Bonding agent, solder matrix and self-fluxing diamond heat sink heat conducting sheet and preparation method

Abstract

The present application relates to a kind of binding agent, solder matrix and self-fusion diamond heat sink heat conducting sheet and preparation method, the raw material composition of binding agent is 15-40wt% polyvinylpyrrolidone, 0.5-7wt% BTA, 0-5wt% PG, 1-8wt% xanthan gum, 1-10wt% methyl cellulose, 0.5-12wt% polyamide wax and 0.1-1wt% polydimethylsiloxane, the rest is glycerol. The composition of solder is 60-75wt% silver, 20-34wt% copper, 1-6wt% titanium and 0.5-1wt% chromium. The above-mentioned solder and binding agent are prepared into solder matrix according to the ratio of 85-93wt%:7-15wt% respectively. In the process of welding with diamond, the above-mentioned solder matrix can form a closely combined binding layer between diamond and copper, and greatly improve the thermal conductivity of material. The thermal conductivity of diamond copper composite material of the present application reaches 960W / (m·K) at most;Process stability, the performance index repeatability of finished product is very good;Process is simple, production mode is simple, no operation difficulty, not limited by equipment and site, process control and industrialization popularization are facilitated.

Description

Technical Field

[0001] This invention relates to the field of diamond heat sink thermal conductive sheet technology, specifically to a binder, solder matrix, self-fluxing diamond heat sink thermal conductive sheet, and preparation method. Background Technology

[0002] In the electronics and semiconductor industries, heat generation is a significant issue for high-power components, creating a demand for high thermal conductivity materials. Copper, a common thermally conductive material, has a thermal conductivity of 400 W / (m·K), which is insufficient to meet the requirements.

[0003] Diamond has a thermal conductivity of around 2200 W / (m·K) at room temperature, making it the material with the highest thermal conductivity in nature. However, it has poor machinability and large-size diamonds are extremely expensive.

[0004] In existing technologies, the high-temperature and high-pressure preparation of diamond-based thermal conductive materials requires a six-sided top press as the main production equipment. This process is not only affected by numerous factors such as the pressure-transmitting performance of auxiliary materials, temperature conditions, pressure conditions, and ambient temperature, pressure, and humidity, but also incurs high electricity, labor, and auxiliary material processing costs. Other production methods utilizing plating or magnetron sputtering equipment for diamond surface alloying are also subject to multiple factors due to their complex processes and numerous steps.

[0005] The more complex the process and the more processing steps there are, the more factors that constrain the final product. To ensure the consistency and repeatability of product performance, existing technologies require highly precise process control, which can lead to variations in product performance and poor stability during large-scale production. This results in high requirements for process control personnel and equipment in the material preparation process, thereby increasing the difficulty of industrialization.

[0006] Currently available diamond-based thermal conductive materials are composites made by combining inexpensive, easily machinable, and thermally conductive copper with diamond, resulting in a diamond metal composite material with relatively good machinability (compared to that of diamond itself). However, diamond metal composite materials prepared by conventional methods have low thermal conductivity. Currently, the thermal conductivity of diamond-copper composite thermal conductive materials is only below 550 W / (m·K), which can only meet the heat dissipation requirements of low-end components and is difficult to meet the thermal management requirements of high-power electronic devices.

[0007] Diamond-copper composite thermal conductive materials have the following problems:

[0008] (1) Diamond has extremely poor wettability with copper (wetting angle > 140° at around 1100℃), resulting in poor interfacial bonding between diamond and copper. The insufficient contact between diamond and copper hinders the smooth conduction of heat in the material, which in turn leads to high thermal resistance between the two phases of the composite material and extremely poor thermal conductivity.

[0009] (2) The coefficients of thermal expansion of diamond and copper differ to some extent (coefficient of thermal expansion of diamond: (0.86±0.1)×10 - 6 K -1 The coefficient of thermal expansion of copper is 17 × 10⁻⁶. -6 K -1 This means that a large number of micro-gaps may appear between the two phases during the preparation of diamond-copper composite materials, which will significantly increase the interfacial thermal resistance, reduce the thermal conductivity, and ultimately make it difficult for the material to achieve a high thermal conductivity.

[0010] In addition, the poor bonding between diamond and copper and the difference in their coefficients of thermal expansion result in more voids and micro-gaps at the interface, which can reduce the service life of diamond-copper composite materials that need to be used in extreme, harsh environments or environments with drastic temperature changes.

[0011] Patent 202011373358.0 discloses a diamond / copper heat sink material for electronic packaging and its preparation method. It solves the problems of increased interfacial thermal resistance and diamond graphitization after diamond modification by adding melting point reducing elements such as silver, tin or indium tin alloy. In this solution, the thermal conductivity of the diamond / copper composite material is increased to more than 500 W / m·K, and the highest reaches 620 W / m·K, but it still cannot meet the thermal management requirements of high-power electronic devices. Summary of the Invention

[0012] The purpose of this invention is to increase the thermal conductivity of diamond-copper composite materials to over 700 W / m·K to meet the application requirements of high-power electronic devices. This invention first provides a binder applicable to diamond-copper composite materials, specifically:

[0013] A binder comprising 15-40 wt% polyvinylpyrrolidone, 0.5-7 wt% BTA (benzotriazole), 0-5 wt% PG (propylene glycol), 1-8 wt% xanthan gum, 1-10 wt% methylcellulose, 0.5-12 wt% polyamide wax and 0.1-1 wt% polydimethylsiloxane, with the remainder being glycerol.

