Preparation method of high frequency flexible copper clad laminate

Abstract

The present application relates to the technical field of copper-clad plate preparation, in particular to a preparation method of high-frequency flexible copper-clad plate. The preparation method uses a mixture of trifluorochloroethylene-vinyl ether fluororesin emulsion and tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer emulsion as a fluorine-containing emulsion matrix, then adds isosorbide polycarbonate to prepare a composite emulsion to coat both sides of the PI film, and a fluorine-containing polymer layer is prepared. The modified PTFE layer modified by the mixture of modified fluorinated graphene and nano silicon nitride has a synergistic effect, and finally copper foil is coated on both sides to prepare a high-frequency flexible copper-clad plate. The fluorine-containing polymer layer has an interfacial bonding effect, the modified PTFE layer has the effects of reducing dielectric loss and enhancing stability, and the two layers have a synergistic effect, so that the prepared high-frequency copper-clad plate has excellent high-frequency dielectric properties, high-strength interfacial bonding properties, and excellent mechanical and dimensional stability.

Description

Technical Field

[0001] This invention belongs to the field of copper clad laminate preparation technology, specifically relating to a method for preparing a high-frequency flexible copper clad laminate. Background Technology

[0002] High-frequency copper-clad laminates are a key material on the motherboards of electronic devices. In daily production and life, whether it is 5G communication switching systems, cloud computing storage systems, IoT radio frequency systems, or many cutting-edge technology fields and industries such as medical equipment, rail transportation, and green logistics, electronic digital signals are indispensable, and the high-frequency copper-clad laminates are precisely what enable the rapid and accurate transmission of signals.

[0003] Because of the high dielectric constant D k It will slow down the signal transmission speed and increase the dielectric loss D f This will cause the signal portion to be converted into heat energy and lost in the substrate material, thus reducing the material's density (D). k / D f This has become a trend in flexible substrate materials.

[0004] The production of polyimide copper-clad laminates mainly involves coating polyimide acid onto copper foil, followed by solvent removal and heat treatment to form a polyimide copper-clad laminate. However, during the production process, due to the difference in thermal expansion coefficients between polyimide and copper foil, the baking process after polyimide coating causes the copper-clad laminate to be rolled up, creating a production obstacle.

[0005] Traditional copper-clad laminates mainly consist of a three-layer structure of polyimide film, adhesive, and copper foil. The adhesive is mainly epoxy resin and acrylic. This type of flexible board material has the following defects: ① The dielectric loss value is relatively large, with a test value of about 0.01 at 10GHz; ② The dimensional change rate of the three-layer adhesive flexible board is greatly affected by temperature, resulting in poor dimensional stability; ③ The peel strength is relatively low.

[0006] Therefore, it is necessary to explore a new type of high-frequency flexible copper-clad laminate. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing a high-frequency flexible copper-clad laminate. The high-frequency flexible copper-clad laminate prepared by this method has excellent high-frequency dielectric properties, high-strength interfacial bonding performance, and excellent mechanical and dimensional stability.

[0008] The method for preparing the high-frequency flexible copper-clad laminate of the present invention comprises the following steps:

[0009] (1) Preparation of fluorinated emulsion matrix

[0010] A fluorinated emulsion matrix was prepared by stirring and mixing a trifluorochloroethylene-vinyl ether fluororesin emulsion with a tetrafluoroethylene-perfluoroalkoxyvinyl ether copolymer emulsion.

[0011] (2) Preparation of composite emulsion

[0012] Fluorinated emulsion matrix and deionized water were added to an emulsification tank and sheared at a high speed of 8000 r / min. Then, isosorbide-based polycarbonate-dichloromethane mixture was pumped into the reaction system at a constant rate over 28-30 min. Finally, silane coupling agent pre-hydrolysis solution was added and shearing was continued for 10-13 min. Ammonia was added to adjust the pH of the reaction system to 10. Dichloromethane was removed by rotary evaporation. Deionized water was added to control the solid content of the emulsion to 30%. The mixture was filtered to obtain a composite emulsion.

[0013] (3) Coat the composite emulsion prepared in step (2) onto both sides of the PI film, place it in an oven at 90-100℃, dry for 10-15 min, raise the temperature to 170-180℃ and keep it at that temperature for 50-60 min to obtain a fluoropolymer layer;

[0014] (4) Mix PTFE emulsion, thickener solution and deionized water to prepare a mixture, then add the mixture of modified fluorinated graphene and nano silicon nitride to the mixture, add ammonia water with a mass concentration of 25% to adjust the pH of the system to 9.0, and prepare a slurry.

[0015] (5) The fluoropolymer layer prepared in step (3) is subjected to plasma treatment, and then the slurry prepared in step (4) is coated on both sides of the fluoropolymer layer to form a modified PTFE layer. Finally, the fluoropolymer-modified PTFE composite layer is prepared by low-temperature drying, medium-temperature curing and high-temperature sintering.

[0016] (6) A high-frequency flexible copper-clad board is prepared by pressing and post-processing the double-sided copper foil of the fluoropolymer-modified PTFE composite layer using a vacuum hot press forming machine.

[0017] in:

[0018] The synthesis method of trifluorochloroethylene-vinyl ether fluororesin emulsion in step (1) is as follows: Wang Jiaqiang, Hou Chuanjin, Liu Yanjun. Synthesis and properties of trifluorochloroethylene-vinyl ether fluororesin emulsion [J]. Journal of Dalian University of Technology, 2022, 41(6):424-427.

[0019] In step (1), the tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer emulsion was manufactured by 3M Chemicals, model number 6910GZ, with a solid content of 50%.

[0020] In step (1), the mass ratio of trifluorochloroethylene-vinyl ether fluororesin emulsion to tetrafluoroethylene-perfluoroalkoxyvinyl ether copolymer emulsion is 3-3.2:10; the stirring speed is 200 r / min and the stirring time is 10 min.

[0021] In step (2), after pumping in at a constant speed, the shearing speed is controlled at 6000 r / min.

[0022] In step (2), the mass ratio of fluorinated emulsion matrix to deionized water is 1:1.

