DE102022201557B3 - Power module assembly and assembly method for the power module assembly - Google Patents

Abstract

Assembly for power modules (1) with at least one power module (2) with a cooling duct (3) with an inlet and outlet (6), the cooling duct (3) being formed by a lower half-shell (4) and an upper half-shell (5) and the line electronics (2) having cooling ribs (7) which protrude through a cutout (5a) into the cooling duct (3), the cooling duct (3) between the power module (2) and the upper half-shell (5) being closed in a materially joined manner.

Description

The invention relates to a unit for power modules with at least one power module with a cooling channel with an inlet and outlet, the cooling channel being formed by a lower half-shell and an upper half-shell and the line electronics having cooling fins which protrude through a cutout into the cooling channel.
The invention also relates to an assembly method for the assembly for power modules.

State of the art

Inverters in the automotive environment contain a so-called power stack as a core element, i.e. power electronic components in a housing.
Switching losses occur when the semiconductor switches of the inverter are actuated, which lead to the semiconductor switches and the power module heating up. Each semiconductor switch or each power module has a maximum operating temperature. If this maximum operating temperature is exceeded, it is possible that the semiconductor switch or the power module will be damaged. Consequently, it is necessary for the semiconductor switch or the power module or other electronic/electrical components, such as resistors, to be cooled. For example, passive heat sinks are used for this purpose, which are made of aluminum and have cooling ribs.

This housing includes a cooling channel and the power semiconductors required to convert direct current into alternating current. In many cases, the cooling channel is designed to be closed off from the power semiconductors. The line semiconductors are applied to the surface of the cooling channel using a suitable method, e.g. by connection via a thermally conductive material, by soldering or sintering, in order to establish the thermal and mechanical connection. The disadvantage here is that further thermal transitions and conductive paths are introduced between the power module and coolant and power semiconductor. As a result, the thermal transition from the heat source to the coolant is worsened, and higher temperatures are therefore often set than is the case with direct cooling.

In addition to these designs, there are also power electronics solutions in which the power semiconductors are already prefabricated with a cooling structure such as ribs. This cooling structure protrudes into the coolant flow in order to extract the thermal energy from the power semiconductors. The connection between the power semiconductor and a cooling channel in the housing is made using a suitable sealing solution, e.g. with an O-ring or a molded seal. It is also known that an assembly for power modules is pressed against the cooling duct by means of additional components specially provided for this purpose in order to achieve the sealing effect and to prevent the assembly for power modules from being lifted off the cooling duct.

These additional components must be considered throughout the procurement, handling and assembly process. The coolant flow is disturbed at several points in a power semiconductor module by the required seals, which on the one hand results in unnecessary pressure loss and on the other hand results in so-called dead water zones. In these zones in the "shadow" of the sealing points, there is hardly any coolant exchange, so that there are local temperature increases.

Another disadvantage of existing solutions is the mostly complex geometric design of the cooling channel. The component and assembly complexity is high, which has a direct impact on costs.
In such a structure, it is also necessary to provide additional elements for fastening the power modules. This includes structures that touch the power modules on one side as well as fastening elements such as screws that preload and hold the structures in place.

The overall high complexity - in particular due to several seals including fastening elements - entails high demands on the necessary safeguards.

From the pamphlet DE 10 2019 202 902 A1 is a unit for power modules with at least one power module and with a cooling duct with an inlet and outlet, the cooling duct being formed by a lower half-shell and an upper half-shell and the line electronics having cooling ribs which protrude through a cutout into the cooling duct, the Cooling channel between the power module and the upper half-shell is closed in a materially bonded manner.

From the DE 10 2019 202 903 A1 and the DE 10 2019 206 262 A1 assembly methods are known, the connection of the upper and lower half-shells not being explained further.

From the DE 10 2013 109 589 B3 it is known to connect the upper half-shell to a lower half-shell and only then to connect the upper half-shell to cooling plates of line modules.

It is therefore an object of the invention to construct a unit for power modules that simply requires a few components that also a easy to connect and efficiently cools the power modules.

Description of the invention

The object is achieved with a unit for power modules with at least one power module and with a cooling channel with an inlet and outlet, the cooling channel being formed by a lower half-shell and an upper half-shell and the line electronics having cooling ribs that protrude through a cutout into the cooling channel , whereby the cooling channel between the power module and the upper half-shell is materially closed.

