Cover tape and electronic component packaging containing the same

Abstract

To provide a cover tape that absorbs little moisture even under high temperature and low humidity conditions, and an electronic component packaging containing the same. [Solution] A cover tape having a transmittance of over 80% at wavelengths of 1300 to 1500 nm. Preferably, the cover tape has a transmittance of 85% or more at wavelengths of 1200 to 1600 nm. Furthermore, it is preferable that the increase or decrease rate of the transmittance at wavelength 1600 nm (T2) relative to the transmittance at wavelength 1200 nm (T1), as represented by the following formula (1), is 90% or more. (T2 / T1) × 100 (%) ... (1)

Description

TECHNICAL FIELD

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

[0002] Along with the miniaturization of electronic devices, the electronic components used therein have also been made smaller and higher in performance. At the same time, in the assembly process of electronic devices, electronic components are automatically mounted on printed circuit boards. Such chip-type surface-mount electronic components are stored in a carrier tape on which storage pockets thermoformed to match the shape of the electronic components are continuously formed. After the electronic components are stored in each storage pocket, a cover tape is overlaid on the upper surface of the carrier tape as a lid material, and both ends of the cover tape are continuously heat-sealed in the length direction with a heated sealing iron to form an electronic component package.

[0003] By the way, the cover tape may be exposed to high temperature and high humidity during transportation or storage, which may cause the cover tape to absorb moisture. If the moisture absorption rate of the cover tape becomes too high, problems such as occurrence of a blocking phenomenon in the cover tape wound in a roll shape and deterioration of heat sealability may occur. In addition, if the cover tape absorbs moisture after being formed into an electronic component package, there is a concern that the enclosed electronic components may be adversely affected.

[0004] To address such a problem, for example, Patent Document 1 proposes a cover tape that hardly causes blocking even when exposed to an environment of high temperature or high temperature and high humidity. As a result of investigations by the inventors of the present application, it has been found that the cover tape absorbs moisture even under high temperature and low humidity, which tends to cause the above-described problems. PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0005] PATENT DOCUMENT 1 International Publication No. 2013 / 054867 SUMMARY OF THE INVENTION [Problems that the invention aims to solve]

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

[0007] In response to the above-mentioned problems, the inventors of this invention conducted diligent research and, surprisingly, discovered a correlation between the transmittance and moisture absorption rate of the cover tape in the near-infrared wavelength range. Specifically, they found that cover tape with a transmittance of over 80% at wavelengths of 1300-1500 nm is less prone to moisture absorption 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 packaging body containing the same. [Brief explanation of the drawing]

[0009] [Figure 1] This graph shows the transmittance measurement results of the cover tapes in the examples and comparative examples. [Modes for carrying out the invention]

[0010] One embodiment of this disclosure will be described in detail below, but the scope of this disclosure is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of this disclosure. Each embodiment disclosed herein can be combined with any other features disclosed herein. Furthermore, if multiple upper and lower limits are given for a particular parameter, any combination of these upper and lower limits can be used to create a suitable numerical range. Also, the lower and / or upper limits of the numerical ranges described herein may be replaced with numerical values ​​within that range, as shown in the examples. The expression "X~Y" indicating a numerical range means "X or greater and Y or less". If a particular description given for one embodiment also applies to other embodiments, that description may be omitted in the other embodiments.

[0011] Each configuration and its combinations in each embodiment are examples, and configurations can be added, omitted, replaced, and otherwise modified as appropriate, without departing from the spirit of this disclosure. This disclosure is not limited by the embodiments. Each aspect disclosed herein can be combined with any other features disclosed herein.

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

[0013] In one embodiment, from the viewpoint of obtaining a cover tape that absorbs less moisture under high temperature and low humidity conditions, the transmittance at wavelengths of 1300 to 1500 nm may be 83% or higher, 85% or higher, or 88% or higher. In another embodiment, the transmittance in the aforementioned wavelength range may be 90% or higher. Furthermore, from the viewpoint of obtaining a cover tape that absorbs less moisture under high temperature and low humidity conditions due to a high transmittance at wavelengths of 1300 to 1500 nm, there is no particular upper limit to the transmittance in this wavelength range. 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 component constituting the cover tape does not contain a polyamide resin, or when it includes an intermediate layer containing an olefin resin and / or a heat seal layer mainly containing a styrene resin, as described later. In this disclosure, "polyamide resin" generally refers to a polyamide resin containing an aliphatic backbone called nylon (registered trademark).

