Cover tape and electronic component packing body comprising the same

Abstract

To provide a cover tape having a high transmittance in a near-infrared wavelength region, and an electronic component packing body comprising it.SOLUTION: Provided is a cover tape whose moisture absorptivity (a) measured under the following conditions is 1500 mass ppm or lower. Conditions: after the cover tape is stored for 12 hours under a dry condition of 60°C / 20%RH, according to "Karl Fisher titration method, moisture vaporization-coulometric titration method" of JIS K0068:2001, the moisture absorptivity (a) of the cover tape is measured at a holding temperature of 280°C. A haze value of the cover tape is preferably less than 25%.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] The cover tape is required to have a transparency sufficient to allow the contents inside to be visually recognized. For example, Patent Document 1 proposes a highly transparent cover tape.

[0004] In recent years, with the further miniaturization of electronic components, camera inspection using near-infrared cameras and the like has become mainstream instead of visual inspection. Near-infrared cameras can capture near-infrared light that is invisible to the human eye, so they can be used to detect defects in electronic components contained in electronic component packaging through cover tape and to recognize circuits printed on electronic components. However, conventional cover tapes have low transmittance in the near-infrared wavelength range, resulting in insufficient visibility in near-infrared camera inspections. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 087999 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a cover tape having high transmittance in the near-infrared wavelength range and an electronic component package including the same. [Means for solving the problem]

[0007] To address the above-mentioned problems, the present inventors conducted extensive research and surprisingly found that there is a correlation between the moisture absorption rate (a) of a cover tape and its transmittance in the near-infrared wavelength range. That is, the inventors discovered that a cover tape having a moisture absorption rate (a) of 1500 mass ppm or less, measured under the following conditions, has high transmittance in the near-infrared wavelength range. <Condition> After storing the cover tape under dry conditions of 60°C / 20% RH for 12 hours, measure the moisture absorption rate (a) of the cover tape at a holding temperature of 280°C in accordance with JIS K0068:2001 "Karl Fischer titration method, moisture evaporation-coulometric titration method." [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a cover tape having high transmittance in the near-infrared wavelength range 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 moisture absorption rate (a) of 1500 mass ppm or less, measured under the following conditions: <Condition> After storing the cover tape under dry conditions of 60°C / 20% RH for 12 hours, measure the moisture absorption rate (a) of the cover tape at a holding temperature of 280°C in accordance with JIS K0068:2001 "Karl Fischer titration method, moisture evaporation-coulometric titration method."

[0013] The moisture absorption rate (a) is an index showing the moisture absorption rate (a) of the cover tape after storing the cover tape in a high-temperature, low-humidity environment for 12 hours. Thus, the cover tape according to the first embodiment, which has a moisture absorption rate (a) of 1500 mass ppm or less measured under the above conditions, has high transmittance in the near-infrared wavelength range. Such a cover tape also tends to have good visibility in near-infrared camera inspection (hereinafter sometimes referred to as "IR camera inspection"). In the present disclosure, "transmittance in the near-infrared wavelength range" (hereinafter referred to as "near-infrared transmittance") includes transmittance of near-infrared rays with wavelengths of 1200 to 1600 nm.

[0014] In one embodiment, the moisture absorption rate (a) measured under the above conditions (hereinafter referred to as "moisture absorption rate (a") is preferably 1400 mass ppm or less, more preferably 1300 mass ppm or less, and even more preferably 1250 mass ppm or less, from the viewpoint of easily increasing the transmittance in the near-infrared wavelength range and easily improving visibility in IR camera inspection. Note that, from the viewpoint that a cover tape with high near-infrared transmittance is easily obtained by lowering the moisture absorption rate (a), the lower limit of the moisture absorption rate (a) is not particularly limited.

[0015] In the cover tape according to the first embodiment, the "moisture absorption rate (a) of 1500 mass ppm or less" is easily achieved, for example, when the resin components constituting the cover tape do not contain polyamide-based resin. Furthermore, when the cover tape according to the first embodiment has a layer structure in which a base layer, an intermediate layer, and a heat-sealing layer are laminated in this order, as described below, the moisture absorption rate (a) is likely to be 1500 mass ppm or less when the intermediate layer does not contain polyamide-based resin, and / or when the intermediate layer contains a polyolefin-based resin and / or the heat-sealing layer contains a styrene-based resin as a main component, as described below. As a result, a cover tape with high transmittance in the near-infrared wavelength range is easily obtained. In this disclosure, "polyamide-based resin" refers to a polyamide resin containing an aliphatic skeleton, commonly known as Nylon (registered trademark).

