Semiconductor power module and method for manufacturing a semiconductor power module

Abstract

The semiconductor power module (1) comprises a metal substrate structure (10) having a metal top layer (11), a metal bottom layer (13), and a dielectric layer (12) therebetween. The semiconductor power module (1) further comprises a housing (2) having a top wall (21) and side walls (22) coupled to the metal substrate structure (10) such that a predetermined distance (D) exists between a bottom surface (24) of the top wall (21) adjacent to the side walls (22) and a top surface (14) of the metal top layer (11) in a stacking direction (A). The semiconductor power module (1) further comprises at least one terminal (16) arranged inside the housing (2), one of the at least one terminal (16) being coupled to the bottom surface (24) of the top wall (21) and the other of the at least one terminal (16) being coupled to the top surface (14) of the metal top layer (11). With respect to the stacking direction (A), the length of the at least one terminal (16) is configured in coordination with the distance (D) such that the at least one terminal (16) causes the metal substrate structure (10) to bend in a predetermined manner to include a convex shape that interacts with the housing (2) and the at least one terminal (16).

Description

[Technical Field]

[0001] The present disclosure relates to a semiconductor power module and a corresponding method for manufacturing the semiconductor power module. [Background technology]

[0002] Traditional insulated metal substrates form the technology for low- and medium-power semiconductor packages, which simultaneously have low insulation and low thermal resistance requirements. Coolers are used to dissipate heat, and contributing to efficient heat dissipation is a challenge. Summary of the Invention [Means for solving the problem]

[0003] Embodiments of the present disclosure can provide a semiconductor power module having an insulated metal substrate structure that enables efficient heat dissipation and reliable function even in high voltage power module applications. Further embodiments of the present disclosure can provide a method for manufacturing such a semiconductor power module.

[0004] According to one embodiment, a semiconductor power module includes an insulated metal substrate structure having a top metal layer, a bottom metal layer, and a dielectric layer. The dielectric layer is bonded to both the top metal layer and the bottom metal layer and disposed between them in the stacking direction of the metal substrate structure. The semiconductor power module further includes a housing configured to enclose electronics of the semiconductor power module. The electronics may include chips, particularly power semiconductor devices, integrated circuits, and / or other devices, such as discrete devices or sensors. The housing includes a top wall and a side wall and may be U-shaped or pot-shaped. The housing is bonded to the metal substrate structure, for example, by its side wall. The housing and the metal substrate structure are directly or indirectly bonded to each other such that a predetermined distance exists between the bottom surface of the top wall adjacent to the side wall and the top surface of the metal top layer in the stacking direction. The semiconductor power module further includes at least one terminal disposed inside the housing or between the housing and the metal substrate structure. One of the at least one terminals is bonded to the bottom surface of the top wall and the other is bonded to the top surface of the metal top layer. In the stacking direction, the at least one terminal has a length configured in coordination with the distance between the lower surface of the top wall adjacent to the side wall and the upper surface of the metal top layer, the length of the at least one terminal being configured such that the at least one terminal causes the metal substrate structure to bend in a predetermined manner and interact with the housing to provide a convex shape on its back surface.

[0005] The described configuration of the housing allows for a suitable thermal interface between the metal substrate structure and one or more terminals of the semiconductor power module, enabling efficient heat dissipation and reliable function even in high-voltage power module applications and large modules. The housing and at least one terminal exert a compressive load on the top or upper surface of the metal substrate structure. Therefore, a pre-bent insulated metal substrate can be realized due to the specific lengths of the sidewalls and one or more terminals configured in coordination with each other, and the convex curvature of the back surface thus formed contributes to proper thermal contact between the metal substrate structure and the cooler.

[0006] According to one embodiment, the overall length, including the length of the at least one terminal, is provided such that the at least one terminal protrudes at least 0.5 mm beyond the distance or length of the side wall or each side wall portion in the direction toward the top metal layer. Alternatively, the overall length is greater than the distance between the lower surface of the top wall and the upper surface of the top metal layer by at least 0.5 mm, respectively. Thus, the one or more terminals can have a certain length beyond the portion of the housing compared to the distance between the module cover and the upper surface of the insulated metal substrate in a relaxed state before attachment of the housing block.

[0007] The respective lengths of the at least one terminal and sidewall may refer to the entire length of the respective portion of the terminal or sidewall, or the associated element along the stacking direction. Due to the fact that the at least one terminal is intentionally formed longer than the corresponding length of the sidewall, the metal substrate structure bends outward from the housing, resulting in a convex shape on the backside of the metal substrate structure. For example, an edge or side region of the metal substrate structure connected to the sidewall of the housing may be pulled or pressed toward the housing by bonding and / or may be fixedly connected to the sidewall of the housing by, for example, gluing or screwing, while one or more terminals exert a compressive load on the metal substrate structure that pushes an intermediate portion of the metal substrate structure out of the housing.

[0008] The length of at least one terminal may also be configured in coordination with adjacent elements to result in a total length greater than the predetermined distance between the lower surface of the upper wall and the upper surface of the metal top layer. For example, additional elements or protrusions may be present on the upper surface of the metal top layer and / or the lower surface of the upper wall. Thus, the length of the terminal itself may be increased, but need not be greater than the distance between the upper wall and the metal top layer.

