KR101084879B1 - Mold release sheet for hot pressing and method for manufacturing flexible printed wiring board using the same - Google Patents

Abstract

It is a release sheet for heat presses which has a film which consists of heat resistant plastics, and the resin layer which has a glass transition temperature (Tg) of -50-20 degreeC, and a mold release property on at least one surface of a film. After the heat press, the substrate is not damaged or the contamination of the resin is not caused, and furthermore, the gold plated surface due to the terminal plating does not cause discoloration or the connection reliability is lowered. It can be easily peeled off from the body.

Release Sheet for Heat Press, Flexible Printed Wiring Board

Description

Release sheet for heat press and method for manufacturing flexible printed wiring board using same {MOLD RELEASE SHEET FOR HOT PRESSING AND METHOD FOR MANUFACTURING FLEXIBLE PRINTED PRINTED WIRING BOARD USING THE SAME}

The present invention relates to a method for producing a release sheet and a flexible printed wiring board using the same, which can be disposed between the workpiece and the hot plate at the time of carrying out a release sheet, in particular hot press work, to uniformly apply heat or pressure to the workpiece. It is about.

BACKGROUND ART Conventionally, reinforcing materials, ornaments, and the like are applied to the surface of articles for the purpose of reinforcement or decoration. For example, in order to protect the IC surface of an IC card, a transparent protective film is stuck, the manufacturing process of a flexible printed wiring board, etc. are mentioned. The processing of these things is often performed mainly by a heat press, and in particular, when an adhesive is made of a thermosetting resin, a heat press is performed at a particularly high temperature, for example, a temperature of 180 ° C or higher. In addition, the heating press is performed not only at the time of the pasting but also at the time of processing to a specific shape such as mold molding using a mold.

In the heating press step, a release sheet is usually disposed between the workpiece and the hot plate. The release sheet can be easily peeled from the mold or hot plate, prevents damage to the workpiece by the mold or hot plate, and further applies uniform heating and pressure to the workpiece. For example, paper, a plastic film, etc. are used (refer patent document 1-8).

Thus, as a main use of a release sheet, the manufacturing process of a printed wiring board is mentioned, Especially it is used by the manufacturing method of a flexible printed wiring board. A flexible printed wiring board is a wiring board in which a wiring pattern made of a metal thin film is formed on one surface of a flexible insulating board. Flexible printed wiring boards, unlike conventional rigid printed wiring boards, have excellent features such as flexibility, flexibility, deformation, and storage in a narrow space, and can be used for mobile phones, portable information terminals, notebook computers, digital video cameras, and the like. It is widely used as a circuit board of a small electronic device requiring miniaturization / high density.

As a method of manufacturing such a flexible printed wiring board, there is a so-called pre-process. For example, a metal foil laminate (CCL: Copper Clad Laminate) in which a metal thin film is formed on one surface of a flexible insulating substrate. ) And the like) as a starting material, and by performing selective etching thereon, an unnecessary portion of the metal thin film is removed to form a wiring pattern.

Next, there is a thing called a post-process, and processing by a coverlay film is performed in order to prevent cutting or peeling of the wiring pattern formed in the previous process and to ensure insulation. Subsequently, the plating process proceeds to the edge connector terminal to be inserted in order to connect to the outside of the printed wiring board or the connection surface of the connection portion. This process is called terminal plating, and generally, the method by electroplating is widely used because it is easy to control the thickness and can plate various kinds of metals.

Conventionally, electroplating of eutectic soldering with a low melting point has been performed, but a method of using lead in consideration of environmental problems has been proposed. When high reliability is required, hard gold electroplating based on nickel is performed.

However, since the metal foil laminate has excellent flexibility and flexibility, the handling strength is not sufficient in the original state and it is difficult to perform selective etching. Therefore, the wiring pattern is formed by selective etching in a state where a sheet made of a resin such as polyester is adhered to the surface where the metal thin film of the metal foil laminate is not formed, as a backing material, and the handling strength is temporarily improved. The method of obtaining a flexible printed wiring board by carrying out coverlay processing and terminal plating process, and then peeling a back contact material from a metal foil laminated board is employ | adopted widely.

Since flexible printed wiring boards are thin and flexible, since a heavy component cannot be mounted as it is or inserted into the card edge connector for a printed circuit board, attaching the reinforcement board with an adhesive agent is performed. As the adhesive, a pressure-sensitive adhesive type and a thermosetting adhesive type are used depending on the intended use. The pressure-sensitive adhesive type cannot be used when its solvent resistance is not very good and high connection reliability is required due to creep characteristics. For this reason, when high reliability is required, the thermosetting adhesive type is used.

