Polytetrafluoroethylene high-frequency copper-clad plate with high thermal conductivity and ultralow dielectric loss and preparation method of polytetrafluoroethylene high-frequency copper-clad plate

Abstract

The invention relates to a polytetrafluoroethylene high-frequency copper-clad plate with high thermal conductivity and ultralow dielectric loss and a preparation method thereof, and belongs to the technical field of copper-clad plate preparation. Aiming at the technical problems of low heat conductivity and high dielectric loss of the existing polytetrafluoroethylene copper-clad plate, the invention provides the high-frequency copper-clad plate which has the thickness of 0.84-1.4 mm and contains a polytetrafluoroethylene core layer of a heat-conducting component h-BN, and an upper dielectric layer and a lower dielectric layer are arranged on the upper surface and the lower surface of the core layer. The thickness of the upper and lower dielectric layers is limited to be 0.05-0.1 mm, the dielectric constant deviation between the core layer and the upper and lower dielectric layers is smaller than or equal to 0.1, the thermal expansion coefficient deviation is smaller than or equal to 5 ppm / DEG C, the Z-direction overall heat conductivity coefficient is larger than or equal to 1.5 W / m.K, the dielectric loss factor is smaller than or equal to 0.00084 at 10 GHz, and the requirements of different circuit designs can be met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of copper-clad plate preparation, and particularly relates to a high-thermal-conductivity and ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate and a preparation method thereof. BACKGROUND

[0002] The polytetrafluoroethylene copper-clad plate has good high-frequency dielectric properties and is a basic material in the fields of aerospace, 5G / 6G communication, automobile radar and the like, and can be used to manufacture devices and as a carrier plate, thus having a broad application prospect. On the one hand, improving the thermal conductivity of the polytetrafluoroethylene copper-clad plate will be conducive to the heat dissipation of the devices and the carrier plate, and improve the stability and service life of the devices and the carrier plate in a long-term working environment. The thermal conductivity of the currently reported polytetrafluoroethylene high-frequency copper-clad plate products is lower than 1.5 W(m·K). On the other hand, with the continuous development of microwave communication technology, the communication frequency has developed from megahertz to gigahertz, and is developing towards terahertz. Therefore, the copper-clad plate with ultra-low dielectric loss under gigahertz will have strong competitiveness. The dielectric loss of the polytetrafluoroethylene high-frequency copper-clad plate products on the market under the frequency of 10 GHz is mostly between 0.0009 and 0.002, and the high-frequency copper-clad plate materials with a dielectric loss lower than 0.0009 are less, but the demand is increasing sharply.

[0003] It is found through analysis of the structure of the polytetrafluoroethylene high-frequency copper-clad plate products at the present stage that most of them are mainly laminated plates with glass fiber cloth as the support structure, which has the advantages of being suitable for batch preparation of large-size products, stable product size and controllable thickness. However, such laminated plates are subject to the presence of the glass fiber cloth: on the one hand, the nodes of the glass fiber cloth are mainly filled with low-thermal-conductivity resin, which will block the heat conduction channel along the Z direction and significantly reduce the thermal conductivity; on the other hand, the dielectric loss of the traditional electronic-grade glass fiber cloth is relatively high (1 order of magnitude higher than that of polytetrafluoroethylene), which will significantly increase the dielectric loss of the high-frequency copper-clad plate after being introduced, so that the final product will lose competitiveness. SUMMARY

[0004] In view of the technical problems of low thermal conductivity and high dielectric loss of the existing polytetrafluoroethylene high-frequency copper-clad plate products, the purpose of the present application is to provide a high-thermal-conductivity and ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate and a preparation method thereof.

[0005] In a first aspect, the present application provides a high-thermal-conductivity and ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate, which has the following structural components: a core layer located at the middle part, an upper dielectric layer and a lower dielectric layer laminated on the upper and lower surfaces of the core layer, and an upper copper foil and a lower copper foil laminated on the upper surface of the upper dielectric layer and the lower surface of the lower dielectric layer. The thickness of the core layer is 0.84-1.4 mm; the thickness of the upper and lower dielectric layers is 0.05-0.1 mm; The dielectric constant of the core layer is 3.0-4.0, and the dielectric constant of the upper and lower dielectric layers is 2.9-4.1; The thermal expansion coefficient of the core layer is 12-20 ppm / ℃, and the thermal expansion coefficient of the upper and lower dielectric layers is 7-25 ppm / ℃.

