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WO2020043313A1 - Curable organopolysiloxane composition, encapsulant and semiconductor device - Google Patents

Curable organopolysiloxane composition, encapsulant and semiconductor device Download PDF

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Publication number
WO2020043313A1
WO2020043313A1 PCT/EP2018/073487 EP2018073487W WO2020043313A1 WO 2020043313 A1 WO2020043313 A1 WO 2020043313A1 EP 2018073487 W EP2018073487 W EP 2018073487W WO 2020043313 A1 WO2020043313 A1 WO 2020043313A1
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WIPO (PCT)
Prior art keywords
group
component
weight
curable organopolysiloxane
organopolysiloxane composition
Prior art date
Application number
PCT/EP2018/073487
Other languages
French (fr)
Inventor
Youngjin Kim
Minwoong Kim
Arvid Kuhn
GyeongHui LEE
HyunKwan Yang
Original Assignee
Wacker Chemie Ag
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Publication date
Application filed by Wacker Chemie Ag filed Critical Wacker Chemie Ag
Priority to PCT/EP2018/073487 priority Critical patent/WO2020043313A1/en
Priority to TW108128941A priority patent/TW202010794A/en
Publication of WO2020043313A1 publication Critical patent/WO2020043313A1/en

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D183/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers
    • C09D183/04—Polysiloxanes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
    • C08G77/04—Polysiloxanes
    • C08G77/12—Polysiloxanes containing silicon bound to hydrogen
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
    • C08G77/04—Polysiloxanes
    • C08G77/20—Polysiloxanes containing silicon bound to unsaturated aliphatic groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
    • C08G77/04—Polysiloxanes
    • C08G77/38—Polysiloxanes modified by chemical after-treatment
    • C08G77/382—Polysiloxanes modified by chemical after-treatment containing atoms other than carbon, hydrogen, oxygen or silicon
    • C08G77/398—Polysiloxanes modified by chemical after-treatment containing atoms other than carbon, hydrogen, oxygen or silicon containing boron or metal atoms
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
    • C08L83/04—Polysiloxanes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
    • C08L83/04—Polysiloxanes
    • C08L83/08—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D183/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers
    • C09D183/04—Polysiloxanes
    • C09D183/06—Polysiloxanes containing silicon bound to oxygen-containing groups
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D183/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers
    • C09D183/04—Polysiloxanes
    • C09D183/08—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen, and oxygen
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/52—Encapsulations
    • H01L33/56—Materials, e.g. epoxy or silicone resin

Definitions

  • the present invention relates to a curable organopolysiloxane composition, an
  • the present invention relates to a curable organopolysiloxane composition with excellent thermal resistance and crack resistance, an LED encapsulant with excellent reliability using the same, and a semiconductor device.
  • a LED package is generally composed of a chip, an adhesive, an encapsulant, a phosphor, and a heat radiation material.
  • the encapsulant basically serves to protect a LED device, and allows light to pass through the LED device and emit light outside the device.
  • curable silicone compositions and curable epoxy compositions have been used.
  • the silicone compositions curable by the hydrosilylation reaction which gives optically clear silicone products, have been mainly used for good properties such as resistance to heat, moisture, and light.
  • An object of the present invention is to provide a curable organopolysiloxane composition with excellent thermal resistance and excellent crack resistance to thermal aging, an LED encapsulant with excellent reliability using the same, and a semiconductor device.
  • the present invention provides a curable organopolysiloxane composition including:
  • (C) a linear organopolysiloxane with both terminal ends of the molecular chain blocked by silicon-bonded hydrogen atoms, having at least one silicon-bonded aryl group per molecule;
  • each R 8 can be the same or different and is independently selected from a substituted or unsubstituted monovalent hydrocarbon group, in which at least one of R 8 per molecule is an alkenyl group, with the proviso that the ratio between alkenyl groups and silicon atoms is from 0.3 to 1 , f, g, h, and i are independently 0 or a positive number,
  • the weight average molecular weight Mw of the siloxane is 1,000 g/mol or less).
  • the present invention provides an LED encapsulant including the above-described curable organopolysiloxane composition.
  • the present invention provides a semiconductor device including a semiconductor element coated with a cured product of the above-described curable organopolysiloxane composition.
  • the composition according to the present invention shows less change in weight and hardness at high temperature and thus may be cured as a cured product with excellent thermal stability. Therefore, the present invention may provide an LED silicon encapsulant which is stable against light generated from LED chips and heat generated during the operation. Furthermore, the present invention has high hardness and flexibility at high temperature and thus may improve the reliability of the LED.
  • Fig, 1 is a photograph illustrating whether cracks occur on LED encapsulants of Example 1 and Comparative Example 1.
  • Fig. 2 is a photograph illustrating whether cracks occur on a cured product of Example 1 and Comparative Example 1 in an aluminum pan.
  • Figs. 3 and 4 are graphs showing a change in hardness and weight of cured silicone in Example 1 and Comparative Example 1 at 200°C. Detailed Description of the Invention
  • the present invention is a curable organopolysiloxane composition, including: (A) a cerium (Ce)-containing branched organopolysiloxane; (B) a branched organopolysiloxane; (C) a linear organopolysiloxane with both terminal ends of the molecular chain blocked by silicon-bonded hydrogen atoms, having at least one silicon- bonded aryl group per molecule; (D) a hydrosilylation reaction catalyst; and (E) a low molecular weight siloxane having at least one silicon-bonded alkenyl group per molecule, represented by the average formula,
  • the cerium (Ce)- containing branched organopolysiloxane (hereinafter,‘component (A)’) imparts thermal stability while imparting strength to a silicone cured product obtained by curing the composition.
  • component (A) is a kind of branched organopolysiloxane
  • the present invention may obtain a silicone cured product with excellent strength as compared to a composition including a linear organopolysiloxane.
  • cerium is not a separate single material, but is contained in the form of cerium ions in the branched organopolysiloxane, so that cerium is stably dispersed in the composition without being precipitated or sedimentation. Further, since cerium takes part in a reaction when the composition is cured, cerium is stably included as one component of the silicone cured product after the curing.
  • the cerium (Ce)-containing branched organopolysiloxane when the cerium (Ce)-containing branched organopolysiloxane is prepared, the content of cerium may be easily controlled according to the content of silanol groups in an alkali metal salt of a silanol group-containing branched organopolysiloxane. Accordingly, since a silicone cured product obtained by curing the composition of the present invention shows less change in weight loss and hardness, the occurrence of cracks due to the thermal aging is minimized or suppressed, and accordingly, when the silicone cured product is applied to an encapsulant of an LED, reliability of the LED may be improved.
  • the content of cerium is not particularly limited, and may be, for example, 0.1 to 2 % by weight based on the total weight of the curable organopolysiloxane composition. If the content of cerium in component (A) is less than 0.1 % by weight, the effect may be insignificant, and while, if the content of cerium in component (A) exceeds 2 % by weight, the value of b* of the cured product becomes 2 or more, and as a result, it is difficult to use the composition of the present invention as an LED encapsulant.
  • the content of cerium in component (A) may be about 5 to 300 ppm as a mass unit based on the total weight of the curable organopolysiloxane composition.
  • the silicone cured product according to the present invention has excellent thermal stability, and a change in light emission color may be minimized when the silicone cured product is used in an optical semiconductor device.
  • This component (A) is a material obtained by reacting an alkali metal salt of a silanol group-containing branched organopolysiloxane with cerium chloride or cerium salt of carboxylic acid.
  • the mixing ratio of an alkali metal salt of the silanol group- containing branched organopolysiloxane to cerium chloride (or cerium salt of carboxylic acid) is not particularly limited, and may be, for example, a molar ratio of 0.1 to 2 : 1.
  • cerium salts of carboxylic acid which may be used in the present invention include cerium 2-ethylhexanoate, cerium naphthenate, cerium oleate, cerium laurate, cerium stearate, and the like, but are not limited thereto. These cerium salts may be used either alone or in a mixture of two or more thereof.
  • alkali metal salts of the silanol group-containing branched organopolysiloxane which may be used in the present invention include sodium salt of the silanol group-containing branched organopolysiloxane, potassium salt of the silanol group-containing branched organopolysiloxane, and the like, but are not limited thereto.
  • the alkali metal salt of the silanol group-containing branched organopolysiloxane may be an alkali metal salt of a branched organopolysiloxane having at least one silanol group, at least one silicon-bonded alkenyl group, and at least one silicon-bonded aryl group per molecule, and having siloxane units represented by the following general formula 1 :
  • R is a substituted or unsubstituted monovalent hydrocarbon group.
  • the alkenyl groups have 2 to 12 carbon atoms, examples thereof include vinyl, allyl, methallyl, butenyl, pentenyl, and hexenyl group, specific examples thereof include vinyl, and allyl group, and more specific examples thereof include vinyl group.
  • aryl groups have 6 to 20 carbon atoms, examples thereof include phenyl, naphthyl, anthryl, phenanthryl, indenyl, benzophenyl, fluorenyl, xanthenyl, and anthronyl; aryloxyaryl groups such as o-phenoxyphenyl and p-phenoxyphenyl; alkaryl groups such as o-tolyl, m-tolyl, p-tolyl, xylyl, and ethylphenyl; and aralkyl groups such as benzyl, a-phenylethyl, and b-phenylethyl, and specific examples thereof include phenyl group.
  • examples of the silicon-bonded organic groups in the silanol group-containing branched organopolysiloxane include substituted or unsubstituted Ci to C 2 o monovalent hydrocarbon groups, specific examples thereof include Ci to C 20 alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl; and Ci to C 20 halogenated alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl, and more specific examples thereof include methyl groups.
  • the monovalent hydrocarbon groups may be unsubstituted or substituted with one or more substituents selected from the group consisting of Ci to C20 alkyl groups, C 2 to C20 alkenyl group, Ce to C 20 aryl groups, C 7 to C 2 o aralkyl groups, and Ci to C 20 halogenated alkyl groups.
