Condensation-curable silicone resin composition

Abstract

One of the purposes of the present invention is to provide a condensation-curable silicone resin composition which show a less increase of the viscosity during handling and cures quickly to provide a cured product which has a very small amount of a remaining catalyst and which has high heat resistance and high light resistance. Thus, the present invention is to provide a condensation-curable silicone composition comprising the following components (A) to (C): (A) 100 parts by mass of an organopolysiloxane which has a branched or network structure and has two or more hydrolyzable groups each bonded to a silicon atom and at least one of (R.sup.1SiO.sub.3/2) and (SiO.sub.4/2) units, wherein R.sup.1 is, independently of each other, a hydrogen atom or a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 12 carbon atoms, (B) 5 to 500 parts by mass of a linear organopolysiloxane having at least one hydrolyzable group bonded to a silicon atom at each of both terminals, and (C) at least one silazane compound represented by the following general formula (3) or (5) or comprising the following units (6) in an amount of 0.02 to 30 parts by mass, relative to total 100 parts by mass of components (A) and (B): ##STR00001##

Claims

1. A LED element encapsulated with a cured product obtained by curing an encapsulating composition for semiconductor devices, wherein the encapsulating composition comprises the following components (A) to (C): (A) 100 parts by mass of an organopolysiloxane which has a branched or network structure, has two or more hydrolyzable groups each bonded to a silicon atom and at least one (R.sup.1SiO.sub.3/2) unit, wherein R.sup.1 is, independently of each other, a hydrogen atom or a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 12 carbon atoms, (B) 5 to 500 parts by mass of a linear organopolysiloxane having at least one hydrolyzable group bonded to a silicon atom at each of both terminals, and (C) at least one silazane compound represented by the following general formula (3), (3) or (5) or comprising the following units (6) in an amount of 0.02 to 30 parts by mass, relative to total 100 parts by mass of components (A) and (B): ##STR00013## wherein X is, independently of each other, a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms, R.sup.1 is, independently of each other, a hydrogen atom or a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 12 carbon atoms, m is an integer of from 3 to 8, f is an integer of from 1 to 500, g is an integer of from 0 to 500, h is an integer of from 0 to 200, provided that the total of f, g and h is 10 to 500, the parenthesized silazane units may form a block unit or bond randomly, and X is, independently of each other, a hydrogen atom, a monovalent hydrocarbon group having 1 to 12 carbon atoms, or a group represented by the following formula (4): ##STR00014## wherein R.sup.1 is, independently of each other, a hydrogen atom or a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 12 carbon atoms, provided that the composition comprises neither any amine compound catalyst besides said silazane compound nor any organic metal catalyst.

2. An encapsulating composition for semiconductor devices comprising the following components (A) to (C): (A) 100 parts by mass of an organopolysiloxane which has a branched or network structure, has two or more hydrolyzable groups each bonded to a silicon atom and at least one (R.sup.1SiO.sub.3/2) unit, wherein R.sup.1 is, independently of each other, a hydrogen atom or a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 12 carbon atoms, (B) 5 to 500 parts by mass of a linear organopolysiloxane having at least one hydrolyzable group bonded to a silicon atom at each of both terminals, and (C) at least one silazane compound represented by the following general formula (3), (3) or (5) or comprising the following units (6) in an amount of 0.02 to 30 parts by mass, relative to total 100 parts by mass of components (A) and (B): ##STR00015## wherein X is, independently of each other, a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms, R.sup.1 is, independently of each other, a hydrogen atom or a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 12 carbon atoms, m is an integer of from 3 to 8, f is an integer of from 1 to 500, g is an integer of from 0 to 500, h is an integer of from 0 to 200, provided that the total of f, g and h is 10 to 500, the parenthesized silazane units may form a block unit or bond randomly, and X is, independently of each other, a hydrogen atom, a monovalent hydrocarbon group having 1 to 12 carbon atoms, or a group represented by the following formula (4): ##STR00016## wherein R.sup.1 is, independently of each other, a hydrogen atom or a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 12 carbon atoms, provided that the composition comprises neither any amine compound catalyst besides said silazane compound nor any organic metal catalyst, and further comprising a rare earth element compound.

