LU83979A1 - CONDENSER AND METHOD AND DEVICE FOR PRODUCING THE SAME - Google Patents

Description

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Illinois Tool Works Inc., 8501 West Higgins Road, Chicago, Illinois 60631, United States.

Capacitor and method and apparatus for making the same.

The present invention relates to capacitors wound in a layer or a stack and to a method and an apparatus for producing the same.

Such a method and such an apparatus are described in US Pat. No. 3,670,378. According to this publication, the method for manufacturing the capacitors comprises a first stage in which capacitor bodies are formed by alternately winding metallic and dielectric thin layers on a drum and at the same time winding separating layers between the capacitor bodies in order in this way to form a mother winding with alternating layers to form capacitor bodies and separating layers, in a next stage a metal sprayed cover layer is applied to the edges of the mother winding for connecting the metallic thin layers, after which the mother winding is separated perpendicular to the separating layers to form the individual capacitor bodies becomes. These resulting capacitor bodies have interwoven metallic layers which are separated by dielectric layers. The layers of a group comprising dielectric substrates and metallic thin layers protrude outwards on one side of the capacitor body, while another group of substrates and thin layers protrude on the other side of the capacitor body.

The metallic cover layer is attached in such a way that it electrically connects the metallic thin layers of the outwardly projecting group of layers to one another. Thus, two electrodes or sets of capacitor "plates" are provided which are dielectrically insulated from one another but are woven together.

With the above-mentioned device, it sometimes happens that in the winding process, the layers that are wound interweave or deviate from their intended paths, resulting in one or more. Layers is incorrectly located with respect to the adjacent layers. If the separation between the groups of layers is not sufficient, the capacitor can be short-circuited or can have a lower than the intended dielectric strength in one or more areas.

If the separation is extremely large, the resulting capacitance of the capacitor is reduced.

The object of the present invention is to provide a capacitor of high quality of the type already mentioned, which, however, has a different structure and whose manufacturing process is considerably cheaper.

Another purpose of the invention is to provide a device of the type mentioned which substantially reduces the possibility of a short circuit occurring due to improper arrangement of the metallic and dielectric thin layers in the capacitor being wound.

Another purpose of the invention is to provide a device of the type mentioned, wherein the production of capacitors can be done much faster than with the currently available apparatus.

Yet another purpose of the invention is to provide a device of the type mentioned which can apply the layers forming the capacitor directly -3- from the laminating or lay-up rolls to a drum or a transfer wheel. Such a device prevents the supplied material from moving unaided through the space, thereby reducing the interweaving and consequently the incorrect alignment of the capacitor layers.

In order to achieve the above-mentioned objects, the capacitor according to the present invention comprises a number of layers with opposing edges, each layer comprising a dielectric substrate and a metallic thin layer, the metallic thin layer extending from one edge to the other, wherein each layer includes an area free of the metallic thin layer, which is adjacent to, but is spaced from, the other edge, thus leaving a narrow band with a thin metal layer along the edge. the other edge, which is separated from the further part of the metallic thin layer by the said region, the layers being arranged such that the metallic thin layer is separated from one layer by dielectric material of the metallic thin layer of the adjacent layer, the Layers are offset with respect to one another in such a way that on one side of the capacitor the edges of the first group of layers lie past the other edges of a second group of layers and on an opposite side of the capacitor the edges of the second group of layers lie outwards at the other edges of the the first group of layers lie past, the layers of the first group and the layers of the second group alternating with one another, and the outward edges of each group being covered with an electrically conductive material in order to electrically connect the metallic thin layers of each group to one another, being there s narrow band along the edge with the metallic thin layer separates the adjacent coating material from the metal-free area.

The method according to the invention comprises the provision of first and second material webs, each with a dielectric substrate, a cover layer made of a metallic thin layer and a narrow, parallel, longitudinal metal-free area; cutting the webs along the parallel lines offset with respect to the metal-free areas to form strips, each having a narrow `` -4- = band with a thin metallic layer along the edge extending from a longitudinal edge of the strip extends inward towards the metal-free area; alternately winding the strips of the first and second sheets on a drum, in which winding the strips of one sheet are displaced with respect to the strips of the other sheet to form a number of adjacent rings with a capacitor structure, each alternately arranged metallic have dielectric layers, and in each construction the layers of the strips of each web in question project sideways from the band along the edge with the metallic: thin layer of the strips of the other web; covering laterally protruding parts of each assembly with a metallic substance to electrically connect the metallic thin layers of the respective tracks of the assembly and separating the assembly transversely with respect to the strips for forming capacitors.

