Microwave radio frequency element phase insulation paste and preparation method thereof

Abstract

The invention provides microwave radio frequency element phase insulation paste and a preparation method thereof.The preparation method comprises the steps that a resin matrix, a diluent, filler, a coupling agent and a curing agent are obtained, the pretreated filler is obtained by pretreating the filler, the resin matrix, the diluent and the coupling agent are mixed to obtain a first mixture, and the first mixture is mixed with the curing agent to obtain the microwave radio frequency element phase insulation paste. Dispersing the pretreated filler into the first mixture to obtain a second mixture, adding the curing agent into the second mixture to obtain a third mixture, and curing the third mixture to obtain the phase insulation paste. According to the low-dielectric microwave radio frequency element insulating glue provided by the invention, the dielectric constant (Dk is less than or equal to 2.3) is reduced through synergism of the novolac epoxy resin and the nanofiller, the wide temperature range stability (-65 DEG C to 200 DEG C) is ensured by adopting a stepped curing process, and the low-dielectric microwave radio frequency element insulating glue is suitable for high-frequency transmission scenes such as 5G high-frequency signals and radar modules.

Description

Technical Field

[0001] The present invention relates to the technical field of insulating adhesives, and in particular to a microwave radio frequency component phase insulating adhesive and a preparation method thereof. Background Art

[0002] Microwave RF components have extremely strict requirements on the performance of insulating materials. Traditional insulating adhesives often have difficulty meeting multiple indicators such as low dielectric constant, low loss factor, high shear strength and wide temperature range in high-frequency environments. There are mutual constraints between these performance indicators. For example, improving temperature resistance may lead to a decrease in dielectric performance, and increasing shear strength may affect the loss factor. Therefore, how to find a balance between these key performance indicators has become the core challenge in the research and development of insulating adhesives for microwave RF components. At the same time, the formula design and preparation process of insulating adhesives also directly affect their final performance. How to optimize the ratio between the resin matrix and the nanofiller, and how to improve the uniformity of the dispersion of fillers in the resin through reasonable pretreatment and dispersion technology are all technical problems that need to be solved urgently. In addition, due to the complex and changeable working environment of microwave RF components, how to establish a scientific and comprehensive performance evaluation method to accurately judge whether the insulating adhesive meets the actual application requirements has also become a key issue restricting its research and development and application. The solution to these technical challenges is not only related to the improvement of the performance of insulating adhesives, but also directly affects the overall performance and reliability of microwave RF components. Summary of the invention

[0003] The present invention provides a microwave radio frequency component phase insulating adhesive and a preparation method thereof, which mainly comprises:

[0004] Obtain a resin matrix, a diluent, a filler, a coupling agent and a curing agent, obtain a pretreated filler by pretreating the filler, mix the resin matrix with the diluent and the coupling agent to obtain a first mixture, disperse the pretreated filler into the first mixture to obtain a second mixture, add the curing agent to the second mixture to obtain a third mixture, and obtain the phase insulation adhesive by curing the third mixture.

[0005] Furthermore, the process of obtaining a resin matrix, a diluent, a filler, a coupling agent and a curing agent includes: obtaining a phenolic epoxy resin as the resin matrix, obtaining propylene oxide benzyl ether as the diluent, obtaining nano-silica and fumed alumina as the filler, obtaining γ-glycidyloxypropyltrimethoxysilane as the coupling agent, and obtaining methylhexahydrophthalic anhydride as the curing agent.

[0006] Furthermore, the method of obtaining the pretreated filler by pretreating the filler includes: obtaining nano-silicon dioxide in the filler, vacuum drying the nano-silicon dioxide at a preset temperature, and obtaining the pretreated nano-silicon dioxide as a part of the pretreated filler.

[0007] Furthermore, the step of mixing the resin matrix with the diluent and the coupling agent to obtain a first mixture includes: obtaining the resin matrix, heating and melting the resin matrix at a preset temperature, adding the diluent and the coupling agent to the melted resin matrix, and stirring at a preset temperature for a preset time to obtain the first mixture.

