Light-shielding flexible copper clad plate, method for preparing same, and use thereof

Abstract

The application provides a light-shielding flexible copper-clad plate, a preparation method and application thereof. The light-shielding flexible copper-clad plate comprises a copper foil layer and a polyimide film layer, and further comprises a light-shielding adhesive layer arranged between the copper foil layer and the polyimide film layer. The light-shielding adhesive layer comprises a composite light-shielding filler, the composite light-shielding filler comprises modified flaky light-shielding pigment, carbon black and auxiliary filler, and the weight ratio of the modified flaky light-shielding pigment, the carbon black and the auxiliary filler is (3-6):(2-5):(1-3). The modified flaky light-shielding pigment comprises flaky light-shielding pigment and an inorganic oxide layer coated on the surface of the flaky light-shielding pigment. Based on a ternary composite light-shielding system, the combination of black pigment with a flaky structure and nanoscale carbon black is adopted, and the auxiliary filler is supplemented, so that a multi-dimensional light-shielding network is constructed, thereby realizing high optical density under a lower filler content and ensuring excellent light-shielding effect.

Description

Technical Field

[0001] This invention relates to the field of electronic device fabrication, and more specifically, to a light-shielding flexible copper-clad laminate, its fabrication method, and its applications. Background Technology

[0002] As consumer electronics (such as smartphones, wearable devices, and camera modules), automotive displays, and high-precision optical equipment evolve towards thinner, lower-density integration, and smarter designs, higher demands are being placed on the performance of flexible copper-clad laminates (CCLs). Flexible CCLs, as a key basic material, are highly favored for their excellent flexibility, high strength, and good electrical properties. However, with the continuous expansion of application scenarios, especially for products that need to maintain reliability in extreme environments, the limitations of traditional flexible CCLs are becoming increasingly apparent, the most significant being their insufficient light-shielding performance. In applications such as smartphone camera modules, display backings for wearable devices, and circuit integration in night vision equipment, light-shielding performance becomes a crucial consideration. Light leakage can not only lead to signal distortion, affecting image quality and product performance, but can also reduce sensor sensitivity due to optical interference, and even compromise the aesthetics and stealth capabilities of electronic components. Therefore, developing flexible CCLs with high light-shielding capabilities has become an urgent need in the industry. Currently, the mainstream light-shielding flexible CCLs on the market achieve their light-shielding effect primarily through the following methods:

[0003] Firstly, black polyimide (PI) film is used: it is expensive, and black PI may be inferior to traditional yellow PI in terms of heat resistance and mechanical strength.

[0004] Secondly, applying a black ink or coating to the surface: While applying an additional layer of black ink or a light-shielding coating to the PI film of a traditional flexible copper-clad laminate can meet basic light-shielding requirements, it introduces new problems in actual production. First, the extra coating process increases production time and cost. Second, the interfacial adhesion between the ink or coating and the PI film is limited, especially under prolonged use and frequent bending, which may lead to delamination or cracking, resulting in reduced light-shielding performance. Furthermore, coating uniformity is also a significant challenge, easily causing performance differences between products.

[0005] Thirdly, adding black pigments to the adhesive: This involves adding black pigments such as carbon black to the adhesive. Theoretically, a high carbon black content (generally 30%-50%) can significantly improve the light-blocking effect, but in practice, excessive carbon black addition can lead to a series of thorny problems. First, the high density and strong aggregation tendency of carbon black particles significantly reduce the flowability and processability of the adhesive, increasing the difficulty of coating; second, the high heat absorption of carbon black may cause localized heat concentration during subsequent laser processing, thus affecting the consistency and reliability of the product; third, excessive carbon black may also damage the electrical insulation properties of the adhesive, posing a potential risk to high-frequency signal transmission and precision circuit layout.

[0006] While the aforementioned methods each have their advantages, they all face a common bottleneck: how to balance the pursuit of ultimate light-shielding performance with other core properties (such as mechanical strength, electrical insulation, and ease of processing), especially when products need to withstand extreme environmental conditions or complex manufacturing processes. In general, for light-shielding flexible copper-clad laminates, existing technologies struggle to simultaneously achieve optimal light-shielding performance, bonding reliability, processability, and cost.

[0007] Therefore, how to provide a light-shielding flexible copper-clad laminate that balances light-shielding performance and adhesion reliability is one of the technical problems that need to be solved in this field. Summary of the Invention

[0008] The main objective of this invention is to provide a light-shielding flexible copper-clad laminate, its preparation method, and its application, so as to solve the problem that the existing light-shielding flexible copper-clad laminates are difficult to balance light-shielding performance and bonding reliability.

[0009] To achieve the above objectives, a first aspect of the present invention provides a light-shielding flexible copper-clad laminate, comprising a copper foil layer and a polyimide film layer. The light-shielding flexible copper-clad laminate further includes a light-shielding adhesive layer disposed between the copper foil layer and the polyimide film layer. The light-shielding adhesive layer includes a composite light-shielding filler, which includes a modified flake light-shielding pigment, carbon black, and auxiliary fillers, wherein the weight ratio of the modified flake light-shielding pigment, carbon black, and auxiliary fillers is (3~6):(2~5):(1~3). The modified flake light-shielding pigment includes a flake light-shielding pigment and an inorganic oxide layer coated on the surface of the flake light-shielding pigment.

[0010] Furthermore, the aspect ratio of the modified flake-shaped opaque pigment is (10~50):1.

[0011] Furthermore, the modified flake-shaped opaque pigment has a flake diameter of 1μm to 5μm.

[0012] Furthermore, the thickness of the modified flake-shaped opaque pigment is 0.1 μm to 0.3 μm.

[0013] Further, the weight ratio of the flaky opaque pigment to the inorganic oxide layer is (5~30):(1~3); preferably, the flaky opaque pigment is selected from one or more of flaky iron oxide and flaky black composite titanium powder.

[0014] Furthermore, the material of the inorganic oxide layer is selected from one or more of silicon dioxide, aluminum oxide, titanium dioxide and zinc oxide; more preferably, the aspect ratio of the flake-shaped light-shielding pigment is (20~40):1, the flake diameter is 1μm~5μm, and the thickness is 0.1μm~0.3μm.

[0015] Furthermore, in the inorganic oxide layer, the D50 particle size of the inorganic oxide material is 0.02μm~0.1μm.

[0016] Furthermore, the modified flake-shaped opaque pigment is obtained by coating and modifying flake-shaped iron oxide black with silica. The aspect ratio of the flake-shaped iron oxide black is (30~35):1, the flake diameter is 2.8μm~3.2μm, the thickness is 0.08μm~0.12μm, the D50 particle size of the silica is 0.04μm~0.06μm, and the weight ratio of flake-shaped iron oxide black to silica is (6~8):1.

