Power semiconductor module and method to manufacture a power semiconductor module

Abstract

The invention relates to a power semiconductor module (1) comprising a module housing (50) with an alignment element (52); and a substrate structure (10) with a plate-shape, a top side (12), a top metallization layer (30) arranged on the top side, a power semiconductor device (18) arranged on the top side (12) and electrically connected to the top metallization layer (30) and a recessed feature (20) arranged on the top side (12), which substrate structure (10) is fastened to the module housing (50) to accommodate the power semiconductor device (18); wherein the alignment element (52) penetrates from the top side (12) into and / or through the recessed feature (20) thereby providing a mechanical engagement between the module housing (50) and the substrate structure (10) with respect to a movement towards at least one direction in a plane (P) along the top side (12).

Description

[0001] Description

[0002] Power semiconductor module and method to manufacture a power semiconductor module

[0003] Technical Field

[0004] The invention relates to a power semiconductor module comprising a module housing and a substrate structure with a plate-shape, a top side, a top metallization layer and a power semiconductor device, which substrate structure is fastened to the module housing and which power semiconductor device is electrically connected to the top metallization layer. The invention also relates to a method to manufacture a power semiconductor module.

[0005] Background Art

[0006] Substrate structures for power semiconductor modules typically have a plate-shape, where an outer edge of the substrate structure is used for positioning the module housing relative to the substrate structure by means of fitting portions extending separate from a surface of the module housing that abuts with the substrate structure top side. Said fitting portions fit to the outer edge and realize the positioning substantially in parallel to the substrate structure. Said fitting portions may be formed as snapfit portions to also realize a mechanical coupling, e.g. by means of a snapmechanism, perpendicular to the substrate structure

[0007] Such alignment structures, e.g. the fitting portions, are typically protruding structures on the bottom surface of the housing frame, which extend downwards and at least partially touch the outer edge of the baseplate.

[0008] The manufacturing process for a baseplate and a module housing where the outer edge is used for the above-described positioning is complicated. For example, the substrate structure may have geometric features such as recesses at its outer edge. The substrate structure may have a shape which deviates from a simple rectangular shape (e.g. a dogbone shape). This makes separate machining steps or more complicated forming tools necessary and reduces the available area of the power module. Such geometric features reduce the heat dissipation capability of the substrate structure. The manufacture for a module housing with fitting portions, e.g. snapfit portions, or other alignment structures is also costly.

[0009] Summary of invention

[0010] It is therefore an object of the invention to provide a power module and a manufacturing method thereof where the positioning of the substrate structure relative to the module housing is enhanced particularly at lower cost. Particularly it is an object to avoid or reduce disadvantages of known solutions.

[0011] The object of the invention is solved by the features of the independent claims. Preferred implementations are detailed in the dependent claims.

[0012] Thus, the object is particularly solved by a power semiconductor module comprising a module housing with an alignment element; and a substrate structure with a plate-shape, a top side, a top metallization layer arranged on / at the top side, a power semiconductor device arranged, particularly fastened, and particularly electrically connected to the top metallization layer, e.g. soldered, on / at the top side of the substrate structure and a recessed feature arranged, particularly formed, on the top side, which substrate structure is fastened to the module housing to accommodate the power semiconductor device; wherein the alignment element is arranged to penetrate and / or penetrates from the top side into and / or through the recessed feature, wherein thereby, particularly by means of the penetration of the alignment element, a mechanical engagement, particularly a positive mechanical engagement and / or a positive fit and / or form fit, between the module housing and the substrate structure at least with respect to a movement in a plane along the top side is provided, which movement particularly pertains to at least one direction or more than one direction which are oblique to each other and / or contained in the plane.

[0013] The object is further solved by a method to manufacture a power semiconductor module or the power semiconductor module as named above, wherein a module housing having an alignment element and a substrate structure with a plate-shape, a top side, a top metallization layer arranged on the top side of the substrate structure, a power semiconductor device arranged, particularly fastened, and particularly electrically connected to the top metallization layer, e.g. soldered, on a top side of the substrate structure and a recessed feature arranged, particularly formed, on the top side are provided, which module housing is designed to accommodate the power semiconductor device, comprising the steps of

[0014] - placing the module housing on the top side wherein the alignment element penetrates the recessed feature from the top side in order to position the module housing relative to the substrate structure along a plane along the top side; and

[0015] - fastening the substrate structure to the module housing by means of bonding and / or screwing.

[0016] The proposed solution is based on the idea that the positioning between substrate structure and module housing can be realized via the recessed feature of the substrate structure that can be penetrated by the alignment element of the module housing. The idea essentially contains that the recessed feature is meant to be penetrated. This could mean that the recessed feature is located somewhere in the middle of the substrate structure as a blind hole or a pocket which can lock the alignment element at least one direction, in a plurality of obliquely arranged directions in the plane, or in all directions in parallel to the substrate structure I the plane. It is especially preferred that the recessed feature (for the alignment element) is formed by means of an isolation groove between / within (a) metallization pattern(s) of the top metallization layer. Particularly in order to allow for the recessed feature to be penetrated into / through, the recessed feature cannot be located at or on an outer edge of the substrate structure. It is an option that the recessed feature is located laterally distant to the power semiconductor device, e.g. to be also accommodated when the module housing is closed.

[0017] Particularly, the present invention provides that a typically, particularly partially and / or at least substantially, plate-shaped substrate structure having at least one power semiconductor device can be positioned easily relative to a module housing upon attaching the module housing to the substrate structure. An alignment element e.g. protruding in the inside of the module housing fits in to a recessed feature in the substrate structure and realizes a positioning in a direction in parallel to the extension of the substrate structure. The recessed feature is particularly located surrounded on all sides by the outer edge of the plate-shaped substrate structure to be accommodated in and / or covered by the module housing. In other words, the recessed feature particularly is substantially located somewhere on an upper surface of the substrate structure and / or not at the outer edge of the substrate structure.

[0018] Particularly, the top metallization layer may form the recessed feature. Particularly, the recessed feature in the sense of the present invention may not be formed in the power semiconductor device, e.g. a chip, and / or may not be formed in a / the bottom plate. As an alternative it may be that the recessed feature is formed in the power semiconductor device.

