Method for manufacturing laminate

Abstract

A method for manufacturing a laminate comprising a substrate (110) having a through-hole (140) and a first cladding layer of an optical waveguide, the method comprising: a step (A) for preparing a workpiece (410) in which the substrate (110) and a layer (310) made of a resin composition for forming the first cladding layer are laminated; and a step (B) for exposing both surfaces of the workpiece (410).

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 have an optical waveguide provided on a substrate. Techniques relating to the optical / electrical composite substrate include those described in Patent Documents 1 and 2, for example.

[0004] Patent Document 1 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 1 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.

[0005] Patent Document 1 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 1). Patent Document 1 also describes a flexible double-sided circuit board E having a metal reinforcing layer M formed thereon (see paragraph 0028 of Patent Document 1). The flexible double-sided circuit board E includes the substrate. Patent Document 1 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 that covers 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 1). Figures 4 to 6 of Patent Document 1 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.

[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. It is described that the optoelectronic wiring board in Patent Document 2 can suitably process large amounts of information and high-speed information processing 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 make up 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).

[0009] JP 2014-238455 A JP 2006-140233 A

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

[0011] An example of an optical / electrical composite substrate is one that has a laminate including a substrate having a through hole and a first clad layer of an optical waveguide, and the through hole formed in the substrate is filled with a resin composition for forming the first clad layer. According to studies by the present inventors, it has been found that in such an optical / electrical composite substrate, depressions may occur above and / or below the resin composition filled in the through hole.

[0012] The present invention has been made in consideration of the above circumstances, and provides a method for manufacturing a laminate that can suppress the amount of recession.

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

[0014] [1] A method for manufacturing a laminate including a substrate having a through hole and a first clad layer of an optical waveguide, the method comprising: a step (A) of preparing a workpiece in which the substrate and a layer made of a resin composition for forming the first clad layer are laminated; and a step (B) of exposing both surfaces of the workpiece to light. [2] In the step (B), an integrated light amount when exposing at least one surface of the workpiece is 50 mJ / cm. ２ More than 1500mJ / cm ２[3] The method for manufacturing a laminate according to [1] above, wherein the step (B) comprises: a step (B-1) of exposing one surface of the workpiece to light; and a step (B-2) of exposing the surface of the workpiece opposite to the one surface after the step (B-1). [4] The method for manufacturing a laminate according to any of [1] to [3] above, further comprising a step (C) of heating the workpiece after the step (B). [5] The method for manufacturing a laminate according to [4] above, wherein the temperature at which the workpiece is heated in the step (C) is 80°C or higher and 200°C or lower. [6] The method for manufacturing a laminate according to any of [1] to [5] above, wherein the substrate is positioned as the outermost layer of the workpiece. [7] The method for manufacturing a laminate according to any of [1] to [6] above, wherein the workpiece further comprises a base film, and wherein the substrate, a layer made of a resin composition for forming the first cladding layer, and the base film are laminated in this order. [8] The method for producing a laminate according to [7] above, wherein the base film is a resin film, and the resin constituting the resin film contains at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. [9] The method for producing a laminate according to [7] or [8] above, further comprising step (D) of removing the base film from the workpiece after step (B).

[10] The method for producing a laminate according to any of [1] to [9] above, wherein the resin composition for forming the first clad layer contains a compound having a cyclic ether structure.

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

[10] above, wherein the resin composition for forming the first clad layer contains a photopolymerization initiator.

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

[11] above, wherein the substrate is a substrate for mounting an optical waveguide.

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

[12] , wherein T / R is 0.10 or more, where T is the thickness of the substrate [μm] and R is the diameter of the through-hole [μm].

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

[13] , wherein the diameter of the through-hole is 10 μm or more and 1000 μm or less.

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

[14] , wherein the thickness of the substrate is 10 μm or more and 1000 μm or less.

[16] The method for manufacturing a laminate according to any one of [1] to

[15] , 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.

[17] The method for manufacturing a laminate according to any one of [1] to

[16] , 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.

[0015] According to the present invention, a method for manufacturing a laminate that can suppress the amount of recession can be provided.

