TW202246062A - Release film and method for manufacturing flexible circuit board - Google Patents

Abstract

This invention provides a release film having a first release layer consisting of thermoplastic resin material on one surface and having a cushion layer on the first release layer, wherein the cushion layer comprises (B1) polybutylene terephthalate (PBT), (B2) polypropylene, and (B3) ethylene-methyl methacrylate copolymer (EMMA).

Description

Release film and method of manufacturing flexible printed circuit board

The invention relates to a method for manufacturing a release film and a flexible printed circuit board.

Mold release films are usually used when manufacturing molded products or when manufacturing laminates that bond different materials. For example, this release film is used to bond a cover layer film (hereinafter also referred to as "CL film") to a flexible film with exposed circuits (hereinafter also referred to as "circuit-exposing film") by heating and pressing. ") to make a flexible printed circuit board (hereinafter also referred to as "FPC").

For example, Patent Document 1 discloses a release film which is laminated with a release layer containing polybutylene terephthalate, and a film composed of polybutylene terephthalate and ethylene-methyl methacrylate copolymer. The buffer layer composed of substances. [Prior Art Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2015-58691

[Problem to be solved by the invention]

However, in recent years, the technical level required for various characteristics of the release film is getting higher and higher. Regarding the release film disclosed in Patent Document 1, there is room for improvement from the viewpoint of both release properties and followability. Also, there is room for improvement from the viewpoint of heat resistance.

The first subject of the present invention is to provide a release film in which releasability and followability are obtained in a highly balanced manner. Moreover, the 2nd subject of this invention is to provide the mold release film which obtains more favorable heat resistance maintaining the said height balance. [Means to solve the problem]

According to the present invention, a release film is provided, which has a first release layer made of a thermoplastic resin material on one surface, and a buffer layer on the first release layer, wherein The buffer layer contains (B1) polybutylene terephthalate (PBT), (B2) polypropylene, and (B3) ethylene-methyl methacrylate copolymer (EMMA).

Also, according to the present invention, a release film is provided, which has a first release layer made of a thermoplastic resin material on one surface, and a buffer layer containing polypropylene on the first release layer, the release film satisfies The following conditions. Conditions: In the DSC curve C1 obtained by measuring the release film at a heating rate of 5°C/min with a differential scanning calorimeter, P1 (mJ/mg) represents "from 140°C to 170°C The heat of fusion obtained from the endothermic peak of polypropylene within the temperature range", and after obtaining the DSC curve C1, it is cooled at 50°C/min until the temperature in the differential scanning calorimeter becomes 25°C. In the DSC curve C2 obtained by setting the heating rate at 5°C/min and measuring with a differential scanning calorimeter, P2 (mJ/mg) represents "from polypropylene in the temperature range of 140°C to 170°C When the heat of fusion obtained from the endothermic peak is ", the ratio of the values of P1 and P2 (P1/P2) is greater than 1.

Also, according to the present invention, a method for manufacturing a flexible printed circuit board is provided, including: On the surface of the cover layer film, the step of arranging the first release layer of the above-mentioned release film in a manner of abutting against the surface; the step of heat pressing both the cover layer film and the release film together; and A step of peeling the release film from the coverlay film. [Effect of Invention]

According to the present invention, it is possible to provide a release film in which releasability and followability are highly balanced. Also, according to the present invention, it is possible to provide a release film in which release properties and followability are obtained in a highly balanced manner while obtaining good heat resistance.

(first embodiment) The mold release film of the first embodiment has a first mold release layer made of thermoplastic resin material on one surface, and has a buffer layer on the first mold release layer, and the buffer layer contains (B1) polybutylene terephthalate ester (PBT), (B2) polypropylene and (B3) ethylene-methyl methacrylate copolymer (EMMA).

(Laminated structure) The laminated structure of the release film 100 is not limited as it only needs to include, for example, a first release layer and a buffer layer on the first release layer. The laminated structure of the release film 100 may include, for example, two or more release layers (first release layer and second release layer). As the laminated structure of the release film 100 , for example, as shown in FIG. 1 , it may be composed of a release layer 110 and a buffer layer 120 laminated thereon. Also, as the laminated structure of the release film 100, for example, as shown in FIG. The second release layer 110b may also form the outer surface of the release film 100A.

In addition, the release film 100 may have a structure having four or more layers such as an adhesive layer (primer layer) and a gas barrier layer, or five layers. In this case, the adhesive layer and the gas barrier layer are not particularly limited, and conventionally known ones can be used.

The thickness of the release film 100 is preferably, for example, 25 to 300 μm from the viewpoint of obtaining good release properties and followability.

Hereinafter, each layer of the release film 100 will be described in detail.

(release layer) The release layer 110 forms one outer surface of the release film 100 . The thickness of the release layer 110 is preferably, for example, not less than 10 μm and not more than 40 μm. Favorable mold releasability can be shown by being more than the said lower limit, and favorable embedding property can be exhibited by being below the said upper limit.

The release layer 110 is formed of (A) thermoplastic resin material. Here, (A) thermoplastic resin material contains a thermoplastic resin, for example. The thermoplastic resin contained as (A) thermoplastic resin material includes, for example, polyethylene terephthalate (PET) resin, polyethylene naphthalate (PEN) resin, and polybutylene terephthalate (PBT) resin. Resins mainly composed of polyester resins are preferred. Among them, it is preferable to contain a polyethylene terephthalate (PET) resin from the viewpoint of highly controlling the balance between mold release properties and followability.

Specific examples of the PBT resin include polybutylene terephthalate homopolymers and copolymers of polybutylene terephthalate and polytetramethylene glycol. Specifically, what is available as a PBT resin is marketed by Mitsubishi Engineering-Plastics Corporation under the brand name NOVADURAN (registered trademark), for example.

In addition, the thermoplastic resin contained in the (A) thermoplastic resin material includes, for example, elastomer resins, polyolefin-based resins, polystyrene-based resins, polyamide-based resins, polyphenylene ether resins, and And polyphenylene sulfide resin (PPS) is preferred. In addition, these resins can be used individually or in combination of 2 or more types.

Examples of the elastomer resin include natural rubber, polybutadiene, polyisoprene, polyisobutylene, neoprene, polysulfide rubber, mercaptan rubber, acrylic rubber, urethane rubber, silicone rubber, Epichlorohydrin rubber, styrene-butadiene block copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS ), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene block copolymer (SIR), hydrogenated styrene-isoprene block copolymer ( SEP), styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS) or ethylene propylene rubber (EPM), ethylene propylene Diene rubber (EPDM), olefin-based rubber such as linear low-density polyethylene elastomer, or butadiene-acrylonitrile-styrene-core-shell rubber (ABS), methyl methacrylate-butadiene-styrene- Core-Shell Rubber (MBS), Methyl Methacrylate-Butyl Acrylate-Styrene-Core-Shell Rubber (MAS), Octyl Acrylate-Butadiene-Styrene-Core-Shell Rubber (MABS), Alkyl Acrylate- Butadiene-acrylonitrile-styrene-core-shell rubber (AABS), butadiene-styrene-core-shell rubber (SBR), methyl methacrylate-butyl acrylate-siloxane, etc. containing siloxane Core-shell type granular elastomers such as core-shell rubber, or rubbers made by modifying them.

