Diamond copper uniform temperature plate material and preparation method thereof

Abstract

This invention provides a diamond-copper heat spreader material and its preparation method, belonging to the technical field of heat spreader technology. The copper-chromium solid solution powder prepared in this application facilitates the migration of chromium to the interface and grain boundaries during sintering, promoting the formation of a fine chromium-rich reaction layer and precipitated phase. Through cleaning, sensitization, activation, and electroless copper plating, a continuous copper layer is constructed on the silicon carbide surface, improving its wettability with the copper substrate. A multi-scale structure is constructed by combining diamond, copper-coated silicon carbide, and copper-chromium solid solution powder to construct a hard, highly thermally conductive framework, medium-sized buffer fillers, and a continuous metal substrate. Densification, interface strengthening, and substrate thermal purification are achieved through spark plasma sintering and heat preservation treatment. In the final diamond-copper heat spreader, diamond provides the dominant thermal pathway, while the copper-coated silicon carbide serves both as interstitial filling and thermal expansion buffer. The copper-chromium solid solution powder and the chromium-rich interface layer jointly enhance interfacial bonding and dimensional stability during thermal cycling.

Description

Technical Field

[0001] This invention belongs to the field of heat exchanger technology, and relates to a diamond copper heat exchanger material and its preparation method. Background Technology

[0002] With the widespread application of third-generation semiconductors in high-power electronic devices, new energy vehicles, and 5G communication base stations, the heat flux density of chips is increasing. Traditional metal heat dissipation materials such as copper and aluminum, due to their high coefficients of thermal expansion and limited thermal conductivity, are gradually failing to meet the stringent requirements of high-power-density devices for heat dissipation efficiency and thermomechanical stability. Diamond / copper composite materials combine the high thermal conductivity and low coefficient of thermal expansion of diamond with the excellent thermal and electrical conductivity of copper, and are considered an ideal choice for next-generation high-performance thermal management materials. However, in practical preparation and application, existing diamond / copper composite material technologies still face technical bottlenecks.

[0003] Diamond does not wet copper, and current technologies often add highly reactive elements such as titanium to improve this. However, titanium is too reactive and easily forms a thick and brittle carbide layer, increasing interfacial thermal resistance. At the same time, after high-temperature sintering, the reactive elements easily dissolve in the copper lattice, producing a strong electron scattering effect, which leads to a decrease in the intrinsic thermal conductivity of the copper matrix.

[0004] The significant difference in thermal expansion coefficients between diamond and copper leads to shear stress at the interface during sintering cooling or service thermal cycling, causing microcracks or bonding failure. Existing nanomaterial buffering methods suffer from difficulties in dispersion and high preparation costs, hindering industrial application.

[0005] When using large-particle diamonds of a single size for preparation, the gaps between the particles are relatively large. If the gaps are completely filled with metallic copper, it will limit the increase of the overall diamond volume fraction. If the filling is insufficient, it will easily form pore defects, affecting the density and thermal conductivity of the heat spreader. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a diamond-copper heat spreader material and its preparation method. The copper-chromium solid solution powder prepared in this application facilitates the migration of chromium to the interface and grain boundaries during sintering, promoting the formation of a relatively finely distributed chromium-rich reaction layer and precipitated phase. Through cleaning, sensitization, activation, and electroless copper plating, a continuous copper layer is constructed on the silicon carbide surface, improving its wettability with the copper substrate. A multi-scale structure is constructed by combining diamond, copper-coated silicon carbide, and copper-chromium solid solution powder to construct a hard, highly thermally conductive framework, medium-sized buffer fillers, and a continuous metal substrate. Combined with two-stage spark plasma sintering and a heat treatment at 350-500℃, densification, interface strengthening, and thermal purification of the substrate are achieved. In the final diamond-copper heat spreader, diamond provides the dominant thermal pathway, while the copper-coated silicon carbide serves both as interstitial filling and thermal expansion buffer. The copper-chromium solid solution powder and the chromium-rich interface layer jointly enhance interfacial bonding and dimensional stability during thermal cycling.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a diamond copper heat spreader material, the method comprising:

[0009] S1: Mix copper powder and chromium powder to obtain a mixed powder, add ethanol, ball mill in an argon atmosphere using a high-energy ball mill, dry, and sieve to obtain copper-chromium solid solution powder;

[0010] S2: Place silicon carbide micro powder in ethanol for ultrasonic cleaning, filter, and dry to obtain cleaned silicon carbide; disperse the cleaned silicon carbide in a sensitizing solution, stir at room temperature, filter, and wash to obtain sensitized silicon carbide; disperse the sensitized silicon carbide in an activation solution, stir at room temperature, filter, and wash with water to obtain activated silicon carbide; disperse the activated silicon carbide in a copper plating solution to obtain a suspension, adjust the pH with sodium hydroxide solution to obtain reaction solution A, stir the reaction, filter, wash, and dry to obtain copper-coated silicon carbide micro powder.

[0011] S3: Diamond, copper-coated silicon carbide micro powder and copper-chromium solid solution powder are mixed to obtain a mixture. Ethanol is added and mixed to obtain a second mixture. After drying, the mixture is sieved to obtain a third mixture. A layer of copper foil is laid at the bottom of the mold. The third mixture is loaded into the mold and cold pre-pressed. Then, a layer of copper foil of the same specification is covered on top to obtain a preform.

[0012] S4: The preform is placed in a spark plasma sintering furnace for vacuum sintering: the temperature is raised to the first temperature at the first heating rate and held at the first temperature, while axial pressure is applied. Then the temperature is raised to the second temperature at the second heating rate and held at the second temperature. After sintering, the axial pressure is unloaded and the sintering current is cut off. The material is cooled to the third temperature in an inert atmosphere and held at the third temperature. After natural cooling, the material is demolded to obtain the diamond copper isothermal plate material.

