Film and method of making same, circuit substrate, printed circuit board

Abstract

The present application relates to a kind of preparation methods of film, comprising the following steps: after mixing fiber, coupling agent and water, it is carried out broom processing, obtain first pretreatment liquid, the dissociation degree of the first pretreatment liquid is 75%-90%;Fluorine resin emulsion, flocculating agent and water are mixed, to obtain second pretreatment liquid, the second pretreatment liquid has fluorine resin flocculating particle with particle size of 30 μm-100 μm;The first pretreatment liquid and the second pretreatment liquid are mixed, to obtain slurry;The slurry is dehydrated and formed, and film is obtained after baking.The present application also relates to a kind of film, circuit substrate and printed circuit board.The preparation method of the present application can make fiber and fluorine resin between combination closely, guarantee the high density and low water absorption of film, simultaneously, can make fiber distribute evenly in film, so that the dielectric properties of film present isotropy, to make circuit substrate have excellent and stable dielectric properties.

Description

Technical Field

[0001] This invention relates to the field of electronic industry technology, and in particular to films and their preparation methods, circuit boards, and printed circuit boards. Background Technology

[0002] With the advanced development of printed circuit board (PCB) manufacturing technology, the requirements for its substrate materials have become increasingly sophisticated. In today's era of continuous development in high-frequency or high-speed digital signal transmission technology, maintaining a constant and stable characteristic impedance of transmission lines on a PCB has led to the recent demand for high-precision control of the characteristic impedance of copper-clad laminates (CCLs), a new challenge for the CCL industry. This performance requirement is comprised of multiple CCL performance parameters, such as low dielectric constant, low water absorption, high thickness precision, and high copper foil thickness stability. The high insulation reliability required of multilayer boards is also a comprehensive reflection of multiple performance characteristics. To achieve high reliability, CCLs must possess high heat resistance, moisture resistance (low water absorption), high insulation performance under humid or hot conditions, and excellent intralayer adhesion.

[0003] In traditional copper clad laminates, the dielectric properties of prepregs made using fiber cloth and other reinforcing materials vary in different directions due to the glass fiber effect. Furthermore, the high water absorption rate of reinforcing materials such as fiber cloth leads to a high water absorption rate in the prepreg, affecting the stability of the dielectric properties of the final product. Consequently, copper clad laminates cannot maintain the normal operation of electronic components in high-temperature and high-humidity environments, thus limiting their use. Summary of the Invention

[0004] Therefore, it is necessary to provide a film and its preparation method, a circuit board, and a printed circuit board to address the above problems. The film obtained by the preparation method has high density and low water absorption, so that the circuit board made from the film has stable dielectric properties and the dielectric properties are isotropic.

[0005] A method for preparing film includes the following steps:

[0006] The fiber, coupling agent and water are mixed and then subjected to a buffing treatment to obtain a first pretreatment solution with a degree of dissociation of 75%-90%.

[0007] A second pretreatment solution is obtained by mixing a fluorinated resin emulsion, a flocculant, and water. The second pretreatment solution contains fluorinated resin flocculent particles with a particle size of 30μm-100μm.

[0008] The first pretreatment liquid and the second pretreatment liquid are mixed to obtain a slurry; and

[0009] The slurry is dehydrated, shaped, and baked to obtain a film.

[0010] In one embodiment, the step of mixing the fiber, coupling agent, and water and then performing a buffing treatment involves rotating at a speed of 1000 r / min to 3000 r / min for 30 to 60 minutes.

[0011] In one embodiment, in the step of mixing the fiber, coupling agent, and water and then performing a buffing treatment, the fiber is 10 parts by weight and the coupling agent is 0.05-0.2 parts by weight.

[0012] In one embodiment, the fiber has a length of 100μm-400μm, a diameter of 1μm-20μm, and an aspect ratio of 5:1-400:1.

[0013] In one embodiment, the molecular chain of the coupling agent includes at least one of an amino group and a benzene ring.

