CN102093713B - Thermal Composite Materials - Google Patents

Abstract

The invention provides a heat dissipation composite material and a corresponding forming method. By combining core-shell filling particles with different particle sizes and different compositions, a polyimide film has high thermal conductivity and has both electrical properties and flexibility of a finished polyimide film.

Description

Thermal Composite Materials

technical field

The invention relates to a heat-conducting polyimide composite material, and particularly relates to the composition, ratio and particle size distribution of its core-shell filling particles.

Background technique

With the trend of light weight, thin and mobile electronic products, the packaging density of electronic products is becoming more and more integrated. In addition, the demand for functions is getting higher and higher, and the required driving power has been increasing, and the heat generated by the system has also risen linearly. How to maintain the stable operation of the electronic product system through good heat dissipation will become an important issue. The key point, polyimide resin is often used as the insulating layer of copper foil substrate materials because of its excellent heat resistance, mechanical properties and electrical properties. In order to respond to the trend of miniaturization and high-speed electronic products in the future For the heat dissipation problem, if the resin insulation layer in the substrate can be given the function of heat conduction, it can provide a good heat dissipation path for the components, so as to increase the reliability and life of the components.

In EP 1672009 (A1), it is disclosed that boron nitride, silicon carbide, aluminum nitride, titanium oxide, calcium phosphide or tantalum oxide coated with high thermal conductivity particles such as aluminum oxide, silicon oxide, boron nitride, and aluminum oxide The structure of the barium bonded to the polyimide film makes the polyimide have good thermal conductivity, high dielectric strength and high adhesion, but this patent does not disclose any thermal conductivity data of the polyimide film. In this patent, up to 80% by weight of highly thermally conductive particles are disclosed, with a particle size between 50nm and 10000nm.

In US Pat.No.5,078,936, a method of increasing the thermal conductivity/conductivity of polyimide film with carbon black is disclosed, but this patent is only limited to the application of conductivity.

In US Pat. No. 6,001,440, a centrifugal casting method (centrifugal casting) is disclosed to form a gradient concentration of high thermal conductivity particles in the polyimide film to improve its thermal conductivity. These particles account for about 10% to 30% of the total weight of the finished film, and are selected from boron nitride, silicon oxide, beryllium oxide or aluminum nitride. However, this patent still does not disclose the thermal conductivity value of the polyimide film.

In JP 2004123867 (A), it is disclosed that carbon nanotubes are used to increase the thermal conductivity of polyimide to above 0.3 W/m.K, wherein the amount of carbon nanotubes is as high as 50% of the total weight of the polyimide film. However, the above method needs to use a large amount of carbon nanotubes, which is not conducive to mass production.

In JP 9137060 (A), it is disclosed that boron nitride or aluminum nitride is used to improve the thermal conductivity of polyimide film. The average particle size is about 0.1 micron to 10 microns, and the thermal conductivity of the finished film is about 0.2 W/m.K to 0.6 W/m.K.

However, the expensive particles used in the above methods will inevitably cause cost problems in mass production, and these patents do not discuss other important properties of the finished film, such as flexibility and dielectric value. A polyimide film added with a large amount of heat-conducting particles will have too high hardness to be practically applied. In addition, while using inorganic particles to improve thermal conductivity, it is still necessary to consider that adding a large amount of inorganic particles to the finished film will increase its dielectric value and cause dielectric loss. However, none of the known technologies systematically discloses or considers the above-mentioned problems.

The inorganic filler particles used in the known technology can improve thermal conductivity, but at the same time improve many properties that do not need to be improved, such as dielectric constant, dielectric loss and film hardness. In this way, even if the thermal conductivity of the finished film is improved, other degraded properties will make the film unusable. Unfortunately, many commercially available thermally conductive film formulations only consider thermal conductivity between 0.2 W/m.K and 0.5 W/m.K, while ignoring the degraded dielectric properties.

The thermally conductive filler particles used in most known technologies are oxides or nitrides, such as silicon oxide, aluminum oxide, titanium oxide, aluminum nitride or boron nitride, or titanium carbide, or silicon carbide and other high dielectric constant and high dielectric lost material. In this way, the above-mentioned filled particles not only improve the thermal conductivity of polyimide, but also improve other dielectric properties. At present, there is no related known technology that can simultaneously improve the thermal conductivity of the polyimide film and reduce or maintain its dielectric constant and dielectric loss.

Another problem is that a certain proportion of inorganic filler particles necessarily reduces the mechanical properties of polyimide such as flexibility. When the inorganic filler particles aggregate, the above problems will be exacerbated and even embrittled film products.

In addition, the coefficient of thermal expansion between polyimide and inorganic filler particles is different, which will cause micro stress between the two. The micro-stress unevenly distributed in the film will block the transmission of phonons in the film, and will reduce the thermal diffusion effect, which in turn will reduce the thermal conductivity of the film. In addition, the aforementioned micro-stresses may deform the film, causing device displacement and degrading device performance.

