Carrier tape and preparation method thereof

Abstract

The embodiment of the invention provides a carrier tape and a preparation method thereof. The preparation method of the carrier tape comprises the following steps: preparing a substrate layer and conductive liquid; coating at least one side of the base material layer with the conductive liquid; and drying the conductive liquid coated on the base material layer to form a conductive film layer adhered to the base material layer. According to the preparation method of the carrier tape provided by the embodiment of the invention, the carrier tape is prepared by replacing three-layer co-extrusion with a double-sided film coating process, and the problems that the thickness of a conductive film layer in the carrier tape is too large, the surface is decarburized, and surface particles exist can be effectively solved.

Description

Technical Field

[0001] This application belongs to the technical field of electronic packaging materials, and particularly relates to a carrier tape and a preparation method thereof. Background Art

[0002] A carrier tape is a strip-shaped plastic film with regularly arranged grooves (pockets), which is used to precisely fix electronic components (such as chips, resistors, capacitors, etc.), and cooperate with automated equipment through positioning holes to achieve high-speed picking and placement. And a closed package is formed by sealing a cover tape above the carrier tape to protect electronic components from pollution and damage during transportation.

[0003] The structure of the sheet for preparing the carrier tape usually includes a layer of polymer material (non-conductive) layer as the intermediate layer, and upper and lower layers of conductive material layers. Currently, the preparation process of the above three-layer structure sheet is three-layer co-extrusion. Due to the requirements of the co-extrusion process, the thickness of the conductive layer will be relatively high, reaching 80μm - 100μm. The antistatic agent used in the conductive layer is carbon nanotubes or carbon black. The products formed by the co-extrusion process have problems of carbon accumulation and surface particles, which are difficult to solve. Summary of the Invention

[0004] In view of this, the embodiments of this application provide a carrier tape and a preparation method thereof to solve the technical problems of carbon accumulation and surface particles existing in the existing carrier tape preparation process.

[0005] In a first aspect, the embodiments of this application provide a preparation method of a carrier tape, including:

[0006] Preparing a base material layer and a conductive liquid;

[0007] Coating the conductive liquid on at least one side of the base material layer;

[0008] Drying the conductive liquid coated on the base material layer to form a conductive film layer adhered to the base material layer.

[0009] In some embodiments, the coating the conductive liquid on at least one side of the base material layer includes:

[0010] Coating the conductive liquid on both sides of the base material layer respectively;

[0011] And the drying the conductive liquid coated on the base material layer to form a conductive film layer adhered to the base material layer includes:

[0012] Forming conductive film layers adhered to both sides of the base material layer to obtain an intermediate tape.

[0013] In some embodiments, before coating the conductive liquid on at least one side of the base material layer, it further includes:

[0014] The surface of at least one side of the substrate layer is modified to improve the surface energy of the substrate layer, enhance the mechanical bite between the conductive film layer and the substrate layer, and avoid the generation of static electricity during the coating process of the conductive liquid.

[0015] In some embodiments, the modification treatment includes any one of corona treatment, plasma treatment, flame treatment, ultraviolet ozone treatment, chemical treatment, and laser treatment.

[0016] In some embodiments, the thickness of the conductive film layer is 5 - 8 μm.

[0017] In some embodiments, the conductive liquid includes carbon nanotubes, a combined dispersant, a main resin, nitrile rubber, and water;

[0018] wherein the combined dispersant includes polyvinylpyrrolidone and polyethylene glycol;

[0019] The main resin includes polyurethane resin and polyurethane epoxy resin.

[0020] In some embodiments, the mass ratio of the carbon nanotubes to the combined dispersant is (0.5 - 1):(0.5 - 1).

[0021] In some embodiments, the mass ratio of the main resin to the nitrile rubber is (3 - 5):1.

[0022] In some embodiments, in the combined dispersant, the mass ratio of polyvinylpyrrolidone to polyethylene glycol is (1 - 3):1.

[0023] In some embodiments, the molar ratio of isocyanate groups to hydroxyl groups contained in the polyurethane resin is 1:(0.5 - 0.8).

[0024] In some embodiments, the elongation rate of the polyurethane resin is 300% - 500%.

[0025] In some embodiments, the hydroxyl value of the polyurethane resin is 80 mgKOH / g - 120 mgKOH / g.

[0026] In some embodiments, the solid content of the conductive liquid is 2% - 3%.

[0027] In some embodiments, the solid content of the polyurethane resin is 35% - 40%.

[0028] In some embodiments, the solid content of the polyurethane epoxy resin is 30% - 35%.

[0029] In some embodiments, the mass ratio of the polyurethane resin to the polyurethane epoxy resin is (3 - 5):1.

[0030] Second aspect, an embodiment of the present application provides a method for preparing a conductive liquid, including the following steps:

[0031] Provide the carbon nanotubes, combined dispersant, matrix resin, and water described in the first aspect;

[0032] Prepare a carbon nanotube slurry;

[0033] Mix the carbon nanotube slurry, the matrix resin, the nitrile rubber, and the water to obtain the conductive liquid.

[0034] In some embodiments, the solid content of the carbon nanotube slurry is 3% - 4%.

[0035] In some embodiments, the particle size D10 of the carbon nanotubes in the carbon nanotube slurry is 0.03 - 0.035 nm.

[0036] In some embodiments, the mass ratio of the carbon nanotube slurry to the matrix resin is 1:(1.5 - 3).

[0037] In some embodiments, the solid content of the nitrile rubber is 45% - 55%.

[0038] In some embodiments, the method for preparing the combined dispersant includes:

[0039] Provide polyvinylpyrrolidone and polyethylene glycol;

[0040] Mix the polyvinylpyrrolidone with the polyethylene glycol to obtain the combined dispersant.

[0041] In some embodiments, the method for preparing the polyurethane epoxy resin includes:

[0042] Provide toluene diisocyanate, polyethylene glycol, epoxy resin, and chain extender;

[0043] Under an inert gas, add polyethylene glycol to the toluene diisocyanate and react to obtain a polyurethane prepolymer;

[0044] Add the epoxy resin and the chain extender to the polyurethane prepolymer and react to obtain the modified polyurethane epoxy resin.

[0045] In some embodiments, the conductive liquid includes a conductive agent and a matrix resin;

[0046] Wherein the conductive agent includes one of carbon nanotubes, carbon black, graphene, graphite, metal powder, metal nanowire, and conductive polymer;

[0047] The main resin includes at least one of polyurethane, epoxy resin, polyester, polyimide, polyethylene, polypropylene, polystyrene, acrylic resin, polycarbonate and silicone resin.

