Manufacturing method of laminate

Abstract

To provide a manufacturing method of a laminate capable of suppressing a depression amount.SOLUTION: A manufacturing method is for a laminate including a substrate 110 having a through hole 140, and a first clad layer of an optical waveguide. The manufacturing method of a laminate includes: a step (A) of preparing a work-piece 410 having a substrate 110 and a layer 310 made of a resin composition for forming a first clad layer; a step (B) of exposing the work-piece 410; and a step (C) of heating and pressing the work-piece 410 after the step (B).SELECTED DRAWING: Figure 3

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

[0012] The present invention has been made in consideration of the above circumstances, and provides a method for producing a laminate that can suppress the amount of recession. [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 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; A step (B) of exposing the workpiece; The method for producing a laminate further comprises, after the step (B), a step (C) of heating and pressing the work. [2] The method for producing a laminate according to [1] above, wherein in the step (C), the temperature to which the workpiece is heated is 80°C or higher and 200°C or lower. [3] The method for producing a laminate according to [1] or [2] above, wherein in the step (C), the pressure for pressing the work is 0.1 MPa or more and 5.0 MPa or less. [4] The step (C) includes a step (C-1) of pressing the workpiece while heating it; A step (C-2) of pressing the workpiece while maintaining the workpiece at a constant temperature; The method for producing a laminate according to any one of the above [1] to [3], further comprising: a step (C-3) of pressing the workpiece while lowering its temperature. [5] In the step (B), the integrated light amount when exposing the workpiece is 50 mJ / cm 2 More than 1500mJ / cm 2 A method for producing a laminate according to any one of the above [1] to [4], which is as follows: [6] The workpiece further includes a base film, The method for producing a laminate according to any one of the above [1] to [5], 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 [6] 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. [8] The method for producing a laminate according to [6] or [7] above, further comprising a step (D) of removing the base film from the workpiece after the step (C). [9] The method for producing a laminate according to any one of the above [1] to [8], wherein a 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 any one of the above [1] to [9], wherein the resin composition for forming the first cladding layer contains a photopolymerization initiator.

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

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

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

[11] , wherein the through holes have a hole diameter of 10 μm or more and 1000 μm or less.

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

[12] , wherein the substrate has a thickness of 10 μm or more and 1000 μm or less.

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

[13] 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.

[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 recession 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. 13 is a diagram for explaining the amount of depression. [Diagram 3] FIG. 2 is a cross-sectional view showing a schematic example of a structure of a workpiece. [Figure 4] 1 is a cross-sectional view showing a schematic example of a structure of a workpiece further including a base film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment 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 ratio. In addition, 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 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] According to the inventors' investigations, it was found that in the conventional manufacturing method of 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, and then a dent may occur above and / or below the resin composition filled in the through hole 140.

[0021] FIG. 2 is a diagram for explaining the amount of recess. In this specification, the amount of recess on the upper side 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 amount of recess on the upper side refers to the depth shown as 10a in FIG. 2. In this specification, the amount of recess on the lower side 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 amount of recess on the lower side refers to the depth shown as 10b in FIG. 2.

[0022] Furthermore, according to the inventors' investigations, since the through-holes 140 in the optical / electrical composite substrate 200 are paths of light propagation, it has been found that if the amount of recess is large, optical loss in the optical / electrical composite substrate may be more likely to occur. The present invention has been made in consideration of the above circumstances, and provides a method for producing a laminate that can suppress the amount of recession.

[0023] The method for manufacturing a laminate of this embodiment is a method for manufacturing a laminate comprising a substrate having a through hole and a first cladding layer of an optical waveguide, and comprises the steps of: step (A) of preparing a workpiece comprising a substrate and a layer made of a resin composition for forming the first cladding layer; step (B) of exposing the workpiece; and, after step (B), step (C) of heating and pressing the workpiece. 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)".

[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 in which a substrate and a layer made of a resin composition for forming a first cladding layer are laminated together.

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

[0027] There are no particular limitations on the substrate 110 as long as it is a substrate having a through hole. Examples of the substrate 110 include a printed circuit board and a flexible substrate, and the like. A flexible substrate is preferable, and a flexible double-sided copper-clad laminate is more preferable.

[0028] The thickness of 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 . 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 be a light propagation path.

