JP7045500B2 - Manufacturing method of laminate and metal leaf with resin layer - Google Patents

Description

The present invention relates to a method for manufacturing a laminate that transfers a conductor circuit pattern on a resin layer to a substrate, and a metal foil with a resin layer used for this purpose.

Conventionally, a method of transferring a conductor circuit pattern to an insulating substrate has been proposed as a method of manufacturing a printed wiring board used for a package for accommodating a semiconductor element, wiring for a display panel, or the like. In this method, a metal foil is first attached to the surface of the resin film, unnecessary parts of the metal foil are removed by an etching method or the like to form a conductor circuit pattern, which is then crimped to an insulating substrate as a transfer sheet, and then the resin. The conductor circuit pattern is transferred by peeling off the film. According to this method, the substrate does not come into contact with various chemicals as compared with the method of laminating a metal foil on a substrate and removing unnecessary parts of the metal foil by an etching method or the like to form a conductor circuit pattern. It has advantages such as being able to prevent deterioration of the characteristics of the substrate due to the chemical solution.

For example, in Patent Document 1, an adhesive made of an ultraviolet curable acrylic resin is applied to the surface of a resin film made of polyethylene terephthalate to form an adhesive layer, and a copper foil is adhered onto the adhesive layer and then etched. A transfer sheet formed by forming a conductor circuit pattern and a method for manufacturing a laminate on which the transfer sheet is transferred are described.
Patent Document 1 states that by using an ultraviolet curable acrylic resin as the pressure-sensitive adhesive, it is possible to prevent the pressure-sensitive adhesive layer from adhering to the non-circuit-formed portion on the substrate.
Patent Document 2 also describes a similar transfer sheet and a method for producing a laminate to which the transfer sheet is transferred. In the same document, the pressure-sensitive adhesive layer is formed by using a pressure-sensitive adhesive obtained by cross-linking an acrylic polymer with a polyfunctional compound having reactivity with a carboxyl group. The acrylic polymer is obtained by copolymerizing a (meth) acrylic acid ester with a carboxyl group-containing radically polymerizable monomer. The document states that the adhesive layer having this structure allows the resin film to be peeled off from the metal foil.

Japanese Unexamined Patent Publication No. 10-178255 Japanese Unexamined Patent Publication No. 2002-134881

However, when the adhesive layer of the acrylic resin as described in Patent Documents 1 and 2 is used, the resin residue on the transferred metal leaf surface exists after the resin film is peeled off, and the final product formed after the transfer is obtained. There was a risk of affecting the heat resistance and reliability of the product. Further, the adhesive layer of the acrylic resin described in Patent Documents 1 and 2 is easily broken when the resin film is peeled off, and is difficult to use without a support such as polyethylene terephthalate, which is a problem from the viewpoint of cost reduction. was there.

An object of the present invention is to provide a method for manufacturing a laminated body and a metal foil with a resin layer, which can eliminate various drawbacks of the above-mentioned prior art.

The present invention comprises a step of forming a predetermined pattern by etching a metal foil with a resin layer having a metal foil and a resin layer.
A step of laminating a base material on the surface side of the metal foil with a resin layer on which the pattern is formed, and
The step of peeling off the resin layer is provided.
The resin layer mainly contains a styrene-butadiene copolymer and further contains a styrene-based compound.
The styrene-based compound is at least one selected from a styrene-based monomer, an oligomer and a polymer having the styrene-based monomer as a constituent unit, and the oligomer or a derivative of the polymer.
In the resin layer, the styrene-based compound is contained in an amount of 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the styrene-butadiene copolymer.
It provides a method for manufacturing a laminated body having a metal pattern (hereinafter, also referred to as a method for manufacturing a first laminated body of the present invention).

Further, the present invention has a peelable resin layer, a metal foil, a second peeling layer, and a carrier in this order.
The metal foil and the resin layer are directly in contact with each other and laminated.
A step of preparing a laminated sheet in which the peel strength Pr between the metal foil and the resin layer is larger than the peel strength Pc between the carrier and the metal foil.
The step of peeling the carrier of the laminated sheet in the peeling layer,
A step of forming a predetermined pattern by etching the metal foil,
A step of laminating a base material on the surface side of the laminated sheet on which the pattern is formed, and
The present invention provides a method for producing a laminate having a metal pattern (hereinafter, also referred to as a method for producing a second laminate of the present invention), which comprises a step of peeling off the resin layer in this order.

Further, the present invention relates to a metal foil with a resin layer having a metal foil and a resin layer for peeling.
The metal foil and the resin layer are directly in contact with each other and laminated.
The resin layer mainly contains a styrene-butadiene copolymer and further contains a styrene-based compound.
The styrene-based compound is at least one selected from a styrene-based monomer, an oligomer and a polymer having the styrene-based monomer as a constituent unit, and the oligomer or a derivative of the polymer.
In the resin layer, the styrene-based compound is contained in a metal foil with a resin layer of 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the styrene-butadiene copolymer.

Further, the present invention is used as a release layer of the resin layer in a metal foil with a resin layer in which a metal foil and a resin layer are directly contacted and laminated, and the resin layer is provided with the above resin composition. It provides use.

Further, the present invention is a method of using the resin layer in a metal foil with a resin layer in which a metal foil and a resin layer are directly contacted and laminated as a release layer, and the resin layer has the above-mentioned resin composition. It provides a usage method to make it.

Hereinafter, the present invention will be described based on the preferred embodiment thereof. This embodiment relates to a metal foil with a resin layer used in a transfer method. Hereinafter, the metal foil with a resin layer of the present embodiment will be described first. The metal foil with a resin layer has a peeling resin layer (A) having a specific resin composition, and a metal foil (B) laminated on one surface of the resin layer (A).

One of the features of this embodiment is that the resin layer (A) mainly contains a styrene-butadiene copolymer and further contains a styrene-based compound in a specific ratio with respect to the styrene-butadiene copolymer.
The present inventor has diligently studied the structure of the metal foil with a resin layer used in the transfer method and the ease of peeling of the resin layer (A) from the metal foil (B). As a result, when a resin layer (A) having a specific resin structure is used instead of the conventionally used acrylic resin-based adhesive layer and polyethylene terephthalate support, the resin layer (A) is used after circuit transfer. ) Can be easily peeled off from the interface of the metal foil (B), and it has been found that the resin residue can be effectively prevented. Therefore, unevenness in surface treatment such as cleaning and roughening is unlikely to occur on the wiring pattern transferred using the metal leaf with a resin layer of the present embodiment, and the surface cleanliness and surface treatment homogeneity are excellent and reliable. A laminate with a high circuit can be obtained.

