DE10053307B4 - Capsule for microsensors, encapsulation of microsensors and capsule element - Google Patents

Abstract

Capsule for microsensors, with
a first capsule element (10), and
a second capsule element (20) connected to the first capsule element (10) to form an interior space between the capsule elements (10, 20),
marked by
at least one metallization (22, 26) serving as a bonding connection for connecting the two capsule elements (10, 20) and at the same time as a contact for an electrically conductive connection from the interior to the outside, wherein the metallization (22, 26) with at least one electrically conductive Contact bushing (13, 14, 15) is electrically conductively connected, which extends through the first capsule element (10) and / or through the second capsule element (20).

Description

The The present invention relates to a capsule for microsensors according to the preamble of claim 1, a method of encapsulating microsensors according to the generic term of claim 11, and a capsule element according to the preamble of claim 17.

Microsensors, such as pressure sensors or acceleration sensors are in many cases housed in a capsule, or encapsulate generally a capsule. Such a capsule has an interior, the completed or from the outside space is separated and in which the sensor or parts thereof housed are. There is the problem of contact implementation at the encapsulation of the sensors or microsensors. Still must guaranteed be that the interior of the capsule even at high working temperatures the sensor is permanently and tightly closed. simultaneously have to safe electrical contacts for contacting the sensor in the interior of the Capsule guaranteed be. In addition, the encapsulated sensors or microsensors economical should be produced.

The EP 0 742 581 A2 describes a method of making sealed cavities on silicon wafer surfaces by anodic bonding. For electrical connection of the cavity or interior with the outer space buried tracks are provided in the silicon substrate.

The publication EP 0 369 352 A1 shows an accelerometer with a first silicon plate, which is located between two other silicon plates. A part of the first silicon plate forms an electrode piece which is movably mounted in a cavity between the two outer plates. The middle plate is used as an electrical conductor.

The publication AT 003 609 U1 describes a microsensor having a microelectromechanical sensor element electrically connected to an integrated circuit. In this case, an electrically conductive capsule element is provided with a bending beam and fixed by means of an electrically conductive solder seam on the integrated circuit. The soldered seam serves as an electrically conductive connection.

The EP 0 943 923 A1 shows a semiconductor acceleration sensor with a central plane with a movable electrode piece, which is arranged in an inner space between two outer plate elements. Between the outer plate elements, a metal layer is formed, which serves as a shield.

So far the encapsulation of microsensors or silicon sensors, by tunneling bonding frames with implantation-doped tracks. The bonding frames usually consist of glass for anodic bonding. The Implantation-doped interconnects have the advantage that they are not exalted or over Protrude component surfaces, which is why it does not negatively affect the bonding process from this point of view influence. In many cases but it is not possible implantation doped tracks provide.

It was trying to solve the problem of elevated contact performance To circumvent this, that additional layers on metallizations, the to carry out the contact serve, be applied. However, this has the disadvantage that the Additional layers consuming by polishing or the like smoothed Need to become. In addition, such processes neither for the processing or production, still for the operation of the sensor are suitable at high temperatures.

Height Temperatures require high temperature resistant materials. Under these Prerequisites, the implantation difficult or excretes technological reasons out.

The Implantation of a feed-through channel or the tunneling with implantation-doped tracks or the covering metallization with tie layers and then smoothing Therefore, significant disadvantages in terms of cost-effective production the encapsulated microsensor and / or in view of its operation especially at high temperatures.

It It is therefore the object of the present invention to provide a capsule for microsensors to create, the easier to produce and suitable for high temperatures is, as well as hermetically tight can be configured. Farther to specify a method for the encapsulation of microsensors be done in a simplified way can be and the production of high temperature, hermetic dense encapsulations of microsensors allows. In addition, a capsule element be created, which is a simplified production of the capsule or encapsulation, and possibly a simplified connection of the capsule to the housing allows.

These Task is solved through the capsule for Microsensors according to claim 1, the method for encapsulation of microsensors according to claim 11 and the capsule element according to claim 17. Further advantageous features, aspects and details of the invention arise from the dependent ones claims, the description and the drawings.

advantages and features associated with the capsule of the invention or the capsule element, also apply to the process according to the invention and vice versa.

