An analytical method for the thermal conductive powder formulation in a thermal conductive material

Abstract

The present invention relates to an analysis method for the thermal conductive powder formula in a thermal conductive material, comprising the steps of: performing solid-liquid extraction on the thermal conductive material with an organic solvent, and filtering to separate the filtrate and the solid residue; adding hydrofluoric acid to the solid residue, fully stirring and then filtering, washing and drying the filter cake to obtain a dried powder; performing particle size distribution testing on the dried powder to obtain a particle size distribution curve, determining each peak in the particle size distribution curve and its corresponding particle size classification, so as to determine the median particle size of each single-particle-size powder in the powder; respectively performing particle size distribution testing on the single-particle-size raw materials to obtain particle size distribution curves, and performing fitting analysis on them to obtain the particle size ratio of the thermal conductive powder in the thermal conductive material. The analysis method for the thermal conductive powder formula in the thermal conductive material of the present invention can perform quantitative analysis on the formula, and has the advantages of simple operation, fast speed, small error and high efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal conductive materials, and particularly to an analysis method for the thermal conductive powder formula in a thermal conductive material. Background Art

[0002] A thermal conductive material is a polymer composite thermal conductive material that uses silicone oil resin as an adhesive base material and achieves thermal conductivity by filling thermal conductive powder. It includes thermal conductive gaskets, thermal conductive gels, thermal conductive silicone greases, thermal conductive adhesives, phase change materials, etc. It is mainly used for the transfer interface between electronic devices and heat sinks or product casings, thereby playing an important role in reducing the working temperature of electronic devices and extending the service life of electronic devices. It has the advantages of convenient use, high thermal conductivity, stable thermal performance, good compressibility, self-adhesion, high cleanliness, etc., and is an excellent thermal conductive material with a wide range of applications.

[0003] The thermal conductive material generally consists of a silicone oil part, a thermal conductive powder part, and other parts. The silicone oil part is a polymer obtained by crosslinking vinyl silicone oil and hydrogen-containing silicone oil under the action of a catalyst; the powder part is generally alumina powder or thermal conductive materials such as aluminum nitride and silicon carbide; other parts include a catalyst for catalyzing the crosslinking reaction of vinyl silicone oil and hydrogen-containing silicone oil, an inhibitor for inhibiting the catalytic effect, and functional additives such as silane coupling agents, carbon black, graphite, graphene, silicon dioxide, and titanium dioxide.

[0004] With the development of the times, it is required that the used electronic materials and electronic components, etc. have functions such as high frequency and high speed, large-capacity storage, and high-speed signal transmission. Such functions will cause a substantial increase in the heat flux density of the chip, and a large amount of heat energy is likely to cause the aging of electronic components, reducing the service life and reliability of the chip. Therefore, higher requirements are put forward for thermal conductive materials. The domestic thermal conductive material started late, especially the thermal conductive materials used in the field of semiconductor chips are still mainly imported. Therefore, more research needs to be invested in the field of thermal conductive materials. The most important performance of the thermal conductive material is the thermal conductivity, which is mainly affected by the solid content and particle size ratio of the thermal conductive powder. Among them, the particle size ratio of the powder is complex, and it is difficult to directly obtain the particle size compounding ratio information in the sample. Therefore, there is an urgent need to develop an analysis method for the powder particle size formula in the thermal conductive material, aiming to conveniently, accurately, and quickly obtain the thermal conductive powder formula in an unknown sample. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide an analysis method for the powder formula in a thermal conductive material. Through the method of the present invention, the quantitative analysis of the powder formula in an unknown thermal conductive material can be realized, and it has the advantages of convenient operation, small error, high efficiency, and fast speed.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] (1) Perform solid-liquid extraction on the thermal conductive material with an organic solvent, and filter to separate the filtrate and the solid residue;

[0008] (2) Add hydrofluoric acid to the solid residue, stir well and then filter. After washing and drying the filter cake, a thermal conductive powder is obtained;

[0009] (3) Perform particle size distribution testing on the thermal conductive powder to obtain a particle size distribution curve, and determine that the thermal conductive powder is composed of n kinds of single-particle-size powders mixed together. The median particle size of the nth kind of single-particle-size powder is the particle size classification corresponding to the nth peak in the particle size distribution curve, where n is a natural number and n≥1;

[0010] (4) Perform particle size distribution testing on the n kinds of single-particle-size powders respectively, construct a fitted particle size distribution curve and fit it with the particle size distribution curve in step (3), and analyze to obtain the formula of the thermal conductive powder in the thermal conductive material;

[0011] Further, the thermal conductive material includes a silicone oil part and a thermal conductive powder part;

[0012] And / or, the thermal conductive material is preferably one of a thermal conductive gasket, a thermal conductive silicone grease, a thermal conductive gel, and a thermal conductive adhesive;

[0013] And / or, the thermal conductive powder is one or a combination of one or more of alumina, aluminum nitride, or silicon carbide powder;

[0014] And / or, the median particle size D50 of the thermal conductive powder is above 1 μm.

