CA1158730A - Metallized film dual capacitor - Google Patents
Metallized film dual capacitorInfo
- Publication number
- CA1158730A CA1158730A CA000390320A CA390320A CA1158730A CA 1158730 A CA1158730 A CA 1158730A CA 000390320 A CA000390320 A CA 000390320A CA 390320 A CA390320 A CA 390320A CA 1158730 A CA1158730 A CA 1158730A
- Authority
- CA
- Canada
- Prior art keywords
- film
- winding
- metallized
- margin
- termination
- 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
- 239000003990 capacitor Substances 0.000 title claims abstract description 55
- 239000011104 metalized film Substances 0.000 title claims abstract description 33
- 230000009977 dual effect Effects 0.000 title claims abstract description 24
- 239000010408 film Substances 0.000 claims abstract description 68
- 238000004804 winding Methods 0.000 claims description 57
- 238000001465 metallisation Methods 0.000 claims description 25
- 239000000463 material Substances 0.000 claims description 17
- -1 polypropylene Polymers 0.000 claims description 5
- 239000004743 Polypropylene Substances 0.000 claims description 3
- 229920000515 polycarbonate Polymers 0.000 claims description 3
- 239000004417 polycarbonate Substances 0.000 claims description 3
- 239000004698 Polyethylene Substances 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 229920000573 polyethylene Polymers 0.000 claims description 2
- 239000005020 polyethylene terephthalate Substances 0.000 claims description 2
- 229920001155 polypropylene Polymers 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 description 10
- 239000002184 metal Substances 0.000 description 10
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 6
- 235000010210 aluminium Nutrition 0.000 description 6
- 125000006850 spacer group Chemical group 0.000 description 6
- 229910052725 zinc Inorganic materials 0.000 description 6
- 239000011701 zinc Substances 0.000 description 6
- 238000000034 method Methods 0.000 description 5
- 230000009850 completed effect Effects 0.000 description 4
- 238000010276 construction Methods 0.000 description 4
- 238000000576 coating method Methods 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 229910000679 solder Inorganic materials 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000008030 elimination Effects 0.000 description 2
- 238000003379 elimination reaction Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 241000193803 Therea Species 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 230000002730 additional effect Effects 0.000 description 1
- 230000001680 brushing effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920002492 poly(sulfone) Polymers 0.000 description 1
- 229920000139 polyethylene terephthalate Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920000136 polysorbate Polymers 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000005476 soldering Methods 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 238000005507 spraying Methods 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
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/002—Details
- H01G4/255—Means for correcting the capacitance value
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/32—Wound capacitors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/38—Multiple capacitors, i.e. structural combinations of fixed capacitors
- H01G4/385—Single unit multiple capacitors, e.g. dual capacitor in one coil
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
Abstract
METALLIZED FILM DUAL CAPACITOR
Abstract of the Disclosure A plain dielectric film is wound with a dielec-tric film which has been metallized on both surfaces and which has unmetallized portions that isolate the three electrodes of a dual capacitor from one another.
Abstract of the Disclosure A plain dielectric film is wound with a dielec-tric film which has been metallized on both surfaces and which has unmetallized portions that isolate the three electrodes of a dual capacitor from one another.
Description
'73~
METALLIZ~ FILM DUAL CAPACITOR
This invention relates ~o a metallized-film dual capacitor, and more particularly to a common electrode dual capacitor in which all electrodes are metallized surfaces of a single film, and to a method of making the same.
~ual capacitors having a common electrode have been known in the prior art, particularly as shunt capaci-tors in wave fllters. One such construction is shown in US 2,918,635 wherein a single common foil electrode is wound with two shorter, serially disposed, foil electrodes.
It is also known in the prior art to substitute metallized films for foil electrodes in a dual capacitor.
It is also known in the prior art to achieve separation be-tween portions of a metallized film by burning metalliza-tion from the film at intermediate points in the winding.
