Manufacturing method of 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

[Technical Field]

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

[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] An example of an optical / electrical composite substrate is one in which an optical waveguide is provided on a substrate. Examples of techniques relating to optical and electrical composite substrates include those described in Patent Documents 1 and 2.

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

[0005] Patent Document 1 describes that a substrate is prepared in which copper foil 21 is formed on the front and back surfaces of an insulating layer 1 made of a resin such as polyimide, and that through holes 1a and via holes 1b for optical paths are formed in the substrate (see paragraph 0023 of Patent Document 1). It also describes a flexible double-sided circuit board E in which a metal reinforcing layer M is formed (see paragraph 0028 of Patent Document 1). The flexible double-sided circuit board E includes the above-mentioned 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 molding materials for the undercladding layer 6 include photosensitive resins and thermosetting resins (see paragraph 0029 of Patent Document 1).From Figures 4 to 6 of Patent Document 1, it can be seen that the molding material for the undercladding layer 6 is filled into recesses formed in the flexible double-sided circuit board E on which the metal reinforcing layer M is formed.

[0006] Patent Document 2 describes an opto-electrical wiring board that is formed by integrating a rigid section in which conductor circuits and insulating layers are laminated on both sides of a substrate with one or more bendable flex sections, wherein the rigid section has external connection terminals formed therein for mounting optical elements and / or package substrates on which optical elements are mounted, and at least one of the flex sections has optical wiring formed therein. According to the optoelectronic wiring board of Patent Document 2, it is described that large amounts of information can be suitably processed and information can be processed at high speed 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 states that the resin layer 221a forms 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] Japanese Patent Application Laid-Open No. 2014-238455 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-140233 Summary of the Invention [Problem to be solved by the invention]

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

[0011] An example of an optoelectronic 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.The inventors have found through their studies that in such optoelectronic composite substrates, 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. [Means for solving the problem]

[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; A method for manufacturing a laminate, comprising: a step (B) of exposing both surfaces of the workpiece to light. [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 the laminate according to [1] above, which is as follows: [3] The step (B) includes a step (B-1) of exposing one surface of the workpiece; The method for manufacturing a laminate according to [1] or [2] above, further comprising, after the step (B-1), a step (B-2) of exposing the surface of the workpiece opposite to the one surface. [4] The method for producing a laminate according to any one of [1] to [3] above, further comprising a step (C) of heating the workpiece after the step (B). [5] The method for producing a laminate according to [4] above, 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 method for producing a laminate according to any one of [1] to [5] above, wherein the substrate is positioned as the outermost layer of the workpiece. [7] The workpiece further comprises a base film, The method for producing a laminate according to any one of [1] to [6] above, 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. [8] the base film is a resin film, The method for producing a laminate according to [7] 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. [9] The method for producing a laminate according to [7] or [8] above, further comprising a step (D) of removing the base film from the workpiece after the step (B).

[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 clad layer contains a compound having a cyclic ether structure.

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

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

[12] The method for producing a laminate according to any one 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] above, wherein T / R is 0.10 or more, where T [μm] is the thickness of the substrate and R [μm] is the diameter of the through-hole.

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

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

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

[14] above, 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 taken as 100% by volume, 70% or more by volume of the through hole is filled with a resin composition for forming the first clad layer.

[17] The method for producing 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. [Effects of the Invention]

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

[0016] [Figure 1] 1 is a cross-sectional view schematically showing an example of the structure of an optoelectronic composite substrate according to an embodiment of the present invention. [Figure 2] FIG. 10 is a diagram for explaining the amount of depression. [Figure 3] FIG. 2 is a cross-sectional view schematically showing an example of the structure of a workpiece. [Figure 4] FIG. 10 is a cross-sectional view schematically illustrating an example of the structure of a workpiece further including a base film. DETAILED DESCRIPTION OF THE INVENTION