[0019] The idea of the invention particularly is that a topography on one side (e.g. the top side) of the substrate structure, particularly the topography meant for electrical interconnection of the power semiconductor device, is used for positioning the module housing relative to the substrate structure.

[0020] The present invention provides a solution which enables a very precise positioning between module housing and substrate structure so that the power semiconductor device can be accommodated and electrically used at very little risk of producing scrap.

[0021] By means of the invention and by means of aspects described in the present application, and enhanced power semiconductor module is provided that can be produced / manufactured more easily.

[0022] Further advantageous implementations of the invention are given as follows. The features named in the implementations may be individually combined with each other or considered alone. The features may be considered in the method and / or in the power semiconductor module. The power semiconductor module is, for example, meant to be a power module in a vehicle to convert direct current from a battery to alternating current for an electric motor, for example, in hybrid vehicles or plug-in electric vehicles, or in a train like a commuter train.

[0023] The module housing at least substantially may have an interior to accommodate the power semiconductor device. The module housing may have at least one side wall and / or an upper cover. The upper cover is meant to be located opposite the substrate structure. Thereby, a closable space for the top side and / or the power semiconductor devices may be provided. When the substrate structure is placed and / or fastened to the module housing facing with the top side the module housing, the power semiconductor device(s) can be accommodated, particularly located and / or protected inside the module housing.

[0024] The module housing may particularly serve to accommodate the alignment element. The alignment element may face and / or may be in contact to the top metallization layer and may be coupled at the module housing opposite the substrate structure for the positioning, wherein 'coupled' may include to be formed integrally with the module housing or connected to the housing as a separate part. The alignment element may particularly not face and / or may not be in contact to an outer border of the substrate structure, but especially rather be located in the module housing.

[0025] Plate-shape means that a shape is flat and at least substantially extends towards two of three dimensions. A plate may be flat in one direction but substantially elongated in two directions, while all three directions are perpendicular to each other. Particularly, each of a width and a length of a plate is at least by a factor of 2, 5, 10, 50, 100 or more larger than a thickness in order to be considered having a plate-shape. A plate-shape may still contain an uneven topography on the top side and / or the bottom side of the substrate structure, e.g. the side including power semiconductor devices, insulation grooves, chips, wires and the like.

[0026] It is understood that the substrate structure has a plate-shape when a typically substantial part of the substrate structure, e.g. base plate / bottom plate or insulation layer, has a plate-shape. A substantial part preferably is considered as a part that makes up for at least 10 % of the weight and / or volume of the substrate structure, which typically is true for one or both of base plate I bottom plate and insulation layer. Particularly, it is most preferred that the insulation layer and / or a / the bottom plate has a plate-shape and / or is at least substantially plate-shaped.

[0027] It is noted that the metallization layer(s) and / or the metallization pattern(s) may be considered plate-shaped.

[0028] 'To penetrate' means that the alignment element enters into / through, makes its way into / through and / or pierces the substrate structure. It is substantially understood that the alignment element at least in part is located inside and / or in and / or somewhere in the middle of and / or somewhere on an upper surface of the substrate structure. It is particularly not sufficient for a penetration to merely face and / or to merely be in contact to the substrate structure, e.g. at the outer edge. Particularly, the substrate structure must particularly at least sectionally and / or from one, two or more sides surround the alignment element. Particularly, penetration may include that the alignment element is in contact to the substrate structure.

[0029] The plane extends substantially along the top side and / or along the dominant extensions of the substrate structure. For example, the plane extends in parallel to any layer, e.g. metallization layer, insulation layer, and / or to any plate, e.g. bottom plate / base plate / bottom metal plate, particularly those of the substrate structure.

[0030] The top side may not have an entirely flat surface and particularly exhibits a specific topography e.g. due to insulation grooves, power conductor devices and / or other features. The top side pertains to substantially one side of the substrate structure e.g. including top metallization layer and chips , wherein the bottom side pertains to substantially another side of the substrate structure e.g. for placement of the entire power semiconductor module, e.g. for heat transfer and the like.

[0031] In a first preferred implementation the substrate structure has an insulation layer with the top metallization layer, and optionally with a bottom metallization layer opposite the top metallization layer. The insulation layer may comprise for electrical insulation a ceramic material and / or a resin sheet typically filled with inorganic particles or fibers. The insulation layer is typically a dielectric layer, e.g. made of a flexible or of a solid material. The top metallization layer and / or the bottom metallization layer particularly comprises or consists of copper. The substrate structure may have the insulation layer with the top metallization layer at the top side and with a bottom metallization layer at the bottom side of the substrate structure. The insulation layer may be a ceramic layer, e.g. comprising at least one type of a ceramic and / or an oxide, for example aluminum oxide. The top metallization layer and / or the bottom metallization layer may be a layer attached to and / or coated on the insulation layer. The insulation layer and the metallization layers may be attached to one another, e.g. to form a structural unit. At least one or both of the metallization layers comprise / s copper, aluminum, or an alloy therewith. One or both of the metallization layers may be applied and / or generated directly on the insulation layer. The insulation layer may provide structural integrity to the substrate structure, the top metallization layer may provide electrical interconnection of at least the power semiconductor devices, and / or the bottom metallization layer may provide heat radiation or dissipation means. In some specific power semiconductor module designs, the bottom metallization layer may provide electrical interconnection.

[0032] The top and / or bottom metallization layer may comprise or be a copper and / or or aluminum or a corresponding alloy. The top and / or bottom metallization layer may have a coating, e.g. a nickel coating for improved corrosion resistance, improved electrical properties, improved bonding properties and / or reduced cost.