A feature of this invention is the provision of simplified structure and processing of three-electrode metallized-film dual capacitors. Another object is the reduction of the inventory of costly metallized film that is required for the construction of metalli~ed-film dual capacitors. Another feature is the provision of structure and method for true control over the effective width of a metallized-film dual capacitor by complete elimination of wavy margins in the winding. Another feature is to pro-vide greater construction efficiency, tigh-ter outer winding, and more uniform tension winding then heretofore attained in metallized-film dual capacitors.
METALLIZ~ FILM DUAL CAPACITOR
This invention relates ~o a metallized-film dual capacitor, and more particularly to a common electrode dual capacitor in which all electrodes are metallized surfaces of a single film, and to a method of making the same.
~ual capacitors having a common electrode have been known in the prior art, particularly as shunt capaci-tors in wave fllters. One such construction is shown in US 2,918,635 wherein a single common foil electrode is wound with two shorter, serially disposed, foil electrodes.
It is also known in the prior art to substitute metallized films for foil electrodes in a dual capacitor.
It is also known in the prior art to achieve separation be-tween portions of a metallized film by burning metalliza-tion from the film at intermediate points in the winding.
A feature of this invention is the provision of simplified structure and processing of three-electrode metallized-film dual capacitors. Another object is the reduction of the inventory of costly metallized film that is required for the construction of metalli~ed-film dual capacitors. Another feature is the provision of structure and method for true control over the effective width of a metallized-film dual capacitor by complete elimination of wavy margins in the winding. Another feature is to pro-vide greater construction efficiency, tigh-ter outer winding, and more uniform tension winding then heretofore attained in metallized-film dual capacitors.
- 2 ~ 3~
In accorda~ce wi~h tl~is inve~tion a plain dielec-tric film is wound with a dielectric film which has been metallized on both of its surfaces and which has unmetal-lized portions that isolate the three electrodes of the dual capacitor from one another.
In a drawing which illustrates emhodiments of this invention, Figure l is a perspective of a finished capaci-tor winding~
Figure 2 is a perspective of the capacitor of Figure l partially unrolled to reveal ~he interrelation-shlp of the films, and Figure 3 is a cross-section taken along line 3-3 of Figure 2.
lS In general, the metallized-film dual capacitor of this invention is a convolute winding of a plain dielectric film and a metallized dielectric film which has metalllza-tion over substantially the full extent of both of its sur-faces. A first metal-free margin extends the length of one surface of the metallized film, and a second metal-free margin extends the full length of the other surface and is disposed diagonally opposite the first margin so as to pro-vide a margin at each lateral-end edge of the winding. A
metal-free region extends across one surface of the metal-lized film from one margin to the second margin so as todivide the metallization on ~hat one surface into a first electrode and a second electrode. A first termination con-tacts the first electrode, a second termination contacts the second elec-trode, and a third termination contacts the metallization on the other surface of the metallized film.
The winding further includes at least one full turn of a third dielectric film which extends from one edge of the winding so as to ensure separation between the first termi-nation and the second termination.
The construction of this invention utilizes addi-tional turns of the plain film as the protective outer wrap, thereby eliminating the need for the separate outer wrap of prior art metallized dual capacitors. By maintaining the 7~a _ 3 _ continuous plain fil~ under tension during the rolling of the outer wrap, a tighter finished winding is obtained than is attainable in the prior art where an additlonal wrapper film has to be introduced into the winding.
In the drawing, Figure 1 shows the capacitor 10 of this invention in perspective, with the third dielectric separator 18 extending from the winding between the termi-nations 14 and 16. Figure 2 shows the capacitor 10 of Fig-ure 1 in a partially unrolled condition so as to reveal the lQ interrelationship of the films 20, 30 and their terminations.
Figure 3 further shows the spacial relationship of the three dielectric films that are employed in the capacitor 10 o~
this invention.
