Insulated metal substrate and method for manufacturing an insulated metal substrate - Patent Application 20070122997

Abstract

An insulated metal substrate (1) for a power semiconductor device is provided. The insulated metal substrate (1) includes a metal base (2), a dielectric layer (3) disposed on the metal base (2), a conductive layer (4) disposed on the dielectric layer (3), and a reinforcing structure (5), the reinforcing structure (5) being disposed in a peripheral region of the insulated metal substrate (1) at least partially surrounding a central region of the insulated metal substrate (1). A method for manufacturing the insulated metal substrate is also provided.

Description

[Technical Field]

[0001] SUMMARY The present disclosure relates to insulated metal substrates for power semiconductor devices and methods for fabricating insulated metal substrates. [Background technology]

[0002] SUMMARY OF THE INVENTION Embodiments of the present disclosure relate to particularly reliable and mechanically stable insulated metal substrates. Further embodiments of the present disclosure relate to methods for manufacturing such insulated metal substrates. Summary of the Invention [Means for solving the problem]

[0003] This is achieved by the subject matter of the independent claims. Further embodiments are evident from the dependent claims in the following description.

[0004] Insulated metal substrates for power semiconductor devices are described. The term "power" as used herein and hereinafter refers to power semiconductor devices, power semiconductor modules and / or power semiconductor chips adapted to handle voltages and currents greater than 100V and / or greater than 10A, for example, exemplary voltages up to 10kV and currents up to 5000A amperes.

[0005] According to one embodiment, the insulated metal substrate includes a metal base. The metal base has a main extending surface extending in a horizontal direction. The metal base has a back surface and a top surface opposite the back surface. The back surface and the top surface are connected by at least one side surface. Both the back surface and the top surface illustratively extend in the horizontal direction, and at least one side surface extends in a vertical direction perpendicular to the horizontal direction. The metal base is particularly formed as a plate.

[0006] The metal base has a height, for example, in the vertical direction, of 0.5 mm to 10 mm, in particular 1 mm to 2 mm. Exemplarily, the metal base comprises or consists of a conductive material, in particular a metal alloy or a metal, for example aluminum and / or copper.

[0007] According to an embodiment, the insulated metal substrate includes a dielectric layer disposed on a metal base, the dielectric layer in particular extending laterally, for example having a back surface and a top surface both extending laterally.

[0008] For example, the dielectric layer, particularly the back surface of the dielectric layer, is disposed directly on the metal base, particularly on the top surface of the metal base. In particular, the dielectric layer is disposed on the first side of the insulated metal substrate. The dielectric layer covers, for example, at least 80% or 90% of the top surface of the metal base. Illustratively, the dielectric layer completely covers the top layer of the metal base.

[0009] The dielectric layer has a vertical height of, for example, 50 μm to 500 μm, in particular 100 μm to 200 μm. Illustratively, the dielectric layer comprises or consists of an electrically insulating material.

[0010] According to an embodiment, the insulated metal substrate includes a conductive layer disposed on a dielectric layer, the conductive layer extending in particular in the laterally extending direction, for example having a back surface and a top surface extending in the laterally extending direction.

[0011] For example, the conductive layer, particularly the back surface of the conductive layer, is disposed directly on the dielectric layer, particularly on the top surface of the dielectric layer. In particular, the conductive layer is disposed on the first side of the insulated metal substrate. The conductive layer covers, for example, at least 50% or 70% and / or at most 95% or 90% of the top surface of the dielectric layer. In particular, the dielectric layer, particularly the top surface of the dielectric layer, is locally free of the conductive layer.

[0012] The vertical height of the conductive layer is, for example, 0.1 mm to 2.5 mm, particularly 0.5 mm to 1.0 mm. Exemplarily, the conductive layer comprises or consists of a conductive material, particularly a metal alloy or a metal, such as aluminum and / or copper.