[0006] Preferably, the chemical composition of the core layer comprises polytetrafluoroethylene and a heat-conducting filler; the heat-conducting filler comprises a heat-conducting component h-BN, or a mixture of the heat-conducting component h-BN and at least one of common components SiO2, TiO2, Al2O3, AlN, Si3N4, MgTiO3, and boehmite.

[0007] Preferably, the content of polytetrafluoroethylene in the core layer is 42-52 wt%, and the content of the heat-conducting filler is 48-58 wt%; in the heat-conducting filler, the content of the heat-conducting component is 80-100 wt%, and the content of the common component is 0-20 wt%.

[0008] Preferably, the chemical composition of the upper and lower dielectric layers both comprises polytetrafluoroethylene and a dielectric ceramic filler; the dielectric ceramic filler comprises at least one of SiO2, TiO2, Al2O3, AlN, Si3N4, MgTiO3, and boehmite.

[0009] Preferably, the content of polytetrafluoroethylene in the upper and lower dielectric layers is 45-55 wt%, and the content of the dielectric ceramic filler is 45-55 wt%.

[0010] Preferably, the dielectric constant of the core layer is 3.0-4.0, and the dielectric constant of the upper and lower dielectric layers is 2.9-4.1; The thermal expansion coefficient of the core layer is 12-20 ppm / ℃, and the thermal expansion coefficient of the upper and lower dielectric layers is 7-25 ppm / ℃.

[0011] In a second aspect, the application provides a preparation method of the high-heat-conducting and ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate, which comprises the following steps: (1) coupling agent modification of a heat-conducting filler and mixing of the heat-conducting filler with fluororesin and an additive to obtain a raw material mixed slurry, molding to obtain a blank, and then extruding, calendering, and heat treating the blank to obtain the core layer; (2) preparation of the upper and lower dielectric layers according to the processing technology of the heat-conducting filler in the step (1) from a dielectric ceramic filler; or preparation of the upper and lower dielectric layers by using a blade coating or a flow casting process on a raw material mixed slurry obtained by processing the heat-conducting filler in the step (1); (3) The core layer, the upper dielectric layer, the lower dielectric layer, the upper copper foil and the lower copper foil are stacked according to the structure of the copper-clad plate, and are subjected to hot pressing and sintering to obtain the high-thermal-conductivity, ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate.

[0012] Preferably, in step (1), the mass ratio of the heat-conductive filler in the mixed slurry is 45-55 wt%, and the mass ratio of the auxiliary agent is 1-5 wt%; in the heat-conductive filler, the mass ratio of the heat-conductive component is 80-100 wt%, and the mass ratio of the ordinary component is 0-20 wt%.

[0013] Preferably, in step (1), the temperature of the heat treatment is 100-300℃, and the time is 5-60 min.

[0014] Preferably, in step (3), the vacuum degree of the hot pressing and sintering is 0.5-5 kPa, the sintering temperature is 360-390℃, the holding time is 1-3 hours, and the sintering pressure is 4-8 MPa.