3. The encapsulating composition for semiconductor devices according to claim 2, wherein the rare earth element compound is at least one compound selected from the group consisting of an organic complex of a rare earth element, a rare earth element alkoxide having an alkoxy group, and an organic acid salt of a rare earth element via an organic acid.

4. The encapsulating composition for semiconductor devices according to claim 2, wherein the rare earth element is at least one element selected from the group consisting of lanthanum, cerium, neodymium, europium, and ytterbium.

5. The encapsulating composition for semiconductor devices according to claim 2, wherein an amount of the rare earth element is 10 to 3,000 ppm relative to a total 100 parts by mass of the components (A), (B) and (C).

6. The LED element according to claim 1, wherein component (A) is represented by the following general formula (1):
(R.sup.1.sub.3SiO.sub.1/2).sub.a(R.sup.1.sub.2SiO.sub.2/2).sub.b(R.sup.1SiO.sub.3/2).sub.c(SiO.sub.4/2).sub.d(O.sub.1/2R.sup.2).sub.e(1) wherein R.sup.1 is, independently of each other, a hydrogen atom or a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 12 carbon atoms, R.sup.2 is, independently of each other, a hydrogen atom or a monovalent hydrocarbon group which has 1 to 6 carbon atoms and may have an oxygen atom, a is an integer of from 0 to 500, b is an integer of from 0 to 1,000, c is an integer of from 1 to 500, d is an integer of from 0 to 500, provided that a total of c and d is 3 to 500, e is an integer of from 2 to 100, and the parenthesized silazane units may form a block unit or bond randomly.

7. The LED element according to claim 1, wherein component (B) is represented by the following general formula (2): ##STR00017## wherein R.sup.1 is, independently of each other, a hydrogen atom or a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 12 carbon atoms, R.sup.2 is, independently of each other, a hydrogen atom or a monovalent hydrocarbon group which has 1 to 6 carbon atoms and may have an oxygen atom, k is, independently of each other, an integer of from 1 to 3, and n is an integer of from 1 to 2,000.

8. The encapsulating composition for semiconductor devices according to claim 2, wherein component (A) is represented by the following general formula (1):
(R.sup.1.sub.3SiO.sub.1/2).sub.a(R.sup.1.sub.2SiO.sub.2/2).sub.b(R.sup.1SiO.sub.3/2).sub.c(SiO.sub.4/2).sub.d(O.sub.1/2R.sup.2).sub.e(1) wherein R.sup.1 is, independently of each other, a hydrogen atom or a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 12 carbon atoms, R.sup.2 is, independently of each other, a hydrogen atom or a monovalent hydrocarbon group which has 1 to 6 carbon atoms and may have an oxygen atom, a is an integer of from 0 to 500, b is an integer of from 0 to 1,000, c is an integer of from 1 to 500, d is an integer of from 0 to 500, provided that a total of c and d is 3 to 500, e is an integer of from 2 to 100, and the parenthesized silazane units may form a block unit or bond randomly.

9. The encapsulating composition for semiconductor devices according to claim 2, wherein component (B) is represented by the following general formula (2): ##STR00018## wherein R.sup.1 is, independently of each other, a hydrogen atom or a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 12 carbon atoms, R.sup.2 is, independently of each other, a hydrogen atom or a monovalent hydrocarbon group which has 1 to 6 carbon atoms and may have an oxygen atom, k is, independently of each other, an integer of from 1 to 3, and n is an integer of from 1 to 2,000.

Description

EXAMPLES

(1) The present invention will be explained below in further detail with reference to a series of the Examples and the Comparative Examples, though the present invention is in no way limited by these Examples.

(2) Components (A) to (C) used in the Examples and the Comparative Examples will be explained below. In the following description, Me is an abbreviation for a methyl group, Et is an abbreviation for an ethyl group, iPr is an abbreviation for an isopropyl group, and Ph is an abbreviation for a phenyl group. The bonding order of the parenthesized siloxane units in the following organopolysiloxane may form a block unit or bond randomly.

