Curable silicone composition

Abstract

A curable composition containing, based on the weight of the curable composition: (A) from 1% to 4% by weight of an alkenyl-functional polyorganosiloxane, (B) a polyorganohydrosiloxane component comprising specific amounts of two different polysiloxanes (B-1) and (B-2), (C) from 93% to 97% by weight of a thermally conductive filler, the thermally conductive filler comprises: (C1) alumina particles having a D50 in the range of from 8 microns to 35 microns, aluminum nitrite particles having a D50 in the range of from 8 microns to 35 microns, or a mixture thereof; (C2) spherical alumina particles having a D50 in the range of 0.3 [mu] m to 4 [mu] m; and (C3) zinc oxide particles having a D50 in the range of from 0.1 microns to less than 0.3 microns; and (D) a filler treatment agent.

Description

Technical Field

[0001] This invention relates to a curable silicone composition (particularly suitable for use as a thermally conductive silicone grease), a method for using such a curable composition, and electronic articles comprising such a curable composition. 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] To improve the heat transfer efficiency between coupled components, the thermally conductive composition is expected to provide a high thermal conductivity (TC) of at least 5.0 W / m Kelvin (W / m K) and no more than 0.12 °C / cm² (°C / cm²) as measured by the test methods defined below. 2 Low thermal resistance (TR) of 100 W / m*K. The challenge in silicone grease compositions is to provide a combination of good thermal conductivity properties (such as the aforementioned TC and TR properties) while being easy to extrude or dispense, allowing for precise application of the thermally conductive material to small parts and improving manufacturing efficiency, such as an extrusion rate of at least 70 g / min as measured using the extrusion rate test defined below. Aluminum (Al) fillers have a high thermal conductivity of 200 W / m*K and can be used to give silicone compositions the aforementioned high TC, but typically compromise electrical insulation properties.

[0004] Thermal greases are common silicone thermal interface materials used in applications with thin gaps. Existing silicone grease compositions typically contain a silicone fluid loaded with alumina (Al₂O₃) filler with a large particle size (e.g., greater than 30 μm) to improve thermal conductivity. However, this often fails to achieve a thin bond layer thickness (BLT) of 80 μm or less, making the composition uncompressible to fill the thin gaps and meet the aforementioned thermal resistance requirements. When using smaller filler particles such as aluminum nitride (AlN) or Al₂O₃, simply increasing the filler loading has limited effect on improving thermal conductivity when the filler type, filler ratio, particle shape, and particle size of each thermally conductive filler are mismatched. The resulting highly filled grease compositions (e.g., greater than 92 wt% relative to the composition weight) typically exhibit reduced extrusion rates and may even become powdery pastes. Furthermore, as CPU chips become thinner and larger, and metal foil replaces the cast substrate as a cover, greater stress is applied to the chip during assembly. Thermal greases with lower hardness are also needed to minimize stress and protect the chip from damage. Simply reducing the amount of polyorganohydrosiloxane crosslinking agent to decrease the hardness of such highly filled grease compositions often leads to reliability issues under harsh conditions. Specifically, voids may appear when the composition is subjected to thermal shock testing at temperatures ranging from -40°C to 140°C, which could result in thermal conductivity failure. Therefore, meeting these performance parameters simultaneously is particularly challenging.

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

[0006] This invention addresses the problem of discovering curable silicone compositions that do not suffer from the aforementioned issues. The curable silicone compositions of this invention comprise a novel combination of a specific ratio of alkenyl-functionalized polysiloxanes and two different polyhydrosiloxane crosslinking agents, and a specific thermally conductive filler package containing at least three different thermally conductive fillers. Such curable compositions exhibit an extrusion rate (ER) of 70 g / min or higher, as measured using an extrusion rate test as defined below. The curable compositions of this invention are cured into a material (i.e., a cured material) having a temperature not exceeding 0.12 °C / cm². 2The material exhibits a thermal resistance (TR) of at least 5.0 W / m Kelvin (W / m K) as measured using a hot plate according to ISO 22007-2, and a Shore 00 hardness of no more than 50 as measured at 25°C according to ASTM D2240-00, while also demonstrating good reliability, allowing the material to maintain its integrity without voids after 168 hours of thermal shock testing between -40°C and 140°C, as measured using the reliability tests defined below.

[0007] In a first aspect, the present invention is a curable composition, which, based on its weight, comprises:

[0008] (A) 1% to 4% by weight of an 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, wherein the alkenyl-functionalized polysiloxane has an average chemical structure of formula (I):

[0009] Where R a Each time it appears, it is independently an alkyl group with 1 to 6 carbon atoms or an aryl group with 6 to 10 carbon atoms, and each time it appears, it is independently an alkenyl group, and the subscript b is greater than 0;

[0010] (B) A polyorganohydrosiloxane component, which comprises:

[0011] (B-1) Polysiloxanes having the average chemical structure of formula (II-1):

[0012] (B-2) Polysiloxanes having the average chemical structure of formula (II-2):

[0013] Where R M Each time it appears, it is independently selected from alkyl groups having 1 to 6 carbon atoms and phenyl groups, with subscript c ranging from 2 to 30, subscript d ranging from 3 to 120, and subscript i ranging from 10 to 150;

[0014] The polysiloxane (B-1) and the polysiloxane (B-2) are present in an amount providing a molar ratio of 6.0 to 20.0 of silicon-bonded hydrogen atoms in the polysiloxane (B-2) to silicon-bonded hydrogen atoms in the polysiloxane (B-1);

