JP7276212B2 - Thermally conductive silicone composition and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thermally conductive silicone composition and a method for producing the same, and more particularly to a thermally conductive silicone composition that exhibits good void resistance for solder resist substrates, low viscosity, and excellent misalignment resistance, and production thereof. Regarding the method.

In general, electrical and electronic parts generate heat during use, so heat removal is necessary for proper operation of these parts. Proposed. In this case, there are two types of thermally conductive materials: (1) easy-to-handle sheet-like materials and (2) paste-like heat-dissipating greases.

The sheet-like material of (1) is not only easy to handle, but also has the advantage of being excellent in stability. It will be. In addition, since a certain degree of strength and hardness is required to maintain the sheet shape, the tolerance generated between the element and the housing cannot be absorbed, and the element may be destroyed by the stress.

On the other hand, in the case of heat dissipating grease of (2), not only can it be applied to the mass production of electrical and electronic products by using a coating device, but it also has the advantage of being excellent in heat dissipating performance due to its low contact thermal resistance. There is However, if the viscosity of the heat dissipating grease is lowered in order to obtain good application performance, the heat dissipating grease will shift due to the thermal shock of the element (pump-out phenomenon), resulting in insufficient heat removal, and as a result, the element will be damaged. A malfunction occurred.

Therefore, a specific organopolysiloxane, a thickening agent such as zinc oxide, alumina, aluminum nitride, boron nitride, silicon carbide, an organopolysiloxane having at least one hydroxyl group directly bonded to a silicon atom in one molecule, and an alkoxy A grease-like silicone composition that suppresses base oil bleeding by combining with silane, a liquid silicone, a thermally conductive inorganic filler having a constant thermal conductivity and a Mohs hardness of 6 or more, and a constant thermal conductivity A thermally conductive silicone composition having excellent thermal conductivity and dispensing properties (Patent Document 1: JP-A-11-246884), which is obtained by combining a thermally conductive inorganic filler having a Mohs hardness of 5 or less, specified and a metallic aluminum powder having an average particle size of 0.5 to 50 μm (Patent Document 2: JP-A-2000-63873), two types with different average particle sizes A silicone grease composition (Patent Document 3: JP-A-2000-169873) in which the filling rate of aluminum nitride in the silicone grease is increased by mixing and using the aluminum nitride powder of the above, and the viscosity of the oil is increased to bleed. Higher performance thermally conductive silicone compositions have been proposed, such as out-controlled silicone grease compositions. However, there has not yet been obtained a device that can sufficiently cope with the high performance of electronic and electrical parts used.

JP-A-11-246884 JP-A-2000-63873 Japanese Patent Application Laid-Open No. 2000-169873

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a thermally conductive silicone composition that exhibits good void resistance for solder resist substrates, low viscosity, and excellent misalignment resistance, and a method for producing the same. intended to

A solder resist substrate is a cured product of an epoxy resin composition containing a basic catalyst or a basic curing agent as a curing agent. For this reason, when thermally conductive grease (thermally conductive silicone composition) is applied to a solder resist substrate, hydrolysis of the alkoxy groups contained in the thermally conductive grease is caused by the basic catalyst and residual basic curing agent. The organic organosiloxane hydrolyzes, which volatilizes the alcohol. This phenomenon is conspicuous when the electronic component generates a large amount of heat. In the worst case, the pressure pushes the thermally conductive silicone composition away, causing through-holes or cracks, resulting in no heat passage.

As a result of intensive studies to achieve the above object, the present inventors have found that (A) an organopolysiloxane having an alkenyl group bonded to a silicon atom and (B) an organohydrogenpolysiloxane are mixed in a specific molar ratio (Si- H / Si-Vi) and the thermally conductive inorganic fillers (C) and (D), which are metal oxides having a specific average particle size, are combined in a specific amount, and (E ) A hydrolyzable organosiloxane containing an alkoxy group and, if necessary, a platinum group metal catalyst are blended, heated and mixed to react components (A) and (B), and then a specific amount of (F ) Combining an alkoxy condensation catalyst to obtain a thermally conductive silicone composition having a specific viscosity and a specific amount of Si—H residues per unit volume, thereby improving void resistance and displacement resistance to a solder resist substrate. The inventors have found that they can be compatible with each other, and have completed the present invention.

In the present invention, the hydrolyzable organosiloxane having an alkoxy group reacts with the alkoxy condensation catalyst and the hydrolyzable organosiloxane having an alkoxy group in the thermally conductive silicone composition and the moisture absorbed by the solder resist substrate to form the hydrolyzable organosiloxane having an alkoxy group. A shielding layer forms on the surface of the solder resist substrate. This surface shielding layer prevents the reaction between the moisture from the solder resist substrate and the hydrolyzable organosiloxane having alkoxy groups in the thermally conductive silicone composition. (Hydrolysis of hydrolyzable organosiloxanes with alkoxy groups) is terminated. This suppresses cracks and voids in the thermally conductive silicone composition.

