Method for producing multilayer body

Abstract

Provided is a method for producing a multilayer body (300) that sequentially comprises a substrate (110), a first cladding layer (20) of an optical waveguide (100), and a core layer (30) of the optical waveguide (100) in this order. This method for producing a multilayer body (300) comprises: a step (A) in which a substrate (110) and a film that is provided with a resin layer (a) (21), which is composed of a resin composition for forming the first cladding layer (20), are superposed upon each other; a step (B) in which the resin layer (a) (21) is photocured after the step (A); and a step (C) in which a film that is provided with a resin layer (b) (31), which is composed of a resin composition for forming the core layer (30), is superposed on a surface on the reverse side of a resin layer (a) (22) from the substrate (110) after the step (B). With respect to this method for producing a multilayer body (300), the resin composition for forming the first cladding layer (20) contains a photopolymerization initiator.

Description

Manufacturing method of laminate

[0001] The present invention relates to a method for producing a laminate.

[0002] BACKGROUND ART In recent years, there has been a demand for components in information and communication devices that can realize more advanced information communication, such as larger information capacity and faster information communication speed, and an optoelectronic composite substrate has been considered as one such component.

[0003] The optical / electrical composite substrate may be, for example, a substrate on which an optical waveguide is provided. Techniques relating to the manufacturing method of an optical waveguide include those described in Patent Documents 1 to 3, for example.

[0004] Patent Document 1 describes a method for continuously manufacturing an optical waveguide having an embedded structure in which a core layer is surrounded by a lower clad and an upper clad, the method comprising the following steps A, B, C, D, and E, and characterized in that steps A, B, C, D, and E are continuously performed. Step A: a step of bonding a core layer-containing stamper film, which has grooves on at least one surface thereof corresponding to the pattern of the core layer in an optical waveguide and has core layers in the grooves, to a laminate having a lower clad photocurable composition layer on one surface of a substrate film, and bringing the core layer into contact with the lower clad photocurable composition layer; Step B: a step of curing the lower clad photocurable composition layer by light irradiation in parallel with or after Step A; Step C: a step of peeling the stamper film from the laminated structure of the core layer-containing stamper film and the laminate after Step B; Step D: a step of covering the core layer with an upper clad photocurable composition after Step C; and Step E: a step of curing the upper clad photocurable composition by light irradiation after Step D.

[0005] The method for manufacturing an optical waveguide described in Patent Document 1 is described as being easily adaptable to the manufacture of various types of optical waveguides, and as being capable of manufacturing optical waveguides with high shape accuracy at low cost through a simpler process.

[0006] Patent Document 2 describes an opto-electrical hybrid board including a flexible circuit board having electrical wiring with mounting pads formed on the surface of an insulating layer, a device mounted on the mounting pads, and an optical waveguide laminated on the back surface of the insulating layer, wherein the flexible circuit board is a flexible double-sided circuit board having electrical wiring also formed on the back surface of the insulating layer, and a metal reinforcing layer is plated on at least a portion of the electrical wiring on the back surface corresponding to the mounting pads, and the optical waveguide is in contact with the metal reinforcing layer. Patent Document 2 describes an opto-electrical hybrid board in which the metal reinforcing layer is adhered to the insulating layer of the flexible circuit board without an adhesive layer, and the metal reinforcing layer prevents deformation due to a pressure load during device mounting, thereby providing an opto-electrical hybrid board in which the device is properly mounted.

[0007] Patent Document 2 describes preparing a substrate having copper foil 21 formed on both sides of an insulating layer 1 made of a resin such as polyimide, and forming through holes 1a and via holes 1b for optical paths in the substrate (see paragraph 0023 of Patent Document 2). Patent Document 2 also describes a flexible double-sided circuit board E having a metal reinforcing layer M formed thereon (see paragraph 0028 of Patent Document 2). The flexible double-sided circuit board E includes the substrate. Patent Document 2 also describes forming an undercladding layer 6 on the back side of the flexible double-sided circuit board E in contact with the metal reinforcing layer M covering the electrical wiring 2B on the back side. Examples of molding materials for the undercladding layer 6 include photosensitive resins and thermosetting resins (see paragraph 0029 of Patent Document 2). Figures 4 to 6 of Patent Document 2 show that the molding material for the undercladding layer 6 is filled into recesses formed in the flexible double-sided circuit board E having the metal reinforcing layer M formed thereon.

[0008] Patent Document 3 describes an optoelectronic wiring board that is formed by integrating a rigid section in which conductor circuits and insulating layers are laminated on both sides of a substrate with one or more bendable flex sections, wherein the rigid section has external connection terminals formed therein for mounting optical elements and / or package substrates on which optical elements are mounted, and at least one of the flex sections has optical wiring formed therein. It is described that the optoelectronic wiring board in Patent Document 3 can suitably process large amounts of information and high-speed information processing without increasing the size of the wiring board.

[0009] Patent Document 3 describes that the rigid section has an optical signal transmitting region formed therein, and that the optical signal transmitting region is filled with a resin composition (see claims 4 and 5 of Patent Document 3). Patent Document 3 also describes that the optical signal transmitting region is formed so as to penetrate all of the substrates and insulating layers that make up the rigid section (see claim 6 of Patent Document 3).

[0010] Furthermore, Patent Document 3 describes a substrate 221 consisting of an optical waveguide film 250 and a surrounding resin layer (insulating layer) 221a, and describes that the resin layer 221a constitutes part of the optical signal transmitting regions 242a, 242b (see paragraph 0033 of Patent Document 3).

[0011] JP 2014-26152 A JP 2014-238455 A JP 2006-140233 A

[0012] One of the properties required for an optoelectronic composite substrate is the suppression of propagation loss.

[0013] The present invention provides a method for producing a laminate that can suppress propagation loss in an optoelectronic composite substrate.

[0014] According to the present invention, there is provided the following method for producing a laminate.

[0015] [1] A method for producing a laminate comprising, in this order, a substrate, a first clad layer of an optical waveguide, and a core layer of the optical waveguide, comprising: step (A) of laminating the substrate and a film comprising a resin layer (a) made of a resin composition for forming the first clad layer, step (B) of photo-curing the resin layer (a) after step (A), and step (C) of laminating, after step (B), a film comprising a resin layer (b) made of a resin composition for forming the core layer, on a surface of the resin layer (a) opposite to the substrate side, wherein the resin composition for forming the first clad layer contains a photopolymerization initiator. [2] A method for producing a laminate according to item [1] above, further comprising step (D) of heating the resin layer (a) between steps (A) and (B). [3] The method for producing a laminate according to [2], wherein in the step (D), the resin layer (a) is heated under conditions of 120° C. or higher and 160° C. or lower. [4] In the step (B), an integrated light amount is 10 mJ / cm 2 ２ More than 1500mJ / cm ２The method for producing a laminate according to any one of [1] to [3], wherein the resin layer (a) is photocured under the following conditions: [5] The method for producing a laminate according to any one of [1] to [4], wherein in step (C), the resin layer (b) is in an uncured state or a semi-cured state. [6] The method for producing a laminate according to any one of [1] to [5], further comprising, after step (C), the steps of: irradiating a part of the resin layer (b) with light to form a core layer including a first core portion consisting of an exposed portion of the resin layer (b) and a second core portion consisting of an unexposed portion of the resin layer (b); and forming a second clad layer on the core layer including the first core portion and the second core portion. [7] The method for producing a laminate according to any one of [1] to [6], wherein the content of the photopolymerization initiator contained in the resin composition for forming the first cladding layer is 0.01 parts by mass or more and 5.00 parts by mass or less, relative to 100 parts by mass of the total content of resin components in the resin composition for forming the first cladding layer. [8] The method for producing a laminate according to any one of [1] to [7], wherein the photopolymerization initiator contained in the resin composition for forming the first cladding layer comprises a cationic photopolymerization initiator. [9] The method for producing a laminate according to [8], wherein the cationic photopolymerization initiator comprises a sulfonium salt-type polymerization initiator.