[0014] In one embodiment, in the step of mixing the fluorinated resin emulsion, flocculant and water, the fluorinated resin emulsion is 10 parts by weight and the flocculant is 0.01-0.1 parts by weight.

[0015] In one embodiment, the fluorinated resin emulsion is selected from at least one of polytetrafluoroethylene emulsion, tetrafluoroethylene-hexafluoropropylene copolymer emulsion, tetrafluoroethylene-ethylene copolymer emulsion, and polyvinylidene fluoride emulsion.

[0016] In one embodiment, the mass ratio of fiber to fluorinated resin in the slurry is 1:10 to 5:10.

[0017] A film prepared by the aforementioned preparation method.

[0018] A circuit board includes an insulating layer and a conductive layer disposed on at least one surface of the insulating layer, wherein the insulating layer is formed by pressing one or at least two laminated films.

[0019] A printed circuit board made from the aforementioned circuit substrate.

[0020] In the preparation method of the film of this invention, the fibers are first subjected to a fissuring treatment and the degree of dissociation is controlled. The fluoropolymer emulsion is then subjected to a flocculation treatment and the particle size of the fluoropolymer flocculants is controlled. After mixing the two, the fissuring portions at both ends of the fibers can insert into the spaces between the fluoropolymer flocculants, or the fibers can wrap around the fluoropolymer flocculants. Furthermore, in the film obtained by the copying process of this invention, the fibers and fluoropolymer are tightly bonded, ensuring high density and low water absorption of the film. Simultaneously, the fibers are evenly distributed throughout the film.

[0021] Therefore, the circuit board made using the film of this invention is free from the influence of glass fiber effect, has stable dielectric properties and isotropic, meets the transmission requirements of different signal directions, has better performance, and can maintain the normal operation of electronic components in high temperature and high humidity environments. Detailed Implementation

[0022] The following will further describe the film, its preparation method, circuit board, and printed circuit board provided by the present invention.

[0023] The film provided by this invention is mainly used for preparing circuit boards, and the preparation method of the film mainly includes the following steps:

[0024] S1, after mixing the fiber, coupling agent and water, the mixture is subjected to a buffing treatment to obtain a first pretreatment solution, wherein the degree of dissociation of the first pretreatment solution is 75%-90%.

[0025] S2, fluorinated resin emulsion, flocculant and water are mixed to obtain a second pretreatment liquid, the second pretreatment liquid containing fluorinated resin flocculent particles with a particle size of 30μm-100μm;

[0026] S3, mix the first pretreatment liquid and the second pretreatment liquid to obtain a slurry;

[0027] S4, the slurry is dehydrated, shaped, and baked to obtain a film.

[0028] In step S1, the step of mixing the fiber, coupling agent and water and then performing buffing treatment is preferably carried out in a defibration machine. By defibration the fiber in the defibration machine, the fiber can be stretched out and buffing phenomenon will appear at both ends.

[0029] Optionally, during the buffing process, the following methods can be used to promote fiber buffing.

[0030] Method 1: During broom treatment, the preferred rotation speed is 1000 r / min-3000 r / min, and the preferred time is 30 minutes-60 minutes.

[0031] Method 2: The length of the fiber is preferably 100μm-400μm, more preferably 150μm-300μm, the diameter is preferably 1μm-20μm, more preferably 4μm-15μm, and the aspect ratio is preferably 5:1-400:1, more preferably 10:1-200:1.

[0032] Method 3: The amount of the coupling agent is 0.05-0.2 parts by weight, based on 10 parts by weight of fiber.

[0033] Since the degree of fiber fibrillation affects the density of the film and ultimately the dielectric loss of the circuit board, the degree of fibrillation of different fibers can be controlled by reasonably selecting the above methods or a combination of the above methods during fibrillation treatment, so that the degree of fiber fibrillation is consistent, such as the combination of method one and method three.

[0034] In addition, the range of fiber length, diameter, and aspect ratio can promote the construction of a connection structure between the fibers in the film, thereby improving the strength of the film; the range of rotation speed and time can also protect the fibers and prevent them from breaking during the buffing process.

