JP2010047262A - Cover tape for electronic component packaging - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cover tape for electronic component packaging, which is reduced in cost by reducing the use of an expensive conductive material and is clean by preventing fall of the conductive material. <P>SOLUTION: The cover tape for electronic component packaging is composed of three layers, which are a base material layer, an intermediate layer, and a sealant layer. In this cover tape, the base material layer has at least one layer of biaxial oriented film. The sealant layer is formed on the intermediate layer by sequentially or simultaneously applying and drying a coating liquid in which a carbon nano fiber material containing a ferromagnetic substance, particles of conductive substance, and a solvent are disposed in thermoplastic resin, or a coating liquid in which a carbon nano fiber material containing a ferromagnetic substance and a solvent are dispersed in thermoplastic resin, and a coating liquid in which particles of conductive substance and a solvent are dispersed in thermoplastic resin. In the sealant layer, the carbon nano fiber material and the particles of conductive material have contacts. The carbon nano fiber material and the particles of conductive substance are formed in two layers, having a density inclination in the direction of the thickness, or they have an inclination function. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plastic carrier in which a storage pocket is formed out of a package having functions of protecting electronic components from contamination and arranging and taking them out for mounting on an electronic circuit board when storing, transporting, and mounting the electronic components. The present invention relates to a cover tape for packaging electronic parts that is heat-sealed to the tape.

  In recent years, for storing and transporting surface mount parts such as various electronic parts and precision equipment parts, carrier tape with embossed parts according to the shape of each part, and preventing parts from falling off after storing the parts in this embossed part For protection, a cover tape sealed with a heat seal or an adhesive is used as a lid material (see Patent Document 1). The cover tape is peeled off at the time of mounting, and the components are taken out and attached to the board.

The cover tape currently on the market is composed of an adhesive for bonding to the base material, the intermediate layer and the carrier tape. The antistatic agent or the conductive agent is applied, or the antistatic agent and the conductive agent are kneaded into the base material and the adhesive.
In addition, in order to impart conductivity to the cover tape as described above, a method of dispersing conductive powder in a sealant resin has been taken.

  However, in the case of carbon black, which is frequently used for conductive particles, an addition amount of a certain amount or more is necessary to obtain sufficient conductivity even when uniformly dispersed, which is also a cause of hindering transparency. . In Patent Document 1, a conductive fine powder made of any one of tin oxide, zinc oxide, titanium oxide, or a combination thereof is used, but the transparency is not always satisfactory. In recent years, nanotechnology has enabled mass production of carbon nanomaterials. In order to obtain transparency for confirming parts after taping, carbon nanomaterials can be used as conductive substances (conducting polymers (π-electron conjugated conductive materials)). It has also been proposed to be used together with molecules) (see Patent Document 2).

  Moreover, the cover tape which consists of these electroconductive particles has the problem that the contact point between electroconductive particles reduces by producing a fine crack at the time of peeling from a carrier tape, and the antistatic function after peeling falls.

  Furthermore, it has also been proposed to use carbon nanomaterials such as fullerene, carbon nanofiber and carbon nanotube as conductive particles, and apply or knead into a resin as a dispersion (see Patent Document 3). However, carbon nanomaterials are expensive because they are very expensive, and there are problems that the blended conductive fibers fall off the sealant layer and contaminate the semiconductor package and the electronic components inside the package.

Japanese Patent Publication No. 7-067774 Japanese Patent Laying-Open No. 2005-081766 JP 2007-45513 A

  The present invention is a cover tape for sealing the upper surface of a carrier tape in which a plurality of recesses for storing electronic components are continuously provided, and has good transparency and excellent visibility of components as contents. In addition to being able to process and exhibiting sufficient antistatic performance without causing a decrease in conductivity even after peeling from the carrier tape, the amount of expensive materials used has been reduced and the cost has been reduced. It is another object of the present invention to provide a clean cover tape for packaging electronic parts in which conductive fibers are hardly dropped off.