Examples of the polyolefin-based resin include linear high-density polyethylene, linear low-density polyethylene, high-pressure low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, intercalated segmented polypropylene, atactic polypropylene, polybutene, 1,2-polybutadiene, 4-methylpentene, cyclic polyolefins and their copolymers (e.g. ethylene-methyl methacrylate copolymer wait.

Examples of the polystyrene resin include atactic polystyrene, parallel polystyrene, high-impact polystyrene (HIPS), and acrylonitrile-butadiene-styrene copolymer (ABS). , acrylonitrile-styrene copolymer (AS), styrene-methacrylic acid copolymer, styrene-methacrylic acid/alkyl ester copolymer, styrene-methacrylic acid/glycidyl ester copolymer, styrene - Acrylic acid copolymers, styrene-acrylic acid/alkyl ester copolymers, styrene-maleic acid copolymers, styrene-fumaric acid copolymers, etc.

Examples of the polyamide-based resin include nylon (registered trademark) 6, nylon (registered trademark) 6,6, and the like.

Furthermore, (A) thermoplastic resin material, in order to impart various functions, various additives are blended, such as antiblocking agent, antioxidant, nucleating agent, antistatic agent, processing oil, plasticizer, mold release agent, barrier Flame retardants, flame retardant additives, pigments, etc. may also be used. Hereinafter, main components are demonstrated.

(anti-blocking agent) As said antiblocking agent, the following inorganic particle or organic particle is mentioned. Examples of inorganic particles include oxides, hydroxides, sulfides, and nitrides of Group IA, Group IIA, Group IVA, Group VIA, Group VIIA, Group VIIIA, Group IB, Group IIB, Group IIIB, and Group IVB elements. , halides, carbonates, sulfates, acetates, phosphates, phosphites, organic carboxylates, silicates, titanates, borates and their hydrates, and complexes centered on them Compounds and natural mineral particles, etc.

Specific examples of inorganic particles used as an anti-blocking agent include lithium fluoride, borax (sodium borate hydrate) and other Group IA element compounds; magnesium carbonate, magnesium phosphate, magnesium oxide (magnesium oxide), magnesium chloride, magnesium acetate , magnesium fluoride, magnesium titanate, magnesium silicate, magnesium silicate hydrate (talc), calcium carbonate, calcium phosphate, calcium phosphite, calcium sulfate (gypsum), calcium acetate, calcium p-titanate, calcium hydroxide, Calcium silicate, calcium fluoride, calcium titanate, strontium titanate, barium carbonate, barium phosphate, barium sulfate, barium sulfite and other group IIA element compounds; titanium dioxide (titanium oxide), titanium monoxide, titanium nitride, titanium dioxide Compounds of group IVA elements such as zirconium (zirconium oxide) and zirconia; compounds of group VIA elements such as molybdenum dioxide, molybdenum trioxide and molybdenum sulfide; compounds of group VIIA elements such as manganese chloride and manganese acetate; cobalt chloride and cobalt acetate, etc. Compounds of group VIII elements; compounds of group IB elements such as copper iodide (I); compounds of group IIB elements such as zinc oxide and zinc acetate; aluminum oxide (aluminum oxide), aluminum hydroxide, aluminum fluoride, aluminosilicate (silicate Aluminum, kaolin, kaolinite) and other group IIIB element compounds; silicon oxide (silica, silica gel), graphite, carbon, graphite (graphite), glass and other group IVB element compounds; carnalite (carnalite), kubeinite, Particles of natural minerals such as mica (mica stone, phlogopite), rose red ore.

Examples of organic particles used as an anti-blocking agent include Teflon (registered trademark), melamine-based resin, styrene-divinylbenzene copolymer, acrylic resin polysiloxane, and cross-linked products thereof.

The average particle diameter of the above-mentioned inorganic particles or organic particles is preferably 0.1-10 μm, and the addition amount is preferably 0.01-15% by weight.

These antiblocking agents can be used individually or in combination of 2 or more types.

Examples of antioxidants include phosphorus-based antioxidants, phenolic antioxidants, sulfur-based antioxidants, acrylic acid 2-[(1-hydroxy-3,5-di-tertiary pentylphenyl)ethyl]-4, 6-di-tertiary pentylphenyl ester, etc. These antioxidants can be used individually or in combination of 2 or more types.

Examples of the nucleating agent include metal salts of carboxylic acids such as di(p-tertiary butylbenzoate) aluminum, phosphoric acid such as sodium bis(2,4-di-tertiary butylphenol) acid phosphate, etc. Metal salts, talc, phthalocyanine (phthalocyanine) derivatives, etc. These nucleating agents can be used individually or in combination of 2 or more types.

Examples of plasticizers include polyethylene glycol, polyamide oligomers, ethylidenebisstearamide, phthalates, polystyrene oligomers, polyethylene wax, polysiloxane oil etc. These plasticizers can be used individually or in combination of 2 or more types.

Examples of the release agent include polyethylene wax, silicone oil, long-chain carboxylic acid, long-chain carboxylic acid metal salt, and the like. These mold release agents can be used individually or in combination of 2 or more types. As the release agent of this embodiment, for example, long-chain carboxylic acid esters that do not contain montanic acid ester wax or the like are preferable. Thereby, it is possible to suppress the release agent from adhering to the FPC during molding of the FPC. Therefore, when long-chain carboxylic acid esters such as montanic acid ester wax are not contained, it is possible to prevent the electroplating layer from being deposited on the FPC when a circuit is formed on the FPC. Also, as the shape of the long-chain carboxylate, for example, it is more preferable not to use a particle shape. Thereby, the outer surface of the mold release film 100 can be smoothed, and mold release property and followability can be further improved.

Examples of the processing oil include paraffin-based oils, naphthene-based oils, and aromatic-based oils. Among them, if the carbon number related to the paraffin (straight chain) calculated by the n-d-M method is calculated as a percentage relative to the total carbon number, it is preferably a paraffin oil with a Cp of 60% or more.

Regarding the viscosity of the processing oil, the kinematic viscosity at 40°C is preferably 15-600cs, more preferably 15-500cs. Also, the amount of processing oil added is preferably 0.01 to 1.5 parts by weight, more preferably 0.05 to 1.4 parts by weight, and even more preferably 0.1 to 1.3 parts by weight, based on 100 parts by weight of the resin forming the release layer 110 . These processing oils can be used individually or in combination of 2 or more types.

In addition, when the release film 100 of this embodiment has multiple release layers such as the first release layer 110a and the second release layer 110b, for example, the multiple release layers can be made of the same (A) thermoplastic resin material, and may also be formed from different (A) thermoplastic resin materials. In addition, the thicknesses of multiple release layers such as the first release layer 110a and the second release layer 110b may be the same as or different from each other, for example.

