Cover tape and electronic component package including the same

Abstract

To provide a cover tape which has little moisture absorption even under high temperature and low humidity, and an electronic component package including the same.SOLUTION: A cover tape has transmittance at a wavelength of 1,300 to 1,500 nm of more than 80%. Preferably, the cover tape has transmittance at a wavelength of 1,200 to 1,600 nm of 85% or more. Preferably, an increase / decrease rate of transmittance (T2) at a wavelength of 1,600 nm to transmittance (T1) at a wavelength of 1,200 nm, which is represented by the following expression (1), is 90% or more. Expression (1): (T2 / T1)×100(%).SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] As electronic devices become smaller, the electronic components used are also becoming smaller and more powerful. At the same time, electronic components are being automatically mounted on printed circuit boards during the assembly process of electronic devices. These chip-type surface-mount electronic components are housed in a carrier tape with a series of thermoformed storage pockets formed to fit the shape of the electronic components. After the electronic components are housed in each storage pocket, a cover tape is placed on top of the carrier tape as a lid, and both ends of the cover tape are heat-sealed continuously in the longitudinal direction with a heated sealing iron to form a package for the electronic components.

[0003] Incidentally, cover tapes may be exposed to high temperatures and humidity during transportation and storage, which can cause the cover tape to absorb moisture. If the moisture absorption rate of the cover tape becomes too high, problems such as blocking may occur in the rolled cover tape and reduced heat sealing properties may occur. Furthermore, if the cover tape absorbs moisture after being used as an electronic component package, there is a concern that this may affect the enclosed electronic components.

[0004] To address this issue, for example, Patent Document 1 proposes a cover tape that is less likely to cause blocking even when exposed to high temperature or high temperature and humidity environments. However, as a result of investigations by the present inventors, it has been found that the cover tape absorbs moisture even under high temperature and low humidity conditions, which makes it prone to the above-mentioned problems. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2013 / 054867 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present invention is to provide a cover tape that absorbs little moisture even under high temperature and low humidity conditions, and an electronic component package including the same. [Means for solving the problem]

[0007] As a result of extensive research into the above-mentioned problems, the inventors of the present invention have surprisingly found that there is a correlation between the transmittance and moisture absorption rate of a cover tape in the near-infrared wavelength range. That is, they have found that a cover tape with a transmittance of more than 80% in the wavelength range of 1300 to 1500 nm is less likely to absorb moisture even under high temperature and low humidity conditions. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a cover tape that absorbs little moisture even under high temperature and low humidity conditions, and an electronic component package including the same. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a graph showing transmittance measurement results for cover tapes of Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present disclosure will be described in detail below. However, the scope of the present disclosure is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the present disclosure. Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. Furthermore, when multiple upper and lower limits are described for a particular parameter, any of these upper and lower limits can be combined to form a suitable numerical range. Furthermore, the lower and / or upper limits of a numerical range described in this disclosure are numerical values ​​within that range and may be replaced with numerical values ​​shown in the examples. The expression "X to Y" indicating a numerical range means "X or more and Y or less." If a specific description described for one embodiment also applies to other embodiments, that description may be omitted in other embodiments.

[0011] The configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible as appropriate without departing from the spirit of the present disclosure. The present disclosure is not limited to the embodiments. Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification.

[0012] [Cover tape] A first embodiment of the present disclosure relates to a cover tape. The cover tape according to the first embodiment has a transmittance of more than 80% at wavelengths of 1300 to 1500 nm. Wavelengths of 1300 to 1500 nm are light in the near-infrared wavelength range. Thus, the cover tape according to the first embodiment, which has a transmittance of more than 80% in the near-infrared wavelength range, is less likely to absorb moisture even under high temperature and low humidity conditions. In the present disclosure, "a transmittance of more than 80% at wavelengths of 1300 to 1500 nm" means that the cover tape has a transmittance of more than 80% at any point within that wavelength range, which is different from an average transmittance of more than 80% in that wavelength range. <Transmittance measurement method> The measurement and analysis equipment used is an ultraviolet-visible-near-infrared spectrophotometer (e.g., Shimadzu Corporation, product name "UV-3600") and a multipurpose large sample chamber (φ60 mm, with built-in integrating sphere; e.g., Shimadzu Corporation, product name "MPC-3100"). First, baseline correction is performed without cover tape, then cover tape is attached and the spectral transmittance is measured using the integrating sphere at wavelengths of 1200 to 1600 nm. The transmittance of the cover tape in the present disclosure is determined by rounding the transmittance measured by the above-described measurement method to one decimal place.