When attaching the reinforcement board with a thermosetting adhesive agent to a flexible printed wiring board, the method of hardening | curing the thermosetting resin by a hot press is normally performed. In order to absorb the unevenness | corrugation of a circuit pattern or a reinforcement board, and to complete adhesion | attachment, an uneven | corrugated followable sheet (release sheet for heat press) is used.

Conventionally, as an uneven | corrugated followable sheet | seat, the sheet | seat which laminated | stacked and bonded the thin heat resistant film on both surfaces of the thick film which consists of paper, the sheet | seat of silicone rubber reinforced fiber, and low temperature heat-soluble thermoplastic resin ( Patent Document 1), a film in which polypropylene or polymethylpentene is used in the upper and lower layers of an intermediate layer made of a copolymer resin of ethylene and methyl methacrylate (see Patent Document 2), and polymethyl on both sides of the polyolefin. The film which formed the layer which consists of pentene resins (refer patent documents 3 and 7), the release sheet using a poly 4-methyl-1- pentene film (refer patent documents 4 and 5), etc. are used. However, these release sheets may not have sufficient releasability with the flexible printed circuit board after hot pressing, or may be formed on the surface of a circuit formed by a conductor such as copper due to eluate from the sheet during hot pressing. There has been a problem that the gold plated surface by terminal plating causes discoloration or deterioration in connection reliability. In order to solve these problems, a release sheet for laminating a printed circuit board (see Patent Document 6) formed by coating polysiloxane on the surface of a metal plate or a release film made of a specific alicyclic olefin resin is used. Although the release sheet (refer patent document 8) which consists of a laminated body laminated | stacked on one side is proposed, not all are satisfactory yet.

[Patent Documents]

Patent Document 1: Japanese Patent Application Laid-Open No. H1-276694

Patent Document 2: Japanese Patent Laid-Open No. 2-24139

Patent Document 3: Japanese Patent Laid-Open No. 2-175247

Patent Document 4: Japanese Patent Application Laid-Open No. 2-238911

Patent Document 5: Japanese Patent Laid-Open No. 3-73588

Patent Document 6: Japanese Patent Application Laid-Open No. H5-147055

Patent Document 7: Japanese Patent Application Laid-Open No. 2000-263724

Patent Document 8: Japanese Patent Application Laid-Open No. 2001-233968

DISCLOSURE OF INVENTION

The present invention provides a release sheet and a flexible printed wiring board using the same, which can be disposed between the workpiece and the hot plate at the time of carrying out a release sheet, in particular, hot press work, to uniformly apply heat or pressure to the workpiece. The present invention relates to a method for providing a heat release mold release sheet having a small degree of discoloration of a gold plated surface in a flexible printed wiring board after heat press, in particular by elution from the sheet during heat press.

In addition, the present invention, as a result of careful research to develop a release sheet for heat press having the excellent performance as described above, the eluate from the sheet during the heat press on at least one side of the heat-resistant plastic film In order to defend, the release sheet which forms the resin layer which has a specific shape was found to achieve the objective, and reached | attained this invention based on this knowledge. That is, according to this invention, the hot press release sheet shown below is provided.

[1] A release sheet for heat press having a film made of a heat resistant plastic and a resin layer having a glass transition temperature (Tg) of -50 to 20 ° C and having a release property on at least one surface of the film.

[2] The release sheet for heat press according to the above [1], wherein the resin layer has a thickness of 0.1 to 10 µm.

[3] The release sheet for heat press according to the above [1] or [2], wherein the resin layer is a reaction product of an acrylic resin and a crosslinking agent.

[4] The release sheet for hot press according to any one of [1] to [3], wherein the discoloration degree by the following discoloration experiment is in the range of 0 to 3.0.

Discoloration Experiment:

(1) L * a * b * color system of the gold plated surface of a gold plated sheet (the gold plated layer having a thickness of 0.15 mu m on a nickel base layer having a thickness of 3 mu m, surface roughness Ra = 0.24 mu m) Measure brightness index and chromatinex index.

(2) On the gold plated sheet, a release sheet for hot press was placed so that the resin layer side was in contact with the gold plated surface, and heat-pressed for one hour under conditions of a temperature of 180 ° C. and a pressure of 30 kg / cm 2. After cooling, the release sheet for heat press was separated from the gold plated sheet, and the brightness index and chromatinex index of the gold plated surface were measured.

(3) The discoloration of the gold-plated surface before and after the heat press is calculated based on the color difference by the L * a * b * color system specified in JIS Z 8730.

