Cover tape and electronic component packaging containing the same

Abstract

The present invention addresses the problem of providing a cover tape to which an electronic component is less likely to adhere when the cover tape is released to extract the electronic component.　This cover tape comprises an insulative heat seal layer provided on one surface and a conductive layer directly laminated on the heat seal layer, wherein a heat seal layer side has a surface resistivity of 1 × 1010Ω／□ or less, and the heat seal layer has a thickness of less than 600 nm.　

Description

[Technical Field]

[0001] The present invention relates to a cover tape and an electronic component packaging body including the same. [Background technology]

[0002] With the miniaturization of electronic devices, the electronic components used have also become smaller and more high-performance, and in addition, the assembly process of electronic devices is now being carried out to automatically mount components onto printed circuit boards. Surface-mount electronic components are housed in carrier tapes in which pockets are continuously formed by thermoforming to match the shape of the electronic components. After housing the electronic components, a cover tape is placed on top of the carrier tape as a lid material, and both ends of the cover tape are continuously heat-sealed in the length direction with a heated sealing bar to form a package.

[0003] In recent years, various electronic components such as capacitors, resistors, ICs, LEDs, connectors, and switching elements have undergone remarkable miniaturization, weight reduction, and thinning. As a result, the performance requirements for peeling off the cover tape to remove the electronic components from the packaging have become more stringent than ever before. Furthermore, problems in the mounting process are becoming more likely to occur, such as electronic components sticking to the cover tape and flying off due to static electricity generated when peeling the cover tape from the carrier tape in order to remove the electronic components. Therefore, static electricity countermeasures for the carrier tape and cover tape have been considered an important issue.

[0004] In cover tapes currently on the market, a conductive agent such as conductive tin oxide is added to the heat seal layer to suppress component adhesion as a measure against static electricity (Patent Document 1).

[0005] [Patent Document 1] International Publication No. 2019 / 087999 [Overview of the project]

[0006] However, in methods that add a conductive agent to the heat seal layer, induced charging can occur within the heat seal layer due to the triboelectric charging of electronic components, and an electric charge may be generated on the surface of the heat seal layer. When an electric charge is generated, an electrostatic attraction is generated, which can cause electronic components to adhere, so the method may not be sufficient as an anti-static measure. The present invention has been made in view of the above circumstances, and aims to provide a cover tape that reduces the risk of electronic components adhering to the cover tape when the cover tape is peeled off in order to remove the electronic components.

[0007] As a result of diligent study on the above-mentioned problems, the inventors have found that instead of providing a heat seal layer containing a conductive agent on a single surface, an insulating heat seal layer is provided, and a conductive layer is directly laminated onto the heat seal layer, and furthermore, the surface resistivity of the heat seal layer side is 1 × 10⁻⁶ 10 We discovered that by using a cover tape with a heat seal layer thickness of less than 600 nm and a capacitance of Ω / □ or less, the generation of electrostatic attraction between the heat seal layer and the electronic component can be suppressed, leading to the present invention.

[0008] The present invention, which solves the above problems, consists of the following: (1) A cover tape having an insulating heat seal layer provided on one surface and a conductive layer directly laminated on the heat seal layer, The surface resistivity of the heat seal layer is 1 × 10⁻⁶ 10 It is less than or equal to Ω / □, The average thickness of the heat seal layer is less than 600 nm. Cover tape. (2) The cover tape according to (1), wherein the conductive layer contains a resin and a conductive agent. (3) The cover tape according to (1) or (2), wherein the conductive agent is selected from the group consisting of conductive tin oxide particles, conductive polymers, and carbon nanomaterials. (4) The cover tape according to (2) or (3), wherein the conductive layer contains 65 to 95% by mass of a conductive agent, and the conductive agent is conductive tin oxide particles. (5) The cover tape according to (3) or (4), wherein the conductive tin oxide particles are antimond-doped tin oxide (ATO). (6) A cover tape according to any one of (1) to (5), having a heat seal layer, a conductive layer, and a base material layer in this order. (7) A cover tape according to any one of (1) to (6), having a heat seal layer, a conductive layer, an intermediate layer, and a base material layer in this order. (8) A cover tape according to any one of (1) to (7), wherein the thickness of the heat seal layer is 30 to 250 nm. (9) A cover tape according to any one of (1) to (8), for use as a lid material for an electronic component package. (10) An electronic component package including a carrier tape and a cover tape according to any one of (1) to (9).

[0009] According to the present invention, when peeling the cover tape to take out the electronic component, a cover tape with a low risk of the electronic component adhering to the cover tape can be obtained.

Brief Description of the Drawings

[0010] [Figure 1] It is a cross-sectional view showing the layer structure of the cover tape of the first embodiment of the present invention. [Figure 2] It is a cross-sectional view showing the layer structure of the cover tape of the second embodiment of the present invention.

Modes for Carrying Out the Invention

[0011] Hereinafter, various embodiments of the cover tape will be described, and then the manufacturing method of the cover tape will be described. However, when the specific description given for one embodiment also applies to other embodiments, the description for other embodiments is omitted.