[0013] In one embodiment, from the viewpoint of easily obtaining a cover tape with less moisture absorption under high temperature and low humidity conditions, the transmittance at wavelengths of 1300 to 1500 nm may be 83% or more, 85% or more, or even 88% or more. In another embodiment, the transmittance at the wavelength range may be 90% or more. Note that, from the viewpoint of easily obtaining a cover tape with less moisture absorption under high temperature and low humidity conditions due to high transmittance at wavelengths of 1300 to 1500 nm, the upper limit of the transmittance at wavelengths of 1300 to 1500 nm is not particularly limited. In the cover tape according to the first embodiment, "a transmittance of more than 80% at wavelengths of 1300 to 1500 nm" is easily achieved, for example, when the resin components constituting the cover tape do not contain a polyamide-based resin, when the cover tape includes an intermediate layer containing an olefin-based resin, and / or when the cover tape includes a heat seal layer containing a styrene-based resin as a main component, as described below. In the present disclosure, "polyamide-based resin" refers to a polyamide resin containing an aliphatic skeleton, commonly known as Nylon (registered trademark).

[0014] The cover tape according to the first embodiment preferably has a transmittance of 84% or more, more preferably 85% or more, at wavelengths of 1200 to 1600 nm. Cover tapes with a transmittance of 84% or more, more preferably 85% or more, over a wavelength range wider than 1300 to 1500 nm are preferred because they have lower moisture absorption. In the present disclosure, "a transmittance of 84% or more at wavelengths of 1200 to 1600 nm" means that the cover tape has a transmittance of 84% or more at any wavelength within that wavelength range, which is different from an average transmittance of 84% or more within that wavelength range.

[0015] The transmittance at wavelengths of 1200 to 1600 nm can be measured by the same method as the transmittance measurement method described above. In one embodiment, the transmittance at wavelengths of 1200 to 1600 nm may be 86% or more, or may be 87% or more. Furthermore, from the viewpoint of obtaining a cover tape that absorbs little moisture under high temperature and low humidity conditions, there are no particular limitations on the upper limit.

[0016] In one embodiment, the change rate of the transmittance (T2) at a wavelength of 1600 nm relative to the transmittance (T1) at a wavelength of 1200 nm of the cover tape, as represented by the following formula (1), may be 90% or more. (T2 / T1) × 100(%) (1)

[0017] If the rate of change represented by the formula (1) is 90% or more, the cover tape is likely to be less hygroscopic under high temperature and low humidity conditions. For example, when the transmittance (T1) at a wavelength of 1200 nm is 85%, a cover tape having a transmittance (T2) at a wavelength of 1600 nm of 76.5% or more is preferred as a cover tape that satisfies the formula (1). Furthermore, the cover tape having a transmittance of 85% or more at wavelengths of 1200 to 1600 nm is preferred because it is likely to have a rate of change represented by the formula (1) of 90% or more.

[0018] The upper limit of the increase / decrease rate represented by the above formula (1) is not particularly limited as long as it has the effects of the present invention. In the cover tape according to the first embodiment, since the aspect of T1 < T2 may be included, the increase / decrease rate may be 100% or more. In one embodiment, the increase / decrease rate may be 90 to 105%, or may be 95 to 102%.

[0019] In general cover tapes, for example, like the cover tape 7 shown in Comparative Example 2 described later, as the wavelength shifts to the higher wavelength side of near-infrared rays, the transmittance tends to gradually decrease. In the case of the cover tape 7 shown in Comparative Example 1, the transmittance at wavelengths of 1300 to 1500 nm is 80% or less, and the increase / decrease rate is also less than 90%. From the studies of the inventors of the present application, it was found that cover tapes like Comparative Example 2 are likely to absorb moisture even under high temperature and low humidity conditions. The cover tape according to the first embodiment has a high transmittance of more than 80% at wavelengths of 1300 to 1500 nm, and the increase / decrease rate of the transmittance in a wider wavelength range, that is, the value of the transmittance (T2) at a wavelength of 1600 nm with respect to the transmittance (T1) at a wavelength of 1200 nm is likely to be 90% or more. Such a cover tape, although the reason is not clear, is less likely to absorb moisture even under high temperature and low humidity conditions, and defects caused by the cover tape absorbing moisture are less likely to occur. Also, the cover tape according to the first embodiment is less likely to absorb moisture due to temperature and humidity changes.

[0020] <Layer structure> The cover tape according to the first embodiment can have a multilayer structure in which a base material layer, an intermediate layer, and a heat-sealing layer are laminated in this order. For each layer constituting the cover tape according to the first embodiment, it is necessary to select a thermoplastic resin, an additive, etc. so that the transmittance of the cover tape at wavelengths of 1300 to 1500 nm is more than 80%. In a preferred embodiment, from the viewpoint of easily achieving the above transmittance, each layer constituting the cover tape does not contain a polyamide-based resin.

[0021] Below, we describe an example of a cover tape that has at least a base layer, an intermediate layer, and a heat seal layer and that is likely to achieve the transmittance requirements of the cover tape of the first embodiment, but the configuration of the cover tape of the first embodiment is not limited to the following.

[0022] <Base material layer> The substrate layer is a layer containing a thermoplastic resin, and is preferably made of a film formed from a thermoplastic resin. The thermoplastic resin constituting the substrate layer is preferably selected from the viewpoints of easily achieving a transmittance of more than 80% at wavelengths of 1300 to 1500 nm and satisfying the mechanical properties required of the cover tape. In one embodiment, polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate, polyolefin-based resins such as polypropylene, polycarbonate-based resins, etc. are preferred. Furthermore, it is more preferred that the substrate layer be composed of a biaxially stretched film.

