WO2015158549A1

WO2015158549A1 - Glass ceramic capacitor with plastic encapsulation

Info

Publication number: WO2015158549A1
Application number: PCT/EP2015/057120
Authority: WO
Inventors: Jörn BESINGER; Martin Letz; Nikolaus Schultz
Original assignee: Schott Ag
Priority date: 2014-04-17
Filing date: 2015-03-31
Publication date: 2015-10-22
Also published as: DE102014105493B3

Abstract

The invention relates to a capacitor (1), particularly suitable for high-voltage applications, comprising at least one glass ceramic moulding (2) as a dielectric and two metal electrodes (3a, b), the metal electrodes being applied as metallic coatings on the opposing surfaces of the glass ceramic moulding. The glass ceramic (2) with metal electrodes (3a, b) has a plastic covering (4) which surrounds the glass ceramic (2) coated with the metal electrodes (3a, b), and in particular the uncoated lateral faces (2c) of the glass ceramic (2) are in full surface contact with the plastic. The invention also relates to a method for producing such a capacitor.

Description

The invention generally relates to capacitors with a glass ceramic as a dielectric. In particular, the invention relates to a capacitor with a glass ceramic as a dielectric and a Kunststoff erkapselung and a method for its preparation.

Field of the invention

From the prior art capacitors are known, which have a ceramic as a dielectric. In this case, for example, a plate or disk-shaped

formed ceramic on the top and bottom provided with a metallic coating, which serves as electrodes. To avoid flashovers between the two electrodes, the thus coated ceramic or the capacitor is embedded in an electrically insulating material such that the electrically insulating material forms an encapsulation of the capacitor.

For example, they are from the prior art

Capacitors are known which are embedded in oil. Another possibility is to coat the capacitor with an electrically insulating plastic.

Capacitors with such plastic encapsulation, i. Plastic covering can be unlike

Capacitors embedded in oil, built more compact and thus lighter than electronic components in

various circuits are used.

The distance between the electrodes and thus the thickness of the dielectric depends on the dielectric strength of the respective dielectric. The required

Minimum thickness of a ceramic dielectric leads in particular when using the capacitors in

High voltage range that ceramic capacitors are relatively thick and the electrodes are accordingly widely spaced.

At the same time, however, there is a need for compact electronic components as possible. This can be achieved, for example, by using a dielectric with a higher

Dielectric strength are possible. Thus, the required minimum thickness of the dielectric and thus the size of the capacitor can be significantly reduced. As with the reduction of the thickness of the dielectric also the

Distance between the two electrodes decreases, the

Encapsulation have a correspondingly higher creep resistance than in a conventional, ceramic

Capacitor. Object of the invention

It is therefore an object of the invention to provide a capacitor which, in addition to a dielectric with high breakdown capability encapsulation with high

Has creep resistance and thus a comparison with the prior art more compact design of the capacitor is made possible. In particular, a corresponding Capacitor also suitable for use in high voltage range. Another object of the invention is to provide a method of making a corresponding capacitor.

The object of the invention is already achieved by the subject matter of the independent claims. advantageous

Embodiments and developments are the subject of the dependent claims.

Brief description of the invention

The invention relates to a capacitor with a

Glass ceramic shaped body as a dielectric. The glass ceramic is preferably plate-shaped or disc-shaped, i. The thickness of the glass ceramic is small in relation to the length and width or to the radius. On the top and bottom or the opposite surfaces of the glass ceramic is in each case a metal electrode in the form of a metal-containing coating. It is preferably a silver-containing coating. Alternatively or additionally, the metal-containing coating may contain other metals such as copper or aluminum. The electrodes also have a supply or supply line for an electronic contact. The side surfaces of the glass ceramic have no metal coating.