[0030] The hole 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 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 hole 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, and may be, for example, 2.00 or less, 1.50 or less, or 1.00 or less. Here, when the substrate 110 has a plurality of through holes 140, it is sufficient that the T / R of at least one of the through holes 140 falls 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, 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] 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.

[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 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.

[0036] The workpiece of this embodiment preferably further comprises a base film, and comprises a substrate, a layer (resin layer (a)) made of a resin composition for forming the first clad layer, and a base film laminated in this order, and more preferably, the substrate, resin layer (a), and base film are laminated in this order so as to be in direct contact with each other. Fig. 4 is a cross-sectional view showing a schematic example of the structure of a workpiece further including a base film. In Fig. 4, the workpiece 420 is formed by laminating the substrate 110, the resin layer (a) 310, and the base film 320 in this order so that they are in direct contact with each other.

[0037] By further providing the base film in the workpiece of this embodiment, the amount of dent can be further suppressed. Although the reason for this is not clear, the present inventors speculate as follows. First, the resin composition for forming the first clad layer of this embodiment may contain a low molecular weight compound (for example, a compound having a cyclic ether structure, which will be described later). The low molecular weight compound contained in the resin composition may be easily thermally decomposed. The present inventors believe that one of the factors that increases the amount of dents 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 base film on the resin layer (a) of the workpiece, it becomes possible to suppress the volatilization of the low molecular weight compound, and the amount of dents can be further suppressed.

[0038] The base film 320 may be, for example, a resin film. 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 a surface treatment such as an antistatic treatment or a release treatment.

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

[0042] [Process of exposing the workpiece (B)] The method for manufacturing a laminate in this embodiment includes a step (B) of exposing a workpiece to light. Step (B) is carried out after step (A). An optional step may be further included between step (A) and step (B).

[0043] In step (B), only one side of the workpiece may be exposed, or both sides of the workpiece may be exposed.

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

[0045] When only one side of the workpiece is exposed in step (B), only side A or only side B may be exposed, but it is preferable to expose side A.

[0046] When both sides of the workpiece are exposed in step (B), both sides of the workpiece may be exposed simultaneously or sequentially, but it is preferable to expose both sides of the workpiece sequentially. That is, when exposing both sides of the workpiece, step (B) preferably includes step (B-1) of exposing one side of the workpiece and, after step (B-1), step (B-2) of exposing the side of the workpiece opposite to the one side. 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).

[0047] In step (B), the integrated light amount when exposing the workpiece is preferably 50 mJ / cm from the viewpoint of further promoting the curing of the resin composition for forming the first cladding layer. 2 More preferably, 100 mJ / cm 2 More preferably, 150 mJ / cm 2 More preferably, 180 mJ / cm 2 or more, and preferably 1500 mJ / cm 2 Less than or equal to 1300 mJ / cm 2 or less, more preferably 1100 mJ / cm 2 The following is the result.

[0048] When both sides of the workpiece are exposed in step (B), the integrated light amount when at least one side of the workpiece is exposed is preferably within the above-mentioned numerical range, and more preferably, the integrated light amount when one side of the workpiece is exposed is within the above-mentioned numerical range, and the integrated light amount when the side opposite to the one side is exposed is also within the above-mentioned numerical range. The integrated light amount when one side of the workpiece is exposed and the integrated light amount when the side opposite to the one side are exposed may be the same value or different values.

[0049] The wavelength of light to be used when exposing 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-rays (365 nm), h-rays (405 nm), g-rays (436 nm), etc. may be used.

[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] [Process (C) of heating and pressing the workpiece] The method for producing a laminate in this embodiment includes a step (C) of heating and pressing the workpiece after the step (B). An optional step may be provided between step (B) and step (C).

[0052] By providing the method for producing a laminate with the step (C), the amount of depression can be suppressed. Although the reason for this is not clear, the present inventors speculate as follows. The present inventors believe that one of the reasons for the increase in the amount of depression is that the resin layer (a) is softened and the resin composition flows as a result of the heating step or the like. By providing the step (C) in the manufacturing method of the laminate, both sides of the work can be heated, which is believed to promote the curing reaction on both sides of the resin layer (a). This hardens both sides of the resin layer (a), suppressing the flow of the resin composition, and therefore suppressing the amount of dents.

