LIGHT EMITTING DIODE (LED) PACKAGE HAVING WAVELENGTH CONVERSION MEMBER AND WAFER LEVEL FABRICATION METHOD
A light emitting diode (LED) package includes a substrate and a light emitting diode (LED) die on the substrate configured to emit electromagnetic radiation in a first spectral region. The (LED) package also includes a dielectric layer on the (LED) die and a wavelength conversion member on the dielectric layer configured to convert the electromagnetic radiation in the first spectral region to electromagnetic radiation in a second spectral region. The (LED) package also includes an interconnect comprising a conductive trace on the wavelength conversion member and on the dielectric layer in electrical contact with a die contact on the (LED) die and with a conductor on the substrate, and a transparent dome configured as a lens encapsulating the (LED) die.
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This disclosure relates generally to light emitting diodes (LED) devices and more particularly to methods for fabricating light emitting diode (LED) packages.
Light emitting diode (LED) devices have been developed that produce white light. In order to produce white light, a blue (LED) die can be used in combination with a wavelength conversion layer, such as a phosphor layer formed on the surface of the die. The electromagnetic radiation emitted by the blue (LED) die excites the atoms of the wavelength conversion layer, which converts some of the electromagnetic radiation in the blue wavelength spectral region to the yellow wavelength spectral region. The ratio of the blue to the yellow can be manipulated by the composition and geometry of the wavelength conversion layer, such that the output of the light emitting diode (LED) device appears to be white light.
In this type of light emitting diode (LED) device, the characteristics of the white light produced by the device are determined by the electromagnetic radiation emitted by the blue LED die and by the wavelength conversion properties of the wavelength conversion layer. For example, the color composite of the white light depends upon the spectral distributions of electromagnetic radiation produced by the blue LED die and the wavelength conversion layer. Any variations in these spectral distributions can vary the color composite of the white light produced by the light emitting diode (LED) device. Because of the variations in the configurations of the blue LED die and the wavelength conversion layer, the white light can have an undesirable color balance and lack the characteristics of a true color rendition.
It is difficult to fabricate white light emitting diode (LED) devices with consistent color balance because any variations in the fabrication process can change the outputs of the light emitting diode (LED) dice and the wavelength conversion layers. The present disclosure is directed to a wafer level method for fabricating light emitting diode (LED) devices with consistent characteristics. For example, using the method a light emitting diode (LED) device can be fabricated that produces electromagnetic radiation in the form of white light having a desired color balance, a desired color temperature or a desired spectral distribution. The present disclosure is also directed to a light emitting diode (LED) device having a wavelength conversion member in the form of a sheet having conductive vias therethrough.
SUMMARYA light emitting diode (LED) package includes a substrate and a light emitting diode (LED) die on the substrate configured to emit electromagnetic radiation in a first spectral region. The (LED) package also includes a dielectric layer on the (LED) die and a wavelength conversion member on the dielectric layer configured to convert the electromagnetic radiation in the first spectral region to electromagnetic radiation in a second spectral region. The (LED) package also includes an interconnect comprising a conductive trace on the wavelength conversion member and on the dielectric layer in electrical contact with a die contact on the (LED) die and with a conductor on the substrate, and a transparent dome configured as a lens encapsulating the (LED) die.
A method for fabricating the light emitting diode (LED) package includes the steps of providing a substrate, attaching a light emitting diode (LED) die to the substrate configured to emit electromagnetic radiation in a first spectral region, and forming a dielectric layer on the (LED) die and the substrate. The method also includes the steps of forming a wavelength conversion member configured to convert the electromagnetic radiation in the first spectral region to electromagnetic radiation in a second spectral region, attaching the wavelength conversion member to the dielectric layer, forming an interconnect comprising a conductive trace on the wavelength conversion member and on the dielectric layer having a first conductive via in the wavelength conversion member in electrical contact with a die contact on the (LED) die and a second conductive via in the dielectric layer in electrical contact with a conductor on the substrate, and forming a transparent dome configured as a lens encapsulating the (LED) die. The method can be performed on a semiconductor wafer containing multiple light emitting diode (LED) dice having multiple metallization patterns, which decreases fabrication time and costs
Exemplary embodiments are illustrated in the referenced figures of the drawings. It is intended that the embodiments and the figures disclosed herein are to be considered illustrative rather than limiting.
