Patent Description:
Power semiconductor module arrangements often include at least one semiconductor substrate arranged in a housing. A semiconductor arrangement including a plurality of controllable semiconductor elements (e.g., two IGBTs in a half-bridge configuration) is arranged on each of the at least one substrate. Each 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 a second metallization layer deposited on a second side of the substrate layer. The controllable semiconductor elements are mounted, for example, on the first metallization layer. The second metallization layer may optionally be attached to a base plate. The controllable semiconductor devices are usually mounted to the semiconductor substrate by soldering or sintering techniques.

Electrical lines or electrical connections are used to connect different semiconductor devices of the power semiconductor arrangement. Such electrical lines and connections may include metal and/or semiconductor material. The housings of power semiconductor module arrangements are generally permeable to gases to a certain extent. Some gases such as sulfur containing gases, for example, may react with metallic components inside the housing. This leads to a chemical degradation of these components which may result in a failure of individual components and ultimately of the whole semiconductor arrangement.

Document <CIT> discloses a power semiconductor module comprising at least one semiconductor substrate comprising a dielectric insulation layer, a first metallization layer attached to the dielectric insulation layer, and a second metallization layer attached to the dielectric insulation layer, wherein the dielectric insulation layer is disposed between the first and second metallization layers. A power semiconductor arrangement is arranged on the at least one semiconductor substrate, wherein the power semiconductor arrangement includes at least one first terminal element and wherein the first terminal element is connected to the semiconductor substrate with a first end. The power semiconductor module further comprises a base plate, wherein the semiconductor substrate is arranged on the base plate, a housing that is configured to enclose the semiconductor substrate and that is configured to be connected to the base plate, the housing comprising sidewalls and a cover, wherein the cover comprises an opening, and a second terminal element that is arranged within the opening in the cover of the housing such that a first end of the second terminal element protrudes into the housing, the first end being configured to be electrically and mechanically connected to a second end of the first terminal element to form a contact element, and such that a second end of the second terminal element protrudes out of the housing to allow the contact element to be electrically contacted from the outside. A first seal is arranged within the opening in the cover of the housing, the first seal being configured to seal the opening such that gases are prevented from entering the housing through the opening.

There is a need for a housing and a power semiconductor module comprising a housing wherein the semiconductor components are protected against corrosion such that the overall lifetime of the power semiconductor module arrangement is increased.

The invention is set out in the appended claims <NUM> to <NUM>.

A housing for a power semiconductor module includes sidewalls and a lid. The lid includes a first layer of a first material comprising a plurality of openings, and second layer of a second material that is different from the first material, wherein the second layer completely covers a bottom surface of the first layer, and the second layer comprises a plurality of protrusions, each protrusion extending into a different one of the plurality of openings of the first layer such that each of the plurality of openings is completely covered by one of the protrusions. Each protrusion of the second layer forms a membrane, each membrane covering one of the openings of the first layer, thereby sealing the openings of the first layer to prevent air, moisture and corrosive gases from entering the inside of the housing. Each membrane is configured to allow a terminal element to easily penetrate through the membrane when inserting a terminal element through the opening.

A power semiconductor module includes a substrate, at least one semiconductor body arranged on a top surface of the substrate, and the housing, wherein the substrate with the at least one semiconductor body arranged thereon is arranged within the housing. The power semiconductor module arrangement further comprises at least one terminal element, wherein a first end of each of the at least one terminal element extends through the inside of the housing, a second end of each of the at least one terminal element protrudes through the second layer and through a different one of the openings to the outside of the housing, wherein the number of openings is greater than the number of terminal elements such that at least one of the openings remains covered and sealed by the respective membrane formed by the second layer.

A method for forming a lid of a housing for a power semiconductor module arrangement includes forming a first layer of a first material including a plurality of openings, forming a second layer of a second material that is different from the first material, wherein the second layer includes a plurality of protrusions, and arranging the second layer on the first layer such that the second layer completely covers a bottom surface of the first layer, and each protrusion extends into a different one of the plurality of openings of the first layer such that each of the plurality of openings is completely covered by one of the protrusions. Each protrusion of the second layer forms a membrane, each membrane covering one of the openings of the first layer, thereby sealing the openings of the first layer to prevent air, moisture and corrosive gases from entering the inside of the housing.