[0015] The polyorganohydrosiloxane component is present in an amount providing a total silicon-bonded hydrogen atom to alkenyl group molar ratio of 0.7 to 1.0 in the composition;

[0016] (C) 93% to 97% by weight of thermally conductive filler, wherein the thermally conductive filler comprises:

[0017] (C1) Alumina particles with a D50 in the range of 8 to 35 micrometers, aluminum nitrite particles with a D50 in the range of 8 to 35 micrometers, or mixtures thereof;

[0018] (C2)D50 consists of spherical alumina particles ranging from 0.3 micrometers to 4 micrometers; and

[0019] (C3) D50 zinc oxide particles in the range of 0.1 micrometers to less than 0.3 micrometers; and

[0020] (D) A filler treatment agent selected from trialkoxysilyl diorganopolysiloxane, alkyltrialkoxysilane, or mixtures thereof.

[0021] In a second aspect, the present invention is a method for using the curable composition of the first aspect. The method includes the following steps:

[0022] a) Applying the curable composition to electronic components, and

[0023] b) The curable composition is cured by heat.

[0024] In a third aspect, the present invention is an electronic article comprising a curable composition of the first aspect, the curable composition being located between and in contact with two components of the electronic article, wherein the curable composition is in a cured or non-cured form. Detailed Implementation

[0025] 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 designations apply to this document: ASTM refers to the ASTM International Association Method.

[0026] 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.

[0027] "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.

[0028] "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.

[0029] 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.

[0030] "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.

[0031] 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.

[0032] Unless otherwise specified, the viscosity of polysiloxanes is determined according to ASTM D445-21 at 25°C. For example, a glass capillary Canon-Fensk viscometer can be used to determine the viscosity.

[0033] The curable composition of the present invention is a thermally conductive composition that can undergo a crosslinking reaction (“curing”). Such a crosslinking reaction can be an addition curing between an alkenyl-functionalized polyorganosiloxane (component A) and a polyorganohydrosiloxane component (B), which comprises a specific combination of (B-1) and (B-2) described below.

[0034] The curable 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-functionalized polyorganosiloxane has a viscosity in the range of 25 mPa·s to 500 mPa·s. 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 sufficient filler to achieve the desired TC and ER properties. The viscosity of alkenyl-functionalized polyorganosiloxanes ranges from 25 mPa*s to 500 mPa*s, and can be 25 mPa*s or greater, 30 mPa*s or greater, 40 mPa*s or greater, 50 mPa*s or greater, 60 mPa*s or greater, 70 mPa*s or greater, 75 mPa*s or greater, 78 mPa*s or greater, or even 80 mPa*s or greater, while the viscosity of 500 mPa*s or less can be 400 mPa*s or less, 300 mPa*s or less, 200 mPa*s or less, 150 mPa*s or less, 100 mPa*s or less, 90 mPa*s or less, or even 80 mPa*s or less, ideally 30 mPa*s to 100 mPa*s, as per ASTM standards. The viscosity of D445-21 is determined at 25°C, for example, using a glass capillary Canon-Fensk viscometer. An alkenyl-functionalized polysiloxane can 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.

[0035] The alkenyl-functionalized polyorganosiloxane (A) used in this invention has the average chemical structure of formula (I):

[0036] 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; the subscript b is greater than zero (>0).

[0037] 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 hydrocarbon groups with 6 carbon atoms. Suitable for R a Examples of aryl groups are phenyl, tolyl, xylyl, naphthyl, benzyl, and dimethylphenyl. Each Ra 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.

[0038] 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.

[0039] The subscript b means per molecule (R a The average number of 2SiO) groups, and having a value sufficient to impart the above viscosity to the alkenyl-functionalized polyorganosiloxane. For example, the subscript b can have 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.

[0040] Ideally, in equation (I), each R a The is methyl, and each R' is vinyl. Ideally, the alkenyl-functionalized polyorganosiloxane comprises a polyorganosiloxane of formula (I), wherein in formula (I), each R... a For methyl, each R' is vinyl, and the subscript b is in the range of 20 to 200.

[0041] Ideally, the alkenyl-functionalized polyorganosiloxane comprises, or consists of, any combination of, one or more vinyl dimethylsiloxy-terminated polydimethylpolysiloxanes having the average chemical structure of formula (IA):

[0042] Where Vi represents vinyl, and the subscript b, as defined above, ideally has a value between 20 and 200.

[0043] For example, an alkenyl-functionalized polyorganosiloxane can be a vinyl dimethylsiloxy-terminated polydimethylsiloxane having a viscosity of 60 mPa*s and containing 1.55 weight percent (wt%) of vinyl groups relative to its molecular weight, such as those available from Gelest under the name HMS-501.

[0044] Based on the weight of the curable composition, the concentration of alkenyl-functionalized polyorganosiloxane (A) in the curable composition 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 being 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%.

[0045] The curable composition of the present invention further comprises a polyorganohydrosiloxane component (also known as a “SiH crosslinker,” component (B)). A “polyorganohydrosiloxane” refers to a polysiloxane containing two or more, or at least three, silicon-bonded hydrogen (“SiH”) atoms per molecule. The SiH group can be a side group, an end group, or a combination of both. An “end 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 that is attached to at least two other siloxane groups. A “siloxane group” is a group containing SiO2 bound to another Si through oxygen from SiO2. Component (B) comprises or consists of the polysiloxanes (B-1) and (B-2) described below.