[0009] For example, if there are no additional elements or protrusions between the terminals and the top wall and / or the terminals and the top metal layer, the length of the terminals is greater than the aforementioned distance and greater than the length of each side wall portion between the lower surface of the top wall and the upper surface of the top metal layer. In such a case, at least one terminal protrudes beyond the distance or length of the side wall or side wall portion in the direction toward the top metal layer, causing bending of the insulated metal substrate structure and a convex shape on its back surface when the housing is joined together with the terminal and the metal substrate structure.

[0010] According to one embodiment of the semiconductor power module, the housing and the metal substrate structure are coupled to each other by at least one of screwing, gluing, clamping and sealing, or any other applicable coupling method. For example, a seal can be disposed between the sidewall or frame portion of the housing and the metal substrate structure. For example, the housing and / or the metal bottom layer include respective threaded holes for enabling a screw connection. Thus, the housing and the metal substrate structure can be coupled to each other by a screw connection disposed in a respective region or part or portion adjacent to the sidewall of the housing.

[0011] According to a further embodiment of the semiconductor power module, the housing is formed by molding, for example, by injection molding, transfer molding, and / or compression molding. One or more terminals are integrally bonded to and partially embedded in the molded housing. The molded housing can be made of a thermoplastic or thermosetting resin. The housing can be made of, for example, an epoxy resin. The housing material can also include fillers, such as particles, fibers, and / or chemical additives.

[0012] According to a further embodiment of the semiconductor power module, at least one terminal is connected to the lower surface of the upper wall and / or the upper surface of the metal top layer by at least one of clamping, soldering, welding, adhesive bonding, and sintering. Alternatively or additionally, other applicable joining methods are possible.

[0013] In the context of the present disclosure, it is known that conventional insulated metal substrates may have a risk of void formation due to concave curvature of the backside of the metal substrate between the base plate and the cooler surface, which significantly reduces the thermal performance of the corresponding power module. Conventional insulated metal substrates are typically flat before power module assembly, and therefore there is a risk that the insulated metal substrate will have a strong, undesirable concave curvature of the backside after module assembly, making this base plate type unusable for power modules with large footprints. The backside of an originally flat insulated metal substrate can have a strong concave curvature of several hundred microns after soldering a chip to the insulated metal substrate, for example, due to thermal mismatch between the silicon chip and the metal sheet and the mechanical features of the insulated metal substrate.

[0014] The above-described pre-bent metal substrate structure allows for a predetermined convex shape on the back surface of the base plate. Taking into account the preliminary step, for example, when a chip is soldered to the metal substrate structure, causing a concave curvature, the described configuration of the semiconductor power module (overcompensates or cancels out the concave curvature). Therefore, the described semiconductor power module configuration makes it possible to prevent the formation of voids between the base plate and the cooler surface when the base plate is attached to a cooler unit or heat sink. Therefore, a highly uniform and large surface contact between the bottom surface of the metal substrate structure and the heat sink is possible, which results in a proper thermal interface between the metal substrate structure and the heat sink. In particular, due to the convex curvature of the back surface or bottom surface, a reliable thermal contact is formed in the center of the metal substrate structure. Due to the pressure applied by the terminals, when the semiconductor power module is attached to the cooler, the substrate may become flat, but pressure is applied, especially in the center, preventing the formation of voids. Additionally, the convex curvature, and therefore the proper thermal interface, can remain available during module operation, which can contribute to improved reliability.

[0015] According to a further embodiment, the semiconductor power module includes two or more terminals disposed inside the housing, one coupled to the lower surface of the upper wall and the other coupled to the upper surface of the metal top layer. The two or more terminals may have different lengths in the stacking direction between the lower surface and the upper surface. Below, the present disclosure is described in the context of multiple terminals. For example, the semiconductor power module may include three, four, or five terminals. However, the features and characteristics of two or more terminals are also disclosed for a semiconductor power module including only one terminal, and vice versa.

[0016] According to a further embodiment of the semiconductor power module, the terminals or respective elongated portions of the terminals are arranged symmetrically inside the housing with respect to a median axis or plane of symmetry of the semiconductor power module along a transverse direction perpendicular to the stacking direction.

[0017] According to a further embodiment of the semiconductor power module, the terminals may comprise springs or stress relief structures configured to apply pressure or to compensate in a predetermined way for excessively strong mechanical stresses on the metal substrate structure or on the respective terminal legs.

[0018] According to a further embodiment, the semiconductor power module includes a cushioning element coupled to at least one terminal configured to apply pressure to the terminal and / or the metal substrate structure in a predetermined manner. The cushioning element may be disposed on an upper wall of the housing, allowing pressure to be applied from above. In some cases, the cushioning element may be disposed between the upper surface of the housing and the respective terminal. The height of the terminal may be the sum of the height of the terminal itself and the cushioning element.

