Manufacturing method of laminate

Abstract

A method for manufacturing a laminate comprising a substrate (110) and a first clad layer of an optical waveguide, the method comprising: a step (A) of preparing a work (350) comprising at least the substrate (110); and a step (B) of attaching an adhesive member (450) to one side of the substrate (110) in the work (350).

Description

[Technical field]

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

[0002] 2. Description of the Related Art In recent years, there has been a demand for components capable of realizing more advanced information communication, such as larger capacity information and faster information communication speeds, in information and communication devices. As one such component, an optical / electrical composite substrate has been considered.

[0003] An example of the optical / electrical composite substrate is one in which an optical waveguide is provided on a substrate. As techniques relating to optical and electrical composite substrates, for example, the techniques described in Patent Documents 1 and 2 can be mentioned.

[0004] Patent Document 1 describes an opto-electrical hybrid board comprising a flexible circuit board in which electrical wiring having mounting pads is formed on the surface of an insulating layer, an element mounted on the mounting pad, 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 in which electrical wiring is also formed on the back surface of the insulating layer, and a metallic reinforcing layer is formed by plating on at least the portion of the electrical wiring on the back surface that corresponds to the mounting pad, and the optical waveguide is in contact with the metallic reinforcing layer. According to the optical-electrical hybrid board described in Patent Document 1, a metallic reinforcing layer is adhered to an insulating layer of a flexible circuit board without an adhesive layer, and it is described that an optical-electrical hybrid board can be provided in which elements are properly mounted while suppressing deformation due to a pressure load when the elements are mounted by the metallic reinforcing layer.

[0005] Patent Document 1 describes a method of 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 an optical path in the substrate (see paragraph 0023 of Patent Document 1). It also describes a flexible double-sided circuit board E on which a metallic reinforcing layer M is formed (see paragraph 0028 of Patent Document 1). The flexible double-sided circuit board E includes the substrate. Furthermore, Patent Document 1 describes that an undercladding layer 6 is formed on the back side of a flexible double-sided circuit board E in contact with a metal reinforcing layer M that covers the electrical wiring 2B on the back side, and describes that examples of a molding material for the undercladding layer 6 include photosensitive resins and thermosetting resins (see paragraph 0029 of Patent Document 1). According to Figures 4 to 6 of Patent Document 1, it can be seen that the molding material for the undercladding layer 6 is filled into a recess formed in the flexible double-sided circuit board E on which the metal reinforcing layer M is formed.

[0006] Patent Document 2 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 is formed with external connection terminals for mounting optical elements and / or package substrates on which optical elements are mounted, and at least one of the flex sections is formed with optical wiring. According to the optoelectronic wiring board of Patent Document 2, it is described that large-volume information processing and high-speed information processing can be suitably performed without increasing the size of the wiring board.

[0007] Patent Document 2 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 2). Furthermore, Patent Document 2 describes that the optical signal transmitting region is formed so as to penetrate all of the substrates and insulating layers that constitute the rigid section (see claim 6 of Patent Document 2).

[0008] Furthermore, Patent Document 2 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 2). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2014-238455 A [Patent Document 2] JP 2006-140233 A Summary of the Invention [Problem to be solved by the invention]

[0010] As described in Patent Documents 1 and 2, in conventional technology relating to optoelectronic composite substrates, there is known an optoelectronic composite substrate in which recesses and through holes formed in a substrate are filled with a resin composition.

[0011] In a method for producing an optical / electrical composite substrate, for example, a method including a step of forming a first clad layer of an optical waveguide on a substrate to obtain a laminate including the substrate and the first clad layer of the optical waveguide is included. According to the study by the present inventors, it was found that warping may occur in such a laminate.

[0012] The present invention has been made in consideration of the above circumstances, and provides a method for producing a laminate capable of suppressing the amount of warping. [Means for solving the problem]

[0013] According to the present invention, there is provided a method for producing a laminate as described below.

[0014] [1] A method for manufacturing a laminate including a substrate and a first clad layer of an optical waveguide, comprising the steps of: A step (A) of preparing a workpiece having at least the substrate; A method for manufacturing a laminate, comprising: a step (B) of attaching an adhesive member to one surface of the substrate in the work. [2] The method for producing a laminate according to [1] above, wherein the adhesive member comprises a base material layer and an adhesive resin layer. [3] The method for producing a laminate according to [2] above, wherein the thickness of the base layer is 10 μm or more and 1000 μm or less. [4] The substrate layer is a resin film, The method for producing a laminate according to [2] or [3] above, wherein the resin constituting the resin film includes at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. [5] The method for producing a laminate according to any one of the above [2] to [4], wherein the adhesive constituting the adhesive resin layer includes at least one selected from the group consisting of (meth)acrylic adhesives, silicone adhesives, urethane adhesives, and rubber adhesives. [6] The method for producing a laminate according to any one of the above [1] to [5], wherein the adhesive strength of the adhesive member to a polyethylene terephthalate test plate, measured by the following method, is 1 mN / 25 mm or more and 230 mN / 25 mm or less. [method] The adhesive member is attached to a polyethylene terephthalate test plate, and pressed back and forth once with a 2 kg rubber roller. After leaving it for 24 hours, the adhesive member is peeled off in a 180 degree direction at a pulling speed of 300 mm / min. The test environment is 23°C and 50% RH. [7] The method for producing a laminate according to any one of the above [1] to [6], further comprising the step (C) of removing the adhesive member from the substrate. [8] The method for producing a laminate according to any one of the above [1] to [7], wherein the substrate is a substrate for mounting an optical waveguide. [9] The method for producing a laminate according to any one of the above [1] to [8], wherein the workpiece is a laminate of the substrate and a layer made of a resin composition for forming the first clad layer.