[0053] As described above, the present inventors believe that one of the reasons for the increase in the amount of recess is that the low molecular weight compound contained in the resin composition for forming the first cladding layer is thermally decomposed and volatilized. Examples of such low molecular weight compounds include those that harden. By providing the step (C) in the laminate manufacturing method, the curing reaction of the resin composition is accelerated, and therefore, it is presumed that the low molecular weight compound is cured before it volatilizes, which makes it possible to suppress the volatilization of the low molecular weight compound, thereby suppressing the amount of dents.

[0054] Furthermore, in process (C), the workpiece is pressed, so it is sandwiched between two press plates. This makes it possible to suppress the volatilization of low molecular weight compounds, and it is assumed that the amount of denting can be further suppressed.

[0055] From the viewpoint of further suppressing the amount of denting, step (C) preferably includes step (C-1) of pressing the workpiece while increasing the temperature, and step (C-2) of pressing the workpiece while maintaining the workpiece at a constant temperature, and more preferably includes, in addition to steps (C-1) and (C-2), step (C-3) of pressing the workpiece while decreasing the temperature.

[0056] In step (C), the temperature to which the workpiece is heated is, from the viewpoint of further promoting the curing of the resin composition for forming the first clad layer, 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. 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 means the temperature at which the workpiece is pressed while being held at a constant temperature. Specifically, when step (C) includes steps (C-1) and (C-2), the temperature to which the workpiece is heated in step (C-2) means the temperature to which the workpiece is heated.

[0057] In step (C), the time for pressing the workpiece while heating is preferably 10 minutes or more, more preferably 20 minutes or more, from the viewpoint of further promoting the curing of the resin composition for forming the first clad 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 time for pressing the workpiece while heating means the time for pressing the workpiece while maintaining the workpiece at a constant temperature. Specifically, when step (C) includes steps (C-1) and (C-2), it means the time for heating the workpiece in step (C-2).

[0058] When step (C) includes step (C-1) of pressing the workpiece while heating it, the heating 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 dents.

[0059] In step (C), the pressure with which the workpiece is pressed is preferably 0.1 MPa or more, more preferably 0.15 MPa or more, and preferably 5.0 MPa or less, more preferably 4.0 MPa or less, even more preferably 3.0 MPa or less, even more preferably 2.0 MPa or less, even more preferably 1.0 MPa or less, even more preferably 0.5 MPa or less, even more preferably 0.3 MPa or less. Here, when step (C) comprises steps (C-1), (C-2) and (C-3), preferably, the pressure for pressing the workpiece in at least one step selected from the group consisting of steps (C-1), (C-2) and (C-3) is within the above-mentioned numerical range, and more preferably, the pressure for pressing the workpiece in all steps of steps (C-1), (C-2) and (C-3) is within the above-mentioned numerical range.

[0060] In step (C), the workpiece may be pressed while being heated at normal pressure, or may be pressed while being heated under reduced pressure.

[0061] In step (C), the method of heating and pressing the workpiece is not particularly limited, and for example, a known press machine can be used. When the workpiece is pressed while being heated under reduced pressure, for example, a known vacuum press machine can be used.

[0062] [Process (D) of removing the base film from the workpiece] The method for producing a laminate of the present embodiment preferably further includes a step (D) of removing the base film from the workpiece after the step (C). An optional step may be provided between step (C) and step (D).

[0063] 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.

[0064] [Other processes] The method for producing a laminate according to the present embodiment may include other steps in addition to the steps described above. Examples of such other steps include a step of further laminating another layer.

[0065] [Laminate] The laminate obtained by the method for producing a laminate of this embodiment includes a substrate having a through hole and a first cladding layer of an optical waveguide. The laminate of the present embodiment may further include other layers, and may be, 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.

[0066] 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 optical / electrical composite substrate of this embodiment may further include a polyimide base material on the surface of the second cladding layer opposite to the core layer side.

[0067] The optoelectronic composite substrate of this embodiment can be produced, for example, as follows. First, steps (A), (B) and (C) of this embodiment are performed to obtain a laminate including a substrate and a first clad layer. ) may further be provided. Thereafter, 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 onto the laminate to form a second clad layer. 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.

[0068] [Resin composition for forming the first clad layer] A preferred embodiment of the resin composition for forming the first cladding layer of this embodiment will be specifically described.

[0069] 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 type selected from the group consisting of polyimide resins, compounds having a cyclic ether structure, and copolymers of styrene-based monomers and diene-based monomers.

[0070] The resin composition for forming the first clad layer preferably contains a polyimide resin.

