Thermal paste and preparation method thereof

Abstract

minutes at room temperature and pressure; and e) sealing the finished product of step d) in an environment not higher than

Description

[Technical Field]

[0001] This invention relates to a paste-like object and its manufacturing method, particularly a heat-dissipating paste and its manufacturing method. [Previous Technology]

[0002] Thermal paste, also known as thermal grease, is a paste-like substance used to fill the tiny gaps between electronic components (such as high-temperature chips) and heat sinks (such as heat sinks and water cooling blocks). Its main function is to improve heat conduction efficiency and ensure the stable operation of electronic devices. Common materials for thermal paste include basic silicone grease, metal-based, ceramic-based, and liquid metal. Common application scenarios include: when installing CPU / GPU in assembled computers or replacing heat sinks, the overall temperature may rise by more than 20°C if thermal paste is not used; high-power LED modules need thermal paste to conduct heat to the aluminum substrate to extend their lifespan; and the power components of power conversion modules (such as MOSFETs and power supplies) need to be coated with heat dissipation material to prevent overheating and burnout.

[0003] In the aforementioned usage scenarios, the temperature of the thermal paste in contact with the heat source is mostly between 40-50°C. At most, the contact temperature may reach above the boiling point due to the high temperature emitted by the object being applied. However, since the temperature of the heat-dissipating object on the other side of the thermal paste is not high, the thermal paste can achieve the expected heat dissipation effect. However, in certain special situations, such as in extremely low temperature environments of tens of degrees below zero, the thermal paste may become brittle due to reaching its unique glass transition temperature. In this case, the heat dissipation effect of the thermal paste may still be acceptable, but the thermal paste will gradually fall off and eventually lose its original intended function.

[0004] In order to solve the problem of embrittlement of existing thermal pastes under extremely low temperature conditions, it is necessary to develop a new type of thermal paste, which is the original intention of this invention. [Summary of the Invention]

[0005] This paragraph extracts and compiles certain features of the invention. Other features will be disclosed in subsequent paragraphs. Its purpose is to cover various modifications and similar arrangements within the spirit and scope of the appended claims.

[0006] To meet the aforementioned needs, the present invention proposes an innovative thermal paste. This thermal paste comprises 100 parts by weight of a polysiloxane and polybutadiene component, 600-1100 parts by weight of a thermally conductive filler component, 0.5-5 parts by weight of a platinum catalyst component, and 0.1-0.5 parts by weight of an inhibitor component. The polysiloxane and polybutadiene component, based on a total weight of 100 parts, comprises 50-90 parts by weight of a vinyl-functionalized polysiloxane, 5-40 parts by weight of a silicon-hydrogen bond-containing polysiloxane, and 1-10 parts by weight of a high-polymer polybutadiene. The thermally conductive filler material comprises, by weight, 40-80 parts of metal particles with a particle size between 10µm and 30µm, 19-50 parts of metal particles with a particle size between 0.5µm and 10 parts of metal oxide particles with a particle size below 0.5µm, based on a total weight of 100 parts; the metal particles are made of aluminum, copper, silver, gold, or copper-plated aluminum; the metal oxide particles are aluminum oxide, zinc oxide, or magnesium oxide; and the inhibitor component is alkyne.

[0007] Preferably, the alkyne is alkynyl alcohol or alkynyl diol.

[0008] Preferably, the platinum catalyst component is a diethylenetetramethyldisiloxane platinum complex methylsilicone oil solution.

[0009] According to the present invention, the molecular weight of the vinyl-functionalized polysiloxane is required to be between 500 Da and 8000 Da. Preferably, the CAS (Chemical Abstracts Service) number of the vinyl-functionalized polysiloxane is 68083-19-2, 26710-23-6 or 68584-83-8.

[0010] According to the present invention, the molecular weight of the polysiloxane containing silane-hydrogen bonds is required to be between 400 Da and 3000 Da. Preferably, the CAS number of the polysiloxane containing vinyl functional groups is 63148-57-2, 69013-23-6 or 70900-21-9.

[0011] According to the present invention, the molecular weight of the polybutadiene polymer is between 1400 Da and 10000 Da, cis-polybutadiene accounts for 90% to 99% of the total weight, and the vinyl content accounts for 35% to 60% of the total weight of the polybutadiene polymer.