[0019] According to a further embodiment of the semiconductor power module, the terminals comprise respective elongated terminal bodies and respective plate-like terminal legs having contact surfaces that contact or face the upper surface of the metal substrate structure. The terminal legs may directly contact the metallization pattern, or the metal top layer or the contact surfaces of the terminal legs may be partially or completely covered with a coating including one or more layers of at least one of gold, silver, and nickel. The finished terminals may also be coated.

[0020] According to further embodiments, the semiconductor power module includes a heat sink coupled to the bottom surface of the metal bottom layer to dissipate heat during operation of the semiconductor power module. The semiconductor power module can include a separate heat sink, for example, with fins or ribs. Alternatively or additionally, the metal bottom layer of the metal substrate structure can act as the heat sink itself, for example, configured with pin fins, ribs, or protrusions to provide beneficial heat dissipation. The metal bottom layer can further function as a base plate for the semiconductor power module. The semiconductor power module including the metal substrate structure can further be partially or completely encapsulated with a resin or dielectric gel created by molding or potting. Even with a hard filler material, the described features or configurations of the semiconductor power module can help provide and maintain the necessary curvature during and after the encapsulation process.

[0021] The described configuration of the semiconductor power module allows for mounting a housing block, of which power and / or auxiliary terminals can be an integral part, on an insulated metal substrate comprising a metal base, an insulating resin sheet, and circuit metallization realized by the metal substrate structure, wherein one or more terminals are specifically designed to apply a compressive load to the insulated metal substrate, resulting in a convex curvature on at least a portion of the backside of the metal substrate structure.

[0022] According to one embodiment, a method for manufacturing a semiconductor power module includes providing a metal substrate structure, a housing, and at least one terminal as described above. The at least one terminal thus has a predetermined length, e.g., at least 0.5 mm, greater than the length of the sidewall of the housing in the stacking direction. The method further includes bonding the at least one terminal, the housing, and the metal substrate structure together such that the at least one terminal is disposed inside the housing and is bonded to a lower surface of the top wall on the one hand and to a top surface of the top metal layer on the other hand. This causes the one or more terminals to apply a compressive load to the metal substrate structure, bending the metal substrate structure in a predetermined manner and including a convex shape on the bottom or back surface of the metal substrate structure that interacts with the housing and the at least one terminal.

[0023] As a result of the described method enabling the manufacture of one embodiment of the aforementioned semiconductor power module, the described features and characteristics of the semiconductor power module are also disclosed as methods of manufacture, and vice versa. Accordingly, the present disclosure includes several aspects, and all features described with respect to one of the aspects are also disclosed herein with respect to the other aspects, even if each feature is not explicitly mentioned in the context of a particular aspect.

[0024] According to one embodiment of the method, the step of bonding the terminals, the housing, and the metal substrate structure together includes forming the housing by molding such that the at least one terminal is integrally bonded to and partially embedded in the molded housing, and the method further includes bonding the molded housing and the at least one embedded terminal to the metal substrate structure by at least one of screwing, clamping, gluing, and sealing.

[0025] According to one embodiment of the method, the step of providing a metal substrate structure can include forming an insulated metal substrate by combining a top metal layer with a dielectric layer and a bottom metal layer. Thus, the method can include aligning the top metal layer, the dielectric layer, and the bottom metal layer with respect to one another, and stacking the top metal layer, the dielectric layer, and the bottom metal layer.

[0026] Alternatively, the step of combining the top metal layer with the dielectric layer and the bottom metal layer includes providing a molding substance, aligning the top metal layer and the bottom metal layer relative to one another with a predetermined distance therebetween, and then forming the dielectric layer by molding by bringing the provided molding substance between the aligned top metal layer and the bottom metal layer. Forming the dielectric layer by molding can be performed, for example, by injection molding, compression molding, and / or transfer molding.

[0027] Thus, the dielectric layer can be realized as a prepreg sheet assembled between two metal plates, one above the other, forming the top and bottom metal layers. Such metallization sheets or plates are bonded to the dielectric layer's insulators, for example, by a lamination process. The required metallization structure of the top metal layer can then be achieved by subsequent masking and etching steps to locally remove the conductive metal, creating the final metallization structure.

[0028] For molded dielectric layers, the molding substance provides a pumpable material with predetermined material properties. The pumpable substance is a liquid or viscous material for the dielectric layer to be formed. For example, the molding substance can be an epoxy and / or ceramic-based liquid containing a thermally conductive inorganic filler material, including ceramic particles. Alternatively or additionally, the dielectric layer material can be a thermosetting or thermoplastic resin material, such as polyamide, PBT, or PET. Alternatively or additionally, the dielectric layer material can include an inorganic filler for improved thermal conductivity and / or CTE adjustment for the metal top layer and / or bottom layer. For example, the molded dielectric layer can include a resin-based dielectric material with a ceramic filler material, such as epoxy, Al2O3, AlN, BN, Si3N4, or SiO2. For example, the dielectric layer can be an epoxy with a filler. The dielectric layer can also be based on other materials suitable for transfer, injection, or compression molding, such as bismaleimide, cyanate ester, polyimide, and / or silicone. Alternatively or additionally, the dielectric layer may comprise a ceramic material and / or a hydroset material, or a combination of two or more of the aforementioned materials. The thickness of the dielectric resin layer may be between 100 and 200 μm.