[0014] The cover tape according to the first embodiment is further preferably 84% or more, and more preferably 85% or more, in the wavelength range of 1200 to 1600 nm. Cover tapes having a transmittance of 84% or more, more preferably 85% or more, in a wavelength range even wider than 1300 to 1500 nm are preferred because they have lower moisture absorption. In this disclosure, "a transmittance of 84% or more in the wavelength range of 1200 to 1600 nm" means that the transmittance of the cover tape is 84% ​​or more at any point within that wavelength range, and 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 using the same method as described above. In one embodiment, the transmittance at wavelengths of 1200 to 1600 nm may be 86% or higher, or 87% or higher. Furthermore, from the viewpoint of obtaining a cover tape with low moisture absorption under high temperature and low humidity conditions, there is no particular upper limit.

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

[0017] If the increase / decrease rate expressed by formula (1) is 90% or more, the cover tape is more likely to absorb moisture less under high temperature and low humidity conditions. As a cover tape that satisfies formula (1), for example, if the transmittance at a wavelength of 1200 nm (T1) is 85%, it is preferable that the transmittance at a wavelength of 1600 nm (T2) is 76.5% or more. Furthermore, a cover tape with a transmittance of 85% or more in the wavelength range of 1200 to 1600 nm is preferable because the increase / decrease rate expressed by formula (1) tends to be 90% or more.

[0018] The upper limit of the increase / decrease ratio represented by the aforementioned formula (1) is not particularly limited as long as the effects of the present invention are achieved. Since the cover tape according to the first embodiment may include an aspect where T1<T2, the increase / decrease ratio may be 100% or more. In one embodiment, the aforementioned increase / decrease ratio may be 90 to 105%, or 95 to 102%.

[0019] A general cover tape, for example, like the cover tape 7 shown in Comparative Example 2 described later, tends to have its transmittance gradually decrease as it shifts to the longer wavelength side of near-infrared rays. In the case of the cover tape 7 shown in Comparative Example 1, the transmittance at a wavelength of 1300 to 1500 nm is 80% or less, and the increase / decrease ratio is also less than 90%. Through studies by the inventors of the present application, it was found that cover tapes such as that of Comparative Example 2 tend to absorb moisture even under high-temperature and low-humidity conditions. The cover tape according to the first embodiment has a high transmittance of over 80% at a wavelength of 1300 to 1500 nm, and the value of the transmittance (T2) at a wavelength of 1600 nm relative to the transmittance (T1) at a wavelength of 1200 nm, which is the increase / decrease ratio of transmittance in a wider wavelength range, tends to be 90% or more. Although the reason for this is not clear, such a cover tape is less likely to absorb moisture even under high-temperature and low-humidity conditions, and defects caused by moisture absorption of the cover tape are less likely to occur. In addition, the cover tape according to the first embodiment is less prone to moisture absorption accompanying changes in temperature and humidity.

[0020] <Layer Structure> The cover tape according to the first embodiment may have a multilayer structure in which a base material layer, an intermediate layer, and a heat seal layer are laminated in this order. For each layer constituting the cover tape according to the first embodiment, it is necessary to select thermoplastic resins, additives and the like so that the transmittance of the cover tape at a wavelength of 1300 to 1500 nm exceeds 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] Hereinafter, an example of a configuration of a cover tape comprising at least a base material layer, an intermediate layer, and a heat seal layer, which easily achieves the transmittance requirement of the cover tape according to the first embodiment will be described, but the configuration of the cover tape according to the first embodiment is not limited to the following.

[0022] <Base Material Layer> The base material layer is a layer containing a thermoplastic resin, and is preferably composed of a film formed by film-forming the thermoplastic resin. The thermoplastic resin constituting the base material layer is preferably selected from the viewpoint that the transmittance at a wavelength of 1300 to 1500 nm easily exceeds 80%, and it satisfies the mechanical properties required for the cover tape. In one embodiment, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyolefin resins such as polypropylene, polycarbonate resins and the like are preferable. Further, the base material layer is more preferably constituted by a biaxially stretched film.

[0023] The base material layer preferably does not contain a polyamide resin, and is more preferably constituted by a film of a polyester resin such as a biaxially stretched polyethylene terephthalate film or biaxially stretched polyethylene naphthalate.

