Method for producing an arrester, and arrester

Abstract

An arrester and a method for producing an arrester are disclosed. In an embodiment the method includes providing at least three green layers, wherein each layer includes at least one green sheet, introducing at least one hole into a first layer and applying an electrically conductive material for forming inner electrodes to a second layer and a third layer. The method further includes laminating the layers to form a green stack, wherein the first layer is arranged between the second layer and the third layer, separating the green stack into individual components and compacting the individual components, wherein laminating the layers and compacting the individual components are effected in a single temperature process by co-firing.

Claims

1. A method for producing an arrester, the method comprising: providing at least three green layers, wherein each layer comprises at least one green sheet; introducing at least one hole into a first layer; applying an electrically conductive material for forming inner electrodes to a second layer and a third layer; laminating the layers to form a green stack, wherein the first layer is arranged between the second layer and the third layer; separating the green stack into individual components; and compacting the individual components, wherein laminating the layers and compacting the individual components are effected in a single temperature process by co-firing.

2. The method according to claim 1, further comprising: applying a metal paste to at least a partial region of an outer face of the individual components; and firing the metal paste for forming at least one outer electrode.

3. The method according to claim 1, wherein the layers have the same material composition.

4. The method according to claim 1, wherein the layers comprise a ceramic material.

5. The method according to claim 4, wherein the individual components are compacted by debindering and sintering of the individual components under a defined temperature and atmosphere.

6. The method according to claim 1, wherein the layers comprise glass.

7. The method according to claim 6, wherein the individual components are compacted by way of a glass transition.

8. The method according to claim 1, wherein the electrically conductive material is applied in a predetermined pattern to outer faces of the second layer and the third layer, and wherein the second layer and the third layer are laminated with the printed outer faces inward onto the first layer to form the green stack.

9. The method according to claim 8, wherein the pattern is chosen in such a way that the at least one hole in the first layer is covered at least partially on both sides with the electrically conductive material.

10. The method according to claim 1, wherein the electrically conductive material is applied to the second layer and the third layer by screen printing.

11. The method according to claim 1, wherein, after separation, the electrically conductive material protrudes at at least one side edge of each individual component.

12. The method according to claim 1, further comprising providing an activation material in the first layer, wherein the activation material is arranged at least partially in the hole.

13. An arrester for protecting against overvoltages comprising: a plurality of layers arranged one above another; and at least one cavity which leads through at least one layer, wherein the arrester comprises inner electrodes, which adjoin the cavity, and wherein the arrester is produced according to the method of claim 1.

14. The arrester according to claim 13, wherein the layers comprise a cover layer and a base layer, which delimit the cavity toward a bottom and a top, and wherein the inner electrodes are arranged on the cover layer and the base layer.

15. The arrester according to claim 14, wherein the inner electrodes have an areal form and completely cover the cavity toward the bottom and the top.

16. The arrester according to claim 13, wherein the layers comprise a ceramic material and/or glass.

17. A method for producing an arrester, the method comprising: providing at least three green layers, wherein each layer comprises at least one green sheet; introducing at least one hole into a first layer; applying an electrically conductive material for forming inner electrodes to a second layer and a third layer; laminating the layers to form a green stack, wherein the first layer is arranged between the second layer and the third layer; separating the green stack into individual components; applying a metal paste to at least a partial region of an outer face of each individual component; and compacting the individual components, wherein laminating the layers, compacting the individual components and firing the metal paste are effected in a single temperature process by co-firing.

18. A method for producing an arrester, the method comprising: providing at least three green layers, wherein each layer comprises at least one green sheet; introducing at least one hole into a first layer; providing an activation material in the first layer, wherein the activation material is arranged at least partially in the hole; applying an electrically conductive material for forming inner electrodes to a second layer and a third layer; laminating the layers to form a green stack, wherein the first layer is arranged between the second layer and the third layer; separating the green stack into individual components; and compacting the individual components, wherein laminating the layers and compacting the individual components are effected in a single temperature process by co-firing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The drawings which are described hereinbelow are not to be understood as true to scale. Instead, individual dimensions may be shown on an enlarged scale, on a reduced scale or else in distorted form for better illustration.

