Manufacturing method of laminate

Abstract

A method for manufacturing a laminate comprising a substrate (110) having a through hole (140) and a first clad layer (20) of an optical waveguide (100), the method comprising at least the steps of: preparing a work (400) on the substrate (110) and having a resin film (300) placed thereon, the work having a resin layer (a) (310) made of a resin composition for forming the first clad layer (20); and laminating the first clad layer (20) onto the substrate (110) by heating and pressing the work (400) under reduced pressure using a vacuum laminator.

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. Techniques relating to a method for manufacturing an optical waveguide include, for example, the techniques described in Patent Documents 1 to 3.

[0004] Patent Document 1 describes a method for producing an embedded polyimide optical waveguide, which is characterized in that an upper cladding between an arbitrary substrate and a ridge-type waveguide has the same heat resistance as the substrate and is bonded together with an adhesive with a lower refractive index than the core. According to the method for producing a polyimide optical waveguide described in Patent Document 1, it is described that a polyimide optical waveguide can be produced on any substrate.

[0005] Patent Document 2 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 2, 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.

[0006] Patent Document 2 describes a method of preparing a substrate 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 forming through holes 1a and via holes 1b for an optical path in the substrate (see paragraph 0023 of Patent Document 2). It also describes a flexible double-sided circuit board E in which a metallic reinforcing layer M is formed (see paragraph 0028 of Patent Document 2). The flexible double-sided circuit board E includes the above substrate. Furthermore, Patent Document 2 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 2). According to Figures 4 to 6 of Patent Document 2, 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.

[0007] Patent Document 3 describes an optoelectronic wiring board that is formed by integrating a rigid section in which conductor circuits and insulating layers are laminated on both sides of a substrate with one or more bendable flex sections, wherein the rigid section 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 3, 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.

[0008] Patent Document 3 describes that the rigid section has an optical signal transmitting region formed therein, and that the optical signal transmitting region is filled with a resin composition (see claims 4 and 5 of Patent Document 3). Furthermore, Patent Document 3 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 3).

[0009] Furthermore, Patent Document 3 describes a substrate 221 consisting of an optical waveguide film 250 and a surrounding resin layer (insulating layer) 221a, and describes that the resin layer 221a constitutes part of the optical signal transmitting regions 242a, 242b (see paragraph 0033 of Patent Document 3). [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2000-321455 A [Patent Document 2] JP 2014-238455 A [Patent Document 3] JP 2006-140233 A Summary of the Invention [Problem to be solved by the invention]

[0011] In conventional technology relating to optoelectronic composite substrates, there are known optoelectronic composite substrates in which recesses and through holes formed in a substrate are filled with a resin composition (see, in particular, Patent Documents 2 and 3).

[0012] The manufacturing process of the photoelectric composite substrate includes, for example, a process of integrating a substrate having a through hole with a film for optical waveguide clad. In this process, the through hole formed in the substrate needs to be filled with the optical waveguide clad (hereinafter, "embedding property" refers to the property of how much the optical waveguide clad can be embedded in the through hole).

[0013] The present invention has been made in consideration of the above circumstances, and provides a method for producing a laminate that can provide an optoelectronic composite substrate with improved embeddability. [Means for solving the problem]

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

[0015] [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 on which a resin film having a resin layer (a) made of a resin composition for forming the first clad layer is placed on the substrate; and (B) laminating the first cladding layer onto the substrate by heating and pressing the work under reduced pressure using a vacuum laminator. [2] The method for producing a laminate according to [1] above, 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. [3] The method for producing a laminate according to [1] or [2] above, wherein the through holes have a hole diameter of 10 μm or more and 1000 μm or less. [4] The method for producing a laminate according to any one of the above [1] to [3], wherein the substrate has a thickness of 10 μm or more and 1000 μm or less. [5] The method for producing a laminate according to any one of the above [1] to [4], wherein the resin layer (a) has a thickness of 10 μm or more and 300 μm or less. [6] The method for producing a laminate according to any one of the above [1] to [5], wherein the resin layer (a) has a thickness smaller than that of the substrate. [7] The resin layer (a) has a complex viscosity η* of 1.0×10 at 100° C. when the complex viscosity is measured by a melt viscoelasticity test under the conditions of a measurement frequency of 10 rad / sec, a temperature range of 23° C. to 200° C., and a temperature rise rate of 3° C. / min. 3 Pa·s or more 1.0×10 7 The method for producing a laminate according to any one of the above [1] to [6], wherein the viscosity is 0.01 Pa·s or less. [8] The method for producing a laminate according to any one of the above [1] to [7], wherein the resin layer (a) contains at least one selected from the group consisting of a polyimide resin, a compound having a cyclic ether structure, and a copolymer of a styrene-based monomer and a diene-based monomer. [9] The method for producing a laminate according to any one of the above [1] to [8], wherein in the step (B), the work is heated to 80° C. or more and 190° C. or less and pressed.

