Thermally conductive addition-curable silicone composition and method for producing thermally conductive addition-curable silicone composition

Abstract

To provide: a thermally conductive addition-curable silicone composition that has good storage stability at 25°C and that requires only a short time for the storage modulus G' to exceed the loss modulus G'' when heated and cured; and a method for producing the same.SOLUTION: A thermally conductive addition-curable silicone composition contains (A) an organopolysiloxane having at least one aliphatic unsaturated hydrocarbon group per molecule and having a kinematic viscosity at 25°C of 60-100,000 mm2 / s, (B) a thermally conductive filler containing amorphous aluminum nitride powder and amorphous zinc oxide powder, (C) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms per molecule, (D) a platinum group metal catalyst, (E) an organopolysiloxane represented by the specified general formula (1), and (F) one or more addition curing reaction control agents selected from the group consisting of acetylene compounds, nitrogen compounds, organophosphorus compounds, oxime compounds and organic chloro compounds.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a thermally conductive addition-curable silicone composition and a method for producing the same.

Background Art

[0002] As a common problem in electronic component packages and power modules, heat generation during operation and the resulting performance degradation are widely known, and various heat dissipation techniques are used as means to solve this problem. In particular, a technique of arranging a cooling member near the heat generating part and bringing the two into close contact, and then efficiently removing heat from the cooling member to dissipate heat is common.

[0003] At this time, if there is a gap between the heat generating part and the cooling member, the heat transfer coefficient will decrease due to the presence of air with poor thermal conductivity, and the temperature of the heat generating member will not drop sufficiently. In order to prevent the presence of such air and improve heat conduction, a heat dissipation material with good thermal conductivity and followability to the surface of the member, such as heat dissipation grease or a heat dissipation sheet, is used.

[0004] As a heat countermeasure for actual electronic component packages and power modules, heat dissipation grease that is thin, compressible, and has excellent invasiveness into the gap between the heat generating part and the cooling member is suitable from the viewpoint of heat dissipation performance. Furthermore, by heat-curing after compression to a desired thickness, it is difficult to generate outflow (pumping out) of the heat dissipation grease due to expansion and contraction caused by the heat history of repeated heat generation and cooling of the heat generating part, and an addition-curable heat dissipation grease that can enhance the reliability of electronic component packages and power modules is particularly useful (for example, Patent Document 1).

[0005] In recent years, with the development of larger areas and more complex structures in electronic component packages and power modules, very large warpage may occur in electronic component packages and power modules. In electronic component packages and power modules with significant warpage, it is important to precisely control the curability of addition-curing type heat dissipation grease. Specifically, when heat-cured, it is preferable that the time required for the storage modulus G' to exceed the loss modulus G'' is shorter. Generally, this can be achieved by increasing the amount of platinum group metal catalyst. However, as a trade-off, the shelf life at 25°C may deteriorate, resulting in a shorter pot life.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] That is, there is a need for a thermally conductive addition-curing type silicone composition in which the time required for the storage modulus G' to exceed the loss modulus G'' when heat-cured is short and the shelf life at 25°C is good.

[0008] The present invention has been made in view of the above problems, and an object thereof is to provide a thermally conductive addition-curing type silicone composition in which the time required for the storage modulus G' to exceed the loss modulus G'' when heat-cured is short and the shelf life at 25°C is good, and a method for producing the same.

Means for Solving the Problems

[0009] To solve the above problems, in the present invention, a thermally conductive addition-curing type silicone composition, (A) having at least one aliphatic unsaturated hydrocarbon group in one molecule and having a kinematic viscosity at 25°C of 60 to 100,000 mm 2An organopolysiloxane in an amount of 1.5 to 90% by mass based on the total composition, (B) A thermally conductive filler containing amorphous aluminum nitride powder and amorphous zinc oxide powder: in an amount of 8 to 96% by mass based on the total composition, (C) An organohydrogenpolysiloxane having hydrogen atoms bonded to two or more silicon atoms in one molecule: in an amount such that the number of Si-H groups in component (C) is 0.5 to 10 with respect to the total number of aliphatic unsaturated hydrocarbon groups in component (A), (D) A platinum group metal catalyst: an effective amount, (E) An organopolysiloxane represented by the following general formula (1): in an amount of 0.5 to 10% by mass based on the total composition, [Chemical formula] (In the formula, R 1 represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, which may have a substituent and represents a monovalent hydrocarbon group having no aliphatic unsaturated bond, and each R 1 may be the same or different. m is an integer of 5 to 100.) (F) One or more addition-curing reaction control agents selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chloro compounds: an effective amount provided is a thermally conductive addition-curing silicone composition characterized by containing the above.

[0010] Such a thermally conductive addition-curing silicone composition has a short time required for the storage elastic modulus G' to exceed the loss elastic modulus G'' when heat-cured, and has good storage stability at 25°C.

[0011] In this case, it is preferable that the thermally conductive addition-curing silicone composition of the present invention is characterized in that the above component (C) is an organohydrogenpolysiloxane having two epoxy ring-containing organic groups in one molecule.

[0012] With such a thermally conductive addition-curing silicone composition, the heat-generating part and the cooling member can be brought into good close contact with each other.