The glass ceramic shows a much higher

Dielectric strength, so that dielectrics with small thicknesses, for example, can be relatively thin glass ceramic discs or plates. The glass ceramic used is preferably a barium titanate or a barium titanate-containing glass ceramic, for example a glass ceramic with barium strontium titanate phases and / or barium aluminum titanate phases. In another

Embodiment of the invention is in the

Glass ceramic around a strontium titanate-containing glass ceramic. The use of a barium zirconate or

Barium aluminum zirconate glass ceramic is possible.

The metallized glass-ceramic, i. Glass ceramic and

Electrodes, is made of a Kunststoffmantel

enclosed. The Kunststoffmantel coating is applied in the form of a coating and encapsulates the dielectric and electrodes,

The capacitor according to the invention is particularly suitable for use in the high voltage range. Corresponding embodiments preferably have a thickness of

Dielectric, i. the glass-ceramic in the range of 0.1 mm to 20 mm, particularly preferably in the range of 0.15 to 10 mm.

These small thicknesses are only due to the high

Dielectric strength of the glass ceramic allows. The small thickness and thus the small distance between the two metal electrodes to each other, however, that the creepage path is reduced. In addition, the surface of the glass-ceramic is smoother than, for example, the surface of a conventional ceramic, which is also the creep path

shortened.

Accordingly, the jacket of the

inventive capacitor with respect to their Creep resistance higher requirements than a conventional capacitor, ie a capacitor with a ceramic dielectric. In particular, this is a good wetting of

Glass ceramic surface by the plastic of the jacket crucial. Therefore, in particular, the side surfaces of the glass ceramic and the Kunstustuffummantelung one

full-surface composite, wherein the KunstStuffummantelung preferably adheres to the glass ceramic or an intermediate layer on the glass ceramic. Furthermore, it has been found to be particularly advantageous if the sheathing the glass ceramic and the applied thereon

Metal electrodes tightly and conclusively wrapped so that between the sheathing and the above

Capacitor components as possible no gas or

Moisture inclusions, which can shorten the creepage path, are present. Be particularly advantageous in the case of the sheath of the capacitor components, the use of a plastic or a corresponding precursor has been found in which by curing the

Polymer and / or by crosslinking

Polymerization shrinkage occurs. While in most applications, such a polymerization shrinkage is just to be avoided, in one embodiment of the invention, the components of the sheath are chosen so that a polymerization shrinkage occurs. Preferably, the polymerization shrinkage is in the range of 0.6 to 10%. Due to the polymerization shrinkage, the sheath contracts, which creates a bond between the sheath and

Glass ceramic favors. The tracking resistance can be influenced on the one hand by the thickness of the insulating sheath. Preferably, the sheath has a thickness in the range of 1 to 15 mm, preferably in the range of 3 to 10 mm.

Depending on the area of application of the capacitor, different requirements arise for the plastic,

for example, in terms of temperature stability. For example, in particular capacitors with a jacket of silicone resin are suitable for

High temperature applications.

The choice of the plastic used in the sheath contributes significantly to the dielectric strength. This can be achieved, for example, by a low dielectric

Loss factor tan δ and / or high

Dielektrizitätskontante £ _{r of} the plastic used can be achieved. In a variant of the invention, therefore, a plastic with a tanö at 50 Hz and a

Temperature of 23 ° C in the range of 0.3 to 30, preferably 0.3 to 10, particularly preferably from 0.3 to 5 used. Alternatively or additionally, the plastic in a further variant of the invention a

Dielectric constant η _r (at 23 ° C) of at least 3, preferably of at least 4 and more preferably of at least 10 on. In one embodiment of the invention, £ _{r is} in the range of 4 to 7.

In one embodiment of the invention, the plastic is crosslinked. By networking, for example, the mechanical strength of the plastic and thus the

Sheath be increased. In addition, increased by the Networking also the density of the plastic, which can have an advantageous effect on the dielectric strength. In addition to thermosets but also thermoplastic

Plastics are used.

To be particularly advantageous, the use of a synthetic material coating with an epoxy resin, a

Polyurethane or a silicone resin as polymeric

Component exposed.

