CN111375774B - Preparation method of graphite-copper-molybdenum-based composite material for electronic packaging - Google Patents

Abstract

The invention discloses a preparation method of a graphite-copper-molybdenum-based composite material for electronic packaging, which comprises the following steps: 1. sequentially carrying out high-temperature oxidation and high-energy ball milling treatment on the electrolytic copper powder to obtain copper oxide powder; 2. ball-milling and mixing copper oxide powder, flake graphite and molybdenum powder to obtain composite powder; 3. carrying out reduction treatment on the composite powder to obtain graphite loaded copper nanoparticle composite powder; 4. and carrying out vacuum hot-pressing sintering on the graphite-loaded copper nanoparticle composite powder to obtain the graphite-copper-molybdenum-based composite material. According to the invention, the electrolytic copper powder is oxidized into copper oxide powder, and is mixed with other component powder and then reduced to construct a graphite loaded copper nanoparticle structure, so that graphite is uniformly dispersed in the copper powder, the graphite agglomeration phenomenon is effectively reduced, the problem that the graphite is difficult to uniformly disperse in a copper matrix due to non-wetting between the graphite and the copper is solved, and the interface bonding is strengthened, so that the graphite-copper-molybdenum-based composite material with excellent mechanical property, high thermal conductivity and low thermal expansion coefficient is obtained.

Description

A preparation method of graphite-copper-molybdenum-based composite material for electronic packaging

technical field

The invention belongs to the technical field of material preparation, and in particular relates to a method for preparing a graphite-copper-molybdenum-based composite material for electronic packaging.

Background technique

With the rapid development of the modern electronic information industry, the design of electronic components is becoming more and more miniaturized and complicated, and more and more heat is generated. The heat dissipation problem has become one of the factors to measure the reliability of electronic products. If the heat dissipation is not up to standard, it will seriously affect the function of electronic components, and even cause the machine not to work normally. Therefore, the performance of electronic packaging materials needs to meet higher requirements.

Copper-molybdenum composite materials are the first generation of thermal management materials, and their thermal conductivity ranges from 184W·m ^-1 K ^-1 to 197W·m ^-1 K ^-1 , which is difficult to meet the performance requirements of electronic packaging materials. Graphite has a relatively low coefficient of thermal expansion and a thermal conductivity as high as 10000W·m ^-1 K ^-1 to 2000W·m ^-1 K ^-1 in the sheet direction, and is an excellent reinforcing phase for metal-based electronic packaging materials. Introducing graphite into copper-molybdenum materials to prepare graphite-copper-molybdenum-based composites is expected to obtain excellent mechanical properties, high thermal conductivity and low thermal expansion coefficient. However, there is no wetting between graphite and copper, and it is difficult to disperse graphite uniformly in the copper matrix. How to solve these problems is the key to improving the performance of composite materials.

Contents of the invention

The technical problem to be solved by the present invention is to provide a preparation method of graphite-copper-molybdenum-based composite material for electronic packaging in view of the above-mentioned deficiencies in the prior art. In this method, electrolytic copper powder is oxidized into copper oxide powder and mixed with other component powders before reduction to construct a graphite-supported copper nanoparticle structure, and the graphite is evenly dispersed in the copper powder, which effectively reduces the graphite agglomeration phenomenon and solves the problem of graphite agglomeration. The problem of graphite being difficult to disperse evenly in the copper matrix caused by non-wetting with copper, and at the same time strengthening the interfacial bonding, obtains a graphite-copper-molybdenum-based composite material with excellent mechanical properties, high thermal conductivity and low thermal expansion coefficient.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: a preparation method of graphite-copper-molybdenum-based composite material for electronic packaging, characterized in that the method comprises the following steps:

Step 1. Prepare copper oxide powder: oxidize the electrolytic copper powder at high temperature, and then perform high-energy ball milling to obtain copper oxide powder; the copper oxide powder is copper powder coated with a copper oxide film on the surface;

Step 2, preparing the composite powder: ball milling and mixing the copper oxide powder, flake graphite and molybdenum powder obtained in the step 1 according to the mass ratio of 44.5: (2.25-18): (5.1-51) to obtain the composite powder;

Step 3, preparing graphite-loaded copper nanoparticle composite powder: placing the composite powder obtained in step 2 in a tube furnace, and performing reduction treatment under reducing atmosphere conditions to obtain graphite-loaded copper nanoparticle composite powder;

Step 4. Preparation of graphite-copper-molybdenum-based composite material: The graphite-loaded copper nanoparticle composite powder obtained in step 3 is vacuum hot-pressed and sintered to obtain a graphite-copper-molybdenum-based composite material.

