Ceramic electrode, assembly comprising a ceramic electrode, arrangement comprising a ceramic electrode and method for producing a ceramic electrode

Abstract

To provide a ceramic electrode suitable for applying a high-frequency AC electric field to a human body or a mammalian body, and to provide a method of manufacturing the same.SOLUTION: A method for producing a ceramic electrode (1), comprising the steps of providing at least one first green sheet (2 '), structuring a metal layer (3 ') on a first surface (21 ') of the at least one first green sheet, forming a blank by applying a green sheet stack (4 ') comprising a second green sheet (41 ') to the first surface, debindering the blank, and constructing a dielectric layer (2) having a thickness (D) of less than or equal to 150 μm from one or more first green sheets by sintering the blank.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a ceramic electrode suitable for applying a high frequency alternating electric field to the human or mammalian body. Furthermore, the present invention relates to a method for manufacturing such an electrode. Finally, the present invention relates to an assembly comprising said ceramic electrode, and to an array comprising a plurality of ceramic electrodes. [Background technology]

[0002] Exposing cells to a high-frequency alternating electric field can inhibit cell division in living organisms. This mechanism can be applied to the treatment of some tumors. Specifically, the high-frequency alternating electric field disrupts the rapid and uncontrollable cell division of tumor cells. The alternating electric field specifically affects proteins that contribute to cell division, disrupting their function. Related methods have already been approved by the U.S. Food and Drug Administration (FDA). High-frequency alternating electric fields for anti-tumor cell therapy are also called "tumor-treating fields" (TTFs). The alternating electric field is delivered to the patient by electrodes placed around the area of ​​the body affected by the tumor. To date, the main application has been in the treatment of brain tumors, but in principle, it can also be applied to other types of cancer or tumors.

[0003] By selecting the appropriate frequency, selectivity can be achieved for different cell types, thereby reducing the side effects of the therapy. For example, U.S. Patent Application Publication No. 2003 / 0150372 and U.S. Patent No. 7,016,725 provide examples of methods and devices for the destruction of uncontrollably dividing cells.

[0004] The described method is of particular interest to electrodes for transmitting high-frequency alternating electric fields to the organism to be treated, where ceramic electrodes are particularly preferred, as they comprise a dielectric layer made of a ceramic material with a high dielectric constant.

[0005] For example, for such applications, Austrian utility model GM50248 / 2016 or PCT patent application WO 2019174719 discloses a polycrystalline ceramic solid, the general formula of whose main phases is as follows: (1-y)Pb a (Mg b Nb c )O 3-e +yPb a Ti d O3

[0006] Prior to this invention, conventional ceramic electrodes were typically 250 mm 2 or more electrode area Has.

[0007] However, the inventors have noticed that ceramic electrodes of this size do not fit well with the surface to which they are applied, such as the patient's body. This problem is particularly pronounced in areas of the body with highly curved surfaces, such as the head or other areas with complex contours. If the ceramic electrode is too large, it may be less comfortable to wear. Also, a large amount of contact gel is usually required. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] US Patent Application Publication No. 2003 / 0150372 [Patent Document 2] U.S. Patent No. 7,016,725 [Patent Document 3] Austrian utility model application GM50248 / 2016 [Patent Document 4] International Publication No. 2019174719 Summary of the Invention

[0009] Additionally, the inventors have found that smaller electrodes are more adaptable to circular or other contoured application sites.

[0010] This object is achieved by the electrode of claim 1. More advantageous implementations are obtained from the other claims.

[0011] In a first aspect, the present invention provides a ceramic electrode comprising a carrier element as a mechanical stabilizing member, a dielectric layer having a thickness (D) of 150 μm or less, and an electrode layer.

[0012] Such a thin dielectric layer allows for the miniaturization or reduction of the electrode for the above-mentioned applications while maintaining a high capacitance value, for example, of 20 to 50 nF. Here, the thickness of the dielectric is reduced from the typical thickness of about 1 mm to a value of 150 μm or less, i.e., a reduction of about one order of magnitude. This reduces the electrode area, for example, to about 1 / 10 to 1 / 50 of that of conventional electrodes. In other words, the size and weight of each electrode can be reduced while maintaining a high capacitance value.

[0013] However, the inventors of the present invention have noticed that the construction of such a thin dielectric layer may cause a concern that the stability required for application may be lost. To solve this problem, the present invention proposes separating the functions of a member for realizing the structure (here, the carrier element) and a dielectric member (i.e., the dielectric layer).

[0014] In this case, the carrier element is arranged to provide the ceramic electrodes with sufficient mechanical stability. As described below, the carrier element may, for example, fulfill this function by being fixedly attached to the electrode layers and / or the dielectric layers. The carrier element may, for example, comprise a ceramic material similar to that of the dielectric layers or may consist of the same material.

[0015] Preferably, the thickness of the carrier element, i.e. its extension in a direction corresponding to the thickness direction of the dielectric layer, is at least equal to the thickness of the dielectric layer, preferably much greater.

[0016] In principle, the carrier element may have any shape provided that it fulfills the function of mechanically stabilizing the thin dielectric layer.

[0017] The carrier element is preferably arranged on the side of the dielectric layer on which the electrode layer is provided, which has the application advantage that the dielectric layer can be in direct contact with the surface during use, for example in the treatment of tumors, with the dielectric layer facing the patient.

[0018] In principle, the carrier element may be constructed so that its surface overlaps most of the dielectric layer, which has the advantage that only a small portion of the dielectric layer is exposed, whereas if the exposed area is too large, it becomes fragile.

[0019] As an alternative technical solution, the carrier element may be constructed on some surfaces, thus allowing for a lower weight and also improving the patient's comfort during application.

[0020] According to one preferred embodiment of the ceramic electrode, the electrode layer is arranged on the first surface of the dielectric layer and covers a part of the dielectric layer, which means that in this case the electrode layer is not present in the free area of ​​the first surface of the dielectric layer, which is in contact with the carrier element.

