WO2021073966A1

WO2021073966A1 - Circuit substrate for a semiconductor module, semiconductor module and method for producing a semiconductor module

Info

Publication number: WO2021073966A1
Application number: PCT/EP2020/078079
Authority: WO
Inventors: Jens Reiter; Christian Lammel
Original assignee: Vitesco Technologies GmbH
Priority date: 2019-10-14
Filing date: 2020-10-07
Publication date: 2021-04-22
Also published as: DE102019215792A1

Abstract

A circuit substrate for a semiconductor module, wherein the circuit substrate comprises the following: – at least one first printed circuit board formed from a glass fiber/epoxy resin composite material, – at least one second printed circuit board embodied as a metal-core printed circuit board, wherein the at least one second printed circuit board is arranged in a cutout of the first printed circuit board and is connected to the latter by means of a soldered joint. Also described are a semiconductor module and a method for producing a semiconductor module.

Description

description

Circuit substrate for a semiconductor module, semiconductor module and method for producing a semiconductor module

The present invention relates to a circuit substrate for a semiconductor module, a semiconductor module and a method for producing a semiconductor module.

Semiconductor modules with several semiconductor components, for example power components, typically comprise either printed circuit boards made of a glass fiber-epoxy resin composite material (FR4), which can be multi-layered, are relatively inexpensive and also both SMD (Surface Mounted Device) connection techniques and connection techniques such as press-fit as a circuit substrate or TRT (through hole technology) and are therefore versatile.

Alternatively, in particular, power semiconductor modules can also have DCB (direct copper bonded) or IMS (insulated metal substrate) substrates, which are typically only formed in one layer and have a metallic base plate, for example made of aluminum or copper, on which a dielectric layer and a wiring layer, for example is applied from copper. Such substrates allow particularly good heat dissipation, but only allow the use of SMD connection techniques, since other connection techniques require complex insulation because of the electrically conductive metallic base plate and would make the connection of a heat sink more difficult.

A circuit substrate for a semiconductor module is known from DE 102015223551 A1, in which carrier plates of different technologies are combined to form a self-supporting hybrid substrate, with a sub-carrier insert formed, for example, as a DBC substrate being embedded in a PCB substrate and pressed with it. It is an object of the present invention to provide a new circuit substrate for a semiconductor module that is particularly easy to manufacture, can be used flexibly and / or has both the advantages of a printed circuit board made of fiberglass-epoxy resin composite material and those of a metal core printed circuit board and is particularly suitable for use is suitable in power semiconductor modules. Furthermore, a method for producing a semiconductor module is to be specified.

This problem is solved by the subject matter of the independent claims. Advantageous embodiments and developments are the subject of the subclaims.

According to one aspect of the invention, a circuit substrate for a semiconductor module is specified, the circuit substrate having at least one first circuit board formed from a glass fiber-epoxy resin composite material and at least one second circuit board formed as a metal core circuit board. The at least one second printed circuit board is arranged in a recess in the first printed circuit board and connected to it by means of a soldered connection, in particular by means of an SMD soldered connection.

A printed circuit board made of a glass fiber-epoxy resin composite is understood here and below to mean a printed circuit board used in semiconductor components with an electrically non-conductive carrier matrix, in particular made of FR4 material, which has one or more conductor track layers, for example made of copper. Such circuit boards have a fiberglass fabric embedded in the epoxy resin.

A metal core circuit board is understood here and in the following to be a circuit board as it is also known by the designations DCB substrate or IMS and which has at least one dielectric layer applied to a metallic base plate and a conductor track layer arranged thereon. The fact that the second circuit board is connected to the first circuit board by means of a soldered connection can mean, for example, that a solder layer is arranged between the two circuit boards - preferably in places - to which the first and second circuit boards adjoin on opposite sides, so that the solder layer the Electrically and mechanically connects circuit boards. The fact that the soldered connection is an SMD soldered connection means in particular that the soldered connection is produced using SMD technology. The production of the soldered connection using SMD technology can include, for example, the printing of a solder paste on the first and / or the second circuit board, subsequent assembly of the circuit boards and heating of the assembled circuit boards in an oven to melt the solder paste.

The circuit substrate has the advantage that it has the advantages of a metal core circuit board in some areas, namely where particularly effective heat dissipation is to be achieved, and in other areas it has the advantages of a circuit board made of a fiberglass-epoxy resin composite material.