Due to the good plasticity of copper powder, high-energy ball milling will cause the copper powder to form a lamellar structure, which fails to achieve the purpose of refinement. The present invention oxidizes the electrolytic copper powder and refines it by high-energy ball milling to obtain copper oxide powder, that is, copper powder coated with a copper oxide film on the surface. During the mixing process, it is not easy to form flakes and is further refined to form a uniform mixed powder. After reduction, copper nanoparticles are formed and attached to the graphite to obtain graphite-loaded copper nanoparticle composite powder, so that the graphite is evenly dispersed in the copper powder. It effectively reduces the graphite agglomeration phenomenon, and solves the problem that graphite is difficult to disperse evenly in the copper matrix caused by non-wetting between graphite and copper. At the same time, due to the presence of copper nanoparticles between the graphite, the interfacial bonding force between copper and graphite is stronger than that between graphite, that is, the interfacial bonding is strengthened, so that excellent mechanical properties can be obtained by vacuum hot pressing sintering. , graphite-copper-molybdenum-based composites with high thermal conductivity and low thermal expansion coefficient, greatly improving the performance of graphite-copper-molybdenum-based composites.

The above-mentioned preparation method of graphite-copper-molybdenum-based composite material for electronic packaging is characterized in that the oxidation temperature in step 1 is 250°C to 400°C, and the ball-to-material ratio used in the high-energy ball milling treatment is (5 ~20): 1. The ball milling speed is 400rpm~500rpm.

The above-mentioned preparation method of graphite-copper-molybdenum-based composite material for electronic packaging is characterized in that, in step 2, the rotating speed of ball milling and mixing is 150rpm-250rpm, and the ball milling time is 2h-4h.

The above-mentioned method for preparing graphite-copper-molybdenum-based composite materials for electronic packaging is characterized in that the temperature of the reduction treatment in step 3 is 350°C-450°C, and the time is 2h-4h.

The above-mentioned method for preparing graphite-copper-molybdenum-based composite materials for electronic packaging is characterized in that the temperature of vacuum hot-pressing sintering in step 4 is 700°C to 1050°C, the degree of vacuum is lower than 10 ^-3 Pa, and the heat preservation The time is 5min~30min, and the pressure is 30MPa~160MPa.

Compared with the prior art, the present invention has the following advantages:

1. The present invention oxidizes electrolytic copper powder into copper oxide powder and mixes it with other component powders and then reduces it to construct a graphite-loaded copper nanoparticle structure, so that graphite is evenly dispersed in copper powder, effectively reducing the phenomenon of graphite agglomeration, and solving the problem of Solved the problem of weak interface binding force.

2. In the present invention, graphite is evenly dispersed in copper powder, which strengthens interfacial bonding, thereby obtaining a graphite-copper-molybdenum-based composite material with excellent mechanical properties, high thermal conductivity and low thermal expansion coefficient, which greatly improves the graphite-copper-molybdenum-based composite material. performance.

3. The raw material of the present invention has good processability, simple process and low raw material cost, and is suitable for large-scale production.

The technical solutions of the present invention will be described in further detail below with reference to the drawings and embodiments.

Description of drawings

Figure 1 is a SEM image of the composite powder prepared in Example 1 of the present invention.

FIG. 2 is an SEM image of graphite-supported copper nanoparticle composite powder prepared in Example 1 of the present invention.

Detailed ways

Example 1

This embodiment includes the following steps:

Step 1. Preparation of copper oxide powder: 200g of electrolytic copper powder with a mass purity of 99.9% is placed in a blast drying oven, oxidized at 250°C for 5h, then mixed with 60mL of ethanol, subjected to high-energy ball milling for 4h, and vacuum-dried for 24h to obtain Copper oxide powder; the ball-to-material ratio used in the high-energy ball milling process is 6:1, and the ball milling speed is 450rpm; the copper oxide powder is a copper powder coated with a copper oxide film on the surface;

Step 2, preparing composite powder: 44.5g of copper oxide powder obtained in step 1, 4.5g of flake graphite and 30.6g of molybdenum powder were ball milled and mixed for 3 hours to obtain a composite powder; the speed of ball milling and mixing was 250rpm;