Accordingly, the present invention provides the following thermally conductive silicone composition and method for producing the same.
1. (A) an organopolysiloxane having a silicon-bonded alkenyl group and (B) an organohydrogenpolysiloxane are combined with the silicon-bonded alkenyl groups in component (A) and the Si— in component (B). a reaction product reacted with H groups at a molar ratio (Si—H/Si—Vi) of 2 to 10;
(C) a thermally conductive inorganic filler with an average particle size of 3 μm or less selected from metal oxides;
(D) a thermally conductive inorganic filler having an average particle size of 5 μm or more selected from metal oxides;
(E) a hydrolyzable organosiloxane having an alkoxy group, and (F) an alkoxy condensation catalyst that is a silane or siloxane containing a guanidyl group : 0.01 to 1% by mass relative to component (E)
and the total amount of components (C) and (D) is 2,000 to 8,000 parts by mass per 100 parts by mass of components (A) and (B), and 25 A thermally conductive silicone composition having an absolute viscosity of 50 to 500 Pa·s at °C and an amount of Si—H residues per unit volume of 1×10 ⁻⁶ to 1×10 ⁻³ mol/cm ³ .
2. 1. The thermal conductivity according to 1, wherein the amount of (E) the hydrolyzable organosiloxane having an alkoxy group is 25 to 400 parts by mass with respect to the total of 100 parts by mass of the components (A) and (B). Silicone composition.
3. 3. The thermally conductive silicone composition according to 1 or 2, which is for solder resist substrates.
4. (A) an organopolysiloxane having a silicon-bonded alkenyl group and (B) an organohydrogenpolysiloxane are combined with the silicon-bonded alkenyl groups in component (A) and the Si— in component (B). a reaction product reacted with H groups at a molar ratio (Si—H/Si—Vi) of 2 to 10;
(C) a thermally conductive inorganic filler with an average particle size of 3 μm or less selected from metal oxides;
(D) a thermally conductive inorganic filler having an average particle size of 5 μm or more selected from metal oxides;
(E) a hydrolyzable organosiloxane having an alkoxy group, and
(F) Alkoxy condensation catalyst: 0.01 to 1% by mass relative to component (E)
and the total amount of components (C) and (D) is 2,000 to 8,000 parts by mass per 100 parts by mass of components (A) and (B), and 25 A method for producing a thermally conductive silicone composition having an absolute viscosity at °C of 50 to 500 Pa·s and an amount of Si—H residues per unit volume of 1×10 ⁻⁶ to 1×10 ⁻³ mol/cm ³ . There is
(I) (A) an organopolysiloxane having an alkenyl group bonded to a silicon atom, (B) an organohydrogenpolysiloxane, and (C) a thermally conductive inorganic filler having an average particle size of 3 μm or less selected from metal oxides; (D) a thermally conductive inorganic filler having an average particle size of 5 μm or more selected from metal oxides, (E) a hydrolyzable organosiloxane having an alkoxy group, and, if necessary, a platinum group metal-based catalyst, (A) a step of mixing the alkenyl groups bonded to silicon atoms in the component and the Si—H groups in the component (B) so that the molar ratio (Si—H/Si—Vi) is 2 to 10 to obtain a mixture; ,
(II) heating the resulting mixture at 100 to 180° C. for 30 minutes to 4 hours to react components (A) and (B);
(III) A method for producing a thermally conductive silicone composition comprising the step of mixing (F) an alkoxy condensation catalyst with the reaction mixture obtained above at room temperature for 10 to 60 minutes.
5. 4. The thermal conductivity according to 4, wherein the amount of (E) the hydrolyzable organosiloxane having an alkoxy group is 25 to 400 parts by mass with respect to the total of 100 parts by mass of the components (A) and (B). A method for producing a silicone composition.
6. 6. The method for producing a thermally conductive silicone composition according to 4 or 5, which is for a solder resist substrate.

ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide a thermally conductive silicone composition that has good void resistance for solder resist substrates, low viscosity and excellent displacement resistance, and a method for producing the same. Therefore, the present invention is suitable for removing heat from electrical/electronic components using solder resist substrates that generate heat during use.
Hereinafter, "thermally conductive silicone composition" may be referred to as "silicone composition".

The present invention will be described in detail below.

The thermally conductive silicone composition of the present invention is
A reaction product obtained by reacting (A) an organopolysiloxane having alkenyl groups bonded to silicon atoms and (B) an organohydrogenpolysiloxane at a specific ratio;
(C) a thermally conductive inorganic filler with an average particle size of 3 μm or less selected from metal oxides;
(D) a thermally conductive inorganic filler having an average particle size of 5 μm or more selected from metal oxides;
It contains (E) a hydrolyzable organosiloxane having an alkoxy group and (F) an alkoxy condensation catalyst, and has a specific viscosity and a specific amount of Si—H residues per unit volume.
Each component will be described below.

[Reaction product]
The reaction product used in the present invention comprises (A) an organopolysiloxane having a silicon-bonded alkenyl group and (B) an organohydrogenpolysiloxane combined with a silicon-bonded alkenyl group in component (A). It is a reaction product obtained by reacting groups with Si--H groups in component (B) at a molar ratio (Si--H/Si--Vi) of 2-10.

[(A) component]
Component (A) is an alkenyl group-containing organopolysiloxane having an average of at least one silicon-bonded alkenyl group per molecule (usually 1 to 20, preferably 1 to 10). These can be used individually by 1 type or in combination of 2 or more types as appropriate.

The molecular structure of component (A) is not particularly limited. It is preferably a straight-chain organopolysiloxane. Specifically, the molecular chain is mainly composed of repeating diorganosiloxane units, and both ends of the molecular chain are blocked with triorganosiloxy groups. is preferably a diorganopolysiloxane of The component (A) may be a polymer consisting of a single siloxane unit or a copolymer consisting of two or more siloxane units. Further, the position of the alkenyl group bonded to the silicon atom in the component (A) is not particularly limited, and the alkenyl group may be either a silicon atom at the terminal of the molecular chain or a silicon atom at the non-terminal of the molecular chain (in the middle of the molecular chain). may be bound only to or may be bound to both of them.

As the component (A), for example, the following average composition formula (1)
^R1mR2nSiO _{(4-mn)/2 ( 1} ⁾
(wherein R ¹ is independently an unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturation, R ² is independently an alkenyl group, m is 0.5 to 2.5, It is preferably a positive number of 1.0 to 2.1, and n is a positive number of 0.001 to 1.1, preferably 0.001 to 1.0, provided that m+n is usually 0.501 to 3. .0, preferably a positive number from 2.0 to 3.0.)
and having at least one alkenyl group bonded to a silicon atom.

Examples of R ¹ include unsubstituted or substituted monovalent hydrocarbon groups containing no aliphatic unsaturated bonds having 1 to 10 carbon atoms. Specific examples of R ¹ include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, hexyl group, octyl group and decyl group; aryl groups such as xylyl group and naphthyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; aralkyl groups such as benzyl group, 2-phenylethyl group and 3-phenylpropyl group; Halogen atoms such as a chlorine atom, a bromine atom, and an iodine atom for some or all of the bonded hydrogen atoms; A fluoropropyl group, a cyanoethyl group and the like can be mentioned.
Among these, a methyl group, a phenyl group, or a combination of both is preferred. Component (A) in which R ¹ is a methyl group, a phenyl group, or a combination of both is easy to synthesize and has good chemical stability.

Examples of R ² include alkenyl groups having 2 to 8 carbon atoms. Specific examples of R ² include vinyl group, allyl group, 1-propenyl group, isopropenyl group, 1-butenyl group, isobutenyl group and hexenyl group. Among these, a vinyl group is preferred. The component (A) in which R ² is a vinyl group is easy to synthesize and has good chemical stability.

