Power module, assembly and method for fixing a control pin

Abstract

The invention relates to a power module (1), an assembly (11) and a method for fastening a control pin (13), the power module (1) comprising a carrier (2) having a structured metallization (3), at least one power semiconductor (4) being arranged on the metallization (3) and the metallization (3) having at least one contact surface (7) for the control pin (13), the power module (1) being encapsulated with a potting compound (9), according to the invention, a base element (5) is arranged on the at least one contact surface (7) for the control pin (13), said base element being electrically connected to the contact surface (7), at least one top side (10) of the base element (5) being not covered by the potting compound (9), the top side (10) having a closed surface which is much larger than the contact surface of the control pin (13).

Description

TECHNICAL FIELD

[0001] The invention relates to a power module, an assembly having at least two power modules and a method for fixing a control pin to such an assembly. BACKGROUND

[0002] Power modules are often used in inverters, DC / DC converters or other switching components. The power module has at least one power semiconductor, which is designed, for example, as an IGBT, MOSFET or GaN HEMT. Usually, the power module has a plurality of power semiconductors. The power semiconductors are arranged on a carrier with a structured metallization. The carrier is, for example, a ceramic which is electrically insulating but good heat conducting. Well-known technologies include IMS (isolated metal substrate) or DCB (direct copper bonding). The partial contact between the power semiconductors is made by means of the metallization. The external voltage is supplied by means of large-area contacts, which are designed, for example, as a lead frame. The output connections are also led out as large-area contacts. The control pins are usually arranged on the contact surface of the metallization layer and are led vertically upwards (i.e. they are parallel to the surface normal of the carrier) for providing a control signal for the control electrode (gate) or recording a measurement signal (for example, the temperature is detected by means of a Kelvin source electrode contact).

[0003] It is also known that power modules are potted for protection. A plurality of such power modules can then be arranged on a common carrier, for example, a heat sink.

[0004] It is known to connect the control pins to the power module only after potting. For this purpose, a pin sleeve is arranged on the respective contact surface of the metallization layer. The surface of the hollow-cylindrical pin sleeve is not potted, so that the control pin can be inserted into the pin sleeve after potting.

[0005] Such a pin sleeve is described, for example, in CN 115274472 A. SUMMARY

[0006] The technical problem addressed by the invention is to create a power module which improves the contact of the control pin. A further technical problem is to create an assembly having a plurality of power modules and a method for fixing a control pin.

[0007] The solution to the technical problem is derived from the power module having the features of claim 1, the assembly having the features of claim 8 and the method having the features of claim 9. Further advantageous embodiments of the invention result from the dependent claims.

[0008] The power module comprises a carrier with a structured metallization, at least one power semiconductor is arranged on the metallization, and the metallization has at least one contact surface for a control pin, which power module is potted with a potting compound. A base element is arranged on the at least one contact surface for a control pin and is electrically connected to the contact surface, wherein at least one top side of the base element is not covered by the potting compound. The top side of the base element has a much larger closed surface than the contact surface of the control pin. This provides greater flexibility for arranging the control pin on the base element, thus compensating for the resulting geometric offset, in particular when two or more power modules are arranged to form an assembly on a common carrier, for example a heat sink. A further advantage of the closed surface is that the potting requirements are reduced compared to the prior art, in which it must always be ensured that no potting compound flows into the pin sleeve of the opening.

[0009] In one embodiment, the at least one base element is designed to be rotationally symmetrical, wherein the top side is preferably a circular surface.

[0010] In another embodiment, the base element is a cylinder or a truncated cone, wherein the larger side of the truncated cone forms the top side.

[0011] In another embodiment, the base element is dumbbell-shaped and consists of three cylinders, the middle cylinder having a smaller diameter. The advantage is that the base element is better surrounded by the potting compound.

[0012] In another embodiment, the base element additionally has a circumferential ring. This ring serves as a support surface for the ultrasonic tool head in order to fix the base element to the contact surface using friction welding.

[0013] In another embodiment, the base element is designed as a hollow body, so that material can be saved, while the increase in electrical resistance is negligible.

[0014] In another embodiment, a pin sleeve is arranged on the top side of the base element. The pin sleeve is preferably applied to the surface after potting. The advantage is that the control pin can be inserted into the pin sleeve using known methods. The pin sleeve is then only shorter than in the prior art.

[0015] The assembly according to the application comprises at least two of the previously described power modules arranged on a common carrier, which carrier is preferably a heat sink.