In a preferred embodiment of the invention, the plastic is also crosslinked via siloxane units. Here, in particular, an organofunctional ionic silane is used for crosslinking the plastic, which may be part of the coating preparation. As special

unsaturated silanes,

especially vinyl and methacryloxysilanes exposed. These can, for example, by

Copolymerization reactions, endcapping or

Propfreakt ions on or in the polymer chains of

Plastic be installed. In the presence of water, a hydrolysis of the alkoxy groups of the silane to silanol groups, which iosreakt by condensation ions form a Siloxannet zwerk. Thus, the use of unsaturated silanes in addition to a crosslinking of the

Plastic additionally has the advantage that through the

Hydrolysis reaction of the silane also the residual content of water in the sheath is reduced, which has an advantageous effect on the tracking resistance of the sheath. Thus, the silanes act not only as crosslinkers, but also as water scavengers. In a preferred embodiment of the invention, corresponding CC silanes are used for crosslinking used. These have particularly high hydrolysis and condensation rates.

Furthermore, the use of organofunctional silanes leads to improved wettability of the

Glass ceramic. So can a connection of the silane to the

Surface of the glass ceramic as well as the metal electrodes to form siloxane units. For silanes with hydrophobic radicals, for example in the form of a

Alkyl chain or a polymer, this leads to a

Hydrophobization of the surface and thus to a

better adhesion of the plastic covering to the

Glass ceramic. The silane thus also functions as

Adhesion promoter.

In one embodiment of the invention, a silane is selected from the group of elements

Methyltrimethoxysilane, methyltriethoxysilane,

Dimethyldimethoxysilane, dimethyldiethoxysilane,

Trimethylethoxysilane, isooctyltrimethoxysilane,

Isooctyltriethoxysilane, hexadecyltrimethoxysilane,

(Cyclohexyl) methyldimethoxysilane,

Dicyclopentyldimethoxysilane, phenyltriethoxysilane,

Triacetoxyethylsilane, 1, 2-bis (triethoxysilyl) ethane and / or a mixture of corresponding silanes used.

Alternatively or additionally, the organic radical of the silane may contain one or more reactive organofunctional moieties

Having groups that allows a covalent attachment to the polymer. Here reacts the reactive

organofunktioneile group of silane with a

functional group of the polymer or prepolymer. In particular, the organofunctional group is an amino, an epoxy, a methacrylic, a vinyl, an isocyanato and / or a mercapto group. The silane is thus covalently bonded both to the surface of the glass ceramic and to the plastic of the sheath.

According to this embodiment, as at least one silane, a silane is selected from the group comprising the elements N- (2-aminoethyl) -3-amino-propyltrimethoxysilane, N- (2-)

Aminoethyl) -3-aminopropyltrimethoxysilane, N-cyclohexyl-3-amino-propyltrimethoxysilane, N-cycloaminomethyltriethoxysilane, 3-aminopropyltriethoxysilane, 3- (2-aminomethylamino) propyltriethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3 -

Aminopropyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, vinyltrimethoxysilane, vinyldimethoxymethylsilane,

Vinyltriethoxysilane, vinyltriacetoxysilane, 3-methacryloxypropyltrimethoxysilane, (methacryloxymethyl) methyldimethoxysilane, methacryloxymethyltrimethoxysilane, 3-methacryloxypropyltriacetoxysilane, N-methyl-3- (trimethoxysilyl) propyl] carbamate, N-dimethoxy- (methyl) silylmethyl-O-methylcarbamate, Tris [3- (trimethoxysilyl) propyl] isocyanurate, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane and / or mixtures thereof.