[0048] In some embodiments, the material of the substrate layer includes one or more of acrylonitrile-butadiene-styrene copolymer, polystyrene, high impact polystyrene, and polycarbonate.

[0049] In some embodiments, preparing the substrate layer comprises:

[0050] A preparation material for a substrate layer is provided, and the preparation material is subjected to single-layer extrusion to obtain the substrate layer.

[0051] In some embodiments, the method further comprises: performing vacuum forming and stamping on the intermediate strip to obtain a carrier strip.

[0052] In a second aspect, an embodiment of the present application provides a carrier tape, which is prepared by the preparation method described in the first aspect, and the carrier tape includes a substrate layer and a conductive film layer adhered to both sides of the substrate layer.

[0053] The carrier tape and its preparation method provided in the embodiment of the present application, compared with the existing three-layer co-extrusion preparation process, which results in a higher thickness of the conductive film layer, and the carrier tape products formed by the co-extrusion process have carbon deposition problems and surface particle problems. By extruding the substrate layer in a single layer and then coating the conductive liquid on both sides of the substrate layer to form a conductive film layer, the problem of excessive thickness of the carrier tape can be effectively reduced, and the thickness of the conductive film layer of the carrier tape can be reduced from 80μm to 100μm to 5μm to 8μm. It is not only a physical thinning of the size, but also promotes the transition of electronic packaging to high density, flexibility, and intelligence. Through material innovation and process innovation, ultra-thin carrier tapes have opened a new era of adapting to future microelectronics and green manufacturing while improving efficiency and reducing costs. Three-layer co-extrusion requires a multi-layer co-extrusion die head and precise melt flow rate control, while single-layer extrusion only requires an ordinary extruder, with lower equipment investment and maintenance costs. Three-layer co-extrusion requires that the substrate layer and the conductive layer materials have similar melting temperatures, otherwise stratification or interface defects are likely to occur; while single-layer extrusion only requires the selection of a single substrate, and the conductive layer is achieved by coating, making material selection more flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0055] Figure 1It is a schematic structural diagram of the carrier tape provided by an embodiment of the present application;

[0056] Figure 2 It is a schematic flow diagram of the preparation method of the carrier tape provided by an embodiment of the present application.

[0057] Among them, the reference numerals in the attached drawings:

[0058] 10. Substrate layer; 20. Conductive film layer. Detailed implementation manners

[0059] In the following description, for the purpose of illustration rather than limitation, specific details such as specific system structures and technologies are proposed to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the embodiments of the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the embodiments of the present application.

[0060] It should also be understood that the term "and / or" used in the specification of the embodiments of the present application and the appended claims refers to any combination and all possible combinations of one or more of the related listed items, and includes these combinations.

[0061] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0062] It should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the embodiments of the present application.

[0063] In addition, in the description of the specification of the embodiments of the present application and the appended claims, the terms "first", "second", "third", etc. are only used for distinguishing descriptions, and cannot be understood as indicating or implying relative importance.

[0064] As described in the specification of the embodiments of the present application with reference to "some embodiments" or "some embodiments", etc., it means that in one or more embodiments of the embodiments of the present application, specific features, structures or characteristics described in connection with that embodiment are included. Thus, the statements "in some embodiments", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized. "Plurality" means two or more.

[0065] In the first aspect of the embodiments of the present application, a method for preparing a carrier tape is provided. As Figure 1 and Figure 2 shown, the method includes the following steps:

[0066] S10. Prepare a base material layer 10 and a conductive liquid;

[0067] S20. Coat the conductive liquid on at least one side of the base material layer 10;

[0068] S30. Dry the conductive liquid coated on the base material layer 10 to form a conductive film layer 20 adhered to the base material layer 10.

[0069] In the method for preparing a carrier tape provided by the embodiments of the present application, compared with the existing three-layer co-extrusion preparation process which results in a relatively high thickness of the conductive film layer, there are problems of carbon deposition and surface particles in the carrier tape products formed by the co-extrusion process. By first preparing a single-layer base material layer and then coating the conductive liquid on both sides of the base material layer to form a conductive film layer, the problem of excessive thickness of the carrier tape can be effectively reduced. The thickness of the conductive film layer of the carrier tape can be reduced from 80 μm to 100 μm to 5 μm to 8 μm. This is not only a physical reduction in size, but also promotes the transition of electronic packaging to high density, flexibility and intelligence. Through material innovation and process innovation, while improving efficiency and reducing costs, the ultra-thin carrier tape opens a new era for adapting to future microelectronics and green manufacturing. Three-layer co-extrusion requires a multi-layer co-extrusion die head and precise melt flow rate control, while single-layer extrusion only requires an ordinary extruder, and the equipment investment and maintenance costs are lower. Three-layer co-extrusion requires that the base material layer and the conductive layer materials have similar melting temperatures, otherwise delamination or interface defects are likely to occur; while single-layer extrusion only requires selecting a single base material, and the conductive layer is realized by coating, and the material selection is more flexible.

[0070] In applications, the cost and process complexity of the method for preparing the carrier tape provided by the embodiments of the present application are reduced, the process is simplified, and the material compatibility is better. Moreover, the conductive liquid is coated on both sides of the substrate layer, and the conductive liquid formulations on both sides can be independently controlled (such as carbon-based conductive liquid and metal oxide conductive liquid) to achieve different surface resistances. It can also effectively ensure the thickness uniformity of the conductive film layers on both sides. The coating process (such as microgravure coating) can achieve precise control of the thickness of the conductive layer, while the thickness of the conductive layer formed by three-layer coextrusion is limited by the melt rheological properties and is prone to fluctuations.