[0033] In another implementation the substrate structure has a bottom plate at a bottom side opposite the top side, optionally with the bottom plate coupled (e.g. directly or indirectly) to the insulation layer, preferably coupled (indirectly) via the bottom metallization layer and / or (directly) with the bottom metallization layer in between, and optionally wherein the bottom plate comprises metal or metal composite material, e.g. AlSiC, MgSiC, aluminum, copper, steel and / or other metals or alloys. Particularly, the bottom plate may comprise metal within an alloy and / or within a composite material, particularly AlSiC and / or MgSiC. The bottom plate may be understood or generally referred to as a base plate or heat sink, e.g. to serve as a base for the power semiconductor module. The bottom plate typically differentiates from the layers (e.g. metallization and / or insulation) particularly by its thickness being preferably above 2 mm or 3 mm and / or below 6 mm or 5 mm, wherein the layers typically exhibit a thickness lower than that. The bottom plate differentiates from the layers (e.g. metallization and / or insulation) particularly by its material preferably comprising by more than 2 wt.-% aluminum, steel, carbon, silicium and / or other materials, wherein the layers may exhibit different materials. It may be that the bottom plate is of the same material as the bottom metallization layer. It is an option that the bottom plate is of a different material relative to the bottom metallization layer. The bottom plate may exhibit a plate shape in that it has a solid and flat structure which extends substantially within / along a / the plane. For example, the bottom plate may comprise a bow, a bump and / or a dent but however is substantially plate-shaped.

[0034] The base plate and / or bottom plate may be soldered and / or bonded and / or coupled to the insulation layer preferably via the bottom metallization layer. The substrate structure may therefore comprise the insulation layer with the top metallization layer at the top side and with the bottom plate at the bottom side of the substrate structure. The insulation layer may be directly bonded and / or laminated on the bottom plate to provide an insulated substrate, particularly insulated metal substrate. The insulation layer may be a polymer layer, e.g. comprising at least one type of a polymer, particularly a polymer compound, a resin, a polymer compound layer, a resin layer and / or a resin sheet, typically filled with inorganic particles or fibers. The bottom plate may provide heat radiation or dissipation means as well as a mounting capability, e.g. to a cooling means.

[0035] The substrate structure can be provided with the bottom metallization layer and / or the bottom plate on its lower side especially in order for thermally connecting the substrate structure to a cooler.

[0036] The power semiconductor device may be electrically connected to the top metallization layer. At least one contact area may be provided for externally contacting the power semiconductor module, particularly the power semiconductor device, particularly by means of one or more respective terminals or connectors, such as terminal pads. The terminal or connectors may be metallization areas, which may be used for mounting of external terminals; such pattern may be electrically connected with the power semiconductor device(s). It may be provided that the top metallization layer has one or more than one power semiconductor device and may further comprise one or more than one contact area.

[0037] The top metallization layer may provide multiple patterns for mounting of power semiconductor devices and / or other electronic devices such as sensors, control devices, and / or passive devices and / or for main and auxiliary terminals, particularly external terminals for external connection. Patterns of the top metallization layer for mounting of terminals may be electrically connected with the power semiconductor devices or other devices or with other patterns of the top metallization.

[0038] The power semiconductor device may be in the form of a chip. More than one power semiconductor device may be provided in the power semiconductor module. It may be provided that as the power semiconductor device(s) one or more of a transistor, and / or switching device is provided, such as insulated-gate bipolar transistor (IGBT) device, metal oxide semiconductor field-effect transistor (MOSFET), diode, and / or the like.

[0039] The power semiconductor devices can be mounted on the same substrate structure or on several substrate structures for the module housing, e.g. on the substrate structure and on another substrate structure. It is also possible, that there is a common bottom plate, where several setups comprising or consisting of: bottom metallization layer, insulation layer, and top metallization layer, are arranged, e.g. mounted.

[0040] All the power semiconductor devices can be of the same type, or there are at least two different types of power semiconductor devices, like diodes and / or transistors. The power semiconductor device may be selected from the group comprising or consisting of a metal-oxide-sem iconductor field-effect transistor, MOSFET for short, a metal-insulator-semiconductor field-effect transistor, MISFET for short, an insulated-gate bipolar transistor, IGBT for short, a bipolar junction transistor, BJT for short, a gate turn-off thyristor, GTO for short, a gate commutated thyristor, GCT for short, a junction gate field-effect transistor, JFET for short, a high electron mobility transistor, HEMT for short, and a diode. If there is a plurality of the power semiconductor device, all the power semiconductor devices can be of the same type, or there are different types of power semiconductor devices.

[0041] The term 'power semiconductor module' means, for example, that the module is configured for high currents. For example, the power semiconductor module is configured to handle a current of at least 10 A or of at least 50 A or of at least 100 A or of at least 500 A. Correspondingly, the power semiconductor device may be high-power device, particularly a high-power chip.

[0042] The metallization layer may be in direct contact with the insulation layer. The insulation layer may be the only layer between the top metallization layer and the bottom metallization layer and / or the bottom plate. The insulation layer may be the only layer between the top metallization layer and the bottom plate.

[0043] The insulation layer may comprise one or a plurality of ceramic layers. For example, the ceramic layer may comprise an AIN, SiSNi, AI2O3, BN, or a resin material filled with particles or fibers of inorganic material. The insulation layer may comprise or consist of at least one isolating resin sheet. The insulation layer may be filled with an inorganic filler like inorganic particles. The at least one inorganic filler can be a ceramic material like AIN, AI2O3, Si3N4, or BN.

[0044] The substrate structure provides an electrical contact platform for one, for some or for all of the power semiconductor device(s).

[0045] In another preferred implementation the substrate structure is fastened to the module housing, preferably by means of a contact surface or at least one section thereof, and / or with the contact surface being in direct contact to the module housing. The contact surface is particularly part of and / or formed with the bottom plate and / or any layer, such as the insulation layer. The contact surface is typically circumferential, mainly / substantially to the top metallization layer. Alternatively or additionally, the module housing may comprise a contact surface, particularly with the contact surfaces of module housing and substrate structure corresponding to each other. Fastening may be realized by means of bonding, e.g. using adhesive, and / or by means of screwing, e.g. screws screwed into the module housing, and / or by means of clamping, e.g. using clamps to clamp the module housing and / or the substrate structure. Bonding may be realized through a particularly circumferential and / or annular contact surface of the module housing abutting with the contact surface of the substrate structure (as above) of the substrate structure at the top side, particularly the contact surface(s) surrounding the power semiconductor device(s) and / or the alignment element(s). The contact surface(s) may be located on one side of the module housing and / or at the front of the side walls of the housing and / or at the side opposite the upper cover of the module housing which is meant to face the substrate structure. The contact surface(s) may be in a contact plane that limits the extension of the module housing particularly including the alignment element on one side of the module housing. Screwing may be realized by means of screws screwed from the bottom side and / or the top side, particularly perpendicular to the plane, particularly through the plane. The substrate structure, e.g. the bottom plate, can be screwed to the module housing from the bottom side opposite the top side in order to couple the entire substrate structure to the housing. Screws can as well be screwed from the top side through the module housing into the substrate structure. Threads or threaded nuts / structures may be located in the substrate structure and / or the module housing for screwing. Self-cutting screws may however be used for screwing.