[0017] Furthermore, in the composite light-shielding filler, the carbon black particle size is 20nm~50nm.

[0018] Furthermore, the volume resistivity of carbon black is 10. 6 Ω·cm~10 12 Ω·cm.

[0019] Furthermore, the weight ratio of the modified flake opaque pigment to carbon black is (3~5):(2~3).

[0020] Furthermore, the auxiliary filler includes flake titanium dioxide, the flake titanium dioxide having a diameter of 0.2μm to 5.0μm and a thickness of 0.05μm to 0.3μm; preferably, the flake titanium dioxide has a diameter of 0.5μm to 2.0μm and a thickness of 0.08μm to 0.15μm.

[0021] Furthermore, the auxiliary filler includes flake barium sulfate, with a flake diameter of 0.1μm~3.0μm and a thickness of 0.02μm~0.2μm; or flake barium sulfate with a flake diameter of 0.3μm~1.5μm and a thickness of 0.05μm~0.1μm.

[0022] Further, by weight, the light-shielding adhesive layer comprises 20 to 50 parts of matrix resin, 3 to 10 parts of toughening rubber, 5 to 15 parts of curing agent, 30 to 45 parts of composite light-shielding filler, and 1 to 5 parts of functional additives; preferably, the matrix resin is epoxy resin; more preferably, the epoxy resin is selected from one or more of bisphenol A type epoxy resin, phenolic type epoxy resin, and alicyclic epoxy resin.

[0023] Furthermore, the toughening rubber is selected from one or more of core-shell rubber, carboxylated butadiene-acrylonitrile rubber, and terminal epoxy-based butadiene-acrylonitrile rubber.

[0024] Furthermore, the functional additives include coupling agents and / or leveling agents.

[0025] More preferably, by weight, the light-shielding adhesive layer comprises 25 to 35 parts of epoxy resin, 4 to 8 parts of toughening rubber, 6 to 10 parts of curing agent, 20 to 25 parts of modified flake light-shielding pigment, 10 to 15 parts of carbon black, 5 to 10 parts of auxiliary filler, 1 to 2 parts of coupling agent, and 0.3 to 0.8 parts of leveling agent.

[0026] Furthermore, the thickness ratio of the copper foil layer, the light-shielding adhesive layer, and the polyimide film layer is (1.0~1.8):1:(0.8~2.5).

[0027] A second aspect of the present invention provides a method for preparing the above-mentioned light-shielding flexible copper-clad laminate, comprising a step of laminating a copper foil layer and a polyimide film layer, wherein a light-shielding adhesive layer is provided between the copper foil layer and the polyimide film layer during the lamination process; the light-shielding adhesive layer includes a composite light-shielding filler, the composite light-shielding filler including a modified flake light-shielding pigment, carbon black and auxiliary filler, and the weight ratio of the modified flake light-shielding pigment, carbon black and auxiliary filler is (3~6):(2~5):(1~3); the modified flake light-shielding pigment is an inorganic oxide-coated modified flake light-shielding pigment.

[0028] Furthermore, the preparation method of the light-shielding flexible copper-clad laminate includes a preparation process of modified flake-shaped light-shielding pigment, and the preparation process of the modified flake-shaped light-shielding pigment includes: step R1, dispersing the flake-shaped light-shielding pigment in a solvent to obtain a dispersion; step R2, adding an inorganic oxide precursor to the dispersion and carrying out a modification reaction under the action of a catalyst to obtain the modified flake-shaped light-shielding pigment; the weight ratio of the flake-shaped light-shielding pigment to the inorganic oxide precursor is (5~10):(1~2); and / or, the inorganic oxide precursor is selected from tetraethyl orthosilicate, aluminum alkoxide, titanium alkoxide and zinc alkoxide. One or more; and / or, the solvent is selected from one or more of ethanol, isopropanol, toluene, methyl ethyl ketone, and N-methylpyrrolidone; and / or, the catalyst is selected from one or more of ammonia, triethylamine, dilute hydrochloric acid, and acetic acid, and the amount of catalyst added is 0.1 wt.% to 2.0 wt.% based on 100% of the total weight of the flake-shaped opaque pigment; and / or, the modification reaction is a hydrolysis-condensation reaction to form a coating layer of inorganic oxide precursor on the surface of the flake-shaped opaque pigment, and the reaction temperature of the hydrolysis-condensation reaction is 50℃ to 80℃, and the reaction time is 2h to 6h.

[0029] A third aspect of the present invention provides an application of a light-shielding flexible copper-clad laminate in the fields of electronic devices, display and backlight devices, high-precision optical devices, and touch and sensing devices, wherein the light-shielding flexible copper-clad laminate is the aforementioned light-shielding flexible copper-clad laminate; or, the light-shielding flexible copper-clad laminate is prepared by the aforementioned method for preparing the light-shielding flexible copper-clad laminate.

[0030] By applying the technical solution of this invention, based on a ternary composite light-shielding system, a multi-dimensional light-shielding network is constructed by using a combination of sheet-like black pigment and nano-sized carbon black, supplemented by auxiliary fillers. This achieves the goal of significantly improving the light-shielding performance of flexible copper-clad laminates without affecting other core performances, thereby achieving high optical density with low filler content and ensuring excellent light-shielding effect. Detailed Implementation

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0032] As described in the background section, existing light-shielding flexible copper-clad laminates suffer from the problem of difficulty in simultaneously achieving light-shielding performance and bonding reliability. To address this technical problem, a first aspect of the present invention provides a light-shielding flexible copper-clad laminate, comprising a copper foil layer and a polyimide film layer. The light-shielding flexible copper-clad laminate further includes a light-shielding adhesive layer disposed between the copper foil layer and the polyimide film layer. The light-shielding adhesive layer includes a composite light-shielding filler, which comprises a modified flake-shaped light-shielding pigment, carbon black, and auxiliary fillers, wherein the weight ratio of the modified flake-shaped light-shielding pigment, carbon black, and auxiliary fillers is (3~6):(2~5):(1~3). The modified flake-shaped light-shielding pigment comprises a flake-shaped light-shielding pigment and an inorganic oxide layer coated on the surface of the flake-shaped light-shielding pigment.