Step 3. Preparation of graphite-loaded copper nanoparticle composite powder: the composite powder obtained in step 2 is placed in a tube furnace, and reduced under the condition of a hydrogen-argon mixed atmosphere with a hydrogen volume content of 8%, to obtain graphite-loaded copper nanoparticle Granular composite powder; the temperature of the reduction treatment is 400°C, and the time is 2h;

Step 4, prepare graphite-copper-molybdenum-based composite material: the graphite-loaded copper nanoparticle composite powder obtained in step 3 is vacuum hot-pressed and sintered to obtain a graphite-copper-molybdenum-based composite material; the temperature of the vacuum hot-pressed sintering is 800 ℃, the vacuum degree is lower than 10 ^-3 Pa, the holding time is 5 minutes, and the pressure is 40MPa.

After testing, the density of the graphite-copper-molybdenum-based composite material prepared in this embodiment is 7.6 g/cm ³ .

Fig. 1 is the SEM image of the composite powder prepared in this example, as can be seen from Fig. 1, under the action of oxidation, high-energy ball milling and ball milling mixed treatment, the copper oxide powder is refined, the size of flake graphite becomes smaller, and some The refined copper oxide powder is covered on flake graphite.

Fig. 2 is the SEM picture of the graphite-supported copper nanoparticle composite powder prepared by the present embodiment. As can be seen from Fig. 2, after the reduction, the surface of the flake graphite is loaded with copper nanoparticles, which inhibits the agglomeration of the flake graphite, and the flake graphite is in the uniformly dispersed in the copper matrix.

The bending strength and longitudinal thermal conductivity of the graphite-copper-molybdenum-based composite material prepared in this example were tested, and compared with the graphite/copper-based composite material in the prior art, the results are shown in Table 1 below.

Table 1 The flexural strength and longitudinal thermal conductivity of the graphite-copper-molybdenum-based composite material prepared in Example 1 and the graphite/copper-based composite material in the prior art

"-" in Table 1 indicates that there is no such content data.

Document 1: Shubin Ren, "The influence of matrix alloy on the microstructure and properties of(flake graphite+diamond)/Cu composites by hot pressing", Journal of Alloys and Compounds 652(2015) 351-357.

Document 2: Jianhao Chen, "Properties and microstructure of nickel-coatedgraphite flakes/copper composites fabricated by spark plasma sintering", Carbon 121(2017) 25-34.

Document 3: Qianyue Cui, "Ultrahigh thermal conductivity copper/graphitemembrane composites prepared by tape casting with hot-pressing sintering", Materials Letters 231(2018) 60–63.

It can be seen from Table 1 that the bending strength of the graphite-copper-molybdenum-based composite material prepared in this example is nearly twice that of the 20% graphite-20% diamond-copper-based composite material in Document 1, but the longitudinal thermal conductivity is higher than that of the document 1 is slightly lower; the bending strength of the graphite-copper-molybdenum-based composite material prepared in this example is almost the same as that of the 20% GF/Cu composite material in Document 2, and the longitudinal thermal conductivity is almost the same as that of the 20% GM/Cu composite material in Document 3 3 times; compared with the graphite/copper-based composite material in the prior art, it can be seen that the preparation method of the present invention effectively reduces the graphite agglomeration phenomenon, and solves the difficulty of graphite in the copper matrix caused by non-wetting between graphite and copper. The problem of uniform dispersion, and at the same time strengthening the interfacial bonding, improves the mechanical properties and longitudinal thermal conductivity of graphite-copper-molybdenum-based composites.

Example 2

This embodiment includes the following steps:

Step 1. Preparation of copper oxide powder: 200g of electrolytic copper powder with a mass purity of 99.9% was placed in a blast drying oven, oxidized at 300°C for 5h, then mixed with 60mL of ethanol, subjected to high-energy ball milling for 4h, and dried in vacuum for 24h to obtain Copper oxide powder; the ball-to-material ratio used in the high-energy ball milling process is 5:1, and the ball milling speed is 400rpm; the copper oxide powder is a copper powder coated with a copper oxide film on the surface;

Step 2, preparing composite powder: 44.5g of copper oxide powder obtained in step 1, 18g of flake graphite and 5.1g of molybdenum powder were ball milled and mixed for 2 hours to obtain a composite powder; the speed of ball milling and mixing was 150rpm;