[0046] Polysiloxane (B-1) has the average chemical structure of formula (II-1):

[0047] Where R M Each time it appears, it is independently selected from alkyl groups having 1 to 6 carbon atoms and phenyl groups, with subscript c ranging from 2 to 30 and subscript d ranging from 3 to 120.

[0048] R MThe alkyl group may have one or more carbons, two or more carbons, three or more carbons, four or more carbons, or even five or more carbons, while having six or fewer carbons, five or fewer carbons, four or fewer carbons, three or fewer carbons, or even two or fewer carbons. Ideally, each R M The groups are independently selected from methyl and phenyl. More ideally, each R M The group is methyl. H is a hydrogen atom.

[0049] The subscript c represents per molecule (R) M The average number of HSiO groups. The subscript c 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, while usually 30 or less, and can be 25 or less, 20 or less, 15 or less, or even 10 or less, 6 or less, 5 or less, 4 or less, or even 3 or less, ideally 2 to 20, more ideally 2 to 10, most ideally 2 to 5.

[0050] The subscript d represents per molecule (R) M The average number of 2SiO groups. The subscript d can be 3 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, while being 120 or less, and can be 110 or less, 100 or less, 90 or less, 75 or less, 50 or less, 40 or less, 30 or less, 25 or less, 20 or less, or even 10 or less, ideally 3 to 30, more ideally 3 to 25, most ideally 3 to 10.

[0051] Polysiloxane (B-1) can be one or more polysiloxanes of formula (II-1), which may differ in one or more properties selected from molecular weight, structure, siloxane units, and sequence. Suitable polysiloxanes used as (B-1) may include: i) bis-trimethylsiloxy-terminated poly(dimethylsiloxane / methylhydrosiloxane), ii) bis-trimethylsiloxy-terminated polymethylhydrosiloxane, or mixtures of i) and ii). Specific examples of (B-1) include those having Me3SiO(Me2SiO)7(MeHSiO)3SiMe3 and Me3SiO(Me2SiO). 22 Those with the average chemical structure of (MeHSiO)2SiMe3, where Me represents methyl; or mixtures thereof.

[0052] Polysiloxane (B-2) has the average chemical structure of formula (II-2):

[0053] Where R M As stated above in equation (II-1), ideally, each R M The subscript i is in the range of 10 to 150, and can be 10 or greater, while being 150 or less, and can be 120 or less, 100 or less, 80 or less, 60 or less, 40 or less, or even 20 or less, ideally 10 to 60, more ideally 10 to 40, and most ideally 10 to 20.

[0054] Polysiloxane (B-2) can be one or more polyorganohydrosiloxanes of formula (II-2), which may differ in one or more properties selected from molecular weight, structure, siloxane units, and sequence. Suitable polysiloxanes used as (B-2) may include: i) bis-dimethylsiloxy-terminated polydimethylsiloxanes, ii) bis-dimethylsiloxy-terminated poly(dimethylsiloxane / methylhydrosiloxane), iii) bis-dimethylsiloxy-terminated polymethylhydrosiloxanes, or mixtures thereof. Specific examples of (B-2) include those having H(Me)₂SiO-[Me₂SiO) 14 -SiMe₂H, H(Me)₂SiO-[Me₂SiO) 16 Those with the average chemical structure of -SiMe2H, or mixtures thereof.

[0055] Component (B) may have a silicon-bonded hydrogen (“SiH”) content ranging from 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, while 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%. The SiH content refers to the weight percentage of silicon-bonded hydrogen atoms relative to the molecular weight of the SiH crosslinking agent and can be determined using Fourier transform infrared (FTIR) spectroscopy.

[0056] Methods for preparing polyorganohydrosiloxanes, such as the hydrolysis and condensation of organohydrohalosilanes, are well known in the art, for example, see U.S. Patent 3,957,713 to Jeram et al. and U.S. Patent 4,329,273 to Hardman et al. Polyorganohydrosiloxanes can also be prepared as described, for example, in U.S. Patent 2,823,218 to Speier et al., which discloses organohydrosiloxane oligomers and linear polymers, such as 1,1,1,3,3-pentamethyldisiloxane; bis-trimethylsiloxy-terminated polymethylhydrosiloxane homopolymers; bis-trimethylsiloxy-terminated poly(dimethyl / methylhydro)siloxane copolymers; and cyclic polymethylhydrosiloxanes. Suitable commercially available SiH crosslinking agents include those available from Gallest Corporation under the names HMS-071, HMS-501, and DMS-H11.

[0057] The polysiloxane (B-1) and polysiloxane (B-2) in the polyorganohydrosiloxane component are present in an amount sufficient to provide a molar ratio of silicon-bonded hydrogen atoms in (B-2) to silicon-bonded hydrogen atoms in (B-1) of 6.0 to 20.0, and this molar ratio may be 6.5 or greater, 7.0 or greater, 7.5 or greater, 7.7 or greater, or even 8.0 or greater, while being 20.0 or less, and may be 19.0 or less, 18.0 or less, 17.0 or less, 16.0 or less, 15.0 or less, 14.0 or less, 13.0 or less, 12.0 or less, 11.0 or less, or even 10.0 or less, ideally 7.0 to 16.0, more ideally 7.5 to 10.0.