Further, in the present embodiment, the resin layer (A) in the metal foil with the resin layer has not only the releasability from the metal foil (B) but also the rigidity that can withstand the deformation at the time of pattern formation and the resin layer (A). As a single unit, it has toughness that does not deform even when peeled off. Therefore, in this embodiment, it is not necessary to use a support such as polyethylene terephthalate. Therefore, in the present embodiment, it is not necessary to apply an adhesive to the peeling resin layer, and the manufacturing cost can be reduced.

On the other hand, the conventional acrylic resin-based adhesive layer tends to generate resin residue on the wiring pattern as described above. This resin residue causes uneven surface treatment when the surface of the metal foil after transfer is surface-treated, and such a laminate having a copper foil as an inner layer has an uneven gloss pattern and an appearance. In addition to being unsuitable for display applications, it may impair heat resistance and reliability when the laminate is used at high temperatures. Further, the acrylic resin is inferior in resistance to heat crimping treatment. Therefore, when the same components as the acrylic adhesive layer are molded into a film and the obtained molded body is laminated with the metal foil by heat pressure bonding treatment, the resin layer is formed even if the molded body is to be peeled off after the circuit is formed. It breaks internally, making it very difficult or impossible to peel it off.

In the present specification, the "peeling resin layer" and the "peeling layer" refer to layers used by peeling from a metal foil.
Further, for the above reason, the resin layer (A) of the present embodiment can also be referred to as a peelable resin layer. In the present specification, the peelability is a laminated body formed by laminating a base material made of any of the resin types described later under the crimping conditions described later on the surface side of the metal leaf with a resin layer on which the pattern is formed. In the resin layer (A), when the resin layer (A) is to be peeled from the metal foil (B), the resin layer (A) is not broken in the resin layer (A) and the metal foil (B) is peeled from the base material. A) means the property of peeling from the metal leaf (B) or, if necessary, from the metal leaf (B) and the base material. The peelability may be exhibited in any one laminate containing the resin layer (A), and in that case, it may not be exhibited in the other laminate.

In the present specification, when the resin layer (A) is peeled off from the metal foil (B), the "metal foil (B)" referred to here is used to cover the entire surface of the resin layer (A) before pattern formation. Both the metal leaf (B) and the metal pattern formed from the metal leaf (B) may be included.

Hereinafter, the metal foil with a resin layer used in the present embodiment will be further described.
<Styrene-butadiene copolymer>
One of the features of the present embodiment is that the resin layer (A) contains a styrene-butadiene copolymer as a main component. As a result, the metal foil with a resin layer of the present embodiment has good adhesion and peelability to the metal foil, and the resin layer (A) itself has excellent elasticity and flexibility. The styrene-butadiene copolymer includes a random copolymer, an alternating copolymer, a block copolymer, a graft copolymer and the like, and the block copolymer is used from the viewpoint of advantageously maintaining the strength at the time of peeling of the resin layer (A). Polymers are preferred. Examples of the block copolymer include a styrene-butadiene block copolymer, a styrene-butadiene-styrene block copolymer, and a styrene- (styrene-butadiene) -styrene block copolymer. These are used alone or in admixture of two or more.

The content of the styrene unit in the styrene-butadiene copolymer (total amount of the copolymer) is preferably 20% by weight or more from the viewpoint of more reliably reducing the resin residue after the resin layer (A) is peeled off. On the other hand, from the viewpoint of maintaining flexibility, 80% by weight or less is preferable. From these points, the weight ratio of the styrene unit in the styrene-butadiene copolymer is more preferably 30% by weight or more and 70% by weight or less, more preferably 45% by weight or more and 65% by weight or less.
In addition, the number average molecular weight (Mn) of the styrene-butadiene copolymer by the GPC (gel permeation chromatography) analysis method is determined from the viewpoint of maintaining flexibility and breaking system more predominantly when the peeling resin layer (A) is peeled off. It is preferably 50,000 or more and 500,000 or less.

Various modifications may be added to the styrene-butadiene copolymer for the purpose of imparting a function such as thermosetting property. Examples of the modification include glycidyl ether modification, oxylan introduction, hydroxyl group modification, carboxyl group modification and the like.

When the resin layer (A) contains a styrene-butadiene copolymer as a main component (main component), it is preferable that the styrene-butadiene copolymer is contained in an amount of 45% by mass or more in the resin component of the resin layer (A). Means that. Since the styrene-butadiene copolymer is contained in an amount of 45% by mass or more based on the resin component in the resin layer (A), the resin layer (A) can be easily formed into a metal foil while preventing breakage inside the resin layer (A). It can be peeled off from B). Further, by setting the amount of the styrene-butadiene copolymer to 80% by mass or less in the resin component of the resin layer (A), a styrene-based compound other than the styrene-butadiene copolymer and polyphenylene described later contained as necessary are contained. The amount of the ether resin can be set to a certain level or more, and the resin layer can be imparted with rigidity, heat resistance, chemical resistance and the like. From these viewpoints, it is more preferable that the styrene-butadiene copolymer is contained in the resin component of the resin layer (A) in an amount of 47% by mass or more and 77% by mass or less, and 49% by mass or more and 75% by mass or less. Is particularly preferable.

<Styrene compound>
The styrene-based compound is used to impart rigidity, toughness, and ease of peeling to the resin layer (A) in the metal leaf with a resin layer of the present embodiment. In the resin layer (A), the styrene-based compound is one or more compounds selected from a styrene-based monomer, an oligomer and a polymer having the styrene-based monomer as a constituent unit, and the oligomer or a derivative of the polymer. ..
Therefore, styrene compounds do not contain block copolymers of styrene and other unsaturated hydrocarbons. The styrene-based compound which is a polymer usually has a styrene chain as a main chain.

Examples of the styrene-based monomer as a constituent unit include styrene and substituted styrene. As the substituted styrene, one or two or more hydrogen atoms bonded to the benzene ring constituting the styrene are alkyl groups having 1 to 5 carbon atoms. , Alkoxy groups having 1 to 5 carbon atoms, those substituted with substituents such as chlorine, bromine and fluorine which are halogen atoms can be mentioned. Specific examples of the styrene-based monomer include styrene, methylstyrene, α-methylstyrene, β-methylstyrene, t-butylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, fluorostyrene, bromostyrene and the like.