In particular, the second printed circuit board provides a substrate which is particularly suitable for equipping with power components because it enables particularly good heat dissipation. The first circuit board, on the other hand, allows a particularly simple and versatile connection to further circuit boards or components arranged on the first circuit board, for example a control for power components. The first circuit board thus enables the use of extensive possibilities of connection technology both to the outside and to components arranged on the first circuit board.

The circuit substrate is therefore particularly well suited for producing a power semiconductor module in which a plurality of power components must be effectively cooled and at the same time a control for the power components must be electrically connected in a simple manner. According to one embodiment, the first printed circuit board has a plurality of cutouts and a second printed circuit board designed as a metal core printed circuit board is arranged in each of the cutouts.

Such a circuit substrate is particularly suitable for receiving a plurality of power components to form a power semiconductor module, for example for use in a high-voltage battery box of an electric vehicle.

According to one embodiment, the soldered connection between the first and the second circuit board is formed in that both the at least one first circuit board and the at least one second circuit board have corresponding solder pads that are connected to one another via a solder material.

In this embodiment, it is provided that the first circuit board and the second circuit board overlap in places, in particular in areas around the cutouts, so that, for example, an upper side of the second circuit board comes into contact with an underside of the first circuit board. In the contact area, the two circuit boards each have corresponding, i.e. matching, solder pads that are connected to one another in an SMD soldering process by means of a solder material.

This embodiment has the advantage that the two circuit boards can be mechanically and electrically connected to one another in a particularly simple manner. In particular, a large number of connection points can be produced in a simple manner and connected to one another in a single soldering process.

According to one embodiment, the at least one second circuit board designed as a metal core circuit board has an aluminum base plate on which a single-layer conductor track structure with a dielectric layer made of polymer filled with ceramic powder is arranged.

In this embodiment, the second printed circuit board is designed in a known manner as a so-called IMS substrate. The use of a metal base plate For example, aluminum has the advantage that the circuit substrate is inexpensive and at the same time enables good heat dissipation.

According to one embodiment, the at least one first printed circuit board has a multi-layer conductor track structure made up of a plurality of electrically conductive and a plurality of electrically insulating layers.

This embodiment has the advantage that the multilayer first printed circuit board allows the connections to be unbundled particularly well. This allows particularly flexible options for the layout of the circuit.

According to one aspect of the invention, a semiconductor module with the circuit substrate described is specified, a power component being arranged on an upper side of the at least one second printed circuit board.

A controller for the power component can also be arranged on an upper side of the at least one first printed circuit board. If the semiconductor module has more than one power component, the controller can be designed as a controller for the plurality of power components. A control is in particular an electronic circuit that is designed for control - for example for switching and / or regulating the power component or the power components.

According to one embodiment, an underside of the at least one second printed circuit board is in contact with a heat sink. In particular, it is in direct mechanical contact with the heat sink or is connected to the heat sink by means of a layer of thermal paste.

In this embodiment, particularly good cooling of the power components is achieved in that the second printed circuit boards are cooled directly. The heat sink can be part of an air or liquid cooling system for the semiconductor module. According to one embodiment, the semiconductor module comprises at least one further printed circuit board, which is electrically connected to the circuit substrate via connections on the first printed circuit board.

In this embodiment it is advantageously used that the first circuit board due to its design as a circuit board from a

Fiberglass-epoxy resin composite offers particularly flexible connection technology options.

Power components arranged on the at least one second printed circuit board are therefore only contacted via the soldered connections to the first printed circuit board.

According to one aspect of the invention, a method for producing a semiconductor module is specified, which comprises providing at least one first printed circuit board formed from a glass fiber-epoxy resin composite material, providing at least one second printed circuit board constructed as a metal core printed circuit board and equipped with at least one power component, and arranging which comprises at least one second circuit board in a recess of the first circuit board. The method further comprises connecting the at least one second printed circuit board to the first printed circuit board via a soldered connection.

The soldered connection between the first and the second circuit board is formed, for example, in that both the first circuit board and the at least one second circuit board have corresponding solder pads that are connected to one another via a solder material.

For this purpose, it is provided in one embodiment that the first printed circuit board and the second printed circuit board overlap in places, in particular in areas around the cutouts, so that an upper side of the second printed circuit board comes into contact with a lower side of the first printed circuit board. In the contact area, the two circuit boards each have corresponding, ie matching, solder pads that are connected to one another in an SMD soldering process by means of a solder material. The at least one power component can be fixed during the connection of the at least one second circuit board to the first circuit board via a soldered connection by means of an SMD adhesive, in particular to avoid blurring of the power component when the solder is melted or re-melted.