[0046] In another preferred implementation the top metallization layer has a thickness of at least 0.25 mm, 0.5 mm, 0,75 mm, 1 mm or more. The thickness of the top metallization layer may be up to 5 mm, 4 mm, 3 mm, 2 mm, or less. The top metallization layer may be deposited in a coating process, a lamination process and / or a brazing process. The thickness may be a nominal thickness of the metallization layer considered directly after its (raw) manufacture.

[0047] In another preferred implementation the top metallization layer has an isolation groove to form individual electrically conducting sections of the top metallization layer and / or at least one electrical circuit, particularly at least substantially comprising the same thickness. More than one isolation groove may be provided. The isolation groove and / or the individual electrically conducting sections may be understood as a topography of the substrate structure and thus may at least in part from the recessed feature. Preferably above the top metallization layer, particularly in individual electrical connection to the electrically conducting sections, particularly above and in contact to the top metallization layer, the power semiconductor device(s) is / are located. It may be that on the top metallization layer another substrate structure is provided, for example the another substrate structure being at least substantially smaller than the substrate structure. The another substrate may be an auxiliary substrate, where gate resistors or control devices are located. Optionally, main and / or auxiliary terminals may be located on the top metallization layer. The top metallization layer can thus be provided in order to form an electrical circuit, for example by the provision of respective conductors formed by means of the topography and / or shape along the top side of the top metallization layer itself.

[0048] A plurality of the recessed feature may be provided. A plurality of the alignment element may be provided. The plurality of the recessed feature or the recessed feature may correspond to the plurality of the alignment element or the alignment elements. The recessed features may be arranged at a distance to each other along the plane. The alignment elements may be arranged at a distance to each other along the plane.

[0049] The isolation groove may at least partially form the recessed feature or the plurality thereof for the alignment element or the plurality thereof. Particularly, the isolation groove may have a depth of 0.25 mm, 0.5 mm or more for a good stability. The recessed feature may be integrated in the substrate structure in order to synergistically use the isolation groove for both electrical isolation and positioning of the module housing. When the alignment element thus penetrates the isolation groove, the likeliness of creep currents via the isolation groove even reduces. At the position of the alignment element, the creep distance is even beneficially blocked.

[0050] In another preferred implementation the recessed feature is surrounded in the plane, particularly in the top metallization layer, sectionally or fully by the top metallization layer, particularly with a radial size starting from the border of the recessed feature of at least 1 mm. The recessed feature may be a local reduction in thickness of the top metallization layer, e.g. a blind hole and / or a recess. The recessed feature may be a bore and / or hole through the metallization layer. The recessed feature may be encircled in full or at least in a section by the metallization layer. Thus, the mechanical stability of the recessed feature is increased. The recessed feature can be provided and / or formed directly by means of the metallization layer and / or manufactured therewith.

[0051] The alignment element may be in the form of a protrusion, e.g. protruding oblique and / or perpendicular to the plane, particularly from the module housing. The alignment element may protrude and / or extend and / or be located in an interior the module housing. The alignment element may have the shape of a pin.

[0052] In another preferred implementation the alignment element penetrates, particularly into and / or through, the top metallization layer. The alignment element particularly penetrates, preferably into and / or through, the insulation layer, e.g. the resin sheet and / or the ceramic material. The alignment element may penetrate, preferably into and / or through, the bottom metallization layer and / or the bottom plate. The recessed feature may be a blind hole starting at the top side and ending somewhere in any section of the substrate structure, e.g. in the top metallization layer, the insulation layer and / or the bottom metallization layer and / or the bottom plate. The recessed feature may be a hole through the substrate structure, e.g. starting at the top side and ending at the opposite side, i.e. the bottom side.

[0053] In another preferred implementation a front of the alignment element is arranged at a distance to or is in contact to the substrate structure, particularly with the distance considered in a direction perpendicular to the plane. The alignment element may be arranged to be placed at a distance, e.g. a minimal distance to provide a gap, to or to be in contact to the substrate structure particularly when the power semiconductor module is assembled. The alignment element may thus stop at a certain way of travel perpendicular and / or oblique to the plane. The alignment element may as well merely project into the recessed feature without stopping.

[0054] The front of the alignment element, e.g. the side of the alignment element facing the substrate structure, may be designed to be in contact to the substrate structure on at least one lateral side of the front. The alignment element may serve to be in contact at least on one side, e.g. one side of its tip and / or front, for the positioning. The alignment element may as well be in contact to the recessed feature, i.e. the geometry of the substrate structure delimiting the recessed feature, in a circumferential manner, e.g. partially or fully. The front may be understood as a frontal portion of the alignment element and / or a frontal surface thereof.

[0055] In another preferred implementation the alignment element is formed integral to the module housing and / or is made of the same material as the module housing. To be integral, the alignment element may be bonded at / to the module housing and / or may be formed monolithically therewith. Especially when the module housing is made of a particularly fiber-reinforced polymer compound e.g. manufactured by means of injection molding or transfer molding, the alignment element(s) may be formed together with making the entire module housing. The alignment element may be produced together with the module housing by means of injection molding and / or transfer molding.

