Semiconductor power module and method for connecting it to other electrical components

Abstract

Semiconductor power module (1) comprising a substrate (3) on which a circuit pattern and electrical components are applied, wherein the substrate is partially covered by a housing (2) and projects outwards from the housing (2) such that at least two adjacent substrate terminals (4), which are applied to the substrate (3) and are provided for the electrical connection of the semiconductor power transistor module (1), project outwards from the housing (2), wherein the at least two adjacent substrate terminals (4) are provided for conducting electrical currents of different electrical potentials, characterized in that the at least two adjacent terminals (4) are provided for being permanently electrically connected to terminals of other power electronic units by means of a metallurgical connection, and are spaced apart from each other.which is smaller than the required distance to prevent leakage currents and / or spark discharges, which is necessary when air is used as an electrically insulating material.

Description

[0001] The present invention relates to the field of semiconductor power modules, in particular silicon carbide semiconductor power modules.

[0002] Semiconductor power modules typically comprise one or more semiconductors or semiconductor switches, such as IGBTs, MOSFETs, or other power-controlling semiconductors. These semiconductors and other electrical components are usually mounted on a substrate onto which a circuit pattern is applied, for example, by printing or etching. These semiconductors are typically enclosed in a package, often a sealed enclosure, but which can also be a mountable box or the like. Conductors connect the semiconductors, semiconductor switches, and electrical components located inside the package to other power electrical devices, such as busbars or the like. These conductors include at least one terminal that protrudes from the package of the semiconductor power module.Screw connections are commonly used in this field for connecting to a terminal of another power electronic device. However, screw connections represent a labor-intensive and therefore costly method of connecting electrical devices, especially when automated connection is preferred, for example, when semiconductor power modules are assembled with other power electronic modules to build a power electronic assembly or a power module assembly group.

[0003] It is therefore an object of the present invention to provide a semiconductor power module that can be connected to any other power electronics unit in a simpler manner, thereby saving costs and assembly time during the assembly of the semiconductor power module with other power electronics units. In general, the connection between the semiconductor power module and the other power electronics unit should be reliable and robust.

[0004] The problem stated above is solved by a semiconductor power module according to claim 1, comprising a substrate on which a circuit pattern is mounted, and further comprising electrical components that are mounted and connected in the circuit pattern on the substrate. These further electrical components can be resistors, transistors, conductors, or any other electrical components known to a person skilled in the art. According to the invention, the substrate with the circuit pattern and the electrical components is partially covered by a housing, such that the substrate and part of the circuit pattern project outwards from the housing.At least two terminals, formed on the substrate for an electrical connection of the semiconductor power module, protrude from the housing to enable permanent, metallurgical connection with terminals of other power electronic devices or modules. These at least two terminals are designed to conduct electrical currents of differing potentials between the outer surface of the housing of the semiconductor power module according to the invention and the electrical components arranged inside the housing.

[0005] These at least two terminals are preferably arranged at a distance from each other that is smaller than the creepage distance or gap provided by air as an electrical insulator. When using air as an electrical insulator between two adjacent terminals that each have different electrical potentials, a minimum distance must be maintained to prevent electrical leakage or creepage currents, or even short circuits. Since the terminals of the semiconductor power module according to the invention are intended to be permanently connected to terminals of other electrical devices via a metallurgical bond, and these permanently connected terminals are subsequently covered with an electrically insulating material, the distance between adjacent terminals with different electrical potentials can be reduced.To avoid electrical leakage currents, creepage currents or even short circuits after the material-bonded connection, the materially bonded connections are covered with electrically insulating material, such as a varnish or a synthetic resin or the like.

[0006] By reducing the creepage distance or the gap between two adjacent terminals, a smaller semiconductor power module design is achieved, with dimensions smaller than those of semiconductor power modules known from the prior art that use screw connections for connection to terminals of other electrical devices. This is achieved because the metallurgical connection is a permanent method for joining two terminals, and accessibility of the connection points for potential disconnection is not required. Therefore, the electrical connection of the semiconductor power module according to the invention is designed to be covered. Furthermore, the inductance of the arrangement is reduced by decreasing the distance between the electrical conductors.