  • R is Ci to C20 monovalent hydrocarbon groups.
  • the Ci to C 2 o monovalent hydrocarbon groups include Ci to C 20 alkyl groups, C 2 to C 2 o alkenyl group, Ce to C 2 o aryl groups, C 7 to C 20 aralkyl groups, and Ci to C20 halogenated alkyl groups.
  • the Ci to C 20 monovalent hydrocarbon groups may be unsubstituted or substituted with one or more substituents selected from the group consisting of Ci to C 20 alkyl groups, C 2 to C 20 alkenyl groups, C 6 to C20 aryl groups, C 7 to C 20 aralkyl groups, and Ci to C 2 o halogenated alkyl groups, and specifically, may be unsubstituted or substituted with one or more substituents selected from the group consisting of C to C 20 alkyl groups and Ce to C 20 aryl groups.
  • the alkali metal salt of the silanol group- containing branched organopolysiloxane may be an alkali metal salt of an organopolysiloxane represented by the following average unit formula 1.
  • each of R 1 , R 2 , and R 3 can be the same or different and is independently selected from a substituted or unsubstituted monovalent hydrocarbon group,
  • At least one of R 1 , R 2 , and R 3 per molecule is a C 2 to C 12 alkenyl group, and at least one of R 1 , R 2 , and R 3 per molecule is a C 6 to C 20 aryl group.
  • the monovalent hydrocarbon groups have 1 to 20 carbon atoms, and examples thereof include the above-described Ci to C20 alkyl groups, the above-described C2 to C20 alkenyl group, the above-described CV, to C20 aryl groups, the above-described C7 to C20 aralkyl groups, and the above-described Ci to C20 halogenated alkyl groups.
  • the content of the silanol groups per molecule is not particularly limited, but may be, for example, 1 to 3 mol% of R 1 , R 2 , and R 3 per molecule. If the content of the silanol groups per molecule in the alkali metal salt of the silanol group-containing branched organopolysiloxane is within the above-described range, thermal stability of the cured product may be improved.
  • the content of the alkenyl groups per molecule is not particularly limited, but may be, for example, 0.1 to 40 mol%, specifically 5 to 25 mol%, of R 1 , R 2 , and R 3 per molecule. If the content of the alkenyl groups per molecule in the alkali metal salt of the silanol group-containing branched organopolysiloxane is within the above-described range, the reactivity of component (A) may be improved.
  • the content of the aryl groups per molecule is not particularly limited, but may be, for example, 10 mol% or more of R 1 , R 2 , and R 3 per molecule. If the content of the aryl groups per molecule in the alkali metal salt of the silanol group- containing branched organopolysiloxane is within the above-described range, it is possible to minimize attenuation due to light refraction, reflection, scattering, etc. in the cured product obtained by curing.
  • R 2 Si0 3/2 it is even more preferable that not less than 30 mol % of R 2 should be represented by the above-mentioned aryl groups, with R 2 other than the alkenyl and aryl groups being preferably represented by methyl groups.
  • X 1 is a hydrogen atom or Ci to C 2 o alkyl group
  • a is 0 or a positive number
  • b is 0 or a positive number
  • c is a positive number
  • d is 0 or a positive number
  • e is 0 or a positive number
  • b/c is a number between 0 and 10
  • a/c is a number between 0 and 0.5
  • d/(a+b+c+d) is a number between 0 and 0.3
  • e/(a+b+c+d) is a number between 0 and 0.4.
  • the alkali metal salt of the silanol group- containing branched organopolysiloxane may be an alkali metal salt of an organopolysiloxane represented by the following average unit formula 2.
  • R 1 is a Ci to C12 alkyl group
  • R 2 is a C 6 to C20 aryl group or a C7 to C 2 o aralkyl group
  • R 3 is a C 2 to C12 alkenyl group
  • a 0 or a positive number
  • b is 0 or a positive number
  • R 1 , R 2 , and R 3 per molecule is a silanol group.
  • the content of the silanol groups in the alkali metal salt of the above-described silanol group-containing branched organopolysiloxane is not particularly limited, and may be, for example, 1 to 3 mol% per molecule. If the content of the silanol groups in the alkali metal salt of the silanol group-containing branched organopolysiloxane is within the above-described range, thermal stability of the cured product may be improved.
  • the weight average molecular weight of the cerium-containing branched organopolysiloxane is not particularly limited, and may be, for example, about 1,000 to 3,000 g/mol, specifically about 1,500 to 2,500 g/mol.
  • component (A) is not particularly limited, but may be, for example, about 0.01 to 5 parts by weight, based on 100 parts by weight of the composition.
  • component (B) is not particularly limited, but may be, for example, about 0.01 to 5 parts by weight, based on 100 parts by weight of the composition.
  • the branched organopolysiloxane (hereinafter,‘component (B)’) imparts strength to a silicone cured product obtained by curing the composition.
  • Component (B) represents a branched organopolysiloxane having at least one silicon-bonded alkenyl group and at least one silicon-bonded aryl group per molecule, and having siloxane units represented by the general formula 2:
  • R is a substituted or unsubstituted monovalent hydrocarbon group having
  • the alkenyl groups have 1 to 20 carbon atoms.
  • the Cl to C20 alkenyl groups include vinyl, allyl, methallyl, butenyl, pentenyl, and hexenyl group, preferably vinyl and allyl group, particularly preferred vinyl group.
  • the aryl groups have 6 to 20 carbon atoms. Examples of the
  • C6 to C20 aryl groups include phenyl, naphthyl, anthryl, phenanthryl, indenyl, benzophenyl, fluorenyl, xanthenyl, anthronyl; aryloxyaryl groups such as o- or p-phen- oxyphenyl; alkaryl groups such as 0-, m-, p-tolyl, xylyl and ethylphenyl; aralkyl groups such as benzyl, a- and b-phenylethyl.
  • the aryl group is phenyl group.
  • examples of silicon-bonded organic groups of component (B) other than the alkenyl and aryl groups include substituted or unsubstituted monovalent hydrocarbon groups having 1 to 20 carbon atoms, examples of which include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, and other alkyl groups; and halogenated alkyl groups having 1 to 20 carbon atoms such as chloromethyl, 3-chloropropyl, and 3,3,3- trifluoropropyl, with methyl being particularly preferable.
  • R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms.
  • Substituents of hydrocarbon groups may include the above-mentioned Cl to C20 alkyl groups, the above-mentioned C2 to C20 alkenyl groups, the above- mentioned C6 to C20 aryl groups, the above-mentioned C7 to C20 aralkyl groups, and the above-mentioned Cl to C20 halogenated alkyl groups, particularly preferably the above-mentioned Cl to C20 alkyl groups and the above-mentioned C6 to C20 aryl groups.
  • each of R 4 , R 5 , and R 6 can be the same or different and is independently selected from a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, wherein at least one of R 4 , R 5 or R 6 per molecule is an C2 to C12 alkenyl group and at least one of R 4 , R 5 or R 6 per molecule is an C6 to C20 aryl group.
  • the monovalent hydrocarbon group having 1 to 20 carbon atoms may be more specifically exemplified by the above-mentioned Cl to C20 alkyl groups, the above- mentioned C2 to C20 alkenyl groups, the above-mentioned C6 to C20 aryl groups, the above-mentioned C7 to C20 aralkyl groups, and the above-mentioned Cl to C20 halogenated alkyl groups.
  • Preferably 0.1 to 40 mol%, more preferably 5 to 25 mol%, of R 4 , R 5 , and R 6 per molecule is the above-mentioned C2 to C12 alkenyl groups. This is due to the fact that when the content of the alkenyl groups is below the lower limit or exceeds the upper limit of the above-mentioned range, its reactivity with component (B) tends to decrease.
  • R 5 , and R 6 should be the above-mentioned C6 to C20 aryl groups, and, in particular, in siloxane units represented by the general formula R 5 Si0 3/2 , it is even more preferable that not less than 30 mol % of R 5 should be represented by the above- mentioned aryl groups, with R 5 other than the alkenyl and aryl groups being preferably represented by methyl groups.
  • X 2 is a hydrogen atom or Cl to C20 alkyl group, a is 0 or a positive number, b is 0 or a positive number, c is a positive number, d is 0 or a positive number, e is 0 or a positive number, b/c is a number between 0 and 10, a/c is a number between 0 and 0.5, d/(a+b+c+d) is a number between 0 and 0.3, and e/(a+b+c+d) is a number between 0 and 0.4.
  • R 4 is a Ci to C12 alkyl group
  • R 5 is a C 6 to C20 aryl group or a C7 to C20 aralkyl group
  • R 6 is a C 2 to C12 alkenyl group
  • a is 0 or a positive number
  • b is 0 or a positive number
  • c is a positive number.
  • component (B) when converted to standard polystyrene, its weight average molecular weight (Mw) should preferably be in the range of from 500 g/mol to 10,000 g/mol, and, especially preferably, in the range of from 700 g/mol to 7,000 g/mol, more preferably in the range from 1,000 g/mol to 5,000 g/mol, particularly from 1,500 to 3,000 g/mol.
  • the content of component (B) is not particularly limited, but may be, for example, about 60 to 85 parts by weight based on 100 parts by weight of the composition. According to one example, the content of component (B) may be about 54 to 80 % by weight, based on the sum of the amounts of components (A), (B), and (C).
  • Component tC) is not particularly limited, but may be, for example, about 60 to 85 parts by weight based on 100 parts by weight of the composition. According to one example, the content of component (B) may be about 54 to 80 % by weight, based on the sum of the amounts of components (A), (B), and (C).
  • Component (C) is the curing agent of the present composition.
  • Component (C) is a linear organopolysiloxane with both terminal ends of the molecular chain blocked by silicon-bonded hydrogen atoms having at least one silicon- bonded aryl group per molecule.
  • the aryl groups have 6 to 20 carbon atoms.
  • Examples of the C6 to C20 aryl groups of component (C) are the same as those described above. Phenyl group is especially preferable.