[0015] Further, the silicone oil part is a polymer obtained by crosslinking vinyl silicone oil and hydrogen-containing silicone oil under the action of a catalyst;

[0016] Further, in the step (1), the organic solvent includes one or a mixture of one or more of dichloromethane, chloroform, tetrahydrofuran, toluene, and acetone; preferably one or a mixture of one or more of dichloromethane and tetrahydrofuran;

[0017] And / or, the solid-liquid extraction ratio is 2-20 mL of extraction solvent per gram of thermal conductive material, preferably 5-10 mL;

[0018] And / or, the number of solid-liquid extraction times is 2-4 times, preferably 3 times;

[0019] Further, in the step (2), the solid residue is magnetically stirred and dispersed with a dispersion solvent;

[0020] Further, the dispersion solvent includes one or a mixture of one or more of water, methanol, ethanol, n-propanol, isopropanol, acetonitrile, tetrahydrofuran, and acetone; preferably, the dispersion solvent is water;

[0021] And / or, the stirring time each time is 10 to 60 minutes, preferably 15 to 30 minutes;

[0022] And / or, the concentration of the hydrofluoric acid is 35% to 50%; preferably 40% to 45%;

[0023] And / or, the ratio of the dispersion solvent to the hydrofluoric acid system is 0.2 to 5.0, preferably 0.5 to 2.0;

[0024] And / or, 1 to 20 mL of hydrofluoric acid is required per gram of solid residue, preferably 2 to 10 mL, more preferably 4 to 6 mL;

[0025] And / or, the stirring temperature is 10 to 40 °C, preferably 20 - 30 °C;

[0026] And / or, the number of water washing times is generally 3 times, and the amount used each time is 10 mL;

[0027] And / or, the number of alcohol washing times is generally 3 times, and the amount used each time is 10 mL; the alcohol washing solvent includes one or a combination of methanol and ethanol;

[0028] And / or, the drying temperature is 80 to 120 °C;

[0029] And / or, the drying time is 30 to 60 minutes.

[0030] In the step (2), the purpose of adding hydrofluoric acid is to degrade the cross-linked silicone resin and remove the organic components for surface modification of the powder, so that the powder becomes non-agglomerated, and the particle size distribution test can be carried out reliably and effectively.

[0031] In the step (2), the purpose of the standing operation is to make the powder settle naturally to the bottom, usually 5 minutes is enough; the purpose of pouring out most of the supernatant is to remove most of the hydrofluoric acid solution, which is convenient for the subsequent filtration operation. The purpose of water washing is to remove the residual hydrofluoric acid, and the purpose of alcohol washing is to remove the residual water.

[0032] Further, the step (4) includes the following steps:

[0033] (4.1) Perform particle size distribution tests on the n kinds of single-particle-size powders respectively, and obtain a total of n particle size distribution curves of the single-particle-size powders. The particle size distribution curve Y of the nth single-particle-size powder n = f n (x), where n is a natural number and n ≥ 1, x represents particle size classification, with the unit of μm, and Y n represents volume density, with the unit of %;

[0034] (4.2) Construct a fitted particle size distribution curve where An represents the mass fraction of the n-th single-particle-size powder;

[0035] (4.3) Adjust the A in step (4.2) n until the fitted particle size distribution curve Y 拟合 basically coincides with the particle size distribution curve in step (3), and obtain the corresponding fraction A of each single-particle-size powder n , thereby obtaining the particle size ratio of the heat-conducting powder in the heat-conducting material.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) Compared with the qualitative analysis method of SEM scanning electron microscope, the present invention can realize the quantitative analysis of the powder formula;

[0038] (2) After solid-liquid extraction of the heat-conducting material, by treating the solid residue with hydrofluoric acid, the cross-linked silicone oil resin can be degraded and the organic components on the surface of the powder can be removed, so that the heat-conducting powder to be measured is no longer agglomerated, improving the accuracy of the subsequent particle size distribution test;

[0039] (3) Taking the existing single-particle-size powder for particle size distribution test and making a fitting comparison with the heat-conducting material to be measured, the particle size formula of the heat-conducting powder in the heat-conducting material to be measured can be quickly obtained, improving the analysis efficiency and the accuracy of the analysis result. Specific embodiments

[0040] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0041] The present invention provides a preparation method of a heat-conducting gasket, including the following steps:

[0042] (1) Perform solid-liquid extraction on the heat-conducting material with an organic solvent, and filter to separate the filtrate and the solid residue;

[0043] (2) Add hydrofluoric acid to the solid residue, stir well and then filter. The filter cake is washed and dried to obtain the heat-conducting powder;

[0044] (3) Perform particle size distribution tests on the thermal conductive powder to obtain a particle size distribution curve, and determine that there are n peaks in the particle size distribution curve and the particle size classification corresponding to each peak, so as to determine that the thermal conductive powder is composed of a mixture of n single-particle size powders. The median particle size of the single-particle size powder is the particle size classification corresponding to the peak, and n is a natural number and n≥1;

[0045] (4) Perform particle size distribution tests on the n single-particle size powders respectively to obtain particle size distribution curves, construct a fitted particle size distribution curve and fit it with the particle size distribution curve described in step (3), and analyze to obtain the particle size ratio of the thermal conductive powder in the thermal conductive material.