For example, when the second release layer 110b is formed of a material different from that of the first release layer 110a, as the second release layer 110b, for example, PET resin, PBT resin, fluororesin, polypropylene, 1,4-formaldehyde, etc. are used. It is better to form a system such as base pentene and p-polystyrene (SPS).

(The buffer layer) The buffer layer 120 is laminated on the release layer 110, for example. The buffer layer 120 is used to uniformly transfer the pressure and heat to the object during heating and pressing, and closely adhere to the shape of the surface of the object to follow.

The buffer layer 120 is preferably made of flexible resin, and contains (B1) polybutylene terephthalate (PBT), (B2) polypropylene and (B3) ethylene-methyl methacrylate copolymer (EMMA) . The content ratio of these ingredients (B1), ingredients (B2) and ingredients (B3) {(B1):(B2):(B3)} is 5~50:5~50:20~70 is better, 10~ 50: 10-50: 30-60 is better. By combining these components (B1) to (B3), it is possible to suppress the outflow of the buffer layer at the time of pressing and to follow a good circuit pattern. Furthermore, even when hot pressing is performed at a high temperature, the stain resistance can be maintained well, and the releasability and followability can be obtained in a high balance. By combining such components (B1) to (B3), it was first discovered by the present inventors that stain resistance, mold release properties, and followability can be achieved at the same time. In particular, the combination of the components (B1) to (B3) can maintain the stain resistance during high-temperature pressing, and at the same time take into account the mold release and followability, which is an effect that cannot be obtained by conventional technologies.

As the polybutylene terephthalate of the above-mentioned component (B1), the same thing as the PBT resin described for the above-mentioned mold release layer 110 can be used. The component (B1) and the release layer 110 may be the same component or composition, or may be different from each other.

As the polypropylene of the above-mentioned component (B2), known ones, ie, same-type, random-type, and block-type polypropylene resins, can be used. By pressing the component (B2) at a high temperature of, for example, 190-200° C., a good balance between mold release and followability can still be maintained. That is, when the conventional release film is hot-pressed at high temperature, the modulus of elasticity of the release film becomes small, so there is a tendency that the embedding property of FPC etc. in surface irregularities becomes better, while the release property tends to decrease. . Also, since the buffer layer tends to flow out, there is a problem of contamination of electronic devices. On the other hand, according to the mold release film of the present invention, by combining a predetermined amount of polypropylene, even if it is hot-pressed at a high temperature, it can still maintain good stain resistance and maintain a high balance between mold release and followability.

The melt flow rate MFR of polypropylene of component (B2) [measurement method: JIS K7210, measurement conditions Heating temperature: 230°C, load: 21.18N] is preferably 0.5g/10min or more and 2.5g/10min or less. Favorable followability with respect to a circuit pattern can be shown by setting it as more than the said lower limit, and it can prevent the buffer layer 120 from flowing out by making it below the said upper limit.

The ethylene-methyl methacrylate copolymer as the component (B3) preferably contains a unit derived from methyl methacrylate in an amount of not less than 5% by weight and not more than 20% by weight. By making the unit derived from methyl methacrylate more than the above-mentioned lower limit value, good followability to the circuit pattern can be shown while maintaining good mold releasability, and by being below the above-mentioned upper limit value, The buffer layer 120 can be prevented from flowing out from the end.

In addition to the above-mentioned components (B1) to (B3), the buffer layer 120 may further contain, for example, a rubber component. Examples of rubber components include styrene-based thermoplastic elastomers such as styrene-butadiene copolymers and styrene-isoprene copolymers, olefin-based thermoplastic elastomers, amide-based elastomers, and polyester-based elastomers. Thermoplastic elastomer materials such as body, rubber materials such as natural rubber, isoprene rubber, neoprene rubber, silicone rubber, etc.

In buffer layer 120, in addition to the above-mentioned components (B1) to (B3), it may further contain, for example, antioxidants, slip agents, anti-blocking agents, antistatic agents, coloring agents such as dyes and pigments, stabilizers, etc. Additives, impact resistance imparting agents such as fluororesin, silicone rubber, etc., inorganic fillers such as titanium oxide, calcium carbonate, talc, etc.

In addition, known methods such as an air-cooled or water-cooled pneumatic extrusion method, T-die extrusion method, etc. can be mentioned as a method for forming the buffer layer 120 .

The thickness of the buffer layer 120 is preferably not less than 30 μm and not more than 100 μm, more preferably not less than 40 μm and not more than 90 μm, most preferably not less than 50 μm and not more than 70 μm. When the thickness of the buffer layer 120 is more than the said lower limit, the fall of the cushioning property of the release film 100 can be suppressed. When the thickness of the buffer layer 120 is below the said upper limit, the fall of mold release property can be suppressed.

＜Manufacturing method of release film＞ The release film 100 of this embodiment can be manufactured by methods, such as a co-extrusion method and an extrusion lamination method. Hereinafter, it demonstrates taking the manufacturing method of the release film which provided the 1st release layer and provided the buffer layer on this 1st release layer as an example.

In the co-extrusion method, the release film 100 is manufactured by extruding the release layer 110 and the buffer layer 120 simultaneously by using a feed block, a multi-manifold die. In addition, in the co-extrusion method, as shown in FIG. 3, the melt M after passing through the die 210 is guided by the first roller 230, and is cooled by the first roller 230 until it is released from the first roller 230, and becomes a melted material. Molding film 100. Then, the release film 100 is conveyed to the downstream side in the film conveying direction (refer to the arrow in FIG. 3 ) by the second roller 240 , and finally wound up by a take-up roller (not shown). At this time, the temperature of the first roller 230 is preferably 30-100° C., and the peripheral speed ratio of the first roller 230 relative to the second roller 240 is preferably 0.990-0.998. In addition, if necessary, a contact roll may be arranged near the first roll.

In the extrusion lamination method, the release layer 110 is extruded by setting the temperature of the barrel of the extruder at 225-250° C., so that the release layer 110 and the buffer layer 120 merge, so that the release layer 110 and The buffer layer 120 is laminated to manufacture the release film 100 . In addition, in the extrusion lamination method, as shown in FIG. 3 , the melt M of the mold release layer forming resin after passing through the mold 210 is guided by the first roll 230 and cooled by the first roll 230 until it passes through the first roll 230. It becomes the release layer film F until detachment. Then, the release layer film F is conveyed to the downstream side in the film conveying direction (refer to the arrow in FIG. 3 ) by the second roller 240 . Furthermore, the melt (not shown) of the resin blend forming the buffer layer 120 merges with the release layer film F conveyed to the downstream side in the film conveying direction, and is integrated with the release layer film F to manufacture a release layer. Film 100. Moreover, the release film 100 manufactured in this way is wound up by the winding-up roller (not shown) provided in the downstream side of a film conveyance direction further. At this time, the temperature of the first roller 230 is preferably 30-100° C., and the peripheral speed ratio of the first roller 230 relative to the second roller 240 is also preferably 0.990-0.998. In addition, if necessary, a contact roller can be arranged near the first roller.

