Light emitting diode, optical semiconductor element and epoxy resin composition suitable for optical semiconductor element and production methods therefor

• US 20030080341A1
• Filed: 09/11/2002
• Published: 05/01/2003
• Est. Priority Date: 01/24/2001
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Sakai, Kazuhiko, Umezu, Toshihiko, Sakano, Kensho, Okada, Yuji
• Granted Patent: US 6,960,878 B2
• Time in Patent Office: Days
• US Class Current: 257/79
• CPC Class Codes: B29C 67/08 Screen moulding, e.g. forcing the moulding material through a perforated screen on to a moulding surface
• CPC Class Codes: C08L 63/00 Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• CPC Class Codes: C09K 11/02 Use of particular materials as binders, particle coatings or suspension media therefor
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• 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 2224/48257 connecting the wire to a die 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 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/83 using a layer connector
• CPC Class Codes: H01L 2224/85 using a wire connector
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• 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 24/45 of an individual wire connector
• 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 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01012 : Magnesium [Mg]
• CPC Class Codes: H01L 2924/0102 : Calcium [Ca]
• CPC Class Codes: H01L 2924/01021 : Scandium [Sc]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/0103 : Zinc [Zn]
• CPC Class Codes: H01L 2924/01032 : Germanium [Ge]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01038 : Strontium [Sr]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01049 : Indium [In]
• CPC Class Codes: H01L 2924/01051 : Antimony [Sb]
• CPC Class Codes: H01L 2924/01052 : Tellurium [Te]
• CPC Class Codes: H01L 2924/01056 : Barium [Ba]
• CPC Class Codes: H01L 2924/01057 : Lanthanum [La]
• CPC Class Codes: H01L 2924/01058 : Cerium [Ce]
• CPC Class Codes: H01L 2924/0106 : Neodymium [Nd]
• CPC Class Codes: H01L 2924/01063 : Europium [Eu]
• CPC Class Codes: H01L 2924/01065 : Terbium [Tb]
• CPC Class Codes: H01L 2924/01066 : Dysprosium [Dy]
• CPC Class Codes: H01L 2924/01075 : Rhenium [Re]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01084 : Polonium [Po]
• CPC Class Codes: H01L 2924/01087 : Francium [Fr]
• CPC Class Codes: H01L 2924/10329 : Gallium arsenide [GaAs]
• CPC Class Codes: H01L 2924/12036 : PN diode
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/12043 : Photo diode
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/20753 : larger or equal to 30 microns less than 40 microns
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding
• CPC Class Codes: H01L 2924/351 : Thermal stress
• CPC Class Codes: H01L 33/486 : adapted for surface mounting
• CPC Class Codes: H01L 33/502 : Wavelength conversion materials
• CPC Class Codes: H01L 33/504 : Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/508 : having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material
• CPC Class Codes: H01L 33/54 : having a particular shape

Abstract

A light emitting diode comprising an LED chip having a light emitting layer made of a nitride compound semiconductor and a light transmitting resin that includes a fluorescent material which absorbs at least a part of light emitted by the LED chip and emits light of a different wavelength, wherein the fluorescent material includes a fluorescent particles of small particle size and a fluorescent particles of large particle size, the fluorescent particles of large particle size being distributed in the vicinity of the LED chip in the light transmitting resin to form a wavelength converting layer, the fluorescent particles of small particle size being distributed on the outside of the wavelength converting layer in the light transmitting resin.

Claims

1. A light emitting diode comprising an LED chip having a light emitting layer made of a nitride compound semiconductor and a light transmitting resin that includes a fluorescent material which absorbs at least a part of light emitted by said LED chip and emits light of a different wavelength,

wherein said fluorescent material includes a fluorescent particles of small particle size and a fluorescent particles of large particle size, said fluorescent particles of large particle size being distributed in the vicinity of said LED chip in said light transmitting resin to form a wavelength converting layer, said fluorescent particles of small particle size being distributed on the outside of said wavelength converting layer in the light transmitting resin.

2. The light emitting diode according to claim 1;

wherein said fluorescent particles of large particle size is prepared by controlling the particle size thereof within a range from 10 to 60 μ

m.

3. The light emitting diode according to claims 1 or 2;

wherein said fluorescent particles of small particle size is prepared by controlling the particle size thereof within a range from 0.2 to 1.5 μ

m.

4. The light emitting diode as in one of claims 1-3;

wherein the peak diameter of the particle size distribution of said fluorescent particles of large particle size is within a range from 20 to 90 times the peak diameter of the particle size distribution of said fluorescent particles of small particle size.

7. The light emitting diodes as in one of claims 1-6;

wherein the median diameter of the particle size of said fluorescent material is within a range from 15 to 50 μ

m.

8. The light emitting diodes according to claim 7;

wherein a distribution frequency of said median diameter is in a region from 20 to 50%.

9. The light emitting diode as in one of claims 1-8 further comprising a diffusing agent along with said fluorescent material in said light transmitting resin.

10. The light emitting diode as in one of claims 1-9;

wherein the light emitting surface of said light transmitting resin is a curved surface.

5. A light emitting diode comprising a LED chip made of a nitride semiconductor and a light transmitting resin having a fluorescent material which absorbs at least a part of light emitted by said LED chip and emits light of a different wavelength,

wherein said fluorescent material is characterized by a volume-based particle size distribution curve that is flat in a region of cumulative percentage from 0.01 to 10 vol %.

6. The light emitting diode according to claim 5;

wherein said fluorescent material consists of the fluorescent particles of small particle size and the fluorescent particles of large particle size separated by said flat region and the peak diameter of the particle size distribution of said fluorescent particles of large particle size is within a range from 20 to 90 times the peak diameter of the particle size distribution of said fluorescent particles of small particle size.