[0016] It is a cross-sectional view showing an example of the structure of the photoelectric composite substrate of this embodiment. It is a diagram for explaining the amount of recess. It is a cross-sectional view showing an example of the structure of a work. It is a cross-sectional view showing an example of the structure of a work further including a base film.

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are simplified and do not correspond to the actual dimensional ratios. Furthermore, unless otherwise specified, the numerical range "A to B" indicates A or more and B or less.

[0018] FIG. 1 is a cross-sectional view schematically illustrating an example of the structure of an optical / electrical composite substrate according to this embodiment. As shown in FIG. 1 , an optical / electrical 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 optical waveguide 100 includes a mirror 50 on the light-emitting element side and a mirror 60 on the light-receiving element side. The substrate 110 has through-holes 140 (140a, 140b) (note that the through-hole 140 shown in FIG. 1 is filled with the first cladding layer 20). A light-emitting element 120 and a light-receiving element 130 are provided on the side of the substrate 110 opposite the optical waveguide 100 side.

[0019] The propagation path of light in the photoelectric composite substrate 200 will be specifically described using Figure 1. 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. After that, 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 Figure 1 are a schematic representation of the propagation of light.

[0020] According to the investigations of the present inventors, it has been found that in the conventional method of manufacturing the optical-electrical composite substrate 200, after filling the through hole 140 with a resin composition for forming the first cladding layer 20, a heating process or the like is performed, which may result in depressions on the upper and / or lower sides of the resin composition filled in the through hole 140.

[0021] FIG. 2 is a diagram for explaining the recess amount. In this specification, the upper recess amount refers to the depth of the recess when the surface of the first cladding layer 20 opposite the substrate 110 side is used as a reference. In other words, the upper recess amount refers to the depth indicated by 10a in FIG. 2. In this specification, the lower recess amount refers to the depth of the recess when the surface of the substrate 110 opposite the first cladding layer 20 side is used as a reference. In other words, the lower recess amount refers to the depth indicated by 10b in FIG. 2.

[0022] Furthermore, according to the study of the present inventors, it was found that, because the through-holes 140 in the optoelectronic composite substrate 200 are paths for light propagation, a large amount of recession may make the optoelectronic composite substrate more susceptible to optical loss. The present invention has been made in view of the above circumstances, and provides a method for manufacturing a laminate that can suppress the amount of recession.

[0023] The method for manufacturing a laminate according to the present embodiment is a method for manufacturing a laminate including a substrate having a through hole and a first clad layer of an optical waveguide, and includes the steps of: (A) preparing a workpiece including a substrate and a layer made of a resin composition for forming the first clad layer; and (B) exposing both surfaces of the workpiece to light. Hereinafter, in this specification, for the sake of simplicity, the "layer made of a resin composition for forming the first clad layer" may be referred to as "resin layer (a)."

[0024] Each step of the method for producing a laminate according to this embodiment will now be described in detail.

[0025] [Step (A) of Preparing a Workpiece] The method for manufacturing a laminate of this embodiment includes step (A) of preparing a workpiece in which a substrate and a layer made of a resin composition for forming a first clad layer are laminated.

[0026] Fig. 3 is a cross-sectional view showing a schematic example of the structure of a workpiece 410. In Fig. 3, a workpiece 410 is formed by laminating a substrate 110 and a layer (resin layer (a)) 310 made of a resin composition for forming a first clad layer. Here, the substrate 110 has a through-hole 140.

[0027] The substrate 110 is not particularly limited as long as it has a through-hole. Examples of the substrate 110 include a printed circuit board and a flexible substrate, and the substrate 110 is preferably a flexible substrate, and more preferably a flexible double-sided copper-clad laminate. The substrate 110 is preferably a substrate for mounting an optical waveguide.

[0028] The thickness of the substrate 110 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.

[0029] The substrate 110 has at least one through hole 140, and may have one through hole 140 or may have two or more through holes 140. Specifically, for example, as shown in Fig. 3, 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 serve as a light propagation path.

[0030] The diameter of the through-hole 140 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 is 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 110 has a plurality of through-holes 140, it is sufficient that the diameter of at least one of the through-holes 140 is within the above range.

