Cover tape and preparation method thereof

Abstract

The embodiment of the invention provides a cover tape and a preparation method thereof. The preparation method of the cover tape comprises the following steps: preparing a base material layer and anti-static liquid; coating one side of the base material layer with the anti-static liquid; curing the anti-static liquid coated on the base material layer to form an anti-static film layer adhered to the base material layer; wherein the anti-static film layer is used for being bonded with the carrier tape and preventing static electricity from being generated when the cover tape is stripped from the carrier tape. According to the cover tape and the preparation method thereof, in addition, the anti-static layer and the heat-sealing layer need to be prepared for a traditional cover tape respectively, the anti-static layer and the heat-sealing layer are combined into a single layer in the new scheme, and the production procedures and the material cost are reduced. And secondly, the anti-static performance of the cover tape can be effectively improved, so that the cover tape is easier to strip the carrier tape, and parts cannot fly out along with the carrier tape due to generation of static electricity.

Description

Technical Field

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

[0002] The cover tape is usually called "cover film" or "encapsulation cover tape", and is an important material for protecting components during the encapsulation process of electronic components. The cover tape usually uses a polyester or polypropylene film as the base layer, and is compounded or coated with different functional layers (antistatic layer, adhesive layer, etc.). It can be sealed on the surface of the carrier tape under external force or heating to form a closed space to protect the electronic components in the carrier tape pocket.

[0003] The cover tape is mainly applied to the electronic component mounting industry. It is used in conjunction with a carrier tape (carrier tape) to carry and store electronic components such as resistors, capacitors, transistors, and diodes in the pockets of the carrier tape. The cover tape is sealed above the pockets formed by the carrier tape to form a closed package, which is used to protect the electronic components from being contaminated and damaged during transportation. However, the current cover tape is prone to generating static electricity, especially when the cover tape is peeled off from the carrier tape, which easily causes the problem that electronic components adhere to the cover tape and fly out. Summary of the Invention

[0004] In view of this, embodiments of this application provide a cover tape and a preparation method thereof to solve the technical problem that the existing cover tape is prone to generating static electricity, especially when the cover tape is peeled off from the carrier tape, which easily causes the problem that electronic components adhere to the cover tape and fly out.

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

[0006] Preparing a base material layer and an antistatic liquid;

[0007] Coating the antistatic liquid on one side of the base material layer;

[0008] Curing the antistatic liquid coated on the base material layer to form an antistatic film layer adhered to the base material layer;

[0009] Wherein, the antistatic film layer is used for bonding with the carrier tape and preventing static electricity from being generated when the cover tape is peeled off from the carrier tape.

[0010] In some embodiments, the antistatic liquid includes the following components in parts by weight:

[0011] 1 - 3 parts of carbon nanotubes;

[0012] 1 - 3 parts of dispersant;

[0013] 10 - 30 parts of resin matrix;

[0014] 0.1 - 0.6 parts of compatibilizer.

[0015] In some embodiments, the carbon nanotubes include single-walled carbon nanotubes.

[0016] In some embodiments, the carbon nanotubes include single-walled carbon nanotubes and multi-walled carbon nanotubes, and the mass percentage of the single-walled carbon nanotubes is greater than or equal to 60%.

[0017] In some embodiments, the resin matrix includes at least one of ethylene-vinyl acetate copolymer, polyolefins, polyurethane, and hot melt adhesives.

[0018] In some embodiments, the solid content of the antistatic liquid is 1.5% - 3%.

[0019] In some embodiments, the solid content of the resin matrix is 25% - 35%.

[0020] In some embodiments, before coating the antistatic liquid on one side of the substrate layer, the surface of the substrate layer is corona-treated to increase the adhesion of the substrate layer and facilitate the adhesion of the antistatic liquid to the substrate layer.

[0021] In some embodiments, the thickness of the substrate layer is 20 - 50 μm.

[0022] In some embodiments, the thickness of the antistatic film layer is 5 - 20 μm.

[0023] In some embodiments, after curing the antistatic liquid coated on the substrate layer to form an antistatic film layer adhered to the substrate layer and obtaining an intermediate strip, the following steps are further included:

[0024] Slitting and inspecting the intermediate strip to obtain a cover tape with a preset specification and meeting the standards.

[0025] In some embodiments, the material of the substrate layer includes at least one of polyethylene terephthalate, polyethylene, polypropylene, and thermoplastic elastomer.

[0026] In a second aspect, an embodiment of the present application provides a cover tape prepared by using the preparation method described in the first aspect. The cover tape includes a substrate layer and an antistatic film layer provided on one side of the substrate layer. The antistatic film layer is used for bonding with a carrier tape and preventing static electricity from being generated when peeling off from the carrier tape.

