THREE PHASE INVERTER POWER STAGE AND ASSEMBLY

Abstract

A three phase invertor has five coplanar leadframes for 2d-c terminals and 3a-c terminals. Power MOSFETs soldered around the periphery of one of the d-c leadframes are wire bonded to adjacent ones of the 3a-c leadframes which are mounted alongside the two edges and an end of one of the d-c leadframes. Further switching die are soldered to the 3a-c leadframes and wire bonded to the other d-c leadframe. The die are spaced along and follow a general U-shaped path. The leadframes are mounted on a heat sink which receives an insulation spacer and cap to form a hermetically sealed volume around the leadframes and die. The heat sink has cavities to mount bus capacitors and has a water cooling channel which follows and is below the U-shaped path of the die.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of the inverter structure of the invention.

FIG. 2 is a top plan view of the assembled leadframes of the invention.

FIG. 3 is a perspective view of the assembly of FIG. 2.

FIG. 3A is a detail view of the circled area in FIG. 3.

FIG. 4 shows the path of the cooling channel in a heat sink beneath the leadframes of FIG. 1.

FIG. 5 is a plan view of the leadframes of FIG. 1 without the die or wire bonds in place to show the substantial coplanarity of the leadframes.

FIG. 6 is an exploded perspective view of the leadframes and insulation printed circuit board (PCB) of FIGS. 1 and 5.

FIG. 7 is a detailed top view of a die mounted on a leadframe in FIG. 1.

FIG. 8 is a cross-section of FIG. 7 taken across section line 8-8 in FIG. 7.

FIG. 8A is a detail showing the bending of a leadframe extension in FIG. 8 to form a power terminal which extends perpendicularly from the plane of the leadframe.

FIG. 9 is a partly cut-away view of the leadframe assembly of FIGS. 2 to 8 assembled on a heat sink.

FIG. 9A is a detail of the capacitor connection terminals in FIG. 9.

FIG. 10 is an exploded perspective view of the housing and leadframe assembly.

FIG. 11 shows the assembly of FIG. 10 without the top cover.

FIG. 12 is a cross-section detail of the seal between the cover and heatsink of FIG. 10.

FIG. 13 and 14 show two respective isometric views of the assembly of FIG. 10.

FIG. 15 is a cross-sectional detail of the connector bolt of FIGS. 10, 13 and 14.

Claims

1. A power stage for a multiphase converter having two d-c terminals and at least 3a-c terminals; said planar power stage comprising separate flat leadframes insulated from one another and connected to respective ones of said terminals; each of said flat leadframes being generally co-planar; said leadframes for said two d-c terminals being disposed one atop the other and having a generally rectangular planar shape with first and second sides and first and second ends; said leadframes for said 3a-c terminals being disposed adjacent said first and second of said sides and one of said ends respectively and being coplanar with said leadframes for said two d-c terminals.

2. The structure of claim 1, wherein said converter is an inverter circuit for converting d-c power to a-c multiphase power.

3. The structure of claim 1, which further includes a first plurality of semiconductor die each having electrodes on their top and bottom surfaces; said first plurality of die having one of their said electrodes soldered to one of said two leadframes of said d-c terminals and spaced from one another and extending adjacent to said first and second sides and said one of said ends, along a general U-shaped path; the other of said electrodes of said first plurality of die being wire bonded to the surfaces of said leadframes of said 3a-c terminals which are adjacent to said die positions.

4. The structure of claim 1, wherein said die of said first plurality of die are MOSgated switching devices.

5. The structure of claim 4, wherein said converter is an invertor circuit for converting d-c power to a-c multiphase power.

6. The structure of claim 3, which further includes second, third and fourth pluralities of die which are identical to those of said first plurality of die each of said second, third and fourth pluralities of die being spaced along and having one of their electrodes soldered to respective ones of said leadframes for said three a-c terminals and having their other electrode wire bonded to an adjacent surface location on said other of said two d-c terminal leadframes; said die of said second, third and fourth pluralities of die being located to each be generally laterally between respective pairs of die of said first plurality of die, whereby all of said die of all of said pluralities are spaced along a U-shaped path.

7. The structure of claim 6, wherein said converter is an inverter circuit for converting d-c power to a-c multiphase power.

8. The structure of claim 6, wherein all of said die of all of said pluralities of die are MOSgated switching devices.

9. The structure of claim 8, wherein said converter is an inverter circuit for converting d-c power to a-c multiphase power.

10. The structure of claim 8, which further includes a printed circuit board fixed atop said power stage and generally coplanar therewith for applying control signals to the gates of each of said die.

11. The power stage of claim 3, which further includes a thermally conductive heat sink positioned beneath and supporting and in thermal communication with said leadframes and die.

12. The device of claim 11, wherein said heat sink has a cooling fluid channel therein; said channel having a U-shape which is disposed beneath and in thermal communication with each of said die.

13. The structure of claim 12, wherein said die of said first plurality of die are MOSgated switching devices.

14. The power stage of claim 6, which further includes a thermally conductive heat sink positioned beneath and supporting and in thermal communication with said leadframes and die.

15. The device of claim 14, wherein said heat sink has a cooling fluid channel therein; said channel having a U-shape which is disposed beneath and in thermal communication with each of said die.

16. The device of claim 1, wherein each of said flat leadframes has an upwardly bent terminal portion at a general right angle to the plane of said leadframes.

17. The device of claim 3, wherein each of said flat leadframes has an upwardly bent terminal portion at a general right angle to the plane of said leadframes.

18. The device of claim 6, wherein each of said flat leadframes has an upwardly bent terminal portion at a general right angle to the plane of said leadframes.

19. The device of claim 10, wherein each of said flat leadframes has an upwardly bent terminal portion at a general right angle to the plane of said leadframes.

20. The device of claim 11, which further includes at least one bus capacitor connected across said d-c terminals; said heat sink having a cavity therein for receiving the body of said capacitor; said capacitor having first and second terminals connected to said first and second d-c terminal leadframes respectively.

21. The device of claim 15, which further includes at least one bus capacitor connected across said d-c terminals; said heat sink having a cavity therein for receiving the body of said capacitor; said capacitor having first and second terminals connected to said first and second d-c terminal leadframes respectively.

22. A multiphase invertor assembly; said multiphase invertor assembly comprising a power stage consisting of a plurality of coplanar leadframes insulated from one another; a plurality of semiconductor switching devices connected to selected ones of said leadframes; a heat sink for receiving said power stage and in thermal communication with said plurality of semiconductor switching devices, an insulation frame enclosing the sides of said plurality of insulated leadframes, and a top cap fastened to said leadframe and in contact with said insulation frame and hermetically enclosing said leadframes and die in said enclosed volume; said plurality of leadframes each having a terminal extending through said cap.

23. The assembly of claim 22, wherein said semiconductor switching devices are spaced from one another along a generally U-shaped path; said heat sink having a water cooling channel therein which is generally U-shaped and which is follows said U-shaped path of said switching devices.

24. The assembly of claim 22, wherein said heat sink has at least one cavity therein; and a d-c bus capacitor mounted within said one cavity and connected to a selected path of said leadframes.