Laminate for photoelectric fusion substrates, and photoelectric fusion substrates

Abstract

To provide a laminate for photoelectric fusion substrates that can fuse optical waveguides while reducing degradation of the electronic substrate, and that offers excellent heat resistance, adhesion, and productivity. [Solution] The device comprises, in this order: a core layer made of a heat-resistant resin with an average thickness of 1 μm to 10 μm and a refractive index n1 at a wavelength of 1310 nm or 1550 nm; an underclad layer made of a heat-resistant resin with an average thickness of 5 μm to 25 μm and a refractive index n2 at a wavelength of 1310 nm or 1550 nm; and an insulating adhesive layer made of a thermosetting resin composition with an average thickness of 10 μm to 200 μm, wherein the volume resistivity of the insulating adhesive layer after curing is 10 8 The laminate for photoelectric fusion substrates has a refractive index of Ω·cm or more, and the refractive indices n1 and n2 satisfy the following relationship: 0.1 < 100 × (n1 - n2) / n1 < 5.

Description

[Technical Field]

[0001] This disclosure relates to a laminate for photoelectric fusion substrates and to photoelectric fusion substrates. [Background technology]

[0002] To realize next-generation optoelectronic integration technology, optoelectronic integration substrates are being developed that integrate optical waveguides, which enable high-speed transmission, high-capacity communication, and low power consumption, with electronic substrates such as semiconductor substrates. For this to work, it is important to perform the lamination of optical waveguides and electronic substrates, the formation of electrical wiring, and the lamination and optical bonding of optical waveguides and / or photoelectric conversion elements with high precision, and for example, heat resistance is required.

[0003] To date, fluorinated polyimides have been known to be useful as core materials due to their low transmission loss at wavelengths of 1310 nm or 1550 nm and their high heat resistance. Specifically, with the aim of providing a plastic material for optical communications that has heat resistance and low optical loss across the entire optical communication wavelength range of 1.0 to 1.7 μm, for example, a fully fluorinated polyimide having repeating units imidized with a fully fluorinated acid anhydride, 1,4-bis(3,4-dicarboxytrifluorophenoxy)tetrafluorobenzene dianhydride (10FDEA), and a fully fluorinated diamine has been reported (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-001148 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The present disclosure aims to provide a laminate for photoelectric fusion substrates that can fuse optical waveguides while reducing degradation of the electronic substrate, and that is excellent in heat resistance, adhesion, and productivity. [Means for solving the problem]

[0006] <1> A core layer made of a heat-resistant resin with an average thickness of 1 μm to 10 μm and a refractive index n1 at a wavelength of 1310 nm or 1550 nm, An undercladding layer made of a heat-resistant resin with an average thickness of 5 μm to 25 μm and a refractive index n2 at a wavelength of 1310 nm or 1550 nm, An insulating adhesive layer having an average thickness of 10 μm to 200 μm and made of a thermosetting resin composition, It has them in this order, The volume resistivity of the insulating adhesive layer after curing is 10 8 It is greater than Ω·cm, A laminate for photoelectric fusion substrates characterized in that the refractive indices n1 and n2 satisfy the following relationship: 0.1 < 100 × (n1 - n2) / n1 < 5. <2> The underclad layer and the insulating adhesive layer further comprise a heat-resistant resin layer made of a heat-resistant resin having an average thickness of 15 μm or more and a glass transition temperature of 150°C or higher. <1> A laminate for photoelectric fusion substrates as described above. <3> The heat-resistant resin layer is made of polyimide resin. <2> A laminate for photoelectric fusion substrates as described above. <4> The core layer has an optical waveguide circuit pattern with a core diameter of 1 μm or more and 10 μm or less. <1> from <3> A laminate for photoelectric fusion substrates as described in any one of the items. <5> The transmission loss of the core layer is 0.2 dB / cm or less. <1> from <4> A laminate for photoelectric fusion substrates as described in any one of the items. <6> The coefficient of linear expansion of the undercladding layer is 80 ppm / K or less. <1> from <5> A laminate for photoelectric fusion substrates as described in any one of the items. <7> The thermosetting resin composition contains one or more selected from the group consisting of epoxy resins, epoxy / phenol resins, epoxy / cyanate resins, and epoxy / active ester resins. <1> from <6> A laminate for photoelectric fusion substrates as described in any one of the items. <8>The core layer is made of a first polyimide having a structural unit represented by the following general formula (1). The laminate for an optoelectronic integration substrate according to any one of <1> to <7>, wherein the underclad layer is made of a second polyimide having a structural unit represented by the following general formula (1).

Chemical formula

Chemical formula

Chemical formula

[0007] According to this disclosure, it is possible to provide a laminate for photoelectric fusion substrates that can fuse optical waveguides while reducing the degradation of the electronic substrate, and that is excellent in heat resistance, adhesion, and productivity. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a cross-sectional view showing an example of a laminate for a photoelectric fusion substrate according to the first embodiment. [Figure 2] Figure 2 is a cross-sectional view showing another example of a laminate for a photoelectric fusion substrate according to the first embodiment. [Figure 3] Figure 3 is a cross-sectional view showing an example of a laminate for a photoelectric fusion substrate according to the second embodiment. [Figure 4] Figure 4 is a cross-sectional view showing another example of a laminate for a photoelectric fusion substrate according to the second embodiment. [Figure 5] Figure 5 is a cross-sectional view showing an example of a photoelectric fusion substrate according to the first embodiment. [Figure 6] Figure 6 is a cross-sectional view showing another example of a photoelectric fusion substrate according to the first embodiment. [Figure 7] Figure 7 is a cross-sectional view showing an example of a photoelectric fusion substrate according to the second embodiment. [Figure 8] Figure 8 is a cross-sectional view showing another example of a photoelectric fusion substrate according to the second embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of this disclosure will be described with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions will be omitted.