Finally, the surface of inorganic filler particles may undergo surface potential catalytic reaction (potential catalytic reaction) with polyimide or its precursor at high temperature. Especially when the particle size of the filler particles is ultra-small such as nanometer scale, the surface potential energy and defect distribution of the filler particles will be significantly improved, which will make the precursor of polyimide react with the filler particles during high temperature cyclization reaction. produce uncontrolled and unexpected reactions. Obviously, the above-mentioned surface potential energy catalyzed reaction will deteriorate the properties of the finished product.

In summary, there is an urgent need for a new method to provide answers to the above questions, so as to simultaneously take into account the high thermal conductivity, high dielectric strength, low dielectric constant, low dielectric loss, and good properties of polyimide films. mechanical flexibility. In order to achieve the above goals, the present invention provides core-shell filled particles with different compositions and particle size distributions.

Contents of the invention

The invention provides a heat dissipation composite material, comprising 100 parts by weight of polyimide resin; 0.1 to 50 parts by weight of first core-shell filled particles, the particle diameter of which is between 10nm and 100nm; and 1 to 60 parts by weight The second core-shell filled particles have a particle size between 100nm and 2000nm. Wherein, the first core-shell filled particles and the second core-shell filled particles are uniformly dispersed in the polyimide resin; the first and second core-shell filled particles have an inorganic core and an organic shell, and the first and second cores The composition of the shell-filled particles varies.

Specific Embodiments of the Invention

The invention provides a heat dissipation composite material, comprising 100 parts by weight of polyimide resin; 0.1 to 50 parts by weight of first core-shell filled particles, the particle diameter of which is between 10nm and 100nm, and 1 to 60 parts by weight The second core-shell filled particles have a particle size between 100nm and 2000nm. The filler particles with smaller particle size can be filled between the filler particles with larger particle size, so they can be more uniformly dispersed among the polyimide resins. In other words, polyimide molecules have more degrees of freedom, which increases the flexibility of the finished film. In addition, increasing the particle size of filler particles may increase the attractive force between each other. If the distribution of the filler particles is narrow, for example, only between 50 nm and 500 nm, the flexibility of the film will be poor.

The above-mentioned flexibility is defined as directly folding the polyimide film in half and flattening it, and repeating the above-mentioned actions to confirm the flexibility of the film. If it breaks after being folded in half once, the film has poor flexibility. If it breaks after repeated folding and flattening times less than ten times, the film has medium flexibility. If the number of repeated folding and flattening exceeds ten times before breaking, the film has good flexibility.

The above two kinds of core-shell filled particles are uniformly dispersed in the polyimide resin, and both have an inorganic core and an organic shell. In addition, the compositions of the two core-shell filled particles are different. For example, two types of core-shell particles may have different cores and/or shells, depending on need.

The preparation method of the above core-shell filled particles can refer to the paper published by P.Rainder et al. in Materials Science and Enginerring A; A498(1-2).135-141(2008), the early publication of US patent US Pub.No. Wang et al published in Applied Physics Letters, 91(14), 141904/1-3(2007), JP 2007146068, MX Gu et al published in Journal of Applied Physics, 100(9)94304/1-8(2006), Y Au et al. in Physical Review B, 74(15) 155317/1-10 (2006), R Prasher et al. in Applied Physics Letters, 89(6)63121/1-3 (2006), M Hu et al. In Chemical Physics Letters, 372 (5, 6) 767-772 (2003), T Zeng et al. published in Journal of Applied Physics, 93 (7) 4163-4168 (2003), Y mamunye et al. published in European Polymer Journal, 38 (9) 1887-1897 (2002), E Suvaci etc. are published in journals or patents such as Ceramic Engineering and Science Proceedings, 21, 79-86 (2000). However, none of the above-mentioned known technologies discloses a solution for combining core-shell particles with polyimide resin to improve its thermal conductivity and simultaneously balance electrical properties and flexibility.

In one embodiment of the present invention, the shell of the above-mentioned core-shell structure is a low molecular weight organic molecule such as stearic acid (stearic acid), 12-hydroxystearic acid (12-hydroxystearic acid), octylammonium chloride (octylammonium chloride), cetyltrimethylammonium bromide, dodecyltrimethylammonium chloride, polyoxyethylene soritan tetraoleate , polyoxyethylene tridecyl ether (polyoxyethylenetridecyl ether), 4,4'-diaminodiphenyl ether (4,4'-oxydianiline), 4,4'-(hexafluoroisopropylidene)-bis( p-benzooxy)dianiline (4,4'-(hexafluoroisopropylidene)bis(p-phenylenoxy)dianiline), 4,4'-(hexafluoroisopropylidene)phthalic anhydride (4,4'- (hexafluoroisopropylidene)diphthalic anhydride), 4,4'-(isopropylidene-diphenoxy)phthalic anhydride (4,4'-(isopropylidene-diphenoxy)bis(phthalic anhydride)), or combinations thereof. The above-mentioned organic molecules have carboxyl, carbonyl, hydroxyl, amide and/or imido groups, which can make the organic molecules react with the inorganic layer and be fixed on the surface of the inorganic core. Organic molecules not immobilized on the inorganic core can be mixed in the polyimide solution as a stabilizer. After the organic molecules are dissolved in a specific solvent to form a relatively stable solution, an organic shell with a thickness of 1 nm to 10 nm, preferably 2 nm to 10 nm, can be deposited on the surface of the inorganic particles. The above-mentioned organic shell accounts for about 0.1% to 20% of the total weight of the core-shell structure, and can effectively protect the surface of the inorganic core from the generation of surface in the high-temperature synthesis environment of polyimide precursors such as dianhydride and diamide, such as 350 ° C. Potential catalytic reaction.

