Aluminum nitride filled thermally conductive silicone composition

Abstract

The composition comprises: (a)(i) 30 to 400 MPa * (b) an alkyltrialkoxysilane and / or mono-trialkoxysiloxy terminated dimethylpolysiloxane treating agent; and (c) a filler mixture containing (i) 40% by weight or more of spherical and irregularly shaped AlN particles, both having an average particle size of 30 microns. and (ii) 25-35 wt. % of spherical Al2O3 particles having an average size of 1-5 micrometers, (iii) 10-15 wt. % of additional thermally conductive filler having an average size of 0.1-0.5 micrometers, and (iv) optionally BN filler having an average size greater than 20 micrometers, wherein the filler mixture is 90-97 wt. % based on the weight of the composition, unless otherwise specified.

Description

[Technical Field]

[0001] The present invention relates to a thermally conductive silicone composition containing an aluminum nitride filler.

[0002] Introduction The miniaturization and increasing power of electronic devices has led to an increased demand in industry for thermally conductive materials useful for dissipating heat generated by such devices. For example, the telecommunications industry is experiencing a generational shift to 5G networks, which requires smaller, more integrated electrical devices and more power (from 600 watts to 1200 watts). The heat generated by the high power in compact devices must be efficiently dissipated or the devices will be damaged. Thermally conductive interface materials are often used in electronic devices to thermally couple heat-generating and heat-dissipating components. To efficiently transfer heat between coupled components, thermally conductive compositions desirably have a thermal conductivity of at least 8.0 watts / meter, as measured according to ASTM method D5470. * Kelvin (W / m * The thermally conductive material has a thermal conductivity of 0.62 MPa (0.62 K). At the same time, as electronic devices become smaller, it becomes more important to accurately and precisely apply the thermal conductivity to the appropriate components during rapid manufacturing processes. In that regard, it is desirable for the thermally conductive material to have an extrusion rate (ER) of greater than 40 grams per minute (g / min) when measured at 0.62 megapascals (90 pounds per square inch) pressure using a standard 30 cubic centimeter EFD syringe package using the procedure described herein below.

[0003] It is difficult to simultaneously achieve such high thermal conductivity and high extrusion rates in thermally conductive materials. Increasing the amount of thermally conductive filler can increase thermal conductivity, but it also increases viscosity, suppressing extrusion rates. Because boron nitride is a highly thermally conductive filler, it is believed that it can increase the thermal conductivity of a composition at a concentration low enough to avoid excessive viscosity. However, because boron nitride has a plate-like shape, even at concentrations of 40% by volume or higher, the viscosity of the thermally conductive composition becomes too high to achieve an ER of more than 40 g / min.

[0004] ER greater than 40g / min and at least 8.0W / m * There remains a need to identify thermally conductive compositions that can simultaneously achieve thermal conductivities of 1000K. Summary of the Invention

[0005] The present invention provides an extrusion rate of greater than 40 g / min and at least 8.0 W / m * The thermally conductive material simultaneously achieves a thermal conductivity of 0.1 K. Furthermore, the thermally conductive material is reactive and can be cured to become a cured thermally conductive material.

[0006] The present invention relates, in part, to a method for producing a composite of aluminum nitride fillers having a particle size of 30 micrometers or greater, which can be blended with a specific amount of spherical aluminum oxide fillers having a particle size of 1-5 micrometers and an additional amount of fillers having an average particle size of 0.1-0.5 micrometers, and which has an ER of greater than 40 g / min and a thermal conductivity of at least 8.0 W / m, even in the absence of boron nitride. * This is the result of the discovery that a thermally conductive material can be provided that simultaneously achieves a thermal conductivity of 1000K.