11. A light emitting diode comprising;

a package having a metal base consisting of a pair of thin metal sheets that constitute positive and negative electrodes being joined via a resin insulator for electrical isolation from each other and a side wall bonded to the circumference of said metal base on one side thereof thereby forming a mounting area,

an LED chip mounted in said mounting area and,

a light transmitting resin that fills the mounting area so as to seal the LED chip.

wherein said light transmitting resin is formed continuously from said mounting area over the top of said side wall and the top surface of said light transmitting resin is flat and substantially parallel to said metal base and the side face on the circumference of the light transmitting resin is substantially flush with the circumferential side face of the package.

12. The light emitting diodes according to claim 11;

wherein said light transmitting resin includes a filler.

13. The light emitting diodes according to claim 12;

wherein said filler includes a fluorescent material which absorbs at least a part of light emitted by said LED chip and emits light of a different wavelength.

14. The light emitting diodes according to claim 13;

wherein median diameter of said fluorescent material is set within a range from 15 to 50 μ

m.

15. A method for producing the light emitting diode according to claim 11 comprising;

a first step of making a package assembly consisting of a plurality of packages by bonding an insulating substrate having a plurality of through holes that are grouped corresponding to said mounting areas and a metal base plate having portions separated by the resin insulator in correspondence to the through holes,

a second step of mounting the LED chip in said mounting area of each package formed with the through hole,

a third step of applying and curing the light transmitting resin on the top surface of the insulating substrate and in the through holes by mimeograph printing by using a mask that has an aperture in correspondence to each group, and

a fourth step of dividing the package assembly having the light transmitting resin applied thereon into individual packages.

16. The method for producing the light emitting diode according to claim 15;

wherein said mimeograph printing is carried out while repeating the cycle of decreasing and increasing the pressure.

17. The method for producing the light emitting diode according to claims 15 or 16;

wherein the light transmitting resin contains fillers.

18. An epoxy resin composition comprising;

an epoxy resin containing an alicyclic epoxy resin, which accounts for 65% by weight or more of the epoxy resin, an acid anhydride represented by the general formula (1) or dicarboxylic acid represented by the general formula (2) in an amount of 0.005 to 1.5 mol based on an epoxy equivalent of the epoxy resin, and

a cation curing agent in an amount of 0.0001 to 0.01 mol based on an epoxy equivalent of said epoxy resin.

wherein R₁ represents a cyclic or aliphatic alkyl or aryl having 0 to 12 carbon atoms and R₂ represents an alkyl or aryl having 0 to 12 carbon atoms.

19. The epoxy resin composition according to claim 18;

wherein said alicyclic epoxy resin is a resin selected from the group consisting of an epoxidated cyclohexene derivative, a hydrated bisphenol A diglycidyl ether and a diglycidyl hexahydrophthalate ester.

20. The epoxy resin composition according to claim 18;

wherein said cation curing agent is one selected from the group consisting of an aromatic sulfonium salt, an aromatic diazonium salt, an aromatic iodonium salt and an aromatic selenium salt.

21. The epoxy resin composition according to claim 18 further comprising;

a polyhydric alcohol or a polycondensate thereof in the amount of 0.1 to 5.0 equivalents based on the acid anhydride or dicarboxylic acid.

22. The epoxy resin composition according to claim 21;

wherein said polyhydric alcohol is one selected from the group consisting of an ethylene glycol, a diethylene glycol, a trimethylene glycol, a triethylene glycol, a propylene glycol, a 1,4-butanediol, and a 1,6-hexanediol.

23. A method for producing the epoxy resin composition according to claim 18 comprising;

reacting said epoxy resin and said acid anhydride or dicarboxylic acid to obtain a crosslinked oligomer,

mixing of said crosslinked oligomer and said cation curing agent.

24. An optical semiconductor device comprising;

at least a pair of lead electrodes,

an optical semiconductor chip that is electrically connected to said lead electrodes, and

a molding resin that seals said optical semiconductor chip,

wherein said epoxy resin composition as in one of claims 18-22.

25. The optical semiconductor device according to claim 24, characterized in the surface mounted type made by joining said optical semiconductor chip on the surface of a substrate having said lead electrodes formed thereon.

26. The optical semiconductor device according to claims 24 or 25;

wherein said optical semiconductor chip is a light emitting diode chip having a light emitting layer made of a nitride semiconductor that includes at least In and Ga and a main peak of emission at a wavelength of 550 nm or shorter.

27. A method for producing a fluorescent material comprising a step of firing a mixture of a stock material and a flux, wherein said step of firing includes a first firing process of firing in a first reducing atmosphere and a second firing process of firing in a second reducing atmosphere, said first reducing atmosphere having weaker reducing power than the second reducing atmosphere.

28. The method for producing the fluorescent material according to claim 27;

wherein said flux is aluminum fluoride.

29. The method for producing the fluorescent material according to claims 27 or 28;

wherein said flux has barium fluoride and boric acid.

30. The method for producing the fluorescent material according to claim 29;

wherein said flux has a liquid.

32. The method for producing a fluorescent material according to claims 30 or 31;

wherein said liquid is water.

33. The method for producing a fluorescent material as in one of claims 27-32;

wherein said stock material includes Y₂O₃, Gd₂O₃, Al₂O₃ and CeO₂.

31. A method for producing a fluorescent material comprising a step of firing a mixture of a stock material and a flux having barium fluoride, boric acid and a liquid.