In addition to protecting the inorganic core, the organic shell has other advantages. For example, the compatibility between the organic shell and the polyimide resin can prevent the core-shell particles from aggregating (aggregation) and disperse more uniformly in the polyimide, which can be used as a link between the polyimide and the inorganic core. The buffer layer, thereby improving the flexibility of the finished film, and reducing the thermal expansion coefficient of the polyimide film through a higher filling amount.

In a preferred embodiment, the inorganic core in the core-shell structure may include, but is not limited to, oxides such as silicon oxide, aluminum oxide, titanium oxide, magnesium oxide, iron oxide, cobalt oxide, copper oxide, or zinc oxide; nitrides such as nitride Silicon, aluminum nitride or boron nitride; carbides such as silicon carbide, titanium carbide or boron carbide. The above-mentioned organic molecules can be deposited to form a shell on the surface of the above-mentioned inorganic core to form a core-shell structure.

The inorganic core of the present invention can be a metal element, including but not limited to aluminum, nickel, cobalt, iron, copper and other high thermal conductivity metals. In another embodiment, before depositing organic molecules on the surface of the metal core, an oxide layer may be further formed to cover the surface of the metal core by means of thermal oxidation or the like. The environment of the above-mentioned thermal oxidation step is general atmosphere, the temperature is between about 300° C. and 600° C., and the time is between 1 minute and 30 minutes. After the deposition of the organic shell, a metal core and organic shell are formed which are clad with oxidized metal.

The metal oxide covering the metal core and the organic shell are both insulating materials, which can improve the electrical insulation properties of the polyimide film. The use of thermal oxidation to form metal oxides on the surface of the metal core can reduce or even eliminate the difference in mechanical properties between the two. The metal oxide layer close to the metal core can prevent the conductive properties of the metal core from affecting the electrical insulation properties of the polyimide, and take into account its thermal conductivity while increasing the breakdown voltage of the finished film.

However, the core-shell filled particles may still increase the dielectric constant and dielectric loss of the polyimide film to a certain extent. This is because the dielectric constant of metal oxides or metal alloys is still relatively high. For example, the dielectric constant of magnesium oxide is 9.7, the dielectric constant of aluminum oxide is between 9 and 11.5, and the dielectric constant of titanium oxide It is 110, the dielectric constant of copper oxide is 18.1, the dielectric constant of silicon carbide is 10.8, the dielectric constant of iron oxide is 14.2, the dielectric constant of titanium carbide is between 5.8-7.0, and the dielectric constant of aluminum nitride The constant is 9. The above-mentioned inorganic cores with high dielectric constants will degrade the dielectric properties of the polyimide film, but none of the known technologies mentioned or considered the above problems.

In order to solve the above-mentioned problem of high dielectric constant of part of the inorganic core, the present invention uses mixed core-shell filling particles. In short, the present invention uses core-shell filler particles with low dielectric constant and low dielectric loss to match the above-mentioned core-shell filler particles with high dielectric constant and high dielectric loss but high thermal conductivity. In this way, the polyimide film can simultaneously have properties such as high thermal conductivity, low dielectric constant, and high dielectric strength, and multiple embodiments of the present invention have proved that the above idea is feasible.

After uniformly mixing the above two kinds of core-shell filled particles with different particle size distributions and different compositions, the precursor solution of polyimide is added. After vigorous high-speed stirring, the steps of degassing, casting, drying, and heating are performed to cyclize the precursor of polyimide to form a polyimide film. The above solution may include, but is not limited to, NMP, DMAc, DMSO, hexane, toluene, heptane, octane, or combinations thereof. The selection standard of the solvent is that there will be no co-precipitation and other phenomena when mixing different solutions, and it will not react with polyimide and core-shell filled particles.

In another embodiment of the present invention, based on 100 parts by weight of polyimide, 5 to 70 parts by weight of another core-shell filler particle can be added. The above-mentioned core-shell filled particles are also uniformly dispersed in the polyimide resin, and the particle diameter is between 2000nm and 10000nm. Another core-shell-filled particle has an inorganic core and an organic shell, and its composition is different from the first and second core-shell-filled particles. The selection of the inorganic core and the organic shell of another filler particle is similar to the above-mentioned first and second core-shell filler particles, and will not be repeated here.