[0029] By aligning the top and bottom metal layers with respect to each other with a predetermined distance between them, the thickness of the molded dielectric layer is substantially predetermined. For example, alignment can be achieved by placing the top metal layer on a release film or liner, or by another fixation, for example, within the mold chase of a molding tool. This allows the metallization structure provided on the top metal layer to be accurately positioned relative to the bottom metal layer, which can be useful, for example, when the top metal layer has separate metal pads due to different operating potentials. In the case of lamination, the thickness of the resin layer is determined by the thickness and behavior of the laminated layers.

[0030] According to a further embodiment of the manufacturing method, the metal top layer can be provided with a given metallization pattern by stamping. Alternatively or additionally, the metal top layer can be provided, for example, by etching and / or cutting. Alternatively or additionally, the metal top layer can be formed in a predetermined configuration, for example, by laser cutting a provided metal sheet.

[0031] The metallization of the top metal layer can be formed from films and / or sheets containing copper and / or aluminum and / or copper alloys and / or aluminum alloys. This also applies to the bottom metal layer, which can be formed, for example, as a copper and / or aluminum plate and / or the corresponding alloys. The top metal layer can include a circuit metallization coating. Such a coating can be one or more layers made of or containing nickel, gold, silver, and / or other metals. The thickness of the circuit metallization or top metal layer can be 150 to 500 μm.

[0032] One or more terminals can function as power terminals or auxiliary terminals, for example, used for signal wiring. The one or more terminals can be made of or include copper or a copper alloy. The one or more terminals can include a coating on the bottom surface of one or more layers made of or including nickel, gold, silver, and / or other metals. Alternatively or additionally, additional components or the complete terminal can be coated. The one or more terminals are specifically designed to apply a compressive load. The length of the terminal is at least 0.5 mm greater than the distance between the bottom surface of the housing module cover and the top surface of the insulated metal substrate in a relaxed state before installation of the housing block. The lengths of the individual terminals may vary. The housing may be formed as a molded block including a shape with pre-bent, curved, or protruding structures capable of supporting the compressive load applied by the terminals.

[0033] The proposed use of a housing block, where terminals exert pressure or compressive loads on an insulated metal substrate, makes this relatively cost-effective substrate technology attractive for larger power modules and higher voltage classes. For example, this allows the manufacture of semiconductor power modules with side lengths or widths up to 34 mm x 100 mm, or even 140 mm x 190 mm. In this respect, the side lengths or widths extend transversely, perpendicular to the stacking direction of the semiconductor power module.

[0034] The application of pressure ensures that the backside of the insulated metal substrate has the correct convex curvature orientation even after assembly of the complete semiconductor power module, which is beneficial for proper thermal interface between the semiconductor power module and the cooler or heat sink. After attachment to the cooler, the substrate becomes nearly flat, but pressure is then applied to the metal substrate structure by one or more longer terminals to prevent the formation of voids, especially in the central region.

[0035] The described configuration of a semiconductor power module allows for significant cost savings when replacing the standard configuration of a ceramic substrate soldered to a base plate with an insulated metal substrate realized by a metal substrate structure. On the one hand, material costs can be reduced, and on the other hand, several process steps, such as the bonding process between the substrate and the base plate in the semiconductor power module assembly, can be eliminated from the process flow. Furthermore, the use of a screw connection between the housing and the insulated metal substrate eliminates the need to glue the module housing to the insulated metal substrate.

[0036] Exemplary embodiments are described below with the aid of schematic diagrams and reference numbers. The drawings show: [Brief explanation of the drawings]

[0037] [Figure 1] 1 is a schematic side view of an embodiment of a semiconductor power module. [Figure 2] 1 is a schematic cross-sectional view of an embodiment of a semiconductor power module. [Figure 3] 1 is a schematic cross-sectional view of an embodiment of a semiconductor power module. [Figure 4] 1 is a flowchart of a method for manufacturing an embodiment of a semiconductor power module. DETAILED DESCRIPTION OF THE INVENTION

[0038] The accompanying drawings are included to provide a further understanding. It should be understood that the embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale. The same reference numerals indicate elements or components having the same function. Insofar as elements or components correspond to each other in terms of their function in different figures, their description will not be repeated for each of the following figures. For clarity, elements may not in some cases be labeled with corresponding reference numerals in all figures.

[0039] FIG. 1 shows a side view of an embodiment of a semiconductor power module 1 for a semiconductor device. According to further embodiments, the semiconductor power module 1 may include other configurations than those shown in FIG. 1 . The semiconductor power module 1 includes a metal substrate structure 10 that implements an insulated metal substrate. The semiconductor power module 1 further includes an electronic device coupled to the metal substrate structure 10 and a heat sink 3 also coupled to the metal substrate structure 10. The electronic device may include, for example, a chip, particularly a power semiconductor device. With respect to the illustrated stacking direction A, the electronic device is coupled to a top surface 14 of a top metal layer 11 of the metal substrate structure 10 (see FIGS. 2 and 3 ). The heat sink 3 is coupled to a bottom surface 15 of a bottom metal layer 13 of the metal substrate structure 10. The metal substrate structure 10 further includes a dielectric layer 12 formed between the top metal layer 11 and the bottom metal layer 13.

