A carboxyl-thiol undecanamine interconnecting graphene film / gold-plated substrate structure for reducing interfacial thermal resistance and a preparation method and application thereof

Abstract

This invention relates to a carboxyl-mercaptoundecylamine interconnected graphene film / gold-plated substrate structure for reducing interfacial thermal resistance, its preparation method, and its application. The structure is formed by hot pressing a functionalized gold-plated substrate and a graphene film. The functionalized gold-plated substrate includes a copper substrate and a self-assembled monomolecular film disposed on the surface of the copper substrate. The self-assembled monomolecular film consists of a gold layer and a covalent bond structure formed between the gold layer and organic molecules with thiol structures. The surface of the graphene film also includes active groups for connecting with the self-assembled monomolecular film to form an interfacial structure. Compared with existing technologies, using carboxyl-mercaptoundecylamine to construct the molecular interconnection structure between the graphene film and the gold-plated substrate effectively reduces interfacial thermal resistance while improving interfacial adhesion. It has the advantages of simple process, stable structure, and suitability for industrial scaling.

Description

Technical Field

[0001] This invention belongs to the field of graphene high-temperature electrothermal film technology, and relates to a carboxyl-mercaptoundecylamine interconnected graphene film / gold-plated substrate structure for reducing interfacial thermal resistance, its preparation method and application. Background Technology

[0002] As electronic devices become increasingly integrated and power-density, the heat flux density in "hot spot" areas inside chips increases dramatically, leading to significant local temperature rises and affecting the operational stability and lifespan of the devices. Studies have shown that over 50% of electronic device failures are caused by excessive temperature, and the failure rate increases exponentially with temperature. Thermal management has become one of the key technological bottlenecks.

[0003] Graphene, due to its extremely high in-plane thermal conductivity, has become an ideal material for thermal management of high heat flux density devices. However, a large interfacial thermal resistance often exists between graphene films and metal substrates, severely weakening the overall heat dissipation performance. Traditional bonding methods, such as thermally conductive tapes and silver paste, have significant shortcomings in terms of reliability, thermal conductivity, and cost.

[0004] In recent years, constructing molecular-scale chemically bonded interconnected structures has been considered an effective way to reduce interfacial thermal resistance, achieving efficient interfacial heat conduction by enhancing phonon coupling. For example, Sumanjeet Kaur's team (DOI: 10.1038 / ncomms4082) proposed introducing covalent organic molecules (1-pyrenebutyric acid) between a vertically aligned multi-walled carbon nanotube array and a metal substrate to form a molecular bridging structure at the interface. This bridging structure significantly enhanced the coupling effect of interfacial thermal phonons, reducing interfacial thermal resistance by approximately six times. Similarly, Mark D. Losego's team (doi: 10.1038 / nmat3303) proposed introducing a self-assembled monolayer between an inorganic material and a gold film as an interfacial control structure. This type of molecular layer forms stable chemical anchoring connections with the surfaces of both materials through its terminal functional groups, effectively reducing the disorder and porosity of the interfacial structure, improving the heat flow conduction path in the heterogeneous interface, and enhancing interfacial thermal conductivity.

[0005] Although research has shown that introducing covalent bridging molecules or self-assembled monolayers between carbon nanostructures and metal interfaces can improve interfacial thermal conductivity, existing technologies still have the following problems: (1) Insufficient interfacial bonding stability: Self-assembled molecular layers rely on van der Waals forces or weak coordination bonds to bond with the metal substrate. They are prone to desorption due to heat treatment, humidity and aging, making it difficult to meet the requirements for long-term stable operation of high-power devices.

[0006] (2) Disordered molecular structure and severe phonon scattering: For example, the bridging molecular chains of 1-pyrene butyric acid are long and soft, and are prone to accumulation and disordered state at the interface, resulting in enhanced phonon scattering and difficulty in establishing a continuous and efficient thermal phonon conduction path.

[0007] (3) The process is complex and difficult to scale up: Some interface modification technologies rely on multi-step metallization or precision deposition equipment, which are complex and costly, limiting their widespread application in actual electronic packaging processes.

[0008] (4) Limited scope of application: Existing research mainly focuses on the interface between carbon nanotubes and metal films, and lacks a general method for constructing interconnect interfaces with low thermal resistance and high bonding strength between graphene films and metal (such as gold) substrates. There is still a significant gap in the field of thermal management of heterogeneous interfaces of two-dimensional materials.

