Thermally conductive silicone composition

Abstract

A thermally conductive composition containing (A) from 1.0 wt% to 4.0 wt%, based on the weight of the thermally conductive composition, of an alkenyl functional polyorganosiloxane; (B) a silyl-hydride functional polysiloxane crosslinking agent containing at least two silyl-hydride groups per molecule; (C) 93% to 96% by weight of a thermally conductive filler containing specific amounts of alumina particles having a D50 in the range of 10 [mu] m to 40 [mu] m, and optionally aluminum nitride particles having a D50 in the range of 10 [mu] m to 40 [mu] m, (C2) spherical aluminum particles having a D50 in the range of 1 [mu] m to 5 [mu] m, and (C3) spherical aluminum particles having a D50 in the range of 1 [mu] m to 5 [mu] m, and (C3) a third thermally conductive filler having a D50 in the range of 0.1 [mu] m to 0.6 [mu] m and selected from the group consisting of zinc oxide particles, alumina particles, and mixtures thereof; and (D) a filler treatment agent.

Description

Technical Field

[0001] The present invention relates to a thermally conductive silicone composition containing a thermally conductive filler comprising a novel combination of at least three different thermally conductive particles. Background Technology

[0002] The industrial drive for smaller, more powerful electronic devices has increased the demand for thermally conductive compositions that can dissipate the heat generated in such devices. Without effective dissipation, the heat generated by the high power in smaller devices can damage them. In particular, advanced integrated circuit devices (such as CPUs) in consumer devices generate significant amounts of heat due to accelerated operating speeds. Thermally conductive interface materials are commonly used in electronic devices to thermally couple heat-generating and heat-dissipating components.

[0003] The challenge of silicone grease compositions is to provide a combination of good thermal conductivity properties for efficient heat transfer between coupled components, while being easily extruded or dispensed to allow for precise application of the thermally conductive material to small parts. Specifically, it is desirable to provide a thermally conductive interface material having an extrusion rate of at least 40 g / min as measured using an extrusion rate test as defined below, and cured to have at least 6.0 W / m as measured using a hot plate according to ISO 22007-2. Kelvin (W / m) Thermal conductivity (TC) of K and not exceeding 0.12 degrees Celsius square centimeters per watt (°C) as determined by ASTM D-5470. cm 2 The material has a thermal resistance (TR) of 200 W / m. Aluminum (Al) filler particles have a thermal resistance (TR) of 200 W / m. K has high thermal conductivity and can be used to provide the aforementioned high TC for silicone compositions in applications where electrical insulation properties are not required. However, due to the conductivity of aluminum, adding more than 30% by weight of aluminum particles based on the weight of the silicone composition generally impairs the electrical insulation properties of the silicone composition and the cured product, making them unsuitable for heat transfer in applications involving high voltage.

[0004] Thermal grease compositions are typically applied between electronic components and structures such as heat sinks to effectively dissipate heat from the electronic components. Existing silicone grease compositions typically contain a silicone fluid loaded with alumina (Al₂O₃) filler. When the goal of such silicone grease compositions is to achieve a thin bond thickness (BLT) of 80 micrometers (µm) or less, the average particle size of the Al₂O₃ filler needs to be within an appropriate range so that the composition can be compressed to fill the thin gaps and meet thermal resistance requirements (≤0.12°C). cm 2 / W). However, when using Al2O3 fillers with an average particle size of 40µm or smaller, high filler loadings (e.g., greater than 94.5% by weight relative to the composition weight) are typically required for silicone compositions to achieve at least 6.0 W / m. The desired thermal conductivity of K reduces the extrusion rate of compositions that can even be converted into powdered pastes. Furthermore, such highly viscous compositions cannot conform to the fine irregularities on the surfaces of electronic components and / or heat sinks, leading to increased thermal resistance. Therefore, meeting these performance parameters is particularly challenging.

[0005] It is still necessary to identify a thermally conductive composition that can simultaneously achieve the above-mentioned extrusion rate and thermal conductivity properties. Summary of the Invention

[0006] This invention provides a thermally conductive composition having an extrusion rate (ER) of 40 g / min or higher as measured using an extrusion rate test as defined herein, and cured to have a thermal conductivity of not more than 0.12 °C / cm² / W (°C) according to ASTM D-5470. cm 2 Thermal resistance (TR) of / W and at least 6.0 W / m as measured using a heat plate according to ISO 22007-2. Kelvin (W / m) Materials with a thermal conductivity (TC) of K). The compositions of the present invention are particularly suitable for use as thermally conductive silicone greases, which can achieve a binder layer thickness (BLT) of 80 µm or less while still meeting TR and TC requirements. Surprisingly, it has been determined that such compositions can be prepared from polysiloxane compositions (also known as “thermally conductive compositions”) containing a novel combination of at least three types and / or different particle sizes of thermally conductive fillers in specific amounts.

[0007] In a first aspect, the present invention is a thermally conductive composition, wherein, based on the weight of the thermally conductive composition, the thermally conductive composition comprises: (A) 1.0 wt% to 4.0 wt% of an alkenyl-functionalized polysiloxane, wherein the alkenyl-functionalized polysiloxane has the properties as determined by ASTM D445-21 at 25°C at 25 mPa. 500 millipascals per second Viscosities within the range of seconds, wherein the alkenyl-functionalized polyorganosiloxane has an average chemical structure (I):

[0008] Where R aEach time it appears, it is independently an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms, and each time it appears, it is independently an alkenyl group, with subscript a ≥ 0, subscript b > 0, subscript c being 0 or 1, subscript d being 0 or 1, and (a+c+d) ≥ 2. (B) A silyl-hydride functional polysiloxane crosslinking agent, wherein each molecule of the silyl-hydride functional polysiloxane crosslinking agent contains at least two silyl-hydride groups and is present at a concentration of 0.4:1 to 1.5:1 molar ratio of silicon-bonded hydrogen atoms to alkenyl groups, which provides the composition. (C) 93% to 96% by weight of thermally conductive filler, wherein the thermally conductive filler comprises: (C1-a) 15 wt% to 65 wt% of D50 alumina particles in the range of 10 micrometers to 40 micrometers. (C1-b) 0% to 40% by weight of D50 aluminum nitride particles in the range of 10 micrometers to 40 micrometers. The combined concentration of alumina particles (C1-a) and aluminum nitride particles (C1-b) is in the range of 45% to 65% by weight. (C2) 10% to 30% by weight of spherical aluminum particles with D50 in the range of 1 micrometer to 5 micrometer; (C3) 10% to 25% by weight of a third thermally conductive filler having a D50 in the range of 0.1 micrometers to 0.6 micrometers, wherein the third thermally conductive filler is selected from the group consisting of zinc oxide particles, alumina particles, and mixtures thereof; and (D) A filler treatment agent selected from the group consisting of trialkoxysilyl diorganopolysiloxanes, alkyltrialkoxysilanes, and mixtures thereof.

[0009] In a second aspect, the present invention is a method for using the thermally conductive composition of the first aspect. The method includes the steps of: a) applying the thermally conductive composition to an electronic component, and b) curing the thermally conductive composition by heating.

[0010] In a third aspect, the present invention is an electronic article comprising a thermally conductive composition of the first aspect, the thermally conductive composition being located between and in contact with two components of the electronic article, wherein the thermally conductive composition is in a cured or uncured form. Detailed Implementation

[0011] When a test method number is not used to indicate a date, the test method refers to the most recent test method as of the priority date of this document. References to test methods include references to both the testing association and the test method number. The following test method abbreviations and identifiers apply to this document: ASTM refers to ASTM International Methods, and ISO refers to the International Organization for Standardization.

[0012] Products identified by trade names refer to compositions available under those trade names as of the priority date of this document. "And / or" means "and, or as an alternative." Unless otherwise specified, all ranges include the endpoints. Unless otherwise stated, all weight percentage (wt%) values ​​are relative to the weight of the composition.