[0033] This invention incorporates a light-shielding adhesive layer between a copper foil layer and a polyimide (PI) film layer, its primary function being to form a robust and efficient light-shielding barrier. Traditional light-shielding methods, such as surface coating with black ink / coating, increase the number of processes and costs, result in weak interfacial adhesion, are prone to delamination and cracking, and have difficulty controlling coating uniformity. Adding high amounts of carbon black directly to adhesives leads to poor adhesive flow and deteriorated processability; furthermore, the high heat absorption of carbon black can trigger thermal runaway during laser processing and impair electrical insulation properties, limiting high-frequency applications. In contrast, the light-shielding adhesive layer provided by this invention integrates modified flake-shaped light-shielding pigments, carbon black, and auxiliary fillers. Through the synergistic effect of these three components, the light-shielding performance and overall material quality are significantly improved. Specifically, the flake-shaped light-shielding pigments in the adhesive layer are tightly coated with a layer of inorganic oxide to form modified flake-shaped light-shielding pigments. The inorganic oxides can form a thin and dense insulating oxide layer on the surface of the flake-shaped pigments through a hydrolysis-condensation reaction. The presence of this oxide layer not only isolates the conductivity of the flake pigment itself, ensuring its high volume resistivity and excellent electrical insulation properties in the light-shielding adhesive layer, but also significantly enhances the interfacial bonding strength between the pigment and the adhesive matrix, improves the bending resistance and high-temperature reliability of the adhesive layer, and reduces the risk of peeling and delamination under flexural and high-temperature conditions.

[0034] Meanwhile, the modified flake-shaped light-blocking pigment, with its unique planar geometry, forms a structure similar to multi-layered roof tiles within the light-blocking adhesive layer. Each flake structure effectively blocks incident light, and through multiple reflections and refractions, greatly extends the light's propagation path within the material, thus significantly enhancing the light-blocking effect. Even at low addition levels, this flake structure achieves high optical density. Compared to spherical carbon black, the flake-shaped pigment used in this invention exhibits better dispersibility in adhesive systems. After modification, the surface activity of the flake pigment is further improved, allowing for better integration with the adhesive matrix. This not only reduces the viscosity of the adhesive layer but also improves its leveling properties, facilitating precision coating and subsequent processing.

[0035] More importantly, in the light-shielding adhesive layer provided by this invention, there is a significant synergistic effect between the modified flake-shaped light-shielding pigment, carbon black, and auxiliary fillers. The flake-shaped pigment, acting as a physical barrier, effectively blocks and reflects / refracts most incident light multiple times through its high aspect ratio flake structure, arranged parallel within the adhesive layer. The carbon black focuses on absorbing residual light, ensuring that any light quanta penetrating the flake-shaped pigment layer are rapidly absorbed, preventing light leakage due to secondary reflection. The auxiliary fillers further disrupt the light propagation path through light scattering effects and help improve the uniformity of the adhesive layer's appearance, reducing uneven "blackness." The three work together to form a comprehensive and durable light-shielding network. The light-shielding effect is most significant when the weight ratio of the three components is as described above, because the flake-shaped pigment effectively blocks most light, while the carbon black ensures that any light quanta penetrating the flake layer are rapidly absorbed, preventing light leakage due to secondary reflection.

[0036] In summary, the light-shielding flexible copper-clad laminate provided by this invention has the following technical effects:

[0037] Firstly, it boasts superior light-blocking properties: Through its unique ternary composite light-blocking system of "sheet-like physical barrier + nano absorption + scattering enhancement", the components produce a synergistic effect, achieving extremely high optical density (OD value ≥ 4.5 @ 400~700nm) with a relatively low total filler addition (for example, 30 to 50 parts by weight), far exceeding traditional carbon black filler adhesives (OD value is usually ≤ 3.0 at the same thickness).

[0038] Secondly, excellent comprehensive performance: Due to the use of highly efficient composite light-shielding filler, the amount of carbon black used is reduced, the bonding strength between the light-shielding adhesive layer and the copper foil layer is greater than or equal to 0.9 N / mm, and the bending resistance, heat resistance and chemical resistance are maintained or even improved.

[0039] Thirdly, it offers excellent processability and appearance: the adhesive has good leveling properties, resulting in uniform coating and a smooth finished surface free of particles or white spots, which facilitates subsequent etching, cover film lamination, and other processes. The composite light-shielding filler has low laser absorption, improving the processing window for laser drilling.

[0040] Fourth, high cost-effectiveness: Under the premise of achieving the same or better light-blocking effect, conventional yellow PI film with lower cost can be used, and the cost of adhesive formulation is controllable, which has significant commercial advantages.

[0041] Furthermore, the aspect ratio of the modified flake-shaped light-shielding pigment is preferably (10~50):1 (more preferably (20~40):1); and / or, the flake diameter of the modified flake-shaped light-shielding pigment is 1μm~5μm; and / or, the thickness of the modified flake-shaped light-shielding pigment is 0.1μm~0.3μm. These characteristics provide better orientation and dispersibility, enabling the formation of a more efficient physical light-shielding barrier within the light-shielding adhesive layer, thereby significantly improving the light-shielding capability of the final light-shielding flexible copper-clad laminate. The preferred weight ratio of the flake-shaped light-shielding pigment to the inorganic oxide layer is (5~30):(1~3), more preferably (20~30):1. This ensures that the surface of the flake-shaped light-shielding pigment is fully coated without excess, forming a more uniform and dense insulating layer, thereby further improving the light-shielding efficiency. Meanwhile, the optimized coating ratio obtained above can further improve the stability of the modified flake-shaped light-shielding pigment in the light-shielding adhesive layer, and the interfacial bonding force with the light-shielding adhesive layer matrix is ​​also improved accordingly, ultimately resulting in a light-shielding adhesive layer with stronger adhesion and better light-shielding properties, thus optimizing the various performance characteristics of the light-shielding flexible copper-clad laminate.

[0042] To further enhance the light-shielding effect and improve the structural stability of the resulting flexible copper-clad laminate, the preferred flake-shaped light-shielding pigment is selected from one or more of flake-shaped iron oxide black (model BAYFERROX® BLACK 4330 / 4340) or flake-shaped black composite titanium powder (model Zhongke Sanhuan TC-100); and / or, the preferred material for the inorganic oxide layer is selected from one or more of silicon dioxide, aluminum oxide, titanium trioxide, and zinc oxide. Furthermore, the preferred aspect ratio of the flake-shaped light-shielding pigment is (20~40):1, with a flake diameter of 1μm~5μm and a thickness of 0.1μm~0.3μm, to allow the modified flake-shaped pigment to extend the light propagation path to a greater extent. Preferably, in the inorganic oxide layer, the D50 particle size of the inorganic oxide material is 0.02μm~0.1μm, which can more effectively modify the flake-shaped pigment, forming a denser and more stable coating layer, further optimizing the light-shielding ability, electrical insulation, and stability of the resulting light-shielding adhesive layer.