[0009] Therefore, there is an urgent need to develop a novel molecular interconnection strategy with strong interfacial bonding, ordered structure, and controllable covalent bond chain length to effectively reduce the interfacial thermal resistance between graphene films and metal substrates, and meet the growing thermal management requirements of high power density devices. Summary of the Invention

[0010] The purpose of this invention is to overcome any one or more of the problems in the prior art, such as high interfacial thermal resistance, low interfacial bonding strength, and complex interconnection process between graphene film and metal substrate, and to provide a carboxyl-mercaptoundecylamine interconnected graphene film / gold-plated substrate structure and its preparation method for reducing interfacial thermal resistance.

[0011] The objective of this invention can be achieved through the following technical solutions: One of the technical solutions of the present invention is to provide a carboxyl-mercaptoundecylamine interconnected graphene film / gold-plated substrate for reducing interfacial thermal resistance, which is formed by hot pressing a functionalized gold-plated substrate and a graphene film, wherein... The functionalized gold-plated substrate includes a copper substrate and a self-assembled monomolecular film disposed on the surface of the copper substrate. The self-assembled monomolecular film is composed of a gold layer and a covalent bond connection structure formed with thiol undecylamine. The surface of the graphene film also includes active groups for connecting with the self-assembled monolayer to form an interface structure.

[0012] The second technical solution of the present invention provides a method for preparing a carboxyl-mercaptoundecylamine interconnected graphene film / gold-plated substrate for reducing interfacial thermal resistance as described in one of the above technical solutions, comprising the following steps: S1. A gold layer is deposited on the surface of a copper substrate to obtain a gold-plated substrate. The gold-plated substrate is immersed in an organic solution containing thiolated undecylamine and reacted at room temperature to form a self-assembled monolayer on the surface of the gold-plated substrate. After curing, a functionalized gold-plated substrate is obtained. S2. Immerse the graphene film in a mixed acid solution and react to introduce active groups on the surface of the graphene film, thus obtaining an activated graphene film. S3. Sequentially lay the activated graphene film obtained in step S2, the functionalized gold-plated substrate obtained in step S1, and the top graphene block on the surface of the bottom graphite block, hot-press and separate to obtain a carboxyl-mercaptoundecylamine interconnected graphene film / gold-plated substrate.

[0013] In some specific embodiments, in step S1, when plating a gold layer on the surface of a copper substrate, a nickel layer is first plated on the surface of the copper substrate, and then a gold layer is plated. The thickness of the nickel layer is (2~4) μm, and the thickness of the gold layer is (90~110) nm.

[0014] In some specific embodiments, in step S1, the organic solution containing thiocyanate undecylamine is toluene, and the concentration of thiocyanate undecylamine is (45~55) mg / L.

[0015] In some specific embodiments, in step S1, the reaction time at room temperature is at least 3 minutes and the temperature is 15-25°C; The curing temperature is (110~130)℃ and the curing time is (25~35)min.

[0016] In some specific embodiments, in step S2, the mixed acid solution is a mixed solution of concentrated sulfuric acid and concentrated nitric acid, with a volume ratio of concentrated sulfuric acid to concentrated nitric acid of 3:1.

[0017] In some specific embodiments, in step S2, the reaction time is 0.5 min to 180 min, and the temperature is 15 to 25 °C.

[0018] In some specific embodiments, in step S3, the hot pressing temperature is (110~130)℃, the hot pressing time is (0.5~1.5) h, and the hot pressing pressure is 300 Pa-800 Pa.

[0019] The third technical solution of the present invention is to provide an application of the carboxyl-mercapto-undecitabine interconnected graphene film / gold-plated substrate as described in one of the above technical solutions in the fabrication of electronic devices.

[0020] Compared with the prior art, the present invention has the following advantages: (1) This invention introduces thiol undecylamine on the surface of a metal substrate to form Au-S covalent bonds with the gold surface, thereby constructing a chemically bonded interface functional layer. The graphene film and the metal substrate are connected by chemical covalent bonds. That is, by functionalizing the surface of the graphene film, a strong covalent bond is formed between it and the surface of the metal substrate which is also chemically functionalized. This is beneficial to improving the bonding strength and thermal coupling efficiency between the graphene film and the metal substrate, thereby forming a continuous and efficient heat transfer channel in the heat conduction path, providing heat dissipation efficiency and significantly reducing the interface thermal resistance.

[0021] Furthermore, the mercaptoundecylamine molecules used are modified in the form of a monolayer on the gold-plated substrate, and no polymerization or cross-linking reactions occur between the mercaptoundecylamine molecules, which effectively shortens the length of the molecular chain at the interface, avoids the disorder of the molecular structure at the interface, and achieves controllable covalent bond chain length.