[5] A method for manufacturing a flexible printed wiring board, comprising: attaching a reinforcing plate having a thermosetting adhesive to a surface on the side opposite to the wiring forming surface of the flexible printed wiring board by hot pressing using a hot plate, in the above [1] ] The manufacturing method of the flexible printed wiring board in which the release sheet for heat presses in any one of [4] is interposed at least between the said heat plate and the said wiring formation surface of the said flexible printed wiring board.

[6] A method of manufacturing a flexible printed wiring board, wherein the coverlay film is attached to the wiring forming surface of the flexible printed wiring board by hot pressing using a hot plate, wherein any one of the above [1] to [4] is used. The manufacturing method of the flexible printed wiring board which interposes the release sheet for heat presses which concerns on at least between the said hot plate and the said coverlay film.

The release sheet for heat press of the present invention is a release sheet which can be easily peeled off after hot pressing, and provides a sheet having a small degree of discoloration of the gold plated surface even when laminating on a gold plated surface and processing such as a hot press. That is, the circuit pattern formed from a conductor such as copper by the eluate from the sheet at the time of the heat press is not only damaged, and no contamination is caused, such as resin adhesion, after the heat press. In addition, the gold-plated surface by the terminal plating does not cause discoloration, or the connection reliability is not lowered, and the effect can be easily peeled from the adherend.

Best Modes for Carrying Out the Invention

EMBODIMENT OF THE INVENTION Hereinafter, although preferred embodiment of this invention is described, this invention is not limited to the following embodiment, On the basis of the general knowledge of a person skilled in the art within the range which does not deviate from the meaning of invention, It is to be understood that modifications, improvements, and the like are appropriately added within the scope of the present invention.

The release sheet for heat press of this invention is a sheet which consists of a film which consists of heat resistant plastics, and a glass transition temperature (Tg) in a -50-20 degreeC resin layer on at least one surface of a film. Hereinafter, the detail part is demonstrated.

The film which consists of heat-resistant plastics which comprise the release sheet for heat presses of this invention is necessary in order to acquire the track | trackability with the said unevenness | corrugation at the time of a hot press, when there exists an unevenness | corrugation in handling property, a cushion property, and the to-be-processed object. In particular, followability enables uniform heating and pressurization to the workpiece, whereby highly precise processing, for example, attaching the coverlay film without bubbles to the surface irregularities, The reinforcement plate can be attached so that the position does not shift or float. As such a film, it is preferable that melting | fusing point is 210 degreeC or more. As such a film, for example, polyethylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polycarbonate, triacetyl cellulose, polyimide, polyamide, polyethersulfone, aromatic polyamide, poly It is a film made of synthetic resin (heat-resistant plastic) such as sulfone. Among them, polybutylene terephthalate is most suitable from the viewpoint of heat resistance, chemical resistance, and uneven tracking. In addition, the film may be transparent, or may be colored by mixing various pigments and dyes with the material constituting the film, and the surface may be processed into a mat shape. The thickness of a film is the range of 10-150 micrometers normally which can be used within the range which does not reduce the cushioning property at the time of hot press. It is preferable that it is 25-100 micrometers in view of handling property.

Moreover, the film which comprises the release sheet for heat press of this invention can contain a well-known additive, specifically, a heat stabilizer, an oxidation stabilizer, a weather stabilizer, a ultraviolet absorber, an antistatic agent, etc. Moreover, in order to improve the adhesiveness of a film and a resin layer, it is preferable to surface-treat a film and / or to provide the intermediate | middle layer which has adhesiveness between a film and a resin layer. As the surface treatment to be carried out on the film, for example, ion treatment such as discharge treatment such as corona discharge treatment and glow discharge treatment, plasma treatment, flame treatment, ozone treatment, ultraviolet treatment, electron beam treatment and radiation treatment, sand mat And roughening treatment such as treatment and hairline treatment, chemical treatment, and adhesive layer coating treatment.

The release sheet for heat press of this invention is a sheet which has a resin layer, ie, laminated structure, at least through the film which consists of said heat resistant plastics, and the intermediate | middle layer provided by said film form directly or as desired. The glass transition temperature (Tg) of a resin layer is -50 degreeC-20 degreeC. If the glass transition temperature is lower than −50 ° C., resin adhesion easily occurs when the sheet is peeled off after hot pressing, which causes one of discoloration of the gold plated surface. On the other hand, when a glass transition temperature is higher than 20 degreeC, since the release sheet for hot press adheres to a flexible printed wiring board after hot press, it becomes difficult to peel, and it is unpreferable. In addition, when separating a release sheet and a flexible printed wiring board after heat press, in consideration of resin adhesion to a flexible printed wiring board and mold release, Tg of resin which forms the resin layer of the release sheet for heat press of this invention is- It is preferable that it is 30-15 degreeC, and it is still more preferable that it is -10 degreeC-10 degreeC.

