Electronic assembly

Abstract

The present invention relates to an electronic assembly comprising: an electronics module (2); a substrate (11) on which the electronics module (2) is arranged; a heat sink (3) which is composed of metal, in particular aluminium, and is designed to cool the electronics module (2), wherein the heat sink (3) is of two-part form with a cover (31) and a base part (32) which are interconnected at an edge of the heat sink (3) by means of a solder connection (33), the cover (31) is directed towards the electronics module (2), and the cover (31) has a first thickness (D1); a moulded body (5) which is composed of plastics material and at least partially surrounds the electronics module (2); and an exposed electrical contact region (7) for the electrical contacting of the electronics module (2), wherein a first spacing (a) in a horizontal direction (X) of the electronic assembly between an edge (11a) of the substrate (11) and the solder connection (33) amounts to at least half of the first thickness (D1) of the cover (31), which the cover (31) exhibits in the region (31a) between the substrate (11) and the solder connection (33).

Description

[0001] Description

[0002] title

[0003] Electronic assembly

[0004] State of the art

[0005] The present invention relates to an electronic assembly, particularly for use in vehicles, with a longer service life and improved heat dissipation.

[0006] Electronic assemblies are known in various configurations from the prior art. When using inverters, power modules are employed to drive the inverter. This can generate significant amounts of heat during operation, which must be dissipated by heat sinks through which a cooling medium can flow. The service life of such electronic assemblies is often compromised by the limited lifespan of the solder joints that secure the heat sink to the heat-generating electronic module.

[0007] Disclosure of the invention

[0008] The electronic assembly according to the invention, in particular an inverter of an electric vehicle controlled by means of power modules, with the features of claim 1, has the advantage that the service life of the electronic assembly can be significantly extended. In particular, with bonded connections of the electronic assembly, stresses during operation that can lead to cracks and / or delamination can be reduced. In particular, typically critical external contact areas can be kept free from stresses, thus significantly extending the service life of the electronic assembly. The external contact areas are particularly critical because they include areas, especially for electrical contact, that are not surrounded by a plastic mold body.This results in mechanical weaknesses in these external contact areas, which reduces their mechanical stiffness. Particularly after all components are assembled, these weakened areas can introduce curvature and high stresses into the assembly, which can lead to cracks and delamination, especially in the case of bonded connections between the assembly and the mold body. Since such cracks and delamination can be prevented, the cooling of electronic modules is also significantly improved.

[0009] According to the invention, this is achieved by the electronic assembly comprising at least one electronic module and a heat sink made of metal, in particular aluminum. The heat sink is designed to cool the electronic module. The heat sink is formed in two parts, consisting of a lid and a base, which are joined together at the edge by means of a solder joint. The lid of the heat sink faces the electronic module to be cooled and has a first thickness D1. The mold body is made of a plastic and surrounds the electronic module at least partially, preferably completely. Furthermore, the electronic assembly comprises at least one exposed electrical contact area, in particular an external contact area at the edge of the electronic assembly, which is designed to electrically contact the electronic module. The electrical contact area is not covered by the plastic mold body.Furthermore, a first distance a in a horizontal direction X of the electronic assembly between an edge of a substrate on which the electronic module is arranged and the solder joint between the cover and the base part is selected such that the first distance a is at least half the first thickness D1 of the cover, which the cover has in the area between the substrate and the solder joint of the cooler. This ensures that no stresses or curvatures are introduced into the assembly, particularly at the edge of the substrate, so that no cracks or delaminations are present that could negatively affect the functionality of the electronic assembly. This also ensures sufficient cooling performance over the lifetime of the electronic assembly. The dependent claims describe preferred embodiments of the invention.

[0010] Preferably, the cover of the cooler is a continuous base plate, in particular made of aluminium, which in particular has a constant thickness D1.

[0011] The electronic assembly preferably further comprises at least one stiffening plate, which is arranged on the cooler on a side of the cooler facing away from the electronic module. The stiffening plate can be designed as a continuous flat plate or as a plate with cutouts. The stiffening plate is preferably made of the same material as the cooler, in particular aluminum.

[0012] The cooler is preferably made entirely of aluminum, i.e., the lid and the base are made of aluminum, the base preferably being a deep-drawn component to provide a cooling channel between the lid and the base. The lid and the base are preferably joined to each other by means of a brazed connection at the circumferential edge of the two components.

[0013] The cooler preferably includes a turbulator arranged in the cooling channel between the base and the lid. The turbulator can also be connected to the lid and / or the base by means of a soldered connection. Alternatively, the turbulator can simply be inserted into the cooling channel.