[0016] <Layer configuration> The cover tape according to the first embodiment can have a multi-layer structure in which a base layer, an intermediate layer, and a heat seal layer are laminated in this order. The thermoplastic resins and additives for each layer constituting the cover tape according to this embodiment must be selected so that the moisture absorption rate (a) of the cover tape is 1500 mass ppm or less. In a preferred embodiment, from the viewpoint of easily achieving the moisture absorption rate (a) requirement, each layer constituting the cover tape does not contain a polyamide resin such as Nylon (registered trademark).

[0017] 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 moisture absorption rate (a) requirement of the first embodiment, but the configuration of the cover tape in this embodiment is not limited to the following.

[0018] <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 base layer is preferably selected from the viewpoint of easily achieving a moisture absorption rate (a) of 1500 mass ppm or less of the cover tape 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 base layer be composed of a biaxially oriented film.

[0019] 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.

[0020] The thickness of the substrate 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 this embodiment, the thickness of the substrate layer is preferably set so that the moisture absorption rate (a) is 1500 mass ppm or less. From these viewpoints, the thickness of the substrate layer is preferably 10 to 30 μm, more preferably 12 to 20 μm.

[0021] 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.

[0022] <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 moisture absorption rate (a) of a cover tape is easily affected by the thermoplastic resin constituting 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 moisture absorption rate (a) is likely to be 1500 mass ppm or less, and further, a cover tape with high transmittance in the near-infrared wavelength range is easily obtained. Furthermore, from the viewpoint of making it easier to obtain a cover tape with a lower moisture absorption rate (a) and a transmittance of 85% or more in the wavelength range of 1200 to 1600 nm, 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.

[0023] 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.

[0024] From the viewpoint of easily achieving a moisture absorption rate (a) of 1500 mass ppm or less and easily obtaining a cover tape with high transmittance in the near-infrared wavelength range, it is preferable that the intermediate layer has a single-layer structure made of one type of polyolefin resin (preferably a single-layer structure made of polyethylene, more preferably a single-layer structure made of LLDPE). Here, "the same type of polyolefin resin" means that the olefin units contained in the polyolefin resin are the same, but the molecular weights, etc., may be different.

[0025] When the intermediate layer comprises LLDPE, it is preferably a metallocene-catalyzed linear low-density polyethylene (m-LLDPE).

[0026] 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.

[0027] 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 control the thickness of the intermediate layer by controlling the moisture absorption rate (a) to 1500 mass ppm or less, in order to obtain a cover tape with high near-infrared transmittance. In one embodiment, the thickness of the intermediate layer is preferably 10 to 40 μm, and more preferably 19 to 38 μm.

[0028] <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 of making it easier for the cover tape to have a moisture absorption rate (a) of 1500 mass ppm or less. 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.

[0029] In one embodiment, the heat seal layer preferably contains a styrene-based resin as a main component. In this case, the moisture absorption rate (a) is likely to be 1500 ppm by mass or less, and as a result, a cover tape with high transmittance in the near-infrared wavelength range is likely to be obtained. In the present disclosure, "containing a styrene-based resin as a main component" refers to containing more than 50% by mass of the styrene-based resin 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 less than 100% by mass, more preferably 70 to 100% by mass, and particularly preferably more than 70% by mass and less than 100% by mass. In a preferred embodiment, the heat seal layer more preferably contains at least one styrene-based resin selected from SB, SEBS, and SBC as a main component.

[0030] The thickness of the heat seal layer is generally set from the viewpoint of heat sealability with the carrier tape. In the cover tape according to this embodiment, it is preferable to control the thickness of the heat seal layer from the viewpoint of obtaining a cover tape with high near-infrared transmittance by controlling the moisture absorption rate (a) to 1500 mass ppm or less in addition to heat sealability. In one embodiment, the thickness of the heat seal layer is preferably 3 to 20 μm, more preferably 5 to 10 μm.

[0031] In one embodiment, the heat seal layer may contain one or more antistatic agents, as described below. By including an antistatic agent in the heat seal layer, the heat seal layer becomes a layer that has heat sealability and antistatic properties. The antistatic agent may be conductive fine particles with low near-infrared absorption.

[0032] (adhesive layer or anchor coat layer) In one embodiment, an adhesive layer or 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 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, an anchor coat layer is preferred, and an anchor coat layer containing a polyurethane adhesive is more preferred, from the viewpoint of the moisture absorption rate (a) of the cover tape and the haze value described below.