[0013] Furthermore, when measuring the storage modulus G' and the loss modulus G'' of the above-mentioned thermally conductive addition-curing silicone composition by using a viscoelasticity measuring device capable of measuring the shear elasticity, after raising the temperature from 25°C to 150°C at a rate of 5°C / min and then maintaining the temperature at 150°C for 7,200 seconds, it is preferable that the time required for the storage modulus G' to exceed the loss modulus G'' is 500 seconds or less, and it takes 5 days or more for the viscosity of the above-mentioned thermally conductive addition-curing silicone composition to exceed 1,000 Pa·s when stored at 25°C.

[0014] With such a thermally conductive addition-curing silicone composition, since the time required for the storage modulus G' to exceed the loss modulus G'' when heat-cured is short and the storage stability at 25°C is good, it can be suitably used for electronic component packages and power modules with large warpage.

[0015] Furthermore, the present invention provides (A) An organopolysiloxane having at least 1 aliphatic unsaturated hydrocarbon group in 1 molecule and having a kinematic viscosity at 25°C of 60 to 100,000 mm 2 / s in an amount of 1.5 to 90% by mass based on the whole composition, (B) A thermally conductive filler containing amorphous aluminum nitride powder and amorphous zinc oxide powder in an amount of 8 to 96% by mass based on the whole composition, (C) An organohydrogenpolysiloxane having hydrogen atoms bonded to 2 or more silicon atoms in 1 molecule, in an amount such that the number of Si-H groups in component (C) is 0.5 to 10 with respect to the total number of aliphatic unsaturated hydrocarbon groups in component (A), (D) A platinum group metal catalyst: an effective amount, (E) An organopolysiloxane represented by the following general formula (1) in an amount of 0.5 to 10% by mass based on the whole composition,

Chemical formula

[0016] According to such a method for producing a thermally conductive addition-curing silicone composition of the present invention, when heat-cured, the time required for the storage elastic modulus G' to exceed the loss elastic modulus G'' is short, and the storage stability at 25°C is good. Thus, a thermally conductive addition-curing silicone composition of the present invention can be produced.

[0017] Further, the method for producing a thermally conductive addition-curing silicone composition of the present invention uses a viscoelasticity measuring device capable of measuring shear elasticity. After raising the temperature from 25°C to 150°C at a rate of 5°C / min and then maintaining at 150°C for 7,200 seconds, when measuring the storage elastic modulus G' and the loss elastic modulus G'' of the thermally conductive addition-curing silicone composition, the time required for the storage elastic modulus G' to exceed the loss elastic modulus G'' is 500 seconds or less, and when the thermally conductive addition-curing silicone composition is stored at 25°C, it takes 5 days or more for the viscosity to exceed 1,000 Pa·s. The above production method is preferably characterized by obtaining such a composition.

[0018] According to such a method for producing a thermally conductive addition-curing silicone composition of the present invention, a thermally conductive addition-curing silicone composition that can be suitably used for electronic component packages or power modules with large warpage can be surely obtained. [Advantages of the Invention]

[0019] The thermally conductive addition-curing silicone composition of the present invention has a short time required for the storage elastic modulus G' to exceed the loss elastic modulus G'' when heat-cured, and good storage stability at 25°C. As a result, it can be suitably used for electronic component packages and power modules with large warpage. Further, with the manufacturing method of the thermally conductive addition-curing silicone composition of the present invention, a thermally conductive addition-curing silicone composition that can be suitably used for electronic component packages and power modules with large warpage can be surely obtained.

Embodiments for Carrying Out the Invention

[0020] As described above, there has been a demand for the development of a thermally conductive addition-curing silicone composition having a short time required for the storage elastic modulus G' to exceed the loss elastic modulus G'' when heat-cured and good storage stability at 25°C.

[0021] As a result of intensive studies on the above problems, the present inventors have found that a thermally conductive addition-curing silicone composition characterized by containing the above components (A) to (F) has a storage elastic modulus G' and a loss elastic modulus G'' of the thermally conductive addition-curing silicone composition measured using a viscoelasticity measuring device capable of measuring shear elasticity, after heating from 25°C to 150°C at a rate of 5°C / min and then maintaining at 150°C for 7,200 seconds. When measured, the time required for the storage elastic modulus G' to exceed the loss elastic modulus G'' is 500 seconds or less, and when the thermally conductive addition-curing silicone composition is stored at 25°C, it takes 5 days or more until the viscosity exceeds 1,000 Pa·s, and thus the present invention has been completed.

[0022] That is, the present invention is a thermally conductive addition-curing silicone composition, (A) An organopolysiloxane having at least one aliphatic unsaturated hydrocarbon group in one molecule and having a kinematic viscosity at 25°C of 60 to 100,000 mm 2 / s: an amount of 1.5 to 90% by mass based on the total composition, (B) Amorphous aluminum nitride powder and amorphous zinc oxide powder as the thermal conductivity filler: in an amount of 8 to 96% by mass based on the whole composition, (C) Organohydrogenpolysiloxane having hydrogen atoms bonded to two or more silicon atoms in one molecule: in an amount such that the number of Si-H groups in component (C) is 0.5 to 10 with respect to the total number of aliphatic unsaturated hydrocarbon groups in component (A), (D) Platinum group metal catalyst: in an effective amount, (E) Organopolysiloxane represented by the following general formula (1): in an amount of 0.5 to 10% by mass based on the whole composition, [Chemical formula] (In the formula, R 1 represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, which may have a substituent and represents a monovalent hydrocarbon group having no aliphatic unsaturated bond, and each R 1 may be the same or different. m is an integer of 5 to 100.) (F) One or more addition-curing reaction control agents selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds and organic chloro compounds: in an effective amount It is a thermally conductive addition-curing silicone composition characterized by containing the same.