[0013] For example, the metal base, the dielectric layer, and the conductive layer are stacked on top of each other in a stacking direction, which is a vertical direction perpendicular to the horizontal direction.

[0014] According to an embodiment, the insulated metal substrate includes a reinforcing structure. The reinforcing structure has a main extending surface extending in a horizontal direction. The reinforcing structure has a back surface and a top surface opposite the back surface. The back surface and the top surface are connected by at least two side surfaces, an inner surface and an outer surface. Both the back surface and the top surface illustratively extend in a horizontal direction, and each of the at least two side surfaces extends in a vertical direction.

[0015] In particular, the reinforcing structure is disposed on a first side of the insulated metal substrate, with the reinforcing structure layer facing the top surface of the metal base.

[0016] The reinforcing structure may, for example, have a vertical height of 0.5 mm to 8 mm or less, or 5 mm or less. Illustratively, the reinforcing structure may include or consist of a conductive material such as a metal or metal alloy.

[0017] According to an embodiment of the insulated metal substrate, the reinforcing structure is disposed in a peripheral region of the insulated metal substrate that at least partially surrounds a central region of the insulated metal substrate.

[0018] For example, the inner surface of the reinforcement structure faces the central region and the outer surface of the reinforcement structure faces away from the central region. The central region is located in the center of the insulated metal substrate and extends laterally toward the edges of the insulated metal substrate. The peripheral region extends laterally along the edges of the insulated metal substrate that define the central region.

[0019] The peripheral region completely surrounds the central region in the lateral direction. The reinforcing structure is disposed at least locally or completely within the peripheral region. For example, the reinforcing structure surrounds the central region in a frame-like shape. It should be understood that the shape of the reinforcing structure is not limited to a "frame-like" shape.

[0020] Illustratively, the reinforcing structure is provided to be connected to the metal base, the dielectric layer, and the conductive layer in a mechanically stable manner. In this case, the reinforcing structure mechanically stably supports the metal base, the dielectric layer, and the conductive layer, thereby reducing or preventing concave bending of the insulated metal substrate. In particular, the back surface of the insulated metal substrate bends convexly. In this specification and the following description, concave bending means that the insulated metal substrate bends toward the top surface, particularly in the central region. In other words, concave bending means that the back surface of the metal base bends toward the conductive layer, particularly in the central region.

[0021] According to an embodiment of the insulated metal substrate, the reinforcement structure does not protrude laterally beyond the metal base. For example, the reinforcement structure does not protrude laterally beyond the dielectric layer and / or the conductive layer. Illustratively, the outer surface of the reinforcement structure terminates flush with the outer surface of the metal base, the outer surface of the dielectric layer, and / or the outer surface of the conductive layer. In particular, the outer surface of the reinforcement structure is coplanar with the outer surface of the metal base, the outer surface of the dielectric layer, and / or the outer surface of the conductive layer.

[0022] For example, the metal base, dielectric layer, and conductive layer are a laminate that may bend, particularly concavely, during the assembly process, which includes heating and cooling steps and exposes the laminate to heat. Concave bending of the backside of the metal base of a conventional insulated metal substrate, especially without a reinforcing structure, can result in several drawbacks. Such drawbacks include, for example, an inadequate thermal interface between the metal base and the heat sink or cracks in the dielectric layer.

[0023] In summary, an insulated metal substrate for a power semiconductor device having a reinforcement structure can provide, among other advantages: By preventing or at least reducing concave bending, a relatively cost-effective insulated metal substrate technology can be used for large power modules and power modules for high-voltage classes. The mechanically rigid reinforcement structure can further reduce the risk of dielectric breakdown due to cracks in the dielectric layer caused by strong bending stresses. Furthermore, such an insulated metal substrate reduces concave or even convex bending of the metal base, which is beneficial for the thermal interface between the power module and the cooler. Additionally, such an insulated metal substrate reduces the increase in thermal resistance over time, resulting in an extended lifespan. Additionally, bending behavior due to thermal cycling during operation of the power semiconductor device is reduced, thereby improving the long-term behavior of the thermal interface, resulting in improved reliability and, for example, less thermal interface material waste. Furthermore, such an insulated metal substrate is lightweight compared to standard configurations in which the substrate is soldered onto a base plate. Such an insulated metal substrate also requires fewer process steps in the assembly process.