[0014] The binder prepared using the above-mentioned raw materials and proportions provides a suitable liquid environment for the diamond blank and the solder matrix, allowing for thorough mixing and relatively uniform distribution of the solder within the gaps between diamond particles. This provides a favorable prerequisite for the formation of the bonding layer during the "welding and sintering treatment." Furthermore, the binder plays a role in eliminating air bubbles, preventing the agglomeration and sedimentation of the blank during the "raw material pretreatment" stage, and ensuring that the solder fully adheres to the diamond surface during the "welding and sintering treatment." In summary, the binder provides an environment with excellent material mixing and minimal adverse effects for the subsequent "raw material pretreatment" and "welding and sintering treatment" processes.

[0015] According to the binder provided by the present invention, the present invention further provides a solder matrix having a raw material composition of 85-93 wt% solder and 7-15 wt% binder of the present invention.

[0016] The amount of binder affects the distribution of solder and diamond particles during subsequent "raw material pretreatment" and "welding and sintering" processes. Too much or too little binder reduces the uniformity of solder distribution among the diamond particles, leading to localized areas of excessive or insufficient solder. This results in poor uniformity of molten solder distribution on the diamond surface during "welding and sintering," ultimately causing uneven bonding layers between the solder and diamond in the finished material. An excessively thick bonding layer significantly reduces the thermal conductivity between diamond and the bonding layer, while an excessively thin layer weakens the bond between the diamond and the metal, failing to effectively reduce the interfacial thermal resistance. Furthermore, excessive binder leaves a large amount of high-thermal-resistance binder material in the finished material, severely reducing its thermal conductivity.

[0017] Preferably, the solder is composed of 60-75 wt% silver, 20-34 wt% copper, 1-6 wt% titanium and 0.5-1 wt% chromium.

[0018] The function of the self-fusing diamond solder prepared using the above-mentioned raw materials and proportions is that, in the molten state, the solder can sufficiently wet, contact, adhere to, and bond with the diamond surface. For example... Figure 1As shown, during the "welding and sintering" process, in a vacuum high-temperature environment, the solder alloy melts and uniformly adheres to the diamond surface. The titanium in the solder first combines with the diamond to form a TiC transition layer (atomic bonding). This TiC transition layer then forms a metal composite layer (metallurgical bonding) with copper and silver. The presence of the TiC transition layer allows for efficient heat exchange between the metal composite layer and the diamond. This "diamond-TiC-metal composite layer-TiC-diamond" structure solves the problem of limited thermal conductivity and difficulty in achieving high thermal conductivity values ​​caused by poor wettability and bonding between copper and diamond. Furthermore, this solder eliminates the need for a separate diamond surface alloying step in the conventional diamond-copper composite material preparation process, simplifying the production process.

[0019] The preferred solder particle size is 300-700 mesh.

[0020] This invention further provides a method for preparing a self-fusing diamond copper heat sink thermal conductive sheet, comprising the following steps:

[0021] 1) Prepare raw diamond materials;

[0022] 2) Prepare the binder and mix the raw materials.

[0023] 3) Prepare the solder matrix by mixing and heating the raw materials;

[0024] 4) Raw material pretreatment: The bare diamond material and solder matrix are stirred and mixed, and then poured into a graphite mold for vibration, heating and drying to form a preform.

[0025] 5) Welding and sintering treatment: The preform is placed in a vacuum welding furnace for high-temperature welding and sintering treatment to produce diamond copper heat sink heat conduction sheet.

[0026] Preferably, in step 1), the composition of the diamond raw material is 35-55 wt% coarse raw material, 15-40 wt% intermediate raw material and 10-35 wt% fine raw material. The coarse raw material is selected from the particle size range of 16 / 18-35 / 40, the intermediate raw material is selected from the particle size range of 40 / 45-60 / 70, and the fine raw material is selected from the particle size range of 70 / 80-140 / 170.

[0027] The use of coarse, medium, and fine diamond blanks in the above ratio is to fill the gaps between the fine and medium blanks with the coarse blank, forming a denser diamond stack. This increases the contact area between the diamond and the solder matrix, enabling more efficient heat conduction and thus improving the thermal conductivity of the material.

[0028] Preferably, in step 4), 30-45 wt% of diamond raw material is stirred and mixed with 55-70 wt% of solder matrix.

[0029] Excessive raw diamond material can lead to direct contact between diamond particles. Since the bonding between diamond particles is merely a simple physical connection, the bonding effect is extremely poor, which will reduce the heat conduction efficiency in this area or even almost block heat conduction.

[0030] Preferably, in step 5), the welding sintering process includes the following steps;

[0031] 51) In the first heating and holding stage, under vacuum, the temperature is raised to 520℃-570℃ at a heating rate of 5℃ / min-10℃ / min and held for 15min-30min.

[0032] 52) In the second heating and holding stage, under vacuum, the temperature is raised to 750℃-790℃ at a heating rate of 7℃ / min-12℃ / min and held for 15min-30min.

[0033] 53) In the third heating and holding stage, under vacuum, the temperature is raised to 850℃-890℃ at a heating rate of 7℃ / min-12℃ / min and held for 3min-10min.

[0034] 54) In the fourth cooling stage, the temperature is cooled to room temperature at a cooling rate of 2℃ / min-7℃ / min under vacuum.

[0035] This process is to bond the self-fluxing diamond solder to the diamond surface and ultimately form the product. Excessive heating and cooling can cause cracking or gaps between diamonds due to the different coefficients of thermal expansion of various raw materials, leading to material fabrication failure or a significant reduction in the material's thermal conductivity.

[0036] Preferably, the heating temperature in step 3) is 120℃-150℃; the heating temperature in step 4) is 130-160℃.

