METHOD FOR MANUFACTURING A POWER MODULE UNIT, POWER MODULE UNIT, POWER SUPPLY AND FREQUENCY CONVERTER

Description

[0001] The invention relates to a method for manufacturing a power module unit and to a power module unit. Furthermore, the invention relates to a power supply unit and a frequency converter.

[0002] Power modules typically comprise a substrate with a power semiconductor, such as an IGBT (Insulated-Gate Bipolar Transistor), which is rigidly bonded to the substrate. The substrate has a metal structure on both sides; one side of the metal structure is designed for bonding with the power semiconductor, while the other side allows it to be mounted to a base plate.

[0003] According to the current state of the art, the base plate is preferably provided with a heat-conducting structure and mounted on a heat sink. To compensate for thermal effects, a complex pre-curvature of the base plate is necessary so that the base plate remains firmly connected to the heat sink even at temperatures exceeding 100 degrees Celsius.

[0004] EP2328172 A1, EP3190371 A1, EP2031332 A1, EP1378940 A2 and DE102006038980 A1 disclose power modules with heat sinks that have cooling fins inserted into recesses and fixed in place.

[0005] The unit, comprising a power module and a heat sink, is referred to here as the power module unit.

[0006] A further disadvantage of the current state of the art is the large number of material interfaces. This reduces the heat flow from the power semiconductor via the base plate to the heat sink.

[0007] To improve heat transfer from the power semiconductor to the heat sink, for example DE 10 2013 207 804 A1 proposes forming a base plate with thermally conductive structures on one side in one piece. The power semiconductor is attached to the opposite side of the base plate.

[0008] However, the size of the heat-conducting structures is limited by the manufacturing process. Furthermore, the production of such a power module unit is complex and therefore expensive.

[0009] The object of the invention is therefore to simplify the method for manufacturing a power module unit.

[0010] The problem is solved by a power module unit according to claim 1. The problem is further solved by a frequency converter or a power supply unit according to claim 10. The problem is also solved by a method according to claim 11.

[0011] Advantageous designs and further training are subject to dependent claims.

[0012] The invention is based on the understanding that directly applying the substrate with the power semiconductor to the base plate eliminates a material boundary between the base plate and the heat sink. Preferably, the substrate is attached to the base plate of the heat sink with a soldered connection. The base plate thus serves as a support for the substrate on one side. Furthermore, the other side of the base plate serves to attach the cooling fins.

[0013] With conventional heat sinks featuring cooling fins, which can be several centimeters long, this method presents difficulties because the entire heat sink must be heated to a temperature of approximately 200 to 500 degrees Celsius, for example, in an oven. Heating the entire heat sink, however, is energy- and time-consuming. Therefore, the invention is based on the insight that it is advantageous to heat only the base plate with the substrate in the oven and to attach the cooling fins to recesses in the base plate after the substrate has been secured. The cooling fins are preferably attached in such a way that the base plate with the substrate is not bent. Bending the base plate could damage the substrate.

[0014] This is achieved, for example, by a trapezoidal cross-section of the recess. Furthermore, the cooling fins can advantageously be inserted into the respective recess in a tangential direction to the first side.

[0015] Preferably, the substrate comprises a ceramic layer, wherein the ceramic layer has a metal layer on both the top and bottom surfaces, at least partially. The metal layer preferably comprises copper, silver, or tin. The metal layer, preferably applied only partially to the top surface of the substrate, serves to attach the power semiconductor. The metal layer, preferably applied to the bottom surface, serves to solder, press, or sinter the substrate to the base plate.

[0016] The power module unit has a base plate with at least one recess on a first side, wherein at least one cooling fin is attached in the respective recess, wherein the respective cooling fin is attached to each recess of the base plate by a connection that is at least partially form-fit, partially material-fit and / or partially force-fit, wherein the base plate has a substrate for a power semiconductor on a second side, wherein the respective cooling fin has an attachment on at least one side, wherein the attachment touches the first side of the base plate after the cooling fin has been inserted.

[0017] The power module unit optionally includes a housing that protects the substrate from environmental influences. The substrate serves as the basis for power semiconductors such as an IGBT or a thyristor. Multiple power semiconductors can also be mounted on the substrate.

[0018] The recess preferably runs along the first side from one end of the base plate to the other end of the base plate.

[0019] The recess is advantageously designed to accommodate one or more cooling fins. The respective cooling fin is preferably inserted into the recess of the base plate after the substrate on the other side has already been attached to the base plate.