[0024] The thickness of the base material layer is generally arbitrarily set from the range of 5 to 50 μm in consideration of the mechanical properties of the cover tape and the like. In the cover tape according to the first embodiment, the thickness of the base material layer is set such that the transmittance at a wavelength of 1300 to 1500 nm exceeds 80%, or the transmittance at a wavelength of 1200 to 1600 nm is 85% or more. It is preferable to set. From these viewpoints, the thickness of the base material layer is preferably 10 to 30 μm, more preferably more than 10 μm and 30 μm or less, and still more preferably 12 to 20 μm.

[0025] In one embodiment, at least one surface of the substrate layer may be surface-treated. Suitable surface treatments include sandblasting, corona discharge, and plasma treatment. In one embodiment, it is preferable that the surface of the substrate layer on which the intermediate layer is laminated is surface-treated. Surface treatment of the substrate layer tends to improve the adhesive strength between the substrate layer and the intermediate layer.

[0026] <Middle class> The intermediate layer is a layer of thermoplastic resin laminated to one side of the base layer, with an adhesive layer or anchor coat layer as needed. The inventors of the present invention have found that the transmittance of the cover tape in the near-infrared wavelength range is easily affected by the thermoplastic resin constituting the intermediate layer. Further investigations by the inventors have shown that the transmittance at wavelengths of 1300 to 1500 nm tends to be 80% or higher when the intermediate layer does not contain a polyamide resin. Furthermore, from the viewpoint of easily achieving a transmittance of 85% or higher at wavelengths of 1200 to 1600 nm, the inventors have also found that it is preferable for the intermediate layer to not contain a polyamide resin but to contain a polyolefin resin.

[0027] Examples of polyolefin resins that can be used include polyethylene (e.g., low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), very low-density polyethylene (VLDPE), etc.), ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-pentene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ethylene-maleic acid copolymer, styrene-ethylene graft copolymer, styrene-propylene graft copolymer, styrene-ethylene-butadiene block copolymer, polypropylene, etc. These polyolefin resins may be used individually or as a mixture of two or more types. Furthermore, the intermediate layer may consist of 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 obtaining a cover tape that easily achieves a transmittance of over 80% at wavelengths of 1300 to 1500 nm and exhibits low moisture absorption under high temperature and low humidity conditions, it is preferable that the intermediate layer contains only a polyolefin resin as its resin component, and more preferably only LLDPE. Furthermore, from the viewpoint of obtaining a cover tape that particularly exhibits low moisture absorption under high temperature and low humidity conditions, it is preferable to have 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). Here, "the same type of polyolefin resin" means that the olefin units contained in the polyolefin resin are the same, but their molecular weights, etc., may differ. When the intermediate layer has a multilayer structure, the intermediate layer may be laminated directly on the base layer without an anchor coat layer in between.

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

[0030] The above-mentioned m-LLDPE is a copolymer of ethylene and an α-olefin substituted with an olefin having 3 or more carbon atoms, preferably a linear, branched, or aromatic nucleus having 3 to 18 carbon atoms, as a comonomer. Examples of linear monoolefins include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-octadecene. Examples of branched monoolefins include 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, and 2-ethyl-1-hexene. Examples of monoolefins substituted with aromatic nuclei include styrene. These comonomers can be copolymerized with ethylene individually or in combination of two or more. In this copolymerization, polyenes such as butadiene, isoprene, 1,3-hexadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene may be copolymerized.

[0031] In cover tapes, 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 determined 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 from the viewpoint of obtaining a cover tape with low moisture absorption under high temperature and low humidity conditions by further controlling the transmittance at wavelengths of 1300 to 1500 nm to more than 80%. 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 contains a thermoplastic resin that exhibits heat-sealing properties to the carrier tape and is easily peelable, allowing for easy removal during use. It can also be selected from the viewpoint that the transmittance of the cover tape at wavelengths of 1300 to 1500 nm tends to exceed 80%. From these viewpoints, the thermoplastic resin included in the heat seal layer is preferably an ethylene-based resin such as polyethylene (e.g., LDPE, LLDPE, VLDPE, etc., as exemplified in the intermediate layer mentioned above), ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-butene-1 random copolymer; or a styrene-based resin such as styrene-butadiene copolymer (SB), styrene-butadiene-styrene block copolymer (SBS) or its hydrogenated product (SEBS), polystyrene (PS), styrene-butadiene copolymer (SBC), or high-impact polystyrene (HIPS). These thermoplastic resins may be used individually or in combination of two or more.