[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 actual dimensional proportions. 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 showing a schematic example of the structure of an optoelectronic composite substrate according to this embodiment. As shown in FIG. 1, an optical / electrical composite substrate 200 has 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. 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) (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 optical / electrical 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 through-hole 140a formed in the substrate 110, enters mirror 50 on the light-emitting element side, and is transmitted through core layer 30. After that, it enters mirror 60 on the light-receiving element side, passes through through-hole 140b formed in the substrate 110, and enters light-receiving element 130. The arrows in Figure 1 schematically illustrate 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, since the through-holes 140 in the optical / electrical composite substrate 200 are a path for 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 manufacturing 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 clad layer of an optical waveguide, and comprises 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 step (B) of exposing both sides of the workpiece. Hereinafter, in this specification, for the sake of simplicity, the "layer made of a resin composition for forming the first cladding layer" may be referred to as the "resin layer (a)".

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

[0025] [Workpiece 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 410. In Fig. 3, a substrate 110 and a layer (resin layer (a)) 310 made of a resin composition for forming a first clad layer are laminated together. 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. The substrate 110 may be, for example, a printed circuit board or a flexible substrate, 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 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 serve as 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, but 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 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] In the workpiece of this embodiment, the through-holes 140 may be filled with a resin composition for forming a first cladding layer. In the workpiece of this embodiment, the proportion of the resin composition for forming the first cladding layer filled in the through hole is preferably 70% by volume or more, more preferably 75% by volume or more, even more preferably 80% by volume or more, even more preferably 85% by volume or more, even more preferably 90% by volume or more, even more preferably 95% by volume or more, even more preferably 98% by volume or more, even more preferably 99% by volume or more, and is, for example, 100% by volume or less, from the viewpoint of further suppressing the propagation loss of the optical waveguide, when the volume of the through hole is taken as 100% by volume.

[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 work of this embodiment preferably further comprises a base film, and the substrate, a layer (resin layer (a)) made of a resin composition for forming the first clad layer, and the base film are laminated in this order, and 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 work of this embodiment, the substrate is preferably located as the outermost layer of the work. 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 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 the base film to the workpiece of this embodiment, the amount of recess can be further reduced. Although the reason for this is not clear, 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 (for example, 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 recession 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) in the workpiece, it is possible to suppress the volatilization of the low molecular weight compound, thereby further suppressing the amount of recession.

[0038] The base film 320 may be, for example, a resin film. The resin constituting the base film 320 is not particularly limited, but may include, 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 substrate 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 methods. First, a film in which a resin layer (a) and a base film are laminated is prepared, and then a substrate having through holes 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 (B) of exposing both sides of the workpiece] The method for manufacturing a laminate of this embodiment includes a step (B) of exposing both surfaces of 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] The workpiece in this embodiment is a laminate in which a substrate and a resin layer (a) are laminated, and therefore exposing both sides of the workpiece means exposing one side of the laminate and the side opposite to the one side.

[0044] Both sides of the workpiece will be specifically described with reference to the drawings. The two surfaces of the workpiece 410 shown in FIG. 3 are a surface 410A of the resin layer (a) 310 opposite the substrate 110 side, and a 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 a surface 420A of the base film 320 opposite to the resin layer (a) 310 side, and a surface 420B of the substrate 110 opposite to the resin layer (a) 310 side. Hereinafter, in this specification, the surface (410A, 420A) on which the resin layer (a) 310 of the workpiece 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] The amount of depression can be reduced by including step (B) in the manufacturing method of the laminate. The reason for this is not clear, but 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) softens and the resin composition flows when a heating step or the like is performed. It is believed that the inclusion of step (B) in the manufacturing method of the laminate further accelerates the curing reaction on both sides of the resin layer (a), which hardens both sides of the resin layer (a) and suppresses the flow of the resin composition, thereby suppressing the amount of depression.

[0046] As mentioned above, the present inventors believe that one of the reasons for the increased depth of the recess 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. The inclusion of step (B) in the laminate manufacturing method further accelerates the curing reaction of the resin composition, and it is therefore speculated that the low molecular weight compound is cured before it volatilizes, thereby making it possible to suppress the volatilization of the low molecular weight compound and thereby reducing the amount of depression.