Examples of the oligomer having a styrene-based monomer as a unit unit include oligomers obtained by polymerizing the styrene-based monomers mentioned above, and examples thereof include 2,4-diphenyl-4-methyl-1-pentene and 2,4-. Diphenyl-1-butene, 1,2-diphenylcyclobutane, 1-phenyltetraline, 2,4,6-triphenyl-1-hexene, 1-phenyl-4- (1'-phenylethyl) tetraline, 1,3, Examples thereof include 5-triphenylcyclohexane. The oligomer includes a dimer and a trimmer. Oligomers usually have about 2 to 20 constituent monomers.

Examples of the polymer having a styrene-based monomer as a unit unit include the above-mentioned styrene-based monomer and / or a polymer obtained by polymerizing the above-mentioned oligomer.

Examples of the above-mentioned styrene-based oligomer or polymer derivative include those obtained by subjecting the styrene-based oligomer or polymer to various modifications such as terminal modification or introduction of a substituent. Examples of the modification include glycidyl ether modification, oxylan introduction, hydroxyl group modification, carboxyl group modification and the like.

Here, when the resin layer (A) is peeled off rapidly, a strong stress is applied to the resin layer (A). From the viewpoint of maintaining the peeling performance more stably even in such a case, the above-mentioned styrene-based compound has a number average molecular weight (Mn) of 15,000 or more and 350,000 or less by a GPC (gel permeation chromatography) analysis method. Is preferable.

The styrene-based compound is the total amount of the above-mentioned styrene-based monomer, the oligomer and the polymer having the styrene-based monomer as a unit unit, and their derivatives, and the styrene-butadiene is used in the resin layer (A) of the metal foil with the resin layer of the present embodiment. It is contained in an amount of 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the polymer. When the amount of the styrene compound is 10 parts by mass or more, the resin layer (A) has sufficient rigidity and is easily peeled off from the metal foil (B), and does not have a support such as polyethylene terephthalate. It can function as a resin layer for peeling. Further, when the amount of the styrene-based compound is 70 parts by mass or less, the resin layer (A) can maintain toughness, which makes it easy to peel off from the metal foil (B). From these viewpoints, the amount of the styrene-based compound in the resin layer (A) is more preferably 15 parts by mass or more and 67 parts by mass or less with respect to 100 parts by mass of the styrene-butadiene copolymer, more preferably 20 parts by mass. It is particularly preferable that the portion is contained in an amount of 65 parts by mass or less. The ratio of the styrene-based monomer, the oligomer having the styrene-based monomer as a constituent unit, and its derivative thereof in the styrene-based compound is not limited. By containing the styrene compound in the above amount in the resin layer (A) of the present embodiment, the resin layer (A) can be stably peeled off without breaking, and the effect of the present invention of reducing the resin residue can be obtained. Can be done.

<Preferable material: Polyphenylene ether resin>
Among the components contained in the resin layer (A), the polyphenylene ether resin contained as a preferable material is a suitable component that imparts heat resistance more predominantly due to its structure. In the metal foil with a resin layer of the present embodiment, when the resin layer (A) contains a polyphenylene ether resin, the resin layer (A) is broken even when the metal foil with a resin layer is laminated with a base material under high temperature conditions. It can be peeled off from the metal foil more stably without any problem, and the resin residue can be reduced more effectively.

As the polyphenylene ether resin, for example, a resin having a structure represented by the following general formula (1) is used. For example, the polyphenylene ether resin may have a structure represented by the general formula (2), for example.

（式中、Ｒ１、Ｒ２、Ｒ３及びＲ４はそれぞれ、同一の又は異なる水素原子又は炭素数１以上３以下の炭化水素基を表す。ｎは１以上の整数を表す。）

(In the formula, R1, R2, R3 and R4 represent the same or different hydrogen atoms or hydrocarbon groups having 1 or more and 3 or less carbon atoms, respectively. N represents an integer of 1 or more.)

（式中、Ｒ１、Ｒ２、Ｒ３及びＲ４は一般式（１）と同じである。また、ａ及びｂはそれぞれ１以上１００以下の整数を表す。Ａは直接結合、又は、炭素数２０以下の直鎖状、分岐状若しくは環状の２価の炭化水素基である。なお、複数存在するＲ１は互いに同一であっても異なってもよく、Ｒ２、Ｒ３及びＲ４も同様である。）

(In the formula, R1, R2, R3 and R4 are the same as the general formula (1). Further, a and b each represent an integer of 1 or more and 100 or less. A is a direct bond or has 20 or less carbon atoms. It is a linear, branched or cyclic divalent hydrocarbon group. A plurality of R1s may be the same or different from each other, and the same applies to R2, R3 and R4.)

Examples of the hydrocarbon group having 1 to 3 carbon atoms represented by R1, R2, R3 and R4 include a methyl group, an ethyl group and a propyl group. The linear, branched or cyclic divalent hydrocarbon group represented by A having 20 or less carbon atoms includes a linear or branched alkylene group, a phenylene group which may be substituted with an alkyl group, and an alkyl group. Examples thereof include a biphenylene group which may be substituted with, and a combination thereof. Examples of the polyphenylene ether resin include poly (2,6-dimethyl-1,4-phenylene) ether, poly (2,6-diethyl-1,4-phenylene) ether, and poly (2,6-dipropyl-1,4). -Phenylene) Ether or the like can be used.

In order to further increase the heat resistance of the resin layer, it is preferable that the end of the polyphenylene ether resin is modified with a thermosetting functional group. Examples of the thermosetting functional group include a hydroxyl group, an acrylic group, a methacrylic group, an acryloyloxy group, a metaacryloyloxy group, a glycidyl ether group, a vinylbenzyl group and an allyl group. Among these, polyphenylene ether resins modified with vinylbenzyl group, acrylic group, methacrylic group, etc. are among these because they are functional groups that impart highly reactive thermosetting properties while maintaining the excellent dielectric properties of polyphenylene ether. preferable.

The number average molecular weight (Mn) of the polyphenylene ether resin by the GPC (gel permeation chromatography) analysis method is preferably 500 or more and 4,000 or less, and more preferably 600 or more and 3,500 or less. Within this range, the polyphenylene ether resin can be easily dissolved in a solvent and easily varnished, and the toughness of the resin layer can be maintained.

In order to significantly exert the advantages of the above-mentioned polyphenylene ether resin, the content of the polyphenylene ether resin in the resin layer is preferably 1 part by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the styrene butadiene copolymer. It is more preferably 2 parts by mass or more and 55 parts by mass or less, further preferably 4 parts by mass or more and 50 parts by mass or less, and particularly preferably 5 parts by mass or more and 20 parts by mass or less.