[0023] The substrate layer preferably does not contain a polyamide resin, and is more preferably made of a polyester resin film such as a biaxially oriented polyethylene terephthalate film or a biaxially oriented polyethylene naphthalate film.

[0024] The thickness of the base layer is generally set arbitrarily within the range of 5 to 50 μm, taking into consideration the mechanical properties of the cover tape. In the cover tape according to the first embodiment, the thickness of the base layer is preferably set so that the transmittance at wavelengths of 1300 to 1500 nm is greater than 80%, or so that the transmittance at wavelengths of 1200 to 1600 nm is 85% or greater. From these viewpoints, the thickness of the base layer is preferably 10 to 30 μm, more preferably greater than 10 μm but not greater than 30 μm, and even more preferably 12 to 20 μm.

[0025] In one embodiment, at least one surface of the substrate layer may be surface-treated. Examples of the surface treatment include sandblasting, corona discharge treatment, and plasma treatment. In one embodiment, the surface of the substrate layer on which the intermediate layer is laminated is preferably surface-treated. By surface-treating the substrate layer, the adhesive strength between the substrate layer and the intermediate layer is likely to be improved.

[0026] <Middle class> The intermediate layer is a layer of a thermoplastic resin laminated on one side of the substrate layer, if necessary via an adhesive layer or an anchor coat layer. The present inventors have found that the transmittance of a cover tape in the near-infrared wavelength range is easily affected by the thermoplastic resin that constitutes the intermediate layer. As a result of further investigation, the present inventors have found that when the intermediate layer does not contain a polyamide-based resin, the transmittance in the wavelength range of 1300 to 1500 nm is likely to be 80% or more. Furthermore, from the viewpoint of also easily achieving a transmittance in the wavelength range of 1200 to 1600 nm of 85% or more, it has also been found that it is preferable for the intermediate layer to contain no polyamide-based resin and to contain a polyolefin-based resin.

[0027] Examples of polyolefin resins that can be used include polyethylene (e.g., low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and very low-density polyethylene (VLDPE)), 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 polypropylene. These polyolefin resins may be used alone or as a mixture of two or more. The intermediate layer may also be two or more layers made of different polyolefin resins, such as a layer made of polyethylene and a layer made of ethylene-1-butene copolymer.

[0028] From the viewpoint of easily obtaining a cover tape that easily has a transmittance of more than 80% at wavelengths of 1300 to 1500 nm and that has low moisture absorption under high temperature and low humidity conditions, the intermediate layer preferably contains only a polyolefin resin as a resin component, and more preferably contains only LLDPE. Furthermore, from the viewpoint of easily obtaining a cover tape that has low moisture absorption under high temperature and low humidity conditions in particular, a multilayer structure in which two or more layers of the same type of polyolefin resin are laminated (preferably a multilayer structure in which two or more layers of polyethylene are laminated, more preferably a multilayer structure in which two or more layers of LLDPE are laminated) is preferred. Here, "the same type of polyolefin resin" means that the olefin units contained in the polyolefin resin are the same, although the molecular weights and the like may be different. When the intermediate layer has a multilayer structure, the intermediate layer may be laminated directly on the substrate layer without an anchor coat layer interposed therebetween.

[0029] When the intermediate layer contains LLDPE, linear low-density polyethylene (m-LLDPE) polymerized with a metallocene catalyst is preferred.

[0030] 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, and 5-ethylidene-2-norbornene may be copolymerized.

[0031] In the cover tape, the thickness of the intermediate layer is generally 5 to 50 μm, and preferably 10 to 40 μm. The thickness of the intermediate layer is generally set from the viewpoint of various physical properties such as the adhesive strength between the intermediate layer and the base layer and the peel strength during heat sealing. In the cover tape according to the first embodiment, it is preferable to further control the thickness of the intermediate layer to more than 80% in the wavelength range of 1300 to 1500 nm, in order to obtain a cover tape with low moisture absorption under high temperature and low humidity conditions. In one embodiment, the thickness of the intermediate layer is preferably 10 to 40 μm, and more preferably 13 to 38 μm. Alternatively, the thickness of the intermediate layer may be 20 to 38 μm.

[0032] <Heat seal layer> The heat seal layer can be selected from the viewpoints of heat sealing the carrier tape, containing a thermoplastic resin that exhibits easy peelability and allows easy peeling during use, and that allows the cover tape to have a transmittance of more than 80% at wavelengths of 1300 to 1500 nm. From these viewpoints, preferred thermoplastic resins contained in the heat seal layer include ethylene-based resins such as polyethylene (e.g., LDPE, LLDPE, VLDPE, etc., as exemplified for the intermediate layer above), ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-butene-1 random copolymer; and styrene-based resins such as styrene-butadiene copolymer (SB), styrene-butadiene-styrene block copolymer (SBS) or its hydrogenated product (SEBS), polystyrene (PS), styrene-butadiene copolymer (SBC), and high impact polystyrene (HIPS). These thermoplastic resins may be used alone or in combination of two or more.

