JP2003012829A - Mold release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold release film excellent in heat resistance and releasability which can be easily disposable after use and used for production process of a printed wiring board, a flexible printed wiring board, multilayer printed wiring board or flexible printed board. SOLUTION: The film comprises a non-halogen-based cross-linked resin having a gel fraction determined by the following formula of 70% or more: gelation rate (%)=x/y×100 [wherein, (x) is a dry weight (g) of insoluble matters after immersion of a cross-linked resin for 24 hours in a solvent in which a resin before cross-linking completely dissolves, and (y) is a weight (g) of the cross- linked resin before immersion in the solvent].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film which is excellent in heat resistance and releasability and which can be easily discarded after use.

[0002]

2. Description of the Related Art In a manufacturing process of a printed wiring board, a flexible printed wiring board, a multilayer printed wiring board, etc., a release film is used when hot pressing a copper clad laminate or a copper foil through a prepreg or a heat resistant film. ing. Further, in the manufacturing process of the flexible printed circuit board, when the cover lay film is heat-pressed and bonded to the flexible printed circuit board body on which the electric circuit is formed by the thermosetting adhesive, the cover lay film and the press hot plate are bonded to each other. In order to prevent this, a method using a release film is widely used.

In recent years, in view of environmental problems and increasing social demands for safety, in addition to the functions such as heat resistance to withstand hot press molding and mold release for printed wiring boards and hot press plates, these release films have been added. , There is a growing demand for ease of disposal.

However, the polymethylpentene film, the silicone-coated polyester film, the fluorine-based film and the like which have been conventionally used as the release film do not fully satisfy the performance required for the release film. That is, the polymethylpentene film is inferior in heat resistance and insufficient in releasability, and the silicon-coated polyester film is inadequate in heat resistance and may transfer the silicon to impair the quality of products such as printed wiring boards. There is. Fluorine-based films are excellent in heat resistance and releasability, but they are expensive, and have problems that they are difficult to burn in waste incineration after use and generate toxic gas.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, it is an object of the present invention to provide a release film which is excellent in heat resistance and releasability and which can be easily discarded after use. .

[0006]

The present invention is a release film comprising a non-halogen cross-linking resin, wherein the non-halogen cross-linking resin has a gel fraction of 70% as determined by the following formula (1). The above is the release film.

[0007]

[Equation 2]

(In the formula, x represents the dry weight (g) of the insoluble matter after the crosslinked resin is immersed in a solvent which completely dissolves the resin before crosslinking for 24 hours, and y represents the crosslinked resin before immersion in the solvent. The present invention will be described in detail below.

The release film of the present invention (hereinafter, also referred to as the release film (I)) is made of a non-halogen cross-linking resin having a gel fraction of 70% or more calculated by the above formula (1). . If the gel fraction is less than 70%, the heat resistance to withstand hot press molding cannot be expressed, and the migration of non-crosslinking components may impair the quality of products such as printed wiring boards. It is preferably 85% or more. Further, since a non-halogen cross-linked resin is used, no toxic gas is generated when the release film (I) of the present invention is discarded.

The above-mentioned non-halogen type cross-linking resin has a gel fraction of 70% or more and fluorine, chlorine,
It is not particularly limited as long as it is a crosslinked resin having no halogen atom such as bromine, for example, epoxy resin, phenol resin,
Melamine resin; polyalkenyl compounds such as diallyl phthalate and trialkenyl isocyanurate; unsaturated polyester resin, urethane resin, silicone resin, modified silicone resin, polysulfide resin, modified polysulfide resin, polyfunctional (meth) acrylate resin, electron beam cross-linking type Examples include crosslinked olefin resins such as polypropylene, thermosetting polyimide resins such as bismaleimide triazine resins, thermosetting polyphenylene ethers, dicyclopentadiene and the like, which are crosslinked by respective crosslinking methods. These crosslinked resins may be used alone,
Two or more kinds may be used in combination.

The above-mentioned thermosetting polyimide resin is a resin having an imide bond in the polymer main chain, for example, a condensation polymer of aromatic diamine and aromatic tetracarboxylic acid, aromatic diamine and bismaleimide. And a bismaleimide triazine resin composed of a dicyanate compound and a bismaleimide resin, and the like.

