Preparation method of flexible and toughened high peel strength copper clad plate

Abstract

The present application relates to a kind of preparation methods of flexible toughening high peel strength copper-clad plate, the copper foil used is first carried out surface plasma treatment to remove surface impurities and contamination, then coupling agent is coated on the surface of copper foil, after drying, it is rolled for standby, according to the requirements of formula, glue solution is configured, glue solution is coated on the copper foil modified by coupling agent, control glue solution viscosity and coating times reach target thickness, after drying and solidification, it is rolled for standby, the copper foil with adhesive is cut according to target size, through high-temperature lamination, composite material and copper foil are tightly combined to make copper-clad plate.The present application ensures that the copper of copper-clad plate and the adhesion of composite material itself are good under the premise, using specific processing process, glue solution and copper strip are subjected to simultaneously unwinding, temperature rising, winding, high-temperature lamination and other external condition changes, timely release stress generated in the processing of material, improve the bendable performance and processing performance of copper-clad plate, realize continuous production, and production efficiency is high.

Description

Technical Field

[0001] This invention relates to the field of circuit boards, specifically a method for preparing a flexible and toughened copper-clad laminate with good processing performance and high peel strength. Background Technology

[0002] As electronic information products continue to develop towards ultra-high integration and multi-functionality, printed circuit boards (PCBs) face the demands of high density and multi-dimensional assembly. This necessitates high dimensional stability, low coefficient of thermal expansion, small bendable internal angles, and high peel strength for copper-clad laminates (CCLs). Conventional board materials typically have a peel strength of 0.5 N / mm or higher. To meet the complex processing requirements of PCBs, rigid-flex PCBs are currently widely used. However, the fabrication of rigid-flex PCBs requires splicing rigid and flexible CCLs. Materials with different mechanical properties exhibit different dimensional and thickness changes when heated, leading to difficulties in matching the mechanical properties at the splice points. This can result in copper strip bulging, delamination, or even detachment during PCB processing, directly causing short circuits and open circuits—a catastrophic defect for electronic interconnect applications. Experience shows that rigid-flex PCBs require high peel strength, generally at least 1.5 N / mm.

[0003] In existing technologies, the main approach is to change the formulation design of composite materials to increase the bendability of rigid copper-clad laminates or thermosetting composite materials, thereby achieving the goal of increasing the flexibility and toughness of composite materials.

[0004] For example, the heat-bendable copper-clad laminate described in invention patent CN107953630 improves the bendability of the copper-clad laminate by adding phenoxy resin to the formulation. However, as the amount of phenoxy resin increases, it gradually becomes unable to fully bond with the epoxy resin system, and the free phenoxy resin leads to a decrease in the thermal and dimensional properties of the system. This method has a bottleneck in improving the bendability of the copper-clad laminate. Furthermore, this preparation method still involves first making an impregnated sheet and then applying copper, without significantly improving the peel strength of the copper-clad laminate.

[0005] In recent years, researchers have also improved the processing procedure. Considering that PCBs require copper foil as a conductor layer, they have studied combining resin adhesive with copper foil to create coated copper foil. This simplifies the PCB pressing and stacking process. Invention patent CN106467668 provides a method for preparing silicone resin-based aluminum-based copper-clad laminates. This method involves coating a silicone resin adhesive containing various crosslinking agents onto copper foil without curing, resulting in coated copper foil. An aluminum plate and the coated copper foil are then stacked and pressurized under vacuum. This method uses vinyl-terminated silicone oil as an active diluent, which effectively reduces the brittleness of silicone resin and improves the toughness of the silicone resin composition. However, this method does not involve curing, and the silicone resin has strong fluidity, making it difficult to guarantee thickness uniformity under vacuum pressure, which is unsuitable for high-frequency and ultra-high-frequency applications.

[0006] Invention patent CN110294920 provides a high-toughness weather-resistant resin composition. Using a coating process, a toughening-enhancing, weather-resistant resin liquid is coated onto an aluminum plate, and then baked at high temperature to form a coated aluminum plate. The surface of the coated aluminum plate is then covered with copper foil and hot-pressed in a vacuum press to obtain a copper-clad laminate. This method, through toughness testing, shows no obvious cracks in the insulation layer after bending 180°. However, aluminum plates themselves have poor bending properties, limiting production to a single-sheet production model, making continuous production difficult and achieving good batch consistency challenging. Furthermore, this method is also unsuitable for preparing double-sided copper-clad laminates.