[0020] Preferably, the power module unit additionally comprises a housing, the housing of which covers at least part of the second side. The housing serves to cover and thus protect the substrate or the at least one power semiconductor.

[0021] A material-bonded connection includes, for example, a soldered joint, an adhesive joint, or a welded joint.

[0022] The connection between the cooling fin and the base plate is preferably designed to be positively locked, at least in some areas. This positive-locking connection ensures good thermal contact between the base plate and the respective cooling fin. The positive-locking connection thus serves to improve the dissipation of heat from the power semiconductors via the base plate to the cooling fins.

[0023] Preferably, the cooling fins are attached to the base plate by a force-fit connection such that the cooling fins are inserted into a heated base plate and form a force-fit connection as the base plate cools. Alternatively or additionally, the cooling fins can also be cooled during insertion and form a force-fit connection upon warming to room temperature.

[0024] The invention offers the following advantages: By directly connecting the substrate to the base plate and with only one additional thermal resistance to the cooling fins, heat can be dissipated from the substrate particularly efficiently via the cooling fins. The variable connection between the base plate and the cooling fins allows parameters of each cooling fin, such as length, shape, and surface finish, to be specifically adapted to the application of the power module unit. Because the substrate is simply attached to the base plate, it can be manufactured quickly and energy-efficiently using an oven.

[0025] In an advantageous embodiment of the invention, the respective cooling fin is connected to the base plate by a press connection, an adhesive connection or a soldered connection.

[0026] Alternatively or additionally, the respective cooling fin can be attached to the recess in the base plate using a soldered or adhesive connection.

[0027] The power module unit is robustly designed against external influences thanks to the fixed connection of each cooling fin to the base plate. Furthermore, this fixed connection ensures efficient and reliable heat transfer from the power semiconductor to the cooling fins.

[0028] In a further advantageous embodiment of the invention, the base plate comprises copper, aluminium or a layer of copper and a layer of aluminium.

[0029] Copper is preferably used as the material for receiving the substrate because it is well suited for forming a soldered connection and is a good heat conductor.

[0030] Aluminium is preferably used as the material for the base plate because aluminium is a good heat conductor and, moreover, its good malleability makes it suitable for a form-fitting connection between the base plate and the cooling fins.

[0031] A particularly advantageous base plate is formed from two firmly bonded metal layers. Such a base plate has an aluminum layer adjacent to the first side, which has a copper layer on its upper surface. The two metal layers are bonded together, for example, by a rolling process. Alternatively, the layers can also be bonded together by a soldering process, especially a high-temperature soldering process.

[0032] Such a layer has the aforementioned advantages and is commercially available.

[0033] The attachment serves to limit the penetration of the cooling fin into the recess in such a way that only one bottom side of the recess touches the cooling fin.

[0034] Alternatively or additionally, the attachment can protrude partially into the recess. For example, the recess has angled side surfaces at its edges. These side surfaces serve to accommodate the angled side surface of the attachment.

[0035] The attachment reduces the stress on the base plate when inserting the respective cooling fin into the recess. In particular, the bending stress, which induces a force perpendicular to the first side of the base plate, can be effectively reduced. By reducing the force and thus the bending stress on the base plate, the connection between the substrate and the base plate is subjected to less stress when inserting the cooling fins into the recess.

[0036] In a further advantageous embodiment of the invention, the respective cooling fin comprises copper, aluminum or an alloy.

[0037] The cooling fin is preferably made of a material with good thermal conductivity, in particular aluminium, an aluminium alloy, copper or a copper alloy.

[0038] A material with good thermal conductivity allows heat to be efficiently dissipated from the base plate.

[0039] In a further advantageous embodiment of the invention, the fastening of the base plate to the respective cooling fin is reinforced by indentations and embossings.

[0040] Preferably, at least some of the recesses in the base plate and / or the cooling fins have indentations and / or raised features. When the cooling fin is inserted into the respective recess, the indentations can create indentations in the cooling fin. These indentations form a positive-locking connection, at least in some areas.

[0041] Preferably, the raised sections of the cooling fin protrude into the indentations of the respective recess. This allows for a particularly strong connection.

[0042] The features in the respective recess therefore serve to improve the connection of the cooling fins to the base plate.

[0043] In a further advantageous embodiment of the invention, the hardness of the material for the base plate and the hardness of the material for the respective cooling fin are different.