[0046] <Thermal Conductive Material>

[0047] In the present invention, the thermal conductive material may be a conventional thermal conductive material in the field such as a thermal conductive gasket, thermal conductive silicone grease, thermal conductive gel, thermal conductive adhesive, etc. The thermal conductive material includes an organosilicon oil part and a thermal conductive powder part; further, in the embodiment of the present invention, the organosilicon oil part is a cross-linked product of vinyl silicone oil and hydrogen-containing silicone oil, and the specific molecular structural formula and reaction process are as follows:

[0048]

[0049] In the present invention, the thermal conductive powder part of the thermal conductive material may be one or more of alumina, aluminum nitride, silicon carbide, etc.; further, in the embodiment of the present invention, the thermal conductive powder of the thermal conductive material is preferably alumina powder; the alumina powder may be modified alumina or unmodified alumina in the shape of a sphere, an angle, etc.;

[0050] The thermal conductive material of the present invention may further include a catalyst, an inhibitor, and functional additives such as silane coupling agent, carbon black, graphite, graphene, silicon dioxide, titanium dioxide, etc.; further, in the embodiment of the present invention, the catalyst of the thermal conductive material is preferably Karstedt platinum catalyst, and the inhibitor is diallyl maleate;

[0051] In the present invention, the median particle size of the single-particle size powder in the thermal conductive powder is above 1 μm; for example, the thermal conductive powder is composed of a mixture of one or more single-particle size powders with median particle sizes of 2 μm, 5 μm, 10 μm, 20 μm, 45 μm, 70 μm, 90 μm, 120 μm, etc.

[0052] <Organic Solvent>

[0053] In the present invention, the role of the organic solvent is to dissolve the incompletely cross-linked organic silicone oil portion in the thermally conductive material, thereby completing the preliminary separation of the powder portion in the thermally conductive material; the organic solvent has the ability to dissolve silicone oil, and generally selected solvents of medium polarity, such as aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, aliphatic hydrocarbons, ethers, ketones, ester solvents, etc., specifically for example, dichloromethane, chloroform, tetrahydrofuran, toluene, acetone, acetonitrile, carbon tetrachloride, benzene, ethyl acetate, etc.; in the embodiment of the present invention, one or more of dichloromethane, chloroform, tetrahydrofuran, toluene, and acetone are preferred, and one or more of dichloromethane and tetrahydrofuran are more preferred.

[0054] <Solid-Liquid Extraction>

[0055] In the present invention, the solid-liquid extraction is the process of separating a solid mixture using a liquid or solvent. Specifically, the solid is immersed in a selected solvent, and the readily soluble components in the solid are dissolved into a solution, thereby separating them from the undissolved solid residue. In the present invention, the solid-liquid extraction process is to add an organic solvent to the thermal conductive material, dissolve it under magnetic stirring at room temperature, and then filter and separate to obtain a filter cake and a filtrate; the filter cake is the solid residue portion of the thermal conductive material that is insoluble in the solvent, mainly including the thermal conductive powder portion and the fully cross-linked silicone oil portion; the filtrate is a solution formed by the components of the thermal conductive material that are readily soluble in the organic solvent and the organic solvent.

[0056] In the present invention, the filtrate contains a silicone oil resin dissolved in an organic solvent, specifically incompletely cross-linked polydimethylsiloxane; the molecular weight and molecular weight distribution of the silicone oil resin in the filtrate can be determined by gel permeation chromatography (GPC), and the test parameters of the gel permeation chromatography are:

[0057] Column: Agilent PLgel single pore size column, part number PL1110-6530, 7.5 × 300 mm, with guard column, part number PL110-1520, 7.5 × 50 mm;

[0058] Column temperature: 40°C;

[0059] Mobile phase: chromatography grade tetrahydrofuran;

[0060] Mobile phase flow rate: 0.7 ml / min;

[0061] Detector: differential detector;

[0062] Sample injection volume: 20 μL.

[0063] In the present invention, the solid residue includes the thermally conductive powder portion and the silicone oil portion not dissolved by the organic solvent in step (1), specifically the fully cross-linked silicone oil portion;

[0064] In step (1) of the present invention, the organic solvent dissolves the organic components in the heat-conducting material, and the filtrate and the solid residue are separated by filtration, realizing the preliminary separation of the inorganic heat-conducting powder part in the heat-conducting material.