[0016] The method for fixing the control pins to the assembly is performed by assigning a geometric position relative to the common carrier to the individual control pins. These are in fact the target positions which the control pins should have so that they correspond to the circuit board on which, for example, a gate driver is arranged. The control pins can then be positioned and fixed to the base elements assigned to them using the corresponding positioning devices. Since the surface area of the base elements is increased, it is now possible to compensate for positional deviations of the power modules on the carrier, for example if the power modules are not aligned exactly parallel to the edges of the carrier. BRIEF DESCRIPTION OF DRAWINGS

[0017] The application is explained in more detail below using preferred exemplary embodiments. The drawings show:

[0018] Figure 1 a schematic view of a power module before potting with potting compound,

[0019] Figure 2 a schematic view of a power module after potting,

[0020] Figure 3 a schematic view of an assembly with three power modules,

[0021] Figure 4 a schematic view of an assembly with control pins,

[0022] Figure 5 a dumbbell-shaped base element, and

[0023] Figure 6 a base element with a circumferential ring. DETAILED DESCRIPTION

[0024] In Figure 1 , a power module 1 before potting with potting compound is shown in a very simplified manner. The power module 1 has a carrier 2, on which a structured metallization 3 is applied. Usually, the metallization is also applied to the underside of the carrier. The carrier 2 is, for example, ceramic. Four power semiconductors 4, four base elements 5 and three connection contacts 6 in the form of lead frames are arranged on the structured metallization 3. The four power semiconductors 4 are, for example, designed as MOSFETs, which, for example, form a half-bridge. For this purpose, two power semiconductors are connected in parallel and the two parallel circuits are connected in series. HV+ and HV- are then provided via two upper connection contacts 6, the lower connection contacts 6 lead out the center tap of the half-bridge. The base elements 5 are connected to the gate contacts of the power semiconductors 4 and are arranged on the contact faces 7 of the structured metallization 3. The base elements 5 are, for example, soldered or welded to the contact faces 7. The base elements are designed as cylinders 8.

[0025] Figure 2A power module 1 is shown after potting with potting compound 9, wherein the top side 10 of the connecting contacts 6 and the base element 5 remains freely accessible. The metallization layer applied to the lower side of the carrier 2 also remains uncovered by the potting compound 9.

[0026] Figure 3 A component 11 is shown, which consists of three power modules 1 according to Figure 2 arranged on a common carrier 12. The power modules 1 are, for example, soldered or sintered. This can lead to a geometric offset between the power modules 1 from one another. However, the target positions of the control pins 13, which they should have, are known, so that they can be connected to a circuit board (not shown). Since the top side 10 of the base element 5 is significantly larger than the contact surface of the control pins 13, it is now possible to arrange them on the top side 10 of the base element 5 so that they are in their target positions, as Figure 4 indicated. This means that, despite the geometric offset of the power modules 1, all control pins 13 are in one position, as if the power modules 1 were aligned correctly. If the power modules 1 were aligned correctly, all control pins 13 would be arranged at the center of the top side 10 of the base element 5.

[0027] Figure 5 An alternative embodiment of the base element 5 is shown, which consists of three cylinders 8, of which the upper and lower cylinders 8 have a larger diameter. This forms a dumbbell shape.

[0028] Figure 6 Another alternative embodiment of the base element 5 is shown, which is designed as a cylinder 8 with a circumferential ring 14.

[0029] In general, the base elements 5 can be made of copper or aluminum. The base elements 5 can also each be designed as a solid body or a hollow body.

[0030] List of reference signs

[0031] 1 power module

[0032] 2 carrier

[0033] 3 structured metallization

[0034] 4 power semiconductor

[0035] 5 base element

[0036] 6 connecting contact

[0037] 7 contact surface

[0038] 8 cylinder

[0039] 9 potting compound

[0040] 10 top side

[0041] 11 component

[0042] 12 carrier

[0043] 13 control pin

[0044] 14 circumferential ring

Claims

1. A power module (1) comprising a carrier (2) having a structured metallized portion (3), wherein, At least one power semiconductor (4) is disposed on the metallization portion (3) and the metallization portion (3) has at least one contact surface (7) for a control pin (13), wherein the power module (1) is encapsulated with potting compound (9). Its features are, A base element (5) is arranged on at least one contact surface (7) for the control pin (13), the base element being electrically connected to the contact surface (7), wherein at least one top side (10) of the base element (5) is not covered by the potting compound (9), wherein the top side (10) has a closed surface that is much larger than the contact surface of the control pin (13).

2. The power module according to claim 1, characterized in that, The base element (5) is designed to be rotationally symmetric.

3. The power module according to claim 2, characterized in that, The base element (5) is at least one cylinder (8) or a truncated cone.

4. The power module according to claim 2 or 3, characterized in that, The base element (5) is designed in the shape of a dumbbell.

5. The power module according to any one of claims 2 to 4, characterized in that, The base element (5) also has a circumferential ring (14).

6. The power module according to any one of the preceding claims, characterized in that, The base element (5) is designed as a hollow body.

7. The power module according to any one of the preceding claims, characterized in that, A pin sleeve is arranged on the top side (10) of the base element (5).

8. A component (11) comprising at least two power modules (1) arranged on a common carrier (12) according to any one of claims 1 to 7.

9. A method for attaching a control pin (13) according to claim 8 to a component (11), characterized in that, The control pin (13) is assigned a geometric position relative to the common carrier (12), wherein the control pin (13) is positioned and fixed on the assigned base element (5) at the assigned geometric position.

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