Cover film and electronic component packaging using the same

Abstract

The object of the present invention is to provide a cover film having a base layer and a heat seal layer, and having an antimony content of a certain level or less. [Solution] The cover film has a substrate layer and a heat seal layer, and is characterized by having an antimony content of less than 100 ppm as measured by ICP emission spectroscopy.

Description

[Technical Field]

[0001] The present invention relates to a cover film and an electronic component package using the same. [Background technology]

[0002] As electronic devices become smaller, the electronic components they use are also becoming smaller and more powerful. At the same time, automatic mounting of components onto printed circuit boards is becoming commonplace during the electronic device assembly process. Surface-mount electronic components are housed in a carrier tape with continuous pockets formed by thermoforming to fit the shape of the electronic components. After the electronic components are housed, a cover film is placed on top of the carrier tape as a lid, and both ends of the cover film are heat-sealed continuously along their length with a heated seal bar to create a package. In recent years, various electronic components such as capacitors, resistors, ICs, LEDs, connectors, and switching elements have become significantly smaller, lighter, and thinner. The smaller and lighter the electronic components stored in them become, the more likely they are to pop out due to vibrations generated when peeling the cover film from the carrier tape, causing problems in the mounting process. As a result, the performance requirements for peeling the cover film to remove the stored electronic components from the package are becoming stricter than ever before.

[0003] From the viewpoint of peel strength, etc., a cover film in which a heat-seal layer of a thermoplastic resin is laminated on a biaxially stretched polyester film substrate is commonly used (Patent Documents 1 and 2). The polyester film used as the substrate for these cover films uses an antimony compound such as antimony trioxide as a polymerization catalyst in its production, and the polyester film itself also contains antimony. Furthermore, some cover films use an antimony compound such as antimony-doped tin oxide as a conductive agent (Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-8152 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-173673 [Patent Document 3] International Publication No. 2012 / 143994 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, antimony compounds have been known to have adverse effects on the environment and the human body, and therefore, there is a demand for cover films that do not contain antimony compounds and are environmentally and humanly friendly. The present invention has been made in view of the above circumstances, and has an object to provide a cover film which has a base layer and a heat seal layer and has an antimony content of a certain level or less. [Means for solving the problem]

[0006] As a result of extensive research, the present inventors have found that a film containing an antimony compound at a certain level or less is suitable as a cover film, and have arrived at the present invention.

[0007] The present invention, which solves the above problems, comprises the following: [1] A cover film having a substrate layer and a heat seal layer, characterized in that the antimony content measured by ICP atomic emission spectrometry is less than 100 ppm. [2] The cover film according to [1], wherein the substrate layer contains at least one resin selected from the group consisting of polyester resins, polyolefin resins, and super engineering plastics synthesized using a catalyst that does not contain antimony. [3] The cover film according to [1] or [2], wherein the base layer comprises at least one film selected from the group consisting of biaxially oriented polyethylene terephthalate film, biaxially oriented polyethylene naphthalate film, and biaxially oriented polypropylene film. [4] A cover film according to any one of [1] to [3], which has an antistatic layer on the side of the heat seal layer opposite to the substrate layer side, the antistatic layer containing an acrylic acid ester copolymer and an antistatic agent, and the antistatic agent containing at least one selected from the group consisting of conductive inorganic compounds and conductive polymers. [5] The cover film according to any one of [1] to [4], wherein the heat seal layer contains an antistatic agent, and the antistatic agent comprises at least one selected from the group consisting of carbon nanotubes, polythiophenes, and phosphorus-doped tin oxide. [6] The cover film according to any one of [1] to [5], which is used as a lid material for packaging of electronic components. [7] An electronic component packaging body having a carrier tape containing a thermoplastic resin and a lid material using the cover film according to any one of [1] to [6]. [Effects of the Invention]

[0008] According to the present invention, there is provided a cover film having a base layer and a heat seal layer, and having an antimony content of a certain level or less. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a layer structure of a cover film according to a first embodiment of the present invention. [Figure 2] FIG. 4 is a cross-sectional view showing the layer structure of a cover film according to a second embodiment of the present invention. [Figure 3] FIG. 4 is a cross-sectional view showing the layer structure of a cover film according to a third embodiment of the present invention. [Figure 4] FIG. 10 is a cross-sectional view showing the layer structure of a cover film according to a fourth embodiment of the present invention. [Figure 5] FIG. 10 is a cross-sectional view showing the layer structure of a cover film according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, one embodiment of the present invention will be described in detail, but if a specific description given for one embodiment also applies to other embodiments, the description will be omitted in the other embodiments. Furthermore, the present invention is not limited to the following embodiment, and can be implemented by making appropriate changes within the scope that does not impair the effects of the present invention.