[0035] Coupling agents can also protect fibers and prevent them from breaking during the buffing process. In addition, the hydrophilic end of the coupling agent can be adsorbed onto the surface of the fiber, while the oleophilic end is free in the water. Therefore, when the first pretreatment solution is mixed with the second pretreatment solution, the fiber can have good compatibility with the hydrophobic fluorinated resin, thereby promoting more uniform fiber dispersion and higher density in the film.

[0036] Specifically, when the coupling agent's molecular chain contains an amino group, the fluorine atoms in the fluorinated resin readily form hydrogen bonds with the hydrogen atoms on the surface of the amino group in the coupling agent, enhancing interfacial interaction and thus improving the compatibility between the fiber and the fluorinated resin. When the coupling agent's molecular chain contains a benzene ring, under thermal conditions, the benzene ring readily entangles with the fluorinated resin, further improving the compatibility between the fiber and the fluorinated resin. Therefore, the coupling agent's molecular chain preferably includes at least one of amino groups and a benzene ring.

[0037] Optionally, the coupling agent includes at least one of phenyltrimethoxysilane, phenyltriethoxysilane, aminopropyltrimethoxysilane, and aminopropyltriethoxysilane.

[0038] Optionally, the fiber is selected from at least one of glass fiber, mica fiber, and asbestos fiber, preferably glass fiber.

[0039] In step S2, the fluorinated resin emulsion and flocculant are mixed first, which can cause the fluorinated resin to flocculate into fluorinated resin flocculent particles with larger particle sizes. When mixed with fibers, it can promote the fibers to insert into the spaces between the fluorinated resin flocculent particles or to wrap around the fluorinated resin flocculent particles.

[0040] Meanwhile, during papermaking, the retention rate of fluorinated resin flocculent particles is higher, which helps to improve the utilization rate of fluorinated resin and reduce costs.

[0041] Optionally, in the step of mixing the fluorinated resin emulsion, flocculant, and water, the fluorinated resin emulsion is 10 parts by weight, and the flocculant is 0.01-0.1 parts by weight, so that the particle size of the fluorinated resin flocculants can be controlled by the mass ratio of the fluorinated resin emulsion to the flocculant.

[0042] The fluoropolymer emulsion includes at least one of the following: polytetrafluoroethylene (PTFE) emulsion, tetrafluoroethylene-hexafluoropropylene copolymer emulsion, tetrafluoroethylene-ethylene copolymer emulsion, copolymer emulsion of tetrafluoroethylene and perfluoro(alkyl vinyl) ether, copolymer emulsion of vinylidene fluoride and ethylene-ethylene tetrafluoroethylene, and polyvinylidene fluoride (PVDF) emulsion. Considering that PTFE has a low dielectric constant (Dk = 2.1), excellent dielectric loss, and heat resistance, the fluoropolymer emulsion is further preferably a PTFE emulsion.

[0043] Optionally, the flocculant is a nonionic flocculant, specifically including at least one of polyetherimide (PEI), polyacrylamide (PAM), cationic polyacrylamide (CPAM), and anionic polyacrylamide (APAM).

[0044] Optionally, in the step of mixing the fluorinated resin emulsion, flocculant and water, stirring can be used to promote the flocculation of the fluorinated resin, and the stirring speed is preferably less than or equal to 100 r / min.

[0045] It is understood that the order of steps S1 and S2 in this invention is not limited. S1 and S2 can be performed either first or simultaneously.

[0046] Therefore, after mixing the first pretreatment liquid and the second pretreatment liquid in step S3, the fiber is linked to the groups of the fluorinated resin through the coupling agent, and the buffed portions at both ends of the fiber can be inserted between the fluorinated resin flocculants, or the fiber can wrap around the fluorinated resin flocculants.