[0015] Advantages The high-thermal-conductivity, ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate provided by the application has the following performances: (1) thermal management performance: the overall thermal conductivity in the Z direction is greater than or equal to 1.5 W / m·K, which is more than 3 times higher than that of a traditional polytetrafluoroethylene copper-clad plate; (2) high-frequency characteristics: the dielectric loss factor Df is less than or equal to 0.00084 (@10 GHz), which is more than 20% lower than that of a traditional polytetrafluoroethylene copper-clad plate; (3) flexible performance regulation: by adjusting the composition of the heat-conductive composite filler and designing a matching dielectric layer, the dielectric constant of the high-thermal-conductivity copper-clad plate can be flexibly regulated to meet different circuit design requirements. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The high-thermal-conductivity, ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate provided by the application has the following performances: (1) thermal management performance: the overall thermal conductivity in the Z direction is greater than or equal to 1.5 W / m·K, which is more than 3 times higher than that of a traditional polytetrafluoroethylene copper-clad plate; (2) high-frequency characteristics: the dielectric loss factor Df is less than or equal to 0.00084 (@10 GHz), which is more than 20% lower than that of a traditional polytetrafluoroethylene copper-clad plate; (3) flexible performance regulation: by adjusting the composition of the heat-conductive composite filler and designing a matching dielectric layer, the dielectric constant of the high-thermal-conductivity copper-clad plate can be flexibly regulated to meet different circuit design requirements. Figure 2 The high-thermal-conductivity, ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate provided by the application has the following performances: (1) thermal management performance: the overall thermal conductivity in the Z direction is greater than or equal to 1.5 W / m·K, which is more than 3 times higher than that of a traditional polytetrafluoroethylene copper-clad plate; (2) high-frequency characteristics: the dielectric loss factor Df is less than or equal to 0.00084 (@10 GHz), which is more than 20% lower than that of a traditional polytetrafluoroethylene copper-clad plate; (3) flexible performance regulation: by adjusting the composition of the heat-conductive composite filler and designing a matching dielectric layer, the dielectric constant of the high-thermal-conductivity copper-clad plate can be flexibly regulated to meet different circuit design requirements. Figure 3 The high-thermal-conductivity, ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate provided by the application has the following performances: (1) thermal management performance: the overall thermal conductivity in the Z direction is greater than or equal to 1.5 W / m·K, which is more than 3 times higher than that of a traditional polytetrafluoroethylene copper-clad plate; (2) high-frequency characteristics: the dielectric loss factor Df is less than or equal to 0.00084 (@10 GHz), which is more than 20% lower than that of a traditional polytetrafluoroethylene copper-clad plate; (3) flexible performance regulation: by adjusting the composition of the heat-conductive composite filler and designing a matching dielectric layer, the dielectric constant of the high-thermal-conductivity copper-clad plate can be flexibly regulated to meet different circuit design requirements. Reference signs: 1, core layer, 2-1, upper dielectric layer, 2-2, lower dielectric layer, 3-1, upper copper foil, 3-2, lower copper foil. DETAILED DESCRIPTION

[0017] The application is further illustrated by the following embodiments, which should be understood as merely illustrative of the application, rather than limiting the application.

[0018] First, as Figure 1As shown, the present application provides a high-thermal-conductivity, ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate. The structure of the high-thermal-conductivity, ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate can include a core layer at the middle part, an upper dielectric layer and a lower dielectric layer stacked on the upper and lower surfaces of the core layer, and an upper copper foil and a lower copper foil stacked on the upper surface of the upper dielectric layer and the lower surface of the lower dielectric layer.

[0019] The core layer plays a role of heat conduction and electrical interconnection. In some embodiments, the chemical composition of the core layer can include polytetrafluoroethylene and a thermal conductive filler; the thermal conductive filler can include a thermal conductive component h-BN, or a mixture of the thermal conductive component h-BN and at least one of common components SiO2, TiO2, Al2O3, AlN, Si3N4, MgTiO3, and boehmite; preferably, the particle size d 50 of the thermal conductive filler can be in the range of 10-35 μm.

[0020] In the core layer, the content of polytetrafluoroethylene can be 42-52 wt%, and the content of the thermal conductive filler can be 48-58 wt%; when the thermal conductive filler is composed of a thermal conductive component and a common component, the content of the thermal conductive component can be 80-100 wt%, and the content of the common component can be 0-20 wt%.

[0021] It should be noted that too low content of the thermal conductive filler will result in decreased thermal conductivity and increased thermal expansion coefficient of the material, causing the thermal expansion coefficients of the core layer, the upper and lower dielectric layers, and the copper foils to be mismatched; too high content of the thermal conductive filler will result in high viscosity of the mixture during preparation of the core layer, poor processability, difficult extrusion, and decreased quality of the calendered film. In addition, the thermal conductive component in the thermal conductive filler can ensure the thermal conductivity (1.5 W•m -1 •K -1 ), and the common component can be used to adjust the dielectric constant of the composite material in the range of 3.0-4.0 to meet different design requirements, and the content of the common component controlled in a specific range can ensure the thermal conduction effect.

