KR102247258B1 - Cover film and electronic component package - Google Patents

Abstract

A cover film in which a base layer, an intermediate layer, a release layer, and a heat seal layer are arranged in this order, wherein the release layer is 50 to 80% by weight of at least one copolymer selected from a styrene-diene block copolymer and a styrene-diene graft copolymer. Styrene-(meth)acrylic containing a resin composition essentially consisting of 50 to 20% by weight of an ethylene-α-olefin copolymer, a non-cut softening temperature of 55 to 80°C, and a heat seal layer having a styrene content of 50 to 80% by weight A cover film containing a rate copolymer, and an electronic component package using the cover film as a cover material for a carrier tape are disclosed.

Description

Cover film and electronic component package {COVER FILM AND ELECTRONIC COMPONENT PACKAGE}

The present invention relates to a cover film and an electronic component package for use in an electronic component package.

With the miniaturization of electronic devices, miniaturization and high performance of electronic components are being improved, and in the assembly process of electronic devices, components are automatically mounted on a printed circuit board. The surface-mounting electronic component is housed in a carrier tape in which pockets are continuously embossed to match the shape of the electronic component. After the electronic parts are stored, the cover film is superimposed on the upper surface of the carrier tape and heat-sealed with a seal bar, which is heat-sealed at both ends of the cover film in the longitudinal direction to form a package. As the cover film material, a biaxially stretched polyester film is used as a base material, and a heat seal layer made of a thermoplastic resin is laminated, and the like is used. As carrier tapes, those made mainly of thermoplastic resin polystyrene or polycarbonate are used.

Recently, various electronic components such as capacitors, resistors, ICs, LEDs, connectors, and switching elements are undergoing remarkable reduction in size, weight, and thickness. The required performance is becoming more difficult than before. When the cover film is peeled off, if the difference between the maximum and minimum values of the peel strength, that is, the "range width", is large, the carrier tape vibrates violently and the electronic parts protrude, causing a failure in mounting. Further, electronic components transported by the electronic component packaging body have been miniaturized with higher performance in accordance with the recent remarkable improvement in surface mounting technology. Such electronic parts may be damaged by generating static electricity due to wear of the inner surface of the carrier tape emboss, the inner surface of the cover film, and the electronic parts due to vibration during transport of the electronic parts package. In addition, the same situation may also occur due to static electricity generated when peeling the cover film from the carrier tape. Therefore, countermeasures against static electricity for carrier tapes and cover films have become the most important issue.

Electronic components are sometimes inspected for presence or absence of components, storage directions of components, defects or curves of leads while being stored in a package. In recent years, according to the miniaturization of electronic components, very high transparency is required for the cover film for inspection of the components contained in the package body. In addition, since the phenomenon that parts adhere to the cover film due to slight static electricity due to the miniaturization of parts is on the surface, in the cover film currently in the market, conductive fine particles such as tin oxide or zinc oxide are added to the heat seal layer as a countermeasure against static electricity. It has been made to suppress the attachment of parts (refer to Patent Document 1). However, in such a method, when the cover film is peeled, the surface of the cover film is charged, and it is difficult to obtain a sufficient effect of suppressing peeling and charging. On the other hand, a method of suppressing static electricity generated when a cover film is peeled from a carrier tape by providing a static electricity diffusion layer between the intermediate layer and the heat seal layer has been proposed (see Patent Document 2). In addition, a method of suppressing peeling charge by making the heat seal layer into a two-layer structure and cohesively destroying one of the heat seal layers upon peeling has been proposed (refer to Patent Document 3). However, with regard to reducing the range of the peel strength due to miniaturization of electronic components, a higher level is required, and the required performance has not yet been satisfied even in the methods of Patent Documents 2 and 3 in some cases.

Japanese Unexamined Patent Application Publication No. Hei 8-258888 Japanese Unexamined Patent Application Publication No. Hei 7-223674 Japanese Unexamined Patent Application Publication No. 2012-214252

In view of the above problems and circumstances, an object of the present invention is to provide a cover film in which charging due to friction between a storage object and a cover film or peeling charging when taking out an electronic component is suppressed. Further, it is an object of the present invention to provide a cover film in which troubles in the mounting step are reduced by suppressing variations in peel strength.

As a result of careful examination of the above problems, the present inventors overcome the problems of the present invention by using a specific thermoplastic resin for the heat seal layer and using a thermoplastic resin of a specific composition for the release layer to set the non-cut softening temperature to a predetermined range. It was found that a cover film was obtained and came to the present invention.