[0033] 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 the anchor coat layer, the polyolefin resin constituting the intermediate layer is preferably a single layer, and more preferably the intermediate layer is configured as a base layer / anchor coat layer / polyethylene resin such as low-density polyethylene. With such a configuration, the moisture absorption rate (a) is likely to be low, and further, the cover tape is likely to have a small haze value, as described below.

[0034] (antistatic layer) The cover tape according to this 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, an antistatic layer need not be provided on the heat seal layer.

[0035] 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 moisture absorption rate (a). 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.

[0036] 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 moisture absorption rate (a) requirement 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.

[0037] As the quaternary ammonium salt, from the viewpoint of easily achieving the moisture absorption rate (a) requirement 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.

[0038] The antistatic layer can 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, which can be used singly or in combination. From the standpoint of easily controlling the moisture absorption rate (a) of the cover tape to 10,000 mass ppm or less, it is preferable that the binder resin not contain a polyamide resin.

[0039] When the cover tape according to the first embodiment has an antistatic layer, it preferably contains at least one selected from an ionic liquid, ATO, and alumina oxide. From the viewpoint of near-infrared transmittance, an antistatic agent with low near-infrared absorption function may be selected, and the amount of the antistatic agent may be controlled. In one embodiment, the antistatic agent may contain aluminum oxide. 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.

[0040] 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.

[0041] (Total thickness of cover tape) The total thickness of the cover tape according to the first embodiment is preferably 40 to 65 μm, more preferably 45 to 65 μm, from the viewpoint of easily achieving the various physical properties required of the cover tape and easily achieving a moisture absorption rate (a) of 1500 mass ppm or less.

[0042] (Haze value) In one embodiment, from the viewpoint of improving visibility in camera inspection, the haze value of the cover tape is preferably less than 25%, more preferably 24% or less, and particularly preferably 23% or less.

[0043] <Cover tape manufacturing method> The cover tape according to the first embodiment can be manufactured by laminating the aforementioned layers so that the moisture absorption rate (a) is 1500 mass ppm or less. 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.

[0044] The manufacturing method according to this embodiment includes laminating a substrate layer, an intermediate layer, and a heat-seal layer to obtain a cover tape having a moisture absorption rate (a) of 1500 ppm by mass or less. In order to more easily achieve a moisture absorption rate (a) of 1500 ppm by mass or less, it is preferable to select the thermoplastic resins for each layer (step (1)) so that the thermoplastic resins constituting the substrate layer, intermediate layer, and heat-seal layer do not contain polyamide-based resins. Furthermore, in order to more easily control the moisture absorption rate (a) to 1500 ppm by mass or less, it is preferable to select the thermoplastic resins for each layer so that the intermediate layer contains an olefin-based resin and the heat-seal layer contains a styrene-based resin as a main component in step (1).

[0045] In one embodiment, after 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)).

[0046] (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.

[0047] (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.

[0048] (Step (4)) When laminating the base layer, intermediate layer, and heat seal layer, it is preferable to sandwich laminate the heat seal layer formed in step (3) on the intermediate layer obtained in step (3).

[0049] (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.

[0050] In one embodiment, the production method may include, after step (1), forming a two-layer film consisting of an intermediate layer and a heat-sealing layer (step (6)), and laminating the two-layer film and a base layer (step (7)).

[0051] (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.

[0052] (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.

[0053] (Process (8)) After step (7), it is preferable to further include laminating an antistatic layer on the surface of the heat seal layer (step (8)). Step (8) can be performed by the same method as step (5) described above.

[0054] In one embodiment, the production method may include, after the step (1), forming a two-layer film consisting of a part of the intermediate layer and the 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 on the intermediate layer side and the surface of the base layer on the intermediate layer side are in contact with each other (step (11)).

[0055] (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.

[0056] (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.

[0057] (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). It is also preferable to include step (12) of laminating an antistatic layer on the heat seal layer. Step (12) can be performed in the same manner as step (5).

[0058] The cover tape obtained by the above steps (9) to (11) (or steps (9) to (12)) has a two-layer structure in which the intermediate layer is formed by co-extrusion with the heat seal layer, and the other layer is formed by sand lamination. From the viewpoint of the moisture absorption rate (a) of the cover tape, the thickness of the layer formed by sand lamination is preferably 10 to 20 μm.