[0007] Invention patent CN113831852 discloses a coated copper foil, its preparation method, and its application. The method involves coating a resin composition onto the rough surface of a copper foil, drying it to obtain a copper foil with a resin layer; then, a protective film is adhered to the side of the resin layer away from the copper foil, resulting in a coated copper foil. The coated copper foil provided by this invention has good high-temperature resistance and good insulation, and its resin layer has good flowability and adhesive strength. However, the product produced by this method is a coated copper foil, not a copper-clad laminate, and this patent does not address the need for increasing the flexibility and toughness of rigid copper-clad laminates.

[0008] Invention patent CN112351591 discloses a method for preparing a PTFE-based microwave composite dielectric material substrate with high peel strength. By uniformly coating a sodium-naphthalene complex surface modifier on the substrate, the adhesion performance between the composite material and the copper foil is improved. Although the peel strength of the product is improved, this method does not involve improving the bendability of the copper-clad laminate. Furthermore, the sodium-naphthalene complex treatment process involves a waste liquid treatment step, and the treatment cost is relatively high.

[0009] The aforementioned technical methods cannot fundamentally solve the problem of copper strip bulging or detachment at the rigid-flexible joint after stress and heat during the processing of rigid-flexible laminates due to factors such as mismatch in the thermal expansion coefficients of the copper strip and the composite material, inconsistent dimensional changes, and inconsistent thicknesses. Good thickness uniformity and high peel strength are prerequisites for preparing flexible and toughened copper-clad laminates. Improving the bendability of the copper-clad laminate, while ensuring good adhesion between the copper and the composite material itself, is essential to better meet the processing requirements of rigid-flexible laminates. Summary of the Invention

[0010] To address the shortcomings of existing technologies, this invention provides a method for preparing a flexible, toughened, and high-peel-strength copper-clad laminate. While ensuring good adhesion between the copper and the composite material, a specific processing procedure is employed to subject the adhesive and copper strip to simultaneous external conditions such as unwinding, heating, winding, and high-temperature lamination. This timely releases the stress generated during processing, improving the bendability and processing performance of the copper-clad laminate. This method offers strong compatibility with composite material formulations, overcoming the bottleneck problem in existing technologies where increasing the toughness of the resin limits its content. Furthermore, it leverages the inherent suitability of copper foil for multiple unwinding and winding processes, enabling continuous production with high efficiency. The flexible, toughened, and high-peel-strength copper-clad laminate solves problems such as copper strip bulging and delamination that occur during the lamination of rigid and flexible copper-clad laminates, meeting the needs of industrial production.

[0011] To achieve this objective, the present invention adopts the following technical solution: a method for preparing a flexible, tough, and high peel strength copper-clad laminate, wherein the copper foil is first subjected to surface plasma treatment to remove surface impurities and contaminants, then a coupling agent is coated on the surface of the copper foil, and after drying, it is rolled up for use. An adhesive solution is prepared according to the formula, and the adhesive solution is coated on the copper foil modified with the coupling agent. The viscosity of the adhesive solution and the number of coatings are controlled to achieve the target thickness. After drying and curing, it is rolled up for use. The adhesive-coated copper foil is cut according to the target size, and the composite material is tightly bonded to the copper foil through high-temperature lamination to form a copper-clad laminate.

[0012] The specific steps are as follows:

[0013] Step 1, Copper Foil Processing: The surface of the copper foil is processed using a plasma generation device. First, the rolled copper foil is unwound and then pulled through the reaction chamber of the plasma device. The plasma atmosphere is argon, the pulling speed is 0.5m / min-2m / min, the processing frequency is 50kHz-5MHz, and the processing time is 2s-10s. The processed copper foil is then rolled up to obtain the processed copper foil.

[0014] Step 2: Preparation of copper foil modification solution: Add 5%-30% of silane coupling agent to a 70%-95% acid-alcohol solution, stir for 10-30 minutes until the silane coupling agent is completely hydrolyzed to obtain the copper foil modification solution; the silane coupling agent is one or more of the following: silane coupling agent with unsaturated double bonds, silane coupling agent with acryloyloxy group, silane coupling agent with epoxy group, and silane coupling agent with amino group; the acid-alcohol solution is a solution prepared by mixing 10%-50% formic acid and 50%-90% ethanol by volume.

[0015] Step 3: Coating with copper foil modification solution: Coating the copper foil modification solution onto the surface of the copper foil using methods such as scraping, roller coating, or extrusion coating, with a coating thickness of 0.5μm-3μm. Then, dry it at a temperature of 60℃-90℃ and roll it up to obtain modified copper foil.