[0031] When the thickness of substrate 110 is T [μm] and the hole diameter of through hole 140 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, but may be, for example, 2.00 or less, 1.50 or less, or 1.00 or less. Here, when substrate 110 has a plurality of through holes 140, it is sufficient that T / R of at least one of through holes 140 is within the above range.

[0032] 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, even 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.

[0033] A preferred embodiment of the resin composition for forming the first clad layer will be described later.

[0034] The workpiece of this embodiment may have a resin composition for forming a first cladding layer filled in the through hole 140. In the workpiece of this embodiment, the ratio of the resin composition for forming the first cladding layer filled in the through hole, when the volume of the through hole is taken as 100 volume %, is 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, from the viewpoint of further suppressing propagation loss of the optical waveguide.

[0035] 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 the resin layer (a) are superimposed on each other, and a vacuum laminator is used to laminate the substrate having the through-holes and the film having the resin layer (a), thereby filling the through-holes with the resin composition for forming the first clad layer.

[0036] The workpiece of this embodiment preferably further comprises a base film, and is formed by laminating a substrate, a layer (resin layer (a)) made of a resin composition for forming the first cladding layer, and the base film in this order; more preferably, the substrate, resin layer (a), and base film are laminated in this order so that they are in direct contact with each other. Also, in the workpiece of this embodiment, the substrate is preferably positioned as the outermost layer of the workpiece. Figure 4 is a cross-sectional view schematically showing an example of the structure of a workpiece further comprising a base film. In Figure 4, the workpiece 420 is formed by laminating a substrate 110, a resin layer (a) 310, and a base film 320 in this order so that they are in direct contact with each other.

[0037] By further providing a substrate film to the workpiece of this embodiment, the amount of denting can be further suppressed. The reason for this is unclear, but the inventors speculate as follows. First, the resin composition for forming the first clad layer of this embodiment may contain a low-molecular-weight compound (e.g., a compound having a cyclic ether structure, as described below). The low-molecular-weight compound contained in the resin composition may be prone to thermal decomposition. The inventors believe that one of the factors that increases the amount of denting is the thermal decomposition and volatilization of the low-molecular-weight compound contained in the resin composition. Therefore, they speculate that by further providing a substrate film on the resin layer (a) to the workpiece, it is possible to suppress the volatilization of the low-molecular-weight compound, thereby further suppressing the amount of denting.

[0038] For example, a resin film can be used as the base film 320. The resin constituting the base film 320 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.

[0039] From the viewpoint of further improving handleability, the thickness of the base film 320 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.

[0040] The base film 320 may be subjected to surface treatment such as antistatic treatment and release treatment.

[0041] The method for manufacturing a workpiece including a base film is not particularly limited, but examples thereof include the following method: First, a film in which a resin layer (a) and a base film are laminated is prepared. Next, a substrate having through holes and the film in which the resin layer (a) and the base film are laminated are superimposed, and the workpiece is obtained by laminating them using a vacuum laminator.

[0042] [Step (B) of Exposing Both Sides of Workpiece] The method for manufacturing a laminate of this embodiment includes step (B) of exposing both sides of the workpiece. Step (B) is performed after step (A). An optional step may be further included between step (A) and step (B).

[0043] The workpiece in this embodiment is a laminate in which a substrate and a resin layer (a) are stacked, and therefore exposing both sides of the workpiece means exposing one side of the laminate and the side opposite to the one side.

[0044] The two surfaces of the workpiece will be specifically described using the drawings. The two surfaces of the workpiece 410 shown in FIG. 3 are the surface 410A of the resin layer (a) 310 opposite the substrate 110 side, and the surface 410B of the substrate 110 opposite the resin layer (a) 310 side. The two surfaces of the workpiece 420 shown in FIG. 4 are the surface 420A of the base film 320 opposite the resin layer (a) 310 side, and the surface 420B of the substrate 110 opposite the resin layer (a) 310 side. Hereinafter, in this specification, the surface (410A, 420A) on the side where the resin layer (a) 310 of the workpiece is located may be referred to as surface A, and the surface (410B, 420B) on the side where the substrate 110 is located may be referred to as surface B.

