Film for cover tape substrates

Abstract

To provide a film for cover tape substrates with no risk of lamination defects that exhibits superior workability.SOLUTION: A film for cover tape substrates has three layers: layer A, layer B and layer C, where layer A contains 5-95 mass% of polyethylene resin and 95-5 mass% of polypropylene resin, layer B is primarily composed of a mixture of high-density polyethylene resin and low-density polyethylene resin, and layer C contains a low-density polyethylene resin with a density of 0.915 g / cm3 or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a film for a cover tape substrate that is suitably used for packaging of electronic devices. [Background technology]

[0002] In order to prevent damage to electronic components such as semiconductor IC chips before they are used, they are enclosed in a container with antistatic properties, which is made of polystyrene or the like and has concave storage pockets formed at equal intervals, called a carrier tape, and a sealant with antistatic properties, called a cover tape, which is heat-sealed to the carrier tape. The electronic component package in which the carrier tape and the cover tape are heat-sealed is stored and transported in a reel-like state. When this electronic component package is assembled to an electronic board, the cover tape is continuously peeled off, and the IC chip inside is taken out and assembled to the board. The cover tape used for such electronic component packages is completed by dry-laminating a film such as polyester on one side of a cover tape base film, and laminating a resin with heat sealability on the other side.

[0003] However, in Prior Patent Document 1, specific examples of films for cover tape substrates include olefin resins such as polyethylene, including low-density polyethylene, linear low-density polyethylene (LLDPE), and branched low-density polyethylene (VLDPE), and ethylene-based copolymers such as ethylene-vinyl acetate copolymer (EVA). However, if these are used as films for cover tape substrates, the resin has a low Young's modulus and the substrate becomes very soft, which may lead to dimensional misalignment when the cover tape substrate film is laminated with polyesters such as polyethylene terephthalate, resulting in lamination defects such as wrinkles. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-142807 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a film for use as a cover tape substrate that is free from the risk of such lamination defects and has good processability. [Means for solving the problem]

[0006] As a result of extensive research into solving the above problems, the present inventors have found that the object can be achieved by the following configuration. (1) The sintered body has three layers, namely, layer A, layer B and layer C. Layer A contains 5 to 95% by mass of polyethylene resin and 95 to 5% by mass of polypropylene resin. Layer B is mainly composed of a mixture of high-density polyethylene resin and low-density polyethylene resin. Layer C has a density of 0.915 g / cm. 3 A cover tape substrate film containing the following low-density polyethylene resin: (2) The film for a cover tape substrate according to (1) above, which has a crystallinity of 70% or less as calculated by the following formula (a): X=100-56.1×(1000×A 1300 ÷t) (a) X··Crystallinity (%) A 1300 ·Wave number 1300cm -1 Absorbance at t Film thickness (μm) (3) The cover tape substrate film according to (1) or (2), wherein the surface centerline average roughness Ra of layer A is 0.05 μm or more and 0.25 μm or less. (4) The cover tape substrate film according to any one of (1) to (3), wherein the Young's modulus of the film is 250 MPa or more and 450 MPa or less in both the longitudinal and transverse directions of the film. Effect of the Invention

[0007] According to the present invention, it is possible to provide a film for a cover tape substrate which is free from the risk of lamination defects and has good processability and handleability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The cover tape substrate film of the present invention is composed of at least three layers, Layer A, Layer B, and Layer C. Layer A is composed of 5 to 95% by mass of polyethylene resin and 95 to 5% by mass of polypropylene resin, Layer B is composed mainly of a mixture of high-density polyethylene resin and low-density polyethylene resin, and Layer C has a density of 0.915 g / cm 3 The present invention is characterized in that the present invention is made of the following low-density polyethylene resin:

[0009] The thickness ratio of layers A, B, and C is not particularly limited as long as it does not affect the Young's modulus of the film. However, if scraps generated during the manufacturing process, such as film formation and edge cutting, are recycled and used, it is preferable that the layer into which the recycled material is added is thick, for example, accounting for 60% or more of the total thickness.

[0010] The polyethylene resin constituting the A layer is preferably a low-density polyethylene, more preferably one with a density of 0.930 g / cm, since if the density is high, the polyethylene resin is scraped off when the A layer surface is scratched, which may cause foreign matter to be mixed into the adherend. 3 The following high pressure low density polyethylenes are used:

[0011] In addition, in layer A, a sea-island structure is formed with the polymer to create unevenness on the surface and form the surface roughness, so a component made of polypropylene is blended as the polypropylene-based resin in layer A. In view of compatibility with the polyethylene-based resin that makes up layer A, a propylene-ethylene random copolymer or a propylene-ethylene block copolymer is preferably used.