[0047] 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, 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 integrated light amount when exposing the workpiece is not particularly limited, but the preferred range is as follows. The integrated amount of light when exposing at least one surface of the workpiece is preferably 50 mJ / cm 2 from the viewpoint of further promoting the curing of the resin composition for forming the first clad 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 or less, more preferably 1300 mJ / cm 2 or less, more preferably 1100 mJ / cm 2 The following is the result. More preferably, the integrated light amount when exposing one side of the workpiece is within the above numerical range, and the integrated light amount when exposing the side opposite to the one side is also within the above numerical range. The integrated light amount when exposing one surface of the workpiece and the integrated light amount when exposing the surface opposite to the one surface may be the same value or may be 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] [Workpiece heating process (C)] The method for producing a laminate of this embodiment preferably further includes a step (C) of heating the workpiece after the step (B). An optional step may be provided between step (B) and step (C).

[0052] From the viewpoint of further suppressing the amount of recession, step (C) preferably comprises step (C-1) of raising 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 comprises step (C-3) of lowering 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, from the viewpoint of further promoting the curing of the resin composition for forming the first clad layer, 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 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 above-mentioned temperature to which the workpiece is heated refers to the temperature at 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 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 above-mentioned workpiece heating time means the time for heating the workpiece while maintaining it 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 it at a constant temperature, the above-mentioned workpiece heating time means the time for heating the workpiece in step (C-2).

[0055] When step (C) includes step (C-1) of heating the workpiece, 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 depression.

[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] [Process (D) of removing the base film from the workpiece] The method for producing a laminate of this embodiment preferably further includes a step (D) of removing the base film from the workpiece after the step (B). An optional step may be included between step (B) and step (D), and preferably step (C) is included. That is, in the method for producing a laminate of this embodiment, the steps are preferably carried out 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 processes] The method for producing a laminate according to the present embodiment may include other steps in addition to the steps described above, such as 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, 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 is a concept that 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, 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 and electrical composite substrate of this embodiment may further include a polyimide substrate on the surface of the second clad layer opposite to the core layer side.

[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 performed. Thereafter, a film for forming a core layer is laminated onto the laminate to form the core layer, and then a film for forming a second clad layer is laminated onto the laminate to form the second clad layer. The method for producing the optical / electrical composite substrate may include steps such as forming a waveguide pattern in the core layer and forming a mirror on the optical waveguide, as appropriate.

[0063] [Resin composition for forming the 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 resin 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, which means a polyimide containing fluorine atoms.

[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 two or more compounds selected from the group consisting of epoxy compounds and oxetane compounds, and more preferably contains one or two or more epoxy compounds.

[0070] The compound having a cyclic ether structure preferably contains an alicyclic structure in the molecule. Here, the compound having a cyclic ether structure containing 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 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 bonding 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. 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 compounds having two or more types of 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 cladding layer, a photopolymerization initiator is preferably included.

[0075] 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 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 type of polymerization initiator, or may contain two or more types of 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 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.

[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, even more preferably 35 parts by mass or more, and is preferably 80 parts by mass or less, more preferably 75 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.

[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, when the total content of non-volatile components in the resin composition for forming the first clad layer is taken as 100% by mass, and is, for example, less than 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 promoting 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 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 can also be adopted. Furthermore, the present invention is not limited to the above-described embodiment, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[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, the raw materials constituting the resin composition for forming the first clad layer will be described.

[0088] <Synthesis of Polyimide Resin (A-1)> A 3-liter separable glass flask equipped with a stirrer and a stirring blade was charged with 67.3 g (0.210 mol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 97.7 g (0.220 mol) of 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and 495 g of dimethylacetamide, which were stirred and dissolved. The mixture was further stirred at room temperature under a nitrogen stream for 12 hours to carry out the polymerization reaction, yielding a polyamic acid solution.