[0022] (2) In this invention, the graphene film is treated with mixed acid to introduce active functional groups such as carboxyl and hydroxyl groups at its defect sites and edges, which is beneficial to form stable non-covalent interactions (such as hydrogen bonds and electrostatic adsorption) with the functionalized metal substrate, thereby improving interface matching and heat transfer continuity while maintaining the high thermal conductivity of the graphene body.

[0023] (3) The present invention utilizes a dual-functionalized interface interconnection structure between a metal substrate and a graphene film. On the one hand, a regular covalent bond connection structure is constructed on the surface of the metal substrate, which improves the uniformity of molecular connection and the continuity of thermal conduction path. On the other hand, active functional groups are introduced on the surface of the graphene film to enhance its matching degree and stability with the interface layer, thereby effectively reducing the interface thermal resistance between the graphene film and the metal substrate and improving the overall thermal transfer performance. This dual-functionalized interconnection structure realizes the construction of a continuous and efficient thermal phonon conduction channel at the molecular level, which is beneficial to improving the thermal management capability of high power density electronic devices and is suitable for large-scale industrial packaging scenarios.

[0024] (4) The present invention uses carboxyl-mercaptoundecylamine to construct the molecular interconnection structure between the graphene film and the gold-plated substrate, which improves the interfacial bonding force and effectively reduces the interfacial thermal resistance. It has the advantages of simple process, stable structure and suitable for industrial expansion. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of introducing thiol-undecylamine onto the surface of the gold-plated substrate in Example 1.

[0026] Figure 2 This is a schematic diagram of the structure in which active groups such as carboxyl and hydroxyl groups are introduced on the surface of the graphene film in Example 1.

[0027] Figure 3 This is a schematic diagram of the structure of the graphene film / gold-plated substrate interconnect sample in Comparative Example 1.

[0028] Figure 4 In Example 1, the interfacial thermal resistance of the carboxyl-mercaptoundecylamine interconnected graphene film / gold-plated substrate structure under different functionalization times of the gold-plated substrate is shown.

[0029] Figure 5 The above are FTIR spectra of the carboxyl-mercaptoundecylamine interconnected graphene film / gold substrate structure at different functionalization times of the gold-plated substrate in Example 1. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0032] Example 1: This embodiment provides a method for preparing a carboxyl-mercaptoundecylamine interconnected graphene film / gold-plated substrate for reducing interfacial thermal resistance, comprising the following steps: (I) Preparation of functionalized gold-plated substrates (1) Select a copper substrate material and electroplate a nickel layer with a thickness of about 3 μm and a gold layer with a thickness of about 100 nm on its surface to obtain a gold-plated substrate. The nickel layer plays the role of enhancing the adhesion between the gold layer and the copper substrate, and the gold layer is used to construct Au-S bonds to achieve molecular interconnection.

[0033] (2) Place the above gold-plated substrate in acetone and anhydrous ethanol for ultrasonic cleaning (5 minutes each) to remove surface contaminants and residues. After cleaning, blow dry and set aside.

[0034] (3) Prepare a 50 mg / L solution of thiocyanate undecylamine toluene and sonicate it for 30 minutes to dissolve it completely.

[0035] (4) The cleaned gold-plated substrate was immersed in the above-mentioned thiol-undecanylamine toluene solution and reacted at room temperature (25°C) for approximately 10 min, 30 min, 60 min, 120 min, and 240 min, respectively. The thiol-undecanylamine molecules formed stable Au-S covalent bonds with gold atoms through their terminal thiol groups, thus constructing a self-assembled monolayer on the surface of the gold-plated substrate, such as... Figure 1 As shown.

[0036] (5) After removing the gold-plated substrate, clean the unbound molecules with toluene and cure it in a vacuum drying oven at 120°C for 30 minutes to obtain the functionalized gold-plated substrate.

[0037] (II) Activation treatment of graphene film (1) Slowly add concentrated sulfuric acid to concentrated nitric acid (the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1) and stir continuously to avoid localized drastic temperature rise, so as to obtain a mixed acid solution.

[0038] (2) The graphene film to be treated is immersed in the above mixed acid solution and reacted at 25°C for 100 min to introduce active functional groups such as carboxyl and hydroxyl groups into surface defects and edge sites, such as... Figure 2 As shown.

[0039] (3) Take out the treated graphene film and wash it in deionized water for 2 hours to remove residual mixed acid.

[0040] (4) After cleaning, place the graphene film in a vacuum drying oven and dry it at 80°C for 2 hours to remove residual moisture.

