Copper-diamond-copper sandwich structure water-cooled radiator and preparation method thereof

Abstract

The invention is suitable for the technical field of heat dissipation of high-power electronic devices, and provides a copper-diamond-copper sandwich structure water-cooling radiator and a preparation method thereof.The main body structure of the water-cooling radiator is of a sandwich structure, the upper layer is copper, the middle layer is an MPCVD diamond polycrystalline or single crystal material, and the lower layer is copper; furthermore, the lower-layer copper can be of a special water cooling channel structure, and the purpose of liquid cooling heat dissipation is achieved. The middle diamond layer plays a role in rapidly guiding out heat of the chip, and the heat is taken away by the water cooling channel for heat dissipation. And the surface layer copper is convenient for processing during chip packaging. The sandwich structure is achieved through the AMB active brazing technology, the slurry of the middle layer is the nano-silver active solder, low-temperature brazing is achieved, the high-temperature thermal cycle reliability after welding is met, the technology has high application value, and powerful support is provided for next-generation water cooling heat dissipation.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat dissipation of high-power electronic devices, and in particular relates to a water-cooled radiator with a copper-diamond-copper sandwich structure and a preparation method thereof. Background Art

[0002] With the rapid development of fields such as artificial intelligence and high-performance computing, the computing power demand for high-power electronic devices (such as GPUs and AI chips) continues to rise, and chip power density has increased significantly. Traditional heat dissipation technologies face severe challenges, especially in the field of liquid cooling. The thermal conductivity and structural design of existing materials are gradually unable to meet the demand for efficient heat dissipation.

[0003] Currently, copper-based water cooling plates remain the mainstream solution due to their ease of processing. However, their upper thermal conductivity limit (approximately 400 W / m·K) makes it difficult to meet the heat dissipation requirements of future higher-power GPU devices. The industry urgently needs breakthrough material and structural innovations to achieve more efficient and stable cooling solutions.

[0004] The upper limit of thermal conductivity of traditional copper-based water-cooling plates is insufficient to meet the heat dissipation requirements of high-power chips (e.g., 500W / cm² heat flux density). Furthermore, the interface thermal conductivity of traditional diamond / copper composites decreases significantly after high-temperature heat treatment, impacting long-term reliability. Conventional brazing processes also lack temperature resistance, making the heat sink susceptible to interfacial cracking or delamination during thermal cycling. Summary of the Invention

[0005] The purpose of the present invention is to provide a copper-diamond-copper sandwich structure water-cooled radiator and its preparation method, aiming to solve the problem of low thermal conductivity of traditional copper and the problem of significant decrease in high and low temperature cycle thermal conductivity of single diamond / copper composite materials.

[0006] The present invention is achieved in this way:

[0007] A copper-diamond-copper sandwich structure water cooling radiator adopts a sandwich structure:

[0008] Upper layer: Electrolytic copper foil (thickness 0.3-0.5mm), used for chip packaging and processing adaptation.

[0009] Intermediate layer: Diamond single crystal or polycrystalline layer grown by MPCVD (thickness 0.1-2mm, thermal conductivity ≥1200 W / m·K), serving as the core thermal conductive layer.

[0010] Lower layer: Copper substrate (2-6mm thick) with asymmetric involute microchannels or macrochannels (channel pitch to depth ratio 1:3 to 1:5) on the surface for liquid cooling.

[0011] Interface connection technology:

[0012] Using AMB (Active Metal Brazing) active brazing process, using nano silver solder paste (Ag content ≥ 95%, particle size 20-50nm, adding 0.5-1.5wt% activator), brazing temperature 260-300℃, pressure 0.5-1.2MPa, holding time 8-15 minutes, achieving low temperature bonding and high temperature reliability.

[0013] The present invention provides a copper-diamond-copper sandwich structure water-cooled radiator and a preparation method thereof, which has the following beneficial effects:

[0014] 1. By introducing an MPCVD diamond layer with a thermal conductivity of ≥1200 W / m·K, the overall thermal conductivity of the heat sink is increased to >800 W / m·K, which is twice as high as that of traditional copper-based solutions.