[0007] Another advantage is that the circuit connections protruding from the housing can be directly connected without the need for separate conductors, as is usually the case in prior art. This significantly reduces the number of connection points, resulting in a semiconductor power module with reduced electrical resistance and connection inductance. This enables faster switching characteristics with the semiconductor used, especially when a silicon carbide semiconductor or another wide-bandgap semiconductor is employed.Furthermore, lower electrical resistance leads to less heat generation within the semiconductor power module, so less cooling is required, or, put another way, so that more electrical current can be passed through the semiconductor power module when the same cooling is applied.

[0008] However, conventional metallic conductors can also be used to conduct electrical currents between an inner and an outer surface of the housing of the semiconductor power module according to the invention, depending on the architecture and the connection options that the semiconductor power module should provide, such as for a top-side connection. Since the substrate connections are formed directly by the circuit pattern on the substrate, these substrate connections are typically arranged in a single plane, with different electrical potentials being connected to either a single connection or multiple connections. The use of multiple connections directly bonded to a substrate can be advantageous, for example, when heat needs to be dissipated over a larger surface area.Here, connections with different potentials can be arranged alternately.

[0009] In a preferred embodiment, the terminals for connecting the semiconductor power module are arranged on a substrate such that these terminals protrude from an outer surface of the housing. This allows an electrical connection to be implemented directly and easily in the plane of the substrate, for example as a plug connection.

[0010] Since the connections for electrically connecting the semiconductor power module according to the invention are provided directly on the substrate, the preferred method for connecting these connections to connections of other power electronic devices is a metallurgical bond. The substrate is usually made of a ceramic material that is pressure-sensitive. Therefore, screwing should be avoided. Thus, the preferred method for connecting the semiconductor power module according to the invention to any other power electronic unit or device is a metallurgical bond, such as gluing, soldering, or welding, in particular, for example, laser welding, ultrasonic welding, friction welding, or spot welding.

[0011] Since a metallurgical bond is preferred for connecting the semiconductor power module according to the invention to any other power electronic device, a further advantage can be exploited. An inherent property of the metallurgical bond is the permanent connection of the terminals, which cannot be disconnected without destroying the connection structure. In comparison, a screw connection can be loosened and tightened several times without sustaining damage. When using a metallurgical bond, the connection can only be broken by damaging the metallurgical bond between the two terminals. However, this can be advantageously mitigated by coating the metallurgical bond, at least at the connection points, with a varnish or a synthetic resin, which helps to increase the electrical insulation of adjacent terminals.Therefore, in the semiconductor power module according to the invention, the required creepage distance and / or gap between adjacent terminals can be considerably reduced compared to semiconductor power modules with terminals designed for screw connections. Screw connections should be detachable; therefore, no lacquer or synthetic resin should be applied to the screw connection so that it remains accessible and detachable at all times.

[0012] Therefore, in semiconductor power modules according to the prior art, a creepage distance and / or gap between adjacent terminals is required, which is such that short circuits via the air do not occur. In contrast, the creepage distances and / or gaps between adjacent terminals of the semiconductor power module according to the invention can be considerably reduced, since lacquer or synthetic resin can be applied to cover the metallurgically bonded connection, which preferably represents a much better electrically insulating material than air. Consequently, the semiconductor power modules according to the invention can be designed with smaller external dimensions and are suitable for use in space-critical applications, such as vehicle powertrains, particularly in the automotive industry.The aforementioned aspects are even more relevant for electrical applications in the aerospace industry. This also applies analogously to the fact that some of the conductors used in the prior art are superfluous, so that the volume occupied by the semiconductor power module according to the invention can be further reduced.

[0013] Furthermore, since the number of conductors can be considerably reduced and sometimes even completely eliminated, the semiconductor power module according to the invention can be made thinner or have a reduced thickness, as no metallic conductor needs to be routed to an outside of the housing. This is usually done via three-dimensional conductors to carry the electrical components mounted on the circuit pattern of the substrate. Therefore, the architecture of the semiconductor power module according to the invention can be implemented in a simpler manner, as no complicated three-dimensional conductor structure is required to provide electrically usable connections on an outside of the housing of the semiconductor power module.In the semiconductor power module according to the invention with connections in only one plane, a stacked arrangement of a plurality of semiconductor power modules is also possible, since in particular accessibility to the connection point is no longer necessary due to the material-bonded connection.