[0041] (III) Assembly and Construction of Interface Structure (1) The activated graphene film is laid flat on the surface of the graphite block, and then the functionalized gold-plated substrate is placed on top of the graphene film. (2) Place another graphite block on the functionalized gold-plated substrate, align the upper and lower graphite blocks, and use high-temperature resistant tape to fix the edges to prevent misalignment during hot pressing. (3) Place the assembled graphite block assembly in a vacuum drying oven, apply a pressure of 500 Pa, and hot press at 120°C for 1 hour; (4) After hot pressing, remove the graphite block assembly, remove the tape and separate the graphite block to obtain an interface interconnection structure in which the graphene film and the functionalized gold-plated substrate are firmly bonded. (5) Cut off the excess graphene film to obtain the graphene film / gold-plated substrate interconnect sample, namely the carboxyl-mercapto-undecitabine interconnect graphene film / gold-plated substrate.

[0042] Comparative Example 1 This comparative example provides a method for connecting an unfunctionalized gold-plated substrate and a graphene film using thermally conductive tape, comprising the following steps: (a) Preparation of gold-plated substrate (1) Select a copper substrate material and electroplate a nickel layer with a thickness of about 3 μm and a gold layer with a thickness of about 100 nm on its surface to obtain a gold-plated substrate. The nickel layer plays the role of enhancing the adhesion between the gold layer and the copper substrate.

[0043] (2) Place the above gold-plated substrate in acetone and anhydrous ethanol for ultrasonic cleaning (5 minutes each) to remove surface contaminants and residues. After cleaning, blow dry and set aside.

[0044] (II) Activation treatment of graphene film (1) Slowly add concentrated sulfuric acid to concentrated nitric acid (the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1) and stir continuously to avoid localized drastic temperature rise, so as to obtain a mixed acid solution.

[0045] (2) The graphene film to be treated is immersed in the above mixed acid solution and reacted at 25°C for 100 min to introduce active functional groups such as carboxyl and hydroxyl groups into surface defects and edge sites, such as... Figure 2 As shown.

[0046] (3) Take out the treated graphene film and wash it in deionized water for 2 hours to remove residual mixed acid.

[0047] (4) After cleaning, place the graphene film in a vacuum drying oven and dry it at 80°C for 2 hours to remove residual moisture.

[0048] (III) Assembly and Construction of Interface Structure (1) The activated graphene film is laid flat on the surface of the graphite block, and then the gold-plated substrate is placed on top of the graphene film. Thermally conductive tape is used for interconnection, such as... Figure 3 As shown; (2) Place another graphite block on the gold-plated substrate, align the upper and lower graphite blocks, and use high-temperature resistant tape to fix the edges to prevent misalignment during hot pressing. (3) Place the assembled graphite block assembly in a vacuum drying oven, apply a pressure of 500 Pa, and hot press at 120°C for 1 hour; (4) After hot pressing, remove the graphite block assembly, remove the tape and separate the graphite block to obtain the interface interconnection structure of graphene film and gold-plated substrate. (5) Cut off the excess graphene film to obtain the graphene film / gold-plated substrate interconnect sample.

[0049] The interconnected graphene films / gold-plated substrates prepared in Example 1 and Comparative Example 1 were subjected to the following performance tests: The thermal resistance of the graphene film / substrate interconnect structure was measured using a transient thermal testing instrument, the T3ster (sampling rate 1 µs, test delay time 1 µs, junction temperature resolution 0.01 °C). Figure 4 As shown.

[0050] When the functionalization time of the gold-plated substrate reaches 4 hours (the time the gold-plated substrate is immersed in a solution of undecylamine toluene), the interfacial thermal resistance of the prepared graphene film / gold-plated substrate interconnect structure can be reduced to 2.85 ± 0.1 mm. 2 ·K·W -1 Compared to traditional thermally conductive tape interconnection methods (interfacial thermal resistance is 4.51±0.05 mm), 2 KW -1 This reduces the interfacial thermal resistance by approximately 37%.