The upper half-shell has at least one cut-out, which encompasses a frame and/or a groove that is raised to the surface of the upper half-shell.

The assembly for power modules has advantages, since the integral connection takes over the sealing function and seals are therefore not required.

The construction allows fastening structures and fastening elements for the power module to be dispensed with, since the components are also mechanically held in place by the integral connection and do not have to be additionally fastened.

A material connection is characterized by the fact that the components to be connected are connected to one another by atomic or molecular connections. This also explains the fact that this type of connection can only be released by destroying the connection means. Within this group, the joining processes can be further differentiated according to whether the connection is made using additional materials of the same type or of a different type. Soldering, welding and gluing are the most well-known joining processes in this group.

Furthermore, the upper half-shell and the lower half-shell are connected to one another along the outer edge of the two half-shells with a form-fitting connection or a material-locking connection. If the edge of the cooling channel is flanged, a form-fitting process is used.

The lower half-shell has a peripheral flange on the outer edge for connection to the upper half-shell.

It is advantageous that the material connection is soldered, welded or glued.

The integral connection between the power module and the upper half-shell consists of a circumferential contact point between the substrate and the power module.

Another positive effect comes into play with the soldered connection: A good thermal path is created from the substrate of the power module via the soldered connection into the upper half-shell of the cooling channel. This allows additional heat to be dissipated from the power module, which further reduces the power module temperature.

It is advantageous that the cooling channel is a continuous space into which only the cooling fins protrude.

By reducing the obstacles in the coolant flow in the cooling channel, there is less "unnecessary" pressure loss.

Due to the thin walls of the metallic, deep-drawn half-shell, there is only a minimal influence on the flow at the joint to the power module. The coolant does not have to overcome any bottlenecks. As a result, more pressure loss is available, which occurs on the cooling structures of the power module and improves thermal cooling.

character list

• 1 bis 3 zeigen schematische Darstellungen einer unteren Halbschale eines Kühlkanals,
• 4 bis 6 zeigen eine obere Halbschale,
• 7 zeigt einen Schnitt durch den Kühlkanal,
• 8 und 9 zeigen den Kühlkanal mit montierten Leistungsmodulen,
• 10 zeigt einen Schnitt durch die Baueinheit für Leistungsmodule,
• 11 zeigt eine erfindungsgemäße Lösung in einer Schnittdarstellung,
• 12 bis 16 zeigen eine weitere Ausführungsform.

The invention is described below by way of example with reference to the accompanying drawings.

• 1 until 3 show schematic representations of a lower half-shell of a cooling channel,
• 4 until 6 show an upper half shell,
• 7 shows a section through the cooling channel,
• 8th and 9 show the cooling channel with mounted power modules,
• 10 shows a section through the assembly for power modules,
• 11 shows a solution according to the invention in a sectional view,
• 12 until 16 show another embodiment.

The invention is a structure of a unit for power modules 1 consisting essentially of two main components, a lower half-shell 4 and an upper half-shell 5. Both half-shells are metal sheets that can be deep-drawn to represent the final shape.

In 2 In a top view of the lower half-shell, you can see an almost rectangular surface 3a, which runs on its long sides to openings 6a for an inlet or outlet 6, following a contour of the outer edge 10. There is a peripheral edge 3b that defines the rectangular Area 3a and the openings 6a surrounds. The edge 3b has a height H. A flange 3c is formed on the edge 3b, which is also circumferential. Cylindrical collars 6b, which are connected to the inlets and outlets 6, are formed on the lower half-shell 4 at the openings 6a.

5 shows the top view of the upper half-shell 5, whose outer dimensions and the outer edge 10 corresponds to those of the lower half-shell 4. The sheet metal surface of the upper half-shell 5 thus rests on the flange 3b of the lower half-shell 4 during assembly. The upper half-shell 5 is flat as seen on its surface, but has three cutouts 5a. The cutouts 5a are each surrounded by a raised frame 5b protruding from the surface of the upper half-shell.

Both half-shells 4, 5 are connected to one another by a suitable method such as brazing, laser welding, flanging, etc. and form, as in 7 shown, a closed body having three cutouts 5a and inlets and outlets 6. The two half-shells are closed without the use of seals.

