METHOD FOR FORMING A POWER SEMICONDUCTOR MODULE ARRANGEMENT

A method includes exerting a pressing force on a section of a first surface of a metal layer by a punch. Either the metal layer is arranged on a working surface with a second surface of the metal layer facing the working surface, the second surface being arranged opposite the first surface, and the punch is pressed against the section of the first surface with a pressing force that forces material of the metal layer to flow up against a stroke of the punch, thereby forming a sleeve extending from the first surface in a vertical direction and away from the second surface, or the punch is pressed against the section of the first surface and forced through the metal layer towards the second surface with a pressing force that forces material of the metal layer to flow down with a stroke of the punch, thereby forming a sleeve extending from the second surface in a vertical direction and away from the first surface. The method further includes, after forming the sleeve, arranging the metal layer in a housing of a power semiconductor module.

TECHNICAL FIELD

The instant disclosure relates to a method for forming a power semiconductor module arrangement.

BACKGROUND

Power semiconductor modules often include a substrate within a housing. The substrate usually comprises a substrate layer (e.g., a ceramic layer), a first metallization layer deposited on a first side of the substrate layer and, optionally, a second metallization layer deposited on a second side of the substrate layer. A semiconductor arrangement including one or more controllable semiconductor elements (e.g., IGBTs, MOSFETs, HEMTs) along with other elements such as passive components, bond wires, etc., may be arranged on the substrate. One or more terminal elements (contact elements), which allow for contacting such a semiconductor arrangement from outside the housing, are usually provided. Power semiconductor modules are known, where the terminal elements are arranged on the substrate and protrude in a direction that is essentially perpendicular to the main surface of the substrate through a cover of the housing.

There is a need for a method for forming a power semiconductor module arrangement that allows to mechanically and electrically couple terminal elements to a metal layer (e.g., metal layer of a substrate) in an efficient and cost-effective manner without creating contaminants that may potentially affect the function of the power semiconductor module.

SUMMARY

A method includes exerting a pressing force on a section of a first surface of a metal layer by means of a punch, wherein either the metal layer is arranged on a working surface, with a second surface of the metal layer facing the working surface, wherein the second surface is arranged opposite the first surface, and the punch is pressed against the section of the first surface with a pressing force that forces material of the metal layer to flow up against a stroke of the punch, thereby forming a sleeve extending from the first surface in a vertical direction and away from the second surface, or the punch is pressed against the section of the first surface and forced through the metal layer towards the second surface with a pressing force that forces material of the metal layer to flow down with a stroke of the punch, thereby forming a sleeve extending from the second surface in a vertical direction and away from the first surface. The method further includes, after forming the sleeve, arranging the metal layer in a housing of a power semiconductor module.

The invention may be better understood with reference to the following drawings and the description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings. The drawings show specific examples in which the invention may be practiced. It is to be understood that the features and principles described with respect to the various examples may be combined with each other, unless specifically noted otherwise. In the description as well as in the claims, designations of certain elements as “first element”, “second element”, “third element” etc. are not to be understood as enumerative. Instead, such designations serve solely to address different “elements”. That is, e.g., the existence of a “third element” does not require the existence of a “first element” and a “second element”. A semiconductor body as described herein may be made from (doped) semiconductor material and may be a semiconductor chip or may be included in a semiconductor chip. A semiconductor body has electrically connecting pads and includes at least one semiconductor element with electrodes.

Referring toFIG.1, a cross-sectional view of a power semiconductor module arrangement100is illustrated. The power semiconductor module arrangement100includes a housing7and a substrate10. The substrate10includes a dielectric insulation layer11, a (structured) first metallization layer111attached to the dielectric insulation layer11, and a (structured) second metallization layer112attached to the dielectric insulation layer11. The dielectric insulation layer11is disposed between the first and second metallization layers111,112.