[0013] "Spherical" shaped particles are defined as particles with an aspect ratio of 1.0 + / - 0.2. The aspect ratio of a particle is determined by imaging with a scanning electron microscope (SEM) and by obtaining the average ratio of the longest dimension (major axis) and the shortest dimension (minor axis) of at least ten particles.

[0014] "Spherical" refers to a shape in which the grain has small edges and the entire grain is a single grain with few crystal edges. Spherical grains have an aspect ratio other than 1.0 + / - 0.2 and can be elliptical, etc., but do not include spheres.

[0015] A "polyhedron" is a shape surrounded by multiple planes, such as a hexahedron, octahedron, and dodecahedron. Each plane does not necessarily have the same shape.

[0016] "Irregular" shaped particles refer to particles that do not have a fixed shape (such as "spherical", "quasi-circular", or "polyhedral"). Irregular particles have an aspect ratio different from 1.0 + / - 0.2 and are observed to have distinct sharp, non-uniform, and differently shaped edges when viewed through SEM imaging.

[0017] The particle size of thermally conductive fillers (which can be used interchangeably with "average particle size" and "D50") refers to the volume-weighted median of the particle diameter distribution (D50). D50 can be determined using a laser diffraction particle size analyzer such as the Mastersizer from Malvern Instruments. ™ The Malvern Instruments 3000 laser diffraction particle size analyzer is used for measurement.

[0018] Unless otherwise specified, the “viscosity” of polysiloxanes is determined according to ASTM D445-21 at 25 degrees Celsius (°C). For example, a glass capillary Canon-Fensk viscometer can be used to determine the viscosity.

[0019] The thermally conductive composition of the present invention is a curable composition that can undergo a crosslinking reaction (“curing”). In the composition of the present invention, the crosslinking reaction is a hydrosilylation reaction between an alkenyl-functionalized polysiloxane component and a silyl-hydride (SiH)-functionalized polysiloxane crosslinking agent.

[0020] The thermally conductive composition of the present invention comprises an alkenyl-functionalized polyorganosiloxane (component (A)) having two or more alkenyl groups per molecule. "Alkenyl" means a branched or unbranched monovalent hydrocarbon group having one or more carbon-carbon double bonds. The alkenyl group can be a terminal group, a side group, or a combination of both. A "terminal" group is located on a terminal siloxane group of the molecule. A "terminal" siloxane group is attached to only one other siloxane group. A "side group" is located on an internal siloxane group of the molecule, which is attached to at least two other siloxane groups. A "siloxane group" is a group containing SiO2 bound to another Si through oxygen in SiO2. Ideally, each molecule of the alkenyl-functionalized polyorganosiloxane has an average of one or more terminal alkenyl groups. The alkenyl-functionalized polyorganosiloxane has a thermal conductivity of 25 mPa. seconds (mPa s) to 500 millipascals Viscosity in the range of seconds. If the viscosity is too low, the polymer matrix and filler tend to separate, thus impairing the physical properties of the composition. If the viscosity is too high, it may be difficult to incorporate enough filler to achieve the desired TC and ER properties. The viscosity of the alkenyl-functionalized polyorganosiloxane is 25 mPa. s to 500mPa s, and can be 25mPa s or greater, 30mPa s or greater, 40mPa s or greater, 50 mPa s or greater, 60mPa s or greater, 70mPa s or greater, 75mPa s or greater, 78mPa s or larger, even 80 mPa s or greater, while 500 mPa s or smaller, and can be 400 mPa s or less, 300mPa s or smaller, 200mPa s or smaller, 150 mPa s or less, 100mPa s or less, 90mPa s or smaller, even 80 mPa s or less, ideally 30 mPa s to 100mPa The viscosity is determined, for example, using a glass capillary Canon-Fensk viscometer at 25°C according to ASTM D445-21. An alkenyl-functionalized polysiloxane may be a combination of two or more alkenyl-functionalized polysiloxanes, which may differ in molecular weight, structure, siloxane unit, and sequence. When an alkenyl-functionalized polysiloxane is a combination of more than one alkenyl-functionalized polysiloxane, the viscosity is the combined viscosity of the alkenyl-functionalized polysiloxane.

[0021] The alkenyl-functionalized polyorganosiloxane (A) that can be used in this invention has an average chemical structure (I):

[0022] Where R a R' is independently an alkyl group with 1 to 6 carbon atoms or an aryl group with 6 to 10 carbon atoms each time it appears, and R' is independently an alkenyl group each time it appears, with subscript a being zero or greater (≥0), subscript b being greater than 0 (>0), subscript c being 0 or 1, subscript d being 0 or 1, and (a+c+d) being 2 or greater (≥2).

[0023] Suitable for R a The alkyl group may include, for example, methyl, ethyl, propyl (e.g., isopropyl and / or n-propyl), butyl (e.g., isobutyl, n-butyl, tert-butyl and / or sec-butyl), pentyl (e.g., isopentyl, neopentyl and / or tert-pentyl), hexyl, and branched saturated alkyl groups with 6 carbon atoms. Suitable for R a Examples of aryl groups are phenyl, tolyl, xylyl, naphthyl, benzyl, and dimethylphenyl. Each R a They can be the same or different. Each R a It can be an alkyl group. Ideally, each R... a Independently methyl, ethyl, or propyl, and more ideally, each R a It is a methyl group.

[0024] The alkenyl group used for R' typically has 2 to 8 carbon atoms, 2 to 6 carbon atoms, or 2 to 4 carbon atoms. Suitable alkenyl groups may include vinyl, allyl, butenyl, and hexenyl. Particularly suitable alkenyl groups for R' are vinyl, allyl, butenyl, and hexenyl. The R' groups may be the same or different. Ideally, each R' is selected from vinyl or hexenyl. More ideally, each R' is vinyl.

[0025] Ideally, index a is 0, index c is 1, index d is 1, and each R... a It is a methyl group.

[0026] The subscript 'a' indicates the number of molecules per molecule (R'R) a The subscript b indicates the average number of (R) groups per molecule. a The average number of 2SiO groups. Ideally, the amount (a+b) is 20 to 600, and can be 25 or greater, 30 or greater, 40 or greater, 50 or greater, 60 or greater, 70 or greater, 80 or greater, 90 or greater, 100 or greater, 120 or greater, 140 or greater, 160 or greater, or even 180 or greater, while typically 600 or less, and can be 560 or less, 500 or less, 400 or less, 350 or less, 200 or less, 180 or less, 160 or less, 140 or less, 120 or less, 100 or less, 80 or less, 60 or less, or even 40 or less, ideally 25 to 60. Ideally, the value of the subscript b is as described above for (a+b). Ideally, the quantity (a+c+d) is 2 or greater, or even 3 or greater, while it is usually 30 or less, and can be 20 or less, 10 or less, or even 3 or less.

[0027] Examples of suitable alkenyl-functionalized polyorganosiloxanes include i) vinyl dimethylsiloxane-terminated polydimethylsiloxane, ii) dimethyl vinyl siloxane-terminated poly(dimethylsiloxane / methyl vinylsiloxane), iii) dimethyl vinyl siloxane-terminated polymethyl vinylsiloxane, iv) trimethyl siloxane-terminated poly(dimethylsiloxane / methyl vinylsiloxane), v) trimethyl siloxane-terminated polymethyl vinylsiloxane, vi) dimethyl vinyl siloxane-terminated poly(dimethylsiloxane / methyl vinylsiloxane), or mixtures thereof.

[0028] Ideally, the alkenyl-functionalized polyorganosiloxane comprises, or consists of, any combination of one or more of vinyl dimethylsiloxy-terminated polydimethylsiloxanes (A1) with an average chemical structure (II):

[0029] Where Vi represents vinyl, and the subscript b is the average number of ((CH3)2SiO) groups per molecule and has a value from 20 to 600, and can be 20 or greater, 25 or greater, 30 or greater, 40 or greater, 45 or greater, 50 or greater, 60 or greater, 70 or greater, 80 or greater, 90 or greater, 100 or greater, 120 or greater, 140 or greater, 160 or greater, or even 180 or greater, while typically having a value of 600 or less, and can be 560 or less, 500 or less, 400 or less, 350 or less, 200 or less, 180 or less, 160 or less, 140 or less, 120 or less, 100 or less, 80 or less, 60 or less, 45 or less, or even 40 or less, ideally 20 to 200. For example, an alkenyl-functionalized polyorganosiloxane can have a value of 60 mPa. The viscosity of s and the relative molecular weight of vinyl dimethylsiloxy-terminated polydimethylsiloxanes containing 1.55 wt% (wt%) vinyl groups, such as those available from Gelest under the name HMS-501.