The Figures of the drawing show convolutely wound capacitor section 10 which includes a double-~etallized film 30 and a plain film 20. Capacitor 10 is rolled so that metallization 32 on one surface of film 30 extends from one lateral end edge of the winding and metallization 34 on the opposite surface of film 30 extends from the other lateral end of the winding. The extended edges of the three metallizations 32 and 34,38 are contacted at the opposite ends of the winding 10.
Figure 1 shows terminals 15 and 17 attached to terminations 14 and 16, respectively, extending ~rom one lateral end of the winding 10. Terminal 13 extends from the opposite end of capacitor winding lO in contact with a s-imilar termination that i~ no~ shown on the drawing. A
spacer member 18 extends outwardly from one end of capaci-tor 10 so as to separate terminations 14 and 16 on that end.
Figure 3 shows the relative lateral placement of the films 20 and 30 for the preferred embodiment of this invention. Film 20 is preferably wide enough to e~tend about half-way into unmetallized margins 42 and 44 on the opposite surfaces of film 30. Film 20 could be of substan~
tially the same width as film 30, although such a wid~h would make more difficult the application of ~he termina-tion material to the ends of capacitor winding lO in good ~ 3 electrical contact with the metallization 32 or 34,38 extending from that end of the winding.
Figure 3 also shows the lateral extent of spacer 18 in the winding 10. It is important that spacer 18 ex-tends beyond one end of winding 10 to an extent greaterthan the tllickness of the termînation material to be ap-plied to that end. Spacer 18 is preEerably made of a material to which the termination material does not stick, and whlch is preferably a material that is still enough to rebound from any rushing in the operation of applying the termination material. Suitable materials for spacer 18 are polymers such as polycarbonate or polysulfone. About the only restriction on the material for spacer 18 is that the material should not melt at the temperature of application of end spray metallizations 14 and 16.
Figure 2 shows a partially unrolled layout of capacitor lO so as to expose metallization 34,38 on the top side of film 30, as also shown in cross-section in Figure 3.
Film 20 is shown as extending beyond the tail end of film 30, and film 30 is shown having an end margin 48; both practices serving to insure against shorting the metalliza-tions on the opposite surfaces of film 30 when the film 30 is cut between successive windings 10 from the same roll of material. Although metal-free end 48 ensures non-short-ing between metallized surfaces, it should be understood that the normal clearing action in a metallized winding serves to vaporize any bridges between metal surfaces that might be present without margin 48.
Film 30 is provided with a metal-free region 46 which extends completely across film 30 from margin 42 to margin 44, thereby dividing the metallization on that sur-face of film 30 into separate metallizations 34 and 38.
The width of metal-free region 46 is shown as being slight-ly greater than the width of margins 42 and 44 and also end region 48. However, all of the metal-free regions may be of the same width, so long as each metal-free region is of a greater width than the arc-over distance of the rated voltage of the capacitor winding.
~ 3 In the processing of the capacitors of this in-vention, the applied overload is twice the rated voltage;
hencel ~he metal-free regions in the commercial embodi-ments are at least twice the arc-over distance of the rated voltage.
Metallization 32 is continuous on the surface of film 30 from one end of the winding 10 to the other. Metal~
lization 32 provides the common electrode in capacitive relation to metallizations 34 and 38, so as to provide a serially-wound dual capacitor 10.
Film 30 is preferably provided with the diago-nally opposite margins 42 and 44 prior to winding of capac-itor section 10. Margins 42 and 44 may be provided during the metallization of film 30, as b~ suitable masks within the metallization chamber.
Ho~ever, in order to be able to wind successive capacitors from a continuous roll of the metallized-film material, it is preferred that regions 46 and 48 on film 30 be cleared of metal during the operation of winding each capacitor. It is preferred that the de-metallizing operation be accomplished on the capacitor winding machine by means of a brush which scrubs or erases the metal coat-ing from onl~ one surface of the film. A suction applied around the scrubber serves to capture the particles of metallization, and thereby prevent their incorporation into the winding.
