Power semiconductor module assembly with heat dissipating element

1. A power semiconductor module assembly comprising:

a power semiconductor module comprising a load terminal and a power semiconductor chip;

an anisotropic thermally conductive heat dissipating element comprising

a first contact face thermally coupled to a first heat sink,

a second contact face thermally coupled to an electrically and thermally conductive contact conductor electrically conductively joined to the load terminal and to the power semiconductor chip,

a third contact face thermally coupled to the load terminal, where the heat dissipating element is defined by a first thermal resistor between the third contact face and the first contact face; and

a second thermal resistance which is greater than the first thermal resistance between the third contact face and the second contact face.

2. The assembly of claim 1 wherein a portion of the heat dissipating element is sandwiched between the load terminal and the contact conductor.

3. The assembly of claim 1 wherein the heat dissipating element is a graphite film.

4. The assembly of claim 1 wherein the heat dissipating element comprises at at least one location in at least one direction a maximum thermal conductivity which is greater than 400 W/(K·m).

5. The assembly of claim 1 wherein the heat dissipating element comprises at at least one location in at least one direction a minimum thermal conductivity which is smaller than 40 W/(K·m).

6. The assembly of claim 1 wherein the heat dissipating element comprises at at least one location of the second contact face in the direction of the normal of the second contact face a second thermal conductivity smaller than a first thermal conductivity which the heat dissipating element comprises at the location in a direction perpendicular to the direction of the normal.

7. The assembly of claim 6 wherein the first thermal conductivity equals the maximum thermal conductivity of the heat dissipating element.

8. The assembly of claim 6 wherein the second thermal conductivity equals the minimum thermal conductivity of the heat dissipating element.

9. The assembly of claim 6 wherein the first thermal conductivity amounts to at least ten times the second thermal conductivity.

10. The assembly of claim 1 wherein the first contact area is at least twice as large as the second contact area.

11. The assembly of claim 1 wherein the power semiconductor module comprises a base plate thermally coupled to the first heat sink.

12. The assembly of claim 1 wherein the heat dissipating element is electrically isolated from the first heat sink by a thermally conductive dielectric.

13. The assembly of claim 1 wherein the power semiconductor module comprises a base plate thermally coupled at its side facing away from the power semiconductor chip to a second heat sink.

14. The assembly of claim 1 wherein the contact conductor is configured as a steep busbar.

15. The assembly of claim 1 wherein the contact conductor is configured as a flexible conductor layer.

16. A power semiconductor module assembly including

a power semiconductor module comprising a load terminal and a power semiconductor chip;

an electrically and thermally conductive contact conductor electrically conductively joined to the load terminal and to the power semiconductor chip;

a heat sink;

an anisotropic thermally conductive heat dissipating element comprising a first contact area via which it is thermally coupled to the heat sink, and a second contact area via which it is thermally coupled to the contact conductor and which is smaller than the first contact area.

17. The assembly of claim 16 wherein the heat dissipating element comprises a third contact face via which it is thermally coupled to the load terminal, wherein

the heat dissipating element comprises along a first path P 1 running the shortest possible within the heat dissipating element from the third contact face to the first contact face, at at least one location a minimum first thermal conductivity in the direction of the path; and

the heat dissipating element comprises along a second path P 2 running the shortest possible within the heat dissipating element from the third contact face to the second contact face, at at least one location a maximum second thermal conductivity in the direction of the path which is smaller than the first thermal conductivity.

18. A power semiconductor module assembly comprising:

a power semiconductor module comprising a load terminal and a power semiconductor chip;

an electrically and thermally conductive contact conductor electrically conductively joined to the load terminal and to the power semiconductor chip;

a heat sink; and

an anisotropic thermally conductive heat dissipating element comprising a portion sandwiched between the load terminal and the contact conductor,

the heat dissipating element comprising a first contact face via which it is thermally coupled to the heat sink and a second contact face via which it is thermally coupled to the first contact conductor, the heat dissipating element comprising at at least one location of the second contact face in the direction of the normal of the second contact face a second thermal conductivity which is smaller than the first thermal conductivity which the heat dissipating element comprises at the location in a direction perpendicular to the direction of the normal.