Specific examples of component (A) include dimethylsiloxane-methylvinylsiloxane copolymer with trimethylsiloxy groups blocked at both molecular chain ends, methylvinylpolysiloxane with trimethylsiloxy groups blocked at both molecular chain ends, and dimethyl with trimethylsiloxy groups blocked at both molecular chain ends. Siloxane/methylvinylsiloxane/methylphenylsiloxane copolymer, dimethylsiloxane/methylvinylsiloxane/diphenylsiloxane copolymer with trimethylsiloxy group-blocked at both molecular chain ends, dimethylpolysiloxane with dimethylvinylsiloxy group-blocked at both molecular chain ends, both molecular chain ends dimethylvinylsiloxy-terminated methylvinylpolysiloxane, dimethylvinylsiloxy-terminated dimethylsiloxane/methylvinylsiloxane copolymer, dimethylvinylsiloxy-terminated dimethylsiloxane/methylvinylsiloxane/methylphenylsiloxane at both molecular chain ends Polymer, dimethylsiloxane-methylvinylsiloxy group-blocked at both molecular chain ends, dimethylsiloxane-methylvinylsiloxane-diphenylsiloxane copolymer, dimethylpolysiloxane-blocked at both molecular chain ends with divinylmethylsiloxy group, dimethylpolysiloxane-blocked at both molecular chain ends with trivinylsiloxy group , a dimethylpolysiloxane in which one end of the molecular chain is blocked with a dimethylvinylsiloxy group and the other end is blocked with a trimethylsiloxy group, and one end of the molecular chain is blocked with a dimethylvinylsiloxy group and the other end is blocked with a trimethylsiloxy group. methylvinylpolysiloxane, and a dimethylsiloxane-methylvinylsiloxane copolymer having a molecular chain end capped with a dimethylvinylsiloxy group at one end and a molecular chain end capped with a trimethylsiloxy group at the other end. These organopolysiloxanes may be used singly or in combination of two or more. Alternatively, one or two or more having different degrees of polymerization may be used in combination.

The alkenyl group content in the organopolysiloxane is preferably 0.002 to 1.2 mol/100 g, more preferably 0.003 to 0.5 mol/100 g. If the amount of alkenyl groups is too large, the degree of cross-linking may become too high, resulting in a highly viscous grease.

The absolute viscosity of component (A) at 25° C. is preferably 0.1 to 20,000 mPa·s, more preferably 10 to 5,000 mPa·s. If the absolute viscosity is too low, the thermally conductive inorganic filler in the resulting silicone composition tends to settle out, possibly resulting in poor long-term storage stability. On the other hand, if the absolute viscosity is too high, the resulting silicone composition will tend to lack fluidity and may have poor workability. In the present invention, absolute viscosity is a value measured by a spiral viscometer such as a Malcolm viscometer (type PC-10AA).

[(B) Component]
Component (B) is an organohydrogenpolysiloxane having one or more silicon-bonded hydrogen atoms (Si—H groups) in one molecule, and is used alone or in combination of two or more. be able to. Component (B) organohydrogenpolysiloxane is a curing agent for silicone compositions, and has an average of 1 or more, preferably 2 or more (usually about 2 to 300, more preferably 2 to 200) per molecule. degree) of hydrogen atoms (Si—H groups) bonded to silicon atoms.

The molecular structure of component (B) is not particularly limited. Those represented by the compositional formula (2) can be used.
^R3pHqSiO _{( 4-pq)/2 (} 2)
(wherein R ³ is independently an unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturation; p is 0.4 to 2.5, preferably 0.8 to 2.2; is a positive number, q is a positive number of 0.03 to 1.0, preferably 0.05 to 0.95, and p+q is 0.43 to 3.0, preferably 0.85 to 3.0 is a positive number of

R ³ in formula (2) includes alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, isopropyl group, isobutyl group, tert-butyl group and cyclohexyl group; Aryl groups such as tolyl group and xylyl group; aralkyl groups such as benzyl group and phenethyl group; halogenated alkyl groups such as 3-chloropropyl group and 3,3,3-trifluoropropyl group; Examples include unsubstituted or halogen-substituted monovalent hydrocarbon groups that do not contain about 10, preferably about 1 to 8, aliphatic unsaturated bonds. A methyl group, an ethyl group, a propyl group, a phenyl group and a 3,3,3-trifluoropropyl group are preferred, and a methyl group is more preferred.

Specific examples of (B) component organohydrogenpolysiloxane include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, methylhydrogencyclo Polysiloxane, methylhydrogensiloxane/dimethylsiloxane cyclic copolymer, tris(dimethylhydrogensiloxy)methylsilane, tris(dimethylhydrogensiloxy)phenylsilane, dimethylhydrogensiloxy group-blocked dimethylsiloxane/methylhydrogen at both molecular chain ends Siloxane copolymer, dimethylhydrogensiloxy-blocked methylhydrogenpolysiloxane at both molecular chain ends, trimethylsiloxy-blocked methylhydrogenpolysiloxane at both molecular chain ends, dimethylpolysiloxane blocked at both molecular chain ends with dimethylhydrogensiloxy groups, molecule Dimethylsiloxane/diphenylsiloxane copolymer with dimethylhydrogensiloxy group-blocked at both chain ends, dimethylsiloxane/methylhydrogensiloxane copolymer with trimethylsiloxy group-blocked at both molecular chain ends, dimethylsiloxane/diphenylsiloxane with both molecular chain ends blocked with trimethylsiloxy group・Methylhydrogensiloxane copolymer, dimethylsiloxane endblocked with dimethylhydrogensiloxy groups at both molecular chain ends ・Methylhydrogensiloxane copolymer, copolymer of H(CH ₃ ) ₂ SiO _1/2 units and SiO ₂ units , copolymers of H(CH ₃ ) ₂ SiO _1/2 units, (CH ₃ ) ₃ SiO _1/2 units and SiO ₂ units, and mixtures of two or more of these organohydrogenpolysiloxanes. be done.

The content of hydrogen atoms (Si—H groups) bonded to silicon atoms in component (B) is 0.001 to 0.02 mol/g, particularly 0.001 to 0.01 mol/g, in the organohydrogenpolysiloxane. It is preferable to If the amount of Si—H groups is too large, the degree of crosslinking may become too high, resulting in a highly viscous grease.

The absolute viscosity of component (B) at 25° C. is not particularly limited, but is preferably 0.5 to 1,000,000 mPa·s, more preferably 1 to 100,000 mPa·s. The organohydrogenpolysiloxane of component (B) preferably has 2 to 500, preferably 3 to 300 silicon atoms (or degree of polymerization) per molecule.

In the silicone composition of the present invention, the molar ratio (Si-H/Si-Vi) of the silicon-bonded alkenyl groups in component (A) to the Si--H groups in component (B) is 2 to 10. It includes a reaction product obtained by reacting within a range. The (A) component and the (B) component are reacted so as to have such a range. More preferably, the molar ratio is 3-8. If the above molar ratio is 0<Si-H/Si-Vi<2, the silicone composition will have an increased viscosity and poor coating properties. On the other hand, when the upper limit of the molar ratio range of 10 is exceeded, the silicone composition shifts during heat cycles.