[0037] According to the method provided by the present invention, the present invention also claims protection for the self-fusing diamond copper heat sink heat-conducting sheet prepared by the method according to the present invention.

[0038] The advantages of this invention are: 1. The thermal conductivity of the diamond-metal composite material reaches 960 W / (m·K);

[0039] 2. The process is stable, and the performance indicators of the finished product have excellent repeatability;

[0040] 3. The process is simple, the production method is straightforward, there are no operational difficulties, it is not limited by equipment and site, and it is easy to carry out process control and industrialization promotion. Attached Figure Description

[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0042] Figure 1 This is a schematic diagram illustrating the working mechanism of self-fluxing diamond solder.

[0043] Figure 2 This is a schematic diagram of the process flow for the diamond copper heat sink heat-conducting sheet in this invention.

[0044] Figure 3 This is a graph showing the detection results of Example 1.

[0045] Figure 4 This is a graph showing the detection results of Example 3.

[0046] Figure 5 This is a graph showing the detection results of Example 4.

[0047] Figure 6 This is a graph showing the detection results for Comparative Example 1.

[0048] Figure 7 This is a diagram showing the detection results for Comparative Example 4.

[0049] Figure 8 This is a graph showing the detection results for Comparative Example 6. Detailed Implementation

[0050] The present invention will now be clearly described in conjunction with specific embodiments. This description is merely illustrative and is not intended to limit the scope of the invention. Any modifications, equivalent substitutions, or improvements made by those skilled in the art based on the embodiments of the present invention without inventive effort to obtain all other embodiments should be included within the scope of protection of the present invention.

[0051] Example 1

[0052] According to Figure 2 The process flow shown is used to prepare the diamond copper heat sink heat-conducting sheet. The specific process is as follows:

[0053] 1. Preparation of raw diamond mixed particle size: Raw diamond materials with particle sizes of 35 / 40 mesh, 60 / 70 mesh and 140 / 170 mesh are added to the mixer in a mass ratio of 43%:30%:27% and thoroughly mixed.

[0054] 2. Mix 16% polyvinylpyrrolidone, 5% BTA, 1% PG, 3% xanthan gum, 2% methylcellulose, 6% polyamide wax and 0.5% polydimethylsiloxane with 66.5% glycerol to form a binder.

[0055] 3. Preparation of solder matrix: Mix 500-mesh silver, copper, titanium and chromium in proportions of 70%, 25%, 4% and 1% respectively to prepare a self-fluxing metal solder. Then, place the binder and the self-fluxing diamond solder in a mixer in proportion of 12%:88% and mix and stir at 140℃ for 30 minutes.

[0056] 4. Weigh the raw diamond material with mixed particle size and the solder matrix at a mass ratio of 36%:64%, and then mix them in a mixer for 30 minutes.

[0057] 5. Pour the mixed material from step 4 into a graphite mold, vibrate to compact it, and then bake it at 140℃ for 1.5 hours. After baking, it becomes a preform.

[0058] 6. The baked preform is placed in a vacuum welding furnace for welding and sintering. The welding and sintering process is divided into a first heating and holding stage, a second heating and holding stage, a third heating and holding stage, and a fourth cooling stage. The specific implementation parameters are as follows:

[0059] In the first heating and holding stage, under vacuum conditions, the temperature is raised to 560℃ at a heating rate of 7℃ / min and held for 15min.

[0060] In the second heating and holding stage, under vacuum conditions, the temperature is raised to 780℃ at a heating rate of 9℃ / min and held for 20min.

[0061] In the third heating and holding stage, under vacuum conditions, the temperature is raised to 880℃ at a heating rate of 9℃ / min and held for 4 minutes.

[0062] In the fourth cooling stage, the temperature is cooled to room temperature at a rate of 4℃ / min under vacuum.

[0063] After the above welding and sintering process, the material is removed, demolded, and trimmed to obtain a self-fluxing diamond copper heat sink heat conductor. The heat conductor is then tested, such as... Figure 3 As shown, the thermal conductivity of the heat-conducting sheet fabricated in this embodiment reaches 962 W / (m·K).

[0064] Example 2

[0065] 1. Preparation of raw diamond mixed particle size: Raw diamond materials with particle sizes of 16 / 18 mesh, 40 / 45 mesh and 70 / 80 mesh are added to the mixer in a mass ratio of 35%:32%:33% and thoroughly mixed.

[0066] 2. Mix 21% polyvinylpyrrolidone, 3% BTA, 2% PG, 4% xanthan gum, 1% methylcellulose, 5% polyamide wax and 0.3% polydimethylsiloxane with 63.7% glycerol to form a binder.

[0067] 3. Mix silver, copper, titanium and chromium with a particle size of 500 mesh in proportions of 63.2%, 30%, 6% and 0.8% respectively to prepare a self-fluxing metal solder. Then, place the binder and the self-fluxing diamond solder in a mixer at a ratio of 9%:91% and mix and stir at 140°C for 30 minutes to finally prepare the solder matrix.

[0068] 4. Weigh the raw diamond material with mixed particle size and the solder matrix at a mass ratio of 38%:62%, and then mix them in a mixer for 30 minutes.

[0069] 5. Pour the mixed material from step 4 into a graphite mold, vibrate to compact it, and then bake it at 140℃ for 1.5 hours. After baking, it becomes a preform.

[0070] 6. The baked preform is placed in a vacuum welding furnace for welding and sintering. The welding and sintering process is divided into a first heating and holding stage, a second heating and holding stage, a third heating and holding stage, and a fourth cooling stage. The specific implementation parameters are as follows:

[0071] In the first heating and holding stage, under vacuum conditions, the temperature is raised to 540℃ at a heating rate of 5℃ / min and held for 20min.

