Switchgear assembly with improved electrical contact

Description

State of the art

[0001] The present invention relates to a circuit carrier arrangement with significantly improved electrical contacting.

[0002] Circuit carrier arrangements are known in various configurations from the prior art. For example, so-called IMS (isolated metal substrates) are known in the form of single-layer or multi-layer printed circuit boards laminated onto a metal substrate, in particular containing copper or aluminum. This metal substrate enables better thermal dissipation of power losses. However, copper-based IMS are significantly more expensive than aluminum-based IMS, assuming otherwise identical construction. In addition to the base layer, the IMS also comprises a copper-based circuit layer and a dielectric intermediate layer between the base layer and the circuit layer. If the base layer is aluminum-based, however, electrical contact problems arise between the base layer (aluminum), which is based on different metal substrates, and the circuit layer (copper).

[0003] A connecting element in the form of a rivet, known from JPS5843595A, establishes an electrical connection between the conductor track and the metal core via a completely filled opening. A rivet is known from JPH0221776U, which is pressed into the metallic carrier layer and soldered to the conductor track layer. Disclosure of the invention

[0004] In contrast, the circuit carrier arrangement according to the invention with the features of claim 1 has the advantage that improved contact is possible with different metal substrates of the circuit carrier arrangement. Here, an aluminum base layer and a copper circuit layer can be used, which are separated from each other by a dielectric intermediate layer. The electrical contact can be implemented very simply and cost-effectively and enables particularly high robustness, which leads to significant advantages, especially when used in moving devices, such as vehicles.According to the invention, an electrical contact between the aluminum base layer and the copper circuit layer is provided by means of a rivet. A force-fit connection is formed between the rivet and the base layer, and a material-fit connection is formed between the rivet and the circuit layer. Thus, the rivet is connected to the two different metal layers by two different connections. The circuit carrier assembly has an opening in which the rivet is located. Therefore, the more cost-effective aluminum base layer can be used for the circuit carrier assembly without any problems, resulting in a wide range of applications, as the electrical contact between the different metal substrates can be significantly improved.

[0005] The dependent claims describe preferred embodiments of the invention.

[0006] The opening is preferably a through-hole. The opening is preferably created after the three layers of the circuit carrier assembly have been assembled. Alternatively, the opening is a blind hole.

[0007] It is particularly preferred that the rivet length be shorter than the opening length. This results in at least one area within the opening of the circuit carrier assembly that is not occupied by the rivet. This allows for various design options. For example, the rivet can be only partially located in the base layer and / or only partially located in the circuit layer. This creates free spaces at the first and second ends of the rivet, which can be used for different purposes.

[0008] The rivet particularly preferably comprises a head, especially a flat head. The head particularly preferably rests on the circuit layer. A metallurgical bond is preferably formed between the head and the circuit layer.

[0009] The material-bonded connection is preferably produced using a solder.

[0010] Alternatively, the rivet is in the form of a headless pin, allowing it to be fully inserted into the opening in the circuit carrier assembly. Preferably, a first end of the rivet is flush with a surface of the circuit layer, with the solder of the metallurgical bond then completely covering the first end of the rivet. Alternatively, the first end of the rivet is countersunk in the opening such that the rivet is only partially in contact with the wall of the opening in the circuit layer, resulting in a solder-filled region of the opening at the metallurgical bond between the rivet and the circuit layer. Preferably, the solder extends beyond a peripheral region of the opening at the circuit layer to ensure reliable electrical contact between the rivet and the circuit layer.

[0011] The circuit carrier arrangement according to the invention is particularly preferably used in a DC / DC converter, especially in conjunction with electrical machines. drawing

[0012] Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawing. The drawing shows: Figure 1 is a schematic, perspective view of a circuit carrier arrangement that is not part of the invention; Figure 2 is a schematic sectional view of the circuit carrier arrangement. Figure 1 Figure 3 is a schematic sectional view of a circuit carrier arrangement according to an embodiment of the invention, and Figure 4 is a schematic sectional view of a circuit carrier arrangement that is not part of the invention.

[0013] The following refers to the Figures 1 and 2A circuit carrier arrangement 1, which is not part of the invention, is described in detail. As shown in the following description: Figure 1 As can be seen, the circuit carrier arrangement 1 is a so-called IMS (insulated metal substrate) with an aluminium base layer 2, a dielectric layer 4 and a copper circuit layer 3.

[0014] The dielectric layer 4 is arranged as an intermediate layer between the base layer 2 and the circuit layer 3, electrically separating these two layers. Here, the dielectric layer 4 is applied directly to the base layer 2, and the circuit layer 3 is applied directly to the dielectric layer 4.

[0015] By using an aluminum-based base layer, a particularly cost-effective circuit carrier arrangement 1 can be provided compared to other base layer materials, with the aluminum base layer 2 enabling reliable dissipation of high heat output. This is especially advantageous in conjunction with high-performance electronic components, such as MOSFETs, IGBTs, transformers, and / or inductors. This prevents heat buildup at the high-performance electronic components.