The method provides a particularly simple option for providing a semiconductor module and a circuit substrate which has the advantages already described above.

Additional aspects of the present disclosure are described in the following text, with individual aspects being numbered to facilitate reference to features of other aspects.

1 . A circuit substrate for a semiconductor module, the circuit substrate comprising:

- At least one first printed circuit board made of a fiberglass-epoxy resin composite material,

At least one second printed circuit board designed as a metal core printed circuit board, the at least one second printed circuit board being arranged in a recess in the first printed circuit board and connected to it by means of a soldered connection.

2. The circuit substrate according to aspect 1, wherein the first printed circuit board has a plurality of cutouts and a second printed circuit board designed as a metal core printed circuit board is arranged in each of the cutouts.

3. Circuit substrate according to aspect 1 or 2, wherein the solder connection is formed in that both the at least one first circuit board and the at least one second circuit board have corresponding solder pads that are connected to one another via a solder material. 4. Circuit substrate according to one of the preceding aspects, wherein the soldered connection is designed as an SMD soldered connection.

5. Circuit substrate according to one of the preceding aspects, wherein the at least one second printed circuit board designed as a metal core printed circuit board has an aluminum base plate on which a single-layer conductor track structure with a dielectric layer is arranged.

6. Circuit substrate according to one of the preceding aspects, wherein the at least one first printed circuit board has a multi-layer conductor track structure made up of a plurality of electrically conductive and a plurality of electrically insulating layers.

7. A semiconductor module with a circuit substrate according to one of the preceding aspects, wherein a power component is arranged on a top side of the at least one second printed circuit board.

8. The semiconductor module according to aspect 7, wherein a controller for the power component is arranged on a top side of the at least one first printed circuit board.

9. The semiconductor module according to aspect 7 or 8, wherein an underside of the at least one second printed circuit board is in contact with a heat sink.

10. The semiconductor module according to one of aspects 7 to 9, wherein the semiconductor module comprises at least one further printed circuit board which is electrically connected to the circuit substrate via connections of the first printed circuit board.

11. A method of manufacturing a semiconductor module, comprising:

- Provide at least one of one

Fiberglass-epoxy composite formed first printed circuit board, Provision of at least one second circuit board configured as a metal core circuit board equipped with at least one power component, arranging the at least one second circuit board in a recess in the first circuit board and

- Connecting the at least one second printed circuit board to the first printed circuit board by means of a soldered connection.

12. The method according to aspect 11, wherein the at least one power component is fixed by means of an SMD adhesive during the connection of the at least one second circuit board to the first circuit board by means of the soldered connection.

Embodiments of the invention are described below by way of example with reference to schematic drawings.

FIG. 1 shows a plan view of a semiconductor module according to an embodiment of the invention;

FIG. 2 shows a sectional view of the semiconductor module according to FIG. 1 and FIG. 3 shows a detail of FIG.

FIG. 1 shows a plan view of a semiconductor module 1 with a housing 2 in which a circuit substrate 4 with semiconductor components 6 arranged thereon is arranged. The semiconductor components 6 are power semiconductor components which have relatively high power losses during operation and thus make effective heat dissipation necessary.

The circuit substrate 4 has a first printed circuit board 8, which has a glass fiber-epoxy resin composite material with conductor track structures. Furthermore, the circuit substrate 4 has several, in the embodiment shown in FIG. 1, a total of nine, second printed circuit boards 10, which are located in recesses the first circuit board 8 are arranged and which are designed as metal core circuit boards. The semiconductor components 6 are arranged on the second printed circuit boards 10.

The semiconductor components 6 are designed as surface-mounted components and applied to the upper sides 12 of the second printed circuit boards 10. The first printed circuit board 8 provides options, not shown, for making contact with the entire semiconductor module 1.

FIGS. 2 and 3 show the semiconductor module 1 in a sectional view, FIG. 3 showing the detail D from FIG.

In the sectional view it can be seen that the second circuit boards 10 are arranged in recesses 16 of the first circuit board 8, the second circuit boards 10 being arranged below the first circuit board 8 in such a way that the circuit boards 8, 10 overlap the upper sides in the edge regions of the recesses 16 12 of the second circuit boards 10 come to rest on undersides 14 of the first circuit board 8.

This can be seen in particular in detail in FIG. In the overlapping areas, the second circuit boards 10 have solder pads 18 which are exposed on the top side 12 of the circuit board 12. The first printed circuit board 8 has solder pads 20 which are exposed on its underside 14. The solder pads 18, 20 correspond to one another in such a way that they come to rest on one another when the second circuit boards 10 are inserted into the recesses 16 of the first circuit board 8.

