WO2020119756A1

WO2020119756A1 - Thermal interface material and preparation method therefor

Info

Publication number: WO2020119756A1
Application number: PCT/CN2019/124829
Authority: WO
Inventors: 孙蓉; 任琳琳; 曾小亮; 许建斌; 汪正平
Original assignee: 中国科学院深圳先进技术研究院
Priority date: 2018-12-14
Filing date: 2019-12-12
Publication date: 2020-06-18
Also published as: CN109651761B; CN109651761A

Abstract

Disclosed in the present invention are a thermal interface material and a preparation method therefor. The preparation method for the thermal interface material comprises the steps: S1. stirring and uniformly mixing spherical boron nitride, a thermosetting resin, a curing agent, a catalyst, and a coupling agent to acquire a mixed slurry; and S2. heat-curing the mixed slurry to obtain a thermal interface material. Also disclosed in the present invention is a thermal interface material, comprising a polymer matrix and spherical boron nitride uniformly filling the polymer matrix. In the present invention, spherical boron nitride is used to fill the resin, increasing the amount of boron nitride filling the resin, and thereby increasing the thermal conductivity coefficient of the thermal interface material; in addition, the viscosity of the thermal interface material is reduced, increasing the operability of the thermal interface material. The preparation method of the present invention is simple and easy to implement, the cost of the raw materials is low, and the prepared thermal interface material has a high thermal conductivity coefficient and can be used in the field of heat dissipation for high-density electronic devices.

Description

Thermal interface material and preparation method thereof

Technical field

The invention belongs to the field of heat dissipation of electronic devices, in particular to a thermal interface material and a preparation method thereof.

Background technique

With the development of electronic devices toward miniaturization and miniaturization, and the integration of electronic chips is getting higher and higher, the working efficiency and reliability of electronic devices are increasingly dependent on the solution of heat dissipation problems, so the heat dissipation of electronic packaging has become more and more important. Thermal interface materials are generally applied to solid interfaces between integrated circuits (chips) or microprocessors and heat sinks or heat spreaders, and between heat spreaders and heat spreaders. The thermal conductivity of the thermal interface material directly affects the heat dissipation performance of the chip. Therefore, the development of thermal interface materials is particularly important.

The polymer-based thermal interface material filled with inorganic fillers improves heat transfer performance by filling the polymer matrix with ceramic or metal particles having high thermal conductivity. Polymer thermal interface materials maintain the characteristics of low processing temperature, flexibility and easy operation of polymers, combined with the characteristics of high thermal conductivity of inorganic fillers, and are currently the most commonly used materials for thermal interface materials. Since ceramic particles have the characteristics of high thermal conductivity, good insulation, and strong breakdown voltage resistance, they are currently the most commonly used inorganic fillers. Commonly used ceramic fillers include alumina, aluminum nitride, boron nitride, silicon nitride, and silicon carbide .

Boron nitride has good electrical insulation and has very good oxidation resistance and corrosion resistance. Common boron nitride has a variety of crystal forms such as amorphous, cubic and hexagonal. Hexagonal boron nitride is the most stable crystalline form, with a layered structure similar to graphite, known as "white graphite", and has been widely researched and applied. Due to its superior performance, boron nitride has very good application prospects as a thermally conductive insulating polymer composite material.

However, the currently used boron nitride is generally a sheet structure and its density is strong. When the resin is mixed with it, the friction resistance between the resin and the boron nitride surface increases, resulting in a sharp increase in the viscosity of the resin polymer, generally reaching 600Pa · Above s, it is difficult to highly fill boron nitride, resulting in a maximum boron nitride filling amount of only 35wt%, so the thermal conductivity of the prepared polymer thermal interface materials are all less than 1W/(m·K).

Summary of the invention

In order to solve the above problems of the prior art, such as the limited addition amount of boron nitride filler, the viscosity of the thermal interface material is too large, and the thermal conductivity is low, the present invention from the filling amount, particle size, geometry and filler of boron nitride filler- Considering the interaction between the substrates, a thermal interface material with a spherical boron nitride filling amount of up to 60 wt%, a viscosity of not more than 600 Pa·s and a thermal conductivity of up to 6 W/(m·K) and a preparation method thereof are provided. In order to achieve the above object of the invention, the present invention adopts the following technical solutions:

The invention provides a method for preparing a thermal interface material, which includes the steps of:

S1, 10 to 60 parts by mass of spherical boron nitride, 10 to 50 parts by mass of thermosetting resin, 10 to 50 parts by mass of curing agent, 1 to 5 parts by mass of catalyst, and 1 to 5 parts by mass of coupling agent are carried out Mix to obtain mixed slurry.