＜Manufacturing method of molded product＞ Next, an example of the manufacturing method of the molded article of this embodiment is demonstrated. As a molded product, a flexible printed circuit board (FPC) is mentioned, for example. The manufacturing method of the flexible printed circuit board includes the following steps: on the surface of the cover layer film, the step of disposing the release layer 110 of the release film 100 on it in a manner of abutting against the surface; A step of heating and pressing the release film 100 together; and a step of peeling the release film 100 from the cover film. That is, in order to protect the circuit formed on the flexible film, the release film 100 is interposed between the cover layer and the pressing machine when the cover layer film is heated and pressed to closely bond the circuit. More specifically, as shown in FIG. 4 , after sandwiching a product 340 that temporarily fixes both the circuit exposure film and the CL film with an adhesive agent so as to face the release layer 110 of the release film 100 , according to Insert Teflon (registered trademark) plate 330, rubber pad 320 and stainless steel plate 310 in sequence, and press with hot plate 300 (see the hollow arrow in Figure 4). Thereby, a flexible printed circuit board in which the CL film was closely bonded to the circuit-exposing film was obtained.

In addition, as a heating method by the hot plate 300, it is as shown in FIG. That is, after 15 minutes elapsed from the start of pressurization, the hot plate 300 was heated from normal temperature to 195° C., and then maintained at that temperature for 35 minutes. Then, the hot plate 300 was cooled from 195° C. to normal temperature over 50 minutes. Also, the pressurization by the hot plate 300 starts at 0 minutes and ends at 100 minutes. The pressing pressure can be properly adjusted between 5 and 15 MPa.

＜Applications of Release Film＞ The release film 100 of the present invention has the characteristics of improving the operability of press mounting and improving the yield rate of FPC, etc., and is particularly effective as a release film that adheres a CL film to a circuit by pressurization When the film is exposed, the CL film is used to cover the cover layer film so that the CL film can be closely adhered to the unevenness of the circuit pattern.

Also known as release films are (1) used in the manufacture of laminated boards, (2) used in the manufacture of front-end composite products, (3) used in the manufacture of sports and leisure products, The release film 100 also has its function as the release film. In addition, the so-called (1) release film used in the manufacture of laminated boards refers to the film used to prevent the adhesion between the printed board and the partition board or other printed boards during the press molding when manufacturing the multilayer printed board. A thin film interposed between them. In addition, (2) The mold release film used in the manufacture of front-end composite products refers to, for example, those used in the manufacture of various products by curing prepregs made of glass cloth, carbon fibers, aramid fibers, and epoxy resins. film. Also, (3) release film used in the manufacture of sports and leisure products means, for example, in the manufacture of fishing rods, golf club shafts, windsurfing poles, etc., prepregs are wound into a cylindrical shape And the film wound on the prepreg when it is cured in an autoclave.

The release film 100 is also effective in applications such as adhesive tapes, double-sided tapes, masking tapes, labels, seals, stickers, and wet cloths for skin sticking.

Furthermore, the release film 100 is also effective as a process film used in the manufacture of printed circuit boards, ceramic electronic parts, thermosetting resin products, cosmetic boards, and the like. In addition, the process film mentioned here refers to sandwiching between metal plates or between resins during the molding step to prevent A film in which the metal plates or the resins are bonded to each other. In particular, it refers to those suitable for use in the manufacture of laminated boards, in the manufacture of flexible printed circuit boards, in the manufacture of front-end composite products, and in the manufacture of sports and leisure products.

(Second Embodiment) The release film of the second embodiment has a first release layer made of a thermoplastic resin material on one surface, and has a cushion layer containing polypropylene on the first release layer, and the release film satisfies the following conditions. Conditions: In the DSC curve C1 obtained by measuring the release film at a heating rate of 5°C/min with a differential scanning calorimeter, P1 (mJ/mg) represents "from 140°C to 170°C The heat of fusion obtained from the endothermic peak of polypropylene within the temperature range" After obtaining the DSC curve C1, cool at 50°C/min until the temperature in the differential scanning calorimeter reaches 25°C, and heat again In the DSC curve C2 obtained by measuring with a differential scanning calorimeter at a rate of 5°C/min, P2 (mJ/mg) represents "endothermic heat from polypropylene in the temperature range from 40°C to 170°C When the heat of fusion obtained by the peak is obtained, the ratio of the values of P1 and P2 (P1/P2) is greater than 1.

Hereinafter, the mold release film of 2nd Embodiment is demonstrated in detail, Focusing on the point which differs from the said 1st Embodiment, it demonstrates. Matters not described can be considered to be the same as those of the first embodiment.

Here, P1 (mJ/mg) of this condition refers to the heat (mJ/mg) calculated from the endothermic peak area in the so-called 1stRUN, and P2 (mJ/mg) refers to the calorie (mJ/mg) obtained in the so-called 2ndRUN. Calorie (mJ/mg) calculated from the endothermic peak area. Here, it is known that in differential scanning calorimetry, molecules become disorganized and uncrystallized by heating above the melting point in 1stRUN, so in 2ndRUN, the thermal properties of the substance itself can be obtained. In the present invention, by controlling (P1/P2) in the release film 100 to be greater than 1 in the temperature range of 140°C to 170°C, appropriate followability can be obtained, and the release can be suppressed in use. Penetration of the buffer layer 120 occurs when the film is thin, and the release property and heat resistance are improved. The details of this mechanism are not clear, but by setting P1 of 1stRUN in the release film 100 higher than P2 of 2ndRUN, the crystallinity of the molecules in the buffer layer 120 of the release film 100 can be increased, thereby enabling It is presumed that the rigidity of the release film 100 is improved, and as a result, appropriate followability is obtained, and the permeation of the cushion layer 120 is suppressed, thereby obtaining good release properties and heat resistance. In addition, when the release film 100 is used for hot pressing, it is crystallized at 140 to 170° C., and then peeled from the FPC at 140 to 170° C., whereby better release properties can be obtained. In addition, the heat resistance of the release film 100 of the present invention means that softening is suppressed by heating and pressing, and the release film 100 is less prone to wrinkles. Thereby, generation|occurrence|production of wrinkles in FPC at the time of manufacture using the mold release film 100 is suppressed, and external appearance can be made favorable.

In addition, the upper limit of (P1/P2) is not particularly limited, but is preferably 3 or less from the viewpoint of obtaining appropriate followability.

In addition, (P1/P2) in this invention means the value measured by the following procedure using a differential scanning calorimeter (DSC). That is, firstly, the materials and standard substances for forming the mold release film 100 are supplied to the differential scanning calorimeter, the temperature is raised to 250° C. at a heating rate of 5° C./min, and the temperature is lowered from 250° C. to 25° C. at a rate of 50° C./min. °C (1st RUN). Then, the temperature was raised to 250° C. at a heating rate of 5° C./minute again, and the temperature was lowered from 250° C. to 25° C. at a rate of 50° C./minute (2nd RUN). The heat of fusion (mJ/mg) was calculated from the endothermic peak at 140-170°C of the obtained DSC curve.