[0007] In a first aspect, the present invention provides a thermally conductive composition comprising: (a)(i) 30 to 400 millipascals *(b) a filler treating agent comprising one or both of an alkyltrialkoxysilane and a mono-trialkoxysiloxy-terminated dimethylpolysiloxane; and (c) a thermally conductive filler mixture comprising: (a) a vinyldimethylsiloxy-terminated polydimethylpolysiloxane having a viscosity in the range of 0.5:1 to 1:1; (b) a vinyldimethylsiloxy-terminated polydimethylpolysiloxane having a viscosity in the range of 0.5:1 to 1:1; ...c) a thermally conductive filler mixture comprising: (a) a vinyldimethylsiloxy-terminated polydimethylpolysiloxane having a viscosity in the range of 0.5:1 to 1:1; a thermally conductive composition comprising: (i) an aluminum nitride filler, wherein the spherical aluminum nitride filler having a particle size of 30 μm or greater is present in a concentration of 40-60 wt% of the total weight of the aluminum nitride filler having a particle size of 30 μm or greater; (ii) 25 wt%-35 wt% of spherical aluminum oxide particles having an average particle size of 1-5 micrometers; (iii) 10 wt%-15 wt% of an additional thermally conductive filler having an average particle size of 0.1-0.5 micrometers; and (iv) optionally, a thermally conductive filler comprising a boron nitride filler having an average particle size greater than 20 micrometers, wherein the weight percentage of each thermally conductive filler is based on the weight of the composition unless otherwise specified, and the total amount of the thermally conductive filler mixture is 90-97 wt% of the weight of the composition.

[0008] In a second aspect, the invention is an article comprising the thermally conductive composition of the first aspect on another material.

[0009] The thermally conductive compositions of the present invention are useful, for example, as thermally conductive interface materials between components of electronic devices. DETAILED DESCRIPTION OF THE INVENTION

[0010] Test methods, unless a date is given with the test method number, refer to the test method most recent as of the priority date of this document. Reference to a test method includes both a reference to the testing society and the test method number. The following test method abbreviations and identifiers apply herein: ASTM refers to ASTM International methods, EN refers to European Norm, DIN refers to Deutsches Institut für Normung, ISO refers to the International Organization for Standards, and UL refers to the Underwriters Laboratory.

[0011] Products identified by trade names refer to compositions available under those trade names as of the priority date of this document.

[0012] "Plurality" means two or more. "And / or" means "and, or alternatively." All ranges are inclusive of endpoints unless otherwise indicated. All weight percent (wt%) values ​​are by weight of the composition and all volume percent (vol%) values ​​are by volume of the composition unless otherwise specified.

[0013] The "viscosity" of a particular polysiloxane is measured according to ASTM D445 using a glass capillary Cannon-Fenske viscometer at 25 degrees Celsius (°C) unless otherwise specified.

[0014] standard 1 H, 13 C, and 29 Determine the chemical structure of the polysiloxane by Si nuclear magnetic resonance (NMR) analysis. Determine the average particle size of the filler particles as the median particle size (D50) using a laser diffraction particle size analyzer (CILAS920 particle size distribution analyzer or Beckman Coulter LS 13 320 SW) according to the operating software.

[0015] The thermally conductive composition itself comprises a curable silicone composition comprising a vinyldimethylsiloxy-terminated polydimethylpolysiloxane (PDMS), a silicon hydride (SiH)-functional crosslinker, and a hydrosilylation catalyst. The relative concentration of the vinyldimethylsiloxy-terminated PDMS and the SiH-functional crosslinker is such that the molar ratio of SiH functionality from the crosslinker to vinyl functionality is in the range of 0.5:1 to 1:1, and can be 0.5:1 or greater, 0.6:1 or greater, 0.7:1 or greater, 0.8:1 or greater, or even 0.9:1 or greater, while being 1:1 or less, 0.9:1 or less, 0.8:1 or less, 0.7:1 or less, or even 0.6:1 or less.

[0016] Vinyldimethylsiloxy-terminated PDMS is 30 mPascals * seconds (mPa * s) or more, preferably 45 mPa * s or more, 60mPa * Viscosity of 90mPa or more * s or more, 100mPa * s or more, 120mPa * s or more, 140mPa * s or more, 160mPa * s or more, and even 180mPa * s or more, and at the same time, * s or less, 300mPa * s or less, 200mPa * s or less, 180mPa * s or less, and even 160mPa * s or less, 140mPa * s or less, 120mPa * s or less, 100mPa * s or less, 80mPa * s or less, and even 60mPa * The viscosity must be less than 1 / 2 s. If the viscosity is too high, the thermally conductive composition will be too viscous to achieve the desired extrusion speed. If the viscosity is too low, the thermally conductive composition will be at risk of having too little viscosity, resulting in insufficient mechanical properties and the risk of choke formation.

