co., homopolymers of vinylidene fluoride, one such polymer being marketed under the trademark KYNAR by Pennwalt Corp., Philadelphia, Pennsylvania.
Polymeric polyhalogenated hydrocarbons other than those cited above, such as polytetrafluoroethylene, cannot be used in the present invention since they will not flow well when heated, having a very high melt viscosity and will not adhere to the anode or anode riser on solidification. Without the ability to flow and adhere, such materials cannot form the required adherent nodule at the junction of the riser and anode.
~ `~
2~
M-~49~
Nonhalogenated polymers, such as polyester or nylon, are also not useful since they will decompose when subjected to the reaction pxoducts of the thermal conversion reaction of man-ganese nitrate to manganese dioxide. The reaction b~-products produced by the decomposition of the nonhalogenated polymers will significantly reduce the wettability of the anode, which in turn significantly degrades the resulting electrical device.
In general the polyhalogenated hydrocarbons are ~apable of forming a melt and of flowing when heated to between about 150C and 450C. Each of the preferred polymeric polyhalogenated hydrocarbons used in the invention has a different temperature at which it will flow. Each material also has a different preferred period for being heated to form the most desirable nodule. For the copolymers of fluorinated ethylene and propylene the prefer-red temperature is from about 300C to 350C and the heating will preferably continue for about l0 to 15 minutes. Chlorotrifluoro-ethylene polymers are generally heated to about 275C to 325C
for about 3 to lO minutes. The preferred heating procedure for copolymers of ethylene and tetrafluoroethylene is from about 275C to 325C for a period of from 3 to 10 minutes. Preferred heating of perfluoro alkoxy resins is from about 350C to 400C
for a period of from about 5 minutes to 15 minutes.
The invention and the preferred embodiments will be apparent from the following drawings as well as from the examples.
26~
BRIEF DESCRIPTION OF THE 'DRAWINGS
Figure l is a cross sectiGnal view of the anode of the invention prior to the melting of the polymeric polyhalogenated - hydrocarbon preform.
Figure 2 is a cross sectional view of the anode assembly of the invention after the formation of the nodule.
: Figure 3 is a cross sectional view of the anode assembly of the invention incorporated into an electrical device, here a capacitor.
DETAILED DESCRIPTION OF T~E DRAWINGS
Referring now to Figure 1 of the drawings there is shown an anode 12 which was formed by pressing a powder, prefer-ably of a film forming metal such as tantalum, into a pellet and then sintering it. An anode riser 14, which can also be made from a film forming metal is shown pressed into the anode 12.
Alternatively the anode riser 14 can be welded (not shown) to the anode 12.
A preform 16, here shown in the shape of a washer, is in place around the anode riser 14. The preform 16 is comprised of a polymeric polyhalogenated hydrocarbon, here fluorinated ethylene and propylene ("Teflon FEP"~. The preform 16 is shown having an aperture 18 of approximately twice the width of the anode riser 14. Such a loose fit permits the preform 16 to be put in place by automated equipment (not shown).
~L~9L26~
Figure 2 is a cxoss sectional ~iew ~f the anode assem~ly 22 of the invention after the formation o~ the nodule 20. The droplet of the polyhalogenated hydrocarbon, which had formed on the melting of the preform 16, closed in around the anode riser 14 through surface tension and on cooling adhered to the riser 14.
The droplet also filled in the area surrounding the egress or junction 24 hetween the riser 14 and the anode 12. On cooling the droplet formed a nodule 20 which adhered to both the riser 14 and anode 12 and protected the junction 24 from physical damage.
Figure 3 is a cross sectional view of the anode assembly 22 encapsulated within a capacitor 26. An anode terminal 28 is welded 3Q to the riser 14. A layer of a solid electrolyte 32, here manganese dioxide, is applied to the anode 12. The electro-lyte layer 32 is surrounded by a ~raphite coat 34, which is in turn surrounded by a metallic coat 36, here of sil~er. The anode assembly 22 and the combination of layers described above are held in place within the case 38 by a ~uantity of solder 40.
The solder 40 also electrically connects the metallic coat 36, which is the cathode, to the case 38. A cathode terminal 42 is connected to the case 38 to provide the second terminal of the capacitor 26.
