EP2684197A1

EP2684197A1 - Coil bodies having a ceramic core

Info

Publication number: EP2684197A1
Application number: EP12709310.2A
Authority: EP
Inventors: Alexander Dohn; Roland Leneis; Alfred Thimm
Original assignee: Ceramtec GmbH
Current assignee: Ceramtec GmbH
Priority date: 2011-03-11
Filing date: 2012-03-12
Publication date: 2014-01-15
Also published as: RU2013145430A; US20130342302A1; WO2012123413A1; BR112013023327A2; JP2014510690A; KR20140017592A; DE102012004676A1; JP5980240B2; CN103703522A

Abstract

The present invention relates to coil bodies (chokes, frequency filters) having a ceramic core.

Description

Spool with ceramic core

The present invention relates to bobbins (throttles, frequency filters) with a ceramic core.

Miniaturized bobbins (chokes, frequency filters) with a ceramic core of ferromagnetic or diamagnetic material such as Al 2 O 3 are well known and widely used in high frequency engineering. The cores are usually made by dry pressing and have a horseshoe-shaped construction with angular or rounded edges, are metallized at the ends and carry windings of e.g. Copper tape or copper wire. Known sizes are 1206, 0805, 0402. They are also available in bone form.

Bobbins with a ceramic core made of ferromagnetic or diamagnetic material such as Al2O3 can dissipate the resulting heat at high frequency only bad. AI2O3 has a thermal conductivity (WLF) of 28 W / mK.

Object of the present invention is therefore to provide bobbins with a ceramic core, which do not have the disadvantages of the prior art.

The object is achieved by the characterizing features of the first claim. Advantageous embodiments of the invention are characterized in the subclaims.

Surprisingly, it has been found that bobbin with a ceramic core of highly heat-conductive electrically insulating material such as diamagnetic AIN, preferably AIN-4% Y ₂ 0 ₃ , at high frequency, the resulting heat can better dissipate. As a result, the electrical resistances can be kept small and the Q value high. The AIN materials used according to the invention achieve a WLF of more than 170 W / mK. Of the Basic body can be produced by dry pressing from appropriate granules. This granules contains in a suitable organics such as waxes and binders a spray granules of AIN with a proportion of usually preferably 2-6% sintering aids such as Y2O3 or other rare earth compounds, possibly also with CaO, MgO. (Range can generally range from about 0.5% to about 10%).

The pressed into the desired shape basic body is sintered at AIN usual temperatures, in AIN-Y2O3 preferably under nitrogen atmosphere at 1700 ° C. Then a strong metallization is brought to the ceramic.

The metallization serves to fix the coil wire and to mount solder on the circuit board, e.g. a) with tungsten (glass) reducing-wet baked at about 1250 ° C + electroless nickel solderable,

b) with molybdenum-manganese + electroless nickel, such as a wet-baked at about 1250 ° C. under N ₂ ,

c) with solderable silver,

d) with silver-palladium or silver-palladium-platinum or silver-platinum or platinum, but also

e) be carried out with copper.

In addition to the metal powder, variants a to d usually also require glasses which are especially suitable for AIN, ie react only slowly or not at all with AIN to form nitrogen. They are mostly made on the basis of ZnO. This metallization is oxidized at 850 ° C.

Dipping, screen-printing or spraying ("InkJet" -like procedure) are used as metallization processes Suitable processes for metallization are described, for example, in DE 198 28 574 B4. In order to be able to produce the contact surfaces in the moldings according to the invention for solder joints, the shaped bodies according to the invention are metallized on the surface areas provided for this purpose, the contact surfaces. When the shaped body has subsequently been processed according to its intended use, it is soldered with its contact surfaces on a circuit or terminals are soldered to the contact surfaces.