  • examples of silicon-bonded organic groups of component (C) other than the aryl groups include substituted or unsubstituted Cl to C20 monovalent hydrocarbon groups with the exception of alkenyl groups, such as the above-described Cl to C20 alkyl groups, the above-described C7 to C20 aralkyl groups, and the above- described Cl to C20 halogenated alkyl groups, with methyl being particularly preferable.
  • component (C) In order to achieve low attenuation due to light refraction, reflection, scattering, etc. in the cured product obtained by curing the content of the silicon-bonded aryl groups among all the silicon-bonded organic groups in component (C) should preferably be not less than 15 mol % and, particularly preferably, not less than 30 mol%. Although there are no limitations concerning the viscosity of component (C) at 25 °C, it is preferably in the range of from 1 to 1,000 mPa-s, and, especially preferably, in the range of from 2 to 500 mPa-s.
  • component (C) is preferable as component (C).
  • each R 7 can be the same or different and is independently selected from a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group with the exception of alkenyl groups.
  • the monovalent hydrocarbon group has 1 to 20 carbon atoms.
  • Examples of the monovalent hydrocarbon groups of R 7 include the above-mentioned Cl to C20 alkyl groups, the above-mentioned C6 to C20 aryl groups, and the above-mentioned Cl to C20 halogenated alkyl groups.
  • At least one R 7 per molecule must be one of the above-mentioned C6 to C20 aryl groups, preferably, phenyl.
  • n in the formula above is an integer of 0 or more, preferably, an integer in the range of from 0 to 20, and, especially preferably, an integer in the range of from 0 to 10. This is due to the fact that when the value of n exceeds the upper limit of the above-mentioned range, the toughness of the resultant composition, or the adhesive properties of the cured product, tend to deteriorate. It is most preferable that n is 1 to 4, particularly, 1, that is, the component (C) represents trisiloxane.
  • Component (C) is preferably present in an amount of 1 to 30 % by weight, more preferably 10 to 30 % by weight, particularly prefered, 15 to 25 % by weight, based on the sum of the amounts of components (A), (B) and (C).
  • component (C) is not particularyl limited, but may be, for example, about 10 to 30 parts by weight, based on 100 parts by weight of the composition.
  • Component ( ⁇ B) is not particularyl limited, but may be, for example, about 10 to 30 parts by weight, based on 100 parts by weight of the composition.
  • Component (D) is a hydrosilylation reaction catalyst.
  • the hydrosilylation reaction catalyst of component (D) is used to promote the reaction of the alkenyl groups of component (B) with the silicon-bonded hydrogen atoms of component (A),
  • component (D) examples include platinum catalysts, rhodium catalysts, and palladium catalysts. Platinum catalysts are preferable because of their ability to significantly stimulate the cure of the present composition. Examples of the platinum catalysts include platinum micropowder, chloroplatinic acid, alcohol solutions of chloroplatinic acid, platinum/alkenylsiloxane complexes, platinum/olefin complexes, and platinum/carbonyl complexes, preferably, platinum/alkenylsiloxane complexes.
  • alkenylsiloxanes examples include l,3-divinyl-l,l,3,3-tetramethyldisiloxane, l,3,5,7-tetramethyl-l,3,5,7-tetravinylcyclotetrasiloxane, alkenylsiloxanes obtained by substituting groups such as ethyl, phenyl etc. for some of the methyl groups of the above-mentioned alkenylsiloxanes, and alkenylsiloxanes obtained by substituting groups such as allyl, hexenyl, etc. for the vinyl groups of the above-mentioned alkenylsiloxanes.
  • l,3-divinyl-l,l,3,3-tetramethyldisiloxane is particularly preferable because of the excellent stability of the platinum/alkenylsiloxane complex. Also, due to the improvement in the stability of the complex that their addition may bring, it is desirable to add l,3-divinyl-l, l,3,3-tetramethyldisiloxane, 1,3-diallyl-l, 1,3,3- tetramethyldisiloxane, 1,3-divinyl-l, 3-dimethyl- l,3-dlphenyldisiloxane, l,3-divinyl- 1, 1,3,3-tetraphenyldisiloxane, l,3,5,7-tetramethyl-l,3,5,7-tetravinylcyclotetrasiloxane and other alkenylsiloxanes and organosiloxane oligomers such as dimethylsiloxane
  • component (D) there are no limitations on the content of component (D) as long as the amount promotes curing of the present composition.
  • the content of component (D) may be about 0.001 to 0.3 parts by weight, based on 100 parts by weight of the composition.
  • component (D) is preferably present in an amount resulting in a platinum content of 0.05 to 100 ppm (parts per million) by weight, more preferably 0.1 to 10 ppm by weight, particularly preferred 0.1 to 5 ppm by weight, relative to 100 parts by weight of the total of components (A), (B) and (C).
  • component (E) is below the lower limit of the above-mentioned range, the present composition tends to fail to completely cure, and, on the other hand, when it exceeds the upper limit of the above-mentioned range, problems may arise in terms imparting various colors to the resultant cured product.
  • Component (E) is below the lower limit of the above-mentioned range, the present composition tends to fail to completely cure, and, on the other hand, when it exceeds the upper limit of the above-mentioned range, problems may arise in terms imparting various colors to the resultant cured product.
  • Component (E) is an additive, which is a low molecular weight siloxane having at least one silicon-bonded alkenyl group per molecule, represented by the average formula 1 :
  • each R 8 can be the same or different and is independently selected from a substituted or unsubstituted monovalent hydrocarbon group, wherein at least one of R 8 per molecule is an alkenyl group, with the proviso that the ratio between alkenyl groups and silicon atoms is from 0.3 to 1, f, g, h, and i are independently 0 or positive, wherein f+g+h+i is 1, and the weight average molecular weight Mw of the siloxane is less than 1 ,000 g/mol, preferably less than 800 g/mol, more preferably less than 500 g/mol.
  • component (E) is selected from the group consisting of D alkenyI 4 , M alkenyl 4Q, M alkenyl 6Q 2, M alkenyl 3T.
  • Particularly preferred as component (E) are cyclotetrasiloxane D vi 4 , and M vi 4 Q, especially D Vl 4.
  • D unit is R 5 2 Si0 2/3 ⁇ 4
  • M unit is R 5 3SiOi / 2
  • Q unit is Si0 4/2
  • T unit is R 5 SiC>3 /2 .
  • component (E) serves to react with an unreacted site (Si-H), thereby protecting additional reaction of the unreacted site due to heat or light.
  • color change and mechanical strength change to high temperature may be remarkably reduced.
  • composition according to prior art which has no component (E)
  • materials often show an increase in hardness after curing during storage at high temperature, which can be attributed to a post-curing reaction of remaining reactive sites and/or show a weight loss by evaporation of low molecular weight species that did not crosslink into the polymer network. Due to the change in hardness and weight loss, the materials were not stable under operating conditions.
  • a reaction of component (E) with unreacted site (Si-H) leads to better stability such as less change in hardness, low weight loss, and discoloration, at high temperature.
  • Component (E) also gives a filling effect, which makes it possible to lower gas and vapor transmission.
  • the encapsulant further comprising component (E) provides stablity to sulfur and such effect is expected to be obtained from the filing effect.
  • Component (E) is both reactive and small enough to react with residual silicone hydride. At the same time, component (E) crosslinks into the siloxane network and thus does not increase the proportion of volatile components in the cured material.
  • Component (E) is preferably used in an amount of at most 10 parts by weight, more preferably at most 7 parts by weight, and even more preferably at most 5 parts by weight relative to 100 parts by weight of the total of components (A), (B) and (C). If component (E) is included in higher amounts, compatibility with the other components would be lower and thus, transmittance would be lower.
  • component (E) is used in an amount of at least 1 parts by weight relative to 100 parts by weight of the total of components (A), (B) and (C). The amount of the component (E) may be adequately selected in consideration of the specific formulation and the feature.
  • the composition of the present invention comprises about 0.5 to 10 parts by weight of component (E), based on 100 parts by weight of the composition.
  • the curable silicone composition of the present invention may not comprise as flexibilizing units, a linear organopolysiloxane having at least two silicon-bonded alkenyl groups and at least one silicon-bonded aryl group per molecule. It is assumed that since bulky branched organopolysiloxane such as component (B) is used as resin instead of a linear organopolysiloxane, the present curable silicone composition provides excellent hardness and toughness. That is, bulky branched organopolysiloxane is directly connected to unreacted Si-H site.
  • the curable organopolysiloxane composition of the present invention may further comprise a crosslinking agent, which is generally used in this field.
  • the curable organopolysiloxane composition of the present invention may further comprise a curing inhibitor, a catalyst, and a phosphor, which are generally used in this field.
  • the present composition may also contain silica, glass, quartz, cristobalit, alumina, zinc oxide and other inorganic fillers; micropowders of organic resins such as polymethacrylate resin; heat-stabilizers, dyes, pigments, flame retardants, solvents, etc. as optional components, so long as this does not impair the purpose of this invention.
  • organic resins such as polymethacrylate resin
  • heat-stabilizers, dyes, pigments, flame retardants, solvents, etc. as optional components, so long as this does not impair the purpose of this invention.
  • compositions described above may be prepared by mixing the components generally used in this art, for example, by mixing all the components at ambient temperature.
  • An LED encapsulant of the present invention comprises the curable organopolysiloxane composition as described above.
  • Encapsulation for light emitting devices in the present invention is well known to the art and may be used in the present invention. For example, casting, dispensing, molding may be used.
  • semiconductor elements are coated with a cured product of the curable organopolysiloxane composition as described above.
  • Such semiconductor elements are exemplified by semiconductor elements used in diodes, transistors, thyristors, solid-state image pickup elements, monolithic ICs and in hydride ICs, In particular, it is preferable that semiconductor elements are light- emitting elements.
