Electrical device, method for manufacturing electrical device

Abstract

The invention relates to an electrical device, comprising:-a component (LM), which is at least partially covered with a gel (VG); -a printed circuit board (LP) having an end face (SS), to which a metal layer is applied, which at least partially covers the end face (SS); -wherein the metal layer (MS) is at least partially covered by the gel (VG); -wherein the metal layer (MS) completely isolates the end face (SS) from the gel (VG) in a physical manner. The invention further relates to a method for producing the aforementioned device.

Description

Technical Field

[0001] The invention relates to an electrical (power) device, such as a (power) inverter, a (power) DC voltage converter, in particular for an electrically driven motor vehicle. The invention also relates to a method for producing such a device. Background Art

[0002] Prior art and invention tasks:

[0003] Electrical (power) devices, such as (power) inverters, (power) DC voltage converters are known and are used in particular in electric drives, in particular for electrically driven motor vehicles. Due to their field of use, such as in motor vehicles, such devices are subject to strong environmental influences, such as strong temperature fluctuations.

[0004] As is common in all technical devices, there is also a general requirement for a high degree of reliability for the devices mentioned above.

[0005] Therefore, the object of the present application is to improve the reliability of the above-mentioned device. Summary of the invention

[0006] This object is achieved by the subject matter of the independent claim. Advantageous embodiments are the subject matter of the dependent claims.

[0007] According to a first aspect of the invention, an electrical device, in particular an electrical power device, in particular for an electrically driven motor vehicle is provided.

[0008] The device has a component (or circuit component) that is at least partially, especially completely, covered with gel, especially sealed. Here, the gel protects the component from environmental influences and voltage breakdown.

[0009] The device further comprises a printed circuit board (or a plastic-based circuit carrier) having an (unequipped or non-equippable) end face. A metal layer is applied to the end face of the printed circuit board, the metal layer at least partially, in particular completely, covering the end face. The metal layer is at least partially, in particular completely, covered by the gel. In this case, the metal layer physically completely isolates or separates the end face from the gel, so that the end face is not in direct physical contact with the gel or is not (even not at least partially) in direct contact (i.e. without the metal layer located in between) with the gel.

[0010] The printed circuit board has an end face which faces the gel and is provided with a metal layer as edge metallization.The end face of the printed circuit board is one of the unequipped or non-equippable (cut) sides or side faces of the printed circuit board.

[0011] The gel which primarily covers the component of the device (which is not the previously mentioned printed circuit board) and thus in particular seals it, extends as far as the metal layer and at least partially covers it.

[0012] The metal layer isolates or separates the end face of the printed circuit board and therefore in particular also the printed circuit board from the gel and acts as a barrier between the gel on the one hand and the end face of the printed circuit board or the printed circuit board on the other hand and thus prevents physical contact between the gel on the one hand and the end face of the printed circuit board.

[0013] Arranging the metal layer on the end face of the printed circuit board and thereby physically isolating the end face of the printed circuit board from the gel effectively prevents outgassing of the printed circuit board, in particular at its end face, which could occur in direct physical contact with the gel and under the influence of temperature changes and could affect the required requirements with regard to high voltage strength and protection from other environmental influences. Due to the edge metallization of the metal layer facing the gel, the end face of the printed circuit board can no longer contribute to outgassing of the printed circuit board.

[0014] This provides a possibility of making the above-mentioned device more stable with respect to temperature fluctuations and thus increasing the reliability of the device overall.

[0015] The component can be an electronic module or power electronic module, in particular an apparatus that is to be protected from environmental influences, such as from moisture, in particular a switchable half-bridge or a part of this module or an electronic or power electronic device, in particular an unpackaged or housing-less and thus naked semiconductor switch or power semiconductor switch.

[0016] The printed circuit board can be a printed circuit board comprising fiber-reinforced plastic.

[0017] A driver / control circuit for operating and / or controlling a component can be formed on the printed circuit board, wherein the component can be formed as a (power) electronic module or as a (power) semiconductor switch.