[10] The method for producing a laminate according to any one of the above [1] to [9], wherein in the step (B), the work is sandwiched between two press plates, and the work is heated and pressed.

[11] The method for producing a laminate according to

[10] above, wherein in the step (B), at least one of the two press plates contains rubber.

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

[11] , wherein in the step (B), the degree of vacuum is 500 Pa or less.

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

[12] , wherein in the step (B), the work is pressed with a pressure of 0.3 MPa or more and 10.0 MPa or less.

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

[13] , further comprising, after the step (B), a step (C) of sandwiching the workpiece between two press plates and heating and pressing the workpiece.

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

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

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

[15] 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

[0016] According to the present invention, it is possible to provide a method for producing a laminate that can provide an optoelectronic composite substrate with improved embeddability. [Brief description of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view showing a schematic example of a structure of an optical / electrical composite substrate according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic example of a structure of a workpiece in step (A). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Furthermore, a numerical range of "A to B" means A or more and B or less unless otherwise specified.

[0019] 1 is a cross-sectional view showing a schematic example of the structure of an optoelectronic composite substrate according to the present embodiment, the drawing being a simplified view and not in accordance with the actual dimensional ratio. 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.

[0020] 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.

[0021] According to the study of the present inventors, it was found that in the conventional manufacturing method of the optical / electrical composite substrate, the first clad layer cannot be sufficiently embedded in the through-hole formed in the substrate, and thus a depression may occur on the surface of the optical waveguide clad opposite to the substrate side (i.e., the core layer side of the first clad layer) or a void may occur in the through-hole. The through-hole is a propagation path of light, and it was found that when the above-mentioned depression or void occurs in the optical / electrical composite substrate, an optical loss occurs at the interface of the depression or void. The present invention has been made in consideration of the above circumstances, and provides a method for producing a laminate that can provide an optoelectronic composite substrate with improved embeddability.

[0022] The method for manufacturing a laminate of the present 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 at least a step (A) of preparing a workpiece on which a resin film having a resin layer (a) made of a resin composition for forming the first clad layer is placed on the substrate, and a step (B) of laminating the first clad layer onto the substrate by heating and pressing the workpiece under reduced pressure using a vacuum laminator.

[0023] Hereinafter, each step of the method for producing the laminate of this embodiment will be specifically described.

[0024] [Work preparation process (A)] The method for manufacturing a laminate of this embodiment includes a step (A) of preparing a workpiece on which a resin film having a resin layer (a) made of a resin composition for forming a first cladding layer is placed on a substrate.

[0025] 2 is a cross-sectional view showing a schematic example of the structure of the workpiece in step (A). Note that the drawing is a simplified drawing and does not correspond to the actual dimensional ratio. The workpiece 400 has a resin film 300 provided with a resin layer (a) 310 made of a resin composition for forming a first clad layer placed on a substrate 110. Here, a through hole 140 is formed in the substrate 110.

[0026] The resin film 300 may be a single-layer film consisting of only the resin layer (a) 310, or may be a multi-layer film as shown in FIG. 2, but is preferably a film in which the resin layer (a) 310 and a base film 320 are laminated. When the resin film 300 includes the base film 320, the handleability of the resin film 300 is improved, and contamination of the vacuum laminating device can be prevented. When the resin film 300 is a multi-layer film, the workpiece 400 is placed on the substrate 110 with the resin layer (a) 310 facing the substrate 110.

[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 . Specifically, for example, in the substrate 110 shown in FIG. 1 and FIG. 2, the through-hole 140 serves as a light propagation path, so 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.

[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 140 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 0.27 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. Generally, the larger the T / R, the more difficult it is to sufficiently fill the through-hole with the first clad layer. On the other hand, according to the method for manufacturing the laminate of the present embodiment, even when the T / R is large, it is possible to sufficiently fill the through-hole with the first clad layer.

