Apparatus and system for miniature surface mount devices
View Patent ↗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.
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 parts and said connection parts has a lead, said leads being disposed in parallel relationship with each other and extending in a second direction 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 said casing comprises black ceramic.
9. The lead frame of claim 1 , wherein said chip carrier part comprises a corresponding thermally conductive body extending in a direction normal to said surface.
10. 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.
11. The device of claim 10 , wherein the first and second electrical terminals of each of said LEDs comprise a cathode and an anode, respectively.
12. The device of claim 10 , wherein the linear array of LEDs extends in a first direction and each of said chip carrier parts and said 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 orthogonal to said first direction.
13. The device of claim 10 , wherein the chip carrier part and the connection parts are made of sheet metal.
14. The device of claim 10 , 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.
15. The device of claim 10 , wherein the LEDs comprise a red, a green, and a blue LED.
16. The device of claim 10 , 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.
17. The device of claim 10 , wherein said casing is comprised of black ceramic.
18. The device of claim 10 , wherein said chip carrier part comprises a corresponding thermally conductive body extending in a direction normal to said surface.
19. 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.
20. The display of claim 19 , wherein said casing of each SMD is comprised of black ceramic.
21. The display of claim 19 , wherein each of said SMDs is coupled with the substrate via solder pads at the bottom surface of each SMD.
22. The display of claim 19 , 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.
23. The display of claim 19 , wherein each of said SMD comprises a corresponding electrically conductive LED chip carrier part having a surface carrying the linear arrangement of LEDs.
24. The display of claim 23 , wherein each corresponding carrier part comprises a corresponding thermally conductive body extending in a direction normal to said surface.