JP7736038B2 - Method for manufacturing a resin sheet with a protective film - Google Patents

Description

The present invention relates to a method for manufacturing a resin sheet with a protective film.

Circuit boards such as printed wiring boards and semiconductor package substrates are widely used in various electronic devices. A known method for manufacturing circuit boards is the build-up method, in which insulating layers and conductor layers are alternately stacked on an inner layer substrate. The insulating layer is manufactured, for example, using a resin sheet in which a resin composition layer is formed on a support. Specifically, the resin sheet is laminated onto the inner layer substrate to form a resin composition layer, and the resin composition layer is then cured to form the insulating layer (Patent Document 1). Such resin sheets may be provided with a protective film that covers the resin composition to protect the resin composition layer during storage and transportation.

Japanese Patent Application Laid-Open No. 2020-23714

Foreign matter can become mixed into the resin composition layer of a resin sheet. Such foreign matter can reduce the yield of the wiring that forms the circuit. Therefore, in conventional resin sheet manufacturing methods, efforts have been made to remove such foreign matter. For example, foreign matter has been removed by filtering the resin varnish used to form the resin composition layer.

In recent years, the need for miniaturization of electronic devices and electronic components has led to demands for finer and denser wiring. As wiring becomes finer and denser, smaller foreign particles than before can interfere with wiring formation. For example, small foreign particles on the order of several tens of microns can interfere with wiring formation. However, with conventional technology, it has been difficult to avoid yield reductions caused by such small foreign particles.

The present invention was devised in light of the above-mentioned problems, and aims to provide a method for manufacturing a resin sheet with a protective film that can eliminate foreign matter and improve the yield of wiring formation.

The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, the present inventors have found that the above-mentioned problems can be solved when a method for producing a resin sheet with a protective film, which includes, in this order, a support having a release layer, a resin composition layer containing a curable resin composition, and a protective film, includes the steps of contacting a first dust removal roller having an adhesive strength within a specific range with the release layer side of the support, forming a resin composition layer on the release layer side of the support, contacting a second dust removal roller having an adhesive strength within a specific range with the first surface of the protective film, and laminating the resin composition layer and the first surface of the protective film, thereby completing the present invention.
That is, the present invention includes the following.

[1] A method for producing a resin sheet with a protective film, comprising, in this order: a support having a release layer, a resin composition layer containing a curable resin composition, and a protective film;
The manufacturing method comprises:
bringing a first dust removal roller into contact with the release layer side of the support;
forming a resin composition layer on a surface of the support on which the release layer is formed;
contacting a second dust removal roller with the first surface of the protective film;
laminating the resin composition layer and the first surface of the protective film;
The first dust removal roller has an adhesive strength of less than 2.9 N/100 ^mm2 ;
A method for producing a resin sheet with a protective film, wherein the second dust removal roller has an adhesive strength of less than 2.9 N/100 ^mm2 .
[2] The method for producing a resin sheet with a protective film according to [1], wherein the step of forming a resin composition layer on the release layer side of the support comprises applying a liquid curable resin composition.
[3] The method for producing a resin sheet with a protective film according to [1] or [2], wherein the production method includes a step of contacting a third dust removal roller with the surface of the support opposite to the release layer.
[4] The method for producing a resin sheet with a protective film according to any one of [1] to [3], wherein the production method includes a step of contacting a fourth dust removal roller with a second surface of the protective film opposite the first surface.
[5] The method for producing a resin sheet with a protective film according to any one of [1] to [4], wherein the curable resin composition contains a curable resin and an inorganic filler.

The present invention provides a method for manufacturing a resin sheet with a protective film that can eliminate foreign matter and improve the yield of wiring formation.

FIG. 1 is a front view schematically showing a laminated resin sheet manufacturing apparatus according to a first embodiment of the present invention. FIG. 2 is a front view schematically showing a laminated resin sheet manufacturing apparatus according to a second embodiment of the present invention.

The present invention will be described below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be modified and implemented as desired without departing from the scope of the claims and their equivalents.

<Outline of the method for manufacturing a resin sheet with a protective film>
In a manufacturing method according to one embodiment of the present invention, a resin sheet with a protective film is manufactured, which comprises, in this order, a support having a release layer, a resin composition layer containing a curable resin composition, and a protective film. In the following description, the "resin sheet with a protective film" may be referred to as a "laminated resin sheet."

The method for producing a laminated resin sheet according to this embodiment includes the steps of:
a step (I) of contacting a first dust removal roller having an adhesive strength within a specific range with the release layer side of the support;
Step (II) of forming a resin composition layer on the release layer side of the support;
(III) contacting a second dust removal roller having an adhesive strength within a specific range with the first surface of the protective film;
(IV) a step of bonding the resin composition layer to the first surface of the protective film;
Includes:

The method for producing a laminated resin sheet according to the present embodiment further includes a step (V) of bringing a third dust removal roller into contact with the surface of the support opposite to the release layer.
Preferably, the composition comprises
a step (VI) of contacting a fourth dust removal roller with a second surface of the protective film opposite to the first surface;
It is preferred that the compound contains:

The manufacturing method according to this embodiment makes it possible to easily manufacture a laminated resin sheet (a resin sheet with a protective film) that effectively removes foreign matter and improves the yield of wiring formation.

<Step (I): Removal of dust from the release layer side of the support>
The manufacturing method according to this embodiment produces a laminated resin sheet using a support having a release layer. The support has a release surface on the release layer side and a back surface on the opposite side of the release surface. Generally, the support has the release layer as the outermost layer, so that the release layer is exposed on the release surface of the support. For example, a sheet having a base layer and a release layer formed on the base layer can be used as such a support.

The method for manufacturing a laminate resin sheet according to this embodiment includes step (I) of contacting a first dust removal roller with the release surface of the support (i.e., the surface on the release layer side). The first dust removal roller has an adhesive strength within a specific range. Therefore, by contacting the first dust removal roller with the release surface of the support, foreign matter adhering to the release surface can be transferred to the first dust removal roller, thereby removing the foreign matter from the release surface. This prevents foreign matter from being mixed into the resin composition layer during the manufacturing process of the laminate resin sheet. Here, "mixing" foreign matter into the resin composition layer includes both the penetration of foreign matter into the resin composition layer and the adhesion of foreign matter to the surface of the resin composition layer.

Typically, the first dust removal roller has a peripheral surface as an adhesive surface, and this peripheral surface has an adhesive strength within a specific range. The adhesive strength of the first dust removal roller is typically less than 2.9 N/100 ^mm² , preferably 2.7 N/100 ^mm² or less. When the adhesive strength is less than the upper limit, it is possible to prevent wrinkles from forming on the support due to contact with the first dust removal roller, and to prevent a part or all of the release layer from peeling off from the support due to contact with the first dust removal roller. The lower limit is not particularly limited, but is preferably 0.6 N/100 ^mm² or more, more preferably 1.0 N/100 mm² or ^more , from the viewpoint of more effectively removing foreign matter from the release surface of the support and significantly improving the yield of wiring formation.

The adhesive strength can be measured as the maximum load when the measuring part of an adhesive strength tester (for example, the "A3-10N" manufactured by Isshin Sangyo Co., Ltd.; the surface of the measuring part that comes into contact with the adhesive surface is a flat surface made of metal such as stainless steel) is pressed against the adhesive surface and the measuring part is pulled back perpendicular to the adhesive surface to peel it off. Specific measurement conditions can be those described in the "Method for measuring the adhesive strength of a dust removal roller" in the Examples section below.

The first dust removal roller may be, for example, a roller with an adhesive surface made of a polymer compound (such as silicone rubber or non-silicone rubber) that exhibits adhesiveness to foreign matter. The roller surface length of the first dust removal roller can be set according to the width of the support. The diameter of the first dust removal roller is not particularly limited as long as it can remove foreign matter adhering to the release surface of the support. The first dust removal roller may be used alone or in combination of two or more.

The first dust removal roller may be a commercially available product. Examples of the first dust removal roller include polymer rubber dust removal rollers manufactured by YanGo (RUS series, HSS series, LPS series, SRR series, etc.), dust removal rollers manufactured by TEKNEK Corporation, and dust removal rollers manufactured by C.M. Systems (CTR-S series).

The first dust removal roller and the support preferably come into contact with each other at an appropriate contact pressure. In one example, the contact pressure between the first dust removal roller and the support is preferably in the range of 0.01 MPa to 0.1 MPa, and more preferably 0.02 MPa to 0.08 MPa.

There are no limitations on the method of contact between the first dust removal roller and the release surface of the support. For example, contact may be achieved by rolling the first dust removal roller over the release surface of the fixed support. From the perspective of efficient foreign matter removal, it is preferable to contact the first dust removal roller and the release surface of the support by transporting the support so that it contacts the adhesive surface of the first dust removal roller. Since the first dust removal roller typically has an adhesive surface on its circumferential surface, it is preferable to transport the support so that the release surface contacts the circumferential surface of the first dust removal roller. The first dust removal roller may rotate when it comes into contact with the release surface of the support. In this case, the first dust removal roller may rotate in response to the transport of the support, or may be rotated by a driving force applied from a driving device such as a motor. The transport direction of the support and the rotation direction of the first dust removal roller are generally the same.

Step (I) may optionally include removing foreign matter adhering to the first dust removal roller. By removing foreign matter adhering to the first dust removal roller, it is possible to prevent foreign matter from accumulating on the first dust removal roller and reducing the adhesive strength of the first dust removal roller, and it is possible to stably and effectively remove foreign matter adhering to the release surface of the support for an extended period of time.

There are no limitations on the method for removing foreign matter from the first dust removal roller. For example, foreign matter may be removed from the first dust removal roller by contacting a first suction roller for removing foreign matter from the first dust removal roller with the first dust removal roller and transferring the foreign matter adhering to the first suction roller. Specifically, a first suction roller having an adhesive surface on its circumferential surface may be prepared, and the adhesive surface of the first suction roller may be brought into contact with the circumferential surface of the first dust removal roller to remove foreign matter from the first dust removal roller. The first suction roller may rotate when in contact with the first dust removal roller. In this case, the first suction roller may rotate in response to the rotation of the first dust removal roller, or may be driven to rotate by a driving force provided by a driving device such as a motor.

The first suction roller may be, for example, a roller provided with an adhesive layer on its peripheral surface that can attract dust and other foreign matter. To effectively remove foreign matter from the first dust removal roller, it is preferable that the adhesive strength of the first suction roller be greater than that of the first dust removal roller. This first suction roller may be a commercially available product, such as the dust transfer adhesive tape rolls "Gapless TMULT" and "Gapless TMSRR" manufactured by YanGo Co., Ltd.; or an adhesive roller manufactured by TEKNEK Co., Ltd. One first suction roller may be used alone, or two or more may be used in combination.

The removal of foreign matter from the release surface of the support by the first dust removal roller and the removal of foreign matter from the first dust removal roller by the first suction roller may be performed simultaneously or asynchronously.

<Step (II): Formation of Resin Composition Layer>
The method for producing a laminated resin sheet according to this embodiment includes step (II) of forming a resin composition layer on the release surface of a support (i.e., the surface on the release layer side). In step (II), a resin composition layer is formed on the release surface of the support from which foreign matter has been removed by contact with a first dust removal roller. Thus, step (II) is performed after step (I). Step (II) provides a resin sheet comprising a support and a resin composition layer formed on the release surface of the support.

There are no limitations on the method for forming the resin composition layer. For example, a resin composition layer may be formed on the release surface of the support by laminating a previously prepared resin composition layer on the release surface. From the perspective of significantly increasing the yield of wiring formation by reducing the chance of foreign matter adhering, it is preferable to form the resin composition layer by a method that includes applying a liquid curable resin composition to the release surface of the support.

For example, if the curable resin composition is liquid in the application environment, the curable resin composition may be applied to the release surface of the support. Alternatively, for example, the non-volatile components of the curable resin composition and a solvent may be mixed to obtain a liquid curable resin composition, and the resulting liquid curable resin composition may be applied to the release surface of the support. Hereinafter, a liquid curable resin composition containing a solvent may be referred to as a "resin varnish." A resin composition layer can be formed by applying the curable resin composition.

There are no limitations on the method for applying the liquid curable resin composition; for example, it can be applied using an application device such as a die coater.

From the time foreign matter is removed in step (I) until the time the resin composition layer is provided in step (II), it is preferable that the release surface of the support be in a non-contact state, i.e., not in contact with other members. Therefore, when a laminated resin sheet is produced while transporting the support through a predetermined transport path, it is preferable that no members (e.g., transport rollers) that come into contact with the release surface of the support be provided in the section of the transport path between the first dust removal roller and the coating device.

Step (II) may, if necessary, include drying the liquid curable resin composition after application. Typically, when a resin varnish containing a solvent is applied, step (II) includes drying the applied resin. Drying allows the solvent contained in the resin composition layer to be removed.

Drying may be carried out by, for example, heating or blowing hot air. Drying conditions are not particularly limited, but drying is typically carried out so that the solvent content in the resin composition layer is 10% by mass or less, preferably 5% by mass or less. For example, if a resin varnish containing 30% to 60% by mass of solvent is applied, drying may be carried out at 50°C to 150°C for 3 to 10 minutes, although this varies depending on the boiling point of the solvent.

By step (II), a resin composition layer can be formed on the release surface of the support. This resin composition layer contains a curable resin composition, and preferably contains only a curable resin composition. The thickness of the resin composition layer is preferably set according to the thickness of the insulating layer formed using the resin composition layer. Specific examples include a thickness of preferably 200 μm or less, more preferably 70 μm or less, and particularly preferably 50 μm or less. The lower limit of the thickness of the resin composition layer is not particularly limited, but can be 5 μm or more, 10 μm or more, etc.

<Step (III): Removal of dust from the first surface of the protective film>
The protective film used in the manufacturing method according to this embodiment has a first surface and a second surface opposite to the first surface. The first surface of the protective film corresponds to the surface to be bonded to the resin composition layer.

The method for manufacturing a laminated resin sheet according to this embodiment includes step (III) of contacting a second dust removal roller with the first surface of the protective film. The second dust removal roller has an adhesive strength within a specific range. Therefore, by contacting the second dust removal roller with the first surface of the protective film, foreign matter adhering to the first surface can be transferred to the second dust removal roller, thereby removing the foreign matter from the first surface. This prevents foreign matter from being mixed into the resin composition layer during the manufacturing process of the laminated resin sheet.

Typically, the second dust removal roller has a peripheral surface serving as an adhesive surface, and this peripheral surface has an adhesive strength within a specific range. The adhesive strength of the second dust removal roller is typically less than 2.9 N/100 ^mm² , preferably 2.7 N/100 ^mm² or less. When the adhesive strength is less than the upper limit, the generation of wrinkles in the protective film due to contact with the second dust removal roller can be suppressed. The lower limit is not particularly limited, but is preferably 0.6 N/100 ^mm² or more, more preferably 1.0 N/100 ^mm² or more, from the viewpoint of more effectively removing foreign matter from the first surface of the protective film and significantly improving the yield of wiring formation. The adhesive strength of the second dust removal roller can be measured using the same method as the adhesive strength of the first dust removal roller.

The second dust removal roller may be the same as the first dust removal roller. The roller surface length of the second dust removal roller may be set according to the width of the protective film. The diameter of the second dust removal roller is not particularly limited as long as it can remove foreign matter adhering to the first surface of the protective film. The second dust removal roller may be used alone or in combination of two or more.

It is preferable that the second dust removal roller and the protective film come into contact with each other at an appropriate range of contact pressure. In one example, the range of contact pressure between the second dust removal roller and the protective film may be the same as the range of contact pressure between the first dust removal roller and the support.

There are no limitations on the method for contacting the second dust removal roller with the first side of the protective film. For example, contact may be achieved by rolling the second dust removal roller over the first side of the fixed protective film. From the perspective of efficient foreign matter removal, it is preferable to contact the first side of the protective film with the second dust removal roller by transporting the protective film so that it contacts the adhesive surface of the second dust removal roller. Since the second dust removal roller typically has an adhesive surface on its circumferential surface, it is preferable to transport the protective film so that its first side contacts the circumferential surface of the second dust removal roller. The second dust removal roller may rotate when it comes into contact with the first side of the protective film. In this case, the second dust removal roller may rotate in response to the transport of the protective film, or may be driven to rotate by a driving force provided by a driving device such as a motor. The transport direction of the protective film and the rotation direction of the second dust removal roller are generally the same.