[0072] In the second heating and holding stage, under vacuum conditions, the temperature is raised to 760℃ at a heating rate of 8℃ / min and held for 20min.

[0073] In the third heating and holding stage, under vacuum conditions, the temperature is raised to 860℃ at a heating rate of 8℃ / min and held for 4 minutes.

[0074] In the fourth cooling stage, the temperature is cooled to room temperature at a rate of 4℃ / min under vacuum.

[0075] After the above welding and sintering process, the material is taken out, demolded and trimmed to obtain a self-fluxing diamond copper heat sink heat conduction sheet. The heat conduction sheet is tested and the thermal conductivity of the heat conduction sheet produced in this embodiment reaches 803 W / (m·K).

[0076] Example 3

[0077] 1. Preparation of raw diamond mixed particle size: Raw diamond materials with particle sizes of 30 / 35 mesh, 50 / 60 mesh and 80 / 100 mesh are added to a mixer in a mass ratio of 35%:32%:33% and thoroughly mixed.

[0078] 2. Mix 27% polyvinylpyrrolidone, 5% BTA, 0.5% PG, 4% xanthan gum, 1% methylcellulose, 5% polyamide wax and 0.3% polydimethylsiloxane with 57.2% glycerol to form a binder.

[0079] 3. Mix silver, copper, titanium and chromium with a particle size of 500 mesh at a ratio of 70%, 25%, 4% and 1% respectively to prepare a self-fluxing metal solder. Then, place the binder and the self-fluxing diamond solder at a ratio of 15%:85% in a mixer and mix them at 140°C for 30 minutes to finally prepare the solder matrix.

[0080] 4. Weigh the raw diamond material with mixed particle size and the solder matrix at a mass ratio of 35%:65%, and then mix them in a mixer for 30 minutes.

[0081] 5. Pour the mixed material from step 4 into a graphite mold, vibrate to compact it, and then bake it at 140℃ for 1.5 hours. After baking, it becomes a preform.

[0082] 6. The baked preform is placed in a vacuum welding furnace for welding and sintering. The welding and sintering process is divided into a first heating and holding stage, a second heating and holding stage, a third heating and holding stage, and a fourth cooling stage. The specific implementation parameters are as follows:

[0083] In the first heating and holding stage, under vacuum conditions, the temperature is raised to 540℃ at a heating rate of 5℃ / min and held for 20min.

[0084] In the second heating and holding stage, under vacuum conditions, the temperature is raised to 760℃ at a heating rate of 8℃ / min and held for 20min.

[0085] In the third heating and holding stage, under vacuum conditions, the temperature is raised to 860℃ at a heating rate of 8℃ / min and held for 4 minutes.

[0086] In the fourth cooling stage, the temperature is cooled to room temperature at a rate of 4℃ / min under vacuum.

[0087] After the above welding and sintering process, the material is removed, demolded, and trimmed to obtain a self-fluxing diamond copper heat sink heat conductor. The heat conductor is then tested, and the results are as follows: Figure 4As shown, the thermal conductivity of the heat-conducting sheet fabricated in this embodiment reaches 896 W / (m·K).

[0088] Example 4

[0089] 1. Preparation of raw diamond materials with mixed particle sizes: Raw diamond materials with particle sizes of 18 / 20 mesh, 60 / 70 mesh and 140 / 170 mesh are added to a mixer in a mass ratio of 55%:15%:30% and mixed thoroughly.

[0090] 2. Mix 15% polyvinylpyrrolidone, 7% BTA, 5% PG, 8% xanthan gum, 10% methylcellulose, 12% polyamide wax and 1% polydimethylsiloxane with 42% glycerol to form a binder.

[0091] 3. Preparation of solder matrix: Mix 300-mesh silver, copper, titanium and chromium in proportions of 60%, 34%, 5.5% and 0.5% respectively to prepare a self-fluxing metal solder. Then, place the binder and the self-fluxing diamond solder in a mixer in proportion of 13%:87% and mix and stir at 120°C for 30 minutes.

[0092] 4. Weigh the raw diamond material with mixed particle size and the solder matrix at a mass ratio of 30%:70%, and then mix them in a mixer for 30 minutes.

[0093] 5. Pour the mixed material from step 4 into a graphite mold, vibrate to compact it, and then bake it at 130℃ for 1.5 hours. After baking, it becomes a preform.

[0094] 6. The baked preform is placed in a vacuum welding furnace for welding and sintering. The welding and sintering process is divided into a first heating and holding stage, a second heating and holding stage, a third heating and holding stage, and a fourth cooling stage. The specific implementation parameters are as follows:

[0095] In the first heating and holding stage, under vacuum conditions, the temperature is raised to 520℃ at a heating rate of 10℃ / min and held for 30min.

[0096] In the second heating and holding stage, under vacuum conditions, the temperature is raised to 750℃ at a heating rate of 7℃ / min and held for 30 minutes.

[0097] In the third heating and holding stage, under vacuum conditions, the temperature is raised to 850℃ at a heating rate of 7℃ / min and held for 10 minutes.

[0098] In the fourth cooling stage, the temperature is cooled to room temperature at a rate of 2℃ / min under vacuum.

[0099] After the above welding and sintering process, the material is removed, demolded, and trimmed to obtain a self-fluxing diamond copper heat sink heat conductor. The heat conductor is then tested, such as... Figure 5 As shown, the thermal conductivity of the heat-conducting sheet fabricated in this embodiment reaches 766 W / (m·K).