[0023] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0024] [Component (A)] Component (A) has at least one, preferably 1 to 100, more preferably 2 to 50 aliphatic unsaturated hydrocarbon groups in one molecule, and has a kinematic viscosity at 25 ° C of 60 to 100,000 mm 2 / s and is an organopolysiloxane.

[0025] The aliphatic unsaturated hydrocarbon group is preferably a monovalent hydrocarbon group having 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, and even more preferably an alkenyl group, which has an aliphatic unsaturated bond. For example, alkenyl groups such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group, and octenyl group can be mentioned. Particularly preferably, it is a vinyl group. The aliphatic unsaturated hydrocarbon group may be bonded to either the silicon atom at the molecular chain end or the silicon atom in the middle of the molecular chain, or may be bonded to both.

[0026] As the organic group other than the aliphatic unsaturated hydrocarbon group bonded to the silicon atom of the organopolysiloxane, it is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, and even more preferably 1 to 8 carbon atoms. For example, alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, and decyl group; aryl groups such as phenyl group, tolyl group, xylyl group, and naphthyl group; aralkyl groups such as benzyl group, phenylethyl group, and phenylpropyl group, or those in which a part or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, bromine, and chlorine, or cyano groups, etc. For example, chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, cyanoethyl group, etc. can be mentioned. Particularly preferably, they are methyl group and trifluoropropyl group.

[0027] The kinematic viscosity of the above organopolysiloxane at 25 °C is 60 to 100,000 mm 2 / s, preferably 100 to 30,000 mm 2 / s. When the kinematic viscosity is less than 60 mm 2 / s, the physical properties of the thermally conductive addition-curable silicone composition of the present invention will deteriorate, and when it exceeds 100,000 mm 2 / s, the stretchability of the above silicone composition will be poor.

[0028] In the present invention, the kinematic viscosity is the value at 25°C measured by an Ubbelohde-type Ostwald viscometer (hereinafter the same).

[0029] The molecular structure of the organopolysiloxane is not particularly limited as long as it has the above properties, and examples thereof include a linear structure, a branched-chain structure, a partially branched structure, or a linear structure having a cyclic structure. In particular, it preferably has a linear structure in which the main chain consists of a repetition of diorganosiloxane units and both ends of the molecular chain are blocked with triorganosiloxy groups. The organopolysiloxane having the linear structure may partially have a branched structure or a cyclic structure.

[0030] The blending amount of component (A) is 1.5 to 90% by mass, preferably 2 to 20% by mass, based on the total composition. If it is more than 90% by mass, there is a risk of poor thermal conductivity, and if it is less than 1.5% by mass, the viscosity of the thermally conductive addition-curing silicone composition of the present invention may increase significantly and the workability may decrease.

[0031] The organopolysiloxane can be used alone or in combination of two or more.

[0032] [Component (B)] Component (B) is a thermally conductive filler containing amorphous aluminum nitride powder and amorphous zinc oxide powder in order to obtain a thermally conductive addition-curing silicone composition that achieves high thermal conductivity, has a short time required for the storage elastic modulus G' to exceed the loss elastic modulus G'' when heat-cured, and can achieve good storage stability at 25°C. In the present invention, the shapes of the aluminum nitride powder and the zinc oxide powder are amorphous, preferably polyhedral.

[0033] When using polyhedral aluminum nitride powder, the curability is improved even with a small amount of platinum group metal catalyst, and it becomes compatible with the pot life. Also, due to the physical entanglement of the polyhedral aluminum nitride powder, G' is improved. The sub-filler zinc oxide powder is preferably amorphous in consideration of the thermal conductivity.

[0034] Moreover, the component (B) is preferably a combination of aluminum nitride powder as the large particle component and zinc oxide powder as the small particle component. The average particle size of the aluminum nitride powder as the large particle component is preferably in the range of 1 to 300 μm, more preferably in the range of 3 to 200 μm, still more preferably in the range of 5 to 150 μm, and even more preferably in the range of 6 to 50 μm. The average particle size of the zinc oxide powder as the small particle component is preferably in the range of 0.01 μm to 10 μm, more preferably 0.1 to 5 μm. If the average particle size of the aluminum nitride powder as the large particle component is in the range of 1 to 300 μm and the average particle size of the zinc oxide powder as the small particle component is in the range of 0.01 μm to 10 μm, the viscosity of the thermally conductive addition-curing silicone composition of the present invention will not become too high, it will have excellent stretchability, and the resulting silicone composition will be uniform. The ratio of the aluminum nitride powder as the large particle component to the zinc oxide powder as the small particle component is not particularly limited, and a range of 9:1 to 1:9 (mass ratio) is preferred. Within this range, it is preferable because appropriate viscosity and thermal conductivity can be achieved simultaneously.

[0035] The average particle size can be determined, for example, as the volume-based average value (median diameter) in the particle size distribution measurement by the laser light diffraction method.

