Low-conductivity resin composition and preparation method thereof

Abstract

The invention discloses a low-conductivity resin composition and a preparation method thereof, and particularly relates to the technical field of polymer composites.The composition comprises 100 parts of liquid crystal epoxy resin, 5-15 parts of polyhedral oligomeric silsesquioxane, 20-40 parts of flaky boron nitride, 10-20 parts of spherical aluminum oxide and 30-50 parts of a maleimide-allyl bisphenol A copolymer curing agent. The preparation method comprises the following steps: S1, prepolymer preparation; S2, filler hybridization; and S3, curing molding. Nano pores are constructed in a matrix through octa-aminopropyl POSS, so that the dielectric constant is effectively reduced, a heat conduction path is formed through directional arrangement of flaky boron nitride, the technical problem that low dielectricity and high heat conduction of a resin material are difficult to consider at the same time is cooperatively solved, and meanwhile, the material has high heat resistance and is particularly suitable for the fields of 5G communication, semiconductor packaging and the like.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and more specifically, to a low electrical conductivity resin composition and its preparation method. Background Technology

[0002] With the rapid development of 5G communication, artificial intelligence and high-performance computing technologies, electronic components are evolving towards high frequency, high speed, high power density and miniaturization. This has placed unprecedented demands on polymer resins, which are key insulation and encapsulation materials: they not only need to have extremely low dielectric constant and dielectric loss factor to reduce signal transmission delay and loss, but also need to have excellent thermal conductivity to ensure that the heat generated by core components such as chips can be dissipated in time. At the same time, they must have sufficiently high heat resistance to ensure reliability in high-temperature processes and service environments.

[0003] To reduce the dielectric constant of resin materials, existing technologies mainly employ the following approaches: 1. Introducing fluorine atoms: For example, using fluorinated epoxy resin or cyanate ester resin. Although this method can effectively reduce the dielectric constant, it has drawbacks such as high material cost, often reduced heat resistance, and the possibility of corrosive hydrogen fluoride being released under certain conditions. 2. Introducing porous structures: Pores are created in the resin matrix by adding pore-forming agents or using templates. However, this method usually faces problems such as difficulty in accurately controlling the pore distribution and size, the introduction of excessive pores leading to a significant deterioration in the mechanical strength of the material, and the increased hygroscopicity potentially worsening the high-frequency dielectric properties. 3. Use low-polarity polymers: such as polyphenylene ether and polyimide. Although these materials have excellent dielectric properties, they have poor compatibility with commonly used matrices such as epoxy resin, are difficult to process, and have high costs.

[0004] In addition, a common practice to improve thermal conductivity is to add high thermal conductivity fillers, such as alumina, aluminum nitride, or boron nitride, to the resin matrix. However, to achieve a high thermal conductivity path, a large amount of filler is often required, which directly leads to a sharp increase in material viscosity and deterioration in processability. Furthermore, since the filler itself contains a high dielectric constant, it will inevitably raise the overall dielectric constant of the composite material, which contradicts the original intention of achieving low dielectric constant.

[0005] In recent years, liquid crystal epoxy resins have attracted attention because their molecular chains can spontaneously orient to form an ordered structure during the curing process, thereby endowing the material with an intrinsic anisotropic high thermal conductivity pathway. However, the potential for further reduction of the dielectric constant of pure liquid crystal epoxy resins is limited, and the stability of their dielectric loss at high frequencies still needs to be improved.

[0006] Therefore, the present invention provides a low conductivity resin composition and a method for preparing the same. Summary of the Invention

[0007] In order to overcome the above-mentioned defects of the prior art, the present invention provides a low conductivity resin composition and a method for preparing the same, so as to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a low conductivity resin composition, comprising the following components by mass parts: 100 parts of liquid crystal epoxy resin, 5-15 parts of cage-type polysilsesquioxane, 20-40 parts of flake boron nitride, 10-20 parts of spherical alumina, and 30-50 parts of maleimide-allyl bisphenol A copolymer curing agent. The cage-like polysilsesquioxane is octaaminopropyl POSS, which is uniformly dispersed in the liquid crystal epoxy resin through chemical bonding to form a cross-linked network structure with nanopores. The plate-like boron nitride is oriented in the composition to form an anisotropic thermal conduction pathway.

[0009] Preferably, the liquid crystal epoxy resin is a liquid crystal compound containing biphenyl mesocrystalline groups and epoxy groups, and its epoxy value ranges from 0.5 to 0.8 eq / 100g.

[0010] Preferably, the thickness of the sheet-like boron nitride is 10-50 nm, the aspect ratio is greater than 50, and its surface is modified by a silane coupling agent, wherein the silane coupling agent is γ-aminopropyltriethoxysilane containing a benzene ring.

