CN-122011773-A - Dynamic reworkable high-heat-conductivity low-dielectric composite material and preparation method and application thereof

CN122011773ACN 122011773 ACN122011773 ACN 122011773ACN-122011773-A

Abstract

The invention relates to a dynamic reworkable high-heat-conductivity low-dielectric composite material and a preparation method and application thereof, belonging to the technical field of electronic advanced packaging and high-frequency substrate thermal management materials. The invention eliminates the traditional hydroxyl-containing binder, utilizes the self-condensation reaction of boric acid precursors under the condition of bidirectional freezing concentration to construct a 3D boron nitride bidirectional orientation framework crosslinked by a boron-oxygen hexacycle in situ, synthesizes novel polysiloxane with a discotic liquid crystal side chain and a dynamic borate network at the same time, and utilizes a vacuum-pressure alternating auxiliary dipping process to induce the discotic liquid crystal to be assembled on the surface of the framework in an epitaxial manner and carry out in-situ addition curing without byproducts. The invention overcomes the defect that the traditional packaging material cannot give consideration to the high heat conduction of the Z axis, the ultra-low dielectric loss of the high frequency and the industry pain point of non-reworkability after solidification, and is particularly suitable for the fields of 5G/6G high-frequency communication and 2.5D/3D Chiplet advanced system-in-package.

Inventors

NIU BO
WANG YOUYI
LONG DONGHUI
Shao Aijia
YAN CHANGSHENG
ZHANG FENGCHENG
GAO JINGWEN
LI YUZHU
CAO YU

Assignees

华东理工大学

Dates

Publication Date: 20260512
Application Date: 20260410

Claims (10)