[0043] Furthermore, the modified flake-shaped light-shielding pigment is obtained by coating flake iron oxide black with silica. The aspect ratio of the flake iron oxide black is (30~35):1, the flake diameter is 2.8μm~3.2μm, the thickness is 0.08μm~0.12μm, the D50 particle size of the silica is 0.04μm~0.06μm, and the weight ratio of flake iron oxide black to silica is (24~26):1. The modified flake-shaped light-shielding pigment obtained by this preferred scheme can better synergize with carbon black and auxiliary fillers to form a more efficient and stable light-shielding system, ultimately resulting in a flexible copper-clad laminate with better light-shielding properties and mechanical stability.

[0044] Furthermore, the carbon black in the composite light-shielding filler preferably has a particle size of 20 nm to 50 nm, in order to more effectively absorb light penetrating the flake-like pigment layer, reduce light leakage, and more effectively reduce rheological property deterioration and agglomeration. The preferred volume resistivity of the carbon black is 10 Ω·cm. 6 Ω·cm~10 12 The modified flake-shaped light-blocking pigment and carbon black are preferably in a weight ratio of (3~5):(2~3) to better complement each other and further improve the light-blocking and insulation properties of the resulting flexible copper-clad laminate. More preferably, the weight ratio of the modified flake-shaped light-blocking pigment, carbon black, and auxiliary filler is (3~5):(2~3):2 to better leverage their synergistic effect and achieve a more significant improvement in light-blocking properties and adhesion reliability.

[0045] The auxiliary fillers in the composite light-shielding filler are preferably flake-shaped titanium dioxide and / or flake-shaped barium sulfate. To promote more uniform dispersion of the auxiliary fillers in the adhesive layer and to form light scattering centers, thereby increasing the probability of random reflection of light within the composite light-shielding layer and more effectively reducing light transmittance, the flake-shaped titanium dioxide preferably has a sheet diameter of 0.2 μm to 5.0 μm (more preferably 0.5 μm to 2.0 μm) and a thickness of 0.05 μm to 0.3 μm (more preferably 0.08 μm to 0.15 μm); the flake-shaped barium sulfate preferably has a sheet diameter of 0.1 μm to 3.0 μm (more preferably 0.3 μm to 1.5 μm) and a thickness of 0.02 μm to 0.2 μm (more preferably 0.05 μm to 0.1 μm). In practical applications, the auxiliary fillers can be further surface-treated with a coupling agent to further improve their dispersibility and compatibility in the light-shielding adhesive layer.

[0046] In several preferred embodiments, the light-shielding adhesive layer comprises, by weight, 20 to 50 parts of a base resin, 3 to 10 parts of toughening rubber, 5 to 15 parts of a curing agent, 30 to 45 parts of a composite light-shielding filler, and 1 to 5 parts of a functional additive. In several more preferred embodiments, the light-shielding adhesive layer comprises, by weight, 25 to 35 parts of epoxy resin, 4 to 8 parts of toughening rubber, 6 to 10 parts of a curing agent, 20 to 25 parts of modified flake light-shielding pigment, 10 to 15 parts of carbon black, 5 to 10 parts of auxiliary filler, 1 to 2 parts of coupling agent, and 0.3 to 0.8 parts of leveling agent. The formulation ratios obtained through these progressive optimizations enable the construction of a more stable and efficient composite light-shielding system. Simultaneously, the dosage of each component in the above formulation also promotes better maintenance of the composite light-shielding layer during processing, thereby more effectively achieving a dual improvement in light-shielding effect and product quality. It is worth noting that the above-mentioned formulation provided by the present invention can achieve extremely high optical density with a low total filler content, far exceeding that of traditional carbon black filler adhesives.

[0047] In practical applications, the matrix resin is epoxy resin, used for adhesion and heat resistance; the toughening rubber is used to provide flexural strength. Specifically, the epoxy resin can be selected from one or more of bisphenol A type epoxy resin (manufacturer model: Nan Ya NPEL-128), phenolic epoxy resin (manufacturer model: Nan Ya NPCN-704), and alicyclic epoxy resin (manufacturer model: Daicel Celloxide 2021P); and / or, the toughening rubber can be selected from one or more of core-shell rubber (manufacturer model: Rohm and Haas Paraaloid EXL-2650), carboxylated nitrile butadiene rubber (manufacturer model: Rion Hycar 1300X8), and terminal epoxy-based nitrile butadiene rubber (manufacturer model: Rion Hycar 2000X16); and / or, the functional additives may include coupling agents and / or leveling agents, and may further contain defoamers. The curing agent further improves the storage stability and controllable curing characteristics of the resulting composite adhesive layer.

[0048] Furthermore, based on a comprehensive consideration of light-shielding effect, mechanical strength, electrical insulation and processing adaptability, the thickness ratio of copper foil layer, light-shielding adhesive layer and polyimide film layer in light-shielding flexible copper clad laminate is preferably (1.0~1.8):1:(0.8~2.5), thereby further achieving a synergistic improvement in light-shielding effect, electrical insulation and mechanical strength.

[0049] A second aspect of the present invention provides a method for preparing the above-mentioned light-shielding flexible copper-clad laminate, comprising a step of laminating a copper foil layer and a polyimide film layer, wherein a light-shielding adhesive layer is provided between the copper foil layer and the polyimide film layer during the lamination process; the light-shielding adhesive layer includes a composite light-shielding filler, the composite light-shielding filler including a modified flake light-shielding pigment, carbon black and auxiliary filler, and the weight ratio of the modified flake light-shielding pigment, carbon black and auxiliary filler is (3~6):(2~5):(1~3); the modified flake light-shielding pigment is an inorganic oxide-coated modified flake light-shielding pigment.

[0050] Furthermore, the preparation method of the light-shielding flexible copper-clad laminate includes a process for preparing modified flake-shaped light-shielding pigments, which comprises: step R1, dispersing the flake-shaped light-shielding pigments in a solvent to obtain a dispersion; step R2, adding an inorganic oxide precursor to the dispersion and carrying out a modification reaction under the action of a catalyst to obtain the modified flake-shaped light-shielding pigments. In the above preparation process of the modified flake-shaped light-shielding pigments, in order to obtain an inorganic oxide layer of more suitable thickness and better integrate with the adhesive matrix to further improve the light-shielding effect, the preferred weight ratio of the flake-shaped light-shielding pigments to the inorganic oxide precursors is (5~10):(1~2). In practical applications, based on the type of inorganic oxide layer to be formed, the inorganic oxide precursors are preferably selected from one or more of tetraethyl orthosilicate, aluminum alkoxide, titanium alkoxide, and zinc alkoxide. The solvent can be selected from one or more of ethanol, isopropanol, toluene, butanone, and N-methylpyrrolidone (NMP).

[0051] To make the coating process more efficient, the catalyst is preferably selected from one or more of ammonia, triethylamine, dilute hydrochloric acid and acetic acid, and the amount of catalyst added is 0.1wt.%~2.0wt.% based on the total weight of the flake-shaped opaque pigment as 100%.