In the upper half-shell 5, the components of the power module 2 are inserted into the cutouts 5a. The cooling structure in the form of the cooling ribs 7 of the power module 2 protrudes into the cooling duct 3. The cooling ribs 7 extend to the lower half-shell 4 along the height H of the cooling duct 3.

In the next step, the power module 2 must be tightly connected to the upper half-shell 5 in order to close the cooling channel 3.

An essential aspect of the invention is the connection between the power module 2 and the upper half-shell 5 of the cooling channel 3.

The connection is made by a soldered connection, e.g. B. made by soldering. The solder joint 8 extends along the frame 5b of the upper half shell 5 and along the substrate 2c of the power module 2 around the heat sink of the power module 2 on the surface of the substrate 2c. The power module 2 has a circuit board 2a on which the actual semiconductor components are installed. The printed circuit board 2a is thermally connected to the connection 2b of the cooling fins. The substrate 2c covers the components.

In 11 the design of the soldering point 8 between the power module 2 and the upper half-shell 5 is shown. In the upper half-shell 5 of the cooling channel, the elevation is provided by the frame 5b, which ensures that a gap 9 is formed between the substrate 2a and the upper half-shell 5. The contact between the two components is therefore limited to the contact between the substrate and the half-shell. It can thus be avoided that the plastic components of the power module 2 are damaged, especially in the case of a soldered connection.

The transition area is formed with a recess in the upper half-shell 5 as a groove 5c around the cutouts 5a. The raised frame 5b can be retained.

Alternatively, instead of soldering, an adhesive connection 8 can also be used. A frame-like indentation around the cutouts 5 is then suitable for producing a defined adhesive layer thickness.

The cooling channel 3 is thus closed in a materially bonded manner, without a seal being used. Inlet and outlet 6 are also integrally connected to the lower half-shell. If necessary, this connection can also be carried out together with the connection of the lower and upper half-shells.

• Herstellung einer unteren Halbschale des Kühlkanals,
• Herstellung einer oberen Halbschale des Kühlkanals,
• Dichtendes Verbinden der oberen und unteren Halbschalen entlang ihrer Außenrands,
• Einsetzen der von Leistungsmodulen mit bereits an ihnen angebrachten Kühlrippen in Ausschnitte der oberen Halbschale des Kühlkanals.

The assembly process for the assembly for power modules is therefore carried out in the following steps:

• Production of a lower half-shell of the cooling channel,
• Production of an upper half-shell of the cooling channel,
• Sealing connection of the upper and lower half-shells along their outer edges,
• Insertion of the power modules with cooling fins already attached to them in cutouts of the upper half-shell of the cooling channel.

The 12 until 16 show a further embodiment or a further assembly method. In the 12 the lower half-shell 4 is shown, which is designed in exactly the same way as in the first exemplary embodiment. The upper half-shell 5 also shows the same structure as in the first exemplary embodiment. Both half shells are placed on top of each other. In the cutouts 5 it can be seen that cooling fins 7 are used. As individual cooling modules, the cooling fins are adapted in size to the cutouts 5 . In 12 you can see that all 3 of the cutouts are already filled with cooling fins. This cooling fins 7 are on the lower half-shell of the cooling channel 3 and protrude to the Surface of the upper half-shell 5 on. In 13 shows how the power modules 2 are placed on the upper half-shell and on the cooling fins 7 . In 14 all 3 power modules have been placed on the respective cooling fins 7.

In order to connect the cooling ribs to the power modules, a soldered connection between the power modules 2 and the cooling ribs 7 is necessary. For this purpose, a prefabricated soldering pad 11 is used, which is placed on the cooling ribs 7 . The flat power module 2 is placed on this soldering pad 11 .

Then, in a common soldering process, the heating is carried out along the frame 5b of the power modules 2 and the upper half-shell 5 and in the soldering pad 11 . This prevents one soldering from negatively affecting the other. In a further step or even before the soldering process described, the outer seam 10 is closed between the lower half-shell 4 and the upper half-shell 5 .