[0021] Within the scope of the present invention, the dielectric layers are preferably planar, i.e., their extension in the transverse direction, i.e., perpendicular to the thickness direction, is much greater than their extension in the thickness direction. The electrode layers are likewise preferably planar.

[0022] Here, the free area may be a continuous area of ​​the first surface of the dielectric layer, but the free area may also consist of areas that are spatially bounded, for example by carrier elements.

[0023] By providing a free area of ​​the dielectric layer on the first surface on which the electrode layer is provided, the carrier element can come into contact with this free area. The carrier element is preferably made of a ceramic material or may be made of the same material as the dielectric layer, which allows for an excellent mechanical contact or bond between the carrier element and the dielectric layer.

[0024] The electrodes are preferably produced by sintering, so that, for example in the sintering process described below, adhesion in the free area between the dielectric layer and the carrier element can be achieved particularly efficiently, and the carrier element can thus preferably function as a stabilizing element.

[0025] Here, the carrier element may cover part or all of the free area.

[0026] Alternatively, the carrier element may be constructed in the region of an electrode layer.

[0027] According to another preferred embodiment, the free area of ​​the first surface of the dielectric layer is a lateral edge area of ​​the first surface of the dielectric layer.

[0028] The dielectric layer has an edge, i.e., an end portion extending along the lateral direction of the dielectric layer, and the lateral edge region may be a section or area of ​​the first surface that contacts the edge.

[0029] The lateral edge region may be constructed, for example, along the entire edge of the dielectric layer, i.e., the lateral edge region may surround the inner region of the first surface of the dielectric layer, in which the electrode layer is preferably constructed, i.e., the lateral edge region may surround the area covered by the electrode layer.

[0030] Since the carrier element is at least partially constructed in the free area, in this preferred embodiment in the side edge area, the carrier element can form a frame-like structure, which can particularly advantageously ensure the mechanical stability of the ceramic electrode.

[0031] According to another preferred embodiment of the ceramic electrode, the width of the free area of ​​the side edge region may be equal to or greater than the thickness D of the dielectric layer. Here, width may be understood as the extension in the lateral direction.

[0032] According to the findings of the inventors of the present invention, the free region can efficiently support and reinforce the mechanical stability or structure of the ceramic electrode, provided that the absolute value of its width reaches at least the thickness of the dielectric layer and the carrier element is at least partially constructed in this free region.

[0033] According to another preferred embodiment, the width of the carrier element is equal to or greater than the thickness of the dielectric layer, where width may be understood as the extension in the lateral direction.

[0034] Due to this minimum width, the carrier element can contribute efficiently to realizing the stability of the ceramic electrode.

[0035] Here, the carrier element may particularly preferably have at least the size in at least one spatial direction of the free area.

[0036] That is, for example, if the carrier element forms a frame or part of a frame, the thickness may be the local direction measured from the edge of the electrode layer to the nearest point on the edge of the dielectric layer, in which case this definition applies both to the lateral edge region of the first surface of the dielectric layer and to the carrier element constructed in this region or part of this region.

[0037] According to another preferred embodiment, the ceramic electrode has a contact member that contacts the electrode layer.

[0038] Preferably, the contact member may provide external electrical contact to the ceramic electrode, i.e., the contact member is for transmitting, for example, an AC electric field to the electrode layer.

[0039] For example, the contact members may be constructed as vias. For example, the construction method described above can be used when the carrier element covers most of the dielectric layer, including the electrode layer located thereon. Such vias may preferably be arranged so as to be in direct contact with the electrodes.

[0040] In such cases, the vias may have a surface on the side not in contact with the electrode layer that terminates with, for example, one side of the carrier element, allowing for solder connection to another component, such as, for example, a flexible circuit board.

[0041] As an alternative technical solution, the contact member may be a contact layer, which may be constructed on the surface of the carrier element opposite the dielectric layer and used as a contact surface during application, in which case the contact member may contact the electrode by means of a cavity.

[0042] According to another embodiment of the ceramic electrode, the thickness D is 20 μm to 100 μm. More preferably, the thickness D is 30 μm to 80 μm. The thickness D may be, for example, 40 to 60 μm.

[0043] Within the above thickness range, the electrode is neither too thin nor too fragile. The inventors of the present invention have discovered that electrodes with a thickness of less than 20 μm often lack the necessary stability, even when a carrier element is present. This is because the grain size of ceramic materials suitable for dielectric layers is on the order of several μm to several tens of μm. In other words, when the thickness is less than 20 μm, the layer may be composed of only a few crystal grains in the thickness direction, which, even when a carrier element is present, will still have a significant adverse effect on the stability of the layer.

[0044] Moreover, if the electrode is too thin, there is a possibility that the insulating properties of the dielectric layer cannot be sufficiently ensured.

[0045] This means that the dielectric layer must be able to withstand an operating voltage of at least 150 V. For safety reasons, it is preferable to have a dielectric strength of 500 V, since any overvoltages that may occur within this range must not be applied to the patient.

[0046] The above advantages can be more suitably realized when the thickness is at least 30 μm or 40 μm.

[0047] Furthermore, according to the discovery of the present inventors, when the thickness is 100 μm or less, the area of ​​the electrode can be reduced more significantly, and therefore, when the electrode thickness is 80 μm or less, or when the electrode thickness is 60 μm or less, the above effect can be more suitably achieved.

[0048] According to one preferred embodiment of the ceramic electrode, the dielectric layer comprises a ceramic material, which has a dielectric constant of 15,000 or greater.

[0049] With a dielectric constant higher than 15,000, a high-capacity electrode can be manufactured preferably in a temperature range of 30 to 42° C., which also contributes to miniaturization.

[0050] Preferably, the ceramic material has a dielectric constant of 25,000 or more, more preferably 40,000 or more.

[0051] Also, within the above temperature range, the loss factor of the ceramic material is preferably less than 0.2, more preferably less than 0.12, and even more preferably less than 0.05.

[0052] Preferably, (1-y)[Pb a (Mg b Nb c )O 3-e ]+y[Pb a Ti d O3] and Ba with dopants including manganese and rare earth elements. m (Ti n Zr p)If it is a ceramic material selected from O3, such a high dielectric constant can be achieved.