Among the above non-halogen type cross-linking resins,
A cross-linked epoxy resin is preferably used. However, the epoxy resin preferably used in the present invention has at least one oxirane ring. The number of epoxy groups in the epoxy resin is preferably 1 or more per molecule, and more preferably 2 or more per molecule. Here, the number of epoxy groups per molecule is obtained by dividing the total number of epoxy groups in the epoxy resin by the total number of molecules in the epoxy resin.

At least one epoxy resin is used.
There is no particular limitation as long as it has one oxirane ring, and examples thereof include bisphenol-type epoxy resins such as bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol AD-type epoxy resin, and bisphenol S-type epoxy resin; phenol novolac type Epoxy resin, novolak type epoxy resin such as cresol novolac type epoxy resin; aromatic epoxy resin such as trisphenolmethane triglycidyl ether and hydrogenated products thereof; 3,4-epoxycyclohexylmethyl-
3,4-epoxycyclohexanecarboxylate,
3,4-epoxy-2-methylcyclohexylmethyl 3,4-epoxy-2-methylcyclohexanecarboxylate, bis (3,4-epoxycyclohexyl) adipate, bis (3,4-epoxycyclohexylmethyl) adipate, bis (3 , 4-epoxy-6-methylcyclohexylmethyl) adipate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexanone-meta-dioxane, bis (2,3-epoxycyclopentyl) Alicyclic epoxy resin such as ether; 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol jig Ethers, diglycidyl ether of polypropylene glycol, 2 carbon atoms
Aliphatic epoxy resin such as polyglycidyl ether of a long chain polyol containing polyoxyalkylene glycol or polytetramethylene ether glycol containing 9, preferably 2 to 4 alkylene groups; phthalic acid diglycidyl ester, tetrahydrophthalic acid Glycidyl ester type epoxy resins such as diglycidyl ester, hexahydrophthalic acid diglycidyl ester, diglycidyl-p-oxybenzoic acid, salicylic acid glycidyl ether-glycidyl ester, dimer acid glycidyl ester, and hydrogenated products thereof; triglycidyl isocyanurate ,
N, N′-diglycidyl derivative of cyclic alkylene urea,
Glycidyl amine type epoxy resins such as N, N, O-triglycidyl derivatives of p-aminophenol and N, N, O-triglycidyl derivatives of m-aminophenol and hydrogenated products thereof; glycidyl (meth) acrylate;
Copolymers with radically polymerizable monomers such as ethylene, vinyl acetate and (meth) acrylic acid ester; unsaturated carbons of polymers mainly composed of conjugated diene compounds such as epoxidized polybutadiene or polymers of partially hydrogenated products thereof Epoxidized double bond; "polymer block mainly composed of vinyl aromatic compound" such as epoxidized SBS and "polymer block mainly composed of conjugated diene compound or polymer block of partially hydrogenated product thereof""Epoxidized unsaturated carbon double bond of a conjugated diene compound of a block copolymer having" in the same molecule; polyester resin having one or more (preferably two or more) epoxy groups per molecule A urethane-modified epoxy resin or polycaprolace in which a urethane bond or a polycaprolactone bond is introduced into the structure of each of the above epoxy resins Ton modified epoxy resin; in the various epoxy resins NBR, CTBN, polybutadiene, and a conventionally known various epoxy resins such as rubber modified epoxy resin containing a rubber component such as acrylic rubber. Among these, commercially available products include, for example, EHPE- manufactured by Daicel Chemical Industries, Ltd., which is an alicyclic epoxy resin.
3550 (softening temperature 71 ° C.) and the like. These epoxy resins may be used alone or in combination of two or more kinds.