[0030] Based on the weight of the thermally conductive composition, the concentration of component (A) alkenyl-functionalized polyorganosiloxane can be from 1.0 wt% to 4.0 wt%, and can be 1.0 wt% or greater, 1.5 wt% or greater, 1.8 wt% or greater, 2.0 wt% or greater, 2.4 wt% or greater, 2.5 wt% or greater, 2.6 wt% or greater, 2.7 wt% or greater, 2.8 wt% or greater, 2.9 wt% or greater, or even 3.0 wt% or greater, while typically 4.0 wt% or less, and can be 3.8 wt% or less, 3.5 wt% or less, 3.3 wt% or less, 3.0 wt% or less, 2.9 wt% or less, 2.8 wt% or less, 2.7 wt% or less, or even 2.6 wt% or less, ideally 1.8 wt% to 2.8 wt%.

[0031] The thermally conductive composition of the present invention comprises a silyl-hydride (SiH) functionalized polysiloxane crosslinker (component (B), also referred to as "SiH crosslinker"). The SiH functionalized polysiloxane crosslinker contains at least two silyl-hydride groups (i.e., at least two silicon-bonded hydrogen atoms per molecule), or even three or more silyl-hydride groups. The SiH groups can be side groups, end groups, or a combination of both. The SiH functionalized polysiloxane crosslinker may have an average chemical structure (III):

[0032] Where R bbEach time it appears, it is independently selected from alkyl groups having 1 to 6 carbon atoms and phenyl groups; each time the subscripts h and h' are independently selected from values ​​in the range of 0 to 3, provided that the combination of e, h and h' is at least 2; the subscript e is from 0 to 30; and the subscript f is from 5 to 200.

[0033] R bb The group can have one or more carbons, two or more carbons, three or more carbons, four or more carbons, or even five or more carbons, and simultaneously six or fewer carbons, five or fewer carbons, four or fewer carbons, three or fewer carbons, or even two or fewer carbons. Ideally, R bb The group is independently selected from methyl and phenyl each time it appears. H is a hydrogen atom.

[0034] The subscripts h and h' refer to the average number of terminal hydrogen atoms at any given end, and each is independently selected from a value between 0 and 3 each time it appears, provided that the combination of e, h, and h' is at least 2. Ideally, h and h' are independently 0 or greater, 1 or greater, or even 2 or greater each time they appear, while simultaneously being 3 or less, 2 or less, or even 1 or less. More ideally, h and h' have the same value. Most ideally, both h and h' are zero. The subscript e represents the number of hydrogen atoms per molecule (HR). bb The average number of SiO groups. If both h and h' are zero, then e is in the range of 2 to 30. If neither h nor h' is zero, then the subscript e can be 0 to 30, provided that the combination of e, h, and h' is 2 or greater. Ideally, the subscript e is 1 or greater, and can be 2 or greater, and can be 3 or greater, 4 or greater, 5 or greater, 6 or greater, 7 or greater, 8 or greater, or even 9 or greater, and is usually 30 or less, and can be 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, 4 or less, 3 or less, or even 2 or less. The subscript f is the number of (R) groups per molecule. bb The average number of 2SiO groups. Generally, the subscript f is 5 or greater, 10 or greater, 20 or greater, 25 or greater, 30 or greater, 40 or greater, 50 or greater, and can be 75 or greater, 100 or greater, 125 or greater, 150 or greater, 175 or greater, or even 190 or greater, and is usually 200 or less, 175 or less, 150 or less, 125 or less, 100 or less, 75 or less, 50 or less, 40 or less, 30 or less, 25 or less, or even 20 or less.

[0035] Ideally, the SiH-functionalized polysiloxane crosslinking agent comprises one or more polysiloxanes having a chemical structure selected from (III-a), (III-b), or combinations thereof:

[0036] The subscript x is 10 to 100, and can be 10 to 60, 10 to 40 or 10 to 20; the subscript y is 2 to 30, and can be 2 to 20, 2 to 10 or 2 to 5; and the subscript z is 3 to 100, and can be 3 to 30, 3 to 20 or 3 to 10.

[0037] Ideally, component (B) is a combination of (III-a) SiH crosslinking agent and (III-b) SiH crosslinking agent.

[0038] SiH-functionalized polysiloxane crosslinking agents may have a silicon-bonded hydrogen atom (H) (“SiH”) content (i.e., SiH content) of 0.01 wt% to 1.0 wt%, and may be 0.01 wt% or greater, 0.05 wt% or greater, 0.1 wt% or greater, 0.11 wt% or greater, 0.15 wt% or greater, 0.20 wt% or greater, 0.25 wt% or greater, 0.30 wt% or greater, or even 0.35 wt% or greater, and typically 1.0 wt% or less, and may be 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, 0.4 wt% or less, or even 0.36 wt% or less, ideally 0.1 wt% to 0.8 wt%. SiH content refers to the weight percentage of silicon-bonded hydrogen atoms relative to the molecular weight of the SiH-functionalized polysiloxane crosslinking agent, and can be determined using Fourier transform infrared (FTIR) spectroscopy.

[0039] Suitable SiH-functionalized polysiloxane crosslinking agents may include, for example, trimethylsiloxy-terminated poly(dimethylsiloxane / methylhydrosiloxane), trimethylsiloxy-terminated polymethylhydrosiloxane, hydrogen-terminated polydimethylsiloxane, hydrogen-terminated poly(dimethylsiloxane / methylhydrosiloxane), or mixtures thereof. The crosslinking agent can be a combination of two or more crosslinking agents that may differ in one or more properties selected from molecular weight, structure, siloxane unit, and sequence, such as mixtures of trimethyl-terminated dimethyl-co-hydromethyl polysiloxane and hydride-terminated polydimethylsiloxane. Specific examples of SiH crosslinking agents include those having the following average chemical structures: Me3SiO(Me2SiO)7(MeHSiO)3SiMe3, Me3SiO(Me2SiO). 108 (MeHSiO) 10 SiMe3, Me3SiO (Me2SiO) 22 (MeHSiO)2SiMe3, HMe2SiO(Me2SiO) 25(MeHSiO)1SiMe2H or H(Me)2SiO-[Me2SiO) 14 -SiMe2H, where Me represents methyl, or a mixture thereof. Suitable commercially available SiH crosslinking agents include those available under the names HMS-071, HMS-501, and DMS-H11 from Gallester. Ideally, the SiH crosslinking agent can be one polymer or a combination of two polymers selected from the group consisting of: (Bi)trimethyl-terminated dimethyl-co-hydromethyl polysiloxane having a strength of 10 mPa at 25°C. s to 14mPa The viscosity of s and the SiH content of 0.36% by weight; and (B-ii) hydride-terminated polydimethylsiloxane, which has a viscosity of 7 mPa at 25 °C. s to 10mPa Viscosity in the range of s and SiH content of 0.16% by weight.

[0040] The concentration of the SiH-functionalized polysiloxane crosslinker is sufficient to provide a molar ratio (also called the "SiH / Vi ratio") of silicon-bonded hydrogen atoms from the crosslinker to alkenyl groups (ideally, vinyl groups) in the thermally conductive composition in the range of 0.4:1 to 1.5:1, and this molar ratio can be 0.4:1 or higher, 0.5:1 or higher, 0.6:1 or higher, 0.7:1 or higher, 0.8:1 or higher, or even 0.9:1 or higher, while being 1.5:1 or lower, and can be 1.4:1 or lower, 1.2:1 or lower, 1:1 or lower, 0.9:1 or lower, 0.8:1 or lower, 0.7:1 or lower, or even 0.6:1 or lower. Ideally, the SiH / Vi ratio is between 0.6:1 and 1.2:1. The SiH / Vi ratio determines the degree of crosslinking that occurs when the thermally conductive composition cures. If the SiH / Vi ratio is too low, the composition tends not to cure sufficiently. If the SiH / Vi ratio is too high, the composition cures so much that it becomes brittle and suffers from surface cracking.