[0024] Such insulated metal substrates can be used in particular in low voltage industrial and automotive applications.

[0025] According to a further embodiment of the insulated metal substrate, the dielectric layer is an electrically insulating resin layer. The insulated metal substrate illustratively comprises or consists of an epoxy resin containing an inorganic filler, which comprises or consists of a ceramic material such as aluminum nitride (AlN), silicon nitride (Si3N4), boron nitride (BN), and / or aluminum oxide (Al2O3).

[0026] According to a further embodiment of the insulated metal substrate, the conductive layer comprises a circuit metallization, for example comprising a plurality of portions, at least some of which are laterally spaced apart from one another, such that at least some of the portions are electrically isolated from one another.

[0027] The circuit metallization is configured to connect to at least one power semiconductor device, for example, in the central region.

[0028] According to a further embodiment of the insulated metal substrate, the height of the reinforcing structure is equal to or greater than the height of the conductive layer. The height of the reinforcing structure ranges from the rear surface to the top surface of the reinforcing layer in the longitudinal direction. Furthermore, the height of the conductive layer ranges from the rear surface to the top surface of the conductive layer in the longitudinal direction. In particular, all portions have the same height.

[0029] Illustratively, the top surface of the reinforcing structure projects vertically away from the metal base and above the top surface of the conductive layer.

[0030] For example, the height of the reinforcing structure is at most 7.5 mm or 4.5 mm greater than the height of the conductive layer.

[0031] Alternatively, the height of the reinforcing structure is less than the height of the conductive layer. The height of the reinforcing structure is determined by taking into account the physical properties of the material used for the reinforcing structure. The physical properties can be Young's modulus, coefficient of thermal expansion, and other physical properties related to the flexibility or hardness of the material and its behavior with temperature changes. The higher the Young's modulus value, the smaller the height or thickness required for the reinforcing structure can be determined for materials with similar coefficients of thermal expansion (constant coefficient of thermal expansion, CTE value).

[0032] According to a further embodiment of the insulated metal substrate, the reinforcing structure is formed continuously. In particular, the reinforcing structure completely surrounds the central region in the lateral direction. In this case, the reinforcing structure is formed continuously. Exemplarily, the reinforcing structure is formed as a single piece.

[0033] Alternatively, the continuously formed reinforcing structure includes at least two sections formed of different materials, illustratively connected to one another.

[0034] According to a further embodiment of the insulated metal substrate, the reinforcing structure is discontinuous. In this case, the reinforcing structure is discontinuous and not continuous. In particular, the reinforcing structure comprises at least two sections, which are illustratively laterally spaced apart from one another. Illustratively, the reinforcing structure is formed as separate parts or sections.

[0035] The compartments may all be formed from the same material, or alternatively, at least two of the compartments are formed from different materials.

[0036] According to a further embodiment of the insulated metal substrate, at least one of the height of the reinforcing structure and the width of the reinforcing structure is uniform, the width of the reinforcing structure being the smallest extent of the reinforcing layer from the inner surface to the outer surface in the lateral direction.

[0037] Illustratively, the height of the reinforcing structure is the same throughout the peripheral region, and the width of the reinforcing structure is the same throughout the peripheral region except for corner regions of the insulated metal substrate, where the corner regions of the reinforcing structure are wider than the regions where the reinforcing structure extends in a straight line.

[0038] For example, the width of the reinforcing structure is 1 mm or more and 20 mm or less, or 10 mm or less. According to a further embodiment of the insulated metal substrate, at least one of the height and width of the reinforcing structure is not uniform. Illustratively, the height of the reinforcing structure is different in at least two regions within the peripheral region. For example, the width of the reinforcing structure is different in at least two regions within the peripheral region.