[0052] Specifically, in order to obtain a denser and more uniform inorganic oxide layer and further optimize the light-shielding ability of the final light-shielding adhesive layer, it is preferable that the modification reaction in the above process is essentially a hydrolysis-condensation reaction, so that the inorganic oxide precursor forms a coating layer on the surface of the flake-shaped light-shielding pigment, and the reaction temperature of the hydrolysis-condensation reaction is 50℃~80℃, and the reaction time is 2h~6h.

[0053] In practical applications, the preparation method of light-shielding flexible copper-clad laminate also includes (Scheme 1): Step S1, toughening rubber, first solvent, and composite light-shielding filler are ground to obtain a first material; the first material, matrix resin, functional additives, second solvent, and curing agent are dispersed to obtain a mixed adhesive; Step S2, the mixed adhesive is coated onto one side of a polyimide film layer (generally black) to form a wet film; the wet film is semi-cured to form a semi-cured film; Step S3, copper foil is bonded to the side of the semi-cured film away from the polyimide film layer to obtain an intermediate product; the intermediate product is sequentially subjected to hot pressing and curing treatment to completely cure the semi-cured film into a light-shielding adhesive layer, thereby obtaining a light-shielding flexible copper-clad laminate. In particular, pre-dispersing and grinding the toughening rubber, first solvent, and composite light-shielding filler into the first material, through the crushing and dispersion of filler particles and the micro-mechanical abrasion of the particle surface by the grinding media, significantly improves the dispersion uniformity and light absorption efficiency of the composite light-shielding filler. Afterwards, through the formation of the mixed adhesive, the coating and semi-curing of the wet film, and the bonding and final pressing and curing of the copper foil and the semi-cured film, a light-shielding flexible copper-clad laminate with better overall performance is obtained. Of course, the preparation method can also be carried out in the following manner (Scheme 2): Step S1, toughening rubber, first solvent and composite light-shielding filler are ground to obtain first material; the first material, matrix resin, functional additives, second solvent and curing agent are dispersed to obtain mixed adhesive; Step S2, the mixed adhesive is coated onto the surface of the polyimide film of the adhesive-free single-sided flexible copper-clad laminate (the side away from the copper foil layer) to form a wet film; the wet film is semi-cured to form a semi-cured film; Step S3, the side of the semi-cured film away from the adhesive-free single-sided panel is bonded to release paper or release PET to obtain an intermediate product with release material; the intermediate product is sequentially hot-pressed and cured to completely cure the semi-cured film into a light-shielding adhesive layer, and after peeling off the release material, a light-shielding flexible copper-clad laminate is obtained.

[0054] Furthermore, in step S1, the fineness of the first material is preferably ≤10μm, and / or the solid content of the mixed adhesive is 40±5wt.%, so as to form a denser light-shielding network in the subsequent adhesive layer preparation process, reduce light leakage, and also improve the flowability and coating performance of the mixed adhesive, thereby enhancing the uniformity and stability of the light-shielding layer during the production process. In step S2, in order to cooperate with the special filler system and promote the gradual evaporation of the solvent in the adhesive layer, while a controllable pre-curing reaction occurs to form a semi-cured adhesive film with more suitable viscosity, creating better favorable conditions for subsequent bonding and pressing, the semi-curing treatment preferably includes a first curing at a temperature of 60±5℃, a second curing at a temperature of 90±5℃, a third curing at a temperature of 130±10℃, and a fourth curing at a temperature of 160±10℃, and the total curing time is 5min~10min. In step S3, the preferred hot-pressing temperature is 50℃~150℃, and the hot-pressing is carried out under a pressure of 2MPa~6MPa, thereby promoting more thorough contact and uniform bonding between the copper foil and the adhesive layer, forming a composite structure with better mechanical properties. The preferred curing temperature is 150℃~180℃, and the time is 2h~4h, and the curing is carried out under oxygen-free conditions. This results in a more uniform and dense composite light-shielding layer, while also avoiding interference from oxygen in the curing reaction, such as oxidation side reactions, further improving the chemical stability and electrical insulation properties of the resulting adhesive layer.

[0055] A third aspect of the present invention provides an application of the aforementioned light-shielding flexible copper-clad laminate in the fields of electronic devices, display and backlight devices, high-precision optical devices, and touch and sensing devices. Because the aforementioned light-shielding flexible copper-clad laminate provided by the present invention possesses particularly superior light-shielding performance and mechanical stability, it can meet the application requirements of multiple fields, especially in applications with high requirements for internal wiring and shielding, and in precision electronic components with stringent light-shielding requirements, effectively preventing optical signal interference and improving device stability.

[0056] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0057] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0058] Example 1

[0059] A method for preparing a light-shielding flexible copper-clad laminate:

[0060] The mixed adhesive to be prepared in this embodiment includes: bisphenol A type epoxy resin (30 parts, as the matrix resin), nitrile rubber (6 parts, as the toughening rubber), modified imidazole latent curing agent (8 parts), modified flake iron oxide black (22.5 parts, aspect ratio of 40:1, flake diameter of 4μm, thickness of 0.1μm, accounting for 50% of the total composite light-shielding filler), and nano carbon black (13.5 parts, particle size of 30nm, volume conductivity of 10). 8 The following ingredients are used as functional additives: Ω·cm (30% of the total composite light-shielding filler), flake titanium dioxide (9 parts, flake diameter 1.2μm, thickness 0.1μm, accounting for 20% of the total composite light-shielding filler), coupling agent (1 part, manufacturer model KH-550), and leveling agent (0.5 parts, manufacturer model BYK-333). Butanone is used as a solvent, and the solid content of the mixed adhesive is 40%.

[0061] The modified flake iron oxide black was prepared in the following manner: flake iron oxide black (Fe3O4) with an aspect ratio of 40:1, a flake diameter of 4μm and a thickness of 0.1μm was used as the flake filler to be coated, and tetraethyl orthosilicate (TEOS) was used as the coating source.

[0062] (R1) Using an ethanol-water mixed solvent (volume ratio 9:1) as the solvent, flake iron oxide black was dispersed in it to obtain a dispersion;

[0063] (R2) Tetraethyl orthosilicate (TEOS) was used as an inorganic oxide (silica) precursor, and TEOS was added to the dispersion at a mass ratio of 7:1 for flake iron oxide black. Simultaneously, 25% ammonia water (0.5 wt.%) was added as a catalyst, based on 100% of the total weight of the flake opaque pigment. A hydrolysis-condensation reaction was then carried out at 65°C for 3 hours to promote the formation of a uniform and continuous coating layer of the inorganic oxide precursor on the surface of the flake opaque pigment. Finally, after washing, drying, and pulverizing, modified flake iron oxide black was obtained.