[0013] As a preferred technical solution of the present invention, in step S1, the particle size of the chromium powder is 1-10 μm, for example, it can be 1.0 μm, 1.9 μm, 2.8 μm, 3.7 μm, 4.6 μm, 5.5 μm, 6.4 μm, 7.3 μm, 8.2 μm, 9.1 μm or 10.0 μm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0014] In some optional embodiments, the mass ratio of copper powder to chromium powder is (97-99):(3-1), for example, it can be (97.0, 97.2, 97.4, 97.6, 97.8, 98.0, 98.2, 98.4, 98.6, 98.8 or 99.0):(3.0, 2.8, 2.6, 2.4, 2.2, 2.0, 1.8, 1.6, 1.4, 1.2 or 1.0), but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0015] In some optional embodiments, the amount of ethanol fed is 1-2% of the mass of the mixed powder, for example, it can be 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9% or 2.0%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0016] In some optional embodiments, the ball-to-material ratio is (10-20):1, for example, it can be 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1 or 20:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0017] In some alternative embodiments, the rotational speed of the ball mill is 300-400 rpm, for example, 300 rpm, 310 rpm, 320 rpm, 330 rpm, 340 rpm, 350 rpm, 360 rpm, 370 rpm, 380 rpm, 390 rpm or 400 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0018] In some alternative embodiments, the ball milling time is 10-20 hours, for example, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours or 20 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0019] As a preferred technical solution of the present invention, in step S2, the particle size of the silicon carbide micro powder is 5-10 μm, for example, it can be 5.0 μm, 5.5 μm, 6.0 μm, 6.5 μm, 7.0 μm, 7.5 μm, 8.0 μm, 8.5 μm, 9.0 μm, 9.5 μm or 10.0 μm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] In some optional embodiments, the time for ultrasonic cleaning of the silicon carbide micro powder in ethanol is 10-20 min, for example, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min or 20 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0021] In some optional embodiments, the time for stirring the cleaned silicon carbide dispersed in the sensitizing solution at room temperature is 10-20 min, for example, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min or 20 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0022] In some optional embodiments, the concentration of stannous chloride in the sensitizing solution is 10-20 g / L, for example, it can be 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L, 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L or 20 g / L, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0023] In some optional embodiments, the concentration of hydrochloric acid in the sensitizing solution is 20-40 mL / L, for example, it can be 20 mL / L, 22 mL / L, 24 mL / L, 26 mL / L, 28 mL / L, 30 mL / L, 32 mL / L, 34 mL / L, 36 mL / L, 38 mL / L or 40 mL / L, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0024] In some optional embodiments, the mass-to-volume ratio of the cleaned silicon carbide to the sensitizing solution is 1g:(20-50)mL, for example, it can be 1g:20mL, 1g:23mL, 1g:26mL, 1g:29mL, 1g:32mL, 1g:35mL, 1g:38mL, 1g:41mL, 1g:44mL, 1g:47mL or 1g:50mL, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0025] In some optional embodiments, the sensitized silicon carbide is dispersed in the activation solution and stirred at room temperature for 10-20 min, for example, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min or 20 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0026] In some optional embodiments, the concentration of palladium chloride in the activation solution is 0.3-0.5 g / L, for example, it can be 0.30 g / L, 0.32 g / L, 0.34 g / L, 0.36 g / L, 0.38 g / L, 0.40 g / L, 0.42 g / L, 0.44 g / L, 0.46 g / L, 0.48 g / L or 0.50 g / L, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0027] In some optional embodiments, the concentration of hydrochloric acid in the activation solution is 5-10 mL / L, for example, it can be 5.0 mL / L, 5.5 mL / L, 6.0 mL / L, 6.5 mL / L, 7.0 mL / L, 7.5 mL / L, 8.0 mL / L, 8.5 mL / L, 9.0 mL / L, 9.5 mL / L or 10.0 mL / L, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0028] In some optional embodiments, the mass-to-volume ratio of the sensitized silicon carbide to the activation solution is 1 g:(20-50) mL, for example, it can be 1 g:20 mL, 1 g:23 mL, 1 g:26 mL, 1 g:29 mL, 1 g:32 mL, 1 g:35 mL, 1 g:38 mL, 1 g:41 mL, 1 g:44 mL, 1 g:47 mL or 1 g:50 mL, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0029] In some optional embodiments, the mass-to-volume ratio of the activated silicon carbide to the copper plating solution is (5-15) g:1000 mL, for example, it can be 5 g:1000 mL, 6 g:1000 mL, 7 g:1000 mL, 8 g:1000 mL, 9 g:1000 mL, 10 g:1000 mL, 11 g:1000 mL, 12 g:1000 mL, 13 g:1000 mL, 14 g:1000 mL or 15 g:1000 mL, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0030] In some optional embodiments, the molar ratio of copper sulfate to ethylenediaminetetraacetic acid in the copper plating solution is 1:(2-4), for example, it can be 1:2.0, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3.0, 1:3.2, 1:3.4, 1:3.6, 1:3.8 or 1:4.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0031] In some optional embodiments, the molar ratio of copper sulfate to sodium phosphite in the copper plating solution is 1:(1.5-3), for example, it can be 1:1.50, 1:1.65, 1:1.80, 1:1.95, 1:2.10, 1:2.25, 1:2.40, 1:2.55, 1:2.70, 1:2.85 or 1:3.00, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0032] In some optional embodiments, the concentration of copper sulfate in the copper plating solution is 10-20 g / L, for example, it can be 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L, 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L or 20 g / L, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0033] In some optional embodiments, the sodium hydroxide solution has a mass fraction of 20-40 wt.%, for example, it may be 20 wt.%, 22 wt.%, 24 wt.%, 26 wt.%, 28 wt.%, 30 wt.%, 32 wt.%, 34 wt.%, 36 wt.%, 38 wt.%, or 40 wt.%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0034] In some alternative embodiments, the suspension is adjusted to a pH of 11-13 using a sodium hydroxide solution, for example, to 11.0, 11.2, 11.4, 11.6, 11.8, 12.0, 12.2, 12.4, 12.6, 12.8, or 13.0, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0035] In some optional embodiments, the temperature of the reaction mixture A during stirring is 40-60°C, for example, it can be 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C or 60°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0036] In some optional embodiments, the reaction time of the reaction solution A is 30-60 min, for example, it can be 30 min, 33 min, 36 min, 39 min, 42 min, 45 min, 48 min, 51 min, 54 min, 57 min or 60 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] As a preferred technical solution of the present invention, in step S3, the particle size of the diamond is 50-200μm, for example, it can be 50μm, 70μm, 90μm, 110μm, 130μm, 150μm, 170μm, 190μm or 200μm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] In some optional embodiments, the volume percentage of the diamond, copper-coated silicon carbide micropowder, and copper-chromium solid solution powder is (50-55):(5-12):(35-45), for example, (50.0, 50.5, 51.0, 51.5, 52.0, 52.5, 53.0, 53.5, 54.0, 54.5, or 55.0):(5.0, 5.7, 6.4, 7.1, 7.8, 8.5, 9.2, 9.9, 10.6, 11.3, or 12.0):(35, 36, 37, 38, 39, 40, 41, 42, 43, 44, or 45), but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0039] In some optional embodiments, the amount of ethanol added is 2-5% of the mass of the mixture, for example, it can be 2.0%, 2.3%, 2.6%, 2.9%, 3.2%, 3.5%, 3.8%, 4.1%, 4.4%, 4.7% or 5.0%, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0040] In some alternative embodiments, the drying temperature of the second mixture is 60-80°C, for example, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0041] In some alternative embodiments, the drying time of the second mixture is 1-3 hours, for example, 1.0 hours, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2.0 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3.0 hours, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0042] In some optional embodiments, the thickness of the copper foil is 0.05-0.3 mm, for example, it can be 0.050 mm, 0.065 mm, 0.080 mm, 0.095 mm, 0.110 mm, 0.125 mm, 0.140 mm, 0.155 mm, 0.170 mm, 0.185 mm, 0.200 mm, 0.22 mm, 0.24 mm, 0.26 mm, 0.28 mm or 0.3 mm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0043] In some optional embodiments, the cold pre-compression pressure is 5-10 MPa, for example, it can be 5.0 MPa, 5.5 MPa, 6.0 MPa, 6.5 MPa, 7.0 MPa, 7.5 MPa, 8.0 MPa, 8.5 MPa, 9.0 MPa, 9.5 MPa or 10.0 MPa, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0044] In some optional embodiments, the third mixture is packed at a rate of 0.8-1.5 g / cm³. 2 For example, it could be 0.80 g / cm³ 2 0.87g / cm 2 0.94g / cm 2 1.01 g / cm 2 1.08g / cm 2 1.15g / cm 21.22g / cm 2 1.29g / cm 2 1.36 g / cm 2 1.43 g / cm 2 Or 1.50g / cm 2 However, this does not apply to all values ​​listed; other unlisted values ​​within the same range also apply.