The metallization of the contact surfaces is carried out in a known manner by applying a metallizing paste on the components to the designated surface areas and a subsequent heat treatment. The metallizing paste is applied by rollers, screen printing or pad printing. These application methods are known, for example, from "Mo-Mn Metallization on AIN Substrate", Ceramic Transactions, 15/1990, pages 365-374, for example in the case of U-shaped ceramic bobbins with particularly small dimensions of the wound body of about 6 mm in length, 4 mm Width and 3 mm in height, the legs have a length of about 0.6 mm with a width of about 1, 2 mm.The surface to be metallized on the front sides of the U-legs is thus about 3.6 mm ^2. By the known In the printing process, the surfaces of the legs adjoining the end surface are wetted only to a very small extent with the soldering paste, and problems with adhesion can occur with solder joints on predetermined contact surfaces of such small dimensions.

The most important parameters of a solder joint are the compositions of the ceramic material, the metallization paste and the solder as well as the required adhesive strength, which is essentially influenced by the size of the contact surface. In the known application method of the metallizing paste, a plurality of moldings are aligned so that the surfaces to be printed are all aligned in the same direction. These faces of the moldings are then printed with the metallizing paste. The adjoining surfaces on the printed face are swelled by the over the edge Metallizing paste usually wets to an extent of about 0.06 mm. By contrast, the metallization process described here, by immersing the shaped bodies in the metallization paste, in addition to the metallization of the respective end faces, furthermore enables a metallization of the adjoining surfaces, in particular of limb surfaces, to any extent.

Particularly in the case of components with legs pointing away from the molded body whose end faces are to be metallized for the production of contact surfaces, the depth of the legs may be up to 90% of the leg length. Preferred is an area with a depth up to 60% of the leg length. The depth is chosen in particular depending on the size of the molded body and thus in dependence on the leg length. The smaller the limb length, the greater the depth of immersion can be in relation to the limb length, thereby obtaining the largest possible metallized area. With a leg length of, for example, 0.6 mm, the metallized leg length would be 0.36 mm at a depth of 60% of the leg length.

By increasing the metallized area, the adhesion of the metallization and thereby also of a solder joint can be correspondingly increased. Increasing the metallized area by at least 50% can achieve more than twice the adhesive strength. Another advantage over the known method for applying the metallizing paste is the simpler and faster process of the process and thereby its greater efficiency.

The moldings are all held in the same orientation for the dipping process by means of a device that the surface areas to be metallized facing down and the end faces on which the connections are to be made, are all arranged at the same height. According to this method, there are two ways to keep the metallizing paste ready for dipping. The metallizing paste can be kept ready in a tub. This requires that with increasing removal of the metallizing paste by the dipping operations each dipping process tuned to the sinking level of the metallizing paste or the filling of the metallizing paste in the tub is set to a constant level.

Alternatively, the metallizing paste may be applied to a flat, horizontally disposed surface in a predetermined layer thickness. For this purpose, the metallizing paste can be spread on the surface by means of a doctor blade so that the required immersion depth is available for the dipping process. The moldings are then immersed with their surfaces to be metallized in the metallizing paste. Dipping may take place until it is placed on the surface carrying the metallizing paste. As a result, an always uniform metallization is achieved. However, the viscosity of the metallizing paste must be adjusted so that after lifting the contact surfaces are wetted with the metallizing paste in the required layer thickness. After each dipping process, the surface is coated anew with the metallizing paste in the specified layer thickness. For this purpose, the metallizing paste of the previous dipping process can be completely removed beforehand from the surface. In this method, unlike the previous dipping method, no fluctuating level of the metallizing paste in a pan has to be considered.