[0065] <Dispersion solvent>

[0066] In the present invention, the dispersion solvent is used to disperse the solid residue, and generally a solvent miscible with water is selected, including one or a mixture of water, alcohol solvents, tetrahydrofuran, acetonitrile, acetone, etc.; the alcohol solvents include conventional alcohol solvents in the art such as methanol, ethanol, n-propanol, isopropanol, etc.; water is preferably selected as the dispersant in the embodiments of the present invention;

[0067] In step (2) of the present invention, the stirring time is selected as the time when the powder is evenly dispersed, generally selected as 10 - 60 min, and further preferably 15 - 30 min; it is preferably 30 min in the embodiments of the present invention;

[0068] The inventors have found through a large number of studies that hydrofluoric acid can not only decompose the cross-linked silicone oil part, but also remove the surface-modified organic components of the powder, and at the same time has a small reaction activity with the heat-conducting powder part. Therefore, adding hydrofluoric acid treatment can make the powder non-agglomerated, so as to reliably and effectively carry out particle size distribution testing.

[0069] At the same time, the inventors have found in the research that improper use of hydrofluoric acid will also cause certain corrosion to the powder, damage the original shape of the powder, and even affect the particle size of the powder, resulting in poor accuracy of the test results. Therefore, further, in step (2) of the present invention, the concentration of hydrofluoric acid is controlled at <35% - 50%>, preferably <40% - 45%>; the ratio of the dispersion solvent to the hydrofluoric acid system is <0.2 - 5.0>, preferably <0.5 - 2.0>; <1 - 20 mL> of hydrofluoric acid is required per gram of sample, preferably <2 - 10 mL>, more preferably <4 - 6 mL>; the stirring temperature is <10 - 40 °C>, preferably <15 - 30 °C>, more preferably <25 °C>.

[0070] In step (2) of the present invention, the standing operation is to make the heat-conducting powder settle to the bottom naturally, usually <5 min> is enough; pouring out most of the supernatant is to remove most of the hydrofluoric acid solution, facilitating the subsequent filtration operation. The purpose of water washing is to remove the residual hydrofluoric acid, and alcohol washing is to remove the residual water. The number of water washing times is generally <3 times>, and the amount used each time is <10 mL>; the number of alcohol washing times is generally <3 times>, and the amount used each time is <10 mL>; the alcohols are common alcohol solvents in the art such as methanol and ethanol.

[0071] In step (2) of the present invention, the drying temperature is <80 - 120 °C>; the drying time is <30 - 60 min>.

[0072] <Particle size distribution test>

[0073] In the embodiment of the present invention, the instrument used for particle size distribution test is a Mastersizer laser particle size analyzer. After adding an appropriate amount of sample, the analysis and detection system of the instrument is started, and finally the particle size distribution data and the corresponding particle size distribution curve of the sample to be tested are obtained. In the particle size distribution curve of the present invention, the abscissa is the particle size classification, with the unit of μm; the ordinate is the volume concentration, with the unit of %.

[0074] The inventor found in the research that the particle size distribution curve of the heat-conducting powder obtained after being treated with hydrofluoric acid can reflect the true powder formulation information. The particle size classification corresponding to the peak in the particle size distribution curve described in step (3) of the present invention is the median particle size of the single-particle-size powder in the heat-conducting powder. For example, if there are two peaks in the particle size distribution curve, corresponding to particle size classifications of 2 μm and 20 μm respectively, it means that the heat-conducting powder is partially composed of two powders with median particle sizes of 2 μm and 5 μm respectively; if there are n peaks, it means that the heat-conducting powder is composed of n single-particle-size powders mixed together, and the median particle size of each powder is the particle size classification corresponding to the corresponding peak. Therefore, the particle size distribution curve measured in step (3) of the present invention can obtain the information on which several single-particle-size powder raw materials the heat-conducting powder is mixed with.

[0075] <Fitting analysis>

[0076] In step (4) of the present invention, the fitting analysis is to use the particle size distribution of the existing single-particle-size powder raw materials to make a fitting comparison with the unknown sample and analyze the powder formulation of the unknown sample. The specific steps are as follows:

[0077] (4.1) Perform particle size distribution tests on n single-particle-size powders respectively, and obtain the particle size distribution curves Y n = f n (x) of the nth single-particle-size powder respectively, where n is a natural number and n≥1, x represents the particle size classification, with the unit of μm, and Y n represents the volume density, with the unit of %.

[0078] (4.2) Construct a fitting particle size distribution curve where A n represents the mass fraction of the nth single-particle-size powder;

[0079] (4.3) Adjust the A n in step (4.2) until the fitting particle size distribution curve Y 拟合 is basically consistent with the particle size distribution curve described in step (3), and obtain the corresponding fractions A n of each single-particle-size powder, so as to obtain the particle size ratio of the heat-conducting powder in the heat-conducting material.