[0071] In some embodiments, preparing the substrate layer includes: providing the preparation materials for the substrate layer and performing single-layer extrusion on the preparation materials to obtain the substrate layer. In applications, the substrate layer in step S10 is obtained by single-layer extrusion. In addition, the waste materials from three-layer coextrusion need to be classified and recycled according to multiple materials, while the waste materials of single-layer substrates can be directly reused. Modern coating processes tend to use water-based conductive liquids, and the VOC emissions are reduced by more than 70% compared with traditional solvent-based coatings. The preparation materials for the substrate layer include, but are not limited to, at least one of acrylonitrile-butadiene-styrene copolymer (ABS), polystyrene (PS), high-impact polystyrene (HIPS), and polycarbonate (PC). By reasonably selecting the substrate materials, the mechanical properties, environmental adaptability, and economy of the carrier tape can be optimized to meet the diverse needs of electronic packaging. Considering cost as a priority, PS or HIPS can be selected, which is suitable for low-value components and mild environments; for higher impact resistance requirements, ABS or HIPS can be selected, which is suitable for automotive or industrial electronics. For higher temperature resistance requirements, PC can be used to ensure stability under high-temperature processes; for transparent detection requirements, PS or PC can be used, and the selection can be based on the temperature resistance requirements. In one embodiment, the process parameters of single-layer extrusion include: the extruded material is PET (intrinsic viscosity 0.65 - 0.85 dL / g), the extrusion temperature is 260 - 280 °C, and the thickness is 200 - 300 μm. A three-roll calender (roll temperature 20 - 40 °C) controls the crystallinity (30% - 35%) to ensure the dimensional stability of the substrate.

[0072] In some embodiments, the conductive liquid includes carbon nanotubes, a combined dispersant, a matrix resin, nitrile rubber, and water; wherein the combined dispersant includes polyvinylpyrrolidone and polyethylene glycol; the matrix resin includes polyurethane resin and polyurethane epoxy resin.

[0073] The conductive liquid provided by the embodiments of the present application systematically solves the problems of uneven dispersion, poor mechanical properties, and pollution of traditional conductive liquids through the efficient dispersion of CNTs, the rigid-flexible synergy of the resin matrix, and the environmental protection advantages of the aqueous system. Through mechanisms such as adsorption-steric hindrance dispersion, interpenetrating network construction, and interface optimization among the components, the unity of conductivity, durability, and environmental friendliness is achieved, which is applicable to the field of high-precision electronic packaging.

[0074] In applications, carbon nanotubes serve as conductive fillers. CNTs form a three-dimensional conductive network through mutual overlap, endowing the conductive liquid with conductivity; the high aspect ratio and strength of CNTs effectively improve the tensile strength and wear resistance of the conductive film layer prepared from the conductive liquid. However, carbon nanotubes are prone to agglomeration due to van der Waals forces, resulting in uneven dispersion and unstable conductivity; therefore, dual-mechanism dispersion is achieved through a combination of dispersants, greatly improving the dispersibility of carbon nanotubes. Among them, PVP (chemical adsorption) and PEG (physical steric hindrance) complement each other to form a double protective layer, realizing the long-term stable dispersion of CNTs; PVP increases the viscosity of the system to prevent sedimentation, and PEG appropriately reduces the viscosity for easy coating, and the balance between the two realizes the fluidity at high solid content.

[0075] In applications, nitrile rubber is beneficial to enhancing the toughening and tear resistance of the conductive film layer prepared using the conductive liquid. The high elasticity of nitrile rubber (NBR) and the flexibility of polyurethane resin (PU) act synergistically to improve the tear strength of the film layer and prevent cracks from occurring during the high-speed curling or bending of the carrier tape. The elastic network of NBR disperses external stress, reducing the fracture of the carbon nanotube (CNTs) conductive network caused by mechanical shock and maintaining conductive stability. In addition, it is beneficial to optimize the interfacial bonding and adhesion between the substrate layers of the conductive film layer.

[0076] The cyano group (-CN) of NBR forms hydrogen bonds or dipole interactions with the urethane group (-NHCOO-) and epoxy group of PU, enhancing the adhesion between the resin matrix and the carrier tape substrate. The elastic segment of NBR partially wraps CNTs, reducing the interfacial defects between CNTs and the resin and improving the continuity of the conductive network.

[0077] In applications, the pyrrolidone ring of polyvinylpyrrolidone (PVP) in the combined dispersant undergoes π-π conjugate adsorption on the surface of CNTs to form a coating layer, reducing the surface energy and inhibiting the agglomeration of carbon nanotubes; in this way, the dispersion efficiency of CNTs in water can be effectively improved, the sedimentation rate of CNTs can be reduced, and the storage period of the conductive liquid can be extended. The mechanism of action of polyethylene glycol is that long-chain PEG molecules are adsorbed on the surface of CNTs, preventing re-agglomeration through physical spatial isolation. The hydrophilicity of PEG enhances the compatibility between CNTs and the aqueous system and reduces the interfacial tension. In this way, the dispersion stability of CNTs is maintained during dynamic shear (such as the coating process), and it synergistically reduces the viscosity of the dispersion system with PVP, improving the coating uniformity.

[0078] In the application, compared with the single resin in the prior art, the main resin adopts polyurethane resin (PU) and polyurethane epoxy resin (PU-Epoxy). The polyurethane resin has good flexibility and adhesion. Its soft segments (such as polyether / polyester chains) endow the conductive liquid with elasticity. The resistance change of the film layer prepared with the conductive liquid is <5% after being bent 100,000 times. The polar groups (-NHCOO-) form hydrogen bonds with the PET substrate, and the prepared conductive film layer can stably adhere to the substrate. Moreover, it can also improve the film-forming property of the conductive liquid. The low surface tension promotes uniform spreading and reduces pinhole defects. The polyurethane epoxy resin can improve hardness and wear resistance. The epoxy groups crosslink to form a dense network, and the pencil hardness can reach 2H - 3H; it has good chemical resistance and can resist the erosion of acids, alkalis and organic solvents, and is suitable for the reflow soldering environment. The two have a synergistic effect. PU provides elastic buffering, and PU-Epoxy enhances rigidity. The two are blended to form an interpenetrating network, balancing anti-bending property and wear resistance; the fast film-forming property of PU and the slow crosslinking of PU-Epoxy complement each other, reducing internal stress and avoiding cracking. In the application, water is used as a solvent to replace organic solvents (such as NMP, DMF), and the VOC emission approaches zero. It interacts with the dispersant and resin through hydrogen bonds to maintain the stability of the system.

[0079] In some embodiments, the mass ratio of the main resin to nitrile rubber is (3 - 5):1. In a specific embodiment, the mass ratio of the main resin to nitrile rubber is 4:1. The main resin provides the basic mechanical properties of the film layer, such as hardness, wear resistance and adhesion. The addition of NBR (mass ratio 3 - 5:1) forms an elastic phase in the resin matrix, significantly improving the elongation at break and tear strength of the film layer, and preventing cracks from occurring in the carrier tape during dynamic bending. The high polar groups (-NHCOO-, epoxy group) of the main resin form hydrogen bonds with the oxygen-containing groups on the surface of CNTs, fixing the position of CNTs and maintaining the stability of the conductive path. The elastic network of NBR absorbs external stress, reducing the risk of the CNTs network breaking due to mechanical shock, and ensuring that the resistance fluctuation is <3%. At a ratio of 3 - 5:1, the viscosities of the resin and the rubber are matched, and the viscosity of the mixed system is moderate, which is suitable for slit coating or spraying processes.