S2. Heating and curing the mixed slurry under the conditions of 60° C. to 200° C. for 0.5 h to 6 h to obtain a thermal interface material.

Wherein, the total mass part of the mixed slurry in step S1 is 100.

Optionally, in the step S1, it further includes mixing no more than 10 parts by mass of the diluent together to obtain the mixed slurry.

Optionally, the primary particles of hexagonal boron nitride are sintered to obtain the spherical boron nitride.

Optionally, the particle size of the spherical boron nitride is 5 μm to 200 μm.

Optionally, the thermosetting resin is liquid epoxy resin or silicone resin; the curing agent is at least one of methylhexahydrophthalic anhydride, ethylenediamine, triethylenetetramine, and m-phenylenediamine; The catalyst is at least one of 2-ethyl-4-methylimidazole, N,N-dimethylbenzylamine and tri-(dimethylaminomethyl)phenol; the coupling agent is a silane coupling agent , At least one of titanate coupling agent, aluminate coupling agent and bimetallic coupling agent.

Optionally, the diluent is a glycidyl ether compound.

The invention also provides a thermal interface material, which includes a polymer matrix and spherical boron nitride uniformly filled in the polymer matrix.

Optionally, the spherical boron nitride is spherical boron nitride obtained by sintering primary hexagonal boron nitride particles.

Optionally, the filling amount of the spherical boron nitride in the thermal interface material is not less than 20wt%, so that the thermal conductivity of the thermal interface material is not less than 2.0W/(m·K).

Optionally, the filling amount of the spherical boron nitride in the thermal interface material is not less than 35wt% and not more than 60wt%, so that the viscosity of the thermal interface material is not less than 65Pa·s and not more than 600Pa· s. The thermal conductivity is not lower than 2.8W/(m·K) and not higher than 6W/(m·K).

Optionally, the filling amount of spherical boron nitride in the thermal interface material is not less than 10% and not more than 35% by weight, so that the viscosity of the thermal interface material is not more than 65 Pa·s and the thermal conductivity is not less than 0.5W/(m·K) and not higher than 2.8W/(m·K).

The invention adopts spherical boron nitride to fill the polymer matrix, reduces the friction resistance between the surface of the spherical boron nitride and the polymer matrix, and increases the filling amount of the spherical boron nitride in the polymer matrix, thereby improving the thermal conductivity of the thermal interface material Coefficient; at the same time, the viscosity of the thermal interface material is reduced, and the operability of the thermal interface material is improved. The invention overcomes the defects of the prior art that the thermal interface material has a limited amount of boron nitride added, a too large viscosity and a low thermal conductivity.

BRIEF DESCRIPTION

The above and other aspects, features, and advantages of embodiments of the present invention will become more clear through the following description in conjunction with the drawings. In the drawings:

1 is a schematic diagram of the structure of the thermal interface material of the present invention:

In the figure, 10 is the polymer matrix, 20 is spherical boron nitride;

2 is a schematic diagram of a method for preparing a thermal interface material according to the present invention.

detailed description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention can be implemented in many different forms, and the present invention should not be interpreted as being limited to the specific embodiments set forth herein. Rather, these embodiments are provided to explain the principles of the present invention and its practical application, so that those skilled in the art can understand various embodiments of the present invention and various modifications suitable for particular intended applications.

Referring specifically to FIG. 1, the present invention discloses a thermal interface material. The thermal interface material includes a polymer matrix 10 and a spherical boron nitride 20 uniformly filled in the polymer matrix 10.

More specifically, the above-mentioned spherical boron nitride of the present invention is a spherical boron nitride obtained by sintering hexagonal boron nitride primary particles; thus, compared with the prior art The primary particles of boron are directly polymerized with the resin, the friction resistance of the surface of the spherical boron nitride of the invention and the polymer matrix is greatly reduced, and the internal thermal resistance is also greatly reduced.