[0011] [First embodiment] The cover film according to the first embodiment of the present invention has a base layer and a heat seal layer, and has an antimony content of less than 100 ppm as measured by ICP atomic emission spectroscopy. Fig. 1 shows a cross-sectional conceptual diagram of the cover film according to the first embodiment. The cover film shown in Fig. 1 has a base layer 2 and a heat seal layer 3 provided in this order.

[0012] (A) Base material layer As shown in FIG. 1, the base layer is one of the layers that make up the cover film.

[0013] In one embodiment of the present invention, the substrate layer may be made of a resin containing at least one of polyester resin, polyolefin resin, and super engineering plastic.

[0014] 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. The polyester polyol preferably has a hydroxyl value (mgKOH / g) of 1 to 200 and a number-average molecular weight of 1,000 to 50,000. The number-average molecular weight referred to here is a value measured according to JIS K7252. Examples of polyester polyols include condensation reaction products of polyhydroxyl group-containing compounds with ester-forming derivatives, such as polycarboxylic acids or anhydrides and their lower alkyl (alkyl groups having 1 to 4 carbon atoms) esters. More specifically, examples thereof include polyethylene terephthalate, polyethylene naphthalate, polyarylate, polyethylene-2,6-naphthalate, polymethylene terephthalate, and polyester resins copolymerized with copolymer components such as diol components, e.g., diethylene glycol, neopentyl glycol, and polyalkylene glycol, and dicarboxylic acid components, e.g., adipic acid, sebacic acid, phthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. When a polyester-based resin is combined with another resin, the content of the polyester-based resin is not particularly limited, but for example, the polyester-based resin can be 50% by mass or more, 70% by mass or more, or 90% by mass or more in the thermoplastic resin.

[0015] Examples of polyolefin resins include polyethylene resins and polypropylene resins. Examples of polyethylene-based resins that can be used include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and linear medium-density polyethylene. Not only simple substances but also copolymers, graft compounds, and blends having these structures can be used. Examples of the latter resins include those copolymerized with a monomer having a polar group in the polyethylene chain, and blends thereof. Examples of the polyethylene copolymerized with a monomer having a polar group 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 with acid anhydrides.

[0016] Furthermore, examples of polypropylene-based resins that can be used include homopolypropylene, random polypropylene, and block polypropylene. 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, and 1-decene. When block polypropylene is used, a block copolymer (block polypropylene), a block copolymer containing a rubber component, or a graft copolymer can be used. These olefin resins can be used alone or in combination with other olefin-based resins. When a polyolefin-based resin is combined with another resin, the content of the polyolefin-based resin is not particularly limited, but for example, the polyolefin-based resin can be 50% by mass or more, 70% by mass or more, or 90% by mass or more in the thermoplastic resin.

[0017] 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 super engineering plastics are combined with other resins, the content of the super engineering plastics is not particularly limited, but for example, the content of the super engineering plastics in the resin can be 50% by mass or more, 70% by mass or more, or 90% by mass or more.

[0018] In one embodiment of the present invention, the polymerization catalyst used in the production of the polyester film is preferably an antimony-free catalyst, and examples of such catalysts that can be used include aluminum-based catalysts, titanium-based catalysts, germanium-based catalysts, etc. The term "antimony-free catalyst" means that the catalyst is substantially free of antimony, and does not exclude the inclusion of antimony as an unavoidable impurity.

[0019] The film used as the substrate layer may be unstretched, uniaxially stretched, or biaxially stretched.

[0020] The average thickness of the base layer is preferably 5 μm to 100 μm, more preferably 10 μm to 80 μm, and even more preferably 12 μm to 30 μm. By making the thickness of the base layer 5 μm or more, the tensile strength of the cover film itself is reduced, which can prevent "film breakage" when the cover film is peeled off. On the other hand, by making the thickness 100 μm or less, it is possible to prevent a decrease in heat sealability to the carrier tape and an increase in costs.

[0021] The amount of antimony compounds contained in the substrate layer can be measured by ICP atomic emission spectrometry, and the content of elemental antimony is preferably less than 100 ppm, more preferably less than 50 ppm, even more preferably less than 10 ppm, and most preferably no antimony is contained. Measurements by "ICP atomic emission spectroscopy" (inductively coupled plasma atomic emission spectroscopy) in this specification can be carried out using an ICP atomic emission spectroscopy analyzer (e.g., CIROS-120 manufactured by Rigaku Corporation) after decomposing the sample by acid decomposition or dry decomposition.