[0033] In one embodiment, the heat seal layer preferably contains a styrene-based resin as a primary component. In this case, the transmittance at wavelengths of 1300 to 1500 nm is likely to exceed 80%, resulting in a cover tape with low moisture absorption under high temperature and low humidity conditions. In the present disclosure, "containing a styrene-based resin as a primary component" refers to a styrene-based resin content of more than 50% by mass relative to the total amount (100% by mass) of all resin components. The proportion of the styrene-based resin in the heat seal layer is preferably more than 50% by mass and not more than 100% by mass, more preferably 70 to 100% by mass, and particularly preferably more than 70% by mass and not more than 100% by mass. In a preferred embodiment, from the viewpoint of making it easier to obtain a cover tape having a transmittance of 84% or more (more preferably 85% or more, and even more preferably 90% or more) at wavelengths of 1200 to 1600 nm, it is more preferable that the heat seal layer contains at least one styrene-based resin selected from SB, SEBS, and SBC as a main component.

[0034] The thickness of the heat seal layer is generally set from the viewpoint of heat sealing properties with the carrier tape. In the cover tape according to the first embodiment, it is preferable to control the thickness of the heat seal layer so that the transmittance at wavelengths of 1300 to 1500 nm is controlled to more than 80% to obtain a cover tape with low moisture absorption under high temperature and low humidity conditions. In one embodiment, the thickness of the heat seal layer is preferably 3 to 30 μm, more preferably 5 to 25 μm.

[0035] In one embodiment, the heat seal layer may contain one or more antistatic agents, which will be described later. When the heat seal layer contains an antistatic agent, the heat seal layer has both heat sealability and antistatic properties.

[0036] (adhesive layer or anchor coat layer) In one embodiment, an adhesive layer or an anchor coat layer can be provided between the intermediate layer and the base layer, or between the intermediate layer and the heat seal layer. When providing an adhesive layer or an anchor coat layer, anchor coating agents such as polyurethane adhesives, polyethyleneimine, modified polybutadiene, and organic titanate compounds, and hot melt adhesives such as polyolefin resins, ethylene-vinyl acetate resins, ethylene-acrylic ester resins, and vinyl chloride-vinyl acetate resins can be used. Among these, from the viewpoint of providing a cover tape that is less likely to absorb moisture under high temperature and low humidity conditions, it is preferable that the anchor coat layer contain a polyurethane adhesive.

[0037] In one embodiment, it is preferable to provide an anchor coat layer between the intermediate layer and the base layer. When the intermediate layer is laminated via an anchor coat layer, the polyolefin resin constituting the intermediate layer is preferably a single layer, and more preferably, the intermediate layer is configured as base layer / anchor coat layer / polyolefin resin such as LLDPE. With such a configuration, the aforementioned transmittance is likely to exceed 80%, and the cover tape is likely to have low moisture absorption under high temperature and low humidity conditions.

[0038] (antistatic layer) The cover tape according to the first embodiment may further include an antistatic layer. The antistatic layer may be provided on the heat seal layer and / or on the surface of the base layer that is not in contact with the intermediate layer. The inclusion of the antistatic layer provides the cover tape with an antistatic effect, making it easier to prevent static breakdown of electronic components. As mentioned above, if the heat seal layer contains an antistatic agent, it is not necessary to provide an antistatic layer on the heat seal layer.

[0039] The antistatic layer is a layer containing an antistatic agent. The antistatic agent is selected from the viewpoint of easily achieving the surface resistivity required for the cover tape and easily achieving the aforementioned transmittance. In one embodiment, the antistatic agent may be selected from conductive fine particles such as barium sulfate, tin oxide, zinc oxide, indium oxide, titanium oxide, aluminum oxide, and antimony-doped tin oxide (ATO); ionic liquids containing cyclic quaternary nitrogen-containing cations; cationic surfactants such as quaternary ammonium salts; polyalkylene oxides (e.g., polyethylene glycol, polypropylene glycol, polybutylene glycol, ethylene oxide-propylene oxide copolymer, etc.), polyether esters having a polyoxyalkylene structure and an ester bond, and the like.

[0040] As the ionic liquid containing a cyclic quaternary nitrogen-containing cation (hereinafter simply referred to as "ionic liquid"), from the viewpoint of easily achieving the above-mentioned transmittance and easily imparting the desired antistatic properties, for example, 1,3-dimethylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-dimethylimidazolium phosphate, 1,3-dimethylimidazolium hydrozine sulfate, etc. can be used.