[0010] (Laminate for photoelectric fusion substrates) The laminate for photoelectric fusion substrates of the present disclosure comprises a core layer, an underclad layer, and an insulating adhesive layer, and in one embodiment further comprises a heat-resistant resin layer, and may further comprise other layers such as a protective layer as needed.

[0011] The core layer has an average thickness of 1 μm to 10 μm and is made of a heat-resistant resin with a refractive index n1 at a wavelength of 1310 nm or 1550 nm. The underclad layer has an average thickness of 5 μm to 25 μm and is made of a heat-resistant resin with a refractive index n2 at a wavelength of 1310 nm or 1550 nm. The insulating adhesive layer has an average thickness of 10 μm to 200 μm and is made of a thermosetting resin composition. Here, the volume resistivity of the insulating adhesive layer after curing is 10 8 The refractive index is greater than or equal to Ω·cm, and the refractive indices n1 and n2 satisfy the following relationship: 0.1 < 100 × (n1 - n2) / n1 < 5.

[0012] When manufacturing an optical waveguide consisting of a core and cladding using the heat-resistant polyimide resin described in Patent Document 1, it is generally manufactured by layer coating. Specifically, first, a polyimide precursor for the undercladding is applied and then converted to polyimide by heating to form the undercladding layer. Next, a polyimide precursor for the core is applied and then converted to polyimide by heating to form the core layer. Furthermore, if necessary, the core layer is patterned and an overcladding layer is formed. However, when considering forming such an optical waveguide on an electronic substrate and fusing it with the substrate, although polyimide itself has excellent heat resistance, the heating temperature required for imidization is high, at over 300°C, which causes thermal damage to the electronic substrate and degrades the substrate. In particular, when incorporated into the process of electronic substrates that are multilayered by lamination or pressing of films, productivity is reduced, and there is also a problem that the optical properties may be impaired depending on the variation in the formation conditions of the core layer. On the other hand, when considering the use of photosensitive polyimide precursors, the resulting polyimide exhibits inferior heat resistance and transparency compared to thermosetting polyimide precursors, making it particularly difficult to ensure the transparency required for the core layer.

[0013] The present invention is based on the identification of the problems of the prior art described above. The inventors have conducted extensive research to solve the problems of the prior art and the aforementioned issues, and have found a solution comprising: a core layer made of a heat-resistant resin with an average thickness of 1 μm to 10 μm and a refractive index n1 at a wavelength of 1310 nm or 1550 nm; an underclad layer made of a heat-resistant resin with an average thickness of 5 μm to 25 μm and a refractive index n2 at a wavelength of 1310 nm or 1550 nm; and an insulating adhesive layer made of a thermosetting resin composition with an average thickness of 10 μm to 200 μm, in this order, wherein the volume resistivity of the insulating adhesive layer after curing is 10 8 We have discovered that by using a laminate for photoelectric fusion substrates with a refractive index of Ω·cm or higher and refractive indices n1 and n2 satisfying the relationship: 0.1 < 100 × (n1 - n2) / n1 < 5, it is possible to fuse optical waveguides while reducing the degradation of the electronic substrate, and we can provide a laminate for photoelectric fusion substrates that is excellent in heat resistance, adhesion, and productivity, thus completing the present invention.

[0014] The laminate for photoelectric fusion substrates disclosed herein provides a laminate that ensures the optical performance of the optical waveguide and improves productivity on the optical waveguide side when manufacturing the photoelectric fusion substrate, as the core layer and underclad layer are already cured and have excellent heat resistance and are pre-formed. Furthermore, by incorporating an insulating adhesive layer, it can be easily fused with the electronic substrate via the insulating adhesive layer, resulting in excellent adhesion. In addition, there is no need to perform heat curing to form the core layer and underclad layer, which reduces the degradation of the electronic substrate and improves productivity on the electronic substrate side when manufacturing the photoelectric fusion substrate. Therefore, it is possible to fuse optical waveguides while reducing the degradation of the electronic substrate, and to provide a laminate for photoelectric fusion substrates that is excellent in heat resistance, adhesion, and productivity.

[0015] [Laminate for photoelectric fusion substrate according to the first embodiment] The laminate for the photoelectric fusion substrate according to the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a cross-sectional view showing an example of the laminate for the photoelectric fusion substrate according to the first embodiment, and Figure 2 is a cross-sectional view showing another example of the laminate for the photoelectric fusion substrate according to the first embodiment.

[0016] The laminate 100 for photoelectric fusion substrate shown in Figure 1 has a core layer 10, an underclad layer 21, and an insulating adhesive layer 30, and further comprises the underclad layer 21, the core layer 10 disposed to cover at least a portion of the first surface of the underclad layer 21, and the insulating adhesive layer 30 disposed to cover at least a portion of the second surface of the underclad layer 21.

[0017] The laminate 110 for photoelectric fusion substrate shown in Figure 2 is an embodiment of the laminate 100 for photoelectric fusion substrate shown in Figure 1, further comprising a heat-resistant resin layer 40 between the underclad layer 21 and the insulating adhesive layer 30, and having a heat-resistant resin layer 40, an underclad layer 21 disposed to cover at least a portion of the first surface of the heat-resistant resin layer 40, a core layer 10 disposed to cover at least a portion of the first surface of the underclad layer 21, and an insulating adhesive layer 30 disposed to cover at least a portion of the second surface of the heat-resistant resin layer 40.

[0018] <Core layer and underclad layer> The core layer 10 is a layer made of heat-resistant resin, with an average thickness of 1 μm to 10 μm, and a refractive index n1 at a wavelength of 1310 nm or 1550 nm. The underclad layer 21 is a layer made of heat-resistant resin, with an average thickness of 5 μm to 25 μm, and a refractive index n2 at a wavelength of 1310 nm or 1550 nm.

[0019] The average thickness of the core layer 10 can be appropriately selected according to the desired embodiment and the characteristics of the optical waveguide, and may be 1 μm or more and less than 3 μm, or 3 μm or more and 10 μm or less.

