DE102022101511A1 - Performance switching device with optimized pressure plate - Google Patents

Abstract

A switching device has a substrate (1) with an upper side (2) and an underside (3). Electronic power components (5) are arranged on the upper side (2) of the substrate (1), and a heat sink (8) rests directly on the underside (3) of the substrate (1) or via an intermediate body (9). The switching device has a pressing device (11) which is pressed against the power components (5) by means of at least one pressing element (16). The pressing device (11) has a plate-shaped pressure body (12) with an underside (13) facing the substrate (1) and an upper side (14) facing away from the substrate (1). Deformable pressure elements (15) are arranged on the underside (13) of the pressure body (12) in the area of the electronic power components (5). Indentations (17, 19) are made in the pressure body (12) from the upper side (14) and/or the underside (13) of the pressure body (12), so that the pressure body (12) at the corresponding points on its opposite side (13, 14) has corresponding curvatures (18, 20). The indentations (17, 19) are made in areas of the pressure body (12) on which pressure elements (15) are located.

Description

• - wobei die Schalteinrichtung ein Substrat mit einer Oberseite und einer Unterseite aufweist,
• - wobei auf der Oberseite des Substrats elektronische Leistungsbauelemente angeordnet sind,
• - wobei ein Kühlkörper direkt oder über einen zwischen dem Substrat und dem Kühlkörper angeordneten Zwischenkörper an der Unterseite des Substrats anliegt,
• - wobei die Schalteinrichtung eine Andrückeinrichtung aufweist, die mittels mindestens eines Andrückelements an die Leistungsbauelemente angedrückt wird,
• - wobei die Andrückeinrichtung einen plattenförmigen Druckkörper mit einer dem Substrat zugewandten Unterseite und einer von dem Substrat abgewandten Oberseite aufweist,
• - wobei an der Unterseite des Druckkörpers im Bereich der elektronischen Leistungsbauelemente verformbare Druckelemente angeordnet sind.

The present invention is based on a switching device

• - wherein the switching device has a substrate with a top and a bottom,
• - wherein electronic power components are arranged on the upper side of the substrate,
• - wherein a heat sink rests directly on the underside of the substrate or via an intermediate body arranged between the substrate and the heat sink,
• - wherein the switching device has a pressing device which is pressed against the power components by means of at least one pressing element,
• - wherein the pressing device has a plate-shaped pressure body with an underside facing the substrate and an upper side facing away from the substrate,
• - Deformable pressure elements being arranged on the underside of the pressure body in the area of the electronic power components.

Such switching devices are well known. Purely exemplary can on the DE 10 2013 104 949 B3 or on the DE 10 2014 106 570 A1 to get expelled. Furthermore, the DE 10 2016 123 697 A1 and the DE 10 2017 126 716 A1 to be named.

Such switching devices are often used in converters. The voltages switched by means of the switching devices can amount to several 100 V, sometimes even a little over 1 kV. The switched currents can be several 100 A. Accordingly, high power losses occur in the electronic power components (often 100 W and more), which have to be dissipated quickly from the power components to the heat sink. Good thermal coupling of the power components and the substrate to the heat sink is therefore required.

The thermal coupling is supported in particular by the fact that the substrate is pressed against the heat sink via the power components. This is done by means of the pressing device. However, despite all the efforts made in the prior art, it has not yet been possible to press the power components onto the substrate with an essentially uniform pressure. In particular, the plate-shaped pressure body is generally pressed against the power components either by means of a centrally arranged screw or with clamps arranged on the outside. In one case, the pressure hull is deflected due to the central effect of the force, so that the pressure force is greatest in the central region of the pressure hull and decreases towards the edges of the pressure hull. In another case, the pressure body also bends, but in this case the pressure force is greatest in the area of the clamps and decreases as the distance from the clamps increases, particularly towards the central area of the pressure body. This results in a location-dependent thermal coupling of the power components to the substrate and of the substrate to the heat sink.

The object of the present invention is to create possibilities by means of which the compressive forces acting on the individual power components can be standardized as far as possible.

The object is achieved by a switching device with the features of claim 1. Advantageous configurations of the switching device according to the invention are the subject matter of dependent claims 2 to 10.

