Fluorine-containing resin-based copper clad plate and application thereof

Abstract

The application provides a fluorine-containing resin-based copper-clad plate and application thereof. The fluorine-containing resin-based copper-clad plate comprises a dielectric layer and copper foils arranged on both sides of the dielectric layer; the dielectric layer comprises an intermediate fluorine-containing resin layer and fluorine-containing resin films A arranged on both sides of the intermediate fluorine-containing resin layer; the intermediate fluorine-containing resin layer comprises at least one fluorine-containing resin film B; the dimensional stability of the fluorine-containing resin film A is negative, and the dimensional stability of the fluorine-containing resin film B is positive. Through the design of the fluorine-containing resin film A with negative dimensional stability and the fluorine-containing resin film B with positive dimensional stability and the formation of the dielectric layer in a specific order, the fluorine-containing resin-based copper-clad plate has excellent and adjustable dimensional expansion and contraction, excellent dimensional stability, excellent peeling strength and electrical strength, and fully meets the performance requirements of high-density and high-precision processing of PCBs.

Description

Technical Field

[0001] This invention belongs to the field of communication materials technology, specifically relating to a fluorinated resin-based copper clad laminate and its applications. Background Technology

[0002] In recent years, with the continuous development of 5G communication technology, satellite communication, radar systems, automotive collision avoidance systems, electronic navigation, and high-integration technology, electronic products are constantly evolving towards higher frequency and higher speed signal transmission. The increasing demands for high frequency and high speed on circuit boards are mainly reflected in end-customers' strong preference for PTFE (polytetrafluoroethylene) sheets. On the other hand, advancements in chip mounting technology have led to an increase in the number of pins and mounting density of components; simultaneously, printed circuit board (PCB) products are developing towards lighter, thinner, shorter, and smaller designs, with increasingly smaller absolute deviation ranges, meaning higher precision requirements. This necessitates that copper-clad laminates have small and controllable dimensional expansion and contraction.

[0003] PTFE copper-clad laminates without supporting materials are mainly prepared by laminating copper foil onto the surface of a PTFE film. The PTFE film is mainly produced by blow molding, extrusion, cutting, or casting. During production, the PTFE film will generate internal stress due to the force applied. During the PCB processing, after etching to remove copper or after heat treatment, some of the internal stress is released during the processing, causing PTFE to shrink in size. This shrinkage will seriously affect the processing accuracy.

[0004] To address the dimensional shrinkage issue of PTFE copper-clad laminates (CCLs), researchers have implemented physical or chemical modifications to the PTFE layer. For example, CN114369239A discloses a low-thermal-expansion fluorinated resin-based high-frequency CCL, which incorporates a linear polyarylamide with a benzo[4] four-membered ring structure into a fluorinated resin dielectric sheet. The linear polyarylamide undergoes in-situ reaction during high-temperature baking under a protective atmosphere, forming a dibenzo[8] eight-membered ring structure with thermal shrinkage and expansion characteristics. Simultaneously, a cross-linked network is formed within the fluorinated resin matrix, reducing the thermal expansion coefficient of the high-frequency CCL and improving its dimensional stability. However, this approach suffers from high preparation costs for the linear polyarylamide with the benzo[4] four-membered ring structure, making the raw materials difficult to obtain. Furthermore, ensuring the linear polyarylamide fully reacts significantly prolongs the lamination time for CCL preparation, increasing the difficulty of CCL fabrication, reducing production efficiency, and hindering industrial applications. CN115503316A discloses a flexible copper-clad laminate, which is formed by laminating a first copper foil, a dielectric material, and a second copper foil. The dielectric material includes a first adhesive layer, a first core layer, and an optional second adhesive layer. The thickness of the first core layer is 25-500 μm, and it is composed of a fluorinated resin modified with inorganic fillers. The thicknesses of the first and second adhesive layers are 5-35 μm, respectively, and they are mainly composed of fluorinated molten resin. Although this flexible copper-clad laminate has good peel strength and low water absorption, its coefficient of thermal expansion is still high, and it has obvious dimensional expansion and contraction problems, resulting in insufficient dimensional stability and difficulty in meeting the performance requirements of copper-clad laminates under high-precision and high-density processing.