[0051] like Figure 5 The image shows the FTIR spectra of gold-plated substrates with different functionalization times. The unfunctionalized gold-plated substrate did not show any obvious characteristic peaks, while the functionalized gold-plated substrate showed obvious characteristic peaks at multiple locations, including 1470 cm⁻¹. -1 2850 cm -1 and 2920 cm -1 All three characteristic peaks are related to the -CH2- group, 1470 cm⁻¹ -1 The characteristic peak at 2850 cm⁻¹ is generated by the bending vibration of -CH₂-. -1 The characteristic peak at 2920 cm⁻¹ is the symmetric stretching vibration peak of -CH₂-. -1 The characteristic peaks are related to the asymmetric stretching vibrations of -CH2-. Even after functionalization, the gold-plated substrate still exhibits peaks at 3200-3500 cm⁻¹. -1 A broad and weak characteristic peak appears at 1520 cm⁻¹. -1 A narrow characteristic peak appears at 3200-3500 cm⁻¹, and both of these characteristic peaks are related to amino functional groups. -1 The characteristic peak at 1520 cm⁻¹ is related to the stretching vibration of NH₃. -1 The characteristic peak at 720 cm⁻¹ is generated by the bending vibration of CN. The gold-plated substrate, after functionalization, exhibits this characteristic peak. -1 The newly emerging characteristic peaks are related to the stretching vibration of CS. The presence of CS, NH, and -CH2- indicates that undecylamine is immobilized on the substrate surface, successfully modifying the gold-plated substrate. As shown in the figure, the intensity of the characteristic peaks related to -CH2- and NH increases with the increase of the functionalization time of the gold-plated substrate, indicating that the longer the functionalization time of the gold-plated substrate, the more Au-S covalent bonds are formed on the surface of the gold-plated substrate, the more undecylamine molecules are immobilized on the gold-plated substrate, and the more amino groups are carried on the surface of the gold-plated substrate.

[0052] As can be seen, with the extension of the functionalization reaction time of the gold-plated substrate, the orderliness of the interface structure and the molecular binding density are significantly enhanced, thereby improving the interface thermal conductivity. This result also fully demonstrates the significant effect of this invention in improving the thermal interface performance of graphene, and has excellent potential for thermal management applications, especially suitable for the heat dissipation requirements of high power density electronic devices.

[0053] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A carboxyl-mercaptoundecylamine interconnected graphene film / gold-plated substrate for reducing interfacial thermal resistance, characterized in that, It is formed by hot pressing a functionalized gold-plated substrate and a graphene film, wherein... The functionalized gold-plated substrate includes a copper substrate and a self-assembled monomolecular film disposed on the surface of the copper substrate. The self-assembled monomolecular film is composed of a gold layer and a covalent bond connection structure formed with thiol undecylamine. The surface of the graphene film also includes active groups for connecting with the self-assembled monolayer to form an interface structure.

2. A method for preparing a carboxyl-mercaptoundecylamine interconnected graphene film / gold-plated substrate for reducing interfacial thermal resistance as described in claim 1, characterized in that, Includes the following steps: S1. A gold layer is deposited on the surface of a copper substrate to obtain a gold-plated substrate. The gold-plated substrate is immersed in an organic solution containing thiolated undecylamine and reacted at room temperature to form a self-assembled monolayer on the surface of the gold-plated substrate. After curing, a functionalized gold-plated substrate is obtained. S2. Immerse the graphene film in a mixed acid solution and react to introduce active groups on the surface of the graphene film, thus obtaining an activated graphene film. S3. Sequentially lay the activated graphene film obtained in step S2, the functionalized gold-plated substrate obtained in step S1, and the top graphene block on the surface of the bottom graphite block, hot-press and separate to obtain a carboxyl-mercaptoundecylamine interconnected graphene film / gold-plated substrate.

3. The preparation method according to claim 2, characterized in that, In step S1, when depositing a gold layer on the surface of a copper substrate, a nickel layer is first deposited on the surface of the copper substrate, and then a gold layer is deposited. The thickness of the nickel layer is (2~4) μm, and the thickness of the gold layer is (90~110) nm.

4. The preparation method according to claim 2, characterized in that, In step S1, the organic solution containing thiocyanate undecylamine is toluene, and the concentration of thiocyanate undecylamine is (45~55) mg / L.

5. The preparation method according to claim 2, characterized in that, In step S1, the reaction time at room temperature is at least 3 minutes, and the temperature is 15-25°C.

6. The preparation method according to claim 2, characterized in that, In step S1, the curing temperature is (110~130)℃ and the curing time is (25~35)min.

7. The preparation method according to claim 2, characterized in that, In step S2, the mixed acid solution is a mixture of concentrated sulfuric acid and concentrated nitric acid, with a volume ratio of 3:

1.

8. The preparation method according to claim 2, characterized in that, In step S2, the reaction time is 0.5 min to 180 min, and the temperature is 15 to 25 °C.

9. The preparation method according to claim 2, characterized in that, In step S3, the hot pressing temperature is (110~130)℃, the hot pressing time is (0.5~1.5) h, and the hot pressing pressure is 300 Pa-800 Pa.

10. The application of the carboxyl-mercaptoundecylamine interconnected graphene film / gold-plated substrate as described in claim 1 in the fabrication of electronic devices.

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