[0080] In step (4) of the present invention, the particle size distributions of the n particle sizes obtained from the analysis in step (3) are first tested respectively to obtain the particle size distribution curves of n single-particle-size powder materials. The particle size distribution curve of the nth single-particle-size powder is Y n = f n (x); a fitting particle size distribution curve is constructed using the particle size distribution curves of the n single-particle-size powder materials where A n represents the number of parts of the nth particle size in the heat-conducting powder; the A n is adjusted until the particle size distribution constructed for fitting analysis basically coincides with the particle size distribution described in step (3), and the A n corresponding to the powder materials of each single particle size is obtained, thereby obtaining the particle size ratio of the heat-conducting powder in the heat-conducting material Description of the Drawings

[0081] Figure 1 The following are the analysis and test diagrams related to Embodiment 1 of the present invention Figure 1 (a) is a comparison diagram of the particle size distribution curves measured after physical mixing (red) of alumina powder (45μm:5μm = 2:1) and after making it into a heat-conducting material and treating it with hydrofluoric acid (green); Figure 1 (b) is the particle size distribution curve measured after the powder is made into a heat-conducting material without being treated with hydrofluoric acid; Figure 1 (c) is a comparison diagram of the fitting particle size distribution curve (red) and the particle size distribution curve (blue) of the heat-conducting material after being treated with hydrofluoric acid

[0082] Figure 2 The following are the analysis and test diagrams related to Embodiment 2 of the present invention Figure 2 (a) is a comparison diagram of the particle size distribution curves measured after physical mixing (red) of alumina powder (90μm:20μm:5μm = 3:1:2) and after making it into a heat-conducting material and treating it with hydrofluoric acid (green); Figure 2 (b) is the particle size distribution curve measured after the powder is made into a heat-conducting material without being treated with hydrofluoric acid; Figure 2 (c) is a comparison diagram of the fitting particle size distribution curve (red) and the particle size distribution curve (blue) of the heat-conducting material after being treated with hydrofluoric acid

[0083] Figure 3 The following are the analysis and test diagrams related to Embodiment 3 of the present invention Figure 3 (a) is a comparison diagram of the particle size distribution curves measured after physical mixing (red) of alumina powder (90μm:20μm:5μm:2μm = 3:1:1.5:0.5) and after making it into a heat-conducting material and treating it with hydrofluoric acid (green); Figure 3 (b) is the particle size distribution curve measured after the powder is made into a heat-conducting material without being treated with hydrofluoric acid; Figure 3(c) is a comparison chart of the fitted particle size distribution curve (red) and the particle size distribution curve of the thermal conductive material after being treated with hydrofluoric acid (blue).

[0084] Example

[0085] The present invention is described below with reference to examples, but the present invention is not limited to the following examples.

[0086] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0087] Preparation Example 1: Preparation of thermal conductive material DH-P1:

[0088] Add vinyl silicone oil, hydrogenated silicone oil, thermal conductive powder, catalyst, inhibitor and other additives into a mixing device and disperse them, then evacuate the mixture to obtain a thermal conductive mixture. The mixture is then cured at 140°C for 2 hours. The mass fractions of the components are as follows: 7.5 parts vinyl silicone oil (viscosity 950 mPa.s), 0.5 parts hydrogenated silicone oil (viscosity 200 mPa.s); 45 μm median particle size (D 50 =45μm) of Al2O3 powder 61.3 parts, 5μm median particle size (D 50 =5μm) Al2O3 powder 30.7 parts; Custer catalyst 0.008 parts, inhibitor diallyl maleate 0.002 parts, nano carbon black 0.06 parts.

[0089] The operating steps of the mixing device are as follows:

[0090] (1) Weigh thermal conductive powders of different particle sizes in a mixing container 1, place them in a rotary machine with a counterweight, adjust the rotary speed to 1000 r / min and the rotation speed to 600 r / min, evacuate the machine and mix them for 3 minutes under an absolute pressure of ≤20 Pa;

[0091] (2) Weigh vinyl silicone oil, catalyst, inhibitor and other additives in mixing container 2, place them in a rotary machine with a counterweight, adjust the revolution speed to 1000 r / min and the rotation speed to 600 r / min, evacuate and mix for 3 minutes under an absolute pressure of ≤20 Pa; then add hydrogenated silicone oil, place them in a rotary machine with a counterweight, and mix for 3 minutes under the same conditions;

[0092] (3) Add the mixed thermal conductive powder in container 1 to container 2, place it in the autorotator with a counterweight, adjust the revolution speed to 1500 r / min and the rotation speed to 900 r / min, evacuate and mix for 3 minutes under the condition of absolute pressure ≤ 20 Pa; repeat the autorotation condition 3 times to obtain a uniformly dispersed thermal conductive mixture.

[0093] Preparation Example 2: Preparation of Thermal Conductive Material DH-P2:

[0094] The experimental steps of this preparation example are the same as those of Preparation Example 1, except that the powder types and proportions in this preparation example are different. Among them, the mass parts of each component are as follows: 7.5 parts of vinyl silicone oil (viscosity 950 mPa·s), 0.5 parts of hydrogen-containing silicone oil (viscosity 200 mPa·s); 46.0 parts of Al2O3 powder with a median particle size of 90 μm (D 50 = 90 μm), 15.3 parts of Al2O3 powder with a median particle size of 20 μm (D 50 = 20 μm), 30.7 parts of Al2O3 powder with a median particle size of 5 μm (D 50 = 5 μm); 0.008 parts of Karstedt catalyst, 0.002 parts of inhibitor diallyl maleate, and 0.06 parts of nano carbon black.