[0041] The thermally conductive composition of the present invention comprises a thermally conductive filler (component (C)). Component (C) comprises at least three or even four different thermally conductive fillers, namely (C1), (C2) and (C3) described below, and optionally a combination of (C4), or may be composed thereof.

[0042] The thermally conductive filler (C) comprises a first thermally conductive filler (C1) comprising (C1-a) alumina particles with a D50 in the range of 10µm to 40µm, and optionally (C1-b) aluminum nitride particles with a D50 in the range of 10µm to 40µm. Alumina particles (C1-a) and aluminum nitride particles (C1-b) can each independently have a D50 particle size of 10µm to 40µm, and can have a D50 of 10µm or larger, 12µm or larger, 15µm or larger, 20µm or larger, 25µm or larger, 30µm or larger, or even 35µm or larger, while having a D50 particle size of 40µm or smaller, and can have a D50 of 38µm or smaller, 35µm or smaller, 32µm or smaller, 30µm or smaller, 28µm or smaller, 25µm or smaller, 22µm or smaller, 20µm or smaller, 18µm or smaller, or even 15µm or smaller. Ideally, alumina particles (C1-a) have a D50 in the range of 15µm to 35µm, and more ideally 20µm to 35µm. Ideally, the aluminum nitride particles (C1-b) have a D50 in the range of 10 µm to 30 µm, and more preferably 10 µm to 20 µm. Based on the weight of the thermally conductive composition, the concentration of alumina particles (C1-a) is from 15 wt% to 65 wt%, and can be 15 wt% or more, 20 wt% or more, 25 wt% or more, 30 wt% or more, 35 wt% or more, 40 wt% or more, 45 wt% or more, 50 wt% or more, 55 wt% or more, or even 58 wt% or more, while being 65 wt% or less, and can be 62 wt% or less, 60 wt% or less, 58 wt% or less, 55 wt% or less, 52 wt% or less, 50 wt% or less, 45 wt% or less, 40 wt% or less, 35 wt% or less, 30 wt% or less, or even 28 wt% or less, ideally 25 wt% to 60 wt%, more ideally 40 wt% to 60 wt%. Based on the weight of the thermally conductive composition, the concentration of aluminum nitride particles (C1-b) ranges from 0 wt% to 40 wt%, and can be 5 wt% or more, 15 wt% or more, or even 24 wt% or more, while 40 wt% or less, and can be 30 wt% or less, 27 wt% or less, 20 wt% or less, 18 wt% or less, or even 10 wt% or less, ideally from 0 wt% to 30 wt% or from 20 wt% to 30 wt%.Based on the total weight of the thermally conductive composition, the combined concentration of alumina particles (C1-a) and aluminum nitride particles (C1-b) (i.e., the total concentration of the first thermally conductive filler (C1)) is 45% to 65% by weight, and may be 46% or more, 48% or more, 50% or more, 51% or more, 52% or more, 53% or more, 54% or more, 55% or more, 56% or more, 57% or more, or even 58% or more, while being 65% or less, and may be 64% or less, 63% or less, 62% or less, 61% or less, 60% or less, 59% or less, or even 58% by weight. The first thermally conductive filler (C1) may consist of alumina particles (C1-a). Alternatively, the thermally conductive filler (C1) may be a blend of 25% to 45% by weight alumina particles (C1-a) and 15% to 30% by weight aluminum nitride particles (C1-b). The first thermally conductive filler (C1) may comprise irregular, spherical, near-circular, or polyhedral particles, or combinations of two or more thermally conductive fillers of different types, shapes, or particle sizes, provided that each has a D50 within the range of 10µm to 40µm. The first thermally conductive filler (C1) may be near-circular, spherical, irregular, or combinations thereof. Ideally, the first thermally conductive filler (C1) comprises near-circular or spherical alumina particles.

[0043] The third thermally conductive filler (C2) is spherical aluminum particles with a D50 particle size of 1µm to 5µm, and can have a D50 of 1µm or larger, 1.1µm or larger, or even 1.5µm or larger, while having a D50 particle size of 5µm or smaller, and can have a D50 of 4.5µm or smaller, 4µm or smaller, 3.5µm or smaller, 3µm or smaller, 2.5µm or smaller, or even 2µm or smaller, or even 1.5µm or smaller, ideally 1µm to 3µm. Based on the weight of the thermally conductive composition, the concentration of spherical aluminum particles (C2) is from 10% to 30% by weight, and can be 10% or more by weight, 12% or more by weight, 14% or more by weight, 15% or more by weight, 16% or more by weight, 18% or more by weight, 20% or more by weight, 21% or more by weight, 22% or more by weight, or even 23% or more by weight, while being 30% or less by weight, and can be 29% or less by weight, 27% or less by weight, 25% or less by weight, 23% or less by weight, or even 21% or less by weight, ideally 15% to 30% by weight, more ideally 20% to 25% by weight.

[0044] The third thermally conductive filler (C3) is a thermally conductive filler having a D50 in the range of 0.1µm to 0.6µm, and may have a D50 of 0.1µm or greater, 0.12µm or greater, 0.15µm or greater, 0.2µm or greater, 0.3µm or greater, or even 0.4µm or greater, while having a D50 particle size of 0.6µm or less, and may be 0.5µm or less, 0.4µm or less, 0.3µm or less, 0.2µm or less, or even 0.15µm or less, ideally 0.1µm to 0.5µm. The third thermally conductive filler particles may have any shape, such as spherical, irregular, near-circular, or polyhedral. The third thermally conductive filler may be selected from one or more combinations of zinc oxide and alumina. Ideally, the third thermally conductive filler is zinc oxide particles, such as irregular zinc oxide. Based on the weight of the thermally conductive composition, the concentration of the third thermally conductive filler (C3) can be from 10 wt% to 25 wt%, and can be 10 wt% or more, 11 wt% or more, 12 wt% or more, 13 wt% or more, 14 wt% or more, or even 14.5 wt% or more, while being 25 wt% or less, and can be 23 wt% or less, 22 wt% or less, 20 wt% or less, 21 wt% or less, 19 wt% or less, 18 wt% or less, 17 wt% or less, 15 wt% or less, or even 14.7 wt% or less, ideally 14 wt% to 22 wt%, more ideally 14 wt% to 20 wt%. Ideally, the third thermally conductive filler (C3) is irregular zinc oxide.

[0045] The thermally conductive filler may or may not include a fourth thermally conductive filler (C4) in addition to (C1), (C2), and (C3) described above. Based on the weight of the thermally conductive composition, the concentration of the fourth thermally conductive filler (C4) is from 0% to 10% by weight, and may be 1% or more, 2% or more, 4% or more, 6% or more, or even 8% or more, while being 10% or less, and may be 9% or less, 7% or less, 5% or less, 3% or less, or even 1% or less. The thermally conductive filler (C4) may have a D50 particle size in the range of 10µm to 40µm, and may have a D50 of 10µm or more, 20µm or more, 30µm or more, or even 35µm or more, while having a D50 particle size of 40µm or less, and may have a D50 of less than 40µm, 25µm or less, or even 15µm or less. The fourth thermally conductive filler (C4) may be selected from one or more of boron nitride, diamond, magnesium oxide, and additional aluminum particles other than (C2), such as aluminum particles having a different shape and / or D50 than (C2). Ideally, the fourth thermally conductive filler (C4) is boron nitride particles. The fourth thermally conductive filler (C4) particles may have any shape, such as spherical, irregular, near-circular, or polyhedral. Ideally, based on the weight of the thermally conductive composition, the total concentration of aluminum particles in the composition (including additional aluminum particles of (C2) and (C4) (if used)) is less than 40% by weight, less than 35% by weight, or even less than 30% by weight.