[0022] (B) Heat seal layer As shown in FIG. 1, the heat seal layer is one layer that, together with the base layer, constitutes the cover film. The heat seal layer is preferably composed primarily of a thermoplastic resin, where "composed primarily of" means that the resin contains 50% by mass or more, 70% by mass or more, or 90% by mass or more of the thermoplastic resin. As the thermoplastic resin, a styrene-acrylic copolymer is used. The styrene-acrylic copolymer is a copolymer essentially composed of a styrene-based monomer and a (meth)acrylic monomer. Examples of the styrene-based monomer include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, and p-phenylstyrene, with styrene being particularly preferred. These styrene-based monomers can be used alone or in combination of two or more. Examples of the (meth)acrylic monomer 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 alone or in combination of two or more. In addition to the styrene-based monomer and the (meth)acrylic monomer, a small amount of other monomer copolymerizable with these monomers may also be copolymerized.

[0023] The resin primarily composed of a styrene-acrylic copolymer exhibits excellent heat-sealing properties with respect to materials constituting the carrier tape, such as polystyrene and polycarbonate. In particular, a resin primarily composed of a styrene-acrylic copolymer having a mass-average molecular weight of 5,000 to 20,000, preferably 10,000 to 20,000, is used. A mass-average molecular weight of 5,000 or greater reduces mounting problems, such as adhesion of stored components to the heat-seal layer due to tackiness. On the other hand, a mass-average molecular weight of less than 20,000 reduces breakage due to a significant increase in peel strength when the peeling speed is increased. Furthermore, the glass transition temperature of the styrene-acrylic copolymer is preferably 70°C to 100°C. At temperatures below 70°C, there is a risk of stored components adhering to the heat-sealed surface of the cover film during transport, such as by sea.

[0024] The average thickness of the heat seal layer is in the range of 3 μm to 70 μm, preferably 10 μm to 50 μm, and more preferably 15 μm to 45 μm. By making the thickness of the heat seal layer 3 μm or more, the heat seal layer can exhibit sufficient peel strength. On the other hand, by making the thickness of the heat seal layer 70 μm or less, not only can an increase in cost be suppressed but also variations in peel strength when peeling off the cover film can be suppressed.

[0025] The amount of antimony compound contained in the heat seal layer can be measured by ICP atomic emission spectroscopy, and the content of elemental antimony is preferably less than 50 ppm, more preferably less than 20 ppm, even more preferably less than 5 ppm, and most preferably no antimony is contained.

[0026] Furthermore, in one embodiment of the present invention, the cover film contains an inorganic filler in the heat seal layer. The cover film of this embodiment, when heat-sealed to the surface of a carrier tape containing electronic components, may be baked for approximately 72 hours at 60°C or 24 hours at 80°C to remove moisture from the encapsulating resin. If the electronic components adhere to the cover film in this case, problems may occur during the process of peeling the cover film and mounting the electronic components. The cover film of this embodiment exhibits minimal variation in peel strength when peeling the cover film, and the adhesiveness of the heat seal layer to the electronic components at high temperatures, such as 60-80°C, can be controlled, significantly eliminating the problem of electronic component adhesion. However, adding an inorganic filler to the heat seal layer more reliably prevents adhesion. The inorganic filler added here may be any type as long as it effectively prevents adhesion. Examples include spherical or crushed talc particles, silica particles, alumina particles, mica particles, calcium carbonate, magnesium carbonate, and the like. To maintain the transparency of the cover film, the inorganic filler has a median diameter (D50) of less than 200 nm, and is contained in an amount of, for example, 10 to 50 parts by mass.

[0027] Furthermore, in one embodiment of the present invention, the heat seal layer contains an antistatic agent, and the surface resistivity thereof is 1×10 12 Less than 1×10 Ω 9 Less than Ω or 1×10 7 It is also possible to configure the antistatic property so that it is less than Ω. Alternatively, in another embodiment, an antistatic layer is not formed, and an antistatic agent can be contained in the heat seal layer (B). Here, the type and amount of the antistatic agent to be contained are the same as those described in the second embodiment below for the case where the antistatic agent is contained in the antistatic layer.

[0028] (cover film) In this embodiment, the average thickness of the cover film is preferably 30 μm to 100 μm, more preferably 45 μm to 80 μm, and even more preferably 40 μm to 70 μm. By making the average thickness of the cover film 30 μm or more, it is possible to prevent the cover film from being torn when peeled off. On the other hand, by making the average thickness of the cover film 100 μm or less, it is possible to not only suppress an increase in costs but also improve productivity by shortening the sealing time.

[0029] The amount of antimony compounds contained in the cover film can be measured by ICP atomic emission spectroscopy, and the content of elemental antimony is less than 100 ppm, preferably less than 50 ppm, more preferably less than 20 ppm, and most preferably no antimony is contained.