The viscosity and thus the spreading of the metallizing paste exerts a significant influence on the result of the metallization. Therefore, it is advantageous if, during the dipping of the surface areas of the shaped bodies to be metallized, the surface of the metallization paste does not bulge as a result of the displacement, for example due to the dipping limbs of bobbins. This avoids that the metallizing paste wets a region that must not be metallized, for example, the area of the bobbin, the Wrapping wears. If, for example, terpineol is used for pasting, a dwelling of the paste surface occurs when a molding is immersed because of its slow course. As advantageous, a high viscosity of about 160000 to 250,000 mPa-s has been found. Such a viscosity, for example, has a metallizing paste containing metal powder and glass frit in a solution of (2-butoxyethyl) acetate. Due to its good flow properties, (2-butoxyethyl) acetate achieves a very high degree of filling of over 85% solids in the metallizing paste. Metals such as tungsten, molybdenum or silver-palladium alloys are particularly suitable for metallization.

The residence time of the surface areas of the shaped bodies to be metallized in the metallizing paste can be advantageously matched to the depth of immersion, the viscosity and the dipping speed and is about 0.2 to 2 seconds.

In order to avoid droplet formation of the metallization paste on the contact surfaces, in particular on the end faces on which the connection is made later, in a further advantageous embodiment, the excess metallization paste can be drained off on a surface provided for this purpose, for example a drip plate. For this purpose, the moldings are briefly placed with their covered with the metallizing paste faces on a flat surface. When lifting off from this surface, the excess metallizing paste remains, so that no drops form.

This flat surface can also be structured as a drip tray. The structuring may for example consist of spaced, narrow parallel grooves or grooves, which may also form a grid in which the excess metallizing paste flows. The grooves or grooves may be inclined to one side of the drip plate so that the excess metallizing paste can flow off the structure automatically. If the drip tray is higher than the dip tray with the metallization paste, the grooves or grooves of the structure may be inclined so that the excess metallization paste flows back into the tray. The flat surface may also be a mesh or wire mesh disposed over a surface. When placing the end faces of the moldings on the sieve, the excess metallizing paste drips through the sieve onto this surface. If this surface is tilted to the immersion tray with the metallizing paste, here also the excess metallizing paste automatically flows back into the tub.

As a residence time on the surface for draining the excess metallizing paste, a time of 0.2 to 2 seconds has been found to be advantageous, depending on the degree of metallization and the viscosity of the metallizing paste.

In order to be able to carry out a continuous metallization of the shaped bodies, it is advantageous if the area on which the excess metallization paste is drained off is subsequently cleaned immediately. For example, the excess metallizing paste may be stripped off with a squeegee or the surface replaced with another prepared surface that has been cleaned. While the surplus metallization paste of a previously performed dipping process is drained on this surface, the previously used surface can be cleaned.

The dipping process and the subsequent dispensing of the excess metallizing paste can advantageously be accelerated by the fact that between the application of the metallizing paste and dispensing the excess metallizing the device with the held moldings and the trough or surface with the metallizing paste as well as the surface for receiving the excess Metallisierungspaste relative be moved to each other. In this case, the trough with the metallizing paste or the surface with the aufgerakelten metallizing paste and the surface for dispensing the excess Metallisierungspaste are arranged side by side. Either the device is silent with the moldings to be metallized and the tub or surface with the Metallization paste and the surface for discharging the excess metallization paste are moved under the device or the tray or surface with the metallization paste and the surface for discharging the excess metallization remain stationary and the device with the held moldings is between metallization paste and the surface of the Returning the excess metallizing paste moved back and forth.

The method can also be used as follows for bobbins or resistors. Perched vertically in the holes of a belt can first be metallized one and after the tightening of the belt, the second end face by dipping into the metallizing paste. The belt with the moldings is stretched horizontally in a suitable holding device on the means for handling the moldings.

The sequence of the metallization process will be explained in more detail with reference to the following exemplary embodiments.

Show it

FIG. 1 shows a device for metallizing surface areas of ceramic shaped bodies of small dimensions, in which the device for handling the shaped bodies in the initial position is above a movable table with a tray filled with metallizing paste,

Figure 2 shows the moldings during the dipping into the metallizing paste

3 shows the moldings, placed on a drip tray, for removing superfluous metallizing paste, FIG. 4 shows the metallized moldings which are kept ready for removal by the device for their handling and the cleaning of the drip plate,

Figure 5 shows another device in which a movable device for

In its initial position the handling of the shaped bodies is above a surface on which a layer of metallizing paste has been applied,

6 shows a table with a structured surface as a drip tray and

Figure 7 shows a table with a sieve as drip tray.