[0011] Preferably, the spherical alumina has a particle size of 0.5-2 μm and is used to fill the gaps between the heat-conducting pathways formed by the plate-like boron nitride.

[0012] The present invention also provides a preparation method for preparing the above-mentioned low conductivity resin composition, comprising the following steps: S1. Preparation of prepolymer: Cage-type polysilsesquioxane and liquid crystal epoxy resin are reacted at a temperature range of 70-90℃ for 1-3 hours under inert gas protection to obtain cage-type polysilsesquioxane-liquid crystal epoxy prepolymer. S2. Filler hybridization: Surface-modified lamellar boron nitride and spherical alumina are added to cage-type polysilsesquioxane-liquid crystal epoxy prepolymer, and the mixture is subjected to ultrasonic power of 400-600W and shear rate of 800-1200s. -1 Under the synergistic effect, the resin is dispersed evenly to obtain a resin mixture; S3. Curing and molding: Add maleimide-allyl bisphenol A copolymer curing agent to the resin mixture, mix evenly, and then perform step-by-step temperature curing treatment.

[0013] Preferably, in step S1, the inert gas is nitrogen or argon, the reaction temperature is 80°C, and the reaction time is 2 hours.

[0014] Preferably, the stepped temperature curing process in step S3 specifically involves: First stage: Pre-curing at 110-130℃ for 1-2 hours; Second stage: Curing at 170-190℃ for 1-3 hours to form an ordered structure; The third stage: Post-curing at 210-230℃ for 0.5-1.5 hours to complete the final cross-linking.

[0015] Preferably, the optimal conditions for the stepped temperature curing treatment are: 120℃ / 1h → 180℃ / 2h → 220℃ / 1h.

[0016] Preferably, in step S2, before adding the plate-shaped boron nitride and spherical alumina, they are first dry-mixed in a high-speed mixer at 80-100°C for 5-15 minutes to form a homogeneous composite filler.

[0017] The technical effects and advantages of this invention are as follows: 1. This invention introduces cage-like polysilsesquioxane, which is chemically bonded to liquid crystal epoxy resin to construct stable nanoscale pores in the matrix. These pores can effectively reduce the density and polarizability of the material, thereby significantly reducing the dielectric constant. At the same time, the siloxane skeleton and branched cross-linking structure of POSS jointly suppress molecular chain segment polarization and interface polarization, so that the material maintains extremely low dielectric loss at high frequencies, perfectly meeting the stringent requirements for signal integrity in applications such as 5G / 6G communication and high-performance computing. 2. This invention utilizes the inherent ordered structure of liquid crystal epoxy resin and combines the directional arrangement of surface-modified lamellar boron nitride under shear flow field to construct an efficient anisotropic thermal conduction path. At the same time, spherical alumina fills the gaps between the lamellar fillers, reducing phonon scattering and significantly improving the thermal conductivity of the material. In addition, the rigid cage structure and high cross-linking density network of POSS together endow the material with excellent heat resistance, ensuring its reliability in high-temperature service environments. 3. This invention successfully resolves the inherent contradiction between low dielectric constant and high thermal conductivity in the field of polymer materials by synergistically combining cage-type polysilsesquioxane nanoporous structure, sheet-like boron nitride directional thermally conductive network, and liquid crystal epoxy ordered matrix. It achieves thermal conductivity and heat resistance levels that are difficult to reach by traditional low dielectric materials, resulting in unexpected technical effects and providing a key material solution for next-generation electronic device packaging. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the overall preparation process of the present invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0020] Example 1 This embodiment provides a low conductivity resin composition, comprising the following components by mass parts: Liquid crystal epoxy resin: 100 parts, epoxy value 0.65 eq / 100g; Octaaminopropyl POSS: 10 parts; Surface-modified lamellar boron nitride: 30 parts, thickness 30 nm, aspect ratio 80; Spherical alumina: 15 parts, particle size 1 μm; Maleimide-allyl bisphenol A copolymer curing agent: 40 parts.