In a preferred embodiment, the total weight of the core-shell filled particles is preferably between 10% and 60% of the finished film. If the amount of the core-shell filler particles is too small, the thermal conductivity of the polyimide film cannot be effectively improved. But relatively, if the content of the core-shell filler particles is too high, the mechanical properties such as flexibility of the polyimide film will be reduced. Those skilled in the art can adjust the weight ratio and types of the above two core-shell particles to achieve the best heat dissipation composite material without exceeding the scope of the present invention, and further apply it to microelectronic products or optoelectronic products.

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, several embodiments are enumerated below in conjunction with the accompanying drawings, and are described in detail as follows.

[Example]

Example 1

Take 60g of silicon oxide (Nissonchemical/DMAc-ST) with a particle size between 10nm and 30nm, put it into a mixture of dimethylacetamide (hereinafter referred to as DMAc) and toluene dissolved in 0.06g to 12g of octadecanoic acid Solvent (v/v=70:30) allowed octadecanoic acid to deposit on the surface of silicon oxide, and the deposition result was confirmed by thermogravimetric analysis. After the above deposition, core-shell particles (SS-1 for short) with silicon oxide as the inorganic core and octadecanoic acid as the organic shell can be obtained. When 60g of silicon oxide is combined with 12g of octadecanoic acid, the thickness of the organic shell of the core-shell structure is between 2nm and 2.5nm.

The present invention can adopt the above conditions to replace octadecanoic acid with 4,4'-(hexafluoroisopropylidene)-bis(p-benzooxy)diphenylamine to form silicon oxide as the inorganic core and 4, 4'-(hexafluoroisopropylidene)-bis(p-benzooxy)diphenylamine is a core-shell particle with an organic shell (SS-2 for short).

Whether it is SS-1 or SS-2, the step of depositing the organic shell on the inorganic core can be combined with zirconia beads for 24 hours of ball milling process, so that 30% by weight of the core-shell particles can be uniformly dispersed in the solution.

Example 2

Take 45g of alumina (Nippon Light Metal/LS-110F) with a particle size between 200nm and 1000nm, and put it into a mixed solvent of DMAc and heptane dissolved in 0.045g to 9g of cetyltrimethylammonium bromide (v/v=60:40), with zirconia beads for 24 hours of ball milling process, so that cetyltrimethylammonium bromide is deposited on the surface of alumina to form a suspension with a solid content of about 30% by weight , and the deposition results were confirmed by thermogravimetric analysis. After the above deposition, core-shell particles (AS-1 for short) with alumina as the inorganic core and cetyltrimethylammonium bromide as the organic shell can be obtained, and the weight ratio of the inorganic core to the organic shell is about 100: Between 1 and 100:1.5.

Example 3

Take 65g of zinc oxide with a particle size between 300nm and 2000nm (Luchang Chemical/U.S. legal system), put 0.65g to 3.25g of 4,4'-(hexafluoroisopropylidene) phthalo In the mixed solvent (v/v=70:30) of N-methylrolidone (hereinafter referred to as NMP) of acid anhydride and heptane, the ball milling process was carried out with zirconia beads for 24 hours to make 4,4'-(hexa Fluoroisopropylidene) phthalic anhydride is deposited on the surface of zinc oxide to form a suspension with a solid content of about 30% by weight, and the deposition result is confirmed by thermogravimetric analysis. After the above deposition, the core-shell particle (ZS-1 for short) with zinc oxide as the inorganic core and 4,4'-(hexafluoroisopropylidene) phthalic anhydride as the organic shell (abbreviated as ZS-1) can be obtained, and the inorganic core and organic The weight ratio of the shell is about 100:1 to 100:1.5.

Example 4

Take 45g of titanium oxide (Yazhong Industry/CR-EL) with a particle size between 300nm and 1000nm, and put it into dimethyl sulfoxide (hereinafter referred to as DMSO) and octane mixed solvent (v/v=60:40), with zirconia beads for 24 hours of ball milling process, so that 12-hydroxyoctadecanoic acid is deposited on the surface of titanium oxide, forming a solid content of about 30 % by weight of the suspension and confirm the deposition results by thermogravimetric analysis. After the above deposition, the core-shell particle (TS-1 for short) with titanium oxide as the inorganic core and 12-hydroxyoctadecanoic acid as the organic shell can be obtained, and the weight ratio of the inorganic core to the organic shell is about 100:1 to 100 : Between 1.5.

Example 5

Take 65g of aluminum powder (Xintao/sphericalaluminum powder) with a particle size between 2000nm and 10000nm, and perform an oxidation process at a high temperature of 300°C to 600°C for 1 to 30 minutes in the atmosphere, and the appearance changes (turns to white) It can be seen that the surface of the aluminum powder has been oxidized. At this point, the surface of the aluminum core is covered with an aluminum oxide layer.

