Led lead frame assembly

• US 6,407,411 B1
• Filed: 04/13/2000
• Issued: 06/18/2002
• Est. Priority Date: 04/13/2000
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Uriarte, Richard J., Horkay, Ferenc, Minnear, William P., Benicewicz, Pamela K., Wojnarowski, Robert J.
• Primary Examiner(s): Flynn, Nathan
• Assistant Examiner(s): Mondt, Johannes
• Application Number:
  US09/548,440
• Time in Patent Office: 796 Days
• Field of Search: 257/98, 257/99, 257/100, 257/675, 257/676, 257/778
• US Class Current: 257/99
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 23/36 Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks H01L23/28, H01L23/40, H01L23/42, H01L23/44, H01L23/46 take precedence; heating H01L23/345
• CPC Class Codes: H01L 23/49558 Insulating layers on lead frames, e.g. bridging members
• CPC Class Codes: H01L 23/60 Protection against electrostatic charges or discharges, e.g. Faraday shields
• 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 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01039 Yttrium [Y]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/19041 being a capacitor
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H01L 33/641 characterized by the materials
• CPC Class Codes: H01L 33/647 the elements conducting electric current to or from the semiconductor body

Abstract

An improved LED lead frame packaging assembly includes a thermally conducting, electrically insulating material that enhances the thermal conduction and structural integrity of the assembly, a UV-resistant encapsulantmaterial, and an integral ESD material that reduces electrostatic discharge. The thermally conducting, electrically insulating material creates an electrically insulating, thermally conductive path in the lead frame assembly for dissipation of power and also acts as a mounting structure thus allowing for the use of a soft encapsulant material, preferably a silicone.

Claims

1. A light-emitting semiconductor device packaging assembly comprising:

a light-emitting semiconductor;

input terminals connected to the light-emitting semiconductor for energizing the light-emitting semiconductor to emit light, said terminals having an electrically and thermally insulating gap therebetween wherein one of the input terminals provides primary heat sinking for the light-emitting semiconductor; and

thermally conductive material forming a thermally conducting path in the assembly for transfer of thermal energy from the heat sinking terminal to another terminal when the light-emitting semiconductor is energized.

2. The packaging assembly of claim 1 wherein the thermally conductive material is arranged in the electrically and thermally insulating gap and forms the thermally conducting path across the electrically and thermally insulating gap.

3. The packaging assembly of claim 1 wherein the thermally conductive material is in the form of a mechanical support ring disposed around a portion of the input terminals.

4. The packaging assembly of claim 1 wherein the thermally conductive material is an epoxide.

5. The packaging assembly of claim 1 wherein the thermally conductive material is added in an amount that will not alter the fixed dimensions of the packaging.

6. The packaging assembly of claim 1 further comprising electrostatic discharge material arranged in the insulating gap or bridging the gap, the electrostatic discharge material providing voltage discharge protection for the light-emitting semiconductor.

7. The packaging assembly of claim 6 wherein the electrostatic discharge material is an MOV material.

8. The packaging assembly of claim 1 wherein the thermally conductive material is also capable of reducing electrostatic discharge.

9. The packaging assembly of claim 8 wherein the thermally conductive material is an MOV material.

10. The packaging assembly of claim 1 further comprising an encapsulant material disposed around the packaging assembly.

11. The packaging assembly of claim 10 wherein the encapsulant material is UV-resistant.

12. The packaging assembly of claim 10 wherein the encapsulant material is silicone.

13. A light-emitting semiconductor device packaging assembly comprising:

a light-emitting diode;

a lead frame comprising first and second leads connected to the light-emitting diode for energizing the light-emitting diode to emit light and for heat sinking the light-emitting diode; and

thermally conductive material forming a thermally conductive path connecting the first and second leads for increasing the thermal conductance of the lead frame when the light emitting diode is energized.

14. The packaging assembly of claim 13 wherein the first and second leads are electrically isolated from each other so as to create a thermal gap between them.

15. The packaging assembly of claim 14 wherein the thermally conductive material is positioned in the thermal gap or encases the thermal gap.

16. The packaging assembly of claim 13 wherein the thermally conductive material is in the form of a mechanical support ring disposed around a portion of the input terminals.

17. The packaging assembly of claim 13 wherein the thermally conductive material is an epoxide.

18. The packaging assembly of claim 13 wherein the thermally conductive material is added in an amount that will not alter the fixed dimensions of the packaging.

19. The packaging assembly of claim 14 further comprising electrostatic discharge material positioned in the thermal gap.

20. The packaging assembly of claim 18 wherein the electrostatic discharge material is an MOV material.

21. The packaging assembly of claim 18 wherein the thermally conductive material is also capable of reducing electrostatic discharge.

22. The packaging assembly of claim 21 wherein the thermally conductive material is an MOV material.

24. The packaging assembly of claim 22 wherein the encapsulant material is UV-resistant.

26. The packaging assembly of claim 13 further comprising fluorescent or phosphorescent material disposed over the light-emitting diode.

27. The packaging assembly of claim 26 wherein the light-emitting diode produces light at predetermined wavelengths which is partially converted by the fluorescent or phosphorescent material into another wavelength to provide a white light.

28. The packaging assembly of claim 13 wherein the light-emitting diode is in a flip chip arrangement.

31. The packaging assembly as set forth in claim 13, wherein the first and second leads include:

a die attach lead having a receiving portion that receives the associated LED die and that has an electrical connection to the associated LED die via a first wire bond, the die attach lead defining a heat sink for heat sinking the associated LED die; and

an isolated lead that has an electrical connection to the associated LED die via a second wire bond, the isolated lead arranged with respect to the die attach lead such that an electrically and thermally isolating gap exists therebetween that is bridged by the thermally

23. The packaging assembly of claim 23 further comprising an encapsulant material disposed around the packaging assembly.

25. The packaging assembly of claim 23 wherein the encapsulant material is silicone.

29. A semiconductor device package for use with a semiconductor device formed in a flip chip arrangement, the package assembly comprising:

a light-emitting semiconductor formed in a flip chip arrangement, the light-emitting semiconductor having a contact surface and one or more micro ball grid array structures attached thereto;

a lead frame connected to the one or more micro ball grid array structures, the lead frame including a plurality of electrically isolated metal layers for heat sinking the light-emitting semiconductor; and

a thermally conductive material forming a thermally conductive path between frame metal layers in the assembly for conducting heat between said frame metal layers when the light-emitting semiconductor is energized.

30. The packaging assembly of claim 29 wherein the thermally conductive material is selected from the group consisting of polymer film insulator material, polymer glue insulator material, and thermally enhanced bonding material.