In addition, the "glass transition temperature" referred to in this invention says the value (degreeC) obtained by performing differential scanning calorimetry (DSC) with respect to the resin layer peeled from the release sheet for heat presses. In addition, the detail of the measuring method of glass transition temperature is mentioned later.

In the present invention, the resin layer of the heat press release sheet is not particularly limited as long as it has the above glass transition temperature, and various kinds can be used. However, in view of releasability from a flexible printed wiring board, it is preferable that it is a reactant of acrylic resin and a crosslinking agent.

Acrylic resin used as resin which forms a resin layer can react with a crosslinking agent. Specifically, the copolymer of the acrylic acid alkyl ester and / or methacrylic acid alkyl ester, and the monomer which has a functional group which can cause reaction with a crosslinking agent is mentioned. As the alkyl ester constituting the acrylic acid alkyl ester and the methacrylic acid alkyl ester, for example, methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, s-butyl ester, t-butyl Esters, pentyl esters, hexyl esters, heptyl esters, octyl esters, isooctyl esters, 2-ethyl hexyl esters, isodecyl esters, dodecyl esters, tridecyl esters, pentadecyl esters, octadecyl esters, nonadecyl esters, eicosyl Ester etc. are mentioned. As a monomer which has a functional group which can react with a crosslinking agent, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid whose functional group is a carboxyl group, and And hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxyhexyl acrylate, and methacrylate whose functional groups are hydroxyl groups. Hydroxyhexyl acrylate, hydroxyoctyl acrylate, hydroxyoctyl methacrylate, hydroxydecyl acrylate, hydroxydecyl methacrylate, hydroxylauryl acrylate, hydroxy lauryl methacrylate and the like.

Furthermore, you may use together monomers other than the monomer mentioned above as needed. Specifically, styrene, vinyl acetate, acrylonitrile, acrylamide, polyethylene glycol acrylate, N-vinyl pyrrolidone, tetra perfuryl acrylate, etc. are mentioned.

Resin which forms the said resin layer can be obtained by radical copolymerizing the monomer of the above-mentioned acrylic acid alkyl ester and / or methacrylic acid alkyl ester, and the monomer which has a functional group which can react with a crosslinking agent. Copolymerization methods in this case are widely known, and examples thereof include emulsion polymerization, solution polymerization, mass phase polymerization, suspension polymerization, and photopolymerization.

In the release sheet for heat press of this invention, it is preferable that resin which forms a resin layer is bridge | crosslinked by the crosslinking agent. Here, the crosslinking agent may be appropriately selected according to the resin used, and isocyanate crosslinking agents, metal chelate crosslinking agents, epoxy crosslinking agents and the like are preferably used. However, the crosslinking agent may be viewed from the viewpoint of releasability from the flexible printed wiring board after the heat press process and prevention of resin adhesion. At this time, it is preferable to use an isocyanate-based crosslinking agent. As an isocyanate type crosslinking agent, 2, 4- triylene diisocyanate, 2, 6- triylene diisocyanate, 1, 3- xylylene diisocyanate, 1, 4- xylylene diisocyanate, diphenylmethane -4,4'- diisocyanate, diphenylmethane-2,4-diisocyanate, 3-methyl diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-di Isocyanate, dicyclohexyl-2, 4- diisocyanate, lysine isocyanate, etc. are mentioned. Among them, trimers of hexamethylene diisocyanate (for example, trade name: Tatenate D-170N, Mitsui Chemical Polyurethane Co., Ltd. product, etc.) can be preferably used. The said crosslinking agent is preferable at the point which shows the effect of being able to provide the outstanding mold release property and heat resistance. In addition, a "crosslinking agent" may be used independently and may be used in combination of 2 or more.

Moreover, what is necessary is just to mix | blend the said resin and the said crosslinking agent suitably so that the glass transition temperature (Tg) of the reaction material of the said resin and the said crosslinking agent may be -50-20 degreeC in the release sheet for heat press of this invention, Usually, it is 100 mass parts It is preferable to mix | blend 0.15-5.0 mass parts of crosslinking agents with respect to resin. When the compounding quantity of a crosslinking agent with respect to 100 mass parts resin is less than 0.1 mass part, resin adhesion etc. may arise in a flexible printed wiring board, or the mold release property with a flexible printed wiring may be damaged. On the other hand, when it exceeds 5.0 mass parts, adhesiveness with a flexible printed wiring board in normal temperature vicinity may fall. It is still more preferable that the compounding ratio of a crosslinking agent is 0.2-3.0 mass parts with respect to 100 mass parts of resin from the point of contamination prevention to a flexible printed wiring board, and mold release property.