[0044] Preferably, the base plate is made of a material with a greater hardness than the material of the cooling fins. This allows the cooling fin material to deform slightly, creating at least a partially positive-locking connection between the base plate and the cooling fin.

[0045] In the alternative described above, it is advantageous that the cooling fin and / or the inside of the recess in the base plate are slightly deformed when the cooling fin is inserted into the respective recess. In particular, embossed features contribute to a deformation of the cooling fin and / or to the deformation of the base plate.

[0046] Alternatively, the material of the cooling fin can be harder than the material of the base plate. Such a design preferably leads to a simplified manufacturing process for the power module unit.

[0047] In a further advantageous embodiment of the invention, the respective cooling fin is U-shaped, O-shaped or 8-shaped.

[0048] Preferably, the cooling fin has an opening. This opening preferably serves to allow the passage of a cooling medium, such as an airflow. Preferably, the opening is designed such that the cross-section of the cooling fin is hollow on the inside. Therefore, the cross-section of the respective cooling fin is preferably O-shaped.

[0049] Preferably, the cooling fin in the middle is designed with a reinforcement, in particular a material transition.

[0050] This material transition results in a figure-eight shaped cross-section of the cooling fin.

[0051] In a further advantageous embodiment of the invention, the cross-section of the respective recess is tapered towards the second side, preferably in a trapezoidal shape.

[0052] To minimize bending stress on the base plate when inserting each cooling fin, the recess is tapered inwards. Preferably, the recess is trapezoidal. Optionally, raised features are positioned on the sides of the inner surface of each recess. These features preferably serve to secure the cooling fin within the recess.

[0053] The inwardly tapered recess advantageously protects the substrate of the power module unit when inserting the respective cooling fin.

[0054] In a further advantageous embodiment of the invention, additional cooling fins are positioned between the cooling fins, wherein the respective additional cooling fin and the cooling fin only overlap laterally in certain areas.

[0055] The additional cooling fins are preferably positively connected to the cooling fins. The additional cooling fins and the cooling fins preferably overlap by a width of 1 to 2 centimeters.

[0056] Preferably, the sides of the cooling fins are formed with a ribbed structure, at least in the area where the cooling fins and subsequent cooling fins overlap. A ribbed structure is understood to mean, in particular, that the side of the respective cooling fin and / or the side of the respective subsequent cooling fin has indentations. The indentation can have a triangular cross-section. Preferably, the indentations are aligned parallel to each other. Advantageously, the indentations are aligned parallel to the edge of the cooling fin.

[0057] Preferably, notches are positioned between the embossed markings. Preferably, the notches have a triangular cross-section.

[0058] Preferably, the raised areas of the cooling fin extend into the indentations of the adjacent cooling fin.

[0059] By extending the existing cooling fins with additional cooling fins, the cooling capacity of the power module unit can be subsequently increased.

[0060] In a further advantageous embodiment of the invention, the cooling fin is at least partially made of carbon, for example graphite.

[0061] Advantageously, the cooling fin can be made of carbon nanotubes, at least in some areas, or can include carbon nanotubes.

[0062] Graphite or carbon nanotubes, in particular, exhibit exceptionally high thermal conductivity.

[0063] The high thermal conductivity allows for improved cooling of the base plate.

[0064] In a further advantageous embodiment of the invention, cooling fins are connected to each other.

[0065] The cooling fins are advantageously connected by connecting elements. The connecting elements and the cooling fins preferably form a single unit. This unit is advantageously inserted as a whole into the recesses of the base plate.

[0066] Preferably, the connecting elements are bonded to the cooling fins by means of a material bond.

[0067] Preferably, the cooling fins and connecting elements are manufactured in one piece. Preferably, the connecting elements have openings. These openings advantageously serve to reduce weight. Furthermore, the openings are preferably designed to allow the passage of a cooling medium, in particular a cooling airflow.

[0068] This design allows for a particularly strong and uniform connection between the cooling fins and the base plate. Furthermore, heat can be transferred from one cooling fin to another.

[0069] In an advantageous embodiment of the invention, cooling fins are connected to each other by means of connecting elements to form a unit. Preferably, the units are designed such that one unit can be connected to another unit by means of a plug connection, a press connection or an adhesive connection.

[0070] The unit preferably has parallel-aligned cooling fins, wherein the cooling fins are connected to each other by the connecting elements.