[10] The method for producing a laminate according to any one of the above [1] to [9], wherein the substrate has a through hole.

[11] The method for manufacturing a laminate described in

[10] above, wherein, when the volume of the through hole of the workpiece is 100 volume %, 70 volume % or more of the through hole is filled with a resin composition for forming the first clad layer.

[12] The method for producing a laminate according to any one of the above [9] to

[11] , wherein the resin composition for forming the first cladding layer in the work is in a semi-cured or cured state.

[13] The method for producing a laminate according to any one of the above [9] to

[12] , further comprising, after the step (B), a step (D) of laminating a film comprising a layer made of a resin composition for forming a core layer onto the layer made of a resin composition for forming the first clad layer.

[14] The method for producing a laminate according to item

[13] above, further comprising, after step (D), a step (E) of laminating a film comprising a layer made of a resin composition for forming a second clad layer onto the layer made of a resin composition for forming the core layer.

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

[14] above, wherein the laminate is an optical / electrical composite substrate further comprising a core layer and a second clad layer in this order on the first clad layer. Effect of the Invention

[0015] According to the present invention, a method for manufacturing a laminate capable of suppressing the amount of warping can be provided. [Brief description of the drawings]

[0016] [Figure 1]1 is a cross-sectional view showing a schematic example of a structure of an optical / electrical composite substrate according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic example of a structure of a workpiece. [Diagram 3] FIG. 1 is a diagram illustrating an example of step (B). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings are simplified and do not correspond to the actual dimensional ratio. The numerical range "A to B" represents A or more and B or less unless otherwise specified. In addition, in this specification, "(meth)acrylic" means "at least one of acrylic and methacrylic".

[0018] FIG. 1 is a cross-sectional view showing a schematic example of the structure of an optical / electrical composite substrate according to the present embodiment. As shown in FIG. 1, the optical / electrical composite substrate 200 has an optical waveguide 100 provided on a substrate 110. The optical waveguide 100 has a first clad layer 20, a core layer 30, and a second clad layer 40 laminated in this order. A mirror 50 on the light-emitting element side and a mirror 60 on the light-receiving element side are formed on the optical waveguide 100. The substrate 110 has through-holes 140 (140a, 140b) (the through-hole 140 shown in FIG. 1 is filled with the first clad layer 20). A light-emitting element 120 and a light-receiving element 130 are provided on the side of the substrate 110 opposite to the optical waveguide 100 side.

[0019] The propagation path of light in the photoelectric composite substrate 200 will be specifically described with reference to Fig. 1. The light emitted from the light emitting portion of the light emitting element 120 passes through a through hole 140a formed in the substrate 110, enters the mirror 50 on the light emitting element side, and is transmitted through the core layer 30. Thereafter, it enters the mirror 60 on the light receiving element side, passes through a through hole 140b formed in the substrate 110, and enters the light receiving element 130. The arrows in Fig. 1 are a schematic representation of the propagation of light.

[0020] In one example of a method for manufacturing an optical-electrical composite substrate, the steps of forming a first clad layer on a substrate to obtain a laminate comprising the substrate and the first clad layer, forming a core layer on the first clad layer of the obtained laminate, and forming a second clad layer on the core layer are sequentially carried out.

[0021] According to the study of the present inventors, it was found that warpage may occur in a laminate including a substrate and a first clad layer (hereinafter, "warpage amount" refers to the degree of warpage of the laminate, and a laminate with a large warpage is also referred to as a large warpage amount). If the warpage amount is large, the handling property in the next process may be deteriorated. Therefore, a laminate with a reduced warpage amount is required.

[0022] The present invention has been made in consideration of the above circumstances, and provides a method for producing a laminate capable of suppressing the amount of warping.

[0023] The method for manufacturing a laminate of this embodiment is a method for manufacturing a laminate comprising a substrate and a first clad layer of an optical waveguide, and comprises a step (A) of preparing a workpiece comprising at least a substrate, and a step (B) of attaching an adhesive member to one side of the substrate in the workpiece.

[0024] Hereinafter, each step of the method for producing the laminate of this embodiment will be specifically described.

[0025] [Work preparation process (A)] The method for producing a laminate of this embodiment includes a step (A) of preparing a workpiece including at least a substrate.

[0026] The workpiece of this embodiment includes at least a substrate. The substrate is not particularly limited, and examples thereof include a printed circuit board and a flexible substrate. A flexible substrate is preferable, and a flexible double-sided copper-clad laminate is more preferable. The substrate is preferably a substrate for mounting an optical waveguide.

[0027] The thickness of the substrate is preferably 10 μm or more, more preferably 30 μm or more, even more preferably 40 μm or more, and even more preferably 45 μm or more, and from the viewpoint of miniaturizing the optoelectronic composite substrate, it is preferably 1000 μm or less, more preferably 800 μm or less, even more preferably 500 μm or less, even more preferably 300 μm or less, even more preferably 200 μm or less, even more preferably 100 μm or less, and even more preferably 80 μm or less.

[0028] The substrate preferably has a through hole. When the substrate has a through hole, it may have one through hole or two or more through holes. 1, the substrate 110 has a through hole 140a on the light emitting element side and a through hole 140b on the light receiving element side. In such a substrate 110, the through hole 140 can be used as a light propagation path.