Metal-free region 46 i5 provided in the winding after a sufficient number of turns have been rolled to pro-vide the desired capacitance of the inner of the two capac-itors. In a like manner, whenever metal-free region 48 is to be provided, metal removal is done after a sufficient number of addîtional turns have been rolled to attain the desired capacitance of the outer capacitor. In practice, it has been found that ît is effective to make the width of metal-free region 48 at least twice the width needed to ensure separatîon of the metal coatings on the opposite surfaces of the film. The winding machine is th~nprogram-med to cut the film 30 in the middle of region 48, thereby ~ '7 also providing a metal-free s~art for the next capacitor winding.
Films 20 and 30 may be selected from among poly-propylene, polyethylene terephthalate, polycarbonate, and polyethylene. It is preferred that ~ilms 20 and 30 be of the same material, with polypropylene being employed in the preferred embodiment.
Metalli~ation on the surfaces of film 30 may be selected from any of the known vapor deposited materials used in the capacitor art, s~uch as aluminum or zinc. Alu-minum has been selected as the preferred embodiment for its ease of handling and its highly reproducible electrical properties.
Terminations 14 and 16 may be of any solder-like material known to provide ~ood electrical contact to alu-minum and which can be applied by metal spray techniques.
Sprayed zinc is the preferred material, with sprayed alu-minum also being saticfactory. The zinc termination per-mits terminals to be attached by welding or by soldering to an overcoat of a tin/lead solder of the 60/40 composi-tion.
Terminals 13, 15 and 17 are preferably tinned copper tab stock. The terminals may be applied to the ter-minations of capacitor 10 by conventional techniques known to the metallized capacitor art, with reflowing of the sol-der overcoat on the termination materials being satisfac-tory. However direct welding to the zinc termination is the preferred method.
The capacitors of this invention may be housed in any conventional capacitor encasement, such as prefonned metal or plastic cases, or by molding or coating techniques.
It is preferred that aluminum cans be employed with termi-nals 13, 15 and 17 being secured to separate terminals in the cover of such a capacitor can. Sui~able pressure inter-rupters known to the capacitor art are preferably utilizedacross the terminals so as to avoid rupture of the housing in the event of over pressure.
'7~
The pre~erred method of this invention is de-scribed in terms of a dual capacitor having a 5 m~d. inner section and a 35 mfd. outer section. Pol.ypropylene film of 8 microns thickne~s was used Eor both the plain and the metallized films. The metallized film 30 was metallized on both surfaces with aluminum to provide a surface resis-tivity of 1 to 4 ohms/square. Margins 42 and ~4 were each 2.5 mm along the ull length of ~ilm 30.
Capacitor winding 1~ was started by spinning 200 turns of plain film 20 and then inserting double metallized film 30. A smaller number of starting turns of plain film 20 would be satisfactory, provided that a rigid core was employed.
The metallized Eilm 30 was 100 mm wide and the plain film 20 was 98 mm wide. The films were centered so that film 30 extended 1 mm beyond each edge of film 30.
In other words, 1 mm of metal was left available for termi-nation spray at each edge of the winding 10.
The 5 mfd. inner section was completed by winding 270 tuxns of combined films 20 and 30. Barrier 18 was in-serted into the winding and margin 46 was produced by brush-ing away 10 mm of metallization from one side o~ film 30.
After 2 turns of combined films 20,30 and 18 were wound, barrier film 18 was cut and released from the winding. The 35 mfd. outer section was completed by winding 820 turns of combined films 20 and 30, at which time metallized film 30 was cut and released from the winding. Capacitor winding 10 was completed by winding 50 additional turns of plain film 20, and then heat sealing film 20 to itself by raising 3Q the Eilm temperature to 180C by contact with a heating element.
