RF power transistor package

• US 20070096297A1
• Filed: 09/21/2005
• Published: 05/03/2007
• Est. Priority Date: 09/21/2005
• Status: Active Grant

• Current Assignee: Microsemi Corporation (Microchip Technology Incorporated)
• Original Assignee: Microsemi Corporation (Microchip Technology Incorporated)
• Inventors: Frey, Richard
• Granted Patent: US 7,569,927 B2
• Time in Patent Office: Days
• US Class Current: 257/706
• CPC Class Codes: H01L 23/04 characterised by the shape of the container or parts, e.g. caps, walls
• CPC Class Codes: H01L 23/057 the leads being parallel to the base
• CPC Class Codes: H01L 23/13 characterised by the shape
• CPC Class Codes: H01L 23/66 High-frequency adaptations
• CPC Class Codes: H01L 25/072 the devices being arranged next to each other
• 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
• CPC Class Codes: H01L 2924/13055 Insulated gate bipolar transistor [IGBT]
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/16152 Cap comprising a cavity for hosting the device, e.g. U-shaped cap

Abstract

An RF power transistor package with a rectangular ceramic base can house one or more dies affixed to an upper surface of the ceramic base. Source leads attached to the ceramic base extend from at least opposite sides of the rectangular base beneath a periphery of a non-conductive cover overlying the ceramic base. The cover includes recesses arranged to receive the one or more die, the ceramic base, gate and drain leads and a portion of the source leads. The cover further includes bolt holes arranged to clamp the ceramic base and source leads to a heat sink. Bosses at corners of the cover outward of the bolt holes exert a downward bowing force along the periphery of the cover between the bolt holes.

Claims

1. A power transistor package comprising:

a rectangular ceramic base;

one or more die affixed to an upper surface of the ceramic base;

one or more source leads extending from at least one of a pair of opposite sides of the ceramic base;

one or more gate and drain leads extending from at least one of a pair of opposite sides of the ceramic base; and

a non-conductive cover overlying the ceramic base and including a recess configured to receive the one or more die, receive the ceramic base and gate and drain leads and receive a portion of the source leads and including bolt holes arranged to secure the ceramic base and source leads to a heat sink.

2. The package of claim 1, wherein the recess includes a portion shaped to receive the ceramic base that has a depth less than the height of the ceramic base.

3. The package of claim 1, wherein the recess includes a portion shaped to receive a portion of the source leads that has a depth less than the thickness of the source leads.

4. The package of claim 3, wherein the portion shaped to receive a portion of the source leads is positioned between the bolt holes.

5. The package of claim 1, further comprising a boss protruding from a bottom surface of the cover corresponding to each bolt hole and arranged toward an outer edge of the cover.

6. The package of claim 1, wherein the cover comprises a material having resistance to creep, high electrical insulation, high yield strength and low dielectric loss.

7. The package of claim 6, wherein the cover comprises a partially glass-filed polyetherimide.

8. The package of claim 6, wherein the cover comprises a partially glass-reinforced liquid crystal polymer.

9. A packaging system for an RF power transistor, comprising:

a heat sink;

a rectangular ceramic base including one or more die affixed to a prepared upper surface of the ceramic base, the ceramic base overlying the heat sink;

source leads connected to and extending from opposite sides of the ceramic base;

gate and drain leads connected to and extending from opposite sides of the ceramic base; and

a non-conductive cover clamping the gate, drain and source leads to the ceramic base and clamping the ceramic base and portions of the source leads extending from the ceramic base onto the heat sink.

10. The packaging system of claim 9, wherein the cover includes a first recess shaped to fit over the ceramic base and source leads.

11. The packaging system of claim 10, wherein the cover includes a second recess arranged within the first recess to offset a portion of the cover from the one or more die.

12. The packaging system of claim 9, wherein the cover includes fastener holes arranged in standardized locations to affix the cover to the heat sink.

13. The packaging system of claim 12, wherein the cover includes protrusions adjacent to the fastener holes and adjacent to an outer edge of the cover.

14. The packaging system of claim 9, wherein the cover is rectangular and includes fastener holes near each corner of the cover and protrusions at each corner.

15. The packaging system of claim 14, wherein the protrusions include a tipping edge aligned perpendicular to a diagonal extending from opposite corners of the rectangular ceramic base.

16. A package for a RF power transistor comprising:

a ceramic base arranged to receive one or more die affixed to a top surface of the base;

a source lead connected to the die and extending outward from a side of the base;

a gate lead connected to the die and extending outward from aside of the base;

a drain lead connected to the die and extending outward from a side of the base; and

a cover having a central die cavity, a peripheral recess and means for clamping the source, gate and drain leads to the base and clamping the base and source leads to an underlying heat sink.

17. The package of claim 16, wherein the means for clamping includes a means for enhancing a clamping force over a central portion of the ceramic base when clamping the base to the underlying heat sink.

18. The package of claim 17, wherein the means for enhancing a clamping force over a central portion of the ceramic base includes protrusions positioned near an outer edge of a bottom side of the cover to cause the clamping means to bow toward the central portion of the ceramic base.

19. The package of claim 16, wherein the cover comprises a material having resistance to creep, high electrical insulation, high yield strength and low dielectric loss.

20. A power transistor package comprising:

a ceramic base;

one ore more die affixed to an upper surface of the base;

one or more leads extending from the base; and

a non-conductive cover arranged to clamp the base and a portion of one or more leads to a heat sink to provide tight thermal and electrical contact between the base, the portion of the one or more leads and a heat sink.