The resin layer (A) may contain components other than the styrene-butadiene copolymer, the styrene-based compound, and the polyphenylene ether resin as long as the peelability is not impaired. Examples of such components include inorganic fillers, dispersants, thermal polymerization inhibitors, antioxidants, ultraviolet absorbers, colorants, leveling agents, plasticizers, surfactants and the like. From the viewpoint of further enhancing the above-mentioned characteristics of the resin layer (A), the resin component in the resin layer (A) is preferably 50% by mass or more, more preferably 80% by mass or more. From the same viewpoint, the content of the components other than the styrene-butadiene copolymer, the styrene compound and the polyphenylene ether resin in the resin layer (A) is preferably 50% by mass or less, more preferably 20% by mass. It is as follows.

In addition to containing the specific component in the specific amount, the resin layer (A) preferably has a storage elastic modulus in a specific range at 30 ° C. Specifically, the resin layer (A) in the present embodiment has a storage elastic modulus at 30 ° C. of 0.1 GPa or more, which enhances the rigidity and toughness of the resin and is a resin layer at the time of peeling. It is preferable because it is easier to prevent the deformation of. If the resin layer is easily deformed at the time of peeling, there are problems that the resin layer is stretched and easily torn at the time of peeling, it is difficult to stably peel it from the metal leaf interface, and resin residue is likely to occur. Further, it is preferable that the storage elastic modulus at 30 ° C. is 0.50 GPa or less because the flexibility of the resin layer can be ensured and the brittleness of the resin layer at the time of peeling can be further reduced. If the resin layer is brittle at the time of peeling, there are problems that the resin is easily broken and is not stably peeled off from the metal foil interface, and that resin residue is likely to occur. From these viewpoints, the storage elastic modulus of the resin layer (A) is more preferably 0.12 GPa or more and 0.40 GPa or less, and further preferably 0.15 GPa or more and 0.32 GPa or less. The storage elastic modulus can be measured by the method described in Examples described later.

Examples of the molding method of the resin layer (A) include an extrusion molding method, an injection molding method, and a coating method, but the coating method is most preferable from the viewpoint of wettability to the metal foil (B) and simplification of the process. .. As the solvent used in the coating method, an organic solvent capable of dissolving or dispersing the resin composition can be appropriately selected and used according to the solubility parameter of the resin and the like. Further, after coating, the resin film or sheet obtained by coating may or may not be heated for the purpose of volatilizing the solvent, and when heating, the temperature and time corresponding to the solvent can be appropriately selected. The resin layer (A) may be formed directly on the metal leaf (B) by using a coating method or the like, or may be formed by using the above-mentioned various methods (in the case of the coating method, a substrate different from the metal leaf (B)). A film-shaped or sheet-shaped resin layer (A) may be produced (by applying a coating liquid to the metal leaf), and the resin layer (A) may be laminated on the metal foil (B) by a known laminating method such as heat pressure bonding or vacuum laminating.

The thickness of the resin layer (A) is preferably 12 μm or more and 1000 μm or less, and more preferably 18 μm or more and 300 μm or less, from the viewpoint of ease of peeling from the metal foil (B) and handleability.

The resin layer (A) may be laminated so as to be in direct contact with the metal foil (B), or may be laminated via another layer as long as the effect of the present invention is not impaired. Even when laminated via another layer, the resin layer (A) is easily peeled (separated) from the metal foil (B), so that the surface cleanliness and surface treatment homogeneity in the metal pattern It can give sex. The resin layer (A) is in direct contact with the metal foil (B) from the viewpoint of further enhancing the effect of the peelability of the resin layer (A) by using the specific component in a specific ratio and from the viewpoint of manufacturing cost. It is preferable that they are laminated. When another layer is formed between the resin layer (A) and the metal foil (B), examples of the constituent components of the other layer include interposing a release layer such as a silicone resin or a fluororesin.

The peel strength Pr between the resin layer (A) and the metal foil (B) is preferably 100 gf / cm or less from the viewpoint of ease of peeling of the resin layer (A) from the metal foil (B). Further, the peel strength Pr between the resin layer (A) and the metal foil (B) is 2 gf / cm or more, so that the adhesion of the resin layer (A) to the metal foil (B) is kept to a certain degree. Therefore, it is preferable from the viewpoint of improving the handleability of the metal foil with a resin layer. From these viewpoints, the peel strength Pr between the resin layer (A) and the metal foil (B) is more preferably 3 gf / cm or more and 80 gf / cm or less, and 4 gf / cm or more and 75 gf / cm or less. Is even more preferable. In order to set the peel strength Pr in the above range, the resin layer (A) is manufactured with the above specific composition, and the surface roughness of the surface of the metal foil (B) on the resin layer (A) side is set in the following range. Alternatively, the conditions for laminating the resin layer (A) and the metal foil (B) may be appropriately adjusted. For example, laminating the resin layer (A) and the metal foil (B) so that the glossy surface when the metal foil (B) is electrolytic copper is in contact with the resin layer (A) can also set the peel strength Pr within the above range. It is preferable because it is easy to use. The peel strength can be measured by the method described in Examples described later. The glossy surface referred to here is a surface of a copper foil obtained by an electrolytic method using a cathode drum, which faces the drum side at the time of manufacture. However, the method is not limited to this method, and as will be described later, when the metal leaf of the metal foil with resin is a metal leaf with a carrier by an electrolytic method, the drum surface (glossy surface) of the carrier (D) manufactured by the electrolytic method. A release layer (C) and a metal foil (B) are provided on the side, and the metal foil (B) is attached to the resin layer (B) in a state where the electrolytic solution surface side of the metal foil (B) is in contact with the resin layer (A). It may be laminated with A).

Next, the metal leaf (B) will be described. The metal in the metal foil (B) is for forming a so-called conductor circuit pattern, and low resistance metals such as gold, silver, copper and aluminum, or alloys thereof are suitable, and copper is particularly preferable. It is preferable from the viewpoint of conductivity and processability. When copper is used, it is preferable that the metal foil is pure copper or a copper alloy, and the proportion of copper is typically 95% by mass or more from the viewpoint of conductivity, etching processability and the like. The thickness of the metal foil (B) is preferably, for example, 3 μm or more and 70 μm or less, preferably 5 μm or more and 35 μm or less, from the viewpoint of handleability of the metal foil with a resin layer and ease of etching. Is more preferable. The manufacturing method of the metal foil (B) is not particularly limited, and may be formed by, for example, an electrolytic method, a rolling method, a vapor phase method, or the like.