Each of the first and second metallization layers111,112may consist of or include one of the following materials: copper; a copper alloy; aluminum; an aluminum alloy; any other metal or alloy that remains solid during the operation of the power semiconductor module arrangement. The substrate10may be a ceramic substrate, that is, a substrate in which the dielectric insulation layer11is a ceramic, e.g., a thin ceramic layer. The ceramic may consist of or include one of the following materials: aluminum oxide; aluminum nitride; zirconium oxide; silicon nitride; boron nitride; or any other dielectric ceramic. Alternatively, the dielectric insulation layer11may consist of an organic compound and include one or more of the following materials: Al2O3, AlN, SiC, BeO, BN, or Si3N4. For instance, the substrate10may, e.g., be a Direct Copper Bonding (DCB) substrate, a Direct Aluminum Bonding (DAB) substrate, or an Active Metal Brazing (AMB) substrate. Further, the substrate10may be an Insulated Metal Substrate (IMS). An Insulated Metal Substrate generally comprises a dielectric insulation layer11comprising (filled) materials such as epoxy resin or polyimide, for example. The material of the dielectric insulation layer11may be filled with ceramic particles, for example. Such particles may comprise, e.g., SiO2, Al2O3, AlN, SiN or BN and may have a diameter of between about 1 μm and about 50 μm. The substrate10may also be a conventional printed circuit board (PCB) having a non-ceramic dielectric insulation layer11. For instance, a non-ceramic dielectric insulation layer11may consist of or include a cured resin.

The substrate10is arranged in a housing7. In the example illustrated inFIG.1, the substrate10forms a ground surface of the housing7, while the housing7itself solely comprises sidewalls and a cover. It is, however, also possible that the substrate10be arranged on a ground surface of the housing7, or on a separate base plate which may be arranged to form a ground surface of the housing7. In some power semiconductor module arrangements100, more than one substrate10is arranged within the same housing7.

One or more semiconductor bodies20may be arranged on the at least one substrate10. Each of the semiconductor bodies20arranged on the at least one substrate10may include a diode, an IGBT (Insulated-Gate Bipolar Transistor), a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), a JFET (Junction Field-Effect Transistor), a HEMT (High-Electron-Mobility Transistor), or any other suitable semiconductor element.

The one or more semiconductor bodies20may form a semiconductor arrangement on the substrate10. InFIG.1, only two semiconductor bodies20are exemplarily illustrated. The second metallization layer112of the substrate10inFIG.1is a continuous layer. According to another example, the second metallization layer112may be a structured layer. According to other examples, the second metallization layer112may be omitted altogether. The first metallization layer111is a structured layer in the example illustrated inFIG.1. “Structured layer” in this context means that the respective metallization layer is not a continuous layer, but includes recesses between different sections of the layer. Such recesses are schematically illustrated inFIG.1. The first metallization layer111in this example includes three different sections. Different semiconductor bodies20may be mounted to the same or to different sections of the first metallization layer111. Different sections of the first metallization layer may have no electrical connection or may be electrically connected to one or more other sections using electrical connections3such as, e.g., bonding wires. Semiconductor bodies20may be electrically connected to each other or to the first metallization layer111using electrical connections3, for example. Electrical connections3, instead of bonding wires, may also include bonding ribbons, connection plates or conductor rails, for example, to name just a few examples. The one or more semiconductor bodies20may be electrically and mechanically connected to the substrate10by an electrically conductive connection layer30. Such an electrically conductive connection layer30may be a solder layer, a layer of an electrically conductive adhesive, or a layer of a sintered metal powder, e.g., a sintered silver (Ag) powder, for example.

The power semiconductor module arrangement100illustrated inFIG.1further includes terminal elements4. The terminal elements4are mechanically and electrically connected to the substrate10(e.g., to the first metallization layer111) and provide an electrical connection between the inside and the outside of the housing7. The terminal elements4may be mechanically and electrically connected to the first metallization layer111with a first end41, while a second end42of the terminal elements4protrudes out of the housing7. The first end41of a terminal element4may be electrically and mechanically connected to the substrate10by inserting the first end41into a sleeve or rivet61, for example. The sleeve or rivet61may be mechanically and electrically connected to the substrate10by means of an electrically conductive connection layer (not specifically illustrated) such as, e.g., a solder layer, a layer of an electrically conductive adhesive, or a layer of a sintered metal powder, e.g., a sintered silver (Ag) powder. The terminal elements4may be electrically contacted from the outside at their second end42. The housing7(i.e., the cover of the housing7) comprises a plurality of through holes72. Each of the plurality of terminal elements4protrudes vertically through a different one of the plurality of through holes72.