Each membrane is configured to allow a terminal element to easily penetrate through the membrane when inserting a terminal element through the opening.

Another method for producing a housing for a power semiconductor module arrangement includes forming, in a mold, a first layer of a first material including a plurality of openings, after forming the first layer, forming, in the same mold, a second layer of a second material that is different from the first material, wherein the second layer is formed including a plurality of protrusions, the second layer completely covers a bottom surface of the first layer, and each protrusion extends into a different one of the plurality of openings of the first layer such that each of the plurality of openings is completely covered by one of the protrusions. Each protrusion of the second layer forms a membrane, each membrane covering one of the openings of the first layer, thereby sealing the openings of the first layer to prevent air, moisture and corrosive gases from entering the inside of the housing.

In the following detailed description, reference is made to the accompanying drawings. The drawings show an example and embodiments in which the invention may be practiced. It is to be understood that the features and principles described with respect to the various embodiments falling within the scope of the present invention 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". An electrical line or electrical connection as described herein may be a single electrically conductive element, or include at least two individual electrically conductive elements connected in series and/or parallel. Electrical lines and electrical connections may include metal and/or semiconductor material, and may be permanently electrically conductive (i.e., non-switchable). A semiconductor body as described herein may be made from (doped) semiconductor material and may be a semiconductor chip or be included in a semiconductor chip. A semiconductor body has electrically connecting pads and includes at least one semiconductor element with electrodes.

Referring to <FIG>, not forming part of the present invention but useful for understanding it, a cross-sectional view of a power semiconductor module arrangement <NUM> is illustrated. The power semiconductor module arrangement <NUM> includes a housing <NUM> and a semiconductor substrate <NUM>. The semiconductor substrate <NUM> includes a dielectric insulation layer <NUM>, a (structured) first metallization layer <NUM> attached to the dielectric insulation layer <NUM>, and a (structured) second metallization layer <NUM> attached to the dielectric insulation layer <NUM>. The dielectric insulation layer <NUM> is disposed between the first and second metallization layers <NUM>, <NUM>.

Each of the first and second metallization layers <NUM>, <NUM> may 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 semiconductor substrate <NUM> may be a ceramic substrate, that is, a substrate in which the dielectric insulation layer <NUM> is 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. For example, the dielectric insulation layer <NUM> may consist of or include one of the following materials: Al<NUM>O<NUM>, AlN, SiC, BeO or Si<NUM>N<NUM>. For instance, the substrate <NUM> may, e.g., be a Direct Copper Bonding (DCB) substrate, a Direct Aluminum Bonding (DAB) substrate, or an Active Metal Brazing (AMB) substrate. Further, the substrate <NUM> may be an Insulated Metal Substrate (IMS). An Insulated Metal Substrate generally comprises a dielectric insulation layer <NUM> comprising (filled) materials such as epoxy resin or polyimide, for example. The material of the dielectric insulation layer <NUM> may be filled with ceramic particles, for example. Such particles may comprise, e.g., Si<NUM>O, Al<NUM>O<NUM>, AlN, or BrN and may have a diameter of between about <NUM> and about <NUM>. The substrate <NUM> may also be a conventional printed circuit board (PCB) having a non-ceramic dielectric insulation layer <NUM>. For instance, a non-ceramic dielectric insulation layer <NUM> may consist of or include a cured resin.

The semiconductor substrate <NUM> is arranged in a housing <NUM>. In the example not forming part of the present invention but useful for understanding it and illustrated in <FIG>, the semiconductor substrate <NUM> forms a ground surface of the housing <NUM>, while the housing <NUM> itself solely comprises sidewalls and a cover. This is, however, only an example not forming part of the present invention but useful for understanding it. It is also possible that the housing <NUM> further comprises a ground surface and the semiconductor substrate <NUM> be arranged inside the housing <NUM>. According to another example not forming part of the present invention but useful for understanding it, the semiconductor substrate <NUM> may be mounted on a base plate (not illustrated). In some power semiconductor module arrangements <NUM>, more than one semiconductor substrate <NUM> is arranged on a single base plate. The base plate may form a ground surface of the housing <NUM>, for example.

One or more semiconductor bodies <NUM> may be arranged on the semiconductor substrate <NUM>. Each of the semiconductor bodies <NUM> arranged on the semiconductor substrate <NUM> may 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 controllable semiconductor element.