[0056] In another preferred implementation the alignment element is formed separate from the module housing and / or is of a material different to the module housing. In specific case, the alignment element may be made of a metal (e.g. when the recessed feature is electrically insulated and / or arranged at a distance to electrical circuits; and / or when the alignment element is inserted to a recessed feature that is not part of an isolating groove and mounted to an isolating housing.) and / or of a polymer compound. The alignment element may be attached to the module housing. The alignment element may be a part separate to both substrate structure and module housing and / or may be placed between module housing and substrate structure.

[0057] In another preferred implementation the alignment element has a round, polygonal, triangular, rectangular, square and / or prismatic shape in sectional view. The shape may be present at least at its front or at at least 10 %, 25 %, 50 % or 75 % of its length considered perpendicular to the plane. The shape may fit to the insulation groove and / or to other available recesses of the substrate structure. The insulation groove may have a shape at least in part corresponding to the shape of the alignment element, particularly the front of the alignment element.

[0058] The front of the alignment element may be at least substantially flat and / or may at least substantially run in parallel to the plane. The alignment element may be of an elongated shape in a direction at least substantially perpendicular to the plane.

[0059] In another preferred implementation the alignment element and / or the recessed feature has / have a size / diameter along and / or in parallel to the plane of at least 0.7 mm. This is beneficial to mechanical stability and the precision of the positioning.

[0060] The alignment element may have a length of at least 1.0 mm, e.g. protruding from an / the upper cover of the module housing towards the substrate structure and / or located between the side walls of the module housing and / or located in an interior of the module housing.

[0061] The alignment element, particularly its front / tip and / or its circumference, may be shaped corresponding to an isolation pattern at the top side and / or the isolation groove and / or the bottom metallization layer. The isolation groove or a plurality thereof may form the isolation pattern.

[0062] The alignment element and the recessed feature may at least substantially exhibit the same size in the plane, e.g. by ± 1 %, ± 2,5 %, ± 5 % or ± 10 %, particularly considered in a direction in parallel to the plane, more particularly the direction including the alignment element to be in contact to the recessed feature for the positioning. The size may be considered as a radial size. This on the one hand allows easy positioning at acceptable tolerance but on the other hand provides a very reliable positioning means.

[0063] In another preferred implementation an outer edge of the substrate structure is not in touch with the module housing, e.g. a fitting portion thereof, particularly the fitting porting comprising a snap-fitting feature and / or being in the form of a snapfit portion. It may be that the substrate structure is in a side view not covered. Particularly, the module housing, e.g. a fitting portion or a protruding edge thereof, does not cover the substrate structure and / or is not in contact thereto in the side view. Particularly, the substrate structure is not covered on all sides and / or considered from a plurality of or from all possible side views. It is particularly omitted that the module housing has elements protruding further than the surface abutting with the substrate structure, such as fitting portions, particularly the fitting portions to grasp and / or cover the outer edge of the substrate structure. It may be that no part or section of the module housing is designed to surpass the outer edge of the substrate structure, particularly not for the positioning.

[0064] In another preferred implementation the substrate structure is fastened by means of bonding, e.g. using adhesive, and / or by means of screwing, e.g. screws screwed into the module housing, wherein during the fastening, e.g. applying or hardening of adhesive and / or screwing in screws, the alignment element penetrates the recessed feature serves to position the module housing relative to the substrate structure along the plane.

[0065] In another preferred implementation the alignment element serves as a strut configured to brace an / the upper cover of the module housing against the substrate structure. Thus, the alignment element may be in contact to and / or coupled to the upper cover on one side and the substrate structure on the other side particularly considered in a direction oblique or perpendicular to the plane. This enhances the overall mechanical stability of the power semiconductor module and may enable to reduce cost due to a possibility for reconstruction of the module housing. Thus, the alignment element may provide an alignment function and a support function. The alignment element provides improved stability.

[0066] Brief description of drawings

[0067] These and other aspects of the invention will be apparent from and elucidated with reference to the implementations described hereinafter.

[0068] In the drawings: Fig. 1 shows a schematic cross-section of a power semiconductor module where an alignment element penetrates into a recessed feature;

[0069] Fig. 2 shows a schematic cross-section of a power semiconductor module where an alignment element penetrates through a recessed feature;

[0070] Fig. 3 shows a schematic cross-section of a power semiconductor module with a substrate structure and power semiconductor devices on a top side where an alignment element provides a positive fit for the module housing relative to the substrate structure; and

[0071] Fig. 4 shows a power semiconductor module in a perspective view.

[0072] Description of implementations

[0073] The description contains procedural or methodical aspects upon describing structural features of the power semiconductor module; the structural features can be understood well in that way. It is emphasized to the reader that such structural features can be lifted from the described context without hesitation or the question of an intermediate generalization to form aspects of the invention. It is also emphasized to the reader that any the structural features described in the following can be understood as individual aspects of the invention to distinguish from known solutions, despite being possibly lifted from the context.

[0074] In each of Fig. 1 and Fig. 2 a power semiconductor module 1 comprising a module housing 50 with an alignment element 52 and a plate-shaped substrate structure 10 is shown. The top surface of the substrate structure 10 at least substantially defines a plane P.

[0075] The power semiconductor module 1 , particularly its substrate structure 10, has power semiconductor devices 18 in the form of chips which are however not visible in the shown section of Fig. 1 or Fig. 2. The power semiconductor devices 18 are arranged and attached at a top side 12 and electrically connected thereto. Opposite the top side 12 is a bottom side 14. In both of Fig. 1 and Fig. 2, the substrate structure 10 is fastened to the module housing 50 (or vice versa) by means of screwing and / or bonding. The fastening substantially is provided at the top side 12, particularly at the sides and / or close to an outer edge of the substrate structure 10. This provides that the top side 12 is at least substantially accommodated. Particularly, the semiconductor devices 18 are accommodated.

[0076] In both of Fig. 1 and Fig. 2, the alignment element 52 serves to position the module housing 50 relative to the substrate structure 10 along the plane P by means of a mechanical engagement and / or positive fit. In the shown arrangements, the alignment element 52 stops in the recessed features 20 when moving along the plane P to the right and to the left direction.