[0016] Step 4, preparation of adhesive solution: The adhesive solution is composed of the following components in the following proportions: organic resin 35wt%-55wt%, organic solvent 20wt%-50wt%, inorganic filler 10wt%-30wt%, curing agent 1wt%-5wt%. Weigh the organic resin and organic solvent according to the proportions, mix them, and mechanically stir until dissolved. Then add the inorganic filler and disperse it at a high speed of 1500r / min-3000r / min. Finally, add the curing agent and mechanically stir until dissolved to obtain the adhesive solution.

[0017] Step 5, Adhesive Coating: Apply the adhesive evenly to the surface of the modified copper foil, with a coating thickness of 50μm-300μm, cure at 100℃-150℃, and then roll it up to obtain the adhesive-coated copper foil.

[0018] Step 6: Preparation of copper-clad laminate: Cut the adhesive copper foil to the target size, then place the film side facing the film side, with the copper foil side on the upper and lower surfaces respectively. Finally, vacuum lamination is performed at a temperature of 260℃-380℃ and a pressure of 4MPa-10MPa to obtain the copper-clad laminate.

[0019] In the above technical solution, the organic resin is selected from any one or a combination of at least two of the following: polytetrafluoroethylene resin, epoxy resin, cyanate ester resin, polyphenylene ether resin, polybutadiene resin, polybutadiene-styrene copolymer resin, polybenzoxazine resin, polyimide, silicone resin, bismaleimide resin, liquid crystal polymer, and bismaleimide triazine resin; the organic solvent is selected from any one or a combination of at least two of the following: acetone, butanone, cyclohexanone, propylene glycol methyl ether, propylene glycol methyl ether acetate, and toluene; the inorganic filler is selected from any one or a combination of at least two of the following: silica, alumina, titanium dioxide, barium titanate, strontium titanate, magnesium titanate, calcium titanate, barium strontium titanate, lead titanate, and glass powder; and the curing agent is selected from any one or a combination of at least two of the following: phenolic curing agent, amine curing agent, polymeric anhydride curing agent, active ester, and free radical initiator.

[0020] The beneficial effects of this invention are: by using plasma to treat the surface of copper foil and then coating it with a modifying liquid, the adhesion between copper and composite materials in the copper-clad laminate is improved, laying the foundation for the preparation of flexible and toughened copper-clad laminates.

[0021] Combining the ease of unwinding and rewinding of copper foil with the high precision of the coating process, the adhesive is uniformly coated on the copper strip. The adhesive and copper strip are simultaneously subjected to changes in external conditions such as unwinding, heating, rewinding, and high-temperature lamination. Residual stress is eliminated in time during the preparation process, improving the bendability and processing performance of the copper-clad laminate and meeting the processing requirements of rigid-flex laminates.

[0022] Each step of this process is a continuous operation, and the resulting copper-clad laminate has both a uniform thickness and uniform peel strength in terms of effective area.

[0023] The method of this invention improves processing efficiency and yield, and is beneficial to environmental protection and large-scale production. Detailed Implementation

[0024] A method for preparing a flexible, tough, and high peel strength copper-clad laminate involves first performing a surface plasma treatment on the copper foil to remove surface impurities and contaminants, then coating the copper foil surface with a coupling agent, drying it, and then winding it up for later use. An adhesive solution is prepared according to a formula and applied to the copper foil modified with the coupling agent. The viscosity of the adhesive solution and the number of coatings are controlled to achieve the target thickness. After drying and curing, the copper foil is wound up for later use. The adhesive-coated copper foil is cut to the target size, and the composite material is tightly bonded to the copper foil through high-temperature lamination to form the copper-clad laminate.

[0025] Example 1: Step 1, Copper Foil Treatment: The surface of the copper foil is treated using a plasma generation device. First, the rolled copper foil is unwound, then drawn through the reaction chamber of the plasma device. The plasma atmosphere used is argon, the drawing speed is 0.8 m / min, the treatment frequency is 5 MHz, and the treatment time is 8 s. The treated copper foil is then wound up to obtain the treated copper foil. The treated copper foil must be used within 10 hours.

[0026] Step 2, Preparation of copper foil modification solution: Add 30% aminosilane coupling agent to 70% acid alcohol solution. The acid alcohol solution consists of 10% formic acid and 90% ethanol by volume. Stir for 30 minutes until the silane coupling agent is completely hydrolyzed to obtain copper foil modification solution.

[0027] Step 3: Coating with copper foil modification solution: Using a roller coating method, the copper foil modification solution is coated onto the surface of the copper foil to a thickness of 3μm. It is then dried at 90℃ and wound up to obtain the modified copper foil. The modified copper foil must be used within 90 days.