[0041] As the quaternary ammonium salt, from the viewpoint of easily achieving the aforementioned transmittance and easily imparting the desired antistatic properties, for example, trimethyl lauryl ammonium methyl sulfate, ethyl dimethyl stearyl ammonium ethyl sulfate, ethyl dimethyl oleyl ammonium ethyl sulfate, ethyl dimethyl lauryl ammonium ethyl sulfate, ethyl dimethyl stearyl ammonium metasulfonium, ethyl dimethyl lauryl ammonium metasulfonium, etc. can be used.

[0042] The antistatic layer may further contain the antistatic agent and a binder resin. Examples of binder resins include polyurethane resins, acrylic resins, polyvinyl chloride resins, ethylene-vinyl acetate resins, polyester resins, butadiene resins, styrene resins including hydrogenated resins, and acrylic-modified polyester resins, and these may be used singly or in combination. From the viewpoint of easily controlling the transmittance to more than 80% in the wavelength range of 1300 to 1500 nm, it is preferable that the binder resin does not contain a polyamide resin.

[0043] When the cover tape according to the first embodiment has an antistatic layer, it is preferable that the cover tape contains at least one selected from ionic liquid, ATO, and alumina oxide, since this tends to achieve a transmittance of more than 80% at wavelengths of 1300 to 1500 nm and a transmittance of 84% or more at wavelengths of 1200 to 1600 nm. When the above-mentioned preferable antistatic agent is blended, the proportion of the antistatic agent is preferably 90% by mass or less based on the total mass of the resin composition constituting the antistatic layer.

[0044] The thickness of the antistatic layer is preferably 0.01 to 2.0 μm, from the viewpoint of easily achieving both antistatic properties and the above-mentioned transmittance.

[0045] (Total thickness of cover tape) The total thickness of the cover tape according to the first embodiment is preferably 40 to 65 μm, from the viewpoints of easily achieving the various physical properties required of the cover tape and easily achieving a transmittance of more than 80% at wavelengths of 1300 to 1500 nm.From the viewpoint of easily obtaining a cover tape with the aforementioned rate of change of 90 to 100%, the total thickness of the cover tape may be 40 to 50 μm, 42 μm or more but less than 50 μm, or 45 μm or more but less than 50 μm.

[0046] <Cover tape manufacturing method> The cover tape according to the first embodiment can be manufactured by, for example, laminating the aforementioned layers so that the transmittance at wavelengths of 1300 to 1500 nm is greater than 80%. Hereinafter, one embodiment of a method for manufacturing a cover tape according to the first embodiment, which includes at least a base layer, an intermediate layer, and a heat seal layer, will be described.

[0047] The manufacturing method according to this embodiment includes laminating a base layer, an intermediate layer, and a heat-sealing layer to achieve a transmittance of more than 80% at wavelengths of 1300 to 1500 nm. In this case, from the viewpoint of easily achieving a transmittance of more than 80%, it is preferable to include selecting the thermoplastic resins for each layer so that the thermoplastic resins constituting the base layer, intermediate layer, and heat-sealing layer do not contain polyamide-based resins (step (1)). Furthermore, from the viewpoint of more easily controlling the transmittance to more than 80%, it is preferable in step (1) to select the thermoplastic resins for each layer so that the intermediate layer contains an olefin-based resin and the heat-sealing layer contains a styrene-based resin as a main component.

[0048] In one embodiment, after the step (1), the process may include forming a heat seal layer (step (2)), applying a thermoplastic resin composition constituting an intermediate layer (hereinafter referred to as "resin composition for intermediate layer") to the base layer (step (3)), and laminating the base layer, intermediate layer, and heat seal layer (step (4)).

[0049] (Process (2)) The heat seal layer can be formed by, for example, a T-die casting method, an inflation method, etc. When an antistatic agent is blended into the heat seal layer, a resin composition containing the antistatic agent may be preblended in advance using a tumbler, and the resin composition may be formed into a film.

[0050] (Step (3)) Examples of coating the intermediate layer resin composition on the substrate layer include extruding the intermediate layer resin composition (preferably a polyolefin resin, particularly preferably containing LLDPE) through a T-die onto the surface of the substrate layer (preferably a biaxially oriented polyester film). Before coating the intermediate layer resin composition, an anchor coating agent (preferably a polyurethane adhesive) may be applied to the surface of the substrate layer, if necessary, and the intermediate layer may be laminated on the surface coated with the anchor coating agent.

[0051] (Step (4)) When laminating the base layer, intermediate layer, and heat seal layer, it is preferable to sandwich laminate the heat seal layer formed on the intermediate layer obtained in step (3).

[0052] (Step (5)) In a preferred embodiment, the method further includes laminating an antistatic layer on the heat seal layer (step (5)). In laminating the antistatic layer on the heat seal layer, it is preferable to apply the resin composition constituting the antistatic layer using, for example, a gravure coater, a reverse coater, a kiss coater, an air knife coater, a Mayer bar coater, a dip coater, or the like.

[0053] In one embodiment, the manufacturing method may include, after the step (1), forming a two-layer film consisting of an intermediate layer and a heat seal layer (step (6)), and laminating the two-layer film and a base layer (step (7)).

