Power conversion device

1. A power conversion device comprising:

a heat releasing heatsink;

a printed circuit board provided on the heatsink, and having a through hole and wires;

a metal case having a depressed portion fitted in the through hole and mounted on a top of the heatsink, the metal case including a bottom portion and a sidewall portion enclosing the depressed portion;

a heat releasable insulating layer made of a ceramic material, and disposed between a bottom of the depressed portion and a top portion of the heatsink; and

a power semiconductor element mounted in the depressed portion and electrically connected to the wires of the printed circuit boards,

wherein the insulating layer is disposed to cover an entire lower surface of the bottom portion of the metal case and is in direct contact with the printed circuit board.

2. The power conversion device according to claim, 1

wherein the heat releasable insulating layer has a heat conductivity of 1 to 300 W/m·K and a thickness of 10 to 500 μm.

3. The power conversion device according to claim 1 , wherein the heat releasable insulating layer is formed of at least one kind of filler selected from the group consisting of silicon oxide, aluminum oxide, silicon nitride, aluminum nitride, or boron nitride fillers.

4. The power conversion device according to claim 1 , wherein the heat releasable insulating layer is formed of at least one kind of deposited ceramic particles by a plasma spraying method.

5. The power conversion device according to claim 1 , wherein the insulating layer is formed of at least one kind of deposited ceramic particles formed by an aerosol deposition method.

6. The power conversion device according to claim 1 , wherein the printed circuit board directly contacts the heatsink.

7. The power conversion device according to claim 1 , wherein the metal case includes a flange portion provided on an upper end of the sidewall portion and extending outwardly from the sidewall portion.

8. The power conversion device according to claim 7 , Wherein the printed circuit hoard further includes a metal foil pattern provided on an upper surface thereof to face the flange portion, and the flange portion and the metal foil pattern being soldered together.

9. The power conversion device according to claim 7 , further comprising a conductor portion formed on inner wall surfaces of the through hole of the printed circuit board, and including an upper surface land portion and a lower surface land portion,

wherein the upper surface land portion is disposed between the printed circuit board and the flange portion of the metal case, and

the insulating layer is arranged beyond a lower surface of the bottom portion of the metal case to cover the top portion of the heatsink, and the lower surface land portion is disposed between the printed circuit board and the insulating layer.

10. The power conversion device according to claim 7 , wherein the insulating layer is disposed to cover side surfaces of the sidewall portion of the metal case.

11. The power conversion device according to claim 10 , wherein the printed circuit board directly contacts the heatsink.

12. The power conversion device according to claim 11 , wherein a distance between the lower surface of the bottom portion and a lower surface of the flange portion in a thickness direction of the printed circuit board is substantially equal to a thickness of the printed circuit board in the thickness direction.

13. The power conversion device according to claim 10 , wherein the insulating layer is disposed to further cover a lower surface of the flange portion of the metal case.

14. The power conversion device according to 13 , wherein the printed circuit board directly contacts the heatsink.