Semiconductor module with improved cooling

Abstract

Semiconductor module, formed from a semiconductor package and at least one insulating package attached to one of the layers of thermally and electrically conductive material of the semiconductor package, the insulating package being formed in a sandwich-like manner from a layer of thermally and electrically conductive material attached to one of the layers of thermally and electrically conductive material, followed by a layer of thermally conductive and electrically insulating material, followed by a layer of thermally and electrically conductive material configured to provide a thermal connection to the outside, wherein the semiconductor package has at least one semiconductor switch with associated load and control busbar, wherein on the underside of the respectiveThe semiconductor switch has a first layer of thermally and electrically conductive material arranged in a designated area for thermal and electrical connection, the area of ​​which is larger than the area of ​​the semiconductor switch, and a second layer of thermally and electrically conductive material arranged on the top side of the semiconductor switch in a designated area for thermal and electrical connection, the area of ​​which is larger than the area of ​​the semiconductor switch, wherein the semiconductor switch with associated load and control busbar and the layers of thermally and electrically conductive material are surrounded by an electrically insulating sheathing such that an outer surface of each layer of thermally and electrically conductive material remains free to provide thermal and electrical connection to the outside.

Description

[0001] The present invention relates to the field of electromobility, in particular to electronic modules for an electric drive.

[0002] The use of electronic modules, also known as power electronics, in motor vehicles has increased significantly in recent decades. This is due on the one hand to the need to improve fuel economy and vehicle performance, and on the other hand to advances in semiconductor technology. The main components of such power electronics are an electronic control unit, also known as an ECU (electronic control unit), which is connected to or forms part of the vehicle control unit(s) and receives control signals and / or information based, for example, on driving behavior or signals from other control units, and a DC / AC inverter, which is used to supply electrical machines such as electric motors or generators with multi-phase alternating current (AC).In this process, direct current generated by a DC power source, such as a battery or accumulator, is converted into multiphase alternating current. For this purpose, an inverter comprises a variety of electronic components, particularly semiconductor switches, which are used to implement bridge circuits (such as half-bridges). The semiconductor switches are housed in a package, either as individual topological switches or already connected to form a half-bridge, and are therefore also referred to as semiconductor packages. Within the package, they are protected from external influences. Only their power and signal / control contacts extend to the outside.

[0003] Current inverter designs are characterized by the fact that the semiconductor switches must be actively cooled to dissipate switching and conduction losses. To dissipate these losses, a heat conduction path is constructed from the semiconductor package into a cooling medium, for example, via a DBC as an insulation and heat conduction element.

[0004] Alternatively, there are modules that do not have insulating ceramic built into the module, so this must be added during assembly to electrically insulate the cooling plate. Thermal resistance has a strong influence on the performance of semiconductors, but in current designs, this can only be influenced to a limited extent. For this reason, modules are already being equipped with double-sided cooling to reduce thermal resistance, as is known from US10586756B2 or US10128165B2.

[0005] Modules with dual-sided cooling are currently characterized by their use of thermal paste to connect them to the corresponding cooling plates. Soldering or sintering, i.e., solid bonding, is currently not possible, partly due to the height tolerances of the modules. Thermal pastes exhibit a significantly higher thermal resistance than comparable solid compounds. This difference affects the overall thermal resistance of the power core and thus its performance.

[0006] Therefore, one goal is to provide improved two-sided cooling for semiconductor packages.

[0007] This problem is solved by the features of the independent claims. Advantageous embodiments are the subject of the dependent claims.

[0008] A semiconductor package is proposed, comprising at least one semiconductor switch with associated load and control busbars, wherein on the underside of the orthe semiconductor switch has a first layer made of thermally and electrically conductive material arranged in a region provided for thermal and electrical connection, the area of ​​which is larger than the area of ​​the semiconductor switch, and a second layer made of thermally and electrically conductive material arranged on the top side of the semiconductor switch has a region provided for thermal and electrical connection, the area of ​​which is larger than the area of ​​the semiconductor switch, wherein the semiconductor switch with associated load and control busbars and the layers made of thermally and electrically conductive material are surrounded by an electrically insulating sheath in such a way that in each case an outer surface of the layers made of thermally and electrically conductive material remains free in order to provide a thermal and electrical connection to the outside.