[0012] The present invention also discloses a method for preparing a thermal paste, comprising the steps of: a) placing 100 parts by weight of the polysiloxane and polybutadiene components into a stirring container and stirring for at least 3 minutes at room temperature and pressure; b) adding 600-1100 parts by weight of the thermally conductive filler component into the stirring container and stirring for at least 3 hours at room temperature and pressure; c) adding 0.1-0.5 parts by weight of the inhibitor component into the stirring container and stirring for at least 3 minutes at room temperature and pressure; d) adding 0.5-5 parts by weight of the platinum catalyst component into the stirring container and stirring for at least 3 minutes at room temperature and pressure; and e) sealing the finished product of step d) in an environment not higher than -20°C at room temperature and pressure.

[0013] In the embodiments, the glass transition temperature of the thermal paste prepared according to the present invention is at least 10°C lower than that of commercially available products. The adjustment of the glass transition temperature mainly comes from the polybutadiene polymer; the more polybutadiene polymer, the lower the glass transition temperature of the thermal paste. The thermal conductivity is controlled by the ratio of the thermally conductive filler component to the polysiloxane and polybutadiene components; the higher the ratio, the higher the thermal conductivity of the thermal paste.

Implementation Method

[0014] The present invention will be described in more detail with reference to the following embodiments.

[0015] This invention discloses a thermal paste and its manufacturing method. The thermal paste comprises 100 parts by weight of polysiloxane and polybutadiene components, 600-1100 parts by weight of thermally conductive filler material components, 0.5-5 parts by weight of platinum catalyst components, and 0.1-0.5 parts by weight of inhibitor components. The contents and characteristics of these components are described below.

[0016] The polysiloxane and polybutadiene components, based on a total weight of 100 parts by weight, comprise 50-90 parts by weight of a vinyl-functionalized polysiloxane, 5-40 parts by weight of a silicon hydrogen bond-containing polysiloxane, and 1-10 parts by weight of polybutadiene polymer. The molecular weight of the vinyl-functionalized polysiloxane is required to be between 500 Da and 8000 Da. According to the present invention, the vinyl-functionalized polysiloxanes preferably used are vinyl-terminated polydimethyl siloxane (CAS (Chemical Abstracts Service) number 68083-19-2), vinyl silicone oil ((66-70% polydimethylsiloxane)-ethylene copolymer, 20-25 cSt) (CAS number 26710-23-6), or vinyl MQ silicone resin (CAS number 68584-83-8). Polysiloxanes containing silane-hydrogen bonds should have a molecular weight between 400 Da and 3000 Da. Preferably, use polymethylhydrosiloxane (CAS number 63148-57-2), hydroxyl-terminated methyhydrosiloxane dimethylsiloxane copolymer (CAS number 69013-23-6), or hydride-terminated polydimethylsiloxane (CAS number 70900-21-9). Polybutadiene polymers should have a molecular weight between 1400 Da and 10000 Da, with cis-polybutadiene comprising 90%–99% of the total weight and vinyl content comprising 35%–60% of the total polybutadiene polymer weight.

[0017] Traditionally, polysiloxanes are the main components of cross-linking reactions used to fix thermally conductive fillers. However, polysiloxanes have a high glass transition temperature (Tg, the temperature at which a glassy material can reversibly transition between a glassy state and a rubbery state). This means that using polysiloxanes alone to fix thermally conductive fillers will cause them to change from a soft and flexible state to a rigid "glassy state" at relatively high temperatures (-30℃ to -40℃). Polysiloxanes in the glassy state are prone to brittleness and cannot bond with thermally conductive materials. On the other hand, polybutadiene polymers have a lower glass transition temperature (approximately -106℃), and cross-linking them with polysiloxanes can lower the overall glass transition temperature. Experiments have shown that polybutadiene polymers with an average molecular weight of 2500 Da have excellent processability and a glass transition temperature reduction effect, but too high (above 10000 Da) or too low (below 1400 Da) will cause problems with poor processability and insignificant glass transition temperature reduction, respectively. Furthermore, according to this invention, the proportion of cis-polybutadiene is significantly higher than that of trans-polybutadiene, which is a variable affecting workability. Generally, the polybutadiene supplied by suppliers does not have an ideally uniform structure. In practice, suppliers adjust the vinyl content according to their own formulations, resulting in products with varying viscosity. In this invention, the vinyl content is used to account for 35% to 60% of the total polybutadiene polymer weight, taking into account its workability when mixed with thermally conductive filler components, resulting in moderate viscosity.