Next, the method of manufacturing the release sheet for heat press of this invention is demonstrated. First, in order to form a resin layer on the upper surface of the film which consists of heat resistant plastics, the above-mentioned component is melt | dissolved or disperse | distributed in a suitable solvent, and the resin layer formation coating liquid whose solid content concentration is about 20-50 mass% is prepared. Subsequently, if the resin layer forming coating liquid is applied to the upper surface of the film by direct phase method and then dried to form a resin layer, a release sheet for hot press can be produced. It is preferable that the thickness of the resin layer to form shall be 0.1-10 micrometers. When the resin layer is thicker than 10 µm, cohesive failure is likely to occur at the time of separating the release sheet from the flexible printed wiring board after hot pressing, so that good release property may not be obtained. On the other hand, when it is thinner than 0.1 micrometer, since it is difficult to prevent the eluate from a sheet | seat at the time of hot pressing, it becomes difficult to prevent the discoloration of the circuit pattern and gold plating process surface which consist of conductors, such as copper. In view of the releasability from the flexible printed wiring board and the degree of discoloration of the circuit pattern formed from the conductor such as copper and the gold plated surface, the thickness of the resin layer is even more preferably 0.5 to 8 µm.

To the resin layer forming coating liquid, various conventionally used additives such as crosslinking accelerators, antioxidants, stabilizers, kurtosis adjusting agents, organic or inorganic fillers, and the like may be added. Examples of the crosslinking accelerator include triethylamine-based, naphthenic acid cobalt-based, and tin-based crosslinking accelerators. Particularly, tin tin chloride, tetra-nbutyl tin, trimethyl tin hydroxide, dimethyl tin chloride, and lauric It is preferable to use tin crosslinking accelerators such as acid di-n-butyltin. In addition, phenolic antioxidants and the like as the antioxidant, terpene resins and the like as the impregnated resin, acrylic and urethane spherical fine particles and the like as the organic filler, silica, calcium carbonate, alumina and the like can be preferably used as the inorganic filler. have.

In addition, the release sheet of the present invention, as described above, provided an intermediate layer on one side or both sides of the heat resistant film, and provided a resin layer having a glass transition temperature (Tg) in the range of -50 to 20 ° C. In addition, the laminated body or one side of the intermediate resin layer laminated on the both sides of the release sheet used in the prior art and the resin layer of the release sheet of the present invention on both sides of the intermediate resin layer made of a resin such as Orient, polyolefin or polyethylene. The release sheet is laminated on the resin layer so that the resin layer is on the outside, and the laminated film is also laminated on the other side by laminating a resin film made of polypropylene, polyethylpentene, or the like, and a film used in the heat resistant film of the present invention. Can be used as These things can obtain more cushioning properties compared to the release sheet which does not use the intermediate resin layer.

Next, the manufacturing method of the flexible printed wiring board of this invention using said release sheet for heat presses is demonstrated. The manufacturing method of the flexible printed wiring board of this invention WHEREIN: The said heat press in the attachment process of attaching the reinforcement board with a thermosetting adhesive to the surface on the opposite side to the wiring formation surface of a flexible printed wiring board by heat-pressing using a hotplate. It is a manufacturing method which interposes a mold release sheet between at least the said heat board and the said wiring formation surface of the said flexible printed wiring board. Hereinafter, the detail will be described.

The reinforcing plate with a thermosetting adhesive is appropriately selected depending on its use, and has a layer made of a reinforcing plate and a thermosetting adhesive disposed on at least one surface of the reinforcing plate. As a material which comprises a reinforcement board, paper phenol, glass epoxy resin, a polyimide resin, a polyester resin etc. are mentioned, for example. The reinforcing plate with a thermosetting adhesive can be obtained by laminating a thermosetting adhesive on the reinforcing plate.

A reinforcing plate with a thermosetting adhesive is cut into a predetermined size and placed at a predetermined position on the opposite side (rear surface) of the wiring forming surface of the flexible printed wiring board. Here, since a thick reinforcing plate with a thermosetting adhesive is used, when the step cannot be absorbed, it is preferable to use a dummy plate (a plate whose center corresponds to a predetermined position described above). It is usually done.

Next, the heat release mold release sheet of this invention is interposed between the hotplate and the wiring formation surface of a flexible printed wiring board as needed, and between the hotplate and the reinforcement board with a thermosetting adhesive agent. However, when the release sheet for hot press provides a resin layer only on one side of a heat resistant film, it is necessary to interpose the resin layer side in the state which contacted the wiring formation surface. In addition, even when the release sheet for heat press is interposed between the hot plate and the reinforcing plate with a thermosetting adhesive, in the case of the release sheet in which the resin layer is provided only on one side, the resin layer of the release sheet for heat press. The side is interposed in contact with a reinforcing plate with a thermosetting adhesive. Next, the thermosetting adhesive is cured using a heat press and the reinforcing plate is bonded. When using a dummy board, after cooling to room temperature, the flexible printed wiring board with a reinforcement board is manufactured by removing a dummy board.