[0032] A preferred embodiment of the resin film 300 will be described later.

[0033] [Laminating process (B)] The method for producing a laminate of this embodiment includes a step (B) of laminating a first cladding layer onto a substrate by heating and pressing a workpiece under reduced pressure using a vacuum laminator. The substrate and the resin layer (a) can be laminated by heating and pressing the workpiece under reduced pressure. Since the resin layer (a) is made of a resin composition for forming the first clad layer, in other words, the substrate and the first clad layer can be laminated by heating and pressing the workpiece under reduced pressure.

[0034] In step (B), the workpiece is heated and pressed under reduced pressure. Here, reduced pressure means that the degree of vacuum is smaller than normal pressure (1013 hPa). In step (B), from the viewpoint of further improving embeddability, the degree of vacuum is preferably 500 Pa or less, more preferably 400 Pa or less, even more preferably 350 Pa or less, and even more preferably 320 Pa or less. The lower limit is not particularly limited, but may be, for example, 10 Pa or more, or 50 Pa or more.

[0035] In step (B), the pressure when pressing the workpiece is preferably 0.3 MPa or more, more preferably 0.5 MPa or more, even more preferably 1.0 MPa or more, even more preferably 1.3 MPa or more, even more preferably 2.0 MPa or more, even more preferably 3.0 MPa or more, and even more preferably 4.0 MPa or more, from the viewpoint of further improving embeddability, and is preferably 10.0 MPa or less, more preferably 8.0 MPa or less, and even more preferably 6.0 MPa or less, from the viewpoint of preventing damage to the substrate.

[0036] In step (B), the temperature of the workpiece when it is heated and pressed is, from the viewpoint of further improving embeddability, preferably 80°C or higher, more preferably 90°C or higher, even more preferably 95°C or higher, and preferably 190°C or lower, more preferably 180°C or lower, even more preferably 150°C or lower, even more preferably 145°C or lower. Here, the temperature of the workpiece may be considered to be the same as the set press temperature of the vacuum laminator, because the workpiece is thin and therefore the temperature of the workpiece is considered to reach the same temperature as the set press temperature within a few seconds after being placed in the vacuum laminator.

[0037] In step (B), the time for pressing the workpiece is preferably 30 seconds or more, more preferably 60 seconds or more, even more preferably 80 seconds or more, and even more preferably 100 seconds or more, from the viewpoint of further improving embeddability, and is preferably 210 seconds or less, more preferably 180 seconds or less, even more preferably 150 seconds or less, and even more preferably 130 seconds or less, from the viewpoint of further improving productivity.

[0038] In the step (B), the method for heating and pressing the workpiece is not particularly limited, and may be a plate press or a roll press. In step (B), the method of heating and pressing the workpiece is preferably a plate pressing method. In other words, in step (B), the workpiece is preferably sandwiched between two press plates and heated and pressed.

[0039] In step (B), when the workpiece is sandwiched between two press plates and heated and pressed, it is preferable that at least one of the two press plates contains rubber, and it is preferable that both of the two press plates contain rubber. The rubber is not particularly limited, but examples thereof include silicone rubber, fluororubber, and acrylic rubber. When the press plate has a structure of two or more layers, it is preferable that the surface of the press plate that comes into contact with the workpiece contains rubber.

[0040] In the step (B), the vacuum laminator is not particularly limited, but for example, a rubber press type laminator, a diaphragm type laminator, etc. can be used, and preferably a rubber press type laminator is used. Specifically, examples of rubber press laminator machines include CVP-600 (manufactured by Nikko Materials Co., Ltd.) and CVP-700 (manufactured by Nikko Materials Co., Ltd.). Examples of diaphragm laminator machines include CVP-300 (manufactured by Nikko Materials Co., Ltd.) and MVLP-500 / 600-IIA (manufactured by Meiki Seisakusho Co., Ltd.).

[0041] [Pressing process (C)] The method for producing the laminate of this embodiment preferably further comprises, after step (B), step (C) of sandwiching the work between two press plates and heating and pressing the work. By further comprising step (C), it becomes possible to further improve the embeddability, and more specifically, it becomes possible to suppress the occurrence of dents on the surface of the first cladding layer opposite to the substrate side.