[0046] Ideally, the thermally conductive filler (C) comprises or consists of the following: 45% to 60% by weight of spherical or near-spherical alumina particles with a D50 of 15µm to 35µm, 20% to 25% by weight of spherical aluminum particles with a D50 in the range of 1µm to 5µm, and 14% to 20% by weight of irregular zinc oxide particles with a D50 in the range of 0.1µm to 0.5µm, based on the weight of the thermally conductive composition.

[0047] Alternatively, the thermally conductive filler (C) may comprise or consist of the following, based on the weight of the thermally conductive composition: (C1) 25% to 45% by weight of (C1-a) alumina particles with a D50 ranging from 15µm to 35µm, and 15% to 30% by weight of (C1-b) aluminum nitride particles with a D50 ranging from 10µm to 20µm; (C2) 15% to 30% by weight of spherical aluminum particles with a D50 ranging from 1µm to 5µm; and (C3) 14% to 22% by weight of irregular zinc oxide particles with a D50 ranging from 0.1µm to 0.5µm.

[0048] Based on the weight of the thermally conductive composition, the total concentration of the thermally conductive filler in the composition can be from 93 wt% to 96 wt%, and can be 93 wt% or greater, 93.5 wt% or greater, 94 wt% or greater, 94.4 wt% or greater, 94.5 wt% or greater, 95 wt% or greater, 95.4 wt% or greater, or even 95.5 wt% or greater, while being 96 wt% or less, and can be 95.5 wt% or less, 95 wt% or less, or even 94.5 wt% or less. Ideally, the thermally conductive filler (C) in the composition is selected from the group consisting of alumina, aluminum nitride, aluminum, and zinc oxide; more ideally, the thermally conductive filler is selected from the group consisting of alumina, aluminum, and zinc oxide.

[0049] The thermally conductive composition of the present invention comprises a filler treatment agent (component (D)). Component (D) may be selected from a trialkoxysilyl diorganopolysiloxane, an alkyltrialkoxysilane, or a mixture thereof. Component (D) is one filler treatment agent or a combination of more than one filler treatment agent. The filler treatment agent component (D) may comprise, or consist of, one or more of a trialkoxysilyl diorganopolysiloxane, wherein the trialkoxysilyl diorganopolysiloxane contains -Si(OR) e )3-group diorganopolysiloxanes, wherein R e Each time R appears, it is treated independently as described in (IV) below. e As described. Ideally, a trialkoxysilyl diorganopolysiloxane is a mono-trialkoxysilyloxy-terminated diorganopolysiloxane. Suitable mono-trialkoxysilyloxy-terminated diorganopolysiloxanes include those having an average chemical structure (IV):

[0050] Where R c R d and R eEach occurrence independently represents a hydrocarbon group (alkyl group) having 1 to 10 carbon atoms, such as alkyl and aryl groups, for example having 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, or even 8 or more carbon atoms, and usually simultaneously having 10 or fewer, 8 or fewer, 6 or fewer, 4 or fewer, or even 2 or fewer carbon atoms; and the subscript g usually has a value from 20 to 150, and can be 20 or greater. 25 or greater, 30 or greater, 40 or greater, 50 or greater, 60 or greater, 70 or greater, 80 or greater, 90 or greater, 100 or greater, or even 110 or greater, and usually with a value of 150 or less, and can be 130 or less, 125 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; and Y is 0 or -[OSiR d 2](CH2) n , where R d As described above, and the subscript n has values ​​from 3 to 20, 3 to 10, or 3 to 6; ideally, Y is 0. Ideally, the subscript g has a value in the range of 25 to 110. Each R c R d and R e They can be the same or different. R c R d and R e Examples of suitable alkyl groups are methyl, ethyl, propyl (e.g., isopropyl and / or n-propyl), butyl (e.g., isobutyl, n-butyl, tert-butyl and / or sec-butyl), pentyl (e.g., isopentyl, neopentyl and / or tert-pentyl), hexyl, and branched saturated hydrocarbon groups with 6 carbon atoms. c R d and R e Each can be an alkyl group independently, such as methyl, ethyl, and propyl. Ideally, each R... c R d and R e It is a methyl group. R c R d and R e Suitable aryl groups may include phenyl and dimethylphenyl. Particularly desirable monotrikoxysilyloxy-terminated diorganopolysiloxanes are monotrikoxysilyloxy and trimethylsilyloxy-terminated polydimethylsiloxanes, such as those having the average chemical formula (CH3)3SiO[(CH3)2SiO]. 30Those of Si(OCH3)3. Suitable monotrialkoxysiloxy-terminated dimethylpolysiloxanes can be synthesized according to the teachings in US2006 / 0100336.

[0051] Component (D) of the filler treatment agent may or may not contain one alkyltrialkoxysilane or a combination of more than one alkyltrialkoxysilane. Suitable alkyltrialkoxysilanes include those having the chemical formula (V):

[0052] Where R f Each time it appears, it is independently an alkyl group having 1 to 20 carbon atoms, and can have 6 or more, 7 or more, 8 or more, 9 or more, or even 10 or more carbon atoms, while having 20 or fewer carbon atoms, and can have 18 or fewer, 16 or fewer, 14 or fewer, 12 or fewer, or even 10 or fewer carbon atoms; and R g Each time it appears, it is independently an alkyl group having 1 to 6 carbon atoms, and can have 1 or more, 2 or more, 3 or more, 4 or more, or even 5 or more carbon atoms, while typically having 6 or fewer, 5 or fewer, 4 or fewer, 3 or fewer, or even 2 or fewer carbon atoms. Ideally, R f Each time it appears, it is independently an alkyl group having 6 to 12 carbon atoms. R g Ideally, it should be methyl to form a methoxy group attached to the silicon atom. Particularly desirable alkyltrialkoxysilanes are n-decyltrimethoxysilane, n-octyltrimethoxysilane, or mixtures thereof. Suitable alkyltrialkoxysilanes include n-decyltrimethoxysilane, which can be DOWSIL ™ Z-6210 silane is available from The Dow Chemical Company, or under the name SID2670.0 from Gallest (DOWSIL is a trademark of Dow Chemical Company).

[0053] Based on the weight of the thermally conductive composition, the filler treatment agent of component (D) used in this invention can be present at a total concentration of 0.5 wt% to 2.5 wt%, and can be 0.5 wt% or more, 0.6 wt% or more, 0.7 wt% or more, 0.8 wt% or more, 0.9 wt% or more, 1.0 wt% or more, 1.2 wt% or more, 1.3 wt% or more, 1.4 wt% or more, 1.5 wt% or more, 1.6 wt% or more, or even 1.7 wt% or more, while typically 2.5 wt% or less, and can be 2.4 wt% or less, 2.3 wt% or less, 2.2 wt% or less, 2.1 wt% or less, 2.0 wt% or less, or even 1.9 wt% or less. Ideally, based on the weight of the thermally conductive composition, the monotrikoxysilyloxy-terminated diorganopolysiloxane is present at a concentration of 0.5 wt% to 2.5 wt%, and may be 0.5 wt% or greater, 0.6 wt% or greater, 0.7 wt% or greater, 0.8 wt% or greater, 0.9 wt% or greater, 1.0 wt% or greater, 1.1 wt% or greater, 1.2 wt% or greater, 1.5 wt% or greater, or even 1.6 wt% or greater, while typically present at a concentration of 2.5 wt% or less, and may be 2.4 wt% or less, 2.2 wt% or less, 2.0 wt% or less, 1.8 wt% or less, or even 1.7 wt% or less. Simultaneously or alternatively, based on the weight of the thermally conductive composition, the alkyltrialkoxysilane may be present at a concentration of 0% to 0.4% by weight, and may be 0% or greater, 0.01% or greater, 0.05% or greater, 0.1% or greater, 0.14% or greater, or even 0.15% or greater, while typically present at a concentration of 0.5% or less, and may be 0.4% or less, 0.3% or less, or even 0.2% or less. Ideally, based on the weight of the thermally conductive composition, the filler treatment agent (D) comprises 1.5% to 2.0% by weight of a monotrialkoxysilyloxy-terminated diorganopolysiloxane and 0.1% to 0.3% by weight of an alkyltrialkoxysilane.