[0047] Therefore, in the slurry obtained by mixing the first pretreatment solution and the second pretreatment solution, the fibers and fluorinated resin flocculants can be mixed evenly. For example, if samples of the same volume are taken from different locations in the slurry, and after high-temperature sintering, the remaining fibers are weighed, the range between the samples is ≤5%, and the range = (maximum value - minimum value) / average value.

[0048] Optionally, in the step of mixing the first pretreatment liquid and the second pretreatment liquid, stirring can be performed to promote the uniformity of mixing of fibers and fluorinated resin flocculants in the slurry.

[0049] Optionally, in the slurry obtained by mixing the first pretreatment liquid and the second pretreatment liquid, the mass ratio of fiber to fluorinated resin is 1:10-5:10, thereby controlling the dielectric constant of the film by adjusting the amount of fiber and fluorinated resin.

[0050] After the first pretreatment liquid and the second pretreatment liquid are mixed to obtain a slurry, the film can be obtained by paper forming.

[0051] Specifically, in step S4, the water in the slurry can be removed by vacuum filtration, so that the slurry can be molded into a preform.

[0052] In the step of baking the preform, the baking temperature is preferably 200℃-250℃, and the baking time is preferably 30 minutes-60 minutes, so as to obtain a dense film.

[0053] Therefore, the present invention first performs a buffing treatment on the fiber and controls the degree of dissociation, and performs a flocculation treatment on the fluorinated resin emulsion and controls the particle size of the fluorinated resin flocculants. Then, the slurry of the two mixtures is formed into a film, which can make the fiber and the fluorinated resin tightly bonded, ensuring the high density and low water absorption of the film. At the same time, the fiber is evenly distributed in the film.

[0054] The present invention also provides a film prepared by the above preparation method, which has high density and low water absorption, and the fibers are evenly distributed in the film.

[0055] The present invention also provides a circuit board comprising an insulating layer and a conductive layer disposed on at least one surface of the insulating layer, wherein the insulating layer is formed by pressing one or at least two laminated films.

[0056] In the pressing step, the temperature is 350℃-380℃ and the pressure is 2MPa-4MPa.

[0057] Optionally, the conductive layer is copper foil, and the circuit board is copper-clad laminate.

[0058] The circuit board made using the film of this invention is free from the glass fiber effect, has stable dielectric properties and isotropic, meets the transmission requirements of different signal directions, has better performance, and can maintain the normal operation of electronic components in high temperature and high humidity environments.

[0059] The present invention also provides a printed circuit board, which is mainly made of the circuit substrate through processes such as drilling, hole filling, micro-etching, pre-immersion, activation, acceleration, chemical copper plating and copper thickening.

[0060] The following specific embodiments will further illustrate the film, its preparation method, circuit board, and printed circuit board.

[0061] In the following examples and comparative examples, the degree of dissociation was tested using a dissociation tester, and the test method was GB / T3332-2004. The particle size of the fluorinated resin flocculants in the second pretreatment solution could be obtained by diluting the treatment solution and testing it with a particle size analyzer.

[0062] Example 1

[0063] Ten parts by weight of glass fiber (200 m in length, 10 μm in diameter, aspect ratio 20:1) and 0.08 parts by weight of phenyltrimethoxysilane coupling agent were added to a conical debonding machine, along with 100 parts by weight of water. The speed of the conical debonding machine was controlled at 2500 rpm, and the glass fiber was subjected to debonding treatment for 40 minutes to obtain the first pretreatment solution. The degree of dissociation of the first pretreatment solution was tested to be 80%.

[0064] 50 parts by weight of polytetrafluoroethylene emulsion were mixed with 100 parts by weight of water, and then 0.05 parts by weight of polyetherimide flocculant were added. The mixture was stirred at 80 rpm for 40 minutes to obtain the second pretreated solution. Analysis showed that the second pretreated solution contained particles with a particle size (D...) 50 The fluoropolymer flocculent particles are 60 μm in size.

[0065] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations within the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 2%.

[0066] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0067] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa and 380°C for 6 hours to form a circuit board.