Step (III) may optionally include removing foreign matter adhering to the second dust removal roller. By removing foreign matter adhering to the second dust removal roller, it is possible to prevent foreign matter from accumulating on the second dust removal roller and reducing the adhesive strength of the second dust removal roller, and it is possible to stably and effectively remove foreign matter adhering to the first surface of the protective film for an extended period of time.

There are no limitations on the method for removing foreign matter from the second dust removal roller. For example, foreign matter may be removed from the second dust removal roller by contacting a second suction roller for removing foreign matter from the second dust removal roller with the second dust removal roller. Specifically, as with the removal of foreign matter from the first dust removal roller, foreign matter may be removed from the second dust removal roller by contacting the adhesive surface of a second suction roller having an adhesive surface on its circumferential surface with the circumferential surface of the second dust removal roller. The adhesive strength of the second suction roller is preferably greater than that of the second dust removal roller. The second suction roller may be the same as the first suction roller, for example. The removal of foreign matter from the first surface of the protective film by the second dust removal roller and the removal of foreign matter from the second dust removal roller by the second suction roller may be performed simultaneously or asynchronously.

<Step (IV): Bonding the resin composition layer to the first surface of the protective film>
The manufacturing method according to this embodiment includes a step (IV) of bonding a resin composition layer to a first surface of a protective film. Specifically, the resin sheet obtained in step (II) is laminated with the protective film from whose first surface foreign matter has been removed in step (III), thereby bonding the resin composition layer to the first surface of the protective film. This step (IV) results in a laminated resin sheet (resin sheet with protective film) having a support, a resin composition layer, and a protective film in this order in the thickness direction. In the obtained laminated resin sheet, the resin composition layer and the protective film are usually in direct contact. Here, "direct" contact between two members means that there is no other member between the two members in contact.

Typically, the resin sheet and protective film are sandwiched between a pair of appropriate pressing members, and at least one pressing member is pressed toward the other pressing member to bond them together. From the perspective of enabling continuous lamination and increasing the manufacturing efficiency of laminated resin sheets, it is preferable to use a rotatable pressing roller as the pressing member. Examples of such pressing rollers include rubber rollers, metal rollers, and composite rollers made of a metal core and a rubber lining.

The pressure applied between the pressing members (the pressure applied to the resin sheet and protective film) is not particularly limited as long as it allows the production of a laminated resin sheet, and may be set, for example, in the range of 0.1 MPa to 3 MPa, preferably in the range of 0.2 MPa to 2.5 MPa, and more preferably in the range of 0.3 MPa to 2 MPa.

The temperature during lamination is not particularly limited as long as it allows the production of a laminated resin sheet, and may be room temperature (approximately 25°C) or heated. From the perspective of ensuring sufficient adhesion between the resin sheet and the protective film, lamination is preferably performed under heated conditions, and the temperature may be, for example, in the range of 50°C to 130°C, preferably 60°C to 120°C.

It is preferable that the first surface of the protective film is in a non-contact state with other members from the time foreign matter is removed in step (III) until it is laminated to the resin composition layer in step (IV). Therefore, when the laminated resin sheet is manufactured while transporting the protective film through a predetermined transport path, it is preferable that no member (e.g., a transport roller) that contacts the first surface of the protective film is provided in the section of the transport path between the second dust removal roller and the pressing member.

<Step (V): Removal of dust from the surface of the support opposite to the release layer>
The method for producing a laminated resin sheet according to this embodiment preferably includes a step (V) of contacting a third dust removal roller with the back surface of the support (i.e., the surface opposite the release layer). The third dust removal roller has adhesive force. Therefore, by contacting the third dust removal roller with the back surface of the support, foreign matter can be removed from the back surface. Therefore, in the process of producing a circuit board using the laminated resin sheet (particularly in the process of laminating the inner layer wiring and the resin sheet), foreign matter on the back surface of the support can be prevented from being mixed into the resin composition layer, thereby effectively increasing the yield of wiring formation.

Typically, the third dust removal roller has a peripheral surface that serves as an adhesive surface, and this peripheral surface has adhesive force. The range of adhesive force of the third dust removal roller can be the same as the range of adhesive force of the first dust removal roller, from the viewpoint of obtaining the same effect as the first dust removal roller. The adhesive force of the third dust removal roller can be measured using the same method as the adhesive force of the first dust removal roller. The third dust removal roller can be, for example, the same as the first dust removal roller. One third dust removal roller may be used alone, or two or more third dust removal rollers may be used in combination.

It is preferable that the third dust removal roller and the support be in contact with each other at an appropriate range of contact pressure. In one example, the range of contact pressure between the third dust removal roller and the support may be the same as the range of contact pressure between the first dust removal roller and the support.

There are no restrictions on the method of contact between the third dust removal roller and the back surface of the support; for example, a method similar to the method of contact between the first dust removal roller and the release surface of the support may be used.

Step (V) may be performed before step (I), after step (I), or simultaneously with step (I). From the perspective of effectively preventing foreign matter from being mixed into the resin composition layer, step (V) is preferably performed before step (IV), and more preferably before step (II).

Step (V) may optionally include removing foreign matter adhering to the third dust removal roller. By removing foreign matter adhering to the third dust removal roller, it is possible to prevent foreign matter from accumulating on the third dust removal roller and reducing the adhesive strength of the third dust removal roller, and foreign matter adhering to the back surface of the support can be removed stably and effectively over an extended period of time.

There are no limitations on the method for removing foreign matter from the third dust removal roller. For example, foreign matter may be removed from the third dust removal roller by contacting a third suction roller for removing foreign matter from the third dust removal roller with the third dust removal roller. Specifically, as with the removal of foreign matter from the first dust removal roller, foreign matter may be removed from the third dust removal roller by contacting the adhesive surface of a third suction roller having an adhesive surface on its circumferential surface with the circumferential surface of the third dust removal roller. The adhesive strength of the third suction roller is preferably greater than that of the third dust removal roller. For example, the third suction roller may be the same as the first suction roller. The removal of foreign matter from the back surface of the support by the third dust removal roller and the removal of foreign matter from the third dust removal roller by the third suction roller may be performed simultaneously or asynchronously.

<Step (VI). Removal of dust from the second surface of the protective film>
The method for producing a laminated resin sheet according to this embodiment preferably includes a step (VI) of contacting a fourth dust removal roller with the second surface of the protective film (i.e., the surface opposite to the first surface). The fourth dust removal roller has adhesive properties. Therefore, contacting the fourth dust removal roller with the second surface of the protective film can remove foreign matter from the second surface. Therefore, in the process of producing a circuit board using the laminated resin sheet (particularly in the process of laminating the inner layer wiring and the resin sheet), foreign matter on the second surface of the protective film can be prevented from being mixed into the resin composition layer, thereby effectively increasing the yield of wiring formation.

Typically, the fourth dust removal roller has a peripheral surface that serves as an adhesive surface, and this peripheral surface has adhesive force. The range of adhesive force of the fourth dust removal roller can be the same as the range of adhesive force of the second dust removal roller, from the viewpoint of obtaining the same effect as the second dust removal roller. The adhesive force of the fourth dust removal roller can be measured using the same method as the adhesive force of the first dust removal roller. The fourth dust removal roller can be, for example, the same as the second dust removal roller. One fourth dust removal roller may be used alone, or two or more fourth dust removal rollers may be used in combination.

It is preferable that the fourth dust removal roller and the protective film be in contact with each other at an appropriate range of contact pressure. In one example, the range of contact pressure between the fourth dust removal roller and the protective film may be the same as the range of contact pressure between the second dust removal roller and the protective film.

There are no restrictions on the method of contact between the fourth dust removal roller and the second surface of the protective film; for example, the same method as the method of contact between the second dust removal roller and the first surface of the protective film may be used.

Step (VI) may be performed before step (III), after step (III), or simultaneously with step (III). From the viewpoint of effectively preventing foreign matter from being mixed into the resin composition layer, step (VI) is preferably performed before step (IV).

Step (VI) may optionally include removing foreign matter adhering to the fourth dust removal roller. By removing foreign matter adhering to the fourth dust removal roller, it is possible to prevent foreign matter from accumulating on the fourth dust removal roller and thereby prevent the adhesive strength of the fourth dust removal roller from decreasing, thereby enabling stable and effective removal of foreign matter adhering to the second surface of the protective film for an extended period of time.

There are no limitations on the method for removing foreign matter from the fourth dust removal roller. For example, foreign matter may be removed from the fourth dust removal roller by contacting a fourth suction roller for removing foreign matter from the fourth dust removal roller with the fourth dust removal roller. Specifically, as with the removal of foreign matter from the first dust removal roller, foreign matter may be removed from the fourth dust removal roller by contacting the adhesive surface of a fourth suction roller having an adhesive surface on its circumferential surface with the circumferential surface of the fourth dust removal roller. The adhesive strength of the fourth suction roller is preferably greater than that of the fourth dust removal roller. For example, the fourth suction roller may be the same as the first suction roller. The removal of foreign matter from the second surface of the protective film by the fourth dust removal roller and the removal of foreign matter from the fourth dust removal roller by the fourth suction roller may be performed simultaneously or asynchronously.

<Other matters related to the manufacturing method of the laminated resin sheet>
The method for producing a laminated resin sheet according to this embodiment may be carried out using a single support and a single protective film. When a single support and a single protective film are used, a single laminated resin sheet can be produced.

From the perspective of efficiently producing laminate resin sheets, it is preferable to produce long laminate resin sheets using a long support and a long protective film. The term "long" for a certain component means that the component has a length that allows it to be wound into a roll, for example, a length that is 10 times or more its width. By using a long support and a long protective film, it is possible to efficiently produce long laminate resin sheets using the roll-to-roll method.

When using a long support and protective film, the above-mentioned process is typically carried out while the support and protective film are continuously transported in the longitudinal direction. In this case, there are no particular restrictions on the transport speed of each component, such as the support, protective film, resin sheet, and laminated resin sheet, and it can be, for example, in the range of 0.1 m/min to 50 m/min.

The method for manufacturing a laminate resin sheet according to this embodiment may include any further steps in combination with the steps described above. For example, the method for manufacturing a laminate resin sheet may include a step of winding and recovering the manufactured laminate resin sheet. By winding the laminate resin sheet, a roll of the laminate resin sheet is obtained, which can be stored and transported in this rolled state.

<First specific example of production method>
[0023] Hereinafter, a first example of a method for manufacturing a laminate resin sheet according to the present embodiment will be described with reference to the drawings. Fig. 1 is a front view schematically showing an apparatus 1 for manufacturing a laminate resin sheet 50 according to the first example of the present invention. As shown in Fig. 1, the manufacturing apparatus 1 is configured to form a resin composition layer 20 on a long support 10 including a base material layer 11 and a release layer 12 to obtain a long resin sheet 30, and to laminate the resin sheet 30 with a long protective film 40 to obtain the laminate resin sheet 50.

The manufacturing apparatus 1 includes a support dust removal unit 100 that is provided to remove foreign matter from the support 10, a layer formation unit 200 that is provided to form a resin composition layer 20 on the release surface 10U of the support 10, a protective film dust removal unit 300 that is provided to remove foreign matter from the protective film 40, and a laminating unit 400 that is provided to bond the resin composition layer 20 of the resin sheet 30 to the first surface 40D of the protective film 40.

The support dust removal unit 100 includes a first dust removal roller 110 and a third dust removal roller 120, which are rotatable in the same direction as the conveyance direction of the support 10. The first dust removal roller 110 and the third dust removal roller 120 have adhesive surfaces with appropriate adhesive strength on their peripheral surfaces 110S and 120S, respectively. In this example, the first dust removal roller 110 and the third dust removal roller 120 are disposed opposite each other so that the support 10 can be conveyed between the first dust removal roller 110 and the third dust removal roller 120. The first dust removal roller 110 and the third dust removal roller 120 are biased toward each other to allow contact with an appropriate contact pressure between the peripheral surface 110S of the first dust removal roller 110 and the release surface 10U of the support 10, and between the peripheral surface 120S of the third dust removal roller 120 and the back surface 10D of the support 10.

The layer forming section 200 includes a coating device 210 and a drying device 220. The coating device 210 is configured to apply a liquid curable resin composition 21 to the release surface 10U of the support 10. The drying device 220 is configured to dry the resin composition layer 20 formed on the release surface 10U of the support 10 to remove the solvent. In this example, an example is shown in which the drying device 220 is an oven configured so that the support 10 can pass through.

The protective film dust removal unit 300 includes a second dust removal roller 310 and a fourth dust removal roller 320, which are rotatable in the same direction as the transport direction of the protective film 40. The second dust removal roller 310 and the fourth dust removal roller 320 have adhesive surfaces with appropriate adhesive strength on their peripheral surfaces 310S and 320S, respectively. In this example, the second dust removal roller 310 and the fourth dust removal roller 320 are disposed opposite each other so that the protective film 40 can be transported between them. Furthermore, the second dust removal roller 310 and the fourth dust removal roller 320 are biased toward each other to allow contact between the peripheral surface 310S of the second dust removal roller 310 and the first surface 40D of the protective film 40, and between the peripheral surface 320S of the fourth dust removal roller 320 and the second surface 40U of the protective film 40, with an appropriate contact pressure.

The laminating unit 400 includes a pair of pressure rollers 410 and 420 that are rotatable in the same direction as the conveyance direction of the resin sheet 30 and the protective film 40, and a chamber 430 that houses the pressure rollers 410 and 420. The pressure rollers 410 and 420 are arranged opposite each other so that the resin sheet 30 and the protective film 40 can be conveyed between the pressure rollers 410 and 420. A heater (not shown) is also provided within the chamber 430 to appropriately adjust the temperature within the chamber 430.

In the method for manufacturing the laminated resin sheet 50 using the manufacturing apparatus 1, the support 10 is transported and supplied to the support dust removal section 100. The support 10 supplied to the support dust removal section 100 is transported so as to pass between the first dust removal roller 110 and the third dust removal roller 120. As the support 10 passes between the first dust removal roller 110 and the third dust removal roller 120, the circumferential surface 110S of the first dust removal roller 110 comes into contact with the release surface 10U of the support 10, and the circumferential surface 120S of the third dust removal roller 120 comes into contact with the back surface 10D of the support 10 (steps (I) and (V)). Thus, foreign matter (not shown) on the release surface 10U and back surface 10D of the support 10 is removed. The support 10 is then sent to the layer formation section 200.

The support 10 sent to the layer forming unit 200 is supplied to the coating device 210. The coating device 210 coats the release surface 10U of the support 10 with a curable resin composition 21 to form a resin composition layer 20 (step (II)). The support 10 and resin composition layer 20 are then sent to the drying device 220, where the resin composition layer 20 is dried. In this example, the resin composition layer 20 is dried by passing it through an oven (drying device 220) set at an appropriate temperature for an appropriate period of time. The solvent is removed from the resin composition layer 20 by drying, resulting in a resin sheet 30 comprising the support 10 and the resin composition layer 20. This resin sheet 30 is then sent to the laminating unit 400.

In addition, in the method for manufacturing the laminated resin sheet 50 using the manufacturing apparatus 1, the protective film 40 is transported and supplied to the protective film dust removal unit 300 separately from the support 10. The protective film 40 supplied to the protective film dust removal unit 300 is transported so as to pass between the second dust removal roller 310 and the fourth dust removal roller 320. As the protective film 40 passes between the second dust removal roller 310 and the fourth dust removal roller 320, the circumferential surface 310S of the second dust removal roller 310 comes into contact with the first side 40D of the protective film 40, and the circumferential surface 320S of the fourth dust removal roller 320 comes into contact with the second side 40U of the protective film 40 (steps (III) and (VI)). Thus, foreign matter (not shown) on the first side 40D and second side 40U of the protective film 40 is removed. The protective film 40 is then sent to the laminating unit 400.

The resin sheet 30 and protective film 40 sent to the laminating unit 400 enter the chamber 430 and are transported between pressure rollers 410 and 420. As they pass between the pressure rollers 410 and 420, the resin sheet 30 and protective film 40 are pressed by the pressure rollers 410 and 420 with the resin composition layer 20 of the resin sheet 30 and the first surface 40D of the protective film 40 facing each other. Thus, the resin sheet 30 and the protective film 40 are laminated so that the resin composition layer 20 and the first surface 40D of the protective film 40 are bonded together, resulting in a long laminated resin sheet 50 comprising the support 10, resin composition layer 20, and protective film 40 in this order.