[Platinum group metal-based catalyst]
The silicone composition of the present invention preferably contains a platinum group metal catalyst, which is an addition reaction catalyst for promoting the reaction between components (A) and (B). Well-known catalysts can be mentioned. These can be used individually by 1 type or in combination of 2 or more types as appropriate. Among these, a hydrosilylation catalyst obtained by diluting a platinum complex such as chloroplatinic acid or chloroplatinate with an organopolysiloxane having a vinyl group such as an alkenyl group is preferred. This can be obtained by mixing a platinum complex and an organopolysiloxane having a vinyl group. If the platinum complex contains a solvent such as toluene, the solvent should be removed after mixing.

When the platinum group metal-based catalyst is blended, the blending amount is preferably 0.1 to 2,000 ppm, more preferably 0.5 to 1,000 ppm in terms of mass of the platinum group metal element with respect to component (A). If the amount of component (F) is too large, a non-uniform reaction may occur, resulting in the formation of a gel.

[(C) Component]
Component (C) is a thermally conductive inorganic filler selected from metal oxides and having an average particle size of 3 μm or less, and can be used singly or in combination of two or more. This inorganic filler has a large specific surface area and is a component that improves the storage elastic modulus at 150° C. by reacting with the component (E) in which alkoxy groups are present. It is also a component for improving the thermal conductivity of the silicone composition by regulating the particle size distribution of the thermally conductive inorganic filler of component (D) and increasing the blending amount by close packing.

(C) Component metal oxides include aluminum oxide, zinc oxide and magnesium oxide. These are insulating materials, industrially selectable from a wide range of grain sizes, readily available as resources, and relatively inexpensive, and are therefore widely used as heat dissipation materials.

As the inorganic filler of the component (C), amorphous, granulated powder, and spherical fillers can be used. Among them, spherical inorganic fillers are preferably used from the viewpoint of filling properties.

The average particle diameter of component (C) is 3 μm or less, more preferably 0.5 to 2.5 μm. If the average particle size is too small, the fluidity of the silicone composition may be reduced, failing to obtain good coating performance. In the present invention, the average particle diameter of the components (C) and (D) is measured by a laser diffraction/scattering method, for example, a volume cumulative average measured by Microtrac MT3300EX, a particle size analyzer manufactured by Nikkiso Co., Ltd. Particle size value D ₅₀ (or median diameter).

The amount of component (C) to be blended is preferably 50 to 4,000 parts by mass, more preferably 300 to 3,000 parts by mass, per 100 parts by mass of components (A) and (B). If the amount of component (C) is too small, the resulting silicone composition may be misaligned or the thermal conductivity may be lowered. It may be difficult to apply. In addition, (C) component is good also as a mixture previously heat-mixed with (E) component with (D) component.

[(D) Component]
Component (D) is a thermally conductive inorganic filler having an average particle size of 5 μm or more selected from metal oxides, and can be used singly or in combination of two or more. This inorganic filler is the main heat conduction path component.

(D) Component metal oxides include aluminum oxide, zinc oxide, magnesium oxide and silicon oxide. Aluminum oxide, zinc oxide, and magnesium oxide overlap with the above component (C), but differ in average particle size.

As the inorganic filler of the component (D), amorphous, granulated powder, and spherical fillers can be used. Among them, spherical inorganic fillers are preferably used from the viewpoint of filling properties.

Component (D) has an average particle size of 5 μm or more, preferably 5 to 200 μm, more preferably 6 to 150 μm, and even more preferably 7 to 100 μm. If the average particle size is less than 5 μm, the silicone composition will be non-uniform and the resistance to slippage will be poor. If the average particle size is too large, the silicone composition may become non-uniform, resulting in poor slip resistance.

The amount of component (D) to be blended is preferably 800 to 8,000 parts by mass, more preferably 700 to 7,000 parts by mass, per 100 parts by mass of components (A) and (B). If the amount of component (D) is too small, the required thermal conductivity may not be obtained, while if it is too large, the viscosity may become high, making it difficult to evenly apply the silicone composition. There is In addition, (D) component is good also as a mixture previously heat-mixed with (E) component with (C) component.

In the silicone composition of the present invention, the total amount of components (C) and (D) is 2,000 to 8,000 parts by mass per 100 parts by mass of components (A) and (B). and preferably 1,000 to 5,000 parts by mass. If the total amount is less than 2,000 parts by mass, sufficient thermal conductivity cannot be achieved, and if it exceeds 8,000 parts by mass, sufficient coating performance cannot be obtained. The mass ratio of component (C) to component (D) ((C):(D)) is preferably 15:85 to 65:35.

[(E) component]
Component (E) is a hydrolyzable organosiloxane having an alkoxy group, and can be used alone or in combination of two or more. Addition of component (E) can reduce the viscosity of the silicone composition. In addition, component (E) maintains the fluidity of the silicone composition even when the silicone composition is highly filled with components (C) and (D), and also plays a role in imparting good handleability to this silicone composition. I have it. Furthermore, when the component (E) is applied to the solder resist substrate, in the presence of the component (F) described later, the component (E) reacts with moisture absorbed by the solder resist substrate to form a hydrolyzable organosiloxane having an alkoxy group. It also has the role of forming a shielding layer and suppressing cracks and voids in the thermally conductive silicone composition.

（式中、Ｒ⁴は独立に脂肪族不飽和結合を含有しない非置換又は置換の１価炭化水素基である。Ｘ¹、Ｘ²、Ｘ³はＲ⁴又は－Ｒ⁵－ＳｉＲ⁶ _(3-g)（ＯＲ⁷）_gで示される基であり、それぞれ異なってもよいが、少なくとも１つは－Ｒ⁵－ＳｉＲ⁶ _(3-g)（ＯＲ⁷）_gである。Ｒ⁵は酸素原子又は炭素数１～４のアルキレン基、Ｒ⁶は独立に脂肪族不飽和結合を含有しない非置換又は置換の１価炭化水素基であり、Ｒ⁷は独立に炭素数１～４のアルキル基もしくはアルコキシアルキル基、又はアシル基であり、ｇは１～３の整数である。ａ及びｂはそれぞれ１≦ａ≦１，０００、０≦ｂ≦１，０００である。） Component (E) includes an organopolysiloxane represented by the following general formula (3), and preferably contains a trifunctional hydrolyzable organopolysiloxane.