[0071] Preferably, the cooling fins have a structured surface, in particular a ribbed surface, at both ends. The structured surface allows for improved connection between the cooling fins, preferably by inserting one cooling fin between two other cooling fins. The structured surface serves to improve the adhesion between the cooling fins. The connecting elements fix the cooling fins together.

[0072] One advantageous application of the power module unit described here is frequency converter or power supply, especially for industrial use.

[0073] Such a frequency converter is advantageously suited for mobile applications such as at least partially electrically powered vehicles. The invention is also advantageously applicable to electrically powered aircraft. Additionally, the invention can be advantageously used in a charger.

[0074] The invention is preferably used in a charger for an electrically powered vehicle or aircraft. Advantageously, the type, number, shape, and size of the cooling fins can be selected according to the cooling requirements of the power module unit in the respective application.

[0075] In the process for manufacturing a power module unit, the power module unit has a base plate with recesses on a first side, comprising the following steps: a) Positioning a substrate on a second side opposite the recesses; b) Heating the base plate and the substrate so that the substrate is attached to the first side of the base plate, in particular by a soldered, sintered, or press-fit connection; c) Inserting and attaching at least one cooling fin in the respective recess, wherein the attachment is positive-locking and / or force-locking, wherein the respective cooling fin has an attachment on at least one side, the attachment contacting the first side of the base plate after the cooling fin has been inserted

[0076] Optional and advantageous steps in the manufacture of the power module unit are: Attaching a housing to the base plate, wherein the housing protects the substrate and a power semiconductor; applying contact elements to a metal layer, wherein the metal layer serves to attach the power semiconductor. The respective contact element can be connected to the housing on one side. The contact element advantageously serves to connect the power semiconductor to an electrical conductor. Preferably, the substrate is insulated. Insulation is advantageously achieved by coating the substrate with a non-conductive polymer-based material, in particular a silicone-based material.

[0077] Preferably, the base plate and the substrate are heated in an oven. The substrate and the base plate are heated to a temperature between 200 and 500 degrees Celsius. This heating process creates a soldered, sintered, or press-fit connection between the substrate and the base plate.

[0078] The cooling fins are preferably inserted together into the recess provided for each cooling fin. For this purpose, the cooling fins are aligned and the base plate is pressed on.

[0079] In an advantageous embodiment, the recesses are made in the base plate after the substrate has been attached.

[0080] Preferably, the recesses are created in the base plate by machining. By subsequently creating the recesses, the base plate can be heated in an oven without them. The cuboid shape of the base plate allows for particularly even heating and provides exceptional stability when the base plate is press-fitted to the substrate.

[0081] To form a force-fit connection, the material of the base plate and the material of the respective cooling fin can be selected in such a way that, when the base plate is heated, the cross-section of the recess in the base plate is enlarged, and at room temperature, a force-fit and / or form-fit connection is formed around the part of the cooling fin that is located in the recess.

[0082] Alternatively or additionally, a soldered connection or an adhesive connection can also be used to attach the respective cooling fin to the base plate.

[0083] The above-described method for manufacturing the power module unit allows the cooling fins to be selected according to the specific application. At the same time, time is saved when joining the base plate to the substrate because the cooling fins do not need to be heated. Furthermore, heating the base plate without cooling fins enables a particularly uniform temperature distribution, resulting in an improved soldered or sintered bond between the substrate and the base plate.

[0084] Furthermore, it can be advantageous for the oven to be particularly low in height.

[0085] In a further advantageous embodiment of the invention, the base plate and the substrate are heated in an oven.

[0086] The base plate and the substrate on the base plate are preferably heated in a continuous oven. The necessary heating of the base plate and substrate can be precisely controlled by simply adjusting the oven's transit time.

[0087] In a further advantageous embodiment of the invention, the cooling fin is inserted into the recess after the base plate has cooled down.

[0088] Preferably, the base plate is cooled to room temperature before the cooling fin is inserted. Cooling the base plate prevents bending of the raised elements in the recess when inserting a cooling fin. Furthermore, an improved bond between the cooling fins and the base plate is achieved through adhesive bonding.

[0089] In a further advantageous embodiment of the invention, the cooling fins are inserted into the respective recess along the recess.

[0090] To protect the substrate when inserting the cooling fin into the recess, the force that would cause the base plate to bend should be avoided. Since the base plate is more stable along its tangential direction to the sides, inserting at least one cooling fin tangentially results in minimal deformation of the base plate and thus a low stress on the substrate.