<Second specific example of the production method>
A second example of the method for manufacturing a laminate resin sheet according to the present embodiment will now be described with reference to the drawings. Fig. 2 is a front view schematically showing an apparatus 2 for manufacturing a laminate resin sheet 50 according to the second example of the present invention. As shown in Fig. 2, the manufacturing apparatus 2 according to this example is configured in the same manner as the manufacturing apparatus 1 according to the first example, except that it includes a support body dust removing unit 500 and a protective film dust removing unit 600 instead of the support body dust removing unit 100 and the protective film dust removing unit 300.

The support dust removal unit 500 includes a first dust removal roller 510 and a third dust removal roller 520. In this example, the first dust removal roller 510 and the third dust removal roller 520 are arranged in the same manner as the first dust removal roller 110 and the third dust removal roller 120 according to the first example, except that the first dust removal roller 510 and the third dust removal roller 520 are arranged at different positions in the transport direction of the support 10.

The first dust removal roller 510 is arranged so that the support 10 can be transported so that it wraps around the circumferential surface 510S of the first dust removal roller 510. Therefore, in this example, the release surface 10U of the transported support 10 can come into contact with the circumferential surface 510S of the first dust removal roller 510 with a contact pressure that corresponds to the transport tension of the support 10.

The third dust removal roller 520 is also arranged so that the support 10 can be transported so that it wraps around the circumferential surface 520S of the third dust removal roller 520. Therefore, in this example, the back surface 10D of the transported support 10 can come into contact with the circumferential surface 520S of the third dust removal roller 520 with a contact pressure that corresponds to the transport tension of the support 10.

The protective film dust removal unit 600 includes a second dust removal roller 610 and a fourth dust removal roller 620. In this example, the second dust removal roller 610 and the fourth dust removal roller 620 are arranged in the same manner as the second dust removal roller 310 and the fourth dust removal roller 320 in the first example, except that the second dust removal roller 610 and the fourth dust removal roller 620 are arranged at different positions in the transport direction of the protective film 40.

The second dust removal roller 610 is arranged so that the protective film 40 can be transported so that it wraps around the circumferential surface 610S of the second dust removal roller 610. Therefore, in this example, the first surface 40D of the transported protective film 40 can come into contact with the circumferential surface 610S of the second dust removal roller 610 with a contact pressure that corresponds to the transport tension of the protective film 40.

Furthermore, the fourth dust removal roller 620 is arranged so that the protective film 40 can be transported so that it wraps around the circumferential surface 620S of the fourth dust removal roller 620. Therefore, in this example, the second surface 40U of the transported protective film 40 can come into contact with the circumferential surface 620S of the fourth dust removal roller 620 with a contact pressure that corresponds to the transport tension of the protective film 40.

In the manufacturing method of the laminated resin sheet 50 using the manufacturing apparatus 2, the support 10 is supplied to the support dust removal section 500 and transported via the first dust removal roller 510 and the third dust removal roller 520. The support 10 supplied to the support dust removal section 500 has foreign matter (not shown) removed from the release surface 10U as it is transported in contact with the circumferential surface 510S of the first dust removal roller 510 (step (I)). The support 10 then has foreign matter (not shown) removed from the back surface 10D as it is transported in contact with the circumferential surface 520S of the third dust removal roller 520 (step (V)). The support 10 is then sent to the layer formation section 200. As in the first example, a resin composition layer 20 is formed on the release surface 10U of the support 10 in the layer formation section 200 to obtain a resin sheet 30 (step (II)), and the resin sheet 30 is then sent to the lamination section 400.

In addition, in the method for manufacturing the laminated resin sheet 50 using the manufacturing apparatus 2, the protective film 40 is supplied to the protective film dust removal unit 600 and transported via the second dust removal roller 610 and the fourth dust removal roller 620. When the protective film 40 supplied to the protective film dust removal unit 600 is transported in contact with the circumferential surface 610S of the second dust removal roller 610, foreign matter (not shown) is removed from the first surface 40D (step (III)), and when the protective film 40 is transported in contact with the circumferential surface 620S of the fourth dust removal roller 620, foreign matter (not shown) is removed from the second surface 40U (step (VI)). The protective film 40 is then sent to the laminating unit 400.

As in the first example, the resin sheet 30 and protective film 40 sent to the laminating unit 400 are laminated in the chamber 430 by pressure rollers 410 and 420 so that the resin composition layer 20 and the first surface 40D of the protective film 40 are bonded together, resulting in a long laminated resin sheet 50 comprising the support 10, resin composition layer 20, and protective film 40 in this order.

<Manufactured laminated resin sheet>
The above-described manufacturing method can produce a laminated resin sheet (a resin sheet with a protective film). This laminated resin sheet includes a resin composition layer formed on the release surface of a support. Since foreign matter has been removed from the release surface by contact with the first dust removal roller, it is possible to prevent foreign matter adhering to the release surface from being mixed into the resin composition layer.

In addition, the resin composition layer of the laminated resin sheet is in direct contact with the first surface of the protective film. Foreign matter is removed from the first surface of the protective film by contact with the second dust removal roller. This prevents foreign matter adhering to the first surface from being mixed into the resin composition layer.

Conventionally, methods for removing foreign matter from the release surface of a support and the first surface of a protective film have been proposed, but these conventional techniques typically involve the use of non-contact devices such as air blowers to remove the foreign matter. In contrast, in this embodiment, the foreign matter is removed using a contact device called a dust removal roller, which allows for effective removal of the foreign matter. The method of this embodiment is particularly advantageous in that it can effectively remove small foreign matter of 100 μm or less (preferably, several tens of μm or less).

In this way, the incorporation of foreign matter into the resin composition layer can be suppressed, and when a circuit board is manufactured using the laminated resin sheet manufactured in this embodiment, the yield of wiring formation can be increased. Specifically, it is possible to suppress the intrusion of foreign matter into the gaps between wiring, which would otherwise unintentionally reduce the insulating performance between the wiring. Furthermore, it is possible to suppress distortion of the wiring shape or chipping of the wiring in the portion above the foreign matter, which would otherwise occur when part of the wiring layer is formed on the foreign matter. Therefore, it is possible to suppress the occurrence of wiring that does not function as intended, making it possible to form the intended wiring with a high yield.

The dust removal roller used in this embodiment also has an appropriate range of adhesive strength. This prevents excessive adhesion from disrupting the transport of the support and protective film. This prevents wrinkles from forming in the support and protective film, resulting in good transportability. Furthermore, since the first dust removal roller in particular has an appropriate range of adhesive strength, it prevents the release layer of the support from adhering to the first dust removal roller and being removed from the support. This allows the support to be smoothly peeled from the insulating layer during circuit board production. This makes it possible to simplify circuit board production and improve circuit board yields.

When foreign matter on the back surface of the support is removed with the third dust removal roller, the foreign matter on the back surface can be prevented from being mixed into the resin composition layer. Furthermore, when foreign matter on the second surface of the protective film is removed with the fourth dust removal roller, the foreign matter on the second surface can be prevented from being mixed into the resin composition layer. Therefore, the incorporation of foreign matter into the resin composition layer can be effectively prevented, further increasing the yield of wiring formation.

The laminate resin sheet according to this embodiment can be preferably used to form a circuit board. In a circuit board, the laminate resin sheet is typically used to form an insulating layer. Specifically, the laminate resin sheet is preferably used to form an insulating layer by curing a resin composition layer. Because the inclusion of foreign matter in the resin composition layer can be suppressed, the laminate resin sheet according to this embodiment can improve the yield of wiring formed on the insulating layer.

In particular, compared to techniques for removing foreign matter from general sheets, the technology according to this embodiment, which can prevent foreign matter from being mixed into the resin composition layer in a laminate resin sheet used to form an insulating layer on a circuit board, has the following advantages:

When forming a wiring layer on a sheet, foreign matter on the surface of the sheet can generally hinder wiring formation. Therefore, attempts are usually made to remove the foreign matter from the surface of the sheet. However, the resin composition layer used to form the insulating layer is required to fill the irregularities on the surface of the inner layer substrate without leaving any gaps, and therefore must have properties such as being flexible enough to remain fluid at an appropriate temperature. If an attempt were made to remove foreign matter from such a flexible resin composition layer using a contact-type device, the resin composition layer could be deformed or damaged. Therefore, considering the intended use, it is difficult to remove foreign matter from the surface of the resin composition layer using a contact-type device.

Furthermore, when a resin composition layer is used to form an insulating layer for a circuit board, foreign matter adhering to the surface of the resin composition layer, as well as foreign matter inside the resin composition layer, can hinder wiring formation. Specifically, when manufacturing a circuit board, a resin composition layer, revealed by peeling off a protective film, is typically laminated with an inner layer substrate, and a resin composition layer is formed on the inner layer substrate. The resin composition layer is then cured to obtain an insulating layer, and wiring is then formed on the insulating layer. At this time, the resin composition layer provided on the inner layer substrate can be subjected to chemical or physical processing. Examples of processing include curing treatments that involve reacting a curable resin with heat or light; hole formation treatments using drills or laser light; desmearing to remove resin residue; and plating treatments for wiring formation. When these processing treatments are performed, foreign matter that was inside the resin composition layer can appear on the surface. These foreign matter that appear on the surface can then hinder wiring formation.

It was previously thought that such foreign matter inside a resin composition layer was contained in the resin composition that is the raw material for that resin composition layer. However, the present inventors have discovered that even when the resin composition is thoroughly removed by filtration, foreign matter can cause a decrease in the yield of wiring formation. They have also discovered that during the manufacturing process of laminated resin sheets, foreign matter that is so small that it was not previously considered a problem can become mixed into the resin composition layer, and that the decrease in yield caused by such small foreign matter becomes apparent as wiring becomes finer and denser.

In contrast, the laminated resin sheet manufactured using the above-described manufacturing method uses a resin composition layer that meets the properties required for forming an insulating layer, while effectively eliminating small foreign objects that could reduce the yield of wiring formation. Therefore, the laminated resin sheet of this embodiment makes it possible to improve the yield of wiring formation, which was difficult to achieve with conventional technology, and is therefore suitable for use as an insulating layer in circuit boards.

<Description of the support>
The support used in this embodiment will be described in detail below.
The support includes a release layer. The support includes the release layer as the outermost layer, so that the release layer is exposed on the outermost surface of the support. A resin composition layer is then formed on the surface of the release layer. Usually, the support includes a base layer, and the release layer is provided on the base layer.

Examples of the substrate layer include thermoplastic resin film, metal foil, and release paper, with thermoplastic resin film and metal foil being preferred. When a thermoplastic resin film is used as the substrate layer, examples of the thermoplastic resin contained in the substrate layer include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylic polymers such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, with inexpensive polyethylene terephthalate being particularly preferred.

When a metal foil is used as the substrate layer, examples of the metal foil include copper foil and aluminum foil, with copper foil being preferred. The copper foil may be a foil made of the single metal copper, or a foil made of an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.).

The surface of the base layer facing the release layer may be subjected to a surface treatment such as matte treatment, corona treatment, or antistatic treatment.

The thickness of the substrate layer is not particularly limited, but is preferably in the range of 5 μm to 75 μm, and more preferably in the range of 10 μm to 60 μm.

The release layer acts to reduce the force (peel strength) required to peel the support. Specifically, the release layer acts to reduce the force required to peel the support that is in contact with the resin composition layer or insulating layer via the release layer, compared to the force required to peel the substrate layer that is in direct contact with the resin composition layer or the insulating layer that is its cured product.

The release layer is typically formed from a release agent. Examples of the release agent include resins. Generally, resins used as release agents contain a release component that provides releasability and may further contain optional components other than the release component, as needed. Thus, in one example, the release layer contains the release component and may further contain optional components as needed. In another example, the release layer may be formed by bonding some or all of the components contained in the release agent through a reaction such as a polymerization reaction or a crosslinking reaction, followed by curing the release agent. In this example, the release layer may contain one or more components selected from the group consisting of the release component and optional components contained in the release agent, as well as their reaction products (e.g., polymers). The release component may be a compound that can reduce the surface free energy of the release layer or the static coefficient of friction of the release layer.

Release components include, for example, long-chain alkyl group-containing resins, olefin resins, fluorine compounds, and wax-based compounds.

A long-chain alkyl group-containing resin refers to a resin containing a long-chain alkyl group. Furthermore, a long-chain alkyl group typically refers to an alkyl group having 12 or more carbon atoms, preferably 16 or more. Resins containing such long carbon chains in their molecules generally have high hydrophobicity and therefore exhibit excellent mold releasability. The upper limit of the number of carbon atoms in the long-chain alkyl group may be, for example, 25 or less. Specific examples of long-chain alkyl group-containing resins include (meth)acrylic resins containing long-chain alkyl groups, such as long-chain acrylic acrylates such as tetradecyl acrylate and octadecyl acrylate; long-chain acrylic methacrylates such as tetradecyl methacrylate and octadecyl methacrylate; and polymers thereof. The term "(meth)acrylic resin" includes (meth)acrylic compounds and their polymers, unless otherwise specified. The term "(meth)acrylic compound" includes acrylic compounds containing acryloyl groups, methacryloyl compounds containing methacryloyl groups, and combinations thereof, unless otherwise specified. Furthermore, the term "polymer" includes both homopolymers and copolymers, unless otherwise specified.

Examples of olefin resins include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, and 1-dodecene.

A fluorine compound refers to a compound that contains fluorine atoms in its molecule. Specific examples of fluorine compounds include perfluoroalkyl group-containing compounds, polymers of olefin compounds that contain fluorine atoms, aromatic fluorine compounds such as fluorobenzene, and (meth)acrylic resins that contain fluorine atoms. Of these, (meth)acrylic resins that contain fluorine atoms are preferred. Examples of (meth)acrylic resins that contain fluorine atoms include fluoroalkyl acrylates such as trifluoroethyl acrylate; fluoroaryl acrylates such as pentafluorophenyl acrylate; fluoroalkyl methacrylates such as trifluoroethyl methacrylate; fluoroaryl methacrylates such as pentafluorophenyl methacrylate; and polymers thereof.

Wax-based compounds include, for example, natural waxes, synthetic waxes, and combinations thereof. Natural waxes include vegetable waxes, animal waxes, mineral waxes, and petroleum waxes. Vegetable waxes include, for example, candelilla wax, carnauba wax, rice wax, Japan wax, and jojoba oil. Animal waxes include, for example, beeswax, lanolin, and spermaceti. Mineral waxes include, for example, montan wax, ozokerite, and ceresin. Petroleum waxes include, for example, paraffin wax, microcrystalline wax, and petrolatum. Synthetic waxes include, for example, synthetic hydrocarbons, modified waxes, hydrogenated waxes, fatty acids, acid amides, amines, imides, esters, and ketones. Synthetic hydrocarbons include, for example, Fischer-Tropsch wax (also known as Sazoir wax) and polyethylene wax. Synthetic hydrocarbons may also include low-molecular-weight polymers (specifically, viscosity-average molecular weights of 500 to 20,000) selected from the group consisting of polypropylene, ethylene-acrylic acid copolymer, polyethylene glycol, polypropylene glycol, block conjugates of polyethylene glycol and polypropylene glycol, and graft conjugates of polyethylene glycol and polypropylene glycol. Modified waxes include, for example, montan wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives. The derivatives referred to here refer to compounds obtained by any of the following processes, or a combination of these: refining, oxidation, esterification, and saponification. Hydrogenated waxes include, for example, hydrogenated castor oil and hydrogenated castor oil derivatives.

The release component may be used alone or in combination of two or more types.

The amount of releasable components in the release agent is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, relative to 100% by mass of the non-volatile components of the release agent; it is preferably 90% by mass or less, more preferably 60% by mass or less, and even more preferably 40% by mass or less.

The amount of the release component in the release layer is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, relative to 100% by mass of the release layer; it is preferably 90% by mass or less, more preferably 60% by mass or less, and particularly preferably 40% by mass or less.