[0020] The average thickness of the underclad layer 21 can be appropriately selected according to the desired configuration and the characteristics of the optical waveguide, as long as it is between 5 μm and 25 μm. However, a thickness of 10 μm to 25 μm is preferred in terms of obtaining sufficient mechanical properties as a cladding layer and ease of processing when forming conductive parts with the electronic substrate.

[0021] The heat-resistant resins for the core layer 10 and the underclad layer 21 are not particularly limited as long as they are combinations of heat-resistant resins whose refractive indices n1 and n2 satisfy the following relationship: 0.1 < 100 × (n1 - n2) / n1 < 5, and can be appropriately selected according to the purpose. For the numerical value 100 × (n1 - n2) / n1, under single-mode (SM) conditions, with a core diameter of 1 μm to 10 μm and a wavelength of 1.3 μm, a value of 0.15 to 4.0 is preferred, a value of 0.20 to 1.0 is more preferred, and a value of 0.25 to 0.8 is even more preferred. The heat-resistant resins for each layer may be used individually or in combination of two or more types.

[0022] Examples of heat-resistant resins include aromatic ring-condensed resins such as polyimide resin, polyamide-imide, and polybenzoxazole (PBO); polyphenylsulfone, polysulfone, polyarylate, polyetherimide, polyethernitrile, and epoxy resin. Among these, aromatic ring-condensed resins such as polyimide resin and polybenzoxazole are preferred, and polyimide resin is preferred, due to their low coefficient of thermal expansion, excellent transparency, and strength. The higher of the glass transition temperature or melting point of the heat-resistant resin is preferably 150°C or higher, more preferably 200°C or higher, even more preferably 250°C or higher, and particularly preferably 300°C or higher, from the viewpoint of heat resistance of the core layer 10 and the undercladding layer 21.

[0023] -Refractive index- The refractive index of the core layer 10 at wavelengths of 1310 nm or 1550 nm is preferably 1.500 or more and 1.650 or less, more preferably 1.640 or less, and even more preferably 1.630 or less, 1.625 or less, and 1.620 or less. The refractive index of the underclad layer 21 at wavelengths of 1310 nm or 1550 nm is preferably 1.450 or more and 1.649 or less, and more preferably 1.625 or less, 1.620 or less, or 1.610 or less.

[0024] The refractive index may be a measured value obtained by a refractometer, or it may be a calculated value obtained from the structural formula of the resin used. The following procedure is a specific method for calculating the refractive index at a particular wavelength from the structural formula of polyimide. If the chemical structure of the polymer can be determined, the refractive index of the polymer (as amorphous material) can be calculated semi-empirically using the group contribution method (Reference 1: DW van Krevelen, et al., "Properties of Polymers", Fourth Edition (2009)). The Lorentz-Lorentz equation, proposed in 1880, was used as the calculation formula for the group contribution method (Reference 2: Lorentz HA, Wied Ann Phys 9 (1880) 641).

[0025] -Glass transition temperature- The glass transition temperature of the core layer 10 is preferably 150°C or higher, more preferably 200°C or higher, even more preferably 250°C or higher, preferably 500°C or lower, more preferably 250°C to 450°C, and even more preferably 300°C to 400°C. The glass transition temperature of the underclad layer 21 is preferably 200°C to 400°C, more preferably 250°C to 400°C, and even more preferably 300°C to 400°C. If the glass transition temperature is 150°C or higher, a low refractive index material with good solder heat resistance and dimensional stability can be obtained.

[0026] -Transmission Loss- The transmission loss of the core layer 10 is preferably 0.3 dB / cm or less, and more preferably 0.2 dB / cm or less, under the conditions of a wavelength of 1310 nm or 1550 nm.

[0027] -Hayes- The haze of the heat-resistant resin is preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. When the haze is 20% or less, transparency is obtained when used in the core layer, cladding layer, and optical waveguide, making it suitable for use.

[0028] -Coefficient of linear thermal expansion- The coefficient of linear expansion refers to the ratio of the amount of deformation ΔL per 1 Kelvin (1°C) change in temperature to the original length L. The coefficient of linear expansion of the core layer 10 is preferably 80 ppm / K or less, more preferably 70 ppm / K or less, even more preferably 60 ppm / K or less, and particularly preferably 40 ppm / K or less. The coefficient of thermal expansion of the underclad layer 21 is preferably 80 ppm / K or less, more preferably 70 ppm / K or less, even more preferably 60 ppm / K or less, and particularly preferably 40 ppm / K or less.

[0029] If the coefficient of thermal expansion is too high, the difference in coefficient of thermal expansion between the substrate (or temporary substrate) and the laminate becomes large during the manufacturing process, causing warping and reducing yield. Furthermore, when the insulating adhesive layer is subjected to high temperatures during lamination or solder reflow processes, warping of the laminate itself or delamination of the interfaces between layers can occur, which is undesirable.

[0030] Specifically, the coefficient of linear expansion when the heat-resistant resin is polyimide can be measured using a thermomechanical analyzer (EXSTAR6000TMA / SS6000, manufactured by SII Nanotechnology Co., Ltd.) on a polyimide film obtained by the polyimide film manufacturing method described later, under the following measurement conditions. --Measurement Conditions-- Stage 1: Heat the sample to 150°C at a rate of 5°C / min to remove adsorbed water. Stage 2: Cool to room temperature by air at a cooling rate of 5°C / minute. Stage 3: Perform the measurement at a heating rate of 5°C / minute. The average value of the linear expansion coefficient in the temperature range of 30°C to 200°C during this measurement is determined and used as the linear expansion coefficient of the target polyimide film.

[0031] When the heat-resistant resin is polyimide, the haze can be specifically measured using a spectroscopic haze meter (HSP-150Vis, manufactured by Murakami Color Technology Laboratory Co., Ltd.) on a polyimide film obtained by the polyimide film manufacturing method described later. The average thickness of the polyimide film used as the measurement sample is preferably 5 μm to 80 μm.