(wherein R ⁴ is independently an unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturation; X ¹ , X ² and X ³ are R ⁴ or -R ⁵ -SiR ⁶ _{(3 -g)} a group represented by (OR ⁷ ) _g , each of which may be different, but at least one is -R ⁵ -SiR ⁶ _(3-g) (OR ⁷ ) _g , where R ⁵ is an oxygen atom or an alkylene group having 1 to 4 carbon atoms, R ⁶ is independently an unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bonds, and R ⁷ is independently an alkyl group having 1 to 4 carbon atoms or an alkoxyalkyl group or an acyl group, g is an integer of 1 to 3, and a and b are 1≦a≦1,000 and 0≦b≦1,000, respectively.)

（式中、Ｒ⁴は独立に脂肪族不飽和結合を含有しない非置換又は置換の１価炭化水素基であり、Ｒ⁷は独立に炭素数１～４のアルキル基もしくはアルコキシアルキル基、又はアシル基であり、ｃは５～１００の整数であり、ｇは１～３の整数である。）
で表されるオルガノポリシロキサン、特に２５℃における絶対粘度が０．００５～１００ｍＰａ・ｓのオルガノポリシロキサンが好ましい。 As the component (E), the following general formula (4)

(wherein R ⁴ is independently an unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, and R ⁷ is independently an alkyl or alkoxyalkyl group having 1 to 4 carbon atoms, or an acyl group, c is an integer of 5 to 100, and g is an integer of 1 to 3.)
Particularly preferred is an organopolysiloxane having an absolute viscosity of 0.005 to 100 mPa·s at 25°C.

In the above formulas (3) and (4), R ⁴ is independently an unsubstituted or substituted group containing no aliphatic unsaturated bond, preferably having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 1 to 3 monovalent hydrocarbon group, examples of which include straight-chain alkyl groups, branched-chain alkyl groups, cyclic alkyl groups, aryl groups, aralkyl groups, and halogenated alkyl groups. Linear alkyl groups include, for example, methyl, ethyl, propyl, hexyl, and octyl groups. Branched chain alkyl groups include, for example, isopropyl, isobutyl, tert-butyl and 2-ethylhexyl groups. Cyclic alkyl groups include, for example, a cyclopentyl group and a cyclohexyl group. Aryl groups include, for example, a phenyl group and a tolyl group. Examples of aralkyl groups include 2-phenylethyl group and 2-methyl-2-phenylethyl group. Halogenated alkyl groups include, for example, 3,3,3-trifluoropropyl, 2-(nonafluorobutyl)ethyl and 2-(heptadecafluorooctyl)ethyl groups. R ⁴ is preferably a methyl group or a phenyl group.

R ⁵ is an oxygen atom or an alkylene group having 1 to 4 carbon atoms such as methylene, ethylene and propylene. R ⁶ is independently an unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bond, and examples thereof are the same as those exemplified for R ⁴ above.

R ⁷ above is independently an alkyl group having 1 to 4 carbon atoms, an alkoxyalkyl group, or an acyl group. Examples of the alkyl group include alkyl groups having 1 to 4 carbon atoms similar to those exemplified for R ⁴ . Examples of alkoxyalkyl groups include methoxyethyl and methoxypropyl groups. As the acyl group, for example, an acyl group having 2 to 8 carbon atoms is preferable, and examples thereof include an acetyl group and an octanoyl group. ^R7 is preferably an alkyl group, more preferably a methyl group or an ethyl group.
a and b are as described above, preferably a+b is 5-150 and c is an integer of 5-100, preferably 10-50. g is an integer of 1 to 3, preferably 3; It is preferable to have 1 to 6, particularly 3 or 6, OR ⁷ groups in the molecule.

Preferred specific examples of the component (E) include the following.

The blending amount of component (E) is preferably 25 to 400 parts by mass, more preferably 50 to 350 parts by mass, per 100 parts by mass of components (A) and (B). If it is less than 25 parts by mass, the silicone composition may become too viscous to be ejected.
The amount of component (E) to be blended with respect to a total of 100 parts by mass of components (C) and (D) is preferably 4.8 to 9.2 parts by mass, and 5.0 to 9.1 parts by mass. is more preferred. If the amount is less than 4.8 parts by mass, the silicone composition may increase in viscosity and may not be ejected. be.

[(F) component]
Component (F) is an alkoxy condensation catalyst for forming a shielding layer on the surface of the solder resist substrate by dehydrating and condensing the hydrolyzable organosiloxane having an alkoxy group of component (E) in the composition of the present invention. is a component of
Specific examples of alkoxy condensation catalysts include alkyltin ester compounds such as dibutyltin diacetate, dibutyltin dilaurate, and dibutyltin dioctoate; Titanate such as propoxybis(acetylacetona)titanium, titanium isopropoxyoctylene glycol, diisopropoxybis(ethylacetoacetate)titanium, diisopropoxybis(methylacetoacetate)titanium, diisopropoxybis(acetylacetonate) titanium chelates such as titanium chelates such as dibutoxybis(ethylacetoacetonate)titanium, dibutoxybis(ethylacetoacetonate)titanium, dimethoxybis(ethylacetoacetonate)titanium, zinc naphthenate, zinc stearate, zinc-2-ethyloctoate, iron-2-ethylheptate Organometallic compounds such as xoate, cobalt-2-ethylhexoate, manganese-2-ethylhexoate, cobalt naphthenate, alkoxyaluminum compounds, 3-aminopropyltriethoxysilane, N-β (aminoethyl) γ -Aminoalkyl group-substituted alkoxysilanes such as aminopropyltrimethoxysilane, amine compounds such as hexylamine and dodecylamine phosphate and salts thereof, quaternary ammonium salts such as benzyltriethylammonium acetate, potassium acetate, sodium acetate, lithium oxalate Lower fatty acid salts of alkali metals such as dimethylhydroxylamine, dialkylhydroxylamine such as diethylhydroxylamine, tetramethylguanidylpropyltrimethoxysilane, tetramethylguanidylpropylmethyldimethoxysilane, tetramethylguanidylpropyltris ( Examples include silanes containing guanidyl groups such as trimethylsiloxy)silane, siloxanes (guanidine compounds), and the like, but these are not limited to one type, and two or more of them may be used as a mixture. Among them, alkyltin ester compounds, titanium chelate compounds, and guanidine compounds are preferred, and guanidine compounds are particularly preferred.

The amount of the alkoxy condensation catalyst (F) to be added is 0.01 to 1% by mass, preferably 0.02 to 0.5% by mass, based on the component (E). If the amount of the alkoxy condensation catalyst to be added is too small, a shielding layer cannot be obtained on the substrate surface when applied to the solder resist substrate, and if it is too large, it is not economical.