Optional components that may be contained in the release agent include, for example, any resin other than the release component. Examples of optional resins include epoxy resins, melamine resins, oxazoline compounds, carbodiimide compounds, polyester resins, urethane resins, and (meth)acrylic resins. Examples of optional (meth)acrylic resins include acrylic compounds such as acrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, acrylamide, N-methylolacrylamide, and diacetone acrylamide; methacrylic compounds such as methacrylic acid, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, and hydroxypropyl methacrylate; and polymers thereof. Any of the resins may be used alone or in combination of two or more.

The amount of any resin in the release agent is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 40% by mass or more, relative to 100% by mass of the non-volatile components of the release agent; it is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less.

The amount of any resin in the release layer is preferably 10% by weight or more, more preferably 20% by weight or more, and even more preferably 40% by weight or more, relative to 100% by weight of the release layer, and is preferably 90% by weight or less, more preferably 85% by weight or less, and even more preferably 80% by weight or less.

Further examples of optional components include optional additives such as lubricants, inorganic particles, organic particles, surfactants, antioxidants, and thermal initiators. One type of optional additive may be used alone, or two or more types may be used in combination. The amount of optional additive is not particularly limited, but may be, for example, 0.001% by mass or more and 10% by mass or less, relative to 100% by mass of the total of the release component and optional resin.

Examples of the above-mentioned release agents include alkyd-based release agents, polyolefin-based release agents, urethane-based release agents, melamine-based release agents, fluorine-based release agents, acrylic-based release agents, and silicone-based release agents. Among these, non-silicone-based release agents are preferred from the perspective of producing circuit boards with insulating layers that have excellent insulating properties. Furthermore, acrylic-based release agents are even more preferred from the perspective of particularly smoothly removing foreign matter. An acrylic-based release agent refers to a release agent that contains a (meth)acrylic resin as either or both of the release component and optional resin.

There are no particular restrictions on the thickness of the release layer, but it is preferably 50 nm or more, more preferably 70 nm or more, and preferably 400 nm or less, more preferably 200 nm or less, and particularly preferably 130 nm or less.

A sheet-like member is usually used as the support. The support may be a single sheet, but from the perspective of enabling continuous production of laminated resin sheets and increasing production efficiency, a long sheet is preferable. Unless otherwise specified, a long sheet refers to a sheet that is long enough to be wound into a roll, and can be, for example, a sheet that is 10 times or more long compared to its width.

The thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, and more preferably in the range of 10 μm to 60 μm.

The support can be manufactured, for example, by a method that includes applying a release agent to the surface of the base layer. The release agent may further contain a solvent in combination with the non-volatile components, such as the releasable component and optional components, described above. When the release agent contains a solvent, the method for manufacturing the support preferably includes applying the release agent and then drying it.

Aqueous solvents are preferred as the solvent, as they prevent rapid evaporation of the solvent and allow for the formation of a uniform release layer. Examples of aqueous solvents include water; and mixed solvents of water and water-soluble organic solvents such as alcohol solvents, ketone solvents, and glycol solvents. One type of solvent may be used alone, or two or more types may be used in combination. When using a solvent, the concentration of non-volatile components in the release agent is preferably 40% by mass or less, in order to ensure good coatability and the formation of a uniform release layer.

Examples of methods for applying the release agent include wire bar coating, reverse coating, gravure coating, die coating, blade coating, dip coating, air knife coating, curtain coating, and roller coating.

There are no particular restrictions on the drying temperature of the release agent. In one example, drying may be performed at a temperature range of 80°C or higher and 130°C or lower. In another example, drying may be performed at a temperature range of 160°C or higher and 240°C or lower.

A layer containing the non-volatile components of the release agent can be formed by applying a release agent to the surface of the substrate layer and drying it as necessary. This layer may be used as the release layer. Alternatively, the layer containing the non-volatile components of the release agent may be cured to obtain the release layer. Examples of curing treatments include heating and ultraviolet irradiation. Typically, the curing treatment promotes polymerization and crosslinking reactions of some or all of the components contained in the release agent, thereby curing the release agent, and a release layer made of the cured product of the release agent can be obtained.

The method for manufacturing the support may also include optional processes such as stretching, if necessary.

<Protective film explanation>
The protective film used in this embodiment will be described in detail below.
The protective film is a film laminated on the resin composition layer in order to protect the resin composition layer from physical damage and to suppress adhesion of foreign matter such as dust, etc. Since the protective film is usually not required during the production of a circuit board, the protective film is generally laminated on the resin composition layer in a peelable manner.

Examples of protective films include thermoplastic resin films and metal foils. When a thermoplastic resin film is used as the protective film, the thermoplastic resin contained in the protective film can be the same as the thermoplastic resin contained in the base layer. The protective film can also be a stretched film that has been subjected to a stretching process. When a metal foil is used as the protective film, the metal foil can be the same as the metal foil used in the base layer. Commercially available protective films include "MA430" and "MA411" (biaxially oriented polypropylene films) manufactured by Oji F-Tex Co., Ltd.

The surface of the protective film that is bonded to the resin composition layer (i.e., the first surface of the protective film) may have an arithmetic mean roughness within a specific range. Specifically, the arithmetic mean roughness of the first surface of the protective film is preferably 150 nm or more, more preferably 200 nm or more, even more preferably 250 nm or more, and preferably 2000 nm or less, more preferably 1500 nm or less, and even more preferably 1200 nm or less. The arithmetic mean roughness can be measured using a non-contact surface roughness meter. A specific example of a non-contact surface roughness meter is the "WYKO NT3300" manufactured by Veeco Instruments. The arithmetic mean roughness can be measured, for example, using a non-contact surface roughness meter in VSI mode with a 50x magnification lens and a measurement range of 121 μm x 92 μm.

The protective film may have a release layer. The release layer is usually formed as the outermost layer on the first surface side, so that the release layer can be exposed on the first surface of the protective film. The release layer of the protective film may be the same as the release layer of the support.

The thickness of the protective film is preferably 5 μm or more, more preferably 10 μm or more, and preferably 75 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less. When using a protective film with a release layer, it is preferable that the total thickness of the protective film including the release layer be within the above range.

The protective film may be a sheet of film, but from the perspective of enabling continuous production of laminated resin sheets and increasing production efficiency, it is preferable that it be a long film. Unless otherwise specified, a long film refers to a film that is long enough to be wound into a roll, and can be, for example, a film that is 10 times or more long compared to its width.

<Description of Curable Resin Composition>
The curable resin composition used in this embodiment will be described in detail below.
The curable resin composition is a curable resin composition, and can usually be cured by one or both of heat and light. As this curable resin composition, a composition containing a curable resin (A) can be used. Specific examples of the composition of the curable resin composition will be described below, but curable resin compositions other than those exemplified below may also be used.

-(A) Curing resin-
The curable resin (A) that can be contained in the curable resin composition is usually selected from the group consisting of thermosetting resins and photocurable resins. As the curable resin (A), only a thermosetting resin may be used, only a photocurable resin may be used, or a combination of a thermosetting resin and a photocurable resin may be used. Furthermore, the curable resin (A) may be used alone or in combination of two or more types.

Thermosetting resins can be resins that can be hardened when heat is applied. Examples of thermosetting resins include epoxy resins, phenolic resins, active ester resins, cyanate resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, thiol resins, and radical polymerizable resins. One type of thermosetting resin may be used alone, or two or more types may be used in combination.

In one example, it is preferable to use a combination of an epoxy resin and a resin that can react with the epoxy resin to cure the curable resin composition. Hereinafter, a resin that can react with an epoxy resin to cure the curable resin composition may be referred to as a "curing agent." Examples of curing agents include phenolic resins, active ester resins, cyanate resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, and thiol resins. Among these, phenolic resins, active ester resins, cyanate resins, and carbodiimide resins are preferred, with phenolic resins and active ester resins being more preferred. Furthermore, one type of curing agent may be used alone, or two or more types may be used in combination.

Epoxy resin is a curable resin containing epoxy groups. Examples of epoxy resins include bixylenol type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol novolac type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, anthracene type epoxy resins, glycidylamine type epoxy resins, glycidyl ester type epoxy resins, cresol novolac type epoxy resins, phenol aralkyl type epoxy resins, biphenyl type epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, naphthylene ether type epoxy resins, trimethylol type epoxy resins, tetraphenylethane type epoxy resins, isocyanurate type epoxy resins, and phenolphthalimidine type epoxy resins. One type of epoxy resin may be used alone, or two or more types may be used in combination.

From the perspective of obtaining a cured product with excellent heat resistance, it is preferable that the epoxy resin contain an aromatic structure. An aromatic structure is a chemical structure generally defined as aromatic, and also includes polycyclic aromatics and aromatic heterocycles. Examples of epoxy resins containing an aromatic structure include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol novolac type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, anthracene type epoxy resins, bisxyleneol type epoxy resins, glycidylamine type epoxy resins having an aromatic structure, glycidyl ester type epoxy resins having an aromatic structure, cresol novolac type epoxy resins, biphenyl type epoxy resins, linear aliphatic epoxy resins having an aromatic structure, epoxy resins having a butadiene structure having an aromatic structure, alicyclic epoxy resins having an aromatic structure, heterocyclic epoxy resins, spiro ring-containing epoxy resins having an aromatic structure, cyclohexanedimethanol type epoxy resins having an aromatic structure, naphthylene ether type epoxy resins, trimethylol type epoxy resins having an aromatic structure, and tetraphenylethane type epoxy resins having an aromatic structure.

The (A) curable resin preferably contains an epoxy resin having two or more epoxy groups per molecule. The proportion of epoxy resin having two or more epoxy groups per molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on 100% by mass of the non-volatile components of the epoxy resin.

Epoxy resins include those that are liquid at a temperature of 20°C (hereinafter sometimes referred to as "liquid epoxy resins") and those that are solid at a temperature of 20°C (hereinafter sometimes referred to as "solid epoxy resins"). The curable resin composition may contain only liquid epoxy resins as the epoxy resin, or only solid epoxy resins, or a combination of liquid and solid epoxy resins.

Preferably, the liquid epoxy resin is one having two or more epoxy groups per molecule.

Preferred liquid epoxy resins are bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins with an ester skeleton, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, and epoxy resins with a butadiene structure.

Specific examples of liquid epoxy resins include DIC's "HP4032," "HP4032D," and "HP4032SS" (naphthalene-type epoxy resins); Mitsubishi Chemical's "828US," "828EL," "jER828EL," "825," and "Epikote 828EL" (bisphenol A-type epoxy resins); Mitsubishi Chemical's "jER807" and "1750" (bisphenol F-type epoxy resins); Mitsubishi Chemical's "jER152" (phenol novolac-type epoxy resin); Mitsubishi Chemical's "630," "630LSD," and "604" (glycidylamine-type epoxy resins); ADEKA's "ED-523T" (glycilol-type epoxy resin); and ADEKA's "EP-3950L" and "EP-3980S." (glycidylamine type epoxy resin); ADEKA Corporation's "EP-4088S" (dicyclopentadiene type epoxy resin); Nippon Steel Chemical & Material Co., Ltd.'s "ZX1059" (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin); Nagase ChemteX Corporation's "EX-721" (glycidyl ester type epoxy resin); Daicel Corporation's "Celloxide 2021P" (alicyclic epoxy resin with an ester skeleton); Daicel Corporation's "PB-3600," Nippon Soda Co., Ltd.'s "JP-100" and "JP-200" (epoxy resins with a butadiene structure); Nippon Steel Chemical & Material's "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resin). These may be used alone or in combination of two or more.

As a solid epoxy resin, a solid epoxy resin having three or more epoxy groups per molecule is preferred, and an aromatic solid epoxy resin having three or more epoxy groups per molecule is more preferred.

Preferred solid epoxy resins include bixylenol-type epoxy resins, naphthalene-type epoxy resins, naphthalene-type tetrafunctional epoxy resins, naphthol novolac-type epoxy resins, cresol novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol AF-type epoxy resins, phenol aralkyl-type epoxy resins, tetraphenylethane-type epoxy resins, and phenolphthalimidine-type epoxy resins.

Specific examples of solid epoxy resins include DIC Corporation's "HP4032H" (naphthalene-type epoxy resin); DIC Corporation's "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resins); DIC Corporation's "N-690" (cresol novolac-type epoxy resin); DIC Corporation's "N-695" (cresol novolac-type epoxy resin); DIC Corporation's "HP-7200," "HP-7200HH," "HP-7200H," and "HP-7200L" (dicyclopentadiene-type epoxy resins); DIC Corporation's "EXA-7311" and "EXA "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000", "HP6000L" (naphthylene ether type epoxy resin); "EPPN-502H" (trisphenol type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolac type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", "NC3000FH", "NC3100" (biphenyl type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V", "ESN4 100V (naphthalene-type epoxy resin); Nippon Steel Chemical & Material Co., Ltd.'s "ESN485" (naphthol-type epoxy resin); Nippon Steel Chemical & Material Co., Ltd.'s "ESN375" (dihydroxynaphthalene-type epoxy resin); Mitsubishi Chemical Corporation's "YX4000H", "YX4000", "YX4000HK", and "YL7890" (bixylenol-type epoxy resin); Mitsubishi Chemical Corporation's "YL6121" (biphenyl-type epoxy resin); Mitsubishi Chemical Corporation's "YX8800" (anthracene-type epoxy resin); Mitsubishi Chemical Corporation's "YX7700" (phenol aralkyl type epoxy resin); "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals Co., Ltd.; "YL7760" and "YX7760" (bisphenol AF type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1010" (bisphenol A type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1031S" (tetraphenylethane type epoxy resin) manufactured by Mitsubishi Chemical Corporation; and "WHR991S" (phenolphthalimidine type epoxy resin) manufactured by Nippon Kayaku Co., Ltd. These may be used alone or in combination of two or more types.

When a liquid epoxy resin and a solid epoxy resin are used in combination as the epoxy resin, the mass ratio between them (liquid epoxy resin:solid epoxy resin) is preferably 20:1 to 1:20, more preferably 15:1 to 1:15, and particularly preferably 10:1 to 1:10.

The epoxy equivalent of the epoxy resin is preferably 50 g/eq. to 5,000 g/eq., more preferably 60 g/eq. to 3,000 g/eq., even more preferably 80 g/eq. to 2,000 g/eq., and particularly preferably 110 g/eq. to 1,000 g/eq. Epoxy equivalent represents the mass of resin per equivalent of epoxy groups. This epoxy equivalent can be measured in accordance with JIS K7236.

The weight-average molecular weight (Mw) of the epoxy resin is preferably 100 to 5,000, more preferably 250 to 3,000, and even more preferably 400 to 1,500. The weight-average molecular weight of the resin can be measured as a polystyrene-equivalent value using gel permeation chromatography (GPC).

The amount of epoxy resin in the curable resin composition is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to 100% by mass of non-volatile components in the curable resin composition; it is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less.

The amount of epoxy resin in the curable resin composition is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, based on 100% by mass of the resin components in the curable resin composition. Unless otherwise specified, the resin components of the curable resin composition refer to the non-volatile components of the curable resin composition, excluding the inorganic filler (B) described below.

Phenolic resins can be compounds containing one or more, preferably two or more, hydroxyl groups bonded to an aromatic ring, such as a benzene ring or a naphthalene ring, per molecule. When combined with an epoxy resin, phenolic resins react with the epoxy resin to cure the curable resin composition, and are therefore sometimes referred to as "phenolic curing agents." Phenolic resins with a novolac structure are preferred for obtaining cured products with excellent heat and water resistance. Furthermore, nitrogen-containing phenolic resins are preferred, and triazine skeleton-containing phenolic resins are more preferred for obtaining cured products with excellent adhesion to wiring. Of these, triazine skeleton-containing phenolic novolac resins are preferred for obtaining cured products with excellent heat resistance, water resistance, and adhesion. Specific examples of phenolic resins include "MEH-7700," "MEH-7810," and "MEH-7851" manufactured by Meiwa Kasei Co., Ltd.; "NHN," "CBN," and "GPH" manufactured by Nippon Kayaku Co., Ltd.; "SN-170," "SN-180," "SN-190," "SN-475," "SN-485," "SN-495," "SN-375," and "SN-395" manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "LA-7052," "LA-7054," "LA-3018," "LA-3018-50P," "LA-1356," "TD2090," and "TD-2090-60M" manufactured by DIC Corporation.