[0021] This invention also provides a preparation method for preparing the above-mentioned low conductivity resin composition, specifically including the following steps: S1, Polymer Preparation In this step, 100 parts by mass of liquid crystal epoxy resin and 10 parts by mass of octaaminopropyl POSS are added to a four-necked flask equipped with a mechanical stirrer, a condenser and a nitrogen inlet tube. Nitrogen gas is introduced to remove air, and the mixture is stirred at 300 rpm for 2 hours in an oil bath at 80°C. During the reaction, samples are taken every 30 minutes for Fourier transform infrared spectroscopy monitoring. When the intensity of the epoxy group characteristic peak decreases by about 50% and tends to stabilize, the reaction is considered to be over, and a uniform and transparent cage-shaped polysilsesquioxane-liquid crystal epoxy prepolymer is obtained. S2, Packing Hybrid In this step, 30 parts by mass of surface-modified flake boron nitride and 15 parts by mass of spherical alumina are dry-mixed in a high-speed mixer at 90°C for 10 minutes to obtain a homogeneous composite filler. This composite filler is then slowly added to the cage-shaped polysilsesquioxane-liquid crystal epoxy prepolymer obtained in step S2. Using an ultrasonic-shear synergistic dispersion system, the system is first pretreated at an ultrasonic power of 500W for 10 minutes, and then a high-speed shear emulsifier is turned on at a shear rate of 1000s. -1 Continue dispersing for 1 hour until the filler is uniformly dispersed to obtain a high-viscosity resin mixture; S3, Curing and Molding In this step, 40 parts by weight of maleimide-allyl bisphenol A copolymer curing agent are added to the resin mixture. After initial mixing by manual stirring, the mixture is mechanically stirred at 500 rpm for 15 minutes to ensure uniform mixing. The mixture is then poured into a mold coated with a release agent and placed on a flat vulcanizing machine for step-by-step curing. First stage: Pre-curing at 120℃ with a pressure of 5MPa for 1 hour; Second stage: Heat to 180℃, maintain pressure of 5MPa, and cure for 2 hours (the formation of liquid crystal texture can be observed through a polarizing microscope POM during this stage). Third stage: Continue to heat to 220℃, maintain pressure of 5MPa, and perform post-curing for 1 hour to complete the final cross-linking; After the process is completed, the material is allowed to cool naturally to below 60°C before demolding, resulting in a cured sample of the low-conductivity resin composition.

[0022] Example 2 This embodiment provides a low conductivity resin composition, comprising the following components by mass parts: 100 parts liquid crystal epoxy resin, 5 parts octaaminopropyl POSS, 20 parts surface-modified flake boron nitride, 10 parts spherical alumina, and 30 parts maleimide-allyl bisphenol A copolymer curing agent.

[0023] This embodiment also provides a preparation method for preparing the above-mentioned low conductivity resin composition. The difference between this embodiment and Example 1 is that the ultrasonic power is adjusted to 400W and the shear rate is adjusted to 800s. -1 Everything else is the same as in Example 1.

[0024] Example 3 This embodiment provides a low conductivity resin composition, comprising the following components by mass parts: 100 parts liquid crystal epoxy resin, 15 parts octaaminopropyl POSS, 40 parts surface-modified flake boron nitride, 20 parts spherical alumina, and 50 parts maleimide-allyl bisphenol A copolymer curing agent.

[0025] This embodiment also provides a preparation method for preparing the above-mentioned low conductivity resin composition. The difference between this embodiment and Example 1 is that the ultrasonic power is adjusted to 600W and the shear rate is adjusted to 1200s. -1 Everything else is the same as in Example 1.

[0026] Comparative Example 1 Comparative Example 1 was identical to Example 1 in terms of formulation and preparation method, except that octaaminopropyl POSS was not added.

[0027] Comparative Example 2 Comparative Example 2 used the same number of spherical alumina (55 parts) to completely replace the plate-like boron nitride, and the rest of the formulation and preparation method were the same as in Example 1.

[0028] Comparative Example 3 The formulation of Comparative Example 3 is exactly the same as that of Example 1, but the curing process is changed from stepped temperature curing to one-step curing: 180℃ / 4h.

[0029] Comparative Example 4 Comparative Example 4 used bisphenol A type epoxy resin with the same epoxy value to replace the liquid crystal epoxy resin, and the rest of the formulation and preparation method were the same as in Example 1.

[0030] The following performance tests were conducted on the samples prepared in Examples 1-3 and Comparative Examples 1-4, and the test methods are as follows: 1. Dielectric properties: The dielectric constant (Dk) and dielectric loss factor (Df) were measured using an impedance analyzer at a frequency of 1MHz. 2. Thermal conductivity: The thermal conductivity (λ, unit: W / m·K) at room temperature was measured using a thermal conductivity meter. 3. Heat resistance: Glass transition temperature (Tg): Tested using differential scanning calorimetry according to ASTM E1356 standard; Thermal decomposition temperature (Td5%): The temperature at which 5% mass loss is recorded by heating at 10℃ / min under a nitrogen atmosphere using a thermogravimetric analyzer.