The curing agent used for the above epoxy resin is not particularly limited, and conventionally known curing agents for various epoxy resins can be used. For example, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyoxy. Propylenediamine,
Chain-like aliphatic amines such as polyoxypropylenetriamine and derivatives thereof; menthenediamine, isophoronediamine, bis (4-amino-3-methylcyclohexyl)
Methane, diaminodicyclohexylmethane, bis (aminomethyl) cyclohexane, N-aminoethylpiperazine, 3,9-bis (3-aminopropyl) 2,4,8,
Cycloaliphatic amines such as 10-tetraoxaspiro (5,5) undecane and derivatives thereof; m-xylenediamine, α- (m / p aminophenyl) ethylamine, m-
Aromatic amines and their derivatives such as phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiethyldimethyldiphenylmethane, α, α′-bis (4-aminophenyl) -p-diisopropylbenzene; the above various amine compounds and succinic acid, Polyaminoamides and their derivatives synthesized from carboxylic acids such as adipic acid, azelaic acid, sebacic acid, dodecadioic acid, isophthalic acid, terephthalic acid, dihydroisophthalic acid, tetrahydroisophthalic acid, and hexahydroisophthalic acid; various amines mentioned above Compounds and their derivatives synthesized from a compound and a maleimide compound such as diaminodiphenylmethane bismaleimide; a ketimine compound synthesized from the above various amine compounds and a ketone compound, and its derivative Body; polyamino compound synthesized from the above various amine compounds and compounds such as epoxy compound, urea, thiourea, aldehyde compound, phenol compound, acrylic compound, N, N'-dimethylpiperazine, pyridine, picoline, benzyldimethyl Amine,
2- (dimethylaminomethyl) phenol, 2,4,6
-Tris (dimethylaminomethyl) phenol, 1,8
-Tertiary amine compounds such as diazabiscyclo (5,4,0) undecene-1, and derivatives thereof; 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2 -Imidazole compounds such as phenylimidazole and derivatives thereof; 1,3-bis (hydrazinocarboethyl) -5-isopropylhydantoin, 7,11-octadecadiene-1,18-dicarbohydrazide, eicosane diacid dihydrazide, adipine Hydrazide compounds such as acid dihydrazides and their derivatives; dicyandiamide and its derivatives; 2,4-diamino-6-vinyl-1,3
Melamine compounds such as 5-triazine and its derivatives; phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic acid anhydride, ethylene glycol bisanhydrotrimellitate, glycerol trisanhydrotrimellyte Tate, methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, nadic acid anhydride, methylnadic acid anhydride, trialkyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, 5- (2,5-
Dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, trialkyltetrahydrophthalic anhydride-maleic anhydride adduct,
Acid anhydrides such as dodecenyl succinic anhydride, polyazelaic anhydride, polydodecane dianhydride, chlorendic anhydride and the like; phenol novolac, o-cresol novolac, p-cresol novolak, t-butylphenol novolac, dicyclo Phenolic compounds such as pentadiene cresol and derivatives thereof; ionic compounds such as benzylsulfonium salt, benzylammonium salt, benzylpyridinium salt and benzylphosphonium salt having antimony hexafluoride, phosphorus hexafluoride, and boron tetrafluoride as counter anions Heat-latent cationic polymerization catalyst; non-ionic heat-latent cationic polymerization catalyst such as N-benzylphthalimide, aromatic sulfonic acid ester; antimony hexafluoride, phosphorus hexafluoride, boron tetrafluoride, etc. as counter anions Aromatic diazoni Salts, aromatic halonium salts, aromatic sulfonium salts and other onium salts; iron-allene complexes, titanocene complexes, arylsilanol-aluminum complexes and other organic metal complexes, and other ionic photolatent cationic polymerization initiators; nitro Benzyl ester, sulfonic acid derivative, phosphoric acid ester, phenolsulfonic acid ester,
Examples thereof include nonionic photolatent cationic polymerization initiators such as diazonaphthoquinone and N-hydroxyimide sulfonate. These curing agents may be used alone or in combination of two or more.

As the curing agent used for the epoxy resin,
Acid anhydride or its derivative, thermal latent cationic polymerization catalyst,
When a photolatent cationic polymerization catalyst is used, polyhydroxyalkane, alkylene glycol, carbon number of 2 to
Long-chain polyols containing polyoxyalkylene glycols, polytetramethylene ether glycols, etc. containing 9, preferably 2-4 alkylene groups, hydroxyl-terminated polyalkadienes, hydroxyl-terminated polyesters, hydroxyl-terminated polycaprolactones, hydroxyl-terminated polycarbonates, Acrylic polyol, (partial) saponified product of ethylene-vinyl acetate copolymer, polyvinyl alcohol, castor oil, ketone resin, xylene resin, and aliphatic hydroxyl group-containing compounds such as copolymers and modified compounds of these aliphatic hydroxyl group-containing compounds The compounds can also be used as co-crosslinking agents.

If desired, other resins may be used in combination with the non-halogen crosslinking resin. Further, the non-halogen cross-linking resin includes a reinforcing material, a thixotropic agent, a stabilizer, an antioxidant, a flame retardant, an antistatic agent, a foaming agent, a slip agent, an antiblocking agent, a coloring agent such as a dye or a pigment. One or more of various additives such as inorganic fillers such as titanium oxide, calcium carbonate, and talc may be contained.