[0012] [First Embodiment] The cover tape according to the first embodiment of the present invention is a cover tape having an insulating heat seal layer provided on one surface and a conductive layer directly laminated on the heat seal layer, and the surface resistivity on the heat seal layer side is 1×10 10A cover tape having a resistance of Ω / □ or less and an average thickness of the heat-sealing layer of less than 600 nm. The configuration of the cover tape of this embodiment is shown in FIG. 1. The cover tape 1 shown in FIG. 1 has a heat-sealing layer 2, a conductive layer 3, and a base material layer 4 provided in this order. In this cover tape 1, the heat-sealing layer 2 constitutes one surface, and the base material layer 4 constitutes the other surface.

[0013] (Heat-sealing layer) The heat-sealing layer is a layer having an action of welding to other resins by heat, and as shown in FIG. 1, it is one layer that constitutes one surface of the cover tape. The heat-sealing layer preferably contains a thermoplastic resin as a main component. Here, "containing as a main component" means containing 50% by mass or more in the resin. In one embodiment, the heat-sealing layer may contain 70% by mass or more, or 90% by mass or more of the thermoplastic resin in the resin. As the thermoplastic resin constituting the heat-sealing layer, polyolefin-based resins, acrylic resins, styrene-acrylic copolymers, etc. can be used. An acrylic resin is a resin containing a structure derived from at least an acrylic monomer in a repeating unit. Specific examples of acrylic monomers include acrylic esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, etc., methacrylic esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, etc. These acrylic monomers may be used alone or in combination of two or more. Styrene-acrylic copolymers are copolymers comprising a styrene monomer and a (meth)acrylic monomer as essential components. Examples of styrene monomers include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, and p-phenylstyrene, with styrene being particularly preferred. These styrene monomers can be used individually or in combination of two or more. Examples of (meth)acrylic monomers include acrylic acid esters such as methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate, and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and cyclohexyl methacrylate. These (meth)acrylic monomers can be used individually or in combination of two or more. In addition, a small amount of other monomers copolymerized with these monomers may be used in addition to the styrene monomer and (meth)acrylic monomer.

[0014] The resin mainly composed of the aforementioned styrene-acrylic copolymer exhibits excellent heat-sealing properties with respect to materials such as polystyrene and polycarbonate that constitute the carrier tape. In particular, resins mainly composed of styrene-acrylic copolymer with a mass-average molecular weight of 5,000 to 80,000, preferably 10,000 to 50,000, are used. If the mass-average molecular weight is 5,000 or higher, mounting problems such as tackiness causing the stored components to adhere to the heat-seal layer are suppressed. On the other hand, if the mass-average molecular weight is 80,000 or lower, the increase in peel strength when the peeling speed is increased is significant, which suppresses the occurrence of breakage. Furthermore, the glass transition temperature of the styrene-acrylic copolymer is preferably 50°C to 90°C. Setting it to 50°C or higher reduces the risk of stored components adhering to the heat-seal surface of the cover tape in transportation environments such as sea freight. The mass-average molecular weight is measured using the following GPC measuring device and under the following conditions. Equipment name: High-speed GPC system HLC-8220 (manufactured by Tosoh Corporation) Column: Three PL gel MIXED-B columns in series Temperature: 40℃ Detection: Differential refractive index Solvent: tetrahydrofuran Concentration: 2wt% Calibration curve: Prepared using standard polystyrene (manufactured by Polymer Laboratories), and the mass-average molecular weight (Mw) is calculated as the molecular weight in polystyrene equivalent.

[0015] The heat seal layer in this embodiment is insulating, meaning that, for example, according to JIS K6911, the surface resistivity measured at an ambient temperature of 23°C, ambient humidity of 50% RH, and applied voltage of 10V is 10%. 11 This means that the ratio is greater than or equal to Ω / □. Preferably 10. 13 Ω / □ or higher, comfortable 10 14 This means that the coefficient of conductivity is Ω / □ or greater. In further embodiments of the present invention, the heat seal layer preferably contains less than 0.01% by mass of an additive that imparts conductivity (e.g., a conductive agent), and more preferably contains no conductive agent.

[0016] Polyolefin resins refer to resins made of polymers containing α-olefins as monomers, and include polyethylene resins and polypropylene resins. Polyethylene resins can include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, linear medium-density polyethylene, etc. Furthermore, not only individual materials but also copolymers, grafts, and blends having these structures can be used. Examples of the latter resins include copolymers and blends of resins having polar groups in the polyethylene chain, such as ethylene-propylene copolymers, ethylene-1-butene copolymers, ethylene-1-pentene copolymers, ethylene-1-hexene copolymers, ethylene-1-octene copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid ester copolymers, ethylene-maleic acid copolymers, styrene-ethylene graft copolymers, styrene-propylene graft copolymers, styrene-ethylene-butadiene block copolymers, and blends with terpolymers containing acid anhydrides.

[0017] Furthermore, as the polypropylene resin, homopolypropylene, random polypropylene, block polypropylene, etc., can be used. When homopolypropylene is used, the structure of the homopolypropylene may be isotactic, atactic, or syndiotactic. When random polypropylene is used, the α-olefin copolymerized with propylene preferably has 2 to 20 carbon atoms, more preferably 4 to 12 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, or 1-decene. When block polypropylene is used, block copolymers (block polypropylene), block copolymers containing rubber components, or graft copolymers can be used. In addition to using these olefin resins alone, other olefin resins can also be used in combination.