According to the present Invention is a capsule for Microsensors are created that include a first and a second capsule element has, wherein the two capsule elements connected to each other are to form an interior space between the capsule elements, and wherein at least one metallization is provided, which as Bond connection for connecting the two capsule elements and at the same time as contact for an electrically conductive connection from the interior to the outside, wherein the metallization with at least one electrically conductive contact bushing electrically is conductively connected through the first capsule element and / or through the second capsule element extends. This makes the capsule easier and therefore cheaper can be produced and z. B. also used at high temperatures. The maximum working temperature of the sensor can z. In the range of 650 ° C and higher. The hermetic sealing of the interior or pressure or gastight contact feedthrough guaranteed.

advantageously, the metallization comprises at least two metals or alloys, which have a different melting point. This can be done at a corresponding process temperature metallization in part be melted, resulting in the production of the capsule a high dimensional stability of the metallization areas. This includes the metallization preferably titanium and copper, in particular copper on titanium can be applied. In the connection process with a working temperature, the higher is the melting point of copper but lower than the melting point of titanium, the metallization remains particularly dimensionally stable. So there is no bleeding the metallization.

Prefers are the first and second capsule elements through the metallization soldered together, wherein the metallization is an electrically conductive contact layer forms. Due to the dual function of metallization, on the one hand for soldering the capsule elements and on the other hand to form an electrical conductive contact layer is used, the bonding of the capsule elements and the contacting of sensor elements in the interior of the capsule take place in a single process step.

By the high temperature during of the soldering step a tempering of the metallization, d. H. behave the contact resistance ohmic after tempering.

The Metallization can be separated metallization areas include. A metallization area or another metallization can close the interior hermetically and / or pressure-tight.

Prefers the capsule comprises at least one electrically conductive contact bushing, the is electrically connected to the metallization and / or made of substantially the same material as the contact layer is. Also, the contact implementation even z. B. form a contact layer in partial areas. Also by it can in one step or step the contacting respectively.

Prefers is the first capsule element and / or the second capsule element disc-shaped or plate-shaped or designed as a chip, wherein at least one contact implementation by the first capsule element and / or by the second capsule element extends. The capsule elements can z. B. be made of silicon carbide or SiC. Also is one Manufacturing in SO technology, Group III nitrides on sapphire, or SOS technology possible. Ie. it can high temperature semiconductor materials can be used. Preferably, a micromechanical production takes place. (SOI = silicon to insulator; SOS = silicon on sapphires).

advantageously, the capsule comprises a sensor, in particular a pressure sensor. This will be a cost effective Sensor or pressure sensor created, which can be used at high temperatures is and has a small footprint. Such encapsulated sensors can z. B. used in aircraft turbines. It is, however possible, to accommodate other types of sensors in the capsule according to the invention, such as B. acceleration sensors or temperature sensors.

at the method according to the invention for the encapsulation of microsensors at least two capsule elements interconnected to form an interior, by means of a metallization in one operation, the interior closed and at the same time an electrically conductive connection from the interior outward is formed, wherein at least a portion of the metallization in Connecting the capsule elements a contact bushing through one of the capsule elements electrically contacted. As a result, the process can be carried out in a simplified manner and it can on low cost Way encapsulated microsensors are produced which have a high Pressure tightness even at high temperatures and a safe electrical conductive connection between the interior and the exterior ensure the capsule.

Advantageously, both capsule elements are ver before joining with the metallization see, wherein the metallization can be designed so that it serves in mutual soldering as a bond between the two capsule elements and at the same time as a contact for an electrical connection between the interior and the exterior. The metallization is z. B. designed so that the interior is hermetically sealed. Thus, a particularly secure and permanent connection of the capsule elements and at the same time a stable contacting of sensor elements is made possible in a simple manner.

at The method is preferably applied a metallization, the consists of at least two metals or alloys containing one may have different melting point, wherein the bonding preferred occurs at a temperature between the two melting points lies. In particular, the metallization includes titanium and copper or corresponding alloys.

advantageously, be in the process in at least one of the capsule elements through holes designed on its inner wall with the metallization be provided, or with another metallization whose melting point z. B. substantially corresponds to the melting point of the metallization or in a same or similar Temperature range can be. But it is z. B. also possible, spring contacts or to provide pressure contacts or z. For example, the holes with conductive metal pastes or conductive Fill glass. This results in a particularly simple way the formation of a Contact bushing and the electrical contact when joining or connecting the capsule elements.