• - dass von der Oberseite und/oder der Unterseite des Druckkörpers aus Vertiefungen in den Druckkörper eingebracht sind, so dass der Druckkörper an den korrespondierenden Stellen seiner jeweils gegenüberliegenden Seite korrespondierende Wölbungen aufweist, und
• - dass die Vertiefungen in Bereiche des Druckkörpers eingebracht sind, an denen sich Druckelemente befinden.

According to the invention, a switching device of the type mentioned at the outset is designed in that

• that depressions are made in the pressure body from the top and/or the bottom of the pressure body, so that the pressure body has corresponding bulges at the corresponding points on its opposite side, and
• - That the indentations are made in areas of the pressure hull where there are pressure elements.

As a result, the compressive forces acting on the individual power components can be adjusted as required. An additional positive side effect is a stiffening of the pressure hull.

Preferably, the indentations are conical or part-spherical. This configuration is simple and reliable.

It is possible for the indentations made in the pressure body to have a uniform depth and/or for the corresponding bulges to have a uniform height. In this case, too, there is still a relatively large degree of flexibility in the setting of the pressure forces, provided some of the depressions enter the pressure body from the top side of the pressure body and some of the depressions from the underside of the pressure body is introduced. However, even better results are obtained if the indentations made in the pressure body have different depths and/or the corresponding bulges have different heights. As a result, the compressive forces acting on the individual power components can be adjusted almost individually. Often the depths of indentations and/or the heights of bulges will be greater at a greater distance from the pressing element than at a smaller distance from the pressing element. However, this is not absolutely necessary.

In many cases, the pressing element is designed as a threaded screw. In this case, the pressing element can alternatively be screwed into the heat sink or the intermediate body.

If the pressing element is designed as a threaded screw, the pressure body has a recess for the passage of the threaded screw through the pressure body. A depression is preferably also made in the pressure body in the area of the recess from the top or bottom of the pressure body, so that the pressure body has a corresponding curvature at the corresponding point on its opposite side. This configuration improves the rigidity of the pressure body.

It is possible that the printing elements are separated from each other. However, at least some of the pressure elements are preferably connected to one another via a connecting structure. This offers manufacturing advantages in particular. The connection structure can be net-like, lattice-like or flat, as required. It is usually made of the same material as the printing elements themselves.

In the case of the connection structure, the connection structure has a smaller thickness than the pressure elements in the areas between the pressure elements. As the name suggests, the connection structure is only used to connect the printing elements to one another. In contrast, no pressure is exerted on the substrate via the connecting structure. The pressure elements thus protrude from the connection structure. As a rule, the pressure elements will protrude out of the connection structure in the direction of the power components. In individual cases - especially when the connection structure is flexible enough - it can also be the other way round.

It is possible for the printing elements to have a uniform thickness. Alternatively, at least some of the pressure elements can have different thicknesses from one another. As a result, the locally applied pressure can be adjusted very flexibly, particularly in conjunction with individual depths of the depressions and/or individual heights of the bulges. The thicknesses of the pressure elements will often be greater at a greater distance from the pressing element than at a smaller distance from the pressing element. However, this is not absolutely necessary.

The pressure body preferably comprises a plate-shaped main part and a plate-shaped reinforcement part, the main part being made of plastic and the reinforcement part being made of metal, in particular steel. As a result, the pressure body can be produced inexpensively and still have a high level of rigidity. In this case, the reinforcement part is generally arranged on the main part on the side facing away from the power components.

As a rule, the indentations are arranged exactly or approximately in the center in relation to the respective printing element.

• 1 eine Schaltungsanordnung,
• 2 eine Draufsicht auf einen Druckkörper,
• 3 einen Schnitt durch den Druckkörper von 2 längs einer Linie III-III in 2,
• 4 eine perspektivische Darstellung eines Schnitts durch den Druckkörper von 2 und
• 5 ein Detail einer Druckplatte.

Further advantages and details result from the following description of exemplary embodiments in conjunction with the drawings. They show in a schematic principle representation:

• 1 a circuit arrangement,
• 2 a plan view of a pressure hull,
• 3 a section through the pressure hull of 2 along a line III-III in 2 ,
• 4 a perspective view of a section through the pressure hull of 2 and
• 5 a detail of a printing plate.