[Other ingredients]
The silicone composition of the present invention may contain optional components other than the above as long as they do not impair the effects of the present invention.
Fillers other than the above components (C) and (D) may be blended for the purpose of coloring, controlling fluidity, or reinforcing the silicone composition. You may use a filler individually by 1 type or in combination of 2 or more types as appropriate. Examples of fillers include clays such as wollastonite, talc, aluminum oxide, calcium sulfate, magnesium carbonate and kaolin; copper carbonates such as aluminum hydroxide, magnesium hydroxide, graphite, barite and malachite; nickel carbonates such as zalachite. barium carbonate such as witherite; strontium carbonate such as strontianite; silicates such as forsterite, sillimanite, mullite, pyrophyllite, kaolinite, vermiculite; non-reinforcing fillers such as diatomaceous earth; The surface of the filler in (1) is treated with an organosilicon compound.
When the above filler is blended, the amount to be blended is preferably 100 parts by mass or less per 100 parts by mass in total of the components (A) and (B).

A tackifier may be added to improve the adhesion of the silicone composition. The tackifiers can be used singly or in combination of two or more. Specific examples of tackifiers include alkylalkenyldialkoxysilanes such as methylvinyldimethoxysilane, ethylvinyldimethoxysilane, methylvinyldiethoxysilane, and ethylvinyldiethoxysilane; methylvinyldioximesilane, ethylvinyldioximesilane; alkylalkenyldioxime silanes such as; alkylalkenyldiacetoxysilanes such as methylvinyldiacetoxysilane and ethylvinyldiacetoxysilane; alkenylalkyldihydroxysilanes such as methylvinyldihydroxysilane and ethylvinyldihydroxysilane; Methoxysilane, allyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane Organotrialkoxysilanes such as silane, bis(trimethoxysilyl)propane, bis(trimethoxysilyl)hexane; triallyl isocyanurate, diallyl(3-trimethoxysilyl)isocyanurate, tris(3-trimethoxysilylpropyl)isocyanate isocyanurate compounds such as nurate, tris(3-triethoxysilylpropyl) isocyanurate, tris(3-tripropoxysilylpropyl) isocyanurate; tetraethyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetra(2-ethylhexyl) titanate, Titanium compounds such as titanium ethylacetonate and titanium acetylacetonate; ethylacetoacetate aluminum diisopropylate, aluminum tris(ethylacetoacetate), alkylacetoacetate aluminum diisopropylate, aluminum tris(acetylacetonate), aluminum monoacetylacetonate aluminum compounds such as nitratebis(ethylacetoacetate); and zirconium compounds such as zirconium acetylacetonate, zirconium butoxyacetylacetonate, zirconium bisacetylacetonate, and zirconium ethylacetoacetate.
The amount of the tackifier to be added is not particularly limited, but it is preferably 0.01 to 10 parts by mass per 100 parts by mass of the components (A) and (B).

[Method for producing thermally conductive silicone composition]
A method for producing the thermally conductive silicone composition of the present invention includes the following steps.
(I) the above components (A), (B), (C), (D), (E) and, if necessary, a platinum group metal-based catalyst, combined with alkenyl groups bonded to silicon atoms in component (A); (B) a step of obtaining a mixture by mixing so that the molar ratio (Si-H/Si-Vi) to the Si-H groups in the component is 2 to 10;
(II) a step of heating the obtained mixture at 100 to 180° C. for 30 minutes to 4 hours to react the components (A) and (B);
(III) A step of mixing (F) an alkoxy condensation catalyst with the reaction mixture obtained above at room temperature (25° C., hereinafter the same) for 10 to 60 minutes.

(I) the above components (A), (B), (C), (D), (E) and, if necessary, a platinum group metal-based catalyst, combined with alkenyl groups bonded to silicon atoms in component (A); Step of obtaining a mixture by mixing so that the molar ratio (Si—H/Si—Vi) with Si—H groups in component (B) is 2 to 10 The platinum group metal-based catalyst is mixed in the above-mentioned proportion according to the above. Other ingredients may be added as needed. The mixing device is not particularly limited, and Trimix, Twinmix, Planetary Mixer (both registered trademarks of mixers manufactured by Inoue Seisakusho Co., Ltd.), Ultra Mixer (registered trademarks of mixers manufactured by Mizuho Industry Co., Ltd.), Hibis Mix using a mixer such as Dispermix (registered trademark of mixer manufactured by Tokushu Kika Kogyo Co., Ltd.). The temperature at which the liquid substance and the inorganic filler are mixed is not particularly limited, and it is preferable to mix them at room temperature for 10 to 60 minutes. Moreover, you may mix under reduced pressure (for example, 70 mmHg).

(II) A step of heating the obtained mixture at 100 to 180° C. for 30 minutes to 4 hours to react the above components (A) and (B). ) at 100 to 180° C., preferably 110 to 170° C., for 30 minutes to 4 hours, preferably 1 to 3 hours, to react with the components. Further, heating may be performed under reduced pressure (for example, 70 mmHg).

(III) Step of mixing the reaction mixture obtained above with (F) an alkoxy condensation catalyst at room temperature for 10 to 60 minutes To the reaction mixture obtained above, add (F) an alkoxy condensation catalyst at room temperature for 10 to 60 minutes , preferably for 10 to 30 minutes, the thermally conductive silicone composition of the present invention can be obtained.
In the present invention, (F) the alkoxy condensation catalyst is a component for dehydration condensation of the hydrolyzable organosiloxane having an alkoxy group of component (E) in the resulting thermally conductive silicone composition. it is necessary not to (F) If the alkoxy condensation catalyst is mixed together with the components (A) to (E) and heated, the hydrolyzable organosiloxane having an alkoxy group of the component (E) will undergo dehydration condensation. A large amount of gel is generated and becomes non-uniform.

[Thermal conductive silicone composition]
The absolute viscosity at 25° C. of the thermally conductive silicone composition of the present invention obtained by the above method is 50 to 500 Pa·s, preferably 150 to 400 Pa·s. If the absolute viscosity is less than 50 Pa·s, the silicone composition drips during application, resulting in poor application properties. Furthermore, sedimentation of components (C) and (D) may occur during long-term storage. On the other hand, when it exceeds 500 Pa·s, the coatability deteriorates and the production efficiency decreases. The absolute viscosity of the silicone composition can be adjusted, for example, by adjusting the degree of cross-linking of components (A) and (B), the amounts of components (C), (D) and (E), or by the manufacturing method described above. By doing so, the above range can be obtained.