[0100] Example 5

[0101] 1. Preparation of raw diamond materials with mixed particle sizes: Raw diamond materials with particle sizes of 35 / 40 mesh, 60 / 70 mesh and 140 / 170 mesh are added to a mixer in a mass ratio of 50%:40%:10% and thoroughly mixed.

[0102] 2. Mix 40% polyvinylpyrrolidone, 0.5% BTA, 1% xanthan gum, 1% methylcellulose, 0.5% polyamide wax and 0.1% polydimethylsiloxane with 56.9% glycerol to form a binder.

[0103] 3. Preparation of solder matrix: Mix 700-mesh silver, copper, titanium and chromium in proportions of 75%, 20%, 4% and 1% respectively to prepare a self-fluxing metal solder. Then, place the binder and the self-fluxing diamond solder in a mixer in proportion of 7%:93% and mix and stir at 150°C for 30 minutes.

[0104] 4. Weigh the raw diamond material with mixed particle size and the solder matrix at a mass ratio of 36%:64%, and then mix them in a mixer for 30 minutes.

[0105] 5. Pour the mixed material from step 4 into a graphite mold, vibrate to compact it, and then bake it at 160℃ for 1.5 hours. After baking, it becomes a preform.

[0106] 6. The baked preform is placed in a vacuum welding furnace for welding and sintering. The welding and sintering process is divided into a first heating and holding stage, a second heating and holding stage, a third heating and holding stage, and a fourth cooling stage. The specific implementation parameters are as follows:

[0107] In the first heating and holding stage, under vacuum conditions, the temperature is raised to 560℃ at a heating rate of 7℃ / min and held for 15min.

[0108] In the second heating and holding stage, under vacuum conditions, the temperature is raised to 790℃ at a heating rate of 12℃ / min and held for 15min.

[0109] In the third heating and holding stage, under vacuum conditions, the temperature is raised to 890℃ at a heating rate of 12℃ / min and held for 3 minutes.

[0110] In the fourth cooling stage, the temperature is cooled to room temperature at a rate of 4℃ / min under vacuum.

[0111] After the above welding and sintering process, the material is taken out, demolded and trimmed to obtain a self-fluxing diamond copper heat sink heat conduction sheet. The heat conduction sheet is tested and the thermal conductivity of the heat conduction sheet produced in this embodiment reaches 771 W / (m·K).

[0112] Example 6

[0113] 1. Preparation of raw diamond mixed particle size: Raw diamond materials with particle sizes of 35 / 40 mesh, 60 / 70 mesh and 140 / 170 mesh are added to the mixer in a mass ratio of 35%:30%:35% and thoroughly mixed.

[0114] 2. Mix 16% polyvinylpyrrolidone, 5% BTA, 1% PG, 3% xanthan gum, 2% methylcellulose, 6% polyamide wax and 0.5% polydimethylsiloxane with 66.5% glycerol to form a binder.

[0115] 3. Preparation of solder matrix: Mix 500-mesh silver, copper, titanium and chromium in proportions of 73.5%, 25%, 1% and 0.5% respectively to prepare a self-fluxing metal solder. Then, place the binder and the self-fluxing diamond solder in a mixer in proportion of 12%:88% and mix and stir at 140°C for 30 minutes.

[0116] 4. Weigh the raw diamond material with mixed particle size and the solder matrix at a mass ratio of 45%:55%, and then mix them in a mixer for 30 minutes.

[0117] 5. Pour the mixed material from step 4 into a graphite mold, vibrate to compact it, and then bake it at 140℃ for 1.5 hours. After baking, it becomes a preform.

[0118] 6. The baked preform is placed in a vacuum welding furnace for welding and sintering. The welding and sintering process is divided into a first heating and holding stage, a second heating and holding stage, a third heating and holding stage, and a fourth cooling stage. The specific implementation parameters are as follows:

[0119] In the first heating and holding stage, under vacuum conditions, the temperature is raised to 560℃ at a heating rate of 7℃ / min and held for 15min.

[0120] In the second heating and holding stage, under vacuum conditions, the temperature is raised to 780℃ at a heating rate of 9℃ / min and held for 20min.

[0121] In the third heating and holding stage, under vacuum conditions, the temperature is raised to 880℃ at a heating rate of 9℃ / min and held for 4 minutes.

[0122] In the fourth cooling stage, the temperature is cooled to room temperature at a rate of 7°C / min under vacuum.

[0123] After the above welding and sintering process, the material is taken out, demolded and trimmed to obtain a self-fluxing diamond copper heat sink heat conduction sheet. The heat conduction sheet is tested and the thermal conductivity of the heat conduction sheet produced in this embodiment reaches 756 W / (m·K).

[0124] Comparative Example 1

[0125] (Compared with Example 1, but without using the self-fluxing metal solder provided by this invention)

[0126] 1. Preparation of raw diamond mixed particle size: Raw diamond materials with particle sizes of 35 / 40 mesh, 60 / 70 mesh and 140 / 170 mesh are added to the mixer in a mass ratio of 43%:30%:27% and thoroughly mixed.

[0127] 2. Mix 16% polyvinylpyrrolidone, 5% BTA, 1% PG, 3% xanthan gum, 2% methylcellulose, 6% polyamide wax and 0.5% polydimethylsiloxane with 66.5% glycerol to form a binder.

[0128] 3. Preparation of solder matrix: Mix 500-mesh silver and copper at a ratio of 70% and 30% respectively to prepare a metal solder. Then, place the binder and metal solder at a ratio of 12%:88% in a mixer and mix at 140℃ for 30 minutes.