Prefers Before joining, a further metallization or a metallization region the capsule elements or at least one capsule element applied, wherein the metallization is designed to be after the Connect hermetically encloses an interior area. In order to will be done in a cost effective way a reliable pressure or gas-tight interior for created a sensor element.

According to one Another aspect of the invention provides a capsule element, to form a capsule for microsensors by bonding serves with a further capsule element, wherein the capsule element having a metallization configured to be when connecting as a bond and at the same time a contact for one forms electrically conductive contact bushing which extends through the further capsule element extends. It is with the capsule element possible, an encapsulated microsensor with a closed interior economical or in a simple manner, which also works reliably, suitable for high temperatures is and z. B. at temperatures of about 650 ° C and more can. The maximum working temperature depends u. a. from the melting point the metallization.

The Metallization preferably comprises at least two metals or alloys, such as copper and / or titanium or corresponding alloys, which have a different melting point. This will be a very high dimensional stability the metallization areas when connecting the capsule elements allows d. h., a flow the metallization is with appropriate choice of the process temperature prevented. This is z. B. achieved by the one component wetting or wetting agent for the other component is.

Especially is the capsule element for forming a capsule according to the invention designed.

following the invention will be described by way of example with reference to the figures. Show it:

1a a carrier chip as part of a capsule according to a preferred embodiment of the invention;

1b a membrane chip, which together with the carrier chip of 1a forming the capsule according to the preferred embodiment of the invention;

2a a view of the membrane chip of 1b but from the opposite side;

2 B a representation of the other side of the carrier chip of 1a ; and

3 a photograph of a sensor chip according to a preferred embodiment of the invention.

The 1a and 1b show a first capsule element 10 or a second capsule element 20 , which together form a capsule for a microsensor. It shows 1a the outermost side 11 of the capsule element 10 , while 1b the inside of the capsule 21 of the second capsule element 20 shows. For the design of the capsule, the two capsule elements 10 . 20 interconnected (arrow V) and form between them an interior. The first capsule element 10 is designed as a carrier chip, while the second capsule element 20 is designed as a membrane chip or sensor chip. On its inside 21 carries the second capsule element 20 a metallization in the form of four metallization areas 22 after the joining of the two capsule elements 10 . 20 when Serve bond and at the same time form a contact for an electrically conductive connection between the interior and the outer space of the capsule.

The two capsule elements 10 . 20 are made in the preferred embodiment of SiC, which allows a high operating temperature of the sensor in the range of 650 ° C.

It but it is also possible for others high temperature semiconductor materials or semiconductor material systems such as B. Group III Nitrides on Sapphire, Silicon on Insulator (SOI), Silicon on sapphires (SOS) to be used as sensor material.

In addition to the metallization areas 22 is on the capsule element 20 another metallization area 26 applied to the other metallization areas 22 and enclosing structures lying between them like a ring. Between the metallization areas 22 are piezo elements 30 educated. conductor tracks 31 in the form of further metallizations form electrical connections between the piezo elements 30 and the metallization areas 22 , In the preferred embodiment shown here, between each two metallization regions 22 a piezo element 30 connected.

The piezo elements 30 are located on a deformation element or a membrane 27 , which is relatively thin compared to the rest of the chip. The deformation element is part of the second capsule element 20 formed in the center and made of the same material as the capsule elements. The metallization or the metallization areas 22 and 26 have a thickness in the range of about one or more microns. They are designed in their shape so that when joining the two capsule elements 10 . 20 form a bond with those metallization areas that are on the side adjacent thereto 12 of the first capsule element 10 are designed.

The first capsule element 10 ( 1a ) or the carrier chip has a number of through holes 13 on their walls also with a metallization 14 are provided. The carrier chip is electrically insulating or has an electrically passivatable surface. The metallizations 14 extend like a ring through the through holes 13 and form on the outside 11 and the inside 12 of the first capsule element 10 in each case further metallization areas 15 , These further metallization areas 15 each ring around one of the holes 13 and form electrical contacts on each side of a hole 13 , Metallization is not absolutely necessary, other electrically conductive materials are also conceivable (eg spring contacts). If both capsule elements 10 . 20 are connected to each other, which z. B. by soldering, are the metallizations 14 from each of the holes 13 of the first capsule element 10 each with an associated Metallisierungsbereich 22 of the second capsule element 20 merged. These metallization regions thus form a bond connection for connecting the two capsule elements 10 . 20 and at the same time an electrical contact and hermetically sealed contact bushing from the interior of the capsule to the outside.