[0005] Therefore, developing copper-clad laminates with good dimensional stability and high peel strength to meet the requirements of high-density and high-precision PCB processing for substrate dimensional expansion and contraction performance is an urgent problem to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a fluorinated resin-based copper clad laminate and its applications. Through the design of a fluorinated resin film A with negative dimensional stability and a fluorinated resin film B with positive dimensional stability, and the dielectric layer formed in a specific order, the fluorinated resin-based copper clad laminate exhibits excellent and adjustable dimensional expansion and contraction properties, good dimensional stability, high peel strength and electrical strength, fully meeting the requirements of high-density and high-precision PCB processing for the dimensional expansion and contraction performance of copper clad laminates.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a fluorinated resin-based copper clad laminate, the fluorinated resin-based copper clad laminate comprising a dielectric layer and copper foil disposed on both sides of the dielectric layer; the dielectric layer comprising an intermediate fluorinated resin layer and a fluorinated resin film A disposed on both sides of the intermediate fluorinated resin layer; the intermediate fluorinated resin layer comprising at least one fluorinated resin film B; the dimensional stability of the fluorinated resin film A is negative, and the dimensional stability of the fluorinated resin film B is positive.

[0009] Due to internal stress and other factors, fluoropolymer-containing films cause copper-clad laminates containing them to exhibit expansion and contraction characteristics different from thermal expansion and contraction, resulting in shrinkage after etching or heat treatment. To address this, the fluoropolymer-based copper-clad laminate provided by this invention has fluoropolymer-containing films A on both sides of the dielectric layer. Specifically, the fluoropolymer-containing film A in contact with the copper foil has negative dimensional stability, while the fluoropolymer-containing film B in the middle fluoropolymer layer has positive dimensional stability. Through the design and mutual compounding of these two types of fluoropolymer-containing films, the fluoropolymer-based copper-clad laminate possesses excellent and adjustable dimensional expansion and contraction properties, excellent dimensional stability, and a high-strength, stable bond between the dielectric layer (fluoropolymer-containing film A) and the copper foil. This endows the fluoropolymer-based copper-clad laminate with high peel strength and excellent electrical strength, thereby fully meeting the performance requirements of high-density, high-precision PCB manufacturing.

[0010] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0011] In this invention, the dimensional stability of the fluorinated resin film A and the fluorinated resin film B can be obtained by laminating the fluorinated resin film with copper on both sides to form a copper-clad laminate, and then testing it according to the IPC-TM-650-2.2.4 method.

[0012] Preferably, the fluorinated resin membrane A comprises a combination of a first fluorinated resin and optionally a first filler. The volume percentage of the first filler in the fluorinated resin membrane A is 0-60%, for example, it can be 0, 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 52%, 55%, or 58%, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0013] And / or, the fluorinated resin membrane B comprises a combination of a second fluorinated resin and a second filler, wherein the volume percentage of the second filler in the fluorinated resin membrane B is 62-80%, for example, it can be 63%, 65%, 68%, 70%, 72%, 75% or 78%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0014] This invention, through research, has discovered that adding fillers to fluoropolymer films helps release internal stress and improves dimensional expansion and contraction performance and dimensional stability. When the filler volume content of the fluoropolymer film is around 62%, the dimensional stability of the copper-clad laminate (CCL) exhibits a sudden change. At this filler volume content of 62%, after partial release of internal stress, the remaining internal stress-induced shrinkage of the board is offset by the thermal expansion of the substrate itself, resulting in dimensional stability (dimensional expansion and contraction after heat treatment) approaching 0 ppm. When the filler volume content is >62%, the dimensional expansion of the CCL exhibits an expanding behavior with increasing filler content, and the dimensional stability is positive, increasing with increasing filler content, but at a decreasing rate. When the filler volume content exceeds 80%, the increase in dimensional stability is minimal, internal defects in the CCL increase, and the adhesion of the fluoropolymer film deteriorates rapidly, leading to decreased board reliability. When the filler volume content is <60%, the dimensional expansion and contraction of the CCL exhibits a contracting behavior with decreasing filler content, and the absolute value increases. Based on this, in this invention, the volume percentage of filler in the fluorinated resin film A, which has negative dimensional stability, is 0-60%, while the volume percentage of filler in the fluorinated resin film B, which has positive dimensional stability, is 62-80%. The combination of the two gives the fluorinated resin-based copper clad laminate excellent and adjustable dimensional expansion and contraction properties, exhibiting excellent dimensional stability. At the same time, the fluorinated resin film A with a lower filler content, when in contact with the copper foil, imparts excellent peel strength to the fluorinated resin-based copper clad laminate.