[10] The method for producing a laminate according to any one of [1] to [9], wherein the resin composition for forming the first cladding layer comprises one or more compounds selected from the group consisting of polyimide resins and compounds having a cyclic ether structure.

[11] The method for producing a laminate according to any one of [1] to

[10] , wherein in step (C), the resin layer (b) contains a photopolymerization initiator, and the photopolymerization initiator contained in the resin layer (b) has the same chemical structure as a photopolymerization initiator contained in the resin composition for forming the first clad layer.

[12] The method for producing a laminate according to any one of [1] to

[11] , wherein the laminate is an optoelectronic composite substrate further comprising a second clad layer on a core layer.

[0016] According to the present invention, a method for producing a laminate capable of suppressing propagation loss in an optoelectronic composite substrate can be provided.

[0017] It is a cross-sectional view showing an example of the structure of the optical and electrical composite substrate of this embodiment. It is a cross-sectional view showing an example of the manufacturing method of the laminate of this embodiment. It is a cross-sectional view showing an example of the manufacturing method of the laminate of this embodiment.

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Numerical ranges "A to B" represent A or more and B or less unless otherwise specified.

[0019] FIG. 1 is a cross-sectional view schematically illustrating an example of the structure of an optoelectronic composite substrate according to this embodiment. Note that the drawing is a simplified diagram and does not correspond to the actual dimensional ratio. As shown in FIG. 1 , an optoelectronic composite substrate 200 includes an optical waveguide 100 provided on a substrate 110. The optical waveguide 100 includes a first cladding layer 20, a core layer 30, and a second cladding layer 40 laminated in this order. The core layer 30 is patterned, and includes a first core portion 35 and a second core portion 36. Here, the first core portion 35 is a core layer that is a light propagation path, and the second core portion 36 is a core layer that is not a light propagation path.

[0020] The inventors have found through their studies that conventional methods for manufacturing an optical / electrical composite substrate may result in an imperfectly formed core layer pattern. Specifically, imperfectly formed core layer pattern refers to, for example, blurring of the interface between the first core portion 35 and the second core portion 36. The inventors have found through their studies that imperfectly formed core layer pattern may result in propagation loss in the optical / electrical composite substrate. The present invention has been made in view of the above circumstances, and provides a method for manufacturing a laminate that can suppress propagation loss in an optical / electrical composite substrate.

[0021] The method for manufacturing a laminate of this embodiment is a method for manufacturing a laminate comprising, in this order, a substrate, a first clad layer of an optical waveguide, and a core layer of the optical waveguide, and comprises: step (A) of laminating the substrate and a film comprising a resin layer (a) made of a resin composition for forming the first clad layer; step (B) of photo-curing the resin layer (a) after step (A); and step (C) of laminating, after step (B), a film comprising a resin layer (b) made of a resin composition for forming the core layer, on the surface of the resin layer (a) opposite the substrate side, wherein the resin composition for forming the first clad layer contains a photopolymerization initiator.

[0022] As described above, in conventional methods for manufacturing an optoelectronic composite substrate, the core layer pattern is not formed neatly, and propagation loss in the optoelectronic composite substrate may occur. The present inventors believe that, in conventional methods for manufacturing an optoelectronic composite substrate, acid derived from the monomer and / or acid generator contained in the first clad layer and / or core layer migrates between the first clad layer and the core layer, resulting in the core layer pattern not being formed neatly.

[0023] As a result of extensive research, the present inventors have found that a laminate manufacturing method that includes a step (B) of photocuring a resin layer (a) made of a resin composition for forming a first clad layer before a step (C) of laminating a film including a resin layer (b) made of a resin composition for forming a core layer can produce a laminate that can reduce propagation loss in an optoelectronic composite substrate. The present inventors believe that including the above steps can prevent acid derived from the monomer and / or acid generator from migrating between the first clad layer and the core layer, thereby forming a clean pattern in the core layer and reducing propagation loss in the optoelectronic composite substrate. That is, the laminate manufacturing method of this embodiment can produce a laminate that can reduce propagation loss in an optoelectronic composite substrate.

[0024] 2 and 3 are cross-sectional views schematically illustrating an example of a method for manufacturing a laminate according to this embodiment. Each step of the method for manufacturing a laminate according to this embodiment will now be described in detail.

[0025] [Step (A) of laminating a substrate and a film having a resin layer (a)] The method for manufacturing a laminate of this embodiment includes step (A) of laminating a substrate 110 and a film having a resin layer (a) 21 made of a resin composition for forming a first clad layer.

[0026] In step (A), the method for laminating the substrate 110 and the film having the resin layer (a) 21 is not particularly limited, but a preferred method is to heat and press a workpiece in which the substrate 110 and the film having the resin layer (a) 21 are superimposed.

[0027] In step (A), the degree of vacuum when the workpiece is heated and pressed is not particularly limited, and the workpiece may be heated and pressed at normal pressure or under reduced pressure, but the workpiece is preferably heated and pressed under reduced pressure. The degree of vacuum when the workpiece is heated and pressed under reduced pressure is not particularly limited, but is, for example, 500 Pa or less.

[0028] In step (A), the pressure when heating and pressing the workpiece is preferably 0.1 MPa or more, more preferably 0.3 MPa or more, and even more preferably 0.4 MPa or more, from the viewpoint of further improving the adhesion between the substrate 110 and the film having the resin layer (a) 21, and is preferably 10.0 MPa or less, more preferably 8.0 MPa or less, even more preferably 6.0 MPa or less, even more preferably 5.0 MPa or less, even more preferably 3.0 MPa or less, and even more preferably 1.0 MPa or less, from the viewpoint of preventing damage to the substrate.

[0029] In step (A), the temperature at which the substrate 110 and the film having the resin layer (a) 21 are laminated is preferably 80°C or higher, more preferably 100°C or higher, even more preferably 120°C or higher, even more preferably 130°C or higher, from the viewpoint of further improving the adhesion between the substrate 110 and the film having the resin layer (a) 21, and is preferably 180°C or lower, more preferably 160°C or lower, even more preferably 150°C or lower.

[0030] In step (A), the time for laminating the substrate 110 and the film having the resin layer (a) 21 is preferably 10 seconds or more, more preferably 30 seconds or more, even more preferably 60 seconds or more, and even more preferably 100 seconds or more, from the viewpoint of further improving the adhesion between the substrate 110 and the film having the resin layer (a) 21, and is preferably 250 seconds or less, more preferably 200 seconds or less, even more preferably 180 seconds or less, and even more preferably 150 seconds or less, from the viewpoint of further improving productivity.

[0031] In the step (A), when the workpiece is heated and pressed, the pressing method is not particularly limited, and may be a flat press or a roll press.

[0032] In the step (A), the device for laminating the substrate 110 and the film comprising the resin layer (a) 21 is not particularly limited, but is preferably a vacuum laminating device.

[0033] The substrate 110 is not particularly limited and may be, for example, a printed circuit board or a flexible substrate, preferably a flexible substrate, more preferably a flexible double-sided copper-clad laminate. The substrate 110 may have through holes.