[0031] The final test table is shown below: Dielectric constant (Dk, 1MHz) Dielectric loss (Df, 1MHz, ×10⁻³) Thermal conductivity (λ, W / m·K) Tg (°C) <![CDATA[Td5% (℃)]]> Example 1 2.38 4.2 0.42 215 410 Example 2 2.52 4.8 0.35 205 405 Example 3 2.45 4.5 0.39 210 408 Comparative Example 1 2.95 8.5 0.28 185 385 Comparative Example 2 2.81 6.8 0.19 195 395 Comparative Example 3 2.7 6 0.31 190 390 Comparative Example 4 3.4 9.5 0.21 175 375 The data in the table above shows that: 1. Example 1 achieves an excellent balance of low dielectric (Dk=2.38), low loss (Df=0.0042), high thermal conductivity (λ=0.42) and high heat resistance (Tg=215℃), which comprehensively surpasses the traditional epoxy resin system of Comparative Example 4; 2. Compared with Example 1, Comparative Example 1 without octaaminopropyl POSS showed a significant increase in dielectric constant and loss, and a decrease in thermal conductivity and heat resistance, proving that the nanoporous cross-linked network formed by octaaminopropyl POSS is the core to achieve ultra-low dielectric constant and improve thermal stability. 3. Compared with Example 1, the thermal conductivity of Comparative Example 2 without plate boron nitride decreased sharply, proving that the anisotropic thermal conduction pathway formed by the directional arrangement of plate boron nitride is the main reason for obtaining high thermal conductivity. 4. Compared with Example 1, the performance of Comparative Example 3 is inferior to that of Example 1 in all aspects, especially in dielectric loss and Tg. This shows that the stepped heating process is crucial for the formation and complete cross-linking of the liquid crystal ordered structure and is the guarantee for obtaining the best performance.

[0032] Conclusion: Through a systematic comparison of the examples and comparative examples, this invention fully demonstrates that the synergistic effect of the three elements—octaaminopropyl POSS nanoporous modification, the construction of a sheet-like boron nitride directional thermally conductive network, and the stepped temperature curing process—produces unexpected technical effects and successfully solves the industry technical problem that low dielectric materials cannot simultaneously possess high thermal conductivity and high heat resistance.

[0033] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low conductivity resin composition, characterized in that: By mass parts, it includes the following components: 100 parts of liquid crystal epoxy resin, 5-15 parts of cage-type polysilsesquioxane, 20-40 parts of flake boron nitride, 10-20 parts of spherical alumina, and 30-50 parts of maleimide-allyl bisphenol A copolymer curing agent. The cage-like polysilsesquioxane is octaaminopropyl POSS, which is uniformly dispersed in the liquid crystal epoxy resin through chemical bonding to form a cross-linked network structure with nanopores. The plate-like boron nitride is oriented in the composition to form an anisotropic thermal conduction pathway.

2. The low conductivity resin composition according to claim 1, characterized in that: The liquid crystal epoxy resin is a liquid crystal compound containing biphenyl mesocrystalline groups and epoxy groups, and its epoxy value ranges from 0.5 to 0.8 eq / 100g.

3. The low conductivity resin composition according to claim 2, characterized in that: The sheet-like boron nitride has a thickness of 10-50 nm, an aspect ratio greater than 50, and its surface is modified by a silane coupling agent, wherein the silane coupling agent is γ-aminopropyltriethoxysilane containing a benzene ring.

4. The low conductivity resin composition according to claim 3, characterized in that: The spherical alumina particles have a diameter of 0.5-2 μm and are used to fill the gaps between the heat-conducting pathways formed by the plate-like boron nitride.

5. A preparation method for preparing the low conductivity resin composition of claim 4, characterized in that: Includes the following steps: S1. Preparation of prepolymer: Cage-type polysilsesquioxane and liquid crystal epoxy resin are reacted at a temperature range of 70-90℃ for 1-3 hours under inert gas protection to obtain cage-type polysilsesquioxane-liquid crystal epoxy prepolymer. S2. Filler hybridization: Surface-modified lamellar boron nitride and spherical alumina are added to cage-type polysilsesquioxane-liquid crystal epoxy prepolymer, and the mixture is subjected to ultrasonic power of 400-600W and shear rate of 800-1200s. -1 Under the synergistic effect, the resin is dispersed evenly to obtain a resin mixture; S3. Curing and molding: Add maleimide-allyl bisphenol A copolymer curing agent to the resin mixture, mix evenly, and then perform step-by-step temperature curing treatment.

6. The preparation method according to claim 5, characterized in that: In step S1, the inert gas is nitrogen or argon, the reaction temperature is 80℃, and the reaction time is 2h.

7. The preparation method according to claim 6, characterized in that: The stepped temperature curing process in step S3 is as follows: First stage: Pre-curing at 110-130℃ for 1-2 hours; Second stage: Curing at 170-190℃ for 1-3 hours to form an ordered structure; The third stage: Post-curing at 210-230℃ for 0.5-1.5 hours to complete the final cross-linking.

8. The preparation method according to claim 7, characterized in that: The optimal conditions for the stepped temperature curing process are: 120℃ / 1h → 180℃ / 2h → 220℃ / 1h.

9. The preparation method according to claim 8, characterized in that: In step S2, before being added, the plate-shaped boron nitride and spherical alumina are dry-mixed in a high-speed mixer at 80-100°C for 5-15 minutes to form a homogeneous composite filler.

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