[0064] The obtained modified flake iron oxide black includes flake iron oxide black and an inorganic oxide coating layer covering its outer surface, wherein the weight ratio of flake iron oxide black to inorganic oxide coating layer is 25:1. In the inorganic oxide coating layer, the D50 particle size of silica is 0.05 μm.

[0065] Next, light-shielding flexible copper-clad laminate is fabricated:

[0066] (1) Preparation of black mixed adhesive: Toughened rubber, part of the solvent, and black composite light-shielding filler were put into a stirred tank and dispersed at high speed under inert gas protection. The mixture was then ground in a sand mill until the fineness reached ≤10μm. The ground raw materials were then put into a stirred tank and, under inert gas protection, epoxy resin, functional additives, and the remaining solvent were added in sequence and dispersed at high speed. Finally, the curing agent was added, and the mixture was stirred at low speed until homogeneous. The mixture was then filtered to obtain a high-light-shielding black epoxy adhesive.

[0067] (2) Coating and semi-curing: The above adhesive solution is uniformly coated on the surface of a 12.5μm thick polyimide film using a precision coating machine. The solvent is removed and semi-cured by step heating in an oven (60℃×2min, 80℃×2min, 120℃×2min, 150℃×2min) to form a black adhesive film with appropriate viscosity.

[0068] (3-1) Pressing and molding: A copper foil with a thickness of 18μm is pressed together with the semi-cured black adhesive film mentioned above using a rubber roller, thereby firmly bonding the copper foil, black adhesive layer and PI film together. The pressing is carried out at a temperature of 120℃ and a pressure of 4MPa.

[0069] (3-2) Post-processing: After curing in an oxygen-free oven (160℃×3h) and cutting, a high-opacity black flexible copper-clad laminate is obtained.

[0070] The resulting light-shielding flexible copper-clad laminate has a uniform black appearance, and the thickness ratio of the copper foil layer, the light-shielding adhesive layer, and the polyimide film layer is 18:15:12.5.

[0071] Example 2

[0072] A method for preparing a light-shielding flexible copper-clad laminate:

[0073] The only difference between this embodiment and Example 1 is the composite light-shielding filler, whose total weight remains unchanged. It includes: 40% by weight of modified flake iron oxide black, 40% by weight of nano carbon black, and 20% by weight of flake barium sulfate (1.5 μm in diameter and 0.1 μm in thickness).

[0074] Example 3

[0075] A method for preparing a light-shielding flexible copper-clad laminate:

[0076] The only difference between this embodiment and Embodiment 1 is that the composite light-shielding filler uses modified flake iron oxide black with a flake diameter of 3μm, a thickness of 0.3μm, and a diameter-to-thickness ratio of 10:1.

[0077] Example 4

[0078] A method for preparing a light-shielding flexible copper-clad laminate:

[0079] The only difference between this embodiment and Embodiment 1 is that the composite light-shielding filler uses modified flake iron oxide black with a flake diameter of 5μm, a thickness of 0.1μm, and a diameter-to-thickness ratio of 50:1.

[0080] Example 5

[0081] A method for preparing a light-shielding flexible copper-clad laminate:

[0082] The only difference between this embodiment and Embodiment 1 is that the particle size of carbon black in the composite light-shielding filler is changed to 10 nm, the particle size of the flake titanium dioxide is changed to 5.0 μm, and the thickness is changed to 0.3 μm.

[0083] Example 6

[0084] A method for preparing a light-shielding flexible copper-clad laminate:

[0085] The only difference between this embodiment and Embodiment 2 is that the particle size of carbon black in the composite light-shielding filler is changed to 60 nm, the particle size of the flake barium sulfate is changed to 0.1 μm, and the thickness is changed to 0.02 μm.

[0086] Example 7

[0087] A method for preparing a light-shielding flexible copper-clad laminate:

[0088] The only difference between this embodiment and Example 1 is that the weight parts of each component in the mixed adhesive are different. Specifically, the bisphenol A type epoxy resin is 20 parts, the nitrile rubber is 10 parts, the modified imidazole latent curing agent is 5 parts, the composite light-shielding filler composed of modified flake iron oxide black, nano carbon black and flake titanium dioxide is 50 parts (the weight ratio of the three is still 5:3:2), the coupling agent is 3 parts, and the leveling agent is 3 parts.

[0089] Example 8

[0090] A method for preparing a light-shielding flexible copper-clad laminate:

[0091] The only difference between this embodiment and Example 1 is that the weight parts of each component in the mixed adhesive are different. Specifically: 50 parts of bisphenol A epoxy resin, 40 parts of nitrile rubber, 15 parts of modified imidazole latent curing agent, 20 parts of composite light-shielding filler composed of modified flake iron oxide black, nano carbon black and flake titanium dioxide (the weight ratio of the three is still 5:3:2), 0.5 parts of coupling agent, and 0.2 parts of leveling agent.

[0092] Example 9

[0093] A method for preparing a light-shielding flexible copper-clad laminate:

[0094] The only difference between this embodiment and Example 1 is that the weight parts of each component in the mixed adhesive are different. Specifically, the bisphenol A type epoxy resin is 50 parts, the nitrile rubber is 3 parts, the modified imidazole latent curing agent is 15 parts, the composite light-shielding filler composed of modified flake iron oxide black, nano carbon black and flake titanium dioxide is 30 parts (the weight ratio of the three is still 5:3:2), the coupling agent is 0.5 parts, and the leveling agent is 0.2 parts.

[0095] Example 10

[0096] A method for preparing a light-shielding flexible copper-clad laminate:

[0097] The only difference between this embodiment and Embodiment 1 is the composite light-shielding filler, whose total weight remains unchanged, wherein the weight ratio of modified composite black pigment, nano carbon black, and flake titanium dioxide is 3:2:1.

[0098] Example 11

[0099] A method for preparing a light-shielding flexible copper-clad laminate:

[0100] The only difference between this embodiment and Embodiment 1 is the composite light-shielding filler, whose total weight remains unchanged, wherein the weight ratio of modified composite black pigment, nano carbon black, and flake titanium dioxide is 6:5:3.

[0101] Example 12

[0102] A method for preparing a light-shielding flexible copper-clad laminate:

[0103] The only difference between this embodiment and Embodiment 1 is that, in preparing the modified flake iron oxide black, the weight ratio of the flake opaque pigment to the inorganic oxide precursor is changed to 12:1.

[0104] Example 13

[0105] A method for preparing a light-shielding flexible copper-clad laminate:

[0106] The only difference between this embodiment and Embodiment 1 is that, in preparing the modified flake iron oxide black, the weight ratio of the flake opaque pigment to the inorganic oxide precursor is changed to 4:2.