[0008] Furthermore, dispersing the pretreated filler into the first mixture to obtain the second mixture includes: obtaining the pretreated filler, adding the pretreated filler into the first mixture in batches, and dispersing for a preset time at a preset power by an ultrasonic dispersing device to obtain the second mixture.

[0009] Furthermore, the adding of the curing agent to the second mixture to obtain the third mixture includes: obtaining the curing agent, adding the curing agent to the second mixture, and degassing the mixture after adding the curing agent for a preset time by vacuum degassing equipment to obtain the third mixture.

[0010] Furthermore, the phase insulating glue is obtained by curing the third mixture, including: obtaining the third mixture, placing the third mixture in a preset mold, and curing the third mixture through a step curing process, wherein the step curing process includes a combination of multiple preset temperatures and corresponding preset times to obtain the phase insulating glue.

[0011] The present invention further provides a microwave radio frequency component phase insulating adhesive, which is prepared using the aforementioned microwave radio frequency component phase insulating adhesive preparation method.

[0012] The technical solution provided by the embodiment of the present invention may have the following beneficial effects:

[0013] The present invention discloses a method for preparing a phase insulating adhesive. The method solves the problems of local discharge and electric tree in traditional phase insulating adhesive in high-voltage power equipment by pretreating fillers, mixing resin matrix with diluent and coupling agent, dispersing pretreated fillers, adding curing agent and step curing process. The present invention adopts phenolic epoxy resin as matrix, propylene oxide benzyl ether as diluent, nano silicon dioxide and fumed alumina as fillers, γ-glycidyl ether oxypropyl trimethoxy silane as coupling agent, and methyl hexahydrophthalic anhydride as curing agent. The dielectric strength and thermal stability of the phase insulating adhesive are effectively improved by vacuum drying pretreatment of nano silicon dioxide, ultrasonic dispersion technology and vacuum degassing treatment, and step curing process, and the insulation performance and service life of the phase insulating adhesive in high-voltage power equipment are significantly improved. The present invention provides a low-dielectric microwave radio frequency component insulating adhesive, which synergistically reduces the dielectric constant (Dk≤2.3) by phenolic epoxy resin and nanofiller, and adopts a step curing process to ensure stability in a wide temperature range (-65°C to 200°C). It is suitable for high-frequency transmission scenarios such as 5G high-frequency signals and radar modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The present invention is a flow chart of a microwave radio frequency component phase insulating adhesive and a preparation method thereof. DETAILED DESCRIPTION

[0015] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] like Figure 1 In this embodiment, a microwave radio frequency component phase insulating adhesive and a preparation method thereof may specifically include:

[0017] Obtain a resin matrix, a diluent, a filler, a coupling agent and a curing agent, obtain a pretreated filler by pretreating the filler, mix the resin matrix with the diluent and the coupling agent to obtain a first mixture, disperse the pretreated filler into the first mixture to obtain a second mixture, add the curing agent to the second mixture to obtain a third mixture, and obtain the phase insulation adhesive by curing the third mixture.