Furthermore, in the thermal interface material obtained by the present invention, the spherical boron nitride morphology remains good, and the hexagonal boron nitride primary particles are oriented in different directions, effectively suppressing the anisotropy of the thermal conductivity, thereby further improving the thermal interface material Thermal conductivity.

Optionally, the filling amount of the spherical boron nitride in the thermal interface material can be controlled to not less than 20 wt%, so that the thermal conductivity of the thermal interface material is not less than 2.0 W/(m·K).

More optionally, the filling amount of spherical boron nitride in the thermal interface material can be controlled to not less than 35wt% and not more than 60wt%, so that the viscosity of the thermal interface material is not less than 65Pa·s and not more than 600Pa·s 2. The thermal conductivity is not lower than 2.8W/(m·K) and not higher than 6W/(m·K).

Optionally, the filling amount of spherical boron nitride in the thermal interface material can be controlled to not less than 10% and not more than 35% by weight, so that the viscosity of the thermal interface material is not more than 65Pa·s and the thermal conductivity is not less than 0.5W /(m·K) and not higher than 2.8W/(m·K).

The maximum filling amount of spherical boron nitride of the thermal interface material can be as high as 60wt%, the viscosity does not exceed 600Pa·s, and the maximum thermal conductivity can be as high as 6W/(m·K).

It is worth mentioning that, first of all, in terms of structure, the thermal interface material of the present invention is filled with spherical boron nitride, while the thermal interface material in the prior art is filled with flake boron nitride or boron nitride primary particles Secondly, in terms of performance, compared with the existing thermal interface materials, under the same loading conditions, the thermal interface material of the present invention has a lower viscosity and a higher thermal conductivity. It can be seen that the thermal interface material of the present invention has a lower viscosity and a higher filling amount than the thermal interface material filled with other materials in the prior art, so that the thermal conductivity is also higher, and a better Application effect.

Referring specifically to FIG. 2, the present invention also provides a method for preparing the above thermal interface material, including the following steps:

In step S1, 10 to 60 parts by mass of spherical boron nitride, 10 to 50 parts by mass of thermosetting resin, 10 to 50 parts by mass of curing agent, 1 to 5 parts by mass of catalyst, and 1 to 5 parts by mass of couple The joint agent is mixed to form 100 parts by mass of a mixed slurry.

Specifically, the primary particles of hexagonal boron nitride are sintered to obtain spherical boron nitride.

Alternatively, the particle diameter of the spherical boron nitride used in this step is 5 μm to 200 μm.

In this step, the mixing operation uses a high-speed mixer for mixing, specifically controlling the rotation speed from 800 rpm to 2500 rpm and the mixing time from 0.5 min to 10 min.

More specifically, in this step, the thermosetting resin may be liquid epoxy resin or silicone resin. The liquid epoxy resin is preferably at least one of bisphenol A type liquid epoxy resin, bisphenol F type liquid epoxy resin and alicyclic liquid epoxy resin. The silicone resin is preferably at least one of polymethyl silicone resin, polyethyl silicone resin, polyphenyl silicone resin, and polyphenyl methyl silicone resin.

The curing agent may be at least one of methylhexahydrophthalic anhydride, ethylenediamine, triethylenetetramine, and m-phenylenediamine.

The catalyst may be at least one of 2-ethyl-4-methylimidazole, N,N-dimethylbenzylamine, and tri-(dimethylaminomethyl)phenol.

The coupling agent may be at least one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, and a bimetallic coupling agent. The silane coupling agent is preferably at least one of KH550 coupling agent, KH560 coupling agent and KH570 coupling agent. The coupling agent is added on the one hand to improve the compatibility of the spherical boron nitride and the thermosetting resin, and on the other hand to enhance the interface between the spherical boron nitride and the thermosetting resin, so as to enhance the interpenetrating thermal conduction network.

Alternatively, no more than 10 parts by mass of diluent can be added during the process of obtaining the mixed slurry.

The diluent is preferably a glycidyl ether compound; the glycidyl ether compound is further preferably n-butyl glycidyl ether, diglycidyl ether, 1,4-butanediol diglycidyl ether, polyglycidyl ether and trihydroxy At least one of methyl propane glycidyl ether.