[0091] In a further advantageous embodiment of the invention, the respective cooling fin comprises an opening, wherein a pressing means is guided into the opening of the cooling fin and the cooling fin is pressed into the recess with the aid of the pressing means.

[0092] Depending on the shape of the pressing device and the cross-section of the cooling fin, the pressing device can contribute to the formation of a positive-locking connection. The pressing device preferably deforms the respective end of the cooling fin so that the material of the cooling fin at least partially fills the recess.

[0093] A rod can be used as a pressing tool. The pressing tool is preferably inserted through an opening in the cooling fin, and the cooling fin is then placed into the recess. By using a pressing tool that acts on the cooling fin in the vicinity of the recess, bending of the cooling fin can be effectively prevented.

[0094] In a further advantageous embodiment of the invention, the base plate comprises copper, aluminum or a layer of copper and a layer of aluminum and / or the respective cooling fin comprises copper, aluminum or an alloy.

[0095] In a further advantageous embodiment of the invention, the attachment is positioned on the respective side of the cooling fin such that, after the cooling fin has been inserted into the recess, a cavity is formed in the recess, wherein the cavity is arranged between the side of the cooling fin and a bottom side of the recess.

[0096] In a further advantageous embodiment of the invention, the base plate with the substrate is heated in an oven and / or the cooling fin is inserted into the recess after the base plate has cooled.

[0097] In a further advantageous embodiment of the invention, the cooling fins, which are provided for insertion into the recesses of the base plate, are inserted into the recess provided for the cooling fin in one step.

[0098] In a further advantageous embodiment of the invention, the at least one cooling fin is inserted tangentially to the first side of the base plate, the recess having a cross-section that is particularly trapezoidal. Preferably, all cooling fins are inserted into the base plate in this manner.

[0099] In a further advantageous embodiment of the invention, when the at least one cooling fin is inserted tangentially into the base plate, the at least one cooling fin is pushed into the recess orthogonally to the cross-section of the recess, so that, in particular, the base plate is only minimally deformed. Preferably, all cooling fins are pushed into the base plate in this manner.

[0100] In a further advantageous embodiment of the invention, the at least one cooling fin is inserted into the recess via a side surface of the base plate, which is aligned orthogonally to the side surface, in particular by being pushed in or pulled in.

[0101] The at least one cooling fin is therefore pushed or pulled into the recess starting from the side surface of the base plate, so that during the insertion of the at least one cooling fin into the recess, the recess is gradually covered by the at least one cooling fin with respect to the first side of the base plate. Preferably, all cooling fins are pushed or pulled into the base plate in this manner.

[0102] The invention is described and explained in more detail below with reference to the figures. The embodiments shown in the figures are merely exemplary and do not limit the invention. Individual features of the exemplary embodiments can be combined to form further embodiments of the invention. They show:

[0103] FIG 1 shows an exemplary power module unit, wherein Fig. 1 FIG 2 is not part of the invention, a section of an exemplary power module unit, wherein Fig. 2 FIG. 3 is an exemplary method and FIG. 4 is a possible cross-section of a recess, which is not part of the invention. Fig. 4 FIG 5 is not part of the invention, another exemplary power unit wherein Fig. 5 FIG. 6 shows a section of a power module unit according to the invention, FIG. 7 shows a section of a power module unit according to the invention, and FIG. 8 shows a connection between cooling fins and further cooling fins, wherein FIG. 8 does not show a connection between cooling fins and further cooling fins. Fig. 8 is not part of the invention.

[0104] FIG 1 (not part of the invention) shows an exemplary power module unit 1. The power module unit 1 comprises a base plate 3, the base plate 3 having recesses 9 on a first side. The recesses 9 each serve to receive at least one cooling fin 7. The base plate has a substrate 4 on a second side 3b. The substrate 4 serves as a support for the power semiconductors 5. The substrate is preferably made of a ceramic, wherein the substrate has a copper coating on both sides. The copper coating serves in particular as the basis for a solder joint 11 for attaching the substrate 4 to the base plate 3. The power semiconductors 5 are preferably also connected to the substrate 4 by a solder joint 11. The base plate 3 is preferably made of a copper or an aluminum alloy.The base plate 3 is particularly advantageous because it is made of aluminum in the lower area, adjacent to the first side 3a, and of copper in the upper area, adjacent to the second side 3b. Such a base plate 3 is based on a layered material. A possible layered structure is indicated by the dashed line in the base plate 3. The respective cooling fin is attached to the base plate 3 by a positive-locking and / or force-locking connection in the respective recess 9.