The surface on the resin layer (A) side of the metal foil (B) preferably has a surface roughness (Rzjis) of 4.0 μm or less, more preferably 3.0 μm or less, still more preferably 2.0 μm or less. Is. By setting the surface roughness (Rzjis) in this range, the ease of peeling of the resin layer (A) when directly laminated with the metal foil (B) can be improved. Further, from the viewpoint of maintaining the adhesion between the resin layer (A) and the metal foil (B), the surface roughness (Rzjis) of the surface of the metal foil on the resin layer (A) side is preferably 0.01 μm or more, more preferably. Is 0.02 μm or more, more preferably 0.05 μm or more. Surface roughness (Rzjis) is measured according to JIS B0601-1994.

When the thickness of the metal foil (B) is as thin as 9 μm or less, the metal foil with a resin layer has a peeling layer on the surface of the metal foil (B) opposite to the resin layer (A) in order to improve handleability. It is preferable to have (C) (second peeling layer) and carrier (D) in this order.

Examples of the carrier (D) include metals such as copper, iron, and aluminum, alloys containing these metals as main components, and heat-resistant resins such as polyester and engineering plastics, which stabilize the peeling strength from the metal foil. Copper foil is preferable from the viewpoint of ensuring the above. The thickness of the carrier is preferably 12 μm or more and 100 μm or less, and more preferably 15 μm or more and 40 μm or less, from the viewpoint of transportability and peelability.

The release layer (C) is used for the purpose of facilitating the release between the metal foil (B) and the carrier (D), and may be either a known organic release layer or an inorganic release layer. Examples of the organic component used for the organic exfoliation layer include nitrogen-containing organic compounds, sulfur-containing organic compounds, and carboxylic acids. Examples of the nitrogen-containing organic compound include a triazole compound and an imidazole compound, and among them, the triazole compound is preferable because the peelability is easily stable. Examples of triazole compounds include 1,2,3-benzotriazole, carboxybenzotriazole, N', N'-bis (benzotriazolylmethyl) urea, 1H-1,2,4-triazole and 3-amino-1H. -1,2,4-triazole and the like can be mentioned. Examples of the sulfur-containing organic compound include mercaptobenzothiazole, thiothianuric acid, 2-benzimidazolethiol and the like. Examples of the carboxylic acid include monocarboxylic acid, dicarboxylic acid and the like. On the other hand, as an example of the inorganic component used for the inorganic release layer, a metal or alloy composed of at least one of Ni, Mo, Co, Cr, Fe, Ti, W, P, Zn and the like, and / or an oxide thereof. Can be mentioned. The thickness of the release layer (C) is typically 1 nm or more and 1 μm or less, preferably 5 nm or more and 500 nm or less.

When the metal foil with a resin layer has a peeling layer (C) and a carrier (D), the peeling strength Pc (peeling strength in the peeling layer (C)) between the carrier (D) and the metal foil (B) is , The peel strength between the resin layer (A) and the metal foil (B) is usually smaller than the peel strength Pr. This makes the metal leaf with a resin layer easy to use in applications that require two-step peeling, in which the carrier (D) is peeled off before pattern formation and the resin layer (A) is peeled off after transfer.

The peel strength Pc between the carrier (D) and the metal foil (B) is typically 100 gf / cm or less from the viewpoint of ease of peeling of the carrier (D) from the metal foil (B). It is preferable from. Further, the peel strength Pc between the carrier (D) and the metal foil (B) is 1 gf / cm or more so that the adhesion of the carrier (D) to the metal foil (B) is kept to a certain degree. It is preferable from the viewpoint of improving the handleability of the metal foil with a resin layer. From these viewpoints, the peel strength Pc between the carrier (D) and the metal foil (B) is more preferably 2 gf / cm or more and 50 gf / cm or less, and more preferably 3 gf / cm or more and 30 gf / cm or less. Even more preferable. In order to keep the peel strength Pc in the above range, it is possible to control by appropriately adjusting the thickness of the peel layer (C), the thickness of the carrier (D), the surface roughness on the peel layer side, and the like. The peel strength can be measured by the method described in Examples described later. Further, in the process of manufacturing the laminate, the peel strength is obtained from the viewpoint of more effectively preventing the resin layer (A) from peeling from the metal foil (B) when the carrier (D) is peeled from the metal foil (B). The difference Pr-Pc between Pc and the peel strength Pr is preferably 2 gf / cm or more and 30 gf / cm or less, and more preferably 3 gf / cm or more and 20 gf / cm or less.

When manufacturing a metal leaf with a resin layer provided with a release layer (C) and a carrier (D), for example, the metal foil (B), the release layer (C) and the carrier (D) are laminated in this order. A method of preparing a metal leaf with a carrier and laminating the metal leaf with a carrier so that the metal foil (B) faces the resin layer (A) can be adopted. As the laminating method of the metal foil with a carrier and the resin layer (A) in this case, various methods such as the coating method described above and preferable conditions thereof can be adopted. Further, as a method of laminating the metal foil (B), the release layer (C) and the carrier (D) to obtain the metal foil with a carrier, for example, when the carrier (D) is a copper foil, a rolling method is used. , It can be formed by a method such as an electrolytic method.

The method for manufacturing the laminate of the present embodiment using the above-mentioned metal leaf with a resin layer will be described in more detail. In this manufacturing method,
(1) A step of etching the metal leaf (B) in the metal leaf with a resin layer to form a predetermined pattern.
(2) A step of laminating a base material on the surface side of the metal foil with a resin layer on which the pattern is formed.
(3) A step of mechanically peeling off the resin layer (A) is provided.
When the metal foil with a resin layer has a peeling layer (C) and a carrier (D), the step (1) is performed after the carrier (D) is mechanically peeled from the metal foil with a resin layer.

The step (1) can usually be performed by a subtractive method. In this case, a layer made of a photoresist is provided on the entire upper surface of the metal foil (B) in the metal foil with a resin layer, then the wiring pattern is exposed on this layer, and the portion other than the portion that becomes the wiring pattern is developed and removed. An etching resist layer having an opening in which the copper layer is exposed is obtained. Then, by an etching process, copper in the opening of the etching resist layer is removed to form a predetermined pattern. As the etching solution, conventionally known etching solutions used in the subtractive method can be used without particular limitation. Then, the etching resist is removed by using an aqueous solution of caustic soda or the like. In this way, a metal foil with a resin layer, which is a transfer laminate with a circuit wiring layer, can be obtained.

