阅读说明：本技术 一种碳纳米管/纳米银焊膏导热材料及其制备方法 (Carbon nano tube/nano silver soldering paste heat conduction material and preparation method thereof ) 是由 张平 许晖 周漫 姜雄 杨培培 杨道国 于 2019-09-11 设计创作，主要内容包括：本发明公开了一种碳纳米管/纳米银焊膏导热复合材料及其制备方法,以表面镀银的碳纳米管作为增强相,将其掺杂在纳米银焊膏中,使纳米银颗粒有效均匀地吸附在表面镀银的碳纳米管上,该导热材料具有较高的导热率,较高的粘接强度和剪切强度等优点,且本发明克服了碳纳米管与纳米银颗粒之间较弱的界面结合能力,制备工艺简单。(The invention discloses a carbon nano tube/nano silver soldering paste heat conduction composite material and a preparation method thereof, wherein a carbon nano tube with a silver-plated surface is used as a reinforcing phase and is doped in the nano silver soldering paste, so that nano silver particles are effectively and uniformly adsorbed on the carbon nano tube with the silver-plated surface.)

1. A carbon nano tube/nano silver soldering paste heat conduction material is characterized in that a carbon nano tube with a silver-plated surface is used as a reinforcing phase and is doped in a nano silver soldering paste.

2. A preparation method of a carbon nano tube/nano silver soldering paste heat conduction material is characterized by comprising the following steps:

(1) Sequentially carrying out oxidation treatment and activation treatment on the carbon nano tube particles;

(2) Carrying out chemical silver plating treatment on the activated carbon nano tube particles to obtain chemical silver plated carbon nano tube particles;

(3) Adding the nano-silver particles into an absolute ethyl alcohol solvent, adding a surfactant, uniformly oscillating by ultrasonic waves, and volatilizing in vacuum to obtain nano-silver slurry;

(4) Mixing the chemical silver-plated carbon nano tube particles with the nano silver slurry according to a certain proportion, stirring until the particles are uniformly dispersed, and washing and separating to obtain the carbon nano tube/nano silver soldering paste.

3. The method of claim 2, wherein in the step (1), the carbon nanotube particles are added to a mixed solution of 0.35mol/L K ₂ Cr ₂ O ₇ and 0.25mol/L HCl, the mixture is boiled at 70 ℃ for 8 hours to be oxidized, and the oxidized carbon nanotubes are put into 0.024mol/L PdCl ₂ solution to be activated, and the carbon nanotube particles are repeatedly washed until neutral.

4. The method of claim 2 or 3, wherein the carbon nanotubes are multi-walled carbon nanotubes having a particle size of 80 ~ 120 nm.

5. The method according to claim 2, wherein in the step (2), the activated carbon nanotube particles are added into silver ammonia solution, stirred, the pH value of the solution is adjusted, formaldehyde solution is added dropwise at different rates until the redox reaction is finished, and the precipitate is washed and dried to obtain the chemical silvered carbon nanotube particles.

6. The method of claim 5, wherein 0.06mol/L of silver nitrate solution is added dropwise to 25wt% aqueous ammonia to obtain a silver ammonia solution.

7. The method of claim 5, wherein the pH of the solution is adjusted to 7.5 ~ 9.5.5 with stirring at 20 ℃ ~ 60 ℃ and 25ml/L formaldehyde solution is added dropwise at a rate of 2 ~ 5 ml/min.

8. The method according to claim 2, wherein in step (3), the surfactant is composed of polyvinylpyrrolidone, tween 80 and terpineol in a mass ratio of 1 ~ 5: 2: 3.

9. The method of claim 2, wherein in step (3), the surfactant is added and the mixture is subjected to ultrasonic oscillation for 30 min.

10. The method according to claim 2, wherein in the step (4), the mass ratio of the electroless silver-plated carbon nanotube particles to the nano-silver paste is 1:30 ~ 40.

Technical Field

the invention relates to the technical field of preparation of composite nano materials, in particular to a carbon nano tube/nano silver soldering paste heat conduction material and a preparation process thereof.

Background

the nano silver soldering paste is prepared by mixing nano silver particles with organic solvents such as a dispersing agent, a bonding agent, a diluting agent and the like through methods such as mechanical stirring, ultrasonic oscillation and the like. And in recent years, electronic packages such as Light Emitting Diodes (LEDs), semiconductor lasers, IGBTs, etc. are increasingly emphasized by their excellent thermal, electrical, mechanical properties and reliability. The effects of high temperature on the reliability, lifetime, stress-strain behavior and creep behavior of electronic products, and temperature cycling caused by frequent switching of power devices, all contribute to product failure. Meanwhile, the bonding layer between the inner parts of the high-power device is taken as a necessary path for heat transmission, which puts higher requirements on the use of bonding materials.

In the prior art, diamond, micron copper and graphene are used as reinforcing phases of the nano silver soldering paste, and although sintering temperature, overall thermal conductivity and the like required in the preparation process of silver paste are improved, the development requirements in the prior art cannot be completely met.

Disclosure of Invention

The invention aims to provide a carbon nano tube/nano silver soldering paste heat conduction material and a preparation process thereof.

In order to solve the technical problems, the technical scheme provided by the invention is as follows: a carbon nano tube/nano silver soldering paste heat conduction material and a preparation method thereof, the carbon nano tube with silver plated on the surface is used as a reinforcing phase, and nano silver particles are effectively and uniformly adsorbed on the carbon nano tube by doping in the nano silver soldering paste to obtain the heat conduction material, comprising the following steps:

(1) Sequentially carrying out oxidation treatment and activation treatment on the carbon nano tube particles;

(2) Carrying out chemical silver plating treatment on the activated carbon nano tube particles to obtain chemical silver plated carbon nano tube particles;

(3) Adding the nano-silver particles into an absolute ethyl alcohol solvent, adding a surfactant, uniformly oscillating by ultrasonic waves, and volatilizing in vacuum to obtain nano-silver slurry;

(4) Mixing the chemical silver-plated carbon nano tube particles with the nano silver slurry according to a certain proportion, stirring until the particles are uniformly dispersed, and washing and separating to obtain the carbon nano tube/nano silver soldering paste.