[0009] In one embodiment, a thermally and electrically conductive intermediate element is arranged between the semiconductor switch and the second layer made of thermally and electrically conductive material, which provides a thermal and electrical connection of the second layer made of copper to the semiconductor switch.

[0010] Furthermore, a semiconductor module is provided which is formed from the semiconductor package and at least one insulation package attached to one of the layers of thermally and electrically conductive material of the semiconductor package, which insulation package is formed in a sandwich-like manner from a layer of a thermally and electrically conductive material attached to one of the layers of thermally and electrically conductive material, followed by a layer of a thermally conductive and electrically insulating material, followed by a layer of a thermally and electrically conductive material which is configured to provide a thermal and electrical connection to the outside.

[0011] In one embodiment, two insulation packages are provided, each of which is attached to one of the layers of thermally and electrically conductive material of the semiconductor package by means of a solid bond with a layer of thermally and electrically conductive material.

[0012] In one embodiment, each insulation package is surrounded by an electrically non-conductive sheathing in such a way that an outer surface of the layers of thermally and electrically conductive material remains free, each providing a thermal and electrical connection to the outside.

[0013] In one version, at least one insulation package is a DBC or AMB printed circuit board.

[0014] Furthermore, a single-phase or multi-phase module is provided, comprising a base plate serving as a heat sink, as well as at least one semiconductor package or semiconductor module attached to the base plate and for each phase, and electrically contacted DC and AC busbars on the semiconductor package(s) or semiconductor module(s) and with associated power connections.

[0015] In one embodiment, a second heat sink is arranged on one side of the semiconductor package(s) or semiconductor module(s) opposite the base plate.

[0016] Furthermore, power electronics are provided for the operation of a three-phase electric motor of a vehicle, wherein the power electronics comprise: an inverter formed from several single-phase or a multi-phase module, and at least one electronic control unit connected to the electric motor for its control and regulation and to the inverter.

[0017] Furthermore, an electric drive for a vehicle is provided, comprising a three-phase electric motor and an accumulator, as well as the power electronics connected to both.

[0018] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures of the drawing, which illustrate details of the invention, and from the claims. The individual features can be implemented individually or in combination in a variant of the invention.

[0019] Preferred embodiments of the invention are explained in more detail below with reference to the accompanying figures. Fig. Figure 1 shows a sectional view of a basic arrangement of a semiconductor package mounted on a heat sink with the associated thermal resistors according to the prior art. Fig. Figure 2 shows a double-sided cooled semiconductor package according to an embodiment of the present invention. Fig. Figure 3 shows a double-sided cooled semiconductor package according to an alternative embodiment of the present invention.

[0020] In the following descriptions of the figures, the same elements or functions are provided with the same reference symbols.

[0021] As already mentioned at the beginning, the semiconductor switches 40 arranged in a semiconductor package 4 for operating an inverter must be actively cooled in order to dissipate the switching and conduction losses resulting from operation. To dissipate the losses, a heat conduction path is constructed from the semiconductor switch 40 into a cooling medium 3, which is characterized by the fact that the total thermal resistance should be as low as possible. The thermal path (resistances Rth are shown on the far right) is usually constructed from the Fig. 1 shown components copper 41, ceramic 42, copper 41, heat sink 2, cooling medium 3, wherein the circuit board formed from the layers copper 41, followed by ceramic 42, followed by copper 41 represents an electrically insulating layer, as in Fig. Figure 1 illustrates this using a single-sided cooled semiconductor package 4. Such a printed circuit board can be, for example, a DBC or an AMB printed circuit board.