[0018] The thermally conductive filler component, based on a total weight of 100 parts by weight, includes 40-80 parts by weight of metal particles with a particle size between 10µm and 30µm, 19-50 parts by weight of metal particles with a particle size between 0.5µm and 10 parts by weight of metal oxide particles with a particle size below 0.5µm. The metal particles can be made of aluminum, copper, silver, gold, or copper-plated aluminum, while the metal oxide particles can be aluminum oxide, zinc oxide, or magnesium oxide. The thermally conductive filler component is in powder form and its weight is 6 to 11 times that of the polysiloxane and polybutadiene components. Since the thermally conductive filler component does not chemically react with the polysiloxane and polybutadiene components, when there is a large amount of the thermally conductive filler component, the overall adhesion becomes worse; however, when there is a small amount of the thermally conductive filler component, the distance between the components in the thermally conductive filler component becomes longer, and they may even be unable to contact other molecules, resulting in a decrease in thermal conductivity (thermal conductivity coefficient). Therefore, the aforementioned thermally conductive filler material composition between "6 times and 11 times" is preferred. This invention uses metal particles of different sizes to allow smaller metal particles to fill the spaces between larger metal particles (the spaces between metal particles or between metal particles and metal oxide particles are filled with polysiloxane and polybutadiene components). Metal particles and metal oxide particles act as heat conduction carriers; higher density results in better thermal conductivity. However, because small-sized metal particles have high surface activity, they can explode even with slight dust dispersion. Therefore, metal oxide particles are used to stabilize their activity, making raw material storage safer.

[0019] In this invention, the inhibitor component is an alkyne. The presence of alkynes can inhibit the crosslinking reaction between polysiloxane and polybutadiene components at room temperature (mainly relying on unsaturated hydrocarbons (functional groups) with triple bonds between carbon atoms). At higher operating temperatures, such as temperatures exceeding the boiling point, the aforementioned reaction is accelerated by the platinum catalyst component, the reason for which will be explained below. In practice, the alkyne is preferably a mono- or di-alkyne alcohol, and the platinum catalyst component can be a solution of diethylenetetramethyldisiloxane platinum complex methylsilicone oil with an average concentration of 5500 ppm.

[0020] See FIG. The preparation method of heat sink paste contains the following steps. Step 1: 100 parts by weight of the polysiloxane and polybutadiene fractions were stirred in a stirring vessel for at least 3 minutes at room temperature and pressure (S01). Normal temperature is defined as 25±1°C, while normal pressure is about one atmosphere. The material of the stirring container is not limited but must be strong and non-falling, embodiments of the present invention use an empty barrel of stainless steel as the stirring vessel. At the beginning of this step, polysiloxane containing vinyl functional groups, polysiloxane containing silicon hydrogen bond, and polybutadiene polymers in the polysiloxane and polybutadiene fractions were still occupying different positions of the stirring vessel (layered according to different feeding times). This method uses a blender for stirring, the rate of which can be 1-2 rounds per second. At the end of this step, the reaction of the polysiloxane with each component in the polybutadiene fraction has started.

[0021] Step 2: At room temperature and pressure, 600~1100 parts by weight of thermally conductive filling material fractions are added to the stirring vessel and stirred for at least 3 hours (S02). In this step, the purpose of stirring is to allow uniform dispersion of all components in the polysiloxane and polybutadiene fractions and the thermally conductive packing material fractions. As mentioned earlier, as all the components in the thermally conductive filler material fraction are very tiny particles, but the total weight is 6 to 13 times that of the polysiloxane and polybutadiene fractions, it is very difficult to stir uniformly in a short time, so the stirring time takes a minimum of 3 hours.