The one or more semiconductor bodies <NUM> may form a semiconductor arrangement on the semiconductor substrate <NUM>. In <FIG>, only two semiconductor bodies <NUM> are exemplarily illustrated. The second metallization layer <NUM> of the semiconductor substrate <NUM> in <FIG> is a continuous layer. The first metallization layer <NUM> is a structured layer in the example not forming part of the present invention but useful for understanding it and illustrated in <FIG>. "Structured layer" means that the first metallization layer <NUM> is not a continuous layer, but includes recesses between different sections of the layer. Such recesses are schematically illustrated in <FIG>. The first metallization layer <NUM> in this example includes three different sections. Different semiconductor bodies <NUM> may be mounted to the same or to different sections of the first metallization layer <NUM>. Different sections of the first metallization layer may have no electrical connection or may be electrically connected to one or more other sections using, e.g., bonding wires <NUM>. Electrical connections <NUM> may also include connection plates or conductor rails, for example, to name just a few examples. The one or more semiconductor bodies <NUM> may be electrically and mechanically connected to the semiconductor substrate <NUM> by an electrically conductive connection layer <NUM>. Such an electrically conductive connection layer may be a solder layer, a layer of an electrically conductive adhesive, or a layer of a sintered metal powder, e.g., a sintered silver powder, for example.

The power semiconductor module arrangement <NUM> illustrated in <FIG> further includes terminal elements <NUM>. The terminal elements <NUM> are electrically connected to the first metallization layer <NUM> and provide an electrical connection between the inside and the outside of the housing <NUM>. The terminal elements <NUM> may be electrically connected to the first metallization layer <NUM> with a first end, while a second end <NUM> of the terminal elements <NUM> protrudes out of the housing <NUM>. The terminal elements <NUM> may be electrically contacted from the outside at their second end <NUM>. The terminal elements <NUM> illustrated in <FIG>, however, are only examples. Terminal elements <NUM> may be implemented in any other way and may be arranged anywhere within the housing <NUM>. For example, one or more terminal elements <NUM> may be arranged close to or adjacent to the sidewalls of the housing <NUM>. Any other suitable implementation is possible.

The semiconductor bodies <NUM> each may include a chip pad metallization, e.g., a source, drain, gate, anode or cathode metallization. A chip pad metallization generally provides a contact surface for electrically connecting the semiconductor body <NUM>. The chip pad metallization may electrically contact a connection layer <NUM>, a terminal element <NUM>, or an electrical connection <NUM>, for example. A chip pad metallization may consist of or include a metal such as aluminum, copper, gold or silver, for example. The electrical connections <NUM> and the terminal elements <NUM> may also consist of or include a metal such as copper, aluminum, gold, or silver, for example.

The above mentioned components, as well as other components of the power semiconductor module arrangement <NUM> inside the housing <NUM>, may corrode when they come into contact with corrosive gases. Corrosive gases may include, e.g., sulfur or sulfur-containing compounds such as hydrogen sulfide H<NUM>S, for example. Corrosive gases in the surrounding area of the power semiconductor module arrangement <NUM> may penetrate into the inside of the housing <NUM>. The housings <NUM> that are used for power semiconductor module arrangements <NUM> are usually not fully protected against intruding gases. Inside the housing <NUM>, the corrosive gases may form acids or solutions, for example, in combination with moisture that may be present inside the housing <NUM>. The corrosive gases or the resulting solutions may cause a corrosion of some or all of the components. During the corrosion process, the metallic constituents of the components may be oxidized to their respective sulfides. The sulfide formation may alter the electrical properties of the components or may result in the formation of new conductive connections and in short circuits within the power semiconductor module arrangement <NUM>.

Further, when exposed to corrosive gases and further under the influence of electric fields and possibly moisture, dendritic structures may form from mobile metal ions (e.g., Cu, Ag, etc.) of the metal comprising components and structures of the power semiconductor module arrangement <NUM> and anions (e.g., S<NUM>-) that are present in the corrosive gas. A dendrite is a characteristic tree-like structure of crystals. Dendritic growth in metal layers has large consequences with regard to material properties and is generally unwanted.