1 shows a schematic representation of a device for metallizing surface areas of ceramic shaped bodies of small dimensions. The ceramic shaped bodies 2 are temporarily fixed on a holding plate 4 for accommodation on a device 3 for handling ceramic shaped bodies 2. In the present embodiment, the ceramic moldings are U-shaped bobbins. These bobbins are first aligned by means of a vibrating plate and then taken up by a heated flat plate, for example made of ceramic or metal, which is covered with a thermoplastic, temporarily effective adhesive. By pressing with a counter plate, the bobbins have been fixed on the support plate 4. They have been aligned so that the surface areas to be metallized, the end faces 5 on which the terminals are to be soldered, are arranged at the same height. The holding plate 4 with the temporarily glued bobbins 2 has then been taken up by the stamp plate 6 of the device 3. The holder takes place in the present embodiment by means of negative pressure via arranged in the surface of the die plate suction nozzles 7, which are shown in dashed lines, above the holding plate 4 are distributed. A connection 8 leads to a Vacuum source, not shown here, in which, symbolized by the arrow 9, the required for fixing the support plate 4 negative pressure is generated.

The stamp plate 6 hangs on a telescopic cylinder 10. The structural features required for the function of the device 3 for handling the molded bodies 2 are known from the prior art and for this reason are not shown and explained in detail here.

In FIG. 1, the device 3 for handling the molded bodies 2 is in its initial position above a table 11. This table 1 1 carries on the left side of a trough 12 which is filled with metallizing paste 13. On the right side next to it is a horizontally arranged, flat surface 14, which serves as a drip plate for removing superfluous metallizing paste on the moldings 2.

The table 1 1 has in the present embodiment rollers 15, with which it is mounted on guide rails 16, of which only the front can be seen here. On these guide rails 16, the table 1 1 below the means 3 for handling the molded body 2 by means of a drive, not shown here, to which the connecting rod 17 leads, back and forth, as indicated by the double arrow 18. The table 1 1 can be moved from the position shown, in which the trough 12 with the metallizing paste 13 below the means 3 for handling the moldings 2, in a position as shown in Figure 3. Then there is the drip plate 14 below the means 3 for handling the molded body 2. Furthermore, a squeegee 19 is shown, with the drip plate 14 is cleaned of the excess metallizing paste, which is drained from the metallized surfaces of the molded body 2.

FIG. 2 shows the method step in which the molded bodies 2, in the present embodiment bobbin, with their surface areas to be metallized are immersed in the trough 12 with the metallizing paste 13 are. For this purpose, the stamp plate 6 has been lowered from its initial position shown in FIG. 1 by means of the telescopic cylinder 10 in the direction of the arrow 20 (FIG. 1). The immersion depth of the bobbin can be controlled via the telescopic cylinder 10 so that not only the end faces 5, but also the adjoining surfaces of the U-legs 21 of the bobbin 2 are wetted to a predetermined depth of the metallizing paste 2. Due to the high viscosity of the metallizing paste of about 160000 to 250,000 mPa-s, there is no bulging of the surface of the metallizing paste. This avoids that the Bewicklungsraum between the legs 21 is wetted by the metallizing paste 13 and ensures that the actual wetting of the surfaces coincides with the predetermined depth. The depth can be up to 90% of the leg length, but is preferably selected in the range up to 60%, depending on the size of the moldings and the length of the legs.

If the molded bodies 2 are lifted out of the metallizing paste 13 again after the predetermined dwell time by means of the device 3, as indicated by the arrow 22, drops of the metallizing paste can form on the end faces 5 of the molded bodies 2. Such drops would result in uneven application of the metallizing paste. For this reason, it is provided according to the method that the excess metallizing paste is removed from the surfaces to be metallized. This is done by the drip plate 14, which adjoins the trough 12 with the metallizing paste 13.