[0045] When the manufacturing method of the laminate includes step (B), the amount of recess can be reduced. The reason for this is unclear, but the inventors speculate as follows. The inventors believe that one of the factors that increases the amount of recess is that the resin layer (a) softens and the resin composition flows when a heating step or the like is performed. It is believed that when the manufacturing method of the laminate includes step (B), the curing reaction on both sides of the resin layer (a) is further promoted. It is speculated that this hardens both sides of the resin layer (a), suppressing the flow of the resin composition and thereby reducing the amount of recess.

[0046] Furthermore, as described above, the present inventors believe that one of the factors that increases the amount of recession is the thermal decomposition and volatilization of the low-molecular-weight compound contained in the resin composition for forming the first cladding layer. Examples of such low-molecular-weight compounds include those that harden. Including step (B) in the laminate manufacturing method further accelerates the curing reaction of the resin composition. Therefore, they speculate that by curing the low-molecular-weight compound before it volatilizes, it is possible to suppress the volatilization of the low-molecular-weight compound, thereby suppressing the amount of recession.

[0047] In step (B), both sides of the workpiece may be exposed simultaneously or sequentially, but preferably both sides of the workpiece are exposed sequentially. That is, step (B) preferably includes step (B-1) of exposing one side of the workpiece, and step (B-2) of exposing the side opposite to the one side of the workpiece after step (B-1). Here, side A may be exposed in step (B-1) and then side B may be exposed in step (B-2), or side B may be exposed in step (B-1) and then side A may be exposed in step (B-2).

[0048] In step (B), the cumulative light amount when exposing the workpiece is not particularly limited, but a preferred range is as follows: The cumulative light amount when exposing at least one surface of the workpiece is preferably 50 mJ / cm from the viewpoint of further promoting the curing of the resin composition for forming the first clad layer. ２ More preferably, 100 mJ / cm２ More preferably, 150 mJ / cm ２ More preferably, 180 mJ / cm ２ or more, and preferably 1500 mJ / cm ２ or less, more preferably 1300 mJ / cm ２ More preferably, 1100 mJ / cm or less ２ or less. More preferably, the integrated light amount when exposing one side of the workpiece is within the above-mentioned numerical range, and the integrated light amount when exposing the side opposite to the one side is also within the above-mentioned numerical range. The integrated light amount when exposing one side of the workpiece and the integrated light amount when exposing the side opposite to the one side may be the same value or different values.

[0049] The wavelength of the light used to expose the workpiece is not particularly limited, but may be, for example, in the range of 300 nm to 450 nm, or 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.

[0050] In step (B), the device for exposing the workpiece is not particularly limited, and for example, a known exposure machine or the like may be used.

[0051] [Step (C) of Heating the Work] The method for producing a laminate according to the present embodiment preferably further includes step (C) of heating the work after step (B). Note that an optional step may be included between step (B) and step (C).

[0052] From the viewpoint of further suppressing the amount of recession, step (C) preferably includes step (C-1) of increasing the temperature of the workpiece and step (C-2) of heating the workpiece while maintaining the temperature at a constant level, and more preferably further includes step (C-3) of decreasing the temperature of the workpiece in addition to steps (C-1) and (C-2).

[0053] In step (C), the temperature to which the workpiece is heated is preferably 80°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, even more preferably 110°C or higher, even more preferably 120°C or higher, even more preferably 130°C or higher, even more preferably 140°C or higher, even more preferably 150°C or higher, and is preferably 200°C or lower, more preferably 190°C or lower, even more preferably 180°C or lower, even more preferably 170°C or lower, from the viewpoint of further promoting the curing of the resin composition for forming the first cladding layer. Here, when the temperature to which the workpiece is heated in step (C) is not constant, the above-mentioned temperature to which the workpiece is heated refers to the temperature at which the workpiece is heated while being maintained at a constant temperature. Specifically, when step (C) comprises step (C-1) of increasing the temperature of the workpiece and step (C-2) of heating the workpiece while maintaining the temperature at a constant temperature, the temperature refers to the temperature to which the workpiece is heated in step (C-2).