[0016] For example, the use of the aluminum-based base layer 2 offers a significant price advantage compared to the use of copper-based base layers, while in practice achieving almost the same thermal conductivities of the base layers.

[0017] As detailed in Figure 2As shown, the circuit carrier arrangement 1 further comprises at least one, preferably several openings 5, which serve as

[0018] Through-openings are provided through the circuit carrier arrangement 1, wherein a central axis of the opening 5 is perpendicular to a surface of the circuit carrier arrangement 1.

[0019] To establish an electrical connection between the circuit layer 3 and the base layer 2, an electrical contact 6 is provided, which includes a rivet 7. The rivet 7 in this embodiment is a cylindrical rivet made of solid material, which has a head 70. As in Figure 2 As shown, the head 70 rests on a surface 30 of the circuit layer 3 in the assembled state.

[0020] The electrical contact 6 is now connected to the base layer 2 and the circuit layer 3 by two different connection types. A force-fit connection 8 is provided between the rivet 7 and the base layer 2, and a material-fit connection 9 is provided between the circuit layer 3 and the rivet 7. In this embodiment, the material-fit connection is formed at the head 70 of the rivet. The material-fit connection is created by means of a solder 10, which is arranged along the outer circumference of the head 70.

[0021] What's next? Figure 2 As can be seen, the rivet 7 has a first length L1 and the opening 5 in the circuit carrier arrangement 1 has a second length L2. The first length L1 is shorter than the second length L2. This results in an area 50 in the opening 5 at a first end 71 that is not filled by the rivet 7.

[0022] The electrical contact via the force-fit connection 8 between the base layer 2 and the rivet 7 enables very good electromagnetic compatibility with reduced interference potential.

[0023] The rivet 7 is preferably made of brass or copper and has a coated surface, preferably a gold or tin coating.

[0024] The material-bonded connection 9 by means of the solder 10 is particularly preferably carried out by means of a reflow soldering process.

[0025] Thus, in the circuit carrier arrangement 1, electrical contact is achieved via two different types of connection, namely a force-fit connection 8 for connection with the base layer 2 and a material-fit connection 9 for connection with the circuit layer 3, which achieves a particularly robust electrical contact between layers made of different materials, namely the base layer, which is essentially made of aluminum, and the circuit layer 3, which is essentially made of copper.

[0026] Figure 3 Figure 1 shows a circuit carrier arrangement 1 according to an embodiment of the invention, wherein identical or functionally identical parts are designated with the same reference numerals. As shown in Figure 1, the following applies: Figure 3As can be seen, the rivet 7 of the electrical contact 6 is exclusively a cylindrical rivet without a head. The rivet 7 is completely countersunk in the opening 5. The first area 50 at the first end 71 of the rivet 7 remains free in the opening, as does a second area 51 at the free or second end 72 of the rivet 7. In the final state, a solder area 10a of the solder 10 of the metallurgical bond 9 is present in area 51 and fills this area 51, as shown in Figure 3 shown schematically.

[0027] Figure 4Figure 1 shows a circuit carrier arrangement 1, which is not part of the invention but essentially corresponds to an exemplary embodiment. The rivet 7 is also headless and has a cylindrical geometric shape. However, in this case, the second end 72 of the rivet 7 is flush with a surface 30 of the circuit layer 3. The solder 10 of the metallurgical connection 9 covers the second end of the rivet 7 and establishes the electrical contact with the circuit layer 3.

[0028] Thus, according to the invention, as shown in the preferred embodiment, a very cost-effective printed circuit board with an aluminum-based base layer 2 and a copper-based circuit layer 3 can be manufactured. The electrical contact between the base layer 2 and the circuit layer 3 is made via a rivet 7, which is connected once by frictional bonding and once by material bonding.

Claims

1. Circuit carrier arrangement, comprising: - a base layer (2) which comprises aluminium, - a circuit layer (3) which comprises copper, - a dielectric layer (4) which is arranged between the base layer (2) and the circuit layer (3), - an opening (5) which runs through the base layer (2), the circuit layer (3) and the dielectric layer (4), and - an electrical contact (6) between the base layer (2) and the circuit layer (3), wherein the electrical contact (6) comprises a rivet (7), - wherein a force-fitting connection (8) is formed between the rivet (7) and the base layer (2), and - wherein a cohesive connection (9) is formed between the rivet (7) and the circuit layer (3), wherein the rivet (7) has a cylindrical shape without a head, characterized in that a free end (72) of the rivet (7) is arranged in the opening (5) of the circuit carrier arrangement in such a way that a region (51) which is filled with solder (10a) of the cohesive connection (9) is provided in the opening (5).

2. Circuit carrier arrangement according to Claim 1, wherein the opening (5) is a passage opening.

3. Circuit carrier arrangement according to either of the preceding claims, wherein a first length (L1) of the rivet (7) is smaller than a second length (L2) of the opening (5).

4. Circuit carrier arrangement according to one of the preceding claims, wherein the solder (10) of the cohesive connection (9) goes beyond the opening (5) and establishes an electrical contact-connection on the surface (30) of the circuit layer (3).