[0036] The blending amount of the component (B) is 8 to 96% by mass based on the whole composition, preferably 40 to 95.5% by mass, and more preferably 70 to 95% by mass. If it is more than 96% by mass, the thermally conductive addition-curing silicone composition of the present invention will have poor stretchability, and if it is less than 8% by mass, it will have poor thermal conductivity.

[0037] [Component (C)] (C) component is an organohydrogenpolysiloxane having hydrogen atoms bonded to two or more silicon atoms in one molecule (Si-H groups), preferably hydrogen atoms bonded to 2 to 100 silicon atoms (Si-H groups), more preferably hydrogen atoms bonded to 2 to 50 silicon atoms (Si-H groups). The organohydrogenpolysiloxane may be any one as long as the Si-H groups in the molecule can undergo an addition reaction with the aliphatic unsaturated hydrocarbon groups of the above-mentioned (A) component in the presence of a platinum group metal catalyst to form a crosslinked structure.

[0038] The molecular structure of the above organohydrogenpolysiloxane is not particularly limited as long as it has the above properties, and examples include linear structures, branched-chain structures, cyclic structures, partially branched structures, or linear structures having a cyclic structure. Linear structures and cyclic structures are preferred.

[0039] The kinematic viscosity of the above organohydrogenpolysiloxane at 25°C is preferably 1 to 1,000 mm 2 / s, more preferably 10 to 300 mm 2 / s. If the kinematic viscosity is in the range of 1 to 1,000 mm 2 / s, the physical properties of the thermally conductive addition-curable silicone composition of the present invention are good, and the silicone composition is rich in stretchability.

[0040] Examples of the organic group bonded to the silicon atom of the organohydrogenpolysiloxane include unsubstituted or substituted monovalent hydrocarbon groups other than aliphatic unsaturated hydrocarbon groups. In particular, they are unsubstituted or substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms. For example, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group, dodecyl group, aryl groups such as phenyl group, aralkyl groups such as 2-phenylethyl group, 2-phenylpropyl group, and those in which some or all of the hydrogen atoms of these are substituted with halogen atoms such as fluorine, bromine, chlorine, cyano group, epoxy ring-containing organic groups (glycidyl group or glycidyl-oxy group-substituted alkyl group), etc. Examples thereof include chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, cyanoethyl group, 2-glycidoxyethyl group, 3-glycidoxypropyl group, and 4-glycidoxybutyl group. Among these, a methyl group and an epoxy ring-containing organic group are preferable. In particular, an epoxy ring-containing organic group is preferable because it can make the heat generating part and the cooling member adhere well to each other.

[0041] The above organohydrogenpolysiloxane may be used alone or in combination of two or more, and at least one kind is preferably an organohydrogenpolysiloxane having two epoxy ring-containing organic groups and two or more hydrogen atoms bonded to silicon atoms in one molecule.

[0042] The blending amount of the organohydrogenpolysiloxane as the component (C) is such that the number of SiH groups in the component (C) is 0.5 to 10 with respect to the total number of aliphatic unsaturated hydrocarbon groups in the component (A), preferably 0.7 to 7.5, more preferably 1.0 to 5.0. When the amount of the component (C) is less than 0.5, the addition reaction does not proceed sufficiently and the crosslinking becomes insufficient. Further, when the amount of the component (C) exceeds 10, the crosslinked structure may become non-uniform, or the storage stability of the thermally conductive addition-curable silicone composition of the present invention may be significantly deteriorated.

[0043] [Component (D)] (D) component is a platinum group metal catalyst and functions to promote the addition reaction of the above-described components. As the platinum group metal catalyst, a conventionally known one used in the addition reaction can be used. For example, platinum-based, palladium-based, and rhodium-based catalysts can be mentioned, and among them, platinum or a platinum compound that is relatively easily available is preferable. For example, elemental platinum, platinum black, chloroplatinic acid, platinum-olefin complex, platinum-alcohol complex, platinum coordination compound, etc. can be mentioned. The platinum group metal catalyst may be used alone or in combination of two or more kinds.

[0044] (D) The blending amount of the component is an effective amount as a catalyst, that is, an effective amount necessary to promote the addition reaction and cure the thermally conductive addition-curable silicone composition of the present invention. Preferably, based on the mass in terms of platinum group metal atoms, it is preferably 0.01 to 10 ppm, more preferably 0.1 to 5 ppm, and still more preferably 0.2 to 3 ppm with respect to the whole composition. If the amount of the above catalyst is 0.01 to 10 ppm, the effect as a catalyst can be sufficiently obtained, it is economical, and the storage stability at 25 °C is good, so it is preferable.

[0045] In addition, the platinum group metal catalyst of (D) component may be diluted with organo(poly)siloxane, toluene, etc. for better dispersibility in the thermally conductive addition-curable silicone composition of the present invention.

[0046] [(E) component] (E) component is used to treat the surface of the thermally conductive filler and plays a role in assisting the high filling of the filler. [Chemical formula] (In the formula, R 1 is a monovalent hydrocarbon group having 1 to 18 carbon atoms, which may have a substituent and represents a monovalent hydrocarbon group having no aliphatic unsaturated bond, and each R 1 may be the same or different. m is an integer of 5 to 100.)