[0058] The ratio of silicon-bonded hydrogen to alkenyl groups in a curable composition is important for the properties of the composition. Typically, this is determined by calculating the total weight % of alkenyl groups (e.g., vinyl groups) [V] and the total weight % of silicon-bonded hydrogen [H] in the composition, and assuming a molecular weight of 1 for hydrogen and a molecular weight of 27 for vinyl, the molar ratio of silicon-bonded hydrogen to vinyl is 27[H] / [V]. The alkenyl-functionalized polyorganosiloxane (A) and the polyorganohydrosiloxane component (B) may be present in the curable composition in an amount sufficient to provide a molar ratio (also known as the "SiH / Vi ratio") of silicon-bonded hydrogen atoms (e.g., the total silicon-bonded atoms in both (B-1) and (B-2)) to alkenyl groups in the range of 0.7 to 1.0, and this molar ratio may be 0.7 or higher, 0.72 or higher, 0.75 or higher, 0.78 or higher, 0.80 or higher, 0.82 or higher, 0.85 or higher, 0.87 or higher, or even 0.90 or higher, while being 1.0 or lower, and may be less than 1.0, 0.99 or lower, 0.98 or lower, 0.97 or lower, 0.96 or lower, 0.95 or lower, 0.94 or lower, 0.93 or lower, 0.92 or lower, or even 0.90 or lower. Ideally, the SiH / Vi ratio is 0.75 to less than 1.0, 0.80 to 0.95, or 0.85 to 0.95. More ideally, the molar ratio of total silicon-bonded hydrogen atoms to alkenyl groups in the composition is in the range of 0.8 to 0.95, and the molar ratio of silicon-bonded hydrogen atoms in polysiloxane (B-2) to silicon-bonded hydrogen atoms in polysiloxane (B-1) is in the range of 7.0 to 16.0.

[0059] The curable composition of the present invention comprises (C) a thermally conductive filler component (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. The first thermally conductive filler (C1) is selected from the group consisting of: (c1-a) alumina particles with D50 in the range of 8 μm to 35 μm, (c1-b) aluminum nitrite particles with D50 in the range of 8 μm to 35 μm, and mixtures thereof. The thermally conductive fillers (c1-a) and (c1-b) each independently have a D50 particle size of 8 μm to 35 μm, and may have a D50 of 8 μm or larger, 10 μm or larger, 12 μm or larger, 15 μm or larger, 20 μm or larger, 25 μm or larger, or even 30 μm or larger, while having a D50 of 35 μm or smaller, and may have a D50 of 32 μm or smaller, 30 μm or smaller, 28 μm or smaller, 25 μm or smaller, 22 μm or smaller, 20 μm or smaller, 18 μm or smaller, or even 15 μm or smaller, alternatively 10 μm to 35 μm, 15 μm to 35 μm, 15 μm to 30 μm, or 20 μm to 30 μm.

[0060] The first thermally conductive filler may consist of: (i) one or more alumina particles with different shapes and / or D50s, (ii) one or more aluminum nitrite particles with different shapes and / or D50s, or (iii) a mixture of alumina particles and aluminum nitrite particles having the D50s described above. The particles (c1-a) and (c1-b) are each independently 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 the D50 of each thermally conductive filler is within the range described above. Ideally, the alumina particles used for (c1-a) are polyhedral, irregular, or near-circular particles, or combinations thereof. Ideally, the aluminum nitrite particles used for (c1-b) are spherical or irregular particles. Ideally, the first thermally conductive filler (C1) comprises spherical aluminum nitrite particles (c1-b) or a mixture thereof with near-circular or polyhedral alumina particles (c1-a).

[0061] Based on the total weight of the curable composition, the combined concentration of alumina particles (C1-a) and aluminum nitride particles (C1-b) (i.e., the concentration of the first thermally conductive filler) can range from 40% to 60% by weight, and can be 40% by weight or more, 41% by weight or more, 42% by weight or more, 45% by weight or more, 48% by weight or more, 50% by weight or more, or even 51% by weight or more, while being 60% by weight or less, and can be 59% by weight or less, 58% by weight or less, 57% by weight or less, 55% by weight or less, 52% by weight or less, 51% by weight or less, 50% by weight or less, 48% by weight or less, 46% by weight or less, 45% by weight or less, 44% by weight or less, or even 43% by weight. The first thermally conductive filler (C1) can consist of either alumina particles (C1-a) or aluminum nitride particles (C1-b). Alternatively, the first thermally conductive filler (C1) may be a blend of 15 wt% to 60 wt% of (c1-a) and 15 wt% to 60 wt% of (c1-b), provided that the combined concentration of (c1-a) and (c1-b) is within the range described herein. Alternatively, the first thermally conductive filler (C1) may be a blend of 20 wt% to 35 wt% of (c1-a) and 20 wt% to 35 wt% of (c1-b).

[0062] The second thermally conductive filler (C2) is spherical alumina particles having a D50 particle size of 0.3 μm to 4 μm, and may have a D50 of 0.3 μm or larger, 0.4 μm or larger, 0.5 μm or larger, 0.8 μm or larger, 1.0 μm or larger, 1.2 μm or larger, 1.5 μm or larger, or even 1.8 μm or larger, while having a D50 particle size of 4 μm or smaller, and may be 3.5 μm or smaller, 3 μm or smaller, 2.5 μm or smaller, or even 2 μm or smaller, or even 1.5 μm or smaller, ideally 0.3 μm to 2.5 μm, more ideally 0.5 μm to 2 μm. Based on the weight of the curable composition, the spherical alumina particles (C2) may be present in an amount of 20% to 40% by weight, and may be 20% or more by weight, 21% or more by weight, 22% or more by weight, 24% or more by weight, 25% or more by weight, 27% or more by weight, 28% or more by weight, or even 29% or more by weight, while being 40% or less by weight, and may be 38% or less by weight, 36% or less by weight, 35% or less by weight, or even 33% or less by weight, ideally 20% to 38% by weight, more ideally 25% to 35% by weight.