[0077] Towards and from the plane of the Figs. 1 and 2, i.e. oblique or vertically or perpendicular to the plane P, the alignment element 52 may move in the case - as here - the recessed feature 20 is formed by an insulating groove 24 running in said direction. Particularly, the alignment element 52 may be movable along an extension of the insulating groove 24 along the plane P, and the alignment element 52 may have the proposed mechanical engagement oblique said extension, e.g. in the left or right direction in Fig. 1 and Fig. 2.

[0078] In Fig. 1 , the alignment element 52 is formed separate from the module housing 50 and removably connected to the module housing 50. The alignment element 52 and the module housing 50 are each made from at least one polymer compound, e.g. the same or different ones.

[0079] In Fig. 2, the alignment element 52 is formed integral to the module housing 50. The alignment element 52 and the module housing 50 are each made from a certain polymer compound as an injection molded part.

[0080] In both Fig. 1 and Fig. 2, the substrate structure 10 has a top metallization layer 30 containing copper, an insulation layer 32 made of insulating material (such as a ceramic material or a resin sheet or a polymer compound) and a bottom metallization layer 34 opposite the top metallization layer 30 containing copper. The layers 30, 34 are laminated, joined or coated on both sides of the insulation layer 32 and thus are mechanically coupled thereto.

[0081] In Fig. 1 , the substrate structure 10 has only in the top metallization layer 30 a recessed feature 20 formed that extends in depth 22 through the top metallization 30 layer along its thickness 31 of at least 0.5 mm and which has a size 21 as a diameter which is 5 % to 10 % larger than a size 52 as a diameter of the alignment element 52 protruding at and / or towards the top side 12. A length 56 of the alignment element 52 is at least 1 mm.

[0082] In Fig. 2, the substrate structure 10 has a recessed feature 20 formed which extends in depth 22 through the entire substrate structure 10. The recessed feature 20 particularly extends in depth through the layers 30, 32, 34 which exhibit the thicknesses 31 , 33, 35. The recessed feature 20 has a size 21 as a diameter which is at least substantially the same as the size 53 as a diameter of the alignment element 52 protruding at and / or towards the top side 12. Particularly the recessed feature 20 is at least 1 % or more larger than the alignment element 52, particularly in length oblique or perpendicular to the plane P. A length 56 of the alignment element 52 is at least 1 mm.

[0083] In both Fig. 1 and Fig. 2, the alignment element 52 penetrates into the recessed feature 20 while in Fig. 2 the alignment element 52 penetrates even through the recessed feature 20 and thus essentially through the substrate structure 10.

[0084] In Fig. 1 the front 54 of the alignment element 52 does not touch the bottom of the recessed feature 20 and / or is arranged at a distance to the substrate structure 20, e.g. the bottom of the recessed feature 20; however, it may be that the alignment element 52 touches the bottom of the recessed feature 20 upon pushing the module housing 50 further towards the substrate structure 10. Optionally, the recessed feature 20 is in the form of a bore and / or a blind hole and / or a groove. In Fig. 1 , the insulation layer 32 represents the bottom of the recessed feature 20. In Fig. 2 the front 54 of the alignment element 52 is located at the bottom side of the substrate structure 10. In Fig. 2, the recessed feature 20 is at least in a section in the form of a through bore and / or a through hole. An upper section of the recessed feature 20 is located in an isolation groove 24 of the top metallization layer 30.

[0085] In Fig. 1 and Fig. 2, the alignment element 52 is designed to be in contact to the substrate structure 10 on a lateral side 57 of the front 54. In Fig. 1 , the lateral side 57 is presently not in contact to the substrate structure 10. In Fig. 2, the lateral side 57 is presently in contact to the substrate structure 10.

[0086] Considering that the recessed feature 20 is a blind hole in Fig. 1 and with respect to the plane P, the recessed feature 20 is surrounded by the top metallization layer 30 in a full circle I fully, namely starting from the border of the recessed feature 20 by a radial size 26 of more than 1 mm.

[0087] Considering that the recessed feature 20 is a part of the isolation groove 24 that runs in parallel to the plane P in Fig. 2 and with respect to the plane P, the recessed feature 20 is at least partially surrounded by the top metallization layer 30 from at least two sides starting from the border of the recessed feature 20 by a radial size 26 of more than 1 mm.

[0088] In Fig. 2 the recessed feature 20 is at least in a section part of the isolation groove 24 which is designed to form individual electrically conducting sections of the top metallization layer 30. The isolation groove 24 at least partially forms the recessed feature 20.

[0089] Preferably, the alignment element 52 has a round, elongated shape. Nevertheless, other shapes are possible.

[0090] The front 54 of the alignment element 52 particularly is flat.

[0091] In Fig. 3 power semiconductor module 1 is shown in a section. The module 1 has a substrate structure 10 comprising at a bottom side 14 a bottom metallization layer 34 and at a top side 12 a top metallization layer 30. The metallization layers 30, 34 are attached at opposite sides 12, 14 to an insulation layer 32 e.g. as metallic coatings or laminates. The insulation layer 32 is especially for the purpose to schematically illustrate at least twice as thick as the metallization layers 30, 34.

[0092] Onto the substrate structure 10, e.g. onto the insulation layer 32, a module housing 50 is attached and / or fastened by means of bonding, possibly also to accommodate an another or auxiliary substrate structure, if present. Further, two power semiconductor devices 18 are supported on the top side 12.

[0093] The power semiconductor devices 18 are electrically connected to the top metallization layer 30, particularly by means of soldering or sintering. Between two of the semiconductor devices an insulation groove 24 may be located which may also serve as a recessed feature 20. The power semiconductor devices 18 are electrically connected to each other. Not shown are terminal pads to electrically contact the power semiconductor devices 18 with external terminals at the module housing 50.

[0094] The substrate structure 10 has isolation grooves 24 in the top metallization layer 30 which at least in part form and / or function as recessed features 20 and provide an isolation pattern, particularly to form individual electrically conduction sections of the top metallization layer 30. Two of the recessed features 20 are located in the top metallization layer 30 which is attached to the insulation layer 32 quite similar to that recessed feature 20 of Fig. 1 .