[0068] Example 2

[0069] Ten parts by weight of glass fiber (300 μm in length, 10 μm in diameter, aspect ratio 30:1) and 0.09 parts by weight of phenyltriethoxysilane coupling agent were added to a conical debonding machine, along with 100 parts by weight of water. The speed of the conical debonding machine was controlled at 2600 r / min, and the glass fiber was subjected to buffing treatment in the conical debonding machine for 45 minutes to obtain the first pretreatment solution. The degree of dissociation of the first pretreatment solution was tested to be 83%.

[0070] 60 parts by weight of polytetrafluoroethylene emulsion were mixed with 100 parts by weight of water, and then 0.09 parts by weight of polyetherimide flocculant were added. The mixture was stirred at 70 r / min for 40 minutes to obtain the second pretreated solution. Analysis showed that the second pretreated solution contained particles with a particle size (D...) 50 The fluoropolymer flocculent particles are 58 μm in size.

[0071] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations in the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 1.9%.

[0072] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0073] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa pressure and 375℃ for 6 hours to form a circuit board.

[0074] Example 3

[0075] Ten parts by weight of glass fiber (300 μm in length, 20 μm in diameter, aspect ratio 15:1) and 0.1 parts by weight of aminopropyltriethoxysilane coupling agent were added to a conical debonding machine, along with 100 parts by weight of water. The speed of the conical debonding machine was controlled at 2800 r / min, and the glass fiber was subjected to buffing treatment in the conical debonding machine for 35 minutes to obtain the first pretreatment solution. The degree of dissociation of the first pretreatment solution was tested to be 85%.

[0076] 60 parts by weight of polytetrafluoroethylene emulsion were mixed with 100 parts by weight of water, and then 0.1 parts by weight of polyacrylamide (PAM) flocculant were added. The mixture was stirred at 60 r / min for 40 minutes to obtain the second pretreated solution. Analysis showed that the second pretreated solution contained particles with a particle size (D...) 50 The fluoropolymer flocculent particles are 75 μm in size.

[0077] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations in the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 1.8%.

[0078] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0079] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa and 380°C for 6 hours to form a circuit board.

[0080] Example 4

[0081] Twenty parts by weight of glass fiber (400 μm in length, 20 μm in diameter, aspect ratio 20:1) and 0.15 parts by weight of aminopropyltriethoxysilane coupling agent were added to a conical debonding machine, along with 150 parts by weight of water. The speed of the conical debonding machine was controlled at 3000 r / min, and the glass fiber was subjected to buffing treatment in the conical debonding machine for 40 minutes to obtain the first pretreatment solution. The degree of dissociation of the first pretreatment solution was tested to be 78%.

[0082] 80 parts by weight of polytetrafluoroethylene emulsion were mixed with 120 parts by weight of water, and then 0.2 parts by weight of polyacrylamide (PAM) flocculant were added. The mixture was stirred at 76 r / min for 38 minutes to obtain the second pretreated solution. Analysis showed that the second pretreated solution contained particles with a particle size (D...) 50 The fluoropolymer flocculent particles are 80 μm in size.

[0083] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations in the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 1.7%.

[0084] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0085] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa pressure and 375℃ for 6 hours to form a circuit board.

[0086] Example 5

[0087] Twenty parts by weight of glass fiber (250 μm in length, 5 μm in diameter, aspect ratio 50:1) and 0.15 parts by weight of aminopropyltrimethoxysilane coupling agent were added to a conical debonding machine, along with 180 parts by weight of water. The speed of the conical debonding machine was controlled at 2900 r / min, and the glass fiber was subjected to buffing treatment in the conical debonding machine for 40 minutes to obtain the first pretreatment solution. The degree of dissociation of the first pretreatment solution was tested to be 79%.

[0088] 50 parts by weight of polytetrafluoroethylene emulsion were mixed with 100 parts by weight of water, and then 0.15 parts by weight of polyacrylamide (PAM) flocculant were added. The mixture was stirred at 65 r / min for 40 minutes to obtain the second pretreated solution. Analysis showed that the second pretreated solution contained particles with a particle size (D...) 50 The fluorinated resin flocculent particles are 69 μm in size.