[0023] In step (2), the mass ratio of the fluorinated emulsion matrix to deionized water and to the isosorbide-type polycarbonate-dichloromethane mixture is 3-3.2:1.

[0024] In step (2), the isosorbide-type polycarbonate-dichloromethane mixture comprises 20% of the total mass of isosorbide-type polycarbonate and dichloromethane. The isosorbide-type polycarbonate is manufactured by Mitsubishi Corporation of Japan and is model DURABIO. TM D7340.

[0025] The preparation method of the silane coupling agent pre-hydrolyzed solution in step (2) is as follows: mix methacryloyloxypropyltrimethoxysilane with deionized water, add ammonia to adjust the pH of the reaction system to 10, and pre-hydrolyze at room temperature for 20-23 min to obtain the silane coupling agent pre-hydrolyzed solution; wherein, the mass concentration of ammonia is 25%, and the mass ratio of methacryloyloxypropyltrimethoxysilane to deionized water is 1:1.

[0026] In step (2), the mass ratio of methacryloyloxypropyltrimethoxysilane in the silane coupling agent pre-hydrolyzed solution to isosorbide-type polycarbonate in the isosorbide-dichloromethane mixture is 1:2.5.

[0027] In step (2), the rotary evaporation is first carried out at a pressure of -0.03MPa for 10-12 minutes, then at a pressure of -0.06MPa for 10-12 minutes, and finally at a pressure of -0.09MPa for 20-23 minutes. The rotary evaporation temperature is controlled at 42℃ throughout the process.

[0028] The filter membrane used in step (2) has a pore size of 0.45 micrometers.

[0029] The PI film mentioned in step (3) is manufactured by DuPont, Inc., USA, and its model is Kapton. ® 100EN.

[0030] In step (4), the thickener solution is obtained by mixing the thickener and deionized water at room temperature. The mass of the deionized water is 7 times the mass of the thickener. The manufacturer of the thickener is Qingdao Enze Chemical Co., Ltd., and the model is thickener TT-935.

[0031] In step (4), the PTFE emulsion is manufactured by Daikin Industries, Japan, model D210, with a solid content of 60%.

[0032] In step (4), the mass of the thickener in the thickener solution accounts for 1.7% of the total mass of the mixture of PTFE emulsion, modified fluorinated graphene, and nano-silicon nitride.

[0033] In step (4), the mass ratio of PTFE emulsion to deionized water is 3-3.2:2.

[0034] In step (4), the mass of the mixture of modified fluorinated graphene and nano-silicon nitride accounts for 20-22% of the mass of the PTFE emulsion.

[0035] The preparation method of the mixture of modified fluorinated graphene and nano silicon nitride in step (4) is as follows: anhydrous ethanol and ammonia water with a mass concentration of 25% are mixed at a volume ratio of 95:5 to prepare a solvent. KH-560 silane coupling agent and tridecafluorooctyltrimethoxysilane are mixed at a mass ratio of 1:1 and added to the solvent. The mixture is hydrolyzed at room temperature for 20 min. Then, fluorinated graphene and nano silicon nitride are added to the silane hydrolysate at one time. The mixture is sonicated for 20 min and then stirred at room temperature for 2 h. The mixture is filtered, washed three times with deionized water, and finally vacuum dried and passed through a 300-mesh sieve to prepare the mixture of modified fluorinated graphene and nano silicon nitride.

[0036] In step (4), the ultrasonic power is 200W, the stirring speed is 500r / min, the vacuum drying temperature is 80℃, and the vacuum drying time is 12h.

[0037] In step (4), the mass ratio of fluorinated graphene to nano silicon nitride in the preparation method of the mixture of modified fluorinated graphene and nano silicon nitride is 1-1.3:2; the mass of KH-560 silane coupling agent and tridecafluorooctyltrimethoxysilane accounts for 20-22% of the mass of fluorinated graphene and nano silicon nitride.

[0038] In step (5), the volume ratio of argon to oxygen in the plasma treatment is 9:1, the total gas flow rate is 18L / min, the plasma power is 450W, the distance from the surface of the fluoropolymer layer to the spray gun is 9mm, and the treatment speed is 2.5m / min.

[0039] In step (5), the low-temperature drying temperature is 90-92℃ and the low-temperature drying time is 13-15min. The medium-temperature curing temperature is 170-173℃ and the medium-temperature curing time is 23-25min. The high-temperature sintering temperature is 385-388℃ and the high-temperature sintering time is 85-90min.

[0040] In step (6), the copper foil is HVLP2 copper foil.

[0041] The pressing in step (6) is to heat to the pressing temperature at a heating rate of 6℃ / min, the pressing temperature is 310-313℃, the pressing pressure is 2.5MPa, the pressing time is 25min, and the vacuum degree is -0.095MPa.

[0042] The post-processing described in step (6) involves removing the high-frequency flexible copper-clad laminate from the vacuum hot press at 50°C, and then drying the high-frequency flexible copper-clad laminate at 55-60°C for 2 hours to obtain the high-frequency flexible copper-clad laminate.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] (1) The method for preparing the high-frequency flexible copper-clad laminate of the present invention uses a mixture of trifluorochloroethylene-vinyl ether fluororesin emulsion and tetrafluoroethylene-perfluoroalkoxyvinyl ether copolymer emulsion as a fluorinated emulsion matrix, and then adds isosorbide-type polycarbonate to prepare a composite emulsion which is coated on both sides of the PI film to prepare a fluorinated polymer layer. This layer works synergistically with a PTFE layer modified by a mixture of modified fluorinated graphene and nano-silicon nitride. Finally, copper foil is coated on both sides to prepare a high-frequency flexible copper-clad laminate. The fluorinated polymer layer has an interfacial bonding effect, and the modified PTFE layer has the effect of reducing dielectric loss and enhancing stability. The two layers work synergistically, thereby making the prepared high-frequency copper-clad laminate have excellent high-frequency dielectric properties, high-strength interfacial bonding performance, and excellent mechanical and dimensional stability.