[0045] As a preferred technical solution of the present invention, in step S4, the first heating rate is 80-100℃ / min, for example, it can be 80℃ / min, 82℃ / min, 84℃ / min, 86℃ / min, 88℃ / min, 90℃ / min, 92℃ / min, 94℃ / min, 96℃ / min, 98℃ / min or 100℃ / min, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0046] In some alternative embodiments, the first temperature is 500-700°C, for example, it can be 500°C, 520°C, 540°C, 560°C, 580°C, 600°C, 620°C, 640°C, 660°C, 680°C or 700°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0047] In some optional embodiments, the holding time at the first temperature is 3-10 min, for example, it can be 3.0 min, 4.0 min, 5.0 min, 6.0 min, 7.0 min, 8.0 min, 9.0 min or 10.0 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0048] In some alternative embodiments, the applied axial pressure is 40-60 MPa, for example, it can be 40 MPa, 42 MPa, 44 MPa, 46 MPa, 48 MPa, 50 MPa, 52 MPa, 54 MPa, 56 MPa, 58 MPa or 60 MPa, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0049] In some optional embodiments, the second heating rate is 50-80℃ / min, for example, it can be 50℃ / min, 53℃ / min, 56℃ / min, 59℃ / min, 62℃ / min, 65℃ / min, 68℃ / min, 71℃ / min, 74℃ / min, 77℃ / min or 80℃ / min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0050] In some alternative embodiments, the second temperature is 800-1000°C, for example, it can be 800°C, 820°C, 840°C, 860°C, 880°C, 900°C, 920°C, 940°C, 960°C, 980°C or 1000°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0051] In some optional embodiments, the holding time at the second temperature is 5-20 min, for example, it can be 5.0 min, 6.0 min, 7.0 min, 8.0 min, 9.0 min, 10.0 min, 11.0 min, 12.0 min, 13.0 min, 14.0 min, 15.0 min, 16.0 min, 17.0 min, 18.0 min, 19.0 min or 20.0 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0052] In some alternative embodiments, the third temperature is 350-500°C, for example, it can be 350°C, 370°C, 390°C, 410°C, 430°C, 450°C, 470°C, 490°C or 500°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0053] In some optional embodiments, the holding time at the third temperature is 30-60 min, for example, it can be 30 min, 33 min, 36 min, 39 min, 42 min, 45 min, 48 min, 51 min, 54 min, 57 min or 60 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0054] Secondly, the present invention provides a diamond copper heat spreader material.

[0055] This application describes a prolonged high-energy ball milling process involving copper powder and a small amount of chromium powder under an inert atmosphere. This process transforms the mixture from a simple mechanical mixture into a copper-chromium solid solution. During the prolonged milling, the copper powder undergoes repeated cold welding, crushing, and re-welding. The harder chromium particles are forced into the interior of the copper particles under impact and shearing, and some chromium atoms diffuse into the copper lattice, thus increasing the degree of solid solution. Compared to directly adding chromium powder, this pre-formed copper-chromium solid solution powder facilitates the relatively uniform migration of chromium from the matrix to the interface and grain boundaries during subsequent spark plasma sintering, reducing the probability of localized coarse carbides or chromium-rich agglomerations. This results in a finely distributed interfacial reaction layer and precipitated phases.

[0056] This application utilizes wet processing methods such as cleaning, sensitization, activation, and electroless copper plating to construct a relatively continuous copper coating layer on the surface of silicon carbide particles. Ethanol ultrasonic cleaning removes physical contaminants and weakly bound impurities from the silicon carbide surface, facilitating subsequent Sn plating. 2+ and Pd 2+ The adsorption provides a relatively clean surface. Stannous chloride in the sensitizing solution can deposit Sn(II) species on the silicon carbide surface under acidic conditions, providing a reducing environment for subsequent palladium deposition; palladium chloride in the activation solution is reduced by Sn(II) species and forms dispersed palladium nanoparticle active centers. Introducing the activated silicon carbide particles into a copper plating solution containing copper sulfate, ethylenediaminetetraacetic acid, and sodium phosphite allows the palladium active sites to catalyze Cu deposition. 2+ Reduction deposition occurs on the particle surface, allowing copper to gradually form a continuous coating on the silicon carbide surface. Ethylenediaminetetraacetic acid (EDTA) is used to control the Cu content. 2+ In terms of concentration and release rate, sodium phosphite provides moderate reducing power, and alkaline conditions help maintain a relatively stable deposition rate. The copper layer helps improve the wettability and contact interface between silicon carbide and the copper substrate.