[0042] The degree of vacuum in step (C) is not particularly limited, and the workpiece may be heated and pressed at normal pressure, or may be heated and pressed under reduced pressure. When the workpiece is heated and pressed under reduced pressure in step (C), the preferred degree of vacuum is the same as the preferred degree of vacuum in step (B).

[0043] In step (C), the pressure when pressing the workpiece is preferably 0.3 MPa or more, more preferably 0.5 MPa or more, even more preferably 1.0 MPa or more, even more preferably 1.3 MPa or more, even more preferably 2.0 MPa or more, even more preferably 3.0 MPa or more, and even more preferably 4.0 MPa or more, from the viewpoint of further improving embeddability, and is preferably 10.0 MPa or less, more preferably 8.0 MPa or less, and even more preferably 6.0 MPa or less, from the viewpoint of preventing damage to the substrate.

[0044] In step (C), the temperature of the workpiece when it is heated and pressed is, from the viewpoint of further improving embeddability, preferably 80°C or higher, more preferably 90°C or higher, even more preferably 95°C or higher, and preferably 190°C or lower, more preferably 180°C or lower, even more preferably 150°C or lower, even more preferably 145°C or lower. Here, the temperature of the workpiece may be considered to be the same as the set press temperature of the press device, because the workpiece is thin and therefore the temperature of the workpiece is considered to reach the same temperature as the set press temperature within a few seconds after being placed in the press device.

[0045] In step (C), the time for pressing the workpiece is preferably 5 seconds or more, more preferably 10 seconds or more, and even more preferably 20 seconds or more, from the viewpoint of further improving embeddability, and is preferably 100 seconds or less, more preferably 80 seconds or less, more preferably 60 seconds or less, and even more preferably 40 seconds or less, from the viewpoint of further improving productivity.

[0046] In the step (C), the method for heating and pressing the workpiece is not particularly limited, and may be a plate press or a roll press. In step (C), the method of heating and pressing the workpiece is preferably a plate pressing method. In other words, in step (C), the workpiece is preferably sandwiched between two press plates and heated and pressed.

[0047] In step (C), the pressing device is not particularly limited, but from the viewpoint of further improving productivity, it is preferable that the vacuum laminating device used in step (B) is a two-stage type, and a flattening stage corresponding to the second stage is used. That is, when the vacuum laminating device is a two-stage type, step (B) can be performed in a laminator corresponding to the first stage, and step (C) can be performed in a flattening stage corresponding to the second stage. After step (B), the workpiece may be removed from the vacuum laminating apparatus used in step (B), and step (C) may be carried out by a press apparatus different from that used in step (B).

[0048] [Other processes] The method for producing the laminate of the present embodiment may include steps other than the steps (A), (B) and (C). Examples of the other steps include a step of laminating another layer after the step (C).

[0049] [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. Here, in the laminate of this embodiment, the first cladding layer of the optical waveguide is conceptually understood to include the resin layer (a). 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.

[0050] 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.

[0051] The optoelectronic composite substrate of this embodiment can be produced, for example, as follows. First, the steps (A) and (B) of this embodiment are performed to obtain a laminate having a substrate, a first clad layer, and a base film in this order. When obtaining a laminate having a substrate, a first clad layer, and a base film in this order, a step (C) may be further included. Thereafter, the base film is peeled off from the laminate having the substrate, the first clad layer, and the base film in that order, and a film for forming a core layer is laminated to form the core layer, and then a film for forming a second clad layer is laminated to form the second clad layer. In addition, the method 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.

[0052] In the laminate of this embodiment, when the volume of the through hole formed in the substrate is taken as 100 volume %, from the viewpoint of further suppressing the propagation loss of the optical waveguide, it is preferable that 70 volume % or more of the through hole is filled with the resin composition for forming the first clad layer. The proportion of the resin composition for forming the first cladding layer filled in the through hole, when the volume of the through hole is taken as 100 volume%, from the viewpoint of further suppressing the propagation loss of the optical waveguide, is 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. The resin composition for forming the first clad layer is the resin composition derived from the resin layer (a) of the resin film.

[0053] [Resin film] The resin film having the resin layer (a) made of a resin composition for forming the first clad layer of this embodiment will be specifically described.

[0054] From the viewpoint of further improving embeddability, the thickness of the resin layer (a) is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more, and from the viewpoint of further improving the light propagation efficiency of the optical waveguide, the thickness 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.