[0045] (2) In the preparation method of the high-frequency flexible copper-clad laminate of the present invention, in the preparation process of the fluoropolymer layer, trifluorochloroethylene-vinyl ether fluororesin emulsion and tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer emulsion are compounded and used. The trifluorochloroethylene-vinyl ether fluororesin emulsion has a low dielectric constant and dielectric loss, and the ether-containing oxygen groups in the molecular structure form hydrogen bonds with isosorbide-type polycarbonate and PI film, thereby improving the initial adhesion between layers. The tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer emulsion can further reduce the dielectric properties of the fluoropolymer layer. The addition of isosorbide-type polycarbonate can play a role in strengthening the strength (fluororesin film is brittle and has low tensile strength) and improving the tensile strength between layers, thereby making the prepared fluoropolymer layer have interfacial bridging and bonding strengthening effects.

[0046] (3) In the preparation method of the high-frequency flexible copper-clad laminate of the present invention, in the preparation process of the fluoropolymer layer, trifluorochloroethylene-vinyl ether fluororesin emulsion and tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer emulsion are compounded and used. The trifluorochloroethylene-vinyl ether fluororesin emulsion contains ether bonds, which provide interfacial binding sites for isosorbide-type polycarbonate and silane coupling agent. The tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer emulsion has a low dielectric constant. After being blended with the trifluorochloroethylene-vinyl ether fluororesin emulsion, a continuous phase is formed, which balances the dielectric properties and film-forming properties. The carbonate groups (polar) of isosorbide-type polycarbonate form hydrogen bonds with the silanol (Si-OH) of the silane coupling agent, while also interacting with the ether bonds of the trifluorochloroethylene-vinyl ether fluororesin emulsion, preventing phase separation in the fluorinated emulsion matrix. The added silane coupling agent provides binding force, and after pre-hydrolysis, the silanol end covalently bonds with the polar sites of the PI film and the fluorinated resin. Meanwhile, the methacryloyloxy end physically entangles with the ester groups of isosorbide-type polycarbonate and the non-polar segments of the fluorinated resin, preventing coating delamination.

[0047] (4) The method for preparing the high-frequency flexible copper-clad laminate of the present invention, wherein the modified PTFE layer contains a PTFE emulsion with ultra-low dielectric and high flow characteristics, and a mixture of modified fluorinated graphene and nano-silicon nitride is used as a filler. Both fluorinated graphene and nano-silicon nitride are low polarity and low dielectric constant fillers, and their addition can further reduce the dielectric constant of the copper-clad laminate. k and D f Furthermore, the addition of both can increase dimensional stability, and after modification with coupling agent, the addition of filler also greatly improves the mechanical properties of copper clad laminate. Detailed Implementation

[0048] Example 1

[0049] The method for preparing the high-frequency flexible copper-clad laminate described in Example 1 consists of the following steps:

[0050] (1) Preparation of fluorinated emulsion matrix

[0051] A fluorinated emulsion matrix was prepared by stirring and mixing a trifluorochloroethylene-vinyl ether fluororesin emulsion with a tetrafluoroethylene-perfluoroalkoxyvinyl ether copolymer emulsion.

[0052] (2) Preparation of composite emulsion

[0053] Fluorinated emulsion matrix and deionized water were added to an emulsification tank and sheared at a high speed of 8000 r / min. Then, isosorbide-based polycarbonate-dichloromethane mixture was pumped into the above reaction system at a uniform rate over 29 min. Finally, silane coupling agent pre-hydrolysis solution was added and shearing was continued for 11 min. Ammonia was added to adjust the pH of the reaction system to 10. Dichloromethane was removed by rotary evaporation. Deionized water was added to control the solid content of the emulsion to 30%. The mixture was filtered to prepare a composite emulsion.

[0054] (3) The composite emulsion prepared in step (2) is coated onto both sides of the PI film, placed in a 95°C oven, dried for 13 min, heated to 175°C and kept warm for 55 min to obtain a fluoropolymer layer;

[0055] (4) Mix PTFE emulsion, thickener solution and deionized water to prepare a mixture, then add the mixture of modified fluorinated graphene and nano silicon nitride to the mixture, add ammonia water with a mass concentration of 25% to adjust the pH of the system to 9.0, and prepare a slurry.

[0056] (5) The fluoropolymer layer prepared in step (3) is subjected to plasma treatment, and then the slurry prepared in step (4) is coated on both sides of the fluoropolymer layer to form a modified PTFE layer. Finally, the fluoropolymer-modified PTFE composite layer is prepared by low-temperature drying, medium-temperature curing and high-temperature sintering.

[0057] (6) A high-frequency flexible copper-clad board is prepared by pressing and post-processing the double-sided copper foil of the fluoropolymer-modified PTFE composite layer using a vacuum hot press forming machine.

[0058] in:

[0059] The synthesis method of trifluorochloroethylene-vinyl ether fluororesin emulsion in step (1) is as follows: Wang Jiaqiang, Hou Chuanjin, Liu Yanjun. Synthesis and properties of trifluorochloroethylene-vinyl ether fluororesin emulsion [J]. Journal of Dalian University of Technology, 2022, 41(6):424-427.

[0060] In step (1), the tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer emulsion was manufactured by 3M Chemicals, model number 6910GZ, with a solid content of 50%.

[0061] In step (1), the mass ratio of trifluorochloroethylene-vinyl ether fluororesin emulsion to tetrafluoroethylene-perfluoroalkoxyvinyl ether copolymer emulsion is 3.1:10; the stirring speed is 200 r / min and the stirring time is 10 min.

[0062] In step (2), after pumping in at a constant speed, the shearing speed is controlled at 6000 r / min.

[0063] In step (2), the mass ratio of fluorinated emulsion matrix to deionized water is 1:1.

[0064] In step (2), the mass ratio of the fluorinated emulsion matrix to deionized water and to the isosorbide-type polycarbonate-dichloromethane mixture is 3.1:1.

[0065] In step (2), the isosorbide-type polycarbonate-dichloromethane mixture comprises 20% of the total mass of isosorbide-type polycarbonate and dichloromethane. The isosorbide-type polycarbonate is manufactured by Mitsubishi Corporation of Japan and is model DURABIO. TM D7340.