According to 1 a switching device has a substrate 1 with a top side 2 and a bottom side 3 . The substrate 1 consists of a ceramic. It is arranged in a housing 4 . Electronic power components 5 are arranged on the upper side 2 of the substrate 1 . The electronic power components 5 can in particular include switching elements (for example IGBTs or MOSFETs) and rectifying elements (in particular diodes). The power components 5 are electrically connected to one another and/or to external connections 6 at least partially via conductor tracks 7 which are arranged on the upper side 2 of the substrate 1 . The conductor tracks 7 can have been applied to the substrate 1 by means of DCB (direct copper bonding) or AMB (active metal brazing), for example.

A heat sink 8 rests on the underside 3 of the substrate 1 . In some configurations, the heat sink 8 can rest directly on the underside 3 of the substrate 1 . According to the design of 1 an intermediate body 9 is arranged between the substrate 1 and the heat sink 8 . The intermediate body 9 is mostly plate-shaped. To optimize the thermal connection of the heat sink 8 to the substrate 1, a thin layer (usually only about 10 µm thick) of a thermally conductive paste 10 can be arranged between the heat sink 8 and the intermediate body 9 and/or the intermediate body 9 and the substrate 1 or (in the case of direct connection of the heat sink 8 to the underside 3 of the substrate 1) between the heat sink 8 and the substrate 1.

A pressing device 11 is present to optimize the thermal connection of the power components 5 to the substrate 1 . The pressing device 11 has a plate-shaped pressure body 12 with an underside 13 facing the substrate 1 and an upper side 14 facing away from the substrate 1 . The pressure body 12 can consist, for example, of metal (particularly steel or aluminum) or of a sufficiently temperature-resistant plastic. An example of a suitable plastic is polyphenylene sulfide. It is also as shown in 1 It is possible for the pressure body 12 to comprise a main part 12'("the main plate") and a reinforcement part 12"("the additional plate"), the main part 12' being made of plastic and the reinforcement part 12" being made of metal (particularly steel).

On the underside 13 of the pressure body 12 5 deformable pressure elements 15 are arranged in the area of the electronic power components. The pressure elements 15 can consist, for example, of a silicone rubber, in particular of so-called liquid silicone. Alternatively, they may have a uniform thickness or different thicknesses from each other as required. Furthermore, they can be connected to each other via a connecting structure (no reference number) as required. If it is present, the connection structure has a smaller thickness in the areas between the pressure elements 15 than the pressure elements 15. The connection structure is therefore only used to connect the pressure elements 15 to one another, but not to exert pressure on the substrate 1.

The pressing device 11 is pressed against the power components 5 by means of (at least) one pressing element 16 . As a result, the corresponding points of the substrate 1 are pressed against the heat sink 8 via the power components 5 . The pressing element 16 can, as shown in FIG 1 be designed in particular as a threaded screw that is screwed into the heat sink 8 (alternatively, the intermediate body 9).

The core of the present invention is the design of the pressure hull 12. It is below in connection with the 2 until 4 explained in more detail.

According to the 2 until 4 are introduced from the top 14 of the pressure body 12 from depressions 17 in the pressure body 12. As a result, the pressure body 12 has corresponding bulges 18 at the corresponding points on its underside 13 . Alternatively or additionally, depressions 19 can be introduced into the pressure body 12 from the underside 13 of the pressure body 12 . In this case, the pressure body 12 has corresponding bulges 20 at the corresponding points on its upper side 14 . In both cases, the indentations 17, 19 are made in areas of the pressure body 12 where pressure elements 15 are located. The depressions 17, 19 are, based on the respective pressure element 15, usually arranged exactly or approximately in the middle. From the depressions 17, 19 and the bulges 18, 20 are in the 2 until 4 for the sake of clarity, only a few are provided with their reference numbers.

The wells 17, 19 can - see in particular 3 - be conical, for example. Alternatively, the indentations 17, 19 can be part-spherical. Furthermore, the depressions 17, 19 (in 3 recognizable only for the depressions 17 introduced from the top 14) preferably have different depths. Likewise, the corresponding bulges 18, 20 preferably have different heights.