[0018] When obtaining the resin matrix, phenolic epoxy resin is selected because of its high benzene ring content in its molecular structure and controllable cross-linking density, which can balance mechanical strength and dielectric properties. In the specific implementation, a resin with an epoxy equivalent of 180g / eq is used, and its viscosity is 800mPa·s at 60°C. It is melted and flowed by heating to 60°C to facilitate subsequent mixing. The benzene ring structure of the resin can reduce the vibration of polar groups, thereby reducing dielectric loss. When propylene oxide benzyl ether is selected as the diluent, its addition amount is 15wt%, which can reduce the viscosity of the system from 800mPa·s to 450mPa·s (25°C). The diluent contains a non-polar benzyl structure, which can reduce the intermolecular dipole interaction and further reduce Df to below 0.007. In actual operation, it is necessary to slowly add and stir after the resin is melted to avoid phase separation caused by excessive local concentration. In the filler pretreatment stage, nano-silica needs to be vacuum dried at 120°C for 2 hours to remove surface hydroxyl adsorbed water. Untreated fillers will increase Dk by more than 0.2 due to dipole losses caused by the polarity of water molecules. The specific surface area of ​​the filler after drying remains at 200 m 2 / g, ensuring that the subsequent coupling agent can fully cover its surface. The addition amount of coupling agent γ-glycidyl ether oxypropyl trimethoxysilane is 2wt%, and its methoxyl group condenses with the hydroxyl group on the filler surface after hydrolysis, while the epoxy group reacts with the resin. This process needs to be stirred at 60°C for 30 minutes to allow the coupling agent to form a monolayer coverage to avoid excessive addition leading to self-polymerization. The treated filler-resin interface bonding strength is increased by 30%, and Dk is reduced by 0.1. Filler dispersion uses 500W ultrasound for 1 hour to form a uniform network of nano-silica in the resin. Ultrasonic cavitation can break up filler agglomerates. When the particle size is controlled at 80nm, the filler spacing is 150-200nm, and the electromagnetic wave scattering loss is minimal at this scale. The addition of fumed alumina fills the gap in the silica network and increases the thermal conductivity to 0.8W / (m·K). The curing agent methyl hexahydrophthalic anhydride is added at 25phr, and its anhydride group has a moderate reaction rate with the epoxy group. Vacuum degassing for 10 minutes can remove the microbubbles introduced by stirring. Residual bubbles will cause Dk to fluctuate by ±0.05. The curing adopts a step-by-step temperature increase process: 80°C pre-curing to form a branched structure, 120°C to complete the main cross-linking, and 150°C post-curing to eliminate internal stress. The final curing degree reaches more than 98%. In the final cured product, the nanofiller forms a three-dimensional heat conduction path, reducing the thermal expansion coefficient to 35ppm / °C (-65°C ~ 200°C). The rigid skeleton of phenolic epoxy resin and the flexible ether bond work synergistically, with a shear strength of 22MPa, and the dielectric constant is stabilized at 2.3±0.05 (10GHz test frequency).

[0019] Performance data:

[0020]

[0021]

[0022] S101, the process of obtaining a resin matrix, a diluent, a filler, a coupling agent and a curing agent comprises: obtaining a phenolic epoxy resin as the resin matrix, obtaining propylene oxide benzyl ether as the diluent, obtaining nano-silica and fumed alumina as the filler, obtaining γ-glycidyloxypropyltrimethoxysilane as the coupling agent, and obtaining methylhexahydrophthalic anhydride as the curing agent.

[0023] S102, obtaining the pretreated filler by pretreating the filler, comprising: obtaining nano-silicon dioxide in the filler, vacuum drying the nano-silicon dioxide at a preset temperature, and obtaining the pretreated nano-silicon dioxide as a part of the pretreated filler.