[0039] According to a further embodiment of the insulated metal substrate, the reinforcing structure includes at least one additional reinforcing structure, for example, the additional reinforcing structure is disposed on a first side of the insulated metal substrate, in which case the additional reinforcing structure layer faces the upper surface of the metal base.

[0040] The longitudinal height of the additional reinforcing structure may be, for example, 0.5 mm to 8 mm or 5 mm. Illustratively, the additional reinforcing structure may include or consist of a conductive material, such as a metal or metal alloy. The additional reinforcing structure may be formed of the same material as the reinforcing structure or a different material from the reinforcing structure.

[0041] Advantageously, the additional reinforcing structure further enhances the mechanically stable support for the metal base, dielectric layer and conductive layer, thereby reducing concave bending of the insulated metal substrate.

[0042] According to a further embodiment of the insulated metal substrate, at least one additional reinforcing structure extends in the central region. In particular, the additional reinforcing structure is disposed in the central region. For example, the additional reinforcing structure extends laterally from the peripheral region in the central region.

[0043] According to a further embodiment of the insulated metal substrate, the at least one additional reinforcing structure is integrally formed with the reinforcing structure, in which case the additional reinforcing structure can be formed as an integral part of the reinforcing structure, for example the additional reinforcing structure is continuously connected with the additional reinforcing structure.

[0044] Alternatively, the additional reinforcing structure and the reinforcing structure are formed of different materials and bonded together.

[0045] According to a further embodiment of the insulated metal substrate, the at least one additional reinforcing structure is spaced apart from the reinforcing structure, which means that the additional reinforcing structure can be formed as a separate part from the reinforcing structure, for example, the additional reinforcing structure is not continuously connected to the additional reinforcing structure.

[0046] The additional reinforcing structures advantageously improve the mechanical stability of the insulated metal substrate, and are advantageously located in the central region or in locations where the strongest bending is likely to occur, in order to further increase or at least reduce the suppression of concave bending in the central region of the insulated metal substrate.

[0047] According to a further embodiment of the insulated metal substrate, the at least one additional reinforcing structure is configured to divide the central region into at least two sections, for example, the additional reinforcing structure extends entirely between opposing side surfaces, i.e., opposing inner surfaces, of the reinforcing structure.

[0048] According to a further embodiment of the insulated metal substrate, the reinforcing structure comprises a metal, a polymeric material and / or an inorganic material.

[0049] Illustratively, the height and / or width of the reinforcing structure and / or the material of the reinforcing structure are predetermined according to the bending of the metal base, dielectric layer, and conductive layer during the assembly process without the reinforcing structure. For example, the laminate is relatively flat, i.e., exhibits no bending, at an initial temperature T1 during the bonding process with the power semiconductor device. However, because the metal base has a "mechanical advantage" over the dielectric layer and conductive layer, the laminate exhibits concave bending, for example, during cooling to a temperature lower than the initial temperature. In this case, the material of the reinforcing structure is predetermined so that the reinforcing structure has a smaller thermal expansion coefficient than the metal base. If the expansion coefficient of the metal base were relatively large, the metal base would bend strongly during cooling if the reinforcing structure were not available. The thickness of the reinforcing structure is predetermined, for example, by Young's modulus, which refers to the stiffness of the material of the reinforcing structure. Additionally, taking into account that bending behavior is reduced due to thermal cycling during operation of the power semiconductor device, the long-term behavior of the thermal interface and, therefore, reliability, may be improved.

[0050] The flat back surface of the metal base is achieved, inter alia, by the following formula: d metal_base ε metal_base λmetal_base + d dielectric_layer ε dielectric_layer λ dielectric_layer = d reinforcment_structure ε reinforcment_structure λ reinforcment_structure where d is the corresponding height, ε is the corresponding Young's modulus, and λ is the corresponding coefficient of thermal expansion.