[0022] The upper and lower dielectric layers mainly play a role of enhancing the peel strength of the copper foils and electrical interconnection. In some embodiments, the chemical composition of the upper and lower dielectric layers can each include polytetrafluoroethylene and a dielectric ceramic filler; the dielectric ceramic filler can include at least one of SiO2, TiO2, Al2O3, AlN, Si3N4, MgTiO3, and boehmite.

[0023] The content of polytetrafluoroethylene in the upper dielectric layer and the lower dielectric layer can be 45-55 wt%, and the content of dielectric ceramic filler can be 45-55 wt%. If the content of dielectric ceramic filler is too low, the dielectric constant of the dielectric layer will be too low, and the thermal expansion coefficient will be too large, which cannot match the core layer; if the content of dielectric ceramic filler is too high, the processability of the preparation will be poor, the dielectric constant will be too large, and the core layer cannot be matched.

[0024] In some embodiments, the thickness of the core layer can be 0.5-1.9 mm, preferably 0.84-1.4 mm; the thickness of the upper dielectric layer and the lower dielectric layer can be 5-8% of the thickness of the core layer, preferably 0.05-0.1 mm.

[0025] If the thickness of the upper dielectric layer and the lower dielectric layer is too large, the peel strength will be too high, the heat conduction network will be invalid, and the thermal conductivity in the Z direction will be reduced; if the thickness of the upper dielectric layer and the lower dielectric layer is too small, the dielectric layer will be easily damaged during the preparation and pressing process, and the core layer and the copper foil will be in contact in some local areas, and the peel strength will be reduced.

[0026] It should be noted that the reason why the core layer of the copper-clad plate provided by the present application adopts a thick single-layer structure is mainly that the composite heat-conducting filler in the core layer contains a flaky heat-conducting component, and the calendering process in the preparation method described below will cause the flaky heat-conducting component to be oriented and arranged in the X-Y plane. By adopting a thick single-layer structure design, the orientation and arrangement of the flaky filler can be weakened, a three-dimensional heat-conducting network can be formed, and the thermal conductivity in the Z direction can be improved.

[0027] In some embodiments, the dielectric constant of the core layer can be 3.0-4.0, the dielectric constant of the upper dielectric layer and the lower dielectric layer can be 2.9-4.1, and the deviation of the dielectric constant of the core layer from the upper dielectric layer and the lower dielectric layer can be ≤0.1. If the deviation of the dielectric constant between different layers is too high, the impedance will be suddenly changed, the time delay will be mismatched, the signal integrity will be affected, and the device will be invalid.

[0028] In some embodiments, the thermal expansion coefficient of the core layer can be 12-20 ppm / ℃, the thermal expansion coefficient of the upper dielectric layer and the lower dielectric layer can be 7-25 ppm / ℃, and the deviation of the thermal expansion coefficient of the core layer from the upper dielectric layer and the lower dielectric layer can be ≤5 ppm / ℃. If the deviation of the thermal expansion coefficient of the two layers is too large, the dielectric layer and the core layer will generate thermal stress, and the internal defects will be caused by the inconsistent expansion and contraction during the manufacturing process of PCB, etc., and the reliability will be reduced.

[0029] In some embodiments, the high-thermal-conductivity, ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate can have a thermal conductivity of ≥1.5 W / (m·K) along the Z-axis direction, preferably 1.5-2.2 W / (m·K), a dielectric loss of less than 0.00084 at 10 GHz, preferably 0.0005-0.00084, and a peel strength of 1.12 N / mm or more, preferably 1.12-1.6 N / mm.

[0030] Hereinafter, the preparation method of the high-thermal-conductivity, ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate provided by the present application is exemplarily described. The preparation method can include the following steps: (1) coupling agent modification of the thermal-conductivity filler and mixing with fluororesin and additives to obtain a raw material mixed slurry, molding to obtain a green body, and then extruding, calendering and heat treating the green body to obtain the core layer; (2) preparing the upper and lower dielectric layers from the dielectric ceramic filler according to the processing process of the thermal-conductivity filler in step (1); or using the raw material mixed slurry obtained by the processing process of the thermal-conductivity filler in step (1) to prepare the upper and lower dielectric layers by means of blade coating and casting process; (3) stacking the core layer, upper and lower dielectric layers, upper and lower copper foils according to the structure of the copper-clad plate, and hot-pressing and sintering to obtain the high-thermal-conductivity, ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate.