[0015] The volume percentage of the first filler in the fluorinated resin film A of the present invention is ≤60%, which gives it good adhesion and peel strength. If the volume percentage of the filler is >60%, the adhesion will decrease and flying wire phenomenon (line peeling phenomenon) is likely to occur when fine lines are prepared by fluorinated resin-based copper clad laminate.

[0016] The volume percentage of the second filler in the fluorinated resin film B described in this invention is 62-80%, which gives it positive dimensional stability. If the volume percentage of the filler in the fluorinated resin film B is <62%, the dimensional stability is negative, causing a decrease in the dimensional stability of the fluorinated resin-based copper clad laminate. If the volume percentage of the filler in the fluorinated resin film B is >80%, the increase in dimensional stability becomes very weak, but the internal defects of the board increase sharply, resulting in a deterioration in the reliability of the fluorinated resin-based copper clad laminate.

[0017] Preferably, the first filler includes silica and optionally other filler A.

[0018] Preferably, the volume percentage of silica in the first filler is 80-100%, for example, it can be 82%, 85%, 88%, 90%, 92%, 95%, 98%, or 99%, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range. This invention has found that when the volume percentage of silica in the filler is ≥80%, the dimensional stability of copper-clad laminates with a filler volume content of approximately 62% containing fluorinated resin film will exhibit a sudden change.

[0019] In this invention, the other filler A refers to fillers other than silica.

[0020] Preferably, the volume percentage of other filler A in the first filler is 0-20%, for example, it can be 0, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0021] Preferably, the other filler A includes any one or a combination of at least two of titanium dioxide, barium titanate, strontium titanate, chopped glass fiber, alumina, boron nitride, silicon nitride, hollow glass microspheres, and hollow silica, with titanium dioxide being more preferred.

[0022] Preferably, the average particle size (D) of the first filler is 50 The value can be 0.01-20μm, for example, 0.05μm, 0.1μm, 0.5μm, 1μm, 5μm, 10μm, 12μm, 15μm, 18μm or 20μm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range, but 0.01-10μm is further preferred.

[0023] For example, the particle size of the filler was obtained using an MS3000 Malvern laser particle size analyzer.

[0024] Preferably, the first fluororesin comprises any one or a combination of at least two of the following: polytetrafluoroethylene, tetrafluoroethylene-fluoropropyl perfluorovinyl ether copolymer, polytetrafluoroethylene propylene, tetrafluoroethylene-perfluoroalkoxy perfluorovinyl ether copolymer, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, and ethylene-chlorotrifluoroethylene copolymer, and more preferably, tetrafluoroethylene-fluoropropyl perfluorovinyl ether copolymer.

[0025] As a preferred embodiment of the present invention, the first fluororesin comprises tetrafluoroethylene-fluoropropyl perfluorovinyl ether copolymer (PFA), which gives the fluororesin film A better adhesion and peel strength.

[0026] Preferably, the second filler comprises silica and optionally other filler B.

[0027] In this invention, the other filler B refers to fillers other than silica.