[0089] After adding 16 g of pyridine to the obtained polyamic acid solution, 82 g of acetic anhydride was added dropwise at room temperature, and then the liquid temperature was kept 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 resulting polyimide solution was poured into 1,000 g of methanol in a 5 L container while stirring to precipitate the polyimide resin. The solid polyimide resin was then filtered using a suction filter and washed with 1,000 g of methanol. The solid was then dried at 100°C for 24 hours using a vacuum dryer, and then further dried at 200°C for 3 hours to obtain 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 measurement was performed, 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, followed by drying 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] [ka]

[0093] <Compound (B) Having a Cyclic Ether Structure> (B-1) Celloxide 2021P (manufactured by Daicel Corporation, epoxy compound with an alicyclic structure, liquid at 23°C, refractive index 1.51)

[0094] [ka]

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

[0096] <Surfactant (D)> (D-1) BYK-333 (BYK Japan Co., Ltd., 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 weight of polyimide resin (A-1), 50 parts by weight of compound (B-1) having a cyclic ether structure, 0.10 parts by weight of photopolymerization initiator (C-1), 0.10 parts by weight of surfactant (D-1), 80 parts by weight of organic solvent (E-1), and 40 parts by weight 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 with a pore size of 0.2 μm to obtain a varnish-like resin composition for forming a first clad layer.

[0099] <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 varnish form obtained by the above method was applied to a 38 μm thick antistatic 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 thickness after drying 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 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)).

[0100] <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.

[0101] [Examples 1 and 2] <Work preparation process (A)> The OPP cover film was peeled off from the film with resin layer (a) obtained by the above method, and the substrate with through holes and the film with resin layer (a) were each superimposed so that the resin layer (a) was in contact with the substrate. Next, using a vacuum laminator (manufactured by Nikko Materials Co., Ltd., product name: CVP-600), the substrate and the film with resin layer (a) were each laminated 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." 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).

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

[0103] <Process (C) of heating the workpiece> After step (B), each workpiece was heated in an oven under the conditions shown in Table 1.

[0104] <Process (D) of removing the base film from the workpiece> After step (C), the PET substrate was peeled off from the workpiece to obtain the laminates of Examples 1 and 2, respectively.

[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 by step (C) performed in the following manner.

[0106] <Process (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)). The workpiece was continuously pressed at a pressure of 0.2 MPa throughout the heating step, holding step, and cooling step. 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 the step (B-2) of exposing the surface opposite to the one surface of the workpiece in Examples 1 and 2 was not performed. In Comparative Example 2, in step (C), the workpiece 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 workpiece was held 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 surface of the workpiece was exposed, and both surfaces of the workpiece were not exposed.

[0109] [evaluation] <Evaluation of the amount of dent> The laminates obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were measured for the amount of recession on the upper side (corresponding to 10a in FIG. 2) and the amount of recession on the lower side (corresponding to 10b in FIG. 2) using a confocal microscope (manufactured by Olympus Corporation, product name: LEXT OLS3100). The amount of recession 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 recession are shown in Table 1.

[0110] [Table 1]

[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. In other words, the manufacturing method of the laminate of this embodiment can suppress the amount of recession of the obtained laminate.

[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 resulting workpiece was used to prepare laminates of Examples 1' to 3' and Comparative Examples 1' to 3' by the same method, except that step (D) was not performed. In other words, these are experimental examples in which the layer structure of the workpiece 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, the same evaluation results as 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. [Explanation of symbols]

[0114] 10a, 10b Depression 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 Photodetector 140, 140a, 140b through hole 200 Optical and electrical composite substrate 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, 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 (B) a step of exposing both surfaces of the workpiece, The workpiece has the substrate positioned on the outermost layer of the workpiece, The method for producing a laminate, wherein the resin composition for forming the first clad layer contains a compound having a cyclic ether structure.

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; 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 manufacturing 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 comprises 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 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 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 or 2, wherein the resin composition for forming the first clad layer contains a photopolymerization initiator.

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

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

12. The method for producing a laminate according to claim 1 or 2, wherein the through holes have a 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 thickness of the substrate is 10 μm or more and 1000 μm or less.

14. 3. The method for manufacturing a laminate according to claim 1, wherein the workpiece has a resin composition for forming the first clad layer filled in at least 70% by volume of the through hole when the volume of the through hole is taken as 100% by volume.

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 on the first clad layer in this order.

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