Put the above-mentioned aluminum powder particles coated with alumina on the surface into a mixed solvent (v/v=60:40) of DMAc and heptane dissolved with 0.065g to 3.25g of cetyltrimethylammonium bromide , with zirconia beads for 24 hours of ball milling process, cetyltrimethylammonium bromide is deposited on the surface of alumina to form a suspension with a solid content of about 30% by weight, and the deposition is confirmed by thermogravimetric analysis result. After the above-mentioned deposition, the core-shell particle (AAS-1 for short) in which the aluminum coated with alumina on the surface is the inorganic core and cetyltrimethylammonium bromide is the organic shell (abbreviated as AAS-1), and the weight of the inorganic core and the organic shell The ratio is between about 100:1 and 100:1.5.

Example 6

Take 65g of nickel powder (EMA Technology/reduction state) with a particle size between 2000nm and 10000nm, and carry out an oxidation process at a high temperature of 300°C to 600°C for 1 to 30 minutes in the atmosphere, and the change from appearance (to Dark green) shows that the surface of the nickel powder has been oxidized. At this time, the surface of the nickel core has been coated with a nickel oxide layer.

Put the above-mentioned nickel particles coated with nickel oxide on the surface into a mixed solvent (v/v=70:30) of DMAc and heptane dissolved with 0.065g to 3.25g of cetyltrimethylammonium bromide, A 24-hour ball milling process was performed with zirconia beads to deposit cetyltrimethylammonium bromide on the surface of nickel oxide to form a suspension with a solid content of about 30% by weight, and the deposition results were confirmed by thermogravimetric analysis . After the above-mentioned deposition, the core-shell particle (NNS-1) in which the nickel coated with nickel oxide on the surface is the inorganic core and cetyltrimethylammonium bromide is the organic shell (abbreviated as NNS-1), and the weight of the inorganic core and the organic shell The ratio is between about 100:1 and 100:1.5.

Example 7

Take 32g of silicon carbide (thick/C-8) with a particle size between 300nm and 1500nm, put it into a mixture of NMP and octane dissolved in 0.32g to 1.6g of 4,4'-diaminodiphenyl ether In a solvent (v/v=60:40), a 24-hour ball milling process is performed with zirconia beads, so that 4,4'-diaminodiphenyl ether is deposited on the surface of silicon carbide to form a suspension with a solid content of about 30% by weight. liquid, and the deposition results were confirmed by thermogravimetric analysis. After the above deposition, core-shell particles (SC-1 for short) with silicon carbide as the inorganic core and 4,4'-diaminodiphenyl ether as the organic shell can be obtained, and the weight ratio of the inorganic core to the organic shell is about 100: Between 1.5 and 100:3.

Example 8

The SS-1 suspension of Example 1 and the AS-1 suspension of Example 2 were taken and uniformly mixed with the polyimide precursor solution, wherein the weight ratio of SS-1 to AS-1 was about 30:70. Then the above mixture was vigorously stirred at high speed for two hours, and then degassed, molded, dried, and heated (350° C.) to cyclize the precursor of polyimide to form a polyimide with a thickness between 25 microns and 37 microns. For polyimide film, SS-1 and AS-1 account for about 10% to 80% of the total weight of the finished product, depending on the proportion of the starting formula. The above-mentioned films containing different proportions of core-shell particles all have smooth surfaces, but if the total weight of the core-shell particles exceeds 60% of the weight of the finished product, the mechanical properties of the film are hard and brittle. To obtain good film flexibility, the total weight of the core-shell particles in the above formulation is preferably less than 60% of the finished film.

The thermal conductivity of the finished films above is between 0.5 W/m.K and 2.8 W/m.K, the dielectric constant is between 3.7 and 4.8, the dielectric loss is between 0.0085 and 0.037, and the dielectric strength Between 3.7kV and 5.3kV.

The properties of the above-mentioned finished products have reached an acceptable level for industrial applications, but in order to further improve its mechanical properties such as flexibility, the total weight of the core-shell particles is preferably less than 60% of the finished film.

The above-mentioned finished film was taken to measure the thermal stretching mechanical properties. The measurement temperature ranged from room temperature to 250°C, and the coefficient of thermal expansion (CTE) ranged from 19.8ppm to 16.7ppm.

Example 9

The SS-1 suspension of Example 1 and the TS-1 suspension of Example 4 were taken and uniformly mixed with the polyimide precursor solution, wherein the weight ratio of SS-1 to TS-1 was about 40:60. Then the above mixture was vigorously stirred at a high speed for two hours, and after degassing, casting, drying, and heating steps (350°C), the precursor of polyimide was cyclized to form a polyimide film, and its SS-1 and TS-1 accounts for about 20% to 80% of the total weight of the finished product, depending on the proportion of the starting formula. The above-mentioned films containing different proportions of core-shell particles all have smooth surfaces, but if the total weight of the core-shell particles exceeds 60% of the weight of the finished product, the mechanical properties of the film are hard and brittle. For better film flexibility, the total weight of the core-shell particles in the above formulation is preferably less than 60% of the finished film.

The thermal conductivity of the finished film is between 0.4 W/m.K and 4.5 W/m.K, the dielectric constant is between 3.7 and 8.8, the dielectric loss is between 0.0165 and 0.047, and the dielectric strength Between 3.7kV and 6.3kV.