[0107] Example 14

[0108] A method for preparing a light-shielding flexible copper-clad laminate:

[0109] The only difference between this embodiment and Example 1 is that, in preparing the modified flake iron oxide black, the hydrolysis-condensation reaction is changed to be carried out at 45°C for 8 hours.

[0110] Example 15

[0111] A method for preparing a light-shielding flexible copper-clad laminate:

[0112] The only difference between this embodiment and Example 1 is that, in preparing the modified flake iron oxide black, the hydrolysis-condensation reaction is changed to be carried out at 85°C for 1 hour.

[0113] Comparative Example 1

[0114] A method for preparing a light-shielding flexible copper-clad laminate:

[0115] The only difference between this comparative example and Example 1 is that an equal weight of high-pigment carbon black is used instead of the composite light-shielding filler.

[0116] Comparative Example 2

[0117] A method for preparing a light-shielding flexible copper-clad laminate:

[0118] The only difference between this comparative example and Example 1 is the composite light-shielding filler, whose total weight remains unchanged, including: 50% by weight of nano carbon black and 50% by weight of spherical iron oxide black (particle size of 3 μm).

[0119] In this comparative example, a higher filler content is required to achieve a similar light-blocking effect as in Example 1, resulting in a sharp increase in processing viscosity and a significant decrease in coating quality.

[0120] Comparative Example 3

[0121] A method for preparing a light-shielding flexible copper-clad laminate:

[0122] The only difference between this comparative example and Example 1 is that, in preparing the modified flake iron oxide black, an equal weight of spherical iron oxide black used in Comparative Example 2 was used instead of the flake iron oxide black in Example 1, and the modified spherical iron oxide black was obtained. This modified spherical iron oxide black was then used as one of the components of the composite light-shielding filler to replace the modified flake iron oxide black in the preparation of the light-shielding flexible copper-clad laminate.

[0123] Comparative Example 4

[0124] A method for preparing a light-shielding flexible copper-clad laminate:

[0125] The only difference between this comparative example and Example 1 is that the weight ratio of modified flake iron oxide black, nano carbon black and flake titanium dioxide in the composite light-shielding filler is changed to 2:1:4.

[0126] Comparative Example 5

[0127] A method for preparing a light-shielding flexible copper-clad laminate:

[0128] The only difference between this comparative example and Example 1 is that the weight ratio of modified flake iron oxide black, nano carbon black and flake titanium dioxide in the composite light-shielding filler is changed to 10:6:1.

[0129] Test methods

[0130] The OD value (optical density, a physical quantity measuring the ability of a medium to block light transmission) at 550 nm was obtained using ultraviolet-visible spectrophotometry. Specifically, the sample after removing the copper foil was cut into 50 mm × 50 mm pieces. Using a blank PI film of the same thickness as a reference, the transmittance T was measured at a wavelength of 550 nm using an ultraviolet-visible spectrophotometer. The result was calculated using the formula OD = -log 10 (T) The optical density value is calculated.

[0131] Copper foil peel strength: The 90° peel strength test method was used (tested according to GB / T 13547-2017 or IPC-TM-6502.4.9 standard). The sample was cut into strips of 3.0 mm × 200 mm (or 10 mm wide), and 20~30 mm of copper foil was pre-peeled. 90° peeling was performed at a speed of 50 mm / min. The average peel force of the stable section was recorded and divided by the sample width to obtain the copper foil peel strength (unit: N / mm).

[0132] The above tests were performed on the light-shielding flexible copper-clad laminate samples obtained in each embodiment and comparative example, and the results are shown in Table 1.

[0133] Table 1

[0134]

[0135] As can be seen from the above description, the embodiments of the present invention, based on a ternary composite light-shielding system, realize the construction of a multi-dimensional light-shielding network, thereby preparing a high-performance flexible copper-clad laminate. The resulting copper-clad laminate not only possesses high light-shielding performance but also exhibits good mechanical structural stability.

[0136] Specifically, in each embodiment:

[0137] Comparing Examples 3 and 4 with Example 1, it can be seen that by optimizing the flake diameter, thickness, and aspect ratio of the modified flake iron oxide black, a more efficient physical light-shielding barrier can be formed in the light-shielding adhesive layer, thereby significantly improving the light-shielding ability of the final light-shielding flexible copper-clad laminate.

[0138] Comparing Examples 5 and 6 with Example 1, it can be seen that by optimizing the particle size of carbon black, the flake size and thickness of auxiliary fillers, light penetrating the flake pigment layer can be absorbed more effectively, reducing light leakage, and at the same time, the deterioration of rheological properties and agglomeration can be reduced more effectively. It can also promote the auxiliary fillers to be more uniformly dispersed in the adhesive layer and form light scattering centers, further increasing the probability of random reflection of light in the composite light-shielding layer and reducing light transmittance more effectively.

[0139] Comparing Examples 7 to 9 with Example 1, it can be seen that by optimizing the weight parts of each component in the mixed adhesive, a more stable and efficient composite light-shielding system can be constructed. At the same time, it can also promote the composite light-shielding layer to maintain a better state during the processing, thereby more effectively achieving a dual improvement in light-shielding effect and product quality.

[0140] Comparing Examples 10 and 11 with Example 1, it can be seen that by optimizing the weight ratio of modified composite black pigment, nano carbon black, and auxiliary filler in the composite light-shielding filler, the synergistic effect of the three can be better utilized, resulting in a more significant improvement in light-shielding performance and bonding reliability.

[0141] Comparing Examples 12 and 13 with Example 1, it can be seen that when preparing modified flake iron oxide black, by optimizing the weight ratio of flake opaque pigment to inorganic oxide precursor, an inorganic oxide layer with a more suitable thickness can be obtained, which can also better integrate with the adhesive matrix and further improve the opaque effect.

[0142] Comparing Examples 14 and 15 with Example 1, it can be seen that by optimizing the conditions of the modification reaction during the preparation of modified flake iron oxide black, a denser and more uniform inorganic oxide layer can be obtained, further optimizing the light-shielding ability of the final light-shielding adhesive layer.

[0143] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0144] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A light-shielding flexible copper-clad laminate, comprising a copper foil layer and a polyimide film layer, characterized in that, The light-shielding flexible copper-clad laminate also includes a light-shielding adhesive layer, and the light-shielding adhesive layer is disposed between the copper foil layer and the polyimide film layer; The light-shielding adhesive layer includes a composite light-shielding filler, which includes modified flake light-shielding pigment, carbon black and auxiliary filler, and the weight ratio of the modified flake light-shielding pigment, the carbon black and the auxiliary filler is (3~6):(2~5):(1~3). The modified flake-shaped opaque pigment includes a flake-shaped opaque pigment and an inorganic oxide layer coated on the surface of the flake-shaped opaque pigment.