In order for the release film 100 to satisfy the above conditions, the present inventors found that it is necessary to study a manufacturing method different from the conventional one. Specifically, it is important to appropriately combine and adjust the following conditions. (i) Selection and combination of materials for the release film 100 (ii) Formation conditions of the release film 100

Regarding the material of the release film 100 in (i) above, it is important to select and combine the materials of the release layer 110 and the buffer layer 120 described later. Among them, regarding the material of the buffer layer 120 , it is more important to combine the materials described later and properly adjust the blending amount according to the materials. In addition to the above (i), the above-mentioned conditions can also be satisfied by controlling the film-forming conditions of the release film of the above-mentioned (ii). As film-forming conditions of the said (ii) release film 100, factors, such as film-forming temperature, extrusion speed, and cooling treatment conditions, are mentioned, for example. For example, the film-forming temperature and extrusion speed were set according to the type of resin material forming the release film 100, and the presence or absence of cooling treatment was studied. When the cooling treatment is performed, various factors such as the selection of the cooling treatment method, the cooling temperature, and the cooling treatment speed are further combined and controlled. In addition, the release film 100 formed by the method described below is usually rolled up after being pressed on a cooled metal roll with a contact roll or an air knife, and the temperature during pressing on the cooled metal roll can also be controlled. In addition, the cooling temperature is preferably set to a temperature higher than 50°C and lower than 90°C, and the cooling processing rate is preferably set to be higher than 50°C/s and lower than 60°C/s.

(The buffer layer) In the second embodiment, unlike the first embodiment, the buffer layer only needs to contain polypropylene. As the resin material for forming the buffer layer 120, in addition to the above-mentioned polypropylene, for example, α-olefin polymers other than polypropylene, ethylene, propylene, butene, pentene, hexene, methylpentene, etc. Engineering plastic resins such as α-olefin-based copolymers, polyether sulfide, and polyphenylene sulfide as polymer components. These can be used alone or in combination. Among them, α-olefin-based copolymers are preferred. Examples of the α-olefin-based copolymers include copolymers of α-olefins such as ethylene and (meth)acrylate, copolymers of ethylene and vinyl acetate, copolymers of ethylene and (meth)acrylic acid, and Part of its ion cross-linked products and so on. Furthermore, from the viewpoint of obtaining good cushioning function, stain resistance, releasability, and heat resistance, polypropylene alone, a mixture of polypropylene and an α-olefin-(meth)acrylate copolymer, or polypropylene The mixture with polybutylene terephthalate and the mixture of polypropylene and 1,4-cyclohexanedimethanol copolymerized polyethylene terephthalate are preferred. Among them, the mixture of polypropylene and ethylene-methyl methacrylate copolymer (EMMA), polypropylene, polybutylene terephthalate, and ethylene- A mixture of methyl methacrylate copolymers, a mixture of polypropylene, polybutylene terephthalate, and ethylene, etc. are more preferable.

In addition, the buffer layer 120 of the second embodiment is the same as the buffer layer of the first embodiment, and may contain rubber components, antioxidants, slip agents, anti-blocking agents, antistatic agents, coloring agents such as dyes and pigments, Additives such as stabilizers, impact resistance imparting agents such as fluororesin and silicone rubber, inorganic fillers such as titanium oxide, calcium carbonate, and talc.

＜Manufacturing method of release film＞ As described above, the release film 100 of the second embodiment controls the film-forming conditions in order to satisfy the specific conditions of the present invention. As a formation method of the release film 100, well-known methods, such as a co-extrusion method, an extrusion lamination method, a dry lamination method, and a blow molding method, can be utilized and can manufacture. In addition, when the release film has a multi-layer structure, the release layer and the buffer layer may be joined by a laminator after each layer is manufactured separately, but the air-cooled or water-cooled co-extrusion blow molding method, co-extrusion It is better to form a film by T-die method. Among them, the method of forming a film by the co-extrusion T-die method is particularly preferable from the viewpoint of being advantageous for thickness control of each layer. In addition, the mold release layer 110 and the buffer layer 120 may be joined directly, or may be joined via an adhesive layer.

In the co-extrusion method, the release film 100 is manufactured by simultaneously extruding the release layer 110 and the buffer layer 120 using a feedblock, multi-manifold die. In addition, in the co-extrusion method, as shown in FIG. 3 , the melt M after passing through the mold 210 is guided by the first roller 230, and is cooled by the first roller 230 until it is released from the first roller 230, and becomes Release film 100. Then, the release film 100 is conveyed to the downstream side in the film conveying direction (see the arrow in FIG. 3 ) by the second roller 240 , and finally wound up by a take-up roller (not shown). At this time, the temperature of the first roller 230 is preferably 30-100° C., and the peripheral speed ratio of the first roller 230 relative to the second roller 240 is preferably 0.990-0.998. In addition, a contact roller can also be arranged near the first roller as required.

In the extrusion lamination method, the release layer 110 is extruded by setting the temperature of the barrel of the extruder at 225-250° C., so that the release layer 110 and the buffer layer 120 merge to form the release layer 110 and The buffer layer 120 is laminated to manufacture the release film 100 . In addition, in the extrusion lamination method, as shown in FIG. 3 , the melt M of the mold release layer forming resin after passing through the mold 210 is guided by the first roller 230 and cooled by the first roller 230 until it passes through the first roller 230. 230, and become the release layer film F. Then, the release layer film F is conveyed to the downstream side in the film conveying direction (refer to the arrow in FIG. 3 ) by the second roller 240 . Furthermore, the melt (not shown) of the resin blend that forms the buffer layer 120 merges with the release layer film F that is conveyed to the downstream side in the film conveying direction, and is integrated with the release layer film F to manufacture a release layer. Film 100. In addition, the release film 100 manufactured in this way is wound up by the winding-up roll (not shown) provided in the film conveyance direction downstream side further. At this time, the temperature of the first roller 230 is preferably 30-100° C., and the peripheral speed ratio of the first roller 230 relative to the second roller 240 is also preferably 0.990-0.998. In addition, a contact roller can also be arranged near the first roller as required.

Below, an example of the reference form is attached. 1. A release film, which has (A) a first release layer made of thermoplastic resin material on one surface, and has a buffer layer on the first release layer, and the buffer layer contains (B1) polyterephthalic acid Butylene glycol ester (PBT), (B2) polypropylene and (B3) ethylene-methyl methacrylate copolymer (EMMA). 2. The release film as described in 1., the content ratio of the component (B1), component (B2) and component (B3) in the buffer layer {(B1):(B2):(B3)} is 5～ 50: 5-50: 20-70. 3. The release film according to 1. or 2., wherein the ethylene-methyl methacrylate copolymer (EMMA) contains a unit derived from methyl methacrylate in an amount of not less than 5% by mass and not more than 20% by mass. 4. The release film according to any one of 1. to 3., wherein the first release layer contains polybutylene terephthalate (PBT). 5. The release film as described in any one of 1. to 4., which further has a second release layer made of a second thermoplastic resin material on the other side of the release film, and the first release layer is laminated sequentially. A release layer, the buffer layer and the second release layer. 6. A method of manufacturing a flexible printed circuit board, comprising: On the surface of the cover layer film, the step of arranging the first release layer of the release film described in any one of 1. to 5. in such a manner as to be in contact with the surface; the step of heat pressing both the cover layer film and the release film together; and A step of peeling the release film from the cover film.