[0057] This application combines diamond, copper-coated silicon carbide microparticles, and copper-chromium solid solution powder to construct a multi-scale structure comprising a hard, highly thermally conductive framework, medium-sized buffer filler particles, and a continuous metallic matrix. Diamond forms relatively interconnected, highly thermally conductive pathways within the overall structure. The copper-coated silicon carbide microparticles, distributed between the diamond particles, increase packing density by filling the gaps between larger particles with smaller particle sizes, reducing the appearance of large pure metal areas or pores. Furthermore, silicon carbide's coefficient of thermal expansion, between that of diamond and copper, provides a certain degree of stress buffering at the microscopic level. The copper-chromium solid solution powder is further filled, forming a continuous metallic network after sintering, providing a thermal background for heat flow and serving as a source of chromium for interfacial microstructure regulation. Using a small amount of ethanol to assist mixing improves powder dispersibility, while subsequent drying and sieving operations help eliminate agglomeration caused by wet mixing. Free-flowing particles are easily and uniformly packed in the mold, thus providing a more uniform initial structure for subsequent dense sintering. The laying of upper and lower copper foils not only facilitates the formation of a copper-clad layer on the surface during the spark plasma sintering process, but also helps to improve the surface flatness.

[0058] In the spark plasma sintering process, the first stage involves rapid heating to 500-700℃ and a short holding time. Before the copper reaches its melting point, the axial pressure increases the contact area between particles. The pulsed current of the spark plasma sintering generates localized resistive heating and a discharge effect at the particle contact points, which helps to break down the surface oxide film and promote the formation of sintering necks, thus achieving initial densification. In the second stage, the temperature is further increased to 800-1000℃ and held for 5-20 minutes. During this stage, the copper matrix is ​​in a highly diffusive state. Chromium atoms in the copper-chromium solid solution powder tend to migrate and accumulate towards grain boundaries, the diamond / copper interface, and the silicon carbide / copper interface under thermodynamic drive. Near the diamond, chromium atoms may contact carbon to form a thin chromium-rich carbide layer or a chromium-rich reaction layer. Around silicon carbide, chromium atoms may also undergo certain interfacial reactions with the matrix and particle surfaces. These chromium-rich interfacial layers are expected to improve the bonding between hard particles and the copper matrix, reduce the proportion of purely mechanical contact interfaces, and thus, to some extent, improve interfacial shear strength and reduce interfacial thermal resistance.

[0059] After sintering, the pressure is unloaded in an inert atmosphere, the discharge current is cut off, and the furnace is cooled to 350-500℃ and held for 30-60 minutes. Within this temperature range, the equilibrium solid solubility of chromium in copper is low. Chromium atoms remaining in the copper lattice will further migrate towards the grain boundaries and existing precipitates, existing as fine precipitates or interface-enriched layers, thus reducing the solid-solid chromium content within the copper lattice. This process helps to reduce the scattering effect of solid-solid chromium on electron migration, preserving to some extent the high thermal conductivity of the copper matrix, while retaining an appropriate amount of chromium-rich precipitates near the interface, enhancing the stability of the interface and grain boundaries. In the diamond-copper vapor chamber obtained by natural cooling, diamond forms the dominant thermal framework, while the copper-coated silicon carbide micropowder on the surface fills the gaps and buffers thermal expansion. The copper-chromium solid solution powder provides a continuous metal thermal conduction channel, and the interface region forms a certain degree of chromium-rich reaction layer and precipitated phase network with the migration and precipitation of chromium. This multi-scale structural synergy helps to achieve good interfacial bonding strength and dimensional stability during thermal cycling while maintaining high thermal conductivity.

[0060] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0061] This application pre-prepares copper-chromium solid solution powder through high-energy ball milling, enabling chromium to migrate uniformly to the interface and grain boundaries during subsequent sintering, avoiding coarse agglomeration, and facilitating the formation of a fine and uniform interface reaction layer and precipitated phase.

[0062] This application achieves a continuous copper coating layer on the surface of silicon carbide particles through cleaning, sensitization, activation, and electroless copper plating; and utilizes a tin / palladium activation system to catalyze Cu... 2+A uniform coating is obtained by reduction deposition on the silicon carbide surface under ethylenediaminetetraacetic acid, sodium phosphite and alkaline conditions, thereby improving the wettability and interfacial contact quality between silicon carbide and copper substrate.

[0063] This application constructs a multi-scale structure by compounding diamond, copper-coated silicon carbide and copper-chromium solid solution powders, which includes a hard, high thermal conductivity framework, medium-sized buffer filler particles and a continuous metal matrix, thereby achieving interconnected thermal conduction pathways, buffering of thermal expansion stress and controllable interfaces. Through wet mixing with ethanol, drying and sieving, and filling with upper and lower copper foils, a uniformly dispersed and smooth initial blank is provided for subsequent dense sintering.

[0064] During the spark plasma sintering process, in the 500-700℃ stage, pressure and partial discharge heating are used to break the surface oxide film and promote the formation of sintering necks, achieving preliminary densification. In the 800-1000℃ stage, chromium in the copper-chromium solid solution is promoted to migrate to the grain boundaries and diamond / copper and silicon carbide / copper interfaces, forming a chromium-rich interface layer, which enhances the bonding and reduces the interface thermal resistance. Subsequently, in the 350-500℃ stage, the residual solid solution chromium is refined and precipitated, taking into account both the thermal conductivity of the copper matrix and the stability of the interface and grain boundaries.