It is worth noting that when the material of the mixed slurry is too viscous and the bubbles are difficult to remove, you can consider removing the bubbles brought in the mixing process by vacuuming or adding an anti-foaming agent. Among them, the defoamer can be modified silicone compound.

In step S2, the mixed slurry is heated and solidified at a temperature of 60°C to 200°C for 0.5h to 6h to obtain a thermal interface material.

Alternatively, an oven may be used to provide energy for the curing process of the thermosetting resin. Of course, other heating methods such as infrared heating may also be used.

It is worth noting that the spherical boron nitride of the present invention has good sphericity, large particle size range, and high mechanical strength. During the mixing process, the friction resistance with the polymer matrix is small, it is not easy to be damaged, and it has a high morphology. Retention. After mixing spherical boron nitride with a particle size of 200 μm and thermosetting resin and other materials at 2000 rpm for 10 min, the spherical boron nitride can still withstand the shearing force experienced during the mixing.

Therefore, the thermal interface material of the present invention achieves a spherical boron nitride filling amount of up to 60 wt%, a viscosity not exceeding 600 Pa·s, and a thermal conductivity of up to 6 W/(m·K through the polymer matrix and the spherical boron nitride filled inside it ), compared with the general thermal interface materials in the prior art, the amount of boron nitride added increases, the viscosity decreases and the thermal conductivity increases.

It is worth noting that, in general, the measurement methods of thermal conductivity are divided into two categories: steady-state method and unsteady-state method. The measurement range of the non-steady state method is 0.1W/(m·K)～2000W/(m·K), and the commonly used non-steady state method is the laser flash method. However, for low thermal conductivity materials, it is not suitable to use the laser pulse method for testing, because the laser flash method usually uses a very thin sample or a high-power laser pulse. If the sample preparation is very thin, the measurement results will be more discrete and the measured results will not be representative; the high-power laser pulse will generate a lot of heat, and the decomposition temperature and melting point of the low thermal conductivity material are not high In the case of using high-power laser pulses, the sample may cause chemical reaction or decomposition reaction, and the measured thermal conductivity is not the true thermal conductivity of the material to be tested. The steady state method does not cause the above problems when measuring the thermal conductivity of low thermal conductivity materials. The thermal interface material of the present invention belongs to a low thermal conductivity material. Therefore, in order to obtain more reliable result data for the thermal conductivity measurement of the thermal interface material of the present invention, the present invention selects the steady-state heat flow method for thermal conductivity measurement.

The following examples further illustrate the above-mentioned thermal interface material and its preparation method of the present invention, but the present invention is not limited thereto. The following embodiments are only specific examples of the above-mentioned thermal interface material and its preparation method of the present invention.

Example one

Take 10 parts by mass of spherical boron nitride with a particle size of 5 μm, 50 parts by mass of bisphenol A liquid epoxy resin, 33 parts by mass of methylhexahydrophthalic anhydride curing agent, and 1 part by mass of 2-ethyl-4 -A methylimidazole catalyst, 1 part by mass of KH560 silane coupling agent, and 5 parts by mass of n-butyl glycidyl ether are mixed, and the above materials are mixed for 10 minutes at a rotation speed of 800 rpm to obtain a uniformly mixed mixture. The obtained mixture was placed in an oven, and the above mixture was cured under normal pressure at 200°C for 0.5 h to obtain a thermal interface material.

The thermal interface material prepared according to the above preparation method includes a polymer matrix and spherical boron nitride uniformly filled inside the polymer matrix, wherein the filling amount of spherical boron nitride is 10 wt%.

The viscosity of the thermal interface material of this example is 2 Pa·s. Under normal temperature and 20 psi pressure conditions, the steady-state heat flow method was used to determine the thermal conductivity of the thermal interface material was 0.5 W/(m·K).

Example 2

Take 60 parts by mass of spherical boron nitride with a particle size of 200 μm, 10 parts by mass of bisphenol F-type liquid epoxy resin, 10 parts by mass of triethylenetetramine curing agent, and 5 parts by mass of N,N-dimethyl A benzylamine catalyst, 5 parts by mass of KH550 silane coupling agent, and 10 parts by mass of 1,4-butanediol diglycidyl ether were mixed, and the above materials were mixed for 5 minutes at a speed of 1500 rpm to obtain a uniformly mixed mixture . The obtained mixture was placed in an oven, and the mixture was cured under normal pressure at 60°C for 6 hours to obtain a thermal interface material.