The release film (I) of the present invention has a thickness of 5
˜300 μm is preferred. If it is less than 5 μm, the strength tends to be insufficient, and if it exceeds 300 μm,
The thermal conductivity during hot press molding may deteriorate. More preferably, it is 25 to 100 μm.

The surface of the release film (I) of the present invention preferably has smoothness, but may have slip properties, anti-blocking properties and the like necessary for handling, and air release during hot press molding. For this purpose, an appropriate embossed pattern may be provided on at least one surface.

The release film (I) of the present invention is prepared by forming a resin before crosslinking, which is mixed with a curing agent, by a conventional film forming method such as a solution casting method, a room temperature coating method, a melt coating method, and the like. It can be produced by cross-linking by a cross-linking method according to the cross-linking resin.

The mixing method of the resin before crosslinking and the curing agent thereof is not particularly limited, and a commonly used mixing method can be used. For example, homodispers, homomixers, universal mixers, planetarium mixers, kneaders, three Examples include a method of uniformly mixing a predetermined amount of each component to be blended at room temperature or under heating using a mixer such as the present roll. Further, the above-mentioned mixing may be carried out without a solvent, or may be carried out in an inert solvent such as aromatic hydrocarbon, acetic ester, ketone or the like.

The solution casting method is not particularly limited, and for example, a solution of a resin before crosslinking which is dissolved in a solvent and a curing agent thereof is applied onto a support such as a metal endless belt or a smooth resin film. After the working, a method of uniformly heating and drying the coating film to form a film may be used. Also,
The solution casting method may be a solid printing method. The solvent used for dissolving the resin before crosslinking and the curing agent therefor may be any solvent capable of dissolving the resin before crosslinking and the curing agent therefor, and is appropriately selected according to the resin before crosslinking and the curing agent therefor. Used together, and two or more kinds may be used in combination.

The coater for applying the above solution is appropriately selected according to the properties such as the coating thickness and the viscosity of the solution. For example, a normal coater such as a comma coater, a roll coater, or a die coater. A coater is mentioned.

The method for drying the coating film coated on the above-mentioned support is not particularly limited, and a commonly used drying method can be used, but infrared heating is used because the coating film can be uniformly heated and dried. The drying method according to is preferred.

The mixture of the resin before cross-linking and its curing agent may be applied as it is to form a film, not as a solution. In this case, as a coater to apply,
It is appropriately selected according to properties such as coating thickness and viscosity of the mixture, and examples thereof include ordinary coating coaters such as a comma coater, a roll coater, and a die coater. Also,
If the cross-linked resin before cross-linking is solid or semi-solid at room temperature, or if it is liquid and has high viscosity and coating is difficult, heat-melt it to the extent that cross-linking does not occur, and then coat in that state. You can go.

When the method of crosslinking the crosslinked resin is heating,
Heating is performed at a predetermined temperature for a predetermined time by a conventionally known heating method such as an infrared heater, a warm air heater, a heat press, and a heat roll.

When the crosslinking method of the crosslinked resin is light irradiation or electron beam irradiation, a predetermined amount of light or electron beam having a predetermined wavelength is irradiated by a conventionally known light irradiation method or electron beam irradiation. Moreover, you may heat as needed. When the photolatent cationic polymerization catalyst is used as a curing agent, ultraviolet rays, which are particularly easy to handle and can obtain relatively high energy, are preferably used. The wavelength of the ultraviolet light is 200
It is preferably ˜400 nm. The light source of the ultraviolet rays is not particularly limited, and examples thereof include carbon arc, mercury vapor arc, fluorescent lamp, argon glow lamp, halogen lamp, incandescent lamp, low pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, flash UV lamp, deep UV lamp. , A xenon lamp, a tungsten filament lamp, sunlight, or the like can be used as appropriate.

When the method of crosslinking the crosslinked resin is humidification,
A predetermined amount of humidification is performed by a conventionally known humidifying method such as a humidifier.

The laminate obtained by laminating the release film (I) of the present invention on at least one side of a resin film has cushioning properties and strength for uniformly applying pressure during hot press molding. Excellent as a film. A laminated release film (hereinafter also referred to as a release film (II)) comprising a laminate in which the release film (I) of the present invention is laminated on at least one surface of such a resin film is also one of the present invention. is there.