Referring to
The substrate 12 (
The substrate 12 can also include additional circuit elements as required, such as a backside heat sink 36 (
In addition, the substrate 12 (
The light emitting diode (LED) die 14 (
In addition, the (LED) die 14 (
As shown in
The wavelength conversion member 16 (
In addition, the wavelength conversion member 16 can comprise a single layer or multiple layers of material. U.S. Pat. No. 7,781,783 B2 to Yen et al., which is incorporated herein by reference, discloses different combinations for multiple wavelength conversion layers. For example,
The transparent dome 20 (
Referring to
The wafer 44 can include a plurality of identical metallization patterns on each substrate 12. Each substrate 12 includes the die-mounting pad 22, the front side conductor 24 in electrical communication with the die-mounting pad 22, the conductive via 26 in electrical communication with the front side conductor 24, and the back side electrode 28 in electrical communication with the conductive via 26. Each substrate 12 also includes the front side conductor 30, the conductive via 32 in electrical communication with the front side conductor 30, and the backside electrode 34 in electrical communication with the conductive via 32. The metallization patterns can be formed using well-known processes such as an additive process (deposition through a mask) or a subtractive process (etching through a mask). In addition, the front side conductors 24, 30 and the backside electrodes 28, 34 can be electrically separated as required by spaces. The conductive vias 26, 32 through the substrates 12 can also be formed using well know processes, such as by forming electrically insulated openings through the substrates 12, and filling the openings with a conductive material, such as a metal or conductive polymer.
Next, as shown in
Next, as shown in
Next, as shown in
Rather than being in sheet form, the wavelength conversion members 16 can be formed on transparent bases, such as a plastic, glass or adhesive polymer plates or lens, using a suitable process such as spraying, dipping, spin coating, rolling, electro deposition or vapor deposition to a desired thickness. The wavelength conversion members 16 can also be deposited directly on the (LED) dice 14 using a suitable process such as precise dispensing, precise stamping, precise jetting, spraying, dispensing and screen printing followed by curing.
Next, as shown in
Next, as shown in
Next, as shown in
Following the dispensing step, a singulation step can be performed to singulate the wafer 44 into a plurality of light emitting diode (LED) packages 10. The singulation process is also referred to in the art as dicing. The singulation step can be performed using a process such as lasering, sawing, water jetting, etching or scribe and break, in which grooves (not shown) separate individual light emitting diode (LED) packages 10.
Thus the disclosure describes improved light emitting diode (LED) packages and method of fabrication. While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and subcombinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.
Claims
1. A light emitting diode (LED) package comprising:
- a substrate having a die-mounting pad, a first conductor in electrical communication with the die mounting pad and a second conductor;
- a light emitting diode (LED) die in electrical contact with the die-mounting pad having a foot print, a circuit side, a die contact on the circuit side and a plurality of edges, the (LED) die configured to emit electromagnetic radiation in a first spectral region;
- a dielectric layer on the circuit side and edges of the (LED) die and on the substrate;
- a wavelength conversion member on the dielectric layer configured to convert the electromagnetic radiation in the first spectral region to electromagnetic radiation in a second spectral region, the wavelength conversion member having a peripheral shape substantially matching the footprint of the (LED) die, a front surface and sidewalls;
- an interconnect comprising a conductive trace on the front surface of the wavelength conversion member and extending along a sidewall of the wavelength conversion member and on the dielectric layer on the edges of the (LED) die in electrical contact with the die contact and with the second conductor; and
- a transparent dome configured as a lens encapsulating the (LED) die.
2. The (LED) package of claim 1 wherein the wavelength conversion member comprises a polymer sheet containing a wavelength conversion compound.
3. The (LED) package of claim 1 further comprising a first conductive via through the wavelength conversion member in electrical contact with the interconnect and a second conductive via through the dielectric layer in electrical contact with the interconnect.
4. The (LED) package of claim 1 further comprising a first electrode on a back side of the substrate in electrical contact with the first conductor, and a second electrode on a back side of the substrate in electrical contact with the second conductor.
5. The (LED) package of claim 1 wherein the light emitting diode (LED) die is configured to emit electromagnetic radiation in the blue spectral region, the wavelength conversion member is configured to convert the electromagnetic radiation to the yellow spectral region and an output of the (LED) package comprises white light.
6. The (LED) package of claim 1 wherein the wavelength conversion member comprises multiple layers including a red fluorescent material in a first wavelength conversion layer and green a fluorescent material in a second wavelength conversion layer.
7. The (LED) package of claim 1 wherein the wavelength conversion member comprises multiple layers including a red fluorescent material in a first wavelength conversion layer and a yellow fluorescent material in a second wavelength conversion layer.
8. The (LED) package of claim 1 wherein the wavelength conversion member comprises multiple layers including a red fluorescent material in a first wavelength conversion layer and a yellow-green fluorescent material in a second wavelength conversion layer.