• Herstellung einer unteren Halbschale 4 des Kühlkanals 3,
• Herstellung einer oberen Halbschale 5 des Kühlkanals 3,
• Einsetzen von Kühlrippen 7 in Ausschnitte der oberen Halbschale 5 des Kühlkanals,
• Auflegen von Lötpads 11 auf die Kühlrippen 7,
• Dichtendes Verbinden der oberen Halbschale 5 mit den Leitungsmodulen 2 entlang des Rahmens 5b der Ausschnitte 5a und zeitgleich Verbinden der Kühlrippen 7 mit den Leistungsmodulen 2,
• Dichtendes Verbinden der oberen und unteren Halbschalen 4,5 entlang ihres Außenrands 10 vor oder nach dem letzten Schritt.

The alternative assembly method according to the invention for the assembly for power modules 1 thus takes place in the following steps:

• production of a lower half-shell 4 of the cooling channel 3,
• production of an upper half-shell 5 of the cooling channel 3,
• Insertion of cooling fins 7 in cutouts of the upper half-shell 5 of the cooling channel,
• placing soldering pads 11 on the cooling fins 7,
• Sealing connection of the upper half-shell 5 to the line modules 2 along the frame 5b of the cutouts 5a and at the same time connecting the cooling fins 7 to the power modules 2,
• Sealing connection of the upper and lower half-shells 4.5 along their outer edge 10 before or after the last step.

Reference List

1

Unit for power module

2

power module

2a

circuit board

2 B

Connection cooling fins

2c

substrate

3

cooling channel

3a

rectangular area

3b

edge

4

lower half-shell cooling channel

4a

flange

5

upper half-shell cooling channel

5a

excerpts

5b

Frame

5c

gutter

6

Inlet and outlet nozzles

6a

Opening to the inlet and outlet connection

6b

cylindrical collar

7

cooling fin

8th

Adhesive/soldered seam/weld

9

gap

10

outer edge

11

solder pad

Claims (9)

Assembly for power modules (1) with at least one power module (2) with a cooling channel (3) with an inlet and outlet (6), the cooling channel (3) being formed by a lower half-shell (4) and an upper half-shell (5). , and wherein the line electronics (2) have cooling ribs (7) which protrude through a respective cutout (5a) into the cooling channel (3), the cooling channel (3) between the power module (2) and the upper half-shell (5) being closed with a material bond , characterized in that the upper half-shell (5) has at least one cut-out (5a) surrounding a frame (5b) raised to the surface of the upper half-shell and/or a channel (5c). Unit for power modules (1) according to claim 1 , characterized in that the upper half-shell (5) and the lower half-shell (4) are connected to one another with a positive or material connection along the outer edge (10) of the two half-shells (4, 5). Unit for power modules (1) according to claim 2 , characterized in that the lower half-shell (4) has a peripheral flange (4a) on the outer edge (10) for connection to the upper half-shell (5). Assembly for power modules (1) according to one of the preceding claims, characterized in that the integral connection is soldering, welding or gluing. Assembly for power modules (1) according to any one of the preceding claims, characterized in that the material connection Connection between the power module (2) and the upper half-shell (5) via a peripheral contact point between the substrate (2c) of the power module (2). Assembly for power modules (1) according to one of the preceding claims, characterized in that the cooling channel (3) is a continuous space into which only the cooling fins (7) project. Assembly for power modules (1) according to one of the preceding claims, characterized in that the two half-shells (4, 5) consist of deep-drawn thin sheet metal. Assembly procedure for the assembly for power modules (1) according to claim 1 takes place in the following steps: - production of a lower half-shell (4) of the cooling channel (3), - production of an upper half-shell (5) of the cooling channel (3), - insertion of the power modules (2) with cooling fins (7) already attached to them in cutouts (5a) of the upper half-shell (4) of the cooling channel (3), - sealing connection of the upper and lower half-shells (4, 5) along their outer edge (10), - sealing connection of the upper half-shell (5) with the line modules ( 2) along the frame (5b) of the cutouts (5a). Assembly procedure for the assembly for power modules (1) takes place in the steps: - Production of a lower half-shell (4) of the cooling channel (3), - Production of an upper half-shell (5) of the cooling channel (3), - Insertion of cooling fins (7) in cutouts (5a) of the upper half-shell (5) of the cooling channel (3), - Place soldering pads (1) on the cooling fins (7), - Sealing connection of the upper half-shell (5) to the line modules (2) along the frame (5b) of the cutouts (5a) and at the same time connecting the cooling fins (7) to the power modules (2), - Joining the upper and lower half-shells (4, 5) along their outer edges (10) before or after the last step.

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