[0022] Step 3: At room temperature and pressure, 0.1~0.5 parts by weight of the inhibitor fraction are added to the stirring vessel and stirred for at least 3 minutes (S03). The addition of the inhibitor fraction before the platinum catalyst fraction is to reduce the cross-linking reaction of each component in the polysiloxane and polybutadiene fraction and avoid the accelerated reaction after the platinum catalyst fraction is added. Since the mixture at the end of the second step was evenly mixed and the amount of inhibitor fraction was relatively small, the stirring time did not need to be too long. Note that the amount of inhibitor fraction can be bounded between 0.5 parts by weight and 5 parts by weight, the amount of which determines the heating time when the heat sink paste is used.

[0023] Step 4: At room temperature and pressure, a platinum catalyst fraction of 0.5~5 parts by weight was stirred into the stirring vessel for at least 3 minutes (S04). The platinum catalyst fraction can accelerate the cross-linking reaction of various components in the polysiloxane and polybutadiene fractions, although it is subject to the inhibitor fraction, in this step, the cross-linking reaction is accelerated at room temperature. Of course, the amount of inhibitor fraction also determines how fast the reaction is.

[0024] Fifth Step: Under normal pressure, the finished product from the fourth step is sealed in an environment not exceeding -20°C (S05). Immediately after the fourth step, the finished product is cooled to below -20°C, which greatly reduces the effect of the platinum catalyst component. At this low temperature, the cross-linking reaction of the thermal paste becomes very slow, which is beneficial for preservation. When using the thermal paste, the thermal paste sealed at low temperature is uniformly heated; when it reaches the operating temperature, such as 130-140°C, the thermal paste is applied to the components that need heat dissipation, and the cross-linking reaction is accelerated by the platinum catalyst component. If the heating process (including the process of thawing after refrigeration) and the coating process are long, more inhibitor components can be used; conversely, less inhibitor components can be used.

[0025] The thermal paste of the present invention has a lower glass transition temperature and a similar thermal conductivity than existing thermal pastes, as illustrated below by several embodiments and comparative examples.

[0026] Comparative Example

[0027] The product used for comparison with the present invention is Shin-Etsu MicroSi, Inc., product serial number G769, a thermal grease commonly used in the electronics industry. According to official data, G769 has a thermal conductivity of 3.0 W / m °K, but no glass transition temperature is specified. Actual measurements show that the glass transition temperature of G769 is -40.1 °C. Considering the error of the testing instrument, this glass transition temperature may be -40 ± 1 °C. The above data is used to compare with the results of various embodiments of the present invention.

[0028] First Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 68083-19-2 90 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 63148-57-2 5 g Polybutadiene polymer 5 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper 790 g Metal particles with a diameter between 0.5µm and 10µm - copper 210 g Metal oxide particles - aluminum oxide 50 g Total 1050 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 0.5 g Inhibitor components Alkyne alcohol 0.1 g thermal conductivity 2.9 W / m °K Glass transition temperature -51.7 ℃ Table 1 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste of the first embodiment. As can be seen from Table 1, although the thermal conductivity of the thermal paste of the first embodiment is slightly worse than that of the comparative example, its glass transition temperature is 11°C lower than that of the comparative example.

[0029] Second Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 68083-19-2 90 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 63148-57-2 5 g Polybutadiene polymer 5 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper 790 g Metal particles with a diameter between 0.5µm and 10µm - copper 210 g Metal oxide particles - aluminum oxide 50 g Total 1050 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 5.0 g Inhibitor components Alkyne alcohol 0.5 g thermal conductivity 2.9 W / m °K Glass transition temperature -51.5 ℃ Table 2 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste in the second embodiment. Compared to the first embodiment, this embodiment increases the amount of platinum catalyst and inhibitor components, while the rest remain unchanged. The results show that although the glass transition temperature changes slightly, the amount of change is within the range of detection error. Therefore, the amount of platinum catalyst and inhibitor components claimed in this invention only affects the characteristics (reaction rate) during subsequent use and does not affect the thermal conductivity and glass transition temperature of the thermal paste.

[0030] Third Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 68083-19-2 90 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 63148-57-2 5 g Polybutadiene polymer 5 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper 420 g Metal particles with a diameter between 0.5µm and 10µm - copper 525 g Metal oxide particles - aluminum oxide 105 g Total 1050 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components Alkyne alcohol 0.1 g thermal conductivity 3.2 W / m °K Glass transition temperature -53.4 ℃ Table 3 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste in the third embodiment. The third embodiment is based on the first embodiment, but with a change in the proportions of the thermally conductive filler components, and the platinum catalyst component and inhibitor component are set at 1.5g and 0.1g, respectively. As shown in Table 3, the thermal conductivity of the thermal paste in the third embodiment is better than that of the comparative example, and the glass transition temperature is also lower at -53.4℃.