[0028] Preferably, the volume percentage of silica in the second filler is 80-100%, for example, it can be 82%, 85%, 88%, 90%, 92%, 95%, 98% or 99%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0029] Preferably, the volume percentage of other filler B in the second filler is 0-20%, for example, it can be 0, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0030] Preferably, the other filler B includes any one or a combination of at least two of the following: titanium dioxide, barium titanate, strontium titanate, chopped glass fiber, alumina, boron nitride, silicon nitride, hollow glass microspheres, and hollow silica, with titanium dioxide being more preferred.

[0031] Preferably, the average particle size (D) of the second filler 50 The value can be 0.01-30μm, for example, 0.05μm, 0.1μm, 0.5μm, 1μm, 5μm, 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 25μm or 28μm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range. More preferably, it is 5-20μm, and even more preferably, it is 5-15μm.

[0032] Preferably, the second fluororesin comprises any one or a combination of at least two of the following: polytetrafluoroethylene, tetrafluoroethylene-fluoropropyl perfluorovinyl ether copolymer, perfluoroethylene propylene, tetrafluoroethylene-perfluoroalkoxy perfluorovinyl ether copolymer, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, and ethylene-chlorotrifluoroethylene copolymer.

[0033] Preferably, the thickness of the fluorinated resin film A is 10-80 μm, for example, it can be 12 μm, 13 μm, 15 μm, 18 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm or 75 μm, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, and it is further preferred to be 12.5-64 μm.

[0034] Preferably, the dimensional stability of the fluorinated resin membrane A is from -36000ppm to -2500ppm, for example, it can be -2500ppm, -3000ppm, -5000ppm, -8000ppm, -10000ppm, -12000ppm, -15000ppm, -18000ppm, -20000ppm, -22000ppm, -25000ppm, -28000ppm, -30000ppm, -32000ppm, or -35000ppm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0035] Preferably, the thickness of the fluorinated resin film B is 10-180 μm, for example, it can be 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm or 170 μm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but preferably 38-127 μm.

[0036] Preferably, the dimensional stability of the fluorinated resin membrane B is from 0 ppm to 2500 ppm, for example, it can be 50 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 800 ppm, 1000 ppm, 1200 ppm, 1500 ppm, 1800 ppm, 2000 ppm, 2200 ppm or 2400 ppm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0037] Preferably, the intermediate fluororesin layer is composed of a fluororesin film B.

[0038] Preferably, the number of fluorinated resin films B in the intermediate fluorinated resin layer is 2-24, for example, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 18, 20, 22 or 24.

[0039] Preferably, the thickness of the dielectric layer is 100-1270 μm, for example, it can be 120 μm, 150 μm, 152 μm, 180 μm, 200 μm, 220 μm, 250 μm, 254 μm, 280 μm, 300 μm, 320 μm, 350 μm, 380 μm, 400 μm, 420 μm, 450 μm, 480 μm, 500 μm, 508 μm, 520 μm, 550 μm, 580 μm, 600 μm, 620 μm, 650 μm, 680 μm, 700 μm, 720 μm, 750 μm or 780 μm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but preferably 100-300 μm.

[0040] In a second aspect, the present invention provides a method for preparing a fluorinated resin-based copper-clad laminate as described in the first aspect, the method comprising:

[0041] Fluorine-containing resin film A, fluorine-containing resin film B, and copper foil are stacked in sequence to obtain a laminated structure with copper foil on both sides and the fluorine-containing resin film A bonded to the copper foil; the laminated structure is then laminated to obtain the fluorine-containing resin-based copper clad laminate.

[0042] In this invention, the fluorinated resin film A and the fluorinated resin film B can be prepared using film-forming methods known in the art, including but not limited to: blow molding, extrusion, cutting, and casting. The fluorinated resin film A can also be a commercially available product.

[0043] The following example illustrates the casting method.

[0044] Preferably, the method for preparing the fluorinated resin film A includes: coating a composition comprising a first fluorinated resin and optionally a first filler onto a release material, followed by drying and / or sintering to obtain the fluorinated resin film A.