[0089] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations in the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 1.5%.

[0090] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0091] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa and 370°C for 6 hours to form a circuit board.

[0092] Example 6

[0093] Ten parts by weight of glass fiber (180 μm in length, 3 μm in diameter, aspect ratio 60:1) and 0.12 parts by weight of phenyltrimethoxysilane coupling agent were added to a conical debonding machine, along with 150 parts by weight of water. The speed of the conical debonding machine was controlled at 3000 r / min, and the glass fiber was subjected to buffing treatment in the conical debonding machine for 42 minutes to obtain the first pretreatment solution. The degree of dissociation of the first pretreatment solution was tested to be 88%.

[0094] 70 parts by weight of polytetrafluoroethylene emulsion were mixed with 130 parts by weight of water, and then 0.18 parts by weight of polyacrylamide (PAM) flocculant were added. The mixture was stirred at 68 r / min for 40 minutes to obtain the second pretreated solution. Analysis showed that the second pretreated solution contained particles with a particle size (D...) 50 The fluoropolymer flocculent particles are 45 μm in size.

[0095] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations in the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 1.6%.

[0096] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0097] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa pressure and 375℃ for 6 hours to form a circuit board.

[0098] Example 7

[0099] The only difference between Example 7 and Example 1 is that the glass fiber has a length of 80 μm, a diameter of 40 μm, and an aspect ratio of 2:1, which makes the degree of dissociation of the first pretreatment solution 77%.

[0100] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations in the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 2.3%.

[0101] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0102] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa and 380°C for 6 hours to form a circuit board.

[0103] Example 8

[0104] The only difference between Example 8 and Example 1 is that the rotation speed of the conical decontamination machine is 800 r / min, which makes the degree of dissociation of the first pretreatment liquid 79%.

[0105] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations in the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 2.5%.

[0106] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0107] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa and 380°C for 6 hours to form a circuit board.

[0108] Example 9

[0109] The only difference between Example 9 and Example 1 is that the coupling agent is hexamethyldisilazane, with a weight of 0.01, which makes the degree of dissociation of the first pretreatment solution 81%.

[0110] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations in the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 2.2%.

[0111] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0112] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa and 380°C for 6 hours to form a circuit board.

[0113] Comparative Example 1

[0114] The only difference between Comparative Example 1 and Example 1 is that the glass fiber is not subjected to buffing treatment, and the glass fiber and coupling agent are directly mixed with the second pretreatment solution.

[0115] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations in the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 10.2%.

[0116] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0117] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa pressure and 375℃ for 6 hours to form a circuit board.

[0118] Comparative Example 2

[0119] The only difference between Comparative Example 2 and Example 1 is that the broom treatment time is 10 minutes, so that the degree of dissociation of the first pretreatment liquid is 70%.

[0120] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations in the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 9.9%.

[0121] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0122] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa and 370°C for 6 hours to form a circuit board.

[0123] Comparative Example 3

[0124] The only difference between Comparative Example 3 and Example 1 is that the broom treatment time is 80 minutes, resulting in a degree of dissociation of 92% for the first pretreatment liquid.

[0125] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations in the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 9.8%.

[0126] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0127] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa and 370°C for 6 hours to form a circuit board.

[0128] Comparative Example 4

[0129] The only difference between Comparative Example 4 and Example 1 is that the polytetrafluoroethylene emulsion is not subjected to flocculation treatment, and the polytetrafluoroethylene emulsion and flocculant are directly added to the first pretreatment solution.

[0130] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations in the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 10.2%.

[0131] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0132] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa and 380°C for 6 hours to form a circuit board.

[0133] Comparative Example 5

[0134] The only difference between Comparative Example 5 and Example 1 is the addition of 0.001 parts by weight of polyetherimide flocculant, which reduces the particle size (D) of the fluorinated resin flocculants in the second pretreatment solution. 50 The value is 25μm.