[0031] Fourth Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 68083-19-2 80 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 63148-57-2 15 g Polybutadiene polymer 5 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper 790 g Metal particles with a diameter between 0.5µm and 10µm - copper 210 g Metal oxide particles - aluminum oxide 50 g Total 1050 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components Alkyne alcohol 0.1 g thermal conductivity 3.0 W / m °K Glass transition temperature -54.2 ℃ Table 4 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste in the fourth embodiment. The fourth embodiment is based on the first embodiment, but with a change in the ratio of polysiloxane to polybutadiene components, and the platinum catalyst and inhibitor components are set at 1.5g and 0.1g, respectively. As shown in Table 4, the thermal conductivity of the thermal paste in the fourth embodiment is close to that of the comparative example, and the glass transition temperature is as low as -54.2℃.

[0032] Fifth Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 68083-19-2 80 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 63148-57-2 15 g Polybutadiene polymer 5 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper 420 g Metal particles with a diameter between 0.5µm and 10µm - copper 525 g Metal oxide particles - aluminum oxide 105 g Total 1050 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components Alkyne alcohol 0.1 g thermal conductivity 3.5 W / m °K Glass transition temperature -50.8 ℃ Table 5 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste in the fifth embodiment. The fifth embodiment is based on the fourth embodiment, but with a change in the proportions of the thermally conductive filler components. The ratio of metal particles with a particle size between 0.5µm and 10µm to metal oxide particles is increased, with the former accounting for approximately half. As shown in Table 5, the thermal conductivity of the thermal paste in the fifth embodiment is higher than that of the comparative example, and the glass transition temperature is -50.8℃.

[0033] Sixth Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 68083-19-2 60 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 63148-57-2 30 g Polybutadiene polymer 10 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper 790 g Metal particles with a diameter between 0.5µm and 10µm - copper 210 g Metal oxide particles - aluminum oxide 50 g Total 1050 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components Alkyne alcohol 0.1 g thermal conductivity 3.5 W / m °K Glass transition temperature -59.3 ℃ Table 6 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste in the sixth embodiment. The sixth embodiment is based on the fourth embodiment, but with a change in the ratio of polysiloxane to polybutadiene components. The content of polysiloxane containing vinyl functional groups is significantly reduced, and the content of polybutadiene polymer is the highest among all embodiments. As shown in Table 6, the thermal conductivity of the thermal paste in the sixth embodiment is higher than that of the comparative example, and the glass transition temperature is reduced to -59.3°C.

[0034] Seventh Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 68083-19-2 60 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 63148-57-2 30 g Polybutadiene polymer 10 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper 420 g Metal particles with a diameter between 0.5µm and 10µm - copper 525 g Metal oxide particles - aluminum oxide 105 g Total 1050 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components Alkyne alcohol 0.1 g thermal conductivity 4.2 W / m °K Glass transition temperature -61.8 ℃ Table 7 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste in the seventh embodiment. The seventh embodiment is based on the sixth embodiment, but with a change in the proportions of the thermally conductive filler components. The ratio of metal particles (0.5µm~10µm) to metal oxide particles is increased, with the former accounting for approximately half. The content of polybutadiene polymer is also the highest among all embodiments. As shown in Table 7, the thermal conductivity of the thermal paste in the seventh embodiment is significantly higher than that of the comparative example, and the glass transition temperature is significantly reduced to -61.8℃.

[0035] Eighth Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 68083-19-2 90 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 63148-57-2 9 g Polybutadiene polymer 1 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper 840 g Metal particles with a diameter between 0.5µm and 10µm - copper 200 g Metal oxide particles - aluminum oxide 10 g Total 1050 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components Alkyne alcohol 0.1 g thermal conductivity 2.8 W / m °K Glass transition temperature -46.5 ℃ Table 8 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste in the eighth embodiment. In this embodiment, the polysiloxane containing vinyl functional groups in the polysiloxane and polybutadiene components, and the metal particles with a particle size between 10µm and 30µm in the thermally conductive filler component, were adjusted to the highest level among all embodiments. The results show that the thermal conductivity of the thermal paste in the eighth embodiment is worse than that of the previous embodiment, and the reduction in glass transition temperature is also less significant.