That is, in one aspect of the present invention, as a cover film in which a base layer (A), an intermediate layer (B), a release layer (C), and a heat seal layer (D) are arranged in this order, the release layer (C) is a styrene-diene block. A resin composition essentially consisting of 50 to 80% by weight of one or more copolymers selected from copolymers and styrene-diene graft copolymers and 50 to 20% by weight of an ethylene-α-olefin copolymer, and at 55 to 80°C There is provided a cover film having a non-cut softening temperature, and the heat seal layer (D) contains a styrene-(meth)acrylate copolymer having a styrene content of 50 to 80% by weight.

In the above aspect, at least one layer of the peeling layer (C) or the heat seal layer (D) may contain conductive fine particles. These conductive fine particles are preferably fibrous or spherical. In addition, in one embodiment, the thickness of the base layer (A) is 12 to 20 μm, the thickness of the intermediate layer (B) is 10 to 40 μm, the thickness of the release layer (C) is 5 to 20 μm, and the total thickness of the cover film is The thickness is 45-65㎛. In addition, in one embodiment, the haze value of the cover film is 30% or less.

In another aspect, there is provided an electronic component packaging body using the cover film according to the present invention as a cover material for a carrier tape formed of a thermoplastic resin. Here, it is preferable that the thermoplastic resin of the carrier tape is polycarbonate. In addition, in one embodiment, the electronic component package body has an absolute value of the peeling electrification voltage when peeling the cover film from the carrier tape of 70 V or less. In another embodiment, in the electronic component package, the absolute value of the frictional electrification voltage generated between the cover film and the carrier tape is 70 V or less.

In the present invention, by using a cover film having a heat seal layer having a specific composition and a release layer having a specific composition, composition range, and non-cut softening temperature, charging due to friction between the storage object and the cover film, or electronic parts, even in a low humidity environment. In order to take out, peeling charge generated when the cover film is peeled is remarkably suppressed. For this reason, when the cover film of the present invention is used as a cover material for a carrier tape, troubles caused by charging in the mounting process are remarkably improved.

1 is a schematic cross-sectional view of a cover film according to an embodiment of the present invention.

Hereinafter, a cover film, a carrier tape, and an electronic component package according to the present invention will be described in order of preferred embodiments thereof.

<cover film>

The cover film according to the embodiment of the present invention is a cover film in which a base layer (A), an intermediate layer (B), a release layer (C), and a heat seal layer (D) are arranged in this order. An example of the structure of the cover film of this embodiment is shown in FIG.

[Substrate layer (A)]

The base material layer (A) is a layer containing biaxially stretched polyester or biaxially stretched nylon, biaxially stretched polyethylene terephthalate (PET), biaxially stretched polyethylene naphthalate (PEN), and biaxially stretched 6,6- Nylon and biaxially stretched 6-nylon can be particularly suitably used. Antistatic agents for antistatic treatment can be added to biaxially stretched PET, biaxially stretched PEN, biaxially stretched 6,6-nylon, and biaxially stretched 6-nylon. In addition, in order to improve the adhesion with the intermediate layer (B) on one side of the base layer (A) on which the intermediate layer (B) is laminated, a two-liquid reaction type or thermosetting anchor coat agent such as acrylic, urethane, and epoxy is used. Coating, corona discharge treatment, easy adhesion treatment, or the like may be performed.

It is preferable that the thickness of the base layer (A) is 12 to 20 μm. Since the tensile strength of the cover film itself increases by making the base material layer (A) 12 micrometers or more, when peeling a cover film, "film breakage" becomes difficult to generate|occur|produce. On the other hand, by setting it as 20 micrometers or less, heat sealability with respect to a carrier tape is improved.

[Intermediate layer (B)]

The intermediate layer (B) is laminated on one side of the base layer (A) through an adhesive layer or the like as necessary as described above, and is disposed between the base layer (A) and the release layer (C). The resin constituting the intermediate layer (B) includes polyolefins such as polyethylene and polypropylene, but among these, linear low-density polyethylene (hereinafter referred to as LLDPE) that has flexibility and moderate stiffness and excellent bursting strength at room temperature (hereinafter referred to as LLDPE). This is desirable. In particular, LLDPE with a density of 0.880 to 0.925 (×10 ³ kg/m ³ ) is difficult to elute of the intermediate layer resin from the end of the cover film due to heat or pressure during heat sealing. It is difficult to cause contamination. In addition, since LLDPE having a density in this range is excellent in alleviating the stress partially generated by the heat seal iron, stable peeling strength is easily obtained when peeling the cover film.

LLDPE includes ones polymerized with a Ziegler-type catalyst and ones polymerized with a metallocene-based catalyst (hereinafter referred to as m-LLDPE). Since m-LLDPE has a narrow molecular weight distribution, it has particularly high tear strength, and it is preferable to use this m-LLDPE as the intermediate layer (B) of the present invention.