  • Examples of such semiconductor devices included diodes, light-emitting diodes, transistors, thyristors, photocouplers, CCDs, monolithic IICs, hybrid ICs, LSIs, and
  • Viscosity data is measured with a rheometer model MCR302 manufactured by the company Anton Paar, D-Ostfildern, according to DIN EN ISO 3219 in rotation with a cone-plate measurement system. Measurements were performed in a range where the samples behavior is newtonian. Viscosity data are given for a temperature of 25 °C and an ambient pressure of 1013 mbar,
  • Molecular weight is determined as weight average molecular weight Mw and number average molecular Mn by Size Exclusion Chromatography SEC. Polystyrene is used as standard. The detector is a RI detector. THF is used as solvent. Sample concentration is 5 mg / mL.
  • phenyl triethoxy silane, dimethyl dimethoxy silane, and divinyl tetramethyl disiloxane as monomers were introduced into a glass reactor at a molar ratio of 7 : 1 : 1, water was introduced thereinto in an amount of 1 part by weight relative to the content of the phenyl triethoxy silane, and then hydrochloric acid (HC1) as a catalyst was introduced thereinto in an amount of 0.0009 part by weight relative to the content of the water.
  • HC1 hydrochloric acid
  • a solution containing a branched organopolysiloxane was obtained by removing the aqueous layer of the solution cooled to room temperature, and introducing toluene thereinto in an amount of 1 part by weight relative to the content of the phenyl triethoxy silane used above.
  • the solvent was removed from the solution containing the branched organopolysiloxane obtained above under vacuum, and 29 Si NMR of the remaining solid content (the branched organopolysiloxane) was (Me 2 ViSiOi / 2): 20%, (Me 2 Si0 2/2 ): 10%, (PhSi0 3/2 ): 70%.
  • cerium ethylhexanoate was introduced in an amount of 0,057 part by weight relative to the estimated content of the branched organopolysiloxane compound, and then the mixture was allowed to react while being stirred at 50°C for 2 hours.
  • Example 1 For the compositions in Example 1 and Comparative Example 1, it was determined whether cracks occurred. Specimens of LED packages and specimens of cured silicone each contained in an aluminum pan were prepared, and then it was observed whether cracks occurred on the specimens at the time of quenching the specimens from 250°C to room temperature (about 22.5°C) at an interval of 4 hours. The results each are shown in Figs. 1 and 2.
  • the composition according to example 1 shows almost no change of hardness and weight at 200 °C, whereas the composition according to comparative example 1 shows increase of hardness and weight.

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Abstract

Disclosed is a curable organopolysiloxane composition, a Light Emitting Diode (LED) encapsulant and a semiconductor device.

Description

CURABLE ORGANOPOLYSILOXANE COMPOSITION, ENCAPSULANT
AND SEMICONDUCTOR DEVICE
Technical Field
The present invention relates to a curable organopolysiloxane composition, an
LED encapsulant, and a semiconductor device, and more particularly, the present invention relates to a curable organopolysiloxane composition with excellent thermal resistance and crack resistance, an LED encapsulant with excellent reliability using the same, and a semiconductor device.
Background Art
A LED package is generally composed of a chip, an adhesive, an encapsulant, a phosphor, and a heat radiation material. Among them, the encapsulant basically serves to protect a LED device, and allows light to pass through the LED device and emit light outside the device.
As a basic material for the LED encapsulant, curable silicone compositions and curable epoxy compositions have been used. Particularly, the silicone compositions curable by the hydrosilylation reaction, which gives optically clear silicone products, have been mainly used for good properties such as resistance to heat, moisture, and light.
Recently, as high power output has been demanded in the field of LED such high power output of LED’s has caused problems with LED package materials due to their lack of thermal resistance. Further, when heat is continuously added to the LED package, the material in the LED encapsulant is additionally subjected to a curing reaction, so that the hardness of the LED encapsulant may be changed, or the weight loss of the LED encapsulant may occur. And thus, cracks may occur on the LED encapsulant.
Disclosure of Invention
An object of the present invention is to provide a curable organopolysiloxane composition with excellent thermal resistance and excellent crack resistance to thermal aging, an LED encapsulant with excellent reliability using the same, and a semiconductor device.
The present invention provides a curable organopolysiloxane composition including:
(A) a cerium (Ce)-containing branched organopolysiloxane;
(B) a branched organopolysiloxane;
(C) a linear organopolysiloxane with both terminal ends of the molecular chain blocked by silicon-bonded hydrogen atoms, having at least one silicon-bonded aryl group per molecule;
(D) a hydrosilylation reaction catalyst; and
(E) a low molecular weight siloxane having at least one silicon-bonded alkenyl group per molecule, represented by the following average formula:
[average formula]
(R8 3Si0l/2)f(R82Si02/2)g(R8Si03/2)h(Si04/2)i
(where each R8 can be the same or different and is independently selected from a substituted or unsubstituted monovalent hydrocarbon group, in which at least one of R8 per molecule is an alkenyl group, with the proviso that the ratio between alkenyl groups and silicon atoms is from 0.3 to 1 , f, g, h, and i are independently 0 or a positive number,
in which f+g+h+i is 1, and
the weight average molecular weight Mw of the siloxane is 1,000 g/mol or less).
Further, the present invention provides an LED encapsulant including the above-described curable organopolysiloxane composition.
In addition, the present invention provides a semiconductor device including a semiconductor element coated with a cured product of the above-described curable organopolysiloxane composition. Effects of Invention
The composition according to the present invention shows less change in weight and hardness at high temperature and thus may be cured as a cured product with excellent thermal stability. Therefore, the present invention may provide an LED silicon encapsulant which is stable against light generated from LED chips and heat generated during the operation. Furthermore, the present invention has high hardness and flexibility at high temperature and thus may improve the reliability of the LED.
Brief Description of the Drawings
Fig, 1 is a photograph illustrating whether cracks occur on LED encapsulants of Example 1 and Comparative Example 1.
Fig. 2 is a photograph illustrating whether cracks occur on a cured product of Example 1 and Comparative Example 1 in an aluminum pan.
Figs. 3 and 4 are graphs showing a change in hardness and weight of cured silicone in Example 1 and Comparative Example 1 at 200°C. Detailed Description of the Invention
Hereinafter, an exemplary embodiment of the present invention will be described in detail. However, the exemplary embodiment of the present invention may be modified in various forms, and the scope of the present invention is not limited to an exemplary embodiment to be described below.
The present invention is a curable organopolysiloxane composition, including: (A) a cerium (Ce)-containing branched organopolysiloxane; (B) a branched organopolysiloxane; (C) a linear organopolysiloxane with both terminal ends of the molecular chain blocked by silicon-bonded hydrogen atoms, having at least one silicon- bonded aryl group per molecule; (D) a hydrosilylation reaction catalyst; and (E) a low molecular weight siloxane having at least one silicon-bonded alkenyl group per molecule, represented by the average formula,
Hereinafter, each component and composition of the curable organopolysiloxane composition will be described.
Component (A)
In the composition according to the present invention, the cerium (Ce)- containing branched organopolysiloxane (hereinafter,‘component (A)’) imparts thermal stability while imparting strength to a silicone cured product obtained by curing the composition.
Specifically, since component (A) is a kind of branched organopolysiloxane, the present invention may obtain a silicone cured product with excellent strength as compared to a composition including a linear organopolysiloxane. Furthermore, in the present invention, cerium is not a separate single material, but is contained in the form of cerium ions in the branched organopolysiloxane, so that cerium is stably dispersed in the composition without being precipitated or sedimentation. Further, since cerium takes part in a reaction when the composition is cured, cerium is stably included as one component of the silicone cured product after the curing. In addition, when the cerium (Ce)-containing branched organopolysiloxane is prepared, the content of cerium may be easily controlled according to the content of silanol groups in an alkali metal salt of a silanol group-containing branched organopolysiloxane. Accordingly, since a silicone cured product obtained by curing the composition of the present invention shows less change in weight loss and hardness, the occurrence of cracks due to the thermal aging is minimized or suppressed, and accordingly, when the silicone cured product is applied to an encapsulant of an LED, reliability of the LED may be improved.
In component (A), the content of cerium is not particularly limited, and may be, for example, 0.1 to 2 % by weight based on the total weight of the curable organopolysiloxane composition. If the content of cerium in component (A) is less than 0.1 % by weight, the effect may be insignificant, and while, if the content of cerium in component (A) exceeds 2 % by weight, the value of b* of the cured product becomes 2 or more, and as a result, it is difficult to use the composition of the present invention as an LED encapsulant. According to one example, the content of cerium in component (A) may be about 5 to 300 ppm as a mass unit based on the total weight of the curable organopolysiloxane composition. In this case, the silicone cured product according to the present invention has excellent thermal stability, and a change in light emission color may be minimized when the silicone cured product is used in an optical semiconductor device. This component (A) is a material obtained by reacting an alkali metal salt of a silanol group-containing branched organopolysiloxane with cerium chloride or cerium salt of carboxylic acid.
In this case, the mixing ratio of an alkali metal salt of the silanol group- containing branched organopolysiloxane to cerium chloride (or cerium salt of carboxylic acid) is not particularly limited, and may be, for example, a molar ratio of 0.1 to 2 : 1.
Examples of the cerium salts of carboxylic acid which may be used in the present invention include cerium 2-ethylhexanoate, cerium naphthenate, cerium oleate, cerium laurate, cerium stearate, and the like, but are not limited thereto. These cerium salts may be used either alone or in a mixture of two or more thereof.
Further, examples of the alkali metal salts of the silanol group-containing branched organopolysiloxane which may be used in the present invention include sodium salt of the silanol group-containing branched organopolysiloxane, potassium salt of the silanol group-containing branched organopolysiloxane, and the like, but are not limited thereto.