[0034] The film including the resin layer (a) will be described in detail later. The film including the resin layer (a) may be a film including a layer other than the resin layer (a) 21. That is, the laminate obtained in the step (A) may include a layer other than the substrate 110 and the resin layer (a) 21.

[0035] [Step (B) of Photocuring Resin Layer (a)] The method for producing a laminate according to the present embodiment includes, after step (A), step (B) of photocuring the resin layer (a) 21. That is, step (B) is a step of irradiating the resin layer (a) 21 with light to obtain a cured resin layer (a) 22.

[0036] In the step (B), the integrated light amount when irradiating with light is preferably 10 mJ / cm from the viewpoint of further promoting the curing of the resin layer (a). ２ More preferably, 30 mJ / cm ２More preferably, 50 mJ / cm ２ More preferably, 80 mJ / cm ２ or more, and preferably 1500 mJ / cm ２ or less, more preferably 1400 mJ / cm ２ More preferably, 1300 mJ / cm or less ２ More preferably, 1200 mJ / cm or less ２ More preferably, 1100 mJ / cm or less ２ The following is the result.

[0037] In step (B), the light irradiation time is preferably 5 seconds or more, more preferably 10 seconds or more, and even more preferably 15 seconds or more, from the viewpoint of further promoting the curing of the resin layer (a), and is preferably 300 seconds or less, more preferably 250 seconds or less, and even more preferably 220 seconds or less, from the viewpoint of further improving productivity.

[0038] In step (B), the wavelength of the light used for light irradiation is not particularly limited and may be appropriately adjusted to match the photopolymerization initiator contained in the resin composition for forming the first cladding layer. The wavelength of the light may be, for example, in the range of 300 nm to 420 nm. More specifically, i-line (365 nm), h-line (405 nm), g-line (436 nm), etc. may be irradiated.

[0039] In the step (B), the resin layer (a) is preferably heated from the viewpoint of further promoting the curing of the resin layer (a). When the resin layer (a) is heated, the heating may be performed simultaneously with the light irradiation or after the light irradiation, but the resin layer (a) is preferably heated after the light irradiation of the resin layer (a).

[0040] In step (B), the temperature to which the resin layer (a) is heated is preferably 100°C or higher, more preferably 120°C or higher, even more preferably 140°C or higher, and even more preferably 150°C or higher, and is preferably 180°C or lower, more preferably 170°C or lower.

[0041] In the step (B), the apparatus for performing the light irradiation is not particularly limited, and for example, an exposure machine, a UV irradiation machine, or the like may be used.

[0042] [Step (C) of Laminating a Film Having Resin Layer (b)] The method for producing a laminate of this embodiment includes, after step (B), step (C) of laminating a film having a resin layer (b) 31 made of a resin composition for forming a core layer onto the surface of the resin layer (a) 22 opposite to the substrate 110. Since step (C) is performed after step (B), the resin layer (a) is a cured resin layer (a) 22 in step (C).

[0043] Here, the resin layer (a) is made of a resin composition for forming the first clad layer, and the resin layer (b) is made of a resin composition for forming the core layer. Therefore, the laminate 300 obtained in step (C) can also be said to be a laminate 300 including, in this order, the substrate, the first clad layer of the optical waveguide, and the core layer of the optical waveguide.

[0044] In step (C), the method for laminating the film having the resin layer (b) 31 is not particularly limited, but is a method in which a workpiece in which the substrate 110, the resin layer (a) 22, and the film having the resin layer (b) 31 are superimposed is heated and pressed.

[0045] In step (C), the degree of vacuum when the workpiece is heated and pressed is not particularly limited, and the workpiece may be heated and pressed at normal pressure or under reduced pressure, but the workpiece is preferably heated and pressed under reduced pressure. The degree of vacuum when the workpiece is heated and pressed under reduced pressure is not particularly limited, but is, for example, 500 Pa or less.

[0046] In step (C), the pressure when heating and pressing the workpiece is preferably 0.1 MPa or more, more preferably 0.3 MPa or more, and even more preferably 0.4 MPa or more, from the viewpoint of further improving the adhesion between the resin layer (a) 22 and the film having the resin layer (b) 31, and is preferably 10.0 MPa or less, more preferably 8.0 MPa or less, even more preferably 6.0 MPa or less, even more preferably 5.0 MPa or less, even more preferably 3.0 MPa or less, and even more preferably 1.0 MPa or less, from the viewpoint of preventing damage to the substrate.

[0047] In step (C), the temperature for laminating the film having the resin layer (b) 31 is preferably 40°C or higher, more preferably 50°C or higher, even more preferably 55°C or higher, from the viewpoint of further improving the adhesion between the resin layer (a) 22 and the film having the resin layer (b) 31, and is preferably 180°C or lower, more preferably 150°C or lower, even more preferably 100°C or lower, even more preferably 80°C or lower.

[0048] In step (C), the time for laminating the film having the resin layer (b) 31 is preferably 10 seconds or more, more preferably 20 seconds or more, from the viewpoint of further improving the adhesion between the resin layer (a) 22 and the film having the resin layer (b) 31, and is preferably 100 seconds or less, more preferably 70 seconds or less, and even more preferably 50 seconds or less, from the viewpoint of further improving productivity.

[0049] In the step (C), when the workpiece is heated and pressed, the pressing method is not particularly limited, and may be a flat press or a roll press.

[0050] In the step (C), the apparatus for laminating the film having the resin layer (b) 31 is not particularly limited, but is preferably a vacuum laminating apparatus.

[0051] The resin layer (b) 31 is made of a resin composition for forming a core layer. The resin contained in the resin layer (b) 31 is not particularly limited, and may be any resin that can be used to form a core layer of an optical waveguide. The resin constituting the resin layer (b) 31 preferably contains a cyclic olefin-based resin, and more preferably contains a norbornene-based resin.

[0052] In step (C), the resin layer (b) 31 may be in any of an uncured state, a semi-cured state, and a cured state, but from the viewpoint of further improving the adhesion between the resin layer (a) 22 and the film including the resin layer (b) 31, it is preferably in an uncured state or a semi-cured state.

[0053] In step (C), the resin layer (b) 31 preferably contains a photopolymerization initiator, and more preferably, the photopolymerization initiator contained in the resin layer (b) 31 has the same chemical structure as the photopolymerization initiator contained in the resin composition for forming the first clad layer. The inventors believe that when the photopolymerization initiator contained in the resin layer (b) 31 has the same chemical structure as the photopolymerization initiator contained in the resin composition for forming the first clad layer, the acid derived from the photopolymerization initiator can be further suppressed from migrating between the first clad layer and the core layer, and the propagation loss of the resulting optoelectronic composite substrate can be further suppressed.

[0054] The resin layer (b) 31 may contain components such as an antioxidant as appropriate.

[0055] The film including the resin layer (b) may be a film including a layer other than the resin layer (b) 31, and may further include, for example, a substrate film. When the film including the resin layer (b) includes a substrate film, the film including the resin layer (b) is easier to handle and can prevent contamination of the laminating device. Examples of the substrate film include a polyethylene terephthalate substrate and a polyimide substrate.

[0056] [Step (D) of Heating Resin Layer (a)] The method for producing a laminate of the present embodiment preferably further includes, between steps (A) and (B), step (D) of heating the resin layer (a) 21. Since step (D) is performed between steps (A) and (B), in step (D), the resin layer (a) is the resin layer (a) 21 before curing.