[0055] The thickness of the resin layer (a) is preferably smaller than the thickness of the substrate. The thickness of the resin layer (a), when the thickness of the substrate is taken as 100%, is preferably 80% or less, more preferably 70% or less, even more preferably 65% ​​or less, even more preferably 60% or less, and even more preferably 55% or less, and may be, for example, 10% or more, or 15% or more.

[0056] Here, the thickness of the resin layer (a) in this specification means the thickness of the resin layer (a) in step (A). That is, in the method for producing a laminate of this embodiment, the work is pressed in step (B), but the thickness of the resin layer (a) in this specification does not mean the thickness after pressing.

[0057] The resin contained in the resin layer (a) is not particularly limited, and may be any resin that can be used to form a cladding layer of an optical waveguide. Among them, the resin layer (a) preferably contains at least one selected from the group consisting of polyimide resins, compounds having a cyclic ether structure, and copolymers of styrene-based monomers and diene-based monomers.

[0058] The resin layer (a) more preferably contains a polyimide resin and a compound having a cyclic ether structure.

[0059] The polyimide resin in the resin layer (a) preferably contains an imide ring structure in the molecule. The polyimide resin in the resin layer (a) preferably contains a fluorinated polyimide, which means a polyimide containing a fluorine atom.

[0060] The polyimide resin in the resin layer (a) may be a single type of polyimide resin, or may contain two or more types of polyimide resins.

[0061] The compound having a cyclic ether structure in the resin layer (a) preferably contains at least one or more types selected from the group consisting of epoxy resins and oxetane compounds, and more preferably contains one or more types of epoxy resins.

[0062] The compound having a cyclic ether structure in the resin layer (a) 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 it 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.

[0063] The compound having a cyclic ether structure in the resin layer (a) preferably contains two or more cyclic ether structures in the molecule, and more preferably contains two or three cyclic ether structures in the molecule.

[0064] The compound having a cyclic ether structure in the resin layer (a) may be a compound having one type of cyclic ether structure, or may contain compounds having two or more types of cyclic ether structures.

[0065] The content of the polyimide resin contained in the resin layer (a), when the total content of the resin components in the resin layer (a) is 100 parts by mass, is, from the viewpoint of further improving embeddability, preferably 20 parts by mass or more, more preferably 23 parts by mass or more, even more preferably 25 parts by mass or more, and even more preferably 28 parts by mass or more, and from the viewpoint of further improving embeddability, 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.

[0066] The content of the compound having a cyclic ether structure contained in the resin layer (a) is, when the total content of the resin components in the resin layer (a) is taken as 100 parts by mass, from the viewpoint of further improving embeddability, 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, and from the viewpoint of further improving embeddability, preferably 80 parts by mass or less, more preferably 75 parts by mass or less.

[0067] The total content of the polyimide resin and the compound having a cyclic ether structure contained in the resin layer (a) is preferably 80 mass% or more, more preferably 90 mass% or more, even more preferably 95 mass% or more, and still more preferably 97 mass% or more, when the total content of all components in the resin layer (a) is 100 mass%, and may be, for example, 99.5 mass% or less, or 99.0 mass% or less.

[0068] More preferably, the resin layer (a) contains a copolymer of a styrene monomer and a diene monomer, and a compound having a cyclic ether structure. Here, the copolymer of a styrene-based monomer and a diene-based monomer in this embodiment also includes a copolymer obtained by hydrogenating a copolymer of a styrene-based monomer and a diene-based monomer. The compound having a cyclic ether structure is as described above.

[0069] In the copolymer of a styrene monomer and a diene monomer, the styrene monomer means styrene or a monomer in which some of the hydrogen atoms of styrene are substituted with an alkyl group, such as a methyl group, an ethyl group, or a propyl group.

[0070] In the copolymer of a styrene monomer and a diene monomer, examples of the diene monomer include 1,3-butadiene and isoprene.

[0071] Specific examples of copolymers of styrene-based monomers and diene-based monomers include styrene-butadiene rubber, styrene-butadiene-styrene (SBS) block copolymer, styrene-ethylene-butylene-styrene (SEBS) block copolymer, styrene-ethylene-propylene (SEP) block copolymer, and styrene-ethylene-ethylene-propylene-styrene (SEEPS) block copolymer. As commercially available copolymers of styrene monomers and diene monomers, for example, SEPTON (registered trademark, manufactured by Kuraray Co., Ltd.) and Tuftec (registered trademark, manufactured by Asahi Kasei Co., Ltd.) can be used.