[0033] In one embodiment, the heat seal layer preferably contains a styrene-based resin as its main component. In this case, the transmittance at wavelengths of 1300 to 1500 nm tends to exceed 80%, and as a result, a cover tape with low moisture absorption under high temperature and low humidity conditions is easily obtained. In this disclosure, "contains a styrene-based resin as its main component" means that the styrene-based resin is present in an amount of more than 50% by mass relative to the total amount (100% by mass) of all resin components. The proportion of styrene-based resin in the heat seal layer is preferably more than 50% by mass and 100% by mass or less, more preferably 70% to 100% by mass, and particularly preferably more than 70% by mass and 100% by mass or less. In one preferred embodiment, from the viewpoint of making it easier to obtain a cover tape with 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, the heat seal layer more preferably contains as a main component at least one styrene-based resin selected from SB, SEBS, and SBC.

[0034] The thickness of the heat seal layer is generally determined from the viewpoint of heat sealability 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 from the viewpoint of obtaining a cover tape with low moisture absorption under high temperature and low humidity conditions by controlling the transmittance at wavelengths of 1300 to 1500 nm to more than 80%. In one embodiment, the thickness of the heat seal layer is preferably 3 to 30 μm, and more preferably 5 to 25 μm.

[0035] In one embodiment, the heat seal layer may contain one or more antistatic agents, as described later. By containing antistatic agents, the heat seal layer becomes a layer that possesses 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 an adhesive layer or anchor coat layer is provided, an anchor coat agent such as a polyurethane adhesive, polyethyleneimine, modified polybutadiene, or organic titanate compound can be used, as can a hot melt adhesive such as a polyolefin resin, ethylene-vinyl acetate resin, ethylene-acrylic acid ester resin, or vinyl chloride-vinyl acetate resin. Of these, from the viewpoint of providing a cover tape that is less susceptible to moisture absorption under high temperature and low humidity conditions, it is preferable that the anchor coat layer contains 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 the anchor coat layer, the polyolefin resin constituting the intermediate layer is preferably a single layer, and it is more preferable to have an intermediate layer consisting of a base layer / anchor coat layer / polyolefin resin such as LLDPE. With such a configuration, the aforementioned transmittance tends to exceed 80%, and the cover tape tends 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. By having an antistatic layer, an antistatic effect can be imparted to the cover tape, making it easier to prevent the electronic components from being dielectric broken down by static electricity. 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 antimond-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.), polyalkylene glycols such as polyether esters having a polyoxyalkylene structure and ester bonds.

[0040] As an ionic liquid containing a cyclic quaternary nitrogen-containing cation (hereinafter simply referred to as "ionic liquid"), from the viewpoint of easily achieving the aforementioned 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 quaternary ammonium salts, from the viewpoint of easily achieving the aforementioned transmittance and easily imparting the desired antistatic properties, for example, trimethyl laurylammonium methyl sulfate, ethyl dimethyl stearylammonium ethyl sulfate, ethyl dimethyl oleylammonium ethyl sulfate, ethyl dimethyl laurylammonium ethyl sulfate, ethyl dimethyl stearylammonium metasulfonium, ethyl dimethyl laurylammonium metasulfonium, etc. can be used.

[0042] Furthermore, the antistatic layer may contain the antistatic agent and a binder resin. The binder resin can be polyurethane resin, acrylic resin, polyvinyl chloride resin, ethylene-vinyl acetate resin, polyester resin, butadiene resin, hydrogenated styrene resin, acrylic-modified polyester resin, etc., either alone or in combination of two or more. From the viewpoint of easily controlling the transmittance at wavelengths of 1300-1500 nm to over 80%, it is preferable that the binder resin does not contain polyamide resin.

[0043] When the cover tape according to the first embodiment is equipped with an antistatic layer, it is preferable that it contains at least one selected from ionic liquid, ATO, and aluminum oxide, from the viewpoint that the transmittance at wavelengths of 1300 to 1500 nm tends to exceed 80%, and the transmittance at wavelengths of 1200 to 1600 nm tends to be 84% or more. Furthermore, when incorporating the aforementioned preferred antistatic agent, the proportion of the antistatic agent is preferably 90% by mass or less relative to the total mass of the resin composition constituting the antistatic layer.

[0044] From the viewpoint of easily achieving both antistatic properties and the aforementioned transmittance, the thickness of the antistatic layer is preferably 0.01 to 2.0 μm.