The m-LLDPE is a copolymer of ethylene with an olefin having 3 or more carbon atoms as a comonomer, preferably an α-olefin substituted with a linear, branched, or aromatic nucleus having 3 to 18 carbon atoms. As a linear monoolefin, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene And 1-octadecene. Moreover, as a branched monoolefin, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-hexene, etc. are mentioned, for example. Moreover, styrene etc. are mentioned as a monoolefin substituted with an aromatic nucleus. These comonomers can be copolymerized with ethylene alone 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.

The thickness of the intermediate layer (B) is preferably 10 to 40 μm. When the thickness of the intermediate layer (B) is 10 μm or more, the adhesive strength between the base layer (A) and the intermediate layer (B) is improved, and when heat sealing the cover film to the carrier tape, the heat seal iron It becomes easy to obtain the effect of alleviating contact unevenness. On the other hand, by setting it as 40 micrometers or less, since the total thickness of a cover film becomes a suitable range, a peeling strength sufficient for heat sealing a cover film to a carrier tape can be obtained. In addition, the intermediate layer (B) may be a double layer, as in the example of a two layer to be described later.

[Peeling layer (C)]

The cover film of the present invention includes a release layer (C) between the intermediate layer (B) and the heat seal layer (D).

The release layer (C) is a resin consisting essentially of 50 to 80% by weight of one or more copolymers selected from styrene-diene block copolymers and styrene-diene graft copolymers and 50 to 20% by weight of an ethylene-α-olefin copolymer It is formed into a composition. Here, the expression "consisting essentially of" means that the resin composition is a styrene-diene block copolymer or a styrene-diene graft copolymer and ethylene-α- as long as it is an amount that does not interfere with achieving the desired effect of the present invention. It means that it does not exclude what contains a resin component other than an olefin copolymer. By using at least 50% by weight of one or more copolymers selected from styrene-diene block copolymers and styrene-diene graft copolymers, adhesion to the heat seal layer is improved, and stable peel strength between the release layer and the heat seal layer is achieved. You can get it. Further, when the content is 80% by weight or less, the adhesive strength between the layers of the release layer and the heat seal layer can be adjusted to an appropriate range, and the change in the peel strength due to the passage of time after heat sealing can be suppressed. Here, in order to further stabilize the peel strength between the peeling layer (C) and the heat seal layer (D), 60 to 75% by weight of at least one copolymer selected from a styrene-diene block copolymer and a styrene-diene graft copolymer , The ethylene-α-olefin copolymer is preferably 40 to 25% by weight.

Styrene-diene block copolymers include diblock copolymers of styrene and butadiene, triblock copolymers of styrene-butadiene-styrene, block copolymers of styrene and isoprene, triblock copolymers of styrene-isoprene-styrene, and hydrogenated (水添) resin, etc. are mentioned. Among these, a diblock copolymer of styrene and butadiene is preferable from the viewpoint of heat sealability.

Styrene-diene graft copolymers include high-impact polystyrene (HI-PS) in which polybutadiene is graft-polymerized with polystyrene, ABS resin in which styrene and acrylonitrile are graft-polymerized in polybutadiene, and polybutadiene with styrene and methylmethacrylate Polymerized MBS resin, etc. are mentioned. Among these, high-impact polystyrene is preferable from the viewpoint of heat sealability.

Examples of α-olefins in the ethylene-α-olefin copolymer include propylene, 1-butene, 2-methyl-1-propene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, and 2-ethyl -1-butene, 2, 3-dimethyl-1-butene, 1-pentene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1 -Butene, 1-heptene, methyl-1-hexene, dimethyl-1-pentene, ethyl-1-pentene, trimethyl-1-butene, methylethyl-1-butene, 1-octene, methyl-1-pentene, ethyl- 1-hexene, dimethyl-1-hexene, propyl-1-heptene, methylethyl-1-heptene, trimethyl-1-pentene, propyl-1-pentene, diethyl-1-butene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, etc. are mentioned. The ethylene-α-olefin copolymer may be a random copolymer and a block copolymer, but among them, from the viewpoint of compatibility with a styrene-diene block copolymer and a styrene-diene graft copolymer, a random copolymer is preferable. Do. Further, the ethylene-?-olefin copolymer may be used in combination of two or more.