Terminations were provided by spraying zinc onto both ends of winding 10 so as to contact the metallizations extending to each oE the edges of the winding. Tinned copper terminals 13,15 and 17 were therea:Eter welded to the respective zinc terminations.
- 8 ~ f3~3 Winding 10 was housed within a cylindrical metal can having three through terminals in its cover, with each of winding terminals 13,15 and 17 joined to a respective cover terminal. The housing ~as sealed in the conventional manner except for a fill hole in the cover.
A vacuum was pulled on the housing, and then a suitable dielectric oil, e.g. diisononlyphthalate, was introduced through the ~ill hole at 15 psi gage pressure.
Three vacuum and pressure cycles of impregnatlon were com-pleted so as to ensure the elimination of voids in thewinding. The fill hole in the housing was closed by sol-der.
In accorda~ce wi~h tl~is inve~tion a plain dielec-tric film is wound with a dielectric film which has been metallized on both of its surfaces and which has unmetal-lized portions that isolate the three electrodes of the dual capacitor from one another.
In a drawing which illustrates emhodiments of this invention, Figure l is a perspective of a finished capaci-tor winding~
Figure 2 is a perspective of the capacitor of Figure l partially unrolled to reveal ~he interrelation-shlp of the films, and Figure 3 is a cross-section taken along line 3-3 of Figure 2.
lS In general, the metallized-film dual capacitor of this invention is a convolute winding of a plain dielectric film and a metallized dielectric film which has metalllza-tion over substantially the full extent of both of its sur-faces. A first metal-free margin extends the length of one surface of the metallized film, and a second metal-free margin extends the full length of the other surface and is disposed diagonally opposite the first margin so as to pro-vide a margin at each lateral-end edge of the winding. A
metal-free region extends across one surface of the metal-lized film from one margin to the second margin so as todivide the metallization on ~hat one surface into a first electrode and a second electrode. A first termination con-tacts the first electrode, a second termination contacts the second elec-trode, and a third termination contacts the metallization on the other surface of the metallized film.
The winding further includes at least one full turn of a third dielectric film which extends from one edge of the winding so as to ensure separation between the first termi-nation and the second termination.
The construction of this invention utilizes addi-tional turns of the plain film as the protective outer wrap, thereby eliminating the need for the separate outer wrap of prior art metallized dual capacitors. By maintaining the 7~a _ 3 _ continuous plain fil~ under tension during the rolling of the outer wrap, a tighter finished winding is obtained than is attainable in the prior art where an additlonal wrapper film has to be introduced into the winding.
In the drawing, Figure 1 shows the capacitor 10 of this invention in perspective, with the third dielectric separator 18 extending from the winding between the termi-nations 14 and 16. Figure 2 shows the capacitor 10 of Fig-ure 1 in a partially unrolled condition so as to reveal the lQ interrelationship of the films 20, 30 and their terminations.
Figure 3 further shows the spacial relationship of the three dielectric films that are employed in the capacitor 10 o~
this invention.
The Figures of the drawing show convolutely wound capacitor section 10 which includes a double-~etallized film 30 and a plain film 20. Capacitor 10 is rolled so that metallization 32 on one surface of film 30 extends from one lateral end edge of the winding and metallization 34 on the opposite surface of film 30 extends from the other lateral end of the winding. The extended edges of the three metallizations 32 and 34,38 are contacted at the opposite ends of the winding 10.
Figure 1 shows terminals 15 and 17 attached to terminations 14 and 16, respectively, extending ~rom one lateral end of the winding 10. Terminal 13 extends from the opposite end of capacitor winding lO in contact with a s-imilar termination that i~ no~ shown on the drawing. A
spacer member 18 extends outwardly from one end of capaci-tor 10 so as to separate terminations 14 and 16 on that end.