[0066] The preparation method of the silane coupling agent pre-hydrolyzed solution in step (2) is as follows: mix methacryloyloxypropyltrimethoxysilane with deionized water, add ammonia to adjust the pH of the reaction system to 10, and pre-hydrolyze at room temperature for 21 min to obtain the silane coupling agent pre-hydrolyzed solution; wherein, the mass concentration of ammonia is 25%, and the mass ratio of methacryloyloxypropyltrimethoxysilane to deionized water is 1:1.

[0067] In step (2), the mass ratio of methacryloyloxypropyltrimethoxysilane in the silane coupling agent pre-hydrolyzed solution to isosorbide-type polycarbonate in the isosorbide-dichloromethane mixture is 1:2.5.

[0068] In step (2), the rotary evaporation is first carried out at a pressure of -0.03 MPa for 11 min, then at a pressure of -0.06 MPa for 11 min, and finally at a pressure of -0.09 MPa for 22 min. The rotary evaporation temperature is controlled at 42℃ throughout the process.

[0069] The filter membrane used in step (2) has a pore size of 0.45 micrometers.

[0070] The PI film mentioned in step (3) is manufactured by DuPont, Inc., USA, and its model is Kapton. ® 100EN.

[0071] In step (4), the thickener solution is obtained by mixing the thickener and deionized water at room temperature. The mass of the deionized water is 7 times the mass of the thickener. The manufacturer of the thickener is Qingdao Enze Chemical Co., Ltd., and the model is thickener TT-935.

[0072] In step (4), the PTFE emulsion is manufactured by Daikin Industries, Japan, model D210, with a solid content of 60%.

[0073] In step (4), the mass of the thickener in the thickener solution accounts for 1.7% of the total mass of the mixture of PTFE emulsion, modified fluorinated graphene, and nano-silicon nitride.

[0074] In step (4), the mass ratio of PTFE emulsion to deionized water is 3.1:2.

[0075] In step (4), the mass of the mixture of modified fluorinated graphene and nano-silicon nitride accounts for 21% of the mass of the PTFE emulsion.

[0076] The preparation method of the mixture of modified fluorinated graphene and nano silicon nitride in step (4) is as follows: anhydrous ethanol and ammonia water with a mass concentration of 25% are mixed at a volume ratio of 95:5 to prepare a solvent. KH-560 silane coupling agent and tridecafluorooctyltrimethoxysilane are mixed at a mass ratio of 1:1 and added to the solvent. The mixture is hydrolyzed at room temperature for 20 min. Then, fluorinated graphene and nano silicon nitride are added to the silane hydrolysate at one time. The mixture is sonicated for 20 min and then stirred at room temperature for 2 h. The mixture is filtered, washed three times with deionized water, and finally vacuum dried and passed through a 300-mesh sieve to prepare the mixture of modified fluorinated graphene and nano silicon nitride.

[0077] In step (4), the ultrasonic power is 200W, the stirring speed is 500r / min, the vacuum drying temperature is 80℃, and the vacuum drying time is 12h.

[0078] In the preparation method of the mixture of modified fluorinated graphene and nano silicon nitride described in step (4), the mass ratio of fluorinated graphene to nano silicon nitride is 1.2:2; the mass of KH-560 silane coupling agent and tridecafluorooctyltrimethoxysilane accounts for 21% of the mass of fluorinated graphene and nano silicon nitride.

[0079] In step (5), the volume ratio of argon to oxygen in the plasma treatment is 9:1, the total gas flow rate is 18L / min, the plasma power is 450W, the distance from the surface of the fluoropolymer layer to the spray gun is 9mm, and the treatment speed is 2.5m / min.

[0080] In step (5), the low-temperature drying temperature is 91℃ and the low-temperature drying time is 14min, the medium-temperature curing temperature is 171℃ and the medium-temperature curing time is 24min, the high-temperature sintering temperature is 386℃ and the high-temperature sintering time is 87min.

[0081] In step (6), the copper foil is HVLP2 copper foil.

[0082] In step (6), the pressing is carried out by heating to the pressing temperature at a heating rate of 6℃ / min, the pressing temperature is 311℃, the pressing pressure is 2.5MPa, the pressing time is 25min, and the vacuum degree is -0.095MPa.

[0083] The post-processing described in step (6) involves removing the high-frequency flexible copper-clad laminate from the vacuum hot press forming machine at 50°C, and then drying the high-frequency flexible copper-clad laminate at 57°C for 2 hours to obtain the high-frequency flexible copper-clad laminate.

[0084] The dielectric constant D of the high-frequency flexible copper-clad laminate prepared in Example 1 was tested at 10 GHz. k The dielectric loss D is 2.06. f The strength is 0.0014, the peel strength is 1.5 kgf / cm, the tensile strength is 220 MPa, the dimensional stability TD is 0.12%, and the dimensional stability MD is 0.10%.

[0085] Example 2

[0086] The method for preparing the high-frequency flexible copper-clad laminate described in Example 2 consists of the following steps:

[0087] (1) Preparation of fluorinated emulsion matrix

[0088] A fluorinated emulsion matrix was prepared by stirring and mixing a trifluorochloroethylene-vinyl ether fluororesin emulsion with a tetrafluoroethylene-perfluoroalkoxyvinyl ether copolymer emulsion.

[0089] (2) Preparation of composite emulsion

[0090] Fluorinated emulsion matrix and deionized water were added to an emulsification tank and sheared at a high speed of 8000 r / min. Then, isosorbide-based polycarbonate-dichloromethane mixture was pumped into the above reaction system at a uniform rate over 28 min. Finally, silane coupling agent pre-hydrolysis solution was added and shearing was continued for 10 min. Ammonia was added to adjust the pH of the reaction system to 10. Dichloromethane was removed by rotary evaporation. Deionized water was added to control the solid content of the emulsion to 30%. The mixture was filtered to prepare a composite emulsion.

[0091] (3) The composite emulsion prepared in step (2) is coated onto both sides of the PI film, placed in a 90°C oven, dried for 15 min, heated to 170°C and kept warm for 60 min to obtain a fluoropolymer layer;

[0092] (4) Mix PTFE emulsion, thickener solution and deionized water to prepare a mixture, then add the mixture of modified fluorinated graphene and nano silicon nitride to the mixture, add ammonia water with a mass concentration of 25% to adjust the pH of the system to 9.0, and prepare a slurry.