[0030] [Second embodiment] In a cover film according to one embodiment of the present invention, an antistatic layer is provided on the surface of the heat seal layer opposite to the substrate layer side, as shown in Fig. 2. In other words, the substrate layer 2, heat seal layer 3, and antistatic layer 4 are provided in this order.

[0031] (C) Antistatic layer The antistatic layer in this embodiment contains an antistatic agent. Examples of the antistatic agent include conductive inorganic compounds and conductive polymers. More specifically, magnesium silicate, smectite (e.g., montmorillonite, beidellite, nontronite, hectorite, and savonite), carbon nanotubes, polythiophene, phosphorus-doped tin oxide, quaternary ammonium salts, and spherical ATO, or a combination thereof, is preferably used. The content of the antistatic agent relative to the total components constituting the antistatic layer is preferably 40 to 80% by mass. When the content is 40% by mass or more, antistatic performance is easily exhibited, and when the content is 80% by mass or less, deterioration of adhesion with the heat seal layer is suppressed.

[0032] The antistatic layer may further contain a thermoplastic resin as a binder component. Suitable examples of such thermoplastic resins include polyurethane resins, acrylic resins, polyvinyl chloride resins, ethylene-vinyl acetate resins, polyester resins, butadiene resins, styrene resins, and acrylic-modified polyester resins, with acrylic ester copolymers being more preferred.

[0033] The average thickness of the antistatic layer is preferably 0.02 μm to 2 μm, more preferably 0.05 μm to 1.5 μm, and even more preferably 0.1 μm to 1.2 μm. By setting the thickness of the antistatic layer to 0.02 μm or more, sufficient antistatic performance is easily achieved, while by setting the thickness of the antistatic layer to 2 μm or less, the risk of the antistatic layer itself being detached due to cohesive failure of the antistatic layer and becoming a problem as foreign matter is reduced. Note that the antistatic layer is usually formed by applying a liquid in which the various components constituting the antistatic layer are dissolved or dispersed, or by applying an emulsion of the various components constituting the antistatic layer. When formed by a coating method, the thickness referred to here is the thickness after drying.

[0034] The amount of antimony compound contained in the antistatic layer can be measured by ICP atomic emission spectroscopy, and the content in terms of elemental antimony is preferably less than 50 ppm, more preferably less than 20 ppm, even more preferably less than 5 ppm, and most preferably no antimony is contained.

[0035] [Third embodiment] In a cover film according to one embodiment of the present invention, as shown in Fig. 3, an intermediate layer 5 is provided between the base material layer 2 and the heat seal layer 3. In other words, the base material layer 2, the intermediate layer 5, and the heat seal layer 3 are provided in this order.

[0036] (D) Middle layer As the resin constituting the intermediate layer, linear low-density polyethylene (hereinafter referred to as LLDPE) can be suitably used, which has flexibility and moderate rigidity and excellent tear strength at room temperature. In particular, a resin having a density of 0.900 to 0.925 (×10 3 kg / m 3 ) resin is used, the intermediate layer resin is less likely to protrude from the edge of the cover film due to the heat and pressure during heat sealing, which makes it less likely for the iron to get dirty during heat sealing. In addition, the intermediate layer softens when the cover film is heat sealed, which reduces uneven contact with the heat sealing iron, making it easier to obtain stable peel strength when peeling the cover film.

[0037] LLDPE includes those polymerized with Ziegler catalysts and those polymerized with metallocene catalysts (hereinafter referred to as m-LLDPE). m-LLDPE has a narrowly controlled molecular weight distribution, which gives it particularly high tear strength, making it suitable for use in the intermediate layer of the present invention.

[0038] The m-LLDPE is a copolymer of ethylene and an olefin having 3 or more carbon atoms, preferably a linear, branched, or aromatic nucleus-substituted α-olefin 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 aromatic nucleus-substituted monoolefins include styrene. These comonomers can be copolymerized with ethylene either alone or in combination. In this copolymerization, polyenes such as butadiene, isoprene, 1,3-hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, etc. may be copolymerized. Among them, those using 1-hexene or 1-octene as a comonomer are preferred because they have high tensile strength and are cost-effective.

[0039] The average thickness of the intermediate layer is preferably 3 μm to 70 μm, more preferably 5 μm to 60 μm, even more preferably 10 μm to 50 μm, and most preferably 15 μm to 35 μm. By making the thickness of the intermediate layer 3 μm or more, it is possible to prevent the adhesive strength between the base layer and the intermediate layer from becoming insufficient, and also to reduce uneven contact with the hot iron when heat-sealing the cover film to the carrier tape. On the other hand, by making the thickness 70 μm or less, it is possible to prevent the total thickness of the cover film from becoming too thick, resulting in insufficient peel strength when heat-sealing the cover film to the carrier tape.