[0047] The above R 1is a monovalent hydrocarbon group having 1 to 18 carbon atoms, which may have a substituent, preferably a monovalent saturated aliphatic hydrocarbon group which may have a substituent, more preferably a monovalent aromatic hydrocarbon group which may have a substituent, and still more preferably a monovalent saturated aliphatic hydrocarbon group which may have a substituent.

[0048] Specific examples of the monovalent saturated aliphatic hydrocarbon group which may have a substituent include linear alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, etc., branched-chain alkyl groups such as isopropyl group, isobutyl group, tert-butyl group, isopentyl group, neopentyl group, etc., cycloalkyl groups such as cyclopentyl group, cyclohexyl group, cycloheptyl group, etc., and halogen-substituted alkyl groups such as chloromethyl group, 3-chloropropyl group, 3,3,3-trifluoropropyl group, bromopropyl group, etc. As for the number of carbon atoms, it is preferably 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and still more preferably 1 to 6 carbon atoms.

[0049] Specific examples of the monovalent aromatic hydrocarbon group which may have a substituent include aryl groups such as phenyl group, tolyl group, etc., aralkyl groups such as benzyl group, 2-phenylethyl group, etc., and halogen-substituted aryl groups such as α,α,α-trifluorotolyl group, chlorobenzyl group, etc. As for the number of carbon atoms, it is preferably 6 to 10 carbon atoms, more preferably 6 to 8 carbon atoms, and still more preferably 6 carbon atoms.

[0050] Among these, the above R 1 is preferably a methyl group, an ethyl group, a 3,3,3-trifluoropropyl group, or a phenyl group, more preferably a methyl group, an ethyl group, or a phenyl group, and particularly preferably a methyl group.

[0051] m is an integer from 5 to 100, preferably from 5 to 80, more preferably from 10 to 60. If the value of m is less than 5, oil bleeding from the thermally conductive addition-curable silicone composition of the present invention cannot be suppressed, and the pump-out resistance is poor. Also, if the value of m is 100 or more, the wettability with the filler is not sufficient, the viscosity of the silicone composition increases, and the coating workability deteriorates.

[0052] The blending amount of component (E) is 0.5 to 10% by mass, preferably 1.0 to 8.0% by mass, based on the total composition. When the blending amount is less than 0.5% by mass or exceeds 10% by mass, the thermally conductive silicone composition of the present invention cannot be brought into an appropriate viscosity range, and the pump-out resistance becomes poor.

[0053] Component (E) may be used alone or in combination of two or more.

[0054] [Component (F)] Component (F) is a reaction control agent that suppresses the progress of the hydrosilylation reaction at room temperature and can be added to extend the shelf life and pot life. As the reaction control agent, conventionally known reaction control agents used in thermally conductive addition-curable silicone compositions can be used. Examples thereof include acetylene compounds such as acetylene alcohols (e.g., ethynyl methyl decyl carbinol, 1-ethynyl-1-cyclohexanol, 3,5-dimethyl-1-hexyne-3-ol), various nitrogen compounds such as tributylamine, tetramethylethylenediamine, and benzotriazole, organic phosphorus compounds such as triphenylphosphine, oxime compounds, and organic chloro compounds.

[0055] (F) The blending amount of the component may be an effective amount as a reaction controller, that is, an effective amount necessary to obtain a desired shelf life and pot life. Preferably, it is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the component (A). If the amount of the reaction controller is 0.05 to 5 parts by mass, a sufficient desired shelf life and pot life can be obtained, and there is no risk of deterioration of the curability of the thermally conductive addition-curing silicone composition.

[0056] Also, the reaction controller may be diluted with an organo(poly)siloxane, toluene, etc. for better dispersibility in the thermally conductive addition-curing silicone composition of the present invention before use.

[0057] [Other components] The thermally conductive addition-curing silicone composition of the present invention may contain an organo(poly)siloxane having no reactivity such as methylpolysiloxane to adjust the strength and viscosity of the composition. Further, for the purpose of imparting adhesiveness to the silicone composition, a hydrolyzable organopolysiloxane, various modified silicones, and a hydrolyzable organosilane may be blended. Further, a solvent for adjusting the viscosity of the silicone composition may be blended. Further, in order to prevent deterioration of the silicone composition, a conventionally known antioxidant such as 2,6-di-tert-butyl-4-methylphenol may be contained as necessary. Further, dyes, pigments, flame retardants, anti-settling agents, or thixotropy improvers, etc. can be blended as necessary.

[0058] The thermally conductive addition-curing silicone composition of the present invention, which contains the components (A) to (F) and, if necessary, the above-mentioned other components, is heated from 25°C to 150°C at a rate of 5°C / min using a viscoelasticity measuring device capable of measuring shear elasticity, and then maintained at 150°C for 7,200 seconds. When measuring the storage modulus G' and the loss modulus G'' of the thermally conductive addition-curing silicone composition, the time required for the storage modulus G' to exceed the loss modulus G'' is 500 seconds or less, and when the thermally conductive addition-curing silicone composition is stored at 25°C, it can take 5 days or more until the viscosity exceeds 1,000 Pa·s.

[0059] For such a thermally conductive addition-curing silicone composition, when heat-cured, the time required for the storage modulus G' to exceed the loss modulus G'' is short, and the storage stability at 25°C is good. As a result, it can be suitably used for electronic component packages and power modules with large warpage.