[0051] For example, depending on the height, Young's modulus, and thermal expansion coefficient of the reinforcing structure relative to the metal base, the dielectric layer, and / or the conductive layer, a predetermined convex curvature of the backside of the metal base can be advantageously achieved, or at least concave curvature can be reduced or prevented, which can advantageously increase cooling efficiency.

[0052] According to a further embodiment of the insulated metal substrate, the reinforcing structure is disposed on the metal base, e.g., in the peripheral region, the metal base does not include the dielectric layer and the conductive layer, and the reinforcing structure is in direct contact with the metal base in the peripheral region.

[0053] According to a further embodiment of the insulated metal substrate, the reinforcing structure is disposed on the dielectric layer. For example, the top surface of the metal base is completely covered with the dielectric layer, but the top surface of the dielectric layer is free of the conductive layer in its peripheral area. The reinforcing structure is in direct contact with the dielectric layer in the peripheral area.

[0054] Illustratively, the additional reinforcing structure is disposed on the dielectric layer, such that the top surface of the dielectric layer does not include the conductive layer in the central region where the additional reinforcing structure is disposed.

[0055] According to a further embodiment of the insulated metal substrate, the reinforcing structure is disposed on the conductive layer. For example, the upper surface of the metal base is completely covered with a dielectric layer. The conductive layer is disposed on the dielectric layer in a peripheral region. In this case, at least one of the portions is disposed in the peripheral region. The reinforcing structure is in direct contact with the conductive layer in the peripheral region.

[0056] Illustratively, the additional reinforcing structure is disposed on the conductive layer, for example, in a central region on one of the at least one portion.

[0057] According to a further embodiment of the insulated metal substrate, the potential of the reinforcing structure is grounded. Illustratively, the reinforcing structure and / or the further reinforcing structure are conductively connected to the conductive layer or to the metal base.

[0058] Alternatively, the potential of the reinforcing structure is floating, in which case, for example, the reinforcing structure is not conductively connected to the conductive layer or the metal base.

[0059] According to a further embodiment of the insulated metal substrate, the reinforcement structure is grounded by at least one screw and / or by at least one bonding wire. For example, the reinforcement structure is conductively connected to the metal base via a screw and / or a bonding wire, or by part of the circuit metallization. Alternatively, the reinforcement structure is conductively connected directly to the base material of the metal base. In particular, the metal base is connected to the ground of the insulated metal substrate.

[0060] Illustratively, the reinforcing structure includes at least one opening extending completely through the reinforcing structure in the longitudinal direction. The opening is configured to receive a screw or bolt, thereby connecting the reinforcing structure to the metal base and, in turn, thereby connecting the insulated metal substrate or the completed power module to a cooler or heat sink. Furthermore, the dielectric layer and / or the conductive connection includes at least one additional opening, which completely overlaps the opening in the transverse direction, specifically to match the opening.

[0061] Additionally, methods for producing insulated metal substrates are described herein by which the insulated metal substrates described herein may be produced or are produced, and therefore features relating to the insulated metal substrates are also disclosed in connection with the methods, and vice versa.

[0062] According to an embodiment of the method, a metal base is provided. According to an embodiment of the method, a dielectric layer is provided disposed on a metal base.

[0063] According to an embodiment of the method, a conductive layer is provided, disposed on a dielectric layer. Exemplarily, a material for the conductive layer is applied onto the dielectric layer. The conductive layer material completely covers the top surface of the dielectric layer. For example, after applying the conductive layer material, the conductive layer material is structured to form a conductive layer. The structuring is achieved, for example, by a chemical etching process and / or a physical etching process.

[0064] Alternatively, a metal base and portions of the circuit metallization are provided and a dielectric layer is molded.

[0065] According to an embodiment of the method, a reinforcing structure is provided, the reinforcing structure being provided in a peripheral region of the insulated metal substrate.