Examples for corrosive gases are hydrogen sulfide (H<NUM>S), carbonyl sulfide (OCS), or gaseous sulfur (S<NUM>). In some applications, the power semiconductor module arrangement may be exposed to corrosive gases such as Cl-, SOx, or NOx, for example. Generally, it is also possible that sulfur gets to the inside of the housing <NUM> as constituent of a solid material or liquid.

Components and structures including one or more metals such as copper (e.g., first metallization layer <NUM>, electrical connection <NUM>, terminal element <NUM>, connection layer <NUM>, chip pad metallization), silver (e.g., first metallization layer <NUM>, electrical connection <NUM>, terminal element <NUM>, connection layer <NUM>, chip pad metallization), or lead (e.g. connection layer <NUM> including leaded solder), may be particularly sensitive to corrosion. Other metals such as aluminum, for example, may have a thin oxide layer covering their surface area, which may provide at least a certain amount of protection against corrosive gases.

Conventional power semiconductor module arrangements <NUM> generally further include a casting compound <NUM>. The casting compound <NUM> may consist of or include a silicone gel or may be a rigid molding compound, for example. The casting compound <NUM> may at least partly fill the interior of the housing <NUM>, thereby covering the components and electrical connections that are arranged on the semiconductor substrate <NUM>. The terminal elements <NUM> may be partly embedded in the casting compound <NUM>. At least their second ends <NUM>, however, are not covered by the casting compound <NUM> and protrude from the casting compound <NUM> through the housing <NUM> to the outside of the housing <NUM>. The casting compound <NUM> is configured to protect the components and electrical connections inside the power semiconductor module <NUM>, in particular inside the housing <NUM>, from certain environmental conditions and mechanical damage. The casting compound <NUM> further provides for an electrical isolation of the components inside the housing <NUM>. However, corrosive gases are usually able to penetrate through the casting compound <NUM>. The casting compound <NUM>, therefore, is usually not able to protect the components and electrical connections from corrosive gases.

The casting compound <NUM> may form a protective layer in a vertical direction y of the semiconductor substrate <NUM>. The vertical direction is a direction that is essentially perpendicular to a top surface of the semiconductor substrate <NUM>. The top surface of the semiconductor substrate <NUM> is a surface on which semiconductor bodies <NUM> are or may be mounted. The casting compound <NUM> at least partly covers any components that are arranged on the top surface of the semiconductor substrate <NUM> as well as any exposed surfaces of the semiconductor substrate <NUM>.

<FIG> schematically illustrates a semiconductor module falling within the scope of the present invention with a plurality of terminal elements <NUM> (first ends <NUM> of terminal elements) protruding out of the lid of the housing <NUM>. The lid according to an embodiment falling within the scope of the present invention comprises a plurality of openings <NUM>. Terminal elements <NUM> protrude out of some but not all of the openings <NUM>. By providing a plurality of openings <NUM> in the lid, one and the same housing <NUM> can be used for many different layouts or applications without the need for customizing the housing <NUM> for specific applications or customers. However, each of the openings <NUM> is a weak spot of the housing <NUM> through which corrosive gases may enter the inside of the housing <NUM>. This applies for each of the plurality of openings <NUM>, regardless of whether or not a terminal element <NUM> protrudes through the opening <NUM>. A casting compound <NUM> as described above may not provide sufficient protection against corrosive gases.

Therefore, to better protect the metallic components of the power semiconductor module arrangement <NUM> against corrosive gases, the cover <NUM> comprises a first layer <NUM> and a second layer <NUM>. This is schematically illustrated in <FIG>. The power semiconductor arrangement <NUM> illustrated in <FIG>, falling within the scope of the present invention, essentially corresponds to the power semiconductor module arrangement <NUM> illustrated in <FIG> not forming part of the present invention but useful for understanding it. The only difference being the housing <NUM>. While the housing <NUM> illustrated in <FIG> is a single layer housing comprising only a single layer of a first material, the housing <NUM> illustrated in <FIG> is a double layer housing comprising a first layer <NUM> of a first material and a second layer <NUM> of a second material that is different from the first material <NUM>. In the embodiment illustrated in <FIG> falling within the scope of the present invention,, only the lid of the housing <NUM> comprises two layers <NUM>, <NUM>, while the sidewalls of the housing <NUM> comprise only the first layer. This, however, is only an embodiment falling within the scope of the present invention. According to another embodiment falling within the scope of the present invention, the sidewalls and/or a bottom of the housing <NUM> also comprise the first layer <NUM> and the second layer <NUM>. The terminal elements <NUM> protrude through the openings <NUM> formed in the housing <NUM>.