[0017] The vinyldimethylsiloxy-terminated PDMS desirably has the following chemical structure (I): Vi(CH3)2SiO-[(CH3)2SiO] n -Si(CH3)2Vi (I) (where "Vi" refers to the vinyl group (-CH=CH2), and n refers to the average number of dimethylsiloxane units, which is the degree of polymerization (DP) of the vinyldimethylsiloxy-terminated PDMS.) n is selected to achieve the desired viscosity of the vinyldimethylsiloxy-terminated PDMS. Typically, n is 25 or greater, and can be 30 or greater, 35 or greater, 40 or greater, 45 or greater, 50 or greater, 60 or greater, 70 or greater, 80 or greater, or even 90 or greater, while typically n is 200 or less, 190 or less, 180 or less, 170 or less, 160 or less, 150 or less, 140 or less, 130 or less, 120 or less, 100 or less, 90 or less, 80 or less, 70 or less, 60 or less, or even 50 or less.

[0018] Desirably, the vinyldimethylsiloxy-terminated PDMS contains 1.2 to 1.4 weight percent vinyl functionality.

[0019] Suitable divinyl PDMS materials can be made by ring-opening polymerization of cyclosiloxanes using terminating vinyl endblockers, as taught in U.S. Patent No. 5,883,215(A). Suitable commercially available divinyl PDMSs include the polysiloxane available from Gelest under the designation DMS-V 21.

[0020] The SiH-functional crosslinker is a polysiloxane containing SiH functionality. Desirably, the SiH-functional crosslinker contains two or more, or even three or more, SiH functionalities per molecule. Preferably, the SiH-functional crosslinker has a SiH concentration of 0.1 wt.% or more, 0.2 wt.% or more, 0.3 wt.% or more, 0.4 wt.% or more, 0.5 wt.% or more, and may be 0.6 wt.% or more, 0.7 wt.% or more, 0.8 wt.% or more, or even 0.9 wt.% or more, based on the weight of the SiH-functional crosslinker, and at the same time, may be 1.0 wt.% or less, 0.9 wt.% or less, 0.8 wt.% or less, 0.7 wt.% or less, 0.6 wt.% or less, 0.5 wt.% or less, or even 0.4 wt.% or less, or 0.3 wt.% or less.

[0021] The SiH functional crosslinker may desirably comprise one or more polysiloxanes having a chemical structure selected from (II) and (III). H(CH3)2SiO-[(CH3)2)SiO)] x -Si(CH3)2H (II) (CH3)3SiO-[(CH3)HSiO] y [(CH3)2)SiO] z -Si(CH3)3(III) [In the formula, The subscript x has a value ranging from 10 to 100, and can be 10 or more, 15 or more, 20 or more, 30 or more, 40 or more, 50 or more, 60 or more, 70 or more, or even 80 or more, and at the same time, can generally be 100 or less, 90 or less, 80 or less, 70 or less, 60 or less, 50 or less, 40 or less, 30 or less, or even 20 or less; the subscript y has a value ranging from 3 to 30, and can be 3 or more, 4 or more, 5 or more, 10 or more, 15 or more, 20 or more, or even 25 or more, and at the same time can generally be 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, or even 4 or less; The subscript z has a value ranging from 3 to 100, and can be 3 or more, 5 or more, 10 or more, 15 or more, 20 or more, 30 or more, 40 or more, 50 or more, 60 or more, 70 or more, or even 80 or more, while generally being 100 or less, 90 or less, 80 or less, 70 or less, 60 or less, 50 or less, 40 or less, 30 or less, 20 or less, 10 or less, 5 or less, or even 4 or less.

[0022] Suitable commercially available SiH functional crosslinkers include those available under the designations HMS-071, MHS-301 and DMS-H11, all available from Gelest.

[0023] The hydrosilylation catalyst can be any hydrosilylation catalyst. Desirably, the hydrosilylation catalyst comprises a platinum-based catalyst such as Speier's catalyst (HPtCl) and / or Karstedt's catalyst (an organoplatinum compound derived from a divinyl-containing disiloxane and also identified as a platinum-divinyltetramethyldisiloxane complex or a 1,3-diethenyl-1,1,3,3 tetramethyldisiloxane platinum complex). The hydrosilylation catalyst can be encapsulated (typically in a phenyl resin) or non-encapsulated. The concentration of the hydrosilylation catalyst is typically present in a concentration of 0.01 wt.% or more, 0.02 wt.% or more, 0.03 wt.% or more, 0.04 wt.% or more, or even 0.05 wt.% or more, relative to the weight of the thermally conductive composition, while being present in a concentration of 0.10 wt.% or less, 0.09 wt.% or less, 0.08 wt.% or less, 0.07 wt.% or less, or even 0.06 wt.% or less.