[0012] In this way, it is preferable to form a sea-island structure on the surface of layer A to create unevenness and to make the film slippery, and it is preferable that the surface center line average roughness Ra is 0.05 μm or more and 0.25 μm or less, and the polyethylene component is 5 to 95 mass % and the polypropylene component is 95 to 5 mass %, more preferably the polyethylene component is 10 to 80 mass %, the polypropylene component is 90 to 20 mass %, and even more preferably the polyethylene component is 20 to 50 mass % and the polypropylene component is 50 to 80 mass %. If the polyethylene resin constituting layer A exceeds 95 mass %, the films will not slide well against each other, and when laminating the cover tape substrate film with a polyester such as polyethylene terephthalate, lamination defects such as wrinkles are likely to occur, making it difficult to handle the film. Furthermore, if the polypropylene resin constituting layer A exceeds 95% by mass, the Young's modulus of the film may exceed 450 MPa, and the Young's modulus of the film may become too high. As a result, after being heat-sealed to the carrier tape as a cover tape, the cover tape may not peel off smoothly, and the peeling may stop or a large force may be required to peel it off, which is known as zipping peeling, and this may result in surface defects.

[0013] The surface centerline average roughness Ra of the A layer in the present invention is preferably 0.05 μm or more and 0.25 μm or less, more preferably 0.10 μm or more and 0.20 μm or less, but if the surface centerline average roughness Ra is more than 0.25 μm, when laminating with a film such as polyester of another substrate, the surface irregularities are rough, so air may be trapped, and the visibility of the contents may be deteriorated. Also, if the surface centerline average roughness Ra is less than 0.05 μm, the sliding between the films is deteriorated, and when laminating the cover tape substrate film with polyester such as polyethylene terephthalate, lamination failure such as wrinkles may easily occur, making it difficult to handle the film.

[0014] The lamination thickness ratio of the B layer in the present invention is preferably 60% or more with respect to the total thickness, and since the resin of the B layer in the present invention greatly affects the Young's modulus of the film for cover tape substrate of the present invention, the resin blended in the B layer is preferably a mixture of high-density polyethylene resin and low-density polyethylene resin as the main component. Here, the main component refers to 50% by mass or more with respect to the total amount of the resin composition of the B layer. The blending ratio of the mixture is not particularly limited as long as it does not affect the Young's modulus of the film, but is preferably 50% by mass to 90% by mass, more preferably 60% by mass to 80% by mass, and 10% by mass to 50% by mass, more preferably 20% by mass to 40% by mass of the high-density polyethylene resin. When the blending ratio of the high-density polyethylene resin is less than 50% by mass, the Young's modulus of the film may be less than 250 MPa, the film may become soft and have a small tensile force, and the film may be easily deformed. When the cover tape substrate film is laminated with a polyester such as polyethylene terephthalate, etc., lamination defects such as dimensional deviation and wrinkles may occur. When the blending ratio of the high-density polyethylene resin is more than 90% by mass, the Young's modulus of the film may exceed 450 MPa, and the Young's modulus of the film may become too high, and after heat sealing to the carrier tape as a cover tape, the cover tape may not be peeled off smoothly, and the peeling may stop or a large force may be required for peeling, so-called zipping peeling may occur, resulting in surface defects. When the blending ratio of the low-density polyethylene resin is more than 50% by mass, the Young's modulus may be low, as in the case of a blending ratio of the high-density polyethylene resin being less than 50% by mass, and lamination defects may occur easily. When the low-density polyethylene resin is less than 10% by mass, the Young's modulus may exceed 450 MPa, as in the case where the blending ratio of the high-density polyethylene resin exceeds 90% by mass, and zipping peeling may occur, resulting in surface defects. 3 It refers to polyethylene polymerized by the above medium or low pressure method, and low density polyethylene resin has a density of 0.910g / cm3 More than 0.930g / cm 3 This refers to low-density polyethylene polymerized by the high-pressure method described below, or linear low-density polyethylene.

[0015] In the present invention, the layer C is preferably coated on the surface with a heat-sealing resin, and in terms of adhesion to the heat-sealing resin, the density is preferably 0.890 g / cm 3 More than 0.915g / cm 3 The following low-density polyethylene resins are preferably used, for example, ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, etc. 3 If larger polyethylene resins or polypropylene resins are used, the adhesive strength with the heat-sealing resin to be coated may be reduced, and the coating may not be successful, resulting in a decrease in the heat-sealing strength with the carrier tape or the seal may peel off. 3 If it is less than this, the stickiness of layer C may increase, the slipperiness of layer C may decrease, and the processability may deteriorate.