[0031] In some embodiments, in step (1), the coupling agent can include at least one of a silane coupling agent and a titanate coupling agent.

[0032] In some embodiments, in step (1), the coupling agent modification of the thermal-conductivity filler can be performed by the following process: adding the thermal-conductivity filler to a coupling agent solution, controlling the concentration of the coupling agent to be 0.1-3 wt% and the concentration of the thermal-conductivity filler to be 10-50 wt%, thoroughly mixing, then filtering, and then drying the obtained solid mixture at 80-120°C.

[0033] By first modifying the surface of the thermal-conductivity filler, a layer of coupling agent can be wrapped around the surface of the thermal-conductivity filler, thereby enhancing the combination of the thermal-conductivity filler and the fluororesin, preventing the occurrence of voids at the interface between the two phases, and increasing the dielectric loss of the interface.

[0034] In some embodiments, in step (1), the fluororesin can include polytetrafluoroethylene, soluble polytetrafluoroethylene, and fluorinated ethylene.

[0035] In some embodiments, in step (1), the auxiliary agent can include at least one of oil-based lubricant, synthetic lubricant. The purpose of adding the auxiliary agent after mixing the thermally conductive filler with the fluororesin is mainly to reduce the resistance in the subsequent extrusion process and improve the quality of the core layer.

[0036] In some embodiments, in step (1), the mass ratio of the thermally conductive filler in the mixed slurry can be 45-55wt% (thermally conductive component 80-100wt%, general component 0-20wt%), and the mass ratio of the auxiliary agent can be 1-5wt%.

[0037] In some embodiments, in step (1), the forming pressure of the blank can be 5-15MPa.

[0038] In some embodiments, in step (1), the extrusion can be carried out in an extruder and a forming die, and the process parameters of the extrusion can include: extrusion pressure 10-20MPa, pushing speed 10-30mm / min.

[0039] In some embodiments, in step (1), the calendering can be carried out in a double-roller calender, and the calendering speed can be 0.1-0.3m / s.

[0040] The purpose of using the extrusion-calendering method to prepare the core layer is mainly to reduce the dielectric loss caused by various auxiliary agents in the raw materials such as impregnating solution in the traditional wet preparation process through dry process.

[0041] In some embodiments, in step (1), the thickness of the core layer sample obtained after calendering can be 0.5-2.0mm.

[0042] In some embodiments, in step (1), the heat treatment temperature can be 100-300℃, and the time can be 5-60min. By performing heat treatment, the auxiliary agent in the core layer obtained after calendering can be removed.

[0043] In some embodiments, in step (2), the mass ratio of the dielectric ceramic filler in the raw material mixed slurry of the upper dielectric layer and the lower dielectric layer can be 45-55wt%, and the mass ratio of the auxiliary agent can be 1-5wt%.

[0044] In some embodiments, in step (2), the thickness of the upper dielectric layer and the lower dielectric layer samples obtained after calendering can be 0.05-0.2mm.

[0045] In some embodiments, in step (3), the vacuum degree of the hot-press sintering can be 0.5-5 kPa, the sintering temperature can be 360-390 ℃, the holding time can be 1-3 hours, and the sintering pressure can be 4-8 MPa. If the temperature and pressure are too small, the density and peel strength of the finally prepared copper-clad plate will be poor; if the temperature and pressure are too high, the glue will flow and the thickness of each layer will be uncontrollable.

[0046] The following examples are further illustrated to explain the present application in detail. It should also be understood that the following examples are only used to further illustrate the present application, and cannot be understood as limiting the protection scope of the present application. Some non-essential improvements and adjustments made by those skilled in the art according to the above content of the present application all belong to the protection scope of the present application. The specific process parameters in the following examples are only one example in the appropriate range, i.e. those skilled in the art can make appropriate selection within the range according to the description herein, and are not limited to the specific values in the following examples. If not specifically indicated, the technical means used in the examples are the conventional means known to those skilled in the art.