[0059] 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. Among these, from the viewpoint of increasing near-infrared transmittance, it is preferable to select an antistatic agent with low near-infrared absorption function, and it is also preferable to control the amount of the agent blended. The antistatic treatment can be carried out using a roll coater or lip coater using a gravure roll, 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, with corona discharge treatment being particularly preferable.

[0060] [Application] The cover tape according to the first embodiment can be used as a cover tape for an electronic component package.

[0061] As described above, the cover tape according to this embodiment exhibits the advantage of high near-infrared transmittance. In the present disclosure, "high near-infrared transmittance" includes a cover tape having a transmittance of greater than 80% at wavelengths of 1300 to 1500 nm. Furthermore, from the perspective of improving visibility in camera inspections, particularly IR camera inspections, this may also include a cover tape having a transmittance of 85% or more at wavelengths of 1200 to 1600 nm. Here, "the cover tape has a transmittance of greater than 80% at wavelengths of 1300 to 1500 nm" means that the cover tape has a transmittance of greater than 80% at any wavelength within the wavelength range, which is different from an average transmittance of greater than 80%. The same applies to the transmittance at wavelengths of 1200 to 1600 nm.

[0062] The transmittance of the cover tape in the near-infrared wavelength range can be measured under the following conditions. <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.

[0063] The cover tape according to the first embodiment has high transmittance in the near-infrared wavelength range, and can therefore be used, for example, as a visibility-improving cover tape for electronic component packaging. Furthermore, because the moisture absorption rate (a) is low, at 1500 mass ppm or less, it can also be used as a low-moisture-absorption cover tape for electronic component packaging.

[0064] A second embodiment of the present disclosure relates to an electronic component packaging body. A package containing electronic components, etc. (hereinafter referred to as "electronic component package") can be obtained, for example, by placing the electronic components, etc. in recesses in a carrier tape for storing the electronic components, etc., using a cover tape as a lid, continuously heat-sealing both longitudinal edges of the cover tape using a heat iron or the like to package the components, and then winding the package onto a reel. Packaged in this form, the 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. The electronic component package is inspected with a near-infrared camera or the like from above the cover tape. The electronic component package according to the second embodiment includes the cover tape according to the first embodiment, which tends to provide good visibility in near-infrared camera inspections. Furthermore, the electronic component packaging according to the second embodiment is less likely to absorb moisture even under high temperature and low humidity conditions because it includes the cover tape described above. This also helps to prevent problems with the electronic components caused by moisture absorption by the cover tape.

[0065] 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.

[0066] 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 incorporating carbon black or carbon nanotubes into the resin; or may be imparted with a surfactant-based antistatic agent such as a cationic, anionic, or nonionic antistatic agent, or a persistent antistatic agent such as polyether ester amide; or may be imparted with antistatic properties by applying a coating liquid to the surface in which a surfactant-based antistatic agent or a conductive material such as polypyrrole or polythiophene is dispersed in an organic binder such as an acrylic resin.

[0067] Another embodiment of the present disclosure is a method for improving the transmittance of a cover tape in the near-infrared wavelength range by controlling the moisture absorption rate (a) of the cover tape, measured under the aforementioned conditions, to 1500 mass ppm or less. The method may be a method for improving the transmittance of the cover tape to more than 80% in the wavelength range of 1300 to 1500 nm. Alternatively, the method may be a method for improving the transmittance of the cover tape to 84% or more in the wavelength range of 1200 to 1600 nm. [Example]

[0068] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following description.

[0069] <Manufacturing of cover tapes 1 to 5> 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) described above, a base layer, an intermediate layer, a heat-seal layer, and an 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 a base layer (PET film) were extrusion-sand-laminated with a 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 5. For cover tapes 2 to 5, 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.

[0070] <Production of cover tapes 6-7> 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 6 to 7 were manufactured in the same manner as cover tapes 1 to 5, except that anchor coat layers were provided between the base layer and intermediate layer, and between the intermediate layer and heat seal layer.

[0071] [Table 1]

[0072] The components listed in Table 1 are as follows: <Base material layer> PET: Biaxially oriented polyethylene terephthalate film <Middle class> m-LLDPE Polyamide resin (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: A mixture of barium sulfate and tin oxide In addition, the notation "-" in Table 1 means that no anchor coat layer was provided.

[0073] [Examples 1 to 4 and Comparative Examples 1 to 3] The moisture absorption rate (a), transmittance, and haze value were measured by the following methods for each cover tape listed in Table 2. The results are shown in Table 2. The transmittance measurement results for each cover tape are also shown in Figure 1.