1. The preparation method of the dynamic reworkable high-heat-conductivity low-dielectric composite material is characterized by comprising the following steps of: S1, dispersing a two-dimensional boron nitride nanosheet and a boric acid precursor in deionized water to form slurry, placing the slurry in a bidirectional temperature gradient die for directional freezing, and then forming a 3D-BN sponge skeleton after freeze drying and heating thermal annealing; S2, preparing a single-end disk-shaped liquid crystal monomer with an alkenyl flexible tail by taking 2,3,6,7,10, 11-hexahexyloxy benzotriphenylene as a precursor through controllable cleavage and etherification reaction; s3, dissolving polymethyl hydrogen-containing siloxane, the discotic liquid crystal monomer and the dienyl dynamic borate crosslinking agent in the step S2 in an organic solvent, and adding a platinum complex catalyst to prepare discotic liquid crystal organosilicon impregnating solution; S4, injecting the discoid liquid crystal organic silicon impregnating solution into the 3D-BN sponge framework, taking out the 3D-BN sponge framework after impregnation saturation by a vacuum-pressure alternating process, standing at room temperature for 1-2 h, and then heating and curing to obtain the dynamic reworkable high-heat-conductivity low-dielectric composite material; Wherein the boric acid precursor is one or more of 1, 4-phenyldiboronic acid, 4' -biphenyl diboronic acid and 1, 4-naphthalene diboronic acid.
2. The method for preparing the dynamic reworkable high-heat-conductivity low-dielectric composite material is characterized in that in the step S1, the mass fraction of the two-dimensional boron nitride nano-sheet in the slurry is 10-20 wt%, and the addition amount of the boric acid precursor is 2-10 wt% of the total mass of the two-dimensional boron nitride nano-sheet; and/or the condition of freeze drying is that the temperature is-50 ℃, the absolute pressure is less than 10 Pa, and the drying time is not less than 48 h; And/or the temperature-rising thermal annealing method comprises the steps of rising the temperature to 110-150 ℃ at the speed of 1-5 ℃ per minute and preserving the temperature for 2-4 hours.
3. The method for preparing the dynamic reworkable high-heat-conductivity low-dielectric composite material according to claim 1 is characterized in that in the step S2, the method for synthesizing the discotic liquid crystal monomer is characterized in that 2,3,6,7,10, 11-hexahexyloxybenzotriphenylene and boron tribromide are subjected to cleavage reaction according to the molar ratio of 1:1.1-1.5 to prepare a monohydroxy intermediate, and the monohydroxy intermediate and 11-bromo-1-undecene or 6-bromo-1-hexene are subjected to etherification reaction according to the molar ratio of 1:1.2-2.0 to prepare the discotic liquid crystal monomer.
4. The method for preparing the dynamic reworkable high-heat-conductivity low-dielectric composite material is characterized in that in the step S3, the dienyl dynamic borate crosslinking agent is prepared by a dehydration condensation reaction of a diboronic acid compound and an alkenyl-containing diol compound, the diboronic acid compound comprises one or more of 1, 4-phenyldiboronic acid and 4,4' -biphenyldiboronic acid, the alkenyl-containing diol compound comprises one or more of propylene oxypropylene glycol and 5-ethylene-1, 2-diol, and the molar ratio of the diboronic acid compound to the alkenyl-containing diol compound is 1:2-2.1.
5. The method for preparing the dynamic reworkable high-heat-conductivity low-dielectric composite material according to claim 1, wherein in the step S3, the molar ratio of Si-H bonds to discotic liquid crystal monomer double bonds to cross-linking agent double bonds is controlled to be 1:0.2-0.6:0.4-0.8.
6. The method for preparing the dynamic reworkable high-heat-conductivity low-dielectric composite material according to claim 1, wherein in the step S4, the operation method of the vacuum-pressure alternating process is that firstly, the 3D-BN sponge skeleton is vacuumized until the absolute pressure is less than or equal to 50 mbar and kept for 20-45 min, and after the discoid liquid crystal organosilicon impregnating solution is injected, positive pressure of 0.1-0.6 MPa is applied for 20-240 min.
7. The method for preparing the dynamic reworkable high-heat-conductivity low-dielectric composite material according to claim 1, wherein in the step S4, the reaction condition of heating and curing is that the temperature is raised to 60-80 ℃ at a rate of 1-5 ℃ per minute and kept for 2-4 hours, and then the temperature is raised to 120-150 ℃ and kept for 2-4 hours.
8. The preparation method of the dynamic reworkable high-heat-conductivity low-dielectric composite material is characterized in that the composite material can be subjected to heating treatment by a composite synergistic repair liquid, degraded into a gel state, and subjected to centrifugal washing by waste liquid after washing to recover two-dimensional boron nitride, wherein the composite synergistic repair liquid consists of a good solvent and a dynamic bond breaking agent according to a volume ratio of 1-3:1, the good solvent is one or more of toluene and D-limonene, and the dynamic bond breaking agent is one or more of ethylene glycol and 1, 3-propylene glycol; The temperature of the heating treatment is 60-80 ℃, the time is 15-40 min, and the rotating speed of the centrifugal washing is more than or equal to 3000 rpm.
9. A dynamic reworkable high-heat-conductivity and low-dielectric composite material is characterized by being prepared by the preparation method of the dynamic reworkable high-heat-conductivity and low-dielectric composite material according to any one of claims 1-8, wherein the composite material has a dual dynamic covalent interpenetrating network structure of inorganic boron-oxygen hexacyclic crosslinked bidirectional 3D-BN sponge skeleton/organic boric acid ester crosslinked discoid liquid crystal polysiloxane, the Z-axis heat conductivity of the composite material is 2.70-6.80W/m.K under the loading of 10-20 wt.% of filler, the dielectric constant is 2.82-3.05 at the frequency of 10 GHz, the dielectric loss is less than or equal to 0.0022, the thermal expansion coefficient is 80-135 ppm/° C, and the intelligent gel resolution can be completed in a composite synergistic reworking liquid of 60-80 ℃ within 15-40 min.
10. An application of a dynamic reworkable high thermal conductivity and low dielectric composite material, which is characterized in that the composite material according to claim 9 is applied to the fields of 5G/6G high frequency communication and 2.5D/3D Chiplet advanced system in package.

