POWER MODULE WITH COOLING CHANNEL

Abstract

A power module (1) comprises a substrate (2) for power semiconductors and a housing (10). An electrically insulating plate (6) is provided between the substrate (2) and the housing (10) of the power module (1). The plate (6), which is prestressed with at least one elastic element (9), allows an optimal gap (5) to be maintained even during operation and regardless of temperature, in order to prevent contact corrosion.

Description

State of the art

[0001] DE 10 2007 046 349 A1 relates to an arrangement for cooling a power semiconductor module. The arrangement comprises a container for the inlet of a coolant with a heat-conducting plate. One side of the heat-conducting plate is in contact with the coolant.

[0002] DE 10 2021 207 284 A1 relates to a pulse-controlled inverter with a central cooling device. A cooling fluid channel is provided for heat dissipation. The cooling fluid channel is defined by a retaining plate and a boundary, which rests against the retaining plate with a seal.

[0003] The power electronics can be an inverter, for example. The inverter controls and monitors the electric motor and ensures that the electric drivetrain receives the torque and speed required. The inverter also converts the battery's DC voltage into the AC voltage required by the electric motor.

[0004] EP 3 836 206 A1 discloses a cooling device for semiconductor switching elements. A cooling channel carrying a coolant is formed between a first main wall and a second main wall. Furthermore, a first side wall and a second side wall delimit the cooling channel.

[0005] With the current cooling structure for a power module with power semiconductors (inverters), thermal expansion during operation can still lead to unwanted contact between the aluminum housing and the nickel-plated cooler. This results in unwanted contact corrosion, which damages the housing, the cooler, and / or possibly other neighboring components. Furthermore, very tight tolerances with respect to the housing are required during production. A defined gap of, for example, 0.05 mm to 0.2 mm should always exist between the housing and the power module carrier. This tight tolerance therefore necessitates expensive and complex manufacturing. An upward deviation from the tolerance leads to a loss of performance of the power module. Brief description of the invention

[0006] It is therefore an object of the invention to provide a power module with a cooling channel that is simple and cost-effective to manufacture and at the same time avoids corrosion during operation of the power module.

[0007] The above object is achieved by a power module with a cooling channel comprising the features of claim 1.

[0008] According to one embodiment of the invention, a power module comprises a carrier for power semiconductors and a housing (inverter housing). A cooling channel having a cooling structure is defined between the carrier and the housing. According to the invention, an electrically insulating plate is provided between the carrier and the housing of the power module. Furthermore, at least one elastic element is provided that mechanically prestresses the plate against the cooling structure. The advantage of the invention is that expensive manufacturing of the housing is avoided due to the tight tolerances that cannot be maintained, and contact corrosion during operation between the cooling structure and the housing no longer occurs due to the different materials.

[0009] In a preferred embodiment, the plate is made of plastic. The plastic prevents corrosion between the carrier and the power module housing.

[0010] According to a further embodiment of the invention, the plate has several spacer tabs on its upper side. Typically, the spacer tabs and the electrically insulating plate are made of the same material.

[0011] The advantage of the spacers is that the ideal gap is always maintained, even when the heat builds up during operation, because at least one elastic element, such as at least one metal spring, compensates for the play between the housing, the plate, and the cooling structure. This reduces mechanical stresses in the housing, and the cooling performance always remains consistent.

[0012] According to an advantageous embodiment of the invention, the electrically insulating plate is sealed against the housing with an O-ring. According to an advantageous embodiment of the invention, the O-ring is omitted. A lateral gap is formed between the electrically insulating plate and the housing, defining a bypass. The bypass thus formed has the advantage that an external bypass, as in the prior art, can be omitted. Short description of the drawings

[0013] The invention is explained in more detail below with reference to the accompanying drawings. Fig. 1 shows a sectional view of an embodiment of a power module according to the prior art. Fig. 2 shows an enlarged view of the Fig. 1 area marked with a dashed circle. Fig. 3 shows a sectional view of a power module according to an embodiment of the invention. Fig. 4 shows an enlarged view of an embodiment of the Fig. 3 lateral area marked with a dashed circle between the electrically insulating plate and the housing. Fig. 5 shows an enlarged view of another embodiment of the lateral region between the electrically insulating plate and the housing. Detailed description of the embodiments and drawings

[0014] Fig. Figure 1 shows a sectional view of an embodiment of a power module 1 according to the prior art. The power module 1 comprises a carrier 2 for power semiconductors and a housing 10. Between the carrier 2 and the housing 10, a cooling channel 20 is formed, which has a cooling structure 4, for example, with a plurality of cooling fins 14. The cooling structure 4 requires very tight tolerances with respect to the housing 10, since, on the one hand, the requirement for a compact power module 1 must be met, and, on the other hand, contact corrosion must be avoided. To solve these problems, according to the prior art, a cooling channel 20 is formed between the housing 10 and the cooling structure 4, as shown in Fig. 2, a defined gap 5 is provided, which establishes a separation between the cooling structure 4 and the housing 10. As already described above, the cooling structure 4 and the housing 10 are usually constructed from different metallic materials. Without such a gap 5, contact between the cooling structure 4 and the housing 10 would occur, resulting in undesirable contact corrosion, which would damage the housing 10, the cooling structure 4 and / or possibly also other adjacent components. For a schematic representation of the gap 5, the Fig. 1 marked area 30 in Fig. 2 is shown enlarged. The gap 5 can, for example, be 0.05 mm to 0.2 mm to define a separation between the cooling structure 4 and the housing 10.