[0057] According to the investigations of the present inventors, it was found that in the conventional method for manufacturing an optical / electrical composite substrate, there is a case where particles of about 5 μm in size are generated as a defect in the first clad layer (i.e., corresponding to the resin layer (a) of the present embodiment). By including step (D), the method for manufacturing a laminate of the present embodiment can further suppress the generation of particles in the resin layer (a). By further suppressing the generation of particles in the resin layer (a), it is possible to further suppress the propagation loss of the obtained optical / electrical composite substrate.

[0058] In step (D), the temperature to which the resin layer (a) is heated is preferably 120°C or higher, more preferably 125°C or higher, even more preferably 130°C or higher, even more preferably 135°C or higher, and preferably 160°C or lower, more preferably 155°C or lower, even more preferably 150°C or lower, even more preferably 145°C or lower.

[0059] In step (D), the time for heating the resin layer (a) is preferably 10 minutes or more, more preferably 20 minutes or more, and from the viewpoint of further improving productivity, is preferably 60 minutes or less, more preferably 50 minutes or less, and even more preferably 40 minutes or less.

[0060] [Other Steps] The method for producing a laminate according to the present embodiment may include other steps in addition to the steps described above. Examples of the other steps include the following steps.

[0061] <Step of forming a pattern on resin layer (b)> The method for manufacturing a laminate according to the present embodiment may include a step of forming a pattern on the resin layer (b) 31. The step of forming a pattern on the resin layer (b) 31 is performed, for example, after step (C).

[0062] By providing a step of forming a pattern in the resin layer (b) 31, a first core portion 35 and a second core portion 36 are formed in the resin layer (b) 31.

[0063] The method for forming a pattern on the resin layer (b) 31 is not particularly limited, and examples thereof include exposure, etching, and replication, with exposure being preferred.

[0064] Furthermore, after forming a pattern in the resin layer (b) 31 by exposure, the resin layer (b) may be subjected to a heat treatment.

[0065] <Step of Forming Second Clad Layer> The method for manufacturing the laminate of the present embodiment may include a step of laminating a film for forming the second clad layer 40 to form the second clad layer 40. The step of forming the second clad layer 40 is performed, for example, after the step of forming a pattern on the resin layer (b) 31. It is preferable that the second clad layer is laminated so as to be in direct contact with the resin layer (b) 31 (i.e., the core layer 30).

[0066] The method for laminating the film to form the second cladding layer 40 is not particularly limited, but a preferred method is the same as that in step (A) of this embodiment.

[0067] The resin composition constituting the second cladding layer 40 is not particularly limited as long as it is a resin composition that can be used for a cladding layer of an optical waveguide. The resin composition constituting the second cladding layer 40 may be the same as the resin composition for forming the first cladding layer, or may be a different resin composition.

[0068] The film for forming the second clad layer 40 may be a film including a layer other than the resin layer for forming the second clad layer, and may further include, for example, a substrate film. The substrate film is preferably a polyimide substrate. If the substrate film is a polyimide substrate, the polyimide substrate in the film for forming the second clad layer 40 can be used as the polyimide layer included in the optoelectronic composite substrate, which is preferable.

[0069] The method for manufacturing the laminate of this embodiment preferably further includes, after step (C), a step of forming a core layer 30 including a first core portion 35 consisting of an exposed portion of the resin layer (b) 31 and a second core portion 36 consisting of an unexposed portion of the resin layer (b) 31 by irradiating a portion of the resin layer (b) 31 with light, and a step of forming a second clad layer 40 on the core layer 30 including the first core portion 35 and the second core portion 36.

[0070] A difference in refractive index occurs between the first core portion 35 and the second core portion 36 depending on whether or not light is irradiated. The difference in refractive index allows the first core portion 35 and the second core portion 36 to be used as a waveguide pattern.

[0071] The core layer 30 preferably includes a plurality of first core portions 35 and a plurality of second core portions 36 as shown in FIG.

[0072] The method of irradiating a part of the resin layer (b) 31 with light is not particularly limited. For example, the method may be an integrated light amount of 10 mJ / cm ２ More than 1500mJ / cm ２ The light irradiation time may be set to 5 seconds or more and 300 seconds or less. The wavelength of the light used for the light irradiation may be set to, for example, 300 nm or more and 420 nm or less.

[0073] In the process of forming the first core portion 35, the second core portion 36, and the core layer 30, the resin layer (b) 31 may be heated after a portion of the resin layer (b) 31 is irradiated with light. When the resin layer (b) 31 is heated, it is preferable to heat the entire resin layer (b) 31. That is, it is preferable to heat both the exposed portion of the resin layer (b) 31 and the unexposed portion of the resin layer (b) 31. The temperature at which the resin layer (b) 31 is heated may be, for example, 100°C or higher and 180°C or lower, and preferably 120°C or higher and 170°C or lower.

[0074] The method for producing a laminate according to the present embodiment preferably does not include, after the step (C), a step of developing the resin layer (b) 31. Furthermore, the method for producing a laminate according to the present embodiment preferably does not include, after the step (C), a step of etching the resin layer (b) 31.

[0075] [Laminate] The laminate of this embodiment includes, in this order, a substrate, a first clad layer of an optical waveguide, and a core layer of the optical waveguide. Here, in the laminate of this embodiment, the first clad layer of the optical waveguide and the core layer of the optical waveguide also include resin layers for forming the first clad layer and the core layer, respectively. That is, the first clad layer of the optical waveguide conceptually includes the resin layer (a), and the core layer of the optical waveguide conceptually includes the resin layer (b).

[0076] The core layer of this embodiment preferably includes a first core portion consisting of an exposed portion of the resin layer (b) and a second core portion consisting of an unexposed portion of the resin layer (b). The core layer of this embodiment preferably includes a plurality of first core portions and a plurality of second core portions.

[0077] The laminate of this embodiment may further include other layers, for example, a laminate including a substrate, a first clad layer of an optical waveguide, a core layer of an optical waveguide, and a base film in this order.

[0078] The laminate of this embodiment is preferably an optoelectronic composite substrate further comprising a second clad layer on the core layer. That is, the optoelectronic composite substrate comprises a substrate, a first clad layer of an optical waveguide, a core layer of the optical waveguide, and a second clad layer in this order. The optoelectronic composite substrate of this embodiment may further comprise a polyimide substrate on the surface of the second clad layer opposite to the core layer.

[0079] The method for producing the optoelectronic composite substrate of this embodiment is not particularly limited, but examples thereof include the methods described in the Examples.

[0080] [Film Having Resin Layer (a)] The film having the resin layer (a) made of the resin composition for forming the first clad layer of this embodiment will be specifically described.

[0081] The thickness of the resin layer (a) is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more, and from the viewpoint of further improving the light propagation efficiency of the optical waveguide, it is preferably 200 μm or less, more preferably 150 μm or less, even more preferably 100 μm or less, even more preferably 80 μm or less, even more preferably 60 μm or less, even more preferably 40 μm or less, and even more preferably 30 μm or less.

[0082] Here, the thickness of the resin layer (a) in this specification means the thickness in a step prior to step (A). That is, in the method for producing a laminate of this embodiment, pressing may be performed when laminating the resin layer (a), but the thickness of the resin layer (a) in this specification does not mean the thickness after pressing.

[0083] The film having the resin layer (a) of this embodiment preferably further includes a substrate film, and more preferably the resin layer (a) is provided on the substrate film. The substrate film may be, for example, a resin film. The resin constituting the substrate film is not particularly limited, but preferably includes at least one or more selected from the group consisting of polyimide and polyethylene terephthalate, and more preferably includes polyethylene terephthalate.