[0036] Ninth Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 68083-19-2 90 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 63148-57-2 9 g Polybutadiene polymer 1 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper 420 g Metal particles with a diameter between 0.5µm and 10µm - copper 525 g Metal oxide particles - aluminum oxide 105 g Total 1050 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components Alkyne alcohol 0.1 g thermal conductivity 3.0 W / m °K Glass transition temperature -48.7 ℃ Table 9 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste in the ninth embodiment. The ninth embodiment is based on the eighth embodiment, but with a change in the proportions of the thermally conductive filler components. The ratio of metal particles with a particle size between 0.5µm and 10µm to metal oxide particles is increased, with the former accounting for approximately half. As shown in Table 9, the thermal conductivity of the thermal paste in the ninth embodiment is the same as that of the comparative example, but the glass transition temperature is reduced to -48.7°C.

[0037] Tenth Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 68083-19-2 50 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 63148-57-2 40 g Polybutadiene polymer 10 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper 840 g Metal particles with a diameter between 0.5µm and 10µm - copper 200 g Metal oxide particles - aluminum oxide 10 g Total 1050 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components Alkyne alcohol 0.1 g thermal conductivity 3.2 W / m °K Glass transition temperature -58.9 ℃ Table 10 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste in the tenth embodiment. The tenth embodiment is based on the eighth embodiment, but with a change in the ratio of polysiloxane to polybutadiene components. The proportion of polysiloxane containing vinyl functional groups is increased to half, and the content of polybutadiene polymer is also the highest among all embodiments. As shown in Table 10, the thermal conductivity of the thermal paste in the tenth embodiment is higher than that of the comparative example, and the glass transition temperature is -58.9°C.

[0038] Eleventh Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 68083-19-2 50 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 63148-57-2 40 g Polybutadiene polymer 10 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper 420 g Metal particles with a diameter between 0.5µm and 10µm - copper 525 g Metal oxide particles - aluminum oxide 105 g Total 1050 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components Alkyne alcohol 0.1 g thermal conductivity 3.8 W / m °K Glass transition temperature -63.1 ℃ Table 11 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste in the eleventh embodiment. The eleventh embodiment is based on the tenth embodiment, but with a change in the proportions of the thermally conductive filler components. The ratio of metal particles (0.5µm~10µm) to metal oxide particles is increased, with the former accounting for approximately half. The content of polybutadiene polymer is also the highest among all embodiments. As shown in Table 11, the thermal conductivity of the thermal paste in the eleventh embodiment increases to 3.8 W / m °K, and the glass transition temperature decreases to -63.1 °C.

[0039] Twelfth Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 68083-19-2 90 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 63148-57-2 5 g Polybutadiene polymer 5 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper 240 g Metal particles with a diameter between 0.5µm and 10µm - copper 300 g Metal oxide particles - aluminum oxide 60 g Total 600 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components Alkyne alcohol 0.1 g thermal conductivity 0.7 W / m °K Glass transition temperature -52.3 ℃ Table 12 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste in the twelfth embodiment. The twelfth embodiment is based on the third embodiment, but the amount of thermally conductive filler material relative to the polysiloxane and polybutadiene components is changed to six times the latter. As shown in Table 12, the thermal conductivity of the thermal paste in the twelfth embodiment is significantly reduced to 0.7 W / m °K, while the glass transition temperature remains relatively low at -52.3 °C. This demonstrates that the amount of thermally conductive filler material has a very large impact on thermal conductivity, almost exponentially, but the addition of polybutadiene polymer to the thermal paste still effectively reduces the glass transition temperature of the finished product.