The organofunctional silane can be the

Coating preparation can be added. Alternatively or additionally, the surface of the glass ceramic and / or the metal electrodes can be treated with an organofunctional silane, so that a corresponding Coating on the surface of the glass ceramic forms. As a result of the reaction of the silane with hydroxyl groups of the glass ceramic, the coating is covalently bonded to the glass ceramic via Si-O bonds. The glass ceramic or the partially metallized glass ceramic can be completely provided with the coating or the coating can be carried out only on portions of the glass ceramic. It has been found to be particularly advantageous if at least the side surfaces of the

Glass ceramic can be treated with the organofunktionilen silane. The glass ceramic thus treated can subsequently be encased with the plastic, the siloxane coating formed by the silane acting as a primer layer. Thus, the capacitor in this

Embodiment of the invention at least partial areas, which have a bonding agent layer between the glass ceramic or the metal electrodes and the KunstStuffummantelung. The primer layer has a

Hydrophobization of the treated surface result. Depending on the silane used, the adhesion-promoting effect of the adhesion promoter layer can be based primarily on van der Waals interactions between the hydrophobic radical of the silane used and the polymer of the

Based on plastic covering. If a silane is used, the reactive organofunktionellen groups compatible with functional groups of the generation of

KunstStockummantelung used polymer or

Prepolymers is, as well as a covalent bond between the adhesive layer and the

Kunststoffmantel done, resulting in a particularly strong bond of the capacitor components. The connection of the adhesive layer to the surface of the glass ceramic can be improved in this case if at least partial areas of the glass ceramic having a Si0 ₂ ^~ containing layer. Through the Si0 ₂ ^~ containing layer, the number of available for the condensation reaction with the silane hydroxy groups is still increased.

In a further development of the invention contains the

Sheath additionally inorganic fillers.

In particular, the sheath is a

A composite having a polymeric matrix and inorganic fillers embedded therein, wherein the polymeric matrix is formed by the plastic. By the inorganic

Fillers can be increased on the one hand, the mechanical strength of the sheath. Furthermore, the use of inorganic fillers can lead to the

The breakdown capability of the cladding increases. This can be done in particular by the use of fillers based on A1 ₂ 0 ₃ . Alternatively or additionally, the sheath can also Si0 ₂ particles as fillers

contain. If, in addition, as already described above, an organofunctional silane as crosslinker and / or

Adhesion promoters used, so can in oxidic

Fillers also carried out a covalent attachment of the silane to the surface of the filler. Thus, a surface modification of the filler can take place up to a covalent attachment of the filler to the polymer via the silane. This can for example lead to an increased mechanical and / or chemical resistance of the

Lead sheathing. The fillers may have particle sizes in the range of 1 to 100 pm. In another embodiment of the invention, the sheath contains fillers

Particle sizes in the nm range, in particular in the range of 5 to 200 nm.

Furthermore, the invention relates to a method for

Production of the capacitor according to the invention. The

In this case, the method comprises at least the following

Method steps a) to c): a) providing a glass ceramic shaped body, in particular a plate-shaped or disc-shaped glass ceramic, b) applying a metal coating on the top and bottom or the opposite surfaces of the glass ceramic c) sheathing the coated in step b) glass ceramic a KunstStoffbeschichtung by applying a

Coating preparation, wherein at least portions of the glass ceramic a full-surface composite with the

Make up plastic coating. In step b), a metal-containing paste, preferably a silver-containing paste, on the top and bottom of the

Applied glass ceramic. This can be done for example by a printing process or by doctoring. The paste contains metal particles in addition to a Anpastmedium,

in particular an oil, and optionally glass powder. Through the glass powder, the adhesion of the metallic

Improved coating on the glass ceramic surface become. Particularly advantageous here is the use of a glass powder from the green glass of

Glass ceramic exposed. Alternatively or additionally, the metal paste may contain particles of other metals, for example copper or aluminum particles.

Before applying the metal paste, the glass ceramic can be completely or partially cleaned or etched. By etching, the surface is additionally roughened, resulting in improved adhesion of the

Metal coating on the surface leads.

Alternatively or additionally, in a the

Process step a) upstream step, a S1O ₂ - containing layer are deposited on the glass ceramic.