As described above, in the step (2), the base material is laminated on the surface side of the metal foil with the resin layer on which the pattern is formed. The base material has a plate-like or sheet-like shape, and examples of the constituent material thereof include a composite material of an organic material such as a resin and an inorganic material such as glass cloth and an inorganic filler. For example, when the base material is composed of a resin, a thermoplastic resin and a thermosetting resin in a semi-cured state can be mentioned. When the base material is a thermoplastic resin, the resin includes polyvinyl acetal resin, polytetrafluoroethylene resin, polycycloolefin resin, liquid crystal polymer, polyphen ether resin, polyimide resin, polyether ether ketone resin, and polyether. Examples thereof include imide resin, polyphenylene sulfide resin, polysulfone resin, polyethersulfone resin, polyarylate resin, polycarbonate resin and the like. The thermosetting resin referred to here includes modified polyphenylene ether resin, bismaleimide resin, epoxy resin, thermosetting polyimide resin, fluororesin, phenol resin, triazine resin, cyanate resin, benzoxazine resin, unsaturated polyester resin, and bis. There are maleimide triazine resin, polyurethane resin and the like, and among them, those capable of forming a B stage state are preferable. In this case, the substrate may contain any inorganic or organic filler.

The thickness of the base material is appropriately set according to the intended use of the laminated body, but is generally preferably 50 μm or more and 2000 μm or less.

In the step (2), the metal leaf with the resin layer and the base material are overlapped and crimped so that the surface on which the pattern is formed in the metal foil with the resin layer described above faces the base material.
This crimping condition can be appropriately adjusted according to the melt viscoelasticity of the base material and the pattern transferability. It is preferable to use it under the conditions of 0.15 MPa or more and 5 MPa or less.

Next, in the step (3), the wiring laminate (the pattern is formed on the base material) by mechanically peeling the resin layer (A) from the metal foil (B) (and the base material if necessary). In the present specification, it may be simply referred to as "laminated body"). The mechanical peeling can be performed, for example, by using a manual peeling device, a peeling device using an auto peeler, or the like. When the base material is composed of a thermosetting resin, the wiring laminate is further heated to completely cure the base material.

In the method for producing a laminated body of the present embodiment, since the metal foil with a resin layer having the specific resin layer (A) is used, there is no resin residue on the pattern surface of the laminated body. Therefore, the laminate is excellent in cleanliness of the pattern surface. Further, for example, when the surface of the pattern is surface-treated, the laminated body has an advantage that the surface treatment can be uniformly performed and the state of the obtained pattern surface becomes homogeneous. Examples of such a surface treatment method include roughening treatment, soft etching, and various precious metal plating treatments in addition to cleaning with water or the like. As the roughening treatment, various construction methods such as a chemical etching method, a physical etching method, and an electrolytic method can be adopted. The laminate obtained by the method of the present embodiment has high heat resistance and reliability because there is almost no resin residue on the surface of the wiring pattern.

The laminate obtained as described above has high reliability attached to printed wiring boards such as rigid multilayer wiring boards and flexible printed wiring boards, wiring for display panels, and intermediate layers of window glass. It can be suitably used for wiring, defrosters, defoggers, wirings for solar cell panels, and the like.

As described above, the method for producing the metal leaf with a resin layer and the laminate of the present invention has been described based on the preferred embodiment, but the present invention is not limited to the above embodiment. For example, the metal leaf with a resin layer of the present invention may be applied to the method for producing a laminated body in which the step (1) is performed, for example, by an additive method. Further, in the present invention, as described above, the metal foil with a resin layer does not require a support such as polyethylene terephthalate to be laminated on the surface of the resin layer (A) on the opposite side of the metal foil (B). However, it goes without saying that a form in which such a support is provided and the support is peeled off together with the resin layer (A) at the time of transfer is also included in the method for producing a metal foil with a resin layer and a laminate of the present invention. Nor. Further, not only in the method for producing the first laminated body of the present invention, but also in the method for producing the second laminated body of the present invention, the adhesive layer is broken at the time of peeling from the above-mentioned metal foil or the like in Patent Documents 1 and 2. And, it is possible to solve the problem that a resin film as a support is required in addition to the adhesive layer on the metal foil.

Hereinafter, the present invention will be described in more detail by way of examples. However, the scope of the invention is not limited to such examples. Unless otherwise specified, "%" means "mass%".
The components used in the preparation of the resin composition in Examples and Comparative Examples are as follows.
1. 1. Styrene-butadiene copolymer (Examples and Comparative Examples)
(1) SB1
Sample: JSR Corporation TR2250
Number average molecular weight Mn: 100,000
Styrene unit content: 52% by weight
(2) SB2
Sample: JSR Corporation TR2003
Number average molecular weight Mn: 100,000
Styrene unit content: 43% by weight

2. 2. Styrene compounds (Examples and Comparative Examples)
(1) ST1
Polystyrene (DIC Corporation CR2500)
Number average molecular weight Mn: 230,000
(2) ST2
2,4-Diphenyl-4-methyl-1-pentene: 67% by mass
Polystyrene (DIC Corporation CR2500): 33% by mass
Number of mixture of the above two components mixed in the above ratio Average molecular weight Mn: 76,000

3. 3. Polyphenylene ether resin (Examples and Comparative Examples)
Mitsubishi Gas Chemical Company Limited OPE-2St (1200)
Number average molecular weight Mn: 1,150

4. Acrylic resin-based composition (comparative example only)
Butyl-2-methyl-acrylate: with respect to 100 parts by mass
Acrylic acid: 10 parts by mass Isocyanate-based cross-linking agent (Nippon Polyurethane Industry Co., Ltd. L-45): 3 parts by mass Benzotriazole: 3 parts by mass

[Example 1]
A metal foil with a resin layer in which a resin layer (A) and a copper foil as a metal foil (B) were laminated in this order was prepared by the following procedure.
First, the copper foil is formed by an electrolytic method and has a surface roughness (Rzjis) of 0.8 μm on the resin layer (A) side, a surface roughness (Rzjis) of 1.5 μm on the opposite side, and a thickness of 18 μm. It was.

On the other hand, the resin composition having the composition shown in Table 1 below is dissolved in toluene as a solvent to prepare a resin varnish having a resin solid content of 25%, coated on the copper foil, air-dried, and then at 150 ° C., 3 After a minute of heat treatment, a metal foil with a resin layer having a thickness of the resin layer (A) of 50 μm was obtained.