The properties of the above-mentioned finished products have reached an acceptable level for industrial applications, but in order to further improve its mechanical properties such as flexibility, the total weight of the core-shell particles is preferably less than 60% of the finished film.

Example 10

The SS-1 suspension in Example 1 and the ZS-1 suspension in Example 3 were uniformly mixed with the polyimide precursor solution, wherein the weight ratio of SS-1 to ZS-1 was about 50:50. Then the above mixture was vigorously stirred at a high speed for two hours, and after degassing, casting, drying, and heating steps (350°C), the precursor of polyimide was cyclized to form a polyimide film, and its SS-1 and ZS-1 accounts for about 10% to 70% of the total weight of the finished product, depending on the proportion of the starting formula.

The thermal conductivity of the finished films above is between 0.3 W/m.K and 2.6 W/m.K, the dielectric constant is between 4.0 and 7.5, the dielectric loss is between 0.0185 and 0.056, and the dielectric strength Between 3.9kV and 6.3kV. However, compared with Example 9, the finished film of Example 10 has a higher dielectric loss when the content of core-shell particles is higher, which should come from the nature of ZS-1.

The properties of the above-mentioned finished products have reached an acceptable level for industrial applications, but in order to further improve its mechanical properties such as flexibility, the total weight of the core-shell particles is preferably less than 50% of the finished film.

Example 11

Take the AS-1 suspension in Example 2 and the SC-1 suspension in Example 7, and mix them uniformly with the polyimide precursor solution, wherein the weight ratio of AS-1 to SC-1 is about 50:50. Then the above mixture was vigorously stirred at a high speed for two hours, and after degassing, casting, drying, and heating steps (350°C), the polyimide precursor was cyclized to form a polyimide film, and its AS-1 and SC-1 accounts for about 10% to 70% of the total weight of the finished product, depending on the proportion of the starting formula.

When the core-shell particles account for 20% to 70% of the total weight of the finished film, the thermal conductivity of the finished film is between 0.4 W/m.K and 10.6 W/m.K. When the core-shell particles account for 10% to 70% of the total weight of the finished film, the dielectric constant of the above-mentioned finished film is between 4.0 and 7.5, the dielectric loss is between 0.0085 and 0.056, and the dielectric strength is between 2.8kV to 5.3kV. However, compared with Example 9, the finished product of Example 11 has a higher dielectric loss when the content of core-shell particles is higher, which should come from the nature of AS-1 and SC-1.

In order to make the finished film have good flexibility, low dielectric constant, and low dielectric loss, the total weight of the core-shell particles is preferably less than 50% of the finished film. Compared with Examples 9-10, the particle size distribution of the core-shell particles in Example 11 is narrower, which may result in poorer flexibility of the finished film.

Example 12

The SS-1 suspension of Example 1 and the AAS-1 suspension of Example 5 were taken and uniformly mixed with the polyimide precursor solution, wherein the weight ratio of SS-1 to AAS-1 was about 50:50. Then the above mixture was vigorously stirred at a high speed for two hours, and after degassing, casting, drying, and heating steps (350°C), the precursor of polyimide was cyclized to form a polyimide film, and its SS-1 and AAS-1 accounts for about 10% to 70% of the total weight of the finished product, depending on the proportion of the starting formula.

The thermal conductivity of the finished film is between 0.3 W/m.K and 4.8 W/m.K, the dielectric constant is between 4.0 and 6.5, the dielectric loss is between 0.0085 and 0.0256, and the dielectric strength Between 4.9kV and 6.3kV. However, the finished film has higher dielectric loss when the content of core-shell particles is higher, which should come from the nature of AAS-1.

In order to make the finished film have good flexibility, the total weight of the core-shell particles is preferably less than 50% of the finished film.

The above-mentioned finished film was taken to measure the coefficient of thermal expansion. The measurement temperature ranged from room temperature to 250°C, and the coefficient of thermal expansion (CTE for short) ranged from 18.8ppm to 16.7ppm. It can be seen from the experimental results that when the amount of core-shell particles increases, the thermal expansion coefficient of the finished film also decreases.

Example 13

The SS-1 suspension of Example 1 and the NNS-1 suspension of Example 6 were taken and uniformly mixed with the polyimide precursor solution, wherein the weight ratio of SS-1 to NNS-1 was about 50:50. Then the above-mentioned mixture was vigorously stirred at high speed for two hours, and after degassing, casting, drying, and heating steps (350° C.), the polyimide precursor was cyclized to form a polyimide film, and its SS-1 and NNS-1 accounts for about 20% to 80% of the total weight of the finished product, depending on the proportion of the starting formula.

The thermal conductivity of the finished film is between 0.5 W/m.K and 5.6 W/m.K, the dielectric constant is between 4.0 and 7.5, the dielectric loss is between 0.0065 and 0.0156, and the dielectric strength Between 4.9kV and 7.3kV. However, the finished film has a higher dielectric loss when the content of core-shell particles is higher, which should come from the nature of NNS-1.