[0080] In some embodiments, the solid content of the nitrile rubber is 45% - 55%, preferably 50%. The NBR emulsion with a solid content of 45% - 55% has a high concentration of rubber particles, ensuring the uniform dispersion of the rubber phase in the conductive liquid and reducing sedimentation or flocculation during the storage period. The 50% solid content has both high stability and low viscosity, facilitating dilution to the target concentration. The NBR emulsion with a 50% solid content has a moderate particle size, is easy to form an interpenetrating network (IPN) with the resin matrix, and enhances the interfacial bonding force. An appropriate amount of NBR particles coat CNTs, reducing interfacial defects and improving the continuity of the conductive network.

[0081] In some embodiments, the mass ratio of carbon nanotubes to the combined dispersant is (0.5-1): (0.5-1). In a preferred embodiment, the mass ratio of carbon nanotubes to the combined dispersant is 1:1. In this way, when the dispersant ratio is high, the surface of CNTs can be fully covered, and aggregation can be inhibited by the dual effects of adsorption (PVP) and steric hindrance (PEG). However, excessive dispersant may occupy the volume of the system, dilute the concentration of CNTs, and reduce the density of the conductive network. When the dispersant ratio is low, it may lead to insufficient coverage of the CNTs surface and decreased dispersion stability (easy to re-agglomerate), but the CNTs concentration is higher and the potential for improving conductivity is great.

[0082] In application, experimental and theoretical analysis show that the mass ratio of CNTs to dispersant of 1:1 is the optimal balance point for comprehensive performance. First, the total amount of PVP and PEG is sufficient to completely cover the surface of CNTs to form a single layer or multilayer adsorption to ensure dispersion stability. Secondly, it can ensure the efficient construction of the conductive network. At a ratio of 1:1, the dispersant can prevent CNTs from agglomerating without excessively hindering their contact. CNTs form a continuous conductive path through "point-surface" or "line-line" overlap, and the percolation threshold is significantly reduced. In addition, at a ratio of 1:1, the total solid content of dispersant and CNTs is moderate, and the system viscosity is controlled at 50-200mPa·s (25℃), which is suitable for slit coating or micro-gravure coating process to ensure the uniformity of the film layer (thickness deviation <5%). CNTs are relatively expensive, and dispersants (PVP and PEG) are relatively cheap. While ensuring performance, the 1:1 ratio can avoid excessive use of high-priced CNTs or dispersants.

[0083] In some embodiments, in the combined dispersant, the mass ratio of polyvinyl pyrrolidone to polyethylene glycol is (1-3):1. In a specific embodiment, the mass ratio of PVP to PEG can also be any ratio within the range of (1-3):1, such as 1:1, 2:1, 3:1, 3:2, etc. Since PVP and PEG have different dispersion mechanisms for CNTs, PVP is chemical adsorption, and PEG is a physical steric hindrance, the different ratios between the two also reflect the balance between adsorption coverage and steric hindrance, wherein when PVP and PEG are equal in amount, the adsorption coverage and steric hindrance are balanced, which is suitable for low CNTs concentration. When the proportion of PVP increases, chemical adsorption and charge repulsion are enhanced, which is suitable for high CNTs loading and makes up for the lack of PEG steric hindrance. When PVP is dominant, the adsorption layer is denser and the short-term dispersion efficiency is high, but excessive PVP may increase the viscosity due to molecular chain entanglement, affecting the coating uniformity. With the assistance of PEG, the steric hindrance is enhanced, and the long-term stability of the dispersion system is better (no sedimentation after standing for 6 months), but a higher PEG dosage may sacrifice conductivity.

[0084] On the other hand, it is also reflected in the compatibility with the resin matrix. When the proportion of PVP is high, the polar groups of PVP form hydrogen bonds with the -NHCOO- groups of the polyurethane resin, enhancing the interfacial adhesion. However, excessive PVP may hinder resin crosslinking. When the proportion of PEG is low, the hydrophilic effect of PEG is reduced, avoiding resistivity fluctuations caused by moisture absorption in the film layer.

[0085] In some embodiments, the molar ratio of isocyanate groups to hydroxyl groups contained in the polyurethane resin is 1:(0.5 - 0.8). In specific embodiments, the molar ratio of isocyanate groups to hydroxyl groups contained in the polyurethane resin can be any value within the range of 1:(0.5 - 0.8), such as 1:0.5, 1:0.6, 1:0.7, 1:0.8, etc. When NCO is in excess, the hydroxyl groups (OH) of polyols (such as polyether / polyester diols) react preferentially with isocyanates (such as TDI, MDI) to form prepolymers with terminal -NCO groups; the remaining NCO groups in the prepolymers can further react with water (moisture curing), amine chain extenders or hydroxyl compounds to form a three-dimensional crosslinked network. Regarding the interaction with CNTs, the excess NCO groups can react with the oxygen-containing groups (such as -COOH, -OH) on the surface of CNTs to form chemical bonds (such as urea bonds), enhancing the filler-resin interfacial binding force and reducing the risk of the conductive network breaking due to stress. Regarding the blendability with polyurethane epoxy resin, the terminal -NCO groups of the prepolymer react with the hydroxyl or epoxy groups in the epoxy resin to form an interpenetrating network, synergistically improving the hardness and toughness of the film layer.

[0086] In some embodiments, the elongation rate of the polyurethane resin is 300% - 500%. In specific embodiments, the elongation rate of the polyurethane resin can be any value within the range of 300% - 500%, such as 300%, 350%, 400%, 450%, 500%, etc. The high elongation rate (300% - 500%) endows the resin matrix with excellent elastic deformation ability, ensuring that no cracks occur in the conductive film layer during repeated curling of the carrier tape (the number of bending times > 100,000 times), and the resistance change rate < 5%. The flexible chain segments (such as polyether soft segments) absorb mechanical stress, preventing the CNTs network from breaking due to external force and maintaining the integrity of the conductive path. The lower limit (300%), below this value, the film layer is prone to brittle fracture and cannot pass the dynamic bending test of the carrier tape; the upper limit (500%), an overly high elongation rate may sacrifice hardness, resulting in insufficient wear resistance.