[0063] Zinc oxide particles (C3) have a D50 ranging from 0.1 μm to less than 0.3 μm, and can have a D50 of 0.1 μm or larger, 0.12 μm or larger, 0.15 μm or larger, or even 0.2 μm or larger, while having a D50 particle size of less than 0.3 μm, and can be 0.25 μm or smaller, 0.2 μm or smaller, 0.15 μm or smaller, or even 0.12 μm or smaller, ideally 0.1 μm to 0.2 μm. Ideally, the zinc oxide particles are irregularly shaped. Based on the weight of the curable composition, the concentration of zinc oxide particles (C3) (i.e., the third thermally conductive filler) can be from 10% to 25% by weight, and can be 10% or more by weight, 11% or more by weight, 12% or more by weight, 13% or more by weight, 14% or more by weight, or even 14.5% or more by weight, while being 25% or less by weight, and can be 23% or less by weight, 22% or less by weight, 20% or less by weight, 21% or less by weight, 19% or less by weight, 18% or less by weight, 17% or less by weight, 15% or less by weight, or even 14.7% or less by weight, ideally 14% to 22% by weight, more ideally 14% to 20% by weight. Ideally, the third thermally conductive filler (C3) is irregular zinc oxide.

[0064] 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 curable composition, the concentration of the fourth thermally conductive filler (C4) may be 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 fourth thermally conductive filler (C4) may be selected from one or more combinations of boron nitride, diamond, and magnesium oxide. The thermally conductive filler (C4) can have a D50 ranging from 10 μm to 40 μm, and can be 20 μm or larger, 30 μm or larger, or even 35 μm or larger, while having a D50 particle size of 40 μm or smaller, and can have a D50 of 25 μm or smaller, or even 15 μm or smaller. Ideally, the fourth thermally conductive filler (C4) is boron nitride particles. The fourth thermally conductive filler (C4) particles can have any shape, such as spherical, irregular, near-circular, or polyhedral.

[0065] Ideally, the thermally conductive filler (C) comprises or consists of: 40% to 60% by weight of a first thermally conductive filler (C1), 20% to 40% by weight of spherical alumina particles (C2), and 10% to 25% by weight of zinc oxide particles (C3) (such as irregular zinc oxide), based on the weight of the curable composition. More ideally, the thermally conductive filler (C) comprises or consists of: (C1) 40% to 55% by weight of a first thermally conductive filler with a D50 in the range of 20 μm to 30 μm, (C2) 25% to 35% by weight of spherical alumina particles with a D50 in the range of 0.3 μm to 2.5 μm, and (C3) 12% to 22% by weight of irregular zinc oxide particles with a D50 in the range of 0.1 μm to 0.2 μm.

[0066] Based on the weight of the curable composition, the total concentration of the thermally conductive filler (C) is from 93.0% to 97.0% by weight, and may be 93.2% or greater, 93.4% or greater, 94.0% or greater, 94.5% or greater, 95% or greater, 95.4% or greater, even 94% or greater, 94.5% or greater, even 94.6% or greater, while being 97.0% by weight or less, and may be 96.5% by weight, 96% by weight or less, 95.8% by weight or less, 95.7% by weight or less, 95.5% by weight or less, 95% by weight or less, 94.6% by weight or less, even 94.5% by weight or less.

[0067] The curable 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 the average chemical structure of formula (IV):

[0068] 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 typically also having 10 or fewer, 8 or fewer, 6 or fewer, 4 or fewer, or even 2 or fewer carbon atoms; and the subscript g typically has a value from 20 to 150, and can be 20 or more. Large, 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 also has 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 The subscript n has values ​​from 3 to 20, 3 to 10, or 3 to 6; ideally, Y is 0. The subscript g ideally 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]. 30 Those of Si(OCH3)3. Suitable monotrialkoxysiloxy-terminated dimethylpolysiloxanes can be synthesized according to the teachings in US2006 / 0100336.

[0069] 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):

[0070] 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).

[0071] Based on the weight of the curable composition, the component (D) filler treatment agent used in this invention can be present in a total concentration of 0.5% by weight to 3.0% by weight, and can be 0.5% by weight or more, 0.6% by weight or more, 0.7% by weight or more, 0.8% by weight or more, 0.9% by weight or more, 1.0% by weight or more, 1.2% by weight or more, 1.3% by weight or more, 1.4% by weight or more, 1.5% by weight or more, 1.6% by weight or more, or even 1.7% by weight or more, while typically 3.0% by weight or less, and can be 2.5% by weight or less, 2.4% by weight or less, 2.3% by weight or less, 2.2% by weight or less, 2.1% by weight or less, 2.0% by weight or less, or even 1.9% by weight or less. Ideally, based on the weight of the curable 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 curable composition, the alkyltrialkoxysilane may be present at a concentration of 0% to 0.5% 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 curable composition, the filler treatment agent (D) comprises 1.0% to 2.4% by weight of a monotrialkoxysilyloxy-terminated diorganopolysiloxane and 0.1% to 0.3% by weight of an alkyltrialkoxysilane.

[0072] The curable 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. ™ 4000 catalyst, SYL-OFF ™ 4500 catalyst and SYL-OFF ™ The 2700 catalyst is 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, which is encapsulated in a dimethylsiloxane containing phenylsilsesquioxane.