[0028] Step 4, preparation of adhesive solution: Mix 35wt% polytetrafluoroethylene resin with 30wt% cyclohexanone and stir mechanically until dissolved. Then add 30wt% silica and disperse at high speed at 1500r / min. Finally, add 5wt% high molecular weight anhydride curing agent and stir mechanically until dissolved to obtain the adhesive solution.

[0029] Step 5, Adhesive Coating: Using an extrusion coating method, the adhesive is evenly coated on the surface of the modified copper foil to a thickness of 50μm. Then, it is dried and cured at 150℃ and rolled up to obtain the adhesive-coated copper foil.

[0030] Step 6: Preparation of copper-clad laminate: Cut the adhesive copper foil to the target size, then place the film side facing the film side, with the copper foil side on the upper and lower surfaces respectively. Finally, vacuum lamination is performed at a temperature of 380℃ and a pressure of 10MPa to obtain the copper-clad laminate.

[0031] Step 7: Copper Clad Laminate Performance Testing: The thickness and tolerance of the board are 45±5μm, the Z-axis thermal expansion coefficient (CTE) is 42ppm / ℃, the copper clad laminate has good bending and forming effect, the inner angle reaches 120°, and the peel strength reaches 2.8N / mm.

[0032] Example 2: This invention provides a method for preparing a flexible, toughened, and high-peel-strength copper-clad laminate, specifically comprising the following steps:

[0033] Step 1: Copper Foil Treatment: The surface of the copper foil is treated using a plasma generator. First, the rolled copper foil is unwound, then drawn through the reaction chamber of the plasma equipment. The plasma atmosphere used is argon, the drawing speed is 1.8 m / min, the treatment frequency is 5 MHz, and the treatment time is 4 seconds. The treated copper foil is then wound up to obtain the treated copper foil. The treated copper foil must be used within 10 hours.

[0034] Step 2, Preparation of copper foil modification solution: Add 30% aminosilane coupling agent to 70% acid alcohol solution. The acid alcohol solution consists of 10% formic acid and 90% ethanol by volume. Stir for 30 minutes until the silane coupling agent is completely hydrolyzed to obtain copper foil modification solution.

[0035] Step 3: Coating with copper foil modification solution: Using an extrusion coating method, the copper foil modification solution is coated onto the surface of the copper foil to a thickness of 3 μm. It is then dried at 90°C and wound up to obtain the modified copper foil. The modified copper foil must be used within 90 days.

[0036] Step 4, preparation of adhesive solution: Mix 35wt% polytetrafluoroethylene resin with 30wt% cyclohexanone and stir mechanically until dissolved. Then add 30wt% silica and disperse at high speed at 1500r / min. Finally, add 5wt% high molecular weight anhydride curing agent and stir mechanically until dissolved to obtain the adhesive solution.

[0037] Step 5, Adhesive Coating: Using a scraper roller coating method, the adhesive is evenly coated on the surface of the modified copper foil to a thickness of 60μm. Then, it is dried and cured at 150℃ and rolled up to obtain the adhesive-coated copper foil.

[0038] Step 6: Preparation of copper-clad laminate: Cut the adhesive copper foil to the target size, then place the film side facing the film side, with the copper foil side placed on the upper and lower surfaces respectively. Finally, vacuum lamination is performed at a temperature of 380℃ and a pressure of 4MPa to obtain the copper-clad laminate.

[0039] Step 7: Copper Clad Laminate Performance Testing: The thickness and tolerance of the board are 55±5μm, the Z-axis thermal expansion coefficient (CTE) is 45ppm / ℃, the copper clad laminate has good bending and forming effect, the inner angle can reach 130°, and the peel strength is 2.1N / mm.

[0040] Example 3: This invention provides a method for preparing a flexible, toughened, and high-peel-strength copper-clad laminate, specifically comprising the following steps:

[0041] Step 1: Copper Foil Treatment: The surface of the copper foil is treated using a plasma generator. First, the rolled copper foil is unwound, then drawn through the reaction chamber of the plasma equipment. The plasma atmosphere used is argon, the drawing speed is 1 m / min, the treatment frequency is 50 kHz, and the treatment time is 8 seconds. The treated copper foil is then wound up to obtain the treated copper foil. The treated copper foil must be used within 10 hours.

[0042] Step 2, Preparation of copper foil modification solution: Add 30% epoxy silane coupling agent to 70% acid alcohol solution. The acid alcohol solution consists of 10% formic acid and 90% ethanol by volume. Stir for 30 minutes until the silane coupling agent is completely hydrolyzed to obtain copper foil modification solution.