In order to make the finished film have good flexibility, the total weight of the core-shell particles is preferably less than 60% of the finished film.

Example 14

Get the SS-1 suspension of Example 1, the AS-1 suspension of Example 3, and the SC-1 suspension of Example 7, and mix evenly with the precursor solution of polyimide, wherein SS-1, AS -1. The weight ratio with SC-1 is about 30:50:20. Then the above-mentioned mixture was vigorously stirred at high speed for two hours, and after degassing, casting, drying, and heating steps (350° C.), the polyimide precursor was cyclized to form a polyimide film, its SS-1, AS-1, and SC-1 account for about 20% to 80% of the total weight of the finished product, depending on the proportion of the starting formula.

The thermal conductivity of the finished films above is between 0.5 W/m.K and 4.6 W/m.K, the dielectric constant is between 4.3 and 6.5, the dielectric loss is between 0.0285 and 0.026, and the dielectric strength Between 3.9kV and 6.3kV. In order to make the finished film have good flexibility, the total weight of the core-shell particles is preferably less than 65% of the finished film.

Example 15

Get the SS-1 suspension of Example 1, the ZS-1 suspension of Example 3, and the AAS-1 suspension of Example 5, and mix them uniformly with the precursor solution of polyimide, wherein SS-1, ZS -1. The weight ratio to AAS-1 is about 20:50:30. Then the above-mentioned mixture was vigorously stirred at high speed for two hours, and after degassing, casting, drying, and heating steps (350° C.), the polyimide precursor was cyclized to form a polyimide film, its SS-1, ZS-1, and AAS-1 account for about 20% to 80% of the total weight of the finished product, depending on the proportion of the starting formula.

The thermal conductivity of the finished films above is between 0.5 W/m.K and 7.6 W/m.K, the dielectric constant is between 4.5 and 6.5, the dielectric loss is between 0.0085 and 0.046, and the dielectric strength Between 3.5kV and 6.7kV. In order to make the finished film have good flexibility, the total weight of the core-shell particles is preferably less than 60% of the finished film.

Comparative example 1

Take the single suspension of SS-1 in Example 1 and mix it uniformly with the precursor solution of polyimide, then stir the above mixture vigorously at high speed for two hours, then perform degassing, casting, drying, and heating steps (350°C) Finally, the polyimide precursor is cyclized to form a polyimide film, the SS-1 of which accounts for about 20% to 60% of the total weight of the finished product, depending on the proportion of the starting formula.

The thermal conductivity of the finished films above is between 0.5 W/m.K and 1.5 W/m.K, the dielectric constant is between 3.8 and 4.7, the dielectric loss is between 0.0095 and 0.028, and the dielectric strength Between 3.6kV and 4.8kV. However, the finished film has higher dielectric loss at higher core-shell particle content.

In order to make the finished film have good flexibility, the total weight of the core-shell particles is preferably less than 60% of the finished film.

Comparative example 2

The AAS-1 suspension of Example 5 and the NNS-1 suspension of Example 6 were taken and uniformly mixed with the polyimide precursor solution, wherein the weight ratio of ASS-1 to NNS-1 was about 50:50. Then the above mixture was vigorously stirred at a high speed for two hours, and after degassing, casting, drying, and heating steps (350°C), the polyimide precursor was cyclized to form a polyimide film, and its ASS-1 and NNS-1 accounts for about 20% to 60% of the total weight of the finished product, depending on the proportion of the starting formula.

The thermal conductivity of the finished films above is between 0.5 W/m.K and 5.8 W/m.K, the dielectric constant is between 4.2 and 7.8, the dielectric loss is between 0.018 and 0.078, and the dielectric strength Between 2.5kV and 3.8kV, the produced polyimide film has poor results in the flexural test.

Ex8 Ex9 Ex10 Ex11 Ex12 Filler type SS-1: 30% AS-1: 70% SS-1: 40% TS-1: 60% SS-1: 50% ZS-1: 50% AS-1: 50% SC-1: 50% SS-1: 50%AAS-1: 50% Filler (Filler) filling rate ≤60wt% ≤60wt% ≤50wt% ≤50wt% ≤60wt% K(thermal conductivity) ⁴⁾ W/M*K 0.5～2.8 0.4～4.5 0.3～2.6 0.4～10.6 0.3～4.8 DK ¹⁾ 3.7～4.8 3.7～8.8 4.0～7.5 4.0～7.5 4.0～6.5 Df ²⁾ 0.0085～0.037 0.0165～0.047 0.0185～0.056 0.0085～0.056 0.0085～0.0256 Destruction voltage3 ⁾ (KV) 3.7～5.3 3.7～6.3 3.9～6.3 2.8～5.3 4.9～6.3 Flexibility good good good good Medium~good