[0053] (1 - y)[Pb a (Mg b Nb c )O 3-e +y[Pb a Ti d O3], preferably, 0.055 ≤ y ≤ 0.065, 0.95 ≤ a ≤ 1.02, 0.29 ≤ b ≤ 0.36, 0.63 ≤ c ≤ 0.69, 0.9 ≤ d ≤ 1.1, 0 ≤ e ≤ 0.1.

[0054] The substance Ba m (Ti n Zr p )O3 preferably satisfies the conditions of 0.95 ≤ m ≤ 1.05, 0.8 ≤ n ≤ 0.9, 0.1 ≤ p ≤ 0.2, m < n + p.

[0055] As described above, this substance is doped with manganese and rare earth elements. Here, if the ratio of manganese is x and the ratio of rare earth elements is z, more preferably, 0.0005 ≤ x ≤ 0.01, 0.001 ≤ z ≤ 0.05.

[0056] The dielectric constant in the range of 15000 - 25000 can be achieved by the ceramic material represented by the formula (1 - y)[Pb a (Mg b Nb c )O 3-e +y[Pb a Ti d O3].

[0057] For the formula Ba m (Ti n Zr p)Ceramic materials represented by O3 can achieve a dielectric constant of 20,000 to 40,000.

[0058] Preferably, the ceramic electrode has the following size: for example, 15 to 100 mm 2 The maximum thickness may be, for example, 300 to 700 μm.

[0059] Maximum thickness may be understood as the maximum extension in a direction perpendicular to the plane of stretching of the dielectric layer.

[0060] More preferably, the basic or cross-sectional area of ​​the ceramic electrode is 20 to 70 mm 2 Range Within 20 to 50 mm, preferably 2 More preferably, it is in the range of 25 to 40 m. m 2 The cross-sectional area is within the range of, for example, 25 mm 2 or 36mm 2 may be.

[0061] The maximum thickness may be, for example, between 400 and 600 μm, for example 500 μm.

[0062] The cross-sectional area of ​​the ceramic electrode or the basic area thus formed is preferably equal to the area of ​​the dielectric layer, the shape of which is in principle not limited, although it is preferably circular, rectangular or square.

[0063] From an application point of view, a circular shape is particularly preferred, as it avoids sharp edges or corners that are prone to breakage, and also improves wearing comfort.

[0064] In view of the manufacturing process described below, a rectangular or square shape is preferred, especially when applying structured patterns.

[0065] The size is preferably suitable for achieving good wearing comfort in applications such as cancer therapy, as the electrodes are small enough not to protrude from complex or circular surfaces, such as the patient's head.

[0066] That is, the ceramic electrodes are arranged so as to be suitable for attachment to the human body or part of the human body.

[0067] According to another preferred embodiment, the ceramic electrode may have one or more cavities, preferably constructed in the carrier element.

[0068] Particularly preferably, the cavities may be constructed in a regular pattern in the carrier element, for example the carrier element may constitute a lattice surrounding each cavity.

[0069] In this way, the low weight of the ceramic electrode can be maintained. The alternating structure of carrier elements and cavities ensures higher stability than when the same material is used as the carrier element but surrounding a single cavity.

[0070] According to another aspect of the present invention, there is provided an assembly including a ceramic electrode according to the above embodiment disposed on a flexible circuit substrate.

[0071] That is, the ceramic electrode of the present invention may be part of the assembly of the present invention. The flexible circuit board can be electrically contacted with the outside, which may be realized, for example, by the contact member described above.

[0072] For example, the ceramic electrodes may be attached to the flexible circuit board in the assembly by solder connections.

[0073] Here, the flexibility of the substrate allows it to fit the surface of the patient's body, which is useful in applications. Here, flexibility means being able to bend or having a certain degree of flexibility.

[0074] According to another aspect of the invention, there is provided an array comprising a plurality of the ceramic electrodes or a plurality of the assemblies.

[0075] For example, in such an arrangement or array, 9 or 18 ceramic electrodes may be provided.

[0076] Such an array may be constructed to flexibly conform to the surface of the patient's body. In the present invention, the electrodes are significantly smaller than in the past, allowing the areas between the electrodes to be flexible.

[0077] According to another aspect of the present invention, there is provided a method for manufacturing the ceramic electrode described above. The method includes the steps of providing at least one first green sheet, building a metal layer on a first surface of the first green sheet, and forming a blank by attaching a green sheet stack including a second green sheet to the first surface. The method also includes the steps of degreasing the blank and then sintering it. The sintering process forms a dielectric layer having a thickness D from the one or more first green sheets. The thickness D is 150 μm or less.

[0078] That is, in principle, the dielectric layer may be composed of a single first green sheet. However, as an alternative technical means, multiple first green sheets may be provided and the dielectric layer may be composed of these first green sheets by the above process. However, it is preferable to use a small number of green sheets, that is, preferably one to four green sheets. When selecting the number and thickness of the green sheets, it is necessary to ensure that the thickness D of the dielectric layer is 150 μm.

[0079] Preferably, according to the above aspect, the carrier element is produced from the green sheet laminate by degreasing and, in particular, sintering.

[0080] In the sintering process, the metal layer preferably constitutes the electrode layer of the ceramic electrode.

[0081] Preferably, the dielectric layer is made of the material described above for the ceramic electrode, and in this case, the sintering temperature can be set within the range of 1000 to 1500°C, preferably 1400 to 1450°C.

[0082] Depending on the method for adding the metal layer, particularly when a metal layer that will become an electrode layer upon sintering is formed by printing a metal paste, the above-mentioned electrode layer can be manufactured from this metal layer by degreasing and sintering.

[0083] In order to withstand high temperatures, the metal and electrode layers may be made of, for example, palladium or a material made of palladium. Because materials such as palladium are expensive, it is preferable to construct the metal or electrode layers very thin.

