A Cu / graphene film layered composite material and preparation method thereof

Abstract

The present invention relates to the technical field of high thermal conductivity copper-based electronic packaging materials, and discloses a method for preparing a Cu / graphene film layered composite material, characterized in that the steps are as follows: Step 1: Process copper foil, titanium foil, and graphene film into a disc with a diameter of 30 mm, and then use a puncher to punch holes in the disc; The above-punched disc is ultrasonically pickled in a hydrochloric acid solution, and then washed with anhydrous ethanol and dried in a drying oven; Step 2: The disc obtained in step 1 is molded in the order of Cu-Ti-GN-Ti; Step 3: After the mold in step 2 is pre-pressed by 10MPa in advance, it is placed in a sintering furnace cavity for sintering. In the present invention, the layered material uses Cu as a skeleton to ensure that the material has a certain strength, and Cu and graphene together serve as a heat dissipation body, so that the thermal conductivity of the layered material is much higher than that of pure copper. At the same time, because the density of graphene is low, it is only one-tenth of pure copper, which reduces the density of the layered material and is suitable for lightweight production.

Description

Technical Field

[0001] The invention relates to the technical field of high thermal conductivity copper-based electronic packaging materials, and in particular to a Cu / graphene film layered composite material and a preparation method thereof. Background Art

[0002] With the rapid development of the information age, electronic devices are more closely connected with people's lives. The operating power of various electronic components is getting higher and higher, which will inevitably increase the heat of the circuit, which may cause the failure of electronic components. At the same time, uneven temperature distribution may cause excessive noise. According to literature, for every 10°C increase in the operating temperature of the semiconductor, the probability of device failure will increase by 3 times. At the same time, the use environment of electronic equipment has also become diverse. It is necessary to ensure that electronic products can operate normally under different temperatures and humidities. Electronic packaging has become more important in electronic components.

[0003] Typically, ideal electronic packaging materials have the following properties:

[0004] 1. Lower CTE value. Electronic packaging materials must match the thermal expansion coefficient of semiconductor electronic components. When there is a large difference between the two, internal stress is easily generated at high temperatures, causing chip damage.

[0005] 2. Excellent thermal conductivity. The packaging material is required to be able to conduct the heat generated by the device in time to prevent the chip from failing due to excessive heat.

[0006] 3. Good airtightness. It can effectively prevent the influence of radiation, moisture, and particles, so that electronic equipment can be used normally in some complex environments.

[0007] 4. Have certain strength and toughness. Can provide some support and have good processing performance.

[0008] Currently, the most commonly used electronic packaging materials are ceramics, diamonds, metals, and metal-based composite materials. Although some of them have been widely used in the field of electronic packaging, they can only meet some of the above requirements. For example, Mo and W have low thermal expansion coefficients and good strength, but they are difficult to process, have high density and are expensive, and their thermal conductivity is much worse than that of copper. Al has excellent thermal conductivity, but its thermal expansion coefficient is too large, which limits its further application. In short, there is currently no single material that can fully meet the needs of electronic packaging, and people are beginning to focus on metal-based composite materials.

[0009] Metal matrix composite material has the advantages of components, has metal easy processing, low thermal expansion and high conductivity, and has good wear resistance and corrosion resistance. Cu has excellent thermal conductivity and excellent processing performance. Graphene not only has excellent thermal conductivity in a certain specific orientation, but also has low density. Therefore, Cu / graphene film layered material is expected to become a kind of electronic packaging material with excellent performance, but the wettability between Cu and graphene is poor, and it is easy to crack under the effect of thermal stress. In the present invention, Ti is selected as the transition layer between Cu and graphene to improve the bonding force of layered material. Summary of the invention

[0010] In order to solve the technical problems raised in the background technology, the present invention provides a method for preparing a Cu / graphene thin film layered composite material.

[0011] The present invention is implemented by the following technical scheme: A method for preparing a Cu / graphene thin film layered composite material, characterized in that it comprises the following steps:

[0012] Step 1: Process the copper foil, titanium foil and graphene film into a disc with a diameter of 30 mm, and then use a puncher to punch holes in the disc; in order to remove impurities and oxides on the surface, the punched disc is ultrasonically pickled in a hydrochloric acid solution, then washed with anhydrous ethanol, and dried in a drying oven;

[0013] Step 2: mold the disc obtained in step 1 in the order of Cu-Ti-GN-Ti, and then fill the holes in GN with copper powder;

[0014] Step 3: After the mold in step 2 is pre-pressed by 10 MPa, it is placed in a sintering furnace chamber, the sintering program is set, and sintering is performed to complete the preparation of the layered composite material under vacuum conditions.