The amount of Si—H residues per unit volume of the thermally conductive silicone composition of the present invention is 1×10 ⁻⁶ to 1×10 ⁻³ mol/cm ³ , and 1×10 ⁻⁵ to 5×1×10 −5 mol/cm 3 . 10 ^-4 mol/cm ³ is preferred. If the amount of Si—H residues is less than 1×10 ⁻⁶ mol/cm ³ , for example, when the following displacement test is performed while sandwiching between adherends, chemical interaction with the adherend occurs. Since the number of functional groups (Si—H groups) is reduced, misalignment is more likely to occur. On the other hand, if it exceeds 1×10 ⁻³ mol/cm ³ , the Si—H/Si—Vi balance is lost, resulting in a composition with a low crosslink density and a tendency to shift. Therefore, the amount of components (C) and (D) is too large, and the amount of component (E) is too small, resulting in a silicone composition with inferior coating performance. The amount of Si—H residues per unit volume of the silicone composition is, for example, the balance of Si—H/Si—Vi in components (A) and (B) between 2 and 10, (A)+(B) The above range can be obtained by setting the ratio of the component (E) to the component and the ratio of the component (C)+(D) to the component (A)+(B) within the ranges described above. The amount of Si—H residues per unit volume of the silicone composition is obtained by subtracting the number of moles of Si—Vi in component (A) from the number of moles of Si—H in component (B). By dividing by the total volume, the amount of Si—H residues per unit volume can be calculated.

The thermal conductivity of the thermally conductive silicone composition of the present invention is preferably 2 W/mK or higher, more preferably 3 W/mK or higher. Although the upper limit is not particularly limited, it can be 20 W/mK or less. Since it has such excellent thermal conductivity, it is suitable for heat dissipation. The thermal conductivity is the value at 25° C. measured by the hot disk method in accordance with ISO 22007-2.

The thermally conductive silicone composition of the present invention can be suitably used for heat-generating components mounted on solder resist substrates. Exhaust heat by applying directly to heat-generating parts, as well as exhausting heat from the solder resist surface on the back side of heat-generating parts, and applying around the solder resist part on the same side as heat-generating parts to exhaust heat. can be used for As industrial application fields, it can be suitably used for electronic parts for vehicles, electronic equipment such as personal computers, portable communication terminals, and the like.

EXAMPLES The present invention will be specifically described below by showing examples and comparative examples, but the present invention is not limited to the following examples. The absolute viscosities of the components (A), (B) and (E) and the silicone composition in the examples are the values at 25° C. measured with the following Malcom viscometer.

The ingredients used in the examples and comparative examples are described below. In addition, the bonding order of each siloxane unit shown in parentheses is not limited to the following.
(A) Alkenyl group-containing organopolysiloxane A-1: dimethylpolysiloxane with absolute viscosity of 100 mPa·s and dimethylvinylsiloxy group-blocked at both ends of the molecular chain (vinyl group content: 0.040 mol/100 g)
A-2: A dimethylpolysiloxane having an average structure with an absolute viscosity of 5,000 mPa s in which one end of the molecular chain is blocked with a dimethylvinylsiloxy group and the other end is blocked with a trimethylsiloxy group (vinyl group content: 0.006 mol/ 100g)

(B) Organohydrogenpolysiloxane B-1: Organohydrogenpolysiloxane represented by the following formula with an absolute viscosity of 12 mPa·s (Si—H group content: 0.0055 mol/g)

B-2: Organohydrogenpolysiloxane represented by the following formula with an absolute viscosity of 17 mPa·s (Si—H content: 0.0013 mol/g)

(C) Thermally conductive inorganic filler C-1: 2 types of zinc oxide (JIS standard, average particle size 1 μm, irregular shape)
C-2: Aluminum oxide powder (average particle size 1 μm, spherical)

(D) Thermally conductive inorganic filler D-1: aluminum oxide powder (average particle size 10 μm, spherical)

(E) Hydrolyzable Organosiloxane E-1: Organopolysiloxane represented by the following formula with an absolute viscosity of 30 mPa·s

Hydrosilylation catalyst obtained by the following method 8.0 g of chloroplatinic acid H ₂ PtCl ₆ .6H ₂ O (37.6% by weight platinum) are placed in a 100 mL reaction flask equipped with a reflux condenser, thermometer and stirring device, 40.0 grams of ethanol and 16.0 grams of divinyltetramethyldisiloxane were then added. After reacting with heating at 70° C. for 50 hours, the reaction mixture was neutralized for 2 hours by gradually adding 16 g of sodium hydrogen carbonate while stirring at room temperature (25° C.). The reaction mixture was subjected to suction filtration, the filtrate was distilled off under reduced pressure to substantially remove ethanol and excess divinyltetramethyldisiloxane, and then diluted with toluene to make the total amount 600 g (containing 0.5% by mass of platinum). .
To the platinum-vinylsiloxane complex toluene solution described above, 290 g of dimethylpolysiloxane having an absolute viscosity of 600 mPa s and having both molecular chain ends blocked with dimethylvinylsiloxy groups was added and stirred, and toluene was distilled off under reduced pressure at 60 ° C./20 torr. A hydrosilylation catalyst (containing 1.0% by mass of platinum) was obtained by removing toluene from the product.

(F) Alkoxy condensation catalyst F-1: Tetramethylguanidylpropyltrimethoxysilane F-2: Dibutyltin diacetate F-3: Diisopropoxybis(ethylacetoacetate)titanium

[Method for preparing solder resist substrate]
Solder resist PSR-800 AUS410 (manufactured by Taiyo Yuden Co., Ltd.) is spin-coated to a thickness of 30 μm on an FR-4 substrate (glass epoxy material R1705, copper foil 70/70 μm, manufactured by Panasonic Electric Works Co., Ltd.). and cured at 150° C./1 hour. Thereafter, the back surface was spin-coated with a solder resist to a thickness of 30 μm by the same method, and the back surface was cured at 150° C. for 1 hour to obtain a double-sided coated substrate. Saturated moisture absorption was performed in a storage environment of 25°C/50% RH.

[Examples 1 to 8, Comparative Examples 1 to 3, 5 to 7]
(I) Components (A), (B), (C), (D), and (E) and a platinum group metal-based catalyst were blended in the blending amounts shown in Tables 1 and 2, and the mixture was mixed at room temperature using a planetary mixer. (25° C.) and mixed under reduced pressure (70 mmHg) for 60 minutes.
(II) The mixture obtained in (I) was heated to 165° C. and mixed under reduced pressure (70 mmHg) for 120 minutes to obtain a reaction mixture.
(III) To the reaction mixture in which the crosslinking reaction of the components (A) and (B) obtained in (II) was completed, the alkoxy condensation catalyst (F) in the amount shown in Tables 1 and 2 was added at room temperature and normal pressure. A silicone composition was made by mixing for 15 minutes.