[0054] (Process (6)) To produce a two-layer film consisting of an intermediate layer and a heat-sealing layer, it is preferable to extrude the aforementioned resin composition for the intermediate layer (preferably containing a polyolefin resin, particularly preferably LLDPE) and the resin composition constituting the heat-sealing layer (hereinafter referred to as the "resin composition for the heat-sealing layer") from separate single-screw extruders and laminate them using a multi-manifold die.

[0055] (Process (7)) To laminate the two-layer film and the base layer, it is preferable to apply an anchor coating agent (preferably a polyurethane adhesive) to the surface of the base layer (preferably a biaxially oriented polyester film) as needed, and then laminate the two-layer film onto the side coated with the anchor coating agent by a dry lamination method.

[0056] (Process (8)) After step (7), step (8) may further comprise laminating an antistatic layer on the surface of the heat seal layer. Step (8) may be performed by the same method as step (5) described above.

[0057] In one embodiment, the manufacturing method may include, after step (1), forming a two-layer film consisting of a part of the intermediate layer and a heat seal layer (step (9)), coating the base layer with a resin composition that constitutes a part of the intermediate layer (step (10)), and laminating them so that the surface of the two-layer film facing the intermediate layer is in contact with the surface of the base layer facing the intermediate layer (step (11)).

[0058] (Process (9)) To produce a two-layer film consisting of a part of the intermediate layer and a heat-sealing layer, it is preferable to extrude the resin composition (preferably a polyolefin resin, particularly preferably containing LLDPE) that constitutes a part of the intermediate layer and the resin composition for the heat-sealing layer from separate single-screw extruders and laminate them using a multi-manifold die.

[0059] (Step (10)) The resin composition constituting a part of the intermediate layer is preferably applied to the substrate layer by extruding the resin composition constituting a part of the intermediate layer (preferably a polyolefin resin, particularly preferably LLDPE) from a T-die onto the surface of the substrate layer (preferably a biaxially oriented polyester film). Before applying the resin composition, an anchor coating agent (preferably a polyurethane adhesive) may be applied to the surface of the substrate layer, if necessary, and the intermediate layer may be laminated on the surface coated with the anchor coating agent.

[0060] (Step (11)) After step (10), the two-layer film and the substrate layer are laminated together so that the surface of the intermediate layer of the two-layer film contacts the surface of the intermediate layer of the substrate layer (sand lamination). Step (12) may also be included in which an antistatic agent is laminated on the heat seal layer. Step (11) may be the same method as step (5).

[0061] The intermediate layer of the cover tape obtained by the above steps (9) to (11) (or steps (9) to (12)) has a two-layer structure consisting of a layer formed by co-extrusion with the heat seal layer and a layer formed by sand lamination. The thickness of the layer formed by sand lamination is preferably 10 to 20 μm, from the viewpoint of easily achieving the aforementioned transmittance of more than 80%.

[0062] In addition to the above-described steps, the manufacturing method according to this embodiment may, if necessary, include antistatic treatment of the surface of the base layer of the cover tape (the surface not in contact with the intermediate layer). Examples of antistatic agents include those described above, and preferred examples of these are also the same. The antistatic treatment can be carried out by a roll coater using a gravure roll, a lip coater, a spray, or the like. Furthermore, in order to apply these antistatic agents uniformly, it is preferable to perform corona discharge treatment or ozone treatment on the film surface before the antistatic treatment, and corona discharge treatment is particularly preferable.

[0063] [Application] The cover tape according to the first embodiment can be used as a cover tape for an electronic component package.

[0064] As described above, the cover tape according to the first embodiment is resistant to moisture absorption even under high temperature and low humidity conditions. In one embodiment, the moisture absorption rate of the cover tape under the following conditions is preferably 1500 ppm by mass or less, more preferably 1400 ppm by mass or less, and even more preferably 1300 ppm by mass or less. <Measurement conditions> After storing the cover tape under dry conditions of 60°C / 20% RH for 12 hours, measure the moisture absorption rate of the cover tape at a holding temperature of 280°C using the Karl Fischer method in accordance with JIS K0068:2001 "Moisture Evaporation-Coulometric Titration Method."

[0065] The cover tape according to the first embodiment has low moisture absorption under high temperature and low humidity conditions. Such a cover tape also tends to absorb less moisture due to humidity fluctuations, and can therefore be used, for example, as a low-moisture-absorption cover tape for electronic component packages.