[0014] The electronic assembly preferably has a second horizontal distance b between the turbulator and the edge of the substrate, wherein the second distance b is at most half the thickness of the sum of a second thickness D2 of the base part and a third thickness D3 of the stiffening plate. Dh b < x (D2 + D3).

[0015] A third distance c in the horizontal direction X between the stiffening plate and the edge of the substrate is further preferred. This distance c must be at most equal to the sum of the second thickness D2 of the base part and the third thickness D3 of the stiffening plate. Therefore, c < D2 + D3. The first distance a is preferably at least 0.5 mm, preferably at least 1 mm. The second distance b is preferably at most 2 mm, preferably 1 mm. The third distance c is at most 4 mm, preferably 2 mm.

[0016] Preferably, the turbulator and / or the stiffening plate is arranged in the horizontal direction X such that the turbulator and / or the stiffening plate project beyond the mold body. This ensures that the edge of the substrate is somewhat spaced from the edge of the electronic assembly and is thus protected from large bending or other adverse influences.

[0017] Preferably, the first distance a is greater than the second distance b. Preferably, the first distance a is also greater than the third distance c. Preferably, the second distance b is greater than the third distance c.

[0018] The substrate preferably does not cover the solder joint between the lid and the base of the cooler in the vertical direction Y of the electronic assembly. That is, the solder joint of the cooler protrudes beyond the edge of the substrate and preferably has a distance from the edge of the substrate.

[0019] Alternatively, the substrate at least partially, and preferably completely, covers the solder joint in the horizontal direction X of the electronic assembly. Preferably, the coverage corresponds to the first distance a in the horizontal direction X.

[0020] Preferably, the electrical contact area for electrically connecting the electronic module is arranged above the edge of the substrate. Preferably, an edge of the electrical contact area and the edge of the substrate lie in a common plane, which is oriented perpendicular to the horizontal direction X.

[0021] The electronic assembly is preferably an inverter with a heat sink, controllable by means of a power module. Preferably, the assembly comprises several power modules. More preferably, the mold body has a plurality of recesses, which are arranged, in particular, along an edge of the electronic assembly. The recesses are specifically designed to enable electrical contact with the electronic assembly.

[0022] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. The drawing shows:

[0023] Figure 1 shows a schematic, perspective sectional view of an electronic assembly according to a first embodiment of the invention.

[0024] Figure 2 is a schematic sectional view of the assembly of Figure 1.

[0025] Figure 3 shows an enlarged partial sectional view of the assembly from Figure 2.

[0026] Figure 4 shows a partial sectional view of an electronic assembly according to a second embodiment of the invention and

[0027] Figure 5 shows a partial sectional view of an electronic assembly according to a third embodiment of the invention.

[0028] An electronic assembly 1 according to a first preferred embodiment of the invention is described in detail below with reference to Figures 1 to 3.

[0029] The electronic assembly 1 comprises two electronic modules 2, which are designed as power modules for controlling an inverter. The electronic assembly 1 essentially has a rectangular, box-like external shape.

[0030] The electronic assembly 1 comprises, in addition to the electronic modules 2, a cooler 3 and a mold body 5. The mold body 5 is shown schematically in Figure 1 and encloses parts of the electronic assembly 1. The mold body 5 has recesses 50 which are designed for contact areas 7 for electrical contact. The recesses 50 are arranged, in particular, along the edges on two parallel sides of the electronic assembly.

[0031] The cooler 3 is arranged on the underside of the electronic assembly and serves to cool the electronic modules 2. The cooler 3 is a fluid-cooled cooler and can be seen in detail in Figures 2 and 3.

[0032] As can be seen from Figures 2 and 3, a metallurgical connection 6 is provided between the electronic modules 2 and the cooler 3. The metallurgical connection 6 comprises a copper layer 61, which is arranged on the cooler 3, and a solder layer 62 on the copper layer 61.

[0033] The cooler 3 is made entirely of aluminum and comprises a turbulator 30, a cover 31, and a base 32. The base 32 is a deep-drawn component that forms a cooling channel 34. The turbulator 30 is inserted into the base 32. The cover 31 serves as a base plate on which the metallurgical connection 6 to the electronic modules 2 is made. The cover 31 and the base 32 are fixed along an outer circumference of the electronic assembly by means of a solder joint 33, which is preferably a hard solder joint. It should be noted that the turbulator 30 can also be connected to the base 32 and / or the cover 31 by means of a solder joint. All components of the cooler 3 are made of aluminum.

[0034] A stiffening plate 4 is also arranged on the side of the cooler 3 facing away from the electronic module 2. In this embodiment, the stiffening plate 4 covers the outwardly facing base surface 32a of the base part 32. The stiffening plate has four recesses. It should be noted that instead of a single stiffening plate 4, several stiffening elements can also be arranged on the cooler 3.