The amount of phenolic resin in the curable resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, relative to 100% by mass of non-volatile components in the curable resin composition; it is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

The amount of phenolic resin in the curable resin composition is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, relative to 100% by mass of the resin components in the curable resin composition; it is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

Active ester resins are generally compounds containing two or more highly reactive ester groups per molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds. Active ester resins are sometimes referred to as "active ester curing agents" because, when combined with epoxy resins, they react with the epoxy resin to cure the curable resin composition. Active ester resins are preferably those obtained by the condensation reaction of a carboxylic acid compound and/or a thiocarboxylic acid compound with a hydroxy compound and/or a thiol compound. From the perspective of obtaining a cured product with excellent heat resistance, activated ester resins obtained from a carboxylic acid compound and a hydroxy compound are preferred, and activated ester resins obtained from a carboxylic acid compound and a phenol compound and/or a naphthol compound are more preferred. Examples of carboxylic acid compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalene, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, and phenol novolak. Here, "dicyclopentadiene-type diphenol compounds" refer to diphenol compounds obtained by condensing one dicyclopentadiene molecule with two phenol molecules.

Specific examples of active ester resins include dicyclopentadiene-type active ester resins, naphthalene-type active ester resins containing a naphthalene structure, active ester resins containing an acetylated phenol novolac, and active ester resins containing a benzoylated phenol novolac. Among these, at least one selected from dicyclopentadiene-type active ester resins and naphthalene-type active ester resins is more preferred. As dicyclopentadiene-type active ester resins, active ester resins containing a dicyclopentadiene-type diphenol structure are preferred.

Commercially available activated ester resins include, for example, activated ester resins containing a dicyclopentadiene-type diphenol structure such as "EXB9451," "EXB9460," "EXB9460S," "EXB-8000L," "EXB-8000L-65M," "EXB-8000L-65TM," "HPC-8000L-65TM," "HPC-8000," "HPC-8000-65T," "HPC-8000H," and "HPC-8000H-65TM" (manufactured by DIC Corporation); activated ester resins containing a naphthalene structure such as "HP-B-8151-62T," "HP-C-8151-62T," "EXB-8100L-65T," and "EXB-8150-60T"; Examples include "EXB-8150-62T," "EXB-9416-70BK," "HPC-8150-60T," "HPC-8150-62T," and "EXB-8" (manufactured by DIC Corporation); a phosphorus-containing activated ester resin such as "EXB9401" (manufactured by DIC Corporation); an activated ester resin that is an acetylated product of phenol novolac such as "DC808" (manufactured by Mitsubishi Chemical Corporation); activated ester resins that are benzoylated products of phenol novolac such as "YLH1026," "YLH1030," and "YLH1048" (manufactured by Mitsubishi Chemical Corporation); and an activated ester resin containing a styryl group and a naphthalene structure such as "PC1300-02-65MA" (manufactured by Air Water Inc.).

The amount of active ester resin in the curable resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 3% by mass or more, relative to 100% by mass of non-volatile components in the curable resin composition; it is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

The amount of active ester resin in the curable resin composition is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, relative to 100% by mass of the resin components in the curable resin composition; it is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

Cyanate resins can be compounds that have one or more, preferably two or more, cyanate groups in one molecule. When combined with epoxy resins, cyanate resins react with the epoxy resin to cure the curable resin composition, and are therefore sometimes called "cyanate-based curing agents." Examples of cyanate resins include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate (oligo(3-methylene-1,5-phenylene cyanate)), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)ether; polyfunctional cyanate resins derived from phenol novolac and cresol novolac; and prepolymers in which these cyanate resins are partially converted to triazine. Specific examples of cyanate resins include Lonza Japan's "PT30" and "PT60" (both phenol novolac-type multifunctional cyanate resins), "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been triazinated to form a trimer).

Carbodiimide resins can be compounds having one or more, preferably two or more, carbodiimide structures in one molecule. When combined with an epoxy resin, carbodiimide resins react with the epoxy resin to cure the curable resin composition, and are therefore sometimes referred to as "carbodiimide-based curing agents." Specific examples of carbodiimide resins include aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexane-bis(methylene-t-butylcarbodiimide); aromatic biscarbodiimides such as phenylene-bis(xylylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, polycyclohexylenecarbodiimide, poly(methylenebiscyclohexylenecarbodiimide), and poly(isophoronecarbodiimide); and aromatic polycarbodiimides such as poly(phenylenecarbodiimide), poly(naphthalenecarbodiimide). Examples of polycarbodiimides include aromatic polycarbodiimides such as poly(methylenebis(methylphenylene)carbodiimide), poly(tolylenecarbodiimide), poly(methyldiisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(diethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide), poly(xylylenecarbodiimide), poly(tetramethylxylylenecarbodiimide), poly(methylenediphenylenecarbodiimide), and poly[methylenebis(methylphenylene)carbodiimide]. Commercially available carbodiimide resins include, for example, "Carbodilite V-02B," "Carbodilite V-03," "Carbodilite V-04K," "Carbodilite V-07," and "Carbodilite V-09" manufactured by Nisshinbo Chemical Inc.; and "Stavaxol P," "Stavaxol P400," and "Hykasil 510" manufactured by Rhein Chemie.

Acid anhydride resins can be compounds having one or more, preferably two or more, acid anhydride groups in one molecule. When combined with epoxy groups, acid anhydride resins can react with the epoxy resin to cure the curable resin composition, and are therefore sometimes referred to as "acid anhydride curing agents." Specific examples of acid anhydride resins include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenonetetracarboxylic dianhydride. Examples of suitable acid anhydrides include hydrates, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(anhydrotrimellitate), and polymeric acid anhydrides such as styrene-maleic acid resins in which styrene and maleic acid are copolymerized. Commercially available acid anhydride resins include, for example, "HNA-100," "MH-700," "MTA-15," "DDSA," and "OSA" manufactured by New Japan Chemical Co., Ltd.; "YH-306" and "YH-307" manufactured by Mitsubishi Chemical Corporation; "HN-2200" and "HN-5500" manufactured by Hitachi Chemical Co., Ltd.; and "EF-30," "EF-40," "EF-60," and "EF-80" manufactured by Clay Valley.

Amine resins can be compounds containing one or more, preferably two or more, amino groups in one molecule. When combined with epoxy groups, amine resins react with the epoxy resin to cure the curable resin composition, and are therefore sometimes referred to as "amine-based curing agents." Examples of amine resins include aliphatic amines, polyether amines, alicyclic amines, and aromatic amines, with aromatic amines being preferred. Primary or secondary amines are preferred as amine resins, with primary amines being more preferred. Specific examples of amine resins include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, and 2,2-bis(3-amino-4-hydroxyphenyl)propanol. Examples of suitable bis(4-aminophenoxy)biphenyl include bis(4-aminophenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, and bis(4-(3-aminophenoxy)phenyl)sulfone. Commercially available amine resins include, for example, "SEIKACURE-S" manufactured by Seika Corporation; "KAYABOND C-200S," "KAYABOND C-100," "KAYAHARD A-A," "KAYAHARD A-B," and "KAYAHARD A-S" manufactured by Nippon Kayaku Co., Ltd.; "EPICURE W" manufactured by Mitsubishi Chemical Corporation; and "DTDA" manufactured by Sumitomo Seika Chemicals Co., Ltd.

When combined with epoxy resins, benzoxazine resins react with the epoxy resin to cure the curable resin composition, and are therefore sometimes referred to as "benzoxazine-based curing agents." Specific examples of benzoxazine resins include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation; "HFB2006M" manufactured by Showa Highpolymer Co., Ltd.; and "P-d" and "F-a" manufactured by Shikoku Chemicals Corporation.

Thiol resins are sometimes called "thiol-based curing agents" because when combined with epoxy resins, they react with the epoxy resin to cure the curable resin composition. Examples of thiol resins include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate.

The active group equivalent of the curing agent is preferably 50 g/eq. to 3000 g/eq., more preferably 100 g/eq. to 1000 g/eq., even more preferably 100 g/eq. to 500 g/eq., and particularly preferably 100 g/eq. to 300 g/eq. The active group equivalent represents the mass of curing agent per equivalent of active group.

The weight average molecular weight (Mw) range of the curing agent may be the same as the weight average molecular weight range of the epoxy resin.

When the number of epoxy groups in the epoxy resin is taken as 1, the number of active groups in the curing agent is preferably 0.05 or more, more preferably 0.1 or more, even more preferably 0.2 or more, and preferably 5.0 or less, more preferably 4.0 or less, and particularly preferably 3.0 or less. The "number of epoxy groups in the epoxy resin" refers to the total value obtained by dividing the mass of the non-volatile components of the epoxy resin present in the curable resin composition by the epoxy equivalent. Furthermore, the "number of active groups in the curing agent" refers to the total value obtained by dividing the mass of the non-volatile components of the curing agent present in the curable resin composition by the active group equivalent.

The amount of curing agent in the curable resin composition is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, relative to 100% by mass of non-volatile components in the curable resin composition; it is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

The amount of curing agent in the curable resin composition is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, relative to 100% by mass of the resin components in the curable resin composition, and is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

The radical polymerizable resin may be a compound having an ethylenically unsaturated bond. Therefore, the radical polymerizable resin may have a radical polymerizable group containing an ethylenically unsaturated bond. Examples of radical polymerizable groups include unsaturated hydrocarbon groups such as vinyl, allyl, 3-cyclohexenyl, 3-cyclopentenyl, 2-vinylphenyl, 3-vinylphenyl, and 4-vinylphenyl; and α,β-unsaturated carbonyl groups such as acryloyl, methacryloyl, and maleimide (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl) groups. The number of radical polymerizable groups contained in one molecule of the radical polymerizable resin may be one, but preferably two or more. Examples of radical polymerizable resins include (meth)acrylic radical polymerizable resins, styrene radical polymerizable resins, allyl radical polymerizable resins, and maleimide radical polymerizable resins. The radical polymerizable resin may be used alone or in combination of two or more types.

The photocurable resin can be a resin that can be cured when exposed to light. Examples of photocurable resins include radical polymerizable resins. One type of photocurable resin may be used alone, or two or more types may be used in combination.

The amount of curable resin (A) in the curable resin composition is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to 100% by mass of non-volatile components in the curable resin composition; it is preferably 70% by mass or less, more preferably 60% by mass or less, and particularly preferably 50% by mass or less.

The amount of curable resin (A) in the curable resin composition is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, relative to 100% by mass of the resin components in the curable resin composition; it is preferably 97% by mass or less, more preferably 96% by mass or less, and particularly preferably 95% by mass or less.

-(B) Inorganic filler-
The curable resin composition may contain an inorganic filler (B) as an optional component. The inorganic filler (B) is usually contained in the curable resin composition in the form of particles.

(B) An inorganic compound is used as the inorganic filler material. Examples of (B) inorganic filler materials include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium titanate zirconate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica and alumina are preferred, with silica being particularly preferred. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Spherical silica is preferred. (B) The inorganic filler may be used alone or in combination of two or more types.

(B) Commercially available inorganic fillers include, for example, "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C," "YA050C," "YA050C-MJE," "YA010C," "SC2500SQ," "SO-C4," "SO-C2," and "SO-C1" manufactured by Admatechs Co., Ltd.; "UFP-30," "DAW-03," and "FB-105FD" manufactured by Denka Company, Limited; "Silfil NSS-3N," "Silfil NSS-4N," and "Silfil NSS-5N" manufactured by Tokuyama Corporation; "CellSpheres" and "MGH-005" manufactured by Taiheiyo Cement Corporation; and "Sfereek" and "BA-1" manufactured by JGC Catalysts and Chemicals Co., Ltd.

(B) The average particle size of the inorganic filler is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and preferably 10 μm or less, more preferably 7 μm or less, and even more preferably 5 μm or less. The average particle size of the inorganic filler can be measured using a laser diffraction/scattering method based on Mie scattering theory. Specifically, a volumetric particle size distribution of the inorganic filler is created using a laser diffraction/scattering particle size distribution analyzer, and the median diameter is used as the average particle size. A measurement sample can be prepared by weighing 100 mg of inorganic filler and 10 g of methyl ethyl ketone into a vial and ultrasonically dispersing the sample for 10 minutes. The volumetric particle size distribution of the inorganic filler is measured using a laser diffraction particle size distribution analyzer with blue and red light source wavelengths using a flow cell system, and the average particle size can be calculated as the median diameter from the obtained particle size distribution. An example of a laser diffraction particle size distribution measuring device is the LA-960 manufactured by Horiba, Ltd.

The specific surface area of (B) inorganic filler is preferably 1 m ² /g or more, more preferably 2 m ² /g or more, even more preferably 3 m ² /g or more, and preferably 60 m ² /g or less, more preferably 50 m ² /g or less, even more preferably 40 m ² /g or less. The specific surface area can be measured according to the BET method by adsorbing nitrogen gas onto the surface of a sample using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) and calculating the specific surface area using the BET multipoint method.

(B) From the viewpoint of improving moisture resistance and dispersibility, it is preferable that the inorganic filler be treated with a surface treatment agent. Examples of surface treatment agents include fluorine-containing silane coupling agents, aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, and titanate coupling agents. One type of surface treatment agent may be used alone, or two or more types may be used in any combination.

Commercially available surface treatment agents include, for example, Shin-Etsu Chemical Co., Ltd.'s "KBM403" (3-glycidoxypropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM803" (3-mercaptopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBE903" (3-aminopropyltriethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "SZ-31" (hexamethyldisilazane), Shin-Etsu Chemical Co., Ltd.'s "KBM103" (phenyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM-4803" (long-chain epoxy-type silane coupling agent), and Shin-Etsu Chemical Co., Ltd.'s "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane).

From the perspective of improving the dispersibility of (B) the inorganic filler, it is preferable that the degree of surface treatment with the surface treatment agent falls within a specific range. Specifically, 100% by mass of the inorganic filler is preferably surface-treated with 0.2% to 5% by mass of the surface treatment agent, more preferably with 0.2% to 3% by mass of the surface treatment agent, and even more preferably with 0.3% to 2% by mass of the surface treatment agent.

The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the amount of carbon per unit surface area of the inorganic filler is preferably 0.02 mg/ ^m2 or more, more preferably 0.1 mg/ ^m2 or more, and even more preferably 0.2 mg/m2 or ^more . On the other hand, from the viewpoint of suppressing an increase in the melt viscosity of the curable resin composition, the amount of carbon per unit surface area of the inorganic filler is preferably 1.0 mg/ ^m2 or less, more preferably 0.8 mg/ ^m2 or less, and even more preferably 0.5 mg/ ^m2 or less.

(B) The amount of carbon per unit surface area of the inorganic filler can be measured after the surface-treated inorganic filler is washed with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler that has been surface-treated with a surface treatment agent, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solids, the amount of carbon per unit surface area of the inorganic filler can be measured using a carbon analyzer. An example of a carbon analyzer that can be used is the "EMIA-320V" manufactured by Horiba, Ltd.

The amount of (B) inorganic filler in the curable resin composition is preferably 10% by mass or more, more preferably 30% by mass or more, and even more preferably 50% by mass or more, relative to 100% by mass of the non-volatile components of the curable resin composition; it is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less.

-(C) Curing accelerator-
The curable resin composition may contain, as an optional component, a curing accelerator (C). The curing accelerator (C) functions as a curing catalyst that accelerates the curing of the curable resin (A).

The (C) curing accelerator may be selected based on the type of (A) curable resin. For example, when the (A) curable resin contains an epoxy resin, examples of (C) curing accelerators that can accelerate the curing of the epoxy resin include phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, imidazole-based curing accelerators, metal-based curing accelerators, and amine-based curing accelerators. One type of (C) curing accelerator may be used alone, or two or more types may be used in combination.

Examples of phosphorus-based curing accelerators include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium)pyromellitate, tetrabutylphosphonium hydrogenhexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butyldimethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, and tetraphenyl Aromatic phosphonium salts such as phosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; aromatic phosphine-quinone addition products such as triphenylphosphine-p-benzoquinone addition products; tributylphosphine, tri- Aliphatic phosphines such as tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine; dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, Examples of aromatic phosphines include tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, and 2,2'-bis(diphenylphosphino)diphenyl ether.