[0032] -Elongation at break- The elongation at break of the polyimide is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more. When the break elongation is 20% or more, tearing during film transport is less likely to occur in the polyimide film manufacturing process, thus maintaining good productivity. Furthermore, bending resistance is maintained when it is made into a flexible printed circuit board, making cracking and wiring breakage less likely during the mounting process.

[0033] -Tensile modulus- The tensile modulus of the heat-resistant resin is preferably 0.5 GPa or higher, more preferably 1 GPa or higher, and even more preferably 2 GPa or higher. When the tensile modulus is 2 GPa or higher, the amount of elongation of the film when tension is applied during film transport in the film manufacturing process is suppressed, and dimensional stability is maintained.

[0034] When the heat-resistant resin is polyimide, the elongation at break and tensile modulus can be measured using a Tensilon universal material tester (RTM-100, manufactured by Orientec Co., Ltd.) in accordance with Japanese Industrial Standards (JIS K 7127:1999). This is done using a sample cut into strips 10 mm wide and 80 mm long from a polyimide film obtained by the polyimide film manufacturing method described later. The width of the sample to be measured is 10 mm, the chuck spacing is 50 mm, the test speed is 50 mm / minute, and the average value is calculated with n=10 measurements.

[0035] <Insulating adhesive layer> The insulating adhesive layer 30 is a layer made of a thermosetting resin composition, with an average thickness of 10 μm to 200 μm, and the volume resistivity of the insulating adhesive layer after curing is 10 8 The density is Ω·cm or greater. Here, the cured insulating adhesive layer is the cured product of the insulating adhesive layer 30 and can function as an insulating layer.

[0036] The average thickness of the insulating adhesive layer 30 can be appropriately selected depending on the desired embodiment, as long as it is between 10 μm and 200 μm. However, from the viewpoint of dielectric strength and processability, 10 μm to 200 μm is preferred, 15 μm to 100 μm is more preferred, 20 μm to 50 μm is even more preferred, and 30 μm to 40 μm is particularly preferred.

[0037] The thermosetting resin composition contains a thermosetting resin having insulating and adhesive properties, and may also contain an inorganic filler, and optionally other components such as a curing agent and a solvent. Furthermore, the insulating adhesive layer 30 is preferably in sheet form for ease of manufacture.

[0038] Examples of thermosetting resins include epoxy resins, epoxy / phenol resins, epoxy / cyanate resins, and epoxy / activated ester resins. These may be used individually or in combination of two or more. Among these, epoxy resins are preferred because they have high mechanical strength, heat resistance, and electrical insulation properties, as well as excellent water resistance, chemical resistance, and adhesion.

[0039] Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, phenol novolac type epoxy resin, tert-butyl-catechol type epoxy resin, naphthol type epoxy resin, naphthalene type epoxy resin, naphthylene ether type epoxy resin, glycidylamine type epoxy resin, glycidyl ester type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, anthracene type epoxy resin, linear aliphatic epoxy resin, epoxy resin having a butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, spiroring-containing epoxy resin, cyclohexanedimethanol type epoxy resin, trimethylol type epoxy resin, and halogenated epoxy resin.

[0040] Among these, bisphenol A type epoxy resin, bisphenol F type epoxy resin, naphthol type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, naphthylene ether type epoxy resin, glycidyl ester type epoxy resin, anthracene type epoxy resin, and epoxy resins having a butadiene structure are preferred due to their superior heat resistance and electrical insulation properties.

[0041] Examples of inorganic fillers include silica, barium sulfate, silicon dioxide, calcined talc, zinc molybdenum-treated talc, barium titanate, titanium dioxide, clay, alumina, mica, boehmite, zinc borate, zinc stannate, other metal oxides or metal hydrates, aluminum hydroxide, calcium carbonate, magnesium hydroxide, magnesium silicate, glass fibers, aluminum borate whiskers, and silicon carbonate whiskers. These may be used individually or in combination of two or more. Among these inorganic fillers, those with silica as the main component are preferred.

[0042] Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, hollow silica, and spherical silica. Among these, spherical silica and fused silica are preferred.

[0043] Regarding the median diameter of silica, from the viewpoint of electrical insulation and surface smoothness, it is preferably 2 μm or less, more preferably 1 μm or less, even more preferably 0.8 μm or less, and particularly preferably 0.6 μm or less. Furthermore, from the viewpoint of improving the dispersibility of silica, it is preferably 0.01 μm or more, more preferably 0.05 μm or more, and even more preferably 0.1 μm or more. The median diameter of silica can be measured by laser diffraction-scattering, based on Mie scattering theory. Specifically, it can be measured using a laser diffraction-scattering particle size distribution analyzer (e.g., LA-950, manufactured by Horiba, Ltd.).

[0044] When a thermosetting resin composition contains an inorganic filler, the inorganic filler content is preferably 30 parts by mass or more and 80 parts by mass or less per 100 parts by mass of resin. When the content is 30 parts by mass or more, a sufficient effect of reducing the coefficient of thermal expansion can be obtained. When the content is 80 parts by mass or less, sufficient moldability of the thermosetting resin composition can be obtained.

[0045] <Heat-resistant resin layer> The heat-resistant resin layer 40 is a layer made of a heat-resistant resin with a glass transition temperature of 150°C or higher, and has an average thickness of 15 μm or more and 150 μm or less. As for heat-resistant resins, there are no particular limitations as long as the glass transition temperature is 150°C or higher, and they can be appropriately selected according to the purpose. Examples include polyimide resins, aromatic ring-condensed resins such as polybenzoxazole (PBO); polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefin resins such as polyethylene, polypropylene, and polystyrene; and polycarbonate, polyether sulfide, polyether sulfone, polyether ketone, polyphenylene ether, polyphenylene sulfide, polyarylate, polysulfone, and liquid crystal polymers. These may be used individually or in combination of two or more. Among these, polyimide resins are preferred because they have a low coefficient of thermal expansion and excellent strength.

