Electroluminescent device with high refractive index and UV-resistant encapsulant

• US 20070295968A1
• Filed: 06/27/2006
• Published: 12/27/2007
• Est. Priority Date: 06/27/2006
• Status: Abandoned Application

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Tan, Kheng Leng, Chua, Janet Bee Yin, Ng, Kee Yean
• Application Number:
  US11/476,519
• Publication Number:
  US 20070295968A1
• Time in Patent Office: Days
• US Class Current: 257/79
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48464 the other connecting portion not on the bonding area also being a ball bond, i.e. ball-to-ball
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• 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 2924/00012 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 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin

Abstract

An encapsulant containing nanoparticles that improve the heat and UV resistance properties of electroluminescent devices. The nanoparticles that are suspended in the encapsulant may be either oxides or non-oxides and may include SiO₂, TiO₂, Al₂O₃, ZrO₂, Ti, TiB₂, TiC, and TiN. The nanoparticles may range in size from 5 to 165 nm in diameter. The encapsulant containing nanoparticles may be used in an electroluminescent device by being deposited in a concave base cavity to cover a light source, such as a light-emitting diode (“LED”), positioned in the concave base cavity, and may also be applied in the form of a conformal coating that covers the light source. An electroluminescent device utilizing the encapsulant containing nanoparticles and a method of producing such a device is also provided.

Claims

1. An electroluminescent device capable of emitting visible light, the electroluminescent device comprising:

a semiconductor radiation source; and

an encapsulant that is applied to the surface of the semiconductor radiation source, wherein the encapsulant contains a plurality of nanoparticles suspended therein selected from groups consisting of oxides and non-oxides.

2. The electroluminescent device of claim 1, wherein the semiconductor radiation source includes at least one light-emitting diode (“

LED”

).

3. The electroluminescent device of claim 2, wherein the nanoparticles are selected from a group consisting of silica (SiO₂), titania (TiO₂), alumina (Al₂O₃), and zirconia (ZrO₂).

4. The electroluminescent device of claim 3, wherein the average particle size of nanoparticles is 80-150 nm in diameter.

5. The electroluminescent device of claim 2, wherein the nanoparticles are selected from a group consisting of Ti, TiB₂, TiC, and TiN.

6. The electroluminescent device of claim 5, wherein the average particle size of nanoparticles is 40-100 nm in diameter.

7. The electroluminescent device of claim 2, wherein the encapsulant is applied to the surface of the at least one LED by at least one application of a conformal coating.

8. The electroluminescent device of claim 7, wherein the conformal coating includes a Spin-on Glass (“

SOG”

) material that contains the nanoparticles.

9. A method for producing an electroluminescent device that utilizes a semiconductor radiation source and an encapsulant, the method comprising:

suspending nanoparticles in the encapsulant;

applying the encapsulant to cover the surface of the semiconductor radiation source; and

packaging the semiconductor radiation source and the encapsulant in the electroluminescent device.

10. The method of claim 9, wherein the encapsulant is an epoxy resin, a silicone system, an acrylic, or a urethane.

11. The method of claim 10, wherein the semiconductor radiation source includes at least one LED.

12. The method of claim 11, wherein the nanoparticles are selected from a group consisting of silica (SiO₂), titania (TiO₂), alumina (Al₂O₃), zirconia (ZrO₂), Ti, TiB₂, TiC, and TiN.

13. The method of claim 12, further including:

positioning the at least one LED in a concave base cavity;

filling the concave base cavity with the encapsulant; and

packaging the concave base cavity with the at least one LED and the encapsulant in the electroluminescent device.

14. The method of claim 13, wherein packaging the concave base cavity further includes filling the electroluminescent device with the encapsulant.

15. The method of claim 12, wherein applying the encapsulant further includes applying the encapsulant in the form of a conformal coating.

16. The method of claim 15, wherein applying the encapsulant in the form of a conformal coating further includes:

suspending the nanoparticles in an SOG material; and

applying the SOG material in a liquid form to cover the at least one LED.

17. An encapsulant for use in an electroluminescent device capable of emitting visible light, the encapsulant comprising:

an epoxy resin, a silicone system, an acrylic, or a urethane; and

nanoparticles selected from groups consisting of oxides and non-oxides, wherein the nanoparticles each have a diameter of less than 165 nm, and are suspended in the encapsulant.

18. The encapsulant of claim 17, wherein the nanoparticles are selected from a group consisting of silica (SiO₂), titania (TiO₂), alumina (Al₂O₃), zirconia (ZrO₂), Ti, TiB₂, TiC, and TiN.

19. The encapsulant of claim 18, wherein the encapsulant is applied to cover a light source positioned in a concave base cavity of the electroluminescent device.

20. The encapsulant of claim 19, wherein the encapsulant is further applied in the form of a conformal coating.