[0024] The thermally conductive composition also includes one or more filler treating agents, which include one or both of an alkyltrialkoxysilane and a mono-trialkoxysiloxy-terminated dimethylpolysiloxane.

[0025] The alkyltrialkoxysilane is desirably a 6-20 carbon (C6-20) alkyltrimethoxysilane, preferably a C8-C12 alkyltrimethoxysilane, and may be n-decyltrimethoxysilane. Suitable alkyltrialkoxysilanes include n-decyltrimethoxysilane, available from Dow, Inc. as DOWSIL™ Z-6210 silane (DOWSIL is a trademark of The Dow Chemical Company) or from Gelest under the designation SID2670.0.

[0026] An example of a suitable mono-trialkoxysiloxy terminated dimethylpolysiloxane has the chemical structure (IV). (CH3)3SiO-[(CH3)2SiO] a -Si(OR')3(IV) (wherein the subscript a has a value of 20 or greater, and can be 30 or greater, 40 or greater, 50 or greater, 60 or greater, 70 or greater, 80 or greater, or even 90 or greater, while typically being 150 or less, 140 or less, 130 or less, 120 or less, 110 or less, 100 or less, 90 or less, 80 or less, 70 or less, 60 or less, 50 or less, 40 or less, or even 30 or less.) An a of 20 or greater (degree of polymerization of 20 or greater) is preferred because it increases the stability of the mono-trialkoxysiloxy-terminated dimethylpolysiloxane compared to when a is less than 20. However, shorter chain lengths are more efficient at reducing viscosity than longer chain lengths, so it is desirable to maintain the value of a below 150. R' is an alkyl group, preferably containing 1 to 12 carbon atoms (C1-C12), and most preferably methyl.

[0027] Suitable mono-trialkoxysiloxy-terminated dimethylpolysiloxanes can be synthesized according to the teachings of US Patent Application Publication No. 2006 / 0100336.

[0028] Desirably, the alkyltrialkoxysilane is typically present in a concentration of 1.8 wt. % or more, 2.0 wt. % or more, 2.5 wt. % or more, 3.0 wt. % or more, or even 3.5 wt. % or more, based on the weight of the thermally conductive composition, while typically present in a concentration of 4.0 wt. % or less, 3.5 wt. % or less, or even 3.0 wt. % or less.

[0029] Additionally, or alternatively, the mono-trialkoxysiloxy-terminated dimethylpolysiloxane is desirably present in a concentration of 0.05 wt. % or more, 0.1 wt. % or more, 0.2 wt. % or more, 0.3 wt. % or more, or even 0.4 wt. % or more, based on the weight of the thermally conductive composition, and typically present in a concentration of 0.5 wt. % or less, 0.4 wt. % or less, 0.3 wt. % or less, or 0.2 wt. % or less.

[0030] The thermally conductive composition further comprises a thermally conductive filler mixture, which contains all of the thermally conductive fillers in the thermally conductive composition. The thermally conductive filler refers to a particulate that promotes heat conduction through the thermally conductive composition.

[0031] The filler mixture contains a mixture of spherical and irregularly shaped aluminum nitride particles. "Spherical" shaped particles are those with an aspect ratio of 1.0 + / - 0.2. Scanning electron microscope (SEM) imaging is used to determine the aspect ratio of particles by taking the average ratio of the longest dimension (major axis) to the shortest dimension (minor axis) of at least 10 particles. "Irregular" shaped particles have an aspect ratio other than 1.0 + / - 0.2 and have at least three faces evident by SEM imaging (distinguishing them from "plates" which have two faces).

[0032] Both spherical and irregular aluminum nitride fillers have an average particle size of 30 micrometers or more, but can also typically have an average particle size of 200 micrometers or less, 175 micrometers or less, 150 micrometers or less, 125 micrometers or less, 100 micrometers or less, or an average particle size of 90 micrometers or less, or 80 micrometers or less.

[0033] The concentration of aluminum nitride filler from this mixture, desirably the concentration of aluminum nitride filler in the thermally conductive composition as the sum of all aluminum nitride fillers, is 40% by weight or more, can be 41% by weight or more, 42% by weight or more, 43% by weight or more, 44% by weight or more, 45% by weight or more, 50% by weight or more, 55% by weight or more, can have a concentration of 60% by weight or more, but at the same time can typically be 63% by weight or less, 60% by weight or less, 55% by weight or less, 50% by weight or less, 45% by weight or less, 44% by weight or less, or even 43% by weight or less.