Are the hanging on the die plate 6 shaped body 2, as indicated by the arrow 22, lifted from the trough 12, the table 1 1 is moved so far in the direction of arrow 23 until the drip plate 14 is below the die plate 6. Then, the stamp plate 6 is lowered so far with the metallized moldings 2 by means of the telescopic cylinder 10 in the direction of arrow 24 until the end faces, here the end faces 5 of the legs 21 of the bobbin 2, the surface of the drip plate 14 touch or almost touch, as shown in FIG 3 shown. When an end face 5 touches the surface of the drip plate 14, It must be ensured that the metallizing paste is not completely pushed away from it. How far the end face 5 may approach the surface of the drip plate 14 depends on the viscosity of the metallizing paste 13 and the desired layer thickness of the metallization on the end face 5. The degree of dripping can also be controlled by the residence time, which can be between 0.2 and 2 seconds.

FIG. 4 shows the method step in which the molded bodies 2 are lifted off the drip plate 14. The U-shaped legs 21 of the bobbin 2 are covered not only on the end face 5, but also in a depth corresponding to the depth of 25 with metallizing paste 13. The bobbins thus metallized can be supplied to the subsequent heat treatment of the metallizing paste, if they have been detached from the holding plate 4.

In Figure 4 is further shown how the table 1 1 is retracted to its initial position shown in Figure 1, as indicated by the arrow 26. While the table 1 1 is retracted on the guide rails 16 to its original position, the excess metallization paste 13 'drained by the bobbins 2 is scraped off the drip plate 14 by means of a squeegee 19 and pushed back into the sump 12. As a result, the surface of the drip plate 14 is cleaned and is prepared for placing a new batch of metallized moldings.

FIG. 5 shows a further exemplary embodiment of a method for metallizing surface areas of ceramic molded bodies. Of the device 1 for metallization, the device 3 for handling the molded body 2 to be metallized is identical to the preceding embodiment. The moldings 2 to be metallized are, as in the previous embodiment, U-shaped bobbins. The metallization method differs from that of the preceding embodiment in that the table 1 1 1 is fixedly arranged, while the means 3 for handling the bobbin 2 between a region 1 12, on which the metallizing paste 13 is applied, and an area , which forms the drip tray, is movable back and forth, as indicated by the double arrow 27. In contrast to the previous embodiment, the metallization paste 13 in the region 1 12, the metallization, in a predetermined layer thickness 28 on the table 1 1 1 applied. The application takes place in that by means of a feed device 29 from a reservoir, not shown here, the metallizing paste 13 is placed on the table 1 1 1 in the range 1 12, as indicated by the arrow 30. The thickness of the layer 28 to be applied is adjusted by means of a doctor blade 31. For this purpose, the distance of the doctor blade 31 from the table 1 1 1 is adjustable, as indicated by the double arrow 32.

From its dashed line position 33, the feeder 29 and the doctor blade 31 are moved in the direction of arrow 34 to the position shown 35. In this case, the metallization paste 13 is applied in the predetermined layer thickness 28 to the region 1 12 of the table 1 1 1.

After the application of the metallization paste 13, the device 3 with the bobbins 2 is lowered until the legs are immersed in the metallization paste 13 with the required immersion depth. The dipping can, as explained above, take place until the end faces on the table 1 1 1. The raising and lowering of the device 3 is indicated by the double arrow 36. After metallization, the bobbin 2 are raised and the device 3 is moved over the drip tray 1 14.

The doctor blade 31 and the feeding device 29 can now be moved back to their starting position 33. For this they are raised so far that they no longer dive into the metallizing paste 13. After the excess Metallisierungspaste 13 'is dropped from the bobbins 2 by placing on the drip tray 1 14, the die plate 6 is raised so far that the holding plate 4 can be removed with the bobbins 2 and the metallized bobbin after detachment from the holding plate 4th the further provided heat treatment can be supplied. The lifting and lowering in the drip tray 1 14 is indicated by the double arrow 36.