[0024] Necessity of pretreatment of fillers: Nano-silica is a key filler for insulating glue. Its surface is easy to absorb water and organic impurities. If it is not removed in advance, the interfacial bonding force between the filler and the resin matrix will be reduced, resulting in pores or agglomeration in the glue layer after curing, affecting the dielectric properties. Vacuum drying can effectively remove physically adsorbed water and low-boiling impurities to ensure subsequent dispersion uniformity. Principle of vacuum drying temperature setting: 120℃ is selected as the drying temperature based on the stability of hydroxyl (-OH) on the surface of nano-silica and the energy barrier for water desorption. It is difficult to completely remove bound water below 100℃, while exceeding 150℃ may cause excessive condensation of hydroxyl groups on the surface of particles, which will reduce the modification effect of the coupling agent. Experiments show that vacuum drying at 120℃ for 2 hours can reduce the water content to below 0.1wt%. The role of vacuum environment: Vacuum conditions (such as -0.095MPa) can reduce the boiling point of water, accelerate its evaporation, and avoid oxidation of nanoparticles at high temperatures. Compared with normal pressure drying, vacuum treatment can shorten the drying time by 40%, and the particle size distribution is more concentrated (such as D50 changes from the original 80nm to 82nm after drying, with a change rate of ≤2.5%). Example of the effect of filler pretreatment on performance: Nano-silica dried in vacuum at 120°C has improved the stability of the suspension formed in the resin after ultrasonic dispersion, and the sedimentation amount after standing for 24 hours has dropped from 15% before drying to 3%. The dielectric constant (Dk) of the colloid after curing is reduced by 0.2, because the drying treatment reduces the polarization loss caused by interface defects. Analysis of the linkage of process parameters: Drying time and temperature need to be controlled in a coordinated manner. If the time is shortened to 1 hour, even if the temperature rises to 130°C, the residual moisture in the filler will still reach 0.5wt%, resulting in bubbles in the cured glue at a high temperature of 200°C; and extending it to 3 hours can further remove water, but it will reduce production efficiency due to increased energy consumption. Comprehensive evaluation shows that 2 hours is the optimal solution. Cooperative pretreatment with other fillers: Although fumed alumina does not require vacuum drying, it needs to be dehydrated in a 150°C oven for 1 hour. The difference in pretreatment between the two is due to the low activity of hydroxyl groups on the surface of alumina, and its large particle size (1-3μm), long water diffusion path, and higher temperature required to drive desorption. Industrial implementation case: The production line uses a double cone vacuum dryer to batch process 10kg of nano-silica, set at 120℃, -0.09MPa, and use a spiral stirrer to increase the heat conduction efficiency by 30%. The specific surface area of ​​the treated filler is increased from 210m 2 / g restore to 205m 2 / g (close to the theoretical value), proving that the pore structure is not destroyed.

[0025] S103, mixing the resin matrix with the diluent and the coupling agent to obtain a first mixture, comprising: obtaining the resin matrix, heating and melting the resin matrix at a preset temperature, adding the diluent and the coupling agent to the melted resin matrix, and stirring at a preset temperature for a preset time to obtain the first mixture.

[0026] In the resin matrix heating and melting step, the preset temperature is set to 60°C based on the glass transition temperature (Tg) and melting characteristics of the novolac epoxy resin. When the temperature is lower than 50°C, the resin viscosity is too high to flow, and exceeding 70°C may cause the diluent to volatilize.

[0027] For example, 80 grams of phenolic epoxy resin (epoxy equivalent 180g / eq) was placed in a constant temperature oil bath and heated at 60°C for 20 minutes until it was completely melted into a transparent liquid. At this time, the viscosity dropped from the initial 2500mPa·s to 800mPa·s. Propylene oxide benzyl ether was selected as the diluent addition link. The synergistic effect of the benzene ring and the epoxy group in its molecular structure can reduce the polarity of the system. In the specific operation, 15wt% of the diluent was added to the molten resin three times: after the first addition of 5%, it was stirred for 5 minutes to reduce the interfacial tension, and the subsequent two additions were added at an interval of 3 minutes. The final mixed viscosity was stabilized at 450mPa·s (measured at 25°C). Adding in batches can avoid phase separation caused by excessive local concentration. The timing of adding the coupling agent γ-glycidyloxypropyltrimethoxysilane is related to temperature control. When 2wt% of the coupling agent is added when the resin-diluent mixture is kept at 60°C, the methoxy hydrolysis rate is optimal. Experiments show that if the temperature is lower than 55°C, the silane coupling agent is not fully hydrolyzed; if it is higher than 65°C, the condensation reaction is too fast to form gel particles. Continue stirring for 30 minutes to allow the coupling agent to be fully grafted onto the resin molecular chain. Infrared spectrum detection shows that the Si-OC characteristic peak appears at 1100cm-1. The setting of the preset time for constant temperature stirring is based on the principle of fluid dynamics. Using an anchor stirring paddle to mix at a speed of 200rpm, the system can reach molecular uniformity in 30 minutes. Through online viscometer monitoring, it was found that the viscosity dropped significantly in the first 15 minutes (from 800mPa·s to 500mPa·s), and the change slowed down in the next 15 minutes, indicating that a stable homogeneous system has been formed at this time. The formation standard of the first mixture is determined by three indicators: no visual particle suspension, viscometer reading fluctuation is less than ±3%, and DSC detection shows a single glass transition peak. For example, after a batch of products was stirred at 60°C for 35 minutes, the viscosity was measured to be 480 mPa·s and FTIR showed that the characteristic peak intensity ratio of resin / coupling agent was stable at 1:0.22, which was determined to be a qualified mixture.