Ex13 Ex14 Ex15 Comparative example 1 Comparative example 2 Filler type SS-1: 50% NNS-1: 50% SS-1: 30% AS-1: 50% SC-1: 20% SS-1: 20% ZS-1: 50% AAS-1: 30% SS-1: 100% AAS-1: 50% NNS-1: 50% Filler (Filler) filling rate ≤60wt% ≤65wt% ≤60wt% ≤60wt% ≤60wt% K(thermal conductivity)W/M*K 0.5～5.6 0.5～4.6 0.5～7.6 0.5～1.5 0.5～5.8

DK 4.0～7.5 4.3～6.5 4.5～6.5 3.8～4.7 4.2～7.8 Df 0.0065～0.0156 0.0028～0.026 0.0085～0.046 0.0095～0.028 0.018～0.078 Destruction voltage (KV) 4.9～7.3 3.9～6.3 3.5～6.7 3.6～4.8 2.5～3.8 Flexibility Medium~good good Medium~good Medium~good Difference

1) DK (dielectric constant):

D k = dielectric coefficient of the dielectric/dielectric coefficient under vacuum

= Capacitance of the dielectric/capacitance with vacuum as the medium

C＝εA/d C ₀ ＝ε ₀ A/d

C/C ₀ =ε/ε ₀ =Dk (dielectric constant)

A: electrode area d: sample thickness

ε ₀ =8.85×10-12

ε＝(C×D)÷(0.0885×A)

A=πr ²

C: Capacitance

D: Sample thickness (cm)

A: electrode area

Measuring equipment: multi-frequency L.C.R measuring instrument, HP42754 instrument

2) Df (dielectric loss):

After the circuit substrate is powered on, the signal (electromagnetic wave) travels on the copper wire, and the atoms in the substrate medium are polarized by the electric field, resulting in the movement of charges, which is the so-called current. This current phenomenon is very small and mostly appears near the surface of the conductor, very shallow, and quickly decays to zero. This phenomenon is the loss of energy (dissipation).

Measuring equipment: multi-frequency L.C.R measuring instrument, HP42754 instrument

3) Destruction voltage:

The ability of a medium to withstand a high voltage of a certain value without collapse. Or the minimum voltage required to turn a non-conducting insulator into a conductor and generate an electric current.

Measuring equipment: withstand voltage tester model 730-1

4) K (thermal conductivity):

Thermal Conductivity: Under the unit temperature difference, the heat passing through the unit area and unit distance per unit time is called the thermal conductivity coefficient of the material. If it is measured with a material of thickness L, the measured value should be multiplied by L, and the obtained value is Is the thermal conductivity coefficient, usually recorded as k.

$\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; \&Delta;T</span>}}$

Measuring equipment: Hot-Disk 2400 type

Although the present invention has disclosed a number of preferred embodiments as above, these embodiments are not intended to limit the present invention, and any person skilled in the art can make some changes and modifications without departing from the spirit and scope of the present invention, therefore The scope of protection of the present invention should be defined by the appended claims.

Claims (3)

1. heat dissipation composite material comprises:

The polyimide resin of 100 weight parts;

0.1 to the first nucleocapsid particle filled composite of 50 weight parts, its particle diameter is between the 10nm to 100nm; And

The second nucleocapsid particle filled composite of 1 to 60 weight part, its particle diameter is between the 100nm to 2000nm;

Wherein, this first nucleocapsid particle filled composite and this second nucleocapsid particle filled composite are dispersed in this polyimide resin;

First and second nucleocapsid particle filled composite of wherein this has inorganic core and organic shell, and the composition of first and second nucleocapsid particle filled composite is different,

Wherein, this inorganic core is oxide compound, is selected from silicon oxide, aluminum oxide, titanium oxide, magnesium oxide, ferric oxide, cobalt oxide, cupric oxide or zinc oxide; Nitride is selected from silicon nitride, aluminium nitride or boron nitride; Carbide is selected from silicon carbide, titanium carbide or norbide; Or metal, be selected from aluminium, cobalt, nickel, titanium, silver, copper or iron, and the metallic surface comprises the oxide compound of corresponding core metal;

Wherein, this organic shell is selected from octadecanoic acid, 12-hydroxyl octadecanoic acid, octyl group ammonium chloride, cetyl trimethylammonium bromide, Dodecyl trimethyl ammonium chloride, polyoxyethylene sorbitol four oleic acid esters, polyoxyethylene groups tridecyl ether, 4,4 '-diaminodiphenyl oxide, 4,4 '-(hexafluoroisopropyli,ene)-two (to benzo oxygen base) pentanoic, 4,4 '-(hexafluoroisopropyli,ene) Tetra hydro Phthalic anhydride, 4,4 '-(isopropylidene two phenoxy groups) Tetra hydro Phthalic anhydride or their combination.

2. heat dissipation composite material as claimed in claim 1, further comprise the 3rd nucleocapsid particle filled composite 5 to 70 weight parts that are dispersed in the polyimide resin, its particle diameter is between the 2000nm to 10000nm, wherein, the 3rd nucleocapsid particle filled composite has inorganic core and organic shell, and its form from this first and this second nucleocapsid particle filled composite different.

3. heat dissipation composite material as claimed in claim 1, it is applied to microelectronic product or photovoltaic.