[0022] To make the semiconductor package 4 coolable on both sides, another DBC, i.e. a layer structure of copper 41, ceramic 42, copper 41, is arranged on its top side.

[0023] One of the problems with such a structure, in particular a structure that can be cooled on both sides, is that tolerance compensation between the semiconductor package 4 and the heat sink 2 arranged above the semiconductor package 4 can only be achieved by means of a thermal paste that has a significantly higher thermal resistance than a solid connection such as sintering or soldering.

[0024] To enable double-sided cooling of a semiconductor package 4 with improved tolerance compensation, a novel semiconductor package 4 is proposed, as described below. This semiconductor package 4 includes one or more semiconductor switches 40 with the associated load and control busbars (not shown), as known from the prior art. The semiconductor switches 40 can be configured as topological switches or as half-bridges. On the underside of the semiconductor switch(es) 40, which is provided for thermal and (via the load and control busbar) electrical connection, a first layer of thermally and electrically conductive material such as copper 41-1 is provided. The area of ​​this layer is larger than the area of ​​the semiconductor switch 40, thus completely covering and extending beyond it, as shown in [reference missing]. Fig. 2. On the top side of the semiconductor switch 40, a second layer made of thermally and (via the load and control busbars, the control busbars being represented by the source, which is also used as an electrical potential for the gate) electrically conductive material such as copper 41-2 is provided in a designated area for thermal and electrical connection, which can also (optionally) be thermally connected to the semiconductor switch 40 via a thermally conductive intermediate element 41-3, which is preferably made of the same material as the second layer 41-2. The area of ​​the second layer made of thermally and electrically conductive material such as copper 41-2 is also larger than the area of ​​the semiconductor switch 40, so that it also completely covers it and projects beyond the semiconductor switch 40, as also shown in Fig. 2 can be seen. This arrangement consisting of semiconductor switch 40 with the associated load and control busbar, as well as the two layers of thermally and electrically conductive material such as copper 41-1, 41-2 and optionally the intermediate element 41-3 is surrounded by an electrically insulating sheathing 42 such as a mold, so that the electrical potentials are isolated from each other and the ingress of moisture towards the semiconductor switch 40 is prevented.

[0025] The load and control rails can be designed as part of components 41-1 and 41-2 or connected to them. These areas may not be part of the cooling path and are therefore not shown in the figures. Furthermore, the control rails can be routed separately between 41-1 and 41-2 or parallel to these surfaces.

[0026] The casing 42 leaves a portion of the load and control busbars exposed for electrical and signal contact, respectively; that is, a portion of the load and control busbars protrudes from the casing 42 to establish an electrical and / or signal connection with the semiconductor switch 40. It also leaves the outer surface of the layers made of thermally and electrically conductive material, such as copper 41-1 and 41-2, exposed, allowing a heat sink 2 to be attached. Thus, a novel semiconductor package 4 has been created, which, unlike prior art semiconductor packages 4 that can be cooled on both sides, does not require a layered structure of copper 41, ceramic 42, and copper 41.

[0027] The described semiconductor package 4 can be contacted directly with a heat sink 2 such as a base plate by connecting the heat sink 2 to the respective layer of thermally and electrically conductive material such as copper 41-1, 41-2 by means of a solid connection, e.g. by sintering or soldering.

[0028] In a further embodiment, an additional insulation package 5 is provided, which is connected to at least one of the layers of thermally and electrically conductive material such as copper 41-1, 41-2 of the semiconductor package 4 by means of a solid-state bond. Advantageously, two insulation packages 5 are provided, each of which is connected to one of the layers of thermally and electrically conductive material such as copper 41-1, 41-2 by means of a solid-state bond, as shown in Fig. 3 indicated. Thus, double-sided cooling of the semiconductor package 4 is achieved.