[0040] The amount of antimony compound contained in the intermediate layer can be measured by ICP atomic emission spectroscopy, and the content of elemental antimony is preferably less than 50 ppm, more preferably less than 20 ppm, even more preferably less than 5 ppm, and most preferably no antimony is contained.

[0041] [Fourth embodiment] As shown in FIG. 4, the cover film of one embodiment of the present invention is composed of a base material layer 2, an intermediate layer 5, a heat seal layer 3, and an antistatic layer 4 in this order.

[0042] [Fifth embodiment] As shown in FIG. 5, the cover film of one embodiment of the present invention is composed of a base material layer 2, an adhesive layer 6, an intermediate layer 5, a heat seal layer 3, and an antistatic layer 4 in this order.

[0043] (adhesive layer) In view of ease of handling, a photocurable adhesive composition can be preferably used as the adhesive layer in this embodiment. Furthermore, as the adhesive composition, an adhesive composition that cures when irradiated with light such as ultraviolet light and softens when heated to a high temperature can be preferably used. Such adhesive compositions include, for example, adhesive compositions containing a polyfunctional (meth)acrylate and a monofunctional (meth)acrylate.

[0044] As the polyfunctional (meth)acrylate, a polyfunctional (meth)acrylate oligomer / polymer having two or more (meth)acryloyl groups at the end or side chain of the oligomer / polymer, or a polyfunctional (meth)acrylate monomer having two or more (meth)acryloyl groups can be used. Examples of polyfunctional (meth)acrylate oligomers / polymers include 1,2-polybutadiene-terminated urethane (meth)acrylates (e.g., "TE-2000" and "TEA-1000" manufactured by Nippon Soda Co., Ltd.), hydrogenated products thereof (e.g., "TEAI-1000" manufactured by Nippon Soda Co., Ltd.), 1,4-polybutadiene-terminated urethane (meth)acrylates (e.g., "BAC-45" manufactured by Osaka Organic Chemical Industry Co., Ltd.), polyisoprene-terminated (meth)acrylates, polyester-based urethane (meth)acrylates (e.g., "UV-2000B," "UV-3000B," and "UV-7000B" manufactured by Nippon Synthetic Chemical Industry Co., Ltd., and "KHP-11" and "KHP-17" manufactured by Negami Chemical Industrial Co., Ltd.), polyether-based urethane (meth)acrylates (e.g., "UV-3700B" and "UV-6100B" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), and bisphenol A-type epoxy (meth)acrylates. Among these, polyester-based urethane (meth)acrylates and / or polyether-based urethane (meth)acrylates are preferred, with polyester-based urethane (meth)acrylates being more preferred. Here, the urethane (meth)acrylate refers to a urethane (meth)acrylate obtained by reacting a polyol compound with an organic polyisocyanate compound.

[0045] Examples of polyol compounds include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, 1,4-butanediol, polybutylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2,2-butylethyl-1,3-propanediol, neopentyl glycol, cyclohexanedimethanol, hydrogenated bisphenol A, polycaprolactone, trimethylolethane, trimethylolpropane, polytrimethylolpropane, pentaerythritol, polypentaerythritol, sorbitol, mannitol, glycerin, poly Examples of suitable polyols include polyhydric alcohols such as diglycerin and polytetramethylene glycol, polyether polyols having at least one structure of polyethylene oxide, polypropylene oxide, or block or random copolymerization of ethylene oxide / propylene oxide, polyester polyols which are condensates of such polyhydric alcohols or polyether polyols with polybasic acids such as maleic anhydride, maleic acid, fumaric acid, itaconic anhydride, itaconic acid, adipic acid, and isophthalic acid, caprolactone-modified polyols such as caprolactone-modified polytetramethylene polyol, polyolefin polyols, polycarbonate polyols, polybutadiene polyols, polyisoprene polyols, hydrogenated polybutadiene polyols, hydrogenated polyisoprene polyols, and silicone polyols such as polydimethylsiloxane polyol. Among these, polyether polyols and / or polyester polyols are more preferred.

[0046] The organic polyisocyanate compound is not particularly limited, but examples of polyisocyanates that can be used include aromatic, aliphatic, alicyclic, and alicyclic polyisocyanates, and among these, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hydrogenated diphenylmethane diisocyanate (H-MDI), polyphenylmethane polyisocyanate (crude MDI), modified diphenylmethane diisocyanate (modified MDI), hydrogenated xylylene diisocyanate (H-XDI), and xylylene diisocyanate are particularly preferred. Suitable examples of suitable isocyanates include polyisocyanates such as hexamethylene diisocyanate (HMDI), trimethylhexamethylene diisocyanate (TMXDI), tetramethylxylylene diisocyanate (m-TMXDI), isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI), and 1,3-bis(isocyanatomethyl)cyclohexane (H6XDI), as well as trimer compounds of these polyisocyanates and reaction products of these polyisocyanates with polyols. Among these, hydrogenated xylylene diisocyanate (H-XDI) and / or isophorone diisocyanate (IPDI) are preferred.