[0084] In order to obtain a suitable size for the ceramic electrode of the present invention, the process of adjusting the size of the component in process must take into account shrinkage during sintering, if necessary.

[0085] Thus, by corresponding processes, devices having the above mentioned advantages can be manufactured.

[0086] According to one preferred embodiment of the method for manufacturing the ceramic electrode, a metal layer is constructed on the first surface of the first green sheet so that the metal layer is absent in the free area of ​​the first surface, in which case the green sheet stack may be added in direct mechanical contact with this free area.

[0087] Therefore, the first green sheet or a suitable ceramic material of the first green sheet is in contact with the material of the green sheet stack, for example, the second green sheet. The material of the second green sheet may preferably be the same as the material of the first green sheet. In this way, the green sheet stack and the first green sheet can be efficiently sintered, i.e., a stable connection can be formed by sintering.

[0088] According to another preferred aspect of the method, the green sheet stack has cavities or, in preparation for the process, the green sheets are configured with cavities or are made to have such cavities.

[0089] Here, the cavity may be understood as a cavity that opens in the thickness direction in the lamination direction and penetrates the green sheet laminate.

[0090] In this case, preferably, the cavities in the green sheet laminate are filled with a metal material, and in the process of adding the green sheet laminate, i.e., the process of forming a blank, the green sheet laminate is added so that the cavities filled with the metal material come into contact with the metal layer, i.e., the metal material comes into contact with the metal layer.

[0091] In this way, the metal layer and the metal material are firmly connected during the sintering process.

[0092] The metal material may be a via, or alternatively, a via that is configured with the metal material during sintering.

[0093] According to another preferred embodiment of the method, the green sheet laminate may have cavities, which are not filled with metal material before sintering, so that the cavities form openings towards which, after sintering, the metal layer or electrode layer constituted thereby is exposed and in contact with said openings so that a contact layer is built up after sintering.

[0094] In this case, the contact layer may correspond to or be the contact member.

[0095] Here, the contact layer may be built up, for example, by sputtering, an electroplating process, or by screen printing of a metal paste and subsequent firing.

[0096] These other methods of construction of the contact members, or the resulting contact members themselves, each offer different advantages.

[0097] An advantage of the solid or all-metal vias described above is that they are easy to manufacture, ie, can be inserted during the processing steps required to process the ceramic component.

[0098] The advantage of constructing the contact layer as a contact element is that it does not require the use of heavy solid materials, and materials that are not subject to or can withstand the harsh conditions of the sintering process can be used, providing greater flexibility in materials selection, and reducing material costs, resulting in cost savings and a lighter device.

[0099] Finally, any cavities remaining during the sintering process will adversely affect the stability of the blank in this process.

[0100] To improve the stability of the green sheet laminate or blank, the cavities may preferably be filled with a polymer paste before adding the green sheet laminate, and during the debinding and / or sintering process, this polymer paste may be removed again, preferably together with other organic components that are removed from the green sheets during these processing steps.

[0101] The residue is preferably completely removed during the degreasing process, but in some cases may be detached from the corresponding ceramic electrode during the sintering process.

[0102] The polymer paste may comprise, for example, polypropylene carbonate.

[0103] According to other aspects of the invention, other methods or variations of other methods for manufacturing ceramic electrodes are described, which may for example be the ceramic electrodes described above.

[0104] This method preferably provides a green sheet laminate including a second green sheet. The green sheet laminate is structured to form cavities and temporary carrier elements. The cavities and temporary carrier elements may be structured in a regular pattern. For example, the cavities formed by the temporary carrier elements may be separated from each other in the regular pattern. The method further includes forming a blank by adding one or more first green sheets to the structured green sheet laminate. A first surface of the first green sheet contacts the structured green sheet laminate. The method also includes degreasing and sintering the blank thus formed. A dielectric layer having a thickness D is formed from the one or more first green sheets by sintering. The thickness D is 150 μm or less, and a metal layer may then be formed. Preferably, the metal layer is formed on the first surface of the first green sheet. It is ensured that the metal layer is not present in the free area of ​​the dielectric layer. A contact layer may also be formed simultaneously.

[0105] Here, regardless of whether the dielectric layer is made up of one or more first green sheets, the basic prerequisites set forth in the above process apply equally.

[0106] Also, by sintering, the carrier element of the ceramic electrode is preferably constructed from the temporary carrier element.

[0107] An advantage of this process is that it allows the simultaneous formation of multiple cavities bounded by carrier elements, for example in a regular pattern, and in this way good stability can be achieved.

[0108] In other aspects, the materials and functions may correspond to the materials or functions of the other processes described above.

[0109] As described for the other processes, here too the cavities formed by structuring may be filled with a polymer paste, which is preferably removed during debinding and / or sintering.

[0110] The polymer paste used here may be the same as the polymer paste in the above method and has similar advantages.

[0111] According to another preferred embodiment of the method, the structuring is carried out by a punching or laser process, which are particularly preferred long-distance processes, making it possible to form elongated regular patterns, which allow the formation of multiple cavities and the production of multiple ceramic electrodes.

[0112] Another advantage of the latter process is that it allows the metal layer that will or can become the electrode layer to be built at the same time as the contact layer is built, or in the same process step.

[0113] In comparison with the previously described process, the cavity formed in the above process is particularly wide, thereby forming a surface large enough to subsequently produce an electrode layer at the bottom of the cavity, i.e., in the area of ​​the first surface of the first green sheet or dielectric layer.

[0114] Preferably, the metal layers and contact layers can here be produced by sputtering, electroplating processes or screen printing.

[0115] According to a preferred aspect of all processes or process embodiments described herein, the width of the free area may be equal to or greater than the thickness of the dielectric layer, which may have advantages, for example, with respect to ceramic electrodes.