[0054] In step (C), the time for heating the workpiece is preferably 10 minutes or more, more preferably 20 minutes or more, from the viewpoint of further accelerating the curing of the resin composition for forming the first cladding layer, and is preferably 120 minutes or less, more preferably 90 minutes or less, even more preferably 60 minutes or less, and even more preferably 40 minutes or less, from the viewpoint of further improving production efficiency. Here, when the temperature to which the workpiece is heated in step (C) is not constant, the above-mentioned time for heating the workpiece refers to the time for heating the workpiece while maintaining it at a constant temperature. Specifically, when step (C) includes step (C-1) of increasing the temperature of the workpiece and step (C-2) of heating the workpiece while maintaining it at a constant temperature, the time for heating the workpiece refers to the time for heating the workpiece in step (C-2).

[0055] When step (C) includes step (C-1) of increasing the temperature of the workpiece, the temperature increase rate in step (C-1) is preferably 1°C / min or more, more preferably 2°C / min or more, from the viewpoint of further improving production efficiency, and is preferably 10°C / min or less, more preferably 8°C / min or less, even more preferably 5°C / min or less, and even more preferably 4°C / min or less, from the viewpoint of further suppressing the amount of recession.

[0056] In step (C), the method for heating the workpiece is not particularly limited, but preferred examples include a method for heating the workpiece using an oven and a method for heating the workpiece while pressing it using a press. In the method for heating the workpiece while pressing it using a press, the workpiece may be pressed under normal pressure, or may be pressed under a vacuum (reduced pressure) atmosphere using a vacuum press.

[0057] [Step (D) of Removing the Base Film from the Workpiece] The method for producing a laminate of this embodiment preferably further includes step (D) of removing the base film from the workpiece after step (B). An optional step may be included between step (B) and step (D), and step (C) is preferably included. That is, the method for producing a laminate of this embodiment preferably performs the steps in the order of step (B), step (C), and step (D).

[0058] In step (D), the method for removing the base film from the workpiece is not particularly limited, and examples thereof include a method in which the base film is peeled off manually, a method in which the base film is peeled off using a film peeling device, and the like.

[0059] [Other Steps] The method for producing a laminate according to the present embodiment may include steps other than the steps described above. Examples of other steps include a step of further laminating another layer.

[0060] [Laminate] The laminate obtained by the laminate manufacturing method of this embodiment includes a substrate having a through hole and a first clad layer of an optical waveguide. The laminate of this embodiment may further include other layers, for example, a laminate including a substrate, a first clad layer, and a base film in this order. Here, in the laminate of this embodiment, the first clad layer conceptually includes a layer made of a resin composition for forming the first clad layer.

[0061] The laminate of this embodiment is preferably an optoelectronic composite substrate further comprising a core layer and a second clad layer on the first clad layer, in this order. That is, 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 comprise a polyimide substrate on the surface of the second clad layer opposite to the core layer side.

[0062] The optoelectronic composite substrate of this embodiment can be produced, for example, as follows. First, steps (A) and (B) of this embodiment are performed to obtain a laminate including a substrate and a first clad layer. When obtaining the laminate, steps (C) and (D) may be further included. Then, a film for forming a core layer is laminated onto the laminate to form a core layer, and then a film for forming a second clad layer is laminated to form the second clad layer. The method for producing an optoelectronic 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, etc.

[0063] [Resin Composition for Forming First Clad Layer] A preferred embodiment of the resin composition for forming the first clad layer of this embodiment will be specifically described.

[0064] The resin contained in the resin composition for forming the first cladding layer is not particularly limited as long as it is a resin that can be used to form a cladding layer of an optical waveguide, but 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.

[0065] The resin composition for forming the first clad layer preferably contains a polyimide resin.

[0066] The polyimide resin preferably contains an imide ring structure in the molecule. The polyimide resin preferably contains a fluorinated polyimide. The fluorinated polyimide means a polyimide containing a fluorine atom.

[0067] The polyimide resin in the resin composition for forming the first clad layer may be one type of polyimide resin, or may contain two or more types of polyimide resins.

[0068] The resin composition for forming the first clad layer preferably contains a compound having a cyclic ether structure.

[0069] The compound having a cyclic ether structure preferably contains at least one or more compounds selected from the group consisting of epoxy compounds and oxetane compounds, and more preferably contains one or more epoxy compounds.