Examples of urea-based curing accelerators include aliphatic dimethylureas such as 1,1-dimethylurea, 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, and 3-cyclooctyl-1,1-dimethylurea; 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, and 3-(3,4-dimethylphenyl)-1,1-dimethylurea. Examples of aromatic dimethylureas include toluene bis(dimethylurea), 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N',N'-dimethylurea), and N,N-(4-methyl-1,3-phenylene)bis(N',N'-dimethylurea) [toluene bisdimethylurea].

Examples of guanidine-based curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide.

Examples of imidazole curing accelerators include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2- Phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl -(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct imidazole compounds such as 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, and 2-phenylimidazoline, as well as adducts of imidazole compounds with epoxy resins. Commercially available imidazole curing accelerators include, for example, "1B2PZ," "2E4MZ," "2MZA-PW," "2MZ-OK," "2MA-OK," "2MA-OK-PW," "2PHZ," "2PHZ-PW," "Cl1Z," "Cl1Z-CN," "Cl1Z-CNS," and "C11Z-A" manufactured by Shikoku Chemicals Corporation; and "P200-H50" manufactured by Mitsubishi Chemical Corporation.

Metal-based curing accelerators include, for example, organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organocobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organocopper complexes such as copper(II) acetylacetonate, organozinc complexes such as zinc(II) acetylacetonate, organoiron complexes such as iron(III) acetylacetonate, organonickel complexes such as nickel(II) acetylacetonate, and organomanganese complexes such as manganese(II) acetylacetonate. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

Examples of amine-based curing accelerators include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene. Commercially available amine-based curing accelerators may also be used, such as "MY-25" manufactured by Ajinomoto Fine-Techno Co., Inc.

The amount of (C) curing accelerator in the curable resin composition is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.05% by mass or more, relative to 100% by mass of non-volatile components in the curable resin composition; it is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and particularly preferably 0.2% by mass or less.

The amount of curing accelerator (C) in the curable resin composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.10% by mass or more, relative to 100% by mass of the resin components in the curable resin composition; it is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, and even more preferably 0.5% by mass or less.

-(D) Polymer resin-
The curable resin composition may contain a polymer resin (D) as an optional component. Examples of the polymer resin (D) include phenoxy resins, polyimide resins, polyvinyl acetal resins, polyolefin resins, polybutadiene resins, polyamideimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, polyphenylene ether resins, polycarbonate resins, polyetheretherketone resins, and polyester resins. The polymer resin (D) may be used alone or in combination of two or more.

Examples of phenoxy resins include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, bisphenolacetophenone, novolac, biphenyl, fluorene, dicyclopentadiene, norbornene, naphthalene, anthracene, adamantane, terpene, and trimethylcyclohexane. The terminals of the phenoxy resins may be any functional group, such as a phenolic hydroxyl group or an epoxy group. Specific examples of phenoxy resins include "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (both phenoxy resins containing a bisphenol A skeleton); "YX8100" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol S skeleton); "YX6954" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol acetophenone skeleton); "FX280" and "FX293" manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "YL7500BH30," "YL7800BH40," "YX6954BH30," "YX7553," "YX7553BH30," "YL7769BH30," "YL6794," "YL7213," "YL7290," "YL7482," and "YL7891BH30" manufactured by Mitsubishi Chemical Corporation.

Specific examples of polyimide resins include "SLK-6100" manufactured by Shin-Etsu Chemical Co., Ltd., and "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd.

Examples of polyvinyl acetal resins include polyvinyl formal resins and polyvinyl butyral resins, with polyvinyl butyral resins being preferred. Specific examples of polyvinyl acetal resins include Denka Butyral 4000-2, Denka Butyral 5000-A, Denka Butyral 6000-C, and Denka Butyral 6000-EP manufactured by Denki Kagaku Kogyo Co., Ltd.; and S-LEC BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, and BM series manufactured by Sekisui Chemical Co., Ltd.

Examples of polyolefin resins include ethylene copolymer resins such as low-density polyethylene, very low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; and polyolefin polymers such as polypropylene and ethylene-propylene block copolymer.

Examples of polybutadiene resins include hydrogenated polybutadiene skeleton-containing resins, hydroxyl group-containing polybutadiene resins, phenolic hydroxyl group-containing polybutadiene resins, carboxyl group-containing polybutadiene resins, acid anhydride group-containing polybutadiene resins, epoxy group-containing polybutadiene resins, isocyanate group-containing polybutadiene resins, urethane group-containing polybutadiene resins, and polyphenylene ether-polybutadiene resins.

Specific examples of polyamide-imide resins include "Vylomax HR11NN" and "Vylomax HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of polyamide-imide resins also include modified polyamide-imides such as "KS9100" and "KS9300" (polysiloxane skeleton-containing polyamide-imides) manufactured by Hitachi Chemical Co., Ltd.

Specific examples of polyethersulfone resins include "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

Specific examples of polysulfone resins include polysulfones "P1700" and "P3500" manufactured by Solvay Advanced Polymers.

Specific examples of polyphenylene ether resins include "NORYL SA90" manufactured by SABIC. Specific examples of polyetherimide resins include "Ultem" manufactured by GE.

Examples of polycarbonate resins include hydroxyl group-containing carbonate resins, phenolic hydroxyl group-containing carbonate resins, carboxyl group-containing carbonate resins, acid anhydride group-containing carbonate resins, isocyanate group-containing carbonate resins, and urethane group-containing carbonate resins. Specific examples of polycarbonate resins include "FPC0220" manufactured by Mitsubishi Gas Chemical Company, Inc., "T6002" and "T6001" (polycarbonate diols) manufactured by Asahi Kasei Chemicals Corporation, and "C-1090," "C-2090," and "C-3090" (polycarbonate diols) manufactured by Kuraray Co., Ltd. Specific examples of polyether ether ketone resins include "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd.

Examples of polyester resins include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polytrimethylene terephthalate resin, polytrimethylene naphthalate resin, and polycyclohexane dimethyl terephthalate resin.

The (D) polymer resin typically has a large molecular weight. Specifically, the weight average molecular weight (Mw) of the (D) polymer resin is preferably greater than 5,000, more preferably 8,000 or more, even more preferably 10,000 or more, and even more preferably 20,000 or more; it is preferably 100,000 or less, more preferably 70,000 or less, even more preferably 60,000 or less, and even more preferably 50,000 or less.

The amount of (D) polymer resin in the curable resin composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more, relative to 100% by mass of non-volatile components in the curable resin composition; it is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.

The amount of (D) polymer resin in the curable resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, relative to 100% by mass of the resin components in the curable resin composition; it is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

-(E) Optional Additives-
The curable resin composition may further contain an optional additive (E) as an optional non-volatile component in combination with the above-described components (A) to (D). Examples of the optional additive (E) include organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium oxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentone and montmorillonite; antifoaming agents such as silicone-based antifoaming agents, acrylic-based antifoaming agents, fluorine-based antifoaming agents, and vinyl resin-based antifoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as urea silane; adhesion imparting agents such as triazole-based adhesion imparting agents, tetrazole-based adhesion imparting agents, and triazine-based adhesion imparting agents; and antioxidants such as hindered phenol-based antioxidants. Examples of the additives include: inhibitors; fluorescent brighteners such as stilbene derivatives; surfactants such as fluorine-based surfactants and silicone-based surfactants; flame retardants such as phosphorus-based flame retardants (e.g., phosphate ester compounds, phosphazene compounds, phosphinic acid compounds, and red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic flame retardants (e.g., antimony trioxide); dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic acid anhydride-based stabilizers; polymerization initiation aids such as tertiary amines; photosensitizers such as pyrarizones, anthracenes, coumarins, xanthones, and thioxanthones; and organic particles. (E) The optional additives may be used singly or in combination of two or more.

-(F) Solvent-
The curable resin composition may further contain a solvent (F) as an optional volatile component in addition to the non-volatile components (A) to (E) described above. An organic solvent is typically used as the solvent (F). Examples of the organic solvent include ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether-based solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, and anisole; alcohol-based solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, and methyl methoxypropionate. ether ester solvents such as methyl lactate, ethyl lactate, methyl 2-hydroxyisobutyrate, and the like; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, diethylene glycol monobutyl ether (butyl carbitol), and the like; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone, and the like; sulfoxide solvents such as dimethyl sulfoxide, and the like; nitrile solvents such as acetonitrile and propionitrile, and the like; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane, and the like; aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene, and the like. The (F) solvent may be used alone or in combination of two or more.

The amount of (F) solvent is not particularly limited, but when all components in the curable resin composition are taken as 100% by mass, it can be, for example, 60% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 15% by mass or less, 10% by mass or less, or even 0% by mass.

-Method for producing curable resin composition-
The curable resin composition can be produced, for example, by mixing components that can be included in the curable resin composition. The components may be mixed partially or entirely at the same time, or may be mixed sequentially. The temperature may be appropriately set during the process of mixing each component, and thus heating and/or cooling may be performed temporarily or throughout. Furthermore, stirring or shaking may be performed during the process of mixing each component.

-Characteristics of curable resin composition-
A cured product can be obtained by curing the curable resin composition. This cured product is preferably used to form an insulating layer of a circuit board. The insulating layer contains a cured product of the curable resin composition, and preferably contains only the cured product. Typically, volatile components such as (F) solvent contained in the curable resin composition can volatilize due to heat applied during curing, so the cured product can contain non-volatile components of the curable resin composition or reaction products thereof.

The cured product of the curable resin composition preferably has excellent dielectric properties. Specifically, the cured product of the curable resin composition preferably has a low dielectric constant. In one example, the dielectric constant of the cured product is preferably 5 or less, more preferably 4 or less, and particularly preferably 3 or less. There is no particular lower limit, and it can be, for example, 1.5 or more, 2.0 or more, etc.

It is also preferable that the cured product of the curable resin composition has a low dielectric dissipation factor. In one example, the dielectric dissipation factor of the cured product is preferably 0.05 or less, more preferably 0.04 or less, and particularly preferably 0.03 or less. There is no particular lower limit, and it can be, for example, 0.001 or more, 0.002 or more, etc.

The dielectric constant and dielectric loss tangent of the cured product of the curable resin composition can be measured by a cavity resonance perturbation method at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C. When the curable resin composition is thermosetting, the dielectric constant and dielectric loss tangent can be measured, for example, using a cured product obtained by thermally curing the curable resin composition at 180°C for 90 minutes. When the curable resin composition is photocurable, the dielectric constant and dielectric loss tangent can be measured using a cured product obtained by irradiating the curable resin composition with ultraviolet light at 1 J/ ^cm2 and then heating it at 180°C for 90 minutes.

<Description of a method for manufacturing a circuit board using a laminated resin sheet>
Hereinafter, a method for producing a circuit board will be described as an example of an application of the laminated resin sheet according to this embodiment. The circuit board typically includes an insulating layer obtained by curing a resin composition layer. This circuit board can be produced, for example, by a method including the following steps (i) to (iii):
(i) A step of peeling off the protective film from the laminated resin sheet to obtain a resin sheet.
(ii) A step of laminating a resin sheet on the inner layer substrate so that the resin composition layer and the inner layer substrate are bonded to each other.
(iii) A step of curing the resin composition layer to form an insulating layer.

The method for manufacturing a circuit board according to this example includes step (i) of peeling a protective film from a laminated resin sheet to obtain a resin sheet. Peeling off the protective film exposes the resin composition layer, which makes it possible to bond the resin composition layer to an inner layer substrate in step (ii).

Typically, the protective film is peeled off by pulling it relative to the resin sheet. For example, the resin sheet may be transported with the protective film fixed in place, and the protective film may be peeled off. Alternatively, the resin sheet may be transported with the protective film fixed in place, and the protective film may be peeled off. Furthermore, the resin sheet may be transported while the protective film is being pulled, and the protective film may be peeled off.

Typically, the protective film is pulled relatively in a peeling direction that forms a specific angle with respect to the surface of the resin composition layer, thereby achieving peeling of the protective film. There are no particular restrictions on the range of angles that the peeling direction forms with respect to the surface of the resin composition layer. The peeling direction may be, for example, parallel to the surface of the resin composition layer, perpendicular to the surface, or in any other direction. Furthermore, there are no particular restrictions on the temperature conditions under which peeling is performed. From the perspective of reducing the energy required to manufacture circuit boards, peeling of the protective film is typically performed at room temperature or a temperature close to room temperature.

The method for manufacturing a circuit board according to this example includes, after step (i), step (ii) of laminating a resin sheet on the inner layer substrate. This lamination is performed so that the resin composition layer and the inner layer substrate are bonded together.

The "inner layer substrate" used in step (ii) is a component that serves as the base material for the circuit board, and examples include glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. The substrate may also have a conductor layer on one or both sides, and this conductor layer may be patterned. Such a conductor layer can function as inner layer wiring. An inner layer substrate with a conductor layer (circuit) formed on one or both sides of the substrate is sometimes called an "inner layer circuit board." Furthermore, intermediate products on which insulating layers and/or conductor layers are to be formed during the manufacture of a circuit board are also included in the aforementioned "inner layer substrate." When the circuit board is a circuit board with built-in components, an inner layer substrate with built-in components may be used.

The inner layer substrate and resin sheet can be laminated, for example, by thermocompression bonding the resin sheet to the inner layer substrate from the support side. Examples of the member that thermocompresses the resin sheet to the inner layer substrate (hereinafter also referred to as the "thermocompression member") include a heated metal plate (such as a SUS panel) or a metal roll (SUS roll). It is preferable to press the thermocompression member not directly onto the resin sheet, but rather via an elastic material such as heat-resistant rubber, so that the resin sheet can adequately conform to the surface irregularities of the inner layer substrate.

The lamination of the inner layer substrate and the resin sheet may be carried out by vacuum lamination. In vacuum lamination, the thermocompression temperature is preferably in the range of 60°C to 160°C, more preferably 80°C to 140°C, the thermocompression pressure is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably 0.29 MPa to 1.47 MPa, and the thermocompression time is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. Lamination is preferably carried out under reduced pressure conditions of 26.7 hPa or less.

Lamination can be performed using a commercially available vacuum laminator. Examples of commercially available vacuum laminators include the vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., the vacuum applicator manufactured by Nikko Materials Co., Ltd., and the batch vacuum pressure laminator.

After lamination, the laminated resin sheets may be smoothed under normal pressure (atmospheric pressure), for example, by pressing a thermocompression member from the support side. The pressing conditions for the smoothing process may be the same as the thermocompression conditions for lamination described above. The smoothing process may be performed using a commercially available laminator. Note that lamination and smoothing may also be performed consecutively using the commercially available vacuum laminator described above.

The method for manufacturing a circuit board according to this example includes, after step (ii), step (iii) of curing the resin composition layer to form an insulating layer. The resin composition layer can be cured by a method suitable for the curable resin composition, such as thermal curing or photocuring. The specific curing conditions for the resin composition layer may be the same as those typically used when forming an insulating layer for a circuit board.

For example, when a thermosetting curable resin composition, such as a curable resin composition containing a thermosetting resin, is used, curing of the curable resin composition can proceed as thermal curing. Therefore, in this case, step (iii) can include thermally curing the resin composition layer. The thermal curing conditions for the resin composition layer can vary depending on the type of curable resin composition. For example, the curing temperature is preferably 120°C to 240°C, more preferably 150°C to 220°C, and even more preferably 170°C to 210°C. The curing time is preferably 5 to 120 minutes, more preferably 10 to 100 minutes, and even more preferably 15 to 100 minutes.

Furthermore, when the resin composition layer is thermally cured, the method for manufacturing a circuit board preferably includes preheating the resin composition layer at a temperature lower than the curing temperature before the thermal curing. For example, prior to thermally curing the resin composition layer, the resin composition layer may be preheated at a temperature typically between 50°C and 150°C, preferably between 60°C and 140°C, and more preferably between 70°C and 130°C for typically 5 minutes or more, preferably between 5 and 150 minutes, more preferably between 15 and 120 minutes, and even more preferably between 15 and 100 minutes.