[0035] The electronic assembly 1 further comprises a substrate 11 on which the electronic modules 2 are fixed. The substrate 11 is arranged on the lid-side of the cooler 3. The substrate 11 can be positioned before the electronic modules 2 are attached to the electronic modules 2 and / or on the solder layer 62. It should be noted that the substrate 11 can also consist of several layers.

[0036] As can be seen further in Figure 3, a top plate 8 is arranged on the outside of the cover above the solder joint 3. The top plate 8 can be made of aluminum or another material and is preferably arranged only on two parallel sides of the electronic assembly 1, on which the recesses 50 are arranged.

[0037] As can be seen in Figure 1, the necessary provision of the recesses 50, particularly at the two edge regions of the electronic assembly 1 where the top plate 8 is arranged, results in a tendency towards a weakening of the electrical contact areas 7. The necessary contact areas 7 for external contacting reduce the mechanical stiffness of the electronic assembly 1 in these regions. In particular, during the fixing of the cooler 3, bending and high stresses can be introduced into the electronic assembly 1. To prevent this, a first gap a is provided in a horizontal direction X of the electronic assembly between an edge 11a of the substrate 11 and the solder joint 3.

[0038] The lid 31 of the cooler 3 has a first thickness D1, wherein the first distance a has a length equal to or greater than half the first thickness D1 of the lid 31. The first thickness D1 of the lid 31 is determined in the region 31a between the substrate 11 and the solder joint 3 (see Figure 3).

[0039] This ensures that the solder joint 33 of the cooler 3, which connects the cover 31 to the base part 32 and is provided along the entire edge of the electronic assembly, has a first gap a, which depends on the thickness of the cover 31. This increases the stiffness of the electronic assembly 1 and, in particular, prevents warping and / or cracking in the substrate and / or the bonded connection between the cooler 3 and the electronic modules 2. As can also be seen in Figure 3, a second gap b in the horizontal direction X of the electronic assembly 1 is provided, which is located between the turbulator 30 and the edge 11a of the substrate 1 in the horizontal direction. The second gap b is at most half the sum of the second thickness D2 of the base part 32 and the third thickness D3 of the stiffening plate 4. Therefore, b < x (D2 + D3). A value for the second gap b is preferably a maximum of 2 mm.

[0040] The second distance b ensures that the metallurgical bond 6 and the substrate 11 are supported as completely as possible by the turbulator 30. In other words, the substrate 11 and the metallurgical bond 6 protrude only minimally, by the second distance b, beyond the end of the turbulator 30 closest to the edge (see Figure 3).

[0041] Furthermore, a third distance c in the horizontal direction X of the electronic assembly 1 between the stiffening plate 4 and the edge 11 a of the substrate 11 is at most equal to the sum of the second thickness D2 of the base part 32 and the third thickness D3 of the stiffening plate 4. That is, c < D2 + D3. The third distance c is preferably at most 4 mm.

[0042] The third distance c ensures that the stiffening plate 4 is located as completely as possible below the substrate 11 and the bonded connection 6. Any overhang of the substrate 11 and the bonded connection 6 in the horizontal direction X is thus limited by the requirement for the third distance c (see Figure 3).

[0043] Preferably, the first distance a is greater than the second distance b and the second distance b is greater than or equal to the third distance c.

[0044] As can be seen from Figures 1 and 2, the mold body 5 also has a circumferential rim 51, which surrounds the necessary recesses 50 for electrical contact. The rim 51 runs parallel to the solder joint 33 between the cover 31 and the base part 32 of the cooler 3. This provides additional reinforcement to these areas through the mold material. The rim 11a of the substrate 11 lies in a plane 10 that is perpendicular to the horizontal direction X. This is shown schematically in Figures 2 and 3. In particular, by adhering to the specifications for the three distances a, b, c, even severe bending and stresses in the mold body 5 can be prevented. Specifically, the arrangement of the solder joint 33 between the cover 31 and the base part 32 and the minimum distance defined by the first distance a prevent local bending of the cooler 3 in the area of ​​the mold body 5 and the substrate 11.This can in particular increase the service life of the solder layer 62 and thus ensure safer heat dissipation from the electronic modules 2 to the cooler 3 in all operating conditions.

[0045] The first gap a is preferably at least 0.5 mm. Preferably, the first gap a is equal to the first thickness D1 of the cover 31. The cover 31 and the base part 32 preferably have a constant material thickness.

[0046] Preferably the first distance a is greater than 0.5 mm and the second distance b and the third distance c are preferably 0 mm, i.e. the end regions of the turbulator 30 and the stiffening plate 4 lie in the plane 10 in which the edge 11a of the substrate 11 also lies.