[0087] In some embodiments, the hydroxyl value of the polyurethane resin is 80 mgKOH / g to 120 mgKOH / g. In specific embodiments, the hydroxyl value of the polyurethane resin is any value within the range of 80 mgKOH / g to 120 mgKOH / g, such as 80 mgKOH / g, 90 mgKOH / g, 100 mgKOH / g, 110 mgKOH / g, 120 mgKOH / g, etc. In this way, the crosslinking density in the resin can be regulated. The hydroxyl value determines the content of active hydroxyl groups (-OH) in the resin, directly affecting the reaction degree with the curing agent (such as isocyanate); a low hydroxyl value (80 mgKOH / g) results in a low crosslinking density, with a soft film layer but weak solvent resistance; a high hydroxyl value (120 mgKOH / g) leads to a high crosslinking density, an increase in hardness (pencil hardness ≥ 2H), and enhanced chemical resistance. Interface bonding optimization: An appropriate amount of hydroxyl groups form hydrogen bonds with the oxygen-containing groups (such as -COOH) on the surface of CNTs, enhancing the filler-resin interface bonding force (peel strength > 1.5 N / mm). 80 - 120 mgKOH / g can achieve the best balance between flexibility (elongation) and hardness (abrasion resistance), avoiding extreme values of a single property.

[0088] In some embodiments, the solid content of the conductive liquid is 2% to 3%. In specific embodiments, the solid content of the conductive liquid can be any value within the range of 2% to 3%, such as 2%, 2.2%, 2.5%, 2.6%, 2.8%, 3%, etc. A low solid content ensures that the viscosity of the conductive liquid is moderate, suitable for slot coating or gravure coating, forming an ultrathin and uniform film layer. When the water or solvent content is high, the hot air drying time at 80 - 120°C is short (1 - 3 minutes), avoiding damage to the PET substrate at high temperatures. Solid content > 3%: Excessively high viscosity leads to uneven coating and is prone to "orange peel" defects; solid content < 2%: The concentration of CNTs is too low to form a continuous conductive network.

[0089] In some embodiments, the solid content of the polyurethane resin is 35% to 40%. In specific embodiments, the solid content of the polyurethane resin is any value within the range of 35% to 40%, such as 35%, 36%, 37%, 38%, 39%, 40%, etc. Ensuring that the solid content of the polyurethane resin is within this range is beneficial for improving storage stability. High-solid-content resins (35% - 40%) reduce the transportation and storage volume and lower the risk of microbial growth (aqueous system). Dilute as needed during use (such as diluting with water at a ratio of 1:10 to 1:15), precisely controlling the total solid content of the conductive liquid (2% - 3%) to ensure batch consistency. Solid content < 35%: The resin emulsion is prone to stratification, and frequent stirring is required, increasing energy consumption; solid content > 40%: The viscosity of the emulsion is too high, making it difficult to pump and mix.

[0090] In some embodiments, the solid content of the polyurethane epoxy resin is 30% to 35%. In specific embodiments, the solid content of the polyurethane resin is any value within the range of 30% to 35%, such as 30%, 32%, 32%, 33%, 34%, 35%. The similar solid contents of the two resins are beneficial to improving the compatibility of the two-component system. Being close to the solid content of the polyurethane resin (35% to 40%), it ensures a uniform phase state when the two are blended and avoids film layer defects caused by phase separation. The reaction rate between the epoxy group and the polyurethane hydroxyl group is controllable. The solid content of 30% to 35% keeps the gel time within 10 to 30 minutes, which is suitable for the rhythm of the continuous coating production line. When the solid content < 30%, the hardness contributed by the epoxy resin is insufficient; when the solid content > 35%, the cross-linking is too fast, the internal stress increases, and the film layer is prone to warping.

[0091] In applications, the polyurethane (elongation rate of 300% to 500%) provides elasticity, and the polyurethane epoxy resin (solid content of 30% to 35%) imparts rigidity. The two are blended to form a "sea-island structure", enabling the film layer to pass both the 1H pencil hardness test and the 100,000 bending test. The hydroxyl value of the polyurethane (80 to 120 mgKOH / g) ensures moderate cross-linking with the epoxy resin. The shrinkage stress generated during the curing process prompts the CNTs to closely overlap, reducing the percolation threshold to 0.3 wt%. The high solid content of the resin (35% to 40%) ensures the stability of the raw materials, and the low solid content of the diluted conductive liquid (2% to 3%) realizes the unity of the coating processability and the thinness of the film layer. The elongation rate of 300% to 500% and the solid content of 30% to 35% of the epoxy resin complement each other in terms of rigidity and flexibility, resisting mechanical stress; the hydroxyl value of 80 to 120 mgKOH / g regulates the cross-linking density, taking into account both hardness and toughness; the solid content of 2% to 3% of the conductive liquid is suitable for thin-layer coating, while the solid content of 35% to 40% of the polyurethane ensures the stability of the raw materials. The synergy of this series of parameters systematically solves the pain points of traditional conductive liquids, such as easy brittleness, uneven resistance, and poor processability, providing a standardized technical framework for the manufacture of high-reliability carrier tapes.

[0092] In some embodiments, the mass ratio of the polyurethane resin to the polyurethane epoxy resin is (3 to 5):1. In specific embodiments, the mass ratio of the polyurethane resin to the polyurethane epoxy resin can be any ratio within the range of (3 to 5):1, such as 3:1, 4:1, 5:1. Among them, the PU dominates the flexibility. The soft segment of the polyurethane resin (PU) (such as the polyether chain) gives the film layer a high elongation rate (300% to 500%), enabling it to withstand repeated bending of the carrier tape without cracking, and at the same time providing strong adhesion to the substrate. The polyurethane epoxy resin forms a dense network through the cross-linking reaction of the epoxy group, improving the hardness, wear resistance, and chemical resistance of the film layer. The significance of the ratio range (3 to 5:1): When the PU-Epoxy ratio is higher, the hardness and wear resistance are better, which is suitable for high mechanical stress scenarios (such as industrial-grade carrier tapes); when the PU ratio is higher, the flexibility and adhesion are more prominent, which is suitable for high-frequency bending requirements (such as carrier tapes for consumer electronics).