[0034] The spherical aluminum nitride particles may be present in a concentration of 40 wt.% or more, 45 wt.% or more, 50 wt.% or more, or even 55 wt.% or more, while also being present in a concentration of 60 wt.% or less, and the weight percentage based on the total weight of aluminum nitride filler having a particle size of 30 micrometers or more may be 55 wt.% or less, 50 wt.% or less, or even 45 wt.% or less. In particular, the thermally conductive composition may have aluminum nitride filler particles in addition to this particular mixture of spherical and irregularly shaped aluminum nitride particles described above, or the thermally conductive composition may not include aluminum nitride filler particles in addition to the particular mixture of spherical and irregularly shaped aluminum nitride particles described above.

[0035] The thermally conductive filler mixture further includes spherical aluminum oxide particles. The spherical aluminum oxide particles have an average particle size of 1 micrometer or more, and can be 2 micrometers or more, 3 micrometers or more, or even 4 micrometers or more, and can have an average particle size of 5 micrometers or less, 4 micrometers or less, even 3 micrometers or less, or 2 micrometers or less. The concentration of the spherical aluminum oxide particles, based on the weight of the thermally conductive composition, can be 25 wt% or more, or 30 wt% or more, and can also be 35 wt% or less, or 30 wt% or less.

[0036] The thermally conductive filler mixture may further include one or more additional thermally conductive fillers having an average particle size of 0.1 micrometers or more, 0.2 micrometers or more, 0.3 micrometers or more, or even 0.4 micrometers or more, and may have an average particle size of 0.5 micrometers or less, 0.4 micrometers or less, 0.3 micrometers or less, or even 0.2 micrometers or less. The total amount of the additional thermally conductive fillers may be present in a concentration of 10 wt% or more, 11 wt% or more, 12 wt% or more, 13 wt% or more, or even 14 wt% or more, based on the weight of the thermally conductive composition, and may be 15 wt% or less, 14 wt% or less, 13 wt% or less, 12 wt% or less, or even 11 wt% or less. The additional thermally conductive fillers may be selected from any filler known in the art, such as metal nitrides and metal oxides (aluminum oxide, magnesium oxide, zinc oxide, etc.). Desirably, the additional thermally conductive filler is zinc oxide.

[0037] In some cases, the thermally conductive filler mixture can include boron nitride fillers with an average particle size greater than 20 micrometers, while typically the boron nitride fillers have an average particle size of 200 micrometers or less, 175 micrometers or less, 150 micrometers or less, 125 micrometers or less, or even 100 micrometers or less, 75 micrometers or less, or 50 micrometers or less.

[0038] The thermally conductive filler may include thermally conductive fillers in addition to those mentioned, or may include no thermally conductive fillers other than those mentioned. The thermally conductive filler mixture desirably consists of the aluminum nitride filler, aluminum oxide particles, additional thermally conductive fillers, and optional boron nitride filler described above. The thermally conductive filler mixture (and the thermally conductive composition as a whole) may be free of magnesium oxide filler, boron nitride filler, or both magnesium oxide and boron nitride fillers.

[0039] The concentration of the thermally conductive filler mixture in the thermal composition can be 90 wt. % or more, 91 wt. % or more, 92 wt. % or more, 93 wt. % or more, 94 wt. % or more, 95 wt. % or more, or even 96 wt. % or more, based on the weight of the thermally conductive composition, and at the same time can be 97 wt. % or less, 96 wt. % or less, or even 95 wt. % or less.

[0040] The thermally conductive composition may further comprise any one or any combination of one or more of the following additional components: an inhibitor (e.g., methyl(tris(1,1-dimethyl-2-propynyloxy))silane), a thermal stabilizer and / or pigment (e.g., copper phthalocyanine powder), a thixotropic agent, fumed silica (preferably surface-treated), and a spacer additive (e.g., glass beads).

[0041] The thermally conductive composition achieves an extrusion rate of over 40 g / min, measured at 0.62 MPa (90 pounds per square inch) pressure using a standard 30 cubic centimeter EFD syringe package (further details are provided below in Extrusion Rate Characterization). Such properties readily eliminate the need to coat the thermally conductive composition onto other materials.