[0054] The thermally conductive compositions of the present invention may contain or not contain one or more platinum (Pt)-based hydrosilylation catalysts (component (E)). Such hydrosilylation catalysts may include compounds and complexes such as platinum (O)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane (Karstedt's catalyst), H2PtCl6, di-μ.-carbonyldi-π.-cyclopentadienyldinickel, platinum-carbonyl complexes, platinum-divinyltetramethyldisiloxane complexes, platinum cyclovinylmethylsiloxane complexes, platinum acetylacetonate (acac), platinum black, platinum compounds (such as chloroplatinic acid, chloroplatinic acid hexahydrate, the reaction product of chloroplatinic acid with a monohydric alcohol, bis(ethyl acetoacetate)platinum, bis(acetylacetonate)platinum, platinum dichloride), and platinum compounds complexed with olefins or low molecular weight organopolysiloxanes, or platinum compounds microencapsulated in a matrix or core-shell structure. Hydrosilylation catalysts may be part of a solution comprising complexes of platinum with low molecular weight organopolysiloxanes, including complexes of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with platinum. These complexes may be microencapsulated or deencapsulated in a resin matrix (typically, in phenyl resins). The resin matrix used for microencapsulating the complexes may be a phenyl resin, an acrylate polymer, a polycarbonate, or other resin matrices with a melting point below 150°C to release Pt during thermosetting. Exemplary hydrosilylation catalysts are described in U.S. Patents 3,159,601 and 3,220,972, and encapsulated platinum catalysts are described in WO2014017671A1. This catalyst may be a complex of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with platinum. Platinum-based hydrosilylation catalysts are commercially available, for example, SYL-OFF. ™ The 4000 catalyst, SYL-OFF 4500 catalyst, and SYL-OFF 2700 catalyst are available from Dow Chemical Company (SYL-OFF is a trademark of Dow Chemical Company). Two different catalysts (e.g., E1 and E2) activated at different temperatures can be added. The two different catalysts can be (E1) a complex of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with platinum, and (E2) an encapsulated platinum catalyst, such as a complex of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with platinum, encapsulated in a dimethylsiloxane containing phenylsilsesquioxane.

[0055] Based on the weight of the thermally conductive composition, the amount of component (E) platinum-based hydrosilylation catalyst is sufficient to provide 0.5 ppm to 30 ppm of platinum, and may be 0.5 ppm or more, 5 ppm or more, 10 ppm or more, 20 ppm or more, or even 30 ppm or more, while typically even 30 ppm or less. Alternatively, based on the weight of the thermally conductive composition, the amount of platinum-based hydrosilylation catalyst can be from 0.01 wt% to 0.6 wt%, and can be 0.01 wt% or more, 0.03 wt% or more, 0.04 wt% or more, 0.05 wt% or more, or even 0.06 wt% or more, while typically 0.6 wt% or less, and can be 0.5 wt% or less, 0.4 wt% or less, 0.3 wt% or less, 0.2 wt% or less, 0.1 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.

[0056] The thermally conductive compositions of the present invention may contain or exclude one or more of a combination of hydrosilylation inhibitors (component (F), also referred to as "inhibitors"). Inhibitors can be used to stabilize the thermally conductive compositions to prevent premature curing and to provide storage stability. Examples of suitable inhibitors include any combination of one or more of the following: acetylene compounds, such as 2-methyl-3-butyn-2-ol; 3-methyl-1-butyn-3-ol; 3,5-dimethyl-1-hexyn-3-ol; 2-phenyl-3-butyn-2-ol; 3-phenyl-1-butyn-3-ol; 1-ethynyl-1-cyclohexanol; 1,1-dimethyl-2-propynyl)oxy)trimethylsilane; and methyl(tri(1,1-dimethyl-2-propynyl))trimethylsilane. oxysilanes; enylene-yne ​​compounds, such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; triazoles, such as benzotriazoles; hydrazine-based compounds; phosphine-based compounds; thiol-based compounds; cycloalkenylsiloxanes, including methylvinylcyclosiloxanes, such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane.

[0057] Based on the weight of the thermally conductive composition, the concentration of component (F) inhibitor can be from 0% by weight to 0.1% by weight, and can be 0.001% by weight or more, 0.002% by weight or more, or even 0.003% by weight or more, while typically 0.1% by weight or less, and can be 0.05% by weight or less, 0.01% by weight or less, 0.005% by weight or less, 0.004% by weight or less, or even 0.003% by weight or less.

[0058] The thermally conductive composition of the present invention may contain or exclude other optional components, which include any combination of one or more of the following components: thermal stabilizers and / or pigments (such as copper phthalocyanine powder), thixotropic agents, fumed silica (ideally, surface-treated), and insulating additives (such as glass beads). Based on the weight of the thermally conductive composition, the total concentration of these additional components may range from 0% by weight to 0.6% by weight, and may be 0% by weight or greater, 0.1% by weight or greater, 0.2% by weight or greater, 0.3% by weight or greater, 0.4% by weight or greater, or even 0.5% by weight or greater, while typically 0.6% by weight or less, and may be 0.5% by weight or less, 0.4% by weight or less, 0.3% by weight or less, 0.2% by weight or less, 0.1% by weight or less, or even 0.05% by weight or less.

[0059] The thermally conductive compositions of the present invention may contain or not contain a combination of one or more solvents. Based on the weight of the thermally conductive composition, the solvent concentration may be less than 0.01% by weight, less than 0.005% by weight, or even zero. Ideally, the thermally conductive composition is substantially solvent-free, i.e., solvent-free or may contain trace amounts of residual solvent delivered from the starting material in the composition. The solvent concentration can be measured by gas chromatography (GC). If the amount of solvent is too high, voids tend to form during the curing of the thermally conductive composition, resulting in a poor surface appearance or even reduced thermal conductivity. The solvent can be an organic solvent, such as saturated or unsaturated aliphatic or aromatic hydrocarbons, such as benzene, toluene, xylene, hexane, heptane, octane, isoalkanes, hydrocarbon compounds having 8 to 18 carbon atoms per molecule and at least one aliphatic unsaturated group, such as tetradecene; ketones, such as acetone, methyl ethyl ketone, or methyl isobutyl ketone; acetates, such as ethyl acetate or isobutyl acetate; ethers, such as glycol ethers, such as propylene glycol methyl ether, dipropylene glycol methyl ether and propylene glycol n-butyl ether, diisopropyl ether, or 1,4-dioxane; cyclic or linear siloxanes having an average degree of polymerization of 3 to 10, such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and / or decamethylcyclopentasiloxane; or mixtures thereof. The thermally conductive composition does not require the use of any solvents (such as those mentioned above) while still achieving the desired ER (i.e., good processability) and TC properties described below.