[0060] In the thermally conductive addition-curing silicone composition of the present invention, the time required for the storage modulus G' to exceed the loss modulus G'' is measured by creating a program in which the thermally conductive addition-curing silicone composition of the present invention is applied with a thickness of 2 mm between two parallel plates with a diameter of 2.5 cm, then the applied plates are heated from 25°C to 150°C at a rate of 5°C / min, and then maintained at 150°C for 7,200 seconds, and reading the time required for the storage modulus to exceed the loss modulus. For the measurement, a viscoelasticity measuring device (ARES-G2: manufactured by TA Instruments) is used.

[0061] [Process for producing a thermally conductive addition-curing silicone composition] The manufacturing method of the thermally conductive addition-curing silicone composition in the present invention will be described. The manufacturing method of the thermally conductive addition-curing silicone composition in the present invention is not particularly limited, but includes a step of preparing each component containing the above-mentioned components (A) to (F) and, if necessary, other components in addition to these.

[0062] The above-prepared components (A) to (F) and, if necessary, other components added thereto are mixed using, for example, mixers such as trimix, twin mix, planetary mixer (all registered trademarks of Inoue Manufacturing Co., Ltd. mixers), ultra mixer (registered trademark of Mizuhou Industry Co., Ltd. mixer), hibiscus mix (registered trademark of Primix Corporation mixer), etc. for 3 minutes to 24 hours, more preferably 5 minutes to 12 hours, and particularly preferably 10 minutes to 6 hours. Also, degassing may be performed during mixing, and mixing is carried out while heating in the range of 40 to 170°C. If it is less than 40°C, the dispersion of component (B) becomes poor, and if it exceeds 170°C, component (E) may be deteriorated, which is not preferable.

[0063] In the present invention, it is preferable from the viewpoint that the thermally conductive addition-curing silicone composition of the present invention exhibits good thermal conductivity to mix components (A), (B) and (E) at 170°C in advance and then mix components (C), (D) and (F) at 25°C.

[0064] The viscosity of the thermally conductive addition-curing silicone composition of the present invention, measured at 25°C, is preferably 10 to 1,000 Pa·s, more preferably 20 to 700 Pa·s, and still more preferably 40 to 500 Pa·s. When the viscosity is in the range of 10 to 1,000 Pa·s, shape retention becomes easy, silver powder does not settle, and workability such as easy discharge and coating becomes easy.

[0065] The viscosity of the thermally conductive addition-curing silicone composition of the present invention is measured at 25°C using a Malcolm viscometer (type PC-1T) (10 rpm with rotor A, shear rate 6 [1 / s]).

[0066] Further, the thermally conductive addition-curing silicone composition of the present invention usually has a thermal conductivity of 0.5 to 100 W / m·K, but preferably has a thermal conductivity of 4.0 W / m·K or more in order to exhibit excellent heat dissipation performance when mounted on an electronic component package or a power module.

[0067] The thermal conductivity is measured using a TPS-2500S manufactured by Kyoto Electronics Industry Co., Ltd. with the thermally conductive addition-curing silicone composition wrapped in plastic wrap.

[0068] When heat-curing the thermally conductive addition-curing silicone composition of the present invention, the curing conditions are not particularly limited, but are preferably 80 to 200 °C, more preferably 100 to 180 °C, for 15 minutes to 4 hours, preferably 30 minutes to 2 hours.

[0069] In addition, the manufacturing method of the thermally conductive addition-curing silicone composition of the present invention uses a viscoelasticity measuring device capable of measuring shear elasticity, and after raising the temperature from 25 °C to 150 °C at 5 °C / min, while maintaining at 150 °C for 7,200 seconds, when measuring the storage elastic modulus G' and loss elastic modulus G'' of the thermally conductive addition-curing silicone composition, the time required for the storage elastic modulus G' to exceed the loss elastic modulus G'' is 500 seconds or less, and when the thermally conductive addition-curing silicone composition is stored at 25 °C, it can be manufactured to require 5 days or more until the viscosity exceeds 1,000 Pa·s.

Examples

[0070] Hereinafter, the present invention will be specifically described using examples and comparative examples, but the present invention is not limited thereto.

[0071] The kinematic viscosity indicates the value at 25 °C measured by an Ubbelohde type Ostwald viscometer.

[0072] The following components (A) to (F) for preparing the thermally conductive addition-curing silicone composition of the present invention, and component (G) as other components were prepared. [Component (A)] A-1: Dimethylpolysiloxane blocked at both ends with dimethylvinylsilyl groups and having a kinematic viscosity of 30,000 mm 2 / s at 25 °C (Vinyl group content = 0.00004 mol / g) A-2: Dimethylpolysiloxane blocked at both ends with dimethylvinylsilyl groups and having a kinematic viscosity of 10,000 mm 2Dimethylpolysiloxane of / s (Vinyl group content = 0.00005 mol / g) A-3: Dimethylpolysiloxane blocked at both ends with dimethylvinylsilyl groups and having a kinematic viscosity at 25°C of 5,000 mm 2 / s (Vinyl group content = 0.00007 mol / g) A-4: Dimethylpolysiloxane blocked at both ends with dimethylvinylsilyl groups and having a kinematic viscosity at 25°C of 600 mm 2 / s (Vinyl group content = 0.00014 mol / g) A-5: Dimethylpolysiloxane blocked at both ends with trivinylsilyl groups and having a kinematic viscosity at 25°C of 1,500 mm 2 / s (Vinyl group content = 0.00026 mol / g)