[0015] 2.AMB active brazing process combined with nano silver solder paste to ensure interface thermal resistance <5× m²·K / W, no failure after 1000 times of -40℃~150℃ thermal cycle test.

[0016] 3. The surface roughness of the upper copper foil reaches the nanometer level, meeting the requirements of electronic-grade chip packaging.

[0017] 4. The lower copper substrate meets the performance requirements of skiving and is denser than the copper layer obtained by traditional powder metallurgy composite materials.

[0018] 5. By designing the thickness of different upper copper foils, the thermal expansion coefficient of the sandwich structure can be adjusted to meet the thermal expansion coefficient requirements of different chip packages. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a diagram of the copper-diamond-copper sandwich structure. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0022] like Figure 1 As shown, a copper-diamond-copper sandwich structure water cooling radiator includes an upper layer, a middle layer and a lower layer, wherein:

[0023] The upper layer is electrolytic copper foil with a thickness of 0.3-0.5mm;

[0024] The middle layer is a diamond single crystal thermal conductive layer or a polycrystalline thermal conductive layer grown by MPCVD method, with a thickness of 0.1-2mm and a thermal conductivity of ≥1200 W / m·K;

[0025] The lower layer is a copper substrate with a thickness of 2-6 mm. The surface is equipped with microchannels and macrochannels. The channel layout is an asymmetric involute structure, and the channel spacing to depth ratio is 1:3 to 1:5.

[0026] The upper layer, the middle layer and the lower layer are connected by an AMB active brazing process.

[0027] A method for preparing a copper-diamond-copper sandwich structure water-cooling radiator, the method comprising:

[0028] S1, performing laser texturing on the diamond layer to form a regular pit array;

[0029] S2, processing asymmetric involute microchannels on a copper substrate and performing surface pickling activation;

[0030] S3, using nanosilver active solder paste to apply to the connection interface by ultrasound-assisted screen printing;

[0031] S4. Complete the brazing connection of the three-layer structure using a gradient pressure control process in a vacuum brazing furnace, with a brazing temperature of 260-300°C, a pressure of 0.5-1.2 MPa, and a holding time of 8-15 minutes.

[0032] Example 1:

[0033] Diamond layer treatment: Polycrystalline diamond was grown in an MPCVD device (methane concentration 30%, deposition rate 10μm / h) to a thickness of 0.5mm. Double-sided laser etching was used to form a regular pit array (depth 20μm, spacing 100μm).

[0034] The thickness of the electrolytic copper foil is 0.3 mm.

[0035] The copper substrate is 3 mm thick, and the microchannels are processed by femtosecond laser etching (pulse energy 0.5 mJ, frequency 100 kHz), and the surface is activated by acid pickling ( =1:3, processing time 30s)

[0036] Brazing process:

[0037] Nano silver solder paste (containing 20-50nm silver powder and nano The composite filler (ethyl cellulose and rosin derivative in a ratio of 3:1) was applied to the interface by ultrasound-assisted screen printing with a thickness of 50 μm.

[0038] Implement a three-stage heating process in a vacuum brazing furnace:

[0039] Preheating stage: 150℃ for 5 minutes;

[0040] Brazing stage: 260℃ for 10 minutes, pressure 0.8MPa;

[0041] Slow cooling stage: cooling to room temperature at a rate of 10℃ / min, vacuum degree ≤5× Pa.

[0042] Example 2:

[0043] Diamond layer treatment: Polycrystalline diamond was grown in an MPCVD device (methane concentration 40%, deposition rate 12μm / h) to a thickness of 1.5mm. Double-sided laser etching was used to form a regular pit array (depth 10μm, spacing 30μm).

[0044] The thickness of the electrolytic copper foil is 0.5 mm.

[0045] The copper substrate is 6 mm thick, and the microchannels are processed by femtosecond laser etching (pulse energy 0.5 mJ, frequency 100 kHz), and the surface is activated by acid pickling ( =1:3, processing time 60s)

[0046] Brazing process:

[0047] Nano silver solder paste (containing 20-50nm silver powder and nano The composite filler (ethyl cellulose and rosin derivative in a ratio of 3:1) was applied to the interface by ultrasound-assisted screen printing with a thickness of 30 μm.