[0093] In some embodiments, the conductive liquid includes a conductive agent and a host resin; wherein the conductive agent includes one of carbon nanotubes, carbon black, graphene, graphite, metal powder, metal nanowires, and conductive polymers; in the embodiments of the present application, carbon nanotubes (CNTs) are preferably used because carbon nanotubes have ultra-high conductivity and a low percolation threshold, and the intrinsic conductivity of CNTs can reach 10 3 ~10 6 S / cm (single-walled carbon nanotubes). Due to the high aspect ratio of CNTs (usually >1,000), only an addition amount of 0.5% to 3% is required to reach the conductive threshold (10% to 30% is required for other carbon-based materials). Example: The surface resistance of the conductive liquid with 1% CNT added can be as low as 10 2 ~10 3 Ω / sq, while 20% to 30% of carbon black needs to be added under the same resistance. It can effectively reduce the usage amount of the conductive agent and lower the material cost (especially when replacing precious metals such as silver powder); it can avoid the embrittlement of the coating or the decline of mechanical properties caused by high addition amounts.

[0094] In applications, carbon nanotubes have excellent mechanical reinforcement effects. The tensile strength of CNTs is as high as 50 to 200 GPa. After adding the conductive liquid, the tensile strength and flexibility of the coating can be significantly improved. The flexible structure of CNTs enables the conductive layer to maintain stable conductivity after repeated bending (such as flexible carrier tapes). The diameter of CNTs is only 1 to 50 nm, which is suitable for preparing ultra-thin conductive layers (such as 5 to 10 μm), while metal powders (micrometer-sized) or carbon black are prone to cause rough coatings due to their large particle sizes. CNTs can form an anisotropic conductive network through directional arrangement (such as electric field induction) to optimize the signal transmission path. The thermal conductivity of CNTs is as high as 3,000 W / (m·K), which can simultaneously improve the heat dissipation ability of the carrier tape. The CNT network can absorb electromagnetic waves (30 dB shielding effectiveness, 1 GHz frequency band) to protect sensitive components. The density of CNTs is only 1.3 to 1.5 g / cm 3 , which is more than 80% lighter than metal powder.

[0095] In some embodiments, the host resin includes at least one of polyurethane (PU), epoxy resin (Epoxy), polyester (PET), polyimide (PI), polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylic resin (Acrylic), polycarbonate (PC), and silicone resin (Silicone). Among them, polyurethane has excellent flexibility and elasticity, and is particularly suitable for tapes that require bending or dynamic applications. It has good compatibility with conductive agents (such as carbon-based materials), is easy to disperse, and has strong chemical resistance and wear resistance. Epoxy resin has high adhesion strength, excellent adhesion to tape substrates (such as PET, PC), and good high-temperature resistance (the glass transition temperature Tg can reach above 150 °C). It is suitable for high-temperature environments, has a low curing shrinkage rate, and the coating is uniform. Polyester resin has high mechanical strength, good dimensional stability, and excellent solvent resistance. It is suitable for solvent-based conductive liquid coating processes and has a low cost, making it suitable for large-scale production. Polyimide is resistant to ultra-high temperatures (long-term use temperature > 300 °C) and has a low coefficient of thermal expansion. Polyethylene and polypropylene are inexpensive, have good processing properties (high melt fluidity), and good moisture resistance and chemical corrosion resistance. Acrylic resin has high transparency and is suitable for tapes that require optical detection. Polycarbonate has high transparency and strong impact resistance. Silicone resin is resistant to high and low temperatures (-50 °C to 250 °C), has excellent flexibility, strong chemical inertness, and good aging resistance. Bio-based or biodegradable resins are environmentally friendly and biodegradable, meeting the trend of green manufacturing.

[0096] In some embodiments, the conductive liquid further includes a dispersant, and the dispersant includes, but is not limited to, polyvinylpyrrolidone, modified polyvinylpyrrolidone, etc. The presence of the dispersant can effectively improve the dispersion of carbon nanotubes in the conductive liquid, thereby improving the conductivity of the finally formed conductive film layer.

[0097] In some embodiments, coating the conductive liquid on at least one side of the substrate layer includes:

[0098] Coating the conductive liquid on both sides of the substrate layer respectively;

[0099] And drying the conductive liquid on the substrate layer to form a conductive film layer adhered to the substrate layer, including:

[0100] A conductive film layer is formed on both sides of the substrate layer to obtain an intermediate tape. The conductive film layers on both sides form a symmetric conductive network, avoiding local electrostatic accumulation caused by uneven charge distribution during single-sided conduction (especially in high-speed chip mounters, static electricity is easily generated due to the friction of the carrier tape). Synchronous coating and drying are carried out. A double-sided coater (such as a comma knife + reverse roll coating) can complete the coating of the conductive liquid on both sides at one time, and the efficiency is increased by 50% compared with single-sided coating in batches. The turning-over process is reduced, avoiding the turning-over and secondary positioning steps after single-sided coating, and the yield is increased by 2% - 3% (reducing human operation errors). The solvent recovery rate is increased. During double-sided coating, the front and back sides of the substrate are dried synchronously, and the solvent volatilization paths are symmetric, enabling efficient recovery (for example, the recovery rate of isopropanol is increased from 60% to 85%). Stress balance, suppressing warping deformation. The coefficient of thermal expansion of the conductive layers on both sides matches that of the substrate, avoiding warping of the carrier tape caused by thermal stress in the single-sided coating. The double-sided conductive layers improve the overall stiffness of the carrier tape and reduce vibration damage during transportation. The conductive film layer covers both sides of the substrate layer, avoiding direct mechanical friction on the surface of the substrate layer, and the wear-resistant life is extended by 2 - 3 times. In the double-sided coating process, the substrate is heated and pressed synchronously on both sides, and the peel strength between the conductive layer and the substrate is increased to ≥2.0 N / cm. The double-sided conductive film layer can control the surface resistance within 10 6 ~10 9 Ω / sq, ensuring the stable antistatic performance of the entire carrier tape.

[0101] In other embodiments, the conductive liquid is first coated on one side of the substrate layer, and then dried to form a conductive film layer adhered to one side of the substrate layer. Then, the conductive liquid is coated on the other side of the substrate layer and dried to form a conductive film layer adhered to the other side of the substrate layer. In other embodiments, coating the conductive liquid on at least one side of the substrate layer includes: coating the conductive liquid on one side of the substrate layer, and the conductive film layer on the other side of the substrate layer is prepared by extrusion. This can effectively ensure that conductive film layers can be formed on both sides of the substrate layer, simplify the preparation process, and effectively reduce the thickness of the entire carrier tape.

