System and method for reduced thermal resistance between a power electronics printed circuit board and a base plate

1. An apparatus comprising:

a base plate including a plurality of depressions and a plurality of first holes in the base plate;

a power electronics printed circuit board including a plurality of traces, a plurality of high voltage components, and a plurality of second holes in the power electronics printed circuit board, the plurality of high voltage components being located at a plurality of locations corresponding to the plurality of depressions in the base plate;

a plurality of fasteners extending through the plurality of first and second holes and securing the printed circuit board to the base plate with the plurality of high voltage components received at the corresponding plurality of depressions;

and a thermally conductive and electrically isolating interface between the base plate and the printed circuit board, the interface being made of a gap filler material conforming to the base plate and to the plurality of depressions in the base plate, and conforming to the printed circuit board and to the plurality of high voltage components;

wherein conforming of the gap filler material maintains contact between the base plate and substantially all of a surface of the printed circuit board including the plurality of traces and the plurality of high voltage components so that the printed circuit board is secured to the base plate by the plurality of fasteners substantially without deflection of the printed circuit board, and wherein a gap between either the power electronics printed circuit board and the base plate or the high voltage components and the base plate is less than 2 mm.

2. The apparatus of claim 1 wherein interface is formed by applying the gap filler material as a substantially liquid material that cures into a solid, such that the substantially liquid material is displaced when the printed circuit board is secured to the base plate to cause the gap filler material to conform to the base plate, the plurality of depressions, the printed circuit board, and the plurality of high voltage components.

3. The apparatus of claim 2 wherein the gap filler material is applied in two parts which are mixed and that cure into the solid.

4. The apparatus of claim 2 wherein the interface includes a substantially uniform layer of the gap filler material between the printed circuit board and the base plate.

5. The apparatus of claim 4 wherein the layer covers the plurality of high voltage components.

6. The apparatus of claim 1 wherein the interface includes a substantially uniform layer of the gap filler material between the printed circuit board and the base plate.

7. The apparatus of claim 6 wherein the layer covers the plurality of high voltage components.

8. An onboard battery charger for an automotive vehicle, the battery charger comprising:

a housing including a base plate, the base plate including a plurality of depressions and a plurality of first holes in the base plate;

a power electronics printed circuit board including a plurality of traces, a plurality of high voltage components, and a plurality of second holes in the power electronics printed circuit board, the plurality of high voltage components being located at a plurality of locations corresponding to the plurality of depressions in the base plate, the printed circuit board including a battery charger circuit;

a plurality of fasteners extending through the plurality of first and second holes and securing the printed circuit board to the base plate with the plurality of high voltage components received at the corresponding plurality of depressions; and

a thermally conductive and electrically isolating interface between the base plate and the printed circuit board, the interface being made of a gap filler material conforming to the base plate and to the plurality of depressions in the base plate, and conforming to the printed circuit board and to the plurality of high voltage components;

wherein conforming of the gap filler material maintains contact between the base plate and substantially all of a surface of the printed circuit board including the plurality of traces and the plurality of high voltage components so that the printed circuit board is secured to the base plate by the plurality of fasteners substantially without deflection of the printed circuit board, and wherein a gap between either the power electronics printed circuit board and the base plate or the high voltage components and the base plate is less than 2 mm.

9. The battery charger of claim 8 wherein interface is formed by applying the gap filler material as a substantially liquid material that cures into a solid, such that the substantially liquid material is displaced when the printed circuit board is secured to the base plate to cause the gap filler material to conform to the base plate, the plurality of depressions, the printed circuit board, and the plurality of high voltage components.

10. The battery charger of claim 9 wherein the gap filler material is applied in two parts which are mixed and that cure into the solid.

11. The battery charger of claim 9 wherein the interface includes a substantially uniform layer of the gap filler material between the printed circuit board and the base plate.

12. The battery charger of claim 11 wherein the layer covers the plurality of high voltage components.

13. The battery charger of claim 8 wherein the interface includes a substantially uniform layer of the gap filler material between the printed circuit board and the base plate.

14. The battery charger of claim 13 wherein the layer covers the plurality of high voltage components.

15. The battery charger of claim 8 wherein the printed circuit board has a length of at least 6 inches and a width of at least 6 inches.

16. A method of making a power electronics apparatus, the method comprising:

providing a base plate including a plurality of depressions and a plurality of first holes in the base plate;

providing a power electronics printed circuit board including a plurality of traces a plurality of high voltage components, and a plurality of second holes in the power electronics printed circuit board, the plurality of high voltage components being located at a plurality of locations corresponding to the plurality of depressions in the base plate;

forming a thermally conductive and electrically isolating interface between the base plate and the printed circuit board, the interface being made of a gap filler material conforming to the base plate and to the plurality of depressions in the base plate, and conforming to the printed circuit board and to the plurality of high voltage components; and

securing the printed circuit board to the base plate with the plurality of high voltage components received at the corresponding plurality of depressions;

wherein conforming of the gap filler material maintains contact between the base plate and substantially all of a surface of the printed circuit board including the plurality of traces and the plurality of high voltage components so that the printed circuit board is secured to the base plate by a plurality of fasteners substantially without deflection of the printed circuit board, and wherein a gap between either the power electronics printed circuit board and the base plate or the high voltage components and the base plate is less than 2 mm.

17. The method of claim 16 wherein forming further comprises:

applying the gap filler material as a substantially liquid material that cures into a solid, such that the substantially liquid material is displaced when the printed circuit board is secured to the base plate to cause the gap filler material to conform to the base plate, the plurality of depressions, the printed circuit board, and the plurality of high voltage components.

18. The method of claim 17 wherein the gap filler material is applied in two parts which are mixed and that cure into the solid.

19. The method of claim 17 wherein the interface includes a substantially uniform layer of the gap filler material between the printed circuit board and the base plate.

20. The method of claim 19 wherein the layer covers the plurality of high voltage components.