[0073] [Component (B)] B-1: Polyhedral aluminum nitride powder with an average particle size of 20 μm and a specific surface area of 0.3 m 2 / g B-2: Polyhedral aluminum nitride powder with an average particle size of 8 μm and a specific surface area of 0.7 m 2 / g B-3: Polyhedral zinc oxide powder with an average particle size of 0.4 μm and a specific surface area of 3.5 m 2 / g b-4: Spherical aluminum powder with an average particle size of 24 μm and a specific surface area of 0.2 m 2 / g b-5: Spherical aluminum powder with an average particle size of 12 μm and a specific surface area of 0.4 m 2 / g b-6: Spherical aluminum nitride powder with an average particle size of 30 μm and a specific surface area of 0.08 m 2 / g

[0074] [Component (C)] C-1: Methylhydrogen dimethylpolysiloxane represented by the following formula (2) (SiH content = 0.0043 mol / g) [Chemical formula] C-2: Methylhydrogen dimethylpolysiloxane represented by the following formula (3) (SiH content = 0.0055 mol / g)

Chem.

Chem.

Chem.

Chem.

[0075] [(Component (D))] D-1: Solution obtained by dissolving a platinum-divinyltetramethyldisiloxane complex in the same dimethylpolysiloxane as the above A-4 (platinum atom content: 1% by mass)

[0076] [(Component (E))] E-1: One-terminal trimethoxysilyl group-blocked dimethylpolysiloxane represented by the following formula (7)

Chem.

[0077] [(Component (F))] F-1: 1-Ethynyl-1-cyclohexanol represented by the following formula (8)

Chem.

[0078] [Component (G)] G-1: Organosilane represented by the following formula (9) [Chemical formula]

[0079] [Examples 1 to 4, Comparative Examples 1 to 5] [Preparation of thermally conductive addition-curing silicone composition] The above components (A) to (G) were blended in the blending amounts shown in Tables 1 and 2 below by the method shown below to prepare a thermally conductive addition-curing silicone composition. In Tables 1 and 2, SiH / SiVi is the ratio of the total number of SiH groups in component (C) to the total number of vinyl groups in component (A).

[0080] Components (A), (B), (E), and (G) were added to a 5-liter planetary mixer (manufactured by Inoue Manufacturing Co., Ltd.) and mixed at 170°C for 1 hour. After cooling to 40°C or lower, components (C), (D), and (F) were then added and mixed until uniform to prepare a thermally conductive addition-curing silicone composition. For the prepared thermally conductive addition-curing silicone composition, the viscosity, thermal conductivity, time required for the storage elastic modulus to exceed the loss elastic modulus, and storage stability at 25°C shown below were measured. The results are shown in Tables 1 to 2.

[0081] [Viscosity] The absolute viscosity of each thermally conductive addition-curing silicone composition was measured at 25°C using a Malcolm viscometer (type PC-1T) (10 rpm with rotor A, shear rate 6 [1 / s]). [Thermal conductivity] Each thermally conductive addition-curing silicone composition was wrapped with kitchen wrap, and the thermal conductivity was measured using a TPS-2500S manufactured by Kyoto Electronics Industry Co., Ltd. [Time required for the storage elastic modulus to exceed the loss elastic modulus] Between two parallel plates with a diameter of 2.5 cm, each thermally conductive addition-curing silicone composition was applied with a thickness of 2 mm. After heating the applied plates from 25°C to 150°C at a rate of 5°C / min, a program was created to maintain them at 150°C for 7,200 seconds, and the time required for the storage modulus to exceed the loss modulus was read. For the measurement, a viscoelasticity measuring device (ARES-G2: manufactured by TA Instruments) was used. [Storage stability at 25°C] Each thermally conductive addition-curing silicone composition was enclosed in a high-density polyethylene container and stored at 25°C, and the time until the viscosity exceeded 1,000 Pa·s was measured.

[0082]

Table 1

[0083]

Table 2

[0084] From the results in Tables 1 and 2, it was found that for the thermally conductive addition-curing silicone compositions of Examples 1 to 4 that meet the requirements of the present invention, the time required for the storage modulus G' to exceed the loss modulus G'' is 500 seconds or less, and it takes 5 days or more until the viscosity exceeds 1,000 Pa·s when stored at 25°C.

[0085] On the other hand, in the thermally conductive addition-curing silicone compositions of Comparative Examples 1, 2, and 5, although it takes 5 days or more until the viscosity exceeds 1,000 Pa·s when stored at 25°C, it was found that the time required for the storage elastic modulus G' to exceed the loss elastic modulus G'' is 500 seconds or more. Also, in the thermally conductive addition-curing silicone composition of Comparative Example 3, the time required for the storage elastic modulus G' to exceed the loss elastic modulus G'' is 500 seconds or more, and it was found that the viscosity exceeds 1,000 Pa·s in less than 5 days when stored at 25°C. Furthermore, in the thermally conductive addition-curing silicone composition of Comparative Example 4, although the time required for the storage elastic modulus G' to exceed the loss elastic modulus G'' is 500 seconds or less, it was found that the viscosity exceeds 1,000 Pa·s in less than 5 days when stored at 25°C.