[0093] (5) The fluoropolymer layer prepared in step (3) is subjected to plasma treatment, and then the slurry prepared in step (4) is coated on both sides of the fluoropolymer layer to form a modified PTFE layer. Finally, the fluoropolymer-modified PTFE composite layer is prepared by low-temperature drying, medium-temperature curing and high-temperature sintering.

[0094] (6) A high-frequency flexible copper-clad board is prepared by pressing and post-processing the double-sided copper foil of the fluoropolymer-modified PTFE composite layer using a vacuum hot press forming machine.

[0095] in:

[0096] The synthesis method of trifluorochloroethylene-vinyl ether fluororesin emulsion in step (1) is as follows: Wang Jiaqiang, Hou Chuanjin, Liu Yanjun. Synthesis and properties of trifluorochloroethylene-vinyl ether fluororesin emulsion [J]. Journal of Dalian University of Technology, 2022, 41(6):424-427.

[0097] In step (1), the tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer emulsion was manufactured by 3M Chemicals, model number 6910GZ, with a solid content of 50%.

[0098] In step (1), the mass ratio of trifluorochloroethylene-vinyl ether fluororesin emulsion to tetrafluoroethylene-perfluoroalkoxyvinyl ether copolymer emulsion is 3:10; the stirring speed is 200 r / min and the stirring time is 10 min.

[0099] In step (2), after pumping in at a constant speed, the shearing speed is controlled at 6000 r / min.

[0100] In step (2), the mass ratio of fluorinated emulsion matrix to deionized water is 1:1.

[0101] In step (2), the mass ratio of the fluorinated emulsion matrix to deionized water and to the isosorbide-type polycarbonate-dichloromethane mixture is 3:1.

[0102] In step (2), the isosorbide-type polycarbonate-dichloromethane mixture comprises 20% of the total mass of isosorbide-type polycarbonate and dichloromethane. The isosorbide-type polycarbonate is manufactured by Mitsubishi Corporation of Japan and is model DURABIO. TM D7340.

[0103] The preparation method of the silane coupling agent pre-hydrolyzed solution in step (2) is as follows: mix methacryloyloxypropyltrimethoxysilane with deionized water, add ammonia to adjust the pH of the reaction system to 10, and pre-hydrolyze at room temperature for 20 min to prepare the silane coupling agent pre-hydrolyzed solution; wherein, the mass concentration of ammonia is 25%, and the mass ratio of methacryloyloxypropyltrimethoxysilane to deionized water is 1:1.

[0104] In step (2), the mass ratio of methacryloyloxypropyltrimethoxysilane in the silane coupling agent pre-hydrolyzed solution to isosorbide-type polycarbonate in the isosorbide-dichloromethane mixture is 1:2.5.

[0105] In step (2), the rotary evaporation is first carried out at a pressure of -0.03 MPa for 10 minutes, then at a pressure of -0.06 MPa for 10 minutes, and finally at a pressure of -0.09 MPa for 23 minutes. The rotary evaporation temperature is controlled at 42℃ throughout the process.

[0106] The filter membrane used in step (2) has a pore size of 0.45 micrometers.

[0107] The PI film mentioned in step (3) is manufactured by DuPont, Inc., USA, and its model is Kapton. ® 100EN.

[0108] In step (4), the thickener solution is obtained by mixing the thickener and deionized water at room temperature. The mass of the deionized water is 7 times the mass of the thickener. The manufacturer of the thickener is Qingdao Enze Chemical Co., Ltd., and the model is thickener TT-935.

[0109] In step (4), the PTFE emulsion is manufactured by Daikin Industries, Japan, model D210, with a solid content of 60%.

[0110] In step (4), the mass of the thickener in the thickener solution accounts for 1.7% of the total mass of the mixture of PTFE emulsion, modified fluorinated graphene, and nano-silicon nitride.

[0111] In step (4), the mass ratio of PTFE emulsion to deionized water is 3:2.

[0112] In step (4), the mass of the mixture of modified fluorinated graphene and nano-silicon nitride accounts for 20% of the mass of the PTFE emulsion.

[0113] The preparation method of the mixture of modified fluorinated graphene and nano silicon nitride in step (4) is as follows: anhydrous ethanol and ammonia water with a mass concentration of 25% are mixed at a volume ratio of 95:5 to prepare a solvent. KH-560 silane coupling agent and tridecafluorooctyltrimethoxysilane are mixed at a mass ratio of 1:1 and added to the solvent. The mixture is hydrolyzed at room temperature for 20 min. Then, fluorinated graphene and nano silicon nitride are added to the silane hydrolysate at one time. The mixture is sonicated for 20 min and then stirred at room temperature for 2 h. The mixture is filtered, washed three times with deionized water, and finally vacuum dried and passed through a 300-mesh sieve to prepare the mixture of modified fluorinated graphene and nano silicon nitride.

[0114] In step (4), the ultrasonic power is 200W, the stirring speed is 500r / min, the vacuum drying temperature is 80℃, and the vacuum drying time is 12h.

[0115] In step (4), the mass ratio of fluorinated graphene to nano-silicon nitride in the preparation method of the mixture of modified fluorinated graphene and nano-silicon nitride is 1:2; the mass of KH-560 silane coupling agent and tridecafluorooctyltrimethoxysilane accounts for 20% of the mass of fluorinated graphene and nano-silicon nitride.

[0116] In step (5), the volume ratio of argon to oxygen in the plasma treatment is 9:1, the total gas flow rate is 18L / min, the plasma power is 450W, the distance from the surface of the fluoropolymer layer to the spray gun is 9mm, and the treatment speed is 2.5m / min.

[0117] In step (5), the low-temperature drying temperature is 90℃ and the low-temperature drying time is 15min, the medium-temperature curing temperature is 170℃ and the medium-temperature curing time is 25min, the high-temperature sintering temperature is 385℃ and the high-temperature sintering time is 85min.

[0118] In step (6), the copper foil is HVLP2 copper foil.

[0119] The pressing in step (6) is achieved by heating to the pressing temperature at a rate of 6℃ / min, with a pressing temperature of 310℃, a pressing pressure of 2.5MPa, a pressing time of 25min, and a vacuum degree of -0.095MPa.