Figure 3 shows the relative lateral placement of the films 20 and 30 for the preferred embodiment of this invention. Film 20 is preferably wide enough to e~tend about half-way into unmetallized margins 42 and 44 on the opposite surfaces of film 30. Film 20 could be of substan~
tially the same width as film 30, although such a wid~h would make more difficult the application of ~he termina-tion material to the ends of capacitor winding lO in good ~ 3 electrical contact with the metallization 32 or 34,38 extending from that end of the winding.
Figure 3 also shows the lateral extent of spacer 18 in the winding 10. It is important that spacer 18 ex-tends beyond one end of winding 10 to an extent greaterthan the tllickness of the termînation material to be ap-plied to that end. Spacer 18 is preEerably made of a material to which the termination material does not stick, and whlch is preferably a material that is still enough to rebound from any rushing in the operation of applying the termination material. Suitable materials for spacer 18 are polymers such as polycarbonate or polysulfone. About the only restriction on the material for spacer 18 is that the material should not melt at the temperature of application of end spray metallizations 14 and 16.
Figure 2 shows a partially unrolled layout of capacitor lO so as to expose metallization 34,38 on the top side of film 30, as also shown in cross-section in Figure 3.
Film 20 is shown as extending beyond the tail end of film 30, and film 30 is shown having an end margin 48; both practices serving to insure against shorting the metalliza-tions on the opposite surfaces of film 30 when the film 30 is cut between successive windings 10 from the same roll of material. Although metal-free end 48 ensures non-short-ing between metallized surfaces, it should be understood that the normal clearing action in a metallized winding serves to vaporize any bridges between metal surfaces that might be present without margin 48.
Film 30 is provided with a metal-free region 46 which extends completely across film 30 from margin 42 to margin 44, thereby dividing the metallization on that sur-face of film 30 into separate metallizations 34 and 38.
The width of metal-free region 46 is shown as being slight-ly greater than the width of margins 42 and 44 and also end region 48. However, all of the metal-free regions may be of the same width, so long as each metal-free region is of a greater width than the arc-over distance of the rated voltage of the capacitor winding.
~ 3 In the processing of the capacitors of this in-vention, the applied overload is twice the rated voltage;
hencel ~he metal-free regions in the commercial embodi-ments are at least twice the arc-over distance of the rated voltage.
Metallization 32 is continuous on the surface of film 30 from one end of the winding 10 to the other. Metal~
lization 32 provides the common electrode in capacitive relation to metallizations 34 and 38, so as to provide a serially-wound dual capacitor 10.
Film 30 is preferably provided with the diago-nally opposite margins 42 and 44 prior to winding of capac-itor section 10. Margins 42 and 44 may be provided during the metallization of film 30, as b~ suitable masks within the metallization chamber.
Ho~ever, in order to be able to wind successive capacitors from a continuous roll of the metallized-film material, it is preferred that regions 46 and 48 on film 30 be cleared of metal during the operation of winding each capacitor. It is preferred that the de-metallizing operation be accomplished on the capacitor winding machine by means of a brush which scrubs or erases the metal coat-ing from onl~ one surface of the film. A suction applied around the scrubber serves to capture the particles of metallization, and thereby prevent their incorporation into the winding.
Metal-free region 46 i5 provided in the winding after a sufficient number of turns have been rolled to pro-vide the desired capacitance of the inner of the two capac-itors. In a like manner, whenever metal-free region 48 is to be provided, metal removal is done after a sufficient number of addîtional turns have been rolled to attain the desired capacitance of the outer capacitor. In practice, it has been found that ît is effective to make the width of metal-free region 48 at least twice the width needed to ensure separatîon of the metal coatings on the opposite surfaces of the film. The winding machine is th~nprogram-med to cut the film 30 in the middle of region 48, thereby ~ '7 also providing a metal-free s~art for the next capacitor winding.
Films 20 and 30 may be selected from among poly-propylene, polyethylene terephthalate, polycarbonate, and polyethylene. It is preferred that ~ilms 20 and 30 be of the same material, with polypropylene being employed in the preferred embodiment.