[0045] Preferably, the method for preparing the fluorinated resin film B includes: coating a composition containing a second fluorinated resin and a second filler onto a release material, followed by drying and / or sintering to obtain the fluorinated resin film B.

[0046] Preferably, the drying temperature is 100-280℃, for example, it can be 110℃, 130℃, 150℃, 170℃, 190℃, 200℃, 210℃, 230℃, 250℃, 260℃ or 270℃, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0047] Preferably, the drying time is 10-120 min, for example, it can be 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min or 110 min, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0048] Preferably, the sintering temperature is 200-400℃, for example, it can be 210℃, 230℃, 250℃, 270℃, 290℃, 300℃, 310℃, 330℃, 350℃, 370℃ or 390℃, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0049] Preferably, the sintering time is 0.1-6h, for example, it can be 0.2h, 0.25h, 0.5h, 0.75h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h or 5.5h, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0050] Preferably, the sintering is carried out in an inert atmosphere.

[0051] Preferably, the inert atmosphere includes a nitrogen atmosphere and / or an argon atmosphere.

[0052] Preferably, the lamination temperature is 200-400℃, for example, it can be 210℃, 230℃, 250℃, 270℃, 290℃, 300℃, 310℃, 330℃, 350℃, 370℃ or 390℃, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0053] Preferably, the lamination pressure is 3-15 MPa, for example, it can be 3 MPa, 5 MPa, 8 MPa, 10 MPa, 12 MPa or 14 MPa, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0054] Preferably, the lamination time is 1-12 hours, for example, it can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours or 11 hours, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the range.

[0055] Thirdly, the present invention provides a printed circuit board, the printed circuit board comprising a fluorinated resin-based copper-clad laminate as described in the first aspect.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] The fluorinated resin-based copper clad laminate provided by this invention, through the design of a fluorinated resin film A with negative dimensional stability and a fluorinated resin film B with positive dimensional stability, and their formation of a dielectric layer in a specific order, gives the fluorinated resin-based copper clad laminate excellent and adjustable dimensional expansion and contraction properties. The absolute value of dimensional stability is 0-1000ppm, which is excellent. Furthermore, a high-strength and stable bond is formed between the fluorinated resin film A and the copper foil, giving the fluorinated resin-based copper clad laminate excellent peel strength. In fine-line PCB processing, there is no wire peeling (no flying wires), and the electrical strength is excellent, which can be 50-58kV / mm, fully meeting the performance requirements of high-density and high-precision PCB processing. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the structure of a fluorinated resin-based copper-clad laminate provided in a specific embodiment;

[0059] Among them, 10 is copper foil, 20 is fluorinated resin film A, and 30 is intermediate fluorinated resin layer. Detailed Implementation

[0060] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0061] In this invention, features specified as "first" and "second" may explicitly or implicitly include one or more of these features, used to distinguish and describe features, without any order or emphasis. In the description of this invention, unless otherwise stated, "multiple" means two or more.

[0062] In one specific embodiment, the structural schematic diagram of the fluorinated resin-based copper-clad laminate provided by the present invention is shown below. Figure 1As shown, the device includes a dielectric layer and copper foils 10 disposed on both sides of the dielectric layer; the dielectric layer includes an intermediate fluoropolymer layer 30 and fluoropolymer films A 20 located on both sides of the intermediate fluoropolymer layer 30; thereby, the fluoropolymer films A 20 are in contact with the copper foils 10; the intermediate fluoropolymer layer 30 includes at least one fluoropolymer film B. The dimensional stability of the fluoropolymer film A is negative, and the dimensional stability of the fluoropolymer film B is positive.

[0063] In the following specific embodiments of the present invention, the material information involved is as follows:

[0064] (1) Fluoropolymer emulsion

[0065] Polytetrafluoroethylene (PTFE) emulsion, D210C, purchased from Daikin Japan;

[0066] Tetrafluoroethylene-fluoropropyl perfluorovinyl ether copolymer (PFA) emulsion, PFA-E50, purchased from Chenguang.