The present invention is as follows.
(1) In a cover tape having a three-layer structure of a base material layer, an intermediate layer, and a sealant layer, the base material layer has at least one biaxially stretched film, and the sealant layer is a polyolefin resin or a polystyrene resin. Polyester resin, polyurethane, acrylic, vinyl chloride-vinyl acetate copolymer, ethylene-acrylic acid copolymer, at least one thermoplastic resin selected from the group of ethylene-vinyl acetate copolymer, ferromagnetic A carbon nanofiber material containing a body and a coating liquid in which a particulate conductive substance and a solvent are dispersed are applied and dried, or a coating liquid in which a carbon nanofiber material containing a ferromagnetic substance and a solvent are dispersed in the thermoplastic resin. And a coating liquid in which a particulate conductive material and a solvent are dispersed in the thermoplastic resin, and each coating liquid is applied and dried in order or simultaneously to form on the intermediate layer. In the sealant layer, the carbon nanofiber material and the particulate conductive material have a contact point, and the carbon nanofiber material and the particulate conductive material are made into a two-layered or gradient functionalized with a concentration gradient in the thickness direction. A cover tape for packaging electronic parts.
(2) The electronic component packaging cover tape according to (1), wherein an electric field or a magnetic field is used as a method of providing a concentration gradient of the carbon nanofiber material and the particulate conductive material.
(3) The concentration gradient of the carbon nanofiber material and the particulate conductive material is such that the concentration of the carbon nanofiber material and the particulate conductive material in the upper layer when the sealant layer is divided into two upper and lower layers in the thickness direction is A1% by weight, A1 / A2 or A2 / A1 is 1.5 or more when B1% by weight, and the concentrations of the carbon nanofiber material and the particulate conductive material in the lower layer are A2% by weight and B2% by weight, respectively, and B1 / The cover tape for packaging electronic parts according to (1) or (2), wherein B2 or B2 / B1 is 1.5 or more.

  In the present invention, the concentration of the carbon nanofiber material and the particulate conductive material in the sealant layer is made to have a concentration gradient in the thickness direction to form a double layer or a gradient function, thereby reducing the amount of material used and reducing the cost. Make it possible. Moreover, the effect which prevents the electroconductive fall after peeling is acquired, and also the preparation of the clean cover tape with almost no omission of a conductive fiber is attained.

The base layer of the cover tape is selected from polyester, polypropylene, polyethylene, and nylon, and is preferably a biaxially stretched film, but has a three-layer structure with polyester / polyethylene / polyester or polyester such as polyester / polyester. It is also possible to use a laminated body. As the polyester / polyester laminate, in addition to polyethylene terephthalate / polybutylene terephthalate, a two-layer structure made of the same material such as polyethylene terephthalate / polyethylene terephthalate may be used. In this case, the strength of the laminate can be improved by using polyethylene terephthalate stretched in the longitudinal direction and one stretched in the width direction. The thickness of the base material layer is 9 μm to 50 μm, preferably 12 to 25 μm. If it is less than the lower limit, the strength of the laminated plastic film is insufficient, and if it exceeds the upper limit, thermal bonding becomes difficult.
An intermediate layer is formed on the cover tape. Examples of the intermediate layer include polyethylene, polyethylene-vinyl acetate copolymer, ethylene-acrylic copolymer, and polyurethane. The thickness is preferably 10 to 50 μm, and when it is less than 10 μm, the tear strength is inferior, and when it exceeds 50 μm. Problems arise in adhesion.

As a processing method of the base material + intermediate layer, either dry lamination or extrusion lamination may be used. Preferably, extrusion lamination is suitable because the flexibility of the base material is obtained.
The sealant layer of the cover tape is formed on the substrate via an intermediate layer. The sealant layer is formed by dispersing a conductive substance in a thermoplastic resin. The thermoplastic resin constituting the sealant layer includes polyolefin resin, polystyrene resin, polyester resin, polyurethane, acrylic, vinyl chloride-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer. There may be mentioned at least one thermoplastic resin selected from the group of coalescence. Here, the polyolefin resin includes polyethylene, polypropylene, ethylene α-olefin copolymer, and the like. The polystyrene resin includes styrene, styrene / butadiene / styrene block copolymer (SBS), styrene / ethylene / butylene.・ Styrene block copolymer (SEBS), styrene / isoprene / styrene block copolymer (SIS), styrene / ethylene / propylene / styrene block copolymer (SEPS), hydrogenated styrene / butadiene random copolymer (HSBR) And the like, and the polyester-based resin includes polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and the like.