[0047] When using the above-mentioned two-component curing adhesive, it is preferable to dilute it in a solvent and then mix it in a predetermined ratio before use. The dilution solvent is not particularly limited, and water, ethyl acetate, toluene, methyl ethyl ketone, etc. can be used. The adhesive layer is formed by applying the two-component curing adhesive to the substrate layer and then drying it.

[0048] The average thickness of the adhesive layer is preferably 0.1 μm to 5 μm, more preferably 0.2 μm to 3 μm, and even more preferably 0.3 μm to 1 μm. By setting the thickness to 0.1 μm or more, it is possible to prevent insufficient adhesive strength, and by setting the thickness to 5 μm or less, it is possible to further prevent large variations in peel strength after heat sealing to a carrier tape. Note that when formed by a coating method, the thickness referred to here is the thickness after drying.

[0049] The amount of antimony compounds contained in the adhesive layer can be measured by ICP atomic emission spectroscopy, and the content of elemental antimony is preferably less than 50 ppm, more preferably less than 20 ppm, even more preferably less than 5 ppm, and most preferably no antimony is contained.

[0050] [Cover film manufacturing method] The method for producing the cover film is not particularly limited, and a general method can be used. For example, an adhesive is applied to the film surface of the base layer, and a resin composition for the intermediate layer is extruded from a T-die and coated on the surface coated with the anchor coating agent to form a two-layer film consisting of a base layer and an intermediate layer. Furthermore, the resin composition for the heat seal layer is coated on the intermediate layer using, for example, a gravure coater, a reverse coater, a kiss coater, an air knife coater, a Mayer bar coater, a dip coater, etc., to obtain the desired cover film.

[0051] Alternatively, the heat seal layer may be formed in advance by a T-die casting method or an inflation method, and then this may be bonded to the base layer via an adhesive by a dry lamination method to obtain a film consisting of the base layer and the heat seal layer.

[0052] In addition to the above steps, an antistatic layer can be formed on the heat seal layer, if necessary. The composition containing the antistatic agent can be applied by a roll coater using a gravure roll, a lip coater, a spray, or the like.

[0053] [Application] The cover film can be used as a lid material for carrier tape, which is a container for storing electronic components. Carrier tape is a strip-shaped material approximately 8 mm to 100 mm wide with pockets for storing electronic components. When heat-sealing the cover film as a lid material, the material constituting the carrier tape is not particularly limited, and commercially available products can be used, such as thermoplastic resins such as polystyrene, polyester, polycarbonate, and polyvinyl chloride. When an acrylic resin is used for the heat-seal layer, it is preferably combined with a polystyrene or polycarbonate carrier tape. The carrier tape can be made conductive by kneading carbon black or carbon nanotubes into the resin, or by kneading an antistatic agent or conductive material into the resin. Alternatively, the carrier tape can be made antistatic by applying a coating liquid in which a surfactant-type antistatic agent or a conductive material such as polypyrrole or polythiophene is dispersed in an organic binder such as acrylic.

[0054] A package containing electronic components can be obtained, for example, by storing electronic components, etc. in an electronic component storage section of a carrier tape, then using a cover film as a lid, continuously heat-sealing both longitudinal edges of the cover film to package the components, and winding the tape onto a reel. Packaging in this form allows electronic components, etc. to be stored and transported. The package containing electronic components, etc. is transported using holes called sprocket holes for carrier tape transport provided on the longitudinal edges of the carrier tape, while the cover film is intermittently peeled off. The components, etc. are removed using a component mounting device while checking the presence, orientation, and position of the electronic components, etc., and are then mounted on a board.

[0055] Furthermore, when peeling off the cover film, if the peel strength is too small, it may peel off from the carrier tape and the stored components may fall off, while if the peel strength is too large, it will be difficult to peel off from the carrier tape and there is a risk that the cover film will break when peeled off. Therefore, when heat-sealed at 120 to 220°C, the peel strength should preferably be 0.15 N or more but less than 1.5 N, and more preferably 0.2 N or more but less than 0.8 N. [Example]