The above resin film is not particularly limited, but polyethylene resin, polypropylene resin, ethylene-methyl methacrylate copolymer, ethylene- A resin made of an olefin resin such as a vinyl acetate copolymer is suitable.

The thickness of the release film (I) laminated on the resin film is preferably 0.5 to 20 μm. If it is less than 0.5 μm, the strength tends to be insufficient, and if it exceeds 20 μm, the cost becomes high. Also,
The release film (II) of the present invention has a thickness of 5 to 300 μm.
Is preferred. If it is less than 5 μm, the strength tends to be insufficient, and if it exceeds 300 μm, the thermal conductivity during hot press molding may deteriorate. More preferably 2
It is 5 to 100 μm.

Examples of the method for producing the release film (II) by laminating the release film (I) of the present invention on the resin film include solvent casting method and hot press molding method. In the above solvent casting method,
For example, after undercoating an anchor layer on a resin film, a resin solution before cross-linking containing a curing agent dissolved in a solvent is applied on the anchor layer and cross-linked by the above-mentioned cross-linking method. In the hot press molding, for example, the release film of the present invention, which has been previously formed into a film and crosslinked, and the resin film are superposed on each other and subjected to hot press molding. Before the hot press molding, a resin film layer may be provided on the release film (I) by a known method such as coextrusion or laminating.

The release film (I) and the release film (II) of the present invention have excellent heat resistance and releasability and can be safely and easily disposed of. Therefore, the printed wiring board, the flexible printed wiring board, and the multi-layer print can be disposed. In the manufacturing process of wiring boards, etc., when hot-pressing a copper clad laminate or copper foil through a prepreg or heat-resistant film, adhesion of the pressed hot plate to the printed wiring board, flexible printed wiring board, multilayer printed wiring board, etc. It is preferably used as a release film for preventing Further, in the manufacturing process of the flexible printed circuit board, when the coverlay film is bonded with a thermosetting adhesive by heat pressing, the coverlay film and the heat press plate, or as a release film for preventing adhesion between the coverlay films. Is also preferably used. Further, a release film for the production of fishing rods, golf clubs, shafts and other sports equipment and aircraft parts produced by curing a prepreg made of glass cloth, carbon fiber or aramid fiber and epoxy resin in an autoclave. It is also useful as a release film in the production of polyurethane foam, ceramic sheets, electric insulating plates and the like.

[0033]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 (1) Preparation of Release Film (I) 260 parts by weight of crystalline saturated polyester resin having carboxyl groups at both ends (Dynacol 8330 manufactured by Huls),
Trifunctional epoxy resin (manufactured by Dow Chemical Co .: TACTIX
742) 21 parts by weight and 2 parts by weight of a trivalent chromium complex (AMC-2 manufactured by BTR Japan Co., Ltd.) are mixed for 20 minutes at 30 rpm by a planetary mixer set to 80 ° C. to mix the resin and its curing agent before crosslinking. To obtain a mixture with. The thickness of this mixture is 100 μm by hot pressing set at 180 ° C.
The film was molded into a film of m and the hot pressing was continued for 40 minutes to complete the crosslinking. This was used as a release film (I).

(2) Preparation of Resin Film Polypropylene resin (manufactured by Montel Esdique Sunrise Co., Ltd .: J-Aroma PC630A) is used in an extruder to produce 230
The resin film was melted and plasticized by heating it to 0 ° C. and extruded from a T-die to obtain a resin film having a thickness of 100 μm.

(3) Measurement of gel fraction About 1 g of the release film (I) after cross-linking was precisely weighed and immersed in methyl ethyl ketone for 24 hours.
It was dried in a 0 ° C. gear oven for 1 hour, precisely weighed again, and the gel fraction determined according to the above formula (1) was 92%.

(4) Preparation of copper-clad laminate A 25 μm-thick polyimide film (DuPont: Kapton) was used as a base film, and a copper foil having a thickness of 35 μm and a width of 50 μm was epoxy-based with a thickness of 20 μm on the base film. A copper-clad laminate bonded with an adhesive was obtained.