In order to form the sealant layer on the intermediate layer, a carbon nanofiber material containing a thermoplastic resin and a ferromagnetic material as a conductive material, and a coating liquid in which a particulate conductive material and a solvent are dispersed are applied to the carbon nanofiber. The material and the particulate conductive material are provided with a concentration gradient in the thickness direction to form a two-layer or gradient function. The state of the conductive material in the double-layered or gradient-functionalized sealant layer has a schematic structure as shown in FIGS. 1 to 5, for example, and is effective in any case. In FIG. 1, the particulate conductive material and the carbon nanofiber material are in contact near the center of the film. In FIG. 2, the particulate conductive material and the carbon nanofiber material are in contact at many contact points while overlapping in the vicinity of the center of the film. FIG. 3 shows a case where the particle size of the particulate conductive material and the carbon nanofiber material is larger than the film thickness, and each is composed of a single layer or several thin layers. FIG. 4 shows a case where the particulate conductive material is concentrated to a thin film interface at the membrane interface, and the carbon nanofiber material contacts from the opposite side. FIG. 5 shows a case where the carbon nanofiber material is concentrated to a thin film thickness at the membrane interface, and the particulate conductive material contacts from the opposite side. In particular, when the intermediate layer is laminated on the side on which the carbon nanofiber material is concentrated, the carbon nanofiber material can be prevented from falling off and protruding from the surface of the sealant layer, and contamination of the package can be prevented. The intermediate layer may be at the upper or lower interface in the schematic diagram.
In the present invention, in the sealant layer, it is necessary that the carbon nanofiber material and the particulate conductive material have a two-layered or gradient function with a concentration gradient. The concentration gradient of the carbon nanofiber material and the particulate conductive material is such that the concentration of the carbon nanofiber material and the particulate conductive material in the upper layer when the sealant layer is divided into two upper and lower layers in the thickness direction is A1 wt% and B1 wt%, respectively. When the concentration of the carbon nanofiber material and the particulate conductive material in the lower layer is A2 wt% and B2 wt%, respectively, A1 / A2 or A2 / A1 is 1.5 or more, and B1 / B2 or B2 / B1 is preferably 1.5 or more.
In addition, it is necessary for the carbon nanofiber material containing the ferromagnetic material and the particulate conductive material to contact in the layer, and there is no contact between the particulate conductive material and the carbon nanofiber material as shown in FIG. In the case of two layers, the antistatic function is not easily exhibited and is not suitable.

The two-layered or gradient functionalization is a coating liquid in which a carbon nanofiber material containing a ferromagnetic material and a solvent are dispersed in a thermoplastic resin, and a coating liquid in which a particulate conductive material and a solvent are dispersed in a thermoplastic resin. Prepare each coating solution in order or at the same time, or apply a coating solution in which a carbon nanofiber material containing a ferromagnetic material and a particulate conductive material and a solvent are dispersed in a thermoplastic resin, and then apply an electric or magnetic field. A method of concentrating the ferromagnetic material in the upper layer or the lower layer using the above may be used. In that case, it is desirable to use a DC current having a voltage of 1 to 20 V and an electric field of 1 V / cm or more, or an AC current having a voltage of 1 to 200 V and a frequency of 0.1 Hz to 10 MHz, and a magnetic field of 0.1 to 30 T neodymium magnet. It is desirable to use permanent magnets such as ferrite magnets, alnico magnets, and samarium cobalt magnets, electromagnets, and superconducting magnets. The electric field or magnetic field may be applied from either the surface side or the base material side of the sealant layer, or may be applied from both sides. When an electric field is used, both the particulate conductive material and the carbon nanofiber material may move. However, when a magnetic field is used, only the carbon nanofiber material, which contains a ferromagnetic material, is used as a magnetic field line. It moves along and concentrates on the one with the magnet.

The amount of the conductive material constituting the sealant layer is preferably such that the carbon nanofiber material is added in an amount of 0.1 to 30 parts by weight with respect to 100 parts by weight of the thermoplastic resin. It is preferable to add 0.01 to 300 parts by weight with respect to 100 parts by weight of the plastic resin. In each case, if it is less than the lower limit value, the surface resistance value exceeds 10 ¹⁰ ohms, and sufficient conductivity cannot be obtained. If the upper limit is exceeded, the haze will exceed 20%.
The haze of the cover tape is preferably 20% or less. The haze (cloudiness value) is defined by (scattered light transmittance / total light transmittance) × 100.