[0116] Similarly, the width of the formed and configured carrier element may be at least as large as the thickness of the dielectric layer. [Brief explanation of the drawings]

[0117] The present invention will now be described more specifically with reference to exemplary embodiments and corresponding drawings, which, except where shown to scale, are for illustrative purposes only and may not be drawn to scale for clarity. [Figure 1] 1A and 1B are a schematic cross-sectional view and a schematic plan view of a ceramic electrode according to a first embodiment of the present invention; [Figure 2] FIG. 10 is a schematic cross-sectional view of a second embodiment of a ceramic electrode. [Figure 3] FIG. 10 is a schematic cross-sectional view of a ceramic electrode according to a third embodiment of the present invention. [Figure 4] FIG. 10 is a schematic cross-sectional view of a fourth embodiment of a ceramic electrode. [Figure 5] FIG. 10 is a schematic cross-sectional view of a ceramic electrode according to a fifth embodiment of the present invention. [Figure 6] 10A to 10C are schematic cross-sectional views illustrating processing steps for manufacturing a ceramic electrode according to a fourth embodiment. [Figure 7] 10A to 10C are schematic cross-sectional views illustrating processing steps for manufacturing a ceramic electrode according to a sixth embodiment. [Figure 8] 10A is a graph showing the temperature correlation of capacitance and the temperature correlation of loss factor for two ceramic electrodes according to the second embodiment; FIG. [Figure 9] 13A is a graph showing the temperature correlation of capacitance and the temperature correlation of loss factor for two ceramic electrodes according to the sixth embodiment; FIG. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0118] Fig. 1 is a diagram showing a first embodiment of a ceramic electrode 1 according to the present invention, in which Fig. 1a is a schematic cross-sectional view of the ceramic electrode 1, and Fig. 1b is a schematic plan view of the ceramic electrode 1.

[0119] The ceramic electrode 1 has a dielectric layer 2. The dielectric layer 2 is preferably made of a ceramic material having a high dielectric constant, preferably higher than 15,000.

[0120] For example, the ceramic material of the dielectric layer 2 is (1-y)[Pb a (Mg b Nb c )O 3-e ]+y[Pb a Ti d O3] materials or Ba with dopants including manganese and rare earth elements. m (Ti n Zr p )O3 material.

[0121] The dielectric layer 2 may have any shape. Preferably, the dielectric layer 2 may be rectangular, square or circular as shown. Here, the dielectric layer is constructed planar, i.e., the extension in the lateral direction of the dielectric layer is much greater than the thickness.

[0122] The dielectric layer is, for example, 15 to 100 mm 2 Preferably, the area is 20~50mm 2 For example, 36 mm 2 may be.

[0123] The dielectric layer is thinner than conventional dielectric layers. The dielectric layer has a thickness D of less than 150 μm.

[0124] The thickness D is preferably between 20 and 100 μm, and may be, for example, 40 μm, although as an alternative technical solution, the thickness may be 80 μm.

[0125] The dielectric layer 2 also has a first surface 21 and a second surface 22. The second surface 22 is the surface facing the patient in applications such as for treating tumors.

[0126] In a first embodiment of the present invention, an electrode layer 3 is provided on the first surface 21 of the dielectric layer 2. Preferably, the electrode layer 3 has the same basic shape as the dielectric layer 2 and may be centrally arranged relative to this dielectric layer. In this case, the electrode layer 3 is plate-shaped or circular and is arranged in the center of the dielectric layer 2.

[0127] However, the area of ​​the electrode layer 3 in the extension direction of the dielectric layer 2 (which is also the extension direction of the electrode layer 3) is smaller than the area of ​​the dielectric layer 2. In this way, the dielectric layer 2 is maintained such that no electrode is present in the free region 23 of the first surface 21, or is not covered by the electrode 3 in this free region.

[0128] In this embodiment, the free area is the side edge area of ​​the dielectric layer, i.e. in this case the free area is in direct contact with the edge of the dielectric layer 2.

[0129] In this embodiment, the electrode layer 3 and the dielectric layer 2 have the same shape and are centrally located relative to each other, so that the side edge region or free region is configured in the shape of a ring extending along the entire outer edge of the dielectric layer 2.

[0130] According to the findings of the inventors of the present invention, it is preferable that the edge region has a width B that is at least equal to the thickness D of the dielectric layer, ie, greater than or equal to the thickness D.

[0131] Here, the width is measured in a direction parallel to the extension direction of the dielectric layer 2. For example, in a point-symmetric shape such as a circle, the width B is preferably measured in a direction passing through the center of the circle. In the case of a rectangle or square, the width B is preferably measured in a direction perpendicular to the outer side of the rectangle or square.

[0132] B is preferably greater than 50 μm, more preferably greater than 100 μm, and is preferably smaller than 1.5 mm, and may for example be smaller than 1 mm.

[0133] The larger B, the stronger the stabilizing effect of the reinforcing or carrier elements in contact with the edge region, but if B is too large, the effective surface defined by the area of ​​the electrodes may become too small, which may adversely affect the total capacitance of the device.

[0134] On the first surface 21 of the dielectric layer 2 a carrier element 4 is further provided.

[0135] The carrier element 4 preferably comprises a ceramic material similar to or the same as the ceramic material of the dielectric layer 2. However, the material of the carrier element is not limited, and the carrier element may be made of, for example, any ceramic material suitable for fixed bonding by sintering with the ceramic material of the dielectric layer 2.

[0136] The carrier element needs to be in direct physical contact with at least a portion of the free area 23 in order to effectively connect with the ceramic of the dielectric layer 2. As shown in this example, the carrier element 4 is preferably configured to completely cover the free area 23.

[0137] Furthermore, the carrier element 4 is further constructed on a part of the electrode layer 3. By polymerizing with the electrode layer 3, the surface covered by the carrier element 4 becomes larger, and the carrier element can be mounted more efficiently.

[0138] The carrier element 4 also has a cavity 5. The cavity 5 penetrates the entire carrier element in a direction perpendicular to the extension direction of the dielectric layer 2, i.e., in the thickness direction. The electrode layer 3 is exposed at the bottom of this cavity 5. In this way, electrical contact with the electrode layer 3 can be made from the outside via the cavity 5, or contact with the electrode layer 3 can be made during application.

[0139] That is, the carrier element 4 preferably has the same or similar shape as the dielectric layer 2 .