[0067] (2) Packing

[0068] Flame-processed spherical silica, NQ2030HK, with an average particle size of about 4μm, was purchased from Lianrui.

[0069] Chemically produced spherical silica, SE0072, with an average particle size of approximately 4 μm, was purchased from Jinyi.

[0070] Angular silica, DF2110, with an average particle size of about 11μm, was purchased from Lianrui.

[0071] Titanium dioxide, TC300, with an average particle size of about 5μm, was purchased from Jinyi.

[0072] Boron nitride, BN200, with an average particle size of about 10 μm, was purchased from Jinyi.

[0073] In the following specific embodiments of the present invention, fluorinated resin membrane A with negative dimensional stability and fluorinated resin membrane B with positive dimensional stability are prepared by the method of the preparation example.

[0074] Preparation Example

[0075] Preparation of fluoropolymer film: According to the volume ratio of fluoropolymer and filler shown in Tables 1 and 2, PTFE emulsion and / or PFA emulsion are mixed with filler. Thickener (polyoxyethylene distyryl phenyl ether, EMULGEN A-60 from Kao Corporation) is added under stirring until the viscosity of the adhesive is 250-300 mPa·s. The mixture is stirred at high speed for 2 hours to obtain an adhesive solution. According to the film thickness requirements shown in Tables 1 and 2, the above adhesive solution is coated onto the surface of release material (polyimide film, PI film) using a coating machine to obtain an adhesive-coated PI film. The adhesive-coated PI film is placed in a vacuum oven at 100°C and baked for 1 hour to remove moisture. It is then baked at 260°C for 1 hour to remove the additive (thickener). Finally, it is sintered at 350°C for 10 minutes. After cooling, the resin layer is peeled off from the PI film to obtain a fluoropolymer film of a specific thickness with uniform thickness and good appearance.

[0076] Examples 1-9, Comparative Examples 1-5

[0077] A fluorinated resin-based copper clad laminate includes a dielectric layer and copper foils (1 oz) disposed on both sides of the dielectric layer. The dielectric layer is composed of a fluorinated resin film, and the stacked structure of the dielectric layer is shown in Tables 1 and 2.

[0078] The preparation method of the fluorinated resin-based copper clad laminate includes: stacking fluorinated resin films according to the stacking structure in Tables 1 and 2, with a size of 320mm×380mm, covering the upper and lower surfaces of the stacked resin film with 1oz thick copper foil, laminating, applying a pressure of 7MPa, a maximum temperature of 390℃, and a holding time of 60min to obtain the fluorinated resin-based copper clad laminate.

[0079] The following performance tests were performed on the aforementioned fluorinated resin-based copper clad laminate:

[0080] (1) Dimensional stability: Tested using IPC-TM-650 2.2.4 method;

[0081] (2) Flying line test: The copper-clad board sample to be tested is made into a pattern with a line width of 3.5mil and a line spacing of 3.5mil. The pattern is gently moved with tweezers to observe whether there is any line peeling. If there is line peeling, it means that the peel strength of the copper foil of the substrate is poor and cannot meet the requirements of fine line PCB processing.

[0082] (3) Electrical strength: Tested using IPC-TM-650 2.5.6.2A method.

[0083] The test results are shown in Tables 1 and 2:

[0084] In Tables 1 and 2, "volume percentage (%)" indicates the volume percentage content of the fluoropolymer membrane. Taking Example 1 as an example, the PTFE volume percentage (%) of fluoropolymer membrane A is 100.0, and the filler volume percentage (%) is 0, which means it is a pure PTFE membrane without filler. The PTFE volume percentage (%) of fluoropolymer membrane B is 16.0, the PFA volume percentage (%) is 4.0, and the filler volume percentage (%) is 80.0, with all fillers being silica.