This is exemplarily illustrated in further detail in <FIG>. <FIG> exemplarily illustrates a section A of the arrangement of <FIG> in greater detail. As is illustrated in <FIG> and will be described in further detail with respect to <FIG> below, the first layer <NUM> comprises a plurality of openings <NUM>. Only one of the plurality of openings <NUM> is exemplarily illustrated in <FIG>. The second layer <NUM> is arranged adjacent to and directly adjoins the first layer <NUM>. The second layer <NUM> is arranged on the inside of the housing <NUM>, whereas the first layer <NUM> is arranged on the outside of the housing <NUM>. The second layer <NUM> completely covers a bottom side of the first layer <NUM> (i.e., the lid), wherein a bottom side of the first layer <NUM> (the lid) is a side which faces the inside of the housing <NUM>. The second layer <NUM> at least partly extends into each of the plurality of openings <NUM>. In this way, any gaps or spaces between the first layer <NUM> and the terminal element <NUM> are sealed by the second layer <NUM> when a terminal element <NUM> extends through the opening <NUM>.

When the housing <NUM> is mounted on a power semiconductor module arrangement and at least one terminal element <NUM> protrudes through at least one of the openings <NUM>, the first layer <NUM> is not in direct contact with the at least one terminal element <NUM>. For example, each of the openings <NUM> may have a round, square, or any other suitable cross-section, and the terminal element <NUM> may protrude centrally through the opening <NUM>. The second layer <NUM> on the other hand adjoins and directly contacts each of the terminal elements <NUM>. In this way, each of the plurality of openings <NUM> is sealed to prevent air, moisture and corrosive gases from entering the inside of the housing <NUM>.

In the embodiment illustrated in <FIG> falling within the scope of the present invention, the first layer <NUM> forms a collar or sleeve <NUM> around the opening <NUM>. The second layer <NUM> at least partly extends into this collar or sleeve <NUM>. That is, the second layer <NUM> comprises a plurality of protrusions, each protrusion extending into a different one of the plurality of openings <NUM>. A cross-sectional area of a terminal element <NUM> is smaller than a cross-sectional area of the opening <NUM>. If, for example, the terminal element <NUM> and the opening <NUM> each have a rounded cross-section, a diameter of the terminal element <NUM> may be smaller than a diameter of the respective opening. In order to facilitate the insertion of the terminal element <NUM>, the second layer <NUM> in the range of the protrusion and the opening <NUM> may form a funnel <NUM>. When inserting the terminal element <NUM> into the opening, the terminal element <NUM> may first be inserted into the wider side of the funnel <NUM> and, from there, be led through the center of the opening <NUM>.

Now referring to <FIG>, the collar or sleeve <NUM> around the openings <NUM> may be omitted. To prevent the second layer <NUM> from unintentionally slipping out of the opening <NUM>, the protrusion of the second layer <NUM> extends through the opening <NUM> and cover parts of the first layer <NUM> that are arranged on the outside of the housing <NUM>. That is, the second layer <NUM> completely covers a bottom surface of the first layer <NUM> and partly covers a top surface of the first layer <NUM>. In this way, in the range of the openings <NUM>, the first layer <NUM> is sandwiched between portions of the second layer <NUM>.

According to an even further embodiment falling within the scope of the present invention illustrated in <FIG>, the first layer <NUM> may comprise protrusions <NUM> around the circumference of the opening <NUM>. The first layer <NUM> may have a first thickness in a vertical direction y. A thickness of the protrusion <NUM> in the same vertical direction y is smaller than the first thickness. Such protrusions <NUM> may provide a further fixation of the second layer <NUM> to prevent it from unintentionally slipping out of the opening <NUM>. The protrusion <NUM> may have any suitable form.