[0029] The hole diameter of the through hole is preferably 10 μm or more, more preferably 30 μm or more, even more preferably 50 μm or more, even more preferably 70 μm or more, even more preferably 90 μm or more, and preferably 1000 μm or less, more preferably 800 μm or less, even more preferably 500 μm or less, even more preferably 400 μm or less, even more preferably 350 μm or less, even more preferably 300 μm or less, even more preferably 250 μm or less, even more preferably 220 μm or less. Here, when the substrate has a plurality of through holes, it is sufficient that the hole diameter of at least one of the through holes is within the above range.

[0030] When the thickness of the substrate is T [μm] and the hole diameter of the through hole is R [μm], T / R is preferably 0.10 or more, more preferably 0.13 or more, even more preferably 0.15 or more, even more preferably 0.20 or more, even more preferably 0.25 or more, even more preferably 0.30 or more, even more preferably 0.35 or more, even more preferably 0.40 or more, even more preferably 0.45 or more, and even more preferably 0.60 or more, and the upper limit is not particularly limited, and may be, for example, 2.00 or less, 1.50 or less, or 1.00 or less. Here, when the substrate has a plurality of through holes, it is sufficient that the T / R of at least one of the through holes is within the above range.

[0031] The workpiece of this embodiment may be a laminate in which a substrate and a layer other than the substrate are laminated. FIG. 2 is a cross-sectional view showing a schematic example of a structure of a workpiece. As shown in FIG. 2, the workpiece 350 preferably comprises a substrate 110 and a layer 310 of a resin composition for forming the first clad layer, and more preferably, the substrate 110 and the layer 310 of a resin composition for forming the first clad layer are in direct contact with each other.

[0032] Hereinafter, in this specification, for the sake of simplicity, the "layer made of a resin composition for forming a first cladding layer" may be referred to as the "resin layer (a)".

[0033] The resin composition for forming the first cladding layer is not particularly limited as long as it is a resin composition that can be used to form a cladding layer of an optical waveguide, but preferred embodiments are as follows.

[0034] The resin contained in the resin composition for forming the first clad layer is not particularly limited, and preferably contains at least one selected from the group consisting of polyimide resins, compounds having a cyclic ether structure, and copolymers of styrene-based monomers and diene-based monomers.

[0035] The resin composition for forming the first clad layer preferably contains a polymerization initiator. Examples of the polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator, and preferably includes 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, and preferably includes a photocationic polymerization initiator.

[0036] The resin composition for forming the first cladding layer may appropriately contain components such as a surfactant.

[0037] The resin composition for forming the first cladding layer preferably contains a polyimide resin and a compound having a cyclic ether structure, and more preferably contains a polyimide resin, a compound having a cyclic ether structure, and a polymerization initiator.

[0038] In the workpiece in step (A), the thickness of the resin layer (a) 310 is preferably 10 μm or more, more preferably 12 μm or more, even more preferably 15 μm or more, and even more preferably 18 μm or more, and from the viewpoint of further improving the light propagation efficiency of the optical waveguide, it is preferably 300 μm or less, more preferably 250 μm or less, even more preferably 200 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.

[0039] In the workpiece of this embodiment, the through-hole 140 may be filled with a resin composition for forming a first cladding layer. In the work of this embodiment, the proportion of the resin composition for forming the first cladding layer filled in the through hole is, when the volume of the through hole is 100 volume%, from the viewpoint of further suppressing the propagation loss of the optical waveguide, preferably 70 volume% or more, more preferably 75 volume% or more, even more preferably 80 volume% or more, even more preferably 85 volume% or more, even more preferably 90 volume% or more, even more preferably 95 volume% or more, even more preferably 98 volume% or more, even more preferably 99 volume% or more, and is, for example, 100 volume% or less.

[0040] The method for filling the through holes with the resin composition for forming the first clad layer is not particularly limited, but examples include a method in which a substrate having a through hole and a film having a resin layer (a) are superimposed on each other, and a vacuum laminator is used to laminate the substrate having a through hole and the film having the resin layer (a), thereby filling the through holes with the resin composition for forming the first clad layer.

[0041] In the resin layer (a) in the workpiece of this embodiment, the resin composition for forming the first clad layer may be an uncured body, a semi-cured body, or a cured body, but is preferably a semi-cured body or a cured body, and more preferably a cured body. In the resin layer (a) in the work of this embodiment, if the resin composition for forming the first clad layer is a cured product, the appearance of the resulting laminate is further improved.

[0042] The workpiece of this embodiment preferably further includes a base film, more preferably has the substrate, the resin layer (a), and the base film laminated in this order, and even more preferably has the substrate, the resin layer (a), and the base film laminated in this order so that they are in contact with each other.

[0043] The base film may be, for example, a resin film. The resin constituting the base film is not particularly limited, but includes, for example, at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, cycloolefin polymer, polycarbonate, and polyimide, more preferably at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and even more preferably polyethylene terephthalate.

[0044] From the viewpoint of further improving handleability, the thickness of the base film 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 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.

[0045] The substrate film may be subjected to a surface treatment such as an antistatic treatment or a release treatment.

[0046] The method for manufacturing the workpiece of this embodiment is not particularly limited, but may be, for example, the following method. When the workpiece is a substrate having a through hole, for example, the workpiece is obtained by forming the hole in the substrate by any method.

[0047] When the workpiece further includes the resin layer (a) and the base film, the workpiece can be obtained, for example, by the following method. First, a film in which the resin layer (a) and the base film are laminated is prepared, and then the substrate and the film in which the resin layer (a) and the base film are laminated are superimposed, and laminated using a vacuum laminator to obtain a workpiece. Furthermore, the resin layer (a) may be exposed to light and heated to form a workpiece in which the resin composition for forming the first cladding layer is cured.

