Semiconductor light emitting device with reflectors having cooling function

• US 20040211970A1
• Filed: 05/27/2003
• Published: 10/28/2004
• Est. Priority Date: 04/24/2003
• Status: Active Grant

• Current Assignee: High Power Lighting Corp.
• Original Assignee: Kyo-A Optics Co., Ltd.
• Inventors: Seo, Young-Joo, Hayashimoto, Yoshiaki
• Granted Patent: US 6,909,123 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/92247 the second connecting process involving a wire connector
• 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 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

A semiconductor light emitting device includes a base substrate, lead electrodes provided on the base substrate, at least one semiconductor light emitting element loaded on the base substrate so as to be spaced apart from the lead electrodes and radiating blue light, a connection member for electrically interconnecting the electrodes and the semiconductor light emitting element, a reflector extended from a bottom of the base substrate to a predetermined height for surrounding the semiconductor light emitting element, and a translucent cover layer formed in the receiving space for housing the light emitting element, the translucent cover layer containing a color-shifting substance for absorbing at least a part of blue light radiated from the light emitting element to radiate a light having a different wavelength. The reflector is made of a material having high translucency and high thermal conductivity on a surface thereof so as to reflect the light radiated from the light emitting element and form a uniform planar light, and the reflector radiates the heat radiated from the light emitting element to outside so as to cool an inside of a receiving space for receiving the light emitting element. Thus, the device emits white light outside by combination of the blue light radiated from the light emitting element and the light having a different wavelength.

Claims

1. A semiconductor light emitting device comprising:

a base substrate;

lead electrodes provided on the base substrate;

at least one semiconductor light emitting element loaded on the base substrate so as to be spaced apart from the lead electrodes and radiating blue light;

a connection member for electrically interconnecting the electrodes and the semiconductor light emitting element;

a reflector extended from a bottom of the base substrate to a predetermined height for surrounding the semiconductor light emitting element,

the reflector being made of a material having high translucency and high thermal conductivity on a surface thereof so as to reflect the light radiated from the light emitting element and form a uniform planar light, the reflector also radiating the heat radiated from the light emitting element to outside so as to cool an inside of a receiving space for receiving the light emitting element; and

a translucent cover layer formed in the receiving space for housing the light emitting element, the translucent cover layer containing a color-shifting substance for absorbing at least a part of blue light radiated from the light emitting element to radiate a light having a different wavelength,

whereby the device emits white light outside by combination of the blue light radiated from the light emitting element and the light having a different wavelength.

2. A semiconductor light emitting device according to claim 1, wherein the reflector is a metal plate having an insulation film formed at least a part of a surface thereof.

3. A semiconductor light emitting device according to claim 2, wherein the reflector is made of aluminum (Al), and the insulation film is made of aluminum oxide (Al₂O₃).

4. A semiconductor light emitting device according to claim 3,

wherein an inner surface of the reflector adjacent to the receiving space is tilted from the bottom of the base substrate at a predetermined angle,

whereby a caliber of the receiving space is gradually increased from a bottom contacted with the base substrate to an opposite side.

5. A semiconductor light emitting device according to claim 3,

wherein an inner surface of the reflector is rounded concave so that an end side of the receiving space substantially forms a symmetric parabola surface or a symmetric oval surface.

6. A semiconductor light emitting device according to claim 5, wherein the semiconductor light emitting element is a blue light emitting diode using a nitride semiconductor.

7. A semiconductor light emitting device according to claim 6,

wherein the translucent cover layer is made of a transparent resin containing a fluorescent material which absorbs a part of the blue light emitted from the light emitting element and then emits yellow light,

wherein the receiving space is filled with the transparent resin.

8. A semiconductor light emitting device according to claim 6, wherein the translucent cover layer includes:

a first translucent cover layer disposed near the light emitting element and containing a color-shifting substance for emitting yellow light by absorbing a part of the blue light emitted from the light emitting element; and

a second translucent cover layer formed on the first translucent cover layer to fill the receiving space, the second translucent cover layer being made of a transparent resin for transmitting the light passing through the first translucent cover layer to outside.

9. A semiconductor light emitting device according to claim 8, wherein the first translucent cover layer is made of a silicate resin containing a color-shifting substance.

10. A semiconductor light emitting device according to claim 8, wherein the second translucent cover layer has a fluorescent substance for absorbing a part of the blue light emitted from the light emitting element and then emitting yellow light.

11. A semiconductor light emitting device comprising:

a base substrate;

lead electrodes provided on the base substrate;

a light emitting element assembly including at least one semiconductor light emitting element loaded on the base substrate so as to be spaced apart from the lead electrodes and radiating blue light;

a connection member for electrically interconnecting the electrodes and the semiconductor light emitting element; and

a reflector extended from a bottom of the base substrate to a predetermined height in order to form a receiving space by surrounding the light emitting element assembly,

wherein the reflector is made of a material having high translucency and high thermal conductivity on a surface thereof so as to reflect the light radiated from the light emitting element and form a uniform planar light, and

wherein the reflector also radiates the heat radiated from the light emitting element to outside so as to cool an inside of the receiving space.

12. A semiconductor light emitting device according to claim 11,

wherein the light emitting element assembly includes at lease one LED chip for emitting blue light (B), at least one LED chip for emitting red light (R), and at least one LED chip for emitting green light (G),

whereby the device emits white light outside by R-G-B combination of the mixed lights emitted from the LED chips.

13. A semiconductor light emitting device according to claim 12, wherein the reflector is a metal plate having an insulation film formed at least a part of a surface thereof.

14. A semiconductor light emitting device according to claim 13, wherein the reflector is made of aluminum (Al), and the insulation film is made of aluminum oxide (Al₂O₃).

15. A semiconductor light emitting device according to claim 14,

wherein an inner surface of the reflector adjacent to the receiving space is tilted from the bottom of the base substrate at a predetermined angle,

whereby a caliber of the receiving space is gradually increased from a bottom contacted with the base substrate to an opposite side.

16. A semiconductor light emitting device according to claim 14,

wherein an inner surface of the reflector is rounded concave so that an end side of the receiving space substantially forms a symmetric parabola surface or a symmetric oval surface.

17. A semiconductor light emitting device according to claim 12, further comprising a transparent resin layer filled in the receiving space for housing the light emitting element assembly.