[0015] In addition, a seal 3 is provided between the carrier 2 and the housing 10 so that the system is sealed against internal and / or external influences.

[0016] Due to thermal expansion, unwanted contact between the cooling structure 4 and the housing 10 can still occur during operation. Since the housing 10 is made of aluminum, for example, and the cooling structure 4 is nickel-plated, contact corrosion still occurs as a result.

[0017] Fig. 3 shows a sectional view of the power module 1 according to an embodiment of the invention. Here, the housing 10 connected to the carrier 2 for power semiconductors is designed such that it accommodates an electrically insulating plate 6. The electrically insulating plate 6 is supported on the housing 10 via at least one elastic element 9 or mechanically prestresses the plate 6 against the cooling structure 4. The at least one elastic element 9 enables tolerance compensation, so that the overall tolerances in the housing 10 can be defined more generously during its manufacture and stresses due to thermal expansion of the cooling structure 4 and the housing 10 are prevented. The housing 10 is usually shaped differently to accommodate the plate 6 than in the prior art according to Fig. 1. In the Fig. In the embodiment shown in Figure 3, two elastic elements 9 are provided on the housing 10, which press against an underside 12 of the electrically insulating plate 6. Although two elastic elements 9 are attached to the housing 10 in the description, this should not be construed as a limitation of the invention. The elastic elements 9, which can be designed as springs, for example, are intended to compensate for the play of the components, such as the housing 10, the cooling structure 4, and possibly also other adjacent components, when heated during operation. Mechanical stresses in the housing 10 are thereby reduced, and the cooling performance of the power module 1 always remains constant.

[0018] According to one embodiment, the electrically insulating plate 6 can be made of a plastic material, which makes the plate 6 particularly easy to manufacture, reduces the weight of the plate 6, and is not susceptible to corrosion. The plastic material of the plate 6 particularly prevents corrosion between the carrier 2 and the housing 10 of the power module 1. In any case, the electrically insulating plate 6 can prevent contact corrosion between the materials of the carrier 2 and the housing 10.

[0019] To create an ideal and well-defined gap 5 (see Fig. 4 or Fig. 5) between the housing 10 and the cooling structure 4, in one embodiment, an upper side 11 of the electrically insulating plate 6 is provided with one or more spacer lugs 7. The spacer lugs 7 are preferably made of the same material as the electrically insulating plate 6. During operation, the gap 5 automatically adapts to the pressure in the cooling channel 20: a higher pressure in the cooling channel 20 causes the elastic elements 9 to be pressed down, thus enlarging the gap 5; in the event of a pressure loss, the elastic elements 9 relax and the gap 5 shrinks.

[0020] Fig. 4 shows an enlarged view of an embodiment of the Fig. 3 with a dashed circle marked lateral area 30 between the electrically insulating plate 6 and the housing 10. As the Fig. 4, according to one embodiment of the invention, an O-ring 8 can be inserted between the electrically insulating plate 6 and the housing 10. The O-ring 8 serves to seal the electrically insulating plate 6.

[0021] Fig. Figure 5 shows an enlarged view of another embodiment of the lateral region 30 between the electrically insulating plate 6 and the housing 10. As the Fig. 5, according to a further embodiment of the invention, a lateral gap 13 can be formed between the electrically insulating plate 6 and the housing 10. The lateral gap 13 provides a defined bypass. The lateral gap 13 is therefore provided instead of the O-ring 8. The advantage of the lateral gap 13 or bypass is that an external bypass, as is usually provided in the prior art, can be omitted. List of reference symbols 1 power module 2 carriers 3 Seal 4 Cooling structure 5 gap 6 plates 7 spacer lugs 8 O-ring 9 elastic element 10 housings 11 Top 12 Bottom 13 lateral distance 14 cooling fins 20 cooling channel 30 area QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2007 046 349 A1

[0001] DE 10 2021 207 284 A1

[0002] EP 3 836 206 A1

[0004]

Claims

[1] A power module (1) comprising a carrier (2) for power semiconductors and a housing (10), a cooling channel (20) arranged between the carrier (2) and the housing (10) and having a cooling structure (4), characterized by an electrically insulating plate (6) arranged between the carrier (2) and the housing (10); and at least one elastic element (9) which mechanically prestresses the plate (6) against the cooling structure (4). [2] Power module (1) according to claim 1, wherein the plate (6) is made of plastic. [3] Power module (1) according to one of the preceding claims, wherein the plate (6) carries a plurality of spacer lugs (7) on an upper side (11). [4] Power module (1) according to one of the preceding claims, wherein the at least one elastic element (9) is a metallic spring. [5] Power module (1) according to one of the preceding claims, wherein the electrically insulating plate (6) is sealed with an O-ring (8) relative to the housing (10). [6] Power module (1) according to one of the preceding claims 1 to 4, wherein a lateral distance (13) defining a bypass is formed between the electrically insulating plate (6) and the housing (10).

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