(A) Branched Organopolysiloxane

(3) (A-1) a branched organopolysiloxane, ex Shin-Etsu Chemical Co., Ltd., represented by the following formula: (Me.sub.3SiO.sub.1/2).sub.4(PhSiO.sub.3/2).sub.16(O.sub.1/2H).sub.4

(4) (A-2) a branched organopolysiloxane, ex Shin-Etsu Chemical Co., Ltd., represented by the following formula: (Me.sub.3SiO.sub.1/2).sub.5(Me.sub.2SiO.sub.2/2).sub.100(PhSiO.sub.3/2).sub.15(O.sub.1/2H).sub.4

(5) (A-3) a branched organopolysiloxane, ex Shin-Etsu Chemical Co., Ltd., represented by the following formula: (Me.sub.3SiO.sub.1/2).sub.30(SiO.sub.4/2).sub.45(O.sub.1/2R).sub.6, wherein the organopolysiloxane is a mixture of the compound wherein R is, independently of each other, H or iPr.

(6) (A-4) a branched organopolysiloxane, ex Shin-Etsu Chemical Co., Ltd., represented by the following formula: (Me.sub.3SiO.sub.1/2).sub.180(SiO.sub.4/2).sub.60, wherein the organopolysiloxane is a mixture of the compound wherein R is, independently of each other, H or Et.

(7) (A-5) a branched organopolysiloxane, ex Shin-Etsu Chemical Co., Ltd., represented by the following formula: (Me.sub.3SiO.sub.1/2).sub.30(Me.sub.2SiO.sub.2/2).sub.30(MeSiO.sub.3/2).sub.190(O.sub.1/2R).sub.50, wherein the organopolysiloxane is a mixture of the compound wherein R is, independently of each other, H or Me.

(B) Linear Organopolysiloxane

(8) (B-1) a linear organopolysiloxane, ex Shin-Etsu Chemical Co., Ltd., represented by the following formula: HO.sub.1/2(PhMeSio.sub.2/2).sub.30O.sub.1/2H

(9) (B-2) a linear organopolysiloxane, ex Shin-Etsu Chemical Co., Ltd., represented by the following formula: RO.sub.1/2-(Me.sub.2SiO.sub.2/2).sub.300O.sub.1/2R, wherein the organopolysiloxane is a mixture of the compound wherein R is, independently of each other, H or Me.

(10) (B-3) a linear organopolysiloxane, ex Shin-Etsu Chemical Co., Ltd., represented by the following formula: RO.sub.1/2-(Me.sub.2SiO.sub.2/2).sub.1980O.sub.1/2R wherein the organopolysiloxane is a mixture of the compound wherein R is, independently of each other, H or Me.

(11) (B-4) a linear organopolysiloxane, ex Shin-Etsu Chemical Co., Ltd., represented by the following formula:

(12) (RO) 3SiO.sub.1/2-(Me.sub.2SiO.sub.2/2).sub.200O.sub.1/2Si(OR).sub.3 wherein R is Me.

(C) Silazane Compound

(13) (C-1) Hexamethylcyclotrisilazane, ex Shin-Etsu Chemical Co., Ltd.:

(14) ##STR00007##

(15) (C-2) Trimethyltriphenylcyclotrisilazane, ex Shin-Etsu Chemical Co., Ltd.:

(16) ##STR00008##

(17) (C-3) Tris(trimethylsilyl)amine, ex Shin-Etsu Chemical Co., Ltd.:

(18) ##STR00009##

(19) (C-4) Bis(trimethylsilyl)amine, ex Shin-Etsu Chemical Co., Ltd.:

(20) ##STR00010##

(21) (C-5) Inorganic polysilazane consisting of the following units, ex Shin-Etsu Chemical Co., Ltd.:

(22) ##STR00011##

(23) wherein f is 180, g is 124 and h is 31. The bonding order of the parenthesized silazane units in the organopolysiloxane may form a block unit or bond randomly.

