Surface-mountable light-emitting diode light source and method of producing a light-emitting diode light source

• US 20020195935A1
• Filed: 07/01/2002
• Published: 12/26/2002
• Est. Priority Date: 12/30/1999
• Status: Active Grant

• Current Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Original Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Inventors: Jager, Harald, Hohn, Klaus, Brunner, Reinhold
• Granted Patent: US 7,098,588 B2
• Time in Patent Office: Days
• US Class Current: 313/512
• 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 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 2924/0102 Calcium [Ca]
• CPC Class Codes: H01L 2924/01039 Yttrium [Y]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/501 characterised by the materials, e.g. binder

Abstract

A surface-mountable light-emitting diode light source is described, in which the leadframe-bends toward the rear side of the package that are required for surface mounting lie within a transparent plastic molded body. Also described is a method of producing a mixed-light, preferably white-light source on the basis of a UV- or blue-emitting semiconductor LED. The LED is mounted on a leadframe, a transparent plastics molding composition is mixed with a conversion substance and possibly further fillers to form a molding composition. The leadframe is encapsulated, preferably by the injection-molding process, with the molding composition in such a way that the LED is surrounded on its light-exiting sides by the molding composition.

Claims

1. A surface-mountable light-emitting diode light source, comprising:

a leadframe having a mounting side, a chip mounting region and an LED chip mounted on said leadframe;

a one-piece transparent plastic molded body encapsulating said leadframe and said LED chip;

leadframe connections for said LED chip, protruding on each of at least two side faces of said plastic body; and

each of said leadframe connections having an S-shaped bend, extending from said chip mounting region to said mounting side, within said plastic molded body of the light-emitting diode light source.

2. The surface-mountable light-emitting diode light source according to claim 1, wherein said transparent plastic molded body is produced from a plastics molding composition.

3. The surface-mountable light-emitting diode light source according to claim 2, wherein said plastics molding composition is admixed with at least one inorganic filler selected from the group consisting of TiO₂, ZrO₂ and α

-Al₂O₃ for increasing a refractive index of said molding composition.

4. The surface-mountable light-emitting diode light source according to claim 2, wherein said plastics molding composition is admixed with an agent selected from the group consisting of demolding agent and release agent.

5. The surface-mountable light-emitting diode light source according to claim 2, wherein said plastics molding composition substantially comprises a pre-reacted epoxy resin.

6. The surface-mountable light-emitting diode light source according to claim 2, wherein said plastics molding composition is admixed with a substance selected from the group consisting of organic substance and inorganic conversion substance, said substance absorbing part of a radiation emitted by said LED chip and emitting a longer-wave radiation in comparison with said absorbed radiation, whereby the light source emits mixed-colored light including primary light of said LED chip and secondary light of said conversion substance.

7. The surface-mountable light-emitting diode light source according to claim 4, wherein said demolding agent is selected from the group consisting of solid wax-based demolding agent and metallic soap with long-chain carboxylic acids.

8. The surface-mountable light-emitting diode light source according to claim 5, wherein said pre-reacted epoxy resin is selected from the group consisting of epoxy novolak resin and epoxy cresol novolak.

9. The surface-mountable light-emitting diode light source according to claim 5, wherein said epoxy resin is pre-reacted with an element selected from the group consisting of phenol and anhydride hardener.

10. The surface-mountable light-emitting diode light source according to claim 5, wherein said epoxy resin is pre-reacted with a phenol and an anhydride hardener.

11. The surface-mountable light-emitting diode light source according to claim 7, wherein said demolding agent includes stearates.

14. The method according to claim 13, which comprises using a resin-based plastics molding composition.

15. The method according to claim 14, which comprises using a pre-reacted epoxy resin selected from the group consisting of epoxy novolak and epoxy cresol novolak.

16. The method according to claim 15, which comprises pre-reacting the epoxy resin with a material selected from the group consisting of phenol and anhydride hardener.

17. The method according to claim 13, which comprises selecting the conversion substance from an organic substance, an inorganic luminescent substance and a mixture thereof.

18. The method according to claim 17, wherein the inorganic luminescent substance contains a luminescent substance metal center in a host lattice on the basis of the general formula A₃B₅X₁₂ or a sulfide, oxysulfide, borate, aluminate or metal-chelate complexes.

19. The method according to claim 13, which comprises admixing an adhesion promoter with the conversion substance to improve the adhesiveness of the conversion substance before the mixing of the plastics molding composition.

20. The method according to claim 19, which comprises admixing the adhesion promoter in liquid form.

21. The method according to claim 13, which comprises using a member selected from the group consisting of 3-glycidoxypropyltrimethoxy-silane and further trialkoxysilane-based derivatives as adhesion promoters.

22. The method according to claim 13, admixing a surface modifier, with the conversion substance to modify the surfaces of the conversion substance, before the mixing of the plastics molding composition.

23. The method according to claim 22, which comprises admixing the surface modifier in liquid form.

24. The method according to claim 23, which comprises using diethyleneglycolmonomethylether as the surface modifier.

25. The method according to claim 13, which comprises admixing an agent selected from the group consisting of demolding agent and release agent with the plastics molding composition before mixing with the conversion substance.

26. The method according to claim 25, which comprises selecting the demolding agent from a solid wax-based demolding agent and a metallic soap with long-chain carboxylic acids.

27. The method as according to claim 13, which comprises:

selecting an inorganic filler from TiO₂, ZrO₂ and a-Al₂O₃; and

admixing the molding composition with the inorganic filler for increasing the refractive index of the molding composition.

28. The method according to claim 13, which comprises:

mixing the plastics molding composition and the conversion substance and optionally further fillers initially coarsely; and

grounding the mixture in a mill and obtaining a homogeneous powder.

29. The method according to claim 28, which comprises milling the plastics molding composition in a coffee mill before mixing.

30. The method according to claim 29, which comprises:

providing the mixed molding composition with the following constituents;

plastics molding composition ≧

60%

conversion substance >

0 and ≦

40%

adhesion promoter ≧

0 and ≦

3%

demolding agent ≧

0 and ≦

2%

surface modifier ≧

0 and ≦

5%

oxidation stabilizer ≧

0 and ≦

5%; and

UV light stabilizer ≧

0 and ≦

2%.

31. The method according to claim 13, which comprises:

producing the light source as a surface-mountable component; and

molding the molding composition, which includes leading out leadframe connections laterally from the molding composition on a mounting side of the completed white-light source and forming horizontal mounting surfaces.

12. A method for producing a light-emitting diode light source, which comprises:

mounting a LED chip in a chip mounting region on a leadframe;

connecting the LED chip in an electrically conducting manner to leadframe connections;

forming the leadframe connections with S-shaped bends; and

encapsulating the semiconductor LED and the S-shaped bends with a transparent plastics molding composition.

13. A method of producing a white-light source with a semiconductor LED chip that emits light radiation in ultraviolet or blue spectral range, which comprises:

mounting the LED chip on a leadframe;

mixing a transparent plastics molding composition with a conversion substance and optionally with further fillers to form a molding composition; and

encapsulating the leadframe with the molding composition in such a way that the LED is surrounded by the molding composition on light exiting sides thereof.