CHIP ON BOARD LIGHT EMITTING DIODE DEVICE HAVING DISSIPATION UNIT ARRAY

• US 20140367716A1
• Filed: 06/13/2013
• Published: 12/18/2014
• Est. Priority Date: 06/13/2013
• Status: Active Grant

• Current Assignee: Cofan USA, Inc.
• Original Assignee: Cofan USA, Inc.
• Inventors: Chen, Pao
• Granted Patent: US 8,975,659 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/81 using a bump connector
• CPC Class Codes: H01L 24/14 of a plurality of bump connectors
• 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 2924/12041 LED
• CPC Class Codes: H01L 2933/0016 relating to electrodes
• CPC Class Codes: H01L 2933/0075 relating to heat extraction or cooling elements
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01L 33/382 the electrode extending partially in or entirely through the semiconductor body
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H01L 33/642 characterized by the shape
• CPC Class Codes: H01L 33/647 the elements conducting electric current to or from the semiconductor body
• CPC Class Codes: H05K 1/0204 using means for thermal conduction connection in the thickness direction of the substrate H05K1/0207 takes precedence
• CPC Class Codes: H05K 1/0306 Inorganic insulating substrates, e.g. ceramic, glass
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]

Abstract

A chip on board light emitting diode (LED) device comprises a LED device, a printed circuit board (PCB) and a dissipation unit array. The LED device comprises a LED substrate, a first contact pad and a second contact pad above the LED substrate and a thermal layer formed on top surface of the LED device. The thermal layer comprises a thermal conductive material. A printed circuit board (PCB) comprises a PCB substrate with a thermal projection extending from surface of the PCB substrate, and a first and a second electrode pads above the PCB substrate. The thermal projection and the PCB substrate comprise the thermal conductive material. The dissipation unit array comprises a plurality of dissipation units each disposed between the LED device and the PCB. The thermal layer is thermally coupled to the thermal projection via at least one dissipation unit. Each of the first and second contact pads is electrically coupled to the corresponding electrode pad via at least one dissipation unit.

Claims

1. A chip on board light emitting diode device comprising:

a light emitting diode device comprising;

a light emitting diode substrate;

a light emitting diode conductive layer forming a first contact pad and a second contact pad above the light emitting diode substrate; and

a thermal layer formed on top surface of the light emitting diode substrate, the thermal layer comprising a first thermal conductive material;

a printed circuit board comprising;

a printed circuit board substrate with a thermal projection projecting from surface of the printed circuit board substrate, the thermal projection and the printed circuit board substrate comprising a second thermal conductive material;

a printed circuit board conductive layer forming a first electrode pad and a second electrode pad above the printed circuit board substrate; and

a dissipation unit array comprising a plurality of dissipation units each disposed between the light emitting diode device and the printed circuit board; and

wherein the thermal layer is thermally coupled to the thermal projection via at least one of the plurality of dissipation units; and

wherein the first contact pad is electrically coupled to the first electrode pad via one of the plurality of dissipation units, and the second contact pad is electrically coupled to the second electrode pad.

2. The device of claim 1, wherein each of the dissipation units comprises a dissipation base, a dissipation body on the dissipation base and a dissipation cap covering the dissipation body.

3. The device of claim 2, wherein each of the dissipation units is thermally coupled to the light emitting diode device with the thermal layer in contact with the dissipation base, and wherein each of the dissipation unit is thermally coupled to the printed circuit board with the thermal projection in contact with the dissipation cap.

4. The device of claim 2, wherein each of the dissipation units is electrically coupled to the light emitting diode device with the contact pads in contact with the dissipation base, and wherein each of the dissipation unit is electrically coupled to the printed circuit board with the electrode pads in contact with the dissipation cap.

5. The device of claim 2, wherein the dissipation base comprises at least one of Ti, Al and Ni.

6. The device of claim 2, wherein the dissipation body comprises at least one of Cu and Al.

7. The device of claim 2, wherein the dissipation cap comprises at least one of Ni, Sn, Ag, Pb and Au.

8. The device of claim 1, wherein surface of the first contact pad and surface of the second contact pad are planer to surface of the thermal layer.

9. The device of claim 1, wherein surface of the first contact pad and surface of the second contact pad are higher or lower than surface of the thermal layer.

10. The device of claim 1, wherein surface of the first electrode pad and surface of the second electrode pad are planar to surface of the thermal projection.

11. The device of claim 1, wherein surface of the thermal projection is higher or lower than surface of the first electrode pad and surface of the second electrode pad.

12. The device of claim 1, wherein each dissipation unit has the same size.

13. The device of claim 1, wherein size of the dissipation units in thermal dissipation unit group is different than that of the dissipation units in electrical dissipation unit group.

14. The device of claim 1, wherein the light emitting diode device further comprises a first type semiconductor layer, an active layer formed on the first type semiconductor layer and a second type semiconductor layer formed on the active layer, the first and second type semiconductor layers including a first material, the active layer including a second material, the first material has wider band gap than that of the second material.

15. The device of claim 14, wherein the light emitting diode device further comprises a conductive layer formed on the second type semiconductor layer.

16. The device of claim 15, wherein the light emitting diode device further comprises a reflective layer covering at least a portion of the conductive layer.

17. The device of claim 16, wherein the light emitting diode device further comprises a passivation layer covering underlying layers.

18. The device of claim 1, wherein the printed circuit board further comprises a dielectric layer sandwiched between the printed circuit board substrate and the electrode pads.

19. The device of claim 1, wherein the printed circuit board substrate and the thermal projection comprise at least one of Al, Cu, Ag, Au, metal alloy and graphite.

20. (canceled)