On the other hand, when a photocurable curable resin composition, such as a curable resin composition containing a photocurable resin, is used, curing of the curable resin composition can proceed as photocuring. Therefore, in this case, step (iii) can include photocuring the resin composition layer. The photocuring conditions for the curable resin composition can vary depending on the type of curable resin composition. For example, the resin composition layer in the irradiated area can be photocured by an exposure treatment in which the resin composition layer is irradiated with actinic rays. Examples of actinic rays include ultraviolet rays, visible rays, electron beams, and X-rays, with ultraviolet rays being particularly preferred. The irradiation dose of ultraviolet rays is, for example, 10 mJ/cm ² to 1000 mJ/cm ^2. In this case, exposure may be performed through the support, or after peeling off the support.

In the exposure process, the resin composition layer may be irradiated with actinic rays through a mask on which a pattern has been formed. Exposure methods using a mask include contact exposure, in which exposure is performed by bringing the mask into contact with the workpiece, and non-contact exposure, in which exposure is performed using parallel light without contact; either method may be used.

Step (iii) may include a development process after the exposure process. The development process removes the non-photocured portions (unexposed portions) to form a pattern in the insulating layer. Development is typically performed by wet development. In wet development, a safe, stable, and easy-to-use developer is used, such as an alkaline aqueous solution, a water-based developer, or an organic solvent. Of these, a development process using an alkaline aqueous solution is preferred. Development methods that can be used include, for example, spraying, swinging immersion, brushing, and scraping.

Furthermore, when the resin composition layer is photocured, a post-baking treatment may be performed after photocuring and development, if necessary. Examples of post-baking treatments include ultraviolet irradiation treatment using a high-pressure mercury lamp and heat treatment using a clean oven. The ultraviolet irradiation treatment may be performed, for example, at an irradiation dose of approximately 0.05 J/cm ² to 10 J/cm ^2. The heat treatment may be performed, for example, at a temperature of preferably 150°C to 250°C for 20 minutes to 180 minutes, more preferably at a temperature of 160°C to 230°C for 30 minutes to 120 minutes.

The method for manufacturing a circuit board typically includes a step (iv) of removing the support. Removal of the support may be carried out before the resin composition layer is cured, but is preferably carried out after the resin composition layer is cured. If the resin composition layer is cured while covered with the support, adhesion of foreign matter to the surface of the resin composition layer during the curing step can be suppressed. Furthermore, if the support is removed after the resin composition layer is cured, removal of the support can be particularly easy.

When manufacturing a circuit board, the following steps may be further carried out: (v) drilling holes in the insulating layer; (vi) roughening the insulating layer; and (vii) forming a conductor layer as wiring. These steps (v) through (vii) may be carried out according to various methods known to those skilled in the art and used in manufacturing circuit boards. If the support is removed after step (iii), the support may be removed between steps (iii) and (v), between steps (v) and (vi), or between steps (vi) and (vii). Furthermore, if necessary, the formation of insulating layers and conductor layers in steps (i) through (vii) may be repeated to form a multilayer circuit board, such as a multilayer printed wiring board.

Step (v) is a step of drilling holes in the insulating layer, thereby forming holes such as via holes and through holes in the insulating layer. Step (v) may be performed using a processing method such as drilling, laser processing, or plasma processing, depending on the composition of the curable resin composition used to form the insulating layer. The dimensions and shape of the holes may be determined appropriately depending on the design of the circuit board.

Step (vi) is a step in which the insulating layer is roughened. Typically, step (vi) also involves removing smears (resin residue) that may be generated during hole formation. The roughening procedure and conditions are not particularly limited, and known procedures and conditions commonly used when forming insulating layers for circuit boards can be used. For example, the insulating layer can be roughened by performing a swelling treatment using a swelling liquid, a roughening treatment using an oxidizing agent, and a neutralization treatment using a neutralizing liquid, in that order.

Examples of swelling solutions used in the roughening treatment include alkaline solutions and surfactant solutions, with alkaline solutions being preferred. Sodium hydroxide solution and potassium hydroxide solution are more preferred as alkaline solutions. Commercially available swelling solutions include "Swelling Dip Securigans P" and "Swelling Dip Securigans SBU" manufactured by Atotech Japan. Swelling treatment using a swelling solution can be performed, for example, by immersing the insulating layer in a swelling solution at 30°C to 90°C for 1 to 20 minutes. To keep swelling of the resin in the insulating layer to an appropriate level, it is preferable to immerse the insulating layer in a swelling solution at 40°C to 80°C for 5 to 15 minutes.

The oxidizing agent used in the roughening treatment can be, for example, an alkaline permanganate solution prepared by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide. Roughening treatment using an oxidizing agent such as an alkaline permanganate solution is preferably carried out by immersing the insulating layer in an oxidizing agent solution heated to 60°C to 100°C for 10 to 30 minutes. The concentration of permanganate in the alkaline permanganate solution is preferably 5% to 10% by mass. Commercially available oxidizing agents include alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Securigance P" manufactured by Atotech Japan.

The neutralizing solution used for roughening treatment is preferably an acidic aqueous solution, and a commercially available product such as "Reduction Solution Securigant P" manufactured by Atotech Japan is one example. Treatment with a neutralizing solution can be carried out by immersing the surface that has been roughened with an oxidizing agent in a neutralizing solution at 30°C to 80°C for 5 to 30 minutes. From the standpoint of workability, etc., it is preferable to immerse the object that has been roughened with an oxidizing agent in a neutralizing solution at 40°C to 70°C for 5 to 20 minutes.

Step (vii) is a step of forming a conductor layer, and the conductor layer is formed on the insulating layer. The conductor material used for the conductor layer is not particularly limited. In a preferred embodiment, the conductor layer contains one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The conductor layer may be a single metal layer or an alloy layer. Examples of alloy layers include layers formed from alloys of two or more metals selected from the above group (e.g., nickel-chromium alloys, copper-nickel alloys, and copper-titanium alloys). Among these, from the standpoint of versatility in forming the conductor layer, cost, ease of patterning, etc., a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy, a copper-nickel alloy, or a copper-titanium alloy, is preferred, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy is more preferred, and a single metal layer of copper is even more preferred.

The conductor layer may have a single-layer structure, or a multi-layer structure consisting of two or more single-metal or alloy layers made of different types of metals or alloys. If the conductor layer has a multi-layer structure, the layer in contact with the insulating layer is preferably a single-metal layer of chromium, zinc, or titanium, or a nickel-chromium alloy layer.

Typically, the conductor layer is patterned so that it can function as wiring. In this case, it is preferable that the minimum line/space ratio of the conductor layer be small. The minimum line/space ratio of the conductor layer is preferably 100 μm/100 μm or less (i.e., a pitch of 200 μm or less), more preferably 80 μm/80 μm or less, even more preferably 50 μm/50 μm or less, and even more preferably 30 μm/30 μm or less. The lower limit may be, for example, 0.5 μm/0.5 μm or more. The pitch may be uniform or nonuniform throughout the conductor layer. The minimum pitch of the conductor layer may be, for example, 200 μm or less, 160 μm or less, 100 μm or less, or 60 μm or less. Here, "line" refers to the wiring width of the conductor layer, and "space" refers to the distance between the wiring lines.

The thickness of the conductor layer depends on the desired circuit board design, but is generally between 3 μm and 35 μm, preferably between 5 μm and 30 μm.

In one embodiment, the conductor layer may be formed by plating. For example, a conductor layer having a desired wiring pattern can be formed by plating the surface of the insulating layer using a conventional technique such as a semi-additive method or a full-additive method. From the perspective of ease of manufacturing, a semi-additive method is preferred. Below is an example of forming a conductor layer using a semi-additive method.

First, a plating seed layer is formed on the surface of the insulating layer by electroless plating. Next, a mask pattern is formed on the formed plating seed layer, exposing a portion of the plating seed layer corresponding to the desired wiring pattern. A metal layer is formed on the exposed plating seed layer by electrolytic plating, and the mask pattern is then removed. Unnecessary plating seed layer is then removed by etching or other methods, forming a conductor layer with the desired wiring pattern.

The method for manufacturing a circuit board may include any additional steps in addition to the steps described above. For example, the method for manufacturing a circuit board may include a step of providing a semiconductor chip so that it is bonded to the conductor layer. To give a specific example, when manufacturing a circuit board for a semiconductor chip package including a semiconductor chip, the method for manufacturing a circuit board may include a step of providing the semiconductor chip. The semiconductor chip may be bonded under appropriate conditions that allow for conductive connection between the terminal electrodes of the semiconductor chip and the conductor layer formed on the insulating layer. For example, conditions used in flip-chip mounting may be used. The semiconductor chip may also be bonded via an insulating adhesive or by reflow bonding. If necessary, the provided semiconductor chip may be filled with a mold underfill material.

The method for manufacturing a circuit board may also include, for example, a process for forming a sealing layer, a process for forming a solder resist layer, and a process for dicing the manufactured circuit board into individual pieces.

Examples of circuit boards manufactured include printed wiring boards and semiconductor chip packages. Examples of semiconductor chip packages include FC-CSP, MIS-BGA package, ETS-BGA package, fan-out type WLP (Wafer Level Package), fan-in type WLP, fan-out type PLP (Panel Level Package), and fan-in type PLP. In these semiconductor chip packages, it is preferable to form a rewiring formation layer using an insulating layer formed by curing the above-mentioned resin composition layer. However, circuit boards manufactured using the laminated resin sheet according to this embodiment are not limited to those exemplified here.

The circuit board can be used to manufacture semiconductor devices. The semiconductor layer comprises the circuit board described above. Examples of semiconductor devices include various semiconductor devices used in electrical appliances (e.g., computers, mobile phones, smartphones, tablet devices, wearable devices, digital cameras, medical equipment, televisions, etc.) and vehicles (e.g., motorcycles, automobiles, trains, ships, aircraft, etc.).

The present invention will be explained in more detail below with reference to examples. However, the present invention is not limited to the examples shown below. In the following explanation, "parts" and "%" representing amounts mean "parts by mass" and "% by mass", respectively, unless otherwise specified. Furthermore, unless otherwise specified, the temperature and pressure conditions were room temperature (25°C) and atmospheric pressure (1 atm).

<Method for measuring adhesive strength of dust removal roller>
The adhesive strength of the dust removal rollers used in the following Examples and Comparative Examples is as follows: Here, the adhesive strength of each dust removal roller refers to the adhesive strength of the adhesive tape forming the surface of the dust removal roller or the circumferential surface of the dust removal roller, and specifically refers to the adhesive strength measured by the following measurement method.
The adhesive tape was wound around a core so that the adhesive layer was on the outside of the roll to obtain a dust removal roller. An adhesive strength tester (Isshin Sangyo Co., Ltd., A3-10N) was placed perpendicular to the peripheral surface of the dust removal roller. The maximum load (N/100 ^mm2 ) when the measuring part was pressed against the adhesive layer and pulled back was measured. The measurement was performed three times, and the average of the three maximum load measurements was taken as the adhesive strength.
Adhesive tape 1: Nichiban "Karitome No. 207" (adhesive strength 2.3 N/100 mm ² )
Adhesive tape 2: Nichiban "Sealing Masking Tape No. 2563" (adhesive strength 2.7 N/100 mm ² )
Dust removal roller 3: Technoroll "Clean Dash E" (adhesive strength 3.0 N/100 mm ² )
Dust removal roller 4: Audio-Technica "HC-730" (adhesive strength 0.6 N/100 mm ² )

Example 1
(1. Production of a support having a release layer containing an acrylic resin)
(1-1. Production of acrylic resin (A))
Into a temperature-controllable reactor equipped with a stirrer, thermometer, and condenser, 500 parts by mass of toluene, 80 parts by mass of stearyl methacrylate (alkyl chain carbon number 18), 15 parts by mass of methacrylic acid, 5 parts by mass of 2-hydroxyethyl methacrylate, and 1 part of azobisisobutyronitrile were added dropwise using a dropper at a reaction temperature of 85°C over 4 hours to carry out a polymerization reaction. The mixture was then aged at the same temperature for 2 hours to complete the reaction, yielding acrylic resin (A). This acrylic resin (A) was dissolved in water containing 5% by mass of isopropyl alcohol and 5% by mass of n-butyl cellosolve to obtain a resin solution containing acrylic resin (A) as a mold-releasing component.

(1-2. Production of acrylic resin (B))
Methyl methacrylate (a), hydroxyethyl methacrylate (b), and an aromatic urethane acrylate oligomer (EBECRYL 220 manufactured by Daicel Allnex Corporation, having 6 acryloyl groups) (c) were charged into a stainless steel reaction vessel in a mass ratio of (a)/(b)/(c) = 94/1/5. Furthermore, 2 parts by mass of sodium dodecylbenzenesulfonate as an emulsifier per 100 parts by mass of the total of (a) + (b) + (c) were added to the reaction vessel and stirred to prepare a mixed solution (1).

Next, a reaction apparatus equipped with a stirrer, reflux condenser, thermometer, and dropping funnel was prepared. 60 parts by mass of the above mixed liquid (1), 200 parts by mass of isopropyl alcohol, and 5 parts by mass of potassium persulfate as a polymerization initiator were added to the reaction apparatus and heated to 60°C to prepare mixed liquid (2). Mixed liquid (2) was maintained at 60°C for 20 minutes.

Next, a mixed solution (3) consisting of 40 parts by mass of mixed solution (1), 50 parts by mass of isopropyl alcohol, and 5 parts by mass of potassium persulfate was prepared. Mixed solution (3) was added dropwise to mixed solution (2) over a period of 2 hours using a dropping funnel to prepare mixed solution (4).

Then, mixed liquid (4) was heated to 60°C and held for 2 hours. The resulting mixed liquid (4) was cooled to below 50°C and then transferred to a container equipped with a stirrer and pressure reduction equipment. 60 parts by mass of 25% aqueous ammonia and 900 parts by mass of pure water were added to this container, and the isopropyl alcohol and unreacted monomers were recovered under reduced pressure while heating to 60°C, yielding a composition containing acrylic resin (B) as an optional resin dispersed in pure water.

(1-3. Production of release agent)
An intermediate composition was obtained by mixing a resin solution containing acrylic resin (A) and a composition containing acrylic resin (B) such that the mass ratio (solid content mass ratio) of the acrylic resin (A) to the acrylic resin (B) was (A)/(B) = 20/80. Furthermore, a fluorine-based surfactant ("PLASCOAT (registered trademark) RY-2" manufactured by GOO Chemical Industry Co., Ltd.) was added to this intermediate composition in an amount of 0.1 part by mass per 100 parts by mass of the entire intermediate composition, thereby obtaining a release agent as a liquid acrylic resin composition.

(1-4. Production of Support)
A PET film ("T60" manufactured by Toray Industries, Inc., thickness 38 μm) was prepared as a substrate layer. A release agent was applied to one side of this substrate layer using a gravure coater and dried to form a release layer with a thickness of 0.1 μm. By the above operations, a long support comprising a substrate layer and a release layer containing an acrylic resin was obtained.

(2. Preparation of Resin Composition)
Tetramethylbisphenol type epoxy resin (Mitsubishi Chemical Corporation "YX4000H", epoxy equivalent 194 g/eq.) 8 parts, biphenylaralkyl type epoxy resin (Nippon Kayaku Co., Ltd. "NC3000L", epoxy equivalent approximately 271 g/eq.) 10 parts, naphthalene type epoxy resin (DIC Corporation "HP6000L", epoxy equivalent approximately 213 g/eq.) 2 parts, bifunctional epoxy resin (Nippon Steel Chemical Co., Ltd. "ZX1658GS", epoxy equivalent approximately 133 g/eq.) 2 parts, phenolic hardener having a triazine skeleton and a cresol novolac structure (DIC Corporation "LA-3018-50P", phenolic hydroxyl group equivalent approximately 151 g/eq., 2-methoxypropanol solution with a solid content of 50%) 4 parts, active ester A resin varnish was prepared as a liquid resin composition by mixing 6 parts of a phenol resin (DIC Corporation "HP-C-8151-62T", active ester group equivalent weight approximately 238 g/eq., toluene solution with a solid content of 62%), 5 parts of a phenoxy resin (Mitsubishi Chemical Corporation "YL7800BH40", MEK and cyclohexane solution with a solid content of 40%), 40 parts of an inorganic filler (average particle size 0.5 μm, surface treatment amount: 0.6% by mass of amino silane coupling agent relative to 100% by mass of inorganic filler) surface-treated with an amino silane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM573", N-phenyl-3-aminopropyltrimethoxysilane), and 1 part of an MEK solution with a solid content of 5% of a curing accelerator (4-dimethylaminopyridine).