[0048] [Step (B) of attaching adhesive material] The method for producing a laminate of this embodiment includes a step (B) of attaching an adhesive member to one surface of a substrate in a work. Step (B) is carried out after step (A). An optional step may be further included between step (A) and step (B).

[0049] FIG. 3 is a diagram for explaining an example of step (B). FIG. 3 is a diagram showing an adhesive member 450 attached to one surface of a substrate 110 in a workpiece 350. In FIG. When the workpiece 350 further includes the resin layer (a) 310 as shown in FIG. 3, an adhesive member 450 is attached to the surface of the substrate 110 opposite to the resin layer (a) 310.

[0050] There are no particular limitations on the adhesive member 450 as long as it can be attached to one surface of the substrate 110, but the preferred embodiment is as follows.

[0051] The adhesive member 450 preferably includes a base layer 420 and an adhesive resin layer 410 . The adhesive member 450 may have an adhesive resin layer 410 on only one side of the base layer 420, or may have an adhesive resin layer 410 on both sides of the base layer 420, but preferably has an adhesive resin layer 410 on only one side of the base layer 420.

[0052] The adhesive member 450 preferably includes a base layer 420 from the viewpoint of further suppressing the amount of warping. The base layer 420 is not particularly limited, and may be, for example, a plate member, a resin film, or the like.

[0053] When the base layer 420 is a plate member, specifically, for example, a glass plate; a metal plate such as a copper plate or a stainless steel plate; or the like can be used.

[0054] The base layer 420 is preferably a resin film. The resin constituting the resin film is not particularly limited, but preferably contains at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and more preferably contains polyethylene terephthalate.

[0055] From the viewpoint of further suppressing the amount of warping, the thickness of the base material layer 420 is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 40 μm or more, even more preferably 60 μm or more, even more preferably 80 μm or more, even more preferably 100 μm or more, even more preferably 110 μm or more, and even more preferably 120 μm or more, and the upper limit is not particularly limited, and may be, for example, 1000 μm or less, 800 μm or less, 600 μm or less, 400 μm or less, 300 μm or less, 250 μm or less, 200 μm or less, or 130 μm or less.

[0056] The adhesive resin layer 410 is a layer for attaching the adhesive member 450 to the workpiece 350 .

[0057] The adhesive resin layer 410 is made of, for example, an adhesive. The adhesive constituting the adhesive resin layer 410 is not particularly limited, but preferably includes at least one selected from the group consisting of a (meth)acrylic adhesive, a silicone adhesive, a urethane adhesive, and a rubber adhesive, more preferably includes at least one selected from the group consisting of a (meth)acrylic adhesive and a silicone adhesive, and even more preferably includes a (meth)acrylic adhesive.

[0058] The adhesive resin layer 410 may be one whose adhesive strength decreases when heated or irradiated with light, for example. The adhesive resin layer 410 can have its adhesive strength reduced by heating or light irradiation, for example, by using an adhesive containing a resin that hardens when heated or irradiated with light as the adhesive that constitutes the adhesive resin layer 410.

[0059] The adhesive member 450 may include other layers in addition to the base layer 420 and the adhesive resin layer 410 .

[0060] The adhesive strength of the adhesive member 450 to a stainless steel test plate, measured in accordance with JIS Z 0237 (2009), is preferably 1 mN / 10 mm or more, more preferably 5 mN / 10 mm or more, even more preferably 8 mN / 10 mm or more, and from the viewpoint of further improving the peelability of the adhesive member, is preferably 500 mN / 10 mm or less, more preferably 300 mN / 10 mm or less, even more preferably 100 mN / 10 mm or less.

[0061] The adhesive strength of the adhesive member 450 to a polyethylene terephthalate test plate is preferably 1 mN / 25 mm or more, more preferably 10 mN / 25 mm or more, more preferably 20 mN / 25 mm or more, even more preferably 40 mN / 25 mm or more, and even more preferably 60 mN / 25 mm or more, and from the viewpoint of further improving the peelability of the adhesive member, it is preferably 230 mN / 25 mm or less, more preferably 210 mN / 25 mm or less, even more preferably 150 mN / 25 mm or less, and even more preferably 120 mN / 25 mm or less.

[0062] The adhesive strength of the adhesive member 450 to a polyethylene terephthalate test plate means a value measured by the following method. [method] The adhesive member 450 is attached to a polyethylene terephthalate test plate, pressed back and forth once with a 2 kg rubber roller, and after leaving it for 24 hours, the adhesive member 450 is peeled off in a 180° direction at a pulling speed of 300 mm / min. The test environment is 23°C and 50% RH.

[0063] The adhesive member 450 may be, for example, a commercially available adhesive tape. Examples of commercially available adhesive tapes include SRL-050F (SFCL) (manufactured by Lintec Corporation), SRL-125F (SF) (manufactured by Lintec Corporation), SRL-0753 (AS) (manufactured by Lintec Corporation), and Rioelm LE905-T (manufactured by Toyochem Co., Ltd.).

[0064] In step (B), the method for attaching the adhesive member to one surface of the substrate in the work is not particularly limited, and the adhesive member may be attached manually or by using a tape applicator or the like.

[0065] [Step (C) of removing the adhesive member] The method for producing a laminate of the present embodiment preferably further comprises the step (C) of removing the adhesive member from the substrate. Step (C) is carried out after step (B). An optional step may be further included between step (B) and step (C).