The metallization or the metallization areas 14 . 15 . 22 . 26 are made of at least two metals or metal alloys, in the present case titanium and copper or corresponding alloys. The metallization or metallization areas are by vapor deposition or sputtering on the respective body of the capsule elements 10 . 20 applied. In this case, there is a layer of copper or a copper alloy on a layer of titanium or a titanium alloy. When soldering at a defined process temperature, which is above the melting point of copper but below the melting point of titanium, liquid copper forms on solid titanium. The liquid copper remains dimensionally stable on the solid titanium, whereby a diffusion process of the titanium can take place. That is, the titanium provides a dimensionally stable connection between the metallization and the base material of the respective capsule element 10 . 20 or between copper and SiC. Thus, no bleeding of the structured metallization takes place during the bonding process. Of course, other materials, such as Ti / Au or Ti / Ag can be used.

In addition to the preceding figures show the 2a and 2 B the other side of the capsule elements 10 . 20 , 2a shows the outside of the assembled capsule side 28 the membrane chip or second capsule element 20 , 2 B shows the inside of the assembled capsule 12 the carrier chip or first capsule element 10 , To form the capsule, the two capsule elements 10 . 20 in the in the 1a and 1b respectively. 2a and 2 B shown position relative to each other (arrow V). The membrane or sensor chip or second capsule element 20 has on its outside 28 a depression 29 for the formation of the membrane described above 27 , That is, the membrane 27 is one compared to the rest of the capsule element 20 thin area forming a wall of the interior of the finished capsule and being flexible. A change in the differential pressure between the interior of the capsule and the outer space causes a deformation of the membrane 27 and thus a signal or a signal change by the piezo elements 30 ,

On the inside of the assembled capsule 12 the carrier chip or first capsule element 10 is also a depression 17 formed so that in the area of the recess 17 after connecting the two capsule elements 10 . 20 a closed interior In the capsule arises. In 2 B are the annular metallization areas 15 shown the through holes 13 surrounded and together with the metallizations 14 in the holes 13 Contact bushings through the first capsule element 10 form. The metallization areas 15 at the through holes 13 are designed so that they join the two capsule elements 10 . 20 each with a metallization area 22 of the second capsule element 20 (S. 1b ) merge or merge with it. The fused metallizations thus form a bond between the two capsule elements 10 . 20 and at the same time an electrical contacting of the sensor elements or piezoelectric elements located in the interior of the capsule 30 ,

Another metallization area 18 also on the inside of the finished capsule 12 the carrier chip or first capsule element 10 is applied completely encloses the annular metallization or metallization regions 15 and in the center of the first capsule element 10 deepening 17 , Here is the further metallization 18 separated from the other metallizations. The further metallization area 18 is structured so that when connecting the capsule elements 10 . 20 with the opposite metallization region 26 of the second capsule element 20 (S. 1b ) merges or a bond is received. In the assembled capsule element is thus by the metallization 18 respectively. 26 the interior pressure sealed to the outside. Likewise close the four ring-shaped metallizations 15 of the first capsule element 10 together with the four metallization areas 22 of the capsule element 20 the interior of the capsule from the outside space. The number of metallization areas 15 . 22 and the number of through holes 13 is not limited to four, but depends on the respective requirements. Each pad is completed by the metallizations individually.

The two capsule elements 10 . 20 , which are designed as a carrier chip and membrane or sensor chip, have at their edges in each case two indentations or recesses 51 . 52 respectively. 61 . 62 which serve for guiding and positioning the chips during assembly, wherein guide means or guide pins cooperate with the recesses. The mounting takes place on the bushing or on the housing.

To produce the encapsulation, first the two capsule elements 10 . 20 provided. In this case, the first capsule element 10 as a sensor chip and the second capsule element 20 as a carrier chip, for example made of SiC. The two chips are designed in shape so that they form an interior when assembled, are housed in the sensor elements.

Now, the metallizations as described above, on the carrier chip and the sensor chip as the first and second capsule element 10 . 20 applied. For this purpose, first titanium and then copper or corresponding alloys are vapor-deposited. Generally, metals or alloys with different melting points are advantageous to the process. The application of the metallization or the metallization areas 14 . 15 . 22 . 26 can also be done by sputtering. After application of the metallization this z. B. structured by lithographic processes. Structuring can also take place by means of a lift-off process or by shadow masks. This will be the metallization areas 14 . 15 . 22 structured so that they after the assembly of the capsule elements 10 . 20 serve as a bond and at the same time form an electrically conductive connection to the interior of the capsule.