[0095] For the mere purpose of disclosing where recessed features 20 can be located, in Fig. 3 one of the recessed features 20 is located atop each one of the power semiconductor devices 18. Typically, a power semiconductor device 18 does not comprise the recessed feature 20 at its top side, and preferably has a flat top surface and / or no recesses at the top.

[0096] Not shown in Fig. 3 is that the recessed feature 20 is located in the insulation layer or in the bottom metallization layer 34, but this is an option as well. The recessed feature 20 which is penetrated by an alignment element 52 is located in the substrate structure 10, particularly only in the top metallization layer 30. Said recessed feature 20 extends perpendicular to the plane P at the top side 12 through the entire thickness 31 of the top metallization layer 30 and ends at the top of the insulation layer 32 that carries the top metallization layer 30. Particularly, the recessed feature 20 is part of an isolation groove 24 extending across the plane P but may as well be a blind hole.

[0097] The alignment element 52 has in a cross-section in parallel to the plane P a rectangular shape. The front 54 of the alignment element 52 is particularly flat to be in contact to the substrate structure 10, e.g. the insulation layer 32. A lateral side 57 of the front 54 is in contact to the top metallization layer 30 for a positioning along the plane P.

[0098] Fig. 4 shows a power semiconductor module 1 that is formed by means of a substrate structure 10 that is fastened at its top side 12 to a module housing 50. The substrate structure 10 comprises a partially shown bottom plate 36 on which (not shown) a bottom metallization layer 34, an insulation layer 32 and a top metallization layer 30 are arranged and / or fastened. Atop the top metallization layer 30 power semiconductor devices 18 are joined thereto (not shown). The not shown features are accommodated in the module housing 50. Terminal pads, electrical connectors or the like may serve to electrically connect the power semiconductor module 1 (not shown).

[0099] The module housing 50 has four side walls 62 and an upper cover 60 to substantially form the module housing 50 in shape. The side walls 62 and the upper cover 60 are formed together monolithically, e.g. from electrically insulating material.

[0100] Each of the side walls 62 has facing away from the upper cover 60 a contact surface. The upper cover 60 has the alignment element 52, particularly monolithically formed therewith.

[0101] The bottom plate 36 is in this case screwed to the module housing 50 from a bottom side 14 opposite the top side 12 in order to couple the entire substrate structure 10 to the housing 50 providing accommodation for the power semiconductor device(s) 18. The substrate structure 10 is furthermore bonded via two abutting annular contact surfaces 38 of both the bottom plate 36 and the module housing 50.

[0102] Additionally or alternatively, a glued connection of substrate structure 10 and module housing 50 is possible. Substrate structure 10 and module housing 50 may alternatively or additionally merely get in touch via a sealing.

[0103] The bottom plate 36 has a thickness 37 which larger than the top metallization layer 30 by factor of at least two, three, four or more.

[0104] In Fig. 4, atop the bottom plate 36 and inside the module housing 50 at least one top metallization layer 30 is attached to the bottom plate 36. The top metallization layer 30 is surrounded by the contact surface(s) 38. Additionally, a bottom metallization layer 34 and an insulation layer 32 are provided atop the bottom plate 36 and below the top metallization layer 30 and, similarly, inside the module housing 50.

[0105] In this embodiment, an outer edge 16 of the bottom plate 36 still has a dogbone shape due to four fitting recesses 17 placed on each of the four sides, particularly on the outer edge 16. The dogbone shape is typically used for the positioning by means of fitting portions of the module housing 50.

[0106] However, in this case the module housing 50 has no fitting portions to cover the outer edge 16. The outer edge 16 is not in touch with the module housing 50 and / or fitting portions thereof. The substrate structure 10 is in a side view not covered by the module housing 50 and / or fitting portions thereof. Thus, the fitting recesses 17 could be omitted to increase the surface at the bottom side 14 of the substrate structure in order to increase a cooling area.

[0107] In Fig. 4, the alignment element 52 serves as a strut configured to brace the upper cover 60 of the module housing 50 against the substrate structure 10. The alignment element 52 is inside coupled to the upper cover 60 on one side and to the substrate structure 19 on the other side via the recessed feature 20. When the module 1 of Fig. 4 was assembled, an alignment element 52 in the inside of the housing 50 penetrated at least partly the substrate structure 10 in order to position the housing 50 relative to the substrate structure 10 along a plane P along the substrate structure 10. This enabled as a product-by-process feature that the hardening of an adhesive for the bonding of the substrate structure 10 to the housing 50 and / or the screwing of screws was made easier and more accurate resulting in enhanced process reliability and less scrap production.

[0108] It is noted that aspects of the above described and shown embodiments may be combined.

[0109] Reference signs list

[0110] 1 Power semiconductor module

[0111] 10 substrate structure

[0112] 12 top side

[0113] 14 bottom side

[0114] 16 outer edge

[0115] 17 fitting recess

[0116] 18 power sem iconductor device

[0117] 20 recessed feature

[0118] 21 size, e.g. diameter

[0119] 22 depth

[0120] 24 isolation groove

[0121] 26 radial size

[0122] 30 top metallization layer

[0123] 31 thickness

[0124] 32 insulation layer

[0125] 33 thickness

[0126] 34 bottom metallization layer

[0127] 35 thickness

[0128] 36 bottom plate

[0129] 37 thickness

[0130] 38 contact surface

[0131] 50 module housing

[0132] 52 alignment element

[0133] 53 size, e.g. diameter

[0134] 54 front

[0135] 56 length

[0136] 57 lateral side

[0137] 60 upper cover

[0138] 62 side wall

[0139] P plane

Claims

Claims1. Power semiconductor module (1 ) comprising a module housing (50) with an alignment element (52); and a substrate structure (10) with a plate-shape, a top side (12), a top metallization layer (30) arranged on the top side, a power semiconductor device (18) arranged on the top side (12) and electrically connected to the top metallization layer (30) and a recessed feature (20) arranged on the top side (12), which substrate structure (10) is fastened to the module housing (50) to accommodate the power semiconductor device (18); wherein the alignment element (52) penetrates from the top side (12) into and / or through the recessed feature (20) thereby providing a mechanical engagement between the module housing (50) and the substrate structure (10) with respect to a movement towards at least one direction in a plane (P) along the top side (12).