In addition, the peeling layer (C) has a non-cut softening temperature of 55 to 80°C, preferably 60 to 75°C in the A120 method of JIS K-7206. By setting the non-cut softening temperature to 55°C or higher, excessive softening of the release layer (C) and protrusion of the release layer (C) can be suppressed when heat sealing the cover film, so contamination or peel strength of the seal head The difference can be reduced. Moreover, by setting it as 80 degreeC or less, the peeling layer (C) softens enough, and favorable peeling strength can be obtained. Adjustment of the non-cut softening temperature can be carried out by changing the type or blending ratio of each copolymer constituting the resin composition of the release layer (C) and its monomers.

In addition, it is preferable to contain conductive fine particles in the release layer (C). It is preferable that the conductive fine particles are fibrous or spherical. Examples of the fibrous conductive fine particles include fibrous carbon such as carbon nanotubes, carbon nanofibers, and carbon fibers. Spherical conductive fine particles include carbon black such as acetylene black and Ketjen black, aluminum powder, gold powder, silver powder, copper powder, nickel powder, platinum powder, metal powder such as palladium powder, metal such as alumina, zinc oxide, and tin oxide. Oxide powder, etc. are mentioned. Among these, acetylene black and tin oxide are preferred, and antimony-doped tin oxide is more preferred from the viewpoint of dispersibility in resin and easy to form percolation. The content of the conductive fine particles is not limited as long as the surface resistivity of the release layer is 10 to 10 ¹² Ω/□, preferably 10 ⁶ to 10 ^{12 Ω/□.}

The thickness of the release layer (C) is preferably 5 to 20 µm. By making the thickness of the release layer (C) 5 µm or more, sufficient peel strength can be obtained when the cover film is heat-sealed to the carrier tape. On the other hand, by making the thickness of the peeling layer (C) 20 µm or less, it becomes easy to obtain sufficient peel strength in an ultra-high-speed heat seal, and the difference in peel strength can be suppressed when peeling the cover film. In addition, as will be described later, the release layer (C) can be formed by a method in which the resin composition constituting the release layer is usually hot-melted with an extruder and extruded with an inflation die, a T die, or the like.

[Heat seal layer (D)]

The cover film of the present invention includes a heat seal layer (D) on the surface of the release layer (C). The heat seal layer (D) is made of a thermoplastic resin, but in particular, a copolymer of styrene and (meth)acrylate is used. Examples of (meth)acrylates include acrylate esters such as methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and cyclohexyl methacrylate. And acrylate esters. These may be those obtained by copolymerizing two or more types of (meth)acrylates. In addition, any form of copolymerization, such as random copolymerization of styrene and (meth)acrylate, graft copolymerization, and block copolymerization, can be used.

The content of styrene in the copolymer of the heat seal layer (D) is 50 to 80% by weight, preferably 70 to 80% by weight. By setting the styrene content to 50% by weight or more, it is possible to reduce the peeling electrification voltage when the cover film is peeled from the carrier tape, and, for example, the absolute value of the peeling electrification voltage can be set to 70V or less. In addition, when the styrene content is 80% by weight or less, the frictional electrification voltage with the electronic component can be suppressed low, and since the absolute value of the frictional electrification voltage can be set to 70V or less, for example, component adhesion is reduced.

It is preferable that the heat seal layer (D) contains the conductive fine particles described above in the release layer (C). As a method of containing conductive fine particles in the heat seal layer (D), a method of mixing the resin forming the heat seal layer (D) and conductive fine particles in advance in a Henschel mixer, then melt-kneading at the time of extrusion and laminating with the release layer (C). , After mixing the conductive fine particles and the resin forming the emulsified heat seal layer (D) in water or an organic solvent medium, a method of coating the surface of the release layer (C) by a roll coater or spray may be employed.

The content of the conductive fine particles in the heat seal layer (D) ^{is not limited if the surface resistivity of the heat seal layer (D) is 10 to 10 12} Ω/□, preferably 10 ⁶ to 10 ¹² Ω/□, but the heat seal layer (D) It is preferably 100 to 700 parts by weight, more preferably 200 to 600 parts by weight, based on 100 parts by weight of the thermoplastic resin to form. When the amount of the conductive fine particles added is 100 parts by weight or more, good conductivity is exhibited. Moreover, by setting it as 700 parts by weight or less, aggregation of conductive fine particles in the heat seal layer (D) can be reduced.

The thickness of the heat seal layer (D) is preferably 0.1 to 5 µm, more preferably 0.1 to 3 µm, and most preferably 0.1 to 0.5 µm. When the thickness of the heat seal layer (D) is 0.1 µm or more, good peel strength of the heat seal layer (D) can be obtained. Further, by setting the thickness of the heat seal layer (D) to 5 µm or less, not only it is possible to suppress an increase in cost, but also the difference in peel strength when peeling the cover film can be reduced.