[0015] Optionally, in step 1, the thicknesses of the copper foil, titanium foil and graphene film are 100um, 50um and 50um respectively, the diameter of the circular hole on the graphene is 5mm, and the concentration of hydrochloric acid is 20vol%.

[0016] Optionally, the temperature of the drying box is 60° C. and the drying time is 30 minutes.

[0017] Optionally, it is characterized in that a carbon paper separator is required between the material and the mold to facilitate subsequent demoulding, and the particle size of the copper powder is 5-25um.

[0018] Optionally, in the step three, the sintering procedure is: the sample is heated from room temperature to 600°C at a heating rate of 100°C / min, kept warm for 5 minutes, then heated to 900°C at a heating rate of 100°C / min, kept warm for 5 minutes, and then starts to cool down. During the heating stage of 600°C-900°C, the pressure increases from 50MPa to 100MPa. During the cooling stage, before 500°C, the cooling rate is maintained at 10°C / min by controlling the current, and then cooled with the furnace.

[0019] The present invention also provides a Cu / graphene film layered composite material, which is prepared by the above-mentioned preparation method.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] In the present invention, the layered material uses Cu as the skeleton to ensure that the material has a certain strength. Cu and graphene together serve as the heat dissipation body, making the thermal conductivity of the layered material much higher than that of pure copper. At the same time, because the density of graphene is low, only one tenth of that of pure copper, the density of the layered material is reduced, which is suitable for lightweight production.

[0022] In the preparation process of the present invention, Ti between copper and graphene solves the disadvantage of poor wettability between copper and graphene, ensures the connection strength of the material, and avoids the disadvantage of cracking under the action of thermal stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of a layered composite material. The layered material uses Cu as the skeleton, and Cu and graphene together serve as the heat dissipation body, making the thermal conductivity of the layered material much higher than that of pure copper. At the same time, because the density of graphene is low, only one-tenth of that of pure copper, the density of the layered material is reduced, making it suitable for lightweight production;

[0024] Figure 2 This is a schematic diagram of the thermal stress buffer layer of layered materials. At high temperatures, thermal stresses in different directions will be generated in Cu and graphene, which can easily lead to cracking of the Cu / graphene interface. After selecting Ti as the intermediate transition layer, thermal stress in the Ti layer is generated in the opposite direction to that of Cu and graphene, reducing the risk of material cracking;

[0025] Figure 3 This is a microscopic morphology of layered materials. It can be observed that the thickness of the Cu layer is about 100um, and the thickness of the graphene and titanium layers is about 50-90um;

[0026] Figure 4 This is a schematic diagram of the Cu skeleton of layered materials. The copper powder filled in the graphene holes plays a good connecting role and improves the strength of the material. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0028] Embodiment 1:

[0029] The layered composite material in this embodiment is provided with an intermediate transition layer Ti.

[0030] The preparation method of the layered composite material in this embodiment is as follows:

[0031] The copper foil, Ti foil and graphene film were processed into discs with a diameter of 30 mm, and a hole puncher was used to randomly process holes with a diameter of 5 mm in the graphene film. In order to remove impurities and oxides on the surface, the processed discs were ultrasonically pickled in a 20 vol% hydrochloric acid-alcohol solution. After the pickled discs were washed with anhydrous ethanol, they were dried in a drying oven at 60°C for 30 minutes.

[0032] The dried sample is placed in a graphite mold. Carbon paper is used to separate the material and the mold to facilitate subsequent demolding. At the same time, copper powder with a particle size of 5-25um is used to fill the holes in the GN.

[0033] The assembled mold is pre-pressed at a pressure of 10MPa. After the mold is loaded into the sintering furnace chamber, the vacuum state is maintained and the pressure is adjusted to 50MPa. The sintering program is set so that the sample is sintered and formed under the action of current and pressure. The sintering program is: the sample is heated from room temperature to 600℃ at a heating rate of 100℃ / min, kept warm for 5min, then heated to 900℃ at a heating rate of 100℃ / min, kept warm for 5min, and then started to cool down. During the heating stage of 600℃-900℃, the pressure increases from 50MPa to 100MPa. In the cooling stage, before 500℃, the cooling rate is maintained at 10℃ / min by controlling the current size, and then cooled with the furnace.