9. A light emitting diode (LED) package comprising:
- a substrate having a first side, a die-mounting pad on the first side, a first conductor on the first side in electrical communication with the die mounting pad and a second conductor on the first side;
- a light emitting diode (LED) die in electrical contact with the die-mounting pad having a foot print, a circuit side, a die contact on the circuit side and a plurality of edges, the (LED) die configured to emit electromagnetic radiation in a first spectral region;
- a dielectric layer on the circuit side and edges of the (LED) die and on the substrate;
- a wavelength conversion member on the dielectric layer comprising a sheet containing a wavelength conversion compound configured to convert the electromagnetic radiation in the first spectral region to electromagnetic radiation in a second spectral region, the wavelength conversion member having a peripheral shape substantially matching the footprint of the (LED) die, a front surface and sidewalls;
- an interconnect comprising a conductive trace on the front surface of the wavelength conversion member and extending along a sidewall of the wavelength conversion member and on the dielectric layer on the edges of the (LED) die in electrical contact with the die contact and with the second conductor;
- a first conductive via comprising a first opening through the wavelength conversion member filled with a conductive material in electrical contact with the interconnect and a second conductive via comprising a second opening through the dielectric layer filled with the conductive material in electrical contact with the interconnect; and
- a transparent dome configured as a lens encapsulating the (LED) die.
10. The (LED) package of claim 9 wherein the wavelength conversion member comprises a polymer sheet containing a phosphor compound.
11. The (LED) package of claim 9 further comprising a first conductive via in the substrate in electrical contact with the first conductor and a first electrode on a back side of the substrate in electrical contact with the first conductive via, and a second conductive via in the substrate in electrical contact with the second conductor and a second electrode on a back side of the substrate in electrical contact with the second conductive via.
12. The (LED) package of claim 9 wherein the light emitting diode (LED) die is configured to emit electromagnetic radiation in the blue spectral region, the wavelength conversion member is configured to convert the electromagnetic radiation to the yellow spectral region and an output of the (LED) package comprises white light.
13. The (LED) package of claim 9 wherein the conductive trace comprises the conductive material.
14. A method for fabricating a light emitting diode (LED) package comprising:
- providing a substrate having a die mounting pad, a first conductor in electrical communication with the die mounting pad and a second conductor;
- attaching a light emitting diode (LED) die to the substrate in electrical contact with the die mounting pad having a foot print, a circuit side, a die contact on the circuit side and a plurality of edges, the (LED) die configured to emit electromagnetic radiation in a first spectral region;
- forming a dielectric layer on the circuit side and edges of the (LED) die and on the substrate;
- forming a wavelength conversion member configured to convert the electromagnetic radiation in the first spectral region to electromagnetic radiation in a second spectral region, the wavelength conversion member having a peripheral shape substantially matching the footprint of the (LED) die, a front surface and sidewalls;
- attaching the wavelength conversion member to the dielectric layer;
- forming an interconnect comprising a conductive trace comprising a conductive material on the front surface of the wavelength conversion member and extending along sidewall of the wavelength conversion member and on the dielectric layer on the edges of the (LED) die having a first conductive via comprising a first opening in the wavelength conversion member filled with the conductive material in electrical contact with the die contact and a second conductive via comprising a second opening in the dielectric layer filled with the conductive material in electrical contact with the second conductor; and
- forming a transparent dome configured as a lens encapsulating the (LED) die.
15. The method of claim 14 wherein the forming the wavelength conversion layer step comprises mixing a wavelength conversion material with a base material to form a mixture, coating the mixture on a release film, curing the mixture and separating a wavelength conversion layer from the release film.
16. The method of claim 15 wherein the coating the mixture on the release film step comprise a process selected from the group consisting of dip coating, rod coating, blade coating, knife coating, air knife coating, Gravure coating, roll coating, and slot and extrusion coating.
17. The method of claim 14 wherein the wavelength conversion layer comprises a plastic, glass or adhesive polymer containing a phosphor compound.
18. The method of claim 14 wherein the (LED) die is configured to emit electromagnetic radiation in the blue spectral region, the wavelength conversion member is configured to convert the electromagnetic radiation to the yellow spectral region and an output of the LED package comprises white light.
19. The method of claim 14 wherein the wavelength conversion layer comprises multiple layers each configured to convert the electromagnetic radiation in the first spectral region to a different spectral region.
20. The method of claim 19 wherein the multiple layers include a red fluorescent material in a first wavelength conversion layer and green a fluorescent material in a second wavelength conversion layer.
21. The method of claim 19 wherein the multiple layers include a red fluorescent material in a first wavelength conversion layer and a yellow fluorescent material in a second wavelength conversion layer.
22. The method of claim 19 wherein the multiple layers include a red fluorescent material in a first wavelength conversion layer and a yellow-green fluorescent material in a second wavelength conversion layer.
Type: Application
Filed: Sep 12, 2011
Publication Date: Mar 14, 2013
Applicant: SEMILEDS OPTOELECTRONICS CO., LTD. (Miao-Li County)
Inventors: JUI- KANG YEN (Taipei City), TRUNG TRI DOAN (Baoshan Hsinchu)
Application Number: 13/229,836
International Classification: H01L 33/50 (20100101); H01L 33/62 (20100101);