[0045] (Total thickness of the cover tape) In the first embodiment, the total thickness of the cover tape is preferably 40 to 65 μm, from the viewpoint of easily achieving the various physical properties required for the cover tape and easily obtaining 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 increase / decrease rate of 90 to 100%, the total thickness of the cover tape may be 40 to 50 μm, 42 μm or more and less than 50 μm, or 45 μm or more and less than 50 μm.

[0046] <How to manufacture cover tape> The cover tape according to the first embodiment can be manufactured, for example, by laminating the aforementioned layers so that the transmittance at wavelengths of 1300 to 1500 nm exceeds 80%. Below, an embodiment of a method for manufacturing a cover tape according to the first embodiment, comprising 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 seal layer to achieve a transmittance of over 80% at a wavelength of 1300 to 1500 nm. At this time, from the viewpoint of easily achieving a transmittance of over 80%, it is preferable to include step (1) in which the thermoplastic resins constituting the base layer, intermediate layer, and heat seal layer are selected such that polyamide resins are not included in each layer. Furthermore, from the viewpoint of making it easier to control the transmittance to over 80%, it is preferable in step (1) to select the thermoplastic resins for each layer such that the intermediate layer contains an olefin resin and the heat seal layer contains a styrene resin as its main component.

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

[0049] (Process (2)) For example, the T-die casting method or the inflation method can be used to form the heat seal layer. Furthermore, when incorporating an antistatic agent into the heat seal layer, a resin composition containing the aforementioned antistatic agent may be prepared in advance by pre-blending using a tumbler, and then the resin composition may be used to form the film.

[0050] (Step (3)) One method for coating a substrate layer with an intermediate layer resin composition is to extrude the intermediate layer resin composition (preferably a polyolefin resin, particularly preferably containing LLDPE) from 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 as needed, and the intermediate layer may be laminated onto the surface coated with the anchor coating agent.

[0051] (Step (4)) For laminating the base layer, intermediate layer, and heat seal layer, it is preferable to perform sand lamination by further layering the heat seal layer, which has been formed, on top of the intermediate layer obtained in step (3).

[0052] (Step (5)) In one preferred embodiment, the process further includes laminating an antistatic layer on the heat seal layer (step (5)). For 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, reverse coater, kiss coater, air knife coater, Meyer bar coater, dip coater, or the like.

[0053] In one embodiment, the manufacturing method may include, after 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 with a substrate layer (step (7)).

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

[0055] (Process (7)) For laminating the two-layer film and the base layer, it is preferable to apply an anchor coating agent (preferably a polyurethane-based 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 where the anchor coating agent is applied by a dry lamination method.

[0056] (Process (8)) After step (7), the process may further include laminating an antistatic layer onto the surface of the heat seal layer (step (8)). Step (8) may be 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 constituting a part of the intermediate layer (step (10)), and laminating them so that the intermediate layer side of the two-layer film and the intermediate layer side of the base layer are in contact (step (11)).

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

[0059] (Step (10)) When coating a base layer with a resin composition that constitutes part of the intermediate layer, it is preferable to extrude the resin composition (preferably a polyolefin resin, particularly preferably LLDPE) that constitutes part of the intermediate layer from a T-die and coat it onto the surface of the base layer (preferably a biaxially oriented polyester film). If necessary, before coating the resin composition, an anchor coating agent (preferably a polyurethane adhesive) may be applied to the surface of the base layer, and the intermediate layer may be laminated onto the surface coated with the anchor coating agent.

[0060] (Step (11)) After step (10), the two-layer film is laminated so that the intermediate layer side of the two-layer film is in contact with the intermediate layer side of the substrate layer (sand lamination). The process may also include laminating an antistatic agent on top of the heat seal layer (step (12)). Step (11) may be the same method as in step (5).

[0061] The intermediate layer of the cover tape obtained by the above steps (9) to (11) (or steps (9) to (12)) consists of two layers: a layer formed by co-extrusion with the heat-seal layer and a layer formed by sand lamination. From the viewpoint of easily achieving a transmittance of over 80%, the thickness of the layer formed by sand lamination is preferably 10 to 20 μm.