The device according to the invention comprises first and second feed rolls for webs, each web having a dielectric substrate with a metallic thin cover layer, a rotatable drum which is spaced apart from the feed rolls, first and second laminating rolls which are laminated rolls spaced apart along the Circumferential of the drum, a free tension sensing roll associated with each laminating roll spaced parallel to the associated laminating roll to form a pair of rolls therewith, a single web being stretched and stretched over each pair of rolls, and means for cutting the web in strips before winding the strips onto the drum so that alternating layers of metallic and dielectric material are provided, the laminating rolls being close enough to the drum and the cutting means close enough to the laminating rolls, such that the strips are in front of the Wrap the same on the drum are supported over almost their entire length.

The invention may also include applying a thin layer of adhesive to at least a portion of the electric field regions of a capacitor on one of the webs, but not applying the adhesive in the area where the web is cut or in laterally projecting portions of the Structure where contact is made with the metallic cover layer by spraying. The purpose of the adhesive, if necessary, is to fix the laminated structure so that the wound capacitor structure can be handled without breaking the laminate '-5-

According to another aspect of the invention, the webs can be passed through a station where a number of laser beams can burn the metal away to accurately form spaced apart metalized areas. These demetallized areas can be much narrower when burned away using a laser than is possible with the material commercially available with conventional demetallized zones, • which zones are much wider than necessary for low voltage capacitors.

The invention is explained below with reference to an embodiment with reference to the drawing.

Show it :

1 schematically shows a view of the device which is constructed according to the invention and is intended for carrying out the method according to the invention;

Figure 2 is a partial view in section along the line II-II in Fig. 1.

3 shows a partial view from above on an enlarged scale of the structure according to FIG. 2;

; Fig. 4 is an enlarged partial view in section along the line IV-IV

in Fig. 3;

Fig. 5 is an enlarged schematic. View, partly in section along the line V-V in Fig. 1;

6 shows a considerably enlarged partial view in section of parts of the capacitor according to the invention;

FIG. 7 shows an enlarged part of FIG. 2, a structure for applying an adhesive to the web being shown; and

Fig. 8 is a schematic view of the laser burn-off station which forms the demetallized zones when the web is withdrawn from the feed roll.

-6-.

Pig. Figure 1 shows a pair of feed rolls 2, 4 from which webs A and B are drawn. Each of the webs A and B comprises a dielectric substrate 6 and a metallic thin layer 8. The substrate 6 can be made of a suitable plastic, such as the synthetic resin sold under the trademark "Mylar". The thin layer 8 can be a vapor-deposited aluminum and both the substrate 6 and the metallic thin layer 8 are extremely thin. For example, but not by way of limitation, the substrate 6 may have a thickness of 25 micrometers or less, while the thickness of the metallic thin layer 8 may be approximately 0.05 micrometers. Each lane A and B has a number of parallel demetallized or metal-free areas 10, as best shown in Figures 3 and 4 for lane B

emerges. However, it will be clear that the same series of demetallized areas are provided on lane A. The tracks A and B can be provided with previously formed demetalized areas 10, or these areas can be formed by a laser burn-off method, as will be described in more detail below. In any case, the webs pass over a series of rollers for cutting into strips or for continuous or alternating winding on a drum or a transmission wheel 20 with a large diameter.

More particularly, the web A passes over a free roller 12a, the axis of rotation of which can be displaced to regulate the weaving of the web A. The free roller 12a reciprocates as a unit with the feed roller 2 under the control of a conventional angle guide scanner, not shown, for controlling the weaving operation. The web runs from the free roller 12a along the aforementioned angular guide scanner to a free tension roller 14a. The free tension sensing roller sends a signal to a variable brake clutch (not shown) on which the feed roller 2 is attached. This closed loop control keeps the voltage at any predetermined value. The device also includes a laminating or application roll 16a. Between the rollers 14a and 16a there is arranged a cutting station for the web, where the web A is cut into a number of strips before it runs around the support roller 16a and is wound on the drum or on the transfer wheel 20. In the same way, the web B passes over a displaceable free roller 12b and from there after a free tension sensing roller 14b along the cutting station to the laminating or support roller 16b, the free roller 12b for regulating the weaving of the web B to a not shown, second '-7-

Angle guide scanner reacts while the free tension sensing roller 14b again sends a signal to a variable brake clutch, not shown, on which the feed roller 14 is attached to maintain the tension at a predetermined value.

The cutting station for the web B comprises a number of spatially parallel cutting devices, such as knives 21b # which cooperate with a polished web support beam 22b over which the web B passes. In the same way, the cutting station for the web A comprises a number of spatially parallel knives 21a (FIG. 7) which cooperate with a web support beam 22a. From each path, the cutting ° station forms a number of strips which go directly onto the rolls 16a or 16b. depending on the application, and from these rolls onto the drum 20. As a result, the strips are supported over almost their entire length before they are wound onto the drum 20. FIG. Because the strips do not move through a room unsupported, weaving is excluded and the strips can be applied precisely to the drum. This is a significant difference from the existing devices, in which edge guides are used to prevent the strip from being woven, which, however, cannot always be avoided.