The thermal interface material prepared according to the above preparation method includes a polymer matrix and spherical boron nitride uniformly filled inside the polymer matrix, wherein the filling amount of spherical boron nitride is 60 wt%.

The viscosity of the thermal interface material of this example is 600 Pa·s. Under normal temperature and 20 psi pressure conditions, the steady-state heat flow method was used to determine the thermal conductivity of the thermal interface material to be 6.0 W/(m·K).

Example Three

Take 20 parts by mass of spherical boron nitride with a particle size of 100 μm, 30 parts by mass of alicyclic liquid epoxy resin, 40 parts by mass of ethylenediamine curing agent, and 4 parts by mass of tri-(dimethylaminomethyl) ) Phenol catalyst, 2 parts by mass of KH550 silane coupling agent, 4 parts by mass of 1,4-butanediol diglycidyl ether, the above materials are mixed for 0.5 min under the condition of rotation speed of 2500 rpm to obtain a uniformly mixed mixture . The resulting mixture was placed in an oven, and the mixture was cured under normal pressure at 120°C for 3 hours to obtain a thermal interface material.

The thermal interface material prepared according to the above preparation method includes a polymer matrix and spherical boron nitride uniformly filled inside the polymer matrix, wherein the filling amount of spherical boron nitride is 20 wt%.

The viscosity of the thermal interface material of this example is 5 Pa·s. Using the steady-state heat flow method, the thermal conductivity of the thermal interface material is determined to be 2.0 W/(m·K) under normal temperature and 20 psi pressure.

Example 4

Take 40 parts by mass of spherical boron nitride with a particle size of 50 μm, 20 parts by mass of bisphenol A liquid epoxy resin, 20 parts by mass of methylhexahydrophthalic anhydride curing agent, and 5 parts by mass of N,N-dimethyl A catalyst consisting of benzylamine and tri-(dimethylaminomethyl)phenol, 5 parts by mass of KH560 silane coupling agent, and 10 parts by mass of n-butyl glycidyl ether are mixed, and the above is carried out at a speed of 2000 rpm The materials were mixed for 3 minutes to obtain a homogeneous mixture. The obtained mixture was placed in an oven, and the mixture was cured under normal pressure at 200°C for 3 hours to obtain a thermal interface material.

The thermal interface material prepared according to the above preparation method includes a polymer matrix and a spherical boron nitride uniformly filled inside the polymer matrix, wherein the filling amount of the spherical boron nitride is 40 wt%.

The viscosity of the thermal interface material of this example is 110 Pa·s. Using the steady-state heat flow method, the thermal conductivity of the thermal interface material was determined to be 3.0 W/(m·K) under normal temperature and 20 psi pressure conditions.

Example 5

45 parts by mass of spherical boron nitride with a particle size of 200 μm, 20 parts by mass of bisphenol A liquid epoxy resin, 18 parts by mass of methylhexahydrophthalic anhydride curing agent, and 5 parts by mass of N,N-dimethyl A catalyst composed of benzylamine and tri-(dimethylaminomethyl)phenol, 2 parts by mass of KH560 silane coupling agent, and 10 parts by mass of n-butyl glycidyl ether are mixed, and the above is carried out at a speed of 1500 rpm The materials were mixed for 8 minutes to obtain a homogeneous mixture. The obtained mixture was placed in an oven, and the mixture was cured under normal pressure at 200°C for 3 hours to obtain a thermal interface material.

The thermal interface material prepared according to the above preparation method includes a polymer matrix and spherical boron nitride uniformly filled inside the polymer matrix, wherein the filling amount of spherical boron nitride is 45% by weight.

The viscosity of the thermal interface material of this example is 120 Pa·s. The steady-state heat flow method was used to measure the thermal conductivity of the thermal interface material at 4.3 W/(m·K) under normal temperature and 20 psi pressure.