In addition to the terminal elements4described with respect toFIG.1, the components inside the housing7may also be electrically contacted from outside the housing7in any other suitable way. For example, additional terminal elements4may be arranged closer to or adjacent to the sidewalls of the housing7. It is also possible that terminal elements4protrude vertically or horizontally through the sidewalls of the housing7. The first end41of a terminal element4may be electrically and mechanically connected to the substrate10by inserting the first end41into a sleeve or rivet61.

The power semiconductor module arrangement100that has been described by means ofFIG.1above, however, is only an example. It is also possible to implement the power semiconductor module in different ways. As is schematically illustrated inFIG.2, for example, instead of arranging the substrate10in a housing7comprising sidewalls and a cover, the substrate10may be arranged in a molded housing7. In this example, the housing7is formed by a molded body of electrically insulating encapsulant material that covers the substrate10. InFIG.2, only a metal layer114(e.g., first metallization layer) of a substrate is schematically illustrated. The molded housing7in this example forms an insulative and protective structure that protects the metal layer114and any components (e.g., semiconductor bodies, or electrical connections) arranged thereon. A molded housing can include a wide variety of electrically insulating encapsulant materials including ceramics, epoxy materials and thermosetting plastics, to only name a few. A molded body may be formed by arranging the substrate10in a chamber and injecting liquefied encapsulant material into the chamber. Examples of these techniques include injection molding, transfer molding, and compression molding.

Similar to what has been described with respect toFIG.1above, the arrangement may comprise terminal elements4providing an electrical connection between the substrate (e.g., the metal layer114) and the outside of the housing7. The housing7comprises a plurality of through holes72, and each of the plurality of terminal elements4protrudes vertically through a different one of the plurality of through holes72. The first end41of a terminal element4may be electrically and mechanically connected to the substrate10by inserting the first end41into a sleeve or rivet61. As is schematically illustrated inFIG.2, the sleeve or rivet61may be formed by means of an indentation formed in the metal layer114.

As has been described with respect toFIG.1above, sleeves or rivets61may be mechanically and electrically coupled to the substrate10by an electrically conductive connection layer. Alternatively, as has been described with respect toFIG.2above, it is also possible that the sleeves or rivets61are formed by means of an indentation formed in the metal layer. Forming a sleeve or rivet61in or arranging a sleeve or rivet61on a metal layer may be cumbersome. Tools that are used to couple a sleeve61to the substrate10by means of an electrically conductive connection layer usually require a certain amount of space. This needs to be considered when planning the layout of the power semiconductor module arrangement (e.g., the arrangement of the different elements on the substrate10). Known methods that are used to form indentations in the metal layer that may function as sleeves61comprise drilling techniques that create contaminants that may potentially affect the function of the power semiconductor module. The methods according to embodiments described in the following avoid these and other drawbacks of known methods.