[0060] The thermally conductive composition of the present invention achieves an extrusion rate (ER) of 40 g / min or greater. Simultaneously, the thermally conductive composition of the present invention provides a temperature of no more than 0.12°C upon curing. cm 2 Thermal resistance (TR) of / W and at least 6.0W / m Thermal conductivity (TC) of K. The extrusion rate described herein was determined using a standard 30 cm³ EFD syringe packaged at a pressure of 0.62 MPa and 25°C. Thermally conductive compositions can have extrusion rates of 40 g / min or greater, including 45 g / min or greater, 55 g / min or greater, 60 g / min or greater, 80 g / min, 90 g / min or greater, or even 100 g / min or greater. ER is a useful characteristic as a measure of extrudability, viscosity, and dispensability, which, for example, allows the thermally conductive composition to be easily dispensed for application to another material (such as electronic components or heat sinks) and ensures application efficiency during the production process. TR can be measured according to ASTM D-5470 at a pressure of 40 psi (275.8 kPa), for example at 80°C for 15 minutes, using thermal resistance and thermal conductivity measuring equipment such as the LonGwin Model LW 9389 TIM Thermal Conductivity and Resistance Tester. The thermally conductive composition can provide 0.11°C. cm 2 / W or less, 0.10℃ cm 2 / W or less, 0.09℃ cm 2 / W or less, or even 0.08℃ cm 2 / W or less TR. TC properties can be measured using a hot plate according to ISO 22007-2 with a cured sample. The thermal conductivity composition can provide 6.0 W / m. K or larger, 6.5W / m K or larger, 7W / m K or larger, or even 8.0 W / m K or greater TC. The thermally conductive composition can achieve a binder thickness (BLT) of 80 micrometers (µm) or less, and can have a BLT of 70 µm or less, 60 µm or less, or even 50 µm or less. Further details evaluating the above properties can be found in the Examples section below. Having such a high ER (easy to dispense), while simultaneously having low TR and high TC (providing efficient heat dissipation), makes the thermally conductive composition particularly suitable as a thermally conductive interface material for effectively transferring heat between two components with thin gaps up to 80 µm or less. Thermally conductive interface materials are commonly used for thermally coupling heat-generating and heat-dissipating components, especially in electronic devices.

[0061] The present invention also relates to a method for preparing a thermally conductive composition, the method comprising: mixing an alkenyl-functionalized polyorganosiloxane, a SiH crosslinking agent, a thermally conductive filler, a filler treatment agent, and optionally a hydrosilylation reaction catalyst and inhibitor, as well as other optional components described above.

[0062] The present invention also includes a method for using the thermally conductive composition described above. The method includes the steps of: a) applying the thermally conductive composition to an electronic component, and b) curing the thermally conductive composition by heating. The application of the thermally conductive composition may involve dispensing or extruding the composition. Due to the aforementioned properties of the thermally conductive composition, such as the excellent dispensability and conformability indicated by the high ER described above, this method allows for automated dispensing and assembly (i.e., increased productivity) with minimal stress applied to fill complex geometries and varying gaps, thereby avoiding potential damage to the electronic component. The aforementioned low BTL also enables the composition to be applied to thin gaps.

[0063] The thermally conductive composition is applied to two components of an electronic device. It may be located between and in contact with one electronic component and a heat-dissipating component (such as a heat sink), or between and in contact with two electronic components of an electronic device, wherein at least one electronic component generates heat during operation. Examples of electronic components that generate heat during operation include a central processing unit (CPU), a graphics processing unit (GPU), a memory chip, a driver chip, and an optical module. The thermally conductive composition may be applied to one or both heat-generating electronic components. Examples of heat-dissipating components include heat sinks, cooling plates / pads, cooling pipes, and metal shields.

[0064] The thermally conductive composition can be cured at room temperature or by heat, for example at temperatures above 25°C, and possibly above 40°C or above 80°C. The curing time can vary depending on the temperature, typically ranging from 0.5 hours to 24 hours. The thermally conductive composition can be cured at room temperature, or by heating in an oven or by heat generated by electronic components. Ideally, when the electronic device is in operation, the heat generated by at least one electronic component typically cures the thermally conductive composition within a few hours, thus forming a cured material.

[0065] Because the concentration of solvent in the thermally conductive composition is low or absent, this method does not involve (i.e., does not involve) additional procedures for removing the solvent, such as stripping or evaporating the solvent. While still imparting the desired ER and TC properties as described above to the resulting composition, the thermally conductive composition allows the method to use the composition without the aid of a solvent, and also makes it suitable for directly dispensing (e.g., by extrusion) the composition onto parts of an article without the need to add a solvent to the composition prior to use.

[0066] The present invention also includes an electronic article comprising a thermally conductive composition and at least two components, wherein the thermally conductive composition is located between and in contact with the two components of the article. The thermally conductive composition may be in a cured or non-cured form. The article can be used as a device that benefits from efficient thermal conduction and good electrical insulation between the components, such as at least one of a heat-generating device and radiator, a cooling plate, a metal cap, or other heat-dissipating component. The two components may be the same or different. The electronic article can be used as an electronic device. Examples of electronic devices include optical modules, smartphones, digital cameras, computers, tablet devices, servers and base stations for communications, power inverters, DC-DC converters, advanced driver assistance systems (ADAS), and battery packs in electric vehicles (EVs).

[0067] Example

[0068] Some embodiments of the invention will now be described in the following examples, wherein all percentages (%) are by weight relative to the weight of the composition, and all particle sizes of the filler are D50 particle sizes. Table 1 lists the materials of the thermally conductive compositions used in the samples described below. Note: “Vi” represents vinyl, “Me” represents methyl, and “TC filler” is a guide thermal filler. SYL-OFF is a trademark of The Dow Chemical Company.

[0069] Samples of Examples (IE) 1 to 7 and Comparative Examples (CE) 1 to 8 of the present invention The formulations of the samples are shown in Tables 2 and 3, where the amount of each component is reported in grams (g). The formulations were prepared using SpeedMixer from FlackTek Inc. (South Carolina, USA). ™The DAC 400 FVZ mixer was used to combine these components to prepare the sample. Vi polymer A-1, SiH crosslinkers B-1 and B-2, treatment agents D-1 and D-2, TC filler C3 and TC filler C4 (if present) were added to the cup of the SpeedMixer. The mixture was mixed at 1000 rpm for 20 seconds, then at 1500 RPM for 20 seconds. TC filler C2 was added and mixed at 1000 RPM for 20 seconds, then at 1500 RPM for 20 seconds. TC filler C1 was added and mixed in the same manner. The resulting composition in the cup was scraped to ensure homogeneous mixing, and then catalyst E-1 and inhibitor F-1 were added and mixed in a similar manner to obtain the thermally conductive composition sample. The extrusion rate, thermal conductivity, and appearance of the obtained thermally conductive composition sample were evaluated according to the following test methods: Thermal resistance test Thermal resistance (“TR”) was measured according to ASTM D-5470 using a LonGwin LW 9389 TIM thermal resistance and conductivity measurement instrument from Longwin Science and Technology Corporation, Taiwan, China. The liquid sample was applied between a protected center hot plate and a cold plate, with the hot plate set to 80°C and held for 15 minutes (min). A pressure of 40 psi was used to maintain contact with the plates. The thermal resistance was recorded. An acceptable thermal resistance was 0.12°C. cm 2 / W or smaller.

[0070] Adhesive layer thickness test

[0071] The adhesive layer thickness (“BLT”) was measured using an ARES G2 rheometer as follows: sample material was dispensed onto a substrate, a plate (8 mm in diameter) was pressed onto the sample at a pressure of 40 psi, the sample was compressed to the minimum adhesive layer thickness, and the adhesive layer thickness of the sample was recorded after 180 seconds.

[0072] Extrusion rate test

[0073] The extrusion rate (“ER”) of the sample was determined using a Nordson EFD dispensing apparatus. The sample material was loaded into a 30 cubic centimeter syringe (an EFD syringe from Nordson Company) with a 2.54 mm opening. The sample was dispensed through the opening at 25°C by applying a pressure of 0.62 MPa to the syringe. The mass of sample extruded in grams (g) after one minute corresponds to the extrusion rate in grams per minute (g / min). The objective of this invention is to achieve an extrusion rate of at least 40 g / min. It is worth noting that some samples were powdery pastes that could not be extruded, and therefore they were reported with an ER of 0 (and no other properties were measured, therefore they were reported as “NA”).

[0074] Thermal conductivity test

[0075] Thermal conductivity (“TC”) was determined using a hot plate according to ISO 22007-2. The thermal conductivity of the cured sample was measured using a Hot Disk TPS 2500 S instrument with a 3.189 mm Kapton sensor (model 5465). Cured samples, measuring 25 mm in size, were prepared by curing the above-prepared curable thermally conductive composition sample at 100 °C for 60 minutes. 25mm 8mm. The object of this invention is to achieve at least 6.0 watts per meter. Kelvin (W / m) Thermal conductivity of K).