[0018] The average thickness of the heat seal layer is less than 600 nm, preferably 580 nm or less, more preferably 400 nm or less, even more preferably 250 nm or less, and still more preferably 200 nm or less. The lower limit of the average thickness of the heat seal layer is not particularly limited within a feasible range, but can be 5 nm or more, 10 nm or more, 20 nm or more, 30 nm or more, or 50 nm or more. Preferred ranges for the average thickness of the heat seal layer include 5 nm or more and less than 600 nm, 10 nm or more and 580 nm or less, 20 nm or more and 400 nm or less, 30 nm or more and 250 nm or less, or 50 nm or more and 200 nm or less. By setting the average thickness of the heat seal layer to a certain level or higher, insulation can be obtained. By setting the average thickness of the heat seal layer to less than 600 nm, the generation of electrostatic attraction can be suppressed. As will be described later, the heat seal layer is usually formed by coating. When formed by coating, the thickness referred to here is the thickness after drying. The method for measuring the average thickness will be described later.

[0019] Furthermore, in the cover tape according to an embodiment of the present invention, an inorganic filler is added to the heat seal layer. In the cover tape of this embodiment, in order to remove moisture contained in the encapsulating resin while being heat-sealed to the surface of the carrier tape containing electronic components, baking treatment may be performed under conditions of 60°C for 72 hours or about 24 hours under an 80°C environment. In such a case, if the electronic components as the contents adhere to the cover tape, it will cause trouble in the process of peeling off the cover tape and mounting the electronic components. In the cover tape of this embodiment, the variation in the peel strength when peeling off the cover tape is small, and the adhesion of the heat seal layer to the electronic components of the contents under high temperatures such as 60 to 80°C can also be controlled. Therefore, such problems of adhesion of electronic components are considerably solved. However, when an inorganic filler is added to the heat seal layer, this adhesion prevention is more surely achieved. Here, the inorganic filler to be added may be any as long as the above adhesion prevention is significantly achieved, but those other than those imparting conductivity are preferred. For example, spherical or crushed talc particles, silica particles, alumina particles, mica particles, calcium carbonate, magnesium carbonate, etc. may be mentioned. Also, in order to maintain the transparency of the cover tape, the inorganic filler should have a median diameter (D50) of less than 400 nm, and for example, 10 to 30 mass% of this is included.

[0020] (Conductive layer) As shown in FIG. 1, the conductive layer is one of the layers constituting the cover tape and is a layer directly laminated on the heat seal layer. The conductive layer in this embodiment is conductive, and conductivity means that, for example, according to JIS K6911, the surface resistivity measured at an ambient temperature of 23°C, an ambient humidity of 50%RH, and an applied voltage of 10V is 10 10 Ω / □ or less. Preferably 10 9 Ω / □ or less, more preferably 10 8 Ω / □ or less.

[0021] The average thickness of the conductive layer is preferably 0.005 μm to 100 μm, more preferably 0.01 to 1 μm, and even more preferably 0.05 to 0.1 μm. A thickness of 0.005 μm or more in the conductive layer suppresses coating defects during application. On the other hand, a thickness of 100 μm or less helps to reduce costs. As will be discussed later, this conductive layer is usually formed by coating, and when formed by coating, the thickness referred to here is the thickness after drying.

[0022] The conductive layer preferably contains a thermoplastic resin. The thermoplastic resin constituting the conductive layer is a resin having an olefin as a component, and for example, low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-pentene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ethylene-maleic acid copolymer, styrene-ethylene graft copolymer, styrene-propylene graft copolymer, styrene-ethylene-butadiene block copolymer, propylene, etc. These polyolefins can be used individually or in combination as a mixture of two or more.

[0023] In one embodiment of the present invention, the conductive layer contains a conductive agent. Examples of conductive agents include conductive tin oxide particles, conductive zinc oxide particles, and conductive titanium oxide particles. Among these, tin oxide doped with antimony, phosphorus, or gallium is more preferably used because it exhibits high conductivity and causes little reduction in transparency. Conductive tin oxide particles, conductive zinc oxide particles, and conductive titanium oxide particles can be spherical, needle-shaped, or mixtures thereof. In particular, when needle-shaped tin oxide doped with antimony is used, a cover tape with particularly good antistatic performance can be obtained. The amount of conductive agent added is preferably 65 to 95% by mass, more preferably 67 to 93% by mass, and even more preferably 70 to 90% by mass, relative to the material constituting the conductive layer. By adding 65% by mass or more of conductive fine particles, the surface resistivity of the heat seal layer side of the cover tape becomes 10 10 By suppressing the ratio from exceeding Ω / □ and keeping it below 95% by mass, the decrease in the relative amount of thermoplastic resin is suppressed, which prevents a decrease in peel strength due to heat sealing.

