Semiconductor light emitting device resistible to ultraviolet light

• US 6,756,731 B1
• Filed: 06/03/2000
• Issued: 06/29/2004
• Est. Priority Date: 06/03/1999
• Status: Expired due to Fees

• Current Assignee: Sanken Electric Company Limited
• Original Assignee: Sanken Electric Company Limited
• Inventors: Sano, Takeshi
• Primary Examiner(s): Patel, Nimeshkumar D.
• Assistant Examiner(s): HODGES, MATTHEW P
• Application Number:
  US09/586,656
• Time in Patent Office: 1,487 Days
• Field of Search: 313/499, 257/98, 257/88, 257/10, 257/100, 257/97
• US Class Current: 313/499
• CPC Class Codes: H01J 1/62 Luminescent screens; Selection of materials for luminescent coatings on vessels
• 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 2224/49107 on the semiconductor or solid-state body
• 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 33/501 characterised by the materials, e.g. binder
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin

Abstract

A semiconductor light emitting device is provided with a coating material 10 which directly covers the semiconductor light emitting element 2. The coating material 10 comprises a polymetaloxane or a ceramic having a permeability to the ultraviolet light projected from a semiconductor light emitting element 2. The coating material 10 with resistances to ultraviolet light and heat will not be deteriorated even under a high-temperature environment irradiated with ultraviolet light over a long period of time.

Claims

1. A semiconductor light emitting device comprising a base having first and second external terminals, a semiconductor light emitting element secured to said base, and a light-permeable coating material for covering said semiconductor light emitting element, said semiconductor light emitting element comprising electrodes electrically connected respectively to said first and second external terminals,

wherein said coating material is selected from one of the following:

(1) a glass of a polymetaloxane formed mainly based on the metaloxane bond from a metal alcoxide,

(2) a gel of a polymetaloxane formed from a metal alcoxide, and

(3) a ceramic formed from a polysilazane as a ceramic precursor; and

said coating material tightly and strongly adheres directly to the semiconductor light emitting element and electrodes.

2. A semiconductor light emitting device of claim 1, wherein said metal alcoxide is of one or more type selected from a single-metal alcoxide, a two-metal alcoxide and a multi-metal alcoxide.

3. A semiconductor light emitting device of claim 1, wherein ceramic of said coating material is formed by applying a heat treatment to the ceramic precursor.

4. A semiconductor light emitting device of claim 1, wherein said coating material covers all the surfaces of said semiconductor light emitting element excluding the bottom surface thereof.

5. A semiconductor light emitting device of claim 1, wherein said base has a concavity filled with said coating material.

6. A semiconductor light emitting device of claim 1, wherein said base is an insulative substrate or a lead frame.

7. A semiconductor light emitting device of claim 1, wherein said semiconductor light emitting element emits light at light wavelengths of 365 nm to 550 nm.

8. A semiconductor light emitting device of claim 7, wherein said semiconductor light emitting element comprises a gallium nitride compound semiconductor light emitting element.

9. A semiconductor light emitting device of claim 1, wherein said coating material contains a fluorescent substance for receiving at least a part of the light projected from said semiconductor light emitting element to perform wavelength-conversion of the light.

10. A semiconductor light emitting device of claim 9, wherein said fluorescent substance absorbs at least a part of the light projected from said semiconductor light emitting element, and emits light having a wavelength longer than that of the light projected.

11. A semiconductor light emitting device of claim 10, wherein the light projected from said semiconductor light emitting element is mixed with the light wavelength-converted by said fluorescent substance to release the mixed light out of said coating material.

12. A semiconductor light emitting device of claim 1, wherein said coating material is covered with an encapsulant.

13. A semiconductor light emitting device of claim 12, wherein said encapsulant is formed of a plastic which contains a light scattering material or a binder.

14. A semiconductor light emitting device of claim 13, wherein the light projected from said semiconductor light emitting element permeates said coating material before being released to the outside of said encapsulant.

15. A semiconductor light emitting device of claim 14, wherein said encapsulant is fitted into said concavity, and said coating material is formed between the bottom surface of said concavity and said encapsulant.

16. A semiconductor light emitting device of claim 1, wherein a concavity is formed in one principal surface of an insulative substrate for constituting said base;

said semiconductor light emitting element is secured to the bottom surface of the concavity; and

a pair of said electrodes in said semiconductor light emitting element is electrically connected to a pair of said external terminals formed on the one principal surface of said insulative substrate.

17. A semiconductor light emitting device of claim 1, wherein a lead frame for constituting said base has a pair of said external terminals;

a concavity is formed in either of said external terminals;

said semiconductor light emitting element is secured to the bottom surface of the concavity.

18. A semiconductor light emitting device comprising a base having first and second external terminals, a semiconductor light emitting element secured to said base, and a light-permeable coating material for covering said semiconductor light emitting element, said semiconductor light emitting element comprising electrodes electrically connected respectively to said first and second external terminals,

wherein said coating material is selected from one of the following:

(1) a glass of a polymetaloxane formed mainly based on the metaloxane bond,

(2) a gel of a polymetaloxane, and

(3) a ceramic formed from a ceramic precursor, and

said coating material directly adheres to the semiconductor light emitting element and electrodes,

said semiconductor light emitting element is secured to said base by an adhesive of the same material as that of said coating material.