[Comparative Example 4]
A silicone composition was obtained in the same manner as in Example 5, except that component (F) was mixed at the same time in step (I) above and heated in step (II).

Properties of the silicone composition were measured by the following methods.
[Thermal conductivity measurement]
Measurement was performed at 25° C. using TPA-501 manufactured by Kyoto Electronics Industry Co., Ltd.

[Absolute viscosity measurement]
The absolute viscosity is the value at 25° C., and the measurement was performed using a Malcom viscometer (type PC-10AA). In the application process of the silicone composition, it is considered practically unusable to have an absolute viscosity of more than 500 Pa·s.

[Slipping Test of Silicone Composition]
0.325 mL of the silicone composition was applied to a glass plate, a 1 mm spacer was inserted, and sandwiched between glass plates to prepare a disk-shaped sample with a diameter of about 20 mm and a thickness of 1 mm.
Place the sample sandwiched between glass so that the disk is vertical, and perform a cycle test under the conditions of -40 ° C / 30 minutes ⇔ 150 ° C / 30 minutes, and the state after 250 cycles. Observed. If the disk-shaped silicone composition was displaced from the original position on the glass plate, it was evaluated as "displaced". When the silicone composition was placed vertically and no deviation occurred from the original position, it was evaluated as "no deviation". Such a situation is preferred.

[Void property test of silicone composition]
0.067 mL of the silicone composition is applied onto the solder resist substrate, a 0.4 mm spacer is inserted, and a disk shape with a diameter of about 10 mm and a thickness of 0.4 mm is sandwiched between the glass plate and the solder resist substrate prepared above. A sample of
The sample sandwiched between the glass and the solder resist substrate was arranged so that the disk was horizontal, placed in a dryer preheated to 150° C., and stored at 150° C. for 90 minutes. If the disc-shaped silicone composition had cracks or voids that accounted for 5% or more of the total area, it was classified as "Cracks/voids present". A case where no cracks or voids occurred even after being stored at 150° C. for 90 minutes was defined as “no cracks/voids”. This situation is preferred because there is no reduction in heat transfer paths per unit area.

The results in Tables 1 and 2 show that the thermally conductive silicone composition of the present invention has an absolute viscosity of 500 Pa·s or less at 25°C, and therefore has excellent coatability and thermal conductivity. Even when it is put in, there is no deviation during the cooling/heating cycle, and no cracks or voids occur in the void test. are doing.

The thermally conductive silicone composition of the present invention not only has excellent thermal conductivity, but also has good void resistance and misalignment resistance to solder resist substrates, so it can be used from electric and electronic parts that generate heat during use. Suitable for heat removal.

Claims (6)

(A) an organopolysiloxane having a silicon-bonded alkenyl group and (B) an organohydrogenpolysiloxane are combined with the silicon-bonded alkenyl groups in component (A) and the Si— in component (B). a reaction product reacted with H groups at a molar ratio (Si—H/Si—Vi) of 2 to 10;
(C) a thermally conductive inorganic filler with an average particle size of 3 μm or less selected from metal oxides;
(D) a thermally conductive inorganic filler having an average particle size of 5 μm or more selected from metal oxides;
(E) a hydrolyzable organosiloxane having an alkoxy group, and (F) an alkoxy condensation catalyst that is a silane or siloxane containing a guanidyl group : 0.01 to 1% by mass relative to component (E)
and the total amount of components (C) and (D) is 2,000 to 8,000 parts by mass per 100 parts by mass of components (A) and (B), and 25 A thermally conductive silicone composition having an absolute viscosity of 50 to 500 Pa·s at °C and an amount of Si—H residues per unit volume of 1×10 ⁻⁶ to 1×10 ⁻³ mol/cm ³ . The heat according to claim 1, wherein the amount of (E) the hydrolyzable organosiloxane having an alkoxy group is 25 to 400 parts by mass with respect to the total of 100 parts by mass of the components (A) and (B). A conductive silicone composition. 3. The thermally conductive silicone composition according to claim 1, which is used for solder resist substrates. (A) an organopolysiloxane having a silicon-bonded alkenyl group and (B) an organohydrogenpolysiloxane are combined with the silicon-bonded alkenyl groups in component (A) and the Si— in component (B). a reaction product reacted with H groups at a molar ratio (Si—H/Si—Vi) of 2 to 10;
(C) a thermally conductive inorganic filler with an average particle size of 3 μm or less selected from metal oxides;
(D) a thermally conductive inorganic filler having an average particle size of 5 μm or more selected from metal oxides;
(E) a hydrolyzable organosiloxane having an alkoxy group, and
(F) Alkoxy condensation catalyst: 0.01 to 1% by mass relative to component (E)
and the total amount of components (C) and (D) is 2,000 to 8,000 parts by mass per 100 parts by mass of components (A) and (B), and 25 A method for producing a thermally conductive silicone composition having an absolute viscosity at °C of 50 to 500 Pa·s and an amount of Si—H residues per unit volume of 1×10 ⁻⁶ to 1×10 ⁻³ mol/cm ³ . There is
(I) (A) an organopolysiloxane having an alkenyl group bonded to a silicon atom, (B) an organohydrogenpolysiloxane, and (C) a thermally conductive inorganic filler having an average particle size of 3 μm or less selected from metal oxides; (D) a thermally conductive inorganic filler having an average particle size of 5 μm or more selected from metal oxides, (E) a hydrolyzable organosiloxane having an alkoxy group, and, if necessary, a platinum group metal-based catalyst, (A) a step of mixing the alkenyl groups bonded to silicon atoms in the component and the Si—H groups in the component (B) so that the molar ratio (Si—H/Si—Vi) is 2 to 10 to obtain a mixture; ,
(II) heating the resulting mixture at 100 to 180° C. for 30 minutes to 4 hours to react components (A) and (B);
(III) A method for producing a thermally conductive silicone composition comprising the step of mixing (F) an alkoxy condensation catalyst with the reaction mixture obtained above at room temperature for 10 to 60 minutes. (E) The heat according to claim 4, wherein the amount of hydrolyzable organosiloxane having an alkoxy group is 25 to 400 parts by mass with respect to a total of 100 parts by mass of components (A) and (B). A method for making a conductive silicone composition. 6. The method for producing a thermally conductive silicone composition according to claim 4 or 5, which is used for solder resist substrates.