This can be done for example by sputtering, a CVD method or a sol-gel method. This can, especially in conjunction with an organofunktionilen silane, the adhesion of the KunstStoffSchicht on the

Glass ceramic can be improved.

In step c), the cladding of the metallized in step b) glass ceramic takes place. In one variant, the metallized glass ceramic is coated with a thermoplastic material. Here, the coating can be applied by a dipping process. For this purpose, the corresponding plastic is melted to a temperature above the glass transition temperature and the metallized

Glass ceramic dipped in the molten plastic. By cooling, the plastic solidifies and forms such a

Plastic covering. Alternatively, the glass-ceramic can also be coated by means of a fluidized bed process. In a further variant of the invention, the

Sheathing a thermosetting plastic. For this purpose, a coating preparation with a prepolymer and a crosslinker is applied. In particular, the coating composition is a two-component casting resin. The casting resin may contain further additives,

for example, to accelerate the crosslinking reaction. The encapsulation may in particular be applied by a vacuum casting method or an automatic pressure gelling method.

Curing of the resin takes place by polymerization and / or crosslinking. The coating composition can be cured at room temperature. Another embodiment provides that the coating composition is hot curing.

In addition, the coating composition may have inorganic fillers, for example Si0 ₂ or A1 ₂ 0 ₃ . The filler content is preferably in the range of 50 to 75 wt .-%, particularly preferably in the range of 55 to 68 wt .-% based on the total weight of the coating composition. In a variant of the invention, the

Coating preparation an epoxy casting resin system. In this variant, the coating preparation comprises as prepolymer an epoxy resin and a hardener, preferably an anhydride or amine. In particular, the prepolymer has an epoxide number (according to ISO 3001) in the range of 2 to 3 Eq / kg, preferably in the range of 2.2 to 2.35 Eq / kg. In one embodiment, the

Coating preparation an epoxy resin based on bisphenol A. This may be a solvent-free epoxy resin, but depending on the desired viscosity of the coating formulation, a reactive diluent may also be used as the solvent. The curing agent contained in the coating composition is an anhydride-based curing agent in this embodiment. A further embodiment provides that the

Coating preparation as a prepolymer

cycloaliphatic epoxy resin and / or an epoxy resin with increased impact strength.

For example, the use of the following two-component epoxy resin casting systems from Huntsman, comprising a prepolymer and a curing agent, that is to say crosslinking agents and optionally inorganic fillers, has proved to be advantageous.

Prepolymer Vernet zer

CW 5730 N HY 5731

CW 1446 BDF HY 2919

CW 2250 HY 2919

CW 1116-1 XW 1257-1

CW 1116-1 HY 2919

CW 1491 BD HW 1491 BD

CW 2122-1 HY 2123

CW 2122-1 HY 2901-1

XB 5763 HY 5726

CW 5725 HY 5726

CW 5742 HY 5726

CW 1195-1 HW 1196 CW 229-3 HW 229-1

These coating formulations are thermosetting epoxy casting systems, i. the crosslinking takes place in these systems at elevated temperatures. It is also possible to use those epoxy resin casting systems which cure at room temperature, for example the following systems from Huntsman:

Prepolymer Vernet zer

CW 1312 HY 1300

CW 1302 HY 1300

CW 2243-2L HY 1872

CW 2243-2L HY 842

CW 2245 HY 2966

CW 2245 HY 956 EN

CW 2248 HY 956 EN

CW 2249 HY 2851

XB 2252 XB 2253

CW 2250-1 HY 2251

CW 5730 N HY 2966

DBF HY 2966

DBF HY 842

DBF HY 956

DBF HY 951

CY 220-1 HY 956

CY 221 HY 842

CY 221 HY 2967

CY 221 HY 2966

CY 221 HY 956

CY 223 HY 956

F HY 956 MY 740 HY 840-1

MY 740 HY 956

Furthermore, the coating preparation can be further

Additives such as e.g. Additives to increase the elasticity of the epoxy resin (Flex) or to accelerate the crosslinking (accelerator) included. Examples of such