[0084] From the viewpoint of further improving the handleability of the film, the thickness of the base film of the present embodiment is preferably 10 μm or more, more preferably 15 μm or more, even more preferably 20 μm or more, preferably 30 μm or more, and is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 60 μm or less, even more preferably 40 μm or less.

[0085] The substrate film of the present embodiment may be subjected to a surface treatment such as an antistatic treatment or a release treatment.

[0086] The film including the resin layer (a) of this embodiment can be obtained, for example, by applying a resin composition for forming the first clad layer onto a substrate film and drying it to form the resin layer (a). When applying the resin composition for forming the first clad layer onto the substrate film, the resin composition is preferably a varnish-like resin composition containing an organic solvent. The organic solvent in the resin composition is removed in the drying process. Examples of application methods include direct application using various coater devices such as a pin coater, die coater, comma coater, and curtain coater, and printing methods such as screen printing.

[0087] [Resin Composition for Forming First Clad Layer] The resin composition for forming the first clad layer of this embodiment will be specifically described. The resin composition for forming the first clad layer of this embodiment contains a photopolymerization initiator.

[0088] The resin contained in the resin composition for forming the first cladding layer of this embodiment is not particularly limited, and may be any resin that can be used in the cladding layer of an optical waveguide. The resin composition for forming the first cladding layer of this embodiment may include, for example, a polyimide resin, a compound having a cyclic ether structure, a norbornene-based resin, a copolymer of a styrene-based monomer and a diene-based monomer, etc., and preferably includes one or more selected from the group consisting of a polyimide resin and a compound having a cyclic ether structure, and more preferably includes a polyimide resin and a compound having a cyclic ether structure.

[0089] The polyimide resin of this embodiment preferably contains an imide ring structure in the molecule. The polyimide resin of this embodiment preferably contains a fluorinated polyimide. The fluorinated polyimide refers to a polyimide containing a fluorine atom.

[0090] The polyimide resin of the present embodiment may be a single type of polyimide resin, or may contain two or more types of polyimide resins.

[0091] The compound having a cyclic ether structure of the present embodiment preferably includes at least one or two or more selected from the group consisting of epoxy resins and oxetane compounds, and more preferably includes one or two or more epoxy resins.

[0092] The compound having a cyclic ether structure of this embodiment preferably contains an alicyclic structure in the molecule. Here, when a compound having a cyclic ether structure contains an alicyclic structure in the molecule, it means that the compound contains an alicyclic structure in addition to the cyclic ether structure. However, the alicyclic structure of this embodiment includes a fused ring structure in which a cyclic ether and an aliphatic ring are fused, and a spiro ring structure in which a cyclic ether and an aliphatic ring are bonded via a spiro bond atom. The number of ring members in the alicyclic structure is not particularly limited, but is preferably a 4- to 10-membered ring, more preferably a 4- to 8-membered ring, even more preferably a 5- or 6-membered ring, and even more preferably a 6-membered ring.

[0093] The compound having a cyclic ether structure of this embodiment preferably contains two or more cyclic ether structures in the molecule, and more preferably contains two or three cyclic ether structures in the molecule.

[0094] The compound having a cyclic ether structure of the present embodiment may be a compound having one type of cyclic ether structure, or may include compounds having two or more types of cyclic ether structures.

[0095] The content of the polyimide resin contained in the resin composition for forming the first clad layer of this embodiment, when the total content of the resin components in the resin composition for forming the first clad layer is taken as 100 parts by mass, is preferably 20 parts by mass or more, more preferably 23 parts by mass or more, even more preferably 25 parts by mass or more, even more preferably 28 parts by mass or more, and is preferably 80 parts by mass or less, more preferably 75 parts by mass or less, even more preferably 70 parts by mass or less, even more preferably 65 parts by mass or less.

[0096] The content of the compound having a cyclic ether structure contained in the resin composition for forming the first clad layer of this embodiment is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, even more preferably 30 parts by mass or more, and even more preferably 35 parts by mass or more, when the total content of the resin components in the resin composition for forming the first clad layer is 100 parts by mass, and is preferably 80 parts by mass or less, more preferably 75 parts by mass or less.

[0097] The total content of the polyimide resin and the compound having a cyclic ether structure contained in the resin composition for forming the first clad layer of this embodiment is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 97% by mass or more, even more preferably 98% by mass or more, and is, for example, less than 100% by mass, when the total content of non-volatile components in the resin composition for forming the first clad layer is taken as 100% by mass.

[0098] The resin composition for forming the first clad layer of this embodiment contains a photopolymerization initiator. The photopolymerization initiator is not particularly limited, and a photocationic polymerization initiator, a photoradical polymerization initiator, or the like can be used.

[0099] The photopolymerization initiator of this embodiment preferably includes a cationic photopolymerization initiator. Examples of the cationic photopolymerization initiator include a sulfonium salt-type polymerization initiator and an iodonium salt-type polymerization initiator, preferably a sulfonium salt-type polymerization initiator, more preferably a triarylsulfonium salt-type polymerization initiator, and even more preferably a triphenylsulfonium salt-type polymerization initiator.

[0100] The anion moiety of the cationic photopolymerization initiator of this embodiment preferably contains a fluorine atom.

[0101] The anion moiety of the cationic photopolymerization initiator of this embodiment preferably contains an aryl group. The aryl group has, for example, 6 to 14 carbon atoms (not including the carbon atoms of the following substituents), and some of the hydrogen atoms in the aryl group are substituted with an alkyl group having 1 to 18 carbon atoms, an alkyl group having 1 to 8 carbon atoms substituted with a halogen atom, an alkenyl group having 2 to 18 carbon atoms, an alkynyl group having 2 to 18 carbon atoms, an aryl group having 6 to 14 carbon atoms, a nitro group, a hydroxyl group, a cyano group, or -OR １ an alkoxy group or an aryloxy group represented by R ２ an acyl group represented by CO—, R ３ an acyloxy group represented by COO-; ４ an alkylthio group or an arylthio group represented by the formula: ５ R ６ or a halogen atom. １ ~R ４ is an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms, and R ５ and R ６ is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 14 carbon atoms. The aryl group is preferably one in which some of the hydrogen atoms in the aryl group have been substituted with fluorine atoms.

[0102] When the total content of the resin components in the resin composition for forming the first cladding layer is taken as 100 parts by mass, from the viewpoint of further suppressing the propagation loss of the optoelectronic composite substrate, the content of the photopolymerization initiator contained in the resin composition for forming the first cladding layer is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, even more preferably 0.05 parts by mass or more, and even more preferably 0.07 parts by mass or more, and is preferably 5.00 parts by mass or less, more preferably 3.00 parts by mass or less, even more preferably 1.00 parts by mass or less, even more preferably 0.50 parts by mass or less, even more preferably 0.30 parts by mass or less, even more preferably 0.20 parts by mass or less, and even more preferably 0.17 parts by mass or less.

[0103] The resin composition for forming the first clad layer of this embodiment may contain components such as a surfactant as appropriate.

[0104] In this embodiment, the content of the (meth)acrylic resin in the resin composition for forming the first clad layer is preferably less than 50% by mass, more preferably less than 30% by mass, even more preferably less than 10% by mass, even more preferably less than 5% by mass, even more preferably less than 1% by mass, even more preferably less than 0.1% by mass, and even more preferably 0% by mass, from the viewpoint of further improving the heat resistance of the resin composition, when the total content of non-volatile components in the resin composition for forming the first clad layer is taken as 100% by mass. Here, the term "(meth)acrylic resin" is used as a concept that includes both methacrylic resin and acrylic resin.