[0129] 4. Weigh the raw diamond material with mixed particle size and the solder matrix at a mass ratio of 36%:64%, and then mix them in a mixer for 30 minutes.

[0130] 5. Pour the mixed material from step 4 into a graphite mold, vibrate to compact it, and then bake it at 140℃ for 1.5 hours. After baking, it becomes a preform.

[0131] 6. The baked preform is placed in a vacuum welding furnace for welding and sintering. The welding and sintering process is divided into a first heating and holding stage, a second heating and holding stage, a third heating and holding stage, and a fourth cooling stage. The specific implementation parameters are as follows:

[0132] In the first heating and holding stage, under vacuum conditions, the temperature is raised to 560℃ at a heating rate of 7℃ / min and held for 15min.

[0133] In the second heating and holding stage, under vacuum conditions, the temperature is raised to 780℃ at a heating rate of 9℃ / min and held for 20min.

[0134] In the third heating and holding stage, under vacuum conditions, the temperature is raised to 880℃ at a heating rate of 9℃ / min and held for 4 minutes.

[0135] In the fourth cooling stage, the temperature is cooled to room temperature at a rate of 4℃ / min under vacuum.

[0136] After the above welding and sintering process, the material is removed, demolded, and trimmed to obtain a self-fluxing diamond copper heat sink heat conductor. The heat conductor is then tested, such as... Figure 6 As shown, the thermal conductivity of the heat-conducting sheet fabricated in this embodiment reaches 633 W / (m·K).

[0137] Comparative Example 2

[0138] (Compared with Example 1, but without using the self-fluxing metal solder provided by this invention)

[0139] 1. Preparation of raw diamond mixed particle size: Raw diamond materials with particle sizes of 35 / 40 mesh, 60 / 70 mesh and 140 / 170 mesh are added to the mixer in a mass ratio of 43%:30%:27% and thoroughly mixed.

[0140] 2. Mix 16% polyvinylpyrrolidone, 5% BTA, 1% PG, 3% xanthan gum, 2% methylcellulose, 6% polyamide wax and 0.5% polydimethylsiloxane with 66.5% glycerol to form a binder.

[0141] 3. Preparation of solder matrix: Mix the binder and 500-mesh copper in a ratio of 12%:88% in a mixer and stir at 140°C for 30 minutes.

[0142] 4. Weigh the raw diamond material with mixed particle size and the solder matrix at a mass ratio of 36%:64%, and then mix them in a mixer for 30 minutes.

[0143] 5. Pour the mixed material from step 4 into a graphite mold, vibrate to compact it, and then bake it at 140℃ for 1.5 hours. After baking, it becomes a preform.

[0144] 6. The baked preform is placed in a vacuum welding furnace for welding and sintering. The welding and sintering process is divided into a first heating and holding stage, a second heating and holding stage, a third heating and holding stage, and a fourth cooling stage. The specific implementation parameters are as follows:

[0145] In the first heating and holding stage, under vacuum conditions, the temperature is raised to 560℃ at a heating rate of 7℃ / min and held for 15min.

[0146] In the second heating and holding stage, under vacuum conditions, the temperature is raised to 780℃ at a heating rate of 9℃ / min and held for 20min.

[0147] In the third heating and holding stage, under vacuum conditions, the temperature is raised to 880℃ at a heating rate of 9℃ / min and held for 4 minutes.

[0148] In the fourth cooling stage, the temperature is cooled to room temperature at a rate of 4℃ / min under vacuum.

[0149] After the above welding and sintering process, the material is taken out, demolded and trimmed to obtain a self-fluxing diamond copper heat sink heat conduction sheet. The heat conduction sheet is tested and the thermal conductivity of the heat conduction sheet produced in this embodiment reaches 506 W / (m·K).

[0150] Comparative Example 3

[0151] (Compared with Example 1, instead of using multi-size diamond mixed raw material, single-size diamond is used as the raw diamond material.)

[0152] 1. Mix 16% polyvinylpyrrolidone, 5% BTA, 1% PG, 3% xanthan gum, 2% methylcellulose, 6% polyamide wax and 0.5% polydimethylsiloxane with 66.5% glycerol to form a binder.

[0153] 2. Mix silver, copper, titanium and chromium with a particle size of 500 mesh at a ratio of 72%, 25%, 2% and 1% respectively to prepare a self-fluxing metal solder. Then, place the binder and the self-fluxing diamond solder at a ratio of 12%:88% in a mixer and mix them at 140°C for 30 minutes to finally prepare the solder matrix.

[0154] 3. Weigh the 60 / 70 diamond blank and the solder matrix at a mass ratio of 36%:64%, and then mix them in a mixer for 30 minutes.

[0155] 4. Pour the mixed material from step 3 into a graphite mold, vibrate to compact it, and then bake it at 140℃ for 1.5 hours. After baking, it becomes a preform.

[0156] 5. The baked preform is placed in a vacuum welding furnace for welding and sintering. The welding and sintering process is divided into a first heating and holding stage, a second heating and holding stage, a third heating and holding stage, and a fourth cooling stage. The specific implementation parameters are as follows:

[0157] In the first heating and holding stage, under vacuum conditions, the temperature is raised to 560℃ at a heating rate of 7℃ / min and held for 15min.

[0158] In the second heating and holding stage, under vacuum conditions, the temperature is raised to 780℃ at a heating rate of 9℃ / min and held for 20min.

[0159] In the third heating and holding stage, under vacuum conditions, the temperature is raised to 880℃ at a heating rate of 9℃ / min and held for 4 minutes.

[0160] In the fourth cooling stage, the temperature is cooled to room temperature at a rate of 4℃ / min under vacuum.