Coating formulations are the following systems from Huntsman:

Prepolymer Vernet zer Flex accelerator filler

Araldite ^® HY 905 DY 040 DY 061 Si0 ₂

CY 5980 HY 5980 DY 040 DY 061 Si0 ₂

CY 5936 HY 5945 Si0 ₂

CY 5948 HY 5945 Si0 ₂

CW 229-3 HW 229-1

CY 5995 HY 5996 Si0 ₂

CY 5995 HY 925 Si0 ₂

CY 5995 HY 227 Si0 ₂

CY 228-1 HY 918 DY 062 Si0 ₂

CY 228-1 HY 918 DY 045 DY 062 Si0 ₂

CY 225 HY 925 Si0 ₂

CY 225 HY 225 Si0 ₂

CY 225 HY 227 Si0 ₂

CT 5900 HT 901 Si0 ₂

CT 5900 HT 903-1 Si0 ₂

CT 5900 HT 923 Si0 ₂

XB 5900 XB 5951

XB 5915 XB 5916

CY 184 HT 907 DY 071 Si0 ₂

CY 184 HY 1235 DY 062 Si0 ₂

CY 184 HY 1235 DY 062 Si0 ₂ CY 184 HY 1235 DY 044 DY 062 S10 ₂

CY 5622 HY 1235 DY 062 S10 ₂

XB 5918-3 XB 5919-3 DY 062

XB 5957 XB 5958

In another variant of the invention contains the

Coating spread as a prepolymer, a polyurethane or a polyurethane precursor and a curing agent. In this case, for example, the following 2-component polyurethane casting resins from Huntsman can be used:

A development of the invention provides that the

Coating mass additionally at least one

contains organofunctional ionic silane, which ions can be covalently bound by hydrolysis and / or Kondensationsreakt to the surface of the glass ceramic and / or the metal electrodes. In addition, the organofunctional silane silane can act as a crosslinker. The organofunctional silane can contain hydrophobic groups. Alternatively or additionally, the organic radical of the silane may be one or more reactive

have organofunktioneile groups that allows a covalent attachment to the polymer. It is also possible to use a mixture of different silanes.

The organofunctional silane or the mixture

various organofunctional silanes may alternatively or additionally in a process step c)

upstream step are applied to the surface of the glass ceramic. Here, the order can be completed or it can be only part of the

Glass ceramic to be coated with the organofunktionilen silane. Preferably, the organofunctional silane is at least on the side surfaces of the glass ceramic

applied. The organofunctional silane forms an adhesion promoter layer. In an advantageous embodiment of the invention, a covalent bonding of the two layers takes place in step c) at the interface between the silane layer and the synthetic material layer. This reacts the

organofunktioneile group of the silane with the polymer or prepolymer of the coating preparation. The covalent attachment preferably takes place by copolymerization, endcapping or free-radical addition.

In a covalent attachment by endcapping the organofunktioneile group of the silane reacts with a

functional end group of the polymer or prepolymer of the coating preparation. To be particularly advantageous the following combinations of end group and organofunctional silane were found: aminosilanes and NCO-terminated polyurethanes, aminosilanes and

Acrylic polymers, aminosilanes and methacrylic polymers,

Isocycanatosilanes and OH-terminated polymers such as polyethers, polyesters, polyurethanes, amino, epoxy and / or glycidoxysilanes, and epoxy precursors as prepolymers, and aminosilanes and phenolic precursors as prepolymers.

Unsaturated silanes and polymer or prepolymer can also be covalently linked together by a radical grafting reaction. In particular, the following combinations have been found to be advantageous: vinylsilanes and polyolefins, methacryloxysilanes and polyolefins, and also methocryloxysilanes and unsaturated polyesters.