[0070] The compound having a cyclic ether structure 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 in 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.

[0071] The compound having a cyclic ether structure preferably contains two or more cyclic ether structures in the molecule, and more preferably contains two or three cyclic ether structures in the molecule.

[0072] The compound having a cyclic ether structure is preferably a low molecular weight compound, and the molecular weight of the compound having a cyclic ether structure is preferably 50 or more and 1,000 or less, more preferably 100 or more and 500 or less.

[0073] The compound having a cyclic ether structure in the resin composition for forming the first clad layer may be a compound having one type of cyclic ether structure, or may contain two or more types of compounds having cyclic ether structures.

[0074] 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 from the viewpoint of further accelerating the curing of the resin composition for forming the first clad layer, the resin composition preferably contains a photopolymerization initiator.

[0075] The photopolymerization initiator is not particularly limited, and may be a cationic photopolymerization initiator, a radical photopolymerization initiator, or the like, and preferably includes a cationic photopolymerization initiator. The cationic photopolymerization initiator includes, for example, a sulfonium salt-type polymerization initiator or 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.

[0076] The polymerization initiator in the resin composition for forming the first clad layer may be a single polymerization initiator, or may contain two or more polymerization initiators.

[0077] The resin composition for forming the first clad layer may contain components such as a surfactant as appropriate.

[0078] The resin composition for forming the first clad 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.

[0079] The content of the polyimide resin contained in the resin composition for forming the first clad layer 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, when the total content of the resin components in the resin composition for forming the first clad layer is 100 parts by mass.

[0080] The content of the compound having a cyclic ether structure contained in the resin composition for forming the first clad layer 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.

[0081] 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.

[0082] The content of the polymerization initiator contained in the resin composition for forming the first cladding layer is preferably 0.01 part by mass or more, more preferably 0.03 part by mass or more, even more preferably 0.05 part by mass or more, and even more preferably 0.07 part by mass or more, 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 accelerating curing of the resin composition for forming the first cladding layer, 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.

[0083] The resin composition for forming the first clad layer can be obtained, for example, by mixing the respective components.

[0084] The layer made of the resin composition for forming the first clad layer can be obtained, for example, by applying a varnish-like resin composition for forming the first clad layer to a substrate film and drying it.

[0085] 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.

[0086] 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.

[0087] [Raw Materials] First, raw materials constituting the resin composition for forming the first clad layer will be described.

[0088] <Synthesis of Polyimide Resin (A-1)> 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 were placed in a 3 L separable glass flask equipped with a stirrer and a stirring blade, and the mixture was stirred to dissolve. Further, the mixture was stirred at room temperature for 12 hours under a nitrogen stream to carry out a polymerization reaction, yielding a polyamic acid solution.

[0089] 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.

[0090] 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 film. The refractive index of the resulting coating film 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 polyimide resin (A-1) was found to be 1.54.

[0091] <Polyimide Resin (A)> (A-1) Polyimide resin synthesized above (Mw = 51,000, imidization rate 99% or more, refractive index n = 1.54)

[0092]

[0093] <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)

[0094]

[0095] <Photopolymerization initiator (C)> (C-1) CPI-310B (manufactured by San-Apro Co., Ltd., photocationic polymerization initiator, triarylsulfonium salt)

[0096] <Surfactant (D)> (D-1) BYK-333 (manufactured by BYK Japan K.K., silicone surfactant)

[0097] <Organic Solvent (E)> (E-1) Propylene glycol monomethyl ether acetate (E-2) Propylene glycol monomethyl ether

[0098] <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. The solution was then filtered through a PTFE filter having a pore size of 0.2 μm to obtain a varnish-like resin composition for forming the first clad layer.

[0099] <Preparation of Film Having Layer Made of Resin Composition for Forming First Clad Layer> The varnish-like resin composition for forming the first clad layer obtained by the above method was applied to a 38 μm thick antistatically treated polyethylene terephthalate substrate (manufactured by Nippa Corporation, product name: PET38×1-TR1-ASQ, hereinafter referred to as PET substrate) using an applicator so that the dry thickness would be 25 μm. The varnish was then dried at 100° C. for 10 minutes, and finally an OPP cover film (manufactured by Oji F-Tex Co., Ltd., 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)).