According to one example, the alkali metal salt of the silanol group-containing branched organopolysiloxane may be an alkali metal salt of a branched organopolysiloxane having at least one silanol group, at least one silicon-bonded alkenyl group, and at least one silicon-bonded aryl group per molecule, and having siloxane units represented by the following general formula 1 :
[general formula 1 ]
RS1O3/2
where R is a substituted or unsubstituted monovalent hydrocarbon group. In the alkali metal salt of the silanol group-containing branched organopolysiloxane, the alkenyl groups have 2 to 12 carbon atoms, examples thereof include vinyl, allyl, methallyl, butenyl, pentenyl, and hexenyl group, specific examples thereof include vinyl, and allyl group, and more specific examples thereof include vinyl group.
Further, the aryl groups have 6 to 20 carbon atoms, examples thereof include phenyl, naphthyl, anthryl, phenanthryl, indenyl, benzophenyl, fluorenyl, xanthenyl, and anthronyl; aryloxyaryl groups such as o-phenoxyphenyl and p-phenoxyphenyl; alkaryl groups such as o-tolyl, m-tolyl, p-tolyl, xylyl, and ethylphenyl; and aralkyl groups such as benzyl, a-phenylethyl, and b-phenylethyl, and specific examples thereof include phenyl group.
Further, in addition to the above-described alkenyl groups and aryl groups, examples of the silicon-bonded organic groups in the silanol group-containing branched organopolysiloxane include substituted or unsubstituted Ci to C2o monovalent hydrocarbon groups, specific examples thereof include Ci to C20 alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl; and Ci to C20 halogenated alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl, and more specific examples thereof include methyl groups. In this case, the monovalent hydrocarbon groups may be unsubstituted or substituted with one or more substituents selected from the group consisting of Ci to C20 alkyl groups, C2 to C20 alkenyl group, Ce to C20 aryl groups, C7 to C2o aralkyl groups, and Ci to C20 halogenated alkyl groups.
In the siloxane unit represented by general formula 1, R is Ci to C20 monovalent hydrocarbon groups. Examples of the Ci to C2o monovalent hydrocarbon groups include Ci to C20 alkyl groups, C2 to C2o alkenyl group, Ce to C2o aryl groups, C7 to C20 aralkyl groups, and Ci to C20 halogenated alkyl groups. In this case, the Ci to C20 monovalent hydrocarbon groups may be unsubstituted or substituted with one or more substituents selected from the group consisting of Ci to C20 alkyl groups, C2 to C20 alkenyl groups, C6 to C20 aryl groups, C7 to C20 aralkyl groups, and Ci to C2o halogenated alkyl groups, and specifically, may be unsubstituted or substituted with one or more substituents selected from the group consisting of C to C20 alkyl groups and Ce to C20 aryl groups.
According to another example, the alkali metal salt of the silanol group- containing branched organopolysiloxane may be an alkali metal salt of an organopolysiloxane represented by the following average unit formula 1.
[average unit formula 1]
(R1R,R3Si0l/2)a(Rl2Si02/2)b(R2Si03/2)c(Si04/2)d(X10l/2)e
In the formula above,
each of R1, R2, and R3 can be the same or different and is independently selected from a substituted or unsubstituted monovalent hydrocarbon group,
with the proviso that at least one of R1, R2, and R3 per molecule is a silanol group,
at least one of R1, R2, and R3 per molecule is a C2 to C12 alkenyl group, and at least one of R1, R2, and R3 per molecule is a C6 to C20 aryl group.
The monovalent hydrocarbon groups have 1 to 20 carbon atoms, and examples thereof include the above-described Ci to C20 alkyl groups, the above-described C2 to C20 alkenyl group, the above-described CV, to C20 aryl groups, the above-described C7 to C20 aralkyl groups, and the above-described Ci to C20 halogenated alkyl groups.
Further, the content of the silanol groups per molecule is not particularly limited, but may be, for example, 1 to 3 mol% of R1, R2, and R3 per molecule. If the content of the silanol groups per molecule in the alkali metal salt of the silanol group-containing branched organopolysiloxane is within the above-described range, thermal stability of the cured product may be improved.
Further, the content of the alkenyl groups per molecule is not particularly limited, but may be, for example, 0.1 to 40 mol%, specifically 5 to 25 mol%, of R1, R2, and R3 per molecule. If the content of the alkenyl groups per molecule in the alkali metal salt of the silanol group-containing branched organopolysiloxane is within the above-described range, the reactivity of component (A) may be improved.
Further, the content of the aryl groups per molecule is not particularly limited, but may be, for example, 10 mol% or more of R1, R2, and R3 per molecule. If the content of the aryl groups per molecule in the alkali metal salt of the silanol group- containing branched organopolysiloxane is within the above-described range, it is possible to minimize attenuation due to light refraction, reflection, scattering, etc. in the cured product obtained by curing. In particular, in the siloxane units represented by the general formula R2Si03/2, it is even more preferable that not less than 30 mol % of R2 should be represented by the above-mentioned aryl groups, with R2 other than the alkenyl and aryl groups being preferably represented by methyl groups.
In addition, in the formula above, X1 is a hydrogen atom or Ci to C2o alkyl group, a is 0 or a positive number, b is 0 or a positive number, c is a positive number, d is 0 or a positive number, e is 0 or a positive number, b/c is a number between 0 and 10, a/c is a number between 0 and 0.5, d/(a+b+c+d) is a number between 0 and 0.3, and e/(a+b+c+d) is a number between 0 and 0.4.
According to another example, the alkali metal salt of the silanol group- containing branched organopolysiloxane may be an alkali metal salt of an organopolysiloxane represented by the following average unit formula 2.
[average unit formula 2]
(R1R1R3Si0,/2)a(R1 2Si02/2)b(R2Si03/2)c
In the formula above,
R1 is a Ci to C12 alkyl group,
R2 is a C6 to C20 aryl group or a C7 to C2o aralkyl group,
R3 is a C2 to C12 alkenyl group,
a is 0 or a positive number,
b is 0 or a positive number, and
c is a positive number,
with the proviso that at least one of R1, R2, and R3 per molecule is a silanol group.
The content of the silanol groups in the alkali metal salt of the above-described silanol group-containing branched organopolysiloxane is not particularly limited, and may be, for example, 1 to 3 mol% per molecule. If the content of the silanol groups in the alkali metal salt of the silanol group-containing branched organopolysiloxane is within the above-described range, thermal stability of the cured product may be improved.
The weight average molecular weight of the cerium-containing branched organopolysiloxane is not particularly limited, and may be, for example, about 1,000 to 3,000 g/mol, specifically about 1,500 to 2,500 g/mol.
In the composition of the present invention, the content of component (A) is not particularly limited, but may be, for example, about 0.01 to 5 parts by weight, based on 100 parts by weight of the composition. Component (B)
In the composition according to the present invention, the branched organopolysiloxane (hereinafter,‘component (B)’) imparts strength to a silicone cured product obtained by curing the composition.
Component (B) represents a branched organopolysiloxane having at least one silicon-bonded alkenyl group and at least one silicon-bonded aryl group per molecule, and having siloxane units represented by the general formula 2:
[general formula 2]
RS1O3/2
where R is a substituted or unsubstituted monovalent hydrocarbon group having
1 to 20 carbon atoms.
In component (B), the alkenyl groups have 1 to 20 carbon atoms. Examples of the Cl to C20 alkenyl groups include vinyl, allyl, methallyl, butenyl, pentenyl, and hexenyl group, preferably vinyl and allyl group, particularly preferred vinyl group.
In component (B), the aryl groups have 6 to 20 carbon atoms. Examples of the
C6 to C20 aryl groups include phenyl, naphthyl, anthryl, phenanthryl, indenyl, benzophenyl, fluorenyl, xanthenyl, anthronyl; aryloxyaryl groups such as o- or p-phen- oxyphenyl; alkaryl groups such as 0-, m-, p-tolyl, xylyl and ethylphenyl; aralkyl groups such as benzyl, a- and b-phenylethyl. Preferably the aryl group is phenyl group.
In addition, examples of silicon-bonded organic groups of component (B) other than the alkenyl and aryl groups include substituted or unsubstituted monovalent hydrocarbon groups having 1 to 20 carbon atoms, examples of which include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, and other alkyl groups; and halogenated alkyl groups having 1 to 20 carbon atoms such as chloromethyl, 3-chloropropyl, and 3,3,3- trifluoropropyl, with methyl being particularly preferable.
In the siloxane units of component (B) represented by the general formula 2 RS1O3/2, R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. Substituents of hydrocarbon groups may include the above-mentioned Cl to C20 alkyl groups, the above-mentioned C2 to C20 alkenyl groups, the above- mentioned C6 to C20 aryl groups, the above-mentioned C7 to C20 aralkyl groups, and the above-mentioned Cl to C20 halogenated alkyl groups, particularly preferably the above-mentioned Cl to C20 alkyl groups and the above-mentioned C6 to C20 aryl groups.
As component (B), an organopolysiloxane represented by the average unit formula 3:
(R4R4R6SiOl/2)a(R42SiO2/2)b(R5SiO3/2)0(SiO4/2)d(X2O1/2)e
is preferable.
In the formula above, each of R4, R5, and R6 can be the same or different and is independently selected from a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, wherein at least one of R4, R5 or R6 per molecule is an C2 to C12 alkenyl group and at least one of R4, R5 or R6 per molecule is an C6 to C20 aryl group.
The monovalent hydrocarbon group having 1 to 20 carbon atoms may be more specifically exemplified by the above-mentioned Cl to C20 alkyl groups, the above- mentioned C2 to C20 alkenyl groups, the above-mentioned C6 to C20 aryl groups, the above-mentioned C7 to C20 aralkyl groups, and the above-mentioned Cl to C20 halogenated alkyl groups.
Preferably 0.1 to 40 mol%, more preferably 5 to 25 mol%, of R4, R5, and R6 per molecule is the above-mentioned C2 to C12 alkenyl groups. This is due to the fact that when the content of the alkenyl groups is below the lower limit or exceeds the upper limit of the above-mentioned range, its reactivity with component (B) tends to decrease.