[0105] FIG 2 (not part of the invention) shows a section of an exemplary power module unit 1. A base plate 3 with a plurality of cooling fins 7 is shown. The cooling fins 7 are each inserted into one of the recesses 9 of the base plate 3. The cooling fins 7 shown each have two openings 7a. The openings 8 are separated from each other by a boundary in the middle of the cooling fin 7. This creates a figure-eight profile of the cooling fin. The figure-eight profile allows an airflow to cool the cooling fin particularly efficiently. The cooling fin 7 is reinforced at each end 7b. Such reinforcement can be achieved by increasing the wall thickness of the cooling fin 7 in the region of its respective end 7a. By reinforcing the cooling fin 7 at its respective end 7a, a particularly stable connection between the respective cooling fin 7 and the base plate 3 is possible.

[0106] FIG 3 This shows an example procedure. The procedure comprises a first step a, a second step b, a third, optional step c, and a fourth step d.

[0107] In the first step a, the respective recess 9 is created in the base plate 3. The recess is embossed into the base plate by a rolling process, a machining process such as milling, or by a forging process.

[0108] In a second step b, a substrate 4 is positioned on the second side 3b of the base plate 3. To attach the substrate 4 to the second side 3b of the base plate 3, the base plate with the substrate is heated in an oven to a temperature of 200 to 500 degrees Celsius. In the second step b, the substrate 4 is permanently bonded to the second side 3b of the base plate by a soldered or sintered connection.

[0109] In a third, optional step c, the base plate with the substrate is cooled back down to room temperature. Depending on the type of bond between the substrate 4 and the base plate 3, the cooling process is either rapid or slow.

[0110] In a fourth step d, the cooling fins 7 are inserted into the respective recess 9 of the base plate and secured. The cooling fins are inserted either from the side, i.e., tangentially to the first side 3a of the base plate 3, or perpendicularly to it. When the cooling fins 7 are inserted tangentially into the base plate, the cooling fin 7 is pushed into the recess orthogonally to the cross-section 9a of the recess 9. This insertion method advantageously deforms the base plate only minimally.

[0111] When inserting the respective cooling fin 7 vertically into the recess 9, care should be taken to ensure that the force acting on the base plate 3 does not lead to a deformation of the base plate 3, as otherwise the substrate 4 could be damaged.

[0112] FIG 4 (not part of the invention) shows a possible cross-section 9a of a recess 9. The recess 9 of the base plate 3 tapers inwards. For improved retention of the cooling fin 7, the recess 9 has embossed features 10 on its inner surface 9b. The embossed features 10 advantageously serve to form partially interlocking connections between the base plate 3 (shown here as a section) and the cooling fin 7.

[0113] The trapezoidal cross-section 9a of the recess 9 serves to reduce the force acting perpendicular to the first side 3a or second side 3b of the base plate 3 when the cooling fin 7 is inserted vertically into the recess 9. Instead, the force is deflected in a direction tangential to the respective side 3a, 3b of the base plate 3. This is illustrated by the arrows emanating from the recess.

[0114] The figure also indicates a pressing device 11. The pressing device 11 serves to insert the cooling fin 7 into the recess 9. Preferably, the pressing device 11 is designed as a rod which is guided through the opening 7a of the cooling fin and can press the cooling fin 7 into the recess 9 of the base plate 3. Depending on the shape of the pressing device 11 and the cross-section of the cooling fin 7, the pressing device 11 can contribute to the formation of a positive-locking connection. The pressing device 11 preferably deforms the respective end 7a of the cooling fin 7 so that the material of the cooling fin 7 at least partially fills the recess 9.

[0115] FIG 5 (not part of the invention) shows another exemplary power module unit 1. The power module unit 1 has an analogous structure to the power module unit shown in FIG 1 shown. Unlike FIG 1 The power module unit shown here comprises 1 cooling fins 7, which are connected to one another. The cooling fins are connected by connecting elements 17. The connecting elements 17 and the cooling fins 7 form a fixed unit. The unit consisting of cooling fins 7 and connecting elements 17 is inserted into the recesses 9 of the base plate 3 and connected there, at least partially, to the base plate by means of a positive fit and / or a force-fit.

[0116] FIG 6 shows a section of a power module unit according to the invention 1.