[0140] The carrier element 4 preferably has a thickness at least equal to the thickness D of the dielectric layer 2. However, it is preferred that the thickness of the carrier element is much greater. The thickness of the carrier element may be, for example, 100 μm to 1000 μm. The thickness of the carrier element may preferably be 200 μm to 700 μm. The thickness of the carrier element may be, for example, 400 μm to 600 μm, for example about 500±30 μm. [Example]

[0141] 2 is a schematic cross-sectional view of a second embodiment of a ceramic electrode according to the invention. The second embodiment of the ceramic electrode corresponds substantially to the embodiment shown in FIG. 1a. However, it differs from the ceramic electrode shown in FIG. 1a in that the second embodiment of the ceramic electrode comprises a contact element 6. In this embodiment, this contact element 6 is constructed as a via located in the carrier element 4. The via fills a cavity 5 in the carrier element 4.

[0142] The vias are preferably made from a conductive metal consisting of palladium, as this metal is particularly suitable for the manufacturing process described below. For example, the vias may be manufactured from a metal paste containing palladium.

[0143] The vias are in contact with the electrode layer 3. Furthermore, by terminating the vias at least with the surface of the carrier element, a ceramic electrode can be inserted from the top of the via during application and, for example, soldered to this top.

[0144] In such a solder connection step, for example, the ceramic of the carrier element 4 may be protected by a solder resist. [Example]

[0145] 3 is a diagram showing a third embodiment of the ceramic electrode of the present invention, which also roughly corresponds to the embodiment shown in FIG.

[0146] Here, besides the elements of the first embodiment, a contact element 6 is further constructed. This contact element is constructed as a contact layer and covers the walls of the cavity 5 and part of the surface of the carrier element 4. Here, the electrical contact to the electrode layer 3 is also realized by this contact layer.

[0147] The contact layer or contact element 6 can be produced by various methods, as described below. The contact layer shown here preferably consists of or contains one or more conductive materials. These conductive materials are preferably selected from chromium, nickel, tin and palladium. For example, a thin layer consisting of chromium and / or nickel can be in direct contact with the carrier element 4, to which a nickel or nickel / tin layer is added.

[0148] The horizontal portions of the contact members 6 shown may also be used as solder connection surfaces. [Example]

[0149] FIG. 4 shows a fourth embodiment, which is a modification of the third embodiment.

[0150] In the fourth embodiment, the contact member 6 is constructed as a continuous layer, thus covering any part of the electrode layer 3 that may be exposed.

[0151] This technical solution has the advantage that the process for manufacturing the contact layer is easy to carry out, the contact element 6 can protect the material of the electrode layer from the outside, and a more stable electrical contact can be achieved due to a higher level, planar connection. [Example]

[0152] FIG. 5 is a schematic cross-sectional view of a fifth embodiment of a ceramic electrode according to the present invention.

[0153] In principle, the ceramic electrodes shown in FIG. 5 correspond approximately to those described above.

[0154] The ceramic electrodes shown in FIG. 5 differ mainly in the following attributes:

[0155] 5, the carrier element 4 is constructed only in the free area 23 or in the lateral edge area of ​​the first surface 21 of the dielectric layer 2. Here, compared to the previous example, the cavity 5 formed by the carrier element 4 is wider, in this case equal to the width or diameter of the electrode layer 3.

[0156] Here, the electrode layer 3 and the contact member 6 are integrally constructed as the same layer. The electrode layer 3 preferably covers the entire bottom of the opening 5 or the entire area of ​​the first surface 21 of the dielectric layer 2 that is not covered by the carrier element 4.

[0157] Here, the contact elements 6 are shown in the areas located at the openings or side walls of the carrier element 4 and in the areas provided on the carrier element 4. The contact elements 6 are constructed as the same layer as the electrode layer 3.

[0158] This single large cavity configuration offers several advantages, such as a small size or volume of the carrier element 4 and a frame that extends approximately along the outer edge of the dielectric layer 2 .

[0159] As will be described later, there is also the advantage in terms of processing that the electrode layer 3 and the contact member 6 can be manufactured in the same step, ie, as the same single layer or multiple layers.

[0160] Fig. 6 is a diagram mainly showing steps a to f of the manufacturing process for the ceramic electrode shown in Fig. 4. The manufacturing process can also be adjusted appropriately and applied to the manufacture of the embodiments of Figs.

[0161] In Fig. 6a, a first green sheet 2' is shown. For example, the green sheet is provided on a carrier film (not shown). The first green sheet 2' has a first surface 21' and a second surface 22'. As an alternative technical solution, two first green sheets or a plurality of first green sheets may be used instead of the first green sheet 2'. Here, in order to solve the shrinkage caused by sintering, it is only important that the thickness of the plurality of first green sheets or the thickness of the single first green sheet is 150 µm or less.

[0162] In a particularly preferred variant, a single or two first green sheets are used.

[0163] As shown in Figure 6b, a metal layer 3' is provided on the first surface 21' of the first green sheet 2'. The metal layer 3' is preferably manufactured by printing a metal paste, preferably containing palladium or other refractory metal.

[0164] 6c, in the next step, a green sheet laminate 4' is provided that includes or is composed of a plurality of second green sheets 41'. The green sheet laminate 4' preferably has a cavity 5, which is preferably filled with a polymer paste 51, for example, containing polypropylene carbonate.

[0165] Except for the recess that forms the cavity 5, the second green sheet 41' generally corresponds to, for example, the first green sheet 2'.

[0166] As an alternative technical solution, the second green sheet 41' is made of a ceramic material, which is particularly suitable for bonding with the ceramic material of the first green sheet 2'.

[0167] There is contact between the green sheet stack 4' and the first surface 21' of the first green sheet 2', especially in the free area 23' of the first surface 21' of the first green sheet 2'.

[0168] In subsequent processes, this contact provides a firm and stable bond between the first green sheet and the green sheet stack.

[0169] In the next step (d in FIG. 6), organic components are removed from the green sheet laminate or green sheets by degreasing the laminate, where the polymer paste is largely or completely removed.