[0027] The cover tape and its preparation method provided by the embodiments of the present application combine the anti-static layer and the heat-sealing layer in the traditional cover tape into a double layer, solving the problems of complex structure, unstable anti-static performance, high cost, etc. of the traditional cover tape. At the same time, the mechanical strength and process efficiency are improved, and it is applicable to high-demand scenarios such as the packaging of precision electronic components. Specifically, the material composite of the anti-static function and the heat-sealing bonding function is achieved breakthroughly, and the interfacial defects between layers are eliminated, effectively improving the interfacial bonding strength, and the film layer thickness is greatly reduced; the coating process is reduced, the curing energy consumption is reduced, and the production rhythm is improved. Brief Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 is a schematic structural diagram of a cover tape in the prior art;

[0030] Figure 2 is a schematic structural diagram of the cover tape provided by the embodiments of the present application;

[0031] Figure 3 is a schematic flow chart of the preparation method of the cover tape provided by the embodiments of the present application.

[0032] Among them, the attached reference numerals:

[0033] 10. Substrate layer; 20. Anti-static layer; 30. Heat-sealing layer; 100. Anti-static film layer. Detailed Embodiments

[0034] 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, the 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.

[0035] It should also be understood that the term " / and / " 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 associated listed items, and includes these combinations.

[0036] It should be noted that when an element is referred to as "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 "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0037] 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 should not be construed as a limitation to the embodiments of the present application.

[0038] 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.

[0039] The reference to "some embodiments" or "some embodiments" etc. in the description of the specification of the embodiments of the present application means that a specific feature, structure or characteristic described in connection with the embodiment is included in one or more embodiments of the embodiments of the present application. Thus, the statements "in some embodiments", "in some embodiments", "in other some embodiments", "in still other some embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiments, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in another way. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in another way. "A plurality" means two or more.

[0040] As Figure 1 shown, the cover tape of the prior art includes a base material layer 10, an anti-static layer 20, and a heat-sealing layer 30 that are sequentially stacked. The heat-sealing layer 30 is used to bond with the carrier tape to realize the connection between the cover tape and the carrier tape, and the anti-static layer 20 is used to prevent static electricity generated when the cover tape is peeled off from the carrier tape.

[0041] However, due to the complex structure of the cover tape in the prior art, the interface between layer structures may fail, specifically including: the risk of interlayer peeling, that is, due to the difference in material polarity among the functional layers (substrate / antistatic layer / heat-sealing layer) (such as poor compatibility between the surface tension of the substrate PET and the resin in the antistatic layer), the interface bonding strength is low, and delamination is likely to occur under high-speed peeling or humid and hot environments. In addition, the electrostatic protection efficiency is limited. The traditional antistatic layer relies on migratory antistatic agents, and the surface resistivity increases in a low-humidity environment. The peeling static voltage can reach 500 - 800V (far exceeding the <100V required by the JESD625-A standard).

[0042] Based on this, the embodiments of the present application provide a cover tape and a preparation method thereof, which combine an antistatic layer and a heat-sealing layer to form an antistatic film layer. As Figure 2 shown, that is, the cover tape includes a substrate layer and an antistatic film layer provided on the substrate layer. Carbon nanotubes are innovatively added to the EVA resin to endow it with antistatic performance. At the same time, single-walled carbon nanotubes are mainly used for the carbon nanotubes, which does not affect the transparency and ensures the transparency of the cover tape.

[0043] It should be noted that the following is the Chinese-English abbreviation correspondence relationship:

[0044] Polyethylene terephthalate - PET, polyethylene - PE, polypropylene - PP, thermoplastic elastomer - TPE; CNT / CNTs - carbon nanotubes, MWCNT - multi-walled carbon nanotubes, SWCNT - single-walled carbon nanotubes; EVA - ethylene-vinyl acetate copolymer; VA - vinyl acetate; PVP - polyvinylpyrrolidone; PEG - polyethylene glycol.

[0045] In the first aspect of the embodiments of the present application, a preparation method of a cover tape is provided. As Figure 3 shown, it includes:

[0046] S10. Prepare a substrate layer and an antistatic liquid;

[0047] S20. Coat the antistatic liquid on one side of the substrate layer;

[0048] S30. Cure the antistatic liquid coated on the substrate layer to form an antistatic film layer adhered to the substrate layer;

[0049] Among them, the antistatic film layer is used for bonding with the carrier tape and preventing static electricity from being generated when the cover tape is peeled off from the carrier tape.

[0050] The traditional process for preparing cover tapes includes: substrate preparation → antistatic layer coating → heat-sealing layer coating → two curing processes → composite processing. The method for preparing cover tapes provided in the embodiments of the present application is: substrate preparation → composite functional layer coating → single curing → finished product, which effectively simplifies the preparation process of cover tapes, combines the antistatic layer and the heat-sealing layer in the traditional cover tape into one layer, solves the problems of complex structure, unstable antistatic performance, and high cost of traditional cover tapes, and at the same time improves the mechanical strength and process efficiency, and is suitable for high-requirement scenarios such as the encapsulation of precision electronic components. Specifically, it breaks through to achieve the material composite of antistatic function and heat-sealing bonding function, eliminates the interfacial defects between layers, effectively improves the interfacial bonding strength, and greatly reduces the film layer thickness; the coating process is reduced, the curing energy consumption is reduced, and the production rhythm is improved.