[0024] The conductive agent can also include carbon nanomaterials such as carbon nanotubes and carbon nanofibers. Among these, carbon nanotubes with an aspect ratio of 10 to 10000 are preferred. The amount of carbon nanomaterial added is 1 to 50% by mass relative to the material constituting the conductive layer, preferably 5 to 45% by mass. By adding 1% by mass or more, the effect of imparting conductivity through the addition of carbon nanomaterials can be obtained, while by adding 50% by mass or less, an increase in cost and a decrease in the transparency of the cover tape can be suppressed. Furthermore, conductive polymers such as water-soluble polymer hydrated gels, polythiophene-based conductive polymers, polyaniline-based conductive polymers, and polypyrrole-based conductive polymers can also be included as conductive agents. The amount of conductive polymer added is 1 to 50% by mass relative to the material constituting the conductive layer, preferably 5 to 45% by mass.

[0025] (base material layer) The base layer preferably contains a thermoplastic resin. As the thermoplastic resin constituting the base layer, a resin containing at least one of polyester resins, polyolefin resins, or super engineering plastics can be used.

[0026] Examples of polyester resins include polyester resins having two or more active hydrogens such as hydroxyl groups or amino groups in the molecule, specifically polyester polyols and polyester polyamines. For polyester polyols, a hydroxyl value (mgKOH / g) of 1 to 200 and a number-average molecular weight of 1,000 to 50,000 are preferred. The number-average molecular weight referred to here is the value measured according to JIS K7252. Examples of polyester polyols include condensation reaction products of polyhydric hydroxyl group-containing compounds with polycarboxylic acids or anhydrides and ester-forming derivatives such as lower alkyl (alkyl group with 1 to 4 carbon atoms) esters. More specifically, examples include polyethylene terephthalate, polyethylene naphthalate, polyarylate, polyethylene-2,6-naphthalate, polymethylene terephthalate, and polyester resins copolymerized with diol components such as diethylene glycol, neopentyl glycol, and polyalkylene glycol, or dicarboxylic acid components such as adipic acid, sebatic acid, phthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. When combining polyester resins with other resins, the content of the polyester resin is not particularly limited, but for example, the polyester resin can be 50% by mass or more, 70% by mass or more, or 90% by mass or more in the thermoplastic resin.

[0027] Examples of polyolefin resins include polyethylene resins and polypropylene resins. Polyethylene resins can include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, linear medium-density polyethylene, etc., and not only individual materials but also copolymers, grafts, and blends having these structures can be used. Examples of the latter resins include copolymers of monomers having polar groups in the polyethylene chain, and blends thereof. Examples of copolymers of monomers having polar groups in the polyethylene chain include ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid ester copolymer, ethylene-vinyl acetate-vinyl chloride copolymer, and terpolymers of the above copolymers and acid anhydrides.

[0028] Furthermore, as polypropylene resins, homopolypropylene, random polypropylene, block polypropylene, etc., can be used. When using homopolypropylene, the structure of the homopolypropylene may be isotactic, atactic, or syndiotactic. When using random polypropylene, the α-olefin copolymerized with propylene preferably has 2 to 20 carbon atoms, more preferably 4 to 12 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, or 1-decene. When using block polypropylene, block copolymers (block polypropylene), block copolymers containing rubber components, or graft copolymers can be used. In addition to using these olefin resins alone, other olefin resins can also be used in combination. When combining polyolefin resins with other resins, the content of the polyolefin resin is not particularly limited, but for example, the polyolefin resin can be 50% by mass or more, 70% by mass or more, or 90% by mass or more in the thermoplastic resin.

[0029] Examples of super engineering plastics include fluororesins such as polytetrafluoroethylene and polyvinylidene fluoride, polyphenylene sulfide, liquid crystal polymers, polyacrylates, thermoplastic polyimides, ketone resins, and sulfone resins. When combining super engineering plastics with other resins, the content of super engineering plastics is not particularly limited, but for example, the amount of super engineering plastics in the resin can be 50% by mass or more, 70% by mass or more, or 90% by mass or more.

[0030] The film used as the base layer may be unoriented, uniaxially oriented, or biaxially oriented.

[0031] The average thickness of the base layer is preferably 5 to 50 μm, and more preferably 8 to 30 μm. By making the base layer thickness 5 μm or more, the tensile strength of the cover tape itself is reduced, which can suppress "film breakage" when peeling off the cover tape. On the other hand, by making it 50 μm or less, a decrease in heat sealability to the carrier tape and an increase in cost can be suppressed. The method for measuring the average thickness is as described above.

[0032] (Cover tape) The cover tape of this embodiment has a surface resistivity of 1 × 10⁻¹⁰ 10 The value is less than or equal to Ω / □, but preferably 1 × 10 6 ~5×10 9 Ω / □, more preferably 1 × 10 6 ~2×10 8 It is Ω / □. On the other hand, its lower limit is not particularly limited within the feasible range, but 1 × 10 4 Ω / □, 1×10 5 Ω / □, or 1 × 10 6 It can be expressed as Ω / □. A preferred range for the surface resistivity of the heat seal layer side surface is 1 × 10 4~1 × 10 10 Ω / □, 1×10 5 ~10 9 Ω / □, or 1 × 10 6 ~10 8 One example is Ω / □. The surface resistivity value of the cover tape in this embodiment is lower than the measured surface resistivity of a single heat seal layer, which is thought to be due to the influence of the directly laminated conductive layer. The surface resistivity of the heat seal layer side of the cover tape can be adjusted by changing the content of the conductive agent in the heat seal layer and the conductive layer, as well as the thickness of the heat seal layer. Furthermore, in the cover tape according to one embodiment of the present invention, the layers other than the conductive layer are preferably insulating, more preferably the content of an additive that imparts conductivity (e.g., a conductive agent) in the layer is less than 0.01% by mass, and even more preferably the layer does not contain a conductive agent.