A resist mask was formed on the surface of the exposed metal foil (B) using a photoresist (thickness 20 μm). Next, a piece (150 mm sq.) In which a wiring pattern (line / space (L / S) of the wiring forming portion: 100 μm / 100 μm) was formed by irradiating with ultraviolet rays using a photomask masking a portion forming the pattern. ) Was formed, and then development was carried out using a 5% solution of sodium carbonate as a developing solution to remove parts other than the wiring pattern portion to form an etching resist layer. Etching was performed by immersing a metal foil with a resin layer in an etching solution (an aqueous solution having a concentration of cupric chloride of about 135 g / L and a concentration of hydrochloric acid of 105 g / L). After etching, the circuit was washed with water, the resist was removed with a 10% aqueous sodium hydroxide solution, washed again with water, and dried to obtain a metal foil with a resin layer for transfer on which a wiring pattern was formed. rice field.

Next, the surface of the metal foil (B) in the metal leaf with a resin layer for transfer on the opposite side to the resin layer was superposed on the precursor (manufactured by Mitsubishi Gas Chemical Company, Limited: GHPL-830NS, thickness 100 μm). Pressurization was performed at a pressure of 2 MPa for 60 seconds to obtain a wiring laminate precursor in which the wiring pattern of the transfer laminate was embedded in the prepreg.
The stacking temperature was set to the following two types.
(1) Laminating temperature 1: 90 ° C.
(2) Lamination temperature 2: 130 ° C
The following evaluation was performed on the obtained wiring laminate precursor.

〔evaluation〕
<Measurement of peel strength>
Regarding the peel strength Pr between the resin layer (A) and the metal foil (B), the metal foil in the wiring laminate precursor laminated at 90 ° C. used the region of the solid pattern, and JIS C6481 (tensile speed: 50 mm / min). Measured according to. The measurement results are shown in Table 1.
In Comparative Examples 1 to 5, the peel strength Pr could not be measured because the resin layer (A) was broken due to the peeling.

<Evaluation of peeling durability and peeling residue of resin layer>
Further, the resin layer was evaluated at the following two peeling speeds.
(1) Peeling speed 1: 50 mm / min
(2) Peeling speed 2: 300 mm / min
The resin layer (A) of the wiring laminate precursor was mechanically peeled off using a peeler to obtain a wiring laminate to which the wiring pattern was transferred.
In this laminated body, it was confirmed that the wiring pattern was almost completely embedded in the surface of the insulating sheet made of the cured resin, and that the surface of the insulating sheet and the surface of the wiring pattern were located on substantially the same plane.
After that, the prepreg resin of the wiring laminate was further cured under the conditions of a pressure of 3.0 MPa, 220 ° C., and 90 minutes to obtain a wiring laminate.
Further, the surface of the wiring pattern after peeling of the resin layer (A) is blackened using a mixed solution of sodium chlorite and sodium hydroxide, and a reduction treatment using a mixed solution of dimethylamine borane and sodium hydroxide. It was roughened.
At the time of peeling, the breaking durability of the resin layer (A) was visually confirmed. In addition, after the blackening treatment, the pieces in which the wiring pattern blackening treatment defect occurred due to the microscopic residue of the resin layer (A) were visually confirmed and confirmed with a 50x stereomicroscope, and were evaluated according to the following evaluation criteria. Judgment was made based on. (The numerical value of% indicates the defect rate (the ratio of the pieces in which the processing defect occurred out of the observed 20 pieces)).
(Evaluation criteria)
AA: No resin breakage and blackening treatment defect rate 0% (best)
A: No resin breakage and blackening treatment defect rate of more than 0% and 10% or less (good)
B: No resin breakage and blackening treatment defect rate of more than 10% and 20% or less (possible)
C: Resin breaks and / and cannot be peeled off, and the residual defect rate on the wiring pattern exceeds 20% (impossible).

<Storage modulus>
The storage elastic modulus is measured for the resin layer (A) after peeling from the wiring pattern by a dynamic viscoelasticity measuring device (DMA) in accordance with the tensile vibration-non-resonant method described in JIS K7244 (1999). Measured the storage elastic modulus performed at an atmospheric atmosphere, a frequency of 1 Hz, and a heating rate of 5 ° C./min to obtain a storage elastic modulus E'at 30 ° C.

[Examples 2, 4 to 8, Comparative Examples 1 to 5]
The composition of the resin in the resin layer (A) was the same as that of Example 1 except that the composition was the same as that of Table 1. Comparative Example 5 is an example in which the same components as the adhesive layer of Patent Document 2 are used for forming the resin layer.

[Example 3]
In this embodiment, the copper foil with a carrier manufactured by the procedure shown in the following (1) to (3) was used as the metal foil, the composition of the resin in the resin layer was as shown in Table 1, and the carrier was attached. Example 1 except that a resin layer (A) was formed on the surface of the copper foil opposite to the carrier of the ultrathin copper foil, and then the carrier was manually and mechanically peeled off to obtain a copper foil with a resin layer. I did the same. The peel strength Pc between the carrier and the copper foil in the copper foil with a carrier was measured as follows.
(1) Production of electrolytic copper foil for carriers A copper sulfate acidic copper solution is used as the copper electrolytic solution, a rotating electrode drum made of titanium having a surface roughness Ra of 0.20 μm is used for the cathode, and DSA (dimensional stability) is used for the anode. Using an anode), electrolysis was performed at a solution temperature of 45 ° C. and a current density of 55 A / dm ² to obtain a carrier electrolytic copper foil (hereinafter referred to as copper foil A) having a thickness of 12 μm.
(2) Formation of Organic Peeling Layer (Second Peeling Layer) CBTA containing 1000 wt ppm of CBTA (carboxybenzotriazole), 150 g / L of sulfuric acid and 10 g / L of copper on the drum surface side of the pickled copper foil A. It was immersed in an aqueous solution at a liquid temperature of 30 ° C. for 30 seconds and pulled up. In this way, the CBTA component was adsorbed on the drum surface side of the copper foil to form the CBTA layer as an organic release layer.
(3) Formation of Copper Foil An ultrathin copper foil having a current density of 8 A / dm ² and a thickness of 7 μm is placed on the organic peeling layer in an acidic copper sulfate solution with respect to the drum surface side of the copper foil A on which the organic peeling layer is formed. Formed in. The surface roughness (Rzjis) of the surface of this ultrathin copper foil (the surface opposite to the organic peeling layer) was 0.8 μm.