[0016] If necessary, a functional resin such as a conductive agent, e.g., polythiophene, may be added to the layers A, B, and C. Furthermore, a functional layer, e.g., a colored layer or a conductive layer, may be laminated between the layers A and B, or between the layers B and C, as long as the function of coating the resin for lamination or heat sealing is not impaired.

[0017] In the present invention, the thickness ratio of layer A to layer B and layer C is preferably 10 to 25% for layer A, 50 to 80% for layer B, and 10 to 25% for layer C, and the total thickness is preferably 10 to 100 μm.

[0018] The cover tape substrate film of the present invention preferably has a crystallinity of 70% or less, as calculated by the following formula (a). X=100-56.1×(1000×A 1300 ÷t) (a) where X is the degree of crystallinity (%), A 1300 is the wavenumber 1300 cm measured by a Fourier transform infrared spectrophotometer. -1 where t is the film thickness (μm).

[0019] The crystallinity of the cover tape substrate film of the present invention is preferably 70% or less, more preferably 20% to 60%, but if the crystallinity exceeds 70%, the film may become hard and brittle, and when laminating with polyester or the like, tension is applied to the cover tape substrate film, which may cause the film to break or crack, making lamination difficult. If the crystallinity is too low, for example, if the crystallinity is less than 20%, the film becomes soft and pliable, but therefore the film dimensions may not be stable when tension is applied to the film for lamination, and wrinkles or warping may occur easily. EXAMPLES

[0020] The cover tape substrate film of the present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0021] <Example 1> Layer A is a polyethylene resin made of low-density polyethylene (CE3059 manufactured by Sumitomo Chemical, density 0.924 g / cm 3 ) and 20% by mass of propylene-ethylene random copolymer (Sumitomo Chemical Co., Ltd.) as a polypropylene-based resin. B layer: High density polyethylene resin (Japan Polyethylene HF562, density 0.963g / cm 3 ) 70% by mass, and linear low-density polyethylene (CW3004, manufactured by Sumitomo Chemical Co., Ltd., density 0.910 g / cm3) as a low-density polyethylene resin. 3 ) 30% by mass, As the C layer, a linear low-density polyethylene (CW3004 manufactured by Sumitomo Chemical, density 0.910 g / cm) was used as a low-density polyethylene resin. 3 ) were each fed into a separate extruder. Using a T-die type composite film-forming machine, the films were co-extruded at an extrusion temperature of 200°C in a layered configuration of A / B / C so that the thickness of layer A was 5 μm, the thickness of layer B was 40 μm, and the thickness of layer C was 5 μm, for a total thickness of 50 μm, to create a film for cover tape substrate.

[0022] <Example 2> A cover tape substrate film was prepared in the same manner as in Example 1, except that layer B was made of 50% by mass of high density polyethylene and 50% by mass of linear low density polyethylene.

[0023] <Example 3> A cover tape substrate film was prepared in the same manner as in Example 1, except that layer B was made of 90% by mass of high density polyethylene and 10% by mass of linear low density polyethylene.

[0024] <Comparative Example 1> A cover tape substrate film was prepared in the same manner as in Example 1, except that layer B was made of 100% by mass of high density polyethylene.

[0025] <Comparative Example 2> A cover tape substrate film was prepared in the same manner as in Example 1, except that layer B was made of 100 mass % linear low-density polyethylene.

[0026] <Comparative Example 3> A cover tape substrate film was prepared in the same manner as in Example 1, except that layer A was made of 100 mass % low-density polyethylene.

[0027] <Comparative Example 4> A cover tape substrate film was prepared in the same manner as in Example 1, except that layer A contained 100 mass % of a propylene-ethylene random copolymer.

[0028] <Comparative Example 5> In Example 1, the C layer was made of linear low-density polyethylene (CW3006 manufactured by Sumitomo Chemical, density 0.922 g / cm 3 A cover tape substrate film was prepared in the same manner as in Example 1, except that

[0029] <Comparative Example 6> A film for a cover tape substrate was prepared in the same manner as in Example 1, except that Layer A was made of 78% by mass of low-density polyethylene and 20% by mass of propylene-ethylene random copolymer, with 2% by weight of ultra-high molecular weight polyethylene (Mipelon PM-200 manufactured by Mitsui Chemicals) as a lubricant, and Layer B was made of 100% by mass of high-density polyethylene.