The capacitors according to the invention or the capacitors produced by the method according to the invention can be used for example in high voltage engineering.

Detailed description of the invention

The invention will be described in more detail below with reference to FIGS. 1 to 3 as well as to exemplary embodiments. Figs. 1 to 3 show schematic representations of the cross sections of different embodiments of the converter according to the invention. 1 shows an embodiment of the capacitor 1. The disk-shaped glass ceramic 2 serves as a dielectric.

Here, the top 2a and the bottom 2b of the glass ceramic 2 with the metal electrodes 3a and 3b

coated. The electrodes 3a and 3b are with the

Derivatives 5a and 5b connected. Glass ceramic 2 and

Electrodes (3a, 3b) have a plastic covering 4. In the embodiment 1 shown here, the side surfaces 2c have a full-surface bond with the

Plastic covering 4 on. The KunstStoffSchicht 4 may contain a crosslinker based on a silane, so that glass ceramic 2 and / or metal electrodes 3a, 3b and

Kunststoffmantel 4 can be covalently connected to each other.

The embodiment 6 shown in FIG. 2 additionally has an adhesion promoter layer 7 between the synthetic material sheath 4 and the glass ceramic 2 or the electrodes (3a, 3b). Preferably, the adhesion promoter layer 7 is attached to the

Interfaces to the glass ceramic 2 and / or to the electrodes 3a, 3b covalently connected via Si-O bonds with these. The adhesion promoter layer 7 contains hydrophobic organic radicals and may be bonded to the plastic layer 4 by van der Waals interactions and / or via covalent bonds. Alternatively to that shown in FIG

Embodiment can also only parts of the

Glass ceramic 2 and / or the electrodes 3a, 3b with the

Adhesive layer 7 are provided. Preferably, at least the side surfaces 2 c of the glass ceramic are coated with the adhesion promoter layer 7. FIG. 3 shows a further embodiment 8 of the capacitor, in which the glass ceramic 2 additionally has a layer 9 containing SiC> 2. The SiC> 2-containing layer 9 improves in particular the wetting of the

Glass ceramic surfaces. In the embodiment 8 shown, an adhesion promoter layer 7 is additionally present.

In the embodiment 1 is a glass ceramic as a

Bariumtitantathaltige glass ceramic used. The top and bottom of the glass ceramic are provided with a silver-containing coating, which each acts as an electrode. The silver-containing coating contains silver and glass particles. The coated glass ceramic is covered with an artificial material layer based on an epoxy resin. The epoxy resin is reinforced with inorganic fillers.

For the production of the Kunsthochstoff coating will be

Two-component epoxy casting resin system with an epoxy resin based on bisphenol A as a prepolymer and a

Anhydride hardener (Araldit ^® - Giessharzsystem the company Huntsman with the components Araldit ^® CW 229-3 and Aradur ^® HW 229-1) used.

Resin and hardener components are homogenized for this purpose in the required amount at slightly elevated temperature up to 60 ° C under vacuum. The sheathing is done with a conventional vacuum casting or with a

automatic pressure gelation method (ADG method).

In the second embodiment is

also a capacitor with a barium titanate glass ceramic as a dielectric and silver-containing Coatings as electrodes. For the production of the Kunstustuffummantelung a two-component Epoxydgiessharzsystem the company Huntsman with the components Araldit ^® CW 1446 BDF and Aradur ^® HY 2919 is used.

Claims

claims

1. capacitor, in particular suitable for

High voltage applications, comprising at least

a glass ceramic shaped body as a dielectric,

two metal electrodes, wherein the metal electrodes in the form of a metal-containing coating on the

opposite surfaces of the glass ceramic shaped body are applied and

- a plastic sheath, the

Enclosure surrounds the coated with the metal electrodes glass-ceramic, in particular the

uncoated side surfaces of the glass ceramic have a full-surface composite with the plastic.