The laminating or support rollers press against the drum or on the transfer wheel 20 and the knives can be directly effective in narrow slots on the rollers 16a and 16b. In any case, the device for cutting the webs causes the knives to cut smoothly without the web material being able to crumple. This is particularly important because it is difficult to get smooth cuts without crumpling in web material that is as thin as the material used in the present invention. In the device according to the invention, the rollers 16a and 16b can either lie at an angle of 90 ° with respect to one another, as shown in FIG. 1, or at an angle of 180 °.

The web B is cut into a number of strips 18b as shown in Figures 2-4. The web A is also cut, whereby strips 18a are obtained which, like the strips 18b, ultimately become capacitor layers (FIG. 6). The cut lines for web B have been offset with respect to the demetallized areas so that strips 24 with a thin metal layer along the edge of each: -8-

Strip 18b are formed. A similar cutting operation is performed for web A, except that the cut line for each knife 21a is offset from that shown in FIG. 3 to form a similar band 24 with a metal layer along the edge of strips 18a.

Thus, if the knife 21b is on the left side of the demetallized area 10 for cutting the web B, as can be seen in FIG. 3, then for the web A the knife 21a will be on the right side of the adjacent demetallized area, as with the arrows 21aa in Fig. 3 is indicated.

The strips are simultaneously applied around drum 20 to form the layered pattern shown in FIG. A number of rings 30 with a capacitor structure are formed, from which individual capacitors can be formed. For the sake of clarity, only one of the rings 30 is shown in cross section in FIG. 5. In addition, the origin of the different strips, namely of A or B on one of the compositions 30 is shown in FIG. 3. It will be clear that the stripes are not drawn to scale, but rather shortened.

In any case, there is an initial winding of A-layers adjacent to the drum 20, as shown in Fig. 5 by the bottom five layers. Then, the strips are alternated and offset with respect to each other while being wound on the drum 20 to form the pattern shown in Fig. 5 with the alternating A and B layers. Then a group of A layers is wound over the group of alternating A and B layers. The inner and outer A layers serve as reinforcement, while the interwoven A and B layers or strips form the active part of the capacitor structure.

Each of the individual rings 30 can be removed from the drum 20 and the sides 32 and 34 can be covered with a metallic sprayed cover 40 in a conventional manner (Fig. 6). The ring 30 can then be cut perpendicular to the edges 32 and 34 to form a particular section with a capacitor structure.

This section can again be cut in the transverse direction to form individual capacitor units.

Fig. 6 shows an enlarged partial view through a number of woven layers of the capacitor. The figure shows that on one side of the -9-

Capacitor metallized thin films 8a and the substrate 6a sideways in front of the adjacent edges 36 of the. Project layers 18b.

The metallized sprayed cover layer 40 electrically connects the metallized thin layers 8a to form a set of capacitor electrodes or plates, this being made possible by the distance between the layers or strips 18a. The distance between the metallic cover layer 40 on the left in the upper part of FIG. 6 and the metallized layer 8b of the strip 18b is at least the same as the width of the metallized area 10 plus the width of the band 24 along the edge with the metallic thin layer . Indeed, the band 24 is a "floating" electrode. By providing the floating electrode formed by band 24, the full width of the demetallized region is used for dielectric separation along the surfaces of the layers, thereby reducing the possibility of short circuiting or a change in the capacitance of the capacitor of the prescribed value becomes.

On the other side of the capacitor, as shown in the lower part of FIG. 6, layers 18b project in front of the edge 37 of layers 18a to receive the right metal spray layer 40, which is shown in the lower part of FIG. 6. The band 24 along the edge with a metallic thin layer., In the lower part of FIG. 6, which lies on the layer 18a, also serves as a "floating" electrode, so that one has the full advantage of the demetallized areas, such as has been described above.

In another embodiment of the invention, shown in Fig. 7, any suitable adhesive can be applied to web A by means of an applicator 50 located at a location just in front of where that Cutting the web takes place. A useful type of adhesive is epoxy, but the invention is not so limited. The adhesive is not applied in the area where the cutting is to be made or in the area of the web where the metallic spray is to be applied. The purpose of the adhesive is, if necessary, to hold the laminate together after it is wound onto the drum 20 so that the structures 30 can be handled without breaking the laminate. The adhesive can be applied and spread with a layer thickness that is substantially less than 1 micrometer, and the adhesive can therefore be used.

; ‘-10- without actually reducing the real capacity / volume ratio.