Now referring toFIGS.3A to3C, a method according to one embodiment of the disclosure is schematically illustrated. In this example, a metal layer110is arranged on a working surface90. The metal layer110comprises a first surface101and a second surface102, opposite the first surface101. As is illustrated inFIG.3A, the metal layer110is arranged on the working surface90such that the second surface102faces the working surface90and the first surface101faces away from the working surface90. Now referring toFIG.3B, a pressing force is exerted on a section of the first surface101of the metal layer110by means of a punch92. The section of the first surface101is small as compared to the overall cross-sectional area of the first surface101. According to one example, a largest extension of the section is between 0.4 and 5 mm (Millimeters). If the section has a round cross-section, the largest extension corresponds to a diameter of the section, for example. The section, however, may generally have any suitable cross-section, e.g., oval, square, rectangular, polygonal, etc. The section of the first surface101being small as compared to the overall cross-sectional area of the first surface101means that the punch92does not exert a pressing force on the entire first surface101. The punch92does not, or does not significantly compress the material of the metal layer110. Further, the punch92does not remove or ablate material of the metal layer110. Instead, a backward extruding process is performed in which material of the metal layer110is merely displaced. That is, as the punch92is pressed against the section of the first surface101, the resulting pressing force forces material of the metal layer110to flow up against a stroke of the punch92, thereby forming a sleeve62extending from the first surface101in a vertical direction y and away from the second surface102. The working surface90on which the metal layer110is arranged, prevents the material of the metal layer110from flowing down with a stroke of the punch92. The material of the metal layer110arranged horizontally adjacent to the section of the metal layer110to which the pressing force is applied prevents the material from flowing in a horizontal direction x. That is, the vertical direction y in a direction up against the stroke of the punch92is the only direction into which the material can flow, thereby forming the sleeve62.

The material of the metal layer110forming the sleeve62is displaced by pressing the punch92on the first surface101and moving it towards the second surface102. In this way, a hole64is formed in the metal layer110. A depth d64of the resulting hole64in the example illustrated inFIG.3Cis less than a thickness d110of the metal layer110. That is, a thin layer of metal remains between the hole64and the second surface102.

Forming the sleeve62in a desired shape may be supported by means of a shaping tool94, for example. As is illustrated inFIGS.3A to3Cand as has been described above, there is generally only one direction in which the material of the metal layer110may be displaced when forming the hole64. A shaping tool94, which is schematically illustrated inFIGS.4A and4B, may be used in order to form a sleeve62having a desired wall thickness, for example. As is schematically illustrated inFIG.4A, the shaping tool94may comprise a sleeve circumferentially surrounding the punch92at a distance d942. In this way, a cavity942is formed between the punch92and the shaping tool94that has the shape of a hollow cylinder. A wall thickness of the resulting sleeve62corresponds to the distance d942.FIG.5, in a bottom view, schematically illustrates the cavity942formed between the punch92and the shaping tool94.

The shaping tool94may be movably attached to the punch92, for example. That is, the shaping tool94may move in a vertical direction y with respect to the punch92. In an initial position, an end of the shaping tool94that faces the first surface101may be aligned with an end of the punch92facing the first surface101, as is illustrated by means of the dashed line inFIG.4A. That is, the punch92and the shaping tool94may contact the first surface101essentially at the same time. While the punch92penetrates into the metal layer110, thereby forming the hole64and forming the sleeve62, the shaping tool94(i.e., the end of the shaping tool94facing the first surface101) may rest on the first surface101without penetrating into the metal layer110. While the punch92moves from the first surface101towards the second surface102, the shaping tool94moves with respect to the punch92such that it may remain in its position on the first surface101. It is, however, also possible that the shaping tool94also exerts a certain force on the metal layer110, however, without significantly penetrating into the metal layer110. If the shaping tool94exerts a certain force on the metal layer110, thereby denting it to a certain degree, the flow of the material may be controlled to a higher degree. A defined indentation caused by the shaping tool may initiate the deformation of the material. The flowability of the material of the metal layer110may be further promoted by suitable chemical treatment of the metal layer110(e.g., suitable coating) or by physical treatment (e.g., thermal treatment).

The cavity942formed between the punch92and the shaping tool94is the only volume available for the material that is being displaced by the punch92such that it fills the cavity942at least partly. The geometry of the punch92as well as of the (optional) shaping tool94may have an influence on the process. The shape of the resulting sleeve62may be determined by the geometry of the punch92and/or the shaping tool94, e.g., by means of specific radii, chamfers, indentations, etc. of the punch92and/or shaping tool94.