[0043] Step 3: Coating with copper foil modification solution: Using a scraping method, the copper foil modification solution is coated onto the surface of the copper foil to a thickness of 3μm. It is then dried at 60℃ and wound up to obtain the modified copper foil. The modified copper foil must be used within 90 days.

[0044] Step 4, preparation of adhesive solution: Mix 55wt% epoxy resin with 20wt% cyclohexanone and stir mechanically until dissolved. Then add 20wt% alumina and disperse at a high speed of 3000r / min. Finally, add 5wt% amine curing agent and stir mechanically until dissolved to obtain the adhesive solution.

[0045] Step 5, Adhesive Coating: Using an extrusion coating method, the adhesive is evenly coated on the surface of the modified copper foil to a thickness of 280μm. Then, it is dried and cured at 100℃ and rolled up to obtain the adhesive-coated copper foil.

[0046] Step 6: Preparation of copper-clad laminate: Cut the adhesive copper foil to the target size, then place the film side facing the film side, with the copper foil side placed on the upper and lower surfaces respectively. Finally, vacuum lamination is performed at a temperature of 260℃ and a pressure of 4MPa to obtain the copper-clad laminate.

[0047] Step 7: Copper Clad Laminate Performance Testing: The thickness and tolerance of the board are 270±10μm, the Z-axis thermal expansion coefficient (CTE) is 50ppm / ℃, the copper clad laminate has good bending and forming effect, the inner angle reaches 140°, and the peel strength is 2.6N / mm.

[0048] Example 4: This invention provides a method for preparing a flexible, toughened, and high-peel-strength copper-clad laminate, specifically comprising the following steps:

[0049] Step 1: Copper Foil Treatment: The surface of the copper foil is treated using a plasma generator. First, the rolled copper foil is unwound, then drawn through the reaction chamber of the plasma equipment. The plasma atmosphere used is argon, the drawing speed is 1 m / min, the treatment frequency is 50 kHz, and the treatment time is 5 seconds. The treated copper foil is then wound up to obtain the treated copper foil. The treated copper foil must be used within 10 hours.

[0050] Step 2, Preparation of copper foil modification solution: Add 5% epoxy silane coupling agent to 95% acid alcohol solution. The acid alcohol solution consists of 10% formic acid and 90% ethanol by volume. Stir for 30 minutes until the silane coupling agent is completely hydrolyzed to obtain copper foil modification solution.

[0051] Step 3: Coating with copper foil modification solution: Using a roller coating method, the copper foil modification solution is coated onto the surface of the copper foil to a thickness of 0.5 μm. It is then dried at 60°C and wound up to obtain the modified copper foil. The modified copper foil must be used within 90 days.

[0052] Step 4, preparation of adhesive solution: Mix 55wt% epoxy resin with 20wt% cyclohexanone and stir mechanically until dissolved. Then add 24wt% alumina and disperse at a high speed of 3000r / min. Finally, add 1wt% amine curing agent and stir mechanically until dissolved to obtain the adhesive solution.

[0053] Step 5, Adhesive Coating: Using an extrusion coating method, the adhesive is evenly coated on the surface of the modified copper foil to a thickness of 300μm. Then, it is dried and cured at 100℃ and rolled up to obtain the adhesive-coated copper foil.

[0054] Step 6: Preparation of copper-clad laminate: Cut the adhesive copper foil to the target size, then place the film side facing the film side, with the copper foil side placed on the upper and lower surfaces respectively. Finally, vacuum lamination is performed at a temperature of 260℃ and a pressure of 4MPa to obtain the copper-clad laminate.

[0055] Step 7: Copper Clad Laminate Performance Testing: The thickness and tolerance of the board are 290±10μm, the Z-axis thermal expansion coefficient (CTE) is 50ppm / ℃, the copper clad laminate has good bending and forming effect, the inner angle reaches 140°, and the peel strength is 1.9N / mm.

[0056] Example 5: This invention provides a method for preparing a flexible, toughened, and high-peel-strength copper-clad laminate, specifically comprising the following steps:

[0057] Step 1: Copper Foil Treatment: The surface of the copper foil is treated using a plasma generation device. First, the rolled copper foil is unwound, then drawn through the reaction chamber of the plasma equipment. The plasma atmosphere used is argon, the drawing speed is 1.8 m / min, the treatment frequency is 5 MHz, and the treatment time is 5 seconds. The treated copper foil is then wound up to obtain the treated copper foil. The treated copper foil must be used within 10 hours.

[0058] Step 2, Preparation of copper foil modification solution: Add 30% acryloyloxysilane coupling agent to 70% acid alcohol solution. The acid alcohol solution consists of 50% formic acid and 50% ethanol by volume. Stir for 10 minutes until the silane coupling agent is completely hydrolyzed to obtain copper foil modification solution.