[0076] Appearance evaluation test

[0077] The surface condition of each thermally conductive composition sample obtained above was evaluated by visual inspection, and the following assessments were made: V: The surface of the oil composition is uniform and smooth.

[0078] M: The oil composition has a rough and granular surface.

[0079] X: The oil and fat composition is in powder form and cannot form a paste.

[0080] The extrusion rate of each sample was characterized using an extrusion rate test, the thermal conductivity of each sample was characterized using a thermal conductivity test, the thermal resistance of each sample was characterized using a thermal resistance test, the binder thickness (BLT) of each sample was characterized using a binder thickness test, and the appearance of each sample was characterized using the appearance evaluation test described above.

[0081] Table 2 presents the characterization results for samples IE1 through IE6. As shown in Table 2, all IE samples contain a novel combination of at least three TC fillers in specific amounts, including (C1) Al2O3 particles with a D50 ranging from 10 µm to 40 µm, (C2) spherical Al particles with a D50 ranging from 1 µm to 5 µm, and (C3) ZnO particles with a D50 ranging from 0.1 µm to 0.6 µm. IE 1, 3, and 7 also contain AlN fillers with a D50 of 10 µm or 20 µm. All IE samples, with a uniform and smooth surface, achieved at least 6 W / m². The TC of K is not higher than 0.12℃. cm 2 The TR was / W and the ER was at least 40 g / min or even greater than 53 g / min (IE 2 and 4-6). In addition, all IE samples achieved a BLT of 80 µm or less.

[0082]

[0083] In contrast, as shown in Table 3, none of the CE samples met one or more of the requirements for ER, TC, and TR. CE 1, containing a lower concentration of 7.6% spherical Al filler (D50: 1.5µm), failed to meet both ER and TR requirements. CE 2, containing TC filler C1 with a D50 of 10µm to 40µm at a concentration less than claimed, produced undesirable low ER and high TR. CE 3, containing spherical Al filler with a D50 of 1.5µm at a concentration higher than claimed, failed to meet the ER requirement. CE 4, using spherical Al filler with a D50 of 9µm instead of spherical Al filler with a D50 of 1µm to 5µm, produced poor processability and thermal properties could not be measured due to its powdery state. CE 5, containing Al2O3 particles with a D50 of 5µm and less than 10µm, produced lower TC and ER than required. CE 6, which does not contain Al2O3 with a D50 in the range of 10µm to 40µm but only contains larger spherical Al2O3 particles with a D50 of 70µm, failed to meet ER and TR requirements. CE 7, which does not contain spherical Al fillers with a D50 of 1µm to 5µm but contains irregular AlN, produced a powdery paste (i.e., poor processability) and could not be measured for TC. CE 8, which contained 40 wt% spherical Al fillers with a D50 of 16µm and 40 wt% spherical Al fillers with a D50 of 1.5µm, with a total Al filler concentration of 80 wt%, produced an undesirable low ER.

[0084]

Claims

1. A thermally conductive composition, said thermally conductive composition comprising, based on the weight of said thermally conductive composition... (A) 1.0 wt% to 4.0 wt% of an alkenyl-functionalized polysiloxane, said alkenyl-functionalized polysiloxane having a viscosity in the range of 25 mPa·s to 500 mPa·s as determined by ASTM D445-21 at 25 degrees Celsius, said alkenyl-functionalized polysiloxane having an average chemical structure (I): Where R a Each time it appears, it is independently an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms, and each time it appears, it is independently an alkenyl group, with subscript a ≥ 0, subscript b > 0, subscript c being 0 or 1, subscript d being 0 or 1, and (a+c+d) ≥ 2. (B) A silyl-hydride functional polysiloxane crosslinking agent, wherein each molecule of the silyl-hydride functional polysiloxane crosslinking agent contains at least two silyl-hydride groups and is present at a concentration that provides a molar ratio of silicon-bonded hydrogen atoms to alkenyl groups of 0.4:1 to 1.5:1 for the composition; (C) 93% to 96% by weight of thermally conductive filler, wherein the thermally conductive filler comprises: (C1-a) 15 wt% to 65 wt% of alumina particles with D50 in the range of 10 micrometers to 40 micrometers. (C1-b) 0% to 40% by weight of D50 aluminum nitride particles in the range of 10 micrometers to 40 micrometers. The combined concentration of the alumina particles (C1-a) and the aluminum nitride particles (C1-b) is in the range of 45% to 65% by weight. (C2) 10% to 30% by weight of spherical aluminum particles with D50 in the range of 1 micrometer to 5 micrometer; (C3) 10% to 25% by weight of a third thermally conductive filler, said third thermally conductive filler having a D50 in the range of 0.1 micrometers to 0.6 micrometers, wherein said third thermally conductive filler is selected from the group consisting of zinc oxide particles, alumina particles, and mixtures thereof; and (D) A filler treatment agent selected from the group consisting of trialkoxysilyl diorganopolysiloxane, alkyltrialkoxysilane, and mixtures thereof.

2. The thermally conductive composition according to claim 1, wherein, based on the weight of the thermally conductive composition, the composition further comprises one or both of the following components: (E) a platinum-based hydrosilylation catalyst in an amount sufficient to provide 0.5 ppm to 30 ppm of platinum, and (F) 0.001 wt% to 0.1 wt% of a hydrosilylation inhibitor.

3. The thermally conductive composition according to claim 1 or 2, wherein the alkenyl-functionalized polyorganosiloxane comprises a vinyl dimethylsiloxy-terminated polydimethylpolysiloxane having an average chemical structure (II): Where Vi represents vinyl and the subscript b has a value from 20 to 200.

4. The thermally conductive composition according to any one of claims 1 to 3, wherein, based on the weight of the curable thermally conductive composition, the filler treatment agent comprises 0.5 wt% to 2.5 wt% of a mono-trialkoxysiloxy-terminated diorganopolysiloxane with an average chemical structure (IV): Where R c R d and R e Each occurrence is independently selected from hydrocarbon groups having 1 to 10 carbon atoms; the subscript g has a value of 25 to 110; and Y is O or [OSiR]. d 2](CH2) n , where the subscript n has values ​​from 3 to 20.

5. The thermally conductive composition according to any one of claims 1 to 4, wherein the third thermally conductive filler is irregular zinc oxide.

6. The thermally conductive composition according to any one of claims 1 to 5, wherein the concentration of the alumina particles (C1-a) is in the range of 25% to 45% by weight, and the concentration of the aluminum nitride particles (C1-b) is in the range of 15% to 30% by weight, based on the weight of the thermally conductive composition.

7. The thermally conductive composition according to any one of claims 1 to 5, wherein, based on the weight of the thermally conductive composition, the thermally conductive composition comprises 45% to 60% by weight of spherical or near-spherical alumina particles with a D50 of 15 to 35 micrometers, 20% to 25% by weight of spherical aluminum particles with a D50 in the range of 1 to 5 micrometers, and 14% to 20% by weight of irregular zinc oxide particles with a D50 in the range of 0.1 to 0.5 micrometers.

8. The thermally conductive composition according to any one of claims 1 to 5, wherein, based on the weight of the thermally conductive composition, the thermally conductive composition comprises 25% to 45% by weight of spherical or near-spherical alumina particles with a D50 in the range of 15 to 35 micrometers, 15% to 30% by weight of aluminum nitride particles with a D50 in the range of 10 to 20 micrometers, 15% to 30% by weight of spherical aluminum particles with a D50 in the range of 1 to 5 micrometers, and 14% to 22% by weight of irregular zinc oxide particles with a D50 in the range of 0.1 to 0.5 micrometers.

9. A method for using the thermally conductive composition according to any one of claims 1 to 8, the method comprising the following steps: a) Applying the thermally conductive composition to the electronic component, and b) The thermally conductive composition is cured by heat.

10. An electronic article comprising a thermally conductive composition according to any one of claims 1 to 8, the thermally conductive composition being located between and in contact with two components of the electronic article, wherein the thermally conductive composition is in a cured or non-cured form.

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