Light emitting device with silicone resin layer formed by screen printing

• US 7,745,818 B2
• Filed: 04/07/2006
• Issued: 06/29/2010
• Est. Priority Date: 04/08/2005
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Tamaki, Hiroto, Sofue, Shinsuke, Izuno, Kunihiro
• Primary Examiner(s): Lee; Eugene
• Assistant Examiner(s): Ho; Anthony
• Application Number:
  US11/399,501
• Publication Number:
  US 20060226758A1
• Time in Patent Office: 1,544 Days
• Field of Search: 257/40, 257/99, 257/100, 257/E33.059
• US Class Current: 257/40
• CPC Class Codes: C09D 183/04 Polysiloxanes
• CPC Class Codes: C09D 183/06 containing silicon bound to oxygen-containing groups C09D183/12 takes precedence
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2924/00011 Not 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 33/56 Materials, e.g. epoxy or silicone resin

Abstract

A light emitting device, including a light emitting element, and a resin layer that has been screen printed to coat said light emitting element is provided. The resin layer is formed from a curable silicone resin composition, which includes (i) an organopolysiloxane with a polystyrene equivalent weight average molecular weight of at least 5×10³, (ii) a condensation catalyst, (iii) a solvent, and (iv) a finely powdered inorganic filler. The uniformity of the film thickness is excellent, thus resulting in little color irregularities during light emission from the light emitting element.

Claims

1. A light emitting device, comprising a light emitting element, and a resin layer that has been screen printed to coat said light emitting element, wherein

said resin layer comprises a cured product in a dry state formed by curing a curable silicone resin composition, said curable silicone resin composition comprising:

(i) an organopolysiloxane with a polystyrene equivalent weight average molecular weight of at least 5×

10³, represented by an average composition formula (1) shown below;

R¹_a(OX)_bSiO<sub>(4−

a−

b)/2</sub> 

 

(1)

wherein, each R¹ represents, independently, an alkyl group, alkenyl group or aryl group of 1 to 6 carbon atoms, each X represents, independently, a hydrogen atom, or an alkyl group, alkenyl group, alkoxyalkyl group or acyl group of 1 to 6 carbon atoms, a represents a number within a range from 1.05 to 1.5, b represents a number that satisfies 0<

b<

2, and a value of a+b satisfies 1.05<

a+b<

2,

(ii) a condensation catalyst selected from the group consisting of organometallic compounds containing a zinc, aluminium, titanium, tin, or cobalt atom,

(iii) a solvent, and

(iv) a finely powdered inorganic filler.

2. The light emitting device according to claim 1, wherein said R¹ represents a methyl group.

3. The light emitting device according to claim 1, wherein a proportion of said R¹ groups within said organopolysiloxane (i) is no more than 32% by mass.

4. The light emitting device according to claim 1, wherein said condensation catalyst (ii) is an organometallic catalyst.

5. The light emitting device according to claim 1, wherein said resin layer has a thickness within a range from 10 μ

m to 3 mm, and is colorless and transparent.

6. The light emitting device according to claim 1, wherein said light emitting element is flip-chip mounted to a sub-mount substrate, and said light emitting element and said sub-mount substrate are coated with a screen printed resin layer.

7. The light emitting device according to claim 6, wherein a hollow space is formed between said light emitting element and said sub-mount substrate.