[0046] The coefficient of linear expansion of the heat-resistant resin layer 40 is preferably 80 ppm / K or less, more preferably 60 ppm / K or less, and even more preferably 40 ppm / K or less. The glass transition temperature of the heat-resistant resin layer 40 is 150°C or higher, preferably 200°C to 500°C, and more preferably 300°C to 400°C.

[0047] There are no particular limitations on the method for manufacturing the laminate for the photoelectric fusion substrate according to the first embodiment, and it can be appropriately selected depending on the purpose. Examples include (I) to (II) below. (I) A manufacturing method comprising the steps of: applying and drying a composition containing a heat-resistant resin precursor for an underclad layer onto a heat-resistant resin layer 40 or a temporary substrate, and then thermally curing the resulting coating to form an underclad layer 21; applying and drying a composition containing a heat-resistant resin precursor for a core layer onto the underclad layer 21, and then thermally curing the resulting coating to form a core layer 10; and, if necessary, peeling off the temporary substrate to form an insulating adhesive layer 30. (II) A manufacturing method comprising the steps of: applying and drying a composition containing a heat-resistant resin precursor for an underclad layer onto a heat-resistant resin layer 40 or a temporary substrate; applying and drying a composition containing a heat-resistant resin precursor for a core layer onto the obtained coating film; and thermally curing the obtained coating film to form an underclad layer 21 and a core layer 10; and, if necessary, peeling off the temporary substrate to form an insulating adhesive layer 30. Alternatively, a method of casting a composition containing a heat-resistant resin precursor onto a heated heat-resistant resin layer 40 or a temporary substrate and then heat-curing it can also be appropriately selected.

[0048] There are no particular restrictions on the temporary substrate, and it can be appropriately selected according to the purpose. Examples include glass substrates; metal substrates such as stainless steel drums, endless stainless steel belts, and aluminum foil.

[0049] [Laminate for photoelectric fusion substrate according to the second embodiment] Referring to Figures 3 and 4, a laminate for a photoelectric fusion substrate according to the second embodiment will be described. Figure 3 is a cross-sectional view showing an example of a laminate for a photoelectric fusion substrate according to the second embodiment, and Figure 4 is a cross-sectional view showing another example of a laminate for a photoelectric fusion substrate according to the second embodiment.

[0050] The laminate 200 for photoelectric substrates shown in Figure 3 is an embodiment of the laminate 100 for photoelectric substrates shown in Figure 1, in which an optical waveguide circuit pattern is formed on the core layer, and comprises an undercladding layer 21, a core layer 11 having an optical waveguide circuit pattern arranged to cover at least a portion of the first surface of the undercladding layer 21, and an insulating adhesive layer 30 arranged to cover at least a portion of the second surface of the undercladding layer 21.

[0051] The laminate 210 for photoelectric substrates shown in Figure 4 is an embodiment of the laminate 110 for photoelectric substrates shown in Figure 2, in which an optical waveguide circuit pattern is formed on the core layer, and comprises a heat-resistant resin layer 40, an underclad layer 21 disposed to cover at least a portion of the first surface of the heat-resistant resin layer 40, a core layer 11 having an optical waveguide circuit pattern disposed to cover at least a portion of the first surface of the underclad layer 21, and an insulating adhesive layer 30 disposed to cover at least a portion of the second surface of the heat-resistant resin layer 40.

[0052] There are no particular limitations on the method for manufacturing the laminate for the photoelectric fusion substrate according to the second embodiment, and it can be appropriately selected depending on the purpose. Specifically, in the method for manufacturing the laminate for the photoelectric fusion substrate according to the first embodiment, one method is to form an optical waveguide circuit pattern on the core layer 10 in a step prior to attaching the insulating adhesive layer 30.

[0053] The core layer 11 having an optical waveguide circuit pattern can be formed, for example, by patterning the core layer 10 in the laminate 100 for the photoelectric fusion substrate shown in Figure 1, and can be carried out by dry etching such as reactive ion etching (RIE). Specifically, a resist is applied to the core layer 10 formed on the underclad layer 21 and mask exposure is performed to form a patterned resist layer. Then, the parts of the core layer where the resist layer is not formed are dry etched and the resist layer is peeled off to form the core layer 11 having an optical waveguide circuit pattern. At this time, the underclad layer 21 may be provided on a heat-resistant resin layer 40 or a temporary substrate and pattern formation may be performed, or after pattern formation, it may be peeled off from the temporary substrate and an insulating adhesive layer 30 may be provided. Alternatively, a dry mask (such as a sputtered film of ZnO, CrO, etc.) may be formed between the resist layer and the core layer, and specifically, the dry mask may be patterned using the resist pattern as a mask, and the formed dry mask pattern may be used as a mask to perform dry etching and pattern the core layer.

[0054] The core diameter of the core layer 11 having an optical waveguide circuit pattern is 1 μm or more and 10 μm or less, and can be appropriately selected depending on the purpose. If the core diameter is 1 μm or more, the alignment tolerance can be increased when coupling with the light-emitting / receiving element or optical fiber after optical waveguide formation, and if the core diameter is 10 μm or less, the refractive index difference between the core and cladding in single mode can be increased, and bending loss can be reduced as an optical waveguide. Here, core diameter refers to the fiber diameter in the fibrous core layer, or the diameter of the fiber cross-section.

[0055] [Laminate for photoelectric fusion substrate according to the third embodiment] Referring to Figures 5 and 6, a laminate for a photoelectric fusion substrate according to the third embodiment will be described. Figure 5 is a cross-sectional view showing an example of a laminate for a photoelectric fusion substrate according to the third embodiment, and Figure 6 is a cross-sectional view showing another example of a laminate for a photoelectric fusion substrate according to the third embodiment.