[0117] Shown is a section of the base plate 3 with the recess 9, in which a cooling fin 7 has been inserted. The cooling fin 7 comprises an attachment 25, the attachment 25 being positioned on the respective side of the cooling fin 7 such that, after the cooling fin 7 is inserted into the recess 9, a cavity 23 is formed in the recess. The cavity 23 is located between the side of the cooling fin 7 and the bottom of the recess 9. The cavity 23 is formed because the cooling fin is not fully inserted into the recess 9. To form the cavity 23, the respective attachment 25 is positioned on the sides of the cooling fin 7 such that, after the cooling fin 7 is inserted into the recess 9, the attachment 25 touches or is attached to the first side 31.

[0118] Advantageously, the attachment 25 of the cooling fin 7 rests on the first side 3a of the base plate 3. This contact of the attachment 25 on the first side 3a advantageously increases the surface contact 21 between the cooling fin 7 and the base plate. This surface contact serves to transfer heat from the base plate 3 to the cooling fin.

[0119] The height of the cavity 23 can also be designed to be so small that the underside of the recess 9 touches the cooling fin 7 in places.

[0120] FIG 7 shows a section of a power module unit according to the invention 1.

[0121] Analogous to the excerpt that is in FIG 6 As shown, the cooling fin 7 also has an attachment 25. The attachment 25 is designed such that it has an inclined bearing surface, which rests on a corresponding incline at the recess 9. When the cooling fin 7 is inserted into the recess 9, the resulting forces are indicated by arrows. Depending on the orientation of the inclined bearing surface, these forces (symbolized by the arrows) have a force component in a direction parallel to the first side of the base plate 3.

[0122] Due to the angled orientation of the contact surface, less force is exerted on the base plate 3 when the cooling fin 7 is inserted, thus reducing the bending stress and consequently the load on the substrate 4. Furthermore, the area between the cooling fin 7 and the base plate 3 is increased. This larger area allows heat to be transferred from the base plate 3 to the cooling fin.

[0123] To improve the connection between the cooling fin 7 and the base plate, the inner surface 9a of the recess 9 and / or the cooling fin 7 on its side has an embossed feature 10. The embossed feature preferably projects into a notch, the notch being located on the side that contacts the embossed feature. Preferably, such an embossed feature 10 contributes to improved stability of the connection between the base plate 3 and the cooling fin 7.

[0124] FIG 8 (not part of the invention) shows a connection 21 between cooling fins 7 and further cooling fins 7'. The connection 21 between the cooling fins 7 and the further cooling fins 7' can be formed by a clamping connection or a force-fit connection. For improved cohesion, the cooling fins 7 and / or the further cooling fins 7' can have a ribbed structure in the area of ​​the connection 21. Preferably, cooling fins 7 and / or further cooling fins 7' have, on their respective sides, embossed features with a triangular cross-section that run parallel in some areas. These features can also project into notches, the notches having a triangular cross-section and being positioned between the embossed features in the cooling fin 7 and / or the further cooling fin 7'. Such a connection 21 is shown in the enlarged view. The ribbed structure serves to provide a more stable connection between the cooling fins 7 and the respective further cooling fin 7'.

[0125] Shown is a connecting element 17, wherein the connecting element 17 enables the connection of the cooling fins 7 (analogous to the embodiment shown in FIG 5 (as shown) is revealed.

[0126] The additional cooling fins 7', which are inserted in the spaces between the respective parallel-oriented cooling fins 7, serve to further improve the cooling of the respective parallel-oriented cooling fins 7 and thus to improve the cooling of the substrate 4 on the base plate 3.

[0127] In summary, the invention relates to a method for manufacturing a power module unit 1 and to a power module unit 1 itself. Furthermore, the invention relates to a power supply unit and a frequency converter. To manufacture the power module unit 1, a base plate 3 is provided with recesses 9. The base plate is connected to a substrate 4, which carries the power semiconductor 5. After the substrate 4 is attached to the base plate, the cooling fins 7 are inserted into the recesses 9 of the base plate 3 and secured by a positive and / or force-fit connection. This design allows a power module unit 1 to be configured with cooling fins 7 as required, while simultaneously simplifying the manufacturing of the power module unit 1.