[0073] Based on the weight of the curable composition, the amount of component (E) platinum-based hydrosilylation catalyst is sufficient to provide 0.5 parts per million (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 curable composition, the amount of platinum-based hydrosilylation catalyst may be from 0.01 wt% to 0.6 wt%, and may be 0.01 wt% or greater, 0.03 wt% or greater, 0.04 wt% or greater, 0.05 wt% or greater, or even 0.06 wt% or greater, while typically 0.6 wt% or less, and may 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.

[0074] The curable compositions of the present invention may contain or not contain one hydrosilylation inhibitor (component (F), also referred to as "inhibitor") or a combination of more than one hydrosilylation inhibitor. Inhibitors can be used to stabilize the curable composition to prevent premature curing and to provide storage stability to the composition. 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.

[0075] Based on the weight of the curable composition, the concentration of component (F) inhibitor can be from zero wt% to 0.1 wt%, and can be 0.001 wt% or more, 0.002 wt% or more, or even 0.003 wt% or more, while typically 0.1 wt% or less, and can be 0.05 wt% or less, 0.01 wt% or less, 0.005 wt% or less, 0.004 wt% or less, or even 0.003 wt% or less.

[0076] The curable compositions of the present invention may contain or exclude other optional components, which include any combination of one or more of the following components: heat stabilizers and / or pigments (such as copper phthalocyanine powder), thixotropic agents, pyrolytic silica (ideally, surface-treated), and spacer additives (such as glass beads). Based on the weight of the curable composition, the total concentration of these additional components may range from 0.5% to 0.6% by weight, and may be 0.5% or greater, 0.1% or greater, 0.2% or greater, 0.3% or greater, 0.4% or greater, or even 0.5% or greater, while typically 0.6% or less, and may be 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, or even 0.05% or less.

[0077] The curable compositions of the present invention may contain or not contain one solvent or a combination of more than one solvent. Based on the weight of the curable composition, the solvent concentration may be less than 0.01% by weight, less than 0.005% by weight, or even zero. Ideally, the curable 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 be created during the curing of the curable composition, which leads to a poor surface appearance or even a decrease in 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 curable 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.

[0078] The curable composition of the present invention achieves an extrusion rate (ER) of 70 g / min or greater. Simultaneously, the curable composition of the present invention provides a curing temperature of no more than 0.12 °C*cm after curing. 2 Thermal resistance (TR) of / W, and can be 0.10℃*cm. 2 / W or less, or even 0.08℃*cm 2 / W or less; and a thermal conductivity (TC) of at least 5.0 W / m*K, and may be 6.0 W / m*K or greater, even 6.5 W / m*K or greater. The extrusion rate described herein was determined using a standard 30 cubic centimeter EFD syringe packaged at a pressure of 0.62 MPa and 25°C. Thermally conductive compositions may have an extrusion rate of 70 g / min or greater, and may be 80 g / min or greater, 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 curable compositions 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 40 psi (275.8 kPa) pressure, for example at 80°C for 15 minutes, using thermal resistance and thermal conductivity measuring equipment such as the LonGwin Model LW9389 TIM Thermal Conductivity and Resistance Tester. TC properties can be measured using a hot plate with cured samples according to ISO 22007-2. Surprisingly, the curable composition achieves a Shore 00 hardness of no more than 50 (≤50) or 40 or less after curing, as measured according to ASTM D2240-00 at 25°C, while also exhibiting good reliability when subjected to thermal shock testing between -40°C and 140°C, as measured using the reliability tests described below. Further details evaluating the above properties can be found in the Examples section below. The curable composition can achieve a BLT thickness of 80 μm or less, and can have a BLT of 70 μm or less, 60 μm or less, or even 50 μm or less. The combination of high ER (easily dispensable), low TR, and high TC (providing efficient heat dissipation) makes curable compositions particularly suitable as thermally conductive interface materials for efficiently transferring heat between two components with thin gaps up to 80 μm or less. Thermally conductive interface materials are commonly used for thermally coupled heat-generating and heat-dissipating components, especially in electronic devices. Curable compositions are particularly suitable as thermally conductive silicone greases that achieve a BLT of 80 μm or less while still meeting the aforementioned TR, TC, and hardness requirements.

[0079] The present invention also relates to a method for preparing a curable composition, the method comprising: mixing an alkenyl-functionalized polyorganosiloxane (A), a polyorganohydrosiloxane component (B), a thermally conductive filler (C), a filler treatment agent (D), and optionally a hydrosilylation reaction catalyst (E) and an inhibitor (F), as well as other optional components described above.

[0080] The present invention also includes a method for using the above-described curable composition. The method includes the steps of: a) applying the curable composition between and in contact with two components, and b) curing the curable composition while it is in place between the two components. The application of the curable composition may involve dispensing or extruding the curable composition. Due to the aforementioned properties of the curable 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) while applying minimal stress to fill complex geometries and varying gaps, thereby avoiding potential damage to electronic components. The aforementioned low BTL also enables the composition to be applied to thin gaps.

[0081] The two components to which the curable composition is applied can be components of an electronic device. The curable composition 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 when the electronic device is in operation. Examples of electronic components that generate heat during operation of the electronic device include a central processing unit (CPU), a graphics processing unit (GPU), a memory chip, a driver chip, and an optical module. The curable 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.

[0082] Curing of the curable composition can occur at room temperature or by heat, for example at temperatures above 25°C, and may exceed 40°C or 80°C. The curing duration can vary depending on the temperature, typically ranging from 0.5 hours to 24 hours. The curable composition can be cured at room temperature 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 curable composition within several hours, thus forming a cured material.