<Production of cover film>

The method of manufacturing the cover film is not particularly limited, and a general method may be used. For example, by extruding the resin composition containing m-LLDPE constituting the intermediate layer (B) as a main component and the resin composition constituting the release layer (C) from a separate single screw extruder and laminating them with a multi-manifold die, the intermediate layer ( It is formed by a two-layer film consisting of B) and a release layer (C). Further, a biaxially stretched polyester film and a two-layer film coated with an anchor coat agent such as polyurethane, polyester, or polyolefin on the surface of the base layer (A) were laminated by a dry lamination method, and the base layer, the intermediate layer, and the like were laminated. It is set as a three-layer film composed of a peeling layer. In addition, by applying the resin composition constituting the heat seal layer (D) on the surface of the release layer (C) by, for example, a gravure coater, a reverse coater, a kiss coater, an air knife coater, a Mayer bar coater, a dip coater, etc. A cover film to be used can be obtained.

As another method, the release layer (C) is previously formed by a method such as a T die-casting method or an inflation method, and an anchor coat of polyurethane, polyester, polyolefin, polyethyleneimine, etc., on the surface of the base layer (A). By a sand lamination method in which a resin composition mainly composed of a biaxially-stretched polyester film coated with an agent and m-LLDPE as an intermediate layer (B) as an intermediate layer (B) is extruded from a T-die, the base layer ( A), an intermediate layer (B), and a three-layer film composed of a release layer (C). In addition, by applying the resin composition constituting the heat seal layer (D) to the surface of the release layer (C) by, for example, a gravure coater, a reverse coater, a kiss coater, an air knife coater, a Mayer bar coater, a dip coater, etc. It is possible to obtain a cover film.

In addition, as another method, the resin composition containing m-LLDPE constituting the intermediate layer (B) as a main component and the resin composition constituting the release layer (C) are extruded from a separate single screw extruder, and laminated with a multi-manifold die, thereby forming the intermediate layer. It is set as a double film consisting of a part of (B) and a peeling layer (C). In addition, between the biaxially stretched polyester film and the double film coated with an anchor coat agent such as polyurethane, polyester, polyolefin, polyethyleneimine, etc. on the surface of the base layer (A), which becomes a part of the intermediate layer (B). A three-layer film composed of a base layer (A), an intermediate layer (B), and a release layer (C) is obtained by a sand lamination method in which a resin composition containing m-LLDPE as a main component is extruded from a T-die. In addition, by applying the resin composition constituting the heat seal layer (D) to the surface of the release layer (C) by, for example, a gravure coater, a reverse coater, a kiss coater, an air knife coater, a Mayer bar coater, a dip coater, etc. It is possible to obtain a cover film. In this method, the intermediate layer (B) has a two-layer structure of a layer formed by coextrusion with the release layer (C) and a layer formed by sand lamination. The thickness of the layer formed by the sand lamination is usually in the range of 10 to 20 μm. In this way, a film having a total thickness of 45 to 65 µm is obtained. When the total thickness is thinner than this, fracture resistance decreases, and when it becomes thicker than this, the difference in peel strength tends to increase.

<Carrier tape>

The cover film is used as a cover material for a carrier tape that is a storage container for electronic components. The carrier tape is an object of about 8mm to 100mm in width having pockets for storing electronic parts. In the case of heat sealing the cover film as a cover material, in general, the material constituting the carrier tape is not particularly limited, and a commercially available material may be used. For example, polystyrene, polyester, polycarbonate, polyvinyl chloride, etc. may be used. I can. However, in the case of the present embodiment in which an acrylic resin is used for the heat seal layer (D) of the cover film, a carrier tape made of polystyrene or polycarbonate is suitably combined. In the carrier tape, carbon black or carbon nanotubes are mixed in a resin to give conductivity, an antistatic agent or a conductive filler is mixed, or a surfactant-type antistatic agent, a conductive material such as polypyrrole or polythiophene is added to acrylic, etc. An antistatic property may be imparted by applying a coating liquid dispersed in the organic binder of the above to the surface.

<Electronic parts package>

In the package containing the electronic component, for example, after the electronic component is stored in the electronic component storage unit of the carrier tape, the cover film is used as a cover material, and both edges in the longitudinal direction of the cover film are continuously It is packed by heat sealing and is obtained by winding it on a reel. By packaging in this form, electronic components and the like are stored and transported. Packages containing electronic components, etc., are transported using holes called sprocket holes for carrier tape transport provided at the edge of the carrier tape in the longitudinal direction, and the cover film is intermittently peeled off, and the presence and orientation of electronic components, etc. by the component mounting device. , Is taken out while the position is confirmed, and, for example, the substrate is mounted.