[0105] The resin composition for forming the first clad layer of this embodiment can be obtained, for example, by mixing the respective components.

[0106] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.

[0107] The present embodiment will be described in detail below based on examples and comparative examples, but the present embodiment is not limited to the descriptions of these examples.

[0108] [Film Having Resin Layer (a)] The preparation of a film having a resin layer (a) made of a resin composition for forming a first clad layer will be described. First, the respective raw materials constituting the resin composition for forming the first clad layer will be described.

[0109] (Synthesis of Polyimide Resin (A-1)) A 3 L separable glass flask equipped with a stirrer and a stirring blade was charged with 67.3 g (0.210 mol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 97.7 g (0.220 mol) of 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and 495 g of dimethylacetamide, and the mixture was stirred to dissolve. Further, stirring was continued at room temperature for 12 hours under a nitrogen stream to carry out a polymerization reaction, yielding a polyamic acid solution.

[0110] To the resulting polyamic acid solution, 16 g of pyridine was added, and then 82 g of acetic anhydride was added dropwise at room temperature. Thereafter, the liquid temperature was maintained at 20 to 100°C and stirring was continued for 24 hours to carry out the imidization reaction, thereby obtaining a polyimide solution.

[0111] The obtained polyimide solution was poured into 1,000 g of methanol in a 5 L container while stirring to precipitate a polyimide resin. Thereafter, the solid polyimide resin was filtered using a suction filtration device and further washed with 1,000 g of methanol. Then, the solid polyimide resin was dried at 100°C for 24 hours using a vacuum dryer and further dried at 200°C for 3 hours to obtain a powdery polyimide resin (A-1). The weight average molecular weight (Mw) of the polyimide resin (A-1) measured by GPC was 51,000. １H-NMR was measured, and the imidization rate was calculated from the quantitative value of the amide peak relative to the peak of the aromatic ring of the polyimide, and the imidization rate was found to be 99% or more. Polyimide resin (A-1) was dissolved in propylene glycol monomethyl ether acetate to a solids concentration of 25%, and then coated using an applicator to a film thickness of 30 μm. The film was then dried in an oven at 100°C for 10 minutes to obtain a polyimide coating. The refractive index of the resulting coating was measured using an Abbe refractometer (manufactured by Atago Co., Ltd., product name: NAR-1T SOLID) under conditions of 23°C and 589 nm, and the refractive index of the polyimide was found to be 1.54.

[0112] Details of the raw materials in Table 1 are as follows:

[0113] <Polyimide Resin (A)> (A-1) Polyimide resin synthesized above (Mw = 51,000, imidization rate 99% or more, refractive index n = 1.54)

[0114]

[0115] <Compound (B) Having a Cyclic Ether Structure> (B-1) Celloxide 2021P (manufactured by Daicel Corporation, epoxy resin having an alicyclic structure, liquid at 23°C, refractive index 1.51)

[0116]

[0117] <Photopolymerization initiator (C)> (C-1) CPI-310B (manufactured by San-Apro Ltd., photocationic polymerization initiator, triarylsulfonium salt) (C-2) CPI-310FG (manufactured by San-Apro Ltd., photocationic polymerization initiator, triarylsulfonium salt)

[0118] <Surfactant (D)> (D-1) BYK-333 (manufactured by BYK Japan K.K., silicone surfactant)

[0119] <Organic Solvent (E)> (E-1) Propylene glycol monomethyl ether acetate (E-2) Propylene glycol monomethyl ether

[0120] <Thermal Polymerization Initiator (F)> (F-1) San-Aid SI-110 (manufactured by Sanshin Chemical Industry Co., Ltd., thermal cationic polymerization initiator) (F-2) San-Aid SI-150 (manufactured by Sanshin Chemical Industry Co., Ltd., thermal cationic polymerization initiator)

[0121] (Preparation of Resin Composition for Forming First Clad Layer) The raw materials formulated according to Table 1 were stirred at room temperature until the raw materials were completely dissolved to obtain a solution. The solution was then filtered through a PTFE filter with a pore size of 0.2 μm to obtain the varnish-like resin compositions used in Examples 1 to 8 and Comparative Example 1.

[0122] (Preparation of film having resin layer (a)) As a PET substrate, a 38 μm thick antistatic treated polyethylene terephthalate substrate (manufactured by Nippa Corporation, product name: PET38×1-TR1-ASQ) was used. Varnish was applied using an applicator to a dried thickness of 25 μm, and then dried at 100 ° C. for 10 minutes. Finally, an OPP cover film (manufactured by Oji F-Tex Co., Ltd., product name: E201F-50 μm) was attached to the surface of the resin layer (a) formed from the resin composition to prepare a film, and the films having the resin layer (a) used in Examples 1 to 7 and Comparative Example 1 were obtained. The film having the resin layer (a) used in Example 8 was obtained in the same manner as the film having the resin layer (a) used in Examples 1 to 7 and Comparative Example 1, except that a 38 μm thick polyethylene terephthalate substrate (manufactured by Toyobo Co., Ltd., product name NB213) was used as the PET substrate.

[0123] [Film Having Resin Layer (b)] The preparation of a film having a resin layer (b) made of a resin composition for forming a core layer will be described.

[0124] (Synthesis of polymer for forming core layer) In a glove box filled with dry nitrogen and with moisture and oxygen concentrations controlled to 1 ppm or less, 7.2 g (40.1 mmol) of hexylnorbornene (HxNB) and 12.9 g (40.1 mmol) of diphenylmethylnorbornene methoxysilane were weighed into a 500 mL vial, 60 g of dehydrated toluene and 11 g of ethyl acetate were added, and the top was sealed with a silicone sealer. Next, 1.56 g (3.2 mmol) of Ni catalyst and 10 mL of dehydrated toluene were weighed into a 100 mL vial, and the vial was sealed with a stirrer tip. The Ni catalyst was thoroughly stirred to completely dissolve, and a Ni catalyst solution was obtained. 1 mL of the Ni catalyst solution was accurately measured with a syringe and quantitatively injected into the vial containing the above two norbornenes dissolved therein. After stirring at room temperature for 1 hour, a significant increase in viscosity was observed. At this point, the stopper was removed, and 60 g of tetrahydrofuran (THF) was added and stirred to obtain a reaction solution. 9.5 g of acetic anhydride, 18 g of hydrogen peroxide (30% concentration), and 30 g of ion-exchanged water were added to a 100 mL beaker and stirred to prepare an aqueous solution of peracetic acid. Next, the entire amount of the aqueous solution of peracetic acid was added to the reaction solution and stirred for 12 hours to perform a Ni reduction treatment. Next, the reaction solution after completion of the treatment was transferred to a separatory funnel, and the lower aqueous layer was removed. 100 mL of a 30% aqueous solution of isopropyl alcohol was added and vigorously stirred. After allowing to stand and allowing complete separation into two layers, the aqueous layer was removed. This water washing process was repeated a total of three times, and the oil layer was then dropped into a large excess of acetone to reprecipitate the resulting polymer. The filtrate was separated by filtration, and then heated and dried for 12 hours in a vacuum dryer set at 60 ° C to obtain a polymer for forming a core layer.

[0125] The molecular weight of the core layer-forming polymer was measured by GPC and found to be Mw = 100,000 and Mn = 40,000. The molar ratio of each structural unit in the core layer-forming polymer was identified by NMR measurement and found to be 50 mol % of hexylnorbornene structural units and 50 mol % of diphenylmethylnorbornenemethoxysilane structural units.