The case 38 is sealed ~rom the environment by a cover 44 comprised of a steel ring 46, an eyelet 48 through which the terminal 28 passes and to which the terminal 28 is soldered, and a ring of compressed glass 50 between the steel ring 46 and eyelet 48. The glass 50 electrically insulates the terminal 28 from the case ~8 thereby preventing electrical shorts.
EXAMPLE
The anode assembly of the present invention is made by first pressing powdered tan~alum into a pellet. An anode riser 14, also made from tantalum, is pressed into the pellet at the same time. The pelle~ is sintered to form an anode 12. Alter-natively the anode riser 14 can be welded to the anode 12 after sintering.
Once the sintering is completed a washer shaped preform 16 made from a copolymer of fluorinated ethylene and propylene which is marketed under the trademark of Teflon FEP, is placed around the anode riser 14. The preform 16 has an outside dia-meter of 0.22 centimeter, a thickness of 0.075 centimeter and a central aperture having a diameter of 0.15 centimeter. The anode assembly with the preform in place i5 shown in Figure 1.
Once the preform 16 is in place, the anode assembly is heated in air at 300C for five minutes to melt the preform 16. When the preform 16 melts the liquid polymer forms a droplet which rests on the anode 12 and surrounds much of the anode riser 14. The polymer also flows into the area around the egress 24 of the anode riser 14 from the anode 12. The polymer adheres to the anode riser 14, anode 12 and the area of the egress 24.
On the cooling of the anode assembly, the droplet forms a nodule 20, which adheres to the riser 14, anode and egress 24.
The anode assembly after the formation of the nodule 20 is shown in Figure 2. The anode assembly is now ready for anodization and further processing.
The preceeding drawings and examples are for illustra-tive purposes only. It is understood that changes and variations can be made without departin~ from the spirit and scope of the present invention as defined in the following claims.
M-~49~
Nonhalogenated polymers, such as polyester or nylon, are also not useful since they will decompose when subjected to the reaction pxoducts of the thermal conversion reaction of man-ganese nitrate to manganese dioxide. The reaction b~-products produced by the decomposition of the nonhalogenated polymers will significantly reduce the wettability of the anode, which in turn significantly degrades the resulting electrical device.
In general the polyhalogenated hydrocarbons are ~apable of forming a melt and of flowing when heated to between about 150C and 450C. Each of the preferred polymeric polyhalogenated hydrocarbons used in the invention has a different temperature at which it will flow. Each material also has a different preferred period for being heated to form the most desirable nodule. For the copolymers of fluorinated ethylene and propylene the prefer-red temperature is from about 300C to 350C and the heating will preferably continue for about l0 to 15 minutes. Chlorotrifluoro-ethylene polymers are generally heated to about 275C to 325C
for about 3 to lO minutes. The preferred heating procedure for copolymers of ethylene and tetrafluoroethylene is from about 275C to 325C for a period of from 3 to 10 minutes. Preferred heating of perfluoro alkoxy resins is from about 350C to 400C
for a period of from about 5 minutes to 15 minutes.
The invention and the preferred embodiments will be apparent from the following drawings as well as from the examples.
26~
BRIEF DESCRIPTION OF THE 'DRAWINGS
Figure l is a cross sectiGnal view of the anode of the invention prior to the melting of the polymeric polyhalogenated - hydrocarbon preform.
Figure 2 is a cross sectional view of the anode assembly of the invention after the formation of the nodule.
: Figure 3 is a cross sectional view of the anode assembly of the invention incorporated into an electrical device, here a capacitor.
DETAILED DESCRIPTION OF T~E DRAWINGS
Referring now to Figure 1 of the drawings there is shown an anode 12 which was formed by pressing a powder, prefer-ably of a film forming metal such as tantalum, into a pellet and then sintering it. An anode riser 14, which can also be made from a film forming metal is shown pressed into the anode 12.
Alternatively the anode riser 14 can be welded (not shown) to the anode 12.