Here, when the cover film is peeled off, if the peeling strength is low, it may be peeled off from the carrier tape and the storage part may fall off, and if it is too large, it becomes difficult to peel from the carrier tape and breaks when peeling the cover film. There are cases. Therefore, when heat-sealing at 120 to 220°C, it has a peel strength of 0.05 to 1.0 N. In addition, for ``range width,'' which means the difference between the maximum and minimum values of the peel strength when peeling the cover film, when the range width is large, the carrier tape vibrates violently and the electronic parts protrude, causing a failure in mounting. Because there is, it is preferable that the range width is less than 0.4N.

Example

Hereinafter, the present invention will be described in detail by examples, but the present invention is not limited thereto. In Examples and Comparative Examples, the following resin raw materials were used for the base layer (A), the intermediate layer (B), the release layer (C), and the heat seal layer (D).

Base layer (A):

Biaxially stretched polyethylene terephthalate film (made by Futamura Chemical Co., Ltd., "FB2001"), thickness 13㎛

Middle layer (B):

(b-1) m-LLDPE (manufactured by Japan Polyethylene Corporation, Harmorex (registered trademark, "NH745N")

(b-2) m-LLDPE (manufactured by Ube Maruzen Polyethylene, Umerit (registered trademark) "2040F")

Release layer (C):

(c-a-1) Styrene-butadiene block copolymer (manufactured by Denki Chemical Industries, Ltd., clearene "170 ZR"), non-cut softening temperature: 76°C, styrene ratio 83% by weight

(c-a-2) Styrene-butadiene block copolymer (manufactured by JSR, "TR-2000") Non-cut softening temperature of 45°C, styrene ratio of 40% by weight

(c-b-1) Ethylene-α-olefin random copolymer (manufactured by Japan Polyethylene Corporation, Kernel (registered trademark) "KF270T"), non-cut softening temperature of 88°C

(c-b-2) Ethylene-α-olefin random copolymer (manufactured by Japan Polyethylene Corporation, Kernel (registered trademark) "KF360T"), non-cut softening temperature of 72°C

(c-b-3) Ethylene-α-olefin random copolymer (manufactured by Mitsui Chemicals, Tafma (registered trademark) “A”), non-cut softening temperature of 55°C

(c-b-4) Ethylene-α-olefin random copolymer (manufactured by Japan Polyethylene, Kernel (registered trademark) “KS240T”), non-cut softening temperature of 44°C

(c-b-5) Ethylene-α-olefin random copolymer (manufactured by Japan Polyethylene Corporation, Kernel (registered trademark) "KF283"), non-cut softening temperature of 102°C

(c-c-1) High-impact polystyrene (manufactured by Dongyang Styrene, Toyo Styrol "E640N") Non-cut softening temperature of 99°C

Heat Seal Layer (D):

(d-1) Acrylic resin (manufactured by Shin-Nakamura Chemical Co., Ltd., NK polymer "EC-24"), an emulsion having a solid content concentration of 35%.

(d-2) Styrene-acrylic copolymer (manufactured by Shin-Nakamura Chemical Co., Ltd., NK polymer "ECS-704"), an emulsion having a styrene content of 40% by weight and a solid content concentration of 35%.

(d-3) Styrene-acrylic copolymer (manufactured by Shin-Nakamura Chemical Co., Ltd., NK polymer "ECS-705"), an emulsion having a styrene content of 50% by weight and a solid content concentration of 35%.

(d-4) Styrene-acrylic copolymer (manufactured by Shin-Nakamura Chemical Industries, Ltd., NK polymer "ECS-706"), an emulsion having a styrene content of 60% by weight and a solid content concentration of 35%.

(d-5) Styrene-acrylic copolymer (manufactured by Shin-Nakamura Chemical Co., Ltd., NK polymer "ECS-707"), an emulsion having a styrene content of 70% by weight and a solid content concentration of 35%.

(d-6) Styrene-acrylic copolymer (manufactured by Shin-Nakamura Chemical Industries, Ltd., NK polymer "ECS-708"), an emulsion having a styrene content of 80% by weight and a solid content concentration of 35%.

(d-7) An emulsion having a styrene-acrylic copolymer (manufactured by Shin-Nakamura Chemical Co., Ltd., NK polymer "ECS-709"), a styrene content of 90% by weight and a solid content concentration of 35%.

(d-8), spherical antimony-doped tin oxide (conductive fine particles), (manufactured by Ishihara Industries, "SN-100D"), number average particle diameter of 110 nm, aqueous dispersion slurry.