[0161] After the above welding and sintering process, the material is taken out, demolded and trimmed to obtain a diamond copper heat-conducting sheet. The thermal conductivity of the heat-conducting sheet made in this comparative example reaches 644 W / (m·K).

[0162] The comparison shows that the thermal conductivity of the heat-conducting sheet obtained by using diamond raw material of single particle size is significantly lower than that of the heat-conducting sheet prepared by using diamond raw material of different particle size ratios according to the present invention.

[0163] Comparative Example 4

[0164] (Compared with Example 1, without using the binder provided by this invention)

[0165] 1. Preparation of raw diamond mixed particle size: Raw diamond materials with particle sizes of 35 / 40 mesh, 60 / 70 mesh and 140 / 170 mesh are added to the mixer in a mass ratio of 43%:30%:27% and thoroughly mixed.

[0166] 2. Mix 16% polyvinylpyrrolidone and 84% glycerol by mass to prepare a mixture.

[0167] 3. Mix silver, copper, titanium and chromium with a particle size of 500 mesh at a ratio of 72%, 25%, 2% and 1% respectively to prepare a self-fluxing metal solder. Then, place the mixture and the self-fluxing diamond solder at a ratio of 12%:88% in a mixer and mix them at 140°C for 30 minutes.

[0168] 4. Weigh the raw diamond material with mixed particle size and the solder matrix at a mass ratio of 36%:64%, and then mix them in a mixer for 30 minutes.

[0169] 5. Pour the mixed material from step 4 into a graphite mold, vibrate to compact it, and then bake it at 140℃ for 1.5 hours. After baking, it becomes a preform.

[0170] 6. The baked preform is placed in a vacuum welding furnace for welding and sintering. The welding and sintering process is divided into a first heating and holding stage, a second heating and holding stage, a third heating and holding stage, and a fourth cooling stage. The specific implementation parameters are as follows:

[0171] In the first heating and holding stage, under vacuum conditions, the temperature is raised to 560℃ at a heating rate of 7℃ / min and held for 15min.

[0172] In the second heating and holding stage, under vacuum conditions, the temperature is raised to 780℃ at a heating rate of 9℃ / min and held for 20min.

[0173] In the third heating and holding stage, under vacuum conditions, the temperature is raised to 880℃ at a heating rate of 9℃ / min and held for 4 minutes.

[0174] In the fourth cooling stage, the temperature is cooled to room temperature at a rate of 4℃ / min under vacuum.

[0175] After the above welding and sintering process, the material is removed, demolded, and trimmed to obtain a self-fluxing diamond copper heat sink heat conductor, such as... Figure 7 As shown, the thermal conductivity of the heat-conducting sheet fabricated in this embodiment reaches 563 W / (m·K).

[0176] The comparison shows that the thermal conductivity of the heat-conducting sheet prepared without the binder of the present invention is much lower than that of the heat-conducting sheet prepared with the binder of the present invention.

[0177] Comparative Example 5

[0178] (Comparison with Example 1, without using the binder provided by this invention)

[0179] 1. Preparation of raw diamond mixed particle size: Raw diamond materials with particle sizes of 35 / 40 mesh, 60 / 70 mesh and 140 / 170 mesh are added to the mixer in a mass ratio of 43%:30%:27% and thoroughly mixed.

[0180] 2. Mix 16% polyvinylpyrrolidone, 5% BTA, 1% PG, 3% xanthan gum, 2% methylcellulose, 6% polyamide wax and 0.5% polydimethylsiloxane with 66.5% glycerol to form a binder.

[0181] 3. Mix silver, copper, titanium and chromium with a particle size of 500 mesh at a ratio of 72%, 25%, 2% and 1% respectively to prepare a self-fluxing metal solder. Then, place the mixture and the self-fluxing diamond solder at a ratio of 12%:88% in a mixer and mix them at 140°C for 30 minutes.

[0182] 4. Weigh the raw diamond material with mixed particle size and the solder matrix at a mass ratio of 36%:64%, and then mix them in a mixer for 30 minutes.

[0183] 5. Pour the mixed material from step 4 into a graphite mold, vibrate to compact it, and then bake it at 140℃ for 1.5 hours. After baking, it becomes a preform.

[0184] 6. The baked preform is placed in a vacuum welding furnace for welding and sintering. The welding and sintering process is divided into a first heating and holding stage, a second heating and holding stage, a third heating and holding stage, and a fourth cooling stage. The specific implementation parameters are as follows:

[0185] In the first heating and holding stage, under vacuum conditions, the temperature is raised to 560℃ at a heating rate of 7℃ / min and held for 15min.

[0186] In the second heating and holding stage, under vacuum conditions, the temperature is raised to 780℃ at a heating rate of 9℃ / min and held for 20min.

[0187] In the third heating and holding stage, under vacuum conditions, the temperature is raised to 880℃ at a heating rate of 9℃ / min and held for 4 minutes.

[0188] In the fourth cooling stage, the temperature is cooled to room temperature at a rate of 4℃ / min under vacuum.

[0189] After the above welding and sintering process, the material is taken out, demolded and trimmed to obtain a self-fluxing diamond copper heat sink heat conduction sheet. The heat conduction sheet produced in this embodiment has a thermal conductivity of 611 W / (m·K).

[0190] The comparison shows that the thermal conductivity of the prepared heat-conducting sheet is significantly reduced after the composition of the binder is changed.