[0042] At the same time, the thermally conductive composition provides a thermal resistance and conductivity of at least 8.0 W / m as measured in accordance with ASTM D-5470 using a LonGwin Model LW 9389 TIM Thermal Resistance and Conductivity Measuring Instrument. *The goal of having a thermal conductivity of 1000K is achieved. Such high thermal conductivity and ease of dispensing makes the thermally conductive composition particularly useful as a thermal interface material (TIM), which is used to thermally couple two items or components of a device. For example, TIMs are useful, particularly in electronic devices, for thermally coupling a heat-generating device to a heat sink, cooling plate, metal cover, or other heat-dissipating component. In such applications, the thermally conductive composition is present between and in thermal contact with at least two components, typically the heat-generating device and at least one of the heat sink, cooling plate, metal cover, or other heat-dissipating component. [Example]

[0043] Table 1 shows materials for use in the sample thermally conductive compositions described herein below. Note: "Vi" refers to a vinyl group. "Me" refers to a methyl group. SYL-OFF and DOWSIL are trademarks of The Dow Chemical Company.

[0044] [Table 1] * The silicone resin is 78 mol% monophenylsiloxane units and 22 mol% dimethylsiloxane units, has a softening point of 80-90°C, and is 55 wt% hexamethyldisilazane-treated fumed silica. The catalyst has a Pt content of 0.16% by weight.

[0045] Sample preparation The sample formulations are shown in Tables 2 and 3, with the amount of each component reported in grams (g). Note: "Wt% spherical AlN" refers to the wt% of spherical AlN that is 30 micrometers or larger relative to all AlN particles that are 30 micrometers or larger.

[0046] Samples are prepared using a SpeedMixer™ DAC 400 FVZ from Flack Components to mix the components together. The Vi polymer, crosslinker, treating agent, and C2 and C3 TC fillers are added to the SpeedMixer cup. Mix at 1000 revolutions per minute (RPM) for 20 seconds, then at 1500 RPM for 20 seconds. Half of the C1 TC filler is added and mixed at 1000 revolutions per minute (RPM) for 20 seconds, then at 1500 RPM for 20 seconds. The remaining C1 TC filler is added and mixed in the same manner. The composition is scraped into the cup to ensure mixing, after which inhibitor E-1 and pigment F-1 are added and mixed in the same manner to obtain the thermally conductive composition sample.

[0047] Sample characterization The following test methods are used to characterize each sample for extrusion rate and thermal conductivity.

[0048] Characterization of Extrusion Rate. The extrusion rate ("ER") of the samples is measured using a Nordson EFD dispensing device. The sample material is packaged in a 30 cubic centimeter syringe with a 2.54 millimeter opening (EFD Syringe manufactured by Nordson Company). The sample is dispensed through the opening by applying a pressure of 0.62 MPa to the syringe. The mass of sample (in grams) extruded after 1 minute corresponds to the extrusion rate (in grams / minute). The objective of this invention is to achieve an extrusion rate of greater than 40 g / minute, preferably 50 g / minute or greater, and even more preferably 60 g / minute or greater. Notably, some samples were powdery pastes that could not be extruded, and therefore reported as having an ER of 0 (TC was not measured).

[0049] Thermal Conductivity Characterization. The thermal conductivity ("TC") of each sample is measured according to ASTM D-5470 using a Longwin Model LW 9389 TIM Thermal Resistance and Conductivity Measuring Instrument from Longwin Science and Technology Corporation, Taiwan. For the purposes of this invention, a thermal conductivity of at least 8.0 watts / meter is * Kelvin (W / m* The goal is to achieve a thermal conductivity of 1000 K.

[0050] [Table 2]

[0051] [Table 3]

[0052] Data analysis / discussion All of the formulations in Table 2 had an ER of over 40 g / min and an ER of 8.0 W / m * The formulations in Table 3, on the other hand, fail to achieve at least one of these objectives.

[0053] Samples 1 to 7 show thermally conductive compositions having various sizes of aluminum nitride particles, with the weight percentage of spherical aluminum nitride particles of 30 micrometers or larger relative to the total aluminum nitride particles of 30 micrometers or larger being varied in the range of 40 wt% to 60 wt%, and the composition being varied within this range.

[0054] Samples 1-5 also contain boron nitride particles, while Samples 6 and 7 do not. These samples demonstrate that the desired TC and ER can be achieved in formulations with or without boron nitride. These samples also show that the inclusion of boron nitride resulted in higher TC formulations, which is generally desirable.