[0047] Example 1 The preparation method of the high-thermal-conductivity, ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate provided in the present embodiment comprises the following steps: (1) The thermal conductive filler is added to the coupling agent solution, and the concentration of the coupling agent is controlled to be 1 wt%, and the concentration of the thermal conductive filler is controlled to be 50 wt%. After slow stirring for 4 hours, the solid mixture obtained after filtration is dried at 120 ℃ for 8 h to obtain the coupling agent modified thermal conductive filler; The coupling agent modified thermal conductive filler is added to the fluororesin and mechanically mixed and dispersed uniformly to obtain a mixture, then an auxiliary agent is added and stirred uniformly to obtain a raw material mixed slurry, which is sealed and stored for 12 h. In the raw material mixed slurry, the mass ratio of the thermal conductive filler is 50 wt% (thermal conductive component 80 wt%, ordinary component 20 wt%), and the mass ratio of the auxiliary agent is 2 wt%; The mixture after sealing and storage is placed in a mold to be molded into a core layer blank, and the molding pressure is controlled to be 8 MPa; The core layer blank is placed in an extruder, and is extruded into a thick film through a molding die. The thick film is calendered to obtain a core layer, and the thickness of the core layer is controlled to be 1.300 mm ± 0.100 mm; The core layer is placed in an oven to remove the auxiliary agent, and the temperature is 100 ℃ for 3 minutes, 200 ℃ for 3 minutes, and 300 ℃ for 3 minutes, and then the finished core layer is obtained; (2) The dielectric ceramic filler is filled according to the processing technology of the heat-conducting filler in step (1) to obtain an upper dielectric layer and a lower dielectric layer; the mass ratio of the dielectric ceramic filler in the raw material mixed slurry of the upper dielectric layer and the lower dielectric layer is 50wt%; the thickness of the calendered upper dielectric layer and the lower dielectric layer is 0.100mm±0.050mm; (3) The finished core layer is cut into a specified size, stacked in the mode of "lower copper foil-lower dielectric film-core layer-upper dielectric film-upper copper foil", and placed into a vacuum hot press for hot pressing and sintering, the sintering temperature is 380℃, the holding time is 2 hours, and the pressure is 5MPa, to obtain the high-heat-conducting and ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate (the thickness of the core layer is 0.910mm, the thickness of the upper dielectric layer and the lower dielectric layer is 0.050mm, and the thickness of the upper copper foil and the lower copper foil is 0.051mm).

[0048] Example 2 The preparation method of the high-heat-conducting and ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate provided in this embodiment refers to Example 1, and the main difference lies in that: In step (1), the mass ratio of the heat-conducting component in the heat-conducting filler is 90wt%, and the mass ratio of the ordinary component is 10wt%; In the finally prepared high-heat-conducting and ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate, the thickness of the core layer is 0.912mm, the thickness of the upper dielectric layer and the lower dielectric layer is 0.050mm, and the thickness of the upper copper foil and the lower copper foil is 0.051mm.

[0049] Example 3 The preparation method of the high-heat-conducting and ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate provided in this embodiment refers to Example 1, and the main difference lies in that: In step (1), the mass ratio of the heat-conducting component in the heat-conducting filler is 100wt%; In the finally prepared high-heat-conducting and ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate, the thickness of the core layer is 0.914mm, the thickness of the upper dielectric layer and the lower dielectric layer is 0.050mm, and the thickness of the upper copper foil and the lower copper foil is 0.051mm.

[0050] Example 4 The preparation method of the high-heat-conducting and ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate provided in this embodiment refers to Example 3, and the main difference lies in that: In step (1), the thickness of the calendered core layer sample is 1.200mm±0.050mm; In step (2), the thickness of the calendered upper dielectric layer and lower dielectric layer sample is 0.150mm±0.050mm; The finally prepared high-thermal-conductivity, ultra-low dielectric loss polytetrafluoroethylene high-frequency copper-clad plate has a core layer thickness of 0.840 mm, an upper dielectric layer thickness of 0.076 mm, a lower dielectric layer thickness of 0.076 mm, an upper copper foil thickness of 0.051 mm and a lower copper foil thickness of 0.051 mm.