[0029] The insulation package 5 is formed as a layered structure of thermally and electrically conductive material such as copper 51-1, electrically insulating material such as ceramic 50, and thermally and electrically conductive material such as copper 51-2, essentially as, for example, a DBC or AMB printed circuit board. Each insulation package 5 is bonded on one copper side (here layer 51-1) to a layer of copper 41-1, 41-2 of the semiconductor package 4 by means of a solid-state bond, covering as much of the surface as possible, so that a semiconductor module 1 results, as shown in Fig. 3. In one embodiment, the area of ​​the layers of thermally and electrically conductive material such as copper 41-1, 41-2 of the semiconductor package 4 corresponds to the area of ​​the layers of thermally and electrically conductive material such as copper 51-1, 51-2 of the insulation package 5 to be connected thereto.

[0030] In an advantageous embodiment, the insulation package 5 is similar to that in Fig. 2 Semiconductor package 4 shown surrounded by an electrically non-conductive cladding 52, as in Fig. 3 shown. A component enclosed in mold is suitable for implementing the air and creepage distance requirements of the overall system.

[0031] In Fig. Figure 3 shows that the submodules semiconductor package 4 and (jacketed) insulation package 5 of semiconductor module 1 do not have the same width. They can also have the same width if this makes more sense from a manufacturing perspective. It is important that the copper surfaces to be connected can be positioned as precisely as possible on top of each other during assembly. It is also important that the clearance and creepage distances are maintained, which depends, among other things, on whether the insulation packages 5 have a jacket 52.

[0032] An insulation package 5 can also be made larger so that it extends over more than one semiconductor package 4, for example it is connected to several semiconductor packages 4.

[0033] Preferably, the insulation packages 5 arranged on the underside of the semiconductor package 4 have the same structure as the insulation packages 5 arranged on the top side of the semiconductor package 4, i.e., they are formed identically. Thus, only two different submodules are needed to produce the described novel semiconductor module 1 that can be cooled on both sides.

[0034] In the concept according to the invention, the classic semiconductor package is divided into several submodules, one of which represents a novel semiconductor package 4, and the other is formed as an isolation package 5.

[0035] Several advantages can be achieved through the proposed new semiconductor package 4 or semiconductor module 1. One advantage is that the semiconductor switches 40 of the semiconductor package 4, which is manufactured separately from any isolation package 5, can be tested for functionality before being contacted with an isolation package 5 or directly with a heat sink 2.

[0036] Furthermore, the thickness of the semiconductor packages 4 can vary due to the inherent tolerances in the manufacturing of the semiconductor switches 40 and the layers of thermally and electrically conductive material such as copper 41-1, 41-2. Dividing the components into submodules allows for simple post-processing, in particular sorting the submodules according to their height, so that a very small tolerance range in height as well as planarity of the overall module can be achieved. This enables a sintered or soldered assembly of several semiconductor packages 4 or semiconductor modules 1 onto the heat sink 2, unlike in the prior art.

[0037] The variable design with multiple submodules allows for sorting into those with the same or similar height, so that they can be installed together in one inverter, which means that the required tolerance compensation to the heat sink 2 can be lower than before.

[0038] The proposed semiconductor packages 4 or semiconductor modules 1 are advantageously used in an inverter of a power electronics unit, preferably used in an electric drive of a vehicle comprising a three-phase electric motor and a battery. The power electronics unit includes a multi-phase inverter and is connected to the electric motor and battery to convert the direct current received from the battery into alternating current usable by the electric motor. An electronic control unit (ECU) is provided as part of the power electronics unit to control the inverter. The ECU is connected to the electric motor for its control and regulation and to the inverter. The electric motor is, in particular, an electric axle drive.