[0040] Thirteenth Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 68083-19-2 60 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 63148-57-2 30 g Polybutadiene polymer 10 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper 240 g Metal particles with a diameter between 0.5µm and 10µm - copper 300 g Metal oxide particles - aluminum oxide 60 g Total 600 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components Alkyne alcohol 0.1 g thermal conductivity 0.8 W / m °K Glass transition temperature -60.3 ℃ Table 13 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste in the thirteenth embodiment. The thirteenth embodiment is based on the twelfth embodiment, but with a change in the ratio of polysiloxane to polybutadiene components. The proportion of polysiloxane containing vinyl functional groups is reduced, and the content of polybutadiene polymer is the highest among all embodiments. As shown in Table 13, the thermal conductivity of the thermal paste in the thirteenth embodiment remains lower than that of the comparative example, and the glass transition temperature is even lower.

[0041] Fourteenth Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 26710-23-6 90 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 69013-23-6 5 g Polybutadiene polymer 5 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - aluminum 320 g Metal particles with a particle size between 0.5µm and 10µm - aluminum 400 g Metal oxide particles - zinc oxide 80 g Total 800 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components acetylidene diol 0.1 g thermal conductivity 1.6 W / m °K Glass transition temperature -51.9 ℃ Table 14 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste of the fourteenth embodiment. The difference between the fourteenth embodiment and the previous embodiments is the change in the types of polysiloxane containing vinyl functional groups, polysiloxane containing silicon hydrogen bonds, metal particles, metal oxide particles, and inhibitor components. The amount of thermally conductive filler component relative to the polysiloxane and polybutadiene components is increased by 8 times. As shown in Table 14, the thermal conductivity of the thermal paste of the fourteenth embodiment is still lower than that of the comparative example, and the glass transition temperature of -51.9°C is also lower than that of the comparative example.

[0042] Fifteenth Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 68584-83-8 60 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 70900-21-9 30 g Polybutadiene polymer 10 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - silver 320 g Metal particles with a diameter between 0.5µm and 10µm - silver 400 g Metal oxide particles - magnesium oxide 80 g Total 800 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components acetylidene diol 0.1 g thermal conductivity 1.9 W / m °K Glass transition temperature -59.7 ℃ Table 15 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste in the fifteenth embodiment. The fifteenth embodiment differs from the previous embodiments in that the types of vinyl-functionalized polysiloxane, silicon-hydrogen bonded polysiloxane, metal particles, and metal oxide particles are changed; the content of vinyl-functionalized polysiloxane is also reduced; the content of polybutadiene polymer is the highest among all embodiments; and the amount of thermally conductive filler component relative to the polysiloxane and polybutadiene components is 8 times greater. As shown in Table 15, the thermal conductivity of the thermal paste in the fourteenth embodiment is still lower than that of the comparative example, while the glass transition temperature is reduced to -59.7°C.

[0043] Sixteenth Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 26710-23-6 90 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 69013-23-6 5 g Polybutadiene polymer 5 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper-plated aluminum 440 g Metal particles with a diameter between 0.5µm and 10µm - copper-plated aluminum 550 g Metal oxide particles - zinc oxide 110 g Total 1100 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components acetylidene diol 0.1 g thermal conductivity 3.5 W / m °K Glass transition temperature -52.8 ℃ Table 16 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste in the sixteenth embodiment. The sixteenth embodiment is based on the fourteenth embodiment, but with changes to the type of metal particles and the ratio of the thermally conductive filler component to the polysiloxane and polybutadiene components; the latter is increased to 11 times. As shown in Table 16, the thermal conductivity of the thermal paste in the sixteenth embodiment is significantly higher than that of the comparative example, while the glass transition temperature remains lower.

[0044] Seventeenth Embodiment Components Ingredient Name / Description Usage / Characteristic Value Polysiloxane and polybutadiene components Polysiloxanes containing vinyl functional groups - CAS No. 26710-23-6 60 g Polysiloxanes containing silane-hydrogen bonds - CAS No. 69013-23-6 30 g Polybutadiene polymer 10 g Total 100 g Thermally conductive filler material composition Metal particles with a diameter between 10µm and 30µm - copper-plated aluminum 440 g Metal particles with a diameter between 0.5µm and 10µm - copper-plated aluminum 550 g Metal oxide particles - zinc oxide 110 g Total 1100 g Platinum catalyst components Diethylenetetramethyldisiloxane platinum complex methyl silicone oil solution 1.5 g Inhibitor components acetylidene diol 0.1 g thermal conductivity 4.4 W / m °K Glass transition temperature -61.1 ℃ Table 17 lists the weight, thermal conductivity, and glass transition temperature of each component of the thermal paste of the seventeenth embodiment. The seventeenth embodiment is based on the sixteenth embodiment, but with a change in the ratio of polysiloxane to polybutadiene components. The polysiloxane containing vinyl functional groups is increased to approximately half by weight, and the content of polybutadiene polymer is also the highest among all embodiments. As shown in Table 17, the thermal conductivity of the thermal paste of the seventeenth embodiment is significantly higher than that of the comparative example, while the glass transition temperature is lower than that of the comparative example and the sixteenth embodiment.