To prepare a new dipping process, both the drip tray 1 14 and the area 1 12 must be cleaned from the metallizing paste. For this purpose, a specially provided for the cleaning of the table 1 1 1 doctor blade 1 19 in the direction of arrow 37 is moved to the position 33. At the same time, the no longer required metallizing paste 13 'is sucked off through a tube 38 with a width of the region 1 12 covering the nozzle 39, as indicated by the arrow 40. This suctioned metallization, as not shown here, the feeder 29 are fed back and reused in the reapplication of metallizing paste in the range 1 12 of the table 1 1 1.

Another embodiment in FIG. 6 shows a planar surface 214 on a table 21 1, which is structured and slightly higher than the surface of the metallization paste 13 in the trough 12. The structure consists of spaced, narrow parallel grooves or grooves 41. The grooves or grooves can also run in a grid shape. The grooves or grooves 42 pointing in the direction of the immersion trough 12 with the metallizing paste 13 are inclined such that the excess metallizing paste 13 'can automatically flow back into the trough 12.

FIG. 7 shows an exemplary embodiment with a table 31 1, the draining surface of which consists of a sieve-shaped wire mesh 314. When placing the end faces 5 of the moldings 2 on this draining surface 314 drips the excess Metallisierungspaste 13 'on the underlying surface 44. This can be so inclined be that the excess metallizing paste 13 'automatically flows back into the trough 12.

The bobbin according to the invention are characterized by a better heat dissipation, a lower resistance in the wire, a better Q-value and less heat loss than the known in the prior art coil body of ferromagnetic or diamagnetic material such as Al2O3.

The present invention accordingly relates to:

> Spool body with a ceramic core of highly heat-conductive electrically insulating material. in which

• the ceramic core consists of highly heat-conductive electrically insulating material with a WLF> 28 W / mK;

• contains the ceramic core AIN;

• the ceramic core AIN and up to 10% sintering aid, preferably sintering aids in amounts of 0.5 to 10%, particularly preferably in amounts of 2 to 6%;

The ceramic core AIN and as sintering aid Y2O3, other rare earth compounds, CaO and / or MgO;

• contains the ceramic core AIN-4% Y ₂ 0 ₃ .

The lists marked with * mean optional, preferably embodiments of the bobbin according to the invention.