Below, an example of the reference form is attached. 1. A release film having a first release layer made of a thermoplastic resin material on one surface and a buffer layer containing polypropylene on the first release layer, the release film satisfying the following conditions. Conditions: In the DSC curve C1 obtained by measuring the release film at a heating rate of 5°C/min with a differential scanning calorimeter, P1 (mJ/mg) represents "from 140°C to 170°C The heat of fusion obtained from the endothermic peak of polypropylene within the temperature range", and after obtaining the DSC curve C1, it is cooled at 50°C/min until the temperature in the differential scanning calorimeter becomes 25°C. In the DSC curve C2 obtained by setting the heating rate at 5°C/min and measuring with a differential scanning calorimeter, P2 (mJ/mg) represents "from polypropylene in the temperature range of 140°C to 170°C When the heat of fusion obtained from the endothermic peak is ", the ratio of the values of P1 and P2 (P1/P2) is greater than 1. 2. The release film according to 1., wherein the first release layer contains polybutylene terephthalate (PBT). 3. The release film according to 1. or 2., wherein the buffer layer contains an α-olefin copolymer. 4. The release film according to any one of 1. to 3., further comprising a second release layer made of a second thermoplastic resin material on the other surface of the release film. 5. A method for manufacturing a flexible printed circuit board, comprising: abutting the first release layer of the release film described in any one of 1. to 4. on the surface of the cover film The way to configure the steps on it; the step of heat pressing both the cover layer film and the release film together; and A step of peeling the release film from the cover film. [Example]

Hereinafter, although an Example and a comparative example demonstrate this invention, this invention is not limited to these.

[Example 1 to Example 4, Comparative Example 1 to Comparative Example 3] First, the release films of Examples 1 to 4 and Comparative Examples 1 to 3 were produced and evaluated. The details are described below.

(Example 1) ＜Manufacture of release film＞ (1) Raw materials for the first release layer As a raw material for the first release layer, polybutylene terephthalate/polytetramethylene glycol block copolymer (polybutylene terephthalate constituting unit/polytetramethylene glycol constituting unit 90 parts by weight/10 parts by weight) (NOVADURAN (registered trademark) 5505S manufactured by Mitsubishi Engineering-Plastics Corporation).

(2) Raw material of buffer layer As raw materials for the buffer layer, 10% by weight of polybutylene terephthalate (indicated as PBT in Table 1.) (manufactured by Mitsubishi Engineering-Plastics Corporation, product name 5505S), 50% by weight of polypropylene (in Table 1 Marked as PP.) (manufactured by Sumitomo Chemical Co., Ltd., NOBLENE (registered trademark) FH1016: MFR0.5g/10min), 40% by weight of ethylene-methyl methacrylate copolymer (methyl methacrylate derived unit Content: 5.8% by weight, indicated as EMMA1 in Table 1.) (manufactured by Sumitomo Chemical Co., Ltd., ACRYFT (registered trademark) WD106).

(3) Raw materials for the second release layer The raw material of the 2nd release layer uses the same raw material as the 1st release layer.

＜Production of release film＞ Using the co-extrusion method, a release film with a first release layer and a second release layer on the surface and back of the buffer layer is produced (see Figure 2).

In addition, specifically, polybutylene terephthalate/polytetramethylene glycol block copolymer, modified polyethylene, ethylene-methyl methacrylate, etc. Blends of copolymers and polypropylene and polypropylene to make release films. At this time, the device shown in FIG. 3 was used, and the temperature of the first roller 230 was 30°C.

In this release film, the thickness of the first release layer was 30 μm, the thickness of the buffer layer was 60 μm, and the thickness of the second release layer was 30 μm.

(Example 2) The blending amounts of PBT, PP, and EMMA1 in the buffer layer were changed to those shown in Table 1. Except for this, the release film was produced in the same manner as in Example 1.

(Example 3) The blending amounts of PBT, PP, and EMMA1 in the buffer layer were changed to those shown in Table 1. Except for this, the release film was produced in the same manner as in Example 1.

(Example 4) The blending amounts of PBT, PP, and EMMA1 in the buffer layer were changed to those shown in Table 1, and 30% by weight of ethylene-methyl methacrylate copolymer was used (content of methyl methacrylate derived units: 20% by weight , indicated as EMMA2 in Table 1.) (manufactured by Sumitomo Chemical Co., Ltd., ACRYFT (registered trademark) WH206-F). Except for this, the release film was produced in the same manner as in Example 1.

(comparative example 1) The blending amounts of PBT, PP, and EMMA1 in the buffer layer were changed to those shown in Table 1. Except for this, the release film was produced in the same manner as in Example 1.

(comparative example 2) The blending amounts of PBT, PP, and EMMA1 in the buffer layer were changed to those shown in Table 1. Except for this, the release film was produced in the same manner as in Example 1.

(comparative example 3) The blending amounts of PBT, PP, and EMMA1 in the buffer layer were changed to those shown in Table 1. Except for this, the release film was produced in the same manner as in Example 1.

The following evaluation was performed using the obtained release film. The results are shown in Table 1.

･Releasability First, a test film was produced in such a way that "the surface of the cover layer (CEA type) manufactured by Arisawa Manufacturing Co., Ltd. on which the adhesive is applied is in contact with the surface of the film where the circuit is exposed" Temporary fixation of the overlay. Next, make the first release surface of the first release layer in the release film adhere to each other in such a way that "the surface of the test film with the cover layer faces" and adhere in this way. The resultant was used as a test piece. Next, the test piece was subjected to hot pressing treatment at 195° C. and 3 MPa for 2 minutes, and then tested in the 180° direction at approximately At a speed of 1000 mm/min, the first release surface of the first release layer of the above-mentioned release film and the cover layer of the above-mentioned test film were peeled off each other, and the peel strength (N/50mm) was measured. If the peel strength is too high, either the test piece or the release film will be broken, and proper measurement cannot be performed. The smaller the peel strength (N/50mm), the better the releasability.