[0028] S104, dispersing the pretreated filler into the first mixture to obtain a second mixture, comprising: obtaining the pretreated filler, adding the pretreated filler into the first mixture in batches, and dispersing the pretreated filler for a preset time at a preset power by an ultrasonic dispersing device to obtain the second mixture.

[0029] In the filler pretreatment step, nano-silica is vacuum dried at 120°C for 2 hours to remove moisture and volatile impurities adsorbed on the surface. Moisture will cause filler agglomeration and affect the dispersion effect; the vacuum environment can avoid high-temperature oxidation.

[0030] For example, if the moisture content of the filler exceeds 0.5%, "pseudo-dispersion" will occur during subsequent ultrasonic dispersion, and micron-sized aggregates will still exist, which will eventually cause the dielectric loss of the colloid to rise to more than 0.015 after curing. Adding fillers in batches can avoid excessive local concentration caused by one-time feeding.

[0031] For example, add 5wt% nano-silica for the first time, and then add the remaining 5wt% after 20 minutes of ultrasonic dispersion, which is completed in 3 times. If 10wt% is added at one time, the filler will form "filler islands" due to insufficient shear force, causing the dielectric constant to fluctuate by ±0.2. The selection of 500W power for ultrasonic dispersion equipment is based on the matching relationship between filler particle size and resin viscosity. If the power is too low (such as 300W), the van der Waals force between nanoparticles cannot be broken, and 20% agglomerates will remain in silica with a particle size of 50nm; if the power is too high (such as 700W), it may cause local thermal degradation of the resin and generate bubbles. The preset dispersion time of 1 hour is an optimized value obtained by monitoring with a dynamic light scattering instrument.

[0032] For example, the filler particle size distribution is 50-200nm after 30 minutes of dispersion, and it can be stabilized at 50-100nm after being extended to 1 hour. Insufficient time will lead to incomplete filler network structure and a 15% decrease in shear strength. The temperature needs to be controlled at 60±5℃ during ultrasonic dispersion. Too high temperature will accelerate the volatilization of diluent and increase the viscosity to above 600mPa·s; too low temperature will cause poor resin fluidity and nano-silica will find it difficult to penetrate the gap between resin molecular chains. The timing of adding fumed alumina is in the middle of ultrasonic dispersion (i.e. after the second batch of nano-silica is added). Because its particle size is smaller (30nm), it will be wrapped by silica if added too early and lose its surface modification effect. Experiments show that adding it at this time can reduce Df by 0.002. Vacuum degassing is carried out immediately after the dispersion is completed, because the diameter of the microbubbles generated by ultrasound is less than 50μm. If the delay exceeds 10 minutes, the bubbles will re-aggregate due to the thixotropy of the resin, and form cavities with a diameter of >100μm after curing, which will reduce the shear strength to below 18MPa.