[0083] Because the solvent concentration in the curable composition is low or absent, the 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 to the resulting composition as described above, the curable 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.

[0084] The present invention also includes an electronic article comprising a curable composition and at least two components, wherein the curable composition is located between and in contact with the two components of the article. The curable 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).

[0085] Example

[0086] 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 fillers are D50 particle sizes. Table 1 lists the materials of the curable compositions used in the samples described below. Note: “Vi” represents vinyl, “Me” represents methyl, and “TC filler” is a guide for thermal fillers. SYL-OFF is a trademark of The Dow Chemical Company.

[0087] Table 1 Note: Viscosity was measured using a glass capillary Canon-Fensk viscometer at 25°C according to ASTM D445-21. The D50 uses Mastersizer from Malvern Instruments. ™ Measured by a 3000 laser diffraction particle size analyzer.

[0088] Samples of Examples (IE) 1 to 4 and Comparative Examples (CE) 1 to 10 of the present invention

[0089] 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 a sample. Vi polymer A-1, SiH crosslinker B-1, SiH crosslinker B-2, treatment agents D-1 and D-2, and TC fillers C2 and C3 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. Half of the TC filler C1 was added and mixed at 1000 RPM for 20 seconds, then at 1500 RPM for 20 seconds. The remaining TC filler C1 was added and mixed in the same manner. The resulting composition was scraped from the cup to ensure homogeneous mixing, and then Pt catalyst E-1 and inhibitor F-1 were added and mixed in a similar manner to obtain a curable composition sample.

[0090] The extrusion rate, thermal conductivity, and appearance of the obtained thermally conductive composition samples were evaluated according to the following test methods:

[0091] Thermal resistance test

[0092] 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.

[0093] Adhesive layer thickness test

[0094] 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.

[0095] Extrusion rate test

[0096] 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 g / min. The objective of this invention is to achieve an extrusion rate of at least 70 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”).

[0097] Thermal conductivity test

[0098] 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). The cured sample, measuring 25 mm × 25 mm × 8 mm, was prepared by curing the above-prepared curable thermally conductive silicone composition sample at 100 °C for 60 minutes. The objective of this invention is to achieve a thermal conductivity of at least 5.0 W / m × K.

[0099] hardness

[0100] Instron Shore is used according to ASTM D2240-00. ™ The Conveloader instrument was used to measure the hardness of the cured sample at 25°C, and the value was recorded 3 seconds after the sample came into contact with the Shore 00 tester probe. The cured sample was prepared as described above in the thermal conductivity test. An acceptable Shore 00 hardness is no greater than 50 at 25°C.

[0101] Reliability testing

[0102] Dispense the sample (0.2 mL) onto an aluminum plate and clamp it with a glass slide, using spacers to control the thickness to 0.5 mm. Cure the sample at 100°C for 60 minutes, then place it in a thermal shock test chamber (ESPEC NorthAmerica) ranging from -40°C to 140°C for 168 hours (each cycle consists of one hour, i.e., 30 minutes at -40°C and 30 minutes at 140°C. For example, hold at -40°C for 30 minutes, then immediately increase the temperature to 140°C and hold for 30 minutes, then immediately decrease the temperature to -40°C and hold for 30 minutes). The appearance of the resulting sample is then evaluated by visual inspection. If no voids are observed, the sample has good reliability. Otherwise, if voids are observed, the sample fails the reliability test.

[0103] Each sample was characterized by the extrusion rate test described above, the thermal conductivity test, and the thermal resistance test.

[0104] Table 2 presents the characterization results for samples IE1 to IE4. As shown in Table 2, all IE samples contain novel combinations of thermally conductive fillers (C1), (C2), and (C3) with specific SiH / Vi ratios (i.e., 0.7 to 1.0) and specific molar ratios of SiH in (B-2) to SiH in (B-1) (i.e., 6.0 to 20.0), achieving the desired TC (TC ≥ 5 W / m*K) and TR (TR ≤ 0.12℃*cm). 2 It exhibits a Shore 00 hardness of ≤50 and good reliability, with a minimum thickness ( / W) and an ER (ER≥70g / min). Furthermore, all IE samples achieved a BLT of 80µm or less.

[0105] Table 2

[0106] 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, using a SiH / Vi ratio <0.7, exhibited voids during reliability testing. CE 2, using a SiH / Vi ratio >1.0, provided excessive hardness and also exhibited voids during reliability testing. For CE 3, where the molar ratio of SiH in (B-2) to SiH in (B-1) was greater than 20, voids were observed during reliability testing. CE 4, containing AlN with a D50 less than 8 μm, exhibited poor machinability and was not dispensable. CE 5, containing AlN or Al2O3 with a D50 of 8 μm to 35 μm, provided an undesirable low TC. CE 6, containing different filler packages, exhibited poor machinability (not dispensable). CE 7, with a SiH / SiH ratio in (B-2) less than 6.0 in (B-1), provided excessive hardness. CE 8, which contained no ZnO with a D50 of 0.1 μm to 0.3 μm, and CE 9, which contained no spherical Al2O3 with a D50 of 0.3 μm to 4 μm, both exhibited poor processability and were not dispensable. CE 10, which contained only irregular Al2O3 and no spherical Al2O3 with a D50 of 0.3 μm to 4 μm, showed an undesirable low ER.