Description

Dynamic reworkable high-heat-conductivity low-dielectric composite material and preparation method and application thereof Technical Field The invention relates to the technical field of electronic advanced packaging and high-frequency substrate thermal management materials, in particular to a dynamic reworkable high-heat-conductivity low-dielectric composite material, and a preparation method and application thereof. Background With the rapid development of fifth generation (5G) and even sixth generation (6G) mobile communication technologies, a high-frequency millimeter wave band (generally referred to as 30GHz to 300 GHz) has become a core band for improving data transmission rate and system capacity. Meanwhile, in order to break through the physical and economic limits of moore's law, advanced three-dimensional stacked packaging schemes such as Chip-on-Wafer-on-Substrate (CoWoS) and InFO (INTEGRATED FAN-Out) based on Chiplet (core) heterogeneous integration technology have become mainstream paths for implementing system-level integration such as high-power processor and high-bandwidth memory (HBM). The convergence of these two technological trends results in an exponential rise in the heat flux density within the package structure. In particular, the close stacking of a plurality of high-computation-force bare chips (Die) in the vertical direction (Z axis) enables the heat generation sources to be highly concentrated, heat is mainly conducted along the thickness direction (Z axis), a serious 'heat accumulation' effect is formed inside the packaging body, and unprecedented severe requirements are imposed on the vertical heat conduction capability of the material. At present, the mainstream electronic packaging heat-conducting material mostly adopts a composite material system of organic silicon or epoxy resin and high heat-conducting inorganic filler (such as alumina, boron nitride, silicon nitride and the like) which are blended. However, in the face of the dual challenge of 5G/6G millimeter wave communication and Chiplet three-dimensional stacking, the traditional blending system exposes three fatal pain points, namely, firstly, filler particles are randomly and randomly distributed in a resin matrix in a sea-island structure, and a continuous and efficient heat conduction path is difficult to form in a vital Z-axis direction, so that the Z-axis heat conduction coefficient of the composite material is far lower than a theoretical value, and the requirement of rapid heat dissipation under a three-dimensional stacking structure cannot be met. Second, the high loading strategy for pursuing high thermal conductivity inevitably results in a large number of interfacial microporosity between the resin matrix and the filler particles, and between the filler particles. Under the action of a high-frequency alternating electric field, space charges can be accumulated at the defect interfaces, and a significant Maxwell-Wagner interface polarization effect is caused. The effect can sharply deteriorate the high-frequency dielectric property of the material, and is particularly shown by the large increase of dielectric constant (Dk) and dielectric loss factor (Df), which not only can lead to serious delay and attenuation of millimeter wave signals in the transmission process, but also can generate extra heat due to dielectric loss, thereby forming positive feedback circulation with deteriorated thermo-electric property and seriously restricting the application prospect in the frequency band of 6G and higher. Third, and most critical, conventional thermally conductive fillers form a permanent, irreversible three-dimensional chemical network upon thermal curing and crosslinking of the encapsulating resin (e.g., epoxy resin). This means that the entire package is a compact, integrated structure. In expensive heterogeneous integrated package modules (e.g., HBM-containing CPU/GPU packages), if a single chip (Chiplet) fails, the entire thousands to tens of thousands dollars worth of packages will be forced to be scrapped, resulting in significant economic and resource waste, as the package material cannot be removed intact to expose the underlying chip for repair or replacement. This "non-reworkable" feature is counter to the high yield and high value reuse concepts pursued in the high-end chip manufacturing arts. To ameliorate the deficiencies of the traditional systems, the industry has attempted a variety of modification schemes. For example, the liquid crystal epoxy resin is used for replacing the common epoxy resin to improve the heat conduction and mechanical properties in a single direction (such as a Z axis). The dielectric constant and loss of the system are reduced by introducing low polarity functional groups or mesoporous materials. However, the intrinsic polarity of the existing liquid crystal epoxy resin is still high, and the requirement of the 6G millimeter wave frequency band on extremely low dielectric lo