[0126] (Preparation of Resin Composition for Forming Core Layer) 10 g of the purified core layer-forming polymer was weighed into a 100 mL glass container, and 3 g of methylcyclohexane, 27 g of toluene, 2.4 g of Aron Oxetane (manufactured by Toagosei Co., Ltd., product name: OXT-213), 0.8 g of Celloxide 2021P (manufactured by Daicel Corporation, epoxy resin), 0.4 g of Celloxide 2000 (manufactured by Daicel Corporation, epoxy resin), and CPI-310B (manufactured by San-Apro Co., Ltd., photocation

[0066] 0.06 g of Irganox 1076 (a hindered phenol-based antioxidant, manufactured by BASF), 0.06 g of dimethylformamide (a methyl acrylate polymerization initiator), 0.003 g of Irganox 1076 (a hindered phenol-based antioxidant, manufactured by BASF), 0.1 g of Irgafox 168 (a phosphorus-based antioxidant, manufactured by BASF), and 0.025 g of Irganox 1076 were added and dissolved uniformly, and the mixture was filtered through a 0.2 µm PTFE filter to obtain a resin composition for forming a core layer.

[0127] (Preparation of film having resin layer (b)) The obtained resin composition for forming the core layer was applied to a release-treated PET substrate using an applicator so that the film thickness after drying would be 40 μm. After application, the substrate was placed in a 45° C. dryer for 5 minutes to completely remove the solvent, and then an OPP cover film (manufactured by Oji F-Tex Co., Ltd., product name: E201F-50 μm) was attached to the surface of the resin layer (b) formed from the resin composition, thereby obtaining a film having resin layer (b).

[0128] [Preparation of Second Clad Layer-Forming Film] (Preparation of Second Clad Layer-Forming Resin Composition) 300.6 parts by mass of toluene, 91.7 parts by mass of Septon Q1250 (Kuraray Co., Ltd., rubber-based elastomer), 2.8 parts by mass of BYK-361N (BYK Japan K.K., acrylic polymer-based surfactant), 2.8 parts by mass of X-12-1281C (Shin-Etsu Chemical Co., Ltd., silane coupling agent), and 2.8 parts by mass of Curesol C11z (Shikoku Kasei Corporation, imidazole-based compound) were stirred at room temperature until each raw material was completely dissolved to obtain a solution. The solution was then filtered through a PTFE filter with a pore size of 0.2 μm to obtain a second clad layer-forming resin composition.

[0129] (Preparation of Film for Forming Second Clad Layer) The resin composition for forming the second clad layer was applied as a varnish using an applicator onto a polyimide substrate (manufactured by UBE Corporation, product name: Upilex 25S) having a thickness of 25 μm so that the film would have a thickness of 10 μm after drying. The varnish was then dried at 160° C. for 10 minutes, and finally an OPP cover film (manufactured by Oji F-Tex Corporation, product name: E201F-50 μm) was attached to the surface of the resin layer formed from the resin composition, thereby obtaining a film for forming a second clad layer.

[0130] [Examples 1 to 7] <Step (A) of laminating a substrate and a film having a resin layer (a)> A double-sided copper-clad laminate was placed as a substrate on a stainless steel plate. The OPP cover film of the film having the resin layer (a) of Examples 1 to 7 was peeled off, and the double-sided copper-clad laminate and the film having the resin layer (a) of Examples 1 to 7 were overlapped with each other so that the surface of the double-sided copper-clad laminate opposite the stainless steel plate was in contact with the resin layer (a) of the film having the resin layer (a) used in Examples 1 to 7. Next, using a vacuum laminator (manufactured by Nikko Materials Co., Ltd., product name: CVP-300), the double-sided copper-clad laminate and the film comprising the resin layer (a) of Examples 1 to 7 were each laminated under conditions of temperature: 140°C, pressure: 0.5 MPa, and time: 120 seconds to obtain laminates each having a layer configuration of "double-sided copper-clad laminate / resin layer (a) (first clad layer) / PET substrate." The PET substrate in the laminate was the PET substrate derived from the film comprising the resin layer (a) of Examples 1 to 7.

[0131] <Step (D) of Heating Resin Layer (a)> The laminates of Examples 1 to 7 having a layer structure of "double-sided copper-clad laminate / resin layer (a) (first clad layer) / PET substrate" were placed in an oven at 140°C for 30 minutes.

[0132] <Step (B) of photocuring resin layer (a)> After step (D), the PET substrate surface of each of the laminates having a layer configuration of "double-sided copper-clad laminate / resin layer (a) (first clad layer) / PET substrate" in Examples 1 to 7 was irradiated with light under the conditions shown in Table 1 using a direct imaging exposure machine (manufactured by SCREEN Corporation, product name: LI-9000), and after the light irradiation, the laminate was placed in an oven at 160°C for 30 minutes, thereby photocuring the resin layer (a).

[0133] <Step (C) of Laminating a Film Having a Resin Layer (b)> After step (B), the PET substrate of the laminate having the layer configuration of "double-sided copper-clad laminate / resin layer (a) (first clad layer) / PET substrate" in Examples 1 to 7 was peeled off, and the laminate and the film having the resin layer (b) were respectively superimposed such that the resin layer (a) of the laminate and the resin layer (b) of the film having the resin layer (b) were in contact. At this time, the OPP cover film of the film having the resin layer (b) was peeled off. Next, using a vacuum laminator (manufactured by Nikko Materials Co., Ltd., product name: CVP-300), the laminate and the film having the resin layer (b) were laminated under conditions of temperature: 60 ° C., pressure: 0.5 MPa, and time: 30 seconds to obtain laminates of "double-sided copper-clad laminate / resin layer (a) (first clad layer) / resin layer (b) (core layer) / PET substrate". The PET substrate in the laminate is a PET substrate derived from the film having the resin layer (b).

[0134] <Step of forming a pattern on the resin layer (b)> The PET substrate was peeled off from the laminate of "double-sided copper-clad laminate / resin layer (a) (first clad layer) / resin layer (b) (core layer) / PET substrate" in Examples 1 to 7, and 20 lines and spaces, each 9 cm long and 50 μm wide, were created on the resin layer (b) using a direct imaging exposure machine (manufactured by SCREEN Co., Ltd., product name: LI-9000). Subsequently, the product was placed in an oven at 150° C. for 30 minutes. When removed from the oven, it was confirmed that a clear waveguide pattern (multiple core portions) with a rectangular cross section appeared on the coating.

[0135] <Step of Laminating Second Clad Layer> After the step of forming a pattern on the resin layer (b), the laminate and the second clad layer-forming film were each superimposed such that the resin layer (b) of the laminate of "double-sided copper-clad laminate / resin layer (a) (first clad layer) / resin layer (b) (core layer)" of Examples 1 to 7 was in contact with the second clad layer of the second clad layer-forming film. At this time, the OPP cover film of the second clad layer-forming film was peeled off. Next, using a vacuum laminator (manufactured by Nikko Materials Co., Ltd., product name: CVP-300), the laminate and the second clad layer-forming film were laminated under conditions of temperature: 140°C, pressure: 0.5 MPa, and time: 210 seconds, to obtain laminates each having a layer configuration of "double-sided copper-clad laminate / first clad layer / core layer / second clad layer / polyimide substrate." The polyimide substrate in the laminate was the polyimide substrate derived from the film for forming the second cladding layer. The resulting laminate was used as the optoelectronic composite substrate of Examples 1 to 7.

[0136] Example 8 An optoelectronic composite substrate of Example 8 was obtained in the same manner as in Examples 1 to 7, except that the step (D) of heating the resin layer (a) was not carried out.