[0135] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations in the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 9.8%.

[0136] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0137] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa and 380°C for 6 hours to form a circuit board.

[0138] Comparative Example 6

[0139] The only difference between Comparative Example 6 and Example 1 is the addition of 0.5 parts by weight of polyetherimide flocculant, which reduces the particle size (D) of the fluorinated resin flocculants in the second pretreatment solution. 50 The value is 110μm.

[0140] The first and second pretreatment solutions were mixed and stirred to obtain a slurry. 10 mL samples were taken from six different locations in the slurry. After high-temperature sintering, the remaining glass fibers were weighed, and the range between the samples was 8.7%.

[0141] The slurry is poured into the mixing tank of the film forming machine (the mixing tank has a metal filter screen at the bottom), and then the water in the slurry is filtered out by vacuum to form a preform. The preform is then placed in a vacuum oven at 200°C and baked for 30 minutes to obtain the film.

[0142] Four films are stacked together, with a copper foil on the top and bottom, and then pressed together at 3MPa pressure and 375℃ for 6 hours to form a circuit board.

[0143] The performance of the circuit boards of Examples 1-9 and Comparative Examples 1-6 was tested. The specific test contents and standards are shown below, and the test results are shown in Table 1.

[0144] Dielectric property testing standard for substrates: IPC-TM-6502.5.5.5;

[0145] Standard for water absorption rate testing of boards: IPC-TM-6502.6.2.1;

[0146] The isotropic test standard for the dielectric properties of the substrate is IPC-TM-6502.5.5.5, which tests the dielectric constants in the X, Y, and Z directions and compares and evaluates whether it is isotropic.

[0147] Table 1

[0148]

[0149]

[0150] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0151] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a film, characterized in that, Includes the following steps: The fiber, coupling agent and water are mixed and then subjected to a buffing treatment to obtain a first pretreatment solution. The degree of dissociation of the first pretreatment solution is 75%-90%, and the buffing treatment time is 30 minutes-60 minutes. A fluorinated resin emulsion, a flocculant, and water are mixed to obtain a second pretreatment solution. The second pretreatment solution contains fluorinated resin flocculent particles with a particle size of 30μm-100μm. The flocculant is 0.01-0.1 parts by weight, with 10 parts by weight of the fluorinated resin emulsion. The first pretreatment liquid and the second pretreatment liquid are mixed to obtain a slurry; as well as The slurry is dehydrated, shaped, and baked to obtain a film.

2. The method for preparing film according to claim 1, characterized in that, In the step of fusing the fiber, coupling agent and water, the rotation speed is 1000 r / min-3000 r / min.

3. The method for preparing film according to claim 1, characterized in that, In the step of mixing the fiber, coupling agent and water and then performing a buffing treatment, the coupling agent is 0.05-0.2 parts by weight, with 10 parts by weight of the fiber.

4. The method for preparing film according to claim 1 or 3, characterized in that, The fiber has a length of 100μm-400μm, a diameter of 1μm-20μm, and an aspect ratio of 5:1-400:

1.

5. The method for preparing film according to claim 1 or 3, characterized in that, The coupling agent comprises at least one of an amino group and a benzene ring in its molecular chain.

6. The method for preparing film according to claim 1, characterized in that, The fluorinated resin emulsion is selected from at least one of polytetrafluoroethylene emulsion, tetrafluoroethylene-hexafluoropropylene copolymer emulsion, tetrafluoroethylene-ethylene copolymer emulsion, and polyvinylidene fluoride emulsion.

7. The method for preparing film according to claim 1, characterized in that, The mass ratio of fiber to fluorinated resin in the slurry is 1:10-5:

10.

8. A film, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. A circuit board, characterized in that, It includes an insulating layer and a conductive layer disposed on at least one surface of the insulating layer, wherein the insulating layer is formed by pressing one or at least two laminated films as described in claim 8.

10. A printed circuit board made from the circuit board of claim 9.

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