The pressure hull 12 has according to the 2 and 4 a recess 21 for the passage of the pressing element 16 (the threaded screw) through the pressure body 12 . For additional stiffening of the pressure body 12 , the pressure body 12 can also have a further depression 22 in the area of the recess 21 . The further depression 22 can be introduced into the pressure body 12 from the upper side 14 or the underside 13 of the pressure body 12 as required. In both cases, however, the pressure body 12 has a corresponding curvature 23 at the corresponding point on its opposite side 13, 14. Here, too, the indentation 22 can in particular be conical or part-spherical.

The present invention has many advantages. In particular, the pressure that is exerted on the power components 5 by means of the pressing device 11 can be adjusted as required, for example equalized, in a simple manner. A deflection of the pressure body 12 can be reduced by the additionally effected stiffening of the pressure body, the remaining deflection can be compensated.

The above description is only intended to explain the present invention. The scope of the present invention, however, is to be determined solely by the appended claims.

Reference List

1

substrate

2, 14

tops

3, 13

subpages

4

Housing

5

power components

6

connections

7

traces

8th

heatsink

9

intermediate body

10

thermal paste

11

pressing device

12

pressure hull

15

printing elements

16

pressing element

17, 19, 22

indentations

18, 20, 23

bulges

21

recess

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102013104949 B3 [0002]
• DE 102014106570 A1 [0002]
• DE 102016123697 A1 [0002]
• DE 102017126716 A1 [0002]

Claims (10)

switching device, - wherein the switching device has a substrate (1) with a top (2) and a bottom (3), - electronic power components (5) being arranged on the upper side (2) of the substrate (1), - wherein a heat sink (8) bears against the underside (3) of the substrate (1) directly or via an intermediate body (9) arranged between the substrate (1) and the heat sink (8), - the switching device having a pressing device (11) which is pressed against the power components (5) by means of at least one pressing element (16), - wherein the pressing device (11) has a plate-shaped pressure body (12) with an underside (13) facing the substrate (1) and an upper side (14) facing away from the substrate (1), - deformable pressure elements (15) being arranged on the underside (13) of the pressure body (12) in the area of the electronic power components (5),characterized, - that depressions (17, 19) are introduced into the pressure body (12) from the top (14) and/or the underside (13) of the pressure body (12), so that the pressure body (12) has corresponding bulges (18, 20) at the corresponding points on its opposite side (13, 14), and - That the depressions (17, 19) are introduced into areas of the pressure body (12) on which pressure elements (15) are located. switching device claim 1 , characterized in that the depressions (17, 19) are conical or part-spherical. switching device claim 1 or 2 , characterized in that the depressions (17, 19) introduced into the pressure body (12) have different depths and/or the corresponding bulges (18, 20) have different heights. switching device claim 1 , 2 or 3 , characterized in that the pressing element (16) is designed as a threaded screw and that the pressing element (16) is screwed into the heat sink (8) or the intermediate body (9). switching device claim 4 , characterized in that the pressure body (12) has a recess (21) for the threaded screw to pass through the pressure body (12) and that a depression (22) is also made in the pressure body (12) in the region of the recess (21) from the upper side (14) or the underside (13) of the pressure body (12), so that the pressure body (12) has a corresponding curvature at the corresponding point on its opposite side (13, 14). (23). Switching device according to one of the above claims, characterized in that at least some of the pressure elements (15) are connected to one another via a net-like, grid-like or flat connection structure. Switching device according to one of the above claims, characterized in that at least some of the pressure elements (15) have different thicknesses from one another. Switching device according to one of the above claims, characterized in that the pressure body (12) comprises a plate-shaped main part (12') and a plate-shaped reinforcement part (12") and that the main part (12') consists of plastic and the reinforcement part (12'') consists of metal, in particular steel. switching device claim 8 , characterized in that the reinforcement part (12'') is arranged on the main part (12') on the side facing away from the power components (5) on the main part (12'). Switching device according to one of the above claims, characterized in that the indentations (17, 19) are arranged exactly or approximately centrally in relation to the respective pressure element (15).

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