[0051] In some embodiments, the antistatic liquid comprises the following components in parts by weight:

[0052] 1-3 parts of carbon nanotubes;

[0053] 1-3 parts of dispersant;

[0054] 10-30 parts of resin matrix;

[0055] 0.1-0.6 parts of compatibilizer.

[0056] In application, through the precise design of the component ratio, this formula achieves the optimal balance among electrical conductivity, mechanical strength, and processing performance, uses the two-component synergy of "dispersant - compatibilizer" to solve the problems of carbon nanotube dispersion and interface, and realizes ultra-thin coating through the rheological control of the resin matrix, and maintains stable electrical conductivity with a low carbon nanotube content.

[0057] In application, carbon nanotubes are used to construct a three-dimensional conductive network, and charge rapid dissipation is achieved through the electron tunneling effect between nanotubes. The dispersant reduces the surface energy of carbon nanotubes and controls the slurry viscosity through the steric hindrance / electrostatic stabilization mechanism (commonly polyvinylpyrrolidone). Further, the carbon nanotubes include single-walled carbon nanotubes, which have high electrical conductivity and high specific surface area, and can form a conductive network at a low addition amount to quickly conduct away static charges.

[0058] In some embodiments, the carbon nanotubes include single-walled carbon nanotubes and multi-walled carbon nanotubes, and the proportion of single-walled carbon nanotubes is greater than or equal to 60%. In specific applications, the mass proportion of single-walled carbon nanotubes in all conductive agents can be 60%, 65%, 70%, 80%, 90%, etc. In applications, single-walled carbon nanotubes have a higher aspect ratio and specific surface area (the diameter of single-walled tubes is about 1 - 2 nm, and that of multi-walled tubes is about 5 - 20 nm), and can form a continuous conductive network throughout the material at a lower addition amount. The carrier mobility of single-walled tubes is significantly higher than that of multi-walled tubes, providing a more efficient charge conduction path. When the proportion of SWCNT ≥ 60%, the conductive network is dominated by single-walled tubes, and the antistatic performance (surface resistivity) can be reduced by 1 - 2 orders of magnitude, which is especially suitable for the encapsulation of high-end electronic components sensitive to static electricity. Although the conductivity of multi-walled carbon nanotubes is slightly lower, their multi-layer structure endows higher mechanical strength and bending resistance. In a system dominated by SWCNT (≥ 60%), MWCNT (≤ 40%) can act as "bridges" and "support skeletons" to prevent the fracture of single-walled tubes caused by excessive bending or thermal stress. It can increase the tensile strength of the antistatic film layer by 20% - 30%, avoid the destruction of the conductive network caused by stress concentration during heat sealing or transportation of the film, and ensure the long-term stability of the antistatic performance.

[0059] In some embodiments, the resin matrix includes at least one of ethylene-vinyl acetate copolymer, polyolefins, polyurethanes, and hot melt adhesives. The resin matrix provides mechanical strength, controls the modulus, and forms chemical bonds / physical adsorption with the substrate (such as PET / PC), providing heat-sealing performance and controlling the peel strength (180° peel test). In a preferred embodiment, EVA resin is selected, which is beneficial to form an aqueous resin system, resulting in zero VOC emissions.

[0060] In applications, since carbon nanotubes are prone to agglomeration due to van der Waals forces, resulting in uneven dispersion and unstable conductivity; therefore, a dual-mechanism dispersion is carried out through a dispersant, which greatly improves the dispersion 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. The balance between the two realizes the fluidity at a high solid content.

[0061] In applications, the pyrrolidone ring of polyvinylpyrrolidone (PVP) in the dispersant undergoes π-π conjugated adsorption with the surface of CNTs, forming a coating layer that reduces the surface energy and inhibits the agglomeration of carbon nanotubes. This can effectively improve the dispersion efficiency of CNTs in water, reduce the sedimentation rate of CNTs, and extend the storage period of the antistatic liquid. The mechanism of action of polyethylene glycol is that long-chain PEG molecules adsorb 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, reducing the interfacial tension. In this way, the dispersion stability of CNTs is maintained during dynamic shearing (such as during the coating process), and it synergistically reduces the viscosity of the dispersion system with PVP, improving the coating uniformity.