[0055] Samples A to C show formulations with only irregularly shaped aluminum nitride particles of 30 micrometers or larger, revealing that when only irregularly shaped aluminum nitride particles of 30 micrometers or larger are present, the ER is less than 40 g / min.

[0056] Samples D, E, and G to I and M represent formulations containing only spherical aluminum nitride particles of 30 micrometers or larger, and in these formulations, the TC value was 8.0 W / m * Formulations G to I investigate the effect of adding boron nitride, magnesium oxide, or aluminum oxide to try to increase TC, but * It is clear that TC values ​​exceeding K have not yet been obtained.

[0057] Sample F represents a formulation having a mixture of spherical and irregularly shaped aluminum nitride particles, but with a weight percent of spherical particles slightly greater than 60% to greater than 67% by weight. The formulation is a powdery paste that cannot be extruded.

[0058] Sample J shows a formulation with a mixture of spherical and irregularly shaped aluminum nitride particles with a weight percent of spherical particles between 40-60 wt. % but using irregularly shaped aluminum oxide instead of spherical aluminum oxide in the particle size range of 1-5 micrometers. The resulting formulation is a powdery paste that cannot be extruded.

[0059] Samples K and L represent formulations using a blend of spherical and irregular aluminum nitride particles with particle sizes of 30 micrometers or greater, but with more or less than 40-60 wt.% spherical particles. The resulting TC value was 8.0 W / m * It is less than K. The present invention includes the following aspects. [1] A thermally conductive composition, a. ia30~400 millipascals * a vinyldimethylsiloxy-terminated polydimethylpolysiloxane having a viscosity in the range of 0.5 to 1.0 seconds; ii. a silicon hydride functional crosslinker, and iii. a hydrosilylation catalyst; a curable silicone composition having a molar ratio of silicon hydride functionality to vinyl functionality from the crosslinker in the range of 0.5:1 to 1:1; b. a filler treatment comprising one or both of an alkyltrialkoxysilane and a mono-trialkoxysiloxy-terminated dimethylpolysiloxane; c. a thermally conductive filler mixture, i. 40 weight percent or more of an aluminum nitride filler comprising a mixture of spherical and irregularly shaped aluminum nitride particles, wherein both the spherical particles and the irregularly shaped particles have an average particle size of 30 μm or more, and wherein the spherical aluminum nitride filler having a particle size of 30 μm or more is present in a concentration of 40-60 weight percent of the total weight of the aluminum nitride filler having a particle size of 30 μm or more; ii. 25% to 35% by weight of spherical aluminum oxide particles having an average particle size of 1 to 5 micrometers; iii. 10% to 15% by weight of an additional thermally conductive filler having an average particle size of 0.1 to 0.5 micrometers; iv. optionally a thermally conductive filler comprising a boron nitride filler having an average particle size greater than 20 micrometers; A thermally conductive composition, wherein the weight percent of each thermally conductive filler is based on the weight of the composition unless otherwise specified, and the total amount of the thermally conductive filler mixture is 90-97 wt% of the weight of the composition. [2] The vinyldimethylsiloxy-terminated polydimethylpolysiloxane has a viscosity of 60 to 80 millipascals. * The thermally conductive composition according to [1] above, having a viscosity in the range of 1.5 to 1.4 seconds and containing 1.2 to 1.4 wt % vinyl functionality. [3] The silicon hydride functional crosslinker is (II) and (III) H(CH 3 ) 2 SiO-[(CH 3 ) 2 )SiO)] x -Si(CH 3 ) 2 H (II) (CH 3 ) 3 SiO-[(CH 3 )HSiO] y [(CH 3 ) 2 )SiO] z -Si(CH 3 ) 3 (III) (wherein the subscript x has a value in the range of 10 to 100, the subscript y has a value in the range of 3 to 30, and the subscript z has a value in the range of 3 to 100). [4] The thermally conductive composition according to [3] above, wherein the silicon hydride functional crosslinker has the chemical structure (II): [5] The thermally conductive composition according to any one of [1] to [4] above, wherein the alkyltrialkoxysilane is selected from C6 to C12 alkyltrimethoxysilanes, and the mono-trialkoxysiloxy-terminated dimethylpolysiloxane is selected from mono-trimethoxy-terminated dimethylpolysiloxanes having the average chemical structure (IV): (CH 3 ) 3 SiO[CH 3 ) 2 SiO] a Si(OCH 3 ) 3 (IV) (wherein the subscript a is a value in the range of 30 to 110) [6] The thermally conductive composition according to any one of [1] to [5] above, wherein the composition does not contain a magnesium oxide filler. [7] The thermally conductive composition according to any one of [1] to [6] above, wherein the composition does not contain a boron nitride filler. [8] The thermally conductive composition according to any one of the above [1] to [7], wherein the additional thermally conductive filler is zinc oxide. [9] An article comprising the thermally conductive composition according to any one of [1] to [8] above on another material.