(3. Production of laminated resin sheet)
The following operations were carried out while transporting the support and the protective film to produce a laminated resin sheet.

(3-1. Adhesion of copper powder as foreign matter to support body)
Copper powder of 100 μm mesh was intentionally attached to both sides of the support as foreign matter.

(3-2. Dust removal from support)
A roll laminator ("VA770" manufactured by Taisei Laminator Co., Ltd.) equipped with a pair of rotatably opposing nip rollers was prepared. Adhesive tape 1 ("Karitome No. 207" manufactured by Nichiban Co., Ltd., adhesive strength 2.3 N/100 mm ² ) was fixed to the pair of nip rollers with the adhesive facing outward, to prepare a pair of dust removal rollers. A support was fed into the roll laminator, and the support was passed between the pair of dust removal rollers, bringing the dust removal rollers into contact with both sides of the support to remove dust.

(3-3. Formation of Resin Composition Layer)
The resin varnish was uniformly applied onto the release layer of the support using a die coater so that the thickness of the resin composition layer obtained after drying would be 18 μm, and then dried in an oven to obtain a resin sheet. The resin sheet had a layer structure of a substrate layer/a release layer/a resin composition layer.

(3-4. Adhesion of copper powder as foreign matter to protective film)
A polypropylene film (Oji F-Tex Co., Ltd., biaxially oriented polypropylene film, product name "MA411," thickness 15 μm) having a roughened surface (arithmetic mean roughness 250 nm) and a smooth surface was prepared as a protective film. Copper powder with a 100 μm mesh was intentionally attached to both sides of this protective film as foreign matter.

(3-5. Dust removal from protective film)
A roll laminator ("VA770" manufactured by Taisei Laminator Co., Ltd.) equipped with a pair of rotatably opposing nip rollers was prepared. Adhesive tape 1 ("Karitome No. 207" manufactured by Nichiban Co., Ltd., adhesive strength 2.3 N/100 mm ² ) was fixed to the pair of nip rollers with the adhesive facing outward, to prepare a pair of dust removal rollers. A protective film was fed into the roll laminator, and the protective film was passed between the pair of dust removal rollers, bringing the dust removal rollers into contact with both sides of the protective film to remove dust.

(3-6. Lamination)
The resin sheet and the protective film were fed to a roll laminator ("VA770" manufactured by Taisei Laminator Co., Ltd.) and laminated by the roll laminator. The lamination was carried out by pressure bonding at a temperature of 70°C and a pressure of 0.3 MPa. A laminated resin sheet having a layer structure of a substrate layer/a release layer/a resin composition layer/a protective film was obtained by lamination.

(4. Manufacturing of Evaluation Circuit Board)
(4-1. Lamination of Resin Sheet and Inner Layer Substrate)
A copper-clad laminate (Panasonic Electric Works "R1515A", copper layer thickness 18 μm, substrate thickness 0.8 mm) was prepared as the inner layer substrate. After peeling the protective film from the laminated resin sheet to obtain a resin sheet having a layer structure of a base layer / release layer / resin composition layer, the resin sheet was laminated on both sides of the inner layer substrate using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd. two-stage build-up laminator "CVP700"). The lamination was performed by reducing the pressure for 30 seconds to 5 hPa or less, and then pressing at 100 ° C. and a pressure of 0.7 MPa for 30 seconds. Next, a heat press was performed at 100 ° C. and a pressure of 0.55 MPa for 60 seconds to perform a smoothing treatment.

(4-2. Curing of Resin Composition Layer)
The inner layer substrate laminated with the resin sheet was placed in an oven at 180° C. and heated for 30 minutes. The resin composition layer was thermally cured by heating, forming an insulating layer.

(4-3. Formation of wiring)
Next, wiring as a conductor layer was formed by a semi-additive process (SAP) utilizing the exposed surface profile of the insulating layer according to the following procedure.

(1) Removal of the support:
The support was peeled off to leave the insulating layer as the outermost layer.

(2) Electroless plating process:
The surface of the insulating layer exposed by peeling off the support was subjected to an electroless plating process (a copper plating process using a chemical solution manufactured by Atotech Japan) including the following steps 1 to 6, to form an electroless copper plating layer.

1. Alkaline cleaning (cleaning the surface of the insulating layer and adjusting the charge):
The surface of the insulating layer was cleaned using Cleaning Cleaner Securiganth 902 (trade name) at 60° C. for 5 minutes.

2. Soft etching (cleaning the surface of the insulating layer):
The surface of the insulating layer was treated with an aqueous solution of sodium peroxodisulfate acidified with sulfuric acid at 30° C. for 1 minute.

3. Pre-dip (adjusting the surface charge of the insulating layer for Pd deposition):
The surface of the insulating layer was treated with Pre. Dip Neogant B (trade name) at room temperature for 1 minute.

4. Adding an activator (adding Pd to the surface of the insulating layer):
The surface of the insulating layer was treated with Activator Neogant 834 (trade name) at 35° C. for 5 minutes.

5. Reduction (reducing Pd added to the insulating layer):
The surface of the insulating layer was treated with a mixed solution of Reducer Neogant WA (trade name) and Reducer Accelerator 810 mod. (trade name) at 30° C. for 5 minutes.

6. Electroless copper plating process (precipitating Cu on the surface of the insulating layer (Pd surface)):
The surface of the insulating layer was treated with a mixed solution of Basic Solution Printganth MSK-DK (trade name), Copper solution Printganth MSK (trade name), Stabilizer Printganth MSK-DK (trade name), and Reducer Cu (trade name) at 35°C for 20 minutes to form an electroless copper plating layer. The thickness of the formed electroless copper plating layer was 0.8 µm.

(3) Formation, exposure and development of plating resist:
After the electroless plating layer was formed, plating resist (a 15 μm thick dry film for pattern formation manufactured by Showa Denko K.K., "RY5115") was laminated on both sides of the electroless plating layer. Next, a 15 cm square glass mask (exposure mask) on which a wiring pattern (details will be described below) was formed was placed on the plating resist, and the resist was exposed (exposure dose: 210 mJ) using a stepper (a projection exposure system "UX-2240" manufactured by Ushio Inc.). After aging for 30 minutes at room temperature, the plating resist was developed (pattern formation) by spraying a 1 wt % aqueous solution of sodium carbonate at 30°C for 30 seconds using a spray-type developer.

Glass mask wiring pattern:
A glass mask having 25 comb-tooth patterns (wiring width 25 μm, spacing 25 μm, wiring length 10 mm, 16 lines) in which wiring from the anode and wiring from the cathode faced each other was used.

(4) Electroplating process:
Next, electrolytic copper plating was carried out using a chemical solution manufactured by Atotech Japan, Inc. to form an electrolytic copper-plated layer having a thickness of 8 μm to 10 μm. This electrolytic copper plating yielded a multilayer substrate comprising an electroless copper-plated layer and an electrolytic copper-plated layer on an insulating layer.

(5) Stripping of plating resist:
The resulting multilayer substrate was immersed in a resist stripper for printed circuit boards "R100S" manufactured by Mitsubishi Gas Chemical Company, Inc. at 50°C for 120 seconds while using ultrasonic waves, thereby removing the plating resist.

(6) Flash Etching:
Next, the multilayer substrate was immersed in a copper seed layer etching agent for semi-additive processes, "Melstrip SE-300," at 25°C to remove unnecessary portions of the electroless copper plating layer, thereby obtaining an evaluation circuit board having comb-tooth wiring. The comb-tooth wiring was formed by a conductor layer including an electroless copper plating layer and an electrolytic copper plating layer, and had the same pattern shape as the comb-tooth pattern of the glass mask when viewed in the thickness direction.

Example 2
A laminated resin sheet and an evaluation circuit board were manufactured in the same manner as in Example 1, except that adhesive tape 2 (Nichiban Co., Ltd.'s "Sealing Masking Tape No. 2563", adhesive strength 2.7 N/100 mm ² ) was used instead of adhesive tape 1 when removing dust from the protective film in step (3-5).

Example 3
A laminated resin sheet and an evaluation circuit board were manufactured in the same manner as in Example 1, except that adhesive tape 2 (Nichiban Co., Ltd.'s "Sealing Masking Tape No. 2563", adhesive strength 2.7 N/100 mm ² ) was used instead of adhesive tape 1 when removing dust from the support in step (3-2).

Example 4
A laminated resin sheet and an evaluation circuit board were manufactured in the same manner as in Example 1, except that adhesive tape 2 (Nichiban Co., Ltd.'s "Sealing Masking Tape No. 2563", adhesive strength 2.7 N/100 mm ² ) was used instead of adhesive tape 1 when removing dust from the support in step (3-2) and when removing dust from the protective film in step (3-5).

Example 5
A laminated resin sheet and an evaluation circuit board were produced in the same manner as in Example 1, except that when removing dust from the support in step (3-2) and the protective film in step (3-5), a dust removal roller 4 ("HC-730" manufactured by Audio-Technica Corporation, adhesive strength 0.6 N/100 mm ² ) was used instead of the dust removal roller obtained by fixing the adhesive tape 1 to a nip roller.

Example 6
A laminated resin sheet and an evaluation circuit board were manufactured in the same manner as in Example 1, except that in the step (3-2) of removing dust from the support, a dust removal roller 4 ("HC-730" manufactured by Audio-Technica Corporation, adhesive strength 0.6 N/100 mm ² ) was used instead of the dust removal roller obtained by fixing adhesive tape 1 to a nip roller, and in the step (3-5) of removing dust from the protective film, adhesive tape 2 ("Sealing Masking Tape No. 2563" manufactured by Nichiban Co., Ltd., adhesive strength 2.7 N/100 mm ² ) was used instead of adhesive tape 1.

<Comparative Example 1>
A laminated resin sheet and an evaluation circuit board were produced in the same manner as in Example 1, except that when removing dust from the support in step (3-2), a dust removal roller 3 ("Clean Dash E" manufactured by Technoroll Co., Ltd., adhesive strength 3.0 N/100 mm ² ) was used instead of the dust removal roller obtained by fixing adhesive tape 1 to a nip roller.

<Comparative Example 2>
A laminated resin sheet and an evaluation circuit board were manufactured in the same manner as in Example 1, except that when removing dust from the protective film in step (3-5), a dust removal roller 3 ("Clean Dash E" manufactured by Technoroll Co., Ltd., adhesive strength 3.0 N/100 mm ² ) was used instead of the dust removal roller obtained by fixing adhesive tape 1 to a nip roller.

<Comparative Example 3>
A laminated resin sheet and an evaluation circuit board were produced in the same manner as in Example 1, except that dust removal from the support in step (3-2) and dust removal from the protective film in step (3-5) were carried out by treatment for 10 seconds using an air-blowing type static eliminator ("BF-6MB" manufactured by Shishido Electrostatic Corporation). The treatment using the air-blowing type static eliminator is a non-contact static elimination treatment in which static elimination is performed using an ionizer while foreign matter is removed by wind force.

<Comparative Example 4>
A laminated resin sheet and an evaluation circuit board were produced in the same manner as in Example 1, except that dust removal from the support in step (3-2) and dust removal from the protective film in step (3-5) were carried out by treating for 10 seconds using a non-contact ultrasonic cleaner ("USW-102" manufactured by Hugle). The treatment using the non-contact ultrasonic cleaner is a non-contact static elimination treatment that removes foreign matter using ultrasonic waves.

Comparative Example 5
A laminated resin sheet and an evaluation circuit board were produced in the same manner as in Example 1, except that dust removal from the support in step (3-2) and dust removal from the protective film in step (3-5) were carried out by treatment using an air gun. The treatment using an air gun is a non-contact static elimination treatment that removes foreign matter by air sprayed from an air gun.

<Test 1. Evaluation of releasability of support>
In the step (4-3) of peeling the support, the case where the support could be peeled off smoothly from the insulating layer was evaluated as "Good", and the case where a part or all of the support was stuck to the insulating layer and the support could not be peeled off smoothly was evaluated as "Poor". The fact that the support could not be peeled off smoothly indicates that a part or all of the release layer was lost due to adhesion to the dust removal roller during the dust removal step of the support, resulting in a decrease in the releasability of the support.

<Test 2. Evaluation of transportability during dust removal from support and protective film>
In step (3-2), when the support was transported while being in contact with the dust removal roller, it was observed whether wrinkles occurred on the support. Also, in step (3-5), when the protective film was transported while being in contact with the dust removal roller, it was observed whether wrinkles occurred on the protective film. When no wrinkles occurred, it was evaluated as "Good", and when wrinkles occurred, it was evaluated as "Poor".

<Test 3. Evaluation of wiring formation yield>
The insulation resistance value of the comb-tooth wiring of the evaluation circuit board was measured using a resistance meter ("ECM-100" manufactured by J-RAS Co., Ltd.) When the proportion of comb-tooth wirings having an insulation resistance value of 1 × ¹⁰ Ω or more was 60% or more (i.e., the number of comb-tooth wirings having an insulation resistance value of 1 × ¹⁰ Ω or more was 15 or more), it was evaluated as "Good", and when it was less than 60%, it was evaluated as "Poor".

<Results>
The results of the above-mentioned Examples and Comparative Examples are shown in the table below.

<Consideration>
From the examples and comparative examples, it was confirmed that the manufacturing method of the present invention was able to produce a laminated resin sheet (a resin sheet with a protective film) that can eliminate foreign matter and improve the yield of wiring formation.

The above examples and comparative examples show results using acrylic release agents, but the inventors have confirmed that even when non-acrylic release agents are used, it is possible to produce laminated resin sheets that can eliminate foreign matter and improve wiring formation yields, although to different degrees.

1 Manufacturing apparatus 2 Manufacturing apparatus 10 Support 10U Release surface (surface on the release layer side)
10D Back side (side opposite to the release layer)
REFERENCE SIGNS LIST 11 Base material layer 12 Release layer 20 Resin composition layer 21 Curable resin composition 30 Resin sheet 40 Protective film 40D First surface 40U Second surface 50 Laminated resin sheet (resin sheet with protective film)
REFERENCE SIGNS LIST 100 Support body dust removal section 110 First dust removal roller 110S Peripheral surface 120 Third dust removal roller 120S Peripheral surface 200 Layer forming section 210 Coating device 220 Drying device 300 Protective film dust removal section 310 Second dust removal roller 310S Peripheral surface 320 Fourth dust removal roller 320S Peripheral surface 400 Laminating section 410 Pressing roller 420 Pressing roller 430 Chamber 500 Support body dust removal section 510 First dust removal roller 510S Peripheral surface 520 Third dust removal roller 520S Peripheral surface 600 Protective film dust removal section 610 Second dust removal roller 610S Peripheral surface 620 Fourth dust removal roller 620S Peripheral surface

Claims (7)

A method for producing a resin sheet with a protective film, comprising a support , a resin composition layer containing a curable resin composition, and a protective film in this order;
The support includes a base layer and a release layer formed on the base layer;
The manufacturing method comprises:
a step (I) of contacting a first dust removal roller with the release layer side of the support;
Step (II) of forming a resin composition layer on the release layer side of the support;
(III) contacting a second dust removal roller with the first surface of the protective film;
and step (IV) of bonding the resin composition layer to the first surface of the protective film;
The first dust removal roller has an adhesive strength of less than 2.9 N/100 ^mm2 ;
A method for producing a resin sheet with a protective film, wherein the second dust removal roller has an adhesive strength of less than 2.9 N/100 ^mm2 . The method for producing a resin sheet with a protective film according to claim 1, wherein step (II) of forming a resin composition layer on the release layer side of the support comprises applying a liquid curable resin composition. The method for producing a resin sheet with a protective film according to claim 1 , further comprising the step (V) of bringing a third dust removal roller into contact with the surface of the support opposite to the release layer. The method for producing a resin sheet with a protective film according to claim 1, further comprising a step (VI) of contacting a second surface of the protective film opposite the first surface with a fourth dust removal roller. The method for producing a resin sheet with a protective film according to claim 1, wherein the curable resin composition contains a curable resin and an inorganic filler. The method for producing a resin sheet with a protective film according to claim 1 , wherein the base material layer and the protective film are thermoplastic resin films. step (I) includes removing foreign matter adhering to the first dust removal roller;
The method for producing a resin sheet with a protective film according to claim 1 , wherein step (III) comprises removing foreign matter adhering to the second dust removal roller.