[0066] Furthermore, such methods for insulated metal substrates advantageously reduce process steps in the assembly process, for example, since no steps are required to bond the substrate to a base plate.

[0067] According to an embodiment of the method, the reinforcing structure is applied to at least one of the metal base, the dielectric layer, and the conductive layer, particularly, the reinforcing structure is pre-fabricated and applied to at least one of the metal base, the dielectric layer, and the conductive layer.

[0068] According to an embodiment of the method, the reinforcement structure is subjected to at least one of the following processes: laminating, bonding, soldering, sintering, brazing, gluing, screwing.

[0069] According to an embodiment of the method, the reinforcing structure is made from a metal-based base material. Exemplarily, a metal-based base material is provided. After providing the metal-based base material, the base material is structured to form a monolithic structure, i.e., the metal base and the reinforcing structure, from the base material. The structuring is achieved, for example, by an etching or grinding process.

[0070] For further understanding, figures are attached. In the figures, elements having the same structure and / or function may be referred to by the same reference numerals. It should be understood that the embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale. [Brief explanation of the drawings]

[0071] [Figure 1] 1 is a schematic three-dimensional view illustrating an insulated metal substrate according to an exemplary embodiment; [Figure 2] 1 is a schematic three-dimensional cross-sectional view of an insulated metal substrate according to an exemplary embodiment; [Figure 3] 1 is a schematic three-dimensional cross-sectional view of an insulated metal substrate according to an exemplary embodiment; [Figure 4] 10 illustrates a simulation of vertical displacement of an insulated metal substrate as a function of height for each reinforcement structure made of different materials in accordance with an illustrative embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0072] The insulated metal substrate 1 according to the exemplary embodiment of FIG. 1 includes a metal base 2, a dielectric layer 3, and a conductive layer 4, and the metal base 2, the dielectric layer 3, and the conductive layer 4 are stacked on top of each other in a stacking direction which is the vertical direction.

[0073] The upper surface of the metal base 2 is completely covered with a dielectric layer 3. The dielectric layer 3 is disposed on the upper surface of the first side of the insulating metal substrate 1. Furthermore, the dielectric layer 3 is an electrically insulating resin layer formed to provide electrical insulation.

[0074] The conductive layer 4 is disposed on the top surface of the dielectric layer 3 at the first side 8. Furthermore, the conductive layer 4 includes a conductively formed circuit metallization, where the conductive layer 4 includes multiple portions, at least some of which are spaced apart from one another in a lateral direction extending perpendicular to the longitudinal direction.

[0075] The metal base 2, the dielectric layer 3, and the conductive layer 4 are particularly formed as a laminate. The metal base 2, the dielectric layer 3, and the conductive layer 4 each have a height. The metal base 2 is formed to have a uniform height along its extension direction. The dielectric layer 3 is formed to have a uniform height along its extension direction. The conductive layer 4, particularly some portions thereof, is formed to have a uniform height along its extension direction. "Uniform" means that each of the heights may vary slightly, i.e., by at least a maximum of 5%, due to manufacturing tolerances. The same applies to the uniform width.

[0076] In addition, the insulated metal substrate 1 has a reinforcing structure 5 disposed in a peripheral region surrounding the central region of the insulated metal substrate 1. In particular, the reinforcing structure 5 is disposed on the top surface of the dielectric layer 3 on the first side 8. The reinforcing structure 5 is in direct contact with the dielectric layer 3.

[0077] In particular, both the metal base 2 and the dielectric layer 3 have a predominantly rectangular shape. By "predominantly," we mean that the rectangular shape has chamfered or rounded corners. Furthermore, the outer surface of the reinforcing structure 5 has a rectangular outline, while the inner surface opposite the outer surface and facing the central region has an octagonal outline. The lateral distance from the outer surface to the inner surface defines the width of the reinforcing structure 5. The width of the reinforcing structure 5 increases in the direction of each corner of the rectangular outline.