[0062] The manufacturing method according to this embodiment may, in addition to the steps described above, optionally include applying an antistatic treatment to the surface of the base material layer of the cover tape (the surface not in contact with the intermediate layer). Examples of antistatic agents are those described above, and the preferred examples are also the same. The antistatic treatment can be applied by a roll coater using a gravure roll, a lip coater, a spray, etc. Furthermore, in order to uniformly apply these antistatic agents, it is preferable to perform a corona discharge treatment or an ozone treatment on the film surface before performing 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 electronic component packaging.

[0064] As described above, the cover tape according to the first embodiment is less susceptible 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, 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 the "Moisture vaporization-coulometric titration method" of JIS K0068:2001.

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

[0066] [Electronic component packaging] A second embodiment of this disclosure relates to an electronic component packaging. A package containing electronic components (hereinafter referred to as "electronic component package") can be obtained, for example, by placing electronic components in recesses on a carrier tape, then using a cover tape as a lid, and continuously heat-sealing both longitudinal edges of the cover tape using a hot iron or the like, before winding it onto a reel. Electronic components are stored and transported in this packaged form. The electronic component package according to the second embodiment can be used for storing and transporting various electronic components such as connectors, ICs, diodes, transistors, capacitors, resistors, and LEDs. When storing or transporting an electronic component package, it is stored and transported under conditions with minimal temperature and humidity changes to avoid moisture absorption of the electronic component package, including the cover tape, due to temperature and humidity changes, and the resulting problems with the stored contents (electronic components). However, as described above, according to the inventors' research, moisture absorption of the cover tape can occur even under high temperature and low humidity conditions, so a cover tape that is less susceptible to moisture absorption even under low humidity conditions is required. The electronic component packaging according to the second embodiment is equipped with the aforementioned cover tape, and is therefore less susceptible to moisture absorption even under high temperature and low humidity conditions. As a result, problems with electronic components caused by moisture absorption by the cover tape are also less likely to occur.

[0067] The electronic component packaging is transported using holes called sprocket holes, which are located along the longitudinal edge of the carrier tape, and the cover tape is intermittently peeled off. The electronic components are then removed by a component mounting device, which checks their presence, orientation, and position, and then mounted onto the circuit board.

[0068] The carrier tape included in the electronic component packaging according to the second embodiment is a strip-shaped material with a width of approximately 4 mm to 100 mm and having a recess for housing electronic components. When heat-sealing the cover tape according to the first embodiment as a lid material, the material constituting the carrier tape is not particularly limited, but carrier tapes containing polystyrene resin, polyester resin, or polycarbonate resin can be suitably used. The carrier tape may be one in which conductivity is imparted by kneading carbon black or carbon nanotubes into the resin, one in which a surfactant-type antistatic agent such as cationic, anionic, or nonionic, or a long-lasting antistatic agent such as polyether ester amide is kneaded into the resin, or one in which antistatic properties are imparted by applying a coating solution to the surface 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, the electronic component packaging can be inspected with an IR camera over the cover tape to detect defects in the electronic components inside and to recognize circuits printed on the electronic components. The cover tape according to the first embodiment has high transmittance in the near-infrared region, so it is also easily visible by an IR camera.

[0070] Another embodiment of the present disclosure is a method for suppressing moisture absorption of 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%. Preferably, the method further includes controlling the transmittance of the cover tape at wavelengths of 1200 to 1600 nm to 84% or more. Preferably, the method further includes controlling the increase or decrease rate of the transmittance at wavelength 1600 nm (T2) to the transmittance at wavelength 1200 nm (T1), as represented by the following formula (1), to 90% or more. (T2 / T1) × 100 (%) ... (1) [Examples]

[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] <Manufacturing of cover tapes 1-6> The thermoplastic resins listed in Table 1 were selected as the thermoplastic resins to constitute each layer. The thickness of each layer was determined as shown in Table 1. Subsequently, the base layer, intermediate layer, heat seal layer, and antistatic layer were laminated in order according to the aforementioned steps (2) to (5). Specifically, the heat seal layer was formed by extruding the resin composition for the heat seal layer using a single-screw extruder with a T-die method. Next, the formed heat seal layer and the base layer (PET film) were extruded and 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 applied on top of 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 applied on top of the base layer, and then the intermediate layer was laminated on the surface of the anchor coat layer.

[0073] <Manufacturing of cover tapes 7-8> The thermoplastic resins listed in Table 1 were selected as the thermoplastic resins to constitute each layer, and the thickness of each layer was determined as shown in Table 1. Subsequently, the base layer, intermediate layer, heat seal layer, and antistatic layer were laminated according to the aforementioned 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 the intermediate layer, and between the intermediate layer and the heat seal layer.