[0030] The films for cover tape substrates obtained in Examples 1 to 3 and Comparative Examples 1 to 6 were evaluated as follows.

[0031] <Crystallization degree> The obtained cover tape substrate film was stored at room temperature of 23°C and humidity of 50% RH for 7 days or more after preparation, and then measured at a wavelength of 1300 cm using a Shimadzu Corporation Fourier transform infrared spectrophotometer "IRTracer-100". -1 The absorbance was measured at 100 nm and the crystallinity was calculated using the following formula (a). X=100-56.1×(1000×A 1300 ÷t) (a) X··Crystallinity (%) A 1300 ·Wave number 1300cm -1 Absorbance at t··film thickness (μm).

[0032] <Young's modulus> The obtained cover tape substrate film was stored for 7 days or more after preparation in an atmosphere of room temperature 23°C and humidity 50 RH%, and then the Young's modulus was measured in accordance with JIS K7161-1:2014 Plastics - Determination of tensile properties.

[0033] <Lamination processability> After the surface of the A layer of the obtained film for the cover tape base material was subjected to corona treatment, a biaxially oriented polyethylene terephthalate film (Toray Industries, Inc.'s "Lumirror (registered trademark)" P60) with a film thickness of 12 μm was laminated, and the presence or absence of abnormalities during the lamination process such as wrinkles and air entrapment was visually confirmed.

[0034] <Coating processability> After the surface of the C layer of the obtained film for the cover tape base material was subjected to corona treatment, an acrylic sealant resin (manufactured by Dainippon Ink and Chemicals, Inc., A450A) as a sealant layer was formed into a film with a film thickness of 2 μm, and the presence or absence of abnormalities during the coating process was visually confirmed.

[0035] <Center line average roughness of the A layer surface> The obtained film for the cover tape base material was stored in an atmosphere of room temperature 23°C and humidity 50RH% for 3 days or more after production, and then the center line average roughness (Ra) of the A layer surface was measured using a SurfCorder "ET4000A" manufactured by Kosaka Laboratory Ltd.

[0036] The evaluation results of Examples 1 to 3 and Comparative Examples 1 to 6 are shown in Table 1.

[0037] In Examples 1 to 3, due to having appropriate crystallinity and Young's modulus, there are no air entrapment or wrinkles during lamination, and the film rolls up neatly. In contrast, in Comparative Example 1, since the crystallinity and Young's modulus are too high, the film is too hard, and as a result, the film breaks and wrinkles easily during lamination. Also, in Comparative Example 2, conversely, since the crystallinity and Young's modulus are too low, the film is too soft, the dimensions shift, and it cannot be laminated uniformly, or air entrapment etc. is observed, resulting in a lamination defect. In Comparative Example 3, the slipperiness between the films is not good, cracks occur, and the dimensions shift, resulting in a lamination defect. In Comparative Example 4, the Young's modulus is high, and as a result, wrinkles are likely to occur as in Comparative Example 1. In Comparative Example 5, although there is no problem with lamination, the coating of the sealant resin cannot be performed, impairing the performance as a cover tape. In Comparative Example 6, like Comparative Example 1, the film breaks and wrinkles easily during lamination, and air entrapment occurs during lamination, resulting in poor transparency.

[0038] In this way, it is possible to provide a cover tape base material for use in electronic component packages that is neatly rolled up without defects such as wrinkles during lamination.

[0039] [Table 1]

Claims

1. The laminate has three layers, A layer, B layer and C layer. A layer contains 5 to 95% by mass of polyethylene resin and 95 to 5% by mass of polypropylene resin. B layer is mainly composed of a mixture of high density polyethylene resin and low density polyethylene resin. C layer has a density of 0.915 g / cm. ３ A cover tape substrate film containing the following low-density polyethylene resin:

2. 2. The cover tape substrate film according to claim 1, having a crystallinity of 70% or less as calculated by the following formula (a): X=100-56.1×(1000×A １３００ ÷t) ・・・(a) X...Crystallinity (%) A １３００ ・Wave number 1300cm －１ Absorbance at t: film thickness (μm)

3. 3. The cover tape substrate film according to claim 1, wherein the surface centerline average roughness Ra of layer A is 0.05 μm or more and 0.25 μm or less.

4. 3. The cover tape substrate film according to claim 1, wherein the Young's modulus of the film is 250 MPa or more and 450 MPa or less in both the longitudinal direction and the width direction of the film.

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