For connecting the capsule elements 10 . 20 becomes the metallization 14 . 15 . 22 . 26 heated. As the process temperature for soldering, a temperature is selected which is between two different melting points of the metal components of the metallization. Thus, when using titanium and copper, soldering occurs at a process temperature that is above the melting point of copper and below the melting point of titanium. The process temperature for soldering the two capsule elements 10 . 20 lies in the present case z. B. in the range of about 1100 ° C. Due to this relatively high process temperature, which is determined by the melting temperature of Cu, it is possible to operate or use the encapsulated sensor even at high operating temperatures, without the safety and operability is compromised.

On account of the selected process temperature, liquid copper forms on solid titanium upon heating, whereby the dimensional stability of the structured metallization is ensured. The through holes 13 can have substantially the same metallization as the other metallization areas. In general, however, it is also possible to provide metallizations which have a similar melting behavior or partially melt at a similar process temperature. That is, the metals or different metal components are chosen so that when melting a component due to their compound or their Contact with the second component preserves the dimensional stability. The choice of metals is determined by the processing steps.

The two capsule elements 10 . 20 are joined together, being closed by the metallization in a single operation, the interior of the capsule and at the same time an electrically conductive connection is formed from the interior to the outside. So it is only a brazing of the two capsule elements 10 . 20 Without intermediate layers must be provided, for example, to compensate for different height ratios that result in conventional contact bushings. The metallization layer is thus simultaneously the bonding layer for closing the capsule and for carrying out the contacts, wherein the bonding and the production of the contacts takes place in one working step.

at The manufacturing process can be based on further connecting layers be waived, d. h., only one intermediate material is used. It also results that problems due to thermal stresses are avoided. Overall, the bonding and metallization are of the same material or from a very similar one Material, the same or similar Has melting points and thermal expansion coefficients.

The present invention makes it possible in a simple manner to produce a reliable and cost-effective sensor capsule which has pressure-tight contact bushings and can contain sensors of any type. There are z. B. meandering piezoresistors on the membrane 27 formed, which lie in the pressure-tight closed interior of the finished capsule. By layers that serve both the contacting, as well as the bonding process, the encapsulation and the contact implementation of a microsensor can be done in one step. Such layers can z. B. titanium-copper layer structures, which can be used for soldering at temperatures above the melting point, but remain structurally stable at these temperatures.

In the case of a pressure sensor for absolute pressure measurement is in the interior of the capsule vacuum or a defined pressure, so that an external pressure across the membrane 27 can be measured.

3 shows a black and white shot of the sensor chip or second capsule element 20 according to the in 1b schematically illustrated, preferred embodiment of the invention. The dark, annular regions are free from the metallization, ie at these points the substrate material of the sensor chip can be seen. The bright areas show the structured metallization or the metallization areas 22 and 26 according to 1b , In the center of the capsule element shown here 20 are the meandering piezoresistors or piezo elements 30 passing through the metallization 22 , which simultaneously serves for bonding, to be contacted.

The outermost metallization area (see area 26 from 1b ) is as shutter metallization on both chips or capsule elements 10 . 20 applied.

In summary is achieved by the contact-integrated encapsulation according to the present invention the problem of contact implementation Encapsulation of microsensors solved. For this purpose soldering and contacting layers simultaneously connected together. Compared to known methods is the encapsulation process considerably simplified. First and foremost is through the encapsulation and the method described, the creation of high temperature suitable Microsensors possible. Of the Sensor is preferably an absolute pressure sensor.