･High temperature followability (bleeding of adhesive) A covering layer (CEA type) made by Arisawa Manufacturing Co., Ltd. consisting of a polyimide film and an epoxy resin adhesive layer was used. Here, the cover film was punched with a window corresponding to the terminal portion of the printed wiring substrate, and the size of the punched portion was 50 mm×50 mm. This coverlay film was laminated|stacked on the 50-micrometer-thick copper foil, and the surface of the 1st release layer of a release film was made to overlap the coverlay film side, and it attached to the heating press machine. It was heated and pressed at 195° C., 3 MPa, for 2 minutes, the press plate was opened and cooled, and the release film was peeled off from the copper foil to which the cover layer film was bonded. The length of the epoxy adhesive component in the part where the epoxy resin adhesive oozes out from the edge of the coverlay film was observed and measured from the top of the film surface with an optical microscope. In this measurement, two points are measured for each of the four sides of the edge portion of the cover film, and the average value thereof is set as the "adhesive bleed length of the cover film (μm)". The shorter the exudation length (μm) of the adhesive of the cover film, the better the followability.

･Pollution resistance The release film (70mm x 70mm in size) is superimposed on the copper foil (100mm x 100mm in size) with a thickness of 50μm, and then clamped on the outside with an aluminum plate and a SUS plate, and installed in a heating press. After heating and pressing at 195°C, 3 MPa, and 2 minutes, releasing the pressing pressure and cooling, the length of the buffer layer component exuded from the end of the release film was observed and measured from the top of the film surface with an optical microscope. In this measurement, two points were measured for each of the four sides of the release film, and the average value thereof was used as the oozing length (μm) of the buffer layer component from the end of the multilayer release film. The shorter the exudation length (μm) of the buffer layer components from the end of the release film, the less contamination and the better the stain resistance.

[Table 1] Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 Comparative example 3 Cushion layer for release film PBT 10 30 40 30 0 20 20 PP 50 10 20 40 30 0 80 EMMA1: WD106 (MMA5.8%) 40 60 40 0 70 80 0 EMMA2: WH206-F (MMA20%) 0 0 0 30 0 0 0 Evaluation Release property: peel strength (N/50mm) 2.2 2.5 1.9 1.7 3.3 3.1 1.3 High temperature followability: the oozing length of the adhesive of the covering film (μm) 68 63 85 88 45 53 128 Pollution resistance: seepage length of buffer layer components (μm) 410 440 380 350 790 530 310

As shown in the above Table 1, compared with the release films of Comparative Examples 1 to 3, it was confirmed that the release films of Examples 1 to 4 can improve the release properties and followability in a high balance.

･Plating layer adhesion Moreover, the adhesion of the plating layer was evaluated using the release films of Examples 1 to 4. According to the appearance of the electroplating layer in item 6.3.4 of the JPCA standard (more than 90% of the area of the necessary electroplating layer is adhered to the electroplating layer, it is considered good), and the adhesion of the electroplating layer of 100 pieces of FPC made with a release film is evaluated. The following ○× were used as evaluation criteria. ○: 98 or more out of 100 good products in which the plating layer adhered to 90% or more of the required plating layer area. ×: The number of good products with plating layer adhered to 90% or more of the required plating layer area is less than 98 out of 100. As a result of the evaluation, it was confirmed that the evaluation results of the plating layer adhesion of the release films of Examples 1 to 4 were all "◯".

[Example 5-Example 6, Comparative Example 4-Comparative Example 5] Next, the release films of Examples 5 to 6 and Comparative Examples 4 to 5 were prepared and evaluated. The details are described below.

(Example 5) ＜Manufacture of release film＞ (1) Raw materials for the first release layer As a raw material of the first release layer, polybutylene terephthalate (PBT: manufactured by Mitsubishi Engineering-Plastics Corporation, product name 5505S) was used.

(2) Raw material of buffer layer As raw materials for the buffer layer, 20% by weight of polybutylene terephthalate ("PBT" in Table 2: manufactured by Mitsubishi Engineering-Plastics Corporation, product name 5505S), and 20% by weight of polypropylene ("PBT" in Table 2) were used. PP": manufactured by Sumitomo Chemical Co., Ltd., NOBLENE (registered trademark) D101: MFR0.5g/10min), 60% by weight ethylene-methyl methacrylate copolymer ("EMMA" in Table 2: methyl Methyl acrylate derived unit content: 5.8% by weight) (manufactured by Sumitomo Chemical Co., Ltd., ACRYFT (registered trademark) WD106).

(3) Raw materials for the second release layer As a raw material of the 2nd release layer, the same raw material as the 1st release layer was used.

＜Production of release film＞ A release film with a first release layer and a second release layer on the surface and back of the buffer layer is produced by co-extrusion (see Figure 2).

Specifically, polybutylene terephthalate/polytetramethylene glycol block copolymer, modified polyethylene, ethylene-methyl methacrylate copolymer were simultaneously extruded using a feed block, multi-manifold die Blended with polypropylene and polybutylene terephthalate/polytetramethylene glycol block copolymer to make release film. At this time, the device shown in FIG. 3 was used, the line speed was 45 m/min, and the temperature of the first roller 230 was 90° C.

In this release film, the first release layer had a thickness of 25 μm, the buffer layer had a thickness of 65 μm, and the second release layer had a thickness of 30 μm.

(Example 6) As raw materials for the buffer layer, 20% by weight of polybutylene terephthalate (manufactured by Mitsubishi Engineering-Plastics Corporation, product name 5505S), 20% by weight of polypropylene (manufactured by Sumitomo Chemical Co., Ltd., NOBLENE (registered trademark) ) FS2011DG2: MFR2.5g/10min), 60% by weight of 1,4-cyclohexanedimethanol copolymer polyethylene terephthalate ("PETG" in Table 2: SK Chemicals., SKYGREEN PETG S2008). Except for this, a release film was produced in the same manner as in Example 5.

(comparative example 4) As raw materials for the buffer layer, 20% by weight of polybutylene terephthalate (manufactured by Mitsubishi Engineering-Plastics Corporation, product name 5505S), 80% by weight of ethylene-methyl methacrylate copolymer (methyl methacrylate derived Unit content: 5.8% by weight) (manufactured by Sumitomo Chemical Co., Ltd., ACRYFT (registered trademark) WD106). Except for this, a release film was produced in the same manner as in Example 5.

(comparative example 5) In Example 5, the line speed was set to 30 m/min, and the temperature of the first roller 230 was set to 30°C. Except for this, a release film was produced in the same manner as in Example 5.

Using the obtained release films of Examples 5 to 6 and Comparative Examples 4 to 5, the following evaluations were performed. The results are shown in Table 2.

･Measurement by Differential Scanning Calorimeter (DSC) Supply the materials and standard substances that form the release film 100 into the differential scanning calorimeter, raise the temperature to 250°C at a heating rate of 5°C/min, and cool down from 250°C to 25°C at a rate of 50°C/min (1stRUN) . Then, the temperature was raised to 250°C again at a heating rate of 5°C/min, and the temperature was lowered from 250°C to 25°C at a rate of 50°C/min (2nd RUN) to obtain a DSC curve. From the obtained DSC curve, the heat of fusion P1 (mJ/mg) obtained from the endothermic peak derived from polypropylene in the temperature range above 140°C and below 170°C was calculated for 1stRUN, and calculated from 170°C for 2ndRUN The heat of fusion P2 (mJ/mg) obtained from the endothermic peak of polypropylene in the temperature range below °C.