  As the conductive material constituting the sealant layer, a carbon nanofiber material containing a ferromagnetic material and a particulate conductive material are used. Examples of the particulate conductive material include tin oxide, zinc oxide, titanium oxide, carbon black, metal-coated particles, Si-based organic compounds, and fullerene. These particulate conductive materials may be used alone or in combination. The particle size of the particulate conductive material is preferably 5 to 2000 nm. When the thickness is less than 5 nm, it is difficult to produce a dispersion liquid of the particulate conductive material, and the resistance value of the transparent conductive film obtained is increased. If it exceeds 2000 nm, the particulate conductive material dispersion liquid tends to settle and handling becomes difficult, and at the same time, it becomes difficult to simultaneously achieve the transmittance and the resistance value.

  The carbon nanofiber material containing a ferromagnetic material used in the present invention will be described. The term “ferromagnetic material” as used herein refers to a residual catalyst used when synthesizing the carbon nanofiber material, a material obtained by coating the surface of the carbon nanofiber material by electroless plating, or a combination thereof. Ferromagnetic materials include rare earth elements such as neodymium (Nd), samarium (Sm), and gadolinium (Ga) in addition to iron (Fe), nickel (Ni), and cobalt (Co), and compounds and alloys containing these. . The content of the ferromagnetic material is desirably 0.1 to 50 parts by weight with respect to 100 parts by weight of the carbon nanofiber material. If it is less than the lower limit, the movement of fibers due to an electric field or a magnetic field is less likely to occur. When the upper limit is exceeded, the conductivity is lowered and a sufficient function cannot be obtained.

  The carbon nanofiber materials are called carbon nanotubes (CNT) or carbon nanofibers (CNF) depending on their diameters and forms, but the present invention recognizes that they are included as one form of carbon nanofiber materials. In general, carbon nanotubes are known that exhibit metallic properties due to their chirality, and those that exhibit semiconducting properties, but it is more desirable that the content of metallic carbon nanotubes exhibiting good conductivity is large. . The method for producing the carbon nanofiber material is not particularly limited, but a vapor phase growth method, an arc discharge method, a laser evaporation method, an electron beam irradiation method in which a hydrocarbon is used as a raw material, thermally decomposed in a gas phase, and fibers are grown from catalyst particles. In addition to the melt spinning method, a substrate method in which fibers are grown on a substrate, a super-growth method, and the like can be given. The carbon nanofiber material has many entanglements and is difficult to disperse because of its large specific surface area and large cohesive force. For this reason, it has a feature that a network can be formed with a small amount. The carbon nanofiber material preferably has an outer diameter of 10 to 200 nm and an aspect ratio of 20 to 50000.

  As described above, in the cover tape containing only the conventional particulate conductive material, the conductivity decreased after peeling from the carrier tape. The cover tape according to the present invention has a structure in which the carbon nanofiber material and the particulate conductive material are made into a two-layered or functionalized gradient, and not only exhibits sufficient conductivity for preventing static electricity before peeling, but also due to cracks after peeling. Even if the contact between the particulate conductive materials decreases, the contact between the particulate conductive material and the carbon nanofiber material, and the contact between the carbon nanofiber material and the carbon nanofiber material is not interrupted. be able to.

  Examples and Comparative Examples of the present invention are shown below, but the present invention is not limited to these Examples. It has been confirmed that the CNTs used in the examples are attracted by magnetic force.

<Example 1>
PET (polyethylene terephthalate) was formed as a base material layer, and LDPE (low density polyethylene) was laminated as an intermediate layer on one side of the layer. Thereafter, the conductive material dispersion coating solution of Formulation 1 (see Table 1 for the formulation) is applied to a thickness of 1 μm after drying, and the carbon nanofiber material is coated on the surface of the coating layer using a 0.4 T neodymium magnet. Concentration was performed. The obtained coating film was dried to obtain a cover tape prototype. The obtained cover tape was slit to a width of 5.5 mm, and then heat-sealed with a carrier tape made of PVC having a width of 8 mm. When the cross section of the sealant layer of the cover tape was observed, it was a structure close to FIG.