[0033] In one embodiment of the present invention, the average thickness of the cover tape is preferably 20 to 80 μm, and more preferably 40 to 60 μm. By setting the average thickness of the cover tape to 20 μm or more, tearing when the cover tape is peeled off can be prevented. On the other hand, by setting the average thickness of the cover tape to 80 μm or less, not only can cost increases be suppressed, but productivity can be improved by shortening the sealing time. The layer thickness is measured by cutting 20mm square sections from five evenly spaced locations along the width of the cover tape, smoothing the edges to allow for determination of the layer structure, and then using a laser microscope (KEYENCE VK-8510). The average thickness of the cover tape refers to the average thickness from one surface to the other. The average thickness of each layer of the cover tape is calculated by measuring the thickness at five locations for each layer and taking the arithmetic mean of these measurements.

[0034] [Second Embodiment] In the cover tape according to the second embodiment of the present invention, an intermediate layer is provided between the base layer and the conductive layer, as shown in Figure 2. The cover tape 1 shown in Figure 2 is provided in the following order: heat seal layer 2, conductive layer 3, intermediate layer 5, and base layer 4. In this cover tape 1, the heat seal layer 2 constitutes one surface, and the base layer 4 constitutes another surface.

[0035] (Middle class) The intermediate layer preferably contains a thermoplastic resin. As the thermoplastic resin constituting the intermediate layer, linear low-density polyethylene (hereinafter referred to as LLDPE), which is flexible, has moderate rigidity, and exhibits excellent tear strength at room temperature, can be suitably used, particularly one with a density of 0.900 to 0.925 (×10). 3 kg / m 3 By using resin within the specified range, the heat and pressure during heat sealing make it less likely for the intermediate layer resin to seep out from the edges of the cover tape, thus reducing contamination of the soldering iron during heat sealing. Furthermore, the softening of the intermediate layer during heat sealing of the cover tape reduces uneven contact with the heat sealing iron, making it easier to obtain stable peel strength when removing the cover tape.

[0036] LLDPEs include those polymerized with a Tigler-type catalyst and those polymerized with a metallocene-based catalyst (hereinafter referred to as m-LLDPE). Because m-LLDPE has a narrowly controlled molecular weight distribution, it has particularly high tear strength and can be suitably used as an intermediate layer in the present invention.

[0037] The above-mentioned m-LLDPE is a copolymer of ethylene and an α-olefin substituted with an olefin having 3 or more carbon atoms, preferably a linear, branched, or aromatic nucleus having 3 to 18 carbon atoms, as a comonomer. Examples of linear monoolefins include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-octadecene. Examples of branched monoolefins include 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, and 2-ethyl-1-hexene. Examples of monoolefins substituted with aromatic nuclei include styrene. These comonomers can be copolymerized with ethylene individually or in combination of two or more. In this copolymerization, polyenes such as butadiene, isoprene, 1,3-hexadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene may be copolymerized. Among these, those using 1-hexene and 1-octene as comonomers are preferable because they have high tensile strength and are cost-effective.

[0038] The average thickness of the intermediate layer is preferably 5 to 60 μm, more preferably 10 to 50 μm, and most preferably 15 to 40 μm. A thickness of 5 μm or more in the intermediate layer helps to suppress the breakage of the cover tape when the heat-sealed cover tape is peeled off at high speed, and also helps to mitigate uneven contact of the heat iron when heat-sealing the cover tape to the carrier tape. On the other hand, a thickness of 60 μm or less helps to prevent the loss of sufficient peel strength when heat-sealing the cover tape to the carrier tape due to a thicker overall cover tape. The method for measuring the average thickness is as described above.

[0039] In one embodiment of the present invention, an anchor coat layer is provided between the base layer and the intermediate layer. In other words, the base layer, anchor coat layer, intermediate layer, conductive layer, and heat seal layer are provided in this order. As the adhesive used for this anchor coat layer, polyurethane adhesives, polyvinyl acetate adhesives, polyacrylic acid ester adhesives, reactive (meth)acrylic adhesives, cyanoacrylate adhesives, ethylene copolymer adhesives consisting of copolymers of ethylene and monomers such as vinyl acetate, ethyl acrylate, acrylic acid, and methacrylic acid, polyester adhesives, polyamide adhesives, polyimide adhesives, amino resin adhesives consisting of urea resin or melamine resin, phenolic resin adhesives, epoxy adhesives, rubber adhesives consisting of chloroprene rubber, styrene-butadiene rubber, and others can be used. The composition system of the above adhesive may be any composition form such as aqueous type, solution type, emulsion type, or dispersion type, and its properties may be any form such as film / sheet type, powder type, or solid type, and the bonding mechanism may be any form such as chemical reaction type using a curing agent, solvent evaporation type, heat melt type, or hot pressure type.