[0066] In the step (C), the adhesive member may be heated or irradiated with light to reduce the adhesive strength of the adhesive resin layer in the adhesive member. Specifically, for example, in step (C), the laminate including the workpiece and the adhesive member may be heated using an oven. The heating conditions may be, for example, a heating temperature of 120° C. or more and 160° C. or less, and a heating time of 30 minutes or more and 120 minutes or less.

[0067] In step (C), the method for removing the adhesive member from the substrate is not particularly limited, and the adhesive member may be peeled off from the substrate by hand, or the adhesive member may be peeled off from the substrate using a tape peeler or the like.

[0068] [Step (D) of laminating a film having a layer made of a resin composition for forming a core layer] The method for producing the laminate of this embodiment preferably further comprises, after step (B), a step (D) of laminating a film comprising a layer made of a resin composition for forming a core layer onto the layer made of a resin composition for forming the first clad layer.

[0069] Step (D) is performed after step (B). An optional step may be further included between step (B) and step (D). For example, when the workpiece includes a base film, a step of peeling off the base film may be further included between step (B) and step (D).

[0070] When the method for producing a laminate of the present embodiment further includes step (C), step (D) is preferably carried out prior to step (C).

[0071] There is no particular limitation on the resin composition for forming the core layer, so long as it is a resin composition capable of forming a core layer of an optical waveguide. The resin contained in the resin composition for forming the core layer includes, for example, a cyclic olefin-based resin, and more specifically, a norbornene-based resin. The resin composition for forming the core layer may contain an antioxidant, a photoacid generator, and the like.

[0072] A film having a layer made of a resin composition for forming a core layer can be obtained by applying a varnish-like resin composition onto a base film (e.g., a polyethylene terephthalate (PET) film, etc.) and drying it.

[0073] In step (D), for example, a known laminator may be used to laminate a film including a layer of a resin composition for forming a core layer on a layer of a resin composition for forming a first clad layer. A vacuum laminator may be used as the laminator to perform lamination in a vacuum atmosphere. In the step (D), the conditions such as the heating temperature, lamination time, and lamination pressure can be arbitrarily set.

[0074] [Step (E) of laminating a film having a layer made of a resin composition for forming a second clad layer] The method for producing the laminate of this embodiment preferably further comprises, after step (D), a step (E) of laminating a film comprising a layer made of a resin composition for forming a second clad layer onto the layer made of a resin composition for forming the core layer.

[0075] Step (E) is carried out after step (D). An optional step may be further included between step (D) and step (E).

[0076] When the method for producing a laminate of the present embodiment further includes step (C), step (E) is preferably carried out prior to step (C).

[0077] The resin composition for forming the second cladding layer is not particularly limited, as long as it is a resin composition capable of forming the second cladding layer of an optical waveguide. The resin composition for forming the second cladding layer may have a similar composition to that of the resin composition for forming the first cladding layer, for example. The resin composition for forming the second cladding layer may be different from the resin composition for forming the first cladding layer.

[0078] A film having a layer made of a resin composition for forming a second clad layer can be obtained by applying a varnish-like resin composition onto a base film (e.g., a polyimide (PI) film, etc.) and drying it.

[0079] In the step (E), for example, a known laminator may be used to laminate a film including a layer of a resin composition for forming a second clad layer on a layer of a resin composition for forming a core layer. A vacuum laminator may be used as the laminator to perform lamination in a vacuum atmosphere. In the step (E), the conditions such as the heating temperature, lamination time, and lamination pressure can be arbitrarily set.

[0080] [Other processes] The method for producing a laminate according to the present embodiment may include steps other than the steps described above.

[0081] When the method for producing a laminate of this embodiment includes steps (A) to (E), it is preferable to carry out each step in the following order: step (A) of preparing a work, step (B) of attaching an adhesive member, step (D) of laminating a film having a layer made of a resin composition for forming a core layer, step (E) of laminating a film having a layer made of a resin composition for forming a second clad layer, and step (C) of removing the adhesive member. Any step may be further included between each step.

[0082] [Laminate] The laminate obtained by the method for producing a laminate of this embodiment includes a substrate and a first cladding layer of an optical waveguide.

[0083] The laminate of this embodiment may further comprise other layers, and may be a laminate comprising an adhesive member, a substrate, and a first clad layer in this order; a laminate comprising an adhesive member, a substrate, a first clad layer, and a base film in this order; etc.

[0084] The laminate of this embodiment is preferably an optoelectronic composite substrate further comprising a core layer and a second clad layer in this order on the first clad layer, i.e., the optoelectronic composite substrate comprises a substrate, a first clad layer, a core layer, and a second clad layer in this order. The optoelectronic composite substrate of this embodiment may further include a polyimide substrate on the surface of the second clad layer opposite to the core layer side. The polyimide substrate is, for example, a polyimide substrate in a film including a layer made of a resin composition for forming the second clad layer in step (E) (i.e., a film including a layer made of a resin composition for forming the second clad layer and a polyimide substrate).

[0085] The optoelectronic composite substrate of this embodiment can be obtained, for example, by carrying out steps (A) to (E). The preferred order of carrying out each step is as described above. The method for producing the optical / electrical composite substrate may appropriately include a step of forming a waveguide pattern in the core layer, a step of forming a mirror on the optical waveguide, and the like.

[0086] Here, in the laminate of this embodiment, the first clad layer is a concept that includes a layer made of a resin composition for forming the first clad layer, the core layer is a concept that includes a layer made of a resin composition for forming the core layer, and the second clad layer is a concept that includes a layer made of a resin composition for forming the second clad layer.