(24) (C-6) Organic polysilazane consisting of the following units, ex Shin-Etsu Chemical Co., Ltd.:

(25) ##STR00012##
wherein f is 40, g is 15 and h is 3. The bonding order of the parenthesized silazane units in the organopolysiloxane may form a block unit or bond randomly.
(C) Condensation catalyst for comparative examples

(26) (C-1) Heptylamine, ex Tokyo Chemical Industry Co., Ltd.

(27) (C-2) Orgatics TC-750, containing 11.2 mass % of Ti, ex Matsumoto Fine Chemical Co. Ltd.

(28) [Examples 1 to 6 and Comparative Examples 1 to 2]

(29) Components (A) and (B) were mixed in amounts as described in Table 1, to which component (C) or (C) was then added and further mixed to prepare a condensation-curable silicone resin composition. The condensation-curable silicone resin compositions prepared in the Examples and the Comparative Examples were evaluated according to the following manners.

(1) Viscosity of the Condensation-Curable Silicone Resin Composition

(30) An initial viscosity of the condensation-curable silicone resin composition was determined with a B-type viscometer at 23 degrees C. according to the Japanese Industrial Standards (JIS), Z 8803:2011. The composition was left in the atmosphere at 23 degrees C. for 4 hours and, a the viscosity was determined. A ratio of the viscosities was calculated according to the following equation: Ratio=[Viscosity after 4 hours]/[Initial viscosity]. The results are as shown in Table 2.

(2) Curing Time

(31) The curing time was determined according to JIS K 6910:2007. That is, approximately 0.5 g of the condensation-curable silicone resin composition was put on a hot plate heated at 150 degrees C. and, immediately, a stopwatch was started. Immediately after the composition were put on the hot plate, the composition was quickly spread uniformly into an area of approximately 4 cm7.5 cm with an edge of a metal spatula having a length of approximately 10 cm and a width of approximately 1.25 cm, then, the spatula was moved back and forth while applying a mild pressure to the composition. One round of the back-and-forth motion took 3 seconds. The back-and-forth motion was continued until the composition did not show gooey string. This was an end point. The time until the end point was recorded as a curing time. The determination of the curing time was conducted three times. The average curing time is as shown in Table 2.

(3) Hardness of a Cured Product

(32) The condensation-curable silicone resin composition was poured into an aluminum-made petri dish having a diameter of 50 mm and a depth of 10 mm and, then, heated at 60 degrees C. for one hour, 100 degrees C. for one hour and, subsequently, 150 degrees C. for 4 hours to obtain a cured product. A hardness of the cured product was determined with a durometer of type A according to the JIS K 6253-3:2012. The results are as shown in Table 2.

(4) Light Transmittance of a Cured Product

(33) A concave Teflon (trademark) spacer having a thickness of 1 mm was sandwiched by two glass slides having dimensions of 50 mm20 mm1 mm and tightly held. The condensation-curable silicone resin composition was poured into the Teflon spacer and cured stepwise at 60 degrees C. for one hour, 100 degrees C. for one hour and, subsequently, 150 degrees C. for 8 hours to obtain a cured product. A transmittance of the cured product at 450 nm was determined with a spectrophotometer, 0-4100, ex Hitachi High-Technologies Corporation. The results are as shown in Table 2.

(5) Heat Resistance

(34) The cured product prepared as in the aforesaid light transmittance test procedure was left in the atmosphere at 200 degrees C. for 1,000 hours. A transmittance of the cured product at 450 nm was determined with a spectrophotometer, 0-4100, ex Hitachi High-Technologies Corporation. The results are as shown in Table 2.

(6) Tensile Strength and an Elongation at Break of a Cured Product

(35) The silicone resin composition was poured into a Teflon (trademark) mold having a cavity of 150 mm200 mm2 mm, and cured stepwise at 60 degrees C. for one hour, 100 degrees C. for one hour and, subsequently, 150 degrees C. for 8 hours to obtain a cured product. A tensile strength and an elongation at break of the cured product were determined according to JIS K 6251:2010 with a testing apparatus, EZ TEST, EZ-L, ex Shimadzu Corporation, in the following conditions: a tensile speed was 500 mm/min, a distance between clamps was 80 mm, and a distance of gauge points was 40 mm. The results are as shown in Table 2.