Forming a sleeve62that extends from the first surface101in a vertical direction y and away from the second surface102, however, is only an example. According to another example, and as is schematically illustrated inFIG.6, it is alternatively also possible to form a sleeve62that extends from the second surface102in a vertical direction y and away from the first surface101. The metal layer110in this case is not arranged on a working surface90. The punch92is pressed against the section of the first surface101and is forced through the metal layer110towards the second surface102with a pressing force that forces material of the metal layer110to flow down with a stroke of the punch92. As there is no working surface90forming a barrier for the material of the metal layer110, the vertical direction y in a direction away from the first surface101is a preferred direction into which the material of the metal layer displaced by the punch92will flow. The sleeve62, therefore, is formed on an opposite side of the metal layer110, as compared to what has been described with respect toFIGS.3A-3C and4A-4Babove. The punch92, however, in this example penetrates all the way through the metal layer110from the first surface101to the second surface102. That is, a depth of a hole formed by the punch92in the metal layer110corresponds to the thickness d110of the metal layer110. The punch92may penetrate through the metal layer110even further, in order to form the sleeve62, as is schematically illustrated inFIG.6.

Similar to what has been described with respect toFIGS.4A-4B and5above, a shaping tool94may be provided in order to form a sleeve62having a desired shape (e.g., with a desired wall thickness). The shaping tool94in this example is not attached to the punch92. Instead, the shaping tool94is provided on the opposite side of the metal layer110(i.e. on the side of the second surface102). This is, because the material of the metal layer110flows in the opposite direction as compared to the example described above. The shaping tool94may have a similar shape as the shaping tool of the examples ofFIGS.4A-4B and5. That is, the shaping tool94may comprise a sleeve. The shaping tool94may be arranged to contact the second surface102of the metal layer110. According to one example, the shaping tool94is pressed onto the second surface102with a certain amount of force. The punch92is pushed through the metal layer110and is moved even further into the vertical direction y into the shaping tool94. In this way, a cavity between the punch92and the shaping tool94is formed, similar to what has been described with respect toFIG.5above. The material of the metal layer110that is displaced by the punch92flows into this cavity, thereby forming the sleeve62. The punch92, while not being connected to the shaping tool94, is also movable with respect to the shaping tool94or, more specifically, the punch92is movable with respect to the shaping tool94.

For some applications, forming the sleeve62by displacing the material of the metal layer110is sufficient. That is, there is enough material available to form the sleeve62in a desired size, shape and desired dimensions. It is, however, also possible to provide additional material. Now referring toFIG.7, a channel96may be provided in the punch92. The channel96may extend vertically through the punch92and may have an opening at the end of the punch92that contacts the metal layer110. Additional material may flow through the channel96. According to one example, material may flow through the channel96continuously while forming the sleeve62. The additional material may mix with the material of the metal layer110, thereby forming the sleeve62. In other words, the additional material may be kneaded into the material of the metal layer110that is displaced by means of the punch92to form the sleeve62. The additional material may be the same as or may differ from the material of the metal layer110. For example, the metal layer110may consist of or comprise a comparably cheap material such as, e.g., aluminum. The additional material may consist of or comprise a comparably expensive material such as, e.g., copper or gold, which has better electrical properties as compared to aluminum.

In the example illustrated inFIG.7, the additional material is provided by an endless strand. It is, however, also possible to provide defined amounts of additional material while forming the sleeve62. This is schematically illustrated inFIG.8. The additional material in this example may also be provided through a channel in the punch92. Additional material from an endless strand as well as in defined amounts, however, may also be provided in any other suitable way.

In the examples illustrated inFIGS.7and8, the additional material is mostly or entirely provided at the same time when forming the sleeve62(while exerting a pressing force on a section of the first surface101of the metal layer110by means of the punch92). As is schematically illustrated inFIG.9, it is however also possible that additional material is provided, at least partly, before exerting a pressing force by means of the punch92. That is, a layer of additional material118may be formed on the metal layer118. This layer of additional material118may be formed in any suitable way. The punch92may then be arranged on the layer of additional material118and exert a pressing force on the metal layer110. The additional material in this example mixes with the material of the metal layer110similar to what has been described with respect toFIGS.7and8above.