[0040] Both the top metal layer 11 and the bottom metal layer 13 are, for example, made of metal or at least contain a metal and / or a corresponding alloy, such as copper and / or aluminum. Alternative thermally and / or electrically conductive materials or material combinations can be used instead. The dielectric layer 12 is, for example, a prepreg sheet or a filled epoxy resin molding. The filler may be ceramic or other inorganic fillers, such as glass fiber. Alternatively or additionally, the dielectric layer 12 can include a thermoplastic or thermosetting resin, such as polyamide, PBT, and / or PET. Alternatively or additionally, the dielectric layer 12 comprises a ceramic-based insulating layer, such as Al2O3, AlN, BN, Si3N4, or SiO2. The dielectric layer 12 can also be based on other materials suitable for injection molding, transfer molding, and / or compression molding, such as bismaleimides, cyanate esters, polyimides, and silicones, or even ceramic materials, such as hydroset materials. Thus, metal substrate structure 10 provides an insulated metal substrate having a structured top metallization, a metal backplane, and a dielectric insulating layer therebetween. Pads on metal top layer 11 are connected to components of an electronic device through leads 4 and / or via terminals 16 that are bonded to metal top layer 11 by, for example, welding or soldering.

[0041] The illustrated semiconductor power module 1 can be realized as a gel or resin-filled power module, in which the electronics of the metal substrate structure 10, or even the entire top surface, or even more, can be embedded or covered in an epoxy resin, thermoplastic or other thermosetting resin, and / or gel encapsulant. Such encapsulation can be performed, for example, by molding after fabrication of the metal substrate structure 10. For example, potting or molding can be performed after chip attachment and resin housing attachment, with integrated or separately attached terminals. Fabrication options for the semiconductor power module 1 include gel filling, epoxy resin filling, or potting by injection molding, transfer molding, and / or other molding methods.

[0042] 2 and 3 show different embodiments of the semiconductor power module 1 in schematic side views and / or cross-sectional views.

[0043] The semiconductor power module 1 includes a metal substrate structure 10 and a housing 2 configured to enclose the semiconductor power module 1 and the electronics of the metal substrate structure 10. The housing 2 includes a top wall 21 and a side wall 22 and is coupled to the metal substrate structure 10 by the side wall 22 and by screwing, clamping, and / or gluing, which may include a seal between the side wall 22 and the metal substrate structure 10. If threaded connections are used, the threaded connections may be located adjacent to the side wall 22 of the housing 2 and spaced apart from the middle portion 18 of the metal substrate structure 10. The housing 2 may be formed, for example, by molding with an epoxy resin or using either a thermoplastic or thermosetting resin. The housing 2 may form the aforementioned encapsulation of the semiconductor power module 1 or may form an additional cover for the metal substrate structure 10. The housing 2 may be integrally formed or may be made of two or more parts, for example, including a frame providing the side wall 22 and a cover providing the top wall 21.

[0044] The semiconductor power module 1 further comprises at least one terminal 16 arranged inside the housing 2. According to the embodiment shown in FIG. 2, the semiconductor power module 1 comprises four terminals 16. According to the embodiment shown in FIG. 3, the semiconductor power module 1 comprises three terminals 16. With respect to the middle axis M or a centrally located symmetry plane, the terminals 16 or their elongated portions are symmetrically arranged inside the housing 2 along a transverse direction B perpendicular to the stacking direction A. Alternatively, the terminal legs can be arranged symmetrically. However, the terminals 16 do not have to be arranged symmetrically.

[0045] The terminals 16 are bonded at one end to the underside 24 of the top wall 21 and at the other end to the top surface 14 of the metal top layer 11. Each terminal 16 includes an elongated terminal body and a plate-like terminal leg having a contact surface 17 that contacts the top surface 14 of the metal substrate structure 10. Alternatively, a bonding layer may be present between the contact surface 17 of one or more terminals 16 and the top surface 14. The bonding layer may be made of or include, for example, an adhesive, a solder, and / or a sintered material. The terminals 16 may be connected to the top surface 14 by soldering, gluing, sintering, ultrasonic welding, laser welding, and / or another welding and / or bonding process. The upper portions of the elongated terminal bodies of the terminals 16 may be integrally bonded to the top wall 21 embedded in the molded housing 2. Dry, pressure, or clamping of the terminals 16 to the housing 2 is also possible. Alternatively or additionally, the elongated terminal body of terminal 16 may be connected to top wall 21 by another joining method, or may be connected to a horizontal terminal portion located on the bottom or lower surface 24 of top wall 21.

[0046] The housing 2 and the metal substrate structure 10 are joined together such that a predetermined distance D exists between the lower surface 24 of the top wall 21 and the upper surface 14 of the top metal layer 11, each adjacent to a side wall 22, in the stacking direction A. The terminals 16 are configured to include a particular length or height. For example, at least one terminal 16 includes a length greater than the length of a corresponding side wall portion adjacent to the side wall 22.