[0095] Preparation Example 3: Preparation of Thermal Conductive Material DH-P3:

[0096] The experimental steps of this preparation example are the same as those of Preparation Example 1, except that the powder types and proportions in this preparation example are different. Among them, the mass parts of each component are as follows: 7.5 parts of vinyl silicone oil (viscosity 950 mPa·s), 0.5 parts of hydrogen-containing silicone oil (viscosity 200 mPa·s); 46.0 parts of Al2O3 powder with a median particle size of 90 μm (D 50 = 90 μm), 15.3 parts of Al2O3 powder with a median particle size of 20 μm (D 50 = 20 μm), 23.0 parts of Al2O3 powder with a median particle size of 5 μm (D 50 = 5 μm), 7.7 parts of Al2O3 powder with a median particle size of 2 μm (D 50 = 2 μm); 0.008 parts of Karstedt catalyst, 0.002 parts of inhibitor diallyl maleate, and 0.06 parts of nano carbon black.

[0097] Example 1

[0098] (1) Weigh 5.004 g of thermal conductive material DH-P1 and put it into a 100 mL single-neck glass flask. Add 50 mL of dichloromethane and stir magnetically at room temperature for 30 min. Filter the solid residue, and continue to perform solid-liquid extraction on the filter cake with 50 mL of dichloromethane twice. Combine the dichloromethane filtrates and concentrate and rotary evaporate them to obtain 0.305 g of colorless oily liquid. Dry the filter cake and weigh it to be 4.690 g. Measure the particle size distribution of the filter cake with a particle size tester, and the results are as Figure 1 (b) shown;

[0099] (2) Take 4.690 g of the dried filter cake powder and put it into a 100 mL plastic centrifuge tube. Add 20 mL of water and disperse it by magnetic stirring. Then add 20 mL of hydrofluoric acid (40% concentration) and stir magnetically at room temperature for 30 min. Let it stand for 5 min and pour out the supernatant. Filter, wash the filter cake 3 times with 10 mL of water and 3 times with 10 mL of methanol, and dry it at 100 °C for 30 min. 4.541 g of the heat-conducting powder is obtained.

[0100] (3) Take the dried heat-conducting powder to measure the particle size distribution, and obtain the particle size distribution curve of the heat-conducting powder. The results are as Figure 1 (a) shown. The particle size gradings corresponding to the peaks in the particle size distribution curve are 5 μm and 45 μm respectively. At the same time, compare the particle size distribution measurement of the heat-conducting powder mixture in step (1) (61.3 parts of Al2O3 powder with a median particle size of 45 μm and 30.7 parts of Al2O3 powder with a median particle size of 5 μm). The comparison results are as Figure 1 (a) shown.

[0101] (4) Conduct particle size distribution tests on the Al2O3 powder with a median particle size of 45 μm and the Al2O3 powder with a median particle size of 5 μm respectively to obtain the particle size distribution curves Y1 = f1(x) and Y2 = f2(x); construct a fitted particle size distribution curve Adjust the A1 and A2 until the particle size distribution curve Y 拟合 basically coincides with the particle size distribution curve measured after hydrofluoric acid treatment in step (3). At this time, the Al2O3 powder formula of the heat-conducting material is 45 μm:5 μm = A1:A2. Take A1 = 2 and A2 = 1 for verification, obtain the fitted particle size distribution curve, and compare it with the particle size distribution curve of the powder after hydrofluoric acid treatment. The comparison results are as Figure 1 (c) shown.

[0102] Example 2

[0103] (1) Weigh 5.007 g of the heat-conducting material DH-P2 and put it into a 100 mL single-neck glass flask. Add 50 mL of dichloromethane and stir magnetically at room temperature for 30 min. Filter the solid residue, and continue to perform solid-liquid extraction on the filter cake 2 times with 50 mL of dichloromethane. Combine the dichloromethane filtrates and concentrate and rotary evaporate to obtain 0.310 g of a colorless oily liquid. The filter cake is dried and weighed to be 4.684 g. Measure the particle size distribution of the filter cake with a particle size tester. The results are as Figure 2 (b) shown;

[0104] (2) Put 4.684 g of the dried filter cake powder into a 100 mL plastic centrifuge tube, add 20 mL of water, disperse it with magnetic stirring, then add 20 mL of hydrofluoric acid aqueous solution (40% concentration), and stir magnetically at room temperature for 30 min. Let it stand for 5 min, and pour out the supernatant. Filter, wash the filter cake 3 times with 10 mL of water and 3 times with 10 mL of methanol, and dry it at 100 °C for 30 min. 4.551 g of heat-conducting powder is obtained.