[0078] The upper surface of the dielectric layer 3 does not include the conductive layer 4 in the peripheral region where the reinforcing structure 5 is disposed. In this case, the conductive layer 4 is disposed only in the central region completely surrounded laterally by the reinforcing structure 5.

[0079] The vertical height of the reinforcing structure 5 is greater than the height of the conductive layer 4. In particular, the height of the reinforcing structure 5 is at most 4.5 mm greater than the height of the conductive layer 4.

[0080] An opening 6 is provided in each area of ​​each corner of the rectangular outline. Each opening 6 is configured to receive a screw, by which the reinforcing structure 5 is grounded to the metal base 2.

[0081] Furthermore, recesses 7 are provided in each corner region of the rectangular outline, spaced laterally from the opening 6. Each of the recesses 7 has a smaller circumference than the opening 6. Illustratively, the recesses 7 are configured to receive adjustment pins of a part of a power semiconductor component or a part of a power semiconductor module configured to be mounted on the insulated metal substrate 1.

[0082] The exemplary embodiment of Figure 2 relates to the exemplary embodiment of Figure 1. The reinforcing structure 5 is arranged directly on the dielectric layer 3 in a peripheral region that completely surrounds the central region.

[0083] In contrast to the exemplary embodiment of Fig. 2, the reinforcing structure 5 is arranged on the conductive layer 4 in the exemplary embodiment of Fig. 3. One of the portions of the conductive layer 4 is arranged in the peripheral region, which is laterally spaced apart from the other portions of the conductive layer 4 in the central region.

[0084] Illustratively, finite element simulations show the effect of the height and material of the reinforcing structure 5 on the bending of the insulated metal substrate 1 upon cooling by 100K, as exemplarily shown in FIG.

[0085] The insulated metal substrate 1 used for the exemplary simulation has a metal base 2 made of copper. For example, the reinforcing structure 5 of the insulated metal substrate 1 used for the exemplary simulation is made of aluminum. At the initial temperature T1, the insulated metal substrate 1, and in particular the metal base 2, are assumed to be flat and unstressed.

[0086] Illustratively, exemplary simulations are performed for reinforcing structures 5 having various heights, such as 2 mm, 4 mm, and 8 mm. The vertical difference corresponding to the undesired concave bending of the rear surface of the metal base 2 after cooling by 100 K is defined as the vertical difference between the highest and lowest points in the vertical direction of the rear surface of the metal base 2. The simulation results in vertical differences of 0.22 mm for a height of 1 mm, 0.18 mm for a height of 2 mm, 0.13 mm for a height of 4 mm, and 0.04 mm for a height of 8 mm.

[0087] In this case, the difference in the vertical direction, ie, the bending of the insulating metal substrate 1, depends on the height of the reinforcing structure 5.

[0088] 4 shows the simulation results similar to the exemplary simulation and in particular the influence of different materials of the reinforcing structure 5 with regard to Young's modulus and thermal expansion coefficient, and the influence of different heights of the reinforcing structure 5. The longitudinal difference z is shown on the y-axis in mm, and the height d of the reinforcing structure 5 is shown on the x-axis of the diagram.

[0089] Simulation points characterized by triangles correspond to reinforcement structures 5 comprising iron-nickel alloys. Simulation points characterized by filled circles correspond to reinforcement structures 5 comprising copper. Simulation points characterized by squares correspond to reinforcement structures 5 comprising aluminum. Simulation points characterized by open circles correspond to reinforcement structures 5 comprising magnesium alloys or stainless steel.

[0090] The greatest reduction in bending occurs when the reinforcing structure 5 comprises aluminum, magnesium alloy or stainless steel.