[0120] The post-processing described in step (6) involves removing the high-frequency flexible copper-clad laminate from the vacuum hot press at 50°C, and then drying the high-frequency flexible copper-clad laminate at 55°C for 2 hours to obtain the high-frequency flexible copper-clad laminate.

[0121] The dielectric constant D of the high-frequency flexible copper-clad laminate prepared in Example 2 was tested at 10 GHz. kThe dielectric loss D is 2.04. f The strength is 0.0015, the peel strength is 1.3 kgf / cm, the tensile strength is 212 MPa, the dimensional stability TD is 0.15%, and the dimensional stability MD is 0.13%.

[0122] Example 3

[0123] The method for preparing the high-frequency flexible copper-clad laminate described in Example 3 consists of the following steps:

[0124] (1) Preparation of fluorinated emulsion matrix

[0125] A fluorinated emulsion matrix was prepared by stirring and mixing a trifluorochloroethylene-vinyl ether fluororesin emulsion with a tetrafluoroethylene-perfluoroalkoxyvinyl ether copolymer emulsion.

[0126] (2) Preparation of composite emulsion

[0127] Fluorinated emulsion matrix and deionized water were added to an emulsification tank and sheared at a high speed of 8000 r / min. Then, isosorbide-based polycarbonate-dichloromethane mixture was pumped into the above reaction system at a uniform rate over 30 min. Finally, silane coupling agent pre-hydrolysis solution was added and shearing was continued for 13 min. Ammonia was added to adjust the pH of the reaction system to 10. Dichloromethane was removed by rotary evaporation. Deionized water was added to control the solid content of the emulsion to 30%. The mixture was filtered to prepare a composite emulsion.

[0128] (3) The composite emulsion prepared in step (2) is coated onto both sides of the PI film, placed in an oven at 100°C, dried for 10 min, and then heated to 180°C and kept at that temperature for 50 min to obtain a fluoropolymer layer.

[0129] (4) Mix PTFE emulsion, thickener solution and deionized water to prepare a mixture, then add the mixture of modified fluorinated graphene and nano silicon nitride to the mixture, add ammonia water with a mass concentration of 25% to adjust the pH of the system to 9.0, and prepare a slurry.

[0130] (5) The fluoropolymer layer prepared in step (3) is subjected to plasma treatment, and then the slurry prepared in step (4) is coated on both sides of the fluoropolymer layer to form a modified PTFE layer. Finally, the fluoropolymer-modified PTFE composite layer is prepared by low-temperature drying, medium-temperature curing and high-temperature sintering.

[0131] (6) A high-frequency flexible copper-clad board is prepared by pressing and post-processing the double-sided copper foil of the fluoropolymer-modified PTFE composite layer using a vacuum hot press forming machine.

[0132] in:

[0133] The synthesis method of trifluorochloroethylene-vinyl ether fluororesin emulsion in step (1) is as follows: Wang Jiaqiang, Hou Chuanjin, Liu Yanjun. Synthesis and properties of trifluorochloroethylene-vinyl ether fluororesin emulsion [J]. Journal of Dalian University of Technology, 2022, 41(6):424-427.

[0134] In step (1), the tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer emulsion was manufactured by 3M Chemicals, model number 6910GZ, with a solid content of 50%.

[0135] In step (1), the mass ratio of trifluorochloroethylene-vinyl ether fluororesin emulsion to tetrafluoroethylene-perfluoroalkoxyvinyl ether copolymer emulsion is 3.2:10; the stirring speed is 200 r / min and the stirring time is 10 min.

[0136] In step (2), after pumping in at a constant speed, the shearing speed is controlled at 6000 r / min.

[0137] In step (2), the mass ratio of fluorinated emulsion matrix to deionized water is 1:1.

[0138] In step (2), the mass ratio of the fluorinated emulsion matrix to deionized water and to the isosorbide-type polycarbonate-dichloromethane mixture is 3.2:1.

[0139] In step (2), the isosorbide-type polycarbonate-dichloromethane mixture comprises 20% of the total mass of isosorbide-type polycarbonate and dichloromethane. The isosorbide-type polycarbonate is manufactured by Mitsubishi Corporation of Japan and is model DURABIO. TM D7340.

[0140] The preparation method of the silane coupling agent pre-hydrolyzed solution in step (2) is as follows: mix methacryloyloxypropyltrimethoxysilane with deionized water, add ammonia to adjust the pH of the reaction system to 10, and pre-hydrolyze at room temperature for 23 min to obtain the silane coupling agent pre-hydrolyzed solution; wherein, the mass concentration of ammonia is 25%, and the mass ratio of methacryloyloxypropyltrimethoxysilane to deionized water is 1:1.

[0141] In step (2), the mass ratio of methacryloyloxypropyltrimethoxysilane in the silane coupling agent pre-hydrolyzed solution to isosorbide-type polycarbonate in the isosorbide-dichloromethane mixture is 1:2.5.

[0142] In step (2), the rotary evaporation is first carried out at a pressure of -0.03 MPa for 12 minutes, then at a pressure of -0.06 MPa for 12 minutes, and finally at a pressure of -0.09 MPa for 20 minutes. The rotary evaporation temperature is controlled at 42℃ throughout the process.

[0143] The filter membrane used in step (2) has a pore size of 0.45 micrometers.

[0144] The PI film mentioned in step (3) is manufactured by DuPont, Inc., USA, and its model is Kapton. ® 100EN.

[0145] In step (4), the thickener solution is obtained by mixing the thickener and deionized water at room temperature. The mass of the deionized water is 7 times the mass of the thickener. The manufacturer of the thickener is Qingdao Enze Chemical Co., Ltd., and the model is thickener TT-935.

[0146] In step (4), the PTFE emulsion is manufactured by Daikin Industries, Japan, model D210, with a solid content of 60%.

[0147] In step (4), the mass of the thickener in the thickener solution accounts for 1.7% of the total mass of the mixture of PTFE emulsion, modified fluorinated graphene, and nano-silicon nitride.

[0148] In step (4), the mass ratio of PTFE emulsion to deionized water is 3.2:2.