[0062] In applications, EVA resin is used as the resin matrix. Optionally, polyolefin elastomers, thermoplastic polyurethanes, ethylene-methyl acrylate, polybutylene succinate, styrene-butadiene block copolymers, etc. can also be used. Among them, the vinyl acetate content of EVA resin is adjustable. The higher the VA content, the lower the melting temperature and the better the flexibility. During the heat sealing process (80 - 120 °C), EVA can quickly melt and bond with the surface of the carrier tape, forming a firm and uniform sealing interface with high heat sealing strength and a wide process window, which is suitable for high-speed automated packaging production lines. The amorphous region in the EVA molecular chain endows the material with high elasticity, making the coated film not easily crack when bent or folded, meeting the packaging requirements of flexible electronic components. The polarity of EVA (from the acetate group) can form hydrogen bonds or van der Waals forces with the surface of carbon nanotubes through a compatibilizer (such as maleic anhydride graft), reducing the agglomeration of the conductive agent and ensuring the uniform distribution of the conductive network. EVA has a low melt viscosity, is easy to mix with solvents and coat into films, and has a flat and defect-free surface after drying, which is suitable for roll-to-roll continuous production processes. EVA is a mature industrial material with a moderate price, and its performance can be optimized by adjusting the VA content, offering high cost performance; at the same time, it does not contain harmful substances such as halogens, meeting the environmental protection requirements of electronic packaging.

[0063] In some embodiments, the solid content of the antistatic liquid is 1% - 3%. In specific embodiments, the solid content of the antistatic liquid can be 1%, 1.5%, 2%, 2.5%, 3%, etc. The antistatic function is achieved with the lowest effective solid loading, while reducing the material and energy consumption costs. Dilution and mixing of the carbon paste and the resin: After the carbon paste (0.5% - 1.5%) and the resin matrix (25% - 35%) are mixed in proportion, the total solid content is diluted to 1% - 3%, ensuring that the proportion of the conductive agent in the final coating is 0.02% - 0.1% (sufficient to form a percolation network); the low solid content reduces the total amount of solvent volatilization, and the drying energy consumption is reduced by 30% - 40%.

[0064] In some embodiments, the solid content of the resin matrix is 25% - 35%. Controlling the solid content of the EVA resin within 25% - 35% and setting it at 30% in the preferred embodiment can optimize the coating quality, ensure a flat surface, uniform thickness, and no defects; improve processing efficiency, be suitable for high-speed continuous production, and reduce energy consumption; balance mechanical properties, have both strength and flexibility to meet heat-sealing requirements; control costs, with a moderate amount of materials used and high cost performance; and stabilize the conductive performance, with a continuous and efficient conductive network and excellent antistatic performance. In some embodiments, the solid content of the EVA resin is 25% - 35%. Relationship between the solid content and mechanical strength: When the solid content of the EVA resin is too low, i.e., the resin matrix is insufficient, the mechanical strength of the coating is low and it is prone to cracking or peeling; when there is too much resin matrix, it may lead to a decrease in flexibility and affect the heat-sealing performance. When the solid content of the EVA resin is within 25% - 35%, especially when the solid content is 30%, the ratio of the resin matrix to the conductive agent is appropriate, and the coating has both good mechanical strength (tensile resistance, puncture resistance) and flexibility; the heat-sealing performance is excellent, and the sealing interface is firm and uniform. In addition, when the resin matrix is insufficient to wrap the conductive agent, the conductive network is prone to breakage; while too much resin matrix may hinder the contact between the conductive agents and reduce the conductive efficiency. When the solid content of the EVA resin is within 25% - 35%, especially when the solid content is 30%, the ratio of the resin matrix to the conductive agent is optimal, the conductive network is continuous and stable; the antistatic performance is excellent, and the surface resistivity can be controlled within 6 -10 8 Ω / sq range.

[0065] In some embodiments, before coating the antistatic liquid on one side of the substrate layer, the surface of the substrate layer is corona-treated to increase the adhesion of the substrate layer and facilitate the adhesion of the antistatic liquid to the substrate layer.

[0066] In applications, corona treatment is a physical and chemical modification of the substrate surface through high-voltage discharge (5 - 20 kV), which specifically includes: corona breaks the molecular chains on the substrate surface (such as PET) to generate polar groups such as carboxyl (-COOH) and hydroxyl (-OH), and the surface energy is increased from <30 mN / m to ≥45 mN / m; improves the spreadability of the antistatic liquid on the substrate, and the contact angle is reduced from >80° to <30°, avoiding pinholes 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 interlocking 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.

[0067] In some embodiments, the corona treatment can also be other modification treatments, including any one of plasma treatment, flame treatment, ultraviolet ozone treatment, chemical treatment, and laser treatment. In a preferred embodiment, the surface of the substrate layer is modified by corona treatment. The specific parameters of the corona treatment include a power density of 1-3 W / cm 2 , a treatment speed of 10-30 m / min, and an electrode spacing of 1-2 mm.