[0047] For example, the length of one or more terminals 16 is at least 0.5 mm greater than one of the sidewalls 22 or distance D. The length and distance D refer to a direction along stacking direction A. The length of each terminal 16 is substantially defined by the length of the elongated terminal body between the lower surface 24 of the top wall 21 and the upper surface 14 of the metal top layer 11. The compared lengths of the sidewalls 22 also relate to the portions of each sidewall 22 between the lower surface 24 of the top wall 21 and the upper surface 14 of the metal top layer 11 and / or between the bottom surfaces of the sidewalls 22 at the outer edge regions where the sidewalls 22 and the metal substrate structure 10 are bonded. As shown in FIGS. 2 and 3 , terminals 16 closer to the edge regions can have a shorter length than terminals 16 closer to the middle portions 18 or intermediate portions. Thus, at least one terminal 16 closer to the middle portions or intermediate portions 18 includes a length that is at least 0.5 mm greater than the length of the sidewalls 22. At least one of the terminals 16, but not necessarily all of the terminals 16, may have a length that is at least 0.5 mm longer than the length of the side wall 22.

[0048] Thus, since the terminal(s) 16 are longer than the side walls 22, a compressive load is applied to the metal substrate structure 10, causing it to bend in a predetermined manner, including a convex shape on the back surface of the substrate that interacts with the housing 2 and the terminal(s) 16. The middle portion 18 of the metal substrate structure 10 is therefore pressed outward, and a resulting bending height H is formed between the height level of the top surface 14 in the edge regions and the height level of the top surface 14 in the middle portion 18. Depending on the length of the terminal(s) 16, the bending height H can have a value of 0.5 mm or more, and the length and / or width of the metal substrate structure 10 along the transverse direction B and corresponding further transverse directions can have values ​​of, for example, 34 mm x 100 mm or 140 mm x 190 mm.

[0049] The pre-bent metal substrate structure 10 and its predetermined convex shape enable the provision of a semiconductor power module 1 that can prevent the formation of voids due to the concave curvature of the substrate back surface between the bottom surface 15 and the top surface of the heat sink 3. Therefore, the described configuration of the metal substrate structure 10 and the semiconductor power module 1 can take distortions into account during assembly by pre-compensating. Therefore, a highly uniform and large surface contact between the bottom surface 15 of the metal substrate structure 10 and the top surface of the heat sink 3 can be achieved, which results in a suitable thermal interface between the metal substrate structure 10 and the heat sink 3. This improves the heat dissipation of the semiconductor power module 1 during operation. The thermal interface can also be thinner in the center due to the applied compressive load and the corresponding convex curvature of the substrate back surface, resulting in better heat dissipation and improved reliability during operation, especially when the compressive load is still available during module operation.

[0050] However, the length of at least one terminal 16 itself can be longer, but need not be longer than the distance D between the top wall 21 and the metal top layer 11. Alternatively or additionally, as illustrated in FIG. 2, additional elements or protrusions 25 may be present on the top surface 14 of the metal top layer 11 and / or on the bottom surface 24 of the top wall 21. The elements or protrusions 25 may be integrally formed with the top wall 21 or may be separate parts. Alternatively or additionally, additional elements, such as chips, metal platelets, auxiliary substrates, or bonding materials, or protrusions between the terminals 16 and the metal top layer 11 may be integrally formed with the metal top layer 11 or formed as separate parts.

[0051] Thus, with respect to the stacking direction A, the at least one terminal 16 has a length configured in coordination with the distance D between the lower surface 24 of the top wall 21 adjacent the side wall 22 and the upper surface 14 of the metal top layer 11. The length of the at least one terminal 16 may be configured in coordination with the one or more elements or protrusions 25 such that the at least one terminal 16 contributes in a predetermined manner to the bending and convex shape of the metal substrate structure 10. As a result, with respect to the relaxed state of the assembled semiconductor power module 1, the distance within the middle portion 18 is greater than the distance D on the outside proximate the side wall 22.

[0052] The corresponding manufacturing method steps may follow the flowchart shown in Figure 4. In step S1, the metal substrate structure 10, the housing 2 and the terminals 16 may be formed and / or provided. At least one terminal 16 has a given length in the stacking direction A that contributes to an overall length that is at least 0.5 mm greater than the corresponding length of the side wall 22 of the housing 2.

[0053] In step S2, the terminals 16, housing 2, and metal substrate structure 10 are bonded together such that the terminals 16 are positioned inside the housing 2 and are bonded at one end to the underside 24 of the top wall 21 and at the other end to the top surface 14 of the metal top layer 11. The terminals 16 thereby provide a compressive load to the metal substrate structure 10, causing it to bend in a predetermined manner and forming a convex shape on the back or bottom surface 15 of the substrate in interaction with the housing 2 and the terminals 16.

[0054] The terminals 16 can be made of copper or copper alloy and can be auxiliary or main terminals. The thickness of the terminals 16 can range from 0.2 mm to 3.0 mm in the transverse direction B and / or the stacking direction A. This can apply to both the upright terminal body portion and / or the horizontal terminal leg portion of the L-shaped terminal 16, respectively. The horizontal and vertical portions can have equal or different thicknesses.