[0059] Step 3: Coating with copper foil modification solution: Using a scraping method, the copper foil modification solution is coated onto the surface of the copper foil to a thickness of 3μm. It is then dried at 90℃ and wound up to obtain the modified copper foil. The modified copper foil must be used within 90 days.

[0060] Step 4, preparation of adhesive solution: Mix 54wt% polybutadiene and 20wt% cyclohexanone, stir mechanically until dissolved, then add 25wt% titanium dioxide and disperse at high speed at 1500r / min, finally add 1wt% phenolic curing agent and stir mechanically until dissolved to obtain adhesive solution.

[0061] Step 5, Adhesive Coating: Using an extrusion coating method, the adhesive is evenly coated on the surface of the modified copper foil to a thickness of 50μm. Then, it is dried and cured at 150℃ and rolled up to obtain the adhesive-coated copper foil.

[0062] Step 6: Preparation of copper-clad laminate: Cut the adhesive copper foil to the target size, then place the film side facing the film side, with the copper foil side placed on the upper and lower surfaces respectively. Finally, vacuum lamination is performed at a temperature of 260℃ and a pressure of 4MPa to obtain the copper-clad laminate.

[0063] Step 7: Copper Clad Laminate Performance Testing: The thickness and tolerance of the board are 45±5μm, the Z-axis thermal expansion coefficient (CTE) is 40ppm / ℃, the copper clad laminate has good bending and forming effect, the inner angle reaches 150°, and the peel strength is 1.9N / mm.

[0064] Example 6: This invention provides a method for preparing a flexible, toughened, and high-peel-strength copper-clad laminate, specifically comprising the following steps:

[0065] Step 1: Copper Foil Treatment: The surface of the copper foil is treated using a plasma generator. First, the rolled copper foil is unwound, then drawn through the reaction chamber of the plasma equipment. The plasma atmosphere used is argon, the drawing speed is 0.8 m / min, the treatment frequency is 1 MHz, and the treatment time is 5 seconds. The treated copper foil is then wound up to obtain the treated copper foil. The treated copper foil must be used within 10 hours.

[0066] Step 2, Preparation of copper foil modification solution: Add 30% acryloyloxysilane coupling agent to 70% acid alcohol solution. The acid alcohol solution consists of 50% formic acid and 50% ethanol by volume. Stir for 10 minutes until the silane coupling agent is completely hydrolyzed to obtain copper foil modification solution.

[0067] Step 3: Coating with copper foil modification solution: Using a roller coating method, the copper foil modification solution is coated onto the surface of the copper foil to a thickness of 0.5 μm. It is then dried at 60°C and wound up to obtain the modified copper foil. The modified copper foil must be used within 90 days.

[0068] Step 4, preparation of adhesive solution: Mix 54wt% polyimide resin with 20wt% cyclohexanone and stir mechanically until dissolved. Then add 25wt% titanium dioxide and disperse at high speed at 1500r / min. Finally, add 1wt% phenolic curing agent and stir mechanically until dissolved to obtain the adhesive solution.

[0069] Step 5, Adhesive Coating: Using a roller coating method, the adhesive is evenly coated on the surface of the modified copper foil to a thickness of 260μm. Then, it is dried and cured at 150℃ and rolled up to obtain the adhesive-coated copper foil.

[0070] Step 6: Preparation of copper-clad laminate: Cut the adhesive copper foil to the target size, then place the film side facing the film side, with the copper foil side placed on the upper and lower surfaces respectively. Finally, vacuum lamination is performed at a temperature of 260℃ and a pressure of 4MPa to obtain the copper-clad laminate.

[0071] Step 7: Copper Clad Laminate Performance Testing: The thickness and tolerance of the board are 250±10μm, the Z-axis thermal expansion coefficient (CTE) is 40ppm / ℃, the copper clad laminate has good bending and forming effect, the inner angle reaches 150°, and the peel strength is 2.1N / mm.

[0072] Example 7: This invention provides a method for preparing a flexible, toughened, and high-peel-strength copper-clad laminate, specifically comprising the following steps:

[0073] Step 1: Copper Foil Treatment: The surface of the copper foil is treated using a plasma generator. First, the rolled copper foil is unwound, then drawn through the reaction chamber of the plasma equipment. The plasma atmosphere used is argon, the drawing speed is 1.8 m / min, the treatment frequency is 100 kHz, and the treatment time is 8 seconds. The treated copper foil is then wound up to obtain the treated copper foil. The treated copper foil must be used within 10 hours.