Also, in order to achieve low attenuation due to light refraction, reflection, scattering etc, in the cured product obtained by curing preferably not less than 10 mol% of R4, R5, and R6 should be the above-mentioned C6 to C20 aryl groups, and, in particular, in siloxane units represented by the general formula R5Si03/2, it is even more preferable that not less than 30 mol % of R5 should be represented by the above- mentioned aryl groups, with R5 other than the alkenyl and aryl groups being preferably represented by methyl groups.
In addition, in the formula above,
X2 is a hydrogen atom or Cl to C20 alkyl group, a is 0 or a positive number, b is 0 or a positive number, c is a positive number, d is 0 or a positive number, e is 0 or a positive number, b/c is a number between 0 and 10, a/c is a number between 0 and 0.5, d/(a+b+c+d) is a number between 0 and 0.3, and e/(a+b+c+d) is a number between 0 and 0.4.
As component (B), an organopolysiloxane with the average unit formula 4:
(R4R4R6Si0l/2)a(R42Si02/2)b(R5Si03/2)c is particularly preferable,
In the formula above, R4 is a Ci to C12 alkyl group, R5 is a C6 to C20 aryl group or a C7 to C20 aralkyl group, R6 is a C2 to C12 alkenyl group, a is 0 or a positive number, b is 0 or a positive number, and c is a positive number.
Although there are no limitations concerning the molecular weight of component (B), when converted to standard polystyrene, its weight average molecular weight (Mw) should preferably be in the range of from 500 g/mol to 10,000 g/mol, and, especially preferably, in the range of from 700 g/mol to 7,000 g/mol, more preferably in the range from 1,000 g/mol to 5,000 g/mol, particularly from 1,500 to 3,000 g/mol.
In the composition of the present invention, the content of component (B) is not particularly limited, but may be, for example, about 60 to 85 parts by weight based on 100 parts by weight of the composition. According to one example, the content of component (B) may be about 54 to 80 % by weight, based on the sum of the amounts of components (A), (B), and (C). Component tC)
Component (C) is the curing agent of the present composition.
Component (C) is a linear organopolysiloxane with both terminal ends of the molecular chain blocked by silicon-bonded hydrogen atoms having at least one silicon- bonded aryl group per molecule. By using a linear organopolysiloxane as the curing agent, instead of a branched organopolysiloxane, a good elongation performance may be obtained.
In Component (C), the aryl groups have 6 to 20 carbon atoms. Examples of the C6 to C20 aryl groups of component (C) are the same as those described above. Phenyl group is especially preferable.
In addition, examples of silicon-bonded organic groups of component (C) other than the aryl groups include substituted or unsubstituted Cl to C20 monovalent hydrocarbon groups with the exception of alkenyl groups, such as the above-described Cl to C20 alkyl groups, the above-described C7 to C20 aralkyl groups, and the above- described Cl to C20 halogenated alkyl groups, with methyl being particularly preferable.
In order to achieve low attenuation due to light refraction, reflection, scattering, etc. in the cured product obtained by curing the content of the silicon-bonded aryl groups among all the silicon-bonded organic groups in component (C) should preferably be not less than 15 mol % and, particularly preferably, not less than 30 mol%. Although there are no limitations concerning the viscosity of component (C) at 25 °C, it is preferably in the range of from 1 to 1,000 mPa-s, and, especially preferably, in the range of from 2 to 500 mPa-s. This is due to the fact that when the viscosity of component (C) is below the lower limit of the above-mentioned range, it may tend to volatilize and the makeup of the resultant composition may be unstable, and, on the other hand, when it exceeds the upper limit of the above-mentioned range, the handling properties of the resultant composition tend to deteriorate.
An organopolysiloxane represented by the general formula 3:
[general Formula 3]
Figure imgf000017_0001
:
is preferable as component (C).
In the formula above, each R7 can be the same or different and is independently selected from a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group with the exception of alkenyl groups.
The monovalent hydrocarbon group has 1 to 20 carbon atoms. Examples of the monovalent hydrocarbon groups of R7 include the above-mentioned Cl to C20 alkyl groups, the above-mentioned C6 to C20 aryl groups, and the above-mentioned Cl to C20 halogenated alkyl groups.
Here, at least one R7 per molecule must be one of the above-mentioned C6 to C20 aryl groups, preferably, phenyl.
In addition, n in the formula above is an integer of 0 or more, preferably, an integer in the range of from 0 to 20, and, especially preferably, an integer in the range of from 0 to 10. This is due to the fact that when the value of n exceeds the upper limit of the above-mentioned range, the toughness of the resultant composition, or the adhesive properties of the cured product, tend to deteriorate. It is most preferable that n is 1 to 4, particularly, 1, that is, the component (C) represents trisiloxane.
By having M unit as the repeating unit, instead of Q or T unit, a good elongation performance may be obtained.
Component (C) is preferably present in an amount of 1 to 30 % by weight, more preferably 10 to 30 % by weight, particularly prefered, 15 to 25 % by weight, based on the sum of the amounts of components (A), (B) and (C).
It is preferable that the molar ratio of Si-H groups in component (C)/ alkenyl
j
groups, for example, vinyl groups, in components (A) and (B) [ ^ 2 , where Mi is a number of moles of the alkenyl group in components (A) and (B), and M2 is a number of moles of the hydrosilyl group in component (C)] is 1 to 1.2 to reduce the reactive residual silicone hydride.
In the composition of the present invention, the content of component (C) is not particularyl limited, but may be, for example, about 10 to 30 parts by weight, based on 100 parts by weight of the composition. Component (ΈB
Component (D) is a hydrosilylation reaction catalyst.
The hydrosilylation reaction catalyst of component (D) is used to promote the reaction of the alkenyl groups of component (B) with the silicon-bonded hydrogen atoms of component (A),
Examples of component (D) include platinum catalysts, rhodium catalysts, and palladium catalysts. Platinum catalysts are preferable because of their ability to significantly stimulate the cure of the present composition. Examples of the platinum catalysts include platinum micropowder, chloroplatinic acid, alcohol solutions of chloroplatinic acid, platinum/alkenylsiloxane complexes, platinum/olefin complexes, and platinum/carbonyl complexes, preferably, platinum/alkenylsiloxane complexes. Examples of the alkenylsiloxanes include l,3-divinyl-l,l,3,3-tetramethyldisiloxane, l,3,5,7-tetramethyl-l,3,5,7-tetravinylcyclotetrasiloxane, alkenylsiloxanes obtained by substituting groups such as ethyl, phenyl etc. for some of the methyl groups of the above-mentioned alkenylsiloxanes, and alkenylsiloxanes obtained by substituting groups such as allyl, hexenyl, etc. for the vinyl groups of the above-mentioned alkenylsiloxanes. l,3-divinyl-l,l,3,3-tetramethyldisiloxane is particularly preferable because of the excellent stability of the platinum/alkenylsiloxane complex. Also, due to the improvement in the stability of the complex that their addition may bring, it is desirable to add l,3-divinyl-l, l,3,3-tetramethyldisiloxane, 1,3-diallyl-l, 1,3,3- tetramethyldisiloxane, 1,3-divinyl-l, 3-dimethyl- l,3-dlphenyldisiloxane, l,3-divinyl- 1, 1,3,3-tetraphenyldisiloxane, l,3,5,7-tetramethyl-l,3,5,7-tetravinylcyclotetrasiloxane and other alkenylsiloxanes and organosiloxane oligomers such as dimethylsiloxane oligomers to the platinum/alkenylsiloxane complex, with alkenylsiloxanes being particularly preferable.
There are no limitations on the content of component (D) as long as the amount promotes curing of the present composition. According to one example, in the present composition, the content of component (D) may be about 0.001 to 0.3 parts by weight, based on 100 parts by weight of the composition. According to another example, in the present composition, component (D) is preferably present in an amount resulting in a platinum content of 0.05 to 100 ppm (parts per million) by weight, more preferably 0.1 to 10 ppm by weight, particularly preferred 0.1 to 5 ppm by weight, relative to 100 parts by weight of the total of components (A), (B) and (C). This is due to the fact that when the content of component (D) is below the lower limit of the above-mentioned range, the present composition tends to fail to completely cure, and, on the other hand, when it exceeds the upper limit of the above-mentioned range, problems may arise in terms imparting various colors to the resultant cured product. Component (E)
Component (E) is an additive, which is a low molecular weight siloxane having at least one silicon-bonded alkenyl group per molecule, represented by the average formula 1 :
[average formula 1]
(R8 3Si0l/2)f(R82Si02/2)g(R8Si03/2)h(Si04/2)i
where each R8 can be the same or different and is independently selected from a substituted or unsubstituted monovalent hydrocarbon group, wherein at least one of R8 per molecule is an alkenyl group, with the proviso that the ratio between alkenyl groups and silicon atoms is from 0.3 to 1, f, g, h, and i are independently 0 or positive, wherein f+g+h+i is 1, and the weight average molecular weight Mw of the siloxane is less than 1 ,000 g/mol, preferably less than 800 g/mol, more preferably less than 500 g/mol.
Preferably component (E) is selected from the group consisting of DalkenyI 4, Malkenyl4Q, Malkenyl6Q2, Malkenyl3T. Preferably the alkenyl group is vinyl (=Vi). Particularly preferred as component (E) are cyclotetrasiloxane Dvi 4, and Mvi 4Q, especially DVl 4. Herein, D unit is R5 2Si02/¾ M unit is R53SiOi/2, Q unit is Si04/2, and T unit is R5SiC>3/2.
It is assumed that component (E) serves to react with an unreacted site (Si-H), thereby protecting additional reaction of the unreacted site due to heat or light. As a result, in the composition comprising component (E), color change and mechanical strength change to high temperature may be remarkably reduced.
In the composition according to prior art, which has no component (E), materials often show an increase in hardness after curing during storage at high temperature, which can be attributed to a post-curing reaction of remaining reactive sites and/or show a weight loss by evaporation of low molecular weight species that did not crosslink into the polymer network. Due to the change in hardness and weight loss, the materials were not stable under operating conditions. In the present invention, a reaction of component (E) with unreacted site (Si-H) leads to better stability such as less change in hardness, low weight loss, and discoloration, at high temperature.