<Peeling strength Pc between carrier and metal foil>
The peel strength Pc between the carrier and the metal foil was measured according to JIS C6481 for a laminate in which the copper foil of the copper foil with a carrier and the glass substrate were attached with double-sided tape (tensile speed: 50 mm / min). The peel strength Pc was 15 gf / cm.

As shown in Table 1, in each embodiment, when the resin layer (A) is peeled from the wiring pattern, the resin layer (A) is not broken inside the resin layer, and the resin layer (A) is separated from the metal foil (B). It was possible to peel off stably at the interface, and no surface treatment unevenness was observed. On the other hand, in Comparative Examples 1 to 5, the resin layer was broken during peeling, and uneven surface treatment was observed.
Therefore, in the method for producing a laminated body of the present invention, by using the resin layer (A) having a specific resin structure, the resin layer (A) can be stably peeled off without breaking, and the resin residue on the surface of the wiring pattern remains. It is clear that there are few.

According to the method for producing a laminated body and the metal leaf with a resin layer of the present invention, the resin layer is stable without breaking when the resin layer is mechanically peeled off after the pattern is transferred without using a support such as polyethylene terephthalate. It is possible to peel off.
Further, according to the method for producing a laminated body and the metal foil with a resin layer of the present invention, it is possible to extremely reduce the resin residue on the surface of the metal foil after the resin layer is mechanically peeled off. Therefore, according to the method for producing a laminated body and the metal leaf with a resin layer of the present invention, a laminated body in which a metal wiring pattern having excellent uniformity in the surface state of the wiring pattern is formed can be easily formed by a transfer method.

Claims (13)

A step of forming a predetermined pattern by etching the metal foil in a metal foil with a resin layer having a metal foil and a resin layer.
A step of laminating a base material on the surface side of the metal foil with a resin layer on which the pattern is formed, and
The step of peeling off the resin layer is provided.
The resin layer mainly contains a styrene-butadiene copolymer and further contains a styrene-based compound.
The styrene-based compound is at least one selected from an oligomer and a polymer having a styrene-based monomer as a constituent unit and the oligomer or a derivative of the polymer, and the styrene-based compound which is the polymer is a homopolymer of the styrene-based monomer or styrene. It is a copolymer of two or more kinds of monomers selected from the system monomers.
In the resin layer, the styrene-based compound is contained in an amount of 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the styrene-butadiene copolymer.
A method for producing a laminate having a metal pattern, wherein the resin layer has a storage elastic modulus at 30 ° C. of 0.1 GPa or more and 0.32 GPa or less. The production method according to claim 1, wherein the resin layer has a storage elastic modulus at 30 ° C. of 0.15 GPa or more. The production method according to claim 1 or 2, wherein the resin layer contains 1 part by mass or more and 60 parts by mass or less of the polyphenylene ether resin with respect to 100 parts by mass of the styrene-butadiene copolymer. The production method according to any one of claims 1 to 3, wherein the resin layer contains 45% by mass or more and 80% by mass or less of the styrene-butadiene copolymer with respect to the resin component in the resin layer. The metal leaf with a resin layer has a peeling layer and a carrier on the surface opposite to the resin layer with the metal foil sandwiched in this order, and after the carriers are peeled off in the peeling layer, the metal foil is attached. The manufacturing method according to any one of claims 1 to 4, wherein a step of forming a predetermined pattern by etching the metal foil on the metal foil is performed. The manufacturing method according to any one of claims 1 to 5, wherein the metal foil and the resin layer are in direct contact with each other. The production method according to claim 5, wherein the peel strength Pr between the metal foil and the resin layer is larger than the peel strength Pc between the carrier and the metal foil. The peel strength Pc is 1 gf / cm or more and 50 gf / cm or less.
The manufacturing method according to claim 7, wherein the peel strength Pr is 2 gf / cm or more and 100 gf / cm or less. In a metal foil with a resin layer having a metal foil and a resin layer for peeling,
The metal foil and the resin layer are directly in contact with each other and laminated.
The resin layer mainly contains a styrene-butadiene copolymer and further contains a styrene-based compound.
The styrene-based compound is at least one selected from an oligomer and a polymer having a styrene-based monomer as a constituent unit and the oligomer or a derivative of the polymer, and the styrene-based compound which is the polymer is a homopolymer of the styrene-based monomer or styrene. It is a copolymer of two or more kinds of monomers selected from the system monomers.
In the resin layer, the styrene-based compound is contained in an amount of 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the styrene-butadiene copolymer.
The resin layer is a metal foil with a resin layer having a storage elastic modulus at 30 ° C. of 0.1 GPa or more and 0.32 GPa or less. The metal leaf with a resin layer according to claim 9, wherein the resin layer contains 1 part by mass or more and 60 parts by mass or less of the polyphenylene ether resin with respect to 100 parts by mass of the styrene-butadiene copolymer. The metal leaf with a resin layer according to claim 9 or 10, wherein the resin layer contains 45% by mass or more and 80% by mass or less of the styrene-butadiene copolymer with respect to the resin component in the resin layer. It is used as a release layer of the resin layer in a metal foil with a resin layer in which the metal foil and the resin layer are directly in contact with each other and laminated. The resin layer mainly contains a styrene-butadiene copolymer and is further styrene-based. The styrene-based compound containing a compound is at least one selected from an oligomer and a polymer having a styrene-based monomer as a constituent unit and the oligomer or a derivative of the polymer, and the styrene-based compound which is the polymer is a styrene-based monomer. It is a homopolymer of the above or a copolymer of two or more kinds of monomers selected from styrene-based monomers.
The styrene-based compound is contained in an amount of 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the styrene-butadiene copolymer, and the resin layer has a storage elastic modulus of 0.1 GPa or more and 0.32 GPa or less at 30 ° C. Is used as a release layer. This is a method in which a resin layer in a metal foil with a resin layer in which a metal foil and a resin layer are directly in contact with each other and laminated is used as a release layer. The resin layer mainly contains a styrene-butadiene copolymer and further styrene. The styrene-based compound containing a system compound is at least one selected from an oligomer and a polymer having a styrene-based monomer as a constituent unit and the oligomer or a derivative of the polymer, and the styrene-based compound which is the polymer is a styrene-based monomer. It is a copolymer of two or more kinds of monomers selected from the homopolymer of the above or a styrene-based monomer.
The styrene-based compound is contained in an amount of 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the styrene-butadiene copolymer, and the resin layer has a storage elastic modulus of 0.1 GPa or more and 0.32 GPa or less at 30 ° C. Is, how to use.