[0068] In applications, the modification treatment can also include plasma treatment, which uses an ionized gas (such as oxygen, nitrogen, argon) to generate high-energy particles that bombard the material surface to generate active groups or etch the surface. This can increase the surface energy (up to over 70 mN / m) and improve wettability. Flame treatment oxidizes the material surface at high temperature through a gas flame (such as propane / air) to generate polar groups. This can increase the surface energy and remove the weak boundary layer on the surface. Ultraviolet ozone treatment uses ultraviolet light (UV) to excite ozone (O3) to decompose into reactive 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.

[0069] In some embodiments, the thickness of the substrate layer is 20-50 μm. In a specific embodiment, the thickness of the substrate layer can be any value within the range of 15-50 μm, such as 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc. Within this thickness range, the mechanical properties of the entire cover tape can be optimized. The 20-μm lower limit meets the tensile strength and can withstand the dynamic tension during carrier tape encapsulation; the 50-μm upper limit can control the bending stiffness ≤ 3.0 mN·m to avoid tape jamming during high-speed mounting. Compared with traditional substrates (original 30-70 μm), the thickness is reduced by 30%, the material cost is reduced by 25%, and the flexibility is increased by 40%.

[0070] In some embodiments, the thickness of the anti-static film layer is 5-20 μm. In a specific embodiment, the thickness of the substrate layer can be any value within the range of 5-20 μm, such as 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 13 μm, 15 μm, 16 μm, 18 μm, 20 μm, etc. This can significantly improve the electrical conductivity of the anti-static film layer. When the integrity of the conductive network and the carbon nanotube (CNT) content ≥ 1.2 wt%, a continuous conductive path can be formed, and the surface resistance is stabilized at 10 8 ~10 9 Ω / sq; the 20-μm upper limit can avoid excessive accumulation of conductive fillers and ensure that the resistance volatility < 5% (traditional structure ±15%).

[0071] In some embodiments, after curing the antistatic liquid coated on the substrate layer to form an antistatic film layer adhered to the substrate layer and obtaining an intermediate strip, the following steps are further included:

[0072] The intermediate strip is slit and inspected to obtain a cover tape with a preset specification and meeting the standards.

[0073] The traditional process may directly wind up after coating and curing, without strict slitting and inspection, resulting in poor product consistency, requiring subsequent processing or customer complaints. However, the current steps can detect problems in a timely manner during the production process, reduce the inflow of defective products into the market, and improve the yield. In addition, the slit cover tape is easier to package and transport, meeting the needs of different customers.

[0074] In applications, slitting is to cut the wide intermediate strip into the required width, such as suitable for carrier tapes of different sizes. During the slitting process, it is necessary to keep the edges neat and avoid burrs or cracks, otherwise it will affect the adhesion between the cover tape and the carrier tape, resulting in poor sealing or electrostatic protection failure. If the slitting accuracy is high, it can improve the material utilization rate, reduce waste, and at the same time ensure the dimensional consistency of each cover tape, which is very important for automated mounting equipment because the equipment requires precise dimensions to operate stably.

[0075] In some embodiments, the material of the substrate layer includes at least one of polyethylene terephthalate, polyethylene, polypropylene, and thermoplastic elastomer. Polyethylene terephthalate (PET) has high strength (≥200 MPa), high transparency (≥90%), and excellent dimensional stability (thermal shrinkage rate <0.5%), and is suitable for the encapsulation of precision electronic components. Polyethylene (PE) has low cost, good flexibility (elongation at break >500%), and excellent chemical resistance, but poor thermal stability (melting point 120 - 130 °C), and is suitable for low-cost general scenarios. Polypropylene (PP) has good heat resistance (melting point 160 - 170 °C), low density (0.9 g / cm 3 )), and excellent fatigue resistance, but lower transparency (80 - 85%), and is suitable for applications in high-temperature environments. Thermoplastic elastomer (TPE) has ultra-high flexibility (bending radius ≤1 mm), excellent low-temperature resistance (no breakage at -40 °C), and recyclable environmental protection, but lower strength (10 - 20 MPa), and is suitable for flexible electronic packaging.

[0076] The embodiments of the present application further provide a cover tape, as Figure 2 shown, prepared by the preparation method described in the first aspect. The cover tape includes a substrate layer 10 and an antistatic film layer 100 provided on one side of the substrate layer 10. The antistatic film layer 100 is used for bonding with the carrier tape and preventing static electricity from being generated when peeling off from the carrier tape.

[0077] The cover tape provided by the embodiment of the present application has the beneficial effects described in the first aspect. In addition, for traditional cover tapes, an antistatic layer (such as coating an antistatic agent) and a heat-sealing layer (such as an EVA layer) need to be prepared separately, while in the new solution, the two are combined into a single layer, reducing the production process and material costs. Secondly, the antistatic performance of the cover tape can be effectively improved, making it easier for the cover tape to be peeled off from the carrier tape without causing components to fly out due to static electricity generation.