(2) Elements which are equal to one another or which perform the same function are denoted by identical reference signs.

(3) In the drawings:

(4) FIG. 1 shows a sectional illustration of an arrester according to a first exemplary embodiment;

(5) FIG. 2 shows a plan view onto the arrester as shown in FIG. 1;

(6) FIG. 3 shows a sectional illustration of an arrester according to a second exemplary embodiment;

(7) FIG. 4 shows a plan view onto the arrester as shown in FIG. 3;

(8) FIG. 5 shows method steps for the production of an arrester; and

(9) FIG. 6 shows a method step for the production of an arrester.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(10) FIGS. 1 and 2 show an arrester 1 for protecting against overvoltages according to a first exemplary embodiment. The arrester 1 is in particular a gas arrester of multi-layered design.

(11) The arrester 1 comprises a main body 30. The main body 30 has a multi-layered construction. The main body 30 comprises a first layer 10 or main layer 10. The main body 30 comprises a second layer 11 or base layer 11. The main body 30 comprises a third layer 12 or cover layer 12.

(12) The layers 10, 11, 12 may each be produced from one or more sheets, in particular green sheets, arranged one above another. By way of example, one or more of the layers 10, 11, 12 are each formed from a multiplicity of sheets, for example, in each case from 20 sheets. In this case, the layers 10, 11, 12 are each formed as sheet assemblies. However, the layers 10, 11, 12 may each also be formed from only one sheet. The number of sheets used depends on the thickness of the sheets and on the required properties of the arrester 1. The layers 10, 11, 12 are arranged one above another, with the main layer 10 being arranged between the base layer 11 and the cover layer 12.

(13) The layers 10, 11, 12 preferably have the same material composition. In addition to an inorganic binder, the layers 10, 11, 12 comprise a material which is compacted readily at high temperatures. By way of example, the layers 10, 11, 12 comprise a ceramic. The ceramic is distinguished by a low dielectric constant and good sintering properties. As an alternative or in addition, the layers 10, 11, 12 may also comprise glass.

(14) The main layer 10 comprises a hole or a cavity 4. The cavity 4 penetrates completely through the main layer 10. The cavity 4 is preferably closed completely toward the outside. In particular, the cavity 4 is delimited toward the top and bottom by the base layer 11 and the cover layer 12.

(15) The shape of the cavity 4 is preferably translationally invariant with respect to the stacking direction of the layers 10, 11, 12. In particular, the cavity 4 has the shape of a right cylinder. In this case, the side walls delimiting the cavity 4 extend perpendicularly to a basic area, in particular perpendicularly to a base area or top area delimiting the cavity 4. The cavity 4 has in particular a basic area parallel to the layer planes and a height along the stacking direction of the layers 10, 11, 12. The height of the cavity 4 corresponds in particular to the thickness of the main layer 10.

(16) The cavity 4 is filled with a gas. The type of gas depends on an atmosphere during the production of the arrester 1, in particular on a sintering atmosphere during the sintering of the layers 10, 11, 12. By way of example, sintering is carried out with exclusion of oxygen. By way of example, halides may also be added to the atmosphere. By way of example, the gas contains nitrogen.

(17) An activation material 5, for example, graphite, may furthermore be arranged in the cavity 4, in particular on the side walls of the main layer 10 which delimit the cavity 4. The formation of an arc can be assisted by the activation material 5. The activation material 5 thus serves as an ignition aid. The activation material 5 may cover merely partial regions of the side walls as narrow strips, or else the complete side walls of the cavity 4.

(18) The arrester 1 furthermore comprises inner electrodes 3. The inner electrodes 3 are arranged in each case on the cover layer 12 and the base layer 11. The cover layer 12 and the base layer 11 thus represent electrode-carrying layers. By way of example, the inner electrodes 3 comprise copper, tungsten and/or nickel.