[0034] Selecting Ti as the intermediate transition layer plays multiple roles: first, Ti can form a solid solution with Cu and react with graphene film to generate TiC, which greatly improves the bonding strength of the interface; second, Ti can improve the bonding strength between Cu and graphene film while acting as a transition layer, alleviating stress cracking caused by the difference in high-temperature thermal expansion coefficients of Cu and graphene film, improving the interlayer bonding strength while reducing the cracking risk of the Cu / graphene layered composite material.

[0035] Comparative Example 1:

[0036] The layered composite material in this embodiment does not have an intermediate transition layer Ti.

[0037] The preparation method of the layered composite material in this embodiment is as follows:

[0038] The copper foil and graphene film were processed into discs with a diameter of 30 mm, and holes with a diameter of 5 mm were randomly processed in the graphene film using a puncher. In order to remove impurities and oxides on the surface, the processed discs were ultrasonically pickled in a 20 vol% hydrochloric acid-alcohol solution. After the pickled discs were washed with anhydrous ethanol, they were dried in a drying oven at 60°C for 30 minutes.

[0039] The dried sample is placed in a graphite mold. Carbon paper is used to separate the material and the mold to facilitate subsequent demolding. At the same time, copper powder with a particle size of 5-25um is used to fill the holes in the graphene.

[0040] The assembled mold is pre-pressed at a pressure of 10MPa. After the mold is loaded into the sintering furnace chamber, the vacuum state is maintained and the pressure is adjusted to 50MPa. The sintering program is set so that the sample is sintered and formed under the action of current and pressure. The sintering program is: the sample is heated from room temperature to 600℃ at a heating rate of 100℃ / min, kept warm for 5min, then heated to 900℃ at a heating rate of 100℃ / min, kept warm for 5min, and then started to cool down. During the heating stage of 600℃-900℃, the pressure increases from 50MPa to 100MPa. In the cooling stage, before 500℃, the cooling rate is maintained at 10℃ / min by controlling the current size, and then cooled with the furnace.

[0041] According to the technical solution disclosed in comparative example 1 in which the intermediate transition layer Ti is not provided, the obtained layered composite material exhibits cracking after one heat treatment. However, according to the technical solution disclosed in embodiment 1 in which the intermediate transition layer is provided, the obtained layered composite material has relatively good strength, and the thermal conductivity of the material is measured to be 635W / (m*K).

[0042] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for preparing a Cu / graphene thin film layered composite material, characterized in that: The steps include: Step 1: Process the copper foil, titanium foil and graphene film into a disc with a diameter of 30 mm, and then use a puncher to punch holes in the disc; in order to remove impurities and oxides on the surface, the punched disc is ultrasonically pickled in a hydrochloric acid solution, then washed with anhydrous ethanol, and dried in a drying oven; Step 2: mold the disc obtained in step 1 in the order of Cu-Ti-GN-Ti, and then fill the holes in GN with copper powder; Step 3: After the mold in step 2 is pre-pressed by 10 MPa in advance, it is placed in a sintering furnace chamber, the sintering program is set, and sintering is performed to complete the preparation of the layered composite material under vacuum conditions; In step 1, the thicknesses of the copper foil, titanium foil, and graphene film are 100 um, 50 um, and 50 um, respectively; the diameter of the circular hole on the graphene is 5 mm; the concentration of hydrochloric acid is 20 vol%; The drying oven temperature is 60°C and the drying time is 30 minutes; Carbon paper is required to separate the material from the mold to facilitate subsequent demoulding, and the particle size of the copper powder is 5-25um; In the step three, the sintering procedure is: the sample is heated from room temperature to 600°C at a heating rate of 100°C / min, kept warm for 5 minutes, then heated to 900°C at a heating rate of 100°C / min, kept warm for 5 minutes, and then started to cool. During the heating stage of 600°C-900°C, the pressure is increased from 50MPa to 100MPa. During the cooling stage, before 500°C, the cooling rate is maintained at 10°C / min by controlling the current size, and then cooled with the furnace.

2. A Cu / graphene thin film layered composite material, characterized in that: It is prepared by the preparation method as claimed in claim 1.

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