[0078] Embodiment

[0079] Embodiment 1

[0080] The embodiment of the present application provides a cover tape and a preparation method thereof, wherein the preparation method of the cover tape includes:

[0081] S10. Prepare a base material layer and an antistatic liquid;

[0082] S20. Coat the antistatic liquid on one side of the base material layer;

[0083] S30. Cure the antistatic liquid coated on the base material layer to form an antistatic film layer adhered to the base material layer;

[0084] After S40, when curing the antistatic liquid coated on the base material layer to form an antistatic film layer adhered to the base material layer to obtain an intermediate tape, it further includes:

[0085] Slit and detect the intermediate tape to obtain a cover tape with a preset specification and meeting the standard. The cover tape model is JXY166.

[0086] Among them, the preparation of the antistatic liquid includes:

[0087] Provide 6 g of single-walled carbon nanotubes and 4 g of multi-walled carbon nanotubes as conductive agents, 7.5 g of PVP and 2.5 g of PEG as dispersants, 133 g of EVA resin, 2.66 g of compatibilizer and 3070 g of water as a solvent, and divide 3070 g of water into 1980 g and 1090 g;

[0088] Mix 6 g of single-walled carbon nanotubes, 4 g of multi-walled carbon nanotubes, 7.5 g of PVP, 2.5 g of PEG and 1980 g of water to obtain a carbon paste, and the solid content of the carbon paste is 1%;

[0089] Mix the carbon paste in the previous step with 133 g of EVA resin, 2.66 g of compatibilizer and 1090 g of water to obtain an antistatic liquid, and adjust the solid content of the antistatic liquid to 2%.

[0090] Table 1 Weights of each component and solid content of the antistatic liquid in Embodiment 1

[0091] Item Total Mass Solid Content Proportion of Solid Content Conductive Agent 10g 10g 100％ Dispersant 10g 10g 100％ Carbon Paste 2000g 20g 1％ EVA Resin 133g 40g 30％ Compatibilizer 2.66g 2.66g 100％ Antistatic Liquid 3133g 62.66g 2％

[0092] Among them, the conductive agent (6 g of single-walled carbon nanotubes and 4 g of multi-walled carbon nanotubes); the mass ratio of the solid content of the carbon paste to the solid content of the main resin is 1:2; in the combined dispersant, the mass ratio of PVP to PEG is 3:1. In addition, after obtaining the antistatic liquid, part of the water needs to be evaporated to adjust the solid content of the antistatic liquid to 2%.

[0093] Among them, in step S10, the preparation of the compatibilizer includes:

[0094] Heat 25 g of maleic anhydride to 65 °C until it melts, then add 25 g of isopropanol. After the addition is completed, continue to heat up to 80 °C and keep the temperature for 1 h to obtain 25 g of isopropyl maleate;

[0095] Mix 25 g of isopropyl maleate and 100 g of water, heat up to 80 °C, then add 13 g of acrylic acid and 3 g of ammonium persulfate. After mixing evenly, keep the temperature for 2 h to obtain the compatibilizer.

[0096] Example 2

[0097] It is basically the same as Example 1, except that the type of the cover tape prepared is JXY5910, and the specific formula of the antistatic liquid used is different, as shown in the following table:

[0098] Table 2 Weights and solid contents of each component of the antistatic liquid in Example 2

[0099] Item Total Mass Solid Content Proportion of Solid Content Conductive Agent 6g 6g 100％ Dispersant 6g 6g 100％ Carbon Paste 2400g 12g 0.5％ EVA Resin 96g 24g 25％ Compatibilizer 2.88g 2.88g 100％ Antistatic Liquid 1944g 38.88 2％

[0100] Among them, the conductive agent (6 g of single-walled carbon nanotubes and 4 g of multi-walled carbon nanotubes); the mass ratio of the solid content of the carbon paste to the solid content of the main resin is 1:2; in the combined dispersant, the mass ratio of PVP to PEG is 3:1. In addition, after obtaining the antistatic liquid, part of the water needs to be evaporated to adjust the solid content of the antistatic liquid to 2%.

[0101] Example 3

[0102] It is basically the same as Example 1, except that the type of the cover tape prepared is YJLG-83, and the specific formula of the antistatic liquid used is different, as shown in the following table:

[0103] Table 3 Weights and solid contents of each component of the antistatic liquid in Example 3

[0104] Item Total Mass Solid Content Proportion of Solid Content Conductive Agent 5g 5g 100％ Dispersant 5g 5g 100％ Carbon Paste 666.67g 10g 1.5％ EVA Resin 85.7g 30g 35％ Compatibilizer 0.86g 0.86g 100％ Antistatic Liquid 2043g 40.86g 2％

[0105] Among them, the conductive agent (6 g of single-walled carbon nanotubes and 4 g of multi-walled carbon nanotubes); the mass ratio of the solid content of the carbon paste to the solid content of the main resin is 1:2; in the combined dispersant, the mass ratio of PVP to PEG is 3:1. In addition, after obtaining the antistatic liquid, part of the water needs to be evaporated to adjust the solid content of the antistatic liquid to 2%.