[0074] Step 2, Preparation of copper foil modification solution: Add 5% aminosilane coupling agent to 95% acid alcohol solution. The acid alcohol solution consists of 10% formic acid and 90% ethanol by volume. Stir for 10 minutes until the silane coupling agent is completely hydrolyzed to obtain copper foil modification solution.

[0075] Step 3: Coating with copper foil modification solution: Using a roller coating method, the copper foil modification solution is coated onto the surface of the copper foil to a thickness of 3μm. It is then dried at 90℃ and wound up to obtain the modified copper foil. The modified copper foil must be used within 90 days.

[0076] Step 4, preparation of adhesive solution: Mix 55wt% bismaleimide resin with 19wt% propylene glycol methyl ether and stir mechanically until dissolved. Then add 25wt% silica and disperse at high speed at 3000r / min. Finally, add 1wt% active ester curing agent and stir mechanically until dissolved to obtain the adhesive solution.

[0077] Step 5, Adhesive Coating: Using an extrusion coating method, the adhesive is evenly coated on the surface of the modified copper foil to a thickness of 50μm. Then, it is dried and cured at 100℃ and rolled up to obtain the adhesive-coated copper foil.

[0078] Step 6: Preparation of copper-clad laminate: Cut the adhesive copper foil to the target size, then place the film side facing the film side, with the copper foil side on the upper and lower surfaces respectively. Finally, vacuum lamination is performed at a temperature of 260℃ and a pressure of 10MPa to obtain the copper-clad laminate.

[0079] Step 7: Copper Clad Laminate Performance Testing: The thickness and tolerance of the board are 45±5μm, the Z-axis thermal expansion coefficient (CTE) is 40ppm / ℃, the copper clad laminate has good bending and forming effect, the inner angle reaches 120°, and the peel strength is 2.8N / mm.

[0080] Example 8: This invention provides a method for preparing a flexible, toughened, and high-peel-strength copper-clad laminate, specifically comprising the following steps:

[0081] Step 1: Copper Foil Treatment: The surface of the copper foil is treated using a plasma generator. First, the rolled copper foil is unwound, then drawn through the reaction chamber of the plasma equipment. The plasma atmosphere used is argon, the drawing speed is 1.8 m / min, the treatment frequency is 100 kHz, and the treatment time is 8 seconds. The treated copper foil is then wound up to obtain the treated copper foil. The treated copper foil must be used within 10 hours.

[0082] Step 2, Preparation of copper foil modification solution: Mix 15% aminosilane coupling agent and 15% acryloyloxy silane coupling agent, and then add them to a 70% acid-alcohol solution. The acid-alcohol solution consists of 10% formic acid and 90% ethanol by volume. Stir for 10 minutes until the silane coupling agent is completely hydrolyzed to obtain the copper foil modification solution.

[0083] Step 3: Coating with copper foil modification solution: Using a roller coating method, the copper foil modification solution is coated onto the surface of the copper foil to a thickness of 2μm. It is then dried at 90℃ and wound up to obtain the modified copper foil. The modified copper foil must be used within 90 days.

[0084] Step 4: Preparation of adhesive solution: Mix 55wt% polytetrafluoroethylene resin with 20wt% cyclohexanone and stir mechanically until dissolved. Then add 15wt% silica and 5% titanium dioxide and disperse at a high speed of 1500r / min. Finally, add 5wt% phenolic curing agent and stir mechanically until dissolved to obtain the adhesive solution.

[0085] Step 5, Adhesive Coating: Using a roller coating method, the adhesive is evenly coated on the surface of the modified copper foil to a thickness of 300μm. Then, it is dried and cured at 100℃, and then rolled up to obtain the adhesive-coated copper foil.

[0086] Step 6: Preparation of copper-clad laminate: Cut the adhesive copper foil to the target size, then place the film side facing the film side, with the copper foil side on the upper and lower surfaces respectively. Finally, vacuum lamination is performed at a temperature of 380℃ and a pressure of 10MPa to obtain the copper-clad laminate.

[0087] Step 7: Copper Clad Laminate Performance Testing: The thickness and tolerance of the board are 290±10μm, the Z-axis thermal expansion coefficient (CTE) is 40ppm / ℃, the copper clad laminate has good bending and forming effect, the inner angle reaches 120°, and the peel strength is 3.2N / mm.