What is necessary is just to heat-press thermosetting resin for 30 minutes-about 2 hours normally under the temperature and pressure conditions of 160-200 degreeC and 15-40 kg / cm <2>.

Next, the manufacturing method of another flexible printed wiring board using the release sheet for heat press of this invention is demonstrated. In the manufacture of the flexible printed wiring board, a conductive layer made of a conductive material such as copper is subjected to selective etching, and then a coverlay film made of a thermosetting resin is applied to cover the formed circuit pattern, and then 160 ° C. The wiring protective layer is formed by pressing with a hot plate under the above high temperature conditions and curing the adhesive of the coverlay film. At this time, the release sheet is laminated between the hot plate and the coverlay film such that at least the resin layer is on the coverlay side, followed by heating and decompression. Since the coverlay film needs to be adhered to irregularities such as a circuit pattern and does not contain bubbles or the like, the release sheet used at this time is preferably good in conformity to surface irregularities.

The discoloration degree in this specification means the color difference by L * a * b * color system prescribed | regulated to JISZ8730. It is preferable that the discoloration degree of the heat release mold release sheet in this invention is 0-3.0 or less. In view of the connection reliability of the flexible printed wiring board, it is preferably 0 to 1.5.

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto by these Examples. Moreover, the measuring method and the evaluation method of the physical-property value of the release sheet for hot press are shown below.

[Glass Transition Temperature]

In addition, "glass transition temperature" as used in this invention says the value (degreeC) obtained by peeling only the resin layer of the release sheet for hot presses, and performing differential scanning calorimetry (DSC). The measurement was carried out at a temperature increase rate of 10 ° C./min using a differential scanning calorimeter (manufactured by Bulguka AX Co., Ltd., product name DSC3200S).

[Peelability]

Using a gold plated sheet (with a gold plated layer of 0.15 μm laminated on the nickel base layer 3 μm, surface roughness Ra = 0.24 μm), attaching the resin layer side of the release sheet for heat press to the gold plated surface, After the heat press was carried out for one hour under the conditions of 180 ° C and 30 kg / cm 2, after cooling, the release sheet for heat press was evaluated at room temperature (23 ° C.) for peeling off the adherend. The evaluation criteria are [○] when the release sheet for hot press is easily peeled off from the gold plated sheet, and [△] when the release sheet for hot press is peeled off by applying force to the release sheet for heat release. It was set as [X].

[Pollution]

In the above-mentioned peelability evaluation, the contamination of the gold-plated surface of the gold-plated sheet which peeled the release sheet for hot presses was expanded by 50 times with the microscope (made by Keyence, product name VH-80-000), and evaluated. Evaluation criteria set [X] as the case where resin adhesion was not recognized and [X] as the case where it was recognized that grass remained on the gold plating process surface.

[Color Discoloration]

Brightness Index and Chromatinex Index by L * a * b * Color System of Gold Plating Surface in Gold Plating Sheet (with Gold Plating Layer Laminated at 0.15µm on Nickel Base Layer 3µm, Surface Roughness Ra = 0.24µm) Measure Then, the release sheet for heat press of the present invention is placed on the resin layer side in contact with the gold plated surface, and heat-pressed for 1 hour under conditions of temperature of 180 ° C. and pressure of 30 kg / cm 2. After cooling, the release sheet for heat press was peeled off, and the brightness index and chromatinex index of the gold plated surface were measured. The discoloration degree of the gold plating process surface before and behind a hot press is computed based on the color difference by L * a * b * color system prescribed | regulated to JISZ8730.