[0106] Example 4

[0107] It is basically the same as Example 1, except that the cover tape model obtained is YJLG-86 and the specific formula of the antistatic liquid used is different, as shown in the following table:

[0108] Table 4 Weights and solid contents of the components of the antistatic liquid in Example 4

[0109] Item Total Mass Solid Content Proportion of Solid Content Conductive Agent 10g 10g 100％ Dispersant 10g 10g 100％ Carbon Paste 2000g 20g 1％ EVA Resin 100g 30g 30％ Compatibilizer 2g 2g 100％ Antistatic Liquid 3100g 52g 1.68％

[0110] Among them, the conductive agent (6 g of single-walled carbon nanotubes and 4 g of multi-walled carbon nanotubes); the mass ratio of the carbon paste solid content to the main resin solid content is 1:1.5; in the combined dispersant, the mass ratio of PVP to PEG is 3:1. In addition, after obtaining the antistatic liquid, part of the water needs to be evaporated to adjust the solid content of the antistatic liquid to 1.68%.

[0111] Performance test

[0112] The following tests were carried out on the cover tapes obtained in the above examples:

[0113] 1. T-peel strength determination: single-sided knife coating (100 um knife coating), oven drying, the thickness of the antistatic film layer is 8-10 um, and the T-peel strength of the carbon nanotube antistatic film on the substrate was determined using a peel tester. 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°.

[0114] The T-peel strength was obtained as 15-25 N / m.

[0115] 2. After sealing with the carrier tape, the pulling force of the cover tape peeling off the carrier tape was tested, with the unit of g. Test settings: test machine number = peel force tester, peel angle = 165°, peel speed = 300 mm / min, peel length = 300 mm, upper limit of pulling force = 100, lower limit of pulling force = 20. The test results are shown in the following table:

[0116] Sample P / N Date Cover Tape Model Maximum Value Minimum Value Average Value Range Standard Deviation Remarks Example 1 D1 JXY166 25.3 18.8 22.497 6.5 1.6562 - Example 1 D1 JXY166 34.8 26.9 30.701 7.9 1.8959 - Example 1 D1 JXY166 38 26.1 31.431 11.9 3.5394 - Example 2 D1 JXY5910 47.1 32.5 40.509 14.6 3.0306 - Example 2 D1 JXY5910 54.5 28.6 44.123 25.9 7.4388 - Example 2 D1 JXY5910 31.3 23.8 27.783 7.5 1.3426 - Example 3 D1 YJLG-83 46.1 30.1 39.461 16 3.3603 - Example 3 D1 YJLG-83 53.1 32 44.119 21.1 4.3079 - Example 4 D1 YJLG-86 76.2 35.9 60.827 40.3 10.411 - Example 4 D1 YJLG-86 68 35.5 55.715 32.5 6.3659 - Example 4 D1 YJLG-86 82.8 50.1 69.31 32.7 7.6198 - Example 2 D3 JXY5910 35.7 26.8 32.611 8.9 1.672 Natural Aging Example 1 D3 JXY166 36.3 25.8 30.697 10.5 2.2191 Natural Aging Example 4 D3 YJLG-86 77.5 43.2 63.582 34.3 5.8299 Natural Aging Example 3 D3 YJLG-83 40.2 28.9 35.783 11.3 2.3142 Natural Aging Example 3 D3 YJLG-83 44.1 25.2 37.359 18.9 3.272 45°C, 65% Humidity Example 4 D3 YJLG-86 71.8 44 61.027 27.8 5.7467 45°C, 65% Humidity Example 1 D3 JXY166 32.8 21.4 28.458 11.4 2.4356 45°C, 65% Humidity Example 2 D3 JXY5910 35.5 27.8 32.758 7.7 1.297 45°C, 65% Humidity Example 2 D7 JXY5910 39.2 28.9 34.645 10.3 1.9173 Natural Aging Example 1 D7 JXY166 35.6 27.5 32.456 8.1 1.5585 Natural Aging Example 4 D7 YJLG-86 76.7 52.4 66.33 24.3 4.8705 Natural Aging Example 3 D7 YJLG-83 42.2 26.9 35.739 15.3 3.0632 Natural Aging Example 3 D7 YJLG-83 40.9 29.5 34.156 11.4 2.6137 45°C, 65% Humidity Example 4 D7 YJLG-86 76.3 47.7 62.731 28.6 7.4772 45°C, 65% Humidity Example 2 D7 JXY5910 38.8 28 35.198 10.8 2.2595 45°C, 65% Humidity Example 1 D7 JXY166 46.5 29.4 39.365 17.1 4.4553 45°C, 65% Humidity Example 2 D14 JXY5910 36.7 30.3 34.455 6.4 1.3632 Natural Aging Example 1 D14 JXY166 35.8 25 32.129 10.8 2.5298 Natural Aging Example 3 D14 YJLG-83 47.3 29 38.362 18.3 4.0487 Natural Aging Example 4 D14 YJLG-86 60.3 39.1 52.216 21.2 4.5009 Natural Aging Example 4 D14 YJLG-86 71.4 49.7 63.64 21.7 5.0471 45°C, 65% Humidity Example 4 D14 YJLG-86 46.3 30.3 39.131 16 3.1033 45°C, 65% Humidity Example 2 D14 JXY5910 29.6 21.8 25.463 7.8 1.731 45°C, 65% Humidity Example 1 D14 JXY166 47.7 29.1 40.333 18.6 5.2157 45°C, 65% Humidity Example 2 D30 JXY5910 48.2 31.1 43.377 17.1 4.7553 Natural Aging Example 1 D30 JXY166 40.9 29.3 37.377 11.6 2.8646 Natural Aging Example 3 D30 YJLG-83 61.4 43.1 53.39 18.3 4.2203 Natural Aging Example 4 D30 YJLG-86 79 57.3 70.619 21.7 4.6381 Natural Aging Example 3 D30 YJLG-83 60.6 44.9 51.905 15.7 3.4998 45°C, 65% Humidity Example 4 D30 YJLG-86 92.6 72.6 81.118 20 3.8193 45°C, 65% Humidity Example 1 D30 JXY166 49.2 29.3 42.266 19.9 5.5834 45°C, 65% Humidity Example 2 D30 JXY5910 36.9 26.2 32.147 10.7 2.8636 45°C, 65% Humidity