[0065] In the diamond-copper vapor chamber prepared in this application, diamond forms the dominant thermal framework, while the copper-coated silicon carbide micropowder on the surface fills the gaps and buffers thermal expansion. The copper-chromium solid solution powder provides a continuous metal thermal conduction channel, and the interface region forms a certain degree of chromium-rich reaction layer and precipitated phase network with the migration and precipitation of chromium. This multi-scale structural synergy helps to obtain good interfacial bonding strength and dimensional stability during thermal cycling while maintaining high thermal conductivity. The prepared vapor chamber can be used in heat exchange devices. Attached Figure Description

[0066] Figure 1 This is a physical image of the diamond copper heat spreader material prepared in Example 1 of this application. Detailed Implementation

[0067] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that employ any obvious substitutions and modifications made to the embodiments described herein.

[0068] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing.

[0069] Example 1

[0070] This embodiment provides a diamond copper heat spreader material and its preparation method. The preparation method of the diamond copper heat spreader material specifically includes the following steps:

[0071] S1: Copper powder and chromium powder with a particle size of 8μm are mixed at a mass ratio of 98:2 to obtain a mixed powder. Ethanol is added at a mass of 1.8% of the mixed powder. The mixture is then ball-milled for 18 hours at a ball-to-powder ratio of 18:1 and a speed of 380 rpm under an argon atmosphere using a high-energy ball mill. The mixture is then dried and sieved to obtain copper-chromium solid solution powder.

[0072] S2: Silicon carbide micropowder with a particle size of 8 μm was ultrasonically cleaned in ethanol for 18 min, filtered, and dried to obtain cleaned silicon carbide. The cleaned silicon carbide was dispersed in a sensitizing solution and stirred at room temperature for 15 min. The sensitizing solution contained 18 g / L stannous chloride and 35 mL / L hydrochloric acid, with a mass-to-volume ratio of 1 g:45 mL for silicon carbide. After filtration and washing, sensitized silicon carbide was obtained. The sensitized silicon carbide was dispersed in an activation solution and stirred at room temperature for 17 min. The activation solution contained 0.45 g / L palladium chloride and 8 mL / L hydrochloric acid, with a mass-to-volume ratio of 1 g:45 mL for silicon carbide. The volume ratio was 1g:40mL. After filtration and washing with water, activated silicon carbide was obtained. The activated silicon carbide was dispersed in a copper plating solution to obtain a suspension. The mass-volume ratio of activated silicon carbide to copper plating solution was 12g:1000mL. The molar ratio of copper sulfate to ethylenediaminetetraacetic acid in the copper plating solution was 1:3.5, the molar ratio of copper sulfate to sodium phosphite was 1:2.5, and the concentration of copper sulfate in the copper plating solution was 18g / L. The pH value was adjusted to 12.5 using a 35wt.% sodium hydroxide solution to obtain reaction solution A. The reaction was stirred at 55℃ for 50min. After filtration, washing, and drying, silicon carbide micro powder with copper coating on the surface was obtained.

[0073] S3: Diamond with a particle size of 130μm, copper-coated silicon carbide micro powder, and copper-chromium solid solution powder are mixed at a volume percentage of 52:8:40 to obtain a mixture. Ethanol is added at a mass of 4% of the mixture to obtain a second mixture. After drying at 75℃ for 2.5h, the mixture is sieved to obtain a third mixture. A copper foil with a thickness of 0.15mm is laid at the bottom of the mold. The third mixture is then loaded into the mold and subjected to cold pre-pressing at 8MPa. The loading amount of the third mixture is 1.2g / cm2. Finally, a copper foil of the same specification is covered on top to obtain a preform.

[0074] S4: The preform is placed in a spark plasma sintering furnace for vacuum sintering: the temperature is raised to the first temperature of 615°C at a first heating rate of 95°C / min and held for 4 min, while an axial pressure of 55 MPa is applied. Then the temperature is raised to the second temperature of 915°C at a second heating rate of 70°C / min and held for 11 min. After sintering, the axial pressure is unloaded and the sintering current is cut off. The preform is cooled in the furnace under an inert atmosphere to the third temperature of 480°C and held for 50 min. After natural cooling, the preform is demolded to obtain the diamond copper heat exchange plate material. Figure 1 Here is a picture of a diamond copper heat spreader material, such as... Figure 1 As shown, the heat spreader has a regular plate-like structure with a complete shape, a continuous and flat surface, and no obvious warping, peeling, or macroscopic cracks. The plate surface forms a uniform and dense matrix appearance, with clear outlines on the upper and lower surfaces and smooth edge transitions.

[0075] Example 2

[0076] This embodiment provides a diamond copper heat spreader material and its preparation method. The preparation method of the diamond copper heat spreader material specifically includes the following steps:

[0077] S1: Copper powder and chromium powder with a particle size of 1μm are mixed at a mass ratio of 99:1 to obtain a mixed powder. Ethanol is added at a feed amount of 1% of the mass of the mixed powder. The mixture is ball-milled for 10 hours at a ball-to-powder ratio of 10:1 and a speed of 300 rpm under an argon atmosphere using a high-energy ball mill. The mixture is then dried and sieved to obtain copper-chromium solid solution powder.

[0078] S2: Silicon carbide micropowder with a particle size of 5 μm was ultrasonically cleaned in ethanol for 10 min, filtered, and dried to obtain cleaned silicon carbide. The cleaned silicon carbide was dispersed in a sensitizing solution and stirred at room temperature for 20 min. The sensitizing solution contained 10 g / L stannous chloride and 20 mL / L hydrochloric acid, with a mass-to-volume ratio of 1 g:20 mL for silicon carbide. After filtration and washing, sensitized silicon carbide was obtained. The sensitized silicon carbide was dispersed in an activation solution and stirred at room temperature for 10 min. The activation solution contained 0.3 g / L palladium chloride and 5 mL / L hydrochloric acid, with a mass-to-volume ratio of 1 g:20 mL for silicon carbide. The activated silicon carbide was obtained by filtering and washing with water at a mass-to-volume ratio of 1g:20mL. The activated silicon carbide was dispersed in a copper plating solution to obtain a suspension, wherein the mass-to-volume ratio of activated silicon carbide to copper plating solution was 5g:1000mL, the molar ratio of copper sulfate to ethylenediaminetetraacetic acid in the copper plating solution was 1:2, the molar ratio of copper sulfate to sodium phosphite was 1:1.5, the concentration of copper sulfate in the copper plating solution was 10g / L, and the pH value was adjusted to 11.0 with a 20wt.% sodium hydroxide solution to obtain reaction solution A. The reaction was stirred at 40℃ for 30min, filtered, washed, and dried to obtain copper-coated silicon carbide micro powder.