[0137] Comparative Example 1 A laminate having a layer structure of "double-sided copper-clad laminate / first clad layer / core layer / second clad layer / polyimide substrate" was obtained using a film including the resin layer (a) of Comparative Example 1 by the same manufacturing method as in Examples 1 to 7, except that step (D) of heating the resin layer (a) and step (B) of photocuring the resin layer (a) were not performed. The obtained laminate was heat-treated in an oven at 160°C for 2 hours to obtain the optoelectronic composite substrate of Comparative Example 1.

[0138] [Evaluation] Evaluation methods for the Examples and Comparative Examples will be described below.

[0139] <Optical Loss Evaluation> The optoelectronic composite substrates obtained in Examples 1 to 8 and Comparative Example 1 were cut by dicing on both sides so that the length of the patterned portion was 7 cm, to obtain samples for optical loss evaluation. The propagation loss [dB] of the optical loss evaluation samples was evaluated in accordance with the cutback method in 4.6.2.1 of "Test Methods for Polymer Optical Waveguides (JPCA-PE02-05-01S-2008)." Note that light with a wavelength of 850 nm was used for the measurement. The results of the optical loss evaluation are shown in Table 1.

[0140] <Evaluation of Film Appearance> (Preparation of Laminate) The OPP cover film was peeled off from the film comprising the resin layer (a) used in Examples 1 to 8 and Comparative Example 1, and the film comprising the resin layer (a) used in Examples 1 to 8 and Comparative Example 1 was superimposed on the PET film so that the resin layer (a) of Examples 1 to 8 and Comparative Example 1 came into contact with the PET film. Next, using a vacuum laminator (manufactured by Nikko Materials Co., Ltd., product name: CVP-300), the film comprising the resin layer (a) used in Examples 1 to 8 and Comparative Example 1 was laminated on the PET film under conditions of temperature: 140°C, pressure: 0.5 MPa, and time: 120 seconds to obtain each laminate. The layer structure of the laminate was "PET film / resin layer (a) / PET substrate derived from the film comprising the resin layer (a)".

[0141] (Laminate Treatment) The laminate of the film and PET film provided with the resin layer (a) used in Examples 1 to 7 was placed in a 140 ° C. oven for 30 minutes. Then, using a direct imaging exposure machine (manufactured by SCREEN Corporation, product name: LI-9000), light irradiation was performed under the conditions described in Table 1, and after light irradiation, the laminate was placed in a 160 ° C. oven for 30 minutes to photocure the resin layer (a), thereby obtaining a sample for appearance evaluation. The treatment of the laminates in Examples 1 to 7 is a treatment that simulates step (D) and step (B). The laminate of the film and PET film provided with the resin layer (a) used in Example 8 was placed in a direct imaging exposure machine (manufactured by SCREEN Corporation, product name: LI-9000) to light irradiation under the conditions described in Table 1, and after light irradiation, the laminate was placed in a 160 ° C. oven for 30 minutes to photocure the resin layer (a), thereby obtaining a sample for appearance evaluation. The treatment of the laminate in Example 8 was a treatment simulating step (B). In Comparative Example 1, the laminate was not treated and used as a sample for appearance evaluation.

[0142] The resin layer (a) of the samples for appearance evaluation of Examples 1 to 8 and Comparative Example 1 was observed using an optical measuring microscope (manufactured by Mitutoyo Corporation, product name: MF-UA1730THD). The observation results were evaluated according to the following criteria: A (good): No defects (particles about 5 μm in size) were observed B (poor): Defects (particles about 5 μm in size) were observed The results of the appearance evaluation are shown in Table 1.

[0143]

[0144] It can be seen from Table 1 that the optoelectronic composite substrate obtained by the laminate manufacturing method of the example has reduced propagation loss compared to the optoelectronic composite substrate of the comparative example. That is, the laminate manufacturing method of this embodiment can obtain a laminate that can reduce the propagation loss of the optoelectronic composite substrate.

[0145] Furthermore, the appearance evaluation samples of the examples had good results in the appearance evaluation. The inventors believe that the laminates obtained by the laminate manufacturing methods of the examples have good appearance evaluations, and therefore it is possible to suppress the propagation loss of the optoelectronic composite substrate.

[0146] This application claims priority based on Japanese Patent Application No. 2023-057401, filed March 31, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0147] 20 First clad layer 21 Resin layer (a) 22 Cured resin layer (a) 30 Core layer 31 Resin layer (b) 35 First core portion 36 Second core portion 40 Second clad layer 100 Optical waveguide 110 Substrate 200 Opto-electrical composite substrate 300 Laminate

Claims

1. A method for manufacturing a laminate including, in this order, a substrate, a first clad layer of an optical waveguide, and a core layer of the optical waveguide, the method comprising the steps of: A step (A) of laminating the substrate and a film having a resin layer (a) made of a resin composition for forming the first clad layer; A step (B) of photocuring the resin layer (a) after the step (A); and (C) a step of laminating a film including a resin layer (b) made of a resin composition for forming the core layer on a surface of the resin layer (a) opposite to the substrate side after the step (B), A method for manufacturing a laminate, wherein a resin composition for forming the first clad layer contains a photopolymerization initiator (excluding a method for manufacturing a laminate including a step of embedding an optical path changing component that becomes an optical path changing section into the uncured first clad layer).

2. The method for producing a laminate according to claim 1 , further comprising a step (D) of heating the resin layer (a) between the step (A) and the step (B).

3. The method for producing a laminate according to claim 2 , wherein in the step (D), the resin layer (a) is heated under conditions of 120° C. or more and 160° C. or less.

4. In the step (B), the integrated light amount is 10 mJ / cm ２ More than 1500mJ / cm ２ The method for producing a laminate according to any one of claims 1 to 3, wherein the resin layer (a) is photocured under the following conditions:

5. The method for producing a laminate according to any one of claims 1 to 3, wherein in the step (C), the resin layer (b) is in an uncured state or a semi-cured state.

6. a step of irradiating a part of the resin layer (b) with light after the step (C) to form a core layer including a first core portion consisting of an exposed part of the resin layer (b) and a second core portion consisting of an unexposed part of the resin layer (b); The method for manufacturing a laminate according to any one of claims 1 to 3, further comprising the step of forming a second clad layer on the core layer including the first core portion and the second core portion.

7. The method for producing a laminate according to any one of claims 1 to 3, wherein a content of the photopolymerization initiator contained in the resin composition for forming the first clad layer is 0.01 parts by mass or more and 5.00 parts by mass or less when a total content of resin components in the resin composition for forming the first clad layer is 100 parts by mass.

8. The method for producing a laminate according to any one of claims 1 to 3, wherein the photopolymerization initiator contained in the resin composition for forming the first clad layer includes a photocationic polymerization initiator.

9. The method for producing a laminate according to claim 8 , wherein the photocationic polymerization initiator includes a sulfonium salt type polymerization initiator.

10. The method for producing a laminate according to any one of claims 1 to 3, wherein the resin composition for forming the first clad layer contains one or more selected from the group consisting of polyimide resins and compounds having a cyclic ether structure.

11. In the step (C), the resin layer (b) contains a photopolymerization initiator, The method for producing a laminate according to any one of claims 1 to 3, wherein the photopolymerization initiator contained in the resin layer (b) has the same chemical structure as the photopolymerization initiator contained in the resin composition for forming the first clad layer.

12. The method for producing a laminate according to any one of claims 1 to 3, wherein the laminate is an optical / electrical composite substrate further comprising a second clad layer on a core layer.