[0018] For example, the printed circuit board has at least one electrical conductor track. In this case, the metal layer can be applied to the end face of the printed circuit board in the same metallization process as the conductor track, wherein the conductor track is applied to the printed circuit board. In this case, the same production process can be used for applying the metal layer to the end face during the metallization process of the conductor track.

[0019] The metal layer may be a metal layer electrodeposited on the end face or may be applied to the end face by electrodeposition of the metal.

[0020] Alternatively, the metal layer can be designed as a metal plate, such as a metal stamping, which is applied to the end face, for example by a material connection, such as being adhesively bonded, welded or sintered to the end face.

[0021] The gel may be a sealing gel or silicone gel for hermetically sealing the components.

[0022] In particular, the filling height of the gel does not exceed the structural height of the upper edge of the metal layer. That is, viewed from the plane of the bottom side of the device, the gel is filled up to a maximum filling height (from the plane of the bottom side), which does not exceed the structural height (from the plane of the bottom side) of the upper edge of the metal layer.

[0023] For example, the component and the printed circuit board are arranged offset from each other or in a row in the longitudinal direction of the device. Correspondingly, the printed circuit board is placed laterally offset relative to the component or the section thereof covered with gel. Thus, the printed circuit board and the gel (or at least a part thereof) are also arranged in a row in the longitudinal direction of the device.

[0024] Alternatively, the printed circuit board may be constructed in such a way that it at least partially surrounds the component.It is also possible to provide a plurality of printed circuit boards and / or a plurality of components which may be constructed or arranged in such a way that they surround one component or a plurality of components.

[0025] The device can be designed as a (power) inverter or a (power) DC voltage converter. In this case, the component can be designed as a power electronic module of the device or a part thereof. Accordingly, a drive / control circuit or a part thereof can be formed on a printed circuit board for operating and / or for controlling the power electronic module.

[0026] Due to the use of a metal layer as edge metallization, the printed circuit board or the driver / control circuit can be positioned close to the component or power electronic module. Parasitic inductances in the electrical connection between the printed circuit board or the driver / control circuit on the one hand and the component or power electronic module on the other hand can be kept low, which leads to an improvement in the controllability of the component or power electronic module and thus to an additional increase in the reliability of the device.

[0027] According to a second aspect of the present invention, a method for manufacturing the aforementioned device is provided, the device comprising a (circuit) component and a printed circuit board (or plastic-based circuit carrier).

[0028] According to the method, a metal layer is applied to an end face of a printed circuit board, wherein the metal layer at least partially, in particular completely, covers the end face.

[0029] The component is then at least partially, in particular completely, covered or sealed with the gel by applying the gel to the component. The gel is applied in such a way that it at least partially covers the metal layer and at the same time is physically completely isolated or separated from the end face of the printed circuit board by the metal layer, so that the end face is not (not even at least partially) directly covered by the gel without the metal layer located in between.

[0030] The advantageous embodiments of the device described above, insofar as they can also be transferred to the above-mentioned method, can also be regarded as advantageous embodiments of the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Referring to the attached drawings, Figure 1 Exemplary embodiments of the present invention are explained in more detail.

[0032] Figure 1 A section of a device V according to an exemplary embodiment of the present invention is shown in a first schematic cross-sectional illustration. DETAILED DESCRIPTION

[0033] In this embodiment, the device V is designed as a power inverter for an electric drive of a motor vehicle and has a housing GH, a group of a plurality of (eg three or six) power electronics modules LM and a printed circuit board LP.

[0034] The housing GH is composed of aluminum or an aluminum alloy, for example, and also serves as a cooler for cooling the device V. The power electronic module LM and the printed circuit board LP are arranged in the housing GH, wherein the printed circuit board LP is arranged on a protrusion VS formed at the housing bottom GB so as to be higher than the power electronic module LM. Here, the power electronic module LM is arranged in a row in a transverse direction QR of the device V or the housing GH (the transverse direction is transverse to the longitudinal direction LR of the device V). The power electronic module group LM and the printed circuit board LP are arranged in a row in the longitudinal direction LR. Alternatively, the printed circuit board LP can be configured in a manner that at least partially surrounds the power electronic module group LM, wherein in this case, the power electronic module LM is arranged in a cavity that is at least partially surrounded by the printed circuit board LP. Alternatively, a plurality of printed circuit boards can also be provided, which are arranged in a manner that surrounds the power electronic module group LM.