[0047] Figure 4 shows an electronic assembly 1 according to a second embodiment of the invention, in which identical or functionally identical parts are designated with the same reference numerals as in the first embodiment.

[0048] In contrast to the first embodiment, the second embodiment features an intermediate plate 9 arranged at the solder joint 3 between the cover 31 and the base part 32 (see Figure 4). The intermediate plate 9 projects slightly in the horizontal direction X beyond the solder joint 33 towards the turbulator 30. The intermediate plate 9 thus replaces the top plate 8 in the first embodiment. The inclusion of the intermediate plate 9 necessitates two solder joints 33a, 33b, one to the base part 32 and one to the cover 31. The material of the intermediate plate 9 is preferably stiffer than the material of the cover 31 and the base part 32. The thickness of the intermediate plate 9 is preferably equal to the thickness of the cover 31.

[0049] Figure 5 shows a third embodiment of the invention, in which identical or functionally equivalent parts are again designated with the same reference numeral.

[0050] In the third embodiment, unlike the two preceding embodiments, the substrate 11 is configured such that the edge 11a of the substrate lies partially over the plumb line 33 in a direction perpendicular to the horizontal direction X. This overlap is limited by the first distance a. The second distance b and the third distance c are determined as in the preceding embodiments. In the third embodiment, the first distance a is determined between the edge 11a of the substrate 11 and the beginning of a bend 32a of the base part 32. The first distance a is at least half the first thickness D1 of the cover 31 and is smaller than the second distance b and smaller than the third distance c.

Claims

Claims 1. Electronic assembly comprising: an electronic module (2), a substrate (11) on which the electronic module (2) is arranged, a metal cooler (3), in particular aluminum, which is configured for cooling the electronic module (2), wherein the cooler (3) is formed in two parts with a cover (31) and a base part (32), which are connected to each other at an edge of the cooler (3) by means of a solder joint (33), wherein the cover (31) is directed towards the electronic module (2) and the cover (31) has a first thickness (D1), a plastic mold body (5) which at least partially surrounds the electronic module (2), and an exposed electrical contact area (7) for electrically contacting the electronic module (2), wherein a first distance (a) in a horizontal direction (X) of the electronic assembly between an edge (11a) of the substrate (11) and the solder joint (33) has at least half the first thickness (D1) of the cover (31).which the lid (31) has in the area (31a) between the substrate (11) and the solder joint (33), 2. Electronic assembly according to claim 1, wherein the cover (31) is a continuous base plate with in particular a constant first thickness (D1).

3. Electronic assembly according to one of the preceding claims, further comprising a stiffening plate (4) which is arranged on the cooler (3) on a side of the cooler facing away from the electronic module (2) on the base part (32).

4. Electronic assembly according to claim 3, wherein the cooler (3) has a turbulator (30) which is located between the cover (31) and the base part (32) is arranged, wherein a second distance (b) in the horizontal direction (X) of the electronic assembly between the turbulator (30) and the edge (11 a) of the substrate (11) in the horizontal direction (X) is at most half of a sum of a second thickness (D2) of the base part (32) and a third thickness (D3) of the stiffening plate (4).

5. Electronic assembly according to claim 4, wherein a third distance (c) in the horizontal direction (X) of the electronic assembly between the stiffening plate (4) and the edge (11 a) of the substrate (11) is at most equal to the sum of the second thickness (D2) of the base part (32) and the third thickness (D3) of the stiffening plate (4).

6. Electronic assembly according to one of the preceding claims, wherein the turbulator (30) and / or the stiffening plate (4) at least partially cover the electrical contact area (7) in the horizontal direction (X).

7. Electronic assembly according to one of the preceding claims, wherein the first distance (a) is larger than the second distance (b) and / or wherein the first distance (a) is larger than the third distance (c) and / or wherein the second distance (b) is larger than the third distance (c).

8. Electronic assembly according to one of the preceding claims, wherein there is no overlap between the substrate (11) and the solder joint (33) in the horizontal direction (X) of the electronic assembly.

9. Electronic assembly according to one of claims 1 to 7, wherein the substrate (11) at least partially covers the solder joint (33) in the horizontal direction (X) of the electrical assembly.

10. Electronic assembly according to one of the preceding claims, wherein the electrical contact area (7) covers the edge (11 a) of the substrate (11) in the horizontal direction (X).

11. Electronic assembly according to one of claims 1 to 9, wherein the electrical contact area (7) has a rim (7a) and the rim (7a) lies in a plane perpendicular to the horizontal direction (X) with the rim (11a) of the substrate (11).

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