[0087] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can also be adopted. Furthermore, the present invention is not limited to the above-described embodiment, and modifications and improvements within the scope of the present invention that can achieve the object of the present invention are included in the present invention. EXAMPLES

[0088] The present embodiment will be described in detail below based on examples and comparative examples. Note that the present embodiment is not limited to the descriptions of these examples.

[0089] [Raw materials] First, the raw materials constituting the resin composition for forming the first cladding layer will be described.

[0090] <Synthesis of polyimide resin (A-1)> 67.3g (0.210 mol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 97.7g (0.220 mol) of 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and 495g of dimethylacetamide were charged into a 3L separable glass flask equipped with a stirrer and agitator blade, and dissolved by stirring. The mixture was further stirred at room temperature for 12 hours under a nitrogen stream to carry out a polymerization reaction, yielding a polyamic acid solution.

[0091] After adding 16 g of pyridine to the obtained polyamic acid solution, 82 g of acetic anhydride was added dropwise at room temperature. The liquid temperature was then kept at 20 to 100° C. and the mixture was stirred for 24 hours to carry out an imidization reaction, thereby obtaining a polyimide solution.

[0092] The obtained polyimide solution was stirred in a 5L container and poured into 1,000g of methanol to precipitate the polyimide resin. The solid polyimide resin was then filtered using a suction filter and washed with 1,000g of methanol. The solid polyimide resin was then dried at 100°C for 24 hours using a vacuum dryer and then dried at 200°C for 3 hours to obtain a powdered polyimide resin (A-1). The weight average molecular weight (Mw) of the polyimide resin (A-1) measured by GPC was 51,000. 1 H-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 solid content of 25%, and then coated with an applicator to a film thickness of 30 μm, and then dried in an oven at 100° C. for 10 minutes to obtain a polyimide coating film. The refractive index of the obtained coating film was measured under conditions of 23° C. and 589 nm using an Abbe refractometer (manufactured by Atago Co., Ltd., product name: NAR-1T SOLID), and the refractive index of polyimide resin (A-1) was 1.54.

[0093] <Polyimide resin (A)> (A-1) Polyimide resin synthesized above (Mw = 51,000, imidization rate 99% or more, refractive index n = 1.54)

[0094] [ka]

[0095] <Compound (B) Having a Cyclic Ether Structure> (B-1) Celloxide 2021P (manufactured by Daicel Corporation, epoxy compound having an alicyclic structure, liquid at 23°C, refractive index 1.51)

[0096] [ka]

[0097] <Photopolymerization initiator (C)> (C-1) CPI-310B (San-Apro Co., Ltd., photocationic polymerization initiator, triarylsulfonium salt)

[0098] <Surfactant (D)> (D-1) BYK-333 (BYK Japan Co., Ltd., silicone surfactant)

[0099] <Organic solvent (E)> (E-1) Propylene glycol monomethyl ether acetate (E-2) Propylene glycol monomethyl ether

[0100] <Preparation of resin composition for forming first clad layer> 50 parts by mass of polyimide resin (A-1), 50 parts by mass of compound (B-1) having a cyclic ether structure, 0.10 parts by mass of photopolymerization initiator (C-1), 0.10 parts by mass of surfactant (D-1), 80 parts by mass of organic solvent (E-1), and 40 parts by mass of organic solvent (E-2) were stirred at room temperature until each raw material was completely dissolved to obtain a solution. Then, the solution was filtered through a PTFE filter with a pore size of 0.2 μm to obtain a resin composition for forming a varnish-like first clad layer.

[0101] <Preparation of a film having a layer made of a resin composition for forming a first clad layer> The resin composition for forming the first clad layer in a varnish form obtained by the above method was applied using an applicator to a 38 μm thick antistatic treated polyethylene terephthalate substrate (manufactured by Nippa Corporation, product name: PET38×1-TR1-ASQ, hereafter referred to as PET substrate) so that the thickness after drying would be 25 μm. The substrate was then dried at 100° 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 layer made of the resin composition to obtain a film having a layer made of the resin composition for forming the first clad layer (resin layer (a)).

[0102] <Substrate with through holes> Through holes with a diameter of 100 μm were formed in a printed circuit board with a thickness of 75 μm. The printed circuit board had a three-layer structure of copper foil / prepreg (glass cloth impregnated with epoxy resin) / copper foil = 12 μm / approximately 50 μm / 12 μm.

[0103] <Adhesive material> Adhesive member 1: SRL-050F (SFCL) (manufactured by Lintec Corporation, adhesive tape having a polyethylene terephthalate film (base layer) and a layer composed of an acrylic adhesive (adhesive resin layer), adhesive strength (SUS): 10 mN / 10 mm, adhesive strength (PET): 70 mN / 25 mm, thickness of base layer: 50 μm) Adhesive member 2: SRL-125F (SF) (manufactured by Lintec Corporation, adhesive tape having a polyethylene terephthalate film (base layer) and a layer composed of an acrylic adhesive (adhesive resin layer), adhesive strength (SUS): 10 mN / 10 mm, adhesive strength (PET): 80 mN / 25 mm, thickness of base layer: 125 μm) Adhesive member 3: SRL-0753 (AS) (manufactured by Lintec Corporation, adhesive tape having a polyethylene terephthalate film (base layer) and a layer composed of an acrylic adhesive (adhesive resin layer), adhesive strength (SUS): 50 mN / 10 mm, adhesive strength (PET): 200 mN / 25 mm, thickness of base layer: 75 μm) Adhesive member 4: Rioelm LE905-T (manufactured by Toyochem Co., Ltd., an adhesive tape having a polyethylene terephthalate film (base layer) and a layer composed of an acrylic adhesive (adhesive resin layer), adhesive strength (PET): 235 mN / 25 mm, thickness of base layer: 125 μm) Adhesive member 5: SRL-1254 (manufactured by Lintec Corporation, adhesive tape having a polyethylene terephthalate film (base layer) and a layer composed of an acrylic adhesive (adhesive resin layer), adhesive strength (SUS): 180 mN / 10 mm, adhesive strength (PET): 460 mN / 25 mm, thickness of base layer: 125 μm)