[0072] The copolymer of a styrene-based monomer and a diene-based monomer in the resin layer (a) may be a single type of copolymer, or may contain two or more types of copolymers.

[0073] The total content of the copolymer of a styrene-based monomer and a diene-based monomer and the compound having a cyclic ether structure contained in the resin layer (a) is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, when the total content of all components in the resin layer (a) is 100% by mass, and may be, for example, 99% by mass or less, or 98% by mass or less.

[0074] The resin layer (a) may contain, in addition to the resin component, components such as a curing agent and a surfactant as appropriate.

[0075] When the total content of all components in the resin layer (a) is taken as 100 mass%, the content of the (meth)acrylic resin in the resin layer (a) is preferably less than 50 mass%, more preferably less than 30 mass%, even more preferably less than 10 mass%, even more preferably less than 5 mass%, even more preferably less than 1 mass%, even more preferably less than 0.1 mass%, and even more preferably 0 mass%, from the viewpoint of further improving the heat resistance of the resin layer (a). Here, the (meth)acrylic resin is a concept that includes both methacrylic resin and acrylic resin.

[0076] When the complex viscosity of the resin layer (a) is measured by a melt viscoelasticity test under the conditions of a measurement frequency of 10 rad / sec, a temperature range of 23° C. to 200° C., and a temperature rise rate of 3° C. / min, the complex viscosity η* at 100° C. is preferably 1.0×10 3 Pa s or more, preferably 2.0×10 3 Pa s or more, more preferably 3.0×10 3 Pa s or more, more preferably 4.0×10 3 Pa s or more, more preferably 5.0×10 3 From the viewpoint of further improving embeddability, it is preferably 1.0×10 7 Pa s or less, preferably 1.0×10 6 Pa s or less, more preferably 5.0×10 5 Pa s or less, more preferably 1.0×10 5Pa s or less, more preferably 9.5×10 4 Pa s or less, more preferably 9.3×10 4 Pa s or less, more preferably 9.0×10 4 Pa s or less, more preferably 8.8×10 4 It is less than Pa·s.

[0077] When the complex viscosity of the resin layer (a) is measured by a melt viscoelasticity test under conditions of a measurement frequency of 10 rad / sec, a temperature range of 23°C to 200°C, and a heating rate of 3°C / min, the temperature at which the complex viscosity η* is minimum is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher, and from the viewpoint of further improving embeddability, is preferably 180°C or lower, more preferably 170°C or lower, even more preferably 160°C or lower, and even more preferably 140°C or lower.

[0078] The complex viscosity η* of the resin layer (a) can be adjusted to a desired numerical range by, for example, adjusting the type of resin constituting the resin layer (a), the weight average molecular weight (Mw) and the glass transition temperature, the content ratio of the components constituting the resin layer (a), etc. More specifically, the complex viscosity η* can be adjusted to a desired numerical range by, for example, including a polyimide resin and a compound having a cyclic ether structure in the resin layer (a).

[0079] The resin film of the present embodiment preferably further includes a base film, and more preferably includes a resin layer (a) provided on the base film. The base film may be, for example, a resin film. The resin constituting the base film is not particularly limited, but preferably contains at least one or more types selected from the group consisting of polyimide and polyethylene terephthalate, and more preferably contains polyethylene terephthalate.

[0080] From the viewpoint of further improving the handleability of the film, the thickness of the base film in this embodiment is preferably 10 μm or more, more preferably 15 μm or more, even more preferably 20 μm or more, preferably 30 μm or more, and is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 60 μm or less, even more preferably 40 μm or less.

[0081] The substrate film of the present embodiment may be subjected to a surface treatment such as an antistatic treatment or a release treatment.

[0082] The resin film of this embodiment can be obtained, for example, by applying a resin composition for forming the first clad layer onto a substrate film, drying it, and forming a resin layer (a). When applying the resin composition for forming the first clad layer onto the substrate film, the resin composition is preferably a varnish-like resin composition containing an organic solvent. The organic solvent in the resin composition is removed in the drying process. Examples of the coating method include direct coating methods using various coater devices such as a pin coater, a die coater, a comma coater, and a curtain coater, and printing methods such as screen printing.

[0083] 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

[0084] 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.

[0085] [Creating resin film] The preparation of a resin film having a resin layer (a) made of a resin composition for forming a first clad layer will be described. First, the respective raw materials constituting the resin composition for forming the first cladding layer will be described.