[0040] The average thickness of the anchor coat layer is typically in the range of 50 to 7000 nm, preferably 100 to 5000 nm. By making the release layer thickness 50 nm or more, coating defects of the anchor coat are suppressed. On the other hand, by making the anchor coat layer thickness 7000 nm or less, the effects of residual solvent after drying are suppressed. The method for measuring the average thickness is as described above. The above adhesive can be applied by coating methods such as roll coating, gravure roll coating, kiss coating, or other coating methods, or by printing, and the coating amount is 0.1 to 10 g / m². 2 It is preferable that it be in a dry state.

[0041] [Other embodiments] In another embodiment of the present invention, a release layer mainly composed of a thermoplastic resin is provided between the intermediate layer and the conductive layer. Examples of thermoplastic resins used in this release layer include acrylic resins, polyester resins, ethylene-vinyl acetate copolymer resins (hereinafter referred to as EVA), ethylene-acrylic acid copolymer resins, ethylene-methacrylic acid copolymer resins, styrene-isoprene diblock copolymer resins, hydrogenated resins of styrene-isoprene diblock copolymers, styrene-butadiene diblock copolymer resins, hydrogenated resins of styrene-butadiene diblock copolymers, hydrogenated resins of styrene-isoprene-styrene triblock copolymers (hereinafter referred to as SEPS), hydrogenated resins of styrene-butadiene-styrene triblock copolymers (hereinafter referred to as SEBS), hydrogenated resins of styrene-butadiene random copolymers, and hydrogenated resins of styrene-isoprene random copolymers. Among these, SEPS and SEBS, which have a styrene ratio of 15 to 35% by mass, can be suitably used because they exhibit less variation in peel strength when peeling off the cover tape.

[0042] The average thickness of the release layer is typically in the range of 0.1 to 3 μm, preferably 0.1 to 1.5 μm. A release layer thickness of 0.1 μm or more suppresses insufficient peel strength when the carrier tape is heat-sealed to the cover tape. On the other hand, a release layer thickness of 3 μm or less suppresses variations in peel strength when the cover tape is peeled off. As will be described later, this release layer is usually formed by coating; however, when formed by coating, the thickness referred to here is the thickness after drying. The method for measuring the average thickness is as described above.

[0043] [How to manufacture cover tape] The method for producing the above-mentioned cover tape is not particularly limited, and general methods can be used. For example, an anchor coating agent may be applied to the surface of the film-formed base material layer as needed, and a laminated film having a base material layer and an intermediate layer may be dry-laminated with the formed intermediate layer or an intermediate layer extruded from a T-die. Furthermore, a conductive layer is formed on the intermediate layer by coating it with a resin composition constituting the conductive layer using, for example, a gravure coater, reverse coater, kiss coater, air knife coater, Meyer bar coater, dip coater, etc. Furthermore, a heat seal layer is formed by coating the conductive layer with a resin composition constituting the heat seal layer, thereby obtaining the desired cover tape.

[0044] Alternatively, a conductive layer can be pre-fabricated using methods such as T-die casting or inflation, and then coated with a resin composition that constitutes the heat-seal layer to obtain a film having both a conductive layer and a heat-seal layer.

[0045] [Application] Cover tape can be used as a lid material for carrier tape, which is a container for electronic components. Carrier tape is a strip-shaped material with a width of approximately 8 mm to 100 mm that has pockets for storing electronic components. When heat-sealing cover tape as a lid material, the material that makes up the carrier tape is not particularly limited and commercially available materials can be used, such as thermoplastic resins such as polystyrene, polyester, polycarbonate, and polyvinyl chloride. When acrylic resin is used for the heat-seal layer, a combination with carrier tape such as polystyrene or polycarbonate is preferably used. Carrier tape can also be made by kneading carbon black or carbon nanotubes into the resin to impart conductivity, by kneading in antistatic agents or conductive agents, or by applying a coating liquid to the surface in which surfactant-type antistatic agents or conductive materials such as polypyrrole or polythiophene are dispersed in an organic binder such as acrylic to impart antistatic properties.

[0046] An electronic component package containing electronic components is obtained, for example, by placing electronic components in the electronic component storage section of a carrier tape, then using a cover tape as a lid, continuously heat-sealing both longitudinal edges of the cover tape, and winding it onto a reel. Electronic components are stored and transported in this form. The package containing the electronic components is transported using holes called sprocket holes for carrier tape transport provided on the longitudinal edge of the carrier tape, and the cover tape is intermittently peeled off. The electronic components are then removed by a component mounting device while confirming their presence, orientation, and position, and mounted onto a circuit board.