Component (E) also gives a filling effect, which makes it possible to lower gas and vapor transmission. The encapsulant further comprising component (E) provides stablity to sulfur and such effect is expected to be obtained from the filing effect.
As a result, an LED package with excellent reliability may be obtained. Component (E) is both reactive and small enough to react with residual silicone hydride. At the same time, component (E) crosslinks into the siloxane network and thus does not increase the proportion of volatile components in the cured material. Component (E) is preferably used in an amount of at most 10 parts by weight, more preferably at most 7 parts by weight, and even more preferably at most 5 parts by weight relative to 100 parts by weight of the total of components (A), (B) and (C). If component (E) is included in higher amounts, compatibility with the other components would be lower and thus, transmittance would be lower. Preferably, component (E) is used in an amount of at least 1 parts by weight relative to 100 parts by weight of the total of components (A), (B) and (C). The amount of the component (E) may be adequately selected in consideration of the specific formulation and the feature.
Preferably, the composition of the present invention comprises about 0.5 to 10 parts by weight of component (E), based on 100 parts by weight of the composition. The curable silicone composition of the present invention may not comprise as flexibilizing units, a linear organopolysiloxane having at least two silicon-bonded alkenyl groups and at least one silicon-bonded aryl group per molecule. It is assumed that since bulky branched organopolysiloxane such as component (B) is used as resin instead of a linear organopolysiloxane, the present curable silicone composition provides excellent hardness and toughness. That is, bulky branched organopolysiloxane is directly connected to unreacted Si-H site.
The curable organopolysiloxane composition of the present invention may further comprise a crosslinking agent, which is generally used in this field.
The curable organopolysiloxane composition of the present invention may further comprise a curing inhibitor, a catalyst, and a phosphor, which are generally used in this field.
The present composition may also contain silica, glass, quartz, cristobalit, alumina, zinc oxide and other inorganic fillers; micropowders of organic resins such as polymethacrylate resin; heat-stabilizers, dyes, pigments, flame retardants, solvents, etc. as optional components, so long as this does not impair the purpose of this invention.
The compositions described above may be prepared by mixing the components generally used in this art, for example, by mixing all the components at ambient temperature.
An LED encapsulant of the present invention comprises the curable organopolysiloxane composition as described above. Encapsulation for light emitting devices in the present invention is well known to the art and may be used in the present invention. For example, casting, dispensing, molding may be used.
In a semiconductor device of the present invention, semiconductor elements are coated with a cured product of the curable organopolysiloxane composition as described above. Such semiconductor elements are exemplified by semiconductor elements used in diodes, transistors, thyristors, solid-state image pickup elements, monolithic ICs and in hydride ICs, In particular, it is preferable that semiconductor elements are light- emitting elements.
Examples of such semiconductor devices included diodes, light-emitting diodes, transistors, thyristors, photocouplers, CCDs, monolithic IICs, hybrid ICs, LSIs, and
VLSIs. Hereinafter, the present invention will be described in more detail with exemplary embodiments. However, the following exemplary embodiments are given for illustrative purposes only, and the scope of the present invention is not limited to these exemplary embodiments.
Examples
<Analytical Methods>
(1) Description of 29Si-NMR measurement
* Solvent: CeDe 99,8%d/CCl4 1: 1 v/v with 1 % w/w Cr(acac)3 as reagent for relaxation
* Sample concentration: ca. 2 g / 1.5 mL solvent in 10 mm NMR tube
* Spectrometer: Bruker Avance 300
* Sample head: 10 mm 1H/13C/,5N/29Si glassfree QNP-Head (Bruker)
* Measurement parameter: Pulprog = zgig60, TD = 64k, NS = 1024, SW = 200 ppm, AQ = 2.75 s, D1 = 4 s, SFOl = 300.13 MHz, Ol = -50 ppm
* Processing-Parameter: SI = 64k, WDW = EM, LB = 0.3 Hz
(2) Viscosity
Viscosity data is measured with a rheometer model MCR302 manufactured by the company Anton Paar, D-Ostfildern, according to DIN EN ISO 3219 in rotation with a cone-plate measurement system. Measurements were performed in a range where the samples behavior is newtonian. Viscosity data are given for a temperature of 25 °C and an ambient pressure of 1013 mbar,
(3) Molecular weight
Molecular weight is determined as weight average molecular weight Mw and number average molecular Mn by Size Exclusion Chromatography SEC. Polystyrene is used as standard. The detector is a RI detector. THF is used as solvent. Sample concentration is 5 mg / mL.
[Example 1]
1-1. Synthesis of Branched Organopolvsiloxane
After phenyl triethoxy silane, dimethyl dimethoxy silane, and divinyl tetramethyl disiloxane as monomers were introduced into a glass reactor at a molar ratio of 7 : 1 : 1, water was introduced thereinto in an amount of 1 part by weight relative to the content of the phenyl triethoxy silane, and then hydrochloric acid (HC1) as a catalyst was introduced thereinto in an amount of 0.0009 part by weight relative to the content of the water. Thereafter, after the mixture was refluxed for 2 hours and heated, sodium hydroxide was introduced thereinto in an amount of 0.0016 part by weight relative to the content of water used, and then the resulting mixture was subjected to condensation polymerization by being refluxed and heated.
After the reaction solution was neutralized with hydrochloric acid until the time point when the acidity of the reaction solution became acidic, a solution containing a branched organopolysiloxane was obtained by removing the aqueous layer of the solution cooled to room temperature, and introducing toluene thereinto in an amount of 1 part by weight relative to the content of the phenyl triethoxy silane used above.
The solvent was removed from the solution containing the branched organopolysiloxane obtained above under vacuum, and 29Si NMR of the remaining solid content (the branched organopolysiloxane) was (Me2ViSiOi/2): 20%, (Me2Si02/2): 10%, (PhSi03/2): 70%.
1-2. Preparation of Branched Organopolvsiloxane lncluding Cerium Salt The content of the solid content in the solution containing the branched organopolysiloxane obtained in Example 1-1 was measured, and the content of branched organopolysiloxane used was estimated based on this content. Thereafter, the solution containing the branched organopolysiloxane was introduced together with methanol into a glass reactor. In this case, methanol was used in an amount of 0.25 part by weight relative to the content of toluene used in Example 1-1. Thereafter, sodium hydroxide was introduced into the glass reactor in an amount of 0.028 part by weight relative to the estimated content of the branched organopolysiloxane, and then the mixture was stirred at room temperature for 2 hours.
Thereafter, cerium ethylhexanoate was introduced in an amount of 0,057 part by weight relative to the estimated content of the branched organopolysiloxane compound, and then the mixture was allowed to react while being stirred at 50°C for 2 hours.
After the reaction was terminated, the solution was cooled, the aqueous layer was removed, and then a branched vinylsiloxane compound containing cerium salt [(Me2ViSiOi/2)(0.2-x)(Me2SiO2/2)(0.i-y)(PhSiO3/2)(0.7-z)(Cei/3Me2SiO2/2)(x+y+z)] was prepared by filtering and distilling the remaining solution.
1-3. Preparation of Curable Organopolysiloxane
2.5 parts by weight of the branched vinylsiloxane compound containing cerium salt obtained in Example 1-2 as component (A), 73.55 parts by weight of the branched vinylsiloxane compound obtained in Example 1-1 as component (B), 21 parts by weight of l,l,5,5-tetramethyl-3,3-diphenyltrisiloxane as component (C), 0.03 parts by weight of a platinum(0)-l,3-divinyl-l, l,3,3,-tetramethyl-disiloxane complex as component (D), 3 parts by weight of DV| 4 as component (E), 0.76 parts by weight of 3- Glycidoxypropyltrimethoxysilane as additive (1) which is adhesion promoter, 0.76 parts by weight of 3-Methacryloxypropyltrimethoxysilane as additive (2) which is adhesion promoter, and 0.9 parts by weight of 2-Methyl-3-butyn~2-ol as additive (3) which is curing inhibitor were mixed to prepare a curable organopolysiloxane composition. In this case, the content of each component was based on 100 parts by weight of the sum of the amounts of components (B), (C), (D), (E), and additive (1) to (3).
[Comparative Example 1]
73.55 parts by weight of the branched vinylsiloxane compound obtained in Example 1-1 as component (B), 21 parts by weight of l,l,5,5-tetramethyl-3,3- diphenyltrisiloxane as component (C), 0.03 parts by weight of a platinum(0)-l,3- divinyl-l,l,3,3,-tetramethyl-disiloxane complex as component (D), 3 parts by weight of DVl4 as component (E), 0.76 parts by weight of 3-Glycidoxypropyltrimethoxysilane as additive (1) which is adhesion promoter, 0.76 parts by weight of 3- Methacryloxypropyltrimethoxysilane as additive (2) which is adhesion promoter, and 0.9 parts by weight of 2-Methyl-3-butyn-2-ol as additive (3) which is curing inhibitor were mixed to prepare a curable organopolysiloxane composition. In this case, the content of each component was based on 100 parts by weight of the sum of the amounts of components (B), (C), (D), (E), and additive (1) to (3).
[Experimental Example 1 : Crack test]
For the compositions in Example 1 and Comparative Example 1, it was determined whether cracks occurred. Specimens of LED packages and specimens of cured silicone each contained in an aluminum pan were prepared, and then it was observed whether cracks occurred on the specimens at the time of quenching the specimens from 250°C to room temperature (about 22.5°C) at an interval of 4 hours. The results each are shown in Figs. 1 and 2.
As shown in Figs. 1 and 2, even though the quenching of the composition in Example 1 from 250°C to room temperature was repeated 25 times (100 hours), any crack did not occur. On the contrary, when the quenching of the composition in Comparative Example 1 from 250°C to room temperature was repeated 6 times (24 hours), cracks occurred. [Experimental Example 2: Hardness and weight change test]
For the composition according to example 1 and comparative example 1, change of hardness and weight after storage at 200 °C was determined. Specimens of cured silicone are prepared and stored at 200 °C. Then, change of hardness and weight of the specimens were measured. The result is shown in the Figs. 3 and 4.