Metalli~ation on the surfaces of film 30 may be selected from any of the known vapor deposited materials used in the capacitor art, s~uch as aluminum or zinc. Alu-minum has been selected as the preferred embodiment for its ease of handling and its highly reproducible electrical properties.
Terminations 14 and 16 may be of any solder-like material known to provide ~ood electrical contact to alu-minum and which can be applied by metal spray techniques.
Sprayed zinc is the preferred material, with sprayed alu-minum also being saticfactory. The zinc termination per-mits terminals to be attached by welding or by soldering to an overcoat of a tin/lead solder of the 60/40 composi-tion.
Terminals 13, 15 and 17 are preferably tinned copper tab stock. The terminals may be applied to the ter-minations of capacitor 10 by conventional techniques known to the metallized capacitor art, with reflowing of the sol-der overcoat on the termination materials being satisfac-tory. However direct welding to the zinc termination is the preferred method.
The capacitors of this invention may be housed in any conventional capacitor encasement, such as prefonned metal or plastic cases, or by molding or coating techniques.
It is preferred that aluminum cans be employed with termi-nals 13, 15 and 17 being secured to separate terminals in the cover of such a capacitor can. Sui~able pressure inter-rupters known to the capacitor art are preferably utilizedacross the terminals so as to avoid rupture of the housing in the event of over pressure.
'7~
The pre~erred method of this invention is de-scribed in terms of a dual capacitor having a 5 m~d. inner section and a 35 mfd. outer section. Pol.ypropylene film of 8 microns thickne~s was used Eor both the plain and the metallized films. The metallized film 30 was metallized on both surfaces with aluminum to provide a surface resis-tivity of 1 to 4 ohms/square. Margins 42 and ~4 were each 2.5 mm along the ull length of ~ilm 30.
Capacitor winding 1~ was started by spinning 200 turns of plain film 20 and then inserting double metallized film 30. A smaller number of starting turns of plain film 20 would be satisfactory, provided that a rigid core was employed.
The metallized Eilm 30 was 100 mm wide and the plain film 20 was 98 mm wide. The films were centered so that film 30 extended 1 mm beyond each edge of film 30.
In other words, 1 mm of metal was left available for termi-nation spray at each edge of the winding 10.
The 5 mfd. inner section was completed by winding 270 tuxns of combined films 20 and 30. Barrier 18 was in-serted into the winding and margin 46 was produced by brush-ing away 10 mm of metallization from one side o~ film 30.
After 2 turns of combined films 20,30 and 18 were wound, barrier film 18 was cut and released from the winding. The 35 mfd. outer section was completed by winding 820 turns of combined films 20 and 30, at which time metallized film 30 was cut and released from the winding. Capacitor winding 10 was completed by winding 50 additional turns of plain film 20, and then heat sealing film 20 to itself by raising 3Q the Eilm temperature to 180C by contact with a heating element.
Terminations were provided by spraying zinc onto both ends of winding 10 so as to contact the metallizations extending to each oE the edges of the winding. Tinned copper terminals 13,15 and 17 were therea:Eter welded to the respective zinc terminations.
- 8 ~ f3~3 Winding 10 was housed within a cylindrical metal can having three through terminals in its cover, with each of winding terminals 13,15 and 17 joined to a respective cover terminal. The housing ~as sealed in the conventional manner except for a fill hole in the cover.
A vacuum was pulled on the housing, and then a suitable dielectric oil, e.g. diisononlyphthalate, was introduced through the ~ill hole at 15 psi gage pressure.
Three vacuum and pressure cycles of impregnatlon were com-pleted so as to ensure the elimination of voids in thewinding. The fill hole in the housing was closed by sol-der.