[0047] Furthermore, when peeling off the cover tape, if the peel strength is too low, it may peel off from the carrier tape, potentially causing the stored components to fall out. If it is too high, it may become difficult to peel it off from the carrier tape, and there is a risk of tearing the cover tape when peeling it off. Therefore, when heat-sealed at 120-220°C, it is preferable to have a peel strength of 0.15N or more and less than 1.5N, and more preferably 0.2N or more and less than 0.8N. [Examples]

[0048] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

[0049] The various raw materials used in the examples are as follows: (Heat seal layer) • Resin: Acrylic resin Dianaal BR-106 (manufactured by Mitsubishi Chemical Corporation), mass-average molecular weight 30000, glass transition temperature 50℃, acid value 3.5 mgKOH / g • Conductive agent: Antimond-doped tin oxide (ATO) FSS-10M (manufactured by Ishihara Sangyo Co., Ltd.), needle-shaped antimond-doped tin oxide, median diameter (D50) average major axis 2 μm, average minor axis 0.1 μm, MEK dispersion type (Conductive layer) • Resin: Styrene-ethylene-butadiene copolymer resin, ToughTec H1272 (manufactured by Asahi Kasei Corporation) • Conductive agent: Antimond-doped tin oxide (ATO) FSS-10M (manufactured by Ishihara Sangyo Co., Ltd.), needle-shaped antimond-doped tin oxide, median diameter (D50) average major axis 2 μm, average minor axis 0.1 μm, MEK dispersion type (base material layer) • Biaxially oriented polyethylene terephthalate film T6142 (manufactured by Toyobo Co., Ltd.), thickness 12 μm (Anchor coat layer) • Main component: Polyurethane adhesive (polyether polyol) TM-319 (manufactured by Toyo Morton Co., Ltd.), ethyl acetate solution, solid content concentration 70% by mass • Curing agent: Polyisocyanate-based curing agent (diphenylmethane diisocyanate type) CAT-11B (manufactured by Toyo Morton Co., Ltd.), ethyl acetate solution, solid content concentration 60% by mass (Middle class) • Polyethylene film TCS (manufactured by Mitsui Tohcello Co., Ltd.), 30 μm thick

[0050] (Example 1) As a base layer, a biaxially oriented polyethylene terephthalate film (thickness 12 μm) was coated with an anchor coating agent and a curing agent (thickness 4000 nm), and then a polyethylene film (thickness 30 μm) was dry-laminated as an intermediate layer. Next, as a conductive layer, a dispersion of ATO was mixed with styrene-ethylene-butadiene copolymer resin dissolved in toluene, so that the ATO content was 80% by mass, and this was coated with a bar coater and dried (thickness 800 nm). Then, as a heat seal layer, an acrylic resin dissolved in MEK was coated with a bar coater to a thickness of 50 nm on the surface of the conductive layer and dried.

[0051] (Example 2) The product was manufactured in the same manner as in Example 1, except that an acrylic resin was applied using a bar coater and dried so that the heat seal layer had a thickness of 100 nm.

[0052] (Example 3) The product was manufactured in the same manner as in Example 1, except that an acrylic resin was applied using a bar coater and dried so that the heat seal layer had a thickness of 200 nm.

[0053] (Example 4) The product was manufactured in the same manner as in Example 1, except that an acrylic resin was applied using a bar coater and dried so that the heat seal layer had a thickness of 300 nm.

[0054] (Example 5) The product was manufactured in the same manner as in Example 1, except that an acrylic resin was applied using a bar coater and dried so that the heat seal layer had a thickness of 400 nm.

[0055] (Example 6) The conductive layer was prepared in the same manner as in Example 3, except that a dispersion of ATO was blended into a styrene-ethylene-butadiene copolymer resin so that ATO constituted 90% by mass.

[0056] (Example 7) The conductive layer was prepared in the same manner as in Example 3, except that a dispersion of ATO was blended into a styrene-ethylene-butadiene copolymer resin so that ATO constituted 70% by mass.

[0057] (Example 8) The product was manufactured in the same manner as in Example 1, except that an acrylic resin was applied using a bar coater and dried so that the heat seal layer had a thickness of 500 nm.

[0058] (Comparative Example 1) The heat seal layer was prepared in the same manner as in Example 3, except that an ATO dispersion was added to an acrylic resin dissolved in MEK so that ATO constituted 80% by mass.

[0059] (Comparative Example 2) The conductive layer was prepared in the same manner as in Example 3, except that a dispersion of ATO was blended into a styrene-ethylene-butadiene copolymer resin so that ATO constituted 60% by mass.

[0060] (Comparative Example 3) The product was manufactured in the same manner as in Example 1, except that an acrylic resin was applied using a bar coater and dried so that the heat seal layer had a thickness of 600 nm.

[0061] <Evaluation Method> The cover tapes prepared in each example and comparative example were evaluated as follows. The results are shown in Table 1. (1) Surface resistivity of the cover tape Using the Highresta UP MCP-HT450 manufactured by Nitto Seiko Analytech Co., Ltd., the surface resistivity of the heat-sealing layer side surface of the cover tape was evaluated according to the JIS K6911 method at an ambient temperature of 23°C, an ambient humidity of 50% RH, and an applied voltage of 10 V.