[0105] (3) Take the dried heat-conducting powder to measure the particle size distribution, and obtain the particle size distribution curve of the heat-conducting powder. The results are as Figure 2 (a) shown. The particle size classifications corresponding to the peaks in the particle size distribution curve are 5 μm, 20 μm, and 90 μm respectively. At the same time, compare the particle size distribution of the heat-conducting powder mixture in step (1) (46.0 parts of Al2O3 powder with a median particle size (D 50 = 90 μm), 15.3 parts of Al2O3 powder with a median particle size (D 50 = 20 μm), and 30.7 parts of Al2O3 powder with a median particle size (D 50 = 5 μm)). The comparison results are as Figure 2 (a) shown.

[0106] (4) Respectively conduct particle size distribution tests on the Al2O3 powder with a median particle size of 90 μm, the Al2O3 powder with a median particle size of 20 μm, and the Al2O3 powder with a median particle size of 5 μm to obtain the particle size distribution curves Y1 = f1(x), Y2 = f2(x), Y1 = f3(x); construct a fitted particle size distribution curve Adjust the A1, A2, and A3 until the particle size distribution curve Y 拟合 basically coincides with the particle size distribution curve measured after hydrofluoric acid treatment in step (3). At this time, the Al2O3 powder formula of the heat-conducting material is 90 μm: 20 μm: 5 μm = A1: A2: A3. Take A1 = 3, A2 = 1, A3 = 2 for verification, obtain the fitted particle size distribution curve, and compare it with the particle size distribution curve of the powder after hydrofluoric acid treatment. The comparison results are as Figure 2 (c) shown.

[0107] Example 3

[0108] (1) Weigh 6.005 g of the heat-conducting material DH-P3 and put it into a 100 mL single-neck glass flask, add 50 mL of dichloromethane, stir magnetically at room temperature for 30 min, filter the solid residue, continue to perform solid-liquid extraction on the filter cake with 50 mL of dichloromethane 2 times, combine the dichloromethane filtrate, concentrate and rotary evaporate to obtain 0.362 g of colorless oily liquid, and dry and weigh the filter cake to be 5.638 g. Measure the particle size distribution of the filter cake with a particle size tester. The results are as Figure 3 (b) shown;

[0109] (2) Take 5.638 g of the dried filter cake powder and put it into a 100 mL polytetrafluoroethylene centrifuge tube. Add 20 mL of water and disperse it by magnetic stirring. Then add 20 mL of hydrofluoric acid aqueous solution (40% concentration), and stir magnetically at room temperature for 30 min. Let it stand for 5 min, and pour out the supernatant. Filter, wash the filter cake 3 times with 10 mL of water and 3 times with 10 mL of methanol, and dry it at 100 °C for 30 min. 5.447 g of the thermally conductive powder is obtained.

[0110] (3) Take the dried thermally conductive powder to measure the particle size distribution, and obtain the particle size distribution curve of the thermally conductive powder. The results are as Figure 3 (a) shown. The particle size classifications corresponding to the peaks in the particle size distribution curve are 2 μm, 5 μm, 20 μm, and 90 μm respectively. At the same time, measure the particle size distribution of the thermally conductive powder mixture in step (1) (46.0 parts of Al2O3 powder with a median particle size (D 50 = 90 μm), 15.3 parts of Al2O3 powder with a median particle size (D 50 = 20 μm), 23.0 parts of Al2O3 powder with a median particle size (D 50 = 5 μm), 7.7 parts of Al2O3 powder with a median particle size (D 50 = 2 μm)) and make a comparison. The comparison results are as Figure 3 (a) shown.

[0111] (4) Conduct particle size distribution tests on the Al2O3 powder with a median particle size of 90 μm, the Al2O3 powder with a median particle size of 20 μm, the Al2O3 powder with a median particle size of 5 μm, and the Al2O3 powder with a median particle size of 2 μm respectively to obtain the particle size distribution curves Y1 = f1(x), Y2 = f2(x), Y3 = f3(x), Y4 = f4(x); construct a fitted particle size distribution curve Adjust the A1, A2, A3, and A4 until the fitted particle size distribution Y 拟合 is basically consistent with the particle size distribution in step (3). At this time, the Al2O3 powder formula of the thermally conductive material is 90 μm: 20 μm: 5 μm: 2 μm = A1: A2: A3: A4. Take A1 = 3, A2 = 1, A3 = 1.5, A4 = 0.5 for verification, obtain the fitted particle size distribution curve, and compare it with the particle size distribution curve of the powder after hydrofluoric acid treatment. The comparison results are as Figure 3 (c) shown.