[0033] S105, adding the curing agent to the second mixture to obtain a third mixture, comprising: obtaining the curing agent, adding the curing agent to the second mixture, and degassing the mixture after adding the curing agent for a preset time by a vacuum degassing device to obtain the third mixture.

[0034] The process of obtaining the curing agent needs to ensure that its chemical stability matches its activity. Taking methyl hexahydrophthalic anhydride as an example, it needs to be weighed in a dry environment (humidity ≤ 30% RH) to avoid moisture absorption and decreased curing efficiency. The amount added is 20-30phr (per hundred parts of resin), which can balance the curing speed and the mechanical properties of the colloid. When adding the curing agent to the second mixture, constant temperature stirring (60℃±2℃) is used to prevent local overheating from inducing pre-curing. For example, low-speed mechanical stirring (200-300rpm) is used with anchor blades to ensure uniform dispersion while avoiding the introduction of bubbles. Vacuum degassing is a key step in eliminating microbubbles. Set the vacuum degree to -0.095MPa to -0.1MPa, and the degassing time is 10 minutes. Under this parameter, bubbles with a diameter of >50μm can be completely removed to avoid the formation of dielectric performance defects after curing. The degassing equipment needs to be equipped with a condensation trap to capture volatile components. The third mixture formed after degassing needs to meet the viscosity threshold (400-600mPa·s, 25°C). For example, by detecting with a rotational viscometer, if it exceeds the range, a diluent (propylene oxide benzyl ether) can be added to adjust, but the total amount does not exceed the upper limit of the formula 20wt%. The process principle of vacuum degassing is that the volume of bubbles expands to rupture under negative pressure conditions. Experiments show that 10 minutes is enough for bubbles to migrate to the liquid surface, while longer time may cause low molecular weight components of the resin to volatilize, affecting the density of the cured network. The technical effect of this step is reflected in: when the residual amount of bubbles is less than 0.1vol%, the dielectric loss factor (Df) of the cured colloid can be reduced by more than 15%; at the same time, the degassing treatment can improve the uniformity of filler distribution and control the size of nano-silica agglomerates below 200nm.

[0035] S106, obtaining the phase insulating glue by curing the third mixture, comprising: obtaining the third mixture, placing the third mixture in a preset mold, and curing the third mixture by a step curing process, wherein the step curing process includes a combination of multiple preset temperatures and corresponding preset times to obtain the phase insulating glue.

[0036] The third mixture is obtained and placed in a preset mold. The purpose of this step is to ensure that the mixture can maintain the desired shape and size during the curing process. The preset mold is usually designed according to the specific structure of the microwave RF component to ensure that the insulating glue can accurately fill the key parts of the component.

[0037] For example, the mold can be designed to match the specific shape of the filter or antenna, so that the insulating glue can fit tightly to the component after curing to avoid gaps or bubbles. The third mixture is cured by a step curing process, which includes a combination of multiple preset temperatures and corresponding preset times. The core idea of ​​step curing is to gradually increase the temperature so that the mixture completes different reaction stages at different temperatures, thereby ensuring the uniformity and stability of the curing process.

[0038] For example, the first stage of low-temperature curing (such as 80℃ / 1h) is mainly used for preliminary cross-linking to prevent the mixture from reacting too quickly at high temperature and causing internal stress concentration; the second stage of intermediate temperature curing (such as 120℃ / 2h) is used to further promote the combination of resin and filler and improve the mechanical strength of the material; the third stage of high-temperature curing (such as 150℃ / 1h) is used for complete curing to ensure the stability of the material in a high temperature environment. The specific temperature and time combination of the step curing process needs to be optimized according to the characteristics of the material.

[0039] For example, the curing reaction of phenolic epoxy resin is sensitive to temperature. Too high a temperature may cause the resin to decompose, while too low a temperature may cause incomplete curing. Therefore, through the step curing process, the cross-linking reaction of the resin can be gradually completed at different temperatures to avoid the degradation of material properties caused by sudden temperature changes.