(Example 1)

(ca-1) 52.5 parts by weight of a styrene-butadiene block copolymer, (ca-2) 12.5 parts by weight of a styrene-butadiene block copolymer, and (cb-1) 35 parts by weight of an ethylene-α-olefin random copolymer It was pre-blended using, and kneaded and extruded at 210°C using a single screw extruder having a diameter of 40 mm to obtain a resin composition for a release layer. This resin composition and (b-2) m-LLDPE constituting the intermediate layer 2 of Tables 1 and 2 were extruded from another single screw extruder, and laminated and extruded using a multi-manifold T-die extruder at 225°C to peel off. A two-layer film having a layer thickness of 5 µm and an intermediate layer 2 having a thickness of 20 µm was obtained.

On the other hand, a two-component curing polyurethane-type anchor coat agent is applied to the biaxially stretched polyethylene terephthalate film FE2001 (thickness 13 μm) constituting the base layer using a roll coater, and the intermediate layer between the coated surface and the two-layer film described above. Between the film faces of (2), the molten (b-1) m-LLDPE constituting the intermediate layer (1) was extruded at 330°C to a thickness of 13 μm to obtain a laminated film according to the sand lamination method.

After corona discharge treatment was performed on the surface of the release layer of this laminated film, (d-3) 100 parts by weight of a styrene-acrylic copolymer and (d-8) 400 parts by weight of spherical antimony-doped tin oxide, prepared in advance as a heat seal layer, A 30% solid content aqueous dispersion was applied using a gravure coater and a solid content thickness of 0.5 μm was applied, and the layer structure of the base layer (A) / intermediate layer (B) / peeling layer (C) / heat seal layer (D). A cover film was obtained. The properties of this cover film are shown in Tables 1 and 2.

(Examples 2 to 9, Comparative Examples 1 to 8)

A cover film was produced in the same manner as in Example 1, except that the release layer (C) and the heat seal layer (D) were formed using raw materials such as resins shown in Tables 1 and 2.

(Comparative Example 9)

A cover film was prepared in the same manner as in Example 1 with the mixing ratio and configuration shown in Table 2, except that the release layer (C) was not provided and the heat seal layer (D) was formed using raw materials such as resins listed in Table 2. did.

(Comparative Example 10)

A cover film was produced in the same manner as in Example 1, except that the intermediate layer (B) was not provided and the release layer (C) and the heat seal layer (D) were sequentially formed on the base layer (A) having a thickness of 25 μm.

(Comparative Example 11)

A cover film was produced in the same manner as in Example 1, except that the heat seal layer (D) was not provided, and the intermediate layer (B) and the release layer (C) were formed using raw materials such as resins shown in Table 2.

<Evaluation method>

The following evaluation was performed about the cover film for carrier tapes of electronic parts produced by each Example and each comparative example. These results are also put together in Table 1 and Table 2, respectively, and are shown.

(Non-cut softening temperature)

The resin composition for forming the release layer was extruded at 210°C using a single screw extruder having a diameter of 40 mm to obtain pellets of the resin composition. The obtained pellet was press-molded at 210°C to obtain a test piece having a thickness of 5 mm, a width of 10 mm, and a length of 100 mm. According to the A120 method of JIS K-7206, the test piece was heated at a load of 10N and 120°C/hour to measure the non-cut softening temperature.

(Haze value)

According to the measurement method A of JIS K7105: 1998, the haze value was measured using an integrating sphere type measuring apparatus.

(Range width of peeling strength)

Using a taping machine (Shibuya Industrial Co., Ltd., ETM-480), seal head width 0.5 mm × 2, seal head length 32 mm, seal pressure 0.1 MPa, transmission length 4 mm, sealing time 0.1 seconds × 8 times, sealing iron temperature at 130°C to 190 Heat sealing was performed on a cover film with a width of 5.5 mm at intervals of 20° C. to° C. so that the peel strength of a polystyrene carrier tape (manufactured by Denki Chemical Industries, Ltd.) of 8 mm was 0.4 N. After leaving for 24 hours in an atmosphere of a temperature of 23°C and 50% relative humidity, the cover film was peeled at a rate of 300 mm per minute and a peeling angle of 170 to 180° under the same atmosphere of 23°C and 50% of relative humidity. From the chart obtained when peeling the cover film for 100 mm in the peeling direction, the difference (range width) between the maximum value and the minimum value of peeling strength was measured. The peel strength range width of 0.2N or less was referred to as "right", the one exceeding 0.2 and 0.4N or less was referred to as "positive", and the one exceeding 0.4N was referred to as "defective".

