Multiple Lenses Molded Over LED Die

• US 20080157114A1
• Filed: 03/14/2008
• Published: 07/03/2008
• Est. Priority Date: 11/15/2004
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.)
• Inventors: Harbers, Gerard, West, Robert Scott, Martin, Paul S., Basin, Grigoriy, Hendriks, Robert F. M., Konijn, Frans H., Smits, Willem H.
• Granted Patent: US 9,081,167 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0066 in the form of an LED array
• CPC Class Codes: G02B 19/0071 adapted to illuminate a complete hemisphere or a plane extending 360 degrees around the source
• CPC Class Codes: H01L 2224/0554 External layer
• CPC Class Codes: H01L 2224/0555 Shape
• CPC Class Codes: H01L 2224/0556 Disposition
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/056 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• 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 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/81 using a bump connector
• CPC Class Codes: H01L 2224/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 24/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• 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 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01049 : Indium [In]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/15787 : Ceramics, e.g. crystalline carbides, nitrides or oxides
• CPC Class Codes: H01L 2924/1815 : Shape
• CPC Class Codes: H01L 2924/19107 : off-chip wires
• CPC Class Codes: H01L 33/46 : Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/507 : the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: H01L 33/54 : having a particular shape
• CPC Class Codes: H01L 33/58 : Optical field-shaping elements
• CPC Class Codes: H05K 2201/10106 : Light emitting diode [LED]
• CPC Class Codes: H05K 3/284 : for encapsulating mounted components H05K1/185 takes precedence

Abstract

One or more LED dice are mounted on a support structure. The support structure may be a submount with the LED dice already electrically connected to leads on the submount. A mold has indentations in it corresponding to the positions of the LED dice on the support structure. The indentations are filled with a liquid optically transparent material, such as silicone, which when cured forms a lens material. The shape of the indentations will be the shape of the lens. The mold and the LED dice/support structure are brought together so that each LED die resides within the liquid silicone in an associated indentation. The mold is then heated to cure (harden) the silicone. The mold and the support structure are then separated, leaving a complete silicone lens over each LED die. This over molding process may be repeated with different molds to create concentric shells of lenses. Each concentric lens may have a different property, such as containing a phosphor, providing a special radiation pattern, having a different hardness value, or curable by a different technique (e.g., UV vs. heat).

Claims

1. A light emitting device formed by the method comprising:

providing a light emitting diode (LED) die attached to a support structure;

molding a first lens directly over the LED die by compression molding, wherein a first mold is first filled with a first lens material, then the LED die is immersed into the first lens material under compression, thereafter the first lens material is cured, and the LED die and first lens are separated from the first mold, wherein no liquid channel for the first lens material leads to the first mold such that there is no excess first lens material from a liquid channel immediately after the LED die and first lens are separated from the first mold;

the first lens encapsulating the LED die, the first lens being formed of a first material and having an outer surface; and

molding a second lens directly over the first lens by compression molding to substantially completely cover the outer surface of the first lens, wherein a second mold is first filled with a second lens material, then the LED die and first lens are immersed into the second lens material under compression, thereafter the second lens material is cured, and the LED die, first lens, and second lens are separated from the second mold, wherein no liquid channel for the second lens material leads to the second mold such that there is no excess second lens material from a liquid channel immediately after the LED die, first lens, and second lens are separated from the second mold, the second lens being formed of a second material.

2. The device of claim 1 wherein the second lens is harder than the first lens.

3. The device of claim 1 wherein the support structure comprises a submount having metal leads in electrical contact with metal contacts on the LED die.

4. The device of claim 1 wherein the LED die is one of a plurality of LED dice affixed to the support structure.

5. The device of claim 1 wherein the first lens is generally hemispherical to emit light in a Lambertian pattern.

6. The device of claim 1 wherein the first lens is generally rectangular with rounded edges.

7. The device of claim 1 wherein the second lens has a pattern molded into an outer surface of the second lens for affecting an emitted light pattern.

8. The device of claim 7 wherein the pattern comprises a Fresnel lens, a diffraction grating, a binary pattern, pyramids, or cones.

9. The device of claim 1 wherein a range of hardness of the first lens is Shore 00 5-90, and the hardness of the second lens is greater than Shore A 30.

10. The device of claim 1 wherein the second lens is a collimating lens.

11. The device of claim 1 wherein the second lens is a side-emitting lens.

12. The device of claim 1 wherein the first lens contains a first phosphor.

13. The device of claim 12 wherein the second lens contains a second phosphor.

14. The device of claim 1 wherein the second lens contains a phosphor.

15. The device of claim 1 further comprising a backlight for a liquid crystal display, the backlight incorporating the LED, first lens, and second lens.

16. The device of claim 1 further comprising a rear projection television, the television incorporating the LED, first lens, and second lens.

17. The device of claim 1 wherein a shape of the first lens is symmetrical about a center axis.

18. The device of claim 1 wherein a shape of the second lens is symmetrical about a center axis.