[0014] Nevertheless, the connections of a semiconductor power module can also be distributed in two or more layers, for example, for layer-wise interconnection. In general, a more compact architecture of the semiconductor power module itself and of power electronics arrangements can be achieved with the semiconductor power module according to the invention.

[0015] A further advantageous solution is achieved with the semiconductor power module according to the invention by reducing the number of element-to-element connections, in particular those between conductors and the circuit pattern and / or the semiconductor and / or other electrical components, thus reducing influences that impede conductivity. In other words, the inductance of the semiconductor power modules according to the invention is reduced, while the conductivity is increased compared to semiconductor power modules known from the prior art.

[0016] The aforementioned advantage of increased conductivity is further enhanced by the fact that the terminals protruding from the housing of the semiconductor power module are not connected by means of a screw connection; that is, no opening is provided for receiving a connecting screw, which would negatively affect the conductivity of such a connection. Since a metallurgical bond is the preferred connection method of the semiconductor power module according to the invention with other power electronic devices, and since a small number of conductors are used to conduct electric current, the semiconductor power module according to the invention achieves a very low inductance.

[0017] Furthermore, by using one or more semiconductor power modules according to the invention, multi-part power electronics assemblies can be provided which have an overall lower inductance, which is advantageous for a high switching rate. Such power electronics assemblies are achieved simply by using at least one semiconductor power module according to the invention and connecting its terminals, which protrude from the housing, to corresponding terminals of at least one other power electronics device. According to the invention, the terminals are permanently electrically connected to terminals of other electrical devices by means of a metallurgical bond. A metallurgical bond can preferably be produced by welding, ultrasonic welding, friction welding, laser welding, soldering, sintering, or bonding.However, any other method for material bonding known to a person skilled in the art in this field is also covered by the concept of the invention.

[0018] After the material-bonded connection of the terminals of at least one semiconductor power module according to the invention with terminals of at least one other power electrical device to form a power electrical arrangement, the material-bonded terminals can be covered, for example, with a synthetic resin or varnish to protect the material-bonded connection, and apart from that, or additionally, the varnish or synthetic resin used electrically insulates the material-bonded connections, thereby increasing the protection against short circuits and allowing two adjacent material-bonded terminals to be arranged closer together than would be allowed if air were the only electrically insulating material between two adjacent material-bonded terminals.The latter is the case with screw-connected terminals of power electrical devices, which are known in the prior art. Covering the connection area also avoids any problems that could arise from contamination or conductive particles over the lifetime of the assembly.

[0019] In the manufacture of such a power electrical assembly as described above, for example as part of a vehicle's electric powertrain, the electrical devices can be arranged compactly because the corresponding terminals protruding from their housings can be connected by means of a metallurgical bond, which typically requires less space than a screw connection. After the metallurgical bond has been carried out, such as by any type of welding, soldering, sintering, or bonding, the metallurgically bonded terminals are preferably covered with an electrically insulating synthetic resin or lacquer to prevent short circuits.

[0020] The aforementioned and other advantageous aspects of the semiconductor power module according to the invention will become apparent from the description of preferred embodiments, which is illustrated by the drawings. These exemplary embodiments, however, do not limit the scope of the invention and can be adapted and modified by a person skilled in the art without deviating from the scope of the concept according to the invention. The drawings show: Fig. 1 a perspective view of an embodiment of a semiconductor power module according to the invention; Fig. 2 a power electrical arrangement according to the invention; Fig. 3 the power electrical arrangement of Fig. 2, whose electrical connection is covered with a covering material; and Fig. 4 a flowchart illustrating the inventive method for connecting a semiconductor power module according to the invention with another electrical unit.

[0021] Fig. Figure 1 shows a perspective view of an embodiment of a semiconductor power module according to the invention. 1 , which is a substrate 3 The substrate comprises a circuit pattern on which a circuit diagram is mounted and on which (not shown) electrical components are mounted. 3 is partially enclosed in a housing 2 covered and stands away from the casing 2 externally. In this embodiment, there are six connections. 4 , which are on the substrate 3 are attached to the outside of the housing and are for the permanent electrical connection of the semiconductor power module 1with connections to other power electronic units or devices. This connection is preferably achieved by a material-bonded joining process, such as welding, in particular laser welding, friction welding or ultrasonic welding, or by soldering or gluing.