Exerting a force on the metal layer110by means of a punch92may comprise pressing the punch92on the material of the metal layer110with a constant force without any additional movement of the punch92. The material of the metal layer reaches its yield point under load and deforms plastically. Now referring toFIG.10, forming the sleeve62by means of the punch92may be further promoted in different ways. For example, exerting a pressing force on a section of a first surface101of a metal layer110by means of a punch92may comprise moving the punch92from the first surface101towards the second surface102in a pulsed manner. That is, the force transmitted by the punch is increased incrementally in a repetitive manner. This is schematically illustrated by means of the series of short arrows (Example a). Alternatively or additionally, exerting a pressing force on a section of a first surface101of a metal layer110by means of a punch92may comprise rotating the punch92. By rotating the punch92, the material of the metal layer110can be more easily set in motion. The resulting friction generates heat which further assists the deformation of the material, as the yield point of the material is reached earlier. This is schematically illustrated by means of the bent arrow (Example b). The punch92may be helical, threaded, or spiral-shaped, for example, or have any other shape that results in the punch92drilling into the metal layer110without resulting in an ablation of the material.

Alternatively or additionally, exerting a pressing force on a section of a first surface101of a metal layer110by means of a punch92may comprise oscillating the punch92. An oscillating movement of the punch may have a similar effect as moving the punch92in a pulsed manner, as has been described above. When moving the punch92in an oscillating manner, however, the material of the metal layer110is repeatedly relieved for a short moment. This is schematically illustrated by means of the double-sided arrow inFIG.10(Example c). Alternatively or additionally, exerting a pressing force on a section of a first surface101of a metal layer110by means of a punch92may comprise performing an ultrasonic supported material forming. That is, the process of forming the sleeve62may be supported by means of ultrasound, similar to conventional ultrasonic welding techniques. In particular, similar effects as in ultrasonic welding techniques may be achieved. For example, the material of the metal layer110may heat up due to the alternating strain caused by the ultrasound, thereby reducing the yield point of the material of the metal layer110. InFIG.10, this is schematically illustrated by means of the oscillating line (Example d).

Alternatively or additionally, exerting a pressing force on a section of a first surface101of a metal layer110by means of a punch92may comprise applying heat to the metal layer110such that the yield point of the material is reached earlier. In this way, the force exerted by the punch92may be minimized. This is schematically illustrated by means of the flash (Example e). Heat may be generated in any suitable way. As has been described above, applying ultrasound or rotating the punch92may result in the generation of heat. It is, however, also possible to generate heat in any other suitable way such as, e.g., conductively, inductively or by means of an electromagnetic light source (e.g., laser, microwave, etc.).

InFIG.10, the metal layer110is arranged on a working surface90. It is, however, also possible to apply one or more of the supporting measures as described above for a metal layer110that is not arranged on a working surface90, as is described with respect toFIG.6, for example.

With the methods described above, a sleeve62may be formed from the material of the metal layer110. That is, the sleeve62and the metal layer110form a single piece. No connection procedure is required to mechanically couple a separate sleeve to the metal layer110. The sleeve62is formed by means of a (backwards) extrusion process (see, e.g., DIN 8583). That is, a plastic deformation of the material occurs.

Generally speaking, a method for forming a sleeve62on a metal layer110comprises exerting a pressing force on a section of a first surface101of a metal layer110by means of a punch92, wherein either the metal layer110is arranged on a working surface90, with a second surface102of the metal layer110facing the working surface90, wherein the second surface102is arranged opposite the first surface101, and the punch92is pressed against the section of the first surface101with a pressing force that forces material of the metal layer110to flow up against a stroke of the punch92, thereby forming a sleeve62extending from the first surface101in a vertical direction y and away from the second surface102. Alternatively, the punch92is pressed against the section of the first surface101and forced through the metal layer110towards the second surface102with a pressing force that forces material of the metal layer110to flow down with a stroke of the punch92, thereby forming a sleeve62extending from the second surface102in a vertical direction y and away from the first surface101.