[0066] [Electronic component packaging] A second embodiment of the present disclosure relates to an electronic component packaging body. A package containing electronic components, etc. (hereinafter referred to as an "electronic component package") can be obtained, for example, by placing electronic components, etc., in recesses in a carrier tape for storing electronic components, etc., and then using a cover tape as a lid. Both longitudinal edges of the cover tape are continuously heat-sealed using a heat iron or the like to package the components, and then winding the package onto a reel. Packaged in this manner, electronic components, etc., are stored and transported. The electronic component package according to the second embodiment can be used to store and transport various electronic components, such as connectors, ICs, diodes, transistors, capacitors, resistors, and LEDs. When storing or transporting the electronic component package, it is stored or transported under conditions with minimal temperature and humidity changes to avoid moisture absorption by the electronic component package, including the cover tape, due to temperature and humidity changes and resulting problems with the stored contents (electronic components). However, as described above, according to the inventors' investigations, the cover tape can absorb moisture even at high temperatures and low humidity, and therefore a cover tape that is less likely to absorb moisture even at low humidity is needed. The electronic component packaging according to the second embodiment includes the cover tape described above, and therefore is less likely to absorb moisture even under high temperature and low humidity conditions, which helps to prevent problems with the electronic components caused by moisture absorption by the cover tape.

[0067] The electronic component package is transported using holes called sprocket holes for transporting the carrier tape, which are provided on the longitudinal edge of the carrier tape, while the cover tape is intermittently peeled off.The electronic components are then removed using a component mounting device, while checking the presence, orientation, and position of the electronic components, and are then mounted on a board.

[0068] The carrier tape included in the electronic component packaging according to the second embodiment is a strip-shaped material approximately 4 mm to 100 mm wide and having a recess for storing electronic components. When the cover tape according to the first embodiment is heat-sealed as a lid, the material of the carrier tape is not particularly limited, but carrier tapes containing polystyrene-based resins, polyester-based resins, or polycarbonate-based resins are suitable. The carrier tape may be imparted with conductivity by kneading carbon black or carbon nanotubes into the resin; or may be kneaded with a surfactant-type antistatic agent such as a cationic, anionic, or nonionic agent, or a persistent antistatic agent such as polyether ester amide; or may be imparted with antistatic properties by coating the surface with 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.

[0069] Furthermore, electronic component packages are inspected by an IR camera through the cover tape to detect defects in the electronic components contained therein and to recognize circuits printed on the electronic components. The cover tape according to the first embodiment has high transmittance in the near-infrared range, and therefore has good visibility with an IR camera.

[0070] Another embodiment of the present disclosure is a method for suppressing moisture absorption by a cover tape under high temperature and low humidity conditions by controlling the transmittance of the cover tape at wavelengths of 1300 to 1500 nm to more than 80%. The method preferably further includes controlling the transmittance of the cover tape at wavelengths of 1200 to 1600 nm to 84% or more. Furthermore, the method preferably includes controlling the rate of change of the transmittance (T2) at a wavelength of 1600 nm relative to the transmittance (T1) at a wavelength of 1200 nm, as expressed by the following formula (1), to 90% or more. (T2 / T1) × 100(%) (1) [Example]

[0071] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following description.

[0072] <Production of cover tapes 1 to 6> The thermoplastic resins listed in Table 1 were selected as the thermoplastic resins constituting each layer. The thickness of each layer was determined as listed in Table 1. Then, following the steps (2) to (5) above, the base layer, intermediate layer, heat seal layer, and antistatic layer were laminated in this order. Specifically, the resin composition for the heat seal layer was extruded using a single-screw extruder by the T-die method to form a heat seal layer. Next, the formed heat seal layer and the base layer (PET film) were extrusion-sand-laminated with the molten resin composition for the intermediate layer, thereby laminating the base layer, intermediate layer, and heat seal layer in this order. Furthermore, an antistatic layer was coated on the heat seal layer and dried to obtain cover tapes 1 to 6. For cover tapes 3 to 6, an anchor coat layer (urethane adhesive) was provided on the base layer, and then an intermediate layer was laminated on the surface of the anchor coat layer.

[0073] <Production of cover tapes 7 and 8> The thermoplastic resins listed in Table 1 were selected as the thermoplastic resins constituting each layer, and the thickness of each layer was determined as listed in Table 1. Then, the base layer, intermediate layer, heat seal layer, and antistatic layer were laminated according to the above-mentioned steps (2) to (5). Cover tapes 7 and 8 were manufactured in the same manner as cover tapes 1 to 6, except that anchor coat layers were provided between the base layer and intermediate layer, and between the intermediate layer and heat seal layer.

[0074] [Table 1]

[0075] The components listed in Table 1 are as follows: <Base material layer> PET: Biaxially oriented polyethylene terephthalate film <Middle class> m-LLDPE Polyamide (nylon) <Heat seal layer> Styrene-based resin 1: Resin composition containing SBC and SB Styrene-based resin 2: SEBS Styrene-based resin 3: SB Ethylene resin: LLDPE Mixed resin: Resin composition containing SB and LLDPE (containing LLDPE as the main component) <Antistatic layer> Antistatic agent 1: A mixture of an ionic liquid (1-ethyl-3-methylimidazolium ethyl sulfate), a quaternary ammonium salt (ethyl dimethyl lauryl ammonium ethyl sulfate), and polyethylene glycol (antistatic agent concentration: 0.5% by mass). Antistatic agent 2: ATO Antistatic agent 3: Aluminum oxide Antistatic agent 4: Barium sulfate Antistatic agent 5: A mixture of barium sulfate and tin oxide In addition, the notation "-" in Table 1 means that no anchor coat layer was provided.