[0055] The described embodiment of the semiconductor power module 1 provides the opportunity to form a convex curvature on the backside of the insulated metal substrate structure 10 even after the complete module assembly process. Increased reliability during module operation can be achieved by applying a compressive load to the center of the base plate, resulting in a convex curvature or at least a flat backside during long-term operation. The semiconductor power module 1 can include an integrated module housing 2 and terminals 16, each of whose legs exerts a pressure or compressive load on the insulated metal substrate structure 10, resulting in a convex curvature on the backside or bottom surface 15. The integrated module housing 2 and terminals 16 can be realized as an integral part or component forming a terminal or housing block. Thus, the terminals 16 can be formed as an integral part of such a housing block. The housing 2 can be screwed, clamped, or glued to the insulated metal substrate structure 10, and the housing block design can therefore support a compressive load on the metal substrate structure 10.

[0056] The housing 2 is typically fastened to the insulated metal substrate structure 10 by a screw connection. In such cases, corresponding screw holes are available in the insulated metal substrate structure 10 and / or the housing 2. Nevertheless, other attachment methods, such as gluing or clamping, are also possible. In the case of screwing or clamping, a seal is provided between the module housing 2 and the insulated metal substrate structure 10. The seal can be used to seal any remaining gaps between the housing 2 and the metal substrate structure 10, so that the semiconductor power module 1 can be filled with a liquid gel or resin during processing without leakage. Such a sealing material can include a rubber seal or other elastic material.

[0057] The described compressive loads on the top surface 14 of the insulated metal substrate structure 10 can be applied by terminals 16, for example, by the following design options.

[0058] The terminals 16 may have a length at least 0.5 mm greater than the distance between the module cover or top wall 21 in a relaxed state before attachment of the housing 2 and the top surface 14 of the insulated metal substrate structure 10. Here, the length of the terminals 16 may vary with respect to their position within the semiconductor power module 1 and the corresponding curvature of the insulated metal substrate structure 10.

[0059] The compressive load may be provided by a corresponding design of the housing 2, which may be realized for example by pre-bending the housing block or by curved or protruding structures.

[0060] Terminals 16 may incorporate springs or stress relief structures that provide pressure to each terminal leg at a better defined amount of pressure.

[0061] The additional cushioning element allows for a better defined amount of pressure to be applied to the terminal area.

[0062] The insulated metal substrate structure 10 can be formed by stamping a metal top layer 11 with a predetermined metallization pattern, a backing metal sheet, and a molded dielectric resin layer 12. Thus, the insulated metal substrate structure 10 can be formed as a stamped and formed metal substrate, or SMMS. Alternatively, the metal substrate structure 10 can be formed by laminating and etching the metal top layer 11. The housing 2 can form a power module housing consisting of a frame and cover portion and incorporates the power and auxiliary terminals 16. Depending on the design, the housing 2 can be formed from one piece or two or more separate pieces. The integral structure can be created by any molding process, such as transfer or injection molding of a resin material that embeds at least the upper portions of the terminal bodies of each of the terminals 16. Various resin materials are contemplated, such as epoxy resin and / or another thermosetting resin, or thermoplastic resin. The resin material may contain any type of filler, such as particles or fibers, as well as chemical additives, for example, to improve mechanical and / or thermal behavior. The connection between each terminal leg of terminal 16 and top surface 14 of insulated metal substrate structure 10 can be achieved by various joining processes, such as soldering, ultrasonic welding, laser welding, adhesive bonding, and / or sintering, or other applicable processes. Dry contact is also possible. Terminals 16 are typically made of copper or a copper alloy and may be coated, for example, with nickel to prevent oxidation.

[0063] 1-4 represent exemplary embodiments of the improved metal substrate structure 10, semiconductor power module 1, and manufacturing method thereof, and therefore do not constitute an exhaustive list of all embodiments. Actual arrangements and methods may differ, for example, from the embodiments shown for the metal substrate structure and power module. [Explanation of symbols]

[0064] Reference sign 1. Semiconductor power module 2. Housing 21 Upper wall of housing 22 Housing side wall 24 Underside of upper wall 25 elements / protrusions 3 Heatsink 4 Lead 10 Metal substrate structure 11 Metal Top Layer 12 Dielectric layer 13 Bottom metal layer 14 Top surface of metal substrate structure 15 Bottom of metal substrate structure 16 terminals 17 Terminal contact surface 18 Middle part of metal substrate structure A Stacking direction B. Horizontal D: Distance between the top wall and the top metal layer M intermediate shaft H bending height S(i) each step of the method for manufacturing a semiconductor power module

Claims

1. A semiconductor power module (1), - a metal substrate structure (10) having a metal top layer (11), a metal bottom layer (13), and a dielectric layer (12) bonded to both the metal top layer (11) and the metal bottom layer (13) between them in the stacking direction (A) of the metal substrate structure (10); a housing (2) configured to enclose the electronics of the semiconductor power module (1), the housing (2) having a top wall (21) and side walls (22), and coupled to the metal substrate structure (10) such that, in the stacking direction (A), there is a predetermined distance (D) between the bottom surface (24) of the top wall (21) adjacent to each of the side walls (22) and the top surface (14) of the metal top layer (11); and at least one terminal (16) arranged inside the housing (2), one of which is connected to the lower surface (24) of the upper wall (21) and the other of which is connected to the upper surface (14) of the metal top layer (11), the length of the at least one terminal (16) being configured in coordination with the distance (D) in the stacking direction (A), so that the at least one terminal (16) causes the metal substrate structure (10) to bend in a predetermined manner and has a convex shape that interacts with the housing (2).