[0035] The printed circuit board LP is formed, for example, with fiber-reinforced plastic as insulating material and is placed on the projection VS via its underside and is physically and thermally connected to the housing GH. On the upper side facing away from the underside, the printed circuit board LP has a mounting surface BF, on which a drive / control circuit TS for operating or controlling the power electronics module LM or a part of such a circuit TS, such as one or more drive resistors (such as gate resistors) for operating the power electronics module LM, is formed or mounted. On the mounting surface BF, the printed circuit board LP also has one or more conductor tracks LB as part of the circuit TS or as an electrical connection to the circuit TS, which in turn have one or more contact surfaces KF for establishing an electrical (signal) connection with the power electronics module LM. The printed circuit board LP has a metal layer MS made of copper or a copper alloy on the end surface SS adjacent to the underside and the upper side facing the power electronics module LM, which metal layer MS is bonded to the end surface SS, for example, as a thin metal stamping. Alternatively, the metal layer MS can be applied to the end surface SS by electrodeposition. In particular, the metal layer MS can be applied to the end face SS in the same metallization process as the conductor track LB. The metal layer MS completely or almost completely covers the end face SS.

[0036] A switchable half bridge of a switchable bridge circuit is formed on the power electronic module LM. In this case, the power electronic module LM has a ceramic substrate KS, for example a DBC or AMB substrate, which in turn has a metal cooling layer KL on its respective underside and is placed on the housing bottom GB via the metal cooling layer and is physically and thermally connected to the housing bottom. The power electronic module LM has two metal bus bars SS1, SS2 ("Bus bars" in English) on the upper side of the respective ceramic substrate KS, which are physically separated from each other and thus electrically insulated by grooves GR extending transversely through the respective ceramic substrate KS.

[0037] The power electronic module LM has two unpackaged power semiconductor switches HS1 and HS2, respectively. In the present embodiment, the power semiconductor switches are configured as SiC-MOSFETs (in English, "Silicon Carbide Metal Oxide Semiconductor Field-Effect Transistor"). The first semiconductor switches HS1 of the respective power electronic modules LM are respectively mounted on the respective first busbar SS1 of the same power electronic module LM via their respective bottom-side drain terminals DA and are electrically connected to the first busbar. Similarly, the second semiconductor switches HS2 of the respective power electronic modules LM are respectively mounted on the respective second busbar SS2 of the same power electronic module LM via their respective bottom-side drain terminals DA and are electrically connected to the second busbar. The first semiconductor switches HS1 are respectively electrically connected to the respective second busbar SS2 of the same power electronic module LM via the respective top-side source terminals SA through bonding strips BB. The first semiconductor switches HS1 are respectively electrically connected to the respective corresponding contact surfaces KF on the printed circuit board LP via the respective top-side gate terminals GA through bonding wires BD.

[0038] The device V further comprises a silicone gel VG or a sealing gel applied to the power electronic modules LM. The silicone gel VG fills the gaps between the power electronic modules LM and the gaps between the power electronic modules LM on the one hand and the printed circuit board LP on the other hand and completely or almost completely covers or seals the power electronic modules LM and thereby protects the power electronic modules LM from environmental influences and voltage breakdown. In this case, the silicone gel VG extends as far as the metal layer MS of the printed circuit board LP and partially covers the metal layer MS, wherein the metal layer MS completely isolates or separates the end face SS of the printed circuit board LP and thereby also the printed circuit board LP from the silicone gel VG physically. The metal layer MS thus acts as a barrier between the silicone gel VG and the end face SS of the printed circuit board LP or the printed circuit board LP and prevents direct physical contact between the silicone gel VG and the end face SS. In order not to cross the barrier caused by the metal layer MS, the silicone gel VG is filled up to a maximum filling height FH, which does not exceed the structural height BH of the upper edge OK of the metal layer MS. Due to the barrier caused by the metal layer MS, possible degassing of the printed circuit board LP, in particular at its end face SS, which may be caused, for example, by temperature fluctuations, is effectively prevented.