<Example 2>
PET (polyethylene terephthalate) was formed as a base material layer, and LDPE (low density polyethylene) was laminated as an intermediate layer on one side of the layer. A dispersion coating solution of the conductive material of Formulation 1 was applied to the intermediate layer so as to have a thickness of 0.5 μm after drying, and a dispersion coating solution of Formulation 2 was applied thereon so as to have a thickness of 0.5 μm after drying. The obtained coating film was dried to obtain a cover tape prototype. Heat sealing was performed in the same manner as in Example 1. When the cross section of the sealant layer of the cover tape was observed, it was a structure close to FIG.

<Comparative Example 1>
PET (polyethylene terephthalate) was formed as a base material layer, and LDPE (low density polyethylene) was laminated as an intermediate layer on one side of the layer. A conductive material dispersion coating solution of Formulation 2 was applied to the intermediate layer so as to have a thickness of 1 μm after drying. The obtained coating film was dried to obtain a cover tape prototype. Heat sealing was performed in the same manner as in Example 1.

The surface resistance value of the sealant layer before peeling of the cover tape prepared by the above method and after peeling at 300 mm / min was measured. Moreover, the total light transmittance and haze of the cover tape prototype were measured. The characteristic evaluation results are shown in Table 2. The surface resistance value was measured according to JIS K6911, and the total light transmittance and haze were measured according to JIS K7105.

The symbols in Table 1 and Table 2 are as follows.
PET: Polyethylene terephthalate LDPE: Low-density polyethylene PMMA-BMA: Polymethacrylate-butyl methacrylate copolymer (molecular weight 4,000 to 12,000)
ATO: antimony-containing tin oxide (average particle size 50 nm)
CNT: carbon nanotube (diameter 30 nm, fiber length 2 μm, manufactured by Gemco)

The schematic diagram of the cross section of one Example of the sealant layer of the cover tape of this invention A circular thing is a particulate conductive material, and a thread-like thing is a carbon nanofiber material. The schematic diagram of the cross section of one Example of the sealant layer of the cover tape of this invention The schematic diagram of the cross section of one Example of the sealant layer of the cover tape of this invention The schematic diagram of the cross section of one Example of the sealant layer of the cover tape of this invention The schematic diagram of the cross section of one Example of the sealant layer of the cover tape of this invention Schematic diagram of a cross section of an example of a sealant layer of a cover tape not suitable for the present invention

Claims (3)

  In a cover tape having a three-layer structure of a base material layer, an intermediate layer, and a sealant layer, the base material layer has at least one biaxially stretched film, and the sealant layer is a polyolefin resin, a polystyrene resin, or a polyester resin. A ferromagnetic material is contained in at least one thermoplastic resin selected from the group consisting of resin, polyurethane, acrylic, vinyl chloride-vinyl acetate copolymer, ethylene-acrylic acid copolymer, and ethylene-vinyl acetate copolymer. A coating liquid in which a carbon nanofiber material and a particulate conductive substance and a solvent are dispersed is applied and dried, or a coating liquid in which a carbon nanofiber material containing a ferromagnetic substance in the thermoplastic resin and a solvent is dispersed, and the above A coating liquid in which a particulate conductive material and a solvent are dispersed in a thermoplastic resin, and each coating liquid is applied or dried in order or simultaneously to form on the intermediate layer. In the sealant layer, the carbon nanofiber material and the particulate conductive material have contact points, and the carbon nanofiber material and the particulate conductive material have a two-layered or gradient function with a concentration gradient in the thickness direction. Cover tape for packaging electronic parts.   2. The cover tape for packaging electronic parts according to claim 1, wherein an electric field or a magnetic field is used as a method of providing a concentration gradient of the carbon nanofiber material and the particulate conductive material.   When the concentration gradient of the carbon nanofiber material and the particulate conductive substance is divided into two upper and lower layers in the thickness direction, the concentration of the carbon nanofiber material and the particulate conductive substance in the upper layer is A1 wt% and B1 wt%, respectively. When the concentration of the carbon nanofiber material and the particulate conductive material in the lower layer is A2 wt% and B2 wt%, respectively, A1 / A2 or A2 / A1 is 1.5 or more, and B1 / B2 or B2 The cover tape for packaging electronic parts according to claim 1 or 2, wherein / B1 is 1.5 or more.

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