[0056] The laminate 300 for photoelectric substrates shown in Figure 5 is an embodiment of the laminate 200 for photoelectric substrates shown in Figure 3, further comprising an overcladding layer 22, and includes an undercladding layer 21, a core layer 11 having an optical waveguide circuit pattern disposed to cover at least a portion of the first surface of the undercladding layer 21, an overcladding layer 22 covering the side surface of the core layer 11 having the optical waveguide circuit pattern together with the first surface of the undercladding layer 21, and an insulating adhesive layer 30 disposed to cover at least a portion of the second surface of the undercladding layer 21. Here, the undercladding layer 21 and the overcladding layer 22 form a cladding layer 20 that covers the side surface of the core layer 11 having the optical waveguide circuit pattern.

[0057] The laminate 210 for photoelectric fusion substrate shown in Figure 6 is an embodiment of the laminate 210 for photoelectric fusion substrate shown in Figure 4, further comprising an overclad layer 22, and includes a heat-resistant resin layer 40, an underclad layer 21 disposed to cover at least a portion of the first surface of the heat-resistant resin layer 40, a core layer 11 having an optical waveguide circuit pattern disposed to cover at least a portion of the first surface of the underclad layer 21, an overclad layer 22 that covers the side surface of the core layer 11 having the optical waveguide circuit pattern together with the first surface of the underclad layer 21, and an insulating adhesive layer 30 disposed to cover at least a portion of the second surface of the heat-resistant resin layer 40. Here, the underclad layer 21 and the overclad layer 22 form a clad layer 20 that covers the side surface of the core layer 11 having the optical waveguide circuit pattern.

[0058] <Overclad layer> The overcladding layer 22 is made of a cured product of a photosensitive resin composition and has a refractive index n3 at a wavelength of 1310 nm or 1550 nm. The photosensitive resin contained in the photosensitive resin composition may be a positive-type photosensitive resin whose solubility in the developer solution improves when exposed to energy rays such as ultraviolet light, allowing the exposed areas to be removed, or a negative-type photosensitive resin that hardens when exposed to energy rays, allowing the unexposed areas to be removed by the developer. Either type can be appropriately selected.

[0059] The cured product of the photosensitive resin composition of the overcladding layer 22 is not particularly limited as long as the refractive indices n1 and n3 are a combination of heat-resistant resins that satisfy the relationship: 0.1 < 100 × (n1 - n3) / n1 < 5, and can be appropriately selected according to the purpose. For the numerical value 100 × (n1 - n3) / n1, under single-mode (SM) conditions, with a core diameter of 1 μm or more and 10 μm or less and a wavelength of 1.3 μm, it is preferably 0.15 or more and 4.0 or less, more preferably 0.20 or more and 1.0 or less, and even more preferably 0.25 or more and 0.8 or less.

[0060] The cured product of the photosensitive resin composition of the overclad layer 22 may be the same or of the same type as the heat-resistant resin of the underclad layer 21, as long as it satisfies the above formula, or it may be different from each other. In addition, the refractive index difference between refractive indices n3 and n2 (|n3-n2|) may or may not be present, but |n3-n2| is preferably 0 or more and 0.10 or less, and more preferably 0 or more and 0.05 or less.

[0061] The average thickness of the overcladding layer 22 is sufficient to cover the sides of each fiber-shaped core of the core layer 11 having the optical waveguide circuit pattern, and is 2 μm to 35 μm greater than the core diameter, for example, 3 μm to 45 μm. The thickness of the overcladding layer 22 is the value from the boundary between the core layer 11 having the optical waveguide circuit pattern and the undercladding layer 21 to the upper surface of the overcladding layer 22.

[0062] The photosensitive resin composition contains a photosensitive resin, may also contain an inorganic filler, and may further contain other components such as a curing agent and a solvent as needed.

[0063] Examples of photosensitive resins include photosensitive polyimide resins, photosensitive acrylic resins, and photosensitive epoxy resins. These may be used individually or in combination of two or more types.

[0064] The overcladding layer 22 can be formed by applying a photosensitive resin composition to cover the side surface of the core layer 11 having an optical waveguide circuit pattern, together with the first surface of the undercladding layer 21, and curing the photosensitive resin composition by light irradiation.

[0065] [Laminate for photoelectric fusion substrate according to the fourth embodiment] Referring to Figures 7-8, the laminate for the photoelectric fusion substrate according to the fourth embodiment will be described. Figure 7 is a cross-sectional view showing an example of the laminate for the photoelectric fusion substrate according to the fourth embodiment, and Figure 8 is a cross-sectional view showing another example of the laminate for the photoelectric fusion substrate according to the fourth embodiment.

[0066] The laminate 400 for photoelectric fusion substrate shown in Figure 7 is an embodiment having an overclad layer 22, a core layer 11 having an optical waveguide circuit pattern, and an underclad layer 21, wherein the underclad layer 21 has an underclad layer 21, a core layer 11 having an optical waveguide circuit pattern arranged to cover at least a portion of the first surface of the underclad layer 21, and an overclad layer 22 that covers the side surface of the core layer 11 having the optical waveguide circuit pattern together with the first surface of the underclad layer 21.

[0067] The laminate 410 for photoelectric fusion substrate shown in Figure 8 is an embodiment of the laminate 400 for photoelectric fusion substrate shown in Figure 7, further having a heat-resistant resin layer 40 on the second surface side of the underclad layer 21, and comprises a heat-resistant resin layer 40, an underclad layer 21 disposed to cover at least a portion of the first surface of the heat-resistant resin layer 40, a core layer 11 having an optical waveguide circuit pattern disposed to cover at least a portion of the first surface of the underclad layer 21, and an overclad layer 22 that covers the side surface of the core layer 11 having an optical waveguide circuit pattern together with the first surface of the underclad layer 21.