&Lt; Example 1 >

60 mass parts of acrylic resin (A) (glass transition temperature -8 degreeC, weight average molecular weight 320,000, and a constituent monomer containing methyl methacrylate, ethyl acrylate, butyl acrylate, and 2-hydroxyethyl methacrylate), acrylic resin ( B) (glass transition temperature -60 ° C, weight average molecular weight 900,000, 10 parts by mass of 2-ethylhexyl acrylate and 2-hydroxyethyl methacrylate as constituent monomers), acrylic resin (C) (glass transition temperature 18 ° C) , Weight average molecular weight 400,000, 40 parts by mass of methyl methacrylate, ethyl acrylate and 2-hydroxyethyl methacrylate as constituent monomers, isocyanate-based crosslinking agent (trade name: Tatenate D-170N, non-volatile content 20%, Mitsui 5 parts by mass of a chemical polyurethane product, etc.), an antioxidant (trade name: Adekadabu AO-330, non-volatile content 10%, manufactured by Asahi Kogyo Co., Ltd.) ) 2 parts by mass, lauric acid di-nbutyl tin (1% of non volatile matter, wagozu) Industrial District (和 光 純 藥 工業) was prepared ㈜ claim (製)) 2 parts by mass of methyl ethyl ketone and 300 parts by weight of uniformly mixed and dissolved to form a resin coating formulation. The resin forming coating solution was applied to a polybutylene terephthalate sheet having a thickness of 50 μm with a baker applicator, and sufficiently dried at 130 ° C., thereby producing a release sheet for heat press having a resin layer having a thickness of 1 μm. . Table 1 shows the measurement results of the physical properties of the release sheet for hot press and the evaluation results of various properties.

<Example 2>

Except having made acrylic resin (B) 2 mass parts, it carried out similarly to Example 1, and produced the release sheet for hot press. Table 1 shows the measurement results of the physical properties of the release sheet for hot press and the evaluation results of various properties.

<Example 3>

30 parts by mass of acrylic resin (C), acrylic resin (D) (glass transition temperature -42 ° C, weight average molecular weight 400,000, constituent monomers include 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate and vinyl acetate) Except having changed 70 mass parts and the crosslinking agent used in Example 1 into 15 mass parts, it carried out similarly to Example 1, and produced the release sheet for hot press. Table 1 shows the measurement results of the physical properties of the release sheet for hot press and the evaluation results of various properties.

<Example 4>

Except having changed the base material into polyethylene terephthalate, it carried out similarly to Example 1, and produced the release sheet for hot press. Table 1 shows the measurement results of the physical properties of the release sheet for hot press and the evaluation results of various properties.

Example 5

Except having changed the film thickness of the resin layer into 3 micrometers, it carried out similarly to Example 1, and produced the release sheet for heat presses. Table 1 shows the measurement results of the physical properties of the release sheet for hot press and the evaluation results of various properties.

<Example 6>

Except having changed the film thickness of the resin layer into 7 micrometers, it carried out similarly to Example 1, and produced the release sheet for hot presses. Table 1 shows the measurement results of the physical properties of the release sheet for hot press and the evaluation results of various properties.

Comparative Example 1

A release sheet for heat press was produced in the same manner as in Example 1 except that 100 parts by mass of the acrylic resin (B) was used without using the acrylic resin (A) and the acrylic resin (C). Table 1 shows the measurement results of the physical properties of the release sheet for hot press and the evaluation results of various properties.

Comparative Example 2

Except for using acrylic resin (E) (glass transition temperature of 22 ° C., weight average molecular weight of 300,000, and constituent monomers including methyl methacrylate and butyl acrylate), all of the release sheets for heat press were prepared in the same manner as in Comparative Example 1. Produced. Table 1 shows the measurement results of the physical properties of the release sheet for hot press and the evaluation results of various characteristics.

Comparative Example 3

Table 2 shows the evaluation results of various properties of the release sheet for hot press using a film obtained by co-extrusion of polymethylpentene on both sides of the polyolefin as the release sheet for hot press.

<Comparative Example 4>

As a release sheet for hot press, the polyethylene terephthalate film of 50 micrometers was used, and the evaluation result of the various characteristics of the said release sheet for hot press is shown in Table 2.

Comparative Example 5

As a release sheet for hot press, the polybutylene terephthalate film of 50 micrometers was used, and the evaluation result of the various characteristics of the said release sheet for hot press is shown in Table 2.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Glass transition temperature (℃) -10 2 -42 -10 -10 -10 -55 25 Coating film thickness (㎛) One One One One 3 7 One One Peelability ○ ○ ○ ○ ○ ○ ○ × Pollutant ○ ○ ○ ○ ○ ○ × ○ Discoloration degree 0.7 0.6 1.8 0.7 0.7 One 3.9 0.9

Comparative Example 3 Comparative Example 4 Comparative Example 5 Initial adhesion ○ ○ ○ Peelability ○ △ × Pollutant × × ○ Discoloration degree 3.6 10.5 1.4

From the results of Tables 1 and 2, it can be seen that all of Examples 1 to 6 had a low discoloration degree of 1.8 or less, as well as excellent peelability from the gold-plated surface and were not easily contaminated. On the other hand, it can be seen that the ones of Comparative Examples 1 to 5 do not satisfy any one of peeling property, staining property, discoloration degree, or both from the gold plated surface. As shown in Table 2, it turns out that the polyethylene terephthalate film and polybutylene terephthalate film conventionally used are inferior to releasability or contamination property than the release sheet for heat presses of this invention. It is considered from the above result that the thing of Examples 1-6 can be made into the material which can replace the release sheet used in the manufacturing process of the conventional flexible printed wiring board.