[0086] As described above, according to the present invention, using the above viscoelasticity measuring device, under the above temperature conditions, the time required for the storage elastic modulus G' to exceed the loss elastic modulus G'' is as short as 500 seconds or less, and when stored at 25°C, it was found that a thermally conductive addition-curing silicone composition of the present invention with good storage stability, which takes 5 days or more until the viscosity exceeds 1,000 Pa·s, can be obtained. As a result, the thermally conductive addition-curing silicone composition of the present invention can be suitably used for electronic component packages and power modules with large warpage. Also, it was found that with the manufacturing method of the thermally conductive addition-curing silicone composition of the present invention, a thermally conductive addition-curing silicone composition that can be suitably used for electronic component packages and power modules with large warpage can be surely obtained.

[0087] Note that the present invention is not limited to the above-described embodiments. The above embodiments are examples, and any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same operational effects is included in the technical scope of the present invention.

Claims

1. A heat-conductive addition-curing silicone composition comprising: (A) An organopolysiloxane having at least one aliphatic unsaturated hydrocarbon group in one molecule and having a kinematic viscosity at 25°C of 60 to 100,000 mm 2 / s, in an amount of 1.5 to 90% by mass based on the total composition; (B) A heat-conductive filler containing amorphous aluminum nitride powder and amorphous zinc oxide powder, in an amount of 8 to 96% by mass based on the total composition; (C) An organohydrogenpolysiloxane having hydrogen atoms bonded to two or more silicon atoms in one molecule, wherein the number of Si-H groups in component (C) is 0.5 to 10 with respect to the total number of aliphatic unsaturated hydrocarbon groups in component (A); (D) A platinum group metal catalyst: an effective amount; (E) An organopolysiloxane represented by the following general formula (1), in an amount of 0.5 to 10% by mass based on the total composition; 【Chemical Formula 1】 (In the formula, R 1 represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, which may have a substituent and represents a monovalent hydrocarbon group having no aliphatic unsaturated bond, and each R 1 may be the same or different. m is an integer of 5 to 100.) (F) One or more addition-curing reaction control agents selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chloro compounds: an effective amount A heat-conductive addition-curing silicone composition characterized by containing the above components.

2. The heat-conductive addition-curing silicone composition according to claim 1, wherein the component (C) is an organohydrogenpolysiloxane having two epoxy ring-containing organic groups in one molecule.

3. The heat-conductive addition-curing silicone composition Using a viscoelasticity measuring device capable of measuring shear elasticity, after heating from 25°C to 150°C at a rate of 5°C / min and then maintaining at 150°C for 7,200 seconds, when measuring the storage modulus G' and loss modulus G'' of the thermally conductive addition-curing silicone composition, the time required for the storage modulus G' to exceed the loss modulus G'' is 500 seconds or less, and when the thermally conductive addition-curing silicone composition is stored at 25°C, it takes 5 days or more until the viscosity exceeds 1,000 Pa·s. The thermally conductive addition-curing silicone composition according to claim 1 or 2, characterized in that.

4. (A) An organopolysiloxane having at least one aliphatic unsaturated hydrocarbon group in one molecule and having a kinematic viscosity at 25°C of 60 to 100,000 mm 2 / s, in an amount of 1.5 to 90% by mass based on the total composition; (B) A thermally conductive filler containing amorphous aluminum nitride powder and amorphous zinc oxide powder, in an amount of 8 to 96% by mass based on the total composition; (C) An organohydrogenpolysiloxane having hydrogen atoms bonded to two or more silicon atoms in one molecule, in an amount such that the number of Si-H groups in component (C) is 0.5 to 10 with respect to the total number of aliphatic unsaturated hydrocarbon groups in component (A); (D) A platinum group metal catalyst: an effective amount (E) An organopolysiloxane represented by the following general formula (1), in an amount of 0.5 to 10% by mass based on the total composition; 【Chemical formula 2】 (In the formula, R 1 represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, which may have a substituent and represents a monovalent hydrocarbon group having no aliphatic unsaturated bond, and each R 1 may be the same or different. m is an integer of 5 to 100.) (F) One or more addition-curing reaction control agents selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds, and organic chloro compounds: an effective amount The step of preparing each component; A step of mixing the above components (A) to (F) while heating at 40 to 170°C, A method for producing a thermally conductive addition-curing silicone composition, comprising:

5. By the method for producing the thermally conductive addition-curing silicone composition, Using a viscoelasticity measuring device capable of measuring shear elasticity, after heating from 25°C to 150°C at a rate of 5°C / min and then maintaining at 150°C for 7,200 seconds, when measuring the storage elastic modulus G' and loss elastic modulus G'' of the thermally conductive addition-curing silicone composition, the time required for the storage elastic modulus G' to exceed the loss elastic modulus G'' is 500 seconds or less, and when the thermally conductive addition-curing silicone composition is stored at 25°C, it takes 5 days or more until the viscosity exceeds 1,000 Pa·s. The method for producing a thermally conductive addition-curing silicone composition according to claim 4, characterized in that such a composition is obtained.

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