[0022] The connections 4 are for conducting electrical current to the inside of the housing 2 arranged electrical components and away from them, whereby it is possible that each connection 4 conducts different electrical potentials. In the Fig. In the embodiment shown in section 2, the connections shown can be 4 either two different electrical potentials, e.g. negative and positive current, which is generated by adjacent terminals 4The connections can be arranged alternately or in any other layout. In a further embodiment, all connections can carry the same electrical potential or even up to six different electrical potentials, whereby the electrical potentials do not necessarily have to remain constant over time during operation of the power electronics module. A person skilled in the art will recognize that neither the number of connections 4 , which are from the casing 2 stand out, is limited, nor is the number of electrical potentials that come from the connections 4 The ability to be guided is limited. This also includes the possibility that the substrate 3 with specially designed connectors 4 It may also protrude from the casing on other sides.

[0023] The in Fig. 1 shown connections 4are arranged at a lateral spacing that is smaller than would necessarily be required if air were used as an insulating material, in order to avoid creepage currents and / or electrical leakage currents or even short circuits. According to the invention, this can be achieved because the connections 4 connected to terminals of other electrical devices via a material-bonded connection, preferably the connected terminals being subsequently covered with an electrically insulating material that has better insulating properties than air.

[0024] Fig. Figure 2 shows a power electronics arrangement 10 according to the invention, for which a material-bonded connection is used to connect the terminals 4 of the semiconductor power module 1 with another electrical device 5 , for example with a busbar module 7, is used. The materially bonded pairs of connections are shown for illustrative purposes only. 6 before applying electrically insulating material 12 shown in the connection area. The connections are also shown for illustrative purposes only. 4 of the exemplary busbar module 7 , as an embodiment for a further electrical device 5 , as separate connections 4 depicted, which are also shown in the same way as the connections 4 of the semiconductor power module according to the invention 1 could be realized, i.e., as connections 4 , which are formed as part of the circuit pattern on a substrate that protrudes outwards from the corresponding busbar module housing.

[0025] As from Fig. As can be seen in section 2, a plurality of semiconductor power modules could be used. 1laterally side by side in the manner according to the invention with the further electrical devices 5 can be connected, even a semiconductor power module 1 on other semiconductor power modules 1 in a stack. This is because the individual pairs of connected terminals 6 after the material-bonded connection of the corresponding connections 4 no longer need to be accessible, as would be the case if the connections were made to connect the ports. 4 A screw connection would have been selected for them.

[0026] Fig. Figure 3 shows the embodiment of the power electronics arrangement according to the invention. 10 from Fig. 2, wherein the connection area with the pairs of materially bonded connections 6 with an insulating material 12The material shown is a semi-transparent covering, used for illustrative purposes only. It is understood that any other suitable insulating material could be applied, such as a varnish, resin, or silicone gel, and it is irrelevant whether it is transparent or opaque. By applying insulating material 12 , which refers to the connection area of ​​the materially bonded connections 6For example, when applied by casting or encapsulation, the lateral and / or vertical distance between two adjacent pairs of terminals can be considerably reduced compared to uncovered pairs of connected terminals where air is the insulating material, in order to prevent electrical creepage and / or leakage currents or even short circuits. Therefore, according to the invention, the architecture of connected pairs of terminals can be 4 They can be designed to be much more compact, as the distance between them is reduced.

[0027] Fig. Figure 4 shows a flowchart illustrating the inventive method for connecting a semiconductor power module according to the invention with a further electrical unit, comprising the following steps: in step S1 the semiconductor power module 1 and another electrical device 5, each with their respective housings 2 the aforementioned connections 4 provided. Preferably the connections are 4 of the two devices 1 and 5 arranged in such a way that the connections 4 , which are to be electrically connected to each other, overlap at least partially.

[0028] In step S2 will the connections 4 of the semiconductor power module 1 with the connections 4 the further electrical device 5 connected by means of a material-bonding joining process, such as welding, in particular laser welding, friction welding and ultrasonic welding, or by soldering or gluing.

[0029] In step S3 The materially bonded connections will be 6 of the two electrical devices 1 and 5with an electrically insulating material 12 covered, which may be a varnish, a synthetic resin, or the like. In a preferred embodiment, the entire connection area, i.e., the gap between the housings, is covered. 2 of the two electrical devices 1 and 5 with encapsulation material, for example the material that is also used to form the housings 2 the electrical devices 1 and 5 is used, filled (see Fig. 3) Filling the gap between the electrical devices provides greater mechanical stability between the housings. 2 of the two electrical devices 1 and 5 This relieves the materially bonded connections of bending forces, which can occur, for example, when the semiconductor power module 1is not supported vertically and the weight of the semiconductor power module 1 would have to be supported by the materially bonded connections.