[0085] Table 1

[0086]

[0087]

[0088] Table 2

[0089]

[0090]

[0091]

[0092] As printed circuit board products develop towards being lighter, thinner, shorter, and smaller, the requirements for the dimensional stability of fluoropolymer-based copper clad laminates in PCB processing are becoming increasingly stringent. Currently, the absolute value of dimensional stability is generally required to be <2000ppm, and further requirements are set at <1500ppm.

[0093] As can be seen from Tables 1 and 2, Examples 1-9 of the present invention use a combination of fluorinated resin film A (filler volume content 0-60%) with negative dimensional stability and fluorinated resin film B (filler volume content 62-80%) with positive dimensional stability to prepare copper-clad laminates, and fluorinated resin film A is brought into contact with copper foil. This allows the fluorinated resin-based copper-clad laminate to exhibit excellent dimensional stability, electrical strength, and peel strength. The absolute value of its dimensional stability is 0-975 ppm, and its electrical strength is 50-58 kV / mm. No wire peeling (no flying wires) occurs during fine-line PCB processing. Furthermore, Examples 1-9 also show that the dimensional stability of the copper-clad laminate can be adjusted by changing the filler ratio in fluorinated resin film A and fluorinated resin film B, or by adjusting the proportion of fluorinated resin film A and fluorinated resin film B in the copper-clad laminate.

[0094] As can be seen from Comparative Examples 1-5, when the filler volume content of both fluorinated resin film A and fluorinated resin film B is >60%, and the dimensional stability of all resin films in the dielectric layer is positive (Comparative Example 1), the copper clad laminate exhibits flying wire phenomenon, failing to meet PCB processing requirements. When fluorinated resin film B is located on the surface of the dielectric layer in contact with the copper foil, and fluorinated resin film A is located in the middle of the dielectric layer (Comparative Example 5), the adhesion between the copper foil and the dielectric layer is insufficient, leading to wire peeling during copper clad laminate fabrication, resulting in flying wire phenomenon, failing to meet PCB processing requirements. When the filler content of fluorinated resin film B is >80% (Comparative Example 2), the internal defects of the copper clad laminate increase significantly, and the electrical strength performance decreases significantly. When the filler content of both fluorinated resin film A and fluorinated resin film B is <60%, and the dimensional stability of all resin films in the dielectric layer is negative (Comparative Examples 3 and 4), the absolute value of the dimensional stability of the copper clad laminate increases significantly, and the dimensional stability deteriorates significantly.

[0095] The applicant declares that this invention illustrates the fluorinated resin-based copper clad laminate and its applications through the above embodiments, but this invention is not limited to the above process steps, that is, it does not mean that this invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used in this invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. A fluorinated resin-based copper-clad laminate, characterized in that, The fluorinated resin-based copper clad laminate includes a dielectric layer and copper foil disposed on both sides of the dielectric layer; The dielectric layer includes an intermediate fluoropolymer layer and a fluoropolymer film A disposed on both sides of the intermediate fluoropolymer layer; the intermediate fluoropolymer layer is composed of a fluoropolymer film B. The copper foil is in contact with the fluorinated resin film A, and the fluorinated resin film A is in contact with the fluorinated resin film B; The dimensional stability of the fluorinated resin membrane A is negative, and the dimensional stability of the fluorinated resin membrane B is positive; the dimensional stability of the fluorinated resin membrane A and the fluorinated resin membrane B are tested according to the IPC-TM-650-2.2.4 method. The fluorinated resin membrane A comprises a combination of a first fluorinated resin and a first filler, wherein the volume percentage of the first filler in the fluorinated resin membrane A is 0-60%, and not 0. The fluorinated resin membrane B comprises a combination of a second fluorinated resin and a second filler, wherein the volume percentage of the second filler in the fluorinated resin membrane B is 62-80%.

2. The fluorinated resin-based copper-clad laminate according to claim 1, characterized in that, The first packing material includes silica and optionally other packing material A.