Claims (8)
1. A metallized-film dual capacitor comprising a convolute winding of a plain dielectric film and a metal-lized dielectric film having metallization over substan-tially the full extent of both surfaces, a first metal-free margin extending the full length of one surface of said metallized film, a second metal-free margin extending the full length of the other surface of said metallized film diagonally opposite said first margin, a metal-free region extending across said one surface from said one margin to said second margin dividing said metallization on said one surface into a first electrode and a second electrode, a first termination contacting said first elec-trode, a second termination contacting said second elec-trode, and a third termination contacting said metalliza-tion on said other surface.
2. The metallized-film dual capacitor of claim 1 wherein said plain film is continued in said winding beyond the outer end of said metallized film a plurality of turns so as to provide the outer wrap of said winding.
3. The metallized film dual capacitor of claim 1 wherein said winding includes at least one full turn of a third dielectric film extending from said winding between said first termination and said second termination.
4. The metallized film dual capacitor of claim 3 wherein said third dielectric film has a low adhesion for said first termination and said second termination.
5. The metallized-film dual capacitor of claim 1 wherein the width of each of said first margin and said second margin and said region is greater than the arc-over distance of twice the rated voltage of said winding.
6. The metallized-film dual capacitor of claim 1 wherein the beginning and the end of at least one surface of said metallized film are metal-free from said one margin to said second margin.
7. The metallized-film dual capacitor of claim 1 wherein said plain film and said metallized film are selected from among polypropylene, polyethylene terephtha-late, polycarbonate, and polyethylene.
8. A method of making a metallized-film dual capaci-tor comprising winding a plain film together with a film which has metallization over substantially the full extent of both surfaces and a metal-free margin on each of said surfaces, inserting into said winding a short length of a third dielectric film so as to extend beyond one lateral edge of said winding, removing metallization from across one surface of said metallized film within the extent of said short length so as to divide the metallization on said one surface into two electrodes, continuing the winding of said plain film beyond the end of said metallized film so as to provide an outer wrap for said winding, and apply-ing termination material to the lateral end edge of said winding from which said third film extends so as to contact said two electrodes.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US21559480A | 1980-12-12 | 1980-12-12 | |
| US215,594 | 1980-12-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1158730A true CA1158730A (en) | 1983-12-13 |
Family
ID=22803598
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000390320A Expired CA1158730A (en) | 1980-12-12 | 1981-11-18 | Metallized film dual capacitor |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS57124414A (en) |
| CA (1) | CA1158730A (en) |
| GB (1) | GB2089569B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4447854A (en) * | 1982-11-22 | 1984-05-08 | Sprague Electric Company | Oval dual-AC-capacitor package |
| JPS59213122A (en) * | 1983-05-18 | 1984-12-03 | ニチコン株式会社 | Method of producing capacitor |
| DE3319333A1 (en) * | 1983-05-27 | 1984-11-29 | Siemens AG, 1000 Berlin und 8000 München | HEAD-CONTACTED ELECTRICAL ROTARY CAPACITOR WITH AT LEAST TWO SWITCHABLE INDIVIDUAL CAPACITIES AND METHOD FOR THE PRODUCTION THEREOF |
| JPS60150617A (en) * | 1984-01-18 | 1985-08-08 | 松下電器産業株式会社 | Composite capacitor |
| GB2159329B (en) * | 1984-03-05 | 1988-03-09 | Swift 1711 Ltd | Multi-terminal interference suppression capacitor |
| JPS6230325U (en) * | 1985-08-07 | 1987-02-24 | ||
| DE102011118577B4 (en) * | 2011-11-15 | 2016-08-04 | Epcos Ag | Capacitor component and method for producing a capacitor component |
-
1981
- 1981-11-18 CA CA000390320A patent/CA1158730A/en not_active Expired
- 1981-12-09 GB GB8137046A patent/GB2089569B/en not_active Expired
- 1981-12-11 JP JP56198712A patent/JPS57124414A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB2089569A (en) | 1982-06-23 |
| GB2089569B (en) | 1985-06-05 |
| JPS57124414A (en) | 1982-08-03 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |