Release film, method for manufacturing a release film, and method for manufacturing a circuit board

Abstract

To prevent a resin from oozing from a specific resin layer by forming a film end into a specific structure.SOLUTION: A release film 10 includes a first resin layer 11, and a second resin layer 12 that is provided on at least one surface 11A side of the first resin layer 11 and has a composition different from the first resin layer 11, and has a coating part 14 coating an end face 11E of the first resin layer 11.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a release film, a method for manufacturing the same, and a method for manufacturing a circuit board.

Background Art

[0002] Conventionally, when manufacturing a circuit board such as a flexible printed circuit (FPC), it is common to perform a hot press process. In the hot press process, a release film is used to prevent the circuit board from adhering to the hot press plate. The release film is required to have properties such as heat resistance that can withstand hot press molding, releasability with respect to the FPC and the hot press plate, non-contamination with respect to the copper circuit, and ease of waste treatment.

[0003] In recent years, the line / space (L / S) of FPCs has been becoming finer, and accordingly, the required quality for the release film has been increasing, and in particular, improvement in the concavo-convex followability has been demanded. In order to improve the concavo-convex followability, the release film may have a multilayer structure and use a highly flexible material for any one of the layers. Specifically, it is common to provide a surface layer and an intermediate layer and use a highly flexible material for the intermediate layer. Further, as the highly flexible material used for the intermediate layer or the like, it is known to use a polyolefin resin such as polyethylene (PE) or ethylene-methyl methacrylate copolymer (EMMA) (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, highly flexible resins such as PE and EMMA have low melting points and may melt or flow during pressing, seeping out from the edges of the film. This seeping resin can adhere to circuit boards, press plates, and even auxiliary materials such as cushioning materials placed inside the press plate, causing contamination.

[0006] Therefore, the object of the present invention is to provide a release film that can prevent leakage from specific resin layers, such as intermediate layers, that occur when heat pressing. Another object of the present invention is to provide a method for manufacturing circuit boards that is less prone to contamination. [Means for solving the problem]

[0007] As a result of diligent research, the inventors have found that the above problems can be solved by making the film edges of a multilayer release film a specific structure, or by manufacturing a circuit board using a release film having a specific structure, and have completed the present invention as follows. That is, the present invention provides the following [1] to

[36] . [1] comprising a first resin layer and a second resin layer provided on at least one side of the first resin layer and having a different composition from the first resin layer, A release film having a covering portion that covers the end face of the first resin layer. [2] The release film according to [1] above, wherein the second resin layer forms the covering portion. [3] The second resin layer is provided on both sides of the first resin layer, The release film according to [2] above, wherein each of the second resin layers forms the covering portion. [4] The release film according to [2] or [3], wherein the second resin layer provided on one surface and forming a covering portion is connected to the second resin layer on the other surface side of the first resin layer. [5] The second resin layer is provided on both sides of the first resin layer, The release film according to any one of the above [2] to [4], wherein each of the second resin layers has an overhang that extends outward from the end face of the first resin layer. [6] The release film according to [5], wherein the length of the protruding portion is greater than the average thickness of the second resin layer. [7] The release film according to [5] or [6] above, wherein the protruding portions are bonded to each other. [8] The release film according to [7], having a compressed portion in which the protruding portions are pressed against each other and bonded together. [9] The release film according to [8] above, wherein the thickness of the crimped portion is less than the sum of the average thicknesses of each of the second resin layers.

[10] The release film according to [1] above, wherein the covering portion is formed by a covering member.

[11] The release film according to

[10] above, wherein the covering member is a resin film.

[12] The release film according to

[10] above, wherein the covering member is a sealant.

[13] The release film according to any one of the above [1] to

[12] , wherein the planar shape is polygonal and covering portions are provided on at least two sides thereof.

[14] The release film according to any one of the above items [1] to

[13] , wherein the covering portion has an inclined surface.

[15] The release film according to any one of the above [1] to

[14] , further comprising a third resin layer provided between the first resin layer and the second resin layer.

[16] comprising a first resin layer and a second resin layer provided on at least one side of the first resin layer and having a different composition from the first resin layer, A release film in which the second resin layer has an overhang portion that extends outward from the end face of the first resin layer.

[17] The release film according to

[16] , wherein the second resin layer is provided on both sides of the first resin layer, and each of the second resin layers has an overhang.

[18] The release film according to

[17] , wherein the overhang length L1 of at least one overhang of the second resin layer is 5 mm or more.

[19] Each of the protruding portions of the second resin layer has a fixing portion that is fixed to each other, The release film according to

[17] or

[18] above, having a space between the fixing portion and the first resin layer.

[20] The release film according to any one of the above

[16] to

[19] , wherein the planar shape is polygonal and covering portions are provided on at least two sides thereof.

[21] The release film according to any one of the above

[16] to

[20] , further comprising a third resin layer provided between the first resin layer and the second resin layer.

[22] A release film comprising a first resin layer and a second resin layer provided on at least one side of the first resin layer and having a different composition from the first resin layer, and having a folded portion.

[23] The release film according to

[22] , wherein the end face of the first resin layer faces inward with respect to the outer edge of the release film.

[24] The release film according to

[22] or

[23] , wherein the folded length L2 of the folded portion of the second resin layer is 5 mm or more.

[25] The release film according to any one of the above

[22] to

[24] , wherein the planar shape is polygonal and covering portions are provided on at least two sides thereof.

[26] The release film according to any one of the above

[22] to

[25] , further comprising a third resin layer provided between the first resin layer and the second resin layer.

[27] A method for manufacturing a release film, comprising the step of forming a covering portion that covers at least a part of the end face of the first resin layer of a laminate comprising a first resin layer and a second resin layer.

[28] The process includes cutting the laminate, The method for manufacturing a release film according to

[27] above, wherein, by cutting, at least a portion of the end face of the first resin layer is covered with the second resin layer to form the covered portion.

[29] A method for manufacturing a release film according to

[28] above, wherein the cutting is performed by at least one of press cutting, shear cutting, and melt cutting.

[30] A method for manufacturing a release film according to

[27] above, in which the covering portion is formed using a covering member.

[31] Provide an overhanging portion on the second resin layer that overhangs outside the end face of the first resin layer. The method for manufacturing a release film according to the above

[27] , which fixes the overhanging portions to each other.

[32] The method for manufacturing a release film according to the above

[31] , which fixes the overhanging portions to each other by at least one of stapling, adhesives, fusing, and crimping.

[33] A method for manufacturing a release film, comprising a step of folding back an end portion of a laminate including a first resin layer and a second resin layer toward the inside to form a folded-back portion.

[34] The method for manufacturing a release film according to the above

[33] , which fixes the folded-back portion by at least one of stapling, adhesives, fusing, and crimping.

[35] A method for manufacturing a circuit board, which manufactures a circuit board using the release film according to any one of the above [1] to

[26] .

[36] Prepare a first resin layer and a second resin layer having a composition different from that of the first resin layer. On the second resin layer Place a first resin layer with dimensions smaller than those of the second resin layer on top, and further stack a second resin layer with dimensions larger than those of the first resin layer to have a lamination step, and perform pressing after the lamination step, a method for manufacturing a circuit board.

Advantages of the Invention

[0008] According to the present invention, by making the film end portion have a specific structure, it is possible to prevent the resin from bleeding out from a specific resin layer such as an intermediate layer. Also, a method for manufacturing a circuit board without contamination can be provided.

Brief Description of the Drawings

[0009] [Figure 1] It is a schematic cross-sectional view showing the end structure of the release film according to the first embodiment of the present invention. [Figure 2]This is a schematic cross-sectional view showing the end structure of a release film according to a modified example of the first embodiment of the present invention. [Figure 3] This is a schematic diagram showing a method for manufacturing a release film according to the first embodiment of the present invention. [Figure 4] This is a schematic cross-sectional view showing the end structure of a release film according to a second embodiment of the present invention. [Figure 5] This is a schematic diagram showing a method for manufacturing a release film according to a second embodiment of the present invention. [Figure 6] This is a schematic cross-sectional view showing the end structure of a release film according to a third embodiment of the present invention. [Figure 7] This is a schematic diagram showing a method for manufacturing a release film according to a third embodiment of the present invention. [Figure 8] This is a schematic cross-sectional view showing the end structure of a release film according to a fourth embodiment of the present invention. [Figure 9] This is a schematic diagram showing a method for manufacturing a release film according to a fourth embodiment of the present invention. [Figure 10] This is a schematic cross-sectional view showing the end structure of a release film according to a fifth embodiment of the present invention. [Figure 11] This is a schematic diagram showing a method for manufacturing a release film according to a fifth embodiment of the present invention. [Figure 12] This is a schematic cross-sectional view showing the end structure of a release film according to a modified example of the fifth embodiment of the present invention. [Figure 13] This is a schematic cross-sectional view showing the end structure of a release film according to the sixth embodiment of the present invention. [Figure 14] This is a schematic cross-sectional view showing the end structure of a release film according to the seventh embodiment of the present invention. [Figure 15] This is a schematic cross-sectional view showing the end structure of a release film according to the eighth embodiment of the present invention. [Figure 16] This is a schematic cross-sectional view showing an end structure according to a modified example of the release film according to the eighth embodiment of the present invention. [Figure 17]This is a schematic cross-sectional view showing the end structure of a release film according to the ninth embodiment of the present invention. [Figure 18] This is a schematic cross-sectional view showing the end structure of a release film according to a modified example of the first embodiment of the present invention. [Figure 19] This is a schematic cross-sectional view showing the end structure of a release film according to a modified example of the ninth embodiment of the present invention. [Figure 20] This is a schematic cross-sectional view showing the end structure of a release film according to a modified example of the first embodiment of the present invention. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described in detail below with reference to the drawings. <First Embodiment> Figure 1 shows the end structure of a release film 10 according to the first embodiment of the present invention. As shown in Figure 1, the release film 10 comprises a first resin layer 11 and second resin layers 12 and 13 provided on both sides 11A and 11B of the first resin layer 11, respectively. Each surface 11A and 11B constitutes the main surface of the first resin layer 11. The release film 10 is a laminate in which the second resin layer 12, the first resin layer 11, and the second resin layer 13 are integrated. The release film 10 is a multilayer film in which the second resin layer 12, the first resin layer 11, and the second resin layer 13 are arranged in this order.

[0011] In the release film 10, the first resin layer 11 is an intermediate layer positioned between the second resin layers 12 and 13, and preferably has cushioning properties. That is, the first resin layer 11 preferably has flowable or flexible properties at the pressing temperature. The second resin layers 12 and 13 are surface layers that constitute the outermost surface of the release film 10. The second resin layers 12 and 13 preferably have release properties, and as will be described later, for example, when manufacturing a circuit board, they preferably have release properties from the circuit board, press plate, cushioning material, etc. That is, they preferably can be easily peeled off from the object to be pressed after pressing. By including the first resin layer 11 in addition to the second resin layers 12 and 13, the release film 10 has good release properties from the press plate and circuit board, while also having good conformability to the unevenness of the circuit board.

[0012] The resin constituting the first resin layer 11 is not particularly limited, but polyolefin resins are an example. Examples of polyolefin resins include polyethylene such as low-density polyethylene, linear low-density polyethylene, and ultra-high molecular weight polyethylene; polypropylene such as homopolypropylene and random polypropylene; ethylene-acrylic monomer copolymers such as ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-acrylic acid copolymer; and ethylene-vinyl acetate copolymer. These may be used individually or in combination of two or more. Among these, low-density polyethylene, linear low-density polyethylene, ethylene-methyl methacrylate copolymer, and ethylene-vinyl acetate copolymer are preferred.

[0013] Furthermore, the resin constituting the first layer 11 may consist solely of a polyolefin resin, but it may also contain resins other than polyolefin resins, such as polystyrene, polyvinyl chloride, polyamide, polycarbonate, polysulfone, and polyester, to the extent that it does not hinder the objectives of the present invention. However, the first layer 11 is mainly composed of a polyolefin resin, and the polyolefin resin should, for example, account for 50% by mass or more, preferably 70% by mass or more, of the total resin components contained in the first layer 11.

[0014] The second resin layers 12 and 13 have a different composition from the first resin layer 11; for example, different types of resins may be used. Examples of resins used in the second resin layers 12 and 13 include polyester resins, polyolefin resins, and polystyrene resins. These may be used individually or in combination of two or more types. Among these, polyester resins are more preferred. Therefore, it is even more preferable that the resin used in the first resin layer 11 is a polyolefin resin, and the resins used in the second resin layers 12 and 13 are polyester resins. Furthermore, the resin used in the second resin layers 12 and 13 may be the same type of resin as the resin used in the first resin layer 11. For example, the resins used in the first resin layer 11 and the second resin layers 12 and 13 may both be polyolefin resins. When using the same type of resin, it is sufficient that at least one of the following differs: for example, molecular weight, type of constituent monomer, or, in the case of a copolymer, molar ratio of constituent monomers. Alternatively, the first resin layer 11 and the second resin layers 12 and 13 may each contain two or more types of resin, and the blending ratios of each resin may be appropriately varied.

[0015] The polyester resin used in the second resin layer can be obtained, for example, by reacting a divalent acid or its ester-forming derivative as an acid component with a diol component. As the acid component, an aromatic dicarboxylic acid or its ester-forming derivative is preferred, and as the polyester resin, a crystalline aromatic polyester resin is preferred that uses an aromatic dicarboxylic acid as the acid component and has crystalline properties.

[0016] Examples of the above-mentioned aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, and paraphenylenedicarboxylic acid. Examples of ester-forming derivatives of aromatic dicarboxylic acids include ester-forming derivatives of the above-mentioned aromatic dicarboxylic acids, specifically dimethyl terephthalate, dimethyl isophthalate, dimethyl orthophthalate, dimethyl naphthalene dicarboxylic acid, and dimethyl paraphenylenedicarboxylic acid. These may be used individually or in combination of two or more types.

[0017] As the diol component, a low molecular weight aliphatic diol may be used, or a combination of a low molecular weight aliphatic diol and a high molecular weight diol may be used. Examples of low molecular weight aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol. These may be used individually or in combination of two or more. Examples of the high molecular weight diols mentioned above include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and polyhexamethylene glycol. These may be used individually or in combination of two or more types.

[0018] Specific examples of crystalline aromatic polyester resins include polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, butanediol terephthalate polytetramethylene glycol copolymer, and butanediol terephthalate-polycaprolactone copolymer. These may be used individually or in combination of two or more. Among these, polybutylene terephthalate is preferred due to its particularly excellent non-contamination and crystallinity. Furthermore, as the polyolefin resin used for the second resin layer, a resin mainly composed of poly(4-methyl-1-pentene) or a resin mainly composed of alicyclic olefin resin can be used as appropriate. As the polystyrene resin, a resin mainly composed of polystyrene resin having a syndiotactic structure can be used as appropriate.

[0019] The resin used in the second resin layers 12 and 13 may consist only of a resin selected from the polyester resin, polyolefin resin, and polystyrene resin described above. However, as long as the properties as a release layer are not impaired, it may also contain other thermoplastic resins and rubber components in addition to the resin selected from the polyester resin, polyolefin resin, and polystyrene resin described above. Other thermoplastic resins are not particularly limited, but examples include polyolefins, modified polyolefins, polystyrene, polyvinyl chloride, polyamides, polycarbonates, polysulfones, and polyesters. The rubber components are not particularly limited, but examples include natural rubber, styrene-butadiene copolymers, polybutadiene, polyisoprene, acrylonitrile-butadiene copolymers, ethylene-propylene copolymers (EPM, EPDM), polychloroprene, butyl rubber, acrylic rubber, silicone rubber, urethane rubber, olefin-based thermoplastic elastomers, styrene-based thermoplastic elastomers, PVC-based thermoplastic elastomers, ester-based thermoplastic elastomers, and amide-based thermoplastic elastomers. These thermoplastic resins and rubber components may be used individually or in combination of two or more types. However, the resin selected from the polyester resin, polyolefin resin, and polystyrene resin mentioned above may be the main component in the second resin layers 12 and 13, respectively, and may, for example, account for 50% by mass or more, preferably 70% by mass or more, of the total resin components contained in the second resin layer. The second resin layers 12 and 13 may have different compositions, or they may have the same composition. Having the same composition allows for easy manufacture of the release film 10.

[0020] Furthermore, additives may be appropriately blended into the resins constituting the first resin layer 11 and the second resin layers 12 and 13. Examples of additives include fibers, inorganic fillers, flame retardants, ultraviolet absorbers, antistatic agents, inorganic substances, and higher fatty acid salts.

[0021] In order to ensure its cushioning properties, the first resin layer 11 preferably has a lower modulus of elasticity in high-temperature environments compared to the second resin layers 12 and 13. Specifically, the storage modulus of elasticity of the first resin layer 11 should be lower than that of the second resin layers 12 and 13. The storage modulus is the storage modulus at 180°C measured under the following conditions using a dynamic viscoelasticity measuring device (for example, DVA-200 manufactured by IT Measurement Control Co., Ltd.). Measurement mode: Tensile Heating rate: 5°C / min Data acquisition interval: 1°C / min Measurement frequency 1Hz Distortion 0.1% Static / dynamic ratio 2 Minimum load 1 cN The storage modulus in the first resin layer 11 is specifically 1.0 × 10⁻⁶ 6 ~1.5×10 7 Pa is preferable. Furthermore, the storage modulus in the second resin layers 12 and 13 is, for example, 1.5 × 10⁻⁶ 7 It is better if it is greater than Pa, preferably 1.5 × 10 7 ~5.0×10 8 It is Pa.

[0022] Furthermore, the flow initiation temperature of the first resin layer 11 should be lower than that of the second resin layers 12 and 13. The flow initiation temperature refers to the temperature at which, for example, when a sample of each layer (e.g., 25 mm x 25 mm) is placed on a hot plate or the like and heated from room temperature at about 10°C / min, the sample area expands by 10% or more due to flow. The flow initiation temperature of the first resin layer can be selected or adjusted according to the hot press temperature, for example, 80 to 200°C, but may be in the range of 80 to 120°C, 120 to 160°C, or 160 to 200°C. Similarly, the flow initiation temperature of the second resin layer can be selected or adjusted according to the hot press temperature, for example, 160 to 280°C, but may be in the range of 160 to 200°C, 200 to 240°C, or 240 to 280°C. The flow initiation temperature of the first resin layer is preferably 20°C or more lower than the temperature at which hot pressing is performed. It is more preferably 30°C or more lower, even more preferably 40°C or more lower, and particularly preferably 50°C or more lower. The flow initiation temperature of the second resin layer is preferably 20°C or more higher than the temperature at which hot pressing is performed. It is more preferably 30°C or more higher, even more preferably 40°C or more higher, and particularly preferably 50°C or more higher. Furthermore, the difference between the flow initiation temperature of the first resin layer and the flow initiation temperature of the second resin layer is preferably 40°C or higher. More preferably 60°C or higher, and even more preferably 80°C or higher.

[0023] The thickness of the first resin layer 11 is preferably greater than the thickness of the second resin layers 12 and 13, respectively, from the viewpoint of ensuring appropriate cushioning and conformability to uneven surfaces. The thickness of the first resin layer 11 is, for example, 5 to 200 μm, preferably 10 to 150 μm, and more preferably 20 to 100 μm. The thickness of the second resin layers 12 and 13 is preferably 1 to 100 μm, more preferably 5 to 50 μm, and even more preferably 10 to 20 μm. A thickness of 1 μm or more prevents tearing of the release film during transport or press molding. A thickness of 100 μm or less prevents a decrease in conformability to uneven surfaces during press molding. Note that the thickness of each resin layer is the average thickness; for example, the average thickness measured at 10 points other than the edges of the release film should be used.

[0024] As shown in Figure 1, in this embodiment, one of the pair of second resin layers 12, 13, resin layer 12, forms a covering portion 14 that covers the end face 11E. In the embodiment shown in Figure 1, the second resin layer 12 covers the first resin layer 11 from one surface 11A to the end face 11E. The release film 10, with the covering portion 14 provided, can prevent the resin constituting the first resin layer 11 from seeping out from the end face 11E even when heated and pressurized during press working. In this specification, "covering" means that the end face or surface is covered, and does not necessarily mean that it is in contact with the object to be covered. Furthermore, it does not necessarily mean that it is in close contact with the object to be covered, and there may be a space between the covered portion and the end face or surface.

[0025] As shown in Figure 1, the second resin layer 12 is, in cross-section, the first resin layer 11 It is preferable to cover the entire end face 11E and connect it to the second resin layer 13 which is positioned on the other surface 11B of the first resin layer 11. In this way, by connecting the pair of second resin layers 12 and 13 to each other, it is possible to more effectively prevent resin from seeping out from the end face. However, as shown in Figure 2, the second resin layer 12 does not need to cover the entire end face 11E in cross-section, and the second resin layers 12 and 13 do not need to be connected to each other. Furthermore, although the second resin layers 12 and 13 are in direct contact with each other in the configuration shown in Figure 1, they do not necessarily need to be in direct contact. The second resin layers 12 and 13 may be connected via members other than the first resin layer, such as a third resin layer, which will be described later. In this embodiment, as will be described later, the end face 11E can be covered by plastically deforming the second resin layer 12 so that it is stretched. Therefore, the thickness of the second resin layer 12 on the end face 11E (i.e., the thickness of the covered portion 14) may be thinner than the average thickness of the second resin layer 12 on one of the surfaces 11A as described above.

[0026] In the first embodiment, the end of the first resin layer 11 may have an end face 11E that is inclined with respect to one surface 11A, as shown in Figure 1. When the end face 11E is inclined with respect to one surface 11A, the thickness of the first resin layer 11 decreases towards the tip 11F. That is, the thickness of the end of the first resin layer 11 may be less than the average thickness of the first resin layer as described above. In other words, the tip 11F of the first resin layer 11 may be tapered. The end face 11E may be an inclined surface that is inclined at an obtuse angle with respect to one surface 11A. Note that the end face 11E does not need to be a flat surface and may include a curved surface or the like as appropriate. Similarly, the covering portion 14 may have an inclined surface.

[0027] The release film according to this embodiment may be in the form of a single sheet or wound into a roll. A single sheet of release film is used, for example, when pressing sheet-shaped circuit boards, etc., by batch pressing or quick pressing, as described later. The single sheet of release film has a polygonal shape in plan view (its planar shape is polygonal), and is typically a quadrilateral such as a rectangle or square, but may also be circular. Furthermore, it is preferable that each end of the release film constituting each side (i.e., four sides in the case of a quadrilateral) is composed of an end face 11E having a covering portion 14 as described above. Since the entire single sheet of release film is generally pressed by a press plate that is slightly larger than the release film, providing a covering portion 14 at each end constituting each side can effectively prevent the first resin layer 11 from seeping out.

[0028] In the case of a single-leaf release film, it is not necessarily required that the entire end surface of the first resin layer 11 be covered; it may be partially covered, but it is preferable that a certain percentage or more is covered. Specifically, when observing the outer edge of the release film around its entire circumference from a direction perpendicular to the thickness direction, if the area of ​​the first resin layer covered in the covered portion is "A1" and the area of ​​the portion where the first resin layer is exposed is "B1", then the covering ratio calculated by the following formula should be, for example, 30% or more, preferably 50% or more, more preferably 70% or more, and most preferably 100%. Coverage ratio = A1 / (A1+B1)×100

[0029] Similarly, in a single-sheet release film, it is not necessary for all of the edges constituting each side to be made of end faces 11E having a covering portion 14; only some of the edges may be made of end faces 11E having a covering portion 14. Furthermore, if the planar shape of the release film is polygonal, it is preferable that the covering portion 14 is provided on at least two sides. For example, in the case of a quadrilateral, it is preferable that the edges constituting opposing sides are made of end faces 11E having a covering portion 14. Even with such a configuration, for example, when the release film is used in a manner in which the entire film is not pressed, the leakage of the resin constituting the first resin layer 11 is effectively prevented.

[0030] On the other hand, the roll-shaped release film may be configured such that both ends are end faces 11E having covering portions 14. The roll-shaped release film is pressed while being conveyed, for example, by roll-to-roll, and during this process, seepage occurs from both ends. By providing covering portions 14 at both ends, seepage can be effectively prevented.

[0031] Furthermore, even in the case of roll-shaped release film, both ends do not necessarily need to be completely covered by the covering portion; they may be partially covered, but it is preferable that a certain percentage or more is covered. Specifically, when observing both ends of the release film parallel to the TD direction, if the area of ​​the first resin layer covered by the covering portion is "A2" and the area of ​​the portion where the first resin layer is exposed is "B2", then the covering ratio calculated by the following formula should be, for example, 30% or more, preferably 50% or more, more preferably 70% or more, and most preferably 100%. Coverage ratio=A2 / (A2+B2)×100

[0032] However, roll-shaped release film may be cut and used as individual sheets. In such cases, after cutting, appropriate covering portions may be provided on ends other than both ends by one of the methods described later.

[0033] Next, an example of a method for manufacturing the release film according to this embodiment will be described with reference to Figure 3. In this embodiment, a laminate 16 is prepared, consisting of a second resin layer 12, a first resin layer 11, and a second resin layer 13. The method for manufacturing the laminate 16 is not particularly limited and includes, for example, a co-extrusion method such as a water-cooled or air-cooled co-extrusion inflation method or a co-extrusion T-die method, a method of laminating films by dry lamination, hot press molding, etc., after preparing films to constitute each resin layer, etc., extrusion lamination method, solvent casting method, etc.

[0034] Next, the release film 10 is obtained by cutting the laminate 16. During this cutting, the second resin layer 12 deforms and forms a covering portion 14. In this embodiment, the laminate 16 is preferably cut by pressing with a pressing blade 17, as shown in Figure 3. The pressing blade 17 may have an inclined surface 17A at its tip, for example, a Thomson blade may be used. In Figure 3, the pressing blade 17 has inclined surfaces 17A on both sides of its tip, but it may also have an inclined surface 17A on only one side. When the laminate 16, supported by, for example, a base 18, is cut by a cutting blade from the surface on the side of the second resin layer 12, as shown in Figure 3, the end face 11E of the first resin layer 11 formed by the cut becomes an inclined surface that follows the shape of the inclined surface 17A, and the second resin layer 12 is stretched and covers the end face 11E of the first resin layer 11A, thereby forming a covering portion 14. After forming the covering portion 14, the laminate can be wound up to form a roll-shaped release film. According to the above method, a release film with a covering portion at the edge can be manufactured using a simple process, making it easy to produce a release film with minimal leakage.

[0035] <Second Embodiment> Figure 4 shows the end structure of the release film according to the second embodiment. The difference between the second embodiment and the first embodiment is the structure of the end of the release film. Specifically, in the first embodiment, the end face was covered by one of the pair of second resin layers, but in this embodiment, it is covered by both of the pair of second resin layers. That is, the pair of second resin layers form the covered portion. In the following, the differences between the release film according to the second embodiment and the first embodiment will be explained, and the points that will be omitted from the explanation will be the same as in the first embodiment.

[0036] In the second embodiment, the release film 20 has a first resin layer 21 and second resin layers 22 and 23 provided on both sides 21A and 21B of the first resin layer 21, respectively, and a covering portion 24 is provided on the end face 21E of the first resin layer 21. In the embodiment shown in Figure 4, the end face 21E has an inclined surface 21G and an inclined surface 21H. Here, in this embodiment, the covering portion 24 is composed of both the second resin layers 22 and 23. That is, each of the second resin layers 22 and 23 covers the end face of the first resin layer 21. In the embodiment shown in Figure 4, the second resin layer 22 covers the first resin layer 21 from one surface 21A to the end face 21E. Similarly, the second resin layer 23 covers the first resin layer 21 from the other surface 21B to the end face 21E. 2 It is preferable that the second resin layers 22 and 23 are connected on the end face 21E. In this embodiment as well, the release film 20 is provided with a covering portion 24, which prevents the resin constituting the first resin layer 21 from seeping out from the end face 21E even when heated and pressurized during hot pressing or the like.

[0037] The pair of second resin layers 22 and 23 are arranged to connect with each other on the end face 21E, and as shown in Figure 4, the entire end face 21E is covered by the covering portion 24 in cross-section. Furthermore, in this embodiment as well, the end face 21E can be covered by plastically deforming the second resin layers 22 and 23 to stretch them, as will be described later. Therefore, the thickness of each of the second resin layers 22 and 23 on the end face 21E may be thinner than the average thickness of each of the second resin layers 22 and 23 on one surface 21A and the other surface 21B.

[0038] In the second embodiment as well, the end of the first resin layer 11 is tapered, but its tip 21F is positioned between the two surfaces 21A and 21B in the thickness direction of the release film 30, and its tip 21F is preferably connected at an obtuse angle to each surface 21A and 21B via the inclined surfaces 21G and 21H that constitute the end surface 21E. Note that the inclined surfaces 21G and 21H do not need to be flat and may include curved surfaces as appropriate.

[0039] Next, an example of a method for manufacturing the release film according to this embodiment will be described. In this embodiment, a laminate 26 is prepared, consisting of a second resin layer 22, a first resin layer 21, and a second resin layer 23. Then, the release film 20 is obtained by cutting the laminate 26, and the above-mentioned covering portion 24 is formed by the second resin layers 22 and 23 through this cutting. Here, the laminate in this embodiment 26 The cutting is preferably performed by press-cutting using a shearing blade 27, as shown in Figure 5. The shearing blade 27 generally consists of an upper blade 27A and a lower blade 27B. The upper blade 27A and the lower blade 27B are brought close to each other along the thickness direction, and a shearing force is applied to the laminate 26 to cut it. As a result of this cutting, the end face 21E of the first resin layer 21 becomes tapered, and the second resin layers 22 and 23 deform to stretch along the shape of the end face 21E, forming a covering portion 24 that covers the end face 21E, as shown in Figure 4.

[0040] <Third Embodiment> When the end face of the first resin layer is covered by a pair of second resin layers as described above, the configuration is not limited to the second embodiment described above, and may have various shapes, for example, a configuration like the release film 30 according to the third embodiment shown in Figure 6. The differences between the release film according to the third embodiment described below and the second embodiment will be explained, and the explanation will be omitted, as in the second embodiment.

[0041] In the release film 30 according to the third embodiment, as shown in Figure 6, the second resin layers 32 and 33 extend outward from the end face 31E. That is, the second resin layers 32 and 33 each have protruding portions 32F and 33F. Having protruding portions in the second resin layers makes it less likely for the first resin layer 31 to seep outside the release film. Preferably, the lengths of the protruding portions 32F and 33F are greater than the average thickness of each of the second resin layers 32 and 33 having their respective protruding portions 32F and 33F. Furthermore, it is preferable that the protruding portions 32F and 33F are bonded to each other. Bonding the protruding portions further effectively prevents seepage. Examples of bonding methods include heat fusion, chemical welding, and bonding with adhesives. In the embodiment shown in Figure 6, the end face 31E has inclined surfaces 31G and 31H.

[0042] In the manufacturing of the release film 30 according to this embodiment, first, a laminate 36 consisting of a second resin layer 32, a first resin layer 31, and a second resin layer 33 is prepared. Next, the release film 30 is obtained by cutting the laminate 36, and the covering portion 34 is formed by the cutting. Here, the laminate in this embodiment 36The cutting is preferably performed by melt cutting using a heated blade 37, as shown in Figure 7. The second resin layers 32 and 33 are stretched while being melted, covering the end face 31E and forming a covered portion 34. When melt cutting occurs, the second resin layers 32 and 33 fuse together on the end face 31E. Also, since the end of the first resin layer 31 is melted and stretched, its tip shape becomes more elongated. Not only the first resin layer 31, but also the second resin layers 32 and 33 are cut while being melted, so they are easily stretched, and the stretched second resin layers 32 and 33 can cover the end face 31E of the first resin layer 31. The heating blade 37 only needs to be heated to a temperature sufficient to melt at least the second resin layers 32 and 33. For example, it is preferable to heat it to a temperature about 30°C higher than the melting point of the resin used, preferably 5 to 20°C higher. The heating blade 37 is a cutting blade, and specifically, a cutting blade having an inclined surface 37A at its tip is shown, but it may be a cutting blade other than a cutting blade.

[0043] In the first to third embodiments described above, the covering portion was formed on the end face of the first resin layer by press cutting, shear cutting, and melt cutting, respectively. However, the covering portion may be formed by other cutting methods. Furthermore, in the shear cutting and melt cutting methods shown in the second and third embodiments, the covering portion was formed by a pair of second resin layers provided on both sides of the first resin layer. However, even when forming the covering portion by these cutting methods, the covering portion may be formed by only one of the second resin layers, similar to the first embodiment, by appropriately selecting the type of resin constituting the second resin layer or the cutting conditions. Furthermore, in the second and third embodiments, the second resin layers 22, 23 (or 32, 33) are shown to be connected to each other on the end face 21E (or 31E). However, as with the modified example of the first embodiment (see Figure 2), they do not need to be connected to each other, and there may be portions on the end face that are not covered by the covering. Also, the second resin layers 22, 23 (or 32, 33) do not need to be in direct contact with each other; they may be connected via a member other than the first resin layer, such as a third resin layer described later. In addition, there may be a space between the covering and the end face.

[0044] Furthermore, the end faces 11E, 21E, and 31E of the first to third embodiments do not necessarily have a tapered shape. For example, in the second embodiment, the two inclined surfaces 21G and 21H constituting the end face 21E were both connected at an obtuse angle to one surface 21A and the other surface 21B, but these inclined surfaces 21G and 21H may be connected at an acute angle to one surface 21A and the other surface 21B. That is, the end face 21E of the first resin layer 21 may have a shape that is recessed inward, and accordingly, the covering portion 24 may also have a shape that is recessed inward. End faces of this type can be formed, for example, by pressing a shearing blade against the end face of the first resin layer when cutting the release film. Furthermore, shaping the end face of the first resin layer into a concave form is also applicable when the covering portion is formed by only one of the second resin layers 12, as in the first embodiment. In that case as well, the concave shape can be formed by pressing the cutting blade against the end face of the first resin layer when cutting the release film.

[0045] Furthermore, although the end faces 11E, 21E, and 31E in the first to third embodiments described above are shown to have inclined surfaces, they are not required to have inclined surfaces and may, for example, be composed of vertical surfaces parallel to the thickness direction. Alternatively, they may be a combination of vertical and inclined surfaces, or they may be made of shapes other than these.

[0046] <Fourth Embodiment> In the first to third embodiments described above, the covering portion was formed by cutting during the manufacturing of the release film, but the covering portion may also be formed by methods other than cutting. A specific example of this will be explained using Figure 8 as the fourth embodiment. The differences between the release film according to the fourth embodiment and the second embodiment will be explained below, and the points that will be omitted from the explanation will be the same as in the second embodiment.

[0047] In this embodiment as well, the release film 40 comprises a first resin layer 41 and second resin layers 42 and 43 provided on both sides 41A and 41B of the first resin layer 41, respectively. In this embodiment, similar to the third embodiment, the second resin layers 42 and 43 each have protruding portions 42F and 43F. The release film 40 has a compressed portion 48 where the protruding portions 42F and 43F are pressed and bonded together. The thickness of the compressed portion 48 is smaller (thinner) than the sum of the average thicknesses of the second resin layers 42 and 43 because it becomes thinner due to compression deformation.

[0048] In this embodiment as well, the release film 40 is provided with a covering portion 44, which prevents the resin constituting the first resin layer 41 from seeping out from the end face 41E even when heated and pressurized during hot pressing. Furthermore, since the second resin layers 42 and 43 are bonded together, seepage can be prevented more reliably.

[0049] Next, an example of a method for manufacturing the release film 40 of this embodiment will be described with reference to Figure 9. In this embodiment, as shown in Figure 9, a laminate 46 is prepared in which a second resin layer 43, a first resin layer 41, and a second resin layer 42 are laminated in this order, similar to the embodiments described above. In this case, the first resin layer 41 is provided intermittently in the laminate 46, and a region 46A is provided between the second resin layers 42 and 43 where the first resin layer 41 is not provided. That is, in the laminate 46, it is preferable that multiple first resin layers 41 are arranged along the planar direction. Next, in the region 46A where the first resin layer 41 is not provided, the first and second resin layers 42 and 43 are pressed together so that they come into contact with each other, and then heated or otherwise compressed to form a compressed portion 48, thereby also forming a covered portion 44. Furthermore, through the above process, protruding portions 42F and 43F are provided, and the protruding portions 42F and 43F are fixed to each other. Subsequently, the laminate 46 may be cut along the crimped portion 48 or the like, if necessary, to obtain multiple release films 40. In Figure 9, the cutting lines are shown as dotted lines.

[0050] <Fifth Embodiment> In the fourth embodiment described above, the first resin layer was not provided in the crimped portion, but the first resin layer may be provided in the crimped portion. A specific example of this will be described as the fifth embodiment using Figure 10. In the following description, the differences between the release film according to the fifth embodiment and the fourth embodiment will be explained, and the explanation will be omitted, as in the fourth embodiment.

[0051] In this embodiment as well, the release film 50 comprises a first resin layer 51 and second resin layers 52 and 53 provided on both sides 51A and 51B of the first resin layer 51, respectively. In this embodiment, the first resin layer 51 has an overhang portion 51F, similar to the second resin layers 52 and 53. The overhang portions 51F, 52F, and 53F have a compressed portion 58 that is pressed and bonded to each other. The compressed portion 58 forms part of the covering portion 54. The thickness of the compressed portion 58 is thinner than the sum of the average thicknesses of the second resin layers 52 and 53 and the first resin layer 51 because it is thinned by compression deformation.

[0052] With the above configuration, the end face 51E of the first resin layer 51 is covered by the covering portion 54. Therefore, in this embodiment as well, the resin constituting the first resin layer 51 is prevented from seeping out from the end face 51E of the first resin layer 51.

[0053] Next, an example of a method for manufacturing the release film 50 of this embodiment will be described using Figure 11. In this embodiment, as shown in Figure 11, a laminate 56 is prepared in which a second resin layer 53, a first resin layer 51, and a second resin layer 52 are laminated in this order, similar to the first embodiment described above. Next, the laminate 56 is partially compressed and deformed by a pressing means 57 such as a heated embossing roller, so that the first resin layer 51, the second resin layers 52 and 53 are partially pressed together, and a pressed portion 58 is formed. After that, the laminate 56 is cut along the pressed portion 58, etc., to obtain the release film 50. Note that the cutting line when manufacturing the release film shown in Figure 10 is shown as a dotted line. Note that the cutting position when manufacturing the release film 50 does not have to be on the pressed portion 58, but may be the position shown by the dashed line in Figure 11. A cross-sectional view of the release film 50 obtained in this case is shown in Figure 12. Even with this configuration, the seepage of the first resin layer 51 can be suppressed. Furthermore, in the manufacturing method, it is not necessary to align the cutting position with the crimping portion 58, making manufacturing even easier. For example, when embossing and crimping are performed while the laminate 56 is conveyed by a roll-to-roll machine, it becomes possible to perform the cutting process in parallel with the embossing.

[0054] In the fourth and fifth embodiments described above (see Figures 8 to 12), it is preferable that the end faces 41E, 51E of the first resin layers 41, 51 deform, for example during compression, to have inclined surfaces 41G, 41H, 51G, 51H. However, the end faces 41E and 51E do not necessarily need to have inclined surfaces 41G, 41H, 51G, and 51H; for example, they may be composed of vertical surfaces (surfaces parallel to the thickness direction). In cases where they are formed of vertical surfaces, there may be a space between the covering portion formed by the compression of the second resin layer and the end face. However, even if there is a space, the seepage of the resin constituting the first resin layer can be adequately prevented.

[0055] Furthermore, in the fourth embodiment described above (see Figure 9), the second and 2The resin layers 42 and 43 were bonded to each other by pressure, but they may be bonded by means other than pressure, such as by fusion, or by using an adhesive. Similarly, in the fifth embodiment described above (see Figure 11), the first resin layer 51, the second and 2 The resin layers 52 and 53 were bonded to each other by pressure, but they may also be bonded by means other than pressure, for example, by fusion.

[0056] <Sixth Embodiment> In the first to fifth embodiments described above, the covering portion that covers the end face of the first resin layer is formed by the second resin layer. However, the covering portion may be formed by a covering member, which is a different member from the second resin layer. Such configurations will be described below as the release films 60 and 70 according to the sixth and seventh embodiments. In the following, we will first explain the differences between the release film according to the sixth embodiment and the first embodiment, referring to Figure 13, but the same points as in the first embodiment will be omitted from the explanation. Furthermore, "another component" means a component separate from the second resin layer when the laminate constituting the release film consists of the first and second resin layers. However, if other resin layers other than the first and second resin layers are provided to constitute the laminate, such as the third resin layer described later, then the "other component" is also a component separate from the other resin layers. However, the "other component" from the other resin layers, such as the third resin layer, may have the same resin composition as the other resin layers.

[0057] In the sixth embodiment, the release film 60 also comprises a first resin layer 61 and second resin layers 62 and 63 provided on both sides 61A and 61B of the first resin layer 61, respectively. In this embodiment, the covering portion 64 that covers the end face 61E of the first resin layer 61 is formed by a covering member. The covering member can be, for example, a resin film. The covering portion 64 can have any configuration as long as it covers the end face 61E, but for example, it is preferable to cover everything from the outer surface of the second resin layer 62 to the end face of the first resin layer and the outer surface of the second resin layer 63. The covering portion 64 may be bonded to the outer surfaces of the second resin layers 62 and 63 with an adhesive, or bonded by fusion, compression, etc. Multiple covering members may be used to form the covering portion 64. In the sixth embodiment as well, the release film 60 includes a covering portion 64, which effectively prevents the resin constituting the first resin layer 61 from seeping out.

[0058] The resin film constituting the coating portion 64 may be any known resin film, but it is preferable to use a resin film that has a higher flow initiation temperature and a higher storage modulus than the first resin layer 61. Specifically, the resins that make up the resin film can be selected and used as appropriate from those indicated above as resins that can be used for the second resin layer. For example, polyester resins, polyolefin resins, polystyrene resins, etc., can be used, and thermoplastic resins and rubber components may also be added to these resins as appropriate. A detailed explanation of these resins is as described above for the second resin layer. The thickness of the resin film is not particularly limited, but is, for example, 1 to 250 μm, preferably 5 to 150 μm.

[0059] When manufacturing the release film 60 according to this embodiment, as in the above embodiments, first, a laminate comprising a first resin layer 61 and second resin layers 62 and 63 is prepared, and a covering member (for example, a resin film) is prepared. Then, the release film 60 can be obtained by attaching the covering member (resin film) to the end of the laminate.

[0060] <Seventh Embodiment> Next, a release film 70 according to the seventh embodiment of the present invention will be described. Figure 14 shows the end structure of the release film 70 according to the seventh embodiment. In this embodiment as well, the release film 70 comprises a first resin layer 71 and second resin layers 72 and 73 provided on both sides 71A and 71B of the first resin layer 71, respectively. In this embodiment, the covering portion 74 that covers the end face 71E of the first resin layer 71 is formed by a covering member, where the covering member is a sealing material. By providing the covering portion 74 formed by the covering member (sealant), the release film 70 can effectively prevent the resin constituting the first resin layer 71 from seeping out.

[0061] The coating portion 74 formed from the encapsulant is preferably laminated not only on the first resin layer 71 but also on the end faces 72E and 73E of the second resin layers 72 and 73, as shown in Figure 14. By laminating the encapsulant layer on the end faces 72E and 73 of the second resin layers 72 and 73, it is possible to more reliably prevent seepage from the end face 71E of the resin constituting the first resin layer 71.

[0062] The release film 70 is prepared in the same manner as in the above embodiments, by first preparing a laminate having a first resin layer 71 and second resin layers 72 and 73, and then applying a sealant to the edges of the laminate to form a covering portion. 74 It can be manufactured by forming [a certain shape].

[0063] The sealing agent constituting the coating portion 74 is not particularly limited, but epoxy resin, urethane resin, silicone resin, phenolic resin, polyimide resin, etc. may be used. The thickness of the coating portion 74 is, for example, 1 to 1000 μm, preferably 10 to 500 μm.

[0064] Furthermore, the covering portion, which consists of a covering member as illustrated in the sixth and seventh embodiments described above, is not limited to a resin film or a sealant, as long as it can cover the end face of the first resin layer. Also, in the sixth and seventh embodiments, the covering portion covered not only the end face of the first resin layer but also the end face of the second resin layer, but as long as the end face of the first resin layer is covered, it is not necessary to cover the end face of the second resin layer. For example, the covering portion 74 formed by the sealant layer shown in the seventh embodiment may cover only the end face of the first resin layer.

[0065] <Eighth Embodiment> In the first to seventh embodiments described above, the end face of the first resin layer is shown to be covered by the covering portion. However, the end face of the first resin layer does not necessarily need to be covered by the covering portion. In the release film according to the eighth embodiment, the end of the second resin layer is arranged to protrude outward from the end face of the first resin layer. The differences between the release film 80 of the eighth embodiment and the first embodiment will be explained below with reference to Figure 15. Note that the same points as in the first embodiment will be omitted from the explanation.

[0066] The release film 80 according to the eighth embodiment comprises a first resin layer 81 and second resin layers 82 and 83 provided on both sides 81A and 81B of the first resin layer 81, respectively. In this embodiment, both ends of the second resin layers 82 and 83 are arranged to protrude outward from the end face 81E of the first resin layer 81, forming protruding portions 82E and 83E. In this embodiment, when the release film 80 is used in a heat press, even if the resin constituting the first resin layer 81 flows due to the heat press, the flowed resin remains between the protruding portions 82E and 83E, preventing it from seeping outward from the outer edge of the release film 80.

[0067] Here, the overhang length L1 of the second resin layers 82 and 83 should be such that even if the resin of the first resin layer 81 flows due to heat pressing, it remains between the overhang portions 82E and 83E, and adequately prevents it from seeping out from the outer edge of the release film 80. The overhang length L1 is not particularly limited, but is, for example, 5 to 50 mm, preferably 10 to 30 mm. The overhang length of the second resin layer 82 and the overhang length of the second resin layer 83 may be different.

[0068] The release film 80 according to this embodiment can be manufactured by preparing a resin film for forming the first resin layer 81 and second and third resin films for forming the second resin layers 82 and 83, and then bonding and laminating them by heat pressing or the like. In this case, the second and third resin films should be slightly larger than the first resin film. As described above, the release film of this embodiment can be manufactured simply by heat pressing resin films, making its manufacturing method easy.

[0069] In this embodiment, the release film 80, if it is in the form of a single sheet, is typically a quadrilateral such as a rectangle or square, and it is preferable that the protruding portions 82E and 83E are provided at each end of the release film that constitutes each side (i.e., all four sides) as described above. However, as with the covering portion shown in the first to seventh embodiments, it is not necessarily required that protruding portions be provided at all ends that constitute each side of the release film 80. If the planar shape of the release film is polygonal, it is preferable that protruding portions be provided on at least two sides. Furthermore, if the release film 80 is in roll form, it is preferable that protruding portions 82E and 83E be provided at both ends, similar to the covering portion described above.

[0070] In this embodiment, the protruding portions 82E and 83E at each end of the release film 80 may be fixed to each other by fixing means (not shown) such as a staple, adhesive, fusion, or crimping. When the protruding portions 82E and 83E are fixed to each other, the first resin layer 81 is sandwiched from above and below by the second resin layers 82 and 83, thereby making the laminated structure more stable. Furthermore, by fixing the protruding portions 82E and 83E together, a covering portion 84 is formed by the protruding portions 82E and 83E to cover the end face 81E, as shown in Figure 16. In this case, the covering portion 84 is preferably positioned with at least a portion of it separated from the end face 81E by a space 88, as shown in Figure 16, but the space 88 is not required. In this case, the release film 80 has a space between the fixing portion where the protruding portions 82E and 83E of the second resin layer are fixed together and the first resin layer 81.

[0071] Furthermore, when fixing with fixing means, for example, in the case of a sheet-shaped release film such as a rectangle, it is preferable to fix each end constituting each side (four sides in the case of a rectangle) with fixing means, but it is not necessarily required to fix each end constituting all sides. Even if each end constituting all sides is not fixed, for example, by fixing the ends constituting two opposing sides with fixing means, the first resin layer 81 will be properly sandwiched by the second resin layers 82 and 83 by that fixing.

[0072] Furthermore, as described above, when the first resin layer 81 is sandwiched between the second resin layers 82 and 83 by the fixing means, it becomes unnecessary to adhere the second resin layers 82 and 83 to both sides 81A and 81B of the first resin layer 81, respectively. Therefore, in the manufacture of the release film 80, it becomes unnecessary to bond the resin films together by pressing or other means. In other words, the release film 80 can be manufactured by overlapping three resin films and fixing the protruding parts with the fixing means, thus simplifying the manufacturing method and making it easy to manufacture without introducing large-scale manufacturing equipment. Furthermore, in this embodiment, both ends of the second resin layers 82 and 83 are arranged to protrude outward from the end face 81E of the first resin layer 81, forming protruding portions 82E and 83E. However, the lengths of the protruding portions do not have to be the same. That is, the protruding portion 82E may be longer than the protruding portion 83E, or the protruding portion 82E may be shorter than the protruding portion 83E.

[0073] <Ninth Embodiment> Figure 17 shows the end structure of the release film according to the ninth embodiment. The differences between the release film 90 according to the ninth embodiment and the first embodiment will be explained below, while the points that will be omitted from the explanation will be the same as in the first embodiment. The release film 90 according to the ninth embodiment comprises a first resin layer 91 and second resin layers 92 and 93 provided on both sides 91A and 91B of the first resin layer 91, respectively. In this embodiment, the release film 90 has a folded portion 98. That is, it has a structure in which the end is folded inward toward the inside of the release film. Therefore, the end face 91E of the first resin layer 91 is located inside the outer edge 90E of the release film 90. Also, the end face 91E of the first resin layer 91 faces inward relative to the outer edge 90E of the release film 90. In the folded portion 98, one of the second resin layers 92 is arranged on the outer circumference side, and the other second resin layer 93 is arranged on the inner circumference side. With this configuration, even if the resin constituting the first resin layer 91 flows due to hot pressing, the resin does not immediately flow out to the outside of the outer edge 90E of the release film 90, thus preventing the resin from seeping out from the outer edge of the release film 90.

[0074] As shown in Figure 17, the outer surfaces of the second resin layer 93 come into contact with each other at the folded portion 98 of the release film 90. These can be fixed by means of adhesive bonding, fusion, compression, or a stapler. By fixing the outer surfaces of the second resin layer 93 together, the release film 90 can be easily held in a folded state at its end. The release film 90 may be formed, for example, by folding back the edges of a laminate composed of a first resin layer 91 and second resin layers 92 and 93. In this embodiment, the folded portion has a gently curved shape, but it may also be flattened. The thickness of the folded portion may be less than the average thickness of the release film.

[0075] In this embodiment, the fold length L2 (i.e., the length from the outer edge 90E of the release film 90 to the end face 91E of the first resin layer 91) should be long enough so that even if the resin constituting the first resin layer 91 flows out from the end face 91E of the resin layer 91 during hot pressing, it remains inside the outer edge 90E of the release film 90. The length L2 is not particularly limited, but for example, it is 1 to 50 mm, preferably 5 to 30 mm.

[0076] Furthermore, in this embodiment, if the release film 90 is in the form of a single sheet, it is typically a rectangle, square, or other quadrilateral, but it is preferable that each end of the release film constituting each side (i.e., all four sides) has a folded portion. However, it is not necessarily required that all ends constituting each side of the release film 90 have a folded portion. For example, if the planar shape of the release film is a polygon, it is preferable that it has folded portions on at least two sides. Also, if the release film 90 is in the form of a roll, it is preferable that both ends have folded portions, similar to the covering portion described above.

[0077] <Other variations> In the release films according to the first to ninth embodiments described above, the second resin layer is provided on both sides of the first resin layer. However, the second resin layer may be provided on only one side of the first resin layer. A specific example of this is shown in Figure 18. Figure 18 is a modified example of the first embodiment, in which the release film 10 comprises a first resin layer 11 and a second resin layer 12 provided only on one side 11A of the first resin layer 11. In this modified example, a covering portion 14 is formed by the second resin layer 12, similar to the first embodiment. The configuration of the covering portion 14 is as described in the first embodiment, but the second resin layer 13 is not provided on the other side 11B. Therefore, the covering portion 14 formed by the second resin layer 12 does not come into contact with the resin layer (second resin layer) provided on the other side 11B.

[0078] Similarly, in the second and third embodiments, the second resin layer may be provided on only one side of the first resin layer, in which case the covering portion may be formed by only one of the second resin layers. Also, in the sixth to ninth embodiments, one of the pair of second resin layers may be omitted. Figure 19 shows a modified example of the ninth embodiment, in which the second resin layer is provided on only one side of the first resin layer. In this modified example, the second resin layer 92 is positioned on the outer periphery side at the folded portion. In the release film 90 according to the ninth embodiment (see Figure 17), the outer surfaces of the second resin layers were in contact with each other, but in this modified example (see Figure 19), it is sufficient for the other surfaces 91B of the first resin layer 91 to be in contact with each other, and the other surfaces 91B can be fixed together by means of fixing such as adhesive bonding, fusion, compression, or a stapler. Furthermore, in the first to third embodiments and the sixth to ninth embodiments, the method for manufacturing the release film when the second resin layer 13 is provided on only one surface is the same as described in each embodiment, except that one of the second resin layers is omitted in the prepared laminate.

[0079] Furthermore, in each embodiment, a third resin layer may be provided between the first resin layer and the second resin layer. Preferably, the third resin layer functions as an adhesive layer that bonds the first resin layer and the second resin layer. As an example of a structure in which the third resin layers 19A and 19B are provided, a modified example of the first embodiment is shown in Figure 20. In Figure 20, one second resin layer 12 is shown connected to the other second resin layer 13 via the third resin layer 19B, but even when a third resin layer is provided, the second resin layers 12 and 13 may be in direct contact with each other. Of course, the second resin layers 12 and 13 do not have to be connected to each other, and a part of the end face 11E does not have to be covered by the covering portion 14. In the first to sixth embodiments, the third resin layer may form a covering portion together with the second resin layer as shown in Figure 20, or it may not form a covering portion.

[0080] The resin constituting the third resin layer may be any resin as long as it performs its function, but it is preferable that it contains, for example, the resin that constitutes the main component of the first resin layer and the resin that constitutes the main component of the second resin layer that is in contact with the third resin layer. Therefore, it is preferable that the third resin layer contains a polyolefin resin other than a polymethylpentene resin and at least one selected from polyester resins and polymethylpentene resins. The third resin layer may also contain other thermoplastic resins and rubber components. Details of these resins, thermoplastic resins and rubber components are as described in the descriptions of the first and second resin layers. The thickness of each of the third resin layers is, for example, 5 to 50 μm, preferably 10 to 30 μm.

[0081] In this case, if the second resin layer is provided on both surfaces of the first resin layer, the third resin layer may be provided only between the first resin layer and one of the second resin layers, but it is preferable to provide it between the first resin layer and each of the second resin layers, as shown in Figure 20. In this way, the release film can adhere the second resin layer to the first resin layer with high adhesive strength by providing the third resin layer.

[0082] The release film of the present invention, by having the above-described configuration, is designed so that the resin constituting the first resin layer is less likely to seep out to the outside of the release film when heated and pressed. Specifically, the release film of the present invention is heated at 170°C for 30 minutes at 30 kgf / cm². 2 Preferably, the amount of seepage of the first resin layer when pressed with the specified pressure is 1.5 mm or less, and more preferably 1.3 mm or less. By keeping the amount of seepage below the above upper limit, contamination of, for example, circuit boards, press plates, and even auxiliary materials such as cushioning materials can be effectively prevented. The amount of seepage refers to the length of the resin that constitutes the first resin layer, relative to the outer edge of the release film, when heated and pressed under the above pressing conditions. The maximum value of the seepage length is used.

[0083] <How to use release film> The release film of the present invention can be suitably used, for example, in the manufacture of circuit boards such as FPCs. A circuit board can be manufactured by preparing a core substrate, a coverlay film, and a release film, and integrating the core substrate and coverlay film by hot pressing using the release film. The method for manufacturing a circuit board will be described in detail below.

[0084] The core substrate comprises a base material made of polyimide resin, polyester resin, liquid crystal polymer, etc., and a circuit section formed on the base material using a conductive material such as copper. The circuit section may be provided on one side of the base material or on both sides. A coverlay film comprises a base film and an adhesive layer provided on one side of the base film. Examples of base films include polyimide resin films, polyester resin films, and liquid crystal polymers. The adhesive layer is composed of epoxy adhesives, acrylic adhesives, and the like. The release film can be appropriately selected from the release films of the present invention described above. As described later, a pair of release films is prepared, and they may have the same configuration or different configurations. Furthermore, it is sufficient to use only one of the release films of the present invention described above, but it is preferable to use both release films of the present invention described above.

[0085] In this manufacturing method, it is preferable to layer the core substrate, coverlay film, and release film. When doing so, it is preferable to layer the coverlay film on the core substrate so that the side with the adhesive layer faces the core substrate. Furthermore, it is preferable to layer the coverlay film on the side of the core substrate where the circuit portion is provided. Therefore, if the circuit portion is provided on both sides of the substrate, it is preferable to layer the coverlay film on both sides of the substrate, and if the circuit portion is provided on one side of the substrate, it is preferable to layer the coverlay film on one side of the substrate. Furthermore, the release film is best layered on both sides of the core substrate, and if a coverlay film is layered on the core substrate, the release film should be layered on the outside of the coverlay film. Therefore, specifically, it is best to layer the materials in the following order: release film / coverlay film / core substrate / release film, or release film / coverlay film / core substrate / coverlay film / release film.

[0086] Next, as described above, the laminate of the stacked core substrate, coverlay film, and release film is heated and pressed using a press plate, thereby bonding the coverlay film to one or both sides of the core substrate with an adhesive layer and integrating them, thereby obtaining a circuit board. The release film should be peeled off from the obtained circuit board. For example, a pair of press plates can be used to heat-press the laminated material between them, but a cushioning material may be appropriately placed between the release film and the press plate. Examples of cushioning materials include glass cloth, paper, PVC film, polyester film, and polyolefin film.

[0087] As described above, the release film of the present invention is such that even when heated and pressurized by a heat press, the resin constituting the first resin layer does not easily seep out to the outside of the release film. Therefore, contamination of the circuit section, cushioning material, press plate, etc., caused by the release film during heat pressing can be prevented.

[0088] Furthermore, as described above, the release film may have a second resin layer on only one side. In such cases, the side with the second resin layer may face either the core substrate side or the press plate side, but it is preferable to face it towards the core substrate side to prevent contamination of the circuit area.

[0089] The above-mentioned circuit boards may be manufactured using batch presses, quick presses, or roll-to-roll presses. When using batch presses or quick presses, the core substrate, coverlay film, and release film should all be prepared in sheet form, and these should be stacked and pressed to manufacture the circuit boards. In the case of roll-to-roll manufacturing, the core substrate, coverlay film, and release film, which are wound into rolls, are unwound into sheets and stacked. The core substrate and coverlay film are then integrated by heat pressing using a press plate between the rolls to manufacture the circuit board. The release film can be peeled off after the circuit board is obtained while the circuit board is being transported between the rolls.

[0090] As a variation of the eighth embodiment, an example of a method for manufacturing a circuit board is shown. In the eighth embodiment, the release film was an integrated film comprising a first resin layer and second resin layers 82 and 83 provided on both sides of the first resin layer, respectively. On the other hand, these resin layers can also be prepared as separate resin films instead of being integrated, and when pressing, they can be laminated in the order of the second resin layer (one of the second resin films), the first resin layer (the first resin film), and the second resin layer (the other of the second resin films). In this case, by making the dimensions of the second resin film larger than those of the first resin film and providing an overhang on the second resin film, it is possible to prevent the resin constituting the first resin film from seeping out and contaminating the surroundings. That is, the method for manufacturing a circuit board shown here has a lamination step of stacking a first resin film smaller in dimensions than the second resin film on top of the second resin film, and then stacking a second resin film larger in dimensions than the first resin film. A circuit board can be manufactured by pressing after such a lamination process. Each resin film used in the circuit board manufacturing method shown here can have the same configuration as each resin layer of the release film according to the eighth embodiment.

[0091] The method of using the release film described above is just one example, and the release film may be used in other ways. For example, it may be used as a release film when manufacturing items other than circuit boards by heating and pressing using a press plate. [Explanation of symbols]

[0092] 10, 20, 30, 40, 50, 60, 70, 80, 90 Release film 11, 21, 31, 41, 51, 61, 71, 81, 91 First resin layer 11E, 21E, 31E, 41E, 51E, 61E, 71E, 81E, 91E End faces of the first resin layer 12, 13, 22, 23, 32, 33, 42, 43, 52, 53, 62, 63, 72, 73, 82, 83, 92, 93 Second resin layer 14, 24, 34, 44, 54, 64, 74 Covering 16, 26, 36, 46, 56 laminated bodies 17 Cutting blade 27 Shear blades 37 Heated blade 48, 58 Crimping section 57 Crimping means 82E, 83E Overhang

Claims

1. The material comprises a first resin layer and a second resin layer provided on one side and the other side of the first resin layer, respectively, and having a different composition from the first resin layer. Having a covering portion that covers the end face of the first resin layer, The second resin layer on one of the surfaces covers the first resin layer from the one surface to the end surface, and the thickness of the second resin layer on the end surface is smaller than the average thickness of the second resin layer on the one surface. A release film in which the second resin layer on the other side covers the first resin layer from the other side to the end face, and the thickness of the second resin layer on the end face is smaller than the average thickness of the second resin layer on the other side.

2. The material comprises a first resin layer and a second resin layer provided on one side and the other side of the first resin layer, respectively, and having a different composition from the first resin layer. Having a covering portion that covers the end face of the first resin layer, The second resin layer on one of the surfaces covers the first resin layer from the one surface to the end surface, and the thickness of the second resin layer on the end surface is smaller than the average thickness of the second resin layer on the one surface. A release film in which each of the second resin layers on one side and the other side has an overhang that extends outward from the end face of the first resin layer.

3. The release film according to claim 2, wherein the protruding portions are bonded to each other.

4. The release film according to claim 2 or 3, wherein the length of the protruding portion is greater than the average thickness of the second resin layer having the protruding portion.

5. The release film according to any one of claims 2 to 4, having a compressed portion formed by the pressing and bonding of the protruding portions against each other.

6. The release film according to claim 5, wherein the thickness of the crimped portion is less than the sum of the average thicknesses of each of the second resin layers.

7. The release film according to any one of claims 1 to 6, wherein the planar shape is polygonal and covering portions are provided on at least two sides thereof.

8. The release film according to any one of claims 1 to 7, wherein the covering portion has an inclined surface.

9. The release film according to any one of claims 1 to 8, further comprising a third resin layer provided between the first resin layer and the second resin layer.

10. A method for manufacturing a circuit board, comprising manufacturing a circuit board using a release film according to any one of claims 1 to 9.

Images