10

first capsule element

11

located outside Side of the first capsule element

12

Inside lying side of the first capsule element

13

through holes

14

Metallization (in holes 13 )

15

Further metallization

17

deepening in the first capsule element

18

Another metallization

20

second capsule element

21

Inside lying side of the second capsule element

22

metallization

26

metallization

27

membrane

28

located outside Side of the second capsule element

30

piezo elements

51 52

recesses of the first capsule element

60

plug

61, 62

recesses of the second capsule element

Claims (19)

Capsule for microsensors, with a first capsule element ( 10 ), and a second capsule element ( 20 ) associated with the first capsule element ( 10 ) is connected to an interior space between the capsule elements ( 10 . 20 ), characterized by at least one metallization ( 22 . 26 ), which serve as a bond connection for connecting the two capsule elements ( 10 . 20 ) and at the same time serves as a contact for an electrically conductive connection from the interior to the outside, wherein the metallization ( 22 . 26 ) with at least one electrically conductive contact bushing ( 13 . 14 . 15 ) is electrically conductively connected through the first capsule element ( 10 ) and / or by the second capsule element ( 20 ). Capsule according to claim 1, characterized in that the metallization ( 22 . 26 ) comprises at least two metals or alloys having a different melting point. Capsule according to claim 1 or 2, characterized in that the metallization ( 22 . 26 ) Ti / Cu, Ti / Au and / or Ti / Ag. Capsule according to one of the preceding claims, characterized in that the first and the second capsule element ( 10 . 20 ) through the metallization ( 22 . 26 ) are soldered together, wherein the metallization ( 22 . 26 ) forms an electrically conductive contact layer. Capsule according to one of the preceding claims, characterized in that the metallization ( 22 . 26 ) or a metallization area closes the interior hermetically and / or pressure-tight. Capsule according to one of the preceding claims, characterized in that the metallization ( 22 . 26 ) comprises different, separate metallization regions, wherein one or more metallization regions hermetically and / or pressure-tightly seals the interior. Capsule according to one of the preceding claims, characterized in that the electrically conductive contact bushing ( 13 . 14 . 15 ) of substantially the same material as the metallization ( 22 . 26 ) or even forms a contact layer. Capsule according to one of the preceding claims, characterized in that the first capsule element ( 10 ) and / or the second capsule element ( 20 ) is designed disc or plate-shaped. Capsule according to one of the preceding claims, characterized in that the first capsule element ( 10 ) and / or the second capsule element ( 20 ) is made of one or more materials of the group silicon carbide, SOS, SOI group III nitrides, wherein the second capsule element is insulating or electrically passivatable. Capsule according to one of the preceding claims, characterized characterized in that it comprises a sensor, in particular a Pressure sensor. Method for encapsulating microsensors, in which at least two capsule elements ( 10 . 20 ) are interconnected to form an interior, characterized in that by means of a metallization ( 22 . 26 ) is sealed in one operation, the interior and at the same time an electrically conductive connection is formed from the interior to the outside, wherein at least a portion of the metallization ( 22 . 26 ) when connecting the capsule elements ( 10 . 20 ) a contact implementation ( 13 . 14 . 15 ) by one of the capsule elements ( 10 . 20 ) contacted electrically. A method according to claim 11, characterized in that the contact bushing ( 13 . 14 . 15 ) is formed by a further metallization and both capsule elements ( 10 . 20 ) before joining to the metallization ( 14 . 15 . 22 . 26 ), the metallization ( 14 . 15 . 22 . 26 ) is designed such that, in the case of mutual soldering, it is designed as a bond between the two capsule elements ( 10 . 20 ) And at the same time serves as a contact for an electrical connection between the interior and the exterior. Method according to claim 11 or 12, characterized in that the metallization ( 14 . 15 . 22 . 26 ) consists of at least two metals or alloys having a different melting point, said bonding occurring at a temperature which is between the two melting points. Method according to one of claims 11 to 13, characterized in that the metallization ( 14 . 15 . 22 . 26 ) Comprises titanium and copper and / or a material system from the group Ti / Au, Ti / Pt, Ti / Pt / Au, Ti / TiN / Au. Method according to one of claims 11 to 14, characterized in that in at least one of the capsule elements ( 10 . 20 ) through holes ( 13 ) are designed with the metallization ( 14 . 15 ). Method according to one of claims 11 to 15, characterized in that before joining a further metallization or a metallization region ( 26 ) is applied, which hermetically encloses an inner area after bonding. Capsule element ( 20 ) for forming a capsule for microsensors by connecting it to another capsule element ( 10 ), characterized by a metallization ( 22 ), which is designed so that it serves as a bonding connection and at the same time forms a contact for an electrically conductive contact bushing, which extends through the further capsule element. Capsule element according to claim 17, characterized in that the metallization ( 22 ) comprises at least two metals or alloys having a different melting point. Capsule element according to claim 17 or 18, characterized characterized in that it is used to form a capsule according to one of claims 1 to 10 is configured.