[0062] (2) Adhesion rate of components to the cover tape In an environment with an ambient temperature of 23°C and an ambient humidity of 50%RH, the cover tape, carrier tape, and 15 components were ionized and packaged. The components were then fixed in contact with the heat-sealed layer of the cover tape and vibrated in a Cute Mixer (manufactured by Tokyo Rikakikai Co., Ltd.) at a rotation speed of 2000 rpm for 10 minutes. The number of components adhering to the cover tape was evaluated when the cover tape was peeled off at a peeling speed of 600 mm / min and a peeling angle of 170-180 degrees, and the component adhesion rate was calculated. A conductive polystyrene carrier tape was used as the carrier tape. The following parts were used: (Component 1) DFN package with dimensions of 0.8mm (width) x 0.8mm (depth) x 0.4mm (thickness) and a weight of 0.6mg. (Component 2) BGA package with dimensions of 1.0mm (width) x 1.0mm (depth) x 0.4mm (thickness) and a weight of 1.5mg. A bonding rate of less than 5% was rated as "Excellent," a rate between 5% and 15% was rated as "Good," and a rate of 15% or more was rated as "Poor."

[0063] (3) Component voltage In an environment with an ambient temperature of 23°C and an ambient humidity of 50%RH, the cover tape, carrier tape, and 15 components were ionized and packaged. The components were then secured so that the heat-seal layer of the cover tape was in contact with them, and the mixture was vibrated in a Cute Mixer (manufactured by Tokyo Rikakikai Co., Ltd.) at a rotation speed of 2000 rpm for 10 minutes. After peeling off the carrier tape while the heat-seal layer of the cover tape was still in contact with the components, the components were grasped with ionized ceramic tweezers, and the voltage on the surface in contact with the heat-seal layer was measured. The average voltage of the 15 components was calculated using a voltmeter (manufactured by MONROE ELECTRONICS). A conductive polystyrene carrier tape was used as the carrier tape. The following parts were used: (Component 1) DFN package with dimensions of 0.8mm (width) x 0.8mm (depth) x 0.4mm (thickness) and a weight of 0.6mg. (Component 2) BGA package with dimensions of 1.0mm (width) x 1.0mm (depth) x 0.4mm (thickness) and a weight of 1.5mg.

[0064] [Table 1]

[0065] The following became clear from the results shown in Table 1. In all of the cover tapes in Examples 1 to 8, the rate of electronic component adhesion to the cover tape due to static electricity was 15% or less, indicating that adhesion to the cover tape was suppressed. This is presumed to be because the electrostatic attraction force generated inside the cover tape suppressed the electrostatic attraction force from the surface of the heat seal layer outwards. On the other hand, the adhesion rates of the cover tapes in Comparative Examples 1 and 2 were high, at least 25%, and could not be said to have been sufficiently suppressed. In particular, it is presumed that in the case of the cover tape in Comparative Example 1, induction charging occurred within the heat seal layer due to the presence of a conductive agent in the heat seal layer, generating an electric charge and thus generating electrostatic attraction. Furthermore, it is presumed that in the case of the cover tape in Comparative Example 2, induction charging within the conductive layer was difficult to occur due to the low content of the conductive agent in the conductive layer, and therefore the electrostatic attraction from the surface of the heat seal layer to the outside could not be suppressed. The adhesion rate of the cover tape in Comparative Example 3 was a high value of 20% in the case of part 1, and it could not be said that it was sufficiently suppressed.

[0066] Although the present invention has been described above using various embodiments, it goes without saying that the technical scope of the present invention is not limited to the embodiments described above. It will be obvious to those skilled in the art that various modifications or improvements can be made to the above embodiments. Furthermore, it is clear from the claims that such modified or improved forms may also be included within the technical scope of the present invention. [Industrial applicability]

[0067] The cover tape of this embodiment suppresses the generation of electrostatic attraction between the heat seal layer and the electronic component. Therefore, when peeling off the cover tape to remove the electronic component, there is less risk of the electronic component adhering to the cover tape, and thus it has industrial applicability. [Explanation of symbols]

[0068] 1 Cover tape 2 Heat seal layers 3. Conductive layer 4 Base material layer 5. Middle Class

Claims

1. A cover tape having an insulating heat seal layer provided on one surface and a conductive layer directly laminated on the heat seal layer, The surface resistivity of the heat seal layer is 1 × 10⁻⁶ １０ It is less than or equal to Ω / □, The average thickness of the heat seal layer is 30 to 250 nm. Cover tape.

2. The cover tape according to claim 1, wherein the conductive layer contains a resin and a conductive agent.

3. The cover tape according to claim 2, wherein the conductive agent is selected from the group consisting of conductive tin oxide particles, conductive polymers, and carbon nanomaterials.

4. The cover tape according to claim 2 or 3, wherein the conductive layer contains 65 to 95% by mass of a conductive agent, and the conductive agent is conductive tin oxide particles.

5. The cover tape according to claim 4, wherein the conductive tin oxide particles are antimond-doped tin oxide (ATO).

6. The cover tape according to claim 1 or 2, having a heat seal layer, a conductive layer, and a base layer in that order.

7. The cover tape according to claim 1 or 2, comprising a heat seal layer, a conductive layer, an intermediate layer, and a base layer in that order.

8. A cover tape according to claim 1 or 2, for use as a lid material for electronic component packaging.

9. An electronic component packaging comprising a carrier tape and a cover tape according to claim 1 or 2.

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