[0068] There are no particular limitations on the method for manufacturing the laminate for the photoelectric fusion substrate according to the fourth embodiment, and it can be appropriately selected depending on the purpose. Specifically, it can be carried out in the same manner as the method for manufacturing the laminate for the photoelectric fusion substrate according to the second embodiment, except that the insulating adhesive layer 30 is not attached.

[0069] [An embodiment in which the core layer and underclad layer are polyimide] In the laminate for photoelectric fusion substrates and the photoelectric fusion substrate of this embodiment, in one embodiment, the heat-resistant resin of the core layer 10 and the underclad layer 21 is preferably an aromatic ring condensation resin such as polyimide resin or polybenzoxazole (PBO), more preferably a fluorine-substituted aromatic ring condensation resin, and even more preferably a fluorine-substituted polyimide resin, as these have a low coefficient of thermal expansion and excellent transparency and strength.

[0070] Among fluorine-substituted polyimide resins, a more preferable embodiment is one in which the core layer consists of a first polyimide having structural units represented by the following general formula (1), and the undercladding layer consists of a second polyimide having structural units represented by the following general formula (1). The general formula (1) is specified by the following formula: f clad >f core By having a combination of a first polyimide and a second polyimide that satisfy the above conditions, it is possible to achieve excellent transmission loss reduction, heat resistance, and low birefringence, and specifically, it can be applied as a laminate for optical waveguides suitable for single-mode optical wavelengths of 1310 nm and 1550 nm.

[0071] [ka] In the above general formula (1), R 1 This is a tetravalent group selected from the group consisting of the following:

[0072] [ka] In the above general formula (1), R 2 This is a divalent group selected from the group consisting of the following:

[0073] [ka]

[0074] In the above general formula (1), R f Each of the elements is independently either hydrogen or fluorine, each of the elements is independently either O, S, SO2, or C=O, and each of the elements is independently either O, S, SO2, or C=O. In the first polyimide, at least one R f It is hydrogen. In the first polyimide, R f The number of hydrogen atoms in N H , R f The number of fluorine atoms in N F , the fluorine substitution rate is f core =N F / (N H +N F ) and in the second polyimide, R f The number of hydrogen atoms in N H , R f The number of fluorine atoms in N F , the fluorine substitution rate is f clad =N F / (N H +N F When we set ) then the following equation: f clad >f core , satisfies.

[0075] Here, R f The fact that X and Y do not contain CF3, Cl, or Br has the advantage of reducing birefringence and thus reducing transmission loss.

[0076] In the first polyimide, R derived from the diamine 2 at least one R in f In one embodiment, it is preferable that the R is fluorine, and R is derived from an acid anhydride. 1 at least one R in fIn other embodiments, it is preferable that the substance is fluorine, and in further embodiments, it is preferable that both conditions are met.

[0077] In the second polyimide, R derived from the diamine 2 at least one R in f In one embodiment, it is preferable that the R is fluorine, and R is derived from an acid anhydride. 1 at least one R in f In other embodiments, it is preferable that the substance is fluorine, and in further embodiments, it is preferable that both conditions are met.

[0078] In the first polyimide represented by the general formula (1), or the second polyimide represented by the general formula (1), R derived from acid anhydride 1 As such, a tetravalent group represented by the following formula (1-1) is preferred, and a tetravalent group represented by the following formula (1-2), a tetravalent group represented by the following formula (1-3), etc. are more preferred. In the above general formula (1), R 1 It may be used alone, or two or more may be used in combination to form a copolymer, and in embodiments in which two or more are used in combination, it is preferable that it further has a tetravalent group represented by the following formula (1-4).

[0079] [ka]

[0080] In the above equation (1-1), R f Each of these is independently either hydrogen or fluorine, and each of these is independently either O or S. f The number of hydrogen atoms in N H , R f The number of fluorine atoms in N F When R is set to R 1 Fluorine substitution rate N F / (N H +N F ) is 0.2 or more and 0.9 or less, preferably 0.4 or more and 0.9 or less, more preferably 0.4 or more and 0.8 or less, and even more preferably 0.4 or more and 0.7 or less.

[0081] [ka]

[0082] In the above equation (1-2), R f X and the fluorine substitution rate can be appropriately selected from the items described in formula (1-1) above.

[0083] [ka]

[0084] In equation (1-3) above, X can be appropriately selected to describe the matters described in equation (1-1).

[0085] [ka]

[0086] In the above general formula (1), R 2 The divalent group can be selected as appropriate for the purpose, as long as it contains an aromatic ring in its main skeleton, without any particular restrictions, but it is preferable that it be a divalent group selected from the group consisting of the following.

[0087] As one embodiment, in the first polyimide represented by the general formula (1), or the second polyimide represented by the general formula (1), R 1 The group is selected from the following, R 2 It is preferable that the following group be selected.

[0088] [ka]

[0089] [ka]

[0090] Furthermore, in the first polyimide represented by the general formula (1), or the second polyimide represented by the general formula (1), R derived from diamine 2 As such, a divalent group represented by formula (2-1) is preferred, and a divalent group represented by formula (2-2), a divalent group represented by formula (1-3), a divalent group represented by formula (2-4), a divalent group represented by formula (2-5), a divalent group represented by formula (2-6), a divalent group represented by formula (2-7), and so on are more preferred. In the general formula (1), R 2 These may be used individually or in combination to form a copolymer.

[0091] [ka]

[0092] In the above equation (2-1), R f R is independently either hydrogen or fluorine, and Y is independently either O or S. f The number of hydrogen atoms in N H , R f The number of fluorine atoms in N F When R is set to R 1 Fluorine substitution rate N F / (N H +N F The ratio is 0.15 or more and 1.0 or less, preferably 0.3 or more and 1.0 or less, and more preferably 0.5 or more and 1.0 or less.

[0093] [ka]

[0094] In the above equation (2-2), R f The fluorine substitution rate and the matters described in formula (2-1) above can be appropriately selected.