Now referring to <FIG>, the first and second layers <NUM>, <NUM> are schematically illustrated before inserting the terminal element <NUM> through the opening <NUM>. Before inserting the terminal element <NUM> into the opening <NUM>, the second layer <NUM> completely covers the opening <NUM>. According to one embodiment falling within the scope of the present invention, a thickness of the second layer <NUM> in the vertical direction y may be smaller in the range of the openings <NUM> as compared to a thickness of the second layer <NUM> in the same direction in those sections where it covers the bottom surface of the first layer <NUM>. In this way a plurality of membranes <NUM> are formed, each of which covers one of the plurality of openings <NUM>. A terminal element <NUM> easily penetrates through the membrane <NUM> when inserting it through the opening <NUM>. The opening <NUM>, however, is still sufficiently sealed after inserting the terminal element <NUM>. That is, the sealing between the terminal element <NUM> and the second layer <NUM> is realized by the penetration of the terminal element <NUM> through the second layer <NUM> and the elastic behavior of the material of the second layer <NUM>. When penetrating through the membrane <NUM>, the first end <NUM> of the terminal element <NUM> opens a small hole in the second layer <NUM>. After this initial hole has been formed, the material of the second layer <NUM> elastically moves to allow the terminal element <NUM> to advance further through the hole. When the terminal element <NUM> is in its final position, the material of the second layer <NUM> due to its elastic properties forms a tight collar around the terminal element <NUM>.

Optionally, the membrane <NUM> can have specific structures such as, e.g., predetermined breaking points, to allow for a controlled rupture and to support the formation of the collar around the terminal element <NUM>. According to another embodiment falling within the scope of the present invention, it is also possible to first penetrate those membranes <NUM> through which a terminal element <NUM> is to be inserted by means of a needle before inserting the terminal elements <NUM> in the holes <NUM>. Holes <NUM> through which no terminal element <NUM> is to be inserted remain covered and sealed by the membrane <NUM> formed by the second layer <NUM>.

Now referring to <FIG>, a housing <NUM> is schematically illustrated before mounting it to a power semiconductor module arrangement. That is, the plurality of openings <NUM> of the first layer <NUM> are still completely covered by the second layer <NUM> which protrudes at least partly through the openings <NUM>. <FIG> schematically illustrates the housing <NUM> from the inside where a plurality of funnels <NUM> is visible.

Referring again to <FIG>, the second layer <NUM> further provides a seal between the lid or cover and the sidewalls of the housing. The lid and the sidewalls of the housing <NUM> may be produced as a separate pieces. In this way, the sidewalls can be mounted to the power semiconductor module arrangement first with the lid still open. The material forming the casting compound <NUM> can be filled into the housing <NUM> before mounting the lid to the sidewalls. In this way, an additional opening in the lid through which the material could be inserted into the housing <NUM> can be omitted. However, if the lid and sidewalls are provided as separate pieces, corrosive gases may enter the housing <NUM> in the range of the points of contact between the lid and the sidewalls. The second layer <NUM> in a horizontal direction x may adjoin the sidewalls after assembling the lid and the sidewalls. In this way, any unintended gaps between the first layer <NUM> of the sidewalls and the first layer <NUM> of the lid can be covered by the second layer <NUM>. The second layer <NUM> due to its elastic properties may form a tight seal between the sidewalls and the lid.

As has been described above, the first layer <NUM> comprises a first material and the second layer <NUM> comprises a second material that is different from the first material. In particular, the first material can be a comparably rigid material. In this way, the housing <NUM> can provide sufficient protection against mechanical damage. The second material, on the other hand, can be a material that is soft as compared to the first material. The second material can further comprise certain elastic properties. This allows the terminal elements <NUM> to penetrate through the membranes <NUM> formed by the second layer <NUM> and to tightly close any gaps between the first layer <NUM> and the terminal elements <NUM>. The first layer <NUM>, for example, can comprise any kind of hard plastic materials or epoxy. The second layer <NUM> can comprise at least one of soft polymers, silicones, (thermoplastic) elastomers, polyurethanes, acrylates, or rubbers, for example. According to one embodiment falling within the scope of the present invention, the first layer <NUM> may have a hardness of at least <NUM> Shore D, or at least <NUM> Shore D. The second layer <NUM>, for example, may have a hardness of <NUM> Shore A or less, or of <NUM> Shore A or less, or of <NUM> Shore <NUM> or less.