[0149] In step (4), the mass of the mixture of modified fluorinated graphene and nano-silicon nitride accounts for 22% of the mass of the PTFE emulsion.

[0150] The preparation method of the mixture of modified fluorinated graphene and nano silicon nitride in step (4) is as follows: anhydrous ethanol and ammonia water with a mass concentration of 25% are mixed at a volume ratio of 95:5 to prepare a solvent. KH-560 silane coupling agent and tridecafluorooctyltrimethoxysilane are mixed at a mass ratio of 1:1 and added to the solvent. The mixture is hydrolyzed at room temperature for 20 min. Then, fluorinated graphene and nano silicon nitride are added to the silane hydrolysate at one time. The mixture is sonicated for 20 min and then stirred at room temperature for 2 h. The mixture is filtered, washed three times with deionized water, and finally vacuum dried and passed through a 300-mesh sieve to prepare the mixture of modified fluorinated graphene and nano silicon nitride.

[0151] In step (4), the ultrasonic power is 200W, the stirring speed is 500r / min, the vacuum drying temperature is 80℃, and the vacuum drying time is 12h.

[0152] In step (4), the mass ratio of fluorinated graphene to nano-silicon nitride in the preparation method of the mixture of modified fluorinated graphene and nano-silicon nitride is 1.3:2; the mass of KH-560 silane coupling agent and tridecafluorooctyltrimethoxysilane accounts for 22% of the mass of fluorinated graphene and nano-silicon nitride.

[0153] In step (5), the volume ratio of argon to oxygen in the plasma treatment is 9:1, the total gas flow rate is 18L / min, the plasma power is 450W, the distance from the surface of the fluoropolymer layer to the spray gun is 9mm, and the treatment speed is 2.5m / min.

[0154] In step (5), the low-temperature drying temperature is 92℃ and the low-temperature drying time is 13min, the medium-temperature curing temperature is 173℃ and the medium-temperature curing time is 23min, the high-temperature sintering temperature is 388℃ and the high-temperature sintering time is 90min.

[0155] In step (6), the copper foil is HVLP2 copper foil.

[0156] In step (6), the pressing is carried out by heating to the pressing temperature at a rate of 6℃ / min, the pressing temperature is 313℃, the pressing pressure is 2.5MPa, the pressing time is 25min, and the vacuum degree is -0.095MPa.

[0157] The post-processing described in step (6) involves removing the high-frequency flexible copper-clad laminate from the vacuum hot press at 50°C, and then drying the high-frequency flexible copper-clad laminate at 60°C for 2 hours to obtain the high-frequency flexible copper-clad laminate.

[0158] The dielectric constant D of the high-frequency flexible copper-clad laminate prepared in Example 3 was tested at 10 GHz. k The dielectric loss D is 2.08. f The strength is 0.0012, the peel strength is 1.6 kgf / cm, the tensile strength is 228 MPa, the dimensional stability TD is 0.10%, and the dimensional stability MD is 0.08%.

[0159] Comparative Example 1

[0160] The preparation method of the high-frequency flexible copper-clad laminate described in Comparative Example 1 is the same as that in Example 1. The only difference is that the composite emulsion is no longer prepared. Instead, the slurry prepared in step (4) is directly coated onto both sides of the PI film, and then copper foil is applied to both sides to prepare the high-frequency flexible copper-clad laminate.

[0161] The dielectric constant D of the high-frequency flexible copper-clad laminate prepared in Comparative Example 1 was tested at 10 GHz. k The dielectric loss D is 2.20. f The strength is 0.0028, the peel strength is 0.5 kgf / cm, the tensile strength is 200 MPa, the dimensional stability TD is 0.35%, and the dimensional stability MD is 0.30%.

[0162] Comparative Example 2

[0163] The preparation method of the high-frequency flexible copper-clad laminate described in Comparative Example 2 is the same as that in Example 1, except that: no modified PTFE layer is prepared, and copper foil is only coated on both sides of the fluoropolymer layer to prepare the high-frequency flexible copper-clad laminate.

[0164] The dielectric constant D of the high-frequency flexible copper-clad laminate prepared in Comparative Example 2 was tested at 10 GHz. k The dielectric loss is 3.30, and the dielectric loss D is 3.30. f The strength is 0.0032, the peel strength is 0.8 kgf / cm, the tensile strength is 180 MPa, the dimensional stability TD is 0.25%, and the dimensional stability MD is 0.22%.

[0165] Therefore, it can be seen that the performance of the high-frequency flexible copper-clad laminates prepared in Examples 1-3 is significantly better than that of Comparative Examples 1-2. The performance of Comparative Examples 1-2 is reduced due to the lack of fluoropolymer layer or modified PTFE layer.

Claims

1. A method for preparing a high-frequency flexible copper-clad laminate, characterized in that: Comprise the following steps: (1) Preparation of fluorine-containing emulsion base The trifluorochloroethylene-vinyl ether fluororesin emulsion and the tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer emulsion are mixed by stirring to prepare a fluorine-containing emulsion base; (2) Preparation of composite emulsion The fluorine-containing emulsion base and deionized water are added to the emulsification kettle, high-speed shearing is carried out at a speed of 8000 r / min, then the isosorbide polycarbonate-dichloromethane mixed solution is pumped into the above reaction system at a constant speed within 28-30 min, finally the pre-hydrolysis solution of silane coupling agent is added and shearing is continued for 10-13 min, ammonia water is added to adjust the pH value of the reaction system to 10, dichloromethane is removed by rotary evaporation, deionized water is added to control the solid content of the emulsion to 30%, and filtration is carried out to prepare a composite emulsion; (3) The composite emulsion prepared in step (2) is coated on both sides of the PI film, placed in an oven at 90-100℃, dried for 10-15 min, heated to 170-180℃ and kept for 50-60 min to prepare a fluorine-containing polymer layer; (4) The PTFE emulsion, thickening agent solution and deionized water are uniformly mixed to prepare a mixed solution, then the mixture of modified fluorinated graphene and nano silicon nitride is added to the mixed solution, ammonia water with a mass concentration of 25% is added to adjust the pH value of the system to 9.0 to prepare a slurry; (5) The fluorine-containing polymer layer prepared in step (3) is subjected to plasma treatment, then the slurry prepared in step (4) is coated on both sides of the fluorine-containing polymer layer to form a modified PTFE layer, and finally low-temperature drying, medium-temperature curing and high-temperature sintering are carried out to prepare a fluorine-containing polymer-modified PTFE composite layer; (6) Copper foil is coated on both sides of the fluorine-containing polymer-modified PTFE composite layer, vacuum hot pressing is carried out by a vacuum hot pressing machine, and post-processing is carried out to prepare a high-frequency flexible copper-clad plate; In step (4), the preparation method of the mixture of modified fluorinated graphene and nano silicon nitride is as follows: anhydrous ethanol and ammonia water with a mass concentration of 25% are mixed in a volume ratio of 95:5 to prepare a solvent, KH-560 silane coupling agent and tridecafluorooctyltrimethoxysilane are uniformly mixed in a mass ratio of 1:1 and added to the solvent, hydrolysis is carried out at room temperature for 20 min, then fluorinated graphene and nano silicon nitride are added at once to the silane hydrolysis solution, ultrasonic treatment is carried out for 20 min, then stirring is continued at room temperature for 2 h, filtration is carried out, washing with deionized water is carried out for 3 times, and finally vacuum drying is carried out through a 300 mesh sieve to prepare the mixture of modified fluorinated graphene and nano silicon nitride.