[0045] As can be seen from the above embodiments, the thermal paste prepared according to the present invention has a different thermal conductivity than commercially available products depending on its composition, but its glass transition temperature is at least 10°C lower than that of commercially available products. The adjustment of the glass transition temperature mainly comes from the polybutadiene polymer; the more of it, the lower the glass transition temperature of the thermal paste. The thermal conductivity is controlled by the ratio of the thermally conductive filler component to the polysiloxane and polybutadiene components. The higher the ratio, the higher the thermal conductivity of the thermal paste, but an excessively high ratio will lead to poor workability, and therefore has an upper limit.

[0046] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the art can make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims. [Simplified Explanation of the Diagram]

[0047] Figure 1 is a flowchart of a method for preparing a thermal paste according to an embodiment of the present invention.

Claims

1. A thermal paste comprising 100 parts by weight of a polysiloxane and polybutadiene component, 600-1100 parts by weight of a thermally conductive filler component, 0.5-5 parts by weight of a platinum catalyst component, and 0.1-0.5 parts by weight of an inhibitor component, wherein, The polysiloxane and polybutadiene component, based on a total weight of 100 parts, comprises 50-90 parts by weight of polysiloxane containing vinyl functional groups, 5-40 parts by weight of polysiloxane containing silane-hydrogen bonds, and 1-10 parts by weight of polybutadiene polymer; the thermally conductive filler component, based on a total weight of 100 parts, comprises 40-80 parts by weight of metal particles with a particle size between 10µm and 30µm, 19-50 parts by weight of metal particles with a particle size between 0.5µm and 10 parts by weight of metal oxide particles with a particle size less than 0.5µm; the metal particles are made of aluminum, copper, silver, gold, or copper-plated aluminum; the metal oxide particles are aluminum oxide, zinc oxide, or magnesium oxide; the inhibitor component is an alkyne.

2. The thermal paste as claimed in claim 1, wherein the platinum catalyst component is a solution of diethylenetetramethyldisiloxane platinum complex methylsilicone oil.

3. The thermal paste as claimed in claim 1, wherein the polysiloxane containing vinyl functional groups has a molecular weight between 500 Da and 8000 Da.

4. The thermal paste as claimed in claim 3, wherein the CAS (Chemical Abstracts Service) number of the polysiloxane containing vinyl functional groups is 68083-19-2, 26710-23-6 or 68584-83-8.

5. The thermal paste as claimed in claim 1, wherein the molecular weight of the polysiloxane containing silicon hydrogen bonds is between 400 Da and 3000 Da.

6. The thermal paste as claimed in claim 5, wherein the CAS number of the polysiloxane containing silicon hydrogen bonds is 63148-57-2, 69013-23-6 or 70900-21-9.

7. The thermal paste as claimed in claim 1, wherein the molecular weight of the polybutadiene polymer is between 1400 Da and 10000 Da, cis-polybutadiene accounts for 90% to 99% of the total weight, and the vinyl content accounts for 35% to 60% of the total weight of the polybutadiene polymer.

8. A method for preparing a thermal paste, comprising the steps of: a) placing 100 parts by weight of the polysiloxane and polybutadiene components into a stirring container and stirring for at least 3 minutes at room temperature and pressure; b) adding 600-1100 parts by weight of the thermally conductive filler component into the stirring container and stirring for at least 3 hours at room temperature and pressure; c) adding 0.1-0.5 parts by weight of the inhibitor component into the stirring container and stirring for at least 3 minutes at room temperature and pressure; d) adding 0.5-5 parts by weight of the platinum catalyst component into the stirring container and stirring for at least 3 minutes at room temperature and pressure; and e) storing the finished product of step d) at an environment not exceeding -20°C at room temperature and pressure.

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