Curable silicone composition for sealing an optical semiconductor element, method of producing a resin-sealed optical semiconductor element, and resin-sealed optical semiconductor element

1. A curable silicone composition for sealing an optical semiconductor element, the composition comprising:

(A) an organopolysiloxane that has a viscosity at 25° C. of 50 to 100,000 mPa·s, that has at least two silicon-bonded vinyl groups in one molecule, that has C 1-10 alkyl for the other silicon-bonded organic groups therein, and that lacks a siloxane unit represented by the following formula: SiO 4/2 ;

(B) an organopolysiloxane represented by the following average unit formula:

(ViR 2 SiO 1/2 ) a (R 3 SiO 1/2 ) b (SiO 4/2 ) c (HO 1/2 ) d

wherein Vi is a vinyl group; each R is independently a C 1-10 alkyl group; and a, b, c, and d are each positive numbers that satisfy: a+b+c=1, a/(a+b)=0.15 to 0.35, c/(a+b+c)=0.53 to 0.62, and d/(a+b+c)=0.005 to 0.03, at from 15 to 35 mass % of the total of components (A) and (B);

(C) an organopolysiloxane that has at least three silicon-bonded hydrogen atoms in one molecule, that has C 1-10 alkyl for the silicon-bonded organic groups therein, and that contains from 0.7 to 1.6 mass % of silicon-bonded hydrogen atoms, in a quantity that provides from 0.8 to 2.0 moles silicon-bonded hydrogen atoms in this component per 1 mole of the total vinyl groups in components (A) and (B); and

(D) a hydrosilylation reaction catalyst, in a quantity sufficient to cure the composition;

wherein a viscosity at 25° C. of the composition lacking component (D) is from 3,000 to 10,000 mPa·s and, letting η 25° C. be this viscosity in mPa·s and letting η 100° C. be a viscosity in mPa·s at 100° C. of the composition lacking component (D), a value of the following formula: Log 10 η 100° C. /Log 10 η 25° C.

is 0.830 to 0.870.

2. The composition according to claim 1 , that cures to form a silicone cured product that has a type A durometer hardness as specified in JIS K 6253 of from 60 to 80.

3. A method of producing a resin-sealed optical semiconductor element, the method comprising resin-sealing an optical semiconductor element using the composition according to claim 1 to produce the resin-sealed optical semiconductor element, wherein resin-sealing occurs at a temperature that yields a gel time of 30 to 120 seconds by the hot plate method specified in JIS C 2105.

4. A resin-sealed optical semiconductor element produced by the method according to claim 3 .

5. The method according to claim 3 , wherein resin-sealing is accomplished by transfer molding the composition according to claim 1 .

6. The method according to claim 3 , wherein resin-sealing is accomplished by compression molding the composition according to claim 1 .

7. The method according to claim 3 , wherein the optical semiconductor element is a light emitting diode (LED).

8. The composition according to claim 1 , wherein component (A) comprises at least one of the following organopolysiloxanes, with Vi representing a vinyl group and Me representing a methyl group:

ViMe 2 SiO(Me 2 SiO) 160 SiMe 2 Vi;

ViMe 2 SiO(Me 2 SiO) 310 SiMe 2 Vi;

ViMe 2 SiO(Me 2 SiO) 515 SiMe 2 Vi;

ViMe 2 SiO(Me 2 SiO) 800 SiMe 2 Vi;

Me 3 SiO(Me 2 SiO) 140 (MeViSiO) 20 SiMe 3 ;

ViMe 2 SiO(Me 2 SiO) 500 (MeViSiO) 15 SiMe 2 Vi;

ViMe 2 SiO(Me 2 SiO) 780 (MeViSiO) 20 SiMe 2 Vi;

MeSi{O(Me 2 SiO) 80 SiMe 2 Vi} 3 ; and

Si{O(Me 2 SiO) 60 SiMe 2 Vi} 4 .

9. The composition according to claim 8 , wherein component (B) comprises at least one of the following organopolysiloxanes, with Vi representing a vinyl group and Me representing a methyl group:

(ViMe 2 SiO 1/2 ) 0.10 (Me 3 SiO 1/2 ) 0.32 (SiO 4/2 ) 0.58 (HO 1/2 ) 0.02 ;

(ViMe 2 SiO 1/2 ) 0.15 (Me 3 SiO 1/2 ) 0.29 (SiO 4/2 ) 0.56 (HO 1/2 ) 0.01 ; and

(ViMe 2 SiO 1/2 ) 0.11 (Me 3 SiO 1/2 ) 0.33 (SiO 4/2 ) 0.56 (HO 1/2 ) 0.01 .

10. The composition according to claim 9 , wherein component (C) comprises at least one of the following organopolysiloxanes, with Me representing a methyl group:

Me 3 SiO(Me 2 SiO) 5 (MeHSiO) 5 SiMe 3 ;

Me 3 SiO(MeHSiO) 14 SiMe 3 ; and

Me 3 SiO(MeHSiO) 50 SiMe 3 .

11. The composition according to claim 1 , wherein component (B) comprises at least one of the following organopolysiloxanes, with Vi representing a vinyl group and Me representing a methyl group:

(ViMe 2 SiO 1/2 ) 0.10 (Me 3 SiO 1/2 ) 0.32 (SiO 4/2 ) 0.58 (HO 1/2 ) 0.02 ;

(ViMe 2 SiO 1/2 ) 0.15 (Me 3 SiO 1/2 ) 0.29 (SiO 4/2 ) 0.56 (HO 1/2 ) 0.01 ; and

(ViMe 2 SiO 1/2 ) 0.11 (Me 3 SiO 1/2 ) 0.33 (SiO 4/2 ) 0.56 (HO 1/2 ) 0.01 .

12. The composition according to claim 1 , wherein component (C) comprises at least one of the following organopolysiloxanes, with Me representing a methyl group:

Me 3 SiO(Me 2 SiO) 5 (MeHSiO) 5 SiMe 3 ;

Me 3 SiO(MeHSiO) 14 SiMe 3 ; and

Me 3 SiO(MeHSiO) 50 SiMe 3 .

13. The composition according to claim 1 , wherein Log 10 η 100° C. /Log 10 η 25° C. is 0.840 to 0.860.

14. The composition according to claim 1 , further comprising:

i) a reaction inhibitor;

ii) an adhesion promoter; or

iii) both i) and ii).

15. A silicone cured product formed from the composition according to claim 1 , wherein the product has a type A durometer hardness as specified in JIS K 6253 of from 60 to 80.