･Releasability First, a test film was produced in such a way that "the surface of the cover layer (CEA type) manufactured by Arisawa Manufacturing Co., Ltd. on which the adhesive is applied is in contact with the surface of the film where the circuit is exposed" Temporary fixation of the overlay. Next, the release surfaces of the first release layer in the release film are bonded to each other in such a way that "the surface of the test film with the cover layer faces" and bonded in this way. as a test piece. Next, the test piece was subjected to hot pressing treatment at 195° C. and 3 MPa for 2 minutes, and then tested in the 180° direction at about At a speed of 1000 mm/min, both the release surface of the first release layer of the above-mentioned release film and the cover layer of the above-mentioned test film were peeled off, and the peel strength (N/50mm) was measured. If the peel strength is too high, either the test piece or the release film will be broken, and proper measurement cannot be performed. The smaller the peel strength (N/50mm), the better the releasability.

･High temperature followability (bleeding of adhesive) A covering layer (CEA type) made by Arisawa Manufacturing Co., Ltd. consisting of a polyimide film and an epoxy resin adhesive layer was used. A window corresponding to the terminal portion of the printed wiring base material was punched into the cover film, and the size of the punched portion was 50 mm×50 mm. This coverlay film was laminated|stacked on the 50-micrometer-thick copper foil, and the surface of the 1st release layer of a release film was made to overlap the coverlay film side, and it mounted in the heating press machine. It was heated and pressed at 195° C., 3 MPa, for 2 minutes, the press plate was opened and cooled, and the release film was peeled off from the copper foil to which the cover layer film was bonded. The length of the epoxy adhesive component in the part where the epoxy resin adhesive oozes out from the edge of the coverlay film was observed and measured from the top of the film surface with an optical microscope. In this measurement, two points are measured for each of the four sides of the edge portion of the cover film, and the average value thereof is set as the "adhesive bleed length of the cover film (μm)". The shorter the exudation length (μm) of the adhesive of the cover film, the better the followability.

･Pollution resistance The release film (70mm x 70mm in size) is superimposed on the copper foil (100mm x 100mm in size) with a thickness of 50μm, and then clamped with an aluminum plate and a SUS plate on the outside, and installed in a heating press. After heating and pressing at 195°C, 3 MPa, and 2 minutes, releasing the pressing pressure and cooling, the length of the buffer layer component exuded from the end of the release film was observed and measured from the top of the film surface with an optical microscope. In this measurement, two points were measured for each of the four sides of the release film, and the average value thereof was used as the oozing length (μm) of the buffer layer component from the end of the multilayer release film. The shorter the exudation length (μm) of the buffer layer components from the end of the release film, the less contamination and the better the stain resistance.

･Heat resistance (wrinkled appearance) In the evaluation of the releasability of the above-mentioned release film, the number of objects of wrinkles on the surface of the test piece (FPC) after peeling the release film was confirmed. The fewer wrinkles, the better the appearance of FPC.

[Table 2] (weight%) Example 5 Example 6 Comparative example 4 Comparative Example 5 Release film first release layer PBT 100 100 100 100 The buffer layer PBT 20 20 20 20 PP 20 20 20 EMMA 60 80 60 PETG 60 second release layer PBT 100 100 100 100 Evaluation P1 (mJ/mg) 16.2 9.84 - 13 P2 (mJ/mg) 15 7.77 - 13.3 P1/P2 1.08 1.27 - 0.98 Release property (N/50mm) 2.4 1.8 2.9 2.6 Followability (μm) 73 79 61 64 Pollution resistance (μm) 450 210 530 480 heat resistance (unit) 0 0 1 2

As shown in the above Table 2, compared with the release films of Comparative Examples 4 to 5, the release films of Examples 5 to 6 obtained good heat resistance, and at the same time, the release properties and followability were obtained in a high balance. , is confirmed. In addition, although Comparative Example 5 is inferior to Examples 5 to 6, it belongs to a release film that can improve release properties and followability in a highly balanced manner.

This application claims the priority of Japanese Patent Application No. 2017-55928 filed on March 22, 2017 and Japanese Patent Application No. 2017-67273 filed on March 30, 2017, and its disclosure content is fully incorporated here.

100,100A: release film 110: release layer 110a: the first release layer 110b: the second release layer 120: buffer layer 210: Mold 230: the first roller 240: Second roller 300: hot plate 310: stainless steel plate 320: rubber pad 330: Teflon board 340: Both the exposed film and the CL film are temporarily fixed with an adhesive F: release layer film

The above objects, as well as other objects, features and advantages, will be more clearly explained by the description of the preferred embodiments described below and the drawings attached thereto.

Fig. 1 is a longitudinal sectional view of an example of a release film according to this embodiment. Fig. 2 is a longitudinal sectional view of an example of the release film of the present embodiment. Fig. 3 is a diagram showing an example of a manufacturing apparatus of a release film according to an embodiment of the present invention. Fig. 4 is a diagram showing an example of the method of using the release film of the present embodiment. Fig. 5 is a diagram showing an example of a heating pattern of heat pressing when the release film of this embodiment is used to closely adhere the CL film to the concave-convex portion of the circuit pattern.

100: release film

110: release layer

120: buffer layer

Claims (6)

A release film, which has a first release layer made of a thermoplastic resin material on one surface, and has a buffer layer containing polypropylene on the first release layer, and the release film satisfies the following conditions, Conditions: In the DSC curve C1 obtained by measuring the release film at a heating rate of 5°C/min with a differential scanning calorimeter, P1 (mJ/mg) represents "from 140°C to 170°C The heat of fusion obtained from the endothermic peak of polypropylene within the temperature range"; and after obtaining the DSC curve C1, it was cooled at 50°C/min until the temperature in the differential scanning calorimeter was 25°C; In the DSC curve C2 obtained by setting the heating rate at 5°C/min and measuring with a differential scanning calorimeter, P2 (mJ/mg) represents "endotherm from polypropylene in the temperature range from 140°C to 170°C When the heat of fusion obtained by the peak is obtained, the ratio of the values of P1 and P2 (P1/P2) is greater than 1. Such as the release film of claim 1, wherein The buffer layer contains an α-olefin copolymer. Such as the release film of claim 1 or 2, wherein The thermoplastic resin material contains polybutylene terephthalate (PBT). Such as the release film of claim 1 or 2, wherein There is also a second release layer made of a second thermoplastic resin material on the other surface of the release film, and the first release layer, the buffer layer and the second release layer are stacked in sequence. Such as the release film of claim 1 or 2, wherein This release film is used for molding of flexible printed circuit boards. A method of manufacturing a flexible printed circuit board, comprising: On the surface of the cover layer film, the step of disposing the first release layer of the release film according to any one of claims 1 to 5 on the surface in a manner of abutting against the surface; the step of heat pressing both the cover layer film and the release film together; and A step of peeling the release film from the coverlay film.

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