Claims

1. Power module unit (1), in particular for a frequency converter, having a base plate (3) with at least one recess (9) on a first side (3a), wherein at least one cooling fin (7) is fastened in the respective recess (9), wherein the respective cooling fin (7) is fastened in the respective recess (9) of the base plate (3) by a connection that is designed with a positive fit at least in regions, a material fit in regions and / or a non-positive fit in regions, characterised in that the base plate (3) has a substrate (4) for a power semiconductor (5) on a second side (3b), wherein the respective cooling fin (7) has an attachment (25) on at least one side, wherein the attachment (25) touches the first side (3a) of the base plate (3) via a planar connection (21) once the cooling fin (7) has been introduced.

2. Power module unit (1) according to claim 1, wherein the respective cooling fin (7) is connected to the base plate (3) by way of a pressed connection, an adhesive connection or a soldered connection.

3. Power module unit (1) according to claim 1 or 2, wherein the base plate (3) has copper, aluminium or a layer of copper and a layer of aluminium and / or the respective cooling fin (7) has copper, aluminium or an alloy.

4. Power module unit (1) according to one of the preceding claims, wherein the attachment (25) is positioned on the respective side of the cooling fin (7) such that, once the cooling fin (7) has been introduced into the recess (9), a cavity (23) is embodied in the recess, wherein the cavity (23) is arranged between the side of the cooling fin (7) and a bottom side of the recess (9).

5. Power module unit (1) according to one of the preceding claims, wherein the fastening of the base plate (3) to the respective cooling fin (7) is reinforced by indentations and notches.

6. Power module unit (1) according to one of the preceding claims, wherein the hardness of the material for the base plate (3) and the hardness of the material for the respective cooling fin (7) are different.

7. Power module unit (1) according to one of the preceding claims, wherein the respective cooling fin (7) is embodied in a U-shaped, O-shaped or 8-shaped manner.

8. Power module unit (1) according to one of the preceding claims, wherein the cross-section (9a) of the respective recess (9) is tapered toward the second side (3b), preferably is embodied in a trapezoid-shaped manner.

9. Power module unit (1) according to one of the preceding claims, wherein further cooling fins (7') are positioned between the cooling fins (7), wherein the respective further cooling fin (7') and the cooling fin (7) only overlap at the sides in regions.

10. Frequency converter or power supply, in particular for industrial use, having a power module unit (1) according to the preceding claim.

11. Method for producing a power module unit (1), wherein the power module unit (1) has a base plate (3) with recesses (9) on a first side (3a), comprising the following steps: a) positioning a substrate (4) on a second side (3b) opposite the recesses; b) heating the base plate (3) and the substrate (4), so that the substrate is fastened to the first side (3a) of the base plate (3), in particular by way of a soldered or sintered connection (11); c) introducing and fastening at least one cooling fin (7) in the respective recess (9), wherein the fastening is designed with a positive fit and / or non-positive fit, wherein the respective cooling fin (7) has an attachment (25) on at least one side, wherein the attachment (25) touches the first side (3a) of the base plate (3) via a planar connection (21) once the cooling fin (7) has been introduced.

12. Method according to claim 11, wherein the heating of the base plate (3) with the substrate (4) takes place in a furnace and / or the introduction of the cooling fin (7) into the recess (9) takes place after the base plate (3) has cooled down.

13. Method according to one of claims 11 or 12, wherein the cooling fins (7) are introduced into the respective recess (9) along the recess (9).

14. Method according to one of claims 11 to 13, wherein the cooling fins (7) that are provided for introduction into the recesses (9) of the base plate (3) are, in one step, introduced into the recess (9) provided for the cooling fin (7) in each case.

15. Method according to one of claims 11 to 14, wherein the introduction of the at least one cooling fin (7) takes place tangentially in relation to the first side (3a) of the base plate (3), wherein the recess (9) has a cross-section (9a) that in particular is embodied in a trapezoid-shaped manner.

16. Method according to claim 15, wherein, when introducing the at least one cooling fin (7) into the base plate (3) tangentially, the at least one cooling fin (7) is slid into the recess (9) orthogonally in relation to the cross-section (9a) of the recess (9), so that in particular the base plate (3) is only minimally deformed.

17. Method according to one of claims 11 to 16, wherein the at least one cooling fin (7) is introduced into the recess (9), in particular slid in or drawn in, via a side area of the base plate (3) which is oriented orthogonally in relation to the side area (3a).

18. Method according to one of claims 11 to 14, wherein the respective cooling fin (7) comprises an opening (7a), wherein a pressing means is guided into the opening (7a) of the cooling fin (7) and the cooling fin (7) is pressed into the recess (9) with the aid of the pressing means.