(5) Preparation of Coverlay Film A coverlay film was obtained by coating an epoxy adhesive having a flow starting temperature of 80 ° C. with a thickness of 20 μm on a polyimide film (Kapton manufactured by DuPont) having a thickness of 25 μm. It was

(6) Fabrication of flexible printed circuit board A release film (I), a copper-clad laminate, a coverlay film, a release film (I), and a resin film are laminated in this order as one set, 32 sets. Placed on a hot press, press temperature 170 ° C, press pressure 300N / c
After hot press molding under conditions of m ² and a pressing time of 30 minutes, the pressing pressure was released, the resin film was removed, and the release film (I) was peeled off to obtain a flexible printed board.

The cover lay film of the obtained flexible printed circuit board was completely in close contact with the substrate body, and no residual air portion was observed. The release film (I) was completely peeled off from the electrode portion made of copper foil in the portion without the coverlay film, and the copper foil was completely exposed at the electrode portion. Moreover, the conductivity of the copper foil at the electrode portion was sufficient, and no contamination due to adhesion of organic matter was observed. Furthermore, the adhesive flow-out to the surface of the copper foil in the portion without the coverlay film is 0.1 from the edge of the coverlay film.
It was not more than mm, and the effect of preventing the adhesive from flowing out was sufficient.

(Example 2) (1) Preparation of release film (II) A mixture of the resin before crosslinking obtained in Example 1 (1) and its curing agent was placed on a hot plate set at 180 ° C. The release PET film was applied with a thickness of 30 μm using a bar coater, and this was heated in a gear oven set at 180 ° C. for 40 minutes to complete crosslinking. The obtained film was overlaid on the resin film prepared in Example 1 (2) to prepare 1
A release film (II) was obtained by pressure laminating with a hot press at 80 ° C. The gel fraction of the crosslinked resin portion of the release film (II) was 92%.

(2) Preparation of flexible printed board A flexible printed board was prepared in the same manner as in Example 1 (6) except that the release film (II) was used in place of the release film (I). did. The cover lay film of the obtained flexible printed circuit board was in complete contact with the substrate body, and no residual air portion was observed. The release film (II) is completely peeled off from the electrode part made of copper foil in the part without the coverlay film,
The copper foil was completely exposed at the electrode portion. Moreover, the conductivity of the copper foil at the electrode portion was sufficient, and no contamination due to adhesion of organic matter was observed. Further, the flow-out of the adhesive to the surface of the copper foil in the portion without the coverlay film was 0.1 mm or less from the edge of the coverlay film, and the effect of preventing the flow-out of the adhesive was sufficient.

[0043]

According to the present invention, it is possible to provide a release film which is excellent in heat resistance and releasability and which can be easily disposed of after use.

Continued front page    (72) Inventor Koji Yonezawa             Sekisui Chemical, 2-1 Hyakusan, Shimamoto-cho, Mishima-gun, Osaka Prefecture             Industry Co., Ltd. F-term (reference) 4F071 AA42 AA44 AF58 AH04 BB12                       BC01                 4F100 AB13 AK01A AK01B AK01C                       AK07 AK41 AK53 BA02 BA03                       BA06 BA07 BA10B BA10C                       CA02 GB43 JB12B JB12C                       JL00 JL14B JL14C YY00B                       YY00C                 5E346 CC46 CC60 DD12 EE05 EE08                       EE09 HH31

Claims (4)

[Claims] 1. A release film comprising a non-halogen cross-linking resin, wherein the non-halogen cross-linking resin has a gel fraction of 70% or more calculated by the following formula (1). (In the formula, x represents the dry weight (g) of the insoluble matter after the crosslinked resin is immersed in a solvent that completely dissolves the resin before crosslinking for 24 hours, and y is the weight (g) of the crosslinked resin before immersion in the solvent. A) represents a release film. 2. A laminated release film, comprising a laminate in which the release film according to claim 1 is laminated on at least one surface of a resin film. 3. A press hot plate when hot pressing a copper clad laminate or a copper foil with a prepreg or a heat-resistant film in a manufacturing process of a printed wiring board, a flexible printed wiring board or a multilayer printed wiring board. The release film according to claim 1 or 2, which is a release film that prevents adhesion between the release film and the printed wiring board, the flexible printed wiring board, or the multilayer printed wiring board. 4. In the process of manufacturing a flexible printed circuit board, when the cover lay film is bonded by a thermosetting adhesive by hot press molding, the cover lay film and the heat press plate or the cover lay films are prevented from being bonded to each other. It is a release film, The release film of Claim 1 or 2 characterized by the above-mentioned.