[0086] (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 glass separable 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.

[0087] 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.

[0088] 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.

[0089] Details of the raw materials in Table 1 are as follows:

[0090] <Polymer (A)> (A-1) Polyimide resin synthesized above (Mw = 51,000, imidization rate 99% or more, refractive index n = 1.54) (A-2) Rubber-based elastomer (manufactured by Kuraray Co., Ltd., product name: Septon Q1250, copolymer of styrene-based monomer and diene-based monomer, Mw=100,000, refractive index n=1.50)

[0091] [ka]

[0092] <Compound (B) Having a Cyclic Ether Structure> (B-1) Celloxide 2021P (manufactured by Daicel Corporation, epoxy resin with an alicyclic structure, liquid at 23°C, refractive index 1.51)

[0093] <Hardening agent (C)> (C-1) San-Aid SI-110 (manufactured by Sanshin Chemical Industry Co., Ltd., thermal cationic polymerization initiator) (C-2) San-Aid SI-150 (manufactured by Sanshin Chemical Industry Co., Ltd., thermal cationic polymerization initiator) (C-3) San-Aid SI-B3 (manufactured by Sanshin Chemical Industry Co., Ltd., thermal cationic polymerization initiator)

[0094] <Surfactant (D)> (D-1) BYK-333 (BYK Japan Co., Ltd., silicone surfactant) (D-2) BYK-361 (BYK Japan Co., Ltd., acrylic polymer surfactant)

[0095] <Organic solvent (E)> (E-1) Propylene glycol monomethyl ether acetate (E-2) Propylene glycol monomethyl ether (E-3) Toluene

[0096] <Preparation of resin composition> The raw materials mixed according to Table 1 were stirred at room temperature until the raw materials were completely dissolved to obtain a solution. The solution was then filtered through a PTFE filter with a pore size of 0.2 μm to obtain varnish-like resin compositions of clad A and clad B, respectively.

[0097] <Creating resin film> The varnish-like resin compositions of Clad A and Clad B obtained by preparing the above resin composition were applied 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) 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 resin layer formed by the resin composition to obtain a resin film. In addition, for the resin film having a thickness of 25 μm as the resin layer (a) in Table 2, the resin film obtained by the above method was used as it was. Resin films in Table 2 having a resin layer (a) thickness greater than 25 μm were prepared by laminating resin films having a resin layer (a) thickness of 25 μm in a laminator under conditions of temperature: 30°C, pressure: 1.0 MPa, and time: 120 seconds until the specified resin layer (a) thickness was reached.

[0098] [Examples 1 to 10 and Comparative Examples 1 to 3] <Work preparation process (A)> The OPP cover film was peeled off from the resin film, and the double-sided copper-clad laminate (CCL) with through holes was placed in contact with the resin layer (a) of the resin film to prepare a workpiece in which the resin film was placed on the double-sided copper-clad laminate. The layer structure of the workpiece was "double-sided copper-clad laminate / resin layer (a) / PET substrate". The type of clad material of the resin film and the thickness of the resin layer (a) are shown in Table 2. The thickness T of the double-sided copper-clad laminate, the hole diameter R of the through hole, and T / R are also shown in Table 2.

[0099] <Laminating process (B)> Based on the conditions described in step (B) of Table 2, the work was pressed to laminate the resin layer (a) onto the double-sided copper-clad laminate. The "rubber" listed in the laminating device in Table 2 means that the work was pressed using the 1st stage of a rubber press laminator (manufactured by Nikko Materials Co., Ltd., product name: CVP-600). The "diaphragm" listed for the laminating device in Table 2 means that the workpiece was pressed using the 1st stage of a diaphragm-type laminator (manufactured by Nikko Materials Co., Ltd., product name: CVP-300).

[0100] <Pressing process (C)> After step (B), the work was further pressed under normal pressure conditions based on the conditions described in step (C) in Table 2 to obtain the laminates of Examples 1 to 10 and Comparative Examples 1 to 3, respectively. In the examples and comparative examples in which the laminating device in step (B) in Table 2 was "rubber," the workpiece was pressed using the 2nd stage of a rubber press laminator (manufactured by Nikko Materials Co., Ltd., product name: CVP-600). In the examples in which the laminating device in step (B) in Table 2 was "diaphragm," the workpiece was pressed using the 2nd stage of a diaphragm-type laminator (manufactured by Nikko Materials Co., Ltd., product name: CVP-300).