[0074] <Measuring method for moisture absorption rate (a)> The moisture absorption rates (a) of cover tapes 1 to 7 were measured by the following method. The results are shown in Table 2. Measurement was carried out under the following conditions. <Condition> After storing the cover tape under dry conditions of 60°C / 20% RH for 12 hours, the moisture absorption rate (a) of the cover tape was measured at a holding temperature of 280°C according to JIS K0068:2001 "Karl Fischer titration method, moisture evaporation-coulometric titration method."

[0075] <Transmittance measurement method> The transmittance of cover tapes 1 to 7 at wavelengths of 1200 to 1600 nm was measured by the following method. 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.

[0076] Generally, near-infrared camera inspection requires high transmittance in the wavelength range of 1200 to 1600 nm. Therefore, the obtained transmittance was evaluated according to the following evaluation criteria. (Transmittance evaluation criteria) Excellent: All transmittances in the wavelength range of 1200 to 1600 nm are 90% or higher. Good: All transmittances in the wavelength range of 1200 to 1600 nm are 84% or more and less than 90%. Acceptable: All transmittances in the wavelength range of 1200 to 1600 nm are greater than 80% and less than 84%. Unacceptable: The transmittance at any wavelength between 1200 and 1600 nm is 80% or less.

[0077] <Method for measuring haze value> To improve visibility in camera inspection, a low haze value is also preferable. Therefore, the haze value of the cover tape was measured and evaluated according to the following evaluation criteria. The haze values ​​of cover tapes 1 to 7 were measured by the following method. The results are shown in Table 2. Using a test piece prepared from the cover tape, measurement was performed using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "Haze Meter NDH 7000") in accordance with JIS K7361-1:1997. Good: The haze value is 15% or more and less than 20%. Acceptable: Haze value is 20% or more and less than 25%. Unacceptable: Haze value is 25% or more.

[0078] <Overall evaluation of cover tape> Those that could not be evaluated for either transmittance or haze value were evaluated as "failed" (poor visibility in camera inspection). The results are shown in Table 2.

[0079] [Table 2]

[0080] As shown in Table 2 and FIG. 1, Examples 1 to 4 (cover tapes 1 to 4), which had a moisture absorption rate (a) of 1500 mass ppm or less, had high near-infrared transmittance. The cover tapes of Examples 1 to 4 were evaluated as excellent or good in transmittance, and also obtained good or fair results in haze values. Such cover tapes are likely to have good visibility in IR camera inspection. On the other hand, Comparative Examples 1 to 3 (cover tapes 5 to 7), which had a moisture absorption rate (a) of more than 1500 mass ppm, had low transmittance in the near-infrared wavelength range. Furthermore, cover tape 5 of Comparative Example 1 also had a high haze value. Therefore, the cover tapes of these comparative examples do not have sufficient visibility in IR camera inspection. From the above results, it was confirmed that the cover tape according to the present disclosure has high transmittance in the near-infrared wavelength range.

[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 moisture absorption rate (a) of 1500 mass ppm or less, measured under the following conditions: <Condition> After storing the cover tape under dry conditions of 60°C / 20% RH for 12 hours, measure the moisture absorption rate (a) of the cover tape at a holding temperature of 280°C in accordance with JIS K0068:2001 "Karl Fischer titration method, moisture evaporation-coulometric titration method." [2] The cover tape according to [1], having a haze value of less than 25%. [3] The cover tape according to [1] or [2], which does not contain polyamide resin. [4] 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 [3], wherein the intermediate layer contains a polyolefin 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 does not contain a polyamide resin. [6] The cover tape according to [4] or [5], wherein the heat seal layer contains a styrene-based resin as a main component. [7] The cover tape according to any one of [1] to [6], which is for use in packaging for electronic components. [8] An electronic component packaging body comprising the cover tape according to any one of [1] to [7].

Claims

1. A cover tape having a moisture absorption rate (a) of 1,500 mass ppm or less measured under the following conditions: <Conditions> After storing the cover tape under dry conditions of 60°C / 20% RH for 12 hours, the moisture absorption rate (a) of the cover tape is measured at a holding temperature of 280°C in accordance with JIS K0068:2001 "Karl Fischer titration method, moisture evaporation-coulometric titration method."

2. 10. The cover tape of claim 1, having a haze value of less than 25%.

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

4. 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.

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 does not contain a polyamide-based resin.

6. The cover tape according to claim 4 , wherein the heat seal layer contains a styrene-based resin as a main component.

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

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

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