[0104] The adhesive strength (SUS) of the adhesive members 1 to 3 and 5 is the value of the adhesive strength of the adhesive member to a stainless steel test plate, measured in accordance with JIS Z 0237 (2009).

[0105] The adhesive strength (PET) of the adhesive members 1 to 3 and 5 means a value obtained by the following measurement method. The adhesive member was attached to a polyethylene terephthalate (PET) test plate, pressed back and forth once with a 2 kg rubber roller, and after leaving it for 24 hours, the adhesive member was peeled off in a 180 degree direction at a pulling speed of 300 mm / min. The test environment was 23°C and 50% RH.

[0106] The adhesive strength (PET) of the adhesive member 4 was measured in the same manner as the adhesive strength (PET) of the adhesive members 1 to 3 and 5, except that the standing time was set to 20 minutes. In the measurement method of adhesive strength (PET), the adhesive strength (PET) tends to become larger as the leaving time is extended. Therefore, the adhesive strength (PET) of the adhesive member 4 is expected to be 240 mN / 25 mm or more when measured after leaving for 24 hours.

[0107] [Examples 1 to 3 and 5 to 6] <Work preparation process (A)> The OPP cover film was peeled off from the film having the resin layer (a) obtained by the above method, and the substrate having the through-hole and the film having the resin layer (a) were laminated together, respectively, so that the substrate having the through-hole and the resin layer (a) were in contact with each other. Next, using a vacuum laminator (manufactured by Nikko Materials Co., Ltd., product name: CVP-600), the substrate and the film having the resin layer (a) were laminated together under the conditions of temperature: 140°C, pressure: 0.5 MPa, and time: 30 seconds, to obtain a laminate having a layer structure of "substrate / resin layer (a) / PET substrate". In addition, by laminating, the resin composition for forming the first clad layer was filled into the through-hole formed in the substrate. The PET substrate in the laminate is a PET substrate derived from the film having the resin layer (a).

[0108] The laminates obtained after lamination were exposed to light using a direct imaging exposure machine (manufactured by SCREEN Co., Ltd., product name: LI-9000). Next, the laminates were heated in an oven at 160°C for 30 minutes to obtain workpieces. That is, the workpieces of Examples 1 to 3 and 5 to 6 have a layer structure of "substrate / resin layer (a) / PET base material", and the resin composition for forming the first clad layer constituting the resin layer (a) is cured.

[0109] <Step (B) of attaching adhesive member> Using a vacuum laminator (manufactured by Nikko Materials Co., Ltd., product name: CVP-300), the adhesive member was attached to the workpiece under the conditions of temperature: 60°C, pressure: 0.6 MPa, and time: 30 seconds so that the substrate in the workpiece and the adhesive resin layer in the adhesive member were in contact with each other, thereby obtaining laminates of Examples 1 to 3 and 5 to 6, respectively. The adhesive members used were the adhesive members shown in Table 1. The laminates of Examples 1 to 3 and 5 to 6 have a layer structure of "substrate layer / adhesive resin layer / substrate / resin layer (a) / PET substrate". The size of the laminates of Examples 1 to 3 and 5 to 6 is 160 mm x 205 mm.

[0110] [Example 4] <Work preparation process (A)> The workpiece of Example 4 is the substrate having the above-mentioned through hole.

[0111] <Step (B) of attaching adhesive member> Using a vacuum laminator (manufactured by Nikko Materials Co., Ltd., product name: CVP-300), the adhesive member 1 was attached to the workpiece under the conditions of temperature: 60°C, pressure: 0.6 MPa, and time: 30 seconds, so that one side of the substrate having a through hole was in contact with the adhesive resin layer in the adhesive member. In other words, a laminate having a layer structure of "base layer / adhesive resin layer / substrate" was obtained.

[0112] The OPP cover film was peeled off from the film having the resin layer (a), and the laminate and the resin layer (a) were superimposed so that the substrate side of the obtained laminate was in contact with the resin layer (a). Next, the substrate and the film having the resin layer (a) were laminated in the same manner as in Examples 1 to 3 and 5 to 6 to obtain a laminate having a layer structure of "substrate layer / adhesive resin layer / substrate / resin layer (a) / PET substrate". In addition, by laminating, the resin composition for forming the first clad layer was filled into the through holes formed in the substrate.

[0113] The laminated laminate was exposed to light and heated in the same manner as in Examples 1 to 3 and 5 to 6 to cure the resin composition for forming the first clad layer constituting the resin layer (a), thereby obtaining the laminate of Example 4. The size of the laminate of Example 4 was 160 mm × 205 mm.

[0114] [Comparative Example 1] A laminate of Comparative Example 1 was obtained in the same manner as in Examples 1 to 3 and 5 to 6, except that step (B) was not performed. That is, the laminate of Comparative Example 1 has a layer structure of "substrate / resin layer (a) / PET base material", and the resin composition for forming the first clad layer constituting the resin layer (a) is cured. The size of the laminate of Comparative Example 1 is 160 mm x 205 mm.