[0101] [Measurement and Evaluation] <Measurement of complex viscosity η* of resin layer (a)> A resin film having a resin layer (a) of 25 μm in thickness was laminated with a laminator under the conditions of temperature: 30° C., pressure: 1.0 MPa, and time: 120 seconds so that the resin layer (a) had a thickness of 100 μm to obtain a sample for complex viscosity measurement. More specifically, two films were laminated to produce two films having a resin layer thickness of 50 μm, and then the two films having a resin layer thickness of 50 μm were laminated to obtain a sample having a resin layer thickness of 100 μm. When obtaining the sample for complex viscosity measurement, the PET substrate and OPP cover film were appropriately removed. The melt viscoelasticity of the sample for complex viscosity measurement was measured using a viscoelasticity measuring device (Anton Paar Japan, product name: MCH302) at a frequency of 10 rad / sec, while changing the temperature from 23°C to 200°C at a heating rate of 3°C / min. From the results obtained, the complex viscosity η* [Pa s] at 100°C at 10 rad / sec and the temperature [°C] at which the complex viscosity η* at a frequency of 10 rad / sec is minimum were calculated. The measurement results of the complex viscosity η* are shown in Table 1.

[0102] <Embeddability evaluation> For the laminates of Examples 1 to 10 and Comparative Examples 1 to 3, the through holes in the substrate were observed under a microscope and evaluated according to the following criteria. A (Very good): The filling is completed without any voids. B (Good): Some voids are present but are filled. C (Poor): The filling was not completed. The results of the embeddability evaluation are shown in Table 2.

[0103] [Table 1]

[0104] [Table 2]

[0105] It can be seen from Table 2 that the embeddability evaluation was good for all the laminates obtained by the manufacturing methods of the examples. That is, according to the manufacturing method of the laminate of the present embodiment, a laminate that can produce an optoelectronic composite substrate with improved embeddability can be obtained.

[0106] This application claims priority based on Japanese Patent Application No. 2023-057399, filed on March 31, 2023, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0107] 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 140a, 140b through hole 200 Photoelectric composite board 300 Resin Film 310 Resin layer (a) 320 Base film 400 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 on which a resin film having a resin layer (a) made of a resin composition for forming the first clad layer is placed on the substrate; and (B) laminating the first clad layer onto the substrate by heating and pressing the workpiece under reduced pressure using a vacuum laminating device; The resin layer (a) has a complex viscosity η* at 100°C of 1.0 x 103 Pa·s or more and 1.0 x 107 Pa·s or less when the complex viscosity is measured by a melt viscoelasticity test under the conditions of a measurement frequency of 10 rad / sec, a temperature range of 23°C to 200°C, and a heating rate of 3°C / min.

2. 2. 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.

3. 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.

4. 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.

5. The method for producing a laminate according to claim 1 or 2, wherein the resin layer (a) has a thickness of 10 μm or more and 300 μm or less.

6. The method for producing a laminate according to claim 1 or 2, wherein a thickness of the resin layer (a) is smaller than a thickness of the substrate.

7. 3. The method for producing a laminate according to claim 1, wherein the resin layer (a) contains at least one selected from the group consisting of a polyimide resin, a compound having a cyclic ether structure, and a copolymer of a styrene-based monomer and a diene-based monomer.

8. The method for producing a laminate according to claim 1 or 2, wherein in the step (B), the work is heated to 80° C. or more and 190° C. or less and pressed.

9. 3. The method for producing a laminate according to claim 1, wherein in the step (B), the work is sandwiched between two press plates, and the work is heated and pressed.

10. The method for producing a laminate according to claim 9 , wherein in step (B), at least one of the two press plates contains rubber.

11. The method for producing a laminate according to claim 1 or 2, wherein the degree of vacuum in the step (B) is 500 Pa or less.

12. 3. The method for producing a laminate according to claim 1, wherein in the step (B), the work is pressed at a pressure of 0.3 MPa or more and 10.0 MPa or less.

13. 3. The method for producing a laminate according to claim 1, further comprising, after the step (B), a step (C) of sandwiching the workpiece between two press plates and heating and pressing the workpiece.

14. 3. The method for producing a laminate according to claim 1, wherein, when the volume of the through hole 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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