A preform 16, here shown in the shape of a washer, is in place around the anode riser 14. The preform 16 is comprised of a polymeric polyhalogenated hydrocarbon, here fluorinated ethylene and propylene ("Teflon FEP"~. The preform 16 is shown having an aperture 18 of approximately twice the width of the anode riser 14. Such a loose fit permits the preform 16 to be put in place by automated equipment (not shown).
~L~9L26~
Figure 2 is a cxoss sectional ~iew ~f the anode assem~ly 22 of the invention after the formation o~ the nodule 20. The droplet of the polyhalogenated hydrocarbon, which had formed on the melting of the preform 16, closed in around the anode riser 14 through surface tension and on cooling adhered to the riser 14.
The droplet also filled in the area surrounding the egress or junction 24 hetween the riser 14 and the anode 12. On cooling the droplet formed a nodule 20 which adhered to both the riser 14 and anode 12 and protected the junction 24 from physical damage.
Figure 3 is a cross sectional view of the anode assembly 22 encapsulated within a capacitor 26. An anode terminal 28 is welded 3Q to the riser 14. A layer of a solid electrolyte 32, here manganese dioxide, is applied to the anode 12. The electro-lyte layer 32 is surrounded by a ~raphite coat 34, which is in turn surrounded by a metallic coat 36, here of sil~er. The anode assembly 22 and the combination of layers described above are held in place within the case 38 by a ~uantity of solder 40.
The solder 40 also electrically connects the metallic coat 36, which is the cathode, to the case 38. A cathode terminal 42 is connected to the case 38 to provide the second terminal of the capacitor 26.
The case 38 is sealed ~rom the environment by a cover 44 comprised of a steel ring 46, an eyelet 48 through which the terminal 28 passes and to which the terminal 28 is soldered, and a ring of compressed glass 50 between the steel ring 46 and eyelet 48. The glass 50 electrically insulates the terminal 28 from the case ~8 thereby preventing electrical shorts.
EXAMPLE
The anode assembly of the present invention is made by first pressing powdered tan~alum into a pellet. An anode riser 14, also made from tantalum, is pressed into the pellet at the same time. The pelle~ is sintered to form an anode 12. Alter-natively the anode riser 14 can be welded to the anode 12 after sintering.
Once the sintering is completed a washer shaped preform 16 made from a copolymer of fluorinated ethylene and propylene which is marketed under the trademark of Teflon FEP, is placed around the anode riser 14. The preform 16 has an outside dia-meter of 0.22 centimeter, a thickness of 0.075 centimeter and a central aperture having a diameter of 0.15 centimeter. The anode assembly with the preform in place i5 shown in Figure 1.
Once the preform 16 is in place, the anode assembly is heated in air at 300C for five minutes to melt the preform 16. When the preform 16 melts the liquid polymer forms a droplet which rests on the anode 12 and surrounds much of the anode riser 14. The polymer also flows into the area around the egress 24 of the anode riser 14 from the anode 12. The polymer adheres to the anode riser 14, anode 12 and the area of the egress 24.
On the cooling of the anode assembly, the droplet forms a nodule 20, which adheres to the riser 14, anode and egress 24.
The anode assembly after the formation of the nodule 20 is shown in Figure 2. The anode assembly is now ready for anodization and further processing.
The preceeding drawings and examples are for illustra-tive purposes only. It is understood that changes and variations can be made without departin~ from the spirit and scope of the present invention as defined in the following claims.
Claims (11)
1. An anode assembly for a capacitor comprising a sintered anode, an anode riser extending from said anode, and a nodule adheringly bonded to both said anode riser and said sintered anode, said nodule comprising and electrically insulating material comprising a polymeric, polyhalogenated hydrocarbon capable of forming a melt at between about 150°C and 450°C with repeating units having the formula:
wherein n is a whole number equal to or greater than 2 and wherein x represents substituents, a predominant portion of which within each repeating unit are fluorine and at least one of which in each repeating unit is a substituent selected from the group consisting of chlorine, bromine, hydrogen, -RYm, -ORYm, and mixtures thereof, wherein Y rep-resents halogen or hydrogen or a mixture thereof, R is a chain having 1-6 carbon atoms, and m represents the requisite number of hydrogen or halogen atoms necessary to complete the chain.
wherein n is a whole number equal to or greater than 2 and wherein x represents substituents, a predominant portion of which within each repeating unit are fluorine and at least one of which in each repeating unit is a substituent selected from the group consisting of chlorine, bromine, hydrogen, -RYm, -ORYm, and mixtures thereof, wherein Y rep-resents halogen or hydrogen or a mixture thereof, R is a chain having 1-6 carbon atoms, and m represents the requisite number of hydrogen or halogen atoms necessary to complete the chain.
