Power semiconductor package with bottom surface protrusions

• US 20110024185A1
• Filed: 07/31/2009
• Published: 02/03/2011
• Est. Priority Date: 07/31/2009
• Status: Active Grant

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Balakrishnan, Balu, Hawthorne, Brad L., Bäurle, Stefan
• Granted Patent: US 8,207,455 B2
• Time in Patent Office: Days
• US Class Current: 174/551
• CPC Class Codes: H01L 23/3107 the device being completely enclosed
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A package includes a body that encapsulates a semiconductor die, the body having a first pair of opposing lateral sides, a second pair of opposing lateral sides, a top, and a bottom. The bottom has a primary surface and a plurality of protrusions that extend outward from the primary surface. When the package is mounted to a printed circuit board (PCB) the protrusions contact the PCB and the primary surface is disposed a first distance away from the PCB. The package further includes a plurality of leads that extend outward from the first pair of opposing lateral sides.

Claims

1. A package for housing a power semiconductor die comprising:

a body that encapsulates the power semiconductor die in a form that includes a first pair of opposing lateral sides, a second pair of opposing lateral sides, a top, and a bottom, the bottom having a primary surface and a plurality of protrusions that extend outward from the primary surface such that when the package is mounted to a printed circuit board (PCB), the protrusions contact the PCB and the primary surface is disposed a first distance away from the PCB; and

a plurality of leads that extend outward from the first pair of opposing lateral sides.

2. The package of claim 1 wherein each of the leads is separated from an adjacent one of the leads by a second distance.

3. The semiconductor package of claim 1 wherein force applied to the top of the package is substantially transferred to the protrusions when the package is mounted to the PCB.

4. The package of claim 1 wherein each of the protrusions is spaced away from an adjacent edge of the primary surface by a third distance.

5. The package of claim 1 wherein the body comprises a molding compound material, the protrusions being integral with the molding compound material.

6. The package of claim 1 wherein each of the protrusions has a height that is substantially equal to the first distance.

7. The package of claim 1 wherein each of the protrusions has a contact area that abuts against the PCB where the package is mounted to the PCB.

8. The package of claim 7 wherein a sum total of the contact area of all of the protrusions is less than or equal to 0.7% of the primary surface.

9. The package of claim 1 wherein the plurality of protrusions comprises three protrusions arranged in a triangular pattern on the primary surface.

10. The package of claim 1 wherein the body is rectilinear and the plurality of protrusions comprises four protrusions, each protrusion being disposed coincident with or adjacent a corresponding corner of the primary surface.

11. A package for housing a power semiconductor device comprising:

a body that encapsulates the power semiconductor device, the body having a first pair of opposing lateral sides, front and back sides, a top that provides a mounting surface for a heat sink, and a bottom surface,

one or more non-conductive protrusions that extends outward from the bottom surface such that when the package is mounted to a printed circuit board (PCB) the one or more non-conductive protrusions contact the PCB; and

a plurality of leads that extend outward from at least the first pair of opposing lateral sides, each of the leads having a substantially constant width over a length that extends from the body to a point through an insertion hole of the PCB when the package is mounted to the PCB.

12. The package of claim 11 wherein the one or more non-conductive protrusions comprise a single elongated protrusion disposed substantially coincident with an edge of the bottom surface.

13. The package of claim 11 wherein the one or more non-conductive protrusions comprise three protrusions arranged in a triangular pattern on the bottom surface.

14. The package of claim 11 wherein the three protrusions each have a substantially flat base.

15. The package of claim 11 wherein the body is rectilinear and the one or more non-conductive protrusions comprise four protrusions.

16. The package of claim 15 wherein the each of the four protrusions is disposed substantially adjacent with a corresponding corner of the bottom surface.

17. The package of claim 15 wherein the each of the four protrusions is disposed at or near the middle of an edge of bottom surface that adjoins a corresponding one of the opposing lateral sides and front and back sides, respectively.

18. The package of claim 11 wherein each of the leads is separated from an adjacent one of the leads by a second distance that is substantially constant over the length.

19. The package of claim 11 wherein the body comprises a material, the one or more non-conductive protrusions being integral with the material.

20. The package of claim 11 wherein a force applied to a heat sink during mounting to the top is substantially transferred to the protrusions when the package is mounted to the PCB.

24. The package of claim 11 wherein the protrusions comprise three protrusions arranged in a triangular pattern.

25. The package of claim 11 wherein the protrusions comprise four protrusions.

26. The package of claim 25 wherein the each of the four protrusions is disposed at or near the middle of an edge of the substantially planar surface that adjoins a corresponding one of the opposing lateral sides and front and back sides, respectively.

27. The package of claim 25 wherein each of the four protrusions is disposed substantially adjacent with a corresponding corner of the substantially planar surface.

21. A package for housing a power semiconductor device comprising:

a body formed of a molding compound that encapsulates the power semiconductor device, the body having a substantially rectilinear shape that includes first pair of opposing lateral sides, front and back sides, a top that provides a mounting surface for a heat sink, and a bottom, the bottom having a plurality protrusions that extends outward from a substantially planar surface, the protrusions each having a substantially equal height such that when the package is mounted to a printed circuit board (PCB) the protrusions contact a top surface of the PCB with a separation distance being provided between the substantially planar surface and the top surface; and

a plurality of leads that extend outward from at least the first pair of opposing lateral sides, each of the leads having a substantially constant width over a length that extends from the body to a tapered end, each of the leads being separated from an adjacent one of the leads by a clearance distance, the clearance distance being substantially constant along the length.

22. The package of claim 21 wherein the protrusions each have a substantially flat base.

23. The package of claim 21 wherein the protrusions each have a substantially semi-spherical shape.

28. The package of claim 21 wherein a force applied to a heat sink during mounting to the top is substantially transferred to the protrusions when the package is mounted to the PCB.

29. The package of claim 21 wherein the separation distance is approximately 250 microns.

30. The package of claim 21 wherein the clearance distance is approximately 1.27 mm.