[0115] [evaluation] <Evaluation of the amount of warpage> The laminates (size: 160 mm×205 mm) obtained in Examples 1 to 6 and Comparative Example 1 were used as samples for evaluating the amount of warpage. The sample for evaluating the amount of warping was placed on a horizontal stand with the PET substrate side of the laminate facing up, and the vertical distance between the apex of the sample for evaluating the amount of warping and the stand was measured. The vertical distance between the stand and each of the four apexes of the sample for evaluating the amount of warping was measured, and the average value was taken as the amount of warping. Here, since the sample for evaluating the amount of warping is rectangular, the four apexes of the sample for evaluating the amount of warping refer to the four corners of the rectangle.

[0116] <Evaluation of peelability> The laminates obtained in Examples 1 to 6 were each heated in an oven at 160° C. for 60 minutes. Then, the adhesive members were manually peeled off from the laminates. The peelability was evaluated according to the following criteria. A: The adhesive member can be easily peeled off. B: Although some force is required, it is possible to peel off the adhesive member. C: The adhesive member can be peeled off, but a considerable force is required to peel it off, or the adhesive member cannot be peeled off.

[0117] The evaluation of the peelability can be said to have been carried out by further carrying out the step (C) of removing the adhesive member from the substrate in the methods for producing the laminates of Examples 1 to 6.

[0118] <Appearance evaluation> The laminates of Examples 1 to 6 and Comparative Example 1 for which the peelability had been evaluated were each visually observed, and the appearance was evaluated according to the following criteria. A: No appearance defects as described in criteria B and C are found. B: There are appearance defects such as adhesive resin from the adhesive member remaining on the substrate, and the resin composition for forming the first clad layer filled in the through hole of the substrate having uneven appearance. C: There is an appearance defect worse than that of criterion B, such as a large amount of adhesive resin from the adhesive member remaining on the substrate.

[0119] The results of each evaluation are shown in Table 1.

[0120] [Table 1]

[0121] It can be seen from Table 1 that the laminates obtained by the manufacturing methods of the Examples all have a smaller amount of warpage than the laminates obtained by the manufacturing methods of the Comparative Examples. In other words, the manufacturing method of the laminate of this embodiment can suppress the amount of warpage of the obtained laminate.

[0122] This application claims priority based on Japanese Patent Application No. 2023-129065, filed on August 8, 2023, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0123] 20 First cladding layer 30 Core Layer 40 Second Cladding Layer 50 Light emitting element side mirror 60 Mirror on the light receiving element side 100 optical waveguide 110 Substrate 120 Light emitting element 130 Photodetector 140, 140a, 140b through hole 200 Photoelectric composite board 310 Layer made of a resin composition for forming a first clad layer (resin layer (a)) 350 Work 410 Adhesive resin layer 420 Base material layer 450 Adhesive material

Claims

1. A method for manufacturing a laminate including a substrate and a first cladding layer of an optical waveguide, comprising: a step (A) of preparing a workpiece including at least the substrate; a step (B) of attaching an adhesive member to one surface of the substrate in the workpiece; wherein the workpiece has a structure in which the substrate and a layer made of a resin composition for forming the first cladding layer are laminated; and further comprising a step (D) of laminating a film including a layer made of a resin composition for forming a core layer on a layer made of a resin composition for forming the first cladding layer after the step (B).

2. The method for manufacturing a laminate according to claim 1, wherein the adhesive member includes a base material layer and an adhesive resin layer.

3. The method for manufacturing a laminate according to claim 2, wherein the thickness of the base material layer is 10 μm or more and 1000 μm or less.

4. The base material layer is a resin film, and the resin constituting the resin film includes at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

5. The adhesive constituting the adhesive resin layer includes at least one selected from the group consisting of (meth)acrylic adhesives, silicone adhesives, urethane adhesives, and rubber adhesives.

6. The method for manufacturing a laminate according to claim 1 or 2, wherein the adhesive force of the adhesive member to a polyethylene terephthalate test plate measured by the following method is 1 mN / 25 mm or more and 230 mN / 25 mm or less. [Method] Attach the adhesive member to a polyethylene terephthalate test plate, press it back and forth once with a 2 kg rubber roller, leave it for 24 hours, and then peel off the adhesive member in a 180-degree direction at a tensile speed of 300 mm / min. The test environment is 23°C and 50% RH.

7. The method for manufacturing a laminate according to claim 1 or 2, further comprising a step (C) of removing the adhesive member from the substrate.

8. The method for manufacturing a laminate according to claim 1 or 2, wherein the substrate is a substrate for mounting an optical waveguide.

9. The method for manufacturing a laminate according to claim 1 or 2, wherein the substrate has a through hole.

10. The method for manufacturing a laminate according to claim 9, wherein when the volume of the through-hole is 100% by volume, the resin composition for forming the first clad layer is filled in 70% by volume or more of the through-hole.

11. The method for manufacturing a laminate according to claim 1 or 2, wherein in the workpiece, the resin composition for forming the first clad layer is a semi-cured body or a cured body.

12. The method for manufacturing a laminate according to claim 1 or 2, further comprising a step (E) of laminating a film including a layer made of a resin composition for forming a second clad layer on a layer made of a resin composition for forming a core layer after the step (D).

13. The method for manufacturing a laminate according to claim 1 or 2, wherein the laminate is an optoelectronic composite substrate further comprising a core layer and a second clad layer in this order on the first clad layer.

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