[0039] Due to the use of edge metallization with metal layer MS, printed circuit board LP can be positioned very close to power electronic module LM without said printed circuit board or its end face SS being in direct contact with silicone rubber VG. As a result, electrical connections, in other words bonding wires BD between power electronic module LM on the one hand and printed circuit board LP on the other hand, can be kept very short, whereby parasitic inductances in these electrical connections can in turn be kept low, which leads to improved controllability of power electronic module LM or power semiconductor switches HS1, HS2 and thus increases their reliability.

[0040] The production of the above-mentioned device V is carried out, for example, in particular as described below:

[0041] First, a metal layer MS is applied to the end face SS of the printed circuit board LP. The printed circuit board LP with the metal layer MS is then mounted on the projection VS of the housing GH. Subsequently, the power electronics module LM is sealed with silicone rubber VG, which is mounted, for example, on the housing bottom GB before the printed circuit board LP. In this case, the silicone rubber VG is filled up to a filling height FH, which is below the structural height BH of the upper edge OK of the metal layer MS. In this case, the silicone rubber VG fills the gap between the power electronics module LM and the printed circuit board LP and extends up to the metal layer MS of the printed circuit board LP and covers it. The metal layer MS physically separates the end face SS of the printed circuit board LP from the silicone rubber VG completely.

Claims

1. An electrical device (V) having: - a component (LM) which is at least partially covered with a gel (VG); a printed circuit board (LP) having an end face (SS), to which a metal layer is applied, said metal layer at least partially covering said end face (SS); - wherein said metal layer (MS) is at least partially covered by said gel (VG); - wherein said metal layer (MS) physically and completely separates said end surface (SS) from said gel (VG).

2. The device (V) according to claim 1, wherein the component (LM) is an electronic module or an electronic device.

3. The device (V) according to claim 1 or 2, wherein the printed circuit board (LP) is a printed circuit board with fiber-reinforced plastic.

4. The device (V) according to claim 1, wherein a drive / control circuit (TS) for operating and / or for controlling the component (LM) is formed on the printed circuit board (LP).

5. The device (V) according to any one of the preceding claims, wherein - the printed circuit board (LP) has at least one electrical conductor track (LB); The metal layer (MS) is applied to the end face (SS) in the same metallization process as the conductor track (LB).

6. Device (V) according to any of the preceding claims, wherein the metal layer (MS) is a metal layer electrodeposited on the end surface (SS).

7. The device (V) according to any of the preceding claims 1 to 5, wherein the metal layer (MS) is designed as a metal plate.

8. The device (V) according to claim 7, wherein the metal plate is applied to the end surface (SS) by a material-fit connection.

9. Device (V) according to any of the preceding claims, wherein said gel (VG) is a sealing gel or silicone for hermetically sealing said component (LM).

10. The device (V) according to any of the preceding claims, wherein a filling height (FH) of the gel (VG) does not exceed a structural height (BH) of the upper edge (OK) of the metal layer (MS).

11. The device (V) according to any of the preceding claims, wherein the component (LM) and the printed circuit board (LP) are arranged offset from one another or in a row in a longitudinal direction (LR) of the device (V).

12. Device (V) according to any one of the preceding claims 1 to 10, wherein the printed circuit board (LP) is constructed in such a way as to at least partially surround the component (LM).

13. A device (V) according to any of the preceding claims, which is configured as an inverter or a DC voltage converter, wherein the component (LM) is a power electronic module and a drive / control circuit for operating and / or controlling the power electronic module is configured on the printed circuit board (LP).

14. A method for producing a device (V) according to any one of the preceding claims, the method comprising the steps of: - applying a metal layer (MS) onto the end surface (SS) of the printed circuit board (LP), wherein the metal layer (MS) at least partially covers the end surface (SS); - at least partially covering the component (LM) with the gel (VG) by applying the gel (VG) onto the component (LM); - wherein the gel (VG) is applied in such a way that the gel (VG) at least partially covers the metal layer (MS) and at the same time the gel (VG) is physically completely isolated from the end surface (SS) of the printed circuit board (LP) by the metal layer (MS).

Images