[0030] Another positive aspect of filling at least the entire width of the gap between the two electrical devices is that a more compact and robust power electronics arrangement is formed, which is easier to handle, for example, in an automated handling process. Reference symbol list 1 semiconductor power module 2 cases 3 Substrat 4 connections 5 electrical device 6 materially bonded connections 7 busbar module 8 ladders 10 Power electrical arrangement 12 insulating material S1 step 1 S2 step 2 S3 step 3

Claims

[1] Semiconductor power module (1) comprising a substrate (3) on which a circuit pattern and electrical components are mounted, wherein the substrate is partially covered by a housing (2) and projects outwards from the housing (2) such that at least two terminals (4) mounted on the substrate (3) and provided for the electrical connection of the semiconductor power transistor module (1) project outwards from the housing (2) in order to be permanently electrically connected to terminals of other power electronic units by means of a metallurgical connection, wherein the at least two terminals (4) are provided for conducting electrical currents of different electrical potentials, and wherein the two terminals (4) are separated by a smaller distance from each other than the required creepage distance and / or gap required when air is the electrically insulating material. [2] Semiconductor power module (1) according to claim 1, wherein for each electrical potential to be connected to the module two or more terminals (4) are provided on the substrate (3) and protrude outwards from the housing (2). [3] Semiconductor power module (1) according to one of the preceding claims, wherein at least one of the terminals (4) can be connected to a terminal of a busbar. [4] Semiconductor power module (1) according to one of the preceding claims, wherein the module comprises a conductor (8) having at least two terminals, wherein a first inner terminal of the conductor (8) is connected within the housing (2) to the circuit pattern or to one of the electrical components and a second outer terminal (4) of the conductor (8) extends outwards from the housing (2). [5] Semiconductor power transistor module (1) according to claim 4, wherein the second terminal (4) of the conductor (8) protrudes from the housing (2) in a plane that differs from that of the substrate (3) and / or on another side of the housing (2). [6] Semiconductor power transistor module (1) according to any one of the preceding claims, wherein the module (1) comprises a silicon carbide semiconductor and / or a wide bandgap semiconductor. [7] Semiconductor power transistor module (1) according to one of the preceding claims, wherein the substrate (3) is a ceramic substrate. [8] Semiconductor power transistor module (1) according to one of the preceding claims, wherein the substrate (3) is an organic substrate. [9] Semiconductor power transistor module (1) according to any one of the preceding claims, wherein the housing (2) is an encapsulated housing. [10] Power electrical arrangement comprising a semiconductor power module according to any one of claims 1 to 9 and a further electrical unit having outwardly projecting terminals, wherein the corresponding terminals are permanently electrically connected to each other by means of a material-bonded connection. [11] Power electrical arrangement (10) according to claim 10, wherein the material-jointed connection is obtained by welding, ultrasonic welding, friction welding, laser welding, soldering, sintering or gluing. [12] Power electrical arrangement (10) according to claim 10 or 11, wherein the materially bonded terminals (4) are covered with an insulating material (12). [13] Power electrical arrangement (10) according to claim 12, wherein the insulating material (12) is an electrically insulating material, for example a synthetic resin or a varnish. [14] Method for connecting a semiconductor power module (1) according to any one of claims 1 to 9 and a further electrical device (5), comprising the following steps: - Provide the semiconductor power module and another electrical device (5) with terminals (4) that protrude from corresponding housings (2) so that the terminals (4) to be electrically connected overlap at least partially; - electrical connection, by means of a material-bonded connection, of the terminals (4) of the semiconductor power module (1) with the terminals (4) of the further electrical device (5); - Covering the materially bonded connections (6) with an electrically insulating material (12). [15] Method according to claim 14, wherein the material-joining is carried out by ultrasonic welding, friction welding, laser welding, soldering, sintering or gluing. [16] Method according to claim 14 or 15, wherein a gap between the housing (2) of the semiconductor power module (1) and the housing (2) of the further electrical device (5) is filled with insulating material (12) at least over the width of the gap.

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