[0191] Comparative Example 6

[0192] (Using a multi-grain size diamond mixed raw material, without the welding and sintering process described in this invention, compared with Example 1)

[0193] 1. Preparation of raw diamond mixed particle size: Raw diamond materials with particle sizes of 35 / 40 mesh, 60 / 70 mesh and 140 / 170 mesh are added to the mixer in a mass ratio of 43%:30%:27% and thoroughly mixed.

[0194] 2. Mix 16% polyvinylpyrrolidone, 5% BTA, 1% PG, 3% xanthan gum, 2% methylcellulose, 6% polyamide wax and 0.5% polydimethylsiloxane with 66.5% glycerol to form a binder.

[0195] 3. Preparation of solder matrix: Mix 500-mesh silver, copper, titanium and chromium in proportions of 72%, 25%, 2% and 1% respectively to prepare a self-fluxing metal solder. Then, place the binder and the self-fluxing diamond solder in a mixer in proportion of 12%:88% and mix and stir at 140℃ for 30 minutes.

[0196] 4. Weigh the raw diamond material with mixed particle size and the solder matrix at a mass ratio of 36%:64%, and then mix them in a mixer for 30 minutes.

[0197] 5. Pour the mixed material from step 4 into a graphite mold, vibrate to compact it, and then bake it at 140℃ for 1.5 hours. After baking, it becomes a preform.

[0198] 6. The baked preform is placed in a vacuum welding furnace for welding and sintering. The welding and sintering process consists of a first heating stage, a second holding stage, and a third cooling stage. The specific implementation parameters are as follows:

[0199] In the first heating and holding stage, the temperature is raised to 880℃ under vacuum conditions at a heating rate of 9℃ / min.

[0200] The second heat preservation stage involves maintaining the temperature at 880℃ for 25 minutes under vacuum conditions.

[0201] In the third cooling stage, the temperature is cooled to room temperature at a rate of 4℃ / min under vacuum.

[0202] After the above welding and sintering process, the material is removed, demolded, and trimmed to obtain a diamond copper heat-conducting sheet, such as... Figure 8 As shown, the thermal conductivity of the heat-conducting sheet fabricated in this comparative example reaches 705 W / (m·K).

[0203] The welding and sintering process provided by this invention is adapted to the composition of the solder matrix raw materials of this invention. When the welding and sintering process is changed, it also has a certain impact on the thermal conductivity.

Claims

1. A solder matrix, characterized in that, The raw material composition is 85 93wt% solder and 7 15 wt% binder; the binder composition is 15 40wt% polyvinylpyrrolidone, 0.5 7wt% BTA, 0 5wt% PG, 1 8wt% xanthan gum, 1 10 wt% methylcellulose, 0.5 12 wt% polyamide wax and 0.1 1 wt% polydimethylsiloxane, the remainder being glycerol; the solder composition is 60. 75wt% silver, 20 34wt% copper, 1 6 wt% titanium and 0.5 1 wt% chromium.

2. The solder matrix according to claim 1, characterized in that, The solder particle size is 300 mesh. 700 mesh.

3. A method for preparing a self-fusing diamond copper heat sink thermal conductive sheet, characterized in that, Includes the following steps: 1) Prepare diamond raw materials; 2) Prepare a binder as described in claim 1, and mix the raw materials by stirring. 3) Prepare the solder matrix, which is obtained by mixing and heating the raw materials as described in claim 1; 4) Raw material pretreatment: The diamond raw material and solder matrix are stirred and mixed, and then poured into a graphite mold for vibration, heating and drying to form a preform. 5) Welding and sintering treatment: The preform is placed in a vacuum welding furnace for high-temperature welding and sintering treatment to produce diamond copper heat sink heat conduction sheet.

4. The method for preparing the self-fusing diamond copper heat sink thermal conductive sheet according to claim 3, characterized in that: In step 1), the composition of the diamond rough is rough rough material 35 55wt%, intermediate raw material 15 40wt% and fine raw material 10 35wt%, raw material selected from 16 / 18 Within the 35 / 40 particle size range, intermediate raw materials are selected from 40 / 45. Within the 60 / 70 particle size range, fine raw materials are selected from 70 / 80. Within the particle size range of 140 / 170.

5. The method for preparing the self-fusing diamond copper heat sink thermal conductive sheet according to claim 3, characterized in that: In step 4), 30 45wt% diamond raw material and 55 70wt% of solder matrix is ​​stirred and mixed.

6. The method for preparing the self-fusing diamond copper heat sink thermal conductive sheet according to claim 3, characterized in that: Step 5) includes the following steps in the welding and sintering process: 51) During the first heating and holding stage, under vacuum conditions, the temperature is increased at a rate of 5℃ / min. A heating rate of 10℃ / min will raise the temperature to 520℃. 570℃ and hold for 15 minutes 30 minutes; 52) During the second heating and holding stage, under vacuum conditions, the temperature is increased at a rate of 7℃ / min. A heating rate of 12℃ / min will raise the temperature to 750℃. 790℃ and hold for 15 minutes 30 minutes; 53) In the third heating and holding stage, under vacuum conditions, the temperature is increased at a rate of 7℃ / min. The temperature was raised to 850℃ at a heating rate of 12℃ / min. 890℃ and hold for 3 minutes 10 min; 54) In the fourth cooling stage, under vacuum conditions, the temperature is increased at a rate of 2℃ / min. The temperature is cooled to room temperature at a cooling rate of 7℃ / min.

7. The method for preparing the self-fusing diamond copper heat sink thermal conductive sheet according to claim 3, characterized in that: The heating temperature in step 3) is 120℃. 150℃; the heating temperature in step 4) is 130℃. 160℃.

8. As claimed in claim 3 The self-fusing diamond copper heat sink heat conductor prepared by the preparation method of any one of the seven claims.

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