The present invention further relates to: Method for producing the abovementioned bobbin, in which the base body of the bobbin is produced from a suitable granulate in a suitable organic material by a suitable pressing method, the base body pressed into the desired shape is sintered and an adherent metallization is applied to the ceramic. wherein o granules as a spray granules is used; o the organics contain waxes and binders. o As the pressing method, the dry pressing method is used. o the spray granules contains a proportion of sintering aids. o is used as sintering aid Y2O3, other rare earth compounds, CaO and / or MgO. o the sintering aids in amounts of 0.5 to 10%, preferably in amounts of 2 to 6% is used. o the pressed into the desired shape base body is sintered under inert gas atmosphere. o nitrogen is used as protective gas. o the bobbin is sintered at 1700 ° C. in the metallization of the bobbin a number of bobbins (2) of the same shape by means of a device (3) in the same orientation is held so that the surface areas to be metallized (5, 21) facing down and thereby the end faces (5) of the molded body ( 2), that the end faces (5) of all moldings (2) are arranged at the same height, that the moldings (2) by means of the device (3) in the metallizing paste (13) are so far dipped until the surface areas to be metallized (5, 21) have been completely covered by the metallizing paste (13) and that thereafter the shaped bodies (2) are subjected to a heat treatment adapted to the composition of the metallizing paste (13). the metallization paste (13) is filled in a trough (12). the metallization paste (13) is applied as a layer (28) in a predetermined thickness on a horizontally arranged, planar surface (1 12). for pasting the metallizing paste (13, 13 ') (2-butoxyethyl) acetate is used. the metallizing paste (13) has a viscosity of about 160,000 to 250,000 mPa · s. in the case of shaped bodies (2) with limbs (21) pointing away from the shaped body (2), the depth (25) of the limbs (21) as a function of the size of the shaped bodies (2) and the length of the limbs (21) up to 90%, preferably in a range up to 60%, the length of the legs (21) is selected. the residence time of the surface areas (5, 21) to be metallized of the molded bodies (2) in the metallizing paste (13) is about 0.2 to 2 seconds. after the application of the metallizing paste (13) to the surface regions (5, 21) of the moldings (2), the moldings (2) are lifted out of the metallizing paste (13) so that the moldings (2) briefly cover their metallurgical paste (13) End surfaces (5) on a flat surface (14, 1 14, 214, 314) are placed and that when placed on the surface (14, 1 14, 214, 314), the excess Metallisierungspaste (13 ') is removed. the planar surface (214) is structured and that the excess metallization paste (13 ') flows into the structuring (41, 42). the end faces (5) of the shaped bodies (2) are placed on a sieve (314). the duration of application to the surface (14, 14, 214, 314) for removing excess metallization paste (13 ') is about 0.2 to 2 seconds. after removal of the moldings (2) from the surface (14, 14), the excess metallizing paste (13 ') is removed from the surface (14, 14). the excess metallizing paste (13 ') is scraped off with a doctor blade (19, 19). the excess metallizing paste is washed off. the excess metallizing paste 13 'automatically flows off the surface (214, 314). between the application of the metallization paste (13) and the dispensing of the excess metallization paste (13 '), the device (3) with the held moldings (2) and the trough (12) or the surface (1 12) with the metallizing paste (13) and the surface (14, 1 14, 214, 314) for receiving the excess Metallisierungspaste (13 ') are moved relative to each other ,

The enumerated with o enumerations mean optional, preferably embodiments of the inventive method for producing the bobbin according to the invention.

Claims

claims

1 . Spool body with a ceramic core of highly heat-conductive electrically insulating material.

2. bobbin according to claim 1, characterized in that the ceramic core consists of highly heat-conductive electrically insulating material with a WLF> 28 W / mK.

3. bobbin according to claim 1 or 2, characterized in that the ceramic core contains AIN.

4. bobbin according to one or more of claims 1 to 3, characterized in that the ceramic core AIN and up to 10% sintering aid, preferably sintering aids in amounts of 0.5 to 10%, particularly preferably in amounts of 2 to 6% ,

5. bobbin according to one or more of claims 1 to 4, characterized in that the ceramic core contains AIN and as a sintering aid Y2O3, other rare earth compounds, CaO and / or MgO.

6. bobbin according to one or more of claims 1 to 5, characterized in that the ceramic core contains AIN-4% Y ₂ 0 ₃ .

7. A method for producing the bobbin according to one or more of the preceding claims, characterized in that the base body of the bobbin is made from a suitable granules in a suitable organic by a suitable pressing process, the sintered into the desired shape of the base body and an adherent metallization is brought to the ceramic.

8. The method according to claim 7, characterized in that as granules a spray granules is used.

9. The method according to claim 7 or 8, characterized in that the organics waxes and binders.

10. The method according to one or more of claims 7 to 9, characterized in that the pressing method, the dry pressing method is used.

1 1. Method according to one or more of claims 7 to 10, characterized in that the spray granules contains a proportion of sintering aids.

12. The method according to one or more of claims 7 to 1 1, characterized in that is used as a sintering aid Y2O3, other rare earth compounds, CaO and / or MgO.

13. The method according to one or more of claims 7 to 12, characterized in that the sintering aid is used in amounts of 0.5 to 10%, preferably in amounts of 2 to 6%.