[0107] Table 3 Note: In Tables 2 and 3 above: "Fill weight %" refers to the weight percentage of the total thermally conductive filler relative to the total weight of all components in the sample. "Package volume %" refers to the volume percentage of total thermally conductive packing relative to the total volume of all components in the sample. The “SiH / Vi ratio” refers to the molar ratio of all silicon-bonded hydrogen atoms to vinyl groups in (B-1) (including (B-1-1) and (B-1-2)) and (B-2) of the sample. The ratio of SiH in (B-2) to SiH in (B-1) refers to the molar ratio of silicon-bonded hydrogen atoms in (B-2) to silicon-bonded hydrogen atoms in (B-1) including (B-1-1) and (B-1-2). "TC filler C1 weight%" refers to the combined concentration (weight%) of Al2O3 and AlN particles with D50 in the range of 8μm to 35μm relative to the total weight of all components in the sample. The above test methods were used to evaluate “ER”, “TC”, “TR”, “BLT”, “hardness”, and “appearance in reliability testing”.

Claims

1. A curable composition, wherein, based on the weight of the curable composition, the curable composition comprises: (A) 1% to 4% by weight 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 of formula (I): R a 2R'SiO-(R a 2SiO) b -SiR'R a 2 (I) Where R a Each time it appears, it is independently an alkyl group with 1 to 6 carbon atoms or an aryl group with 6 to 10 carbon atoms, and each time it appears, it is independently an alkenyl group, and the subscript b is greater than 0; (B) A polyorganohydrosiloxane component, wherein the polyorganohydrosiloxane component comprises: (B-1) Polysiloxanes having the average chemical structure of formula (II-1): R M 3SiO-(R M HSiO) c (R M 2SiO) d -SiR M 3 (II-1) (B-2) Polysiloxanes having the average chemical structure of formula (II-2): HR M 2SiO(R M 2SiO) i SiR M 2H (II-2) Where R M Each time it appears, it is independently an alkyl group or phenyl group having 1 to 6 carbon atoms, with subscript c in the range of 2 to 30, subscript d in the range of 3 to 120, and subscript i in the range of 10 to 150; The polysiloxane (B-1) and the polysiloxane (B-2) are present in an amount providing a molar ratio of 6.0 to 20.0 of silicon-bonded hydrogen atoms in the polysiloxane (B-2) to silicon-bonded hydrogen atoms in the polysiloxane (B-1); The polyorganohydrosiloxane component is present in an amount providing a total silicon-bonded hydrogen atom to alkenyl group molar ratio of 0.7 to 1.0 in the composition; (C) 93% to 97% by weight of thermally conductive filler, wherein the thermally conductive filler comprises: (C1) Alumina particles with a D50 in the range of 8 to 35 micrometers, aluminum nitrite particles with a D50 in the range of 8 to 35 micrometers, or mixtures thereof; (C2)D50 consists of spherical alumina particles ranging from 0.3 micrometers to 4 micrometers; and (C3) D50 zinc oxide particles in the range of 0.1 micrometers to less than 0.3 micrometers; and (D) A filler treatment agent selected from trialkoxysilyl diorganopolysiloxane, alkyltrialkoxysilane, or mixtures thereof.

2. The curable composition according to claim 1, wherein, based on the weight of the curable composition, the curable composition further comprises: (E) a platinum-based hydrosilylation catalyst in an amount sufficient to provide 0.5 parts per million to 30 parts per million of platinum, (F) a hydrosilylation inhibitor in a concentration of 0.001 wt% to 0.1 wt%, or a mixture thereof.

3. The curable composition according to claim 1 or 2, wherein the molar ratio of silicon-bonded hydrogen atoms in the polysiloxane (B-2) to silicon-bonded hydrogen atoms in the polysiloxane (B-1) is in the range of 7.0 to 16.0, and the molar ratio of total silicon-bonded hydrogen atoms to alkenyl groups in the composition is in the range of 0.8 to 0.

95.

4. The curable composition according to any one of claims 1 to 3, wherein the alkenyl-functionalized polyorganosiloxane comprises a polyorganosiloxane of formula (I), wherein each R a For methyl, each R' is vinyl, and the subscript b is in the range of 20 to 200.

5. The curable composition according to any one of claims 1 to 4, wherein the concentration of the zinc oxide particles (C3) is in the range of 10% to 25% by weight, based on the weight of the curable composition.

6. The curable composition according to any one of claims 1 to 5, wherein, based on the weight of the curable composition, the combined concentration of the alumina particles with a D50 in the range of 8 micrometers to 35 micrometers and the aluminum nitrite particles with a D50 in the range of 8 micrometers to 35 micrometers is in the range of 40% to 60% by weight, the concentration of the spherical alumina particles (C2) is in the range of 20% to 40% by weight, the zinc oxide particles (C3) are irregular particles, and the concentration of the zinc oxide particles (C3) is in the range of 10% to 25% by weight.

7. The curable composition according to any one of claims 1 to 6, wherein, based on the weight of the curable composition, the filler treatment agent comprises 0.5 wt% to 2.5 wt% of a mono-trialkoxysilyloxy-terminated diorganopolysiloxane having an average chemical structure of formula (IV): R c 3Si[OR d 2Si] g -Y-Si(OR e )3 (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.

8. A method for using a curable composition according to any one of claims 1 to 7, the method comprising the following steps: a) Applying the curable composition to electronic components, and b) The curable composition is cured by heat.

9. An electronic article comprising a curable composition according to any one of claims 1 to 7, the curable composition being located between and in contact with two components of the electronic article, wherein the curable composition is in a cured or non-cured form.

10. The electronic article of claim 9, wherein the curable composition in the cured form has a Shore 00 hardness of not more than 50 at 25 degrees Celsius according to ASTM D2240-00.

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