[0095] [ka]

[0096]

Chem.

[0097] In the above formula (2-4), R f , and the fluorine substitution rate can be appropriately selected from the matters described for the above formula (2-1).

[0098]

Chem.

[0099] In the above formula (2-5), R f , and the fluorine substitution rate can be appropriately selected from the matters described for the above formula (2-1).

[0100]

Chem.

[0101] In the above formula (2-6), R f , and the fluorine substitution rate can be appropriately selected from the matters described for the above formula (2-1).

[0102]

Chem.

[0103] In the above formula (2-7), R f , and the fluorine substitution rate can be appropriately selected from the matters described for the above formula (2-1).

[0104] -Relationship with fluorine substitution rate- The fluorine substitution rate of the first polyimide is, in the first polyimide, when the number of hydrogen atoms in R f is N H , and the number of fluorine atoms in R f is N F , f core = N F / (N H + NF ) is defined as follows. The fluorine substitution rate of the second polyimide is, in the second polyimide, R f The number of hydrogen atoms in N H , R f The number of fluorine atoms in N F When that happens, f clad =N F / (N H +N F ) is defined as follows.

[0105] Here, the following equation: f clad >f core The transmission loss can be reduced by satisfying the above conditions, that is, by having a fluorine substitution rate of the second polyimide greater than the fluorine substitution rate of the first polyimide. f clad and f core The relationship is given by the following equation: 0.005≦f clad -f core It is preferable that the value <0.5 be satisfied.

[0106] The fluorine substitution rate f of the first polyimide core There are no particular restrictions on this, and it can be selected as appropriate depending on the purpose, but from the viewpoint of transparency of the core layer, a value of 0.50 or more and 0.97 or less is preferred, with a lower limit of 0.55 or more being more preferred, 0.60 or more being even more preferred, and 0.65 or more being particularly preferred, and an upper limit of 0.95 or less being more preferred, and 0.90 or less being even more preferred.

[0107] Furthermore, the number of modes in an optical waveguide can be predicted by calculation. For example, when the core diameter is 6 μm or more, it can be calculated using the following formula (1).

[0108]

number

[0109] For single-mode operation to be valid, the normalized frequency V ≤ 2.405. Specifically, by substituting the free-space wavelength λ = 1.31 [μm] or 1.55 [μm], the waveguide core radius a = 3 [μm], and the normalized frequency V = 2.405, the numerical aperture NA for a wavelength of 1.31 [μm] or 1.55 [μm] can be calculated. Then, according to equation (2) below, the refractive index n of the core layer is such that the numerical aperture NA is obtained. core , and the refractive index n of the cladding layer clad We can find the combinations.

[0110]

number

[0111] -Method for synthesizing polyimides- The term "polyimide" refers collectively to the first polyimide, the second polyimide, and other polyimide resins. There are no particular restrictions on the method of synthesizing the polyimide, and a known method can be appropriately selected depending on the purpose. For example, polyamic acid (polyamic acid), which is a precursor of polyimide, can be synthesized by polymerizing equimolar amounts of acid anhydride and diamine, and the resulting polyamic acid can be heated at a temperature of 200°C or higher, or an imidation (dehydration and cyclization) reaction can be carried out using a catalyst to obtain polyimide.

[0112] The acid anhydride and diamine corresponding to the polyimide represented by the general formula (1) are the acid anhydride represented by the following general formula (3) and the diamine represented by the following general formula (4). In the above general formula (3), R 1 This is R in the general formula (1) above. 1 It is synonymous with [the above]. In the above general formula (4), R 2 This is R in the general formula (1) above. 2 It is synonymous with [the above]. Alternatively, a tetracarboxylic acid corresponding to the acid anhydride may be used in place of, or in combination with, the acid anhydride.

[0113] [ka] [ka]

[0114] When multiple acid anhydrides and / or multiple diamines are used, the resulting polyamic acid and polyimide may be random copolymers, block copolymers, or mixtures thereof.

[0115] The polyamic acid and the composition containing the polyamic acid can be synthesized, for example, by the following procedure. A thermometer and a stirring rod with stirring blades are set in a 300 mL four-neck separable flask. Next, a solvent (e.g., dimethylacetamide, DMAC) is added under a stream of dry nitrogen and the temperature is raised to 60°C. After the temperature rises, the diamine is added while stirring and dissolved. Then, equimolar amounts of acid anhydride are added and stirred to polymerize the acid anhydride and diamine. After that, the mixture is cooled to room temperature, and if necessary, solvent is added and the mixture is filtered to obtain a composition containing polyamic acid.

[0116] The reaction temperature for polymerizing the acid anhydride and the diamine is preferably -20°C to 150°C, and more preferably 0°C to 100°C. The reaction time is preferably 0.1 hours to 168 hours, and more preferably 0.5 hours to 96 hours. It is also preferable that the number of moles of acid anhydride and the number of moles of diamine used in the reaction are equal. Polyamic acids in which the amounts of acid anhydride and diamine are close to equal tend to yield polyimide films with high mechanical properties.

[0117] For example, the following procedure can be used to synthesize the polyimide from the polyamic acid by an imidation reaction. The resulting polyamic acid-containing composition is applied to a substrate (e.g., by spin coating). Then, it is dried using a hot plate (e.g., at 70°C for 5 minutes). Subsequently, it can be heated at a temperature of 200°C or higher to form a film-like polyimide on the substrate. As an example of a method for heating to a temperature of 200°C or higher, one could use an oven and, under a nitrogen atmosphere (oxygen concentration of 20 ppm or less), raise the temperature from 50°C at a rate of 4°C / minute, heat at 180°C for 30 minutes, and then continue heating at 350°C for 30 minutes.

[0118] -Method for identifying polyimides- There are no particular limitations on the method for identifying the polyimide, and it can be appropriately selected depending on the purpose. For example, one method is