The sheet material used in the present invention can be purchased with the demetalized area. However, these demetallized areas are usually larger than is necessary for low-voltage capacitors. Accordingly, as shown in Fig. 8, it is possible to form the demetalized regions 10 when the web A or web B is withdrawn from the feed roll. This can be done by passing the web through a laser burn-off station 52 where laser beams 53 '' can be used to burn the deposited metal and to form an extremely narrow demetallized area 10, which area is much smaller than the areas present on commercially available railways. This reduces the material costs and also reduces the dimensions of the capacitor. Voltage sensing systems and edge guide control systems used in the present invention are commercially available.

Claims (15)

1. A capacitor, characterized by a number of layers with opposing edges, each layer comprising a dielectric substrate and a metallic thin layer, the metallic thin layer extending from one edge to the other edge, each layer comprising an area which is free of the metallic thin layer, and this is adjacent to the, but is at a distance from the other edge so as to leave behind a narrow band with a metallic thin layer 'along the edge at the other edge which passes through said area is separated from the further part of the metallic thin layer, the layers being attached such that the metallic thin layer is separated from one layer, by dielectric material of the metallic thin layer of the adjacent layer, the layers being offset with respect to one another in this way, that on one side of the capacitor the edges of the first group layer They lie outside the other edges of a second group of layers and on an opposite side of the capacitor, the edges of the second group of layers lie outwards past the other edges of the first group of layers, the layers of the first group and the layers of the second group being opposite one another alternate, and wherein the outward edges of each group are covered with an electrically conductive material to electrically interconnect the metallic thin layers of each group. 2. Capacitor according to claim 1, characterized in that the metal-free area and the narrow metallic thin layer along the edge together have a width which forms a small part of the width of the associated layer. 3. A capacitor according to claim 2, characterized in that reinforcing layers are provided on opposite sides of the first and second groups of layers. 4. A process for the production of capacitors, characterized in that the process comprises the following stages: the procurement of first and second material webs, each with a dielectric substrate, a cover layer made of a metallic thin layer and narrow, parallel, longitudinal, metal-free regions; -12- »- the cutting of the webs along the parallel lines, which are offset with respect to the« metal-free areas, to form strips, each of which has a narrow band with a thin metallic layer along the edge which extends from a longitudinal edge the strip extends inward towards the metal-free area; - alternately winding the strips of the first tone of the second sheets onto one. A drum in which winding the strips of one web are displaced with respect to the strips of the other web to form a number of adjacent rings with a capacitor structure, each having alternating metallic dielectric layers, and in each structure the layers of Strips of each relevant web project sideways from the band along the edge with the metallic thin layer of the strips of the other web; covering laterally protruding parts of each assembly with a metallic substance to electrically connect the metallic thin layers of the respective tracks of the assembly and separating the assembly transversely with respect to the strips for forming capacitors, 5. A capacitor according to claim 4, characterized by energizing the tracks over a length of each of them and cutting the tracks in the tensioned part. 6. The method according to claim 5, characterized by the application of an adhesive «between the tapes of each structure which have to be wound. 7. A device for producing capacitors, characterized by first and second feed rolls for webs, each web having a dielectric substrate with a metallic thin cover layer, a rotatable drum which is spaced from the feed rolls, first and second laminating rolls, which laminating rolls in Spaced apart along the circumference of the drum, a free tension sensing roll associated with each laminating roll spaced parallel to the associated laminating roll to form a pair of rolls therewith, a single web being stretched and tensioned over each pair of rolls, and means for cutting the web into strips before winding the strips onto the drum so as to provide alternating layers of metallic and dielectric material, the laminating rolls being close enough to the drum and the cutting means close enough to the laminating rolls, in such a way that the strips before wrapping the same on the drum i. . * -13- ä. / E are supported over almost their entire length. 8. The device according to claim 7, characterized in that the laminating rolls are approximately at an angle of 90 ° 'with respect to each other around the circumference of the drum. 9. The device according to claim 7, characterized in that the laminating rolls are approximately at an angle of 180 ° with respect to each other around the circumference of the drum. 3rd 10. The device according to claim 8, characterized by between the rollers; a pair of lying means for applying adhesive to the surface of a web. 11. The device according to claim 10, characterized in that the means for applying adhesive are arranged between the tension sensing roller and the cutting means. 12. The apparatus of claim 11, characterized by laser organs for forming a number of longitudinal parallel metal-free areas on a web before the web is cut. 13. The apparatus according to claim 9, characterized by means lying between the rollers of a pair for applying an adhesive to the surface of a web. 14. The apparatus according to claim 13, characterized in that the means for applying the adhesive are arranged between the tension sensing roller and the cutting means. 15. The apparatus according to claim 14, characterized by laser organs for forming a number of longitudinal parallel metal-free areas on a web before the web is cut.