2. The light-shielding flexible copper-clad laminate according to claim 1, characterized in that, The aspect ratio of the modified flake-shaped opaque pigment is (10~50):1; and / or, The modified flake-shaped opaque pigment has a flake diameter of 1 μm to 5 μm; and / or, The thickness of the modified flake-shaped opaque pigment is 0.1 μm to 0.3 μm.

3. The light-shielding flexible copper-clad laminate according to claim 1 or 2, characterized in that, The weight ratio of the flaky opaque pigment to the inorganic oxide layer is (5~30):(1~3); Preferably, the flake-shaped opaque pigment is selected from one or more of flake-shaped iron oxide and flake-shaped composite titanium powder; and / or, The material of the inorganic oxide layer is selected from one or more of silicon dioxide, aluminum oxide, titanium oxide, and zinc oxide; More preferably, the aspect ratio of the flake-shaped opaque pigment is (20~40):1, the flake diameter is 1μm~5μm, and the thickness is 0.1μm~0.3μm; and / or, in the inorganic oxide layer, the D50 particle size of the inorganic oxide material is 0.02μm~0.1μm.

4. The light-shielding flexible copper-clad laminate according to claims 1 to 3, characterized in that, The modified flake-shaped opaque pigment is obtained by coating and modifying flake iron oxide black with silica. The aspect ratio of the flake iron oxide black is (30~35):1, the flake diameter is 2.8μm~3.2μm, and the thickness is 0.08μm~0.12μm. The D50 particle size of the silica is 0.04μm~0.06μm, and the weight ratio of the flake iron oxide black to the silica is (6~8):

1.

5. The light-shielding flexible copper-clad laminate according to any one of claims 1 to 4, characterized in that, In the composite light-shielding filler The carbon black has a particle size of 20 nm to 50 nm; and / or, The volume resistivity of the carbon black is 10. 6 Ω·cm~10 12 Ω·cm; and / or, The weight ratio of the modified flake-shaped opaque pigment to the carbon black is (3~5):(2~3); and / or, The auxiliary filler includes flake-shaped titanium dioxide, wherein the flake-shaped titanium dioxide has a diameter of 0.2 μm to 5.0 μm and a thickness of 0.05 μm to 0.3 μm; preferably, the flake-shaped titanium dioxide has a diameter of 0.5 μm to 2.0 μm and a thickness of 0.08 μm to 0.15 μm; and / or, The auxiliary filler includes flake barium sulfate, wherein the flake barium sulfate has a diameter of 0.1 μm to 3.0 μm and a thickness of 0.02 μm to 0.2 μm. Preferably, the flake barium sulfate has a diameter of 0.3 μm to 1.5 μm and a thickness of 0.05 μm to 0.1 μm.

6. The light-shielding flexible copper-clad laminate according to any one of claims 1 to 5, characterized in that, By weight, the light-shielding adhesive layer comprises 20 to 50 parts of matrix resin, 3 to 10 parts of toughening rubber, 5 to 15 parts of curing agent, 30 to 45 parts of the composite light-shielding filler, and 1 to 5 parts of functional additives. Preferably, the matrix resin is epoxy resin; More preferably, the epoxy resin is selected from one or more of bisphenol A type epoxy resin, phenolic type epoxy resin and alicyclic epoxy resin; and / or, the toughening rubber is selected from one or more of core-shell rubber, carboxylated butadiene-acrylonitrile rubber and terminal epoxy group butadiene-acrylonitrile rubber; and / or, the functional additives include coupling agents and / or leveling agents. More preferably, by weight, the light-shielding adhesive layer comprises 25 to 35 parts of the epoxy resin, 4 to 8 parts of the toughening rubber, 6 to 10 parts of the curing agent, 20 to 25 parts of the modified flake light-shielding pigment, 10 to 15 parts of the carbon black, 5 to 10 parts of the auxiliary filler, 1 to 2 parts of the coupling agent, and 0.3 to 0.8 parts of the leveling agent.

7. The light-shielding flexible copper-clad laminate according to any one of claims 1 to 6, characterized in that, The thickness ratio of the copper foil layer, the light-shielding adhesive layer, and the polyimide film layer is (1.0~1.8):1:(0.8~2.5).

8. A method for preparing a light-shielding flexible copper-clad laminate according to any one of claims 1 to 7, comprising the step of laminating the copper foil layer and the polyimide film layer, characterized in that, During the composite process, the light-shielding adhesive layer is disposed between the copper foil layer and the polyimide film layer; The light-shielding adhesive layer includes the composite light-shielding filler, which includes modified flake light-shielding pigment, carbon black and auxiliary filler, and the weight ratio of the modified flake light-shielding pigment, the carbon black and the auxiliary filler is (3~6):(2~5):(1~3). The modified flake-shaped opaque pigment is an inorganic oxide-coated modified flake-shaped opaque pigment.

9. The method for preparing the light-shielding flexible copper-clad laminate according to claim 8, characterized in that, The method for preparing the light-shielding flexible copper-clad laminate further includes a process for preparing the modified flake-shaped light-shielding pigment, and the process for preparing the modified flake-shaped light-shielding pigment includes: Step R1: Disperse the flake-shaped opaque pigment in a solvent to obtain a dispersion; Step R2: An inorganic oxide precursor is added to the dispersion, and a modification reaction is carried out under the action of a catalyst to obtain the modified flake-shaped opaque pigment. The weight ratio of the flaky opaque pigment to the inorganic oxide precursor is (5~10):(1~2); and / or, The inorganic oxide precursor is selected from one or more of tetraethyl orthosilicate, aluminum alkoxide, titanium alkoxide, and zinc alkoxide; and / or, The solvent is selected from one or more of ethanol, isopropanol, toluene, butanone, and N-methylpyrrolidone; and / or, The catalyst is selected from one or more of ammonia, triethylamine, dilute hydrochloric acid, and acetic acid, and the amount of catalyst added is 0.1 wt.% to 2.0 wt.% based on 100% of the total weight of the flake-shaped opaque pigment; and / or, The modification reaction is a hydrolysis-condensation reaction, which causes the inorganic oxide precursor to form a coating layer on the surface of the flake-shaped opaque pigment. The hydrolysis-condensation reaction is carried out at a temperature of 50°C to 80°C and for a reaction time of 2 to 6 hours.

10. The application of a light-shielding flexible copper-clad laminate in the fields of electronic devices, display and backlight devices, high-precision optical devices, and touch and sensing devices, characterized in that, The light-shielding flexible copper-clad laminate is the light-shielding flexible copper-clad laminate according to any one of claims 1 to 7; or, the light-shielding flexible copper-clad laminate is prepared by the preparation method of the light-shielding flexible copper-clad laminate according to claim 8 or 9.

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