[Pollution (Cu)]

Bonding sheet (Somaar Corporation, Somatac PS-105WA) was attached to the polyimide surface of the copper clad laminated board by the method based on JISZ0237, and then it carried out on the copper surface Example 1 And the resin surface of each of the release sheets for heat press described in Comparative Examples 3 to 5. The sheet was subjected to heat press for 1 hour under conditions of 180 ° C. and 30 kg / cm 2, and then allowed to cool, and then the copper surface was contaminated when the copper foil laminate and the release sheet for heat press were separated at room temperature (23 ° C.). It was evaluated by expanding it 50 times with the scope (Kiens Co., Ltd., product name VH-8000). Evaluation criteria made [X] the case where resin adhesion was not recognized, and when the adhesion of a resin component was recognized on the copper surface.

Example 1 Comparative Example 3 Comparative Example 4 Comparative Example 5 Pollutant (Cu) ○ X X X

From the results of Table 3, it can be seen that the release sheet of Example 1 does not contaminate the copper surface as compared with Comparative Examples 3 to 5. From the above results, it can be seen that the release sheet of the present invention can be effectively used without contaminating the copper surface even when used in place of the release sheet used in the manufacturing process of the conventional flexible printed wiring board.

The release sheet for heat press of the present invention can be peeled off without causing resin adhesion after the heat press in the attaching step of the reinforcing plate with the thermosetting adhesive of the flexible printed wiring board, and the degree of discoloration of the gold-plated surface Since is smaller than the conventional one, it can contribute to the improvement of the connection reliability of a flexible printed wiring board.

Claims (7)

A film made of heat resistant plastic; Release sheet for heat press, characterized in that the at least one side of the film, made of a reactant of an acrylic resin and a crosslinking agent, the glass transition temperature (Tg) having a release property of -50 ~ 20 ℃; . The method according to claim 1, The release sheet for heat press whose discoloration degree by the following discoloration degree experiment exists in the range of 0-3.0. Discoloration Experiment: (1) L * a * b * color system of the gold plated surface of a gold plated sheet (the gold plated layer having a thickness of 0.15 mu m on a nickel base layer having a thickness of 3 mu m, surface roughness Ra = 0.24 mu m) Measure brightness index and chromatinex index. (2) On the gold plated sheet, a release sheet for hot press was placed so that the resin layer side was in contact with the gold plated surface, and heat-pressed for 1 hour under conditions of a temperature of 180 ° C. and a pressure of 30 kg / cm 2. After cooling, the release sheet for heat press was separated from the gold plated sheet, and the brightness index and chromatinex index of the gold plated surface were measured. (3) The discoloration of the gold-plated surface before and after the heat press is calculated based on the color difference by the L * a * b * color system specified in JIS Z 8730. The method according to claim 1 or 2, The release sheet for heat press, characterized in that the thickness of the resin layer is 0.1 to 10㎛. A method for manufacturing a flexible printed wiring board, comprising: attaching a reinforcing plate having a thermosetting adhesive to a surface on the side opposite to the wiring forming surface of the flexible printed wiring board by hot pressing using a hot plate, to claim 1 or 2 And a release sheet for thermal press according to the present invention, interposed between at least the hot plate and the wiring forming surface of the flexible printed wiring board. A method for manufacturing a flexible printed wiring board, comprising: a heat press according to claim 3 in an attaching step of attaching a reinforcing plate with a thermosetting adhesive to a surface on the side opposite to the wiring forming surface of the flexible printed wiring board by hot pressing using a hot plate. A release sheet for use is interposed between at least the said hot plate and the said wiring formation surface of the said flexible printed wiring board, The manufacturing method of the flexible printed wiring board characterized by the above-mentioned. As a method of manufacturing a flexible printed wiring board, in the attachment step of attaching a coverlay film to the wiring forming surface of the flexible printed wiring board by hot pressing using a hot plate, the release sheet for thermal press according to claim 1 or 2, A method of manufacturing a flexible printed wiring board, which is interposed between at least the hot plate and the coverlay film. A method for manufacturing a flexible printed wiring board, wherein the release sheet for heat press according to claim 3 is used at least in the hot plate in an attaching step of attaching a coverlay film to the wiring forming surface of the flexible printed wiring board by hot pressing using a hot plate. And the coverlay film interposed between the method of manufacturing a flexible printed wiring board.