To connect the second printed circuit boards 10 to the first printed circuit board 8, a solder material is introduced between the solder pads 18, 20 and soldered in a reflow process in order to create a mechanical and electrical connection between the second printed circuit boards 10 and the first printed circuit board 8.

The second printed circuit boards 10, which are designed as IMS substrates in the embodiment shown, stand with their metallic underside 13 a heat sink 22 of the semiconductor module 1 in contact. In the embodiment shown, the heat sink 22 has ribs around which a cooling liquid can flow for even better cooling.

Claims

1. A circuit substrate (4) for a semiconductor module (1), the circuit substrate (4) having the following:

- A first printed circuit board (8) formed from a glass fiber-epoxy resin composite material,

- At least one second printed circuit board designed as a metal core printed circuit board

(10), wherein the at least one second circuit board (10) is arranged in a recess (16) of the first circuit board (8) and is connected to it by means of a soldered connection, the at least one second circuit board (10) in this way below the first circuit board ( 8) is arranged so that the circuit boards (8, 10) overlap in the edge regions of the recesses (16) and a top side (12) of the at least one second circuit board (10) comes to rest on an underside (14) of the first circuit board (8) , wherein the at least one second circuit board (10) has solder pads (18) in the overlapping areas, which are exposed on the upper side (12) of the circuit board (10), and the first circuit board (8) has solder pads (20) on its The underside (14) are exposed, the solder pads (18, 20) corresponding to one another in such a way that they come to rest on one another when the at least one second circuit board (10) is inserted into the recesses (16) of the first circuit board (8).

2. The circuit substrate (4) according to claim 1, wherein the first circuit board (8) has a plurality of recesses (16) and a second circuit board (10) designed as a metal core circuit board is arranged in each of the recesses (16).

3. circuit substrate (4) according to any one of the preceding claims, wherein the solder connection is designed as an SMD solder connection.

4. Circuit substrate (4) according to one of the preceding claims, wherein the at least one second circuit board (10) designed as a metal core circuit board has an aluminum base plate on which a single-layer conductor track structure with a dielectric layer is arranged.

5. circuit substrate (4) according to any one of the preceding claims, wherein the first printed circuit board (8) has a multi-layer conductor track structure made of several electrically conductive and several electrically insulating layers.

6. Semiconductor module (1) with a circuit substrate (4) according to one of the preceding claims, wherein a power component (6) is arranged on a top side (12) of the at least one second printed circuit board (10).

7. The semiconductor module (1) according to claim 6, wherein a controller for the power component is arranged on a top side of the first printed circuit board (8).

8. The semiconductor module (1) according to claim 6 or 7, wherein an underside (13) of the at least one second printed circuit board (10) is in contact with a heat sink (22).

9. The semiconductor module (1) according to any one of claims 6 to 8, wherein the semiconductor module (1) comprises at least one further circuit board which is electrically connected to the circuit substrate (4) via connections of the first circuit board (8).

10. A method for producing a semiconductor module (1), which has the following:

- Provision of a first printed circuit board (8) formed from a fiberglass-epoxy resin composite material,

- Provision of at least one second printed circuit board (10) designed as a metal core printed circuit board and equipped with at least one power component (6), - Arranging the at least one second circuit board (10) in a recess (16) of the first circuit board (8), the at least one second circuit board (10) being arranged below the first circuit board (8) in such a way that in edge regions of the recesses (16 ) overlap the circuit boards (8, 10) and an upper side (12) of the at least one second circuit board (10) comes to rest on an underside (14) of the first circuit board (8), the at least one second circuit board (10) in the overlapping areas has solder pads (18) which are exposed on the upper side (12) of the circuit board (12), and the first circuit board (8) has solder pads (20) which are exposed on its underside (14), wherein the solder pads (18, 20) correspond to one another in such a way that they come to rest on one another when the at least one second circuit board (10) is inserted into the recess (16) of the first circuit board (8), and

- Mechanical and electrical connection of the at least one second circuit board (10) to the first circuit board (8) by means of a soldered connection by introducing a solder material between the solder pads (18, 20) and soldering in a reflow process.

11. The method according to claim 10, wherein the at least one power component (6) is fixed during the connection of the at least one second circuit board (10) to the first circuit board (8) by means of the soldered connection by means of an SMD adhesive.