[0079] S3: Diamond with a particle size of 170μm, copper-coated silicon carbide micro powder, and copper-chromium solid solution powder are mixed in a volume percentage of 50:5:45 to obtain a mixture. Ethanol is added at a mass of 2% of the mixture to obtain a second mixture. After drying at 60℃ for 1 hour, the mixture is sieved to obtain a third mixture. A copper foil with a thickness of 0.05mm is laid at the bottom of the mold. The third mixture is then loaded into the mold and subjected to cold pre-pressing at 5MPa. The loading amount of the third mixture is 0.8g / cm2. Finally, a copper foil of the same specification is covered on top to obtain a preform.

[0080] S4: The preform is placed in a spark plasma sintering furnace for vacuum sintering: the temperature is raised to the first temperature of 500°C at a first heating rate of 80°C / min and held for 3 min, while an axial pressure of 40 MPa is applied. Then the temperature is raised to the second temperature of 800°C at a second heating rate of 50°C / min and held for 5 min. After sintering, the axial pressure is unloaded and the sintering current is cut off. The preform is cooled in the furnace to the third temperature of 350°C under an inert atmosphere and held for 30 min. After natural cooling, the preform is demolded to obtain the diamond copper heat exchange plate material.

[0081] Example 3

[0082] This embodiment provides a diamond copper heat spreader material and its preparation method. The preparation method of the diamond copper heat spreader material specifically includes the following steps:

[0083] S1: Copper powder and chromium powder with a particle size of 5μm are mixed at a mass ratio of 97:3 to obtain a mixed powder. Ethanol is added at a mass of 1.2% of the mixed powder. The mixture is then ball-milled for 12 hours at a ball-to-powder ratio of 12:1 and a speed of 320 rpm under an argon atmosphere using a high-energy ball mill. The mixture is then dried and sieved to obtain copper-chromium solid solution powder.

[0084] S2: Silicon carbide micropowder with a particle size of 6 μm was ultrasonically cleaned in ethanol for 12 min, filtered, and dried to obtain cleaned silicon carbide. The cleaned silicon carbide was dispersed in a sensitizing solution and stirred at room temperature for 18 min. The sensitizing solution contained 12 g / L stannous chloride and 25 mL / L hydrochloric acid, with a mass-to-volume ratio of 1 g:30 mL for silicon carbide. After filtration and washing, sensitized silicon carbide was obtained. The sensitized silicon carbide was dispersed in an activation solution and stirred at room temperature for 13 min. The activation solution contained 0.35 g / L palladium chloride and 6 mL / L hydrochloric acid, with a mass-to-volume ratio of 1 g:30 mL for silicon carbide. The activated silicon carbide was obtained by filtering and washing with water at a mass-to-volume ratio of 1g:35mL. The activated silicon carbide was dispersed in a copper plating solution to obtain a suspension, wherein the mass-to-volume ratio of activated silicon carbide to copper plating solution was 8g:1000mL, the molar ratio of copper sulfate to ethylenediaminetetraacetic acid in the copper plating solution was 1:2.5, the molar ratio of copper sulfate to sodium phosphite was 1:2, and the concentration of copper sulfate in the copper plating solution was 12g / L. The pH value was adjusted to 11.5 using a 25wt.% sodium hydroxide solution to obtain reaction solution A. The reaction was stirred at 45℃ for 40min, filtered, washed, and dried to obtain copper-coated silicon carbide micro powder.

[0085] S3: Diamond with a particle size of 200μm, copper-coated silicon carbide micro powder, and copper-chromium solid solution powder are mixed at a volume percentage of 55:12:35 to obtain a mixture. Ethanol is added at a mass of 3% of the mixture to obtain a second mixture. After drying at 65℃ for 1.5h, the mixture is sieved to obtain a third mixture. A copper foil with a thickness of 0.3mm is laid at the bottom of the mold. The third mixture is then loaded into the mold and subjected to cold pre-pressing at 6MPa. The loading amount of the third mixture is 1.0g / cm2. Finally, a copper foil of the same specification is covered on top to obtain a preform.

[0086] S4: The preform is placed in a spark plasma sintering furnace for vacuum sintering: the temperature is raised to a first temperature of 605°C at a first heating rate of 85°C / min and held for 8 min, while an axial pressure of 45 MPa is applied. Then the temperature is raised to a second temperature of 945°C at a second heating rate of 60°C / min and held for 15 min. After sintering, the axial pressure is unloaded and the sintering current is cut off. The preform is cooled in an inert atmosphere to a third temperature of 460°C and held for 40 min. After natural cooling, the preform is demolded to obtain the diamond copper heat exchange plate material.

[0087] Example 4

[0088] This embodiment provides a diamond copper heat spreader material and its preparation method. The preparation method of the diamond copper heat spreader material specifically includes the following steps:

[0089] S1: Copper powder and chromium powder with a particle size of 10μm are mixed at a mass ratio of 98.5:1.5 to obtain a mixed powder. Ethanol is added at a feed amount of 2% of the mass of the mixed powder. The mixture is then ball-milled for 20 hours at a ball-to-powder ratio of 20:1 and a speed of 400 rpm under an argon atmosphere using a high-energy ball mill. After drying, the mixture is sieved to obtain copper-chromium solid solution powder.