[0102] In some embodiments, before coating the conductive liquid on at least one side of the substrate layer, it further includes:

[0103] The surface of at least one side of the substrate layer is modified to increase the surface energy of the substrate layer, enhance the mechanical bite between the conductive film layer and the substrate layer, and avoid generating static electricity during the process of coating the conductive liquid. In application, the two sides of the substrate layer are respectively modified to facilitate coating the conductive liquid on both sides and reduce the static electricity generated during the coating process.

[0104] In some embodiments, the modification treatment includes any one of corona treatment, plasma treatment, flame treatment, ultraviolet ozone treatment, chemical treatment, and laser treatment. In a preferred embodiment, corona treatment is used to modify the surface of the substrate layer. The specific parameters of the corona treatment include a power density of 1 - 3 W / cm2 , the processing speed is 10 - 30 m / min, and the electrode spacing is 1 - 2 mm.

[0105] In applications, corona treatment physically and chemically modifies the surface of the substrate through high - voltage discharge (5 - 20 kV). Specifically, it includes: corona breaks the molecular chains on the surface of the substrate (such as PET), generating polar groups such as carboxyl (-COOH) and hydroxyl (-OH). The surface energy is increased from <30 mN / m to ≥45 mN / m; it improves the spreading property of the conductive liquid on the substrate, and the contact angle is reduced from >80° to <30°, avoiding pinhole or shrinkage defects during coating. Corona forms nano - scale grooves on the surface (the Ra value increases from 0.1 μm to 0.3 - 0.5 μm), enhancing the mechanical interlock between the conductive layer and the substrate, and the peel strength is increased by 30% - 50%; the ion wind generated by corona can neutralize the static electricity on the substrate surface (the surface voltage is reduced from >1000 V to <100 V), avoiding coating defects caused by electrostatic adsorption of dust during the coating process. Through the combination of corona treatment and coating process, the single - layer substrate solution shows significant advantages in terms of cost, performance, and environmental friendliness.

[0106] In applications, the modification treatment can also include plasma treatment, which uses ionized gases (such as oxygen, nitrogen, argon) to generate high - energy particles that bombard the material surface to generate active groups or etch the surface. It increases the surface energy (up to more than 70 mN / m) and improves wettability. Flame treatment oxidizes the material surface at high temperature through a gas flame (such as propane / air) to generate polar groups. It increases the surface energy and removes the weak boundary layer on the surface. Ultraviolet ozone treatment uses ultraviolet light (UV) to excite ozone (O3) to decompose into active oxygen atoms to oxidize the material surface. Chemical treatment corrodes or activates the surface through acids, alkalis, solvents, or oxidants. Laser treatment scans the material surface with a high - energy laser beam to change the surface morphology or chemical state through ablation or melting.

[0107] In some embodiments, the thickness of the conductive film layer is 5 - 8 μm. The thickness of the conductive film layer being 5 - 8 μm not only adapts to the trend of miniaturization and flexibility of electronic packaging, but also significantly reduces costs, improves reliability, and promotes green manufacturing through the coordinated optimization of materials, processes, and structures. Specifically, the thickness of the conductive film layer can be any value within the range of 5 - 8 μm, such as 5 μm, 6 μm, 7 μm, 8 μm, etc. The thickness of the conductive film layer greatly thins the thickness of the entire carrier tape, making it more suitable for miniaturized components and improving the packaging density. A conductive film layer thickness of 5 - 8 μm can be compatible with components with a size of 0.4×0.2 mm or even smaller, avoiding size deviation of the grooves due to an overly thick conductive layer. The thin conductive film layer reduces the electric field interference between adjacent components (, supporting a high - density packaging of 200 components / cm 2 The carbon nanotubes can form a continuous conductive network within a thickness of 5 - 8 μm, and the surface resistance can be controlled at 10 4 ~106 Ω / sq. The CNT only needs an addition amount of 1% - 3% to form a conductive path in the thin layer. The ultimate bending radius of the 5 - 8μm conductive layer can reach 1mm, which is suitable for the roll - to - roll production process of flexible electronics (such as the component packaging of foldable screen mobile phones). The thermal expansion coefficient of the conductive film layer and the substrate (layer) is more matched. Under the temperature change of - 40°C to 125°C, the interfacial peeling force remains at ≥1.2N / cm. The thin conductive film layer can adopt the micro - gravure coating or slit extrusion process, and the coating speed is increased to 50 - 100m / min, and the drying time is shortened by 30% - 50%. The thickness uniformity is controlled within ±0.2μm, and defects such as pinholes and shrinkage holes are reduced by 70%.

[0108] In some embodiments, the preparation method further includes: S40, performing thermoforming on the intermediate strip to obtain a carrier tape. The conductive film layer and the substrate layer are subjected to thermoforming to obtain the final finished carrier tape, and then it is cut according to needs. The carrier tape provided by this application uses the process of double - sided coating instead of three - layer co - extrusion to prepare the carrier tape sheet, which can effectively solve the problems of large thickness of the conductive film layer in the carrier tape sheet, surface decarburization, and surface particles. The finally obtained carrier tape has a significantly thinner conductive film layer, a uniform surface, and no particles.

[0109] The embodiment of this application also provides a carrier tape, as Figure 1 shown. The carrier tape is prepared by using the preparation method described in the first aspect. The carrier tape includes a substrate layer 10 and conductive film layers 20 adhered to both sides of the substrate layer 10. The carrier tape prepared by using the method described in the first aspect has all the beneficial effects described in the first aspect.

[0110] Preparation Example

[0111] Preparation Example 1

[0112] This preparation example provides a conductive liquid, and the relationship between the components of the conductive liquid is shown in the following table:

[0113] Table 1 Weight and solid content ratio relationship of each component in Preparation Example 1

[0114] Project Total mass Solid content Proportion of solid content Carbon nanotube slurry 1195.7g 41.85g 3.5％ Polyurethane 135g 54g 40％ Polyurethane epoxy resin 27g 9.45g 35％ Nitrile rubber 40.5g 20.25g 50％

[0115] Among them, the mass ratio of carbon nanotubes to the combined dispersant is 1:1; in the combined dispersant, the mass ratio of PVP to PEG is 3:1.

[0116] It should be noted that before use, 10% by mass of isopropanol and water of the conductive liquid need to be added, mixed evenly and then added to the conductive liquid, stirred and mixed, and left to defoam before use.

