Light Emitting Device Comprising Chip-on-board Package substrate and method for manufacturing

• US 20150097201A1
• Filed: 05/17/2013
• Published: 04/09/2015
• Est. Priority Date: 05/21/2012
• Status: Active Grant

• Current Assignee: De L Associates Inc.
• Original Assignee: De L Associates Inc.
• Inventors: Imai, Yuji
• Granted Patent: US 9,293,662 B2
• Time in Patent Office: Days
• US Class Current: 257/89
• CPC Class Codes: F21K 9/232 specially adapted for generating an essentially omnidirectional light distribution, e.g. with a glass bulb
• CPC Class Codes: F21V 3/00 Globes; Bowls; Cover glasses with refracting properties F21V5/00; with reflecting properties F21V7/00; characterised by cooling arrangements F21V29/506
• CPC Class Codes: F21Y 2105/10 comprising a two-dimensional array of point-like light-generating elements
• CPC Class Codes: F21Y 2105/12 characterised by the geometrical disposition of the light-generating elements, e.g. arranging light-generating elements in differing patterns or densities
• CPC Class Codes: F21Y 2113/13 comprising an assembly of point-like light sources
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 2224/14 of a plurality of bump connectors
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• 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 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 27/15 including semiconductor components having potential barriers, specially adapted for light emission
• 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 2924/181 Encapsulation
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

[Problem] To provide a chip-on-board light emitting device and a method for manufacturing the same such that even though the light emitting device is a chip-on-board light emitting device, it is possible to improve color rendering thereof without excessively reducing the amount of light emission and without installing special circuit patterns or performing current control. [Solution] A chip-on-board light emitting device in which a plurality of LED elements are mounted directly on a package substrate includes a circuit pattern formed on the package substrate, the circuit pattern including a plurality of mounting sections on which the plurality of LED elements are mounted and an anode electrode and cathode electrode pair. The LED elements mounted on the circuit pattern include a plurality of types of LED elements having different emission wavelengths and temperature characteristics, so that by utilizing the temperature characteristics of the plurality of types of LED elements, the device as a whole has a greater average color rendering index (Ra) at an operating temperature than at a ordinary temperature.

Claims

1. A light emitting device having a chip-on-board type package substrate on which a plurality of LED elements are directly mounted, comprising:

a circuit pattern having a plurality of mounting parts, which are formed on the package substrate and on which the plurality of LED elements are mounted, and a pair of an anode electrode and a cathode electrode, wherein

each LED element mounted on the circuit pattern includes plural kinds of LED elements which are different from one another in light emission wavelength and in temperature characteristics, and wherein

by using the temperature characteristics of the plural kinds of LED elements, an average color rendering index (Ra) as a whole device is configured to become larger at an operating temperature than at an ordinary temperature.

2. The light emitting device having the chip-on-board type package substrate according to claim 1, wherein the plural kinds of LED elements include a blue LED element, a green LED element and a red LED element.

3. The light emitting device having the chip-on-board type package substrate according to claim 2, wherein

the power attenuation factor of the blue LED element is 8 to 20% from an ordinary temperature to an operating temperature, wherein

the power attenuation factor of the green LED element is 10 to 40% from the ordinary temperature to the operating temperature, and wherein

the power attenuation factor of the red LED element is 10 to 60% from the ordinary temperature to the operating temperature.

4. The light emitting device having the chip-on-board type package substrate according to claim 3, further including yellow phosphors which emit yellow light if exited by the blue LED element.

5. The light emitting device having the chip-on-board type package substrate according to claim 1, wherein

the plural kinds of LED elements includes:

a blue LED element and a red LED element;

green phosphors which emit green light if exited by the blue LED element or the red LED element; and

yellow phosphors which emit yellow light if exited by the blue LED element or the red LED element.

6. A method for manufacturing the light emitting device having the chip-on-board type package substrate according to claim 1, including:

a mounting step where a plurality of flip-chip type LED elements, each of which has a growth substrate, a semiconductor light emitting part on the growth substrate and electrodes on the semiconductor light emitting part, are mounted on a package substrate; and

a removing step where the growth substrate is removed with each of the LED elements being mounted on the growth substrate.