[0074] [Table 1]

[0075] The ingredients 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 resin 1: Resin composition containing SBC and SB • Styrene resin 2: SEBS • Styrene resin 3: SB • Ethylene-based resin: LLDPE • Mixed resin: Resin composition containing SB and LLDPE (containing LLDPE as the main component) <Antistatic layer> • Antistatic agent 1: A mixture of ionic liquid (1-ethyl-3-methylimidazolium ethyl sulfate), quaternary ammonium salt (ethyl dimethyl laurylammonium ethyl sulfate), and polyethylene glycol (concentration of antistatic agent: 0.5% by mass) • Antistatic agent 2: ATO • Antistatic agent 3: Aluminum oxide • Antistatic agent 4: Barium sulfate • Antistatic agent 5: Mixture of barium sulfate and tin oxide Furthermore, the "-" notation in Table 1 indicates that an anchor coat layer was not provided.

[0076] [Examples 1-5 and Comparative Examples 1-3] For each cover tape listed in Table 2, the transmittance and moisture absorption rate were measured using the method described below. The results are shown in Table 2.

[0077] <Method for measuring transmittance> The transmittance of cover tapes 1-8 at wavelengths of 1200-1600 nm was measured using the following method. The results are shown in Table 2 and Figure 1. As measurement and analysis equipment, a UV-Vis-Near-Infrared spectrophotometer (Shimadzu Corporation, product name "UV-3600") and a multi-purpose large sample chamber (φ60mm, with built-in integrating sphere; Shimadzu Corporation, product name "MPC-3100") were used. First, baseline correction was performed without the cover tape, and then the cover tape was attached, and the spectral transmittance at wavelengths of 1200 to 1600 nm was measured using the integrating sphere.

[0078] <Method for measuring moisture absorption rate under high temperature and low humidity conditions> The moisture absorption rates of cover tapes 1-8 were measured using 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 the "Moisture vaporization-coulometric titration method" of JIS K0068:2001. The tape was also evaluated according to the following evaluation criteria, and a rating of B or higher was considered acceptable. (Evaluation Criteria) A: The moisture absorption rate under high temperature and low humidity conditions was 1000 ppm by mass or less. B: Under high temperature and low humidity conditions, the moisture absorption rate was between 1000 ppm by mass and 1500 ppm by mass. C: The moisture absorption rate under high temperature and low humidity conditions was over 1500 ppm by mass.

[0079] [Table 2]

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

[0081] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of this disclosure is provided below. [1] A cover tape having a transmittance of over 80% at wavelengths of 1300-1500 nm. [2] The cover tape described in [1], wherein the transmittance at wavelengths of 1200 to 1600 nm is 84% ​​or more. [3] The cover tape described in [1] or [2], wherein the increase or decrease rate of the transmittance at a wavelength of 1600 nm (T2) relative to the transmittance at a wavelength of 1200 nm (T1), as expressed by the following formula (1), is 90% or more. (T2 / T1) × 100 (%) ... (1) [4] A cover tape according to any of [1] to [3], which does not contain polyamide resin. [5] At a minimum, the base layer, the intermediate layer, and the heat seal layer are laminated in this order. The cover tape according to any one of [1] to [4], wherein the intermediate layer comprises a polyolefin resin. [6] At a minimum, the base layer, the intermediate layer, and the 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 comprises a styrene resin as the main component. [8] Cover tape for electronic component packaging, as described in any of [1] to [7]. Electronic component packaging including the cover tape described in any of [9][1] to [8].

Claims

1. A cover tape with a transmittance of over 80% at wavelengths of 1300-1500 nm.

2. The cover tape according to claim 1, wherein the transmittance at a wavelength of 1200 to 1600 nm is 84% ​​or more.

3. The cover tape according to claim 1 or 2, wherein the increase or decrease rate of the transmittance at a wavelength of 1600 nm (T2) relative to the transmittance at a wavelength of 1200 nm (T1), as expressed by the following formula (1), is 90% or more. (T2 / T1)×100(%)...(1)

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

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

6. At a minimum, the base layer, the intermediate layer, and the 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 resin.

7. The cover tape according to claim 5, wherein the heat seal layer mainly comprises a styrene resin.

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

9. An electronic component packaging comprising the cover tape described in claim 1 or 2.

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