[0091] If the reinforcing structure 5 comprises copper, the reduction in bending can be less. If the reinforcing structure 5 comprises an iron-nickel alloy, the opposite effect of stronger bending is achieved, which increases as the height of the reinforcing structure 5 increases. In particular, the iron-nickel alloy has a smaller coefficient of thermal expansion than the metal base 2, while all other materials of the reinforcing structure 5 have a larger coefficient of thermal expansion than the metal base 2. [Explanation of symbols]

[0092] Reference sign 1 insulated metal substrate, 2 metal base, 3 dielectric layer, 4 conductive layer, 5 reinforcement structure, 6 opening, 7 recess, 8 first side.

Claims

1. An insulated metal substrate (1) for a power semiconductor device, comprising: - Metal base (2) and a dielectric layer (3) placed on said metal base (2); a conductive layer (4) placed on said dielectric layer (3); a reinforcing structure (5), - said reinforcing structure (5) is arranged in a peripheral region of said insulated metal substrate (1) at least partially surrounding a central region of said insulated metal substrate (1); - said reinforcing structure (5) does not protrude laterally beyond said metal base (2); an insulated metal substrate (1), said reinforcing structure (5) being made of metal;

2. the dielectric layer (3) is an electrically insulating resin layer, - said conductive layer (4) comprises a circuit metallization; 2. The insulated metal substrate (1) according to claim 1, wherein the insulated metal substrate (1) is at least one of:

3. - An insulated metal substrate (1) according to claim 1 or 2, wherein the height of said reinforcing structure (5) is equal to or greater than the height of said conductive layer (4).

4. - An insulated metal substrate (1) according to any one of claims 1 to 3, wherein the reinforcing structure (5) is continuously formed.

5. An insulated metal substrate (1) according to any one of claims 1 to 3, wherein the reinforcing structure (5) is discontinuously formed.

6. - at least one of the height of the reinforcing structure (5) and the width of the reinforcing structure (5) is uniform, and / or An insulated metal substrate (1) according to any one of claims 1 to 5, wherein at least one of the height of the reinforcing structure (5) and the width of the reinforcing structure (5) is non-uniform.

7. - said reinforcing structure (5) comprises at least one additional reinforcing structure, - Insulated metal substrate (1) according to any one of claims 1 to 6, wherein said at least one additional reinforcing structure extends in said central region.

8. - said at least one additional reinforcing structure is integrally formed with said reinforcing structure (5), or - Insulated metal substrate (1) according to claim 7, wherein said at least one additional reinforcing structure is spaced apart from said reinforcing structure (5).

9. - An insulated metal substrate (1) according to claim 7 or 8, wherein said at least one additional reinforcing structure (5) is configured to divide said central region into at least two sections.

10. - said reinforcing structure (5) is placed on said metal base (2); - said reinforcing structure (5) is placed on said dielectric layer (3), - said reinforcing structure (5) is placed on said conductive layer (4); 10. The insulated metal substrate (1) according to any one of claims 1 to 9, wherein the insulated metal substrate (1) is at least one of:

11. - the potential of said reinforcing structure (5) is earthed, The insulated metal substrate (1) according to any one of claims 1 to 10, wherein the reinforcing structure (5) is grounded by at least one screw and / or the reinforcing structure (5) is grounded by at least one bonding wire.

12. A method for manufacturing an insulated metal substrate (1) for a power semiconductor device, comprising: - providing a metal base (2); - providing a dielectric layer (3) placed on said metal base (2); - providing a conductive layer (4) arranged on said dielectric layer (3); - providing a reinforcing structure (5), - said reinforcing structure (5) is provided in the peripheral area of ​​said insulated metal substrate (1); - said reinforcing structure (5) does not protrude laterally beyond said metal base (2); - the method, wherein said reinforcing structure (5) is made of metal.

13. - said reinforcing structure (5) is applied to at least one of said metal base (2), said dielectric layer (3) and said conductive layer (4); The method according to claim 12, wherein said reinforcing structure (5) is subjected to at least one of the following processes: laminating, gluing, soldering, sintering, brazing, gluing, screwing.

14. The method according to claim 12, wherein said reinforcing structure (5) is made from the base material of said metal base (2).

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