[0112] According to Figure 1 (b), Figure 2 (b), Figure 3(b) The data given by the particle size distribution curve shows that the particle size distribution is above 100 μm, which is extremely different from the raw materials used. Therefore, it is meaningless to directly measure the particle size distribution of the thermal conductive material without hydrofluoric acid treatment. The displayed particle size distribution cannot reflect the true particle size distribution of the thermal conductive powder because there are still organic components such as fully cross-linked silicone oil parts in the test sample that are not extracted by organic solvents, resulting in agglomeration of the thermal conductive powder. After hydrofluoric acid treatment and then particle size distribution test, the results are as Figure 1 (a), Figure 2 (a), Figure 3 (a) shown. It is basically consistent with the particle size distribution curve measured by using the thermal conductive powder raw material mixture with the same ratio, proving that the agglomerated thermal conductive powder can be dispersed through hydrofluoric acid treatment, restoring the true particle size distribution of the thermal conductive powder, thereby improving the accuracy of powder particle size formula quantification.

[0113] As Figure 1 (c), Figure 2 (c), Figure 3 (c) shown, the fitting result analysis shows that the fitting method adopted in the present invention can quickly and relatively accurately obtain the particle size formula of the thermal conductive powder. The fitting curve under the theoretical value of the particle size ratio is basically consistent with the particle size distribution curve measured after hydrofluoric acid treatment of the sample to be tested, thereby proving that the analysis method of the present invention can relatively quickly and accurately obtain the powder formula of the sample to be tested, with small error, fast speed and good operability.

[0114] Although the present invention has been described in detail above with general descriptions, specific embodiments and experiments, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A method for analyzing the formula of heat-conducting powder in a heat-conducting material, characterized in that, The steps include: (1) Performing solid-liquid extraction on the thermal conductive material using an organic solvent, and filtering and separating the filtrate and solid residue; (2) Add hydrofluoric acid to the solid residue, stir thoroughly and filter, wash and dry the filter cake to obtain thermal conductive powder; (3) performing a particle size distribution test on the thermally conductive powder to obtain a particle size distribution curve, determining that the thermally conductive powder is a mixture of n types of single particle size powders, the median particle size of the n-th single particle size powder is the particle size classification corresponding to the n-th peak in the particle size distribution curve, where n is a natural number and n≥1; (4) performing particle size distribution tests on the n types of single particle size powders to obtain particle size distribution curves, constructing fitted particle size distribution curves to fit the particle size distribution curves in step (3), and analyzing to obtain the formula of the thermal conductive powder in the thermal conductive material; The thermally conductive powder is one or more combinations of aluminum oxide, aluminum nitride or silicon carbide powder; The step (2) further comprises the following steps: dispersing the solid residue with a dispersing solvent by magnetic stirring, adding hydrofluoric acid thereto, and stirring thoroughly; standing, pouring off most of the supernatant; filtering, washing the filter cake with water, washing with alcohol, and drying to obtain a thermal conductive powder; the volume ratio of the dispersing solvent to the hydrofluoric acid is 0.5-2.0; the concentration of the hydrofluoric acid is 35%-50%; 2-10 mL of hydrofluoric acid is required for each gram of solid residue; The step (4) is specifically as follows: (4.1) Perform particle size distribution tests on the n types of single-particle-size powders respectively. The particle size distribution curve of the nth single-particle-size powder is Y n = ƒ n (x), where n is a natural number and n ≥ 1, x represents particle size classification, with the unit of μm, and Y n represents volume density, with the unit of %; (4.2) Construct the fitted particle size distribution curve Y 拟合 = ,in Indicates the mass fraction of the nth type of single particle size powder; (4.3) Adjust the until the fitted particle size distribution curve Y 拟合 is basically consistent with the particle size distribution curve described in step (3), and obtain the mass fraction corresponding to each single particle size powder , so as to obtain the formula of the heat-conducting powder in the heat-conducting material.

2. The method according to claim 1, wherein: The heat-conducting material includes a silicone oil portion and a heat-conducting powder portion.

3. The method according to claim 2, characterized in that: The silicone oil part is a cross-linked product of vinyl silicone oil and hydrogen-containing silicone oil.

4. The method according to claim 1, wherein: The thermally conductive material is selected from one of a thermally conductive gasket, a thermally conductive silicone grease, a thermally conductive gel, and a thermally conductive adhesive.

5. The method according to claim 1, wherein: The median particle size D50 of the thermally conductive powder is greater than 1 μm.

6. The method according to claim 1, wherein: The organic solvent in step (1) includes one or more combinations of dichloromethane, chloroform, tetrahydrofuran, toluene, and acetone.

7. The method according to any one of claims 1 to 6, characterized in that: The solid-liquid extraction ratio in step (1) is 2 to 20 mL of extraction solvent per gram of thermal conductive material; and the number of solid-liquid extractions is 2 to 4 times.

8. The method according to claim 1, wherein the dispersion solvent comprises one or more of water, methanol, ethanol, n-propanol, isopropanol, acetonitrile, tetrahydrofuran, and acetone.

9. The method according to claim 1, wherein the stirring time is 10 to 60 minutes; the drying temperature is 80 to 120°C, and the drying time is 30 to 60 minutes.

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