[0100] <Substrate with Through Holes> Through holes with a diameter of 100 μm were formed in a double-sided copper-clad laminate (CCL) having a thickness of 50 μm.

[0101] [Examples 1 and 2] <Step (A) of Preparing a Workpiece> The OPP cover film was peeled off from the film provided with the resin layer (a) obtained by the above method, and the substrate and the film provided with the resin layer (a) were superimposed on each other so that the substrate having a 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 provided with the resin layer (a) were laminated under the conditions of temperature: 140°C, pressure: 0.5 MPa, and time: 30 seconds. The laminate obtained after lamination was used as a workpiece. The layer structure of the workpiece was "substrate / resin layer (a) / PET substrate." Furthermore, by laminating, the resin composition for forming the first clad layer was filled into the through holes formed in the substrate. Note that the PET substrate in the workpiece was a PET substrate derived from the film provided with the resin layer (a).

[0102] <Step (B) of exposing both surfaces of workpiece> <Step (B-1) of exposing one surface of workpiece> First, the surface of the workpiece facing the PET substrate (side A) was exposed using a direct imaging exposure machine (manufactured by SCREEN Corporation, product name: LI-9000) under the conditions of the integrated light intensity shown in Table 1. <Step (B-2) of exposing the surface opposite to one surface of the workpiece> Next, the surface of the workpiece facing the substrate (side B) was exposed using a direct imaging exposure machine (manufactured by SCREEN Corporation, product name: LI-9000) under the conditions of the integrated light intensity shown in Table 1.

[0103] <Step (C) of Heating Workpieces> After step (B), the workpieces were each heated in an oven under the conditions shown in Table 1.

[0104] <Step (D) of Removing the Base Film from the Work> After step (C), the PET base film was peeled off from the work, and the laminates of Examples 1 and 2 were obtained.

[0105] [Example 3] A laminate of Example 3 was obtained in the same manner as in Examples 1 and 2, except that step (C) of heating the workpiece in Examples 1 and 2 was replaced with step (C) performed in the following manner.

[0106] <Step (C) of Heating the Workpiece> After step (B), the workpiece was heated under the conditions shown in Table 1 using a press (Kitagawa Seiki Co., Ltd., product name: KVHC). Specifically, the workpiece was heated from room temperature (approximately 25°C) to the heating temperature shown in Table 1 at the heating rate shown in Table 1 (heating step: step (C-1)), the workpiece was held at the heating temperature shown in Table 1 and heated for the heating time shown in Table 1 (holding step: step (C-2)), and the workpiece was cooled from the heating temperature shown in Table 1 to room temperature at a temperature drop rate of 5°C / min (heating step: step (C-3)). In all steps of the heating step, holding step, and temperature drop step, the workpiece was continuously pressed at a pressure of 0.2 MPa. Furthermore, in step (C), the workpiece was pressed in a vacuum (reduced pressure) atmosphere.

[0107] [Comparative Examples 1 to 3] Laminates of Comparative Examples 1 to 3 were obtained in the same manner as in Examples 1 and 2, except that step (B-2) of exposing the surface opposite to one surface of the workpiece in Examples 1 and 2 was not performed. In Comparative Example 2, in step (C), the workpiece was heated in an oven from room temperature to the heating temperature shown in Table 1 at the heating rate shown in Table 1, and then the workpiece was maintained at the heating temperature shown in Table 1 and heated for the heating time shown in Table 1.

[0108] That is, Comparative Examples 1 to 3 are experimental examples in which only one side of the workpiece was exposed, and both sides of the workpiece were not exposed.

[0109] [Evaluation] <Evaluation of Dent Amount> For the laminates obtained in Examples 1 to 3 and Comparative Examples 1 to 3, the amount of dent on the upper side (corresponding to 10a in FIG. 2 ) and the amount of dent on the lower side (corresponding to 10b in FIG. 2 ) were measured using a confocal microscope (manufactured by Olympus Corporation, product name: LEXT OLS3100). The amount of dent was evaluated according to the following criteria: A: The amount of dent on the upper side was 3 μm or less, and the amount of dent on the lower side was 3 μm or less. B: At least one of the amount of dent on the upper side and the amount of dent on the lower side was greater than 3 μm. The evaluation results of the amount of dent are shown in Table 1.