2. A capacitor according to claim 1, wherein the

Glaskeramikformkörper plate or disc-shaped

is formed and the metal electrodes are applied to the top and bottom.

3. capacitor one of the preceding claims, wherein the glass-ceramic bariumtitanathaltige phases, preferably

Barium titanate, barium strontium titanate and / or

Bariumaluminiumtitanatphasen, strontiumtitantathaltige phases and / or bariumzirkonathige phases contains.

4. A capacitor according to one of the preceding claims, wherein the glass ceramic has a thickness in the range of 0.1 to 20, preferably in the range of 0.15 to 10 mm.

5. A capacitor according to one of the preceding claims, wherein the sheath has a thickness in the range of 1 to 15 mm, preferably in the range of 3 to 10 mm.

6. Capacitor one of the preceding claims, wherein the plastic comprises a polyurethane, an epoxy resin and / or a silicone resin.

7. A capacitor according to any one of the preceding claims, wherein the plastic is crosslinked via siloxane units.

8. A capacitor according to any one of the preceding claims, wherein the plastic has a tan δ at 50 Hz and 23 ° C in the range of 0.3 to 10, preferably 0.3 to 5 and / or a £ _r at 23 ° C in the range of at least 3, preferably at least 10 has.

9. A capacitor according to any one of the preceding claims, wherein the sheath inorganic fillers, preferably Si0 ₂ and / or A1 ₂ 0 ₃ contains.

10. A capacitor according to one of the preceding claims, wherein the glass ceramic has at least in some areas a Si0 ₂ - containing layer.

11. A capacitor according to one of the preceding claims, wherein at least portions of the capacitor between the

Glass ceramic and the plastic, a primer layer, preferably a primer layer comprising a

organofunctionalized silane, more preferably a silane having hydrophobic groups.

12. A capacitor according to claim 11, wherein the glass-ceramic and the adhesion promoter layer are joined together at the interface via covalent bonds, preferably via Si-O bonds.

13. A capacitor according to claim 11 or 12, wherein plastic and adhesive layer are covalently bonded together at the interface.

14. A method for producing a capacitor according to claim 1 with at least the following steps: a) providing a glass ceramic shaped body as

Dielectric, b) applying a metal coating to at least

Partial areas of the opposite surfaces of the

Glass ceramic shaped body, c) sheathing the coated in step b)

Glass ceramic molding with a KunstStoffbeschichtung by applying a coating preparation, wherein at least portions of the glass ceramic molding form a full-surface composite with the KunstStoffbeschichtung.

15. The method according to claim 14, wherein in step b) the metal coating in the form of a paste comprising

Metal particles, glass powder and a Anpastmedium is applied.

16. The method according to claim 14 or 15, wherein the

Surface of the provided in step a) glass ceramic is at least partially cleaned and / or etched.

17. The method according to any one of claims 14 to 16, wherein at least on subregions of the surface of the glass ceramic provided in step a) a Si0 ₂ ~ containing layer is deposited.

18. The method according to any one of claims 14 to 17, wherein in step c) a coating composition comprising an epoxy resin and / or a Epoxydharzvorstufe is provided as a prepolymer and a crosslinking agent, preferably an anhydride.

19. The method according to any one of claims 14 to 18, wherein in a step c) upstream process step on at least partial areas of the glass ceramic surface, a bonding agent layer, preferably by applying a silane with hydrophobic and / or functional groups, is deposited.

20. The method according to any one of claims 14 to 19, wherein in step c) at the interface between

Adhesive layer and KunstStoffbeschichtung a covalent attachment of adhesion promoter layer and

KunstStoffSchicht, in particular by reaction of

organofunctional groups of silane with functional groups of the synthetic material layer takes place.

21. The method according to any one of the preceding claims 14 to 20, wherein the provided in step c) Coating Preparation Crosslinked, preferred

contains organofunctionalized silanes.

22. The method according to any one of claims 14 to 21, wherein the provided in step c) provided inorganic fillers.