[0056] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0057] The various raw materials used in the examples are as follows: (A) Base material layer (a-1) Biaxially stretched polyethylene terephthalate film: Made of polyethylene terephthalate resin using an aluminum catalyst, Toyobo Ester GS (manufactured by Toyobo Co., Ltd.), thickness 16 μm (a-2) Biaxially stretched polyethylene terephthalate film: Made of polyethylene terephthalate resin using a titanium catalyst, thickness 16 μm (a-3) Biaxially stretched polyethylene naphthalate film: Made of polyethylene naphthalate resin using an aluminum catalyst, thickness 16 μm (a-4) Polyarylate film: T-240AF (manufactured by Unitika Ltd.), thickness 16 μm (a-5) Polyphenylene sulfide filler: P3010 (BASF), thickness 16 μm (a-6) Biaxially oriented polypropylene film: FOA (manufactured by Futamura Chemical Co., Ltd.), thickness 25 μm (a-7) Biaxially stretched polyethylene terephthalate film: Made of polyethylene terephthalate resin using an antimony catalyst, E-5100 (manufactured by Toyobo Co., Ltd.), thickness 16 μm

[0058] (B) Heat seal layer (b-1) Styrene-butadiene copolymer film: Clearen 335A (manufactured by Denka Co., Ltd.), thickness 35 μm (b-2) LLDPE film: LC-2T (manufactured by Tamapoly Co., Ltd.), thickness 35 μm

[0059] (C) Antistatic layer (c-1) Acrylic acid ester copolymer: EC242 (manufactured by Shin-Nakamura Chemical Co., Ltd.) (c-2) Polyester resin: S-680EA (manufactured by Takamatsu Oil Co., Ltd.) (c-3) Carbon nanotubes: antistatic agent, S grade (manufactured by Nippon Shizai Co., Ltd.) (c-4) Polythiophene: antistatic agent, PEDOT, P342ST (manufactured by Nagase ChemteX Corporation) (c-5) Phosphorus-doped tin oxide: antistatic agent, SP-2 (manufactured by Mitsubishi Materials Electronics Co., Ltd.) (c-6) Quaternary ammonium salt: antistatic agent, Bondip PM (Konishi Co., Ltd.) (c-7) Spherical ATO: SN100D (Ishihara Sangyo Kaisha)

[0060] (adhesive layer) Main ingredient: TM-319 (manufactured by Toyo-Morton Co., Ltd.), polyether polyol, ethyl acetate solution, solids concentration 70% by mass, 103 kg / m 3 Hardener components in adhesive layer: Hardener: CAT-11B (manufactured by Toyo-Morton Co., Ltd.), diphenylmethane diisocyanate, ethyl acetate solution, solids concentration 60% by mass

[0061] [Example 1] The raw material for the heat seal layer (Clearen 335A) was extruded from a single-screw extruder and formed into a film having a thickness of 35 μm. Next, a two-component curing adhesive consisting of a polyether polyol (manufactured by Toyo Morton, "TM-319") as the base material and a diphenylmethane diisocyanate-based curing agent (manufactured by Toyo Morton, "CAT-11B") as the main component was mixed in a solids ratio of 50 (base material): 50 (curing agent) using the gravure method on the side that would be bonded to the heat seal layer of the base material layer, biaxially oriented polyethylene terephthalate film (Toyobo Ester GS, thickness 16 μm). An adhesive layer was formed so that the thickness after drying would be 3 μm. This was then bonded to the heat seal layer using the dry lamination method and stored at 40°C for one day to obtain a cover film for carrier tape of electronic components.

[0062] [Comparative Example 1] Comparative Example 1 was produced in the same manner as in Example 1, except that the type of (A) base layer was changed, to obtain a cover film for carrier tape of electronic components.

[0063] [Example 2] After bonding the base layer and heat seal layer together in the same manner as in Example 1, an acrylic acid ester copolymer (manufactured by Shin-Nakamura Chemical Co., Ltd., "EC-242") and an antistatic agent, carbon nanotubes (manufactured by Nippon Shizai Co., Ltd., "S Grade"), were mixed in a ratio of 90:10 in terms of solid content on the surface of the heat seal layer, and the mixture was applied by gravure coating to form an antistatic layer with a thickness of 0.5 μm after drying, thereby obtaining a cover film for carrier tape of electronic components.

[0064] [Examples 3-7, Comparative Example 2] Examples 3 to 7 and Comparative Example 2 were produced in the same manner as in Example 2, except that the type of base layer was changed, to obtain cover films for carrier tapes of electronic components.

[0065] [Examples 8-10, Comparative Example 3] Examples 8 to 10 and Comparative Example 3 were prepared in the same manner as Example 2, except that the type of antistatic agent in the antistatic layer was changed from carbon nanotubes and the ratio of the acrylic acid ester copolymer to the antistatic agent was changed to 20:80 in terms of solid content, to obtain cover films for carrier tapes of electronic components.