[0071] The polyimide resin preferably contains an imide ring structure in the molecule. The polyimide resin preferably contains a fluorinated polyimide, which means a polyimide containing a fluorine atom.

[0072] The polyimide resin in the resin composition for forming the first cladding layer may be one type of polyimide resin, or may contain two or more types of polyimide resins.

[0073] The resin composition for forming the first clad layer preferably contains a compound having a cyclic ether structure.

[0074] The compound having a cyclic ether structure preferably contains at least one or more types selected from the group consisting of epoxy compounds and oxetane compounds, and more preferably contains one or more types of epoxy compounds.

[0075] The compound having a cyclic ether structure preferably contains an alicyclic structure in the molecule. Here, the compound having a cyclic ether structure contains an alicyclic structure in the molecule means that the compound contains an alicyclic structure in addition to the cyclic ether structure. However, the alicyclic structure in this embodiment includes a condensed ring structure in which a cyclic ether and an aliphatic ring are condensed, and a spiro ring structure in which a cyclic ether and an aliphatic ring are bonded by 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.

[0076] 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.

[0077] 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 compounds having two or more types of cyclic ether structures.

[0078] 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 promoting the curing of the resin composition for forming the first cladding layer, a photopolymerization initiator is preferably included.

[0079] 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. The photocationic polymerization initiator includes, for example, a sulfonium salt type polymerization initiator and an iodonium salt type polymerization initiator, preferably a sulfonium salt type polymerization initiator, more preferably a triarylsulfonium salt type polymerization initiator, and further preferably a triphenylsulfonium salt type polymerization initiator.

[0080] The polymerization initiator in the resin composition for forming the first cladding layer may be a single type of polymerization initiator, or may contain two or more types of polymerization initiators.

[0081] The resin composition for forming the first cladding layer may appropriately contain components such as a surfactant.

[0082] 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.

[0083] 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, and 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.

[0084] 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.

[0085] 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 mass% or more, more preferably 90 mass% or more, even more preferably 95 mass% or more, even more preferably 97 mass% or more, even more preferably 98 mass% or more, when the total content of the non-volatile components in the resin composition for forming the first clad layer is 100 mass%, and is, for example, less than 100 mass%.

[0086] The content of the polymerization initiator included in the resin composition for forming the first clad layer is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, even more preferably 0.05 parts by mass or more, and even more preferably 0.07 parts by mass or more, when the total content of the resin components in the resin composition for forming the first clad layer is taken as 100 parts by mass, from the viewpoint of further promoting curing of the resin composition for forming the first clad 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.

[0087] The resin composition for forming the first clad layer can be obtained, for example, by mixing the respective components.

[0088] 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.

[0089] 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

[0090] 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.

[0091] [Raw materials] First, the raw materials constituting the resin composition for forming the first cladding layer will be described.

[0092] <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.

[0093] 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.

[0094] 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 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 the polyimide was 1.54.

[0095] <Polyimide resin (A)> (A-1) Polyimide resin synthesized above (Mw = 51,000, imidization rate 99% or more, refractive index n = 1.54)

[0096] [ka]

[0097] <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)

[0098] [ka]

[0099] <Photopolymerization initiator (C)> (C-1) CPI-310B (San-Apro Co., Ltd., photocationic polymerization initiator, triarylsulfonium salt)

[0100] <Surfactant (D)> (D-1) BYK-333 (BYK Japan Co., Ltd., silicone surfactant)

[0101] <Organic solvent (E)> (E-1) Propylene glycol monomethyl ether acetate (E-2) Propylene glycol monomethyl ether

[0102] <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.

[0103] <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)).

[0104] <Substrate with through holes> Through holes with a diameter of 100 μm were formed in a double-sided copper-clad laminate (CCL) with a thickness of 50 μm.

[0105] [Example 1] <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 superimposed so that the substrate and the resin layer (a) were in contact with each other. Next, the substrate and the film having the resin layer (a) were laminated using a vacuum laminator (manufactured by Nikko Materials Co., Ltd., product name: CVP-600) under the conditions of temperature: 140°C, pressure: 0.5 MPa, and time: 30 seconds. The laminate obtained after lamination was used as the workpiece. The layer structure of the workpiece is "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. The PET substrate in the workpiece is a PET substrate derived from a film having a resin layer (a).