[0051] Comparative Example 1 The preparation method of the copper-clad plate provided in the present comparative example refers to that of Example 3, and the main difference lies in that: In step (1), the thickness of the core layer sample after calendering is 1.100 mm ± 0.050 mm; In step (2), the thickness of the upper and lower dielectric layers after calendering is 0.200 mm ± 0.050 mm; The finally prepared copper-clad plate has a core layer thickness of 0.766 mm, an upper dielectric layer thickness of 0.144 mm, a lower dielectric layer thickness of 0.144 mm, an upper copper foil thickness of 0.051 mm and a lower copper foil thickness of 0.051 mm.

[0052] Comparative Example 2 The preparation method of the copper-clad plate provided in the present comparative example refers to that of Example 3, and the main difference lies in that: In step (1), the forming pressure of the core layer blank is 5 MPa; and the thickness of the core layer after calendering is 1.300 mm ± 0.050 mm; The preparation of the upper and lower dielectric layers in step (2) is not performed; In step (3), the finished core layer is cut into a specified size, stacked in the order of “lower copper foil-core layer-upper copper foil” and sintered; The finally prepared copper-clad plate has a core layer thickness of 0.890 mm, an upper copper foil thickness of 0.051 mm and a lower copper foil thickness of 0.051 mm.

[0053] Table 1 below is a performance comparison list of the copper-clad plates prepared in Examples 1-4 and Comparative Examples 1-2: Sample No. Proportion of heat conductive component wt% Proportion of common component wt% Core thickness after pressing mm Medium layer thickness after pressing mm Copper clad plate foil removal thickness mm Thermal conductivity in Z direction W / (m K) Dielectric loss @ 10 GHz Peel strength N / mm Example 1 40 10 0.910 0.050 1.010 1.72 8.4 x 10 -4 ]] 1.24 Example 2 45 5 0.912 0.050 1.012 1.93 7.1 x 10 -4 ]] 1.18 Example 3 50 0 0.914 0.050 1.014 2.12 6.0 x 10 -4 ]] 1.12 Example 4 50 0 0.840 0.076 0.992 1.77 7.4 x 10 -4 ]] 1.26 Comparative Example 1 50 0 0.766 0.144 1.054 1.32 8.6 x 10 -4 ]] 1.52 Comparative Example 2 50 0 0.890 0 0.890 2.25 5.4 x 10 -4 ]]> 0.64

[0054] As can be seen from Table 1, with the increase of the thermal conductive filler component in the high-thermal-conductivity composite ceramic, the thermal conductivity is significantly improved, and the highest thermal conductivity can reach 2.12 W / (m·K). The main reason is that with the increase of the thermal conductive filler component, the thermal conductive network is gradually constructed. When the thermal conductive filler reaches 100%, the thermal conductive network is completed, and at this time, the heat can be quickly transferred along the Z-directional thermal conductive network, showing the highest thermal conductivity. With the increase of the thickness of the upper and lower dielectric layers, the thermal conductivity will decrease slightly, mainly because the thermal conductivity of the dielectric layer is not high, resulting in a lower heat transfer efficiency, but the peel strength will be significantly improved. In addition, as can be seen from Comparative Example 2, the sandwich structure composed of the upper and lower dielectric layers is a prerequisite for improving the peel strength and meeting the application requirements of printed circuit boards.

[0055] In summary, the sandwich-structured high-thermal-conductivity and ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate prepared by the application is significantly superior to conventional high-frequency copper-clad plate products.

[0056] Figure 2 The structural schematic diagram of the high-thermal-conductivity and ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate prepared in Example 1 is shown in the figure. As can be seen from the figure, the thickness measurement results of each layer of the copper-clad plate sample prepared in Example 1.

[0057] Figure 3 The structural schematic diagram of the copper-clad plate prepared in Comparative Example 2 is shown in the figure. As can be seen from the figure, the core layer thickness of the copper-clad plate sample prepared in Comparative Example 2 is 0.890 mm.

[0058] Although the content of the application has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as limiting the application. After reading the above content, various modifications and alternatives of the application will be apparent to those skilled in the art. Therefore, the protection scope of the application should be defined by the appended claims.