2. Power semiconductor module (1 ) according to the preceding claim, wherein the substrate structure (10) has an insulation layer (32) with the top metallization layer (30), optionally with a bottom metallization layer (34) opposite the top metallization layer (30), particularly wherein the insulation layer (32) comprises for electrical insulation a ceramic material or a resin sheet, and particularly wherein the or at least one metallization layer (32, 34) comprises or consists of copper.

3. Power semiconductor module (1 ) according to any one of the preceding claims, wherein the substrate structure (10) has a bottom plate (36) at a bottom side (14) opposite the top side (12), optionally with the bottom plate (36) coupled to the insulation layer (32), preferably coupled via the bottom metallization layer (34), and optionally wherein the bottom plate (36) comprises metal, e.g within an alloy and / or within a composite material, particularly AlSiC and / or MgSiC.

4. Power semiconductor module (1 ) according to any one of the preceding two claims, wherein the substrate structure (10) is fastened to the module housing (50) by means of a contact surface (38) of the bottom plate (36) or the insulation layer (32) which contact surface (38) is circumferential to the top metallization layer (30).

5. Power semiconductor module (1 ) according to any one of the preceding claims, wherein the top metallization layer (30) has a thickness (31 ) of at least 0.5 mm.

6. Power semiconductor module (1 ) according to any of the preceding claims, wherein the top metallization layer (30) has an isolation groove (24) to form individual electrically conducting sections of the top metallization layer (30), wherein the isolation groove (24) at least partially forms the recessed feature (20) or a plurality of said recessed feature (20) for a plurality of said alignment element (52).

7. Power semiconductor module (1 ) according to any one of the preceding claims, wherein the recessed feature (20) is surrounded in the plane (P) sectionally or fully by the top metallization layer (30), particularly with a radial size (53) starting from the border of the recessed feature (20) of at least 1 mm.

8. Power semiconductor module (1 ) according to any one of the preceding claims, wherein the alignment element (52) penetrates the top metallization layer (30).

9. Power semiconductor module (1 ) according to any one of the preceding claims, wherein the alignment element (52) penetrates the insulation layer (32).

10. Power semiconductor module (1 ) according to any one of the preceding claims, wherein the alignment element (52) penetrates the bottom metallization layer (34).11 . Power semiconductor module (1 ) according to any one of the preceding claims, wherein the alignment element (52) penetrates the bottom plate (36).

12. Power semiconductor module (1 ) according to any of the preceding claims, wherein a front (54) of the alignment element (52) is arranged at a distance to or is in contact to the substrate structure (10), particularly the distance considered in a direction perpendicular to the plane (P).

13. Power semiconductor module (1 ) according to any one of the preceding claims, wherein a / the front (54) of the alignment element (52) is designed to be in contact to the substrate structure (10) on at least one lateral side of the front (54).

14. Power semiconductor module (1 ) according to any one of the preceding claims, wherein the alignment element (52) is formed integral to the module housing (50) and / or is made of the same material as the module housing (50).

15. Power semiconductor module (1 ) according to any one of the preceding claims, wherein the alignment element (52) is produced together with the module housing (50) by means of injection molding or transfer molding.

16. Power semiconductor module (1 ) according to any one of the preceding claims, wherein the alignment element (52) is formed separate from and / or is of a material different to the module housing (50)..

17. Power semiconductor module (1 ) according to any one of the preceding claims, wherein the alignment element (52) has a round, polygonal, triangular, rectangular, square and / or prismatic shape in cross-sectional view at least at its front (54).

18. Power semiconductor module (1 ) according to any one of the preceding claims, wherein a / the front (54) of the alignment element (52) is partially or fully flat.

19. Power semiconductor module (1 ) according to any one of the preceding claims, wherein the alignment element (52) is of an elongated shape in a direction substantially perpendicular to the plane (P).

20. Power semiconductor module (1 ) according to any one of the preceding claims, wherein the alignment element (52) and / or the recessed feature (20) has a size (21 , 53) along the plane (P) of at least 0.7 mm, and / or wherein the alignment element (52) has a length (56) of at least 1 .0 mm, and / or wherein the alignment element (52) and the recessed feature (20) at least substantially exhibit the same size (21 , 53) in the plane (P), e.g. by ± 5 %.21 . Power semiconductor module (1 ) according to any one of the preceding claims, wherein an outer edge (16) of the substrate structure (10) is not in touch with the module housing (50), e.g. a fitting portion thereof, and / or wherein the substratestructure (10) is in a side view not covered, particularly by the module housing (50), e.g. a fitting portion thereof.

22. Power semiconductor module (1 ) according to any one of the preceding claims, wherein the substrate structure (10) is fastened by means of bonding, e.g using adhesive, and / or by means of screwing, e.g. screws screwed into the module housing (50), wherein during the fastening, e.g. applying or hardening of adhesive and / or screwing in screws, the alignment element (52) penetrates the recessed feature (20) and thereby serves to position the module housing (50) relative to the substrate structure (10) along the plane (P).

23. Power semiconductor module (1 ) according to any one of the preceding claims, wherein the alignment element (52) serves as a strut configured to brace an upper cover (60) of the module housing (50) against the substrate structure (10).

24. Method to manufacture a power semiconductor module (1 ) or the power semiconductor module (1 ) according to any one of the preceding claims, wherein a module housing (50) having an alignment element (52) and a substrate structure (10) with a plate-shape, a top side (12), a top metallization layer (30) arranged on the top side (12), a power semiconductor device (18) arranged on the top side (12) and a recessed feature (20) arranged on the top side (12) are provided, which module housing (50) is designed to accommodate the power semiconductor device (18), comprising the steps of- placing the module housing (50) on the top side of the substrate structure (12) wherein the alignment element (52) penetrates the recessed feature (20) from the top side (12) in order to position the module housing (50) relative to the substrate structure (10) along a plane (P) along the top side (12); and- fastening the substrate structure (10) to the module housing (50) by means of bonding and / or screwing.

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