[0066] [Example 11] Example 11 was produced in the same manner as Example 2 except that the type of heat seal layer was changed, to obtain a cover film for carrier tape of electronic components.

[0067] [Example 12] Example 12 was produced in the same manner as in Example 2, except that the acrylic acid ester copolymer in the antistatic layer was changed to a polyester resin, to obtain a cover film for a carrier tape of electronic parts.

[0068] (Other implementation) The heat seal layer was adjusted to a thickness of 20 μm, and an intermediate layer (m-LLDPE: "Yumerit 2040F" manufactured by Ube Maruzen Polyethylene Co., Ltd.) was provided between the base layer and the heat seal layer.

[0069] <Evaluation method> The cover films for carrier tapes of electronic components produced in each of the Examples and Comparative Examples were evaluated as follows. The results are summarized in Tables 1 and 2.

[0070] (1) Antimony content The cover film was decomposed by acid decomposition, and then quantitative analysis was carried out using an ICP emission spectrometer CIROS-120 (manufactured by Rigaku Corporation). "3": Antimony was less than 100 ppm "1": Antimony was 100 ppm or more

[0071] (2) Antistatic Using a Hiresta UP MCP-HT450 (manufactured by Mitsubishi Chemical Corporation), the surface resistivity (Ω / □) of the heat seal layer or antistatic layer was evaluated according to the method of JIS K6911 at an ambient temperature of 23°C, an ambient humidity of 50% RH, and an applied voltage of 500V. "3": Surface resistivity was less than 1.0 x 10 to the 10th power "2": Surface resistivity was 1.0 x 10 to the 10th power or more but less than 1.0 x 10 to the 13th power "1": Surface resistivity was 1.0 x 10 to the power of 13 or more

[0072] (3) Sealing Using a taping machine (Nagata Seiki Co., Ltd., NK-600), a 21.5 mm wide cover film was heat-sealed to a 24 mm wide polycarbonate carrier tape (Denka Co., Ltd.) using a sealing iron with a 0.5 mm width, 24 mm length, 0.5 kgf sealing pressure, 12 mm feed length, and 0.3 second sealing time twice. The temperature of the sealing iron was varied from 140°C to 190°C in 10°C intervals. After 24 hours of storage at 23°C and 50% relative humidity, the cover film was peeled at a speed of 300 mm per minute and a peel angle of 170° to 180°, also at 23°C and 50% relative humidity. Sealing performance was evaluated based on the average peel strength when heat-sealed at a sealing iron temperature of 170°C. Peel strength was measured on three samples. "3": Average peel strength is 0.2N or more but less than 0.8N "2": Average peel strength is 0.15N or more but less than 0.2N, or 0.8N or more but less than 1.5N "1": Average peel strength is less than 0.15N or 1.5N or more

[0073] [Table 1]

[0074] [Table 2] [Explanation of symbols]

[0075] 1 Cover film 2 Base material layer 3 Heat-seal layer 4 Antistatic layer 5. Middle class 6 Adhesive layer

Claims

1. A cover film having a base layer containing a polyester resin and a heat seal layer, characterized in that the antimony content measured by ICP atomic emission spectroscopy is less than 100 ppm, and having an antistatic layer on the surface of the heat seal layer opposite to the base layer side, the average thickness of the antistatic layer being 0.5 μm to 2 μm, the heat seal layer contains a styrene-butadiene copolymer, the antistatic layer contains an acrylic ester copolymer and carbon nanotubes; Cover film.

2. The cover film according to claim 1 , wherein the substrate layer comprises at least one film selected from the group consisting of a biaxially oriented polyethylene terephthalate film, a biaxially oriented polyethylene naphthalate film, and a biaxially oriented polypropylene film.

3. The cover film according to claim 1 or 2, which is used as a lid material for packaging of electronic components.

4. An electronic component packaging body comprising a carrier tape containing a thermoplastic resin and a lid material using the cover film according to any one of claims 1 to 3.

5. The cover film according to claim 1 , wherein the average peel strength measured by the following method is 0.35 N or more and 0.6 N or less. (Measurement method) Using a taping machine, a 21.5 mm wide cover film was heat-sealed to a 24 mm wide polycarbonate carrier tape at a sealing iron temperature of 170°C with a seal head width of 0.5 mm x 2, a seal head length of 24 mm, a sealing pressure of 0.5 kgf, a feed length of 12 mm, and a sealing time of 0.3 seconds x 2. The seal iron was then left to stand for 24 hours in an atmosphere of 23°C and 50% relative humidity, after which the cover film was peeled off at a speed of 300 mm per minute and a peel angle of 170° to 180° in the same atmosphere of 23°C and 50% relative humidity. This test was performed three times, and the average value was taken as the average peel strength.

Images