Claims

1. A high thermal conductivity, ultra-low dielectric loss polytetrafluoroethylene high-frequency copper-clad plate, characterized in that, The structure of the high-thermal-conductivity, ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate comprises a core layer at the middle part, an upper dielectric layer and a lower dielectric layer stacked on the upper and lower surfaces of the core layer, and an upper copper foil and a lower copper foil stacked on the upper surface of the upper dielectric layer and the lower surface of the lower dielectric layer; The thickness of the core layer is 0.84-1.4 mm, and the thickness of the upper and lower dielectric layers is 0.05-0.1 mm. The dielectric constant deviation of the core layer from the upper and lower dielectric layers is ≤0.

1. The thermal expansion coefficient deviation of the core layer from the upper and lower dielectric layers is ≤5 ppm / ℃.

2. The high thermal conductivity, ultra-low dielectric loss polytetrafluoroethylene high frequency copper clad laminate according to claim 1, characterized in that, The chemical composition of the core layer comprises polytetrafluoroethylene and a thermal conductive filler; the thermal conductive filler comprises a thermal conductive component h-BN or a mixture of the thermal conductive component h-BN and at least one of common components SiO2, TiO2, Al2O3, AlN, Si3N4, MgTiO3, and boehmite.

3. The high thermal conductivity, ultra-low dielectric loss polytetrafluoroethylene high frequency copper clad laminate according to claim 2, characterized in that, The content of polytetrafluoroethylene in the core layer is 42-52 wt%, and the content of the thermal conductive filler is 48-58 wt%; in the thermal conductive filler, the content of the thermal conductive component is 80-100 wt%, and the content of the common component is 0-20 wt%.

4. The high thermal conductivity, ultra-low dielectric loss polytetrafluoroethylene high frequency copper clad laminate of claim 1, wherein, The chemical composition of the upper and lower dielectric layers each comprises polytetrafluoroethylene and a dielectric ceramic filler; the dielectric ceramic filler comprises at least one of SiO2, TiO2, Al2O3, AlN, Si3N4, MgTiO3, and boehmite.

5. The high thermal conductivity, ultra-low dielectric loss PTFE high frequency copper clad laminate according to claim 4, characterized in that, The content of polytetrafluoroethylene in the upper and lower dielectric layers is 45-55 wt%, and the content of the dielectric ceramic filler is 45-55 wt%.

6. The high thermal conductivity, ultra-low dielectric loss polytetrafluoroethylene high frequency copper clad laminate of claim 1, wherein, The dielectric constant of the core layer is 3.0-4.0, and the dielectric constant of the upper and lower dielectric layers is 2.9-4.

1. The thermal expansion coefficient of the core layer is 12-20 ppm / ℃, and the thermal expansion coefficient of the upper and lower dielectric layers is 7-25 ppm / ℃.

7. A method of producing the high thermal conductive, ultra-low dielectric loss polytetrafluoroethylene high-frequency copper clad plate according to any one of claims 1 to 6, characterized by, The preparation method comprises the following steps: (1) coupling agent modification of the thermal conductive filler and mixing with fluororesin and an additive to obtain a raw material mixed slurry, molding to obtain a blank, and then extruding, calendering, and heat treating the blank to obtain the core layer; (2) preparing the upper and lower dielectric layers according to the processing technology of the thermal conductive filler in step (1) or using the raw material mixed slurry obtained by processing the thermal conductive filler in step (1) to prepare the upper and lower dielectric layers by using a doctor blade coating or a casting process; (3) stacking the core layer, the upper and lower dielectric layers, and the upper and lower copper foils according to the structure of the copper-clad plate, and hot pressing and sintering to obtain the high-thermal-conductivity, ultra-low-dielectric-loss polytetrafluoroethylene high-frequency copper-clad plate.

8. The preparation method according to claim 7, characterized in that, In step (1), the mass ratio of the thermal conductive filler in the mixed slurry is 45-55 wt%, and the mass ratio of the additive is 1-5 wt%; in the thermal conductive filler, the mass ratio of the thermal conductive component is 80-100 wt%, and the mass ratio of the common component is 0-20 wt%.

9. The preparation method according to claim 7, characterized in that, In step (1), the heat treatment temperature is 100-300℃, and the time is 5-60 min.

10. The preparation method according to claim 7, characterized in that, In step (3), the vacuum degree of the hot-press sintering is 0.5-5 kPa, the sintering temperature is 360-390 ℃, the holding time is 1-3 hours, and the sintering pressure is 4-8 MPa.

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