[0106] <Process of exposing the workpiece (B)> The PET substrate side (side A) of the workpiece was exposed under the conditions of the integrated light amount shown in Table 1 using a direct imaging exposure machine (manufactured by SCREEN Co., Ltd., product name: LI-9000).

[0107] <Process (C) of heating and pressing the workpiece> After step (B), the workpiece was heated and pressed under the conditions of Table 1 using a press machine (Kitagawa Seiki Co., Ltd., product name: KVHC). Specifically, the workpiece was pressed while heating from room temperature (about 25°C) to the heating temperature listed in Table 1 at the heating rate listed in Table 1 (step (C-1)), the workpiece was kept at the heating temperature listed in Table 1 and pressed for the heating time listed in Table 1 (step (C-2)), and the workpiece was pressed while cooling from the heating temperature listed in Table 1 to room temperature at a cooling rate of 5°C / min (step (C-3)). In all steps (C-1), (C-2) and (C-3), the workpiece was pressed under a pressure of 0.2 MPa. In step (C), the workpiece was pressed under a vacuum (reduced pressure) atmosphere.

[0108] <Process (D) of removing the base film from the workpiece> After step (C), the PET substrate was peeled off from the workpiece, and the laminate of Example 1 was obtained.

[0109] [Example 2] A laminate of Example 2 was obtained in the same manner as in Example 1, except that, instead of step (B) of exposing the work in Example 1, step (B) was carried out in the following manner.

[0110] <Process of exposing the workpiece (B)> <Process of exposing one side of the workpiece (B-1)> First, the PET substrate side (side A) of the workpiece was exposed under the conditions of the integrated light amount shown in Table 1 using a direct imaging exposure machine (manufactured by SCREEN Co., Ltd., product name: LI-9000). <Process (B-2) of exposing the opposite side of the workpiece> Next, the substrate side surface (side B) of the workpiece was exposed under the conditions of the integrated light amount shown in Table 1 using a direct imaging exposure machine (manufactured by SCREEN Co., Ltd., product name: LI-9000).

[0111] [Comparative Examples 1 and 3] The laminates of Comparative Examples 1 and 3 were obtained in the same manner as in Example 1, except that instead of step (C) of heating and pressing the workpiece in Example 1, an oven was used to heat the workpiece under the conditions shown in Table 1.

[0112] [Comparative Example 2] The laminate of Comparative Example 2 was obtained in the same manner as in Example 1, except that instead of step (C) of heating and pressing the work in Example 1, the work was heated using an oven from room temperature to the heating temperature shown in Table 1 at the heating rate shown in Table 1, and then the work was held at the heating temperature shown in Table 1 and heated for the heating time shown in Table 1.

[0113] That is, Comparative Examples 1 to 3 are experimental examples in which the step (C) of heating and pressing the workpiece was not carried out.

[0114] [evaluation] <Evaluation of the amount of dent> For the laminates obtained in Examples 1 and 2 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 depression on the upper side is 3 μm or less, and the amount of depression on the lower side is 3 μm or less. B: At least one of the upper and lower recess amounts is greater than 3 μm. The evaluation results of the amount of dent are shown in Table 1.

[0115] [Table 1]

[0116] It can be seen from Table 1 that the laminates obtained by the manufacturing methods of the Examples all had good evaluations of the amount of dents. That is, according to the manufacturing method of the laminate of the present embodiment, the amount of dents in the obtained laminate can be suppressed. [Explanation of symbols]

[0117] 10a, 10b Depression amount 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)) 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; A step (B) of exposing the workpiece; A method for manufacturing a laminate, comprising: a step (C) of heating and pressing the workpiece after the step (B).

2. The method for producing a laminate according to claim 1 , wherein in the step (C), the temperature to which the workpiece is heated is 80° C. or higher and 200° C. or lower.

3. 3. The method for producing a laminate according to claim 1, wherein in the step (C), the work is pressed at a pressure of 0.1 MPa or more and 5.0 MPa or less.

4. The step (C) includes a step (C-1) of pressing the workpiece while heating it; A step (C-2) of pressing the workpiece while maintaining the workpiece at a constant temperature; The method for producing a laminate according to claim 1 or 2, further comprising: a step (C-3) of pressing the workpiece while lowering its temperature.

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

6. The workpiece further includes a base film, 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, 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 (C).

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. 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.

12. 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.

13. 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.

14. 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.

15. 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.

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