[0117] In the above examples, the descriptions of each example have their own focuses. For parts not detailed or recorded in a certain example, the relevant descriptions of other examples can be referred to.

[0118] The above-described embodiments are only used to illustrate the technical solutions of the embodiments of the present application, rather than 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 cause the essence of the corresponding technical solutions to 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 cover tape, characterized in that, Comprising: Preparing a substrate layer and an antistatic liquid; Coating the antistatic liquid on one side of the substrate layer; Curing the antistatic liquid coated on the substrate layer to form an antistatic film layer adhered to the substrate layer; Wherein, the antistatic film layer is used for bonding with a carrier tape and preventing static electricity from being generated when a cover tape is peeled off from the carrier tape.

2. The preparation method according to claim 1, characterized in that, The antistatic liquid comprises the following components in parts by weight: 1 - 3 parts of carbon nanotubes; 1 - 3 parts of a dispersant; 10 - 30 parts of a resin matrix; 0.1 - 0.6 parts of a compatibilizer.

3. The preparation method according to claim 2, characterized in that, The carbon nanotubes comprise single - wall carbon nanotubes; Or, the carbon nanotubes comprise single - wall carbon nanotubes and multi - wall carbon nanotubes, and the mass ratio of the single - wall carbon nanotubes is greater than or equal to 60%.

4. The preparation method according to claim 2, wherein, The resin matrix comprises at least one of ethylene - vinyl acetate copolymer, polyolefins, polyurethane, hot melt adhesives.

5. The preparation method according to claim 1, characterized in that, The solid content of the antistatic liquid is 1.5% - 3%; And / or, the solid content of the resin matrix is 25% - 35%.

6. The preparation method according to claim 1, wherein Before coating the antistatic liquid on one side of the substrate layer, the surface of the substrate layer is corona - treated to increase the adhesion of the substrate layer, facilitating the adhesion of the antistatic liquid to the substrate layer.

7. The preparation method according to claim 1, characterized in that, The thickness of the substrate layer is 20 - 50 μm; And / or, the thickness of the antistatic film layer is 5 - 20 μm.

8. The preparation method according to claim 1, characterized in that, After curing the antistatic liquid coated on the substrate layer to form an antistatic film layer adhered to the substrate layer and obtaining an intermediate tape, it further includes: Slitting and inspecting the intermediate tape to obtain a cover tape with a preset specification and meeting the standards.

9. The preparation method according to any one of claims 1 to 8, characterized in that, The material of the substrate layer comprises at least one of polyethylene terephthalate, polyethylene, polypropylene, thermoplastic elastomer.

10. A cover tape, characterized in that, Prepared by the preparation method according to any one of claims 1 to 9, the cover tape comprises a substrate layer and an antistatic film layer provided on one side of the substrate layer, and the antistatic film layer is used for bonding with a carrier tape and preventing static electricity from being generated when peeled off from the carrier tape.

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