[0040] For example, initial curing at 80°C can ensure uniform mixing of the resin and filler; intermediate curing at 120°C can promote full bonding of the resin and filler; and final curing at 150°C can ensure the stability of the material in a high temperature environment. Another advantage of the step curing process is that it can reduce stress concentration inside the material. During the curing process, the volume of the resin changes. If the curing speed is too fast, it may cause stress inside the material, thus affecting its mechanical and dielectric properties. Through the step curing process, the stress inside the material can be gradually released to ensure that the cured material has a uniform structure and stable performance.

[0041] For example, preliminary curing at 80°C can slow down the cross-linking speed of the resin and reduce the generation of internal stress; subsequent curing at 120°C and 150°C can gradually release the generated stress and ensure the overall performance of the material. The step curing process can also improve the temperature resistance of the material. By gradually curing at different temperatures, the stability of the material in a high temperature environment can be ensured.

[0042] For example, final curing at 150°C can ensure that the material will not decompose or deform in a high temperature environment, thus meeting the use requirements of microwave RF components in a high temperature environment. In addition, the step curing process can also improve the dielectric properties of the material. Through gradual curing, it can ensure the full combination of resin and filler, reduce the dielectric constant and dielectric loss factor of the material, and thus reduce interference with RF signals.

[0043] Example 1

[0044] Take 70 wt % of phenolic epoxy resin (epoxy equivalent 170-190 g / eq), 15 wt % of propylene oxide benzyl ether, and 2 wt % of coupling agent and mix them.

[0045] Add 10wt% nano-SiO 2 (75nm), 3wt% gas phase Al 2 O 3 , ultrasonic dispersion for 1h.

[0046] Add 25phr of curing agent, degas and pour into PTFE mold.

[0047] Step curing: 80℃ / 1h→120℃ / 2h→150℃ / 1h.

[0048] Example 2

[0049] Take 70 wt % of phenolic epoxy resin (epoxy equivalent 170-190 g / eq), 15 wt % of propylene oxide benzyl ether, and 2 wt % of coupling agent and mix them.

[0050] Add 10wt% nano-SiO 2 (75nm), 3wt% gas phase Al 2 O 3 , ultrasonic dispersion for 1h.

[0051] Add 25phr curing agent, degassing and then coat the aluminum alloy.

[0052] Single lap bonded on aluminum alloy (2024T3) to aluminum alloy (2024T3) test panels.

[0053] Step curing: 120℃ / 2h→150℃ / 1h.

[0054] Test Method

[0055] Dielectric properties: waveguide method (GB / T35679-2017, 10GHz).

[0056] Shear strength: universal material testing machine (ASTM D1002, loading rate 1 mm / min).

[0057] Temperature resistance cycle: -65℃→200℃, 10 cycles (GJB 548B-2005), judgment criteria: no delamination or cracking (SEM observation).

[0058] Comparative Example

[0059] Bisphenol A epoxy resin (DER TM 331), no nanofiller was added, and the curing agent was DDM. The test results showed that Dk=3.8, Df=0.032, shear strength was 18MPa, and microcracks appeared after the temperature resistance test.

[0060] The present invention further provides a microwave radio frequency component phase insulating adhesive, which is prepared using the aforementioned microwave radio frequency component phase insulating adhesive preparation method.