2. 2. The semiconductor power module (1) according to claim 1, wherein the total length of the at least one terminal (16) including the length is such that the at least one terminal (16) protrudes at least 0.5 mm beyond the length of the side wall (22) in a direction towards the top metal layer (11).

3. 3. The semiconductor power module (1) according to claim 1 or 2, wherein the housing (2) and the metal substrate structure (10) are joined together by at least one of screwing, gluing, clamping and sealing.

4. 4. The semiconductor power module (1) according to claim 3, wherein the housing and / or the bottom metal layer (13) each comprise one or more screw holes, and the housing (2) and the metal substrate structure (10) are joined to each other by screw connections, the screw connections being arranged in respective areas adjacent to the side walls (22) of the housing (2).

5. 3. The semiconductor power module (1) according to claim 1 or 2, wherein the housing (2) is formed by molding, and the at least one terminal (16) is integrally connected to the upper wall (21) that is partially embedded in the molded housing (2).

6. 3. The semiconductor power module (1) according to claim 1 or 2, wherein the at least one terminal (16) is connected to the lower surface (24) of the upper wall (21) and / or the upper surface (14) of the metal top layer (11) by at least one of clamping, soldering, welding, adhesive bonding, and sintering.

7. Two or more terminals (16) are disposed inside the housing (2), one of which is coupled to the lower surface (24) of the upper wall (21) and the other of which is coupled to the upper surface (14) of the metal top layer (11), the two or more terminals (16) including different lengths in the stacking direction (A) between the lower surface (24) and the upper surface (14). A semiconductor power module (1) according to claim 1 or 2.

8. 8. The semiconductor power module (1) according to claim 7, wherein with respect to a medial axis (M) or a plane of symmetry, the two or more terminals (16) are symmetrically arranged inside the housing (2) along a lateral direction (B) perpendicular to the stacking direction (A).

9. 3. The semiconductor power module (1) according to claim 1 or 2, wherein the at least one terminal (16) comprises a spring or a resilient or stress-relieving structure configured to apply pressure to the metal substrate structure (10) in a predetermined manner.

10. a cushioning element coupled to the at least one terminal (16) configured to apply pressure to the terminal and / or the metal substrate structure (10) in a predetermined manner; A semiconductor power module (1) according to claim 1 or 2.

11. 3. The semiconductor power module (1) according to claim 1 or 2, wherein the at least one terminal (16) comprises an elongated terminal body and a plate-shaped terminal leg having a contact surface (17) that contacts or faces the top surface (14) of the metal substrate structure (10).

12. 12. The semiconductor power module (1) according to claim 11, wherein the contact surfaces (17) of the terminal legs and / or the contact portions of the upper surface (14) of the metal top layer (11) are covered with a coating comprising at least one layer of at least one of gold, silver, and nickel.

13. a heat sink (3) coupled to the bottom surface (15) of the bottom metal layer (13); A semiconductor power module (1) according to claim 1 or 2.

14. A method for manufacturing a semiconductor power module (1), comprising: - providing a metal substrate structure (10) with a metal top layer (11), a metal bottom layer (13) and a dielectric layer (12) bonded to both the metal top layer (11) and the metal bottom layer (13) in the stacking direction (A) of the metal substrate structure (10); - providing a housing (2) having a top wall (21) and a side wall (22) of a given length; - providing at least one terminal (16) having a given length; - coupling the at least one terminal (16), the housing (2), and the metal substrate structure (10) together such that the at least one terminal (16) is arranged inside the housing (2), one of the at least one terminal (16) being coupled to the lower surface (24) of the top wall (21) and the other of the at least one terminal being coupled to the upper surface (14) of the metal top layer (11), wherein the length of the at least one terminal (16) is configured in cooperation with a distance (D) between the lower surface (24) of the top wall (21) adjacent to each of the side walls (22) and the upper surface (14) of the metal top layer (11), whereby the metal substrate structure (10) is bent in a predetermined manner and provides a compressive load by the at least one terminal (16) to the metal substrate structure (10) so as to include a convex shape that interacts with the housing (2) and the at least one terminal (16).

15. bonding the at least one terminal (16), the housing (2), and the metal substrate structure (10) together, said bonding comprising: - forming said housing (2) by molding so that said at least one terminal (16) is integrally connected to said top wall (21) partially embedded in said molded housing (2); - bonding the molded housing (2) and the at least one embedded terminal (16) to the metal substrate structure (10) by at least one of screwing, clamping, gluing, and sealing.

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