(19) The inner electrodes 3 extend parallel to the layers 10, 11, 12. In this exemplary embodiment, the inner electrodes 3 extend in an alternating manner as far as a side edge 7 of the main body 30. This means that an inner electrode 3 is guided to a first side edge 7 (right-hand side edge in FIG. 1), while the inner electrode 3 in question does not extend as far as the opposite second side edge 7 of the main body 30. A further inner electrode 3 extends as far as the second side edge 7 (left-hand side edge in FIG. 1), but not as far as the opposite first side edge 7. However, inner electrodes 3 which are not guided as far as the side edge 7 at all but instead serve as conductive electrodes for the flashover (not shown explicitly) are also conceivable.

(20) The inner electrodes 3 delimit the cavity 4 toward the top or bottom. In this respect, the inner electrodes 3 can have an areal form, and therefore they cover the cavity 4 completely from the top and/or bottom. In other words, the respective inner electrode 3 can completely cover the layer 11, 12 on which it is arranged at least in the region of the cavity 4. As an alternative thereto, it is also possible for at least one of the inner electrodes 3 to be formed merely as a narrow line and to protrude into the cavity 4 at a top side and/or at a bottom side of the cavity 4.

(21) For connecting the inner electrodes 3, outer electrodes 6, for example, in the form of metal caps, are arranged on the end sides of the main body 30. The outer electrodes 6 preferably comprise copper. In this exemplary embodiment, the outer electrodes 6 are arranged at the opposing end sides of the main body 30. The outer electrodes 6 are preferably attached to the main body 30 by means of hard soldering. The inner electrodes 3 are alternately connected to the outer electrodes 6 for contacting the arrester 1.

(22) The arrester 1 is preferably in the form of an SMD component, i.e., in the form of a surface-mountable component. By way of example, the arrester 1 is formed for assembly on a printed circuit board.

(23) FIGS. 3 and 4 show an arrester 1 for protecting against overvoltages according to a second exemplary embodiment. Hereinbelow, only the differences between the two exemplary embodiments will be explained.

(24) In contrast to the arrester 1 shown in FIGS. 1 and 2, the inner electrodes 3 are guided on both sides as far as the side edge 7 of the main body 30. In other words, each inner electrode 3 extends as far as the two side edges 7 of the main body 30. It is thus possible to take alternative installation situations for the arrester 1 into consideration.

(25) In this exemplary embodiment, the outer electrodes 6 are not arranged on the end sides of the main body 30 for contacting the inner electrodes 3. Since the inner electrodes 3 protrude on both sides as far as the edge of the main body 30, the outer electrodes 5 are formed on the opposing longitudinal sides or main faces of the main body 30. In particular, the outer electrodes 6 are applied to the main body 30 from above and below in the form of metal caps. In this case, the outer electrodes 6 protrude partially onto the end sides of the main body 30 for connecting the inner electrodes 3.

(26) For the rest, the features described in conjunction with FIGS. 1 and 2 also apply to the arrester 1 shown in FIGS. 3 and 4.

(27) FIGS. 5 and 6 show method steps for the production of an arrester. The method will preferably produce an arrester 1 as shown in FIGS. 1 to 4.

(28) Firstly, three green layers 10, 11, 12 are provided. The layers 10, 11, 12 comprise the same material. In this case, at least one sheet is provided for each of the green layers 10, 11, 12. These are preferably green sheets, for example, ceramic green sheets.

(29) The sheets preferably comprise a ceramic powder. A suitable ceramic base material here are all ceramics whose sintering temperature lies below the melting temperature of the electrode materials used (in particular copper, tungsten and/or nickel) and which have a sufficient mechanical and electrical stability after the sintering. As an alternative thereto, glass-filled sheets are also conceivable.

(30) It is also possible for a plurality of sheets to be provided for each layer 10, 11, 12. The first layer 10 or main layer 10 of the arrester 1 is preferably formed from a plurality of first sheets. The second layer 11 or base layer 11 of the arrester 1 is preferably formed from a plurality of second sheets. The third layer 12 or cover layer 12 of the arrester 1 is preferably formed from a plurality of third sheets. The number of sheets used depends on the thickness of the sheets and on the required properties of the arrester 1. By way of example, the main layer 10 can comprise up to 20 sheets or more, with a thickness of, for example, in each case 40 m.