[10] The article of [9], wherein the thermally conductive composition is between and in thermal contact with a heat-generating component of an electronic device and one or more of a heat sink, a cooling plate, and a metal cover of the electronic device.

Claims

1. A thermally conductive composition comprising: a. i.a. 30 to 400 millipascals ＊ a vinyldimethylsiloxy-terminated polydimethylpolysiloxane having a viscosity in the range of 0.5 to 1.0 seconds; ii. a silicon hydride functional crosslinker, and iii. a hydrosilylation catalyst; a curable silicone composition having a molar ratio of silicon hydride functionality to vinyl functionality from said crosslinker in the range of 0.5:1 to 1:1; b. a filler treating agent comprising one or both of an alkyltrialkoxysilane and a mono-trialkoxysiloxy-terminated dimethylpolysiloxane; c. a thermally conductive filler mixture comprising: i. 40 weight percent or more of an aluminum nitride filler comprising a mixture of spherical and irregularly shaped aluminum nitride particles, wherein both the spherical particles and the irregularly shaped particles have an average particle size of 30 μm or more, and wherein the spherical aluminum nitride filler of 30 μm or more in size is present in a concentration of 40-60 weight percent of the total weight of the aluminum nitride filler of 30 μm or more in size; ii. 25% to 35% by weight of spherical aluminum oxide particles having an average particle size of 1 to 5 micrometers; iii. 10% to 15% by weight of an additional thermally conductive filler having an average particle size of 0.1 to 0.5 micrometers; the weight percent of each thermally conductive filler is based on the weight of the composition unless otherwise specified, and the total amount of the thermally conductive filler mixture is 90-97 wt% of the weight of the composition; A thermally conductive composition, wherein said composition does not contain a boron nitride filler.

2. The vinyldimethylsiloxy-terminated polydimethylpolysiloxane has a viscosity of 60 to 80 millipascals. ＊ 10. The thermally conductive composition of claim 1 having a viscosity in the range of 10 ...

3. The silicon hydride functional crosslinker comprises (II) and (III) H(H) ３ ) ２ SiO-[(CH ３ ) ２ )SiO)] ｘ -Yes (CH) ３ ) ２ H (II) (CH) ３ ) ３ SiO-[(CH ３ )HSiO] ｙ [(CH ３ ) ２ )Si] ｚ -Yes (CH) ３ ) ３ (III) 3. The thermally conductive composition of claim 1, comprising one or more polysiloxanes having a chemical structure selected from: wherein subscript x has a value in the range of 10 to 100, subscript y has a value in the range of 3 to 30, and subscript z has a value in the range of 3 to 100.

4. 4. The thermally conductive composition of claim 3, wherein the silicon hydride functional crosslinker has the chemical structure (II):

5. 5. The thermally conductive composition of claim 1, wherein the alkyltrialkoxysilane is selected from C6 to C12 alkyltrimethoxysilanes, and the mono-trialkoxysiloxy-terminated dimethylpolysiloxane is selected from mono-trimethoxy-terminated dimethylpolysiloxanes having the average chemical structure (IV): (CH ３ , ３ SiO[(CH ３ , ２ SiO] ａ Si(OCH ３ , ３ (IV) where the subscript a is a value ranging from 30 to 110.

6. The thermally conductive composition of any one of claims 1 to 5, wherein the composition does not contain magnesium oxide filler.

7. The thermally conductive composition according to any one of claims 1 to 6, wherein the additional thermally conductive filler is zinc oxide.

8. An article comprising the thermally conductive composition of any one of claims 1 to 7 on another material.

9. 10. The article of claim 8, wherein the thermally conductive composition is between and in thermal contact with a heat-generating component of an electronic device and one or more of a heat sink, a cooling plate, and a metal cover of the electronic device.

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