[0170] Thereafter, the degreased blank is sintered as shown in Fig. 6e. In this manner, the first green sheet 2' or a plurality of first green sheets 2' constitute the dielectric layer 2. The metal layer 3' constitutes the electrode layer 3. The sintering green sheet laminate 4' constitutes the carrier element 4. In this manner, for example, the ceramic electrode 1 shown in Fig. 1 can be obtained.

[0171] In another step shown in FIG. 6f, a contact member 6 may be added to the ceramic electrode fabricated in FIG. 6e.

[0172] The contact layer or contact element 6 can be realized by screen printing and subsequent firing of a metal-containing paste, where the firing temperature may be, for example, 680-760°C. As an alternative technique, a sputtering process may be used. The contact layer or contact element 6 may also be manufactured by an electroplating process. For example, a seed layer may first be applied by sputtering, and then the contact layer may be grown by an electrochemical or electroplating process. As an alternative technique, electroless plating may also be used. [Example]

[0173] Other processes are shown in Figure 7 or Figures 7a to 7f. The ceramic electrode of the present invention shown in Figure 5 may be manufactured by a modified method. In addition, the ceramic electrode of the sixth embodiment (Figure 7f) described below may be formed by the process in Figure 7.

[0174] In the first step, a green sheet laminate 4' is provided for producing a ceramic electrode (the green sheet laminate is not shown).

[0175] The green sheet laminate 4' has a size of, for example, 4×4 mm 2 ~8×8mm 2 , e.g. 6.5 x 6.5 mm 2 The green sheet laminate 4' may be a square. The first green sheet 41' includes or is made up of the second green sheet 41'.

[0176] The process may be multiple, i.e., multiple ceramic electrodes may be produced simultaneously, where each green sheet laminate is separated or singulated in one of the following steps:

[0177] Figure 7a and 7b show the next steps.

[0178] The green sheet laminate 4' is structured by the structuring method to form cavities 5 in the second green sheet laminate 4', which extend vertically through the green sheet laminate 4' in the thickness direction. The cavities 5 are preferably configured in a regular pattern located on the green sheet laminate 4'.

[0179] FIG. 7a is a plan view of a structured green sheet laminate 4', and FIG. 7b is a schematic cross-sectional view of this green sheet laminate taken along the cutting line AB in FIG. 7a.

[0180] The cavity 5 may be filled with a polymer paste 51 to enhance stability during the process.

[0181] Structuring is preferably carried out by punching and laser processes, which structuring methods are particularly suitable for producing regular patterns.

[0182] By means of a punching or laser process, several green sheet stacks 4' can be structured simultaneously, which is particularly suitable for producing several ceramic electrodes of the same shape and quality.

[0183] In another process step, shown in Figure 7c, one or more first green sheets 2' are attached to the green sheet stack 4'. In this example, only a single green sheet 2' is shown. In this way, a blank is constructed.

[0184] The structured green sheet laminate 4' has the above-mentioned cavities 5. Here, the ceramic material from the green sheet laminate may be considered as a temporary carrier element, since, as described below, the carrier element 4 will be constructed from these remaining structures of the green sheet laminate 4' by sintering.

[0185] As shown in the schematic cross-sectional view of Figure 7d, in a next step, the previously produced blank may be degreased to remove mainly the polymer material 51. Therefore, after degreasing, the cavity is preferably opened so that the first surface 21' of the first green sheet 2' is exposed in the cavity.

[0186] The sintering step (e in FIG. 7) forms the first green sheet 2' or a plurality of first green sheets 2' into a dielectric layer 2. The sintering forms the green sheet stack 4' or the carrier element 4 from the temporary carrier element.

[0187] Here, the structuring of the carrier element 4 is similar to that of the structured green sheet laminate shown in Fig. 7a, i.e. the carrier element 4 forms a grid and constitutes the walls separating the cavities 5 from each other.

[0188] The cavity formed is 0.06 mm 2 ~5mm 2 , preferably 0.25 mm 2 ~2. 25mm 2, and more preferably 0.55 mm 2 ~1.5mm 2 , e.g. 1 mm 2 may have a cross-sectional area of

[0189] In any case, the width of the carrier element or part separating the cavities 5 is greater than the thickness D of the dielectric layer, for example 0.2 mm to 1.5 mm, preferably 0.5 mm to 1.25 mm, and may for example be 0.75 mm.

[0190] The thickness of the carrier element located between the outermost cavity 5 and the edge of the dielectric layer may also be within the above range. However, it is preferred that the carrier element is slightly thicker, for example, 25-50% thicker. Towards the edge, the thickness of the carrier element may be, for example, 1 mm.

[0191] Preferably, but not exclusively, the structuring forms a surround, which improves stability by avoiding exposure of the dielectric layer at edges or corners.

[0192] The portions of the carrier element 4 located between the cavities reduce the unsupported area of ​​the dielectric layer 2, thus further improving the mechanical stability.

[0193] In another final step f, a metal layer 3' or an electrode layer 3 can be simultaneously constructed together with a contact element 6 as a contact layer. These layers are constructed in a manner similar to that described in Figure 5. Here, sputtering, firing of pastes and / or electroplating processes can be used in particular.

[0194] In this way, multiple cavities can be constructed in the ceramic electrode 1.

[0195] In this embodiment, the number of cavities is 9. However, any pattern may be similarly produced, including a single cavity similar to the structure shown in Figure 5, or multiple cavities, for example 2, 3, 8, 9, 12 or 16 cavities.

[0196] FIG. 8a is a graph showing the capacitance versus temperature relationship for the two ceramic electrodes of the present invention shown in FIG.

[0197] The two ceramic electrodes are similarly provided with a dielectric layer having a thickness of about 80 μm. The effective electrode area or electrode layer area is about 20 mm 2 is.

[0198] As shown in the graph in FIG. 8a, ignoring slight variations due to laboratory methods, a capacitance higher than 20 nF, even close to 30 nF, can be achieved in the relative temperature range, i.e., 30°C to 40°C.