[0076] [Examples 1 to 5 and Comparative Examples 1 to 3] The transmittance and moisture absorption rate of each cover tape listed in Table 2 were measured by the following method. The results are shown in Table 2.

[0077] <Transmittance measurement method> The transmittance of cover tapes 1 to 8 at wavelengths of 1200 to 1600 nm was measured by the following method, and the results are shown in Table 2 and FIG. The measurement and analysis equipment used was an ultraviolet-visible-near-infrared spectrophotometer (Shimadzu Corporation, product name "UV-3600") and a multipurpose large sample chamber (φ60 mm, with built-in integrating sphere; Shimadzu Corporation, product name "MPC-3100"). First, baseline correction was performed without cover tape, and then the cover tape was attached and the spectral transmittance was measured using the integrating sphere at wavelengths of 1200 to 1600 nm.

[0078] <Method for measuring moisture absorption rate under high temperature and low humidity conditions> The moisture absorption rates of cover tapes 1 to 8 were measured by the following method. The results are shown in Table 2. After storing the cover tape under dry conditions of 60°C / 20% RH for 12 hours, the moisture absorption rate of the cover tape was measured at a holding temperature of 280°C using the Karl Fischer method in accordance with JIS K0068:2001 "Moisture Evaporation-Coulometric Titration Method." Evaluation was also conducted according to the following criteria, with a rating of B or higher being considered a pass. (Evaluation criteria) A: The moisture absorption rate under high temperature and low humidity conditions was 1000 mass ppm or less. B: The moisture absorption rate under high temperature and low humidity conditions was more than 1000 mass ppm and 1500 mass ppm or less. C: The moisture absorption rate under high temperature and low humidity conditions was more than 1500 mass ppm.

[0079] [Table 2]

[0080] As shown in Table 2 and Figure 1, Examples 1 to 5 (cover tapes 1 to 5), which had a transmittance of over 80% at wavelengths of 1300 to 1500 nm, exhibited low moisture absorption under high temperature and low humidity. On the other hand, Comparative Examples 1 to 3 (cover tapes 6 to 8), which had a transmittance of 80% or less at wavelengths of 1300 to 1500 nm, exhibited a moisture absorption rate of over 1500 mass ppm under high temperature and low humidity, indicating that the cover tape absorbed a large amount of moisture. From these results, it was confirmed that the cover tape according to the present disclosure is resistant to moisture absorption even under high temperature and low humidity.

[0081] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of the present disclosure are set forth below. [1] A cover tape having a transmittance of more than 80% at wavelengths of 1300 to 1500 nm. [2] The cover tape according to [1], which has a transmittance of 84% or more at wavelengths of 1200 to 1600 nm. [3] The cover tape according to [1] or [2], wherein the rate of increase or decrease of the transmittance (T2) at a wavelength of 1600 nm relative to the transmittance (T1) at a wavelength of 1200 nm, as represented by the following formula (1), is 90% or more. (T2 / T1) × 100(%) (1) [4] The cover tape according to any one of [1] to [3], which does not contain a polyamide resin. [5] At least a base layer, an intermediate layer, and a heat seal layer are laminated in this order, The cover tape according to any one of [1] to [4], wherein the intermediate layer contains a polyolefin resin. [6] At least a base layer, an intermediate layer, and a heat seal layer are laminated in this order, The cover tape according to any one of [1] to [4], wherein the intermediate layer does not contain a polyamide resin. [7] The cover tape according to [5] or [6], wherein the heat seal layer contains a styrene-based resin as a main component. [8] The cover tape according to any one of [1] to [7], which is for use in packaging for electronic components. [9] An electronic component packaging body comprising the cover tape according to any one of [1] to [8].

Claims

1. A cover tape having a transmittance of more than 80% at wavelengths of 1300 to 1500 nm.

2. The cover tape according to claim 1, which has a transmittance of 84% or more at wavelengths of 1200 to 1600 nm.

3. 3. The cover tape according to claim 1, wherein the rate of change in transmittance (T2) at a wavelength of 1600 nm relative to the transmittance (T1) at a wavelength of 1200 nm, as represented by the following formula (1), is 90% or more. (T2 / T1)×100(%)...(1)

4. The cover tape according to claim 1 or 2, which does not contain a polyamide resin.

5. At least a base layer, an intermediate layer, and a heat seal layer are laminated in this order, The cover tape according to claim 1 or 2, wherein the intermediate layer comprises a polyolefin resin.

6. At least a base layer, an intermediate layer, and a heat seal layer are laminated in this order, The cover tape according to claim 1 or 2, wherein the intermediate layer does not contain a polyamide-based resin.

7. The cover tape according to claim 5 , wherein the heat seal layer contains a styrene-based resin as a main component.

8. The cover tape according to claim 1 or 2, which is for use in packaging for electronic components.

9. An electronic component package comprising the cover tape according to claim 1 or 2.

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