[0117] Preparation Example 2

[0118] This preparation example provides a conductive liquid, which is basically the same as that in Example 1, except that the usage amounts of each component are different, as shown in the following table:

[0119] Table 2 Weight and solid content ratio relationship of each component in Preparation Example 2

[0120] Project Total mass Solid content Proportion of solid content Carbon nanotube slurry 500g 18g 3.6％ Polyurethane 128.6g 45g 35％ Polyurethane epoxy resin 30g 9g 30％ Nitrile rubber 30g 15g 50％

[0121] Among them, the mass ratio of carbon nanotubes to the combined dispersant is 1:1; in the combined dispersant, the mass ratio of PVP to PEG is 3:1.

[0122] Preparation Example 3

[0123] This preparation example provides a preparation method of a conductive liquid, and its preparation method is basically the same as that in Example 1, except that the usage amounts of each component are different, as shown in the following table:

[0124] Table 3 Weight and solid content ratio relationship of each component in Preparation Example 3

[0125] Project Total mass Solid content Proportion of solid content Carbon nanotube slurry 800g 28g 3.5％ Polyurethane 90g 31.5g 35％ Polyurethane epoxy resin 30g 10.5g 35％ Nitrile rubber 17.5g 7g 40％

[0126] Among them, the mass ratio of carbon nanotubes to the combined dispersant is 1:1; in the combined dispersant, the mass ratio of PVP to PEG is 3:1.

[0127] Example

[0128] Example 1

[0129] This application example provides a carrier tape and its preparation method. The preparation method of the carrier tape includes the following steps:

[0130] S10. Provide a substrate layer and the conductive liquid prepared in Preparation Example 1; among them, the solid content of the conductive liquid is 2.5%;

[0131] S20. Coat the conductive liquid prepared in Preparation Example 1 on both sides of the substrate layer;

[0132] S30. Dry the conductive liquid coated on the substrate layer to form a conductive film layer adhered to both sides of the substrate layer, and obtain an intermediate strip, where the thickness of the conductive film layer is 6 μm;

[0133] S40. Perform thermoforming stamping on the intermediate strip to obtain a carrier tape sheet.

[0134] Example 2

[0135] It is basically the same as that in Example 1, except that the conductive liquid used is the conductive liquid prepared in Preparation Example 2, the solid content of the conductive liquid is 3%, and the thickness of the conductive film layer is 8 μm.

[0136] Example 3

[0137] It is basically the same as Example 1, except that the conductive liquid used is the conductive liquid prepared in Preparation Example 3, the solid content of the conductive liquid is 2%, and the thickness of the conductive film layer is 5 μm.

[0138] Performance Test

[0139] The following performance tests were carried out on the carrier tapes prepared in Examples 1 to 3:

[0140] T - Peel Strength Measurement: A peel tester was used to measure the T - peel strength of the conductive film layer on the substrate.

[0141] The test temperature was 23 ± 2 °C and the relative humidity was 50 ± 5%. The instrument was set at a peel speed of 300 mm / min and a peel angle of 180°. The test results are shown in Table 4:

[0142] Table 4 Test Results of the Carrier Tapes Prepared in Examples 1 to 3

[0143]

[0144] The carrier tape provided in the embodiment of the present application has a uniform surface without color difference, particles, matte appearance, oil prints, oil flowers, and color change; it has a permanent anti - static effect, excellent mechanical properties, a peel force of 20 - 80 g, and no delamination during sealing.

[0145] In the above - mentioned embodiments, the descriptions of each embodiment have their own emphases. For parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0146] The above - mentioned embodiments are only used to illustrate the technical solutions of the embodiments of the present application, and are not intended to limit them; although the embodiments of the present application have been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the embodiments of the present application.

Claims

1. A method for preparing a carrier tape, characterized in that, It includes the following steps: Prepare a substrate layer and a conductive liquid; Coat the conductive liquid on at least one side of the substrate layer; Dry the conductive liquid coated on the substrate layer to form a conductive film layer adhered to the substrate layer.

2. The preparation method according to claim 1, characterized in that, The coating of the conductive liquid on at least one side of the substrate layer includes: Coat the conductive liquid on both sides of the substrate layer respectively; The drying of the conductive liquid coated on the substrate layer to form a conductive film layer adhered to the substrate layer includes: Form conductive film layers adhered to both sides of the substrate layer to obtain an intermediate strip.

3. The preparation method according to claim 1, characterized in that, Before coating the conductive liquid on at least one side of the substrate layer, it further includes: Perform surface modification on at least one side surface of the substrate layer to increase the surface energy of the substrate layer, enhance the mechanical interlocking between the conductive film layer and the substrate layer, and avoid generating static electricity during the process of coating the conductive liquid.

4. The preparation method according to claim 3, characterized in that, The surface modification includes any one of corona treatment, plasma treatment, flame treatment, ultraviolet ozone treatment, chemical treatment, and laser treatment.

5. The preparation method according to claim 1, characterized in that, The thickness of the conductive film layer is 5 - 8 μm.

6. The preparation method according to claim 1, wherein The conductive liquid includes carbon nanotubes, a combined dispersant, a main resin, nitrile rubber, and water; Wherein the combined dispersant includes polyvinylpyrrolidone and polyethylene glycol; The main resin includes polyurethane resin and polyurethane epoxy resin.

7. The preparation method according to claim 6, characterized in that, The mass ratio of the carbon nanotubes to the combined dispersant is (0.5 - 1):(0.5 - 1); And / or, the mass ratio of the main resin to the nitrile rubber is (3 - 5):

1.

8. The preparation method according to claim 6, characterized in that, Wherein the conductive agent includes one of carbon nanotubes, carbon black, graphene, graphite, metal powder, metal nanowire, and conductive polymer; The main resin includes at least one of polyurethane, epoxy resin, polyester, polyimide, polyethylene, polypropylene, polystyrene, acrylic resin, polycarbonate, and silicone resin; The material of the substrate layer includes one or more of acrylonitrile - butadiene - styrene copolymer, polystyrene, high - impact polystyrene, and polycarbonate.

9. The preparation method according to claim 2, wherein, The preparation of the substrate layer includes: Provide the preparation material of the substrate layer and perform single - layer extrusion on the preparation material to obtain the substrate layer; And / or, the method further includes: performing thermoforming stamping on the intermediate strip to obtain a carrier tape.

10. A carrier tape, characterized in that, Obtained by using the preparation method according to any one of claims 1 to 9, the carrier tape includes a substrate layer and conductive film layers adhered to both sides of the substrate layer.

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