As shown in Figs. 3 and 4, the composition according to example 1 shows almost no change of hardness and weight at 200 °C, whereas the composition according to comparative example 1 shows increase of hardness and weight.

Claims

WHAT IS CLAIMED IS:
1. A curable organopolysiloxane composition comprising;
(A) a cerium (Ce)-containing branched organopolysiloxane;
(B) a branched organopolysiloxane;
(C) a linear organopolysiloxane with both terminal ends of the molecular chain blocked by silicon-bonded hydrogen atoms, having at least one silicon-bonded aryl group per molecule;
(D) a hydrosilylation reaction catalyst; and
(E) a low molecular weight siloxane having at least one silicon-bonded alkenyl group per molecule, represented by the following average formula 1 :
[average formula 1]
(R8 3Si0,/2)f(R82Si02/2)g(R8Si03/2)h(Si04/2)i
(where
each R8 is the same or different and is independently selected from a substituted or unsubstituted monovalent hydrocarbon group,
wherein at least one of R8 per molecule is an alkenyl group,
with the proviso that a ratio between alkenyl groups and silicon atoms is from
0.3 to 1 : 1,
f, g, h, and i are independently 0 or a positive number,
wherein f+g+h+i is 1, and
the weight average molecular weight Mw of the siloxane is 1,000 g/mol or less).
2. The curable organopolysiloxane composition of claim 1, wherein in component (A), a content of cerium is 0.1 to 2% by weight based on the total weight of the curable organopolysiloxane composition.
3. The curable organopolysiloxane composition of claim 1, wherein component (A) is a material formed by allowing an alkali metal salt of a silanol group-containing branched organopolysiloxane to react with cerium chloride or cerium salt of carboxylic acid.
4. The curable organopolysiloxane composition of claim 3, wherein a molar ratio of the cerium chloride (or cerium salt of carboxylic acid) to the alkali metal salt of the silanol group containing-branched organopolysiloxane is 1 : 0.1 to 2.
5. The curable organopolysiloxane composition of claim 3, wherein a content of silanol groups in the alkali metal salt of the silanol group-containing branched organopolysiloxane is 1 to 3 mol% per molecule.
6. The curable organopolysiloxane composition of claim 3, wherein the alkali metal salt of the silanol group-containing branched organopolysiloxane is an alkali metal salt of a branched organopolysiloxane having at least one silanol group, at least one silicon-bonded alkenyl group, and at least one silicon-bonded aryl group per molecule, and having siloxane units represented by the following general formula 1 :
[genera] formula 1]
RS1O3/2
(where R is a Ci to C20 monovalent hydrocarbon group).
7. The curable organopolysiloxane composition of claim 3, wherein the alkali metal salt of the silanol group-containing branched organopolysiloxane is an alkali metal salt of an organopolysiloxane represented by the following average unit formula 1:
[average unit formula 1]
(R1R1R3Si0,/2)a(R12Si02/2)b(R2Si03/2)c(Si04/2)d(X10,/2)e
(where each of R1, R2, and R3 is the same or different and is independently selected from a substituted or unsubstituted Ci to C20 monovalent hydrocarbon group, with the proviso that at least one of R1, R2, and R3 per molecule is a silanol group, at least one of R1, R2, and R3 per molecule is a C2 to Ci2 alkenyl group, and at least one of R1, R2, and R3 per molecule is a C6 to C20 aryl group,
X1 is a hydrogen atom or a Ci to C20 alkyl group,
a is 0 or a positive number,
b is 0 or a positive number,
c is a positive number,
d is 0 or a positive number,
e is 0 or a positive number,
b/c is a number between 0 and 10,
a/c is a number between 0 and 0.5,
d/(a+b+c+d) is a number between 0 and 0.3, and
e/(a+b+c+d) is a number between 0 and 0.4).
8. The curable organopolysiloxane composition of claim 3, wherein the alkali metal salt of the silanol group-containing branched organopolysiloxane is an alkali metal salt of an organopolysiloxane represented by the following average unit formula 2
[average unit formula 2]
(R1R1R3Si0l/2)a(R12Si02/2)b(R2Si03/2)c
(where R1 is a Cj to C12 alkyl group,
R2 is a C , to C20 aryl group or a C7 to C2o aralkyl group,
R3 is a C2 to C12 alkenyl group,
a is 0 or a positive number,
b is 0 or a positive number, and
c is a positive number,
with the proviso that at least one of R1, R2, and R3 per molecule is a silanol group).
9. The curable organopolysiloxane composition of claim 7, wherein a content of the silanol groups is 1 to 3 mol% of R1, R2, and R3 per molecule.
10. The curable organopolysiloxane composition of claim 1, wherein the cerium- containing branched organopolysiloxane has a weight average molecular weight of 1,000 to 3,000 g/mol,
11. The curable organopolysiloxane composition of claim 1, in which the component (B) is a branched organopolysiloxane having at least one silicon-bonded alkenyl group and at least one silicon-bonded aryl group per molecule, and having siloxane units represented by the general formula 2: [general formula 2]
RS1O3/2
where R is a substituted or unsubstituted monovalent a Ci to C20 hydrocarbon group
12. The curable organopolysiloxane composition of claim 1, in which the component (B) is an organopolysiloxane represented by the average unit formula 3 :
[average unit formula 3]
(R4R4R6Si0l/2)a(R42Si02/2)b(RSSi03/2)c(Si04/2)d(X20l/2)e
where each of R4, R5, and R6 can be the same or different, and is independently selected from a substituted or unsubstituted a Ci to C20 monovalent hydrocarbon group, wherein at least one of R4, R5, or R6 per molecule is a Ci to C12 alkenyl group and at least one of R4, R5, or R6 per molecule is a Ci to C20 aryl group,
X2 is a hydrogen atom or a Ci to C20 alkyl group,
a is 0 or a positive number,
b is 0 or a positive number,
c is a positive number,
d is 0 or a positive number,
e is 0 or a positive number,
b/c is a number between 0 and 10,
a/c is a number between 0 and 0.5,
d/(a+b+c+d) is a number between 0 and 0.3, and
e/(a+b+c+d) is a number between 0 and 0.4.
13. The curable organopolysiloxane composition of claim 1, in which component
(B) is an organopolysiloxane with the average unit formula 4:
[average unit formula 4]
(R4R4R6SiO,/2)a(R42Si02/2)b(R5Si03/2)c
where R4 is a Ci to C12 alkyl group,
R5 is a Ce to C20 aryl group or C7 to C2o aralkyl group,
R6 is a C2 to C12 alkenyl group,
a is 0 or a positive number,
b is 0 or a positive number, and
c is a positive number.
14. The curable organopolysiloxane composition of claim 1, in which component
(C) is an organopolysiloxane represented by the general formula 3:
[general formula 3]
Figure imgf000034_0001
i where each R7 can be the same or different and is independently selected from a hydrogen atom or a substituted or unsubstituted Ci to C20 monovalent hydrocarbon group with the exception of alkenyl groups, wherein at least one R7 per molecule is a Ce to C20 aryl group, and
n is an integer of 0 or more.
15. The curable organopolysiloxane composition of claim 1, in which component (E) is selected from the group consisting of DVi 4, MVl4Q, MVY,Q2. MVl3T.
16, The curable organopolysiloxane composition of claim 1, in which component
(E) comprises DV| 4.
17. The curable organopolysiloxane composition of claim 1, wherein based on 100 parts by weight of the composition, the curable organopolysiloxane composition comprises:
0.01 to 5 parts by weight of the component (A);
60 to 85 parts by weight of the component (B);
10 to 30 parts by weight of the component (C);
0.001 to 0.3 parts by weight of the component (D); and
0.5 to 10 parts by weight of the component (E).
18. The curable organopolysiloxane composition of claim 1, wherein the molar ratio of the hydrosilyl group in component (C) with respect to the alkenyl group in
,
components (A) and (B) [ , where Mi is a number of moles of the alkenyl group in components (A) and (B), and M2 is a number of moles of the hydrosilyl group in component (C)] is 1 to 1. 2.
19. The curable organopolysiloxane composition of claim 1, further comprising at least one selected from the group consisting of a crosslinking agent, a curing inhibitor, a catalyst, and a phosphor.
20. An LED encapsulant comprising the curable organopolysiloxane composition according to any one of claims 1 to 19.
21. A semiconductor device, in which semiconductor elements are coated with a cured product of the curable organopolysiloxane composition according to any one of claims 1 to 19.
22. The semiconductor device according to claim 21, in which said semiconductor elements are light-emitting elements.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1393078A (en) * 1972-12-18 1975-05-07 Toray Silicone Co Organopolysiloxane composition having heat stability
WO2014130784A1 (en) * 2013-02-22 2014-08-28 Dow Corning Toray Co., Ltd. Curable silicone composition, cured product threreof, and optical semiconductor device
CN107629460A (en) * 2017-09-28 2018-01-26 广州慧谷化学有限公司 Organopolysiloxane composition and preparation method thereof, semiconductor devices
WO2018028792A1 (en) * 2016-08-12 2018-02-15 Wacker Chemie Ag Curable organopolysiloxane composition, encapsulant and semiconductor device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1393078A (en) * 1972-12-18 1975-05-07 Toray Silicone Co Organopolysiloxane composition having heat stability
WO2014130784A1 (en) * 2013-02-22 2014-08-28 Dow Corning Toray Co., Ltd. Curable silicone composition, cured product threreof, and optical semiconductor device
WO2018028792A1 (en) * 2016-08-12 2018-02-15 Wacker Chemie Ag Curable organopolysiloxane composition, encapsulant and semiconductor device
CN107629460A (en) * 2017-09-28 2018-01-26 广州慧谷化学有限公司 Organopolysiloxane composition and preparation method thereof, semiconductor devices

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