[0090] S2: Silicon carbide micropowder with a particle size of 10 μm was ultrasonically cleaned in ethanol for 20 min, filtered, and dried to obtain cleaned silicon carbide. The cleaned silicon carbide was dispersed in a sensitizing solution and stirred at room temperature for 10 min. The sensitizing solution contained 20 g / L stannous chloride and 40 mL / L hydrochloric acid, with a mass-to-volume ratio of 1 g:50 mL for silicon carbide. After filtration and washing, sensitized silicon carbide was obtained. The sensitized silicon carbide was dispersed in an activation solution and stirred at room temperature for 20 min. The activation solution contained 0.5 g / L palladium chloride and 10 mL / L hydrochloric acid. The mass-to-volume ratio of the sensitized silicon carbide to the activation solution was 1 g:50 mL. The activated silicon carbide was obtained by filtering and washing with water at a mass-to-volume ratio of 1g:50mL. The activated silicon carbide was dispersed in a copper plating solution to obtain a suspension, wherein the mass-to-volume ratio of activated silicon carbide to copper plating solution was 15g:1000mL, the molar ratio of copper sulfate to ethylenediaminetetraacetic acid in the copper plating solution was 1:4, the molar ratio of copper sulfate to sodium phosphite was 1:3, the concentration of copper sulfate in the copper plating solution was 20g / L, and the pH value was adjusted to 13.0 with a 40wt.% sodium hydroxide solution to obtain reaction solution A. The reaction was stirred at 60℃ for 60min, filtered, washed, and dried to obtain copper-coated silicon carbide micro powder.

[0091] S3: Diamond with a particle size of 50μm, copper-coated silicon carbide micro powder and copper-chromium solid solution powder are mixed at a volume percentage of 53:10:37 to obtain a mixture. Ethanol is added at a mass of 5% of the mixture to obtain a second mixture. After drying at 80℃ for 3 hours, the mixture is sieved to obtain a third mixture. A copper foil with a thickness of 0.2mm is laid at the bottom of the mold. The third mixture is then loaded into the mold and subjected to cold pre-pressing at 10MPa. The loading amount of the third mixture is 1.5g / cm2. Finally, a copper foil of the same specification is covered on top to obtain a preform.

[0092] S4: The preform is placed in a spark plasma sintering furnace for vacuum sintering: the temperature is raised to a first temperature of 700°C at a first heating rate of 100°C / min and held for 10 min, while an axial pressure of 60 MPa is applied. Then the temperature is raised to a second temperature of 1000°C at a second heating rate of 80°C / min and held for 20 min. After sintering, the axial pressure is unloaded and the sintering current is cut off. The preform is cooled in an inert atmosphere to a third temperature of 500°C and held for 60 min. After natural cooling, the preform is demolded to obtain the diamond copper isothermal plate material.

[0093] Comparative Example 1

[0094] This comparative example provides a diamond copper heat spreader material. The difference between this example and Example 1 is that copper powder and chromium powder are directly mixed in S1 without high-energy ball milling. Other operating steps and process parameters are exactly the same as in Example 1.

[0095] Comparative Example 2

[0096] This comparative example provides a diamond copper heat spreader material. The difference between this example and Example 1 is that pure copper powder is used instead of copper-chromium solid solution powder. Other operating steps and process parameters are exactly the same as in Example 1.

[0097] Comparative Example 3

[0098] This comparative example provides a diamond copper heat spreader material. The difference from Example 1 is that cleaned silicon carbide is used to replace the copper-coated silicon carbide micropowder on the surface. Other operating steps and process parameters are exactly the same as in Example 1.

[0099] Comparative Example 4

[0100] This comparative example provides a diamond copper heat spreader material. The difference between this example and Example 1 is that no copper-coated silicon carbide micropowder is added. All other operating steps and process parameters are exactly the same as in Example 1.

[0101] Comparative Example 5

[0102] This comparative example provides a diamond copper heat spreader material. The difference from Example 1 is that after the second temperature heat preservation is completed, the material is directly demolded after natural cooling, and the third temperature treatment process is omitted. Other operation steps and process parameters are exactly the same as in Example 1.

[0103] The performance of the diamond copper heat spreader materials of Examples 1-4 and Comparative Examples 1-5 was tested, and the specific process is as follows:

[0104] The density of the test sample was determined according to GB / T 3850-2015;

[0105] The coefficient of thermal expansion of the sample was tested according to GB / T 4339;

[0106] The flexural strength of the sample was tested according to GB / T 232;

[0107] The interfacial shear strength of the test sample was determined according to GB / T 11363.

[0108] The thermal conductivity of the sample was tested according to GB / T 22588;

[0109] Thermal shock resistance: The sample was subjected to a thermal cycling test at -40℃ to 125℃ for 100 cycles, and the presence of peeling or cracking was observed.

[0110] The test results are shown in Table 1.

[0111] Table 1: Material performance test results of diamond copper heat exchange plates in Examples 1-4 and Comparative Examples 1-5

[0112]

[0113] As shown in Table 1, the test results of Example 1 and Comparative Example 1 reveal that in S1, copper and chromium powders were directly mixed without high-energy ball milling to form a copper-chromium solid solution powder. This resulted in uneven migration and distribution of chromium during sintering, easily leading to the formation of coarse chromium-rich phases or carbide agglomerates near local grain boundaries and interfaces. These hard and brittle agglomerates weaken the continuity of the interfacial reaction layer and introduce stress concentration sources into the matrix, reducing the densification quality and interfacial bonding integrity of the material, as well as decreasing flexural strength and interfacial shear strength. Simultaneously, the interfacial thermal resistance and scattering centers increase, disrupting effective heat conduction pathways and reducing overall thermal conductivity. Under thermal cycling conditions, microcracks are more likely to form around the locally chromium-rich hard and brittle areas, leading to decreased thermal shock stability.

[0114] As shown in Table 1, the test results of Example 1 and Comparative Example 2 reveal that when pure copper powder is used to replace the copper-chromium solid solution powder, the system lacks active chromium elements that can directionally migrate to the interface during sintering and the post-sintering holding process. Consequently, it is difficult to form a continuous chromium-rich reaction layer at the diamond / copper and silicon carbide / copper interfaces. The interfaces are mainly based on physical contact and weak metallurgical bonding, resulting in decreased interfacial shear strength and overall bending load-bearing capacity. Increased interfacial thermal resistance leads to a decrease in the effective thermal conductivity of the composite system. The lack of buffering for thermal expansion mismatch makes interfacial delamination and crack propagation more likely under thermal shock conditions, resulting in a decline in thermal conductivity and mechanical properties.

[0115] As shown in Table 1, the test results of Example 1 and Comparative Example 3 reveal that replacing the copper-coated silicon carbide micropowder with cleaned silicon carbide leads to a decrease in the wettability and metallurgical bonding between silicon carbide and the copper substrate, and an increase in residual micropores and weak bonding areas at the interface. Due to the poor bonding between the interstitial particles and the matrix, the overall density after sintering decreases, as do the flexural strength and interfacial shear strength. Simultaneously, the interfacial voids and discontinuous contacts surrounding the silicon carbide increase local thermal resistance, disrupting the effective heat conduction network and reducing thermal conductivity. During thermal cycling, these weak interfacial areas easily become sites for microcrack initiation, resulting in decreased thermal shock resistance.