3. The fluorinated resin-based copper-clad laminate according to claim 2, characterized in that, The volume percentage of silica in the first filler is 80-100%.

4. The fluorinated resin-based copper-clad laminate according to claim 2, characterized in that, The other filler A includes any one or a combination of at least two of the following: titanium dioxide, barium titanate, strontium titanate, chopped glass fiber, alumina, boron nitride, silicon nitride, hollow glass microspheres, and hollow silica.

5. The fluorinated resin-based copper-clad laminate according to claim 4, characterized in that, The other filler A is titanium dioxide.

6. The fluorinated resin-based copper-clad laminate according to claim 1, characterized in that, The first fluororesin includes any one or a combination of at least two of the following: polytetrafluoroethylene, tetrafluoroethylene-fluoropropyl perfluorovinyl ether copolymer, perfluoroethylene propylene, tetrafluoroethylene-perfluoroalkoxy perfluorovinyl ether copolymer, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, and ethylene-chlorotrifluoroethylene copolymer.

7. The fluorinated resin-based copper-clad laminate according to claim 6, characterized in that, The first fluororesin is a tetrafluoroethylene-fluoropropyl perfluorovinyl ether copolymer.

8. The fluorinated resin-based copper-clad laminate according to claim 1, characterized in that, The second filler includes silica and optionally other filler B.

9. The fluorinated resin-based copper-clad laminate according to claim 8, characterized in that, The volume percentage of silica in the second filler is 80-100%.

10. The fluorinated resin-based copper-clad laminate according to claim 8, characterized in that, The other filler B includes any one or a combination of at least two of the following: titanium dioxide, barium titanate, strontium titanate, chopped glass fiber, alumina, boron nitride, silicon nitride, hollow glass microspheres, and hollow silica.

11. The fluorinated resin-based copper-clad laminate according to claim 10, characterized in that, The other filler B is titanium dioxide.

12. The fluorinated resin-based copper-clad laminate according to claim 1, characterized in that, The second fluororesin includes any one or a combination of at least two of the following: polytetrafluoroethylene, tetrafluoroethylene-fluoropropyl perfluorovinyl ether copolymer, perfluoroethylene propylene, tetrafluoroethylene-perfluoroalkoxy perfluorovinyl ether copolymer, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, and ethylene-chlorotrifluoroethylene copolymer.

13. The fluorinated resin-based copper-clad laminate according to claim 1, characterized in that, The thickness of the fluorinated resin film A is 10-80 μm.

14. The fluorinated resin-based copper-clad laminate according to claim 13, characterized in that, The thickness of the fluorinated resin film A is 12.5-64 μm.

15. The fluorinated resin-based copper-clad laminate according to claim 1, characterized in that, The dimensional stability of the fluorinated resin membrane A is -36000 ppm to -2500 ppm.

16. The fluorinated resin-based copper-clad laminate according to claim 1, characterized in that, The thickness of the fluorinated resin film B is 10-180 μm.

17. The fluorinated resin-based copper-clad laminate according to claim 16, characterized in that, The thickness of the fluorinated resin film B is 38-127 μm.

18. The fluorinated resin-based copper-clad laminate according to claim 1, characterized in that, The dimensional stability of the fluorinated resin membrane B is from 0 ppm to 2500 ppm, excluding 0.

19. The fluorinated resin-based copper-clad laminate according to claim 1, characterized in that, The number of fluorinated resin films B in the intermediate fluorinated resin layer is 2-24.

20. A method for preparing a fluorinated resin-based copper-clad laminate as described in any one of claims 1-19, characterized in that, The preparation method includes: Fluorine-containing resin film A, fluorine-containing resin film B, and copper foil are stacked in sequence to obtain a laminated structure with copper foil on both sides and the fluorine-containing resin film A bonded to the copper foil; the laminated structure is then laminated to obtain the fluorine-containing resin-based copper clad laminate.

21. A printed circuit board, characterized in that, The printed circuit board includes a fluorinated resin-based copper-clad laminate as described in any one of claims 1-19.

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