[0110]

[0111] It can be seen from Table 1 that the evaluation results for the amount of recession were good for all of the laminates obtained by the manufacturing methods of the examples. That is, according to the manufacturing method of the laminate of the present embodiment, the amount of recession of the obtained laminate can be suppressed.

[0112] Furthermore, in Examples 1 to 3 and Comparative Examples 1 to 3, the PET substrate was peeled off from the laminate obtained after lamination, and the laminates of Examples 1' to 3' and Comparative Examples 1' to 3' were produced by the same method, except that step (D) was not performed. That is, these are experimental examples in which the layer structure of the work was "substrate / resin layer (a)". When the laminates of Examples 1' to 3' and Comparative Examples 1' to 3' were also evaluated for the amount of recession, evaluation results similar to those of Examples 1 to 3 and Comparative Examples 1 to 3 were obtained, respectively.

[0113] This application claims priority based on Japanese Patent Application No. 2023-118086, filed on July 20, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0114] 10a, 10b Recess amount 20 First cladding layer 30 Core layer 40 Second cladding layer 50 Mirror on the light-emitting element side 60 Mirror on the light-receiving element side 100 Optical waveguide 110 Substrate 120 Light-emitting element 130 Light-receiving element 140, 140a, 140b Through hole 200 Opto-electrical composite substrate 310 Layer made of resin composition for forming first cladding layer (resin layer (a)) 320 Base film 410, 420 Work

Claims

1. A method for manufacturing a laminate including a substrate having a through hole and a first clad layer of an optical waveguide, comprising the steps of: A step (A) of preparing a workpiece in which the substrate and a layer made of a resin composition for forming the first clad layer are laminated; and (B) a step of exposing both sides of the workpiece to light; A method for manufacturing a laminate, wherein the workpiece has the substrate positioned as the outermost layer of the workpiece.

2. In the step (B), the integrated light amount when exposing at least one surface of the workpiece is 50 mJ / cm ２ More than 1500mJ / cm ２ The method for producing a laminate according to claim 1 , wherein:

3. The step (B) includes a step (B-1) of exposing one surface of the workpiece to light; The method for producing a laminate according to claim 1 or 2, further comprising: a step (B-2) of exposing a surface of the workpiece opposite to the one surface after the step (B-1).

4. The method for producing a laminate according to claim 1 or 2, further comprising a step (C) of heating the workpiece after the step (B).

5. The method for producing a laminate according to claim 4, wherein in the step (C), the temperature to which the workpiece is heated is 80°C or higher and 200°C or lower.

6. The workpiece further includes a base film, 3. The method for producing a laminate according to claim 1, wherein the substrate, a layer made of a resin composition for forming the first clad layer, and the base film are laminated in this order.

7. The base film is a resin film, The method for producing a laminate according to claim 6 , wherein a resin constituting the resin film includes at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

8. The method for producing a laminate according to claim 6 , further comprising a step (D) of removing the base film from the workpiece after the step (B).

9. The method for producing a laminate according to claim 1 , wherein the resin composition for forming the first clad layer contains a compound having a cyclic ether structure.

10. The method for producing a laminate according to claim 1 or 2, wherein the resin composition for forming the first clad layer contains a photopolymerization initiator.

11. The method for producing a laminate according to claim 1 , wherein the substrate is a substrate for mounting an optical waveguide.

12. 3. The method for producing a laminate according to claim 1, wherein when the thickness of the substrate is T [μm] and the hole diameter of the through hole is R [μm], T / R is 0.10 or more.

13. The method for producing a laminate according to claim 1 or 2, wherein the through holes have a hole diameter of 10 μm or more and 1000 μm or less.

14. The method for producing a laminate according to claim 1 or 2, wherein the substrate has a thickness of 10 μm or more and 1000 μm or less.

15. 3. The method for manufacturing a laminate according to claim 1, 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.

16. 3. The method for producing a laminate according to claim 1, 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.