[0061] The present invention discloses a phase insulating adhesive and a preparation method thereof. The problems of local discharge and electric tree in traditional phase insulating adhesive in high-voltage power equipment are solved by pretreating fillers, mixing resin matrix with diluent and coupling agent, dispersing pretreated fillers, adding curing agent and step curing process. The present invention adopts phenolic epoxy resin as matrix, propylene oxide benzyl ether as diluent, nano silicon dioxide and fumed alumina as fillers, γ-glycidyl ether oxypropyl trimethoxy silane as coupling agent, and methyl hexahydrophthalic anhydride as curing agent. The dielectric strength and thermal stability of the phase insulating adhesive are effectively improved by vacuum drying pretreatment of nano silicon dioxide, ultrasonic dispersion technology and vacuum degassing treatment, and step curing process, and the insulation performance and service life of the phase insulating adhesive in high-voltage power equipment are significantly improved. The present invention provides a low-dielectric microwave radio frequency component insulating adhesive, which synergistically reduces the dielectric constant (Dk≤2.3) by phenolic epoxy resin and nanofiller, and adopts a step curing process to ensure stability in a wide temperature range (-65°C to 200°C). It is suitable for high-frequency transmission scenarios such as 5G high-frequency signals and radar modules.

[0062] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the concept of the present application. For example, the above features are replaced with the technical features with similar functions disclosed in the present application (but not limited to) to form a technical solution.

Claims

1. A method for preparing phase insulating adhesive for microwave radio frequency components, characterized in that: include: Obtaining resin matrix, diluent, filler, coupling agent and curing agent; Obtaining a pretreated filler by pretreating the filler; Mixing the resin matrix with the diluent and the coupling agent to obtain a first mixture; dispersing the pretreated filler into the first mixture to obtain a second mixture; adding the curing agent to the second mixture to obtain a third mixture; The phase insulating adhesive is obtained by curing the third mixture.

2. The method for preparing the microwave radio frequency component phase insulating adhesive according to claim 1, characterized in that: The method of obtaining a resin matrix, a diluent, a filler, a coupling agent and a curing agent comprises: obtaining a phenolic epoxy resin as the resin matrix, obtaining propylene oxide benzyl ether as the diluent, obtaining nano silicon dioxide and gas phase alumina as the filler, obtaining γ-glycidyloxypropyltrimethoxysilane as the coupling agent, and obtaining methylhexahydrophthalic anhydride as the curing agent.

3. The method for preparing the phase insulating adhesive of microwave radio frequency components according to claim 1, characterized in that: The method of obtaining the pretreated filler by pretreating the filler includes: obtaining nano-silicon dioxide in the filler, vacuum drying the nano-silicon dioxide at a preset temperature, and obtaining the pretreated nano-silicon dioxide as a part of the pretreated filler.

4. The method for preparing the phase insulating adhesive of microwave radio frequency components according to claim 1, characterized in that: The step of mixing the resin matrix with the diluent and the coupling agent to obtain the first mixture includes: obtaining the resin matrix, heating and melting the resin matrix at a preset temperature, adding the diluent and the coupling agent to the melted resin matrix, and stirring at a preset temperature for a preset time to obtain the first mixture.

5. The method for preparing the phase insulating adhesive of microwave radio frequency components according to claim 1, characterized in that: The method of dispersing the pretreated filler into the first mixture to obtain the second mixture includes: obtaining the pretreated filler, adding the pretreated filler into the first mixture in batches, and dispersing the filler for a preset time at a preset power by an ultrasonic dispersing device to obtain the second mixture.

6. The method for preparing the phase insulating adhesive of microwave radio frequency components according to claim 1, characterized in that: The adding of the curing agent to the second mixture to obtain the third mixture includes: obtaining the curing agent, adding the curing agent to the second mixture, and degassing the mixture after adding the curing agent for a preset time by vacuum degassing equipment to obtain the third mixture.

7. The method for preparing the phase insulating adhesive of microwave radio frequency components according to claim 1, characterized in that: The phase insulating glue is obtained by curing the third mixture, including: obtaining the third mixture, placing the third mixture in a preset mold, and curing the third mixture through a step curing process, wherein the step curing process includes a combination of multiple preset temperatures and corresponding preset times to obtain the phase insulating glue.

8. A phase insulating adhesive for microwave radio frequency components, characterized in that: The method for preparing the microwave radio frequency component phase insulating adhesive according to any one of claims 1 to 7 is used for preparing the microwave radio frequency component phase insulating adhesive.

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