Method of making a light emitting device having a molded encapsulant

• US 8,092,735 B2
• Filed: 08/06/2007
• Issued: 01/10/2012
• Est. Priority Date: 08/17/2006
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Thompson, D. Scott, Boardman, Larry D., Leatherdale, Catherine A.
• Primary Examiner(s): Del Sole, Joseph
• Assistant Examiner(s): KENNEDY, TIMOTHY J
• Application Number:
  US11/834,137
• Publication Number:
  US 20080079182A1
• Time in Patent Office: 1,618 Days
• Field of Search: 264/1.38, 264/1.9, 264/272.17, 264/272.11, 264/272.12, 264/272.13, 264/272.14, 264/272.15, 264/272.16, 264/494
• US Class Current: 264/272.17
• CPC Class Codes: B29C 2035/0827 using UV radiation
• CPC Class Codes: B29C 35/02 Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mouldcold vulcanisation B29C35/18 ; vulcanising tyres, presses therefor B29D30/0601
• CPC Class Codes: B29C 39/006 Monomers or prepolymers by reaction injection moulding B29C67/246
• CPC Class Codes: B29C 39/021 by casting in several steps
• CPC Class Codes: B29C 39/12 Making multilayered or multicoloured articles B29C39/021 takes precedence
• CPC Class Codes: B29C 65/02 by heating, with or without pressure
• CPC Class Codes: B29C 65/1416 Near-infrared radiation [NIR]
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/7375 uncured, partially cured or fully cured
• CPC Class Codes: B29C 66/73754 the to-be-joined areas of both parts to be joined being partially cured
• CPC Class Codes: B29C 66/73941 characterised by the materials of both parts being thermosets
• CPC Class Codes: B29C 70/72 Encapsulating inserts having non-encapsulated projections, e.g. extremities or terminal portions of electrical components B29C70/742 takes precedence
• CPC Class Codes: B29K 2063/00 Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2083/00 Use of polymers having silicon, with or without sulfur, nitrogen, oxygen, or carbon only, in the main chain, as moulding material
• CPC Class Codes: B29K 2105/243 Partially cured
• CPC Class Codes: B29K 2105/246 Uncured, e.g. green
• CPC Class Codes: B29L 2011/00 Optical elements, e.g. lenses, prisms
• CPC Class Codes: B29L 2031/747 Lightning equipment
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/85 : using a wire 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 24/97 : 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 2924/00014 : 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 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01045 : Rhodium [Rh]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01077 : Iridium [Ir]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/351 : Thermal stress
• CPC Class Codes: H01L 33/52 : Encapsulations

Abstract

Disclosed herein is a method of making a light emitting device having an LED die and a molded encapsulant made by polymerizing at least two polymerizable compositions. The method includes: (a) providing an LED package having an LED die disposed in a reflecting cup, the reflecting cup filled with a first polymerizable composition such that the LED die is encapsulated; (b) providing a mold having a cavity filled with a second polymerizable composition; (c) contacting the first and second polymerizable compositions; (d) polymerizing the first and second polymerizable compositions to form first and second polymerized compositions, respectively, wherein the first and second polymerized compositions are bonded together; and (e) optionally separating the mold from the second polymerized composition. Light emitting devices prepared according to the method are also described.

Claims

1. A method of making a light emitting device, the method comprising:

(a) providing an LED package comprising an LED die disposed in a reflecting cup, the reflecting cup filled with a first photopolymerizable composition such that the LED die is encapsulated, and partially polymerizing the first photopolymerizable composition to form a first partially photopolymerized composition, wherein partially polymerizing comprises applying actinic radiation having a wavelength of 700 nm or less;

(b) providing a mold having a cavity filled with a second polymerizable composition;

(c) contacting the first partially photopolymerized composition and the second polymerizable composition;

(d) polymerizing the first partially photopolymerized composition and the second polymerizable composition to form first and second polymerized compositions, respectively, wherein the first and second polymerized compositions are bonded together; and

(e) optionally separating the mold from the second polymerized composition.

2. The method of claim 1, wherein contacting the first partially photopolymerized composition and the second polymerizable composition comprises inverting the LED package.

3. The method of claim 1, wherein contacting the first partially photopolymerized composition and the second polymerizable compositions comprises inverting the mold.

4. The method of claim 1, wherein the second polymerizable composition comprises a second partially polymerized composition.

5. The method of claim 1, wherein the first photopolymerizable composition and/or the second polymerizable compositions are thixotropic.

6. The method of claim 1, wherein the first photopolymerizable composition comprises a resin selected from the group consisting of silicon-containing resins comprising silicon-bonded hydrogen and aliphatic unsaturation, epoxy silicones, and (meth)acrylated silicones.

7. The method of claim 1, wherein the second polymerizable composition comprises a resin selected from the group consisting of silicon-containing resins comprising silicon-bonded hydrogen and aliphatic unsaturation, epoxy silicones, and (meth)acrylated silicones.

8. The method of claim 1, wherein the second polymerizable composition comprises a multi-functional (meth)acrylate.

9. The method of claim 1, wherein the first photopolymerizable composition and the second polymerizable compositions are the same.

10. The method of claim 1, wherein the second polymerized composition is harder than the first.

11. The method of claim 1, wherein the first polymerized composition has a refractive index greater than that of the second.

12. The method of claim 1, wherein the second polymerized composition is harder than the first, and the first polymerized composition has a refractive index greater than that of the second.

13. The method of claim 1, wherein the first photopolymerizable composition comprises two layers having the same or different composition.

14. The method of claim 1, wherein the second polymerizable composition comprises two layers having the same or different composition.

15. The method of claim 1, the mold comprising a mold material and being shaped to impart a positive or negative lens on a substantial portion of the surface of the second polymerizable composition.

16. The method of claim 1, the mold comprising a mold material and being shaped to impart macrostructures, each macrostructure having a dimension of from 10 um to 1 mm.

17. The method of claim 1, the mold comprising a mold material and being shaped to impart microstructures, each microstructure having a dimension of from 100 nm to less than 10 um.

18. The method of claim 1, wherein polymerizing the first partially photopolymerized composition and the second polymerizable composition comprises applying actinic radiation having a wavelength of 700 nm or less.

19. The method of claim 1, wherein polymerizing the first partially photopolymerized composition and the second polymerizable composition comprises simultaneously applying actinic radiation having a wavelength of 700 nm or less and heating at less than 150°

C.

20. The method of claim 1, comprising separating the mold from the second polymerized composition to form a molded second polymerized composition, and the method further comprising heating the molded second polymerized composition at less than 150°

C.

21. The method of claim 1, the LED die comprising a plurality of LED dice.

22. The method of claim 21, wherein each LED die of the LED dice emits light of substantially the same wavelength.

23. The method of claim 21, wherein the LED dice emit light of different wavelengths.

24. The method of claim 1, wherein providing an LED package comprising an LED die disposed in a reflecting cup comprises providing a plurality of LED packages disposed on a lead frame, each LED package comprising an LED die disposed in a reflecting cup.