[0039] Advantageously, a vehicle, such as a passenger car or a commercial vehicle, has at least one such drive system. The vehicle is, in particular, a commercial vehicle like a truck or a bus, or a passenger car. The power electronics module (i.e., the power electronics) comprises a DC / AC inverter with the described structure. It may also include an AC / DC rectifier, a DC / DC converter, a transformer, and / or another electrical converter, or a part thereof. Specifically, the power electronics module serves to supply power to an electric machine, for example, an electric motor and / or a generator. List of reference symbols 1 semiconductor module 2 heat sinks 3 Cooling medium 4 semiconductor package 40 semiconductor switches 41-1, 41-2 layer of copper 41-3 thermally conductive intermediate element (copper) 42 Sheathing 5 Insulation Package 50 ceramics 51 copper 52 Sheathing

Claims

[1] Semiconductor module (1) formed from a semiconductor package (4) and at least one insulation package (5) attached to one of the layers of thermally and electrically conductive material (41-1, 41-2) of the semiconductor package (4), which insulation package is formed in a sandwich-like manner from a layer (51-1) of a thermally and electrically conductive material attached to one of the layers of thermally and electrically conductive material (41-1, 41-2), followed by a layer (50) of a thermally conductive and electrically insulating material, followed by a layer (51-2) of a thermally and electrically conductive material, which is designed to provide a thermal connection to the outside, wherein the semiconductor package (4) has at least one semiconductor switch (40) with associated load and control busbars, wherein - on the underside of the semiconductor switch(es) (40) in a region provided for thermal and electrical connection, a first layer of thermally and electrically conductive material (41-1) is arranged, the area of ​​which is larger than the area of ​​the semiconductor switch (40), and - on the top side of the semiconductor switch (40), in a region provided for this purpose for thermal and electrical connection, a second layer of thermally and electrically conductive material (41-2) is arranged, the area of ​​which is larger than the area of ​​the semiconductor switch (40), wherein the semiconductor switch (40) with associated load and control busbars and the layers of thermally and electrically conductive material (41-1, 41-2) are surrounded by an electrically insulating sheath (42) in such a way that in each case an outer surface of the layers of thermally and electrically conductive material (41-1, 41-2) remains free in order to provide a thermal and electrical connection to the outside. [2] Semiconductor module (1) according to claim 1, wherein a thermally and electrically conductive intermediate element (41-3) is arranged on the semiconductor package (4) between the semiconductor switch (40) and the second layer of thermally and electrically conductive material (41-2), which intermediate element provides a thermal and electrical connection of the second layer of copper (41-2) to the semiconductor switch (40). [3] Semiconductor module (1) according to claim 1 or 2, wherein two insulation packages (5) are provided, each of which is fastened with a layer (51-1) of a thermally and electrically conductive material to one of the layers of thermally and electrically conductive material (41-1, 41-2) of the semiconductor package (4) by means of a solid connection. [4] Semiconductor module (1) according to claim 1, 2 or 3, wherein each insulation package (5) is surrounded by an electrically non-conductive sheath (52) such that an outer surface of the layers of thermally and electrically conductive material (51-1, 51-2) remains free, each of which provides a thermal and electrical connection to the outside. [5] Semiconductor module (1) according to claim 4, wherein at least one insulation package (5) is a DBC or AMB circuit board. [6] Single-phase or multi-phase module, comprising - a base plate serving as a heat sink (2), and - at least one semiconductor module (1) according to one of claims 1 to 5, attached to the base plate and per phase, and - DC and AC busbars electrically contacted on the semiconductor package(s) (4) or semiconductor module(s) (1) and with associated power connections. [7] Single-phase or multi-phase module according to claim 6, wherein a second heat sink (2) is arranged on a side of the semiconductor package(s) (4) or semiconductor modules (1) opposite the base plate. [8] Power electronics for operating a three-phase electric motor of a vehicle, the power electronics comprising: - an inverter formed from several single-phase or one multi-phase module according to claim 6 or 7, and - at least one electronic control unit connected to the electric motor for its control and regulation and to the inverter. [9] Electric drive of a vehicle, comprising a three-phase electric motor and an accumulator, as well as power electronics connected to both according to claim 8.

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