Step 3. Preparation of graphite-loaded copper nanoparticle composite powder: the composite powder obtained in step 2 is placed in a tube furnace, and reduced under the condition of a hydrogen-argon mixed atmosphere with a hydrogen volume content of 8%, to obtain graphite-loaded copper nanoparticle Granular composite powder; the temperature of the reduction treatment is 350°C, and the time is 2.5h;

Step 4, prepare graphite-copper-molybdenum-based composite material: the graphite-loaded copper nanoparticle composite powder obtained in step 3 is subjected to vacuum hot-pressing sintering to obtain graphite-copper-molybdenum-based composite material; the temperature of the vacuum hot-pressing sintering is 700 ℃, the vacuum degree is lower than 10 ^-3 Pa, the holding time is 15min, and the pressure is 30MPa.

Example 3

This embodiment includes the following steps:

Step 1. Preparation of copper oxide powder: 200g of electrolytic copper powder with a mass purity of 99.9% was placed in a resistance furnace, oxidized at 400°C for 5h, then mixed with 60mL of ethanol, subjected to high-energy ball milling for 4h, and vacuum-dried for 24h to obtain copper oxide powder; the ball-to-material ratio used in the high-energy ball milling process is 20:1, and the ball milling speed is 500rpm; the copper oxide powder is the copper powder coated with a copper oxide film on the surface;

Step 2, preparing composite powder: 44.5g of copper oxide powder obtained in step 1, 2.25g of flake graphite and 51g of molybdenum powder were ball milled and mixed for 4 hours to obtain a composite powder; the speed of ball milling and mixing was 200rpm;

Step 3. Preparation of graphite-loaded copper nanoparticle composite powder: the composite powder obtained in step 2 is placed in a tube furnace, and reduced under the condition of a hydrogen-argon mixed atmosphere with a hydrogen volume content of 8%, to obtain graphite-loaded copper nanoparticle Granular composite powder; the temperature of the reduction treatment is 450°C, and the time is 4h;

Step 4, prepare graphite-copper-molybdenum-based composite material: the graphite-loaded copper nanoparticle composite powder obtained in step 3 is vacuum hot-pressed and sintered to obtain a graphite-copper-molybdenum-based composite material; the temperature of the vacuum hot-pressed sintering is 1050 ℃, the vacuum degree is lower than 10 ^-3 Pa, the holding time is 30min, and the pressure is 160MPa.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any way. All simple modifications, changes and equivalent changes made to the above embodiments according to the technical essence of the invention still belong to the protection scope of the technical solution of the invention.

Claims (3)

1. A preparation method of a graphite-copper-molybdenum-based composite material for electronic packaging is characterized by comprising the following steps:

step one, preparing copper oxide powder: oxidizing electrolytic copper powder at high temperature, and then carrying out high-energy ball milling treatment to obtain copper oxide powder; the copper oxide powder is copper powder with a copper oxide film coated on the surface; the temperature of the oxidation is 250-400 ℃, and the ball-to-feed ratio adopted by the high-energy ball milling treatment is (5-20): 1, the ball milling speed is 400rpm to 500rpm;

step two, preparing composite powder: mixing the copper oxide powder, the crystalline flake graphite and the molybdenum powder obtained in the step one according to a ratio of 44.5: (2.25 to 18): (5.1-51) performing ball milling and mixing to obtain composite powder; the rotation speed of ball milling mixing is 150rpm to 250rpm, and the ball milling time is 2h to 4h;

step three, preparing graphite loaded copper nanoparticle composite powder: placing the composite powder obtained in the step two in a tubular furnace, and carrying out reduction treatment under the reducing atmosphere condition to obtain graphite loaded copper nanoparticle composite powder;

step four, preparing the graphite-copper-molybdenum-based composite material: and (3) carrying out vacuum hot-pressing sintering on the graphite-loaded copper nanoparticle composite powder obtained in the third step to obtain the graphite-copper-molybdenum-based composite material.

2. The preparation method of the graphite-copper-molybdenum-based composite material for electronic packaging, according to claim 1, characterized in that the temperature of the reduction treatment in the third step is 350 ℃ to 450 ℃ and the time is 2h to 4h.

3. The method for preparing the graphite-copper-molybdenum-based composite material for electronic packaging according to claim 1, wherein the step four is performedThe temperature of the vacuum hot-pressing sintering is 700-1050 ℃, and the vacuum degree is lower than 10 ^-3 Pa, the heat preservation time is 5min to 30min, and the pressure is 30MPa to 160MPa.

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