[0199] 8(b) shows the correlation between the loss factor tan δ and temperature for these ceramic electrodes. In the correlation temperature range of 30 to 40°C, both cases achieved a loss factor far lower than 0.04.

[0200] This design therefore does not affect the loss factor and therefore allows for the production of high quality electrodes.

[0201] FIG. 9a is a graph showing the capacitance as a function of temperature of two ceramic electrodes of the present invention manufactured according to the embodiment shown in FIG. 7f.

[0202] Here, the dielectric has a thickness of 0.072 mm, i.e., 72 μm, and is produced by first green sheets each having a thickness of 40 μm. The total area of ​​the dielectric layer covered by the electrode layer 3 is about 9×13 mm 2 The remaining part of the surface is covered by the carrier element. That is, the occupied area, that is, the coverage rate by the electrode layer is 36%.

[0203] As shown in the graph in FIG. 9a, both of the two samples can achieve a capacitance close to 30 nF in the relative temperature range of 30 to 40°C.

[0204] In other words, an efficient ceramic electrode can be constructed by the electrode arrangement including multiple cavities shown in Fig. 7f. 2 It is possible to manufacture high capacity electrodes with an electrode area of Therefore, the electrodes are much smaller than those conventionally used.

[0205] For the example of Figure 9b, Figure 9b shows the temperature correlation of loss factor tan δ, where in the correlation temperature range of 30-40°C, the loss factor is also about 0.02 or lower. [Explanation of symbols]

[0206] 1 ceramic electrode 2. Dielectric Layer 2' 1st Green Sheet 3 electrode layer 3' metal layer 4 Carrier element 4' Green sheet laminate 5 Cavity 6 Contact member 21 first surface of dielectric layer 21' First surface of the first green sheet 22 second surface of the dielectric layer 22' Second surface of the first green sheet 23 Dielectric free region 23' Free area of ​​No. 1 Green Sheet 41' 2nd Green Sheet 51 Polymer Paste D thickness of the dielectric layer B. Width of the free area

Claims

1. A method for manufacturing a laminated ... B. building a metal layer (3') on the first surface (21') of said at least one first green sheet (2'); C. Forming a blank by adding a green sheet stack (4') including a second green sheet (41') to the first surface (21'); D. degreasing the blank; E. Sintering the blank to form a dielectric layer (2) having a thickness (D) of 150 μm or less from the one or more first green sheets (2′); A method for producing a ceramic electrode (1), comprising:

2. Maintaining a metal layer (3') absent in a free region (23') of the first surface (21'), and constructing the metal layer (3') on the first surface (21'); 2. The method for manufacturing a ceramic electrode (1) according to claim 1, wherein the green sheet laminate (4') is added so as to contact the free region (23'), the free region (23') being a side edge region of the dielectric layer (2).

3. The green sheet laminate (4') has a cavity (5), and before adding the green sheet laminate (4'), a metal material is filled into the cavity, The metal material and the metal layer (3') are in contact with each other. A method for manufacturing a ceramic electrode (1) according to claim 1 or 2.

4. A method for manufacturing a ceramic electrode (1) as described in claim 1 or 2, wherein the green sheet laminate (4') has a cavity (5) and, after sintering, constructs a contact layer in the cavity that contacts the metal layer (3').

5. A method for manufacturing a ceramic electrode (1) as described in claim 4, wherein a polymer paste (51) is filled into the cavity (5) before adding the green sheet laminate (4'), and the polymer paste is removed by degreasing and / or sintering.

6. A step of providing a green sheet laminate (4') including a second green sheet (41'); Structuring the green sheet stack (4') in the context of the construction of the B cavity (5) and the temporary carrier element; C. forming a blank by adding at least one first green sheet (2') to the structured green sheet stack (4') and bringing a first surface (21') of the first green sheet (2') into contact with the structured green sheet stack (4'); D. degreasing the blank; E. Sintering the blank to form a dielectric layer (2) having a thickness (D) of 150 μm or less from the one or more first green sheets (2′); F. building a metal layer (3') on the first surface (21') of the first green sheet (2') in the cavity (5); A method for producing a ceramic electrode (1), comprising:

7. A method for manufacturing a ceramic electrode (1) as described in claim 6, wherein after the structuring, a polymer paste (51) is filled into the cavity (5), and the polymer paste is removed by degreasing and / or sintering.

8. A method for manufacturing a ceramic electrode (1) as described in claim 6 or 7, wherein the structuring is performed by a punching process or a laser process.

9. A method for manufacturing a ceramic electrode (1) described in any one of claims 1 to 8, wherein the width of the free region (23') is greater than or equal to the thickness (D) of the dielectric layer (2).

10. A method for manufacturing a ceramic electrode (1) described in any one of claims 1 to 9, wherein the metal layer (3') is constructed by sputtering, an electroplating process or screen printing.

11. A method for manufacturing a ceramic electrode (1) described in any one of claims 1 to 10, wherein the thickness (D) is 20 μm≦D≦100 μm.

12. The dielectric layer (2) 12. A method for producing a ceramic electrode (1) according to any one of claims 1 to 11, comprising using a ceramic material with a dielectric constant of 25,000 or more.

13. A method for manufacturing a ceramic electrode (1) described in any one of claims 1 to 12, wherein the dielectric layer (2) has a ceramic material with a dielectric constant of 40,000 or more.

14. A method for producing a ceramic electrode (1) described in claim 12 or 13, wherein the ceramic material is selected from (1-y)[Pb a (Mg b Nb c )O 3-e ] + y[Pb a Ti d O 3 ] and Ba m (Ti n Zr p )O 3 having a dopant including manganese and a rare earth element.

15. A carrier element (4) as a mechanically stabilizing member having one or more cavities (5), A dielectric layer (2) having a thickness (D) of 100 μm or less; an electrode layer (3) formed on the dielectric layer (2) only within the cavity (5); and The electrode layer (3) is in direct contact with the material filling the cavity (5), a ceramic electrode (1).

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