(Friction high voltage)

Heat sealing was performed so that the peel strength of the polycarbonate carrier tape (manufactured by Denki Chemical Industries, Ltd.) in advance with the built-in LED was in the range of 0.4±0.05 N. The sealed package was loaded on a cute mixer (CM-1000) and subjected to elliptical vibration for 30 minutes at 1000 rpm to cause frictional charging between the LED (PG1111C manufactured by Stanley) and the cover film. The package body was placed on the metal plate with the cover film side down, the carrier tape was peeled off, and the LED was exposed. The LED was adhered to a conductive double-sided adhesive tape and fixed to a metal platen so that the cover film contact surface was upward. Using an electrometer (MONROE ELECTRONICS ISOPROBE ELECTROSTATICVOLTMETER MODEL 279) and a measurement terminal (1034 EH type), the high voltage of the fixed LED was measured at an ambient temperature of 23°C and an ambient humidity of 50% RH. Here, the distance from the LED to the potential probe was 0.5 mm, and the spatial resolution of the potential probe was Φ 1.5 mm. Five LEDs were measured, and among the obtained results, the maximum absolute value was taken as the frictional electrification voltage in this measurement. When the value of the frictional voltage was within ±50V, it was expressed as "right", the value exceeding ±50V and within ±70V was expressed as "positive", and the value exceeding ±70V was expressed as "defective".

(Peeling large voltage)

Heat sealing was performed so that the peel strength of the polycarbonate carrier tape (manufactured by Denki Chemical Industries) was in the range of 0.4±0.05N. The cover film was peeled off, and the electrometer and the measurement terminal described above were used at an ambient temperature of 23°C and an ambient humidity of 50% RH, and the high voltage of the cover film and the heat seal layer (D) was applied to 8 mm in the width direction and 30 mm in the length direction, respectively. Measurement was performed at 0.5 mm intervals. At this time, the distance from the cover film peeling position to the dislocation probe was 0.5 mm, and the spatial resolution of the dislocation probe was set to Φ 1.5 mm. Among the obtained results, the maximum value of the absolute value was taken as the peeling electrification voltage in this measurement. The value of the peeling electrification voltage within ±50V was expressed as "right", the one exceeding ±50V and within ±70V was expressed as "positive", and the one exceeding ±70V was expressed as "defective". It is shown in the column of peeling charging in Table 1 and Table 2.

(Surface resistivity)

Using a resistivity meter (manufactured by Mitsubishi Chemical Corporation, "Hyresta UP MCP-HT450"), by the method of JIS K6911, the surface resistance value of the surface of the heat seal layer was measured at an atmosphere temperature of 23°C, an atmosphere humidity of 50%RH, and an applied voltage of 10V. did.

Note: The number following ``E'' represents the decimal point (e.g. 1.00E+07 is 1.00×10 to the 7th power)

Note: The number following ``E'' represents the decimal point (e.g. 1.00E+07 is 1.00×10 to the 7th power)

1 cover film
2 base layer
3 middle floor
4 peeling layer
5 Heat seal layer

Claims (9)

As a cover film in which a base layer (A), an intermediate layer (B), a release layer (C), and a heat seal layer (D) are arranged in this order,
The release layer (C) is a resin comprising 50 to 80% by weight of one or more copolymers selected from styrene-diene block copolymers and styrene-diene graft copolymers, and 50 to 20% by weight of an ethylene-α-olefin copolymer While containing the composition, has a non-cut softening temperature of 55 ~ 80 ℃,
The heat seal layer (D) is a cover film containing a styrene-(meth)acrylate copolymer having a styrene content of 50 to 80% by weight. The method according to claim 1,
A cover film in which at least one layer of the release layer (C) or the heat seal layer (D) contains conductive fine particles. The method according to claim 2,
A cover film in which the conductive fine particles are fibrous or spherical. The method according to any one of claims 1 to 3,
Cover film with a thickness of the base layer (A) of 12 to 20 μm, a thickness of the intermediate layer (B) of 10 to 40 μm, a thickness of the release layer (C) of 5 to 20 μm, and a total thickness of 45 to 65 μm . The method according to any one of claims 1 to 3,
A cover film having a haze value of 30% or less of the cover film. An electronic component package using the cover film according to any one of claims 1 to 3 as a cover material for a carrier tape made of a thermoplastic resin. The method of claim 6,
Electronic component packaging body in which the thermoplastic resin is polycarbonate. The method of claim 6,
An electronic component package in which the absolute value of the peeling electrification voltage when peeling the cover film from the carrier tape is 70 V or less. The method of claim 6,
An electronic component package whose absolute value of the frictional electrification voltage generated between the cover film and the carrier tape is 70V or less.

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