To even better protect the metallic components of the power semiconductor module arrangement <NUM> against corrosive gases, the second layer <NUM> of the housing may further include a reactant, for example. The reactant may be configured to chemically react with the corrosive gases, or, in particular, with the sulfur or sulfur-containing compounds of the corrosive gases. Corrosive gas may also be trapped, adsorbed or absorbed by the reactant. By chemically reacting with the corrosive gas, the reactant further prevents the harmful substances from reaching the (metal) components inside the housing <NUM> and thereby protects the components against corrosion. The reactant may be, for example, a powder of a third material which is distributed throughout the second material of the second layer <NUM>. The third material may include any materials, e.g., metallic materials, which react with the corrosive gases and which may, e.g., form a metal sulfide when exposed to corrosive gases. The reactant may be essentially evenly distributed throughout the second material of the second layer <NUM>.

The second layer <NUM> may adhere to the first layer, e.g., by means of chemical bonding, mechanical interlock or any other suitable connection method. An example of a mechanical interlock has been described by means of <FIG> and <FIG> above. Depending on the materials used for the first layer <NUM> and the second layer <NUM>, a chemical bond may be formed between the layers <NUM>, <NUM>, for example. According to one embodiment falling within the scope of the present invention, the second layer <NUM> has a certain adhesiveness such that it adheres to the first layer to a certain degree without the need for any mechanical interlocks.

The housing <NUM> can be produced using any suitable technique such as, e.g., (<NUM>) injection molding, manual assembly of separately produced injection molded or casted parts, and dispensing of a soft component on an injection molded part.

Now referring to <FIG> falling within the scope of the present invention, an embodiment of a method for producing a housing <NUM> falling within the scope of the present invention is exemplarily illustrated. As is illustrated in the top view of <FIG>, in a first step a first layer <NUM> of a first material is formed. The first layer <NUM> may have a rectangular or square cross-section, for example, and comprises a plurality of openings <NUM>. According to one embodiment falling within the scope of the present invention, the plurality of openings <NUM> are distributed over the plane of the first layer <NUM> in a regular pattern. This, however, is only an example. The plurality of openings <NUM> can be distributed over the plane of the first layer <NUM> in any suitable way. One of the openings <NUM> is schematically illustrated in the cross-sectional view on the right side of <FIG>. The first layer <NUM> can be formed in any suitable way such as, e.g., injection molding.

According to one embodiment falling within the scope of the present invention, the first layer <NUM> remains in the mold and the second layer <NUM> is formed directly on the first layer <NUM> in the same mold. The step of forming the second layer <NUM> is schematically illustrated in <FIG>. The second layer <NUM> is formed to comprise a plurality of protrusions, wherein each of the protrusions extends into one of the plurality of openings <NUM>. This is schematically illustrated in the cross-sectional view on the right side of <FIG>. This method can be used, for example, if the second layer <NUM> is formed according to the examples described by means of <FIG> and <FIG> above.

According to another embodiment falling within the scope of the present invention, the second layer <NUM> is formed separately, e.g., in a separate mold. The second layer <NUM> is removed from the mold and the first layer <NUM> and the second layer <NUM> are then assembled. That is, the second layer <NUM> is placed on the first layer <NUM> such that the protrusions of the second layer <NUM> protrude into the openings <NUM> of the first layer <NUM>. This method can be used, for example, if the second layer <NUM> is formed according to the example described by means of <FIG> above.

Claim 1:
A housing (<NUM>) for a power semiconductor module arrangement (<NUM>) comprises sidewalls and a lid, wherein the lid comprises:
a first layer (<NUM>) of a first material comprising a plurality of openings (<NUM>); and
a second layer (<NUM>) of a second material that is different from the first material, wherein
the second layer (<NUM>) completely covers a bottom surface of the first layer (<NUM>), and
the second layer (<NUM>) comprises a plurality of protrusions, each protrusion extending into a different one of the plurality of openings (<NUM>) of the first layer (<NUM>) such that each of the plurality of openings (<NUM>) is completely covered by one of the protrusions, wherein
each protrusion of the second layer (<NUM>) forms a membrane (<NUM>), each membrane covering one of the openings (<NUM>) of the first layer (<NUM>), thereby sealing the openings (<NUM>) of the first layer (<NUM>) to prevent air, moisture and corrosive gases from entering the inside of the housing (<NUM>), and
each membrane (<NUM>) is configured to allow a terminal element (<NUM>) to easily penetrate through the membrane (<NUM>) when inserting a terminal element (<NUM>) through the opening (<NUM>).