The metal layer110may be the metal layer of a substrate10. That is, the metal layer110may be arranged on a dielectric insulation layer11, as has been described with respect toFIGS.1and2above. The metal layer110may be arranged on a dielectric insulation layer11before forming the sleeve62or after forming the sleeve62. The dielectric insulation layer11may be a ceramic layer consisting of or comprising aluminum oxide, aluminum nitride, zirconium oxide, silicon nitride, boron nitride, silicon carbide, beryllium oxide, or boron nitride, for example. Alternatively, the dielectric insulation layer11may be an Insulated Metal Substrate comprising epoxy resin or polyimide. According to an even further example, the dielectric insulation layer11may be a non-ceramic dielectric insulation layer11consisting of or including a cured resin. The metal layer110may comprise or consist of copper, a copper alloy, aluminum, or an aluminum alloy, for example.

If the metal layer110is arranged on the dielectric insulation layer11after forming the sleeve62, it is arranged on the dielectric insulation layer11such that the sleeve62faces away from the dielectric insulation layer11. After forming the sleeve62, the metal layer110is arranged in a housing7of a power semiconductor module100. The metal layer110may be arranged on a dielectric insulation layer11before arranging the metal layer110in the housing7. The method for forming a sleeve62may be repeated several times, for example, in order to form a plurality of sleeves62on the metal layer110. It is, however, also possible to form a plurality of sleeves62simultaneously.

A terminal element4may be arranged in the sleeve62, similar to what has been described with respect toFIGS.1and2above, wherein the terminal element4is configured to provide an electrical connection between the metal layer110and the outside of the housing7. According to one example, the punch92is a dedicated tool for forming the sleeve62and is removed once forming of the sleeve62has been completed. It is, however, also possible that a terminal element4is used as a punch92. In this case, the terminal element4may remain in the sleeve62once forming of the sleeve62has been completed. In this case, a separate step of inserting a terminal element4into the sleeve62is not required. A terminal element4may have a diameter of, e.g., 0.4 to 5 mm. An inner diameter of the sleeve62may correspond to or may be slightly smaller than the diameter of the terminal element4. In this way, the terminal element4is pressed into the sleeve62, thereby forming a stable connection between the terminal element4and the sleeve62. As is illustrated inFIG.5, for example, a diameter d92of the punch92may correspond to the inner diameter of the resulting sleeve62.

The punch92illustrated inFIG.5has a round cross-section. This, however, is only an example. The punch92may generally have any suitable cross-section, e.g., oval, square, rectangular, polygonal, etc. The cross-section of the punch92may correspond to the cross-section of the terminal element4that is to be inserted into the sleeve62. It is, however, also possible that the cross-section of the terminal element4inserted into a sleeve62differs from the cross-section of the sleeve62. For example, a terminal element4having a square cross-section may be inserted into a sleeve62having a round cross-section. In this case, the terminal element4cants when being pressed into the sleeve62. In this way, a mechanically stable connection between the terminal element4and the sleeve62may be formed. Other cross-sections, however, are also possible.

According to an even further example, the sleeve62may be formed such that a thread is formed on its inner diameter. A terminal element4may comprise a matching thread and may be screwed into the sleeve62. In this way, a detachable connection may be formed between the terminal element4and the sleeve4. That is, the terminal element4may be removed from the sleeve62without damaging the sleeve62and/or the terminal element4.

The expression “and/or” should be interpreted to include all possible conjunctive and disjunctive combinations, unless expressly noted otherwise. For example, the expression “A and/or B” should be interpreted to mean only A, only B, or both A and B. The expression “at least one of” should be interpreted in the same manner as “and/or”, unless expressly noted otherwise. For example, the expression “at least one of A and B” should be interpreted to mean only A, only B, or both A and B.

It is to be understood that the features of the various embodiments described herein can be combined with each other, unless specifically noted otherwise.