(7) Thermal Cycle Test (TCT)

(36) The silicone resin composition was dispensed on a Tiger3528 package, ex Shin-Etsu Chemical Co. Ltd., and cured stepwise at 60 degrees C. for one hour, 100 degrees C. for one hour and, subsequently, 150 degrees C. for 8 hours to cure to obtain a sample package encapsulated with the cured product. The 20 samples were subjected to a thermal cycle test (TCT) with 1000 thermal cycles of 50 to 140 degrees C. and vice-versa. The number of the sample packages which had cracks was recorded. The results are as shown in Table 2.

(37) TABLE-US-00001 TABLE 1 Com. Com. Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 1 Ex. 2 (A) (A-1) 100 100 100 100 (A-2) 100 (A-3) 100 (A-4) 100 (A-5) 100 (B) (B-1) 100 100 100 100 (B-2) 100 300 250 (B-3) 10 100 (B-4) 150 (C) (C-1) 1 (C-2) 2 (C-3) 20 (C-4) 10 (C-5) 10 (C-6) 20 (C) (C-1) 2 Com- (C-2) 0.5 para- tive conden- sation catalyst

(38) TABLE-US-00002 TABLE 2 Com. Com. Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 1 Ex. 2 Evaluation Viscosity 23 degrees C., Pa .Math. s 4.6 4.5 9.2 6.8 8.6 5.8 3.6 3.8 Initial 23 degrees C., Pa .Math. s 4.8 4.6 9.2 7.0 9.2 6.1 gelled 8.0 after 4 hours Ratio of Viscosity 1.04 1.02 1.00 1.03 1.07 1.05 2.11 the after 4 hours/Initial viscosities viscosity Curing time 150 degrees C. min 16 14 18 14 8 10 3 15 Hardness Type A 78 80 45 35 31 51 79 77 Transmittance Initial, % T 99.7 99.8 99.7 99.7 99.6 99.6 99.7 99.6 Thickness of 1 mm, 450 nm Heat 200 degrees C., % T 99.6 99.6 99.4 99.5 99.3 99.4 76.4 91.3 resistance 1000 hr Thickness of 1 mm, 450 nm Tensile 25 degrees C. MPa 2 2.1 1.9 1.6 1.1 3.4 2.2 2 strength Elongation 25 degrees C. % 160 160 140 170 190 110 150 160 at break Thermal 1000 thermal Number 0/20 0/20 0/20 0/20 0/20 0/20 20/20 20/20 cycle test cycles of 50 of the to/from 140 cracked degrees C. samples

(39) As seen in Table 2, Examples 1 to 6, the condensation-curable silicone resin composition which contained the silazane compound as a condensation catalyst cures quickly by heating at 150 degrees C. to provide a colorless and transparent product.

(40) The viscosity of the composition which contained an amine catalyst or a metal catalyst increases at room temperature, as seen in Comparative Examples 1 and 2. In contrast, the ratio of the viscosities at room temperature of the present composition is small. That is, increase of the viscosity is prevented.

(41) Further, as seen in Comparative Examples 1 and 2, the cured product obtained from the composition containing the amine catalyst or the metal catalyst causes cracks in the TCT, and the transmittance of the cured product decreases at 200 degrees C. after 1000 hours. Thus, the heat resistance and the crack resistance of the cured product are poor. In contrast, the cured product obtained from the present composition does not cause cracks in the TCT, and the transmittance of the cured product does not decrease at 200 degrees C. after 1000 hours. Thus, the cured product has excellent heat resistance and crack resistance.

INDUSTRIAL APPLICABILITY

(42) The present condensation-curable silicone resin composition has good handling property and provides a cured product having high reliability such as a heat resistance. Accordingly, a semiconductor element may be encapsulated with the cured product of the present condensation-curable silicone resin composition to thereby provide a semiconductor device having excellent reliability. Further, the present condensation-curable silicone composition provides a cured product having a high light transmittance, so that the present condensation-curable silicone composition is usable as an encapsulating material for LEDs, in particular, blue LEDs and ultraviolet LEDs.