2. The anode assembly of claim 1 wherein said polymeric poly-halogenated hydrocarbon is selected from the group consisting of copolymers of fluorinated ethylene and propylene, copolymers of ethylene and tetrafluoroethylene, chlorotrifluoroethylene polymers and polymers having a fluorocarbon backbone and a perfluoro alkoxy side chain.
3. The anode assembly of claim 1 wherein said anode assembly is anodized.
4. The anode assembly of claim 1 wherein said sintered anode comprises a film-forming metal.
5. The anode assembly of claim l wherein said anode is sintered tantalum.
6. A capacitor comprising the anode assembly of claim 13 an electrolyte, and a cathode operatively associated with said anode assembly and said electrolyte.
7. The capacitor of claim 6 wherein said electrolyte is manganese dioxide.
8. In a method of making an anode assembly wherein an anode riser is attached to an anode and said anode is anodized, the improve-ment comprising placing a preform of said polymeric, polyhalogenated hydrocarbon of claim 1 in the proximity of the junction of said anode riser and said anode, melting said polymeric, polyhalogenated hydro-carbon and permitting it to flow into the area of the junction of said anode riser and said anode where it solidifies to form a nodule adheringly bonded to both said anode riser and said anodes and then anodizing said anode.
9. The method of claim 8, wherein the polymer preform is in the shape of a washer, said riser passes through an aperture in said washer, and the body of said washer fits against said pellet and the junction of said pellet with said riser.
10. The method of claim 9 wherein said polyhalogenated hydro-carbon is capable of forming a melt when heated to between about 150°C and 450°C.
11. The method of claim 9, wherein the step of melting said polyhalogenated hydrocarbon comprises heating said polyhalogenated hydrocarbon to a temperature of between about 150°C and 450°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US94883878A | 1978-10-05 | 1978-10-05 | |
| US948,838 | 1978-10-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1142611A true CA1142611A (en) | 1983-03-08 |
Family
ID=25488302
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000335157A Expired CA1142611A (en) | 1978-10-05 | 1979-09-06 | Meltable washer for anode protector |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5552216A (en) |
| BR (1) | BR7905983A (en) |
| CA (1) | CA1142611A (en) |
| DE (1) | DE2940465A1 (en) |
| GB (1) | GB2032691B (en) |
| MX (1) | MX148998A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58154224A (en) * | 1982-03-09 | 1983-09-13 | 日本電気ホームエレクトロニクス株式会社 | Method of producing solid electrolytic condenser |
| NL8403928A (en) * | 1984-12-24 | 1986-07-16 | Philips Nv | DRY ELECTROLYTIC CONDITIONER. |
| JPS6426828U (en) * | 1987-08-10 | 1989-02-15 | ||
| JP3801660B2 (en) * | 1994-05-30 | 2006-07-26 | ローム株式会社 | Method for manufacturing capacitor element for tantalum solid electrolytic capacitor |
-
1979
- 1979-09-06 CA CA000335157A patent/CA1142611A/en not_active Expired
- 1979-09-19 BR BR7905983A patent/BR7905983A/en unknown
- 1979-09-28 GB GB7933761A patent/GB2032691B/en not_active Expired
- 1979-10-04 MX MX17951879A patent/MX148998A/en unknown
- 1979-10-04 JP JP12843779A patent/JPS5552216A/en active Pending
- 1979-10-05 DE DE19792940465 patent/DE2940465A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| DE2940465A1 (en) | 1980-04-17 |
| GB2032691A (en) | 1980-05-08 |
| JPS5552216A (en) | 1980-04-16 |
| GB2032691B (en) | 1982-11-24 |
| BR7905983A (en) | 1980-07-08 |
| MX148998A (en) | 1983-08-05 |
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