[0116] As shown in Table 1, the test results of Example 1 and Comparative Example 4 reveal that without the addition of copper-coated silicon carbide micropowder, and only retaining diamond and copper-chromium solid solution powder, the system degenerates from a three-phase gradient structure to a two-phase structure. The lack of small-particle-size copper-coated silicon carbide micropowder filling the diamond interstices increases the number of locally copper-rich areas. Thermal expansion transitions directly from diamond to copper-chromium solid solution powder, and the absence of an intermediate buffer layer with a higher coefficient of thermal expansion leads to an increased coefficient of thermal expansion and intensified thermal stress concentration. Although the continuous phase of the matrix metal is slightly increased, and the thermal conductivity is close to that of Example 1, stress concentration and microcrack sensitivity near the interface increase, bending strength and interfacial shear strength decrease, interfacial damage after thermal cycling intensifies, and thermal shock resistance weakens.

[0117] As shown in Table 1, the test results of Example 1 and Comparative Example 5 indicate that after the second temperature holding period, the mold was removed after direct natural cooling, omitting the third temperature treatment process. This resulted in some chromium remaining in a solid solution state within the copper lattice, failing to fully precipitate and form a stable, fine precipitate network near the grain boundaries and interfaces. On one hand, the lattice distortion and electron scattering caused by the solid solution chromium reduced thermal conductivity, leading to an overall decrease in thermal conductivity. On the other hand, insufficient precipitation strengthening at the interfaces and grain boundaries reduced interfacial shear strength and flexural strength. Under thermal cycling conditions, the lack of sufficient heat holding for interface stabilization and stress relaxation resulted in decreased thermal shock resistance.

[0118] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a diamond-copper heat spreader material, characterized in that, The preparation method includes: S1: Mix copper powder and chromium powder to obtain a mixed powder, add ethanol, ball mill in an argon atmosphere using a high-energy ball mill, dry, and sieve to obtain copper-chromium solid solution powder; S2: Place silicon carbide micro powder in ethanol for ultrasonic cleaning, filter, and dry to obtain cleaned silicon carbide; disperse the cleaned silicon carbide in a sensitizing solution, stir at room temperature, filter, and wash to obtain sensitized silicon carbide; disperse the sensitized silicon carbide in an activation solution, stir at room temperature, filter, and wash with water to obtain activated silicon carbide; disperse the activated silicon carbide in a copper plating solution to obtain a suspension, adjust the pH with sodium hydroxide solution to obtain reaction solution A, stir the reaction, filter, wash, and dry to obtain copper-coated silicon carbide micro powder. S3: Diamond, copper-coated silicon carbide micro powder and copper-chromium solid solution powder are mixed to obtain a mixture. Ethanol is added and mixed to obtain a second mixture. After drying, the mixture is sieved to obtain a third mixture. A layer of copper foil is laid at the bottom of the mold. The third mixture is loaded into the mold and cold pre-pressed. Then, a layer of copper foil of the same specification is covered on top to obtain a preform. S4: The preform is placed in a spark plasma sintering furnace for vacuum sintering: the temperature is raised to the first temperature at the first heating rate and held at the first temperature, while axial pressure is applied. Then the temperature is raised to the second temperature at the second heating rate and held at the second temperature. After sintering, the axial pressure is unloaded and the sintering current is cut off. The material is cooled to the third temperature of 350-500℃ in an inert atmosphere and held at the third temperature. After natural cooling, the material is demolded to obtain the diamond copper isothermal plate material.

2. The method for preparing a diamond-copper heat spreader material according to claim 1, characterized in that, In S1: The mass ratio of copper powder to chromium powder is (97-99):(3-1); The amount of ethanol fed is (1-2) of the mass of the mixed powder.

3. The method for preparing a diamond-copper heat spreader material according to claim 1, characterized in that, In S2: The concentration of stannous chloride in the sensitizing solution is (10-20) g / L; The concentration of hydrochloric acid in the sensitizing solution is (20-40) mL / L; The mass-to-volume ratio of the cleaned silicon carbide to the sensitizing solution is 1 g:(20-50) mL.

4. The method for preparing a diamond-copper heat spreader material according to claim 1, characterized in that, In S2: The concentration of palladium chloride in the activation solution is (0.3-0.5) g / L; The concentration of hydrochloric acid in the activation solution is (5-10) mL / L; The mass-to-volume ratio of the sensitized silicon carbide to the activation solution is 1 g:(20-50) mL.

5. The method for preparing a diamond-copper heat spreader material according to claim 1, characterized in that, In S2: The mass-to-volume ratio of the activated silicon carbide to the copper plating solution is (5-15) g: 1000 mL; The molar ratio of copper sulfate to ethylenediaminetetraacetic acid in the copper plating solution is 1:(2-4).

6. The method for preparing a diamond-copper heat spreader material according to claim 1, characterized in that, In S2: The molar ratio of copper sulfate to sodium phosphite in the copper plating solution is 1:(1.5-3); The concentration of copper sulfate in the copper plating solution is 10-20 g / L.

7. The method for preparing a diamond-copper heat spreader material according to claim 1, characterized in that, In S3: The volume percentages of the diamond, copper-coated silicon carbide micro powder, and copper-chromium solid solution powder are (50-55):(5-12):(35-45); The amount of ethanol added is (2-5)% of the mass of the mixture.

8. The method for preparing a diamond-copper heat spreader material according to claim 1, characterized in that, In S3: The thickness of the copper foil is (0.05-0.3) mm; The pressure of the cold pre-compression is (5-10) MPa; The loading amount of the third mixture is (0.8-1.5) g / cm2.

9. The method for preparing a diamond-copper heat spreader material according to claim 1, characterized in that, In S4: The first temperature is 500-700℃; The applied axial pressure is 40-60 MPa; The second temperature is 800-1000℃.

10. A diamond copper heat spreader material prepared by the preparation method according to any one of claims 1-9.

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