Example Six

Take 35 parts by mass of spherical boron nitride with a particle size of 200 μm, 30 parts by mass of bisphenol A liquid epoxy resin, 28 parts by mass of methylhexahydrophthalic anhydride curing agent, and 1 part by mass of 2-ethyl-4 -A methylimidazole catalyst, 1 part by mass of KH560 silane coupling agent, and 5 parts by mass of n-butyl glycidyl ether are mixed, and the above materials are mixed for 10 minutes under the condition of a rotation speed of 2000 rpm to obtain a uniformly mixed mixture. The resulting mixture was placed in an oven, and the mixture was cured under normal pressure at 200°C for 1 hour to obtain a thermal interface material.

The thermal interface material prepared according to the above preparation method includes a polymer matrix and spherical boron nitride uniformly filled inside the polymer matrix, wherein the filling amount of spherical boron nitride is 35 wt%.

The viscosity of the thermal interface material of this example is 65 Pa·s. The steady-state heat flow method was used to measure the thermal conductivity of the thermal interface material at 2.8 W/(m·K) under normal temperature and 20 psi pressure.

Although the present invention has been shown and described with reference to specific embodiments, those skilled in the art will understand that the form and form can be carried out without departing from the spirit and scope of the invention as defined by the claims and their equivalents. Various changes in details.

Claims

A method for preparing a thermal interface material, which includes the steps of:

S1, 10 to 60 parts by mass of spherical boron nitride, 10 to 50 parts by mass of thermosetting resin, 10 to 50 parts by mass of curing agent, 1 to 5 parts by mass of catalyst, and 1 to 5 parts by mass of coupling agent are carried out Mix to get mixed slurry;

S2. Heating and curing the mixed slurry under the conditions of 60°C to 200°C for 0.5h to 6h to obtain a thermal interface material;

Wherein, the total mass part of the mixed slurry in step S1 is 100.
The preparation method according to claim 1, wherein in the step S1, it further comprises mixing together no more than 10 parts by mass of a diluent to obtain the mixed slurry.
The preparation method according to claim 1, wherein the spherical boron nitride is obtained by sintering primary particles of hexagonal boron nitride.
The production method according to claim 2, wherein the primary particles of hexagonal boron nitride are sintered to obtain the spherical boron nitride.
The preparation method according to claim 3, wherein the spherical boron nitride has a particle diameter of 5 μm to 200 μm.
The preparation method according to claim 5, wherein the thermosetting resin is liquid epoxy resin or silicone resin; the curing agent is methylhexahydrophthalic anhydride, ethylenediamine, triethylenetetramine and m-phenylenediamine At least one of the above; the catalyst is at least one of 2-ethyl-4-methylimidazole, N,N-dimethylbenzylamine and tri-(dimethylaminomethyl)phenol; The coupling agent is at least one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, and a bimetallic coupling agent.
The production method according to claim 2, wherein the diluent is a glycidyl ether compound.
A thermal interface material, wherein the thermal interface material includes a polymer matrix and spherical boron nitride uniformly filled in the polymer matrix.
The thermal interface material according to claim 8, wherein the spherical boron nitride is spherical boron nitride obtained by sintering primary hexagonal boron nitride particles.
The thermal interface material according to claim 8, wherein the filling amount of the spherical boron nitride in the thermal interface material is not less than 20wt%, so that the thermal conductivity of the thermal interface material is not less than 2.0W/(m · K).
The thermal interface material according to claim 9, wherein the filling amount of the spherical boron nitride in the thermal interface material is not less than 20wt%, so that the thermal conductivity of the thermal interface material is not less than 2.0W/(m · K).
The thermal interface material according to claim 10, wherein the filling amount of spherical boron nitride in the thermal interface material is not less than 35wt% and not more than 60wt%, so that the viscosity of the thermal interface material is not less than 65Pa·s and not higher than 600Pa·s, thermal conductivity is not lower than 2.8W/(m·K) and not higher than 6W/(m·K).
The thermal interface material according to claim 8, wherein the filling amount of spherical boron nitride in the thermal interface material is not less than 10% and not more than 35% by weight, so that the viscosity of the thermal interface material is not higher than 65Pa·s, thermal conductivity is not lower than 0.5W/(m·K) and not higher than 2.8W/(m·K).