[0088] The specific data from the eight embodiments show that, within the scope defined by the claims, the method of treating the copper foil surface with plasma and then coating it with a modifying liquid improves the adhesion between the copper and the composite material in the copper-clad laminate. The highest peel strength achieved is 3.2 N / mm, and the lowest is 1.9 N / mm, which lays the foundation for improving the flexibility of the board. This invention utilizes the ease of unwinding and rewinding of the copper foil itself and the high precision of the coating process to ensure uniform coating of the adhesive onto the copper strip, achieving good control over the board thickness uniformity. The minimum thickness tolerance can reach ±5 μm. Because the adhesive and copper strip are simultaneously subjected to external conditions such as unwinding, heating, rewinding, and high-temperature lamination, residual stress is eliminated in a timely manner during the preparation process, improving the bendability and processing performance of the copper-clad laminate. The maximum bending inner angle can reach 150°, and the Z-axis thermal expansion coefficient is (45±5) ppm / ℃. The board produced by this method has good mechanical properties, and the copper-clad laminate exhibits good bending forming effect, meeting the processing requirements of rigid-flexible laminates.

[0089] As can be seen from the copper foil modification liquid and adhesive formulations of the eight embodiments, this method has strong compatibility with the formulations of copper foil modification liquid and adhesive, and solves the bottleneck problem in the prior art where the upper limit of the toughness resin content is limited when increasing the toughness resin to achieve flexibility and toughness.

Claims

1. A method for preparing a flexible, toughened, and high-peel-strength copper-clad laminate, characterized in that: The specific steps are as follows: Step 1, Copper Foil Processing: The surface of the copper foil is processed using a plasma generation device. First, the rolled copper foil is unwound and then pulled through the reaction chamber of the plasma device. The plasma atmosphere is argon, the pulling speed is 0.5m / min-2m / min, the processing frequency is 50kHz-5MHz, and the processing time is 2s-10s. The processed copper foil is then rolled up to obtain the processed copper foil. Step 2: Preparation of copper foil modification solution: Add 5%-30% of silane coupling agent to a 70%-95% acid-alcohol solution, stir for 10-30 minutes until the silane coupling agent is completely hydrolyzed to obtain the copper foil modification solution; the silane coupling agent is one or more of the following: silane coupling agent with unsaturated double bonds, silane coupling agent with acryloyloxy group, silane coupling agent with epoxy group, and silane coupling agent with amino group; the acid-alcohol solution is a solution prepared by mixing 10%-50% formic acid and 50%-90% ethanol by volume. Step 3: Coating with copper foil modification solution: Coating the copper foil modification solution onto the surface of the copper foil using a scraping, roller coating or extrusion coating method, with a coating thickness of 0.5μm-3μm, and then drying at a temperature of 60℃-90℃, and then winding to obtain modified copper foil; Step 4, preparation of adhesive solution: The adhesive solution is composed of the following components in the following proportions: organic resin 35wt%-55wt%, organic solvent 20wt%-50wt%, inorganic filler 10wt%-30wt%, curing agent 1wt%-5wt%. Weigh the organic resin and organic solvent according to the proportions, mix them, and mechanically stir until dissolved. Then add the inorganic filler and disperse it at a high speed of 1500r / min-3000r / min. Finally, add the curing agent and mechanically stir until dissolved to obtain the adhesive solution. Step 5, Adhesive Coating: Apply the adhesive evenly to the surface of the modified copper foil, with a coating thickness of 50μm-300μm, cure at 100℃-150℃, and then roll it up to obtain the adhesive-coated copper foil. Step 6: Preparation of copper-clad laminate: Cut the adhesive copper foil to the target size, then place the film side facing the film side, with the copper foil side on the upper and lower surfaces respectively. Finally, vacuum lamination is performed at a temperature of 260℃-380℃ and a pressure of 4MPa-10MPa to obtain the copper-clad laminate.

2. The method for preparing a flexible, toughened, and high peel strength copper-clad laminate as described in claim 1, characterized in that: The organic resin is selected from any one or a combination of at least two of the following: polytetrafluoroethylene resin, epoxy resin, cyanate ester resin, polyphenylene ether resin, polybutadiene resin, polybutadiene-styrene copolymer resin, polybenzoxazine resin, polyimide, bismaleimide resin, and bismaleimide triazine resin; the organic solvent is selected from any one or a combination of at least two of the following: acetone, butanone, cyclohexanone, propylene glycol methyl ether, propylene glycol methyl ether acetate, and toluene; the inorganic filler is selected from any one or a combination of at least two of the following: silica, alumina, titanium dioxide, barium titanate, strontium titanate, magnesium titanate, calcium titanate, barium strontium titanate, lead titanate, and glass powder; the curing agent is selected from any one or a combination of at least two of the following: phenolic curing agent, amine curing agent, reactive ester curing agent, and polymeric anhydride curing agent.