Further, in the step (1), adding carbon nano tube particles into a mixed solution of 0.35mol/L K ₂ Cr ₂ O ₇ solution and 0.25mol/L HCl solution, boiling at 70 ℃ for 8h for oxidation treatment, wherein the carbon nano tubes are multi-walled carbon nano tubes, the particle size of the carbon nano tubes is 80-120 nm, placing the oxidized carbon nano tubes into 0.024mol/L PdCl ₂ solution for activation treatment, and finally repeatedly cleaning the activated carbon nano tubes with deionized water until the carbon nano tubes are neutral.

Further, in the step (2), the activated carbon nano tube particles are added into silver ammonia solution, stirred, the pH value of the solution is adjusted, formaldehyde solution is dripped at different rates until the oxidation reduction reaction is finished, and the precipitate is washed and dried to obtain the chemical silver-plated carbon nano tube particles.

Further, 0.06mol/L of silver nitrate solution was added dropwise to 25wt% aqueous ammonia to prepare a silver-ammonia solution.

Further, magnetically stirring the mixture in a water bath kettle at the temperature of between 20 and 60 ℃, adjusting the pH value of the solution to between 7.5 and 9.5, and dropwise adding 25ml/L formaldehyde solution at the speed of between 2 and 5 ml/min.

further, in the step (3), the mass ratio of the surfactant to the surfactant is 1-5: 2:3, polyvinylpyrrolidone, tween 80 and terpineol.

Further, in the step (3), a surfactant is added, and ultrasonic oscillation is carried out for 30 min.

Further, in the step (4), the mass ratio of the chemical silver plating carbon nanotube particles to the nano silver paste is 1: 30-40.

Compared with the prior art, the invention has the advantages that:

(1) The invention improves the wettability of the surface of the carbon nano tube by chemical silver plating and improves the interface bonding force between the carbon nano tube and the nano silver particles.

(2) Formaldehyde can be used as a reducing agent, and compared with a common reducing agent, the reducing effect is better, smaller particles can be prepared, and the combination between interfaces is facilitated.

(3) The carbon nano tube/nano silver soldering paste prepared by the invention has high thermal conductivity, high shear strength, good bonding strength and better application prospect; the process flow is simple, and the production period is short.

drawings

fig. 1 is a process flow diagram of the carbon nanotube/nano silver solder paste heat conduction material according to the present invention.

Detailed Description

the invention will be further elucidated with reference to the drawings and examples, without however being limited thereto.

With reference to fig. 1, the preparation method of the carbon nanotube/silver solder paste heat conduction material of the present invention comprises the following steps:

(1) Adding multi-wall carbon nano-tube particles with the particle size of 80-120 nm into a mixed solution of 0.35mol/L K ₂ Cr ₂ O ₇ solution and 0.25mol/L HCl solution, boiling at 70 ℃ for 8 hours for oxidation treatment, then placing the carbon nano-tubes subjected to oxidation treatment in 0.024mol/L PdCl ₂ solution for activation treatment, and finally repeatedly cleaning the carbon nano-tubes subjected to activation treatment by deionized water until the carbon nano-tubes are neutral;

(2) And carrying out chemical silver plating treatment on the nano carbon nano tube particles. Dropwise adding 0.06mol/L silver nitrate solution into 25wt% of analytically pure ammonia water at normal temperature to prepare silver ammonia solution, then adding activated carbon nanotube particles into the silver ammonia solution, magnetically stirring in a water bath kettle at 20-60 ℃, adjusting the pH value of the solution to 7.5-9.5, finally dropwise adding 25ml/L formaldehyde solution into the solution at the speed of 2-5 ml/min as a reducing agent until the redox reaction is finished, and washing and drying the precipitate to obtain silver-plated carbon nanotube particles;

(3) And preparing nano silver paste. Adding nano silver particles into an absolute ethyl alcohol solvent at normal temperature, and mixing polyvinylpyrrolidone, tween 80 and terpineol according to a mass ratio of 1-5: 2:3, then oscillating for 30min by ultrasonic waves, and then evaporating in vacuum to obtain the nano-silver slurry with high thermal conductivity.

(4) Preparing the nano carbon nano tube/nano silver soldering paste. At normal temperature, chemically plating silver on the carbon nano tube particles and nano silver slurry according to the mass ratio of 1: and 30-40, stirring until the particles are uniformly dispersed, and washing and separating to obtain the carbon nano tube/nano silver soldering paste.

The inventor tries to prepare a carbon nanotube-doped nano-silver solder paste heat conduction material, so that nano-silver particles are expected to be well combined with carbon nanotube particles, the sintering temperature of the nano-silver solder paste is reduced, the heat conductivity is improved, and a unique multifunctional chip interconnection material is developed. However, in the present application, the inventors surprisingly found that when the carbon nanotube is used as the reinforcing phase, the interface bonding force between the carbon nanotube and the nano-silver particle is poor, which results in low thermal conductivity and shear strength, and the addition of the carbon nanotube particle with silver coated on the surface in the nano-silver solder paste effectively improves the interface bonding capability between the nano-silver particle and the carbon nanotube particle, forms a phonon-electron heat transfer path, and improves the thermal conductivity and shear strength.