2. The method for preparing high-frequency flexible copper-clad laminate according to claim 1, characterized in that: In step (1), the mass ratio of trifluorochloroethylene-vinyl ether fluororesin emulsion to tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer emulsion is 3-3.2:10; the stirring and mixing speed is 200 r / min, and the stirring and mixing time is 10 min.

3. The method for preparing high-frequency flexible copper-clad laminate according to claim 1, characterized in that: In step (2), the shearing speed is controlled to 6000 r / min after pumping at a constant speed; In step (2), the mass ratio of fluorine-containing emulsion base to deionized water is 1:1; The mass ratio of the fluorine-containing emulsion base in step (2) to deionized water and to the isosorbide polycarbonate-dichloromethane mixture is 3-3.2:1; The mass of the isosorbide polycarbonate in the isosorbide polycarbonate-dichloromethane mixture in step (2) accounts for 20% of the mass sum of the isosorbide polycarbonate and dichloromethane; The preparation method of the silane coupling agent pre-hydrolysis solution in step (2) is as follows: mixing methacryloxypropyl trimethoxysilane and deionized water, adding ammonia water to adjust the pH of the reaction system to 10, and pre-hydrolyzing at room temperature for 20-23 min to obtain the silane coupling agent pre-hydrolysis solution; wherein the mass concentration of the ammonia water is 25%, and the mass ratio of the methacryloxypropyl trimethoxysilane to the deionized water is 1:

1.

4. The method for preparing high-frequency flexible copper-clad laminate according to claim 1, characterized in that: The mass ratio of the methacryloxypropyl trimethoxysilane in the silane coupling agent pre-hydrolysis solution in step (2) to the isosorbide polycarbonate in the isosorbide polycarbonate-dichloromethane mixture is 1:2.5; In step (2), the rotary evaporation is first carried out at a pressure of -0.03 MPa for 10-12 min, then at a pressure of -0.06 MPa for 10-12 min, and finally at a pressure of -0.09 MPa for 20-23 min, with the rotary evaporation temperature controlled at 42°C throughout the process; The filter membrane pore size used in the filtration in step (2) is 0.45 microns.

5. The method for preparing a high-frequency flexible copper-clad laminate according to claim 1, characterized in that: The thickening agent solution in step (4) is obtained by stirring and mixing the thickening agent and deionized water at room temperature, and the mass of the deionized water is 7 times the mass of the thickening agent. The mass of the thickening agent in the thickening agent solution in step (4) accounts for 1.7% of the mass sum of the PTFE emulsion and the mixture of modified fluorinated graphene and nano silicon nitride. The mass ratio of the PTFE emulsion to deionized water in step (4) is 3-3.2:

2. The mass of the mixture of modified fluorinated graphene and nano silicon nitride in step (4) accounts for 20-22% of the mass of the PTFE emulsion.

6. The method for preparing high-frequency flexible copper-clad laminate according to claim 1, characterized in that: In the preparation method of the mixture of modified fluorinated graphene and nano silicon nitride in step (4), the ultrasonic power is 200 W, the stirring speed is 500 r / min, the vacuum drying temperature is 80°C, and the vacuum drying time is 12 h. In the preparation method of the mixture of modified fluorinated graphene and nano silicon nitride in step (4), the mass ratio of the fluorinated graphene to the nano silicon nitride is 1-1.3:2, and the mass sum of the KH-560 silane coupling agent and the tridecafluorooctyltrimethoxysilane accounts for 20-22% of the mass sum of the fluorinated graphene and the nano silicon nitride.

7. The method for preparing high-frequency flexible copper-clad laminate according to claim 1, characterized in that: In step (5), the volume ratio of argon to oxygen in the plasma treatment is 9:1, the total gas flow is 18 L / min, the plasma power is 450 W, the distance from the surface of the fluorine-containing polymer layer to the spray gun is 9 mm, and the treatment speed is 2.5 m / min. The low-temperature drying temperature in step (5) is 90-92℃, the low-temperature drying time is 13-15min, the medium-temperature curing temperature is 170-173℃, the medium-temperature curing time is 23-25min, the high-temperature sintering temperature is 385-388℃, and the high-temperature sintering time is 85-90min.

8. The method for preparing high-frequency flexible copper-clad laminate according to claim 1, characterized in that: The copper foil in step (6) is HVLP2 copper foil. In step (6), the pressing is heated to a pressing temperature at a heating rate of 6℃ / min, the pressing temperature is 310-313℃, the pressing pressure is 2.5MPa, the pressing time is 25min, and the vacuum degree is-0.095MPa. In step (6), the post-treatment is that the high-frequency flexible copper-clad plate after pressing is taken out from the vacuum hot-pressing machine after being reduced to 50℃, and then the high-frequency flexible copper-clad plate after pressing is dried at 55-60℃ for 2h to obtain the high-frequency flexible copper-clad plate.