Mini V SMD

• US 20090283781A1
• Filed: 05/16/2008
• Published: 11/19/2009
• Est. Priority Date: 05/16/2008
• Status: Active Grant

• Current Assignee: Cree Huizhou Solid State Lighting Company Limited (Smart Global Holdings Incorporated)
• Original Assignee: CREE Hong Kong Limited (Wolfspeed, Inc.)
• Inventors: Wang, Xuan, Chan, Alex
• Granted Patent: US 8,049,230 B2
• Time in Patent Office: Days
• US Class Current: 257/89
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/45099 Material
• 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 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 25/0753 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/12041 LED
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 33/486 adapted for surface mounting

Abstract

In one embodiment, a surface-mount device comprises a casing having opposed, first and second main surfaces, side surfaces, and end surfaces. A lead frame partially encased by the casing comprises (1) an electrically conductive LED chip carrier part having a surface carrying a linear array of LEDs adapted to be energized to produce in combination a substantially full range of colors, each LED having a first electrical terminal and a second electrical terminal, the first terminal of each of the LEDs being electrically and thermally coupled to the chip carrying surface of the chip carrier part; and (2) electrically conductive connection parts separate from the chip carrier part, each of the connection parts having a connection pad, the second terminal of each of the LEDs being electrically coupled to the connection pad of a corresponding one of the connection parts with a single wire bond. The linear array of LEDs extends in a first direction, and each of the chip carrier part and connection parts has a lead. The leads may be disposed in parallel relationship with each other and extend through the end surfaces of the casing in a second direction, the second direction being orthogonal to the first direction. An array of the surface-mount devices may be used in an LED display such as an indoor LED screen.

Claims

1. A lead frame for a surface-mount device, said lead frame comprising:

an electrically conductive LED chip carrier part having a surface carrying a linear array of LEDs adapted to be energized to produce in combination a substantially full range of colors, each LED having a first electrical terminal and a second electrical terminal, the first terminal of each of the LEDs being electrically and thermally coupled to said chip carrying surface of said chip carrier part;

electrically conductive connection parts separate from said chip carrier part, each of said connection parts having a connection pad;

the second terminal of each of said LEDs being electrically coupled to the connection pad of a corresponding one of said connection parts; and

a black casing at least partially encasing said lead frame.

2. The lead frame of claim 1, wherein the first and second electrical terminals of each of said LEDs comprise a cathode and an anode, respectively.

3. The lead frame of claim 1, wherein the linear array of LEDs extends in a first direction and each of said chip carrier part and connection parts has a lead, said leads being disposed in parallel relationship with each other and extending in a second direction, and wherein said second direction is orthogonal to said first direction.

4. The lead frame of claim 1, wherein the chip carrier part and the connection parts are made of sheet metal.

5. The lead frame of claim 1, wherein said chip carrier part has a lead electrically coupled to said chip carrying surface, said lead having a thickness, and said chip carrying surface of the chip carrier part comprises a surface of a thermally conductive body extending in a direction normal to said chip carrying surface, said thermally conductive body having a thickness greater than the thickness of said chip carrier part lead.

6. The lead frame of claim 1, wherein the LEDs comprise a red, a green, and a blue LED.

7. The lead frame of claim 1, wherein the second electrical terminal of each of said LEDs is electrically coupled to the connection pad of the associated connection part by means of a single wire bond.

8. The lead frame of claim 1, wherein each of said LEDs is coupled to a respective connection pad via solder.

9. The lead frame of claim 8, wherein said solder is not visible when viewing the lead frame from the top.

10. The lead frame of claim 1, wherein said casing comprises black ceramic.

11. A surface-mount device, comprising:

a dark casing comprising opposed, first and second main surfaces, opposed side surfaces, and opposed end surfaces, the casing defining a cavity extending into the interior of the casing from the first main surface; and

a lead frame at least partially encased by said casing, the lead frame comprising;

an electrically conductive LED chip carrier part having a surface carrying a linear array of LEDs adapted to be energized to produce in combination a substantially full range of colors, each LED having a first electrical terminal and a second electrical terminal, the first terminal of each of the LEDs being electrically and thermally coupled to said chip carrying surface of said chip carrier part;

electrically conductive connection parts separate from said chip carrier part, each of said connection parts having a connection pad; and

the second terminal of each of said LEDs being electrically coupled to the connection pad of a corresponding one of said connection parts.

12. The device of claim 11, wherein the first and second electrical terminals of each of said LEDs comprise a cathode and an anode, respectively.

13. The device of claim 11, wherein the linear array of LEDs extends in a first direction, and each of said chip carrier and connection parts has a lead, said leads being disposed in parallel relationship with each other and extending through the end surfaces of the casing in a second direction, and wherein said second direction is orthogonal to said first direction.

14. The device of claim 11, wherein the chip carrier part and the connection parts are made of sheet metal.

15. The device of claim 11, wherein the chip carrying surface of the chip carrier part comprises a surface of a thermally conductive body extending in a direction normal to said chip carrying surface to a bottom surface of the body exposed through an aperture formed in the second main surface of the casing.

16. The device of claim 11, wherein the LEDs comprise a red, a green, and a blue LED.

17. The device of claim 11, wherein the second electrical terminal of each of said LEDs is electrically coupled to the connection pad of the associated connection part by means of a single wire bond.

18. The device of claim 11, wherein each of said LEDs is coupled to a respective connection pad via solder.

19. The device of claim 18, wherein said solder is not visible when viewing the lead frame from the top.

20. The device of claim 11, wherein said casing is comprised of black ceramic.

21. An LED display comprising:

a substrate carrying an array of surface-mount devices arranged in vertical columns and horizontal rows, each of said SMDs comprising a dark casing and containing a vertically oriented, linear arrangement of LEDs adapted to be energized to produce in combination a substantially full range of colors and to define one pixel of the display; and

signal processing and LED drive circuitry electrically connected to selectively energize said array of SMDs for producing visual images on said display.

22. The display of claim 21, wherein said casing of each SMD is comprised of black ceramic.

23. The display of claim 21, wherein each of said SMDs is coupled with the substrate via solder pads at the bottom surface of each SMD.

24. The display of claim 23, wherein said solder pads are not visible when viewing said LED display.

25. The display of claim 21, wherein said casing of each SMD comprises rounded edges such that through-holes are created when the SMDs are arranged on said substrate, said through-holes aiding in thermal management.