14. The method according to one or more of claims 7 to 13, characterized in that the pressed into the desired shape basic body is sintered under a protective gas atmosphere.

15. The method according to one or more of claims 7 to 14, characterized in that nitrogen is used as protective gas.

16. The method according to one or more of claims 7 to 15, characterized in that the bobbin is sintered at 1700 ° C.

17. The method according to one or more of claims 7 to 16, characterized in that in the metallization of the bobbin a number of bobbin (2) of the same shape by means of a device (3) is held in the same orientation so that the surface areas to be metallized ( 5, 21) pointing downwards and thereby forming the end faces (5) of the shaped bodies (2) that the end faces (5) of all shaped bodies (2) are arranged at the same height that the shaped bodies (2) by means of the device (3) immersed in the metallization paste (13) until the surface areas (5, 21) to be metallized have been completely covered by the metallization paste (13), and thereafter the moldings (2) are matched to the composition of the metallization paste (13) Be subjected to heat treatment.

18. The method according to claim 17, characterized in that the metallization paste (13) is filled in a trough (12).

19. The method according to claim 17 or 18, characterized in that the metallizing paste (13) is applied as a layer (28) in a predetermined thickness on a horizontally arranged, planar surface (1 12).

20. The method according to one or more of claims 17 to 19, characterized in that for pasting the metallizing paste (13, 13 ') (2-butoxyethyl) acetate is used.

21. Method according to one or more of claims 17 to 20, characterized in that the metallizing paste (13) has a viscosity of about 160000 to 250,000 mPa s.

22. The method according to one or more of claims 17 to 21, characterized in that in the case of shaped bodies (2) with legs (21) pointing away from the shaped body (2), the immersion depth (25) of the legs (21) in Depending on the size of the molded body (2) and the length of the legs (21) up to 90%, preferably in a range up to 60%, the length of the legs (21) is selected.

23. The method according to one or more of claims 17 to 22, characterized in that the residence time of the surface areas to be metallized (5, 21) of the shaped body (2) in the metallizing paste (13) is about 0.2 to 2 seconds.

24. The method according to one or more of claims 17 to 23, characterized in that after the application of the metallizing paste (13) on the surface regions (5, 21) of the molded body (2) the molded body (2) lifted from the metallizing paste (13) be that the shaped body (2) briefly with its metallized paste (13) covered end faces (5) on a flat surface (14, 1 14, 214, 314) are placed and that when placed on the surface (14, 1 14, 214, 314) the excess metallizing paste (13 ') is removed.

25. The method according to claim 24, characterized in that the flat surface (214) is structured and that the excess metallization paste (13 ') flows into the structuring (41, 42).

26. The method according to claim 24, characterized in that the end faces (5) of the shaped body (2) are placed on a sieve (314).

27. The method according to one or more of claims claim 24 to 26, characterized in that the duration of the placement on the surface (14, 1 14, 214, 314) for removing excess metallizing paste (13 ') about 0.2 to 2 seconds is.

28. The method according to one or more of claims claim 24 to 27, characterized in that after lifting the molded body (2) of the surface (14, 1 14), the excess metallizing paste (13 ') of the surface (14, 1 14 ) Will get removed.

29. The method according to claim 27, characterized in that the excess metallizing paste (13 ') with a doctor blade (19, 1 19) is scraped off.

30. The method according to claim 27, characterized in that the excess metallizing paste is washed off.

31. A method according to claim 25 or 26, characterized in that the excess Metallisierungspaste 13 'automatically flows from the surface (214, 314).

32. The method according to any one of claims 24 to 31, characterized in that between the application of the metallizing paste (13) and the dispensing of the excess Metallisierungspaste (13 '), the means (3) with the held moldings (2) and the trough (12) or the surface (1 12) with the metallizing paste (13) and the surface (14, 1 14, 214, 314) for receiving the excess Metallisierungspaste (13 ') are moved relative to each other.