(31) Thereafter, at least one hole 4 is introduced into the first layer 10, for example, by lasering or punching. The hole 4 is provided to form the later gas inner space. The hole 4 penetrates through the first layer 10 and in particular the multiplicity of sheets of the first layer 10 completely.

(32) In an optional step, an activation material 5 may be introduced into the hole 4. In this case, by way of example, a graphite paste is introduced onto the side walls of the first layer 10, which delimit the hole 4.

(33) As an alternative thereto, the activation material 5 may also already be introduced during the construction of the first layer 10, before the hole 4 is produced. In particular, the activation material 5 may be introduced in this case between individual sheets of the first layer 10. In this case, a ring made up of activation material 5 is formed on the walls of the hole 4 during the formation of the hole 4.

(34) An electrically conductive material 13, in particular a metal paste, for forming inner electrodes 3 is then applied to the second layer 11 and the third layer 12. The material 13 is applied to an outer face 11a, 12a of the respective layer 11, 12. The material 13 is preferably printed onto the second and third layer 11, 12, e.g., by means of screen printing. By way of example, the electrically conductive material 13 may comprise copper, tungsten or nickel.

(35) The printing is effected in the form of certain patterns. By way of example, the electrically conductive material 13 can be applied as a continuous strip. The printing patterns are chosen in such a way that, after later singulation of the stack, the metal regions protrude at least partially at the side edge 7, and are thus accessible for electrical contacting from the outside. Furthermore, the printing patterns are chosen in such a way that the at least one hole 4 in the first layer 10 is covered on both sides, i.e., from the top and bottom, with the electrically conductive material 13.

(36) Then, the second layer 11 and the third layer 12 are laminated with the printed outer face 11a, 12a inward onto the first layer 10 to form a stack 20 (see FIG. 6). This lamination is effected in the green state of the layers under pressure and moderate temperature. By way of example, the lamination is effected at a temperature of 80 C. to 100 C.

(37) In a further step, the ceramic green stacks 20 are separated into individual components 30 (main bodies 30). This is effected by means of cutting or sawing, for example. The individual components 30 are then compacted in a single step under a defined temperature and atmosphere. If the layers 10, 11, 12 comprise a ceramic, the individual components 30 are debindered and sintered under a defined temperature and atmosphere in this step.

(38) Sintering is preferably carried out with exclusion of oxygen. In this case, the sintering temperature is dependent on the material used, and may lie between 900 C. and 1200 C. If glass-filled sheets are used, the compaction step is realized by way of a glass transition, rather than by way of sintering. In this case, the individual component 30 is exposed to a temperature which is lower than the temperature used for sintering.

(39) In a last step, a metal paste is applied to at least a partial region of the outer face of the respective individual component 30. Depending on the configuration of the inner electrodes 3, the metal paste may be applied to the end faces or the main faces of the respective individual component 30 (see FIGS. 1 to 4). The metal paste is then fired for forming the outer electrodes 6. The type and geometry of the outer electrodes 6 are chosen in such a way that a surface-mountable component similar to a multi-layered capacitor (MLLC) is formed.

(40) The lamination of the layers 10, 11, 12, the compaction of the individual components 30, and the firing are effected in a single temperature process by co-firing. Further temperature processes, which complicate the method, are superfluous.

(41) The advantage compared to conventional gas arresters consists in the fact that no individual elements, but instead multiple arrangements, need to be processed. This allows for a high degree of automation and also makes it possible to produce very small, miniaturized designs. Construction by means of individual sheets furthermore makes it possible to arrange the inner electrodes 3 freely. It is thus possible to combine an areal inner electrode 3 and electrodes which protrude into the hole 4 only as a narrow line.

(42) Electrodes which are not guided outward to the side edges 7 and serve as conductive electrodes for the flashover are also possible.

(43) The description of the subjects specified here is not limited to the individual specific embodiments. Instead, the features of the individual embodimentsas far as technically feasiblecan be combined with one another as desired.