[0048] Implement a three-stage heating process in a vacuum brazing furnace:

[0049] Preheating stage: 150℃ for 5 minutes;

[0050] Brazing stage: 260℃ for 10 minutes, pressure 0.8MPa;

[0051] Slow cooling stage: cooling to room temperature at a rate of 10℃ / min, vacuum degree ≤5× Pa.

[0052] Example 3:

[0053] Diamond layer treatment: Single crystal diamond was grown in an MPCVD device (methane concentration 20%, deposition rate 2μm / h) to a thickness of 2mm. Double-sided laser etching was used to form a regular pit array (depth 5μm, spacing 10μm).

[0054] The thickness of the electrolytic copper foil is 0.4 mm.

[0055] The copper substrate is 2 mm thick, and the microchannels are processed by femtosecond laser etching (pulse energy 0.6 mJ, frequency 100 kHz), and the surface is activated by acid pickling ( =1:3, processing time 20s)

[0056] Brazing process:

[0057] Nano silver solder paste (containing 20-50nm silver powder and nano The composite filler (ethyl cellulose and rosin derivative in a ratio of 3:1) was applied to the interface by ultrasound-assisted screen printing with a thickness of 30 μm.

[0058] Implement a three-stage heating process in a vacuum brazing furnace:

[0059] Preheating stage: 150℃ for 5 minutes;

[0060] Brazing stage: 260℃ for 10 minutes, pressure 0.8MPa;

[0061] Slow cooling stage: cooling to room temperature at a rate of 10℃ / min, vacuum degree ≤5× Pa.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A copper-diamond-copper sandwich structure water-cooled radiator, characterized in that: The copper-diamond-copper sandwich structure water-cooling radiator includes an upper layer, a middle layer and a lower layer, wherein: The upper layer is electrolytic copper foil with a thickness of 0.3-0.5mm; The middle layer is a diamond single crystal thermal conductive layer or a polycrystalline thermal conductive layer grown by MPCVD method, with a thickness of 0.1-2mm and a thermal conductivity of ≥1200 W / m·K; The lower layer is a copper substrate with a thickness of 2-6 mm. The surface is equipped with microchannels and macrochannels. The channel layout is an asymmetric involute structure, and the channel spacing to depth ratio is 1:3 to 1:

5. The upper layer, the middle layer and the lower layer are connected by an AMB active brazing process.

2. The copper-diamond-copper sandwich structure water-cooling radiator according to claim 1, characterized in that: The surface of the microchannel copper substrate is provided with a turbulence promoting structure, including periodic protrusions with a height of 50 μm.

3. The copper-diamond-copper sandwich structure water-cooling radiator according to claim 1, characterized in that: The surface of the diamond layer is laser textured to form a pit array with a depth of 20 μm and a spacing of 100 μm.

4. A method for preparing a copper-diamond-copper sandwich structure water-cooling radiator according to any one of claims 1 to 3, characterized in that: The preparation method comprises: S1, performing laser texturing on the diamond layer to form a regular pit array; S2, processing asymmetric involute microchannels on a copper substrate and performing surface pickling activation; S3, using nanosilver active solder paste to apply to the connection interface by ultrasound-assisted screen printing; S4. Complete the brazing connection of the three-layer structure using a gradient pressure control process in a vacuum brazing furnace, with a brazing temperature of 260-300°C, a pressure of 0.5-1.2 MPa, and a holding time of 8-15 minutes.

5. The method for preparing a copper-diamond-copper sandwich structure water-cooling radiator according to claim 4, characterized in that: The nano silver active solder paste comprises 20-50nm silver powder and nano The composite filler of the particles, the organic carrier is composed of ethyl cellulose and rosin derivatives in a ratio of 3:

1.

6. The method for preparing a copper-diamond-copper sandwich structure water-cooling radiator according to claim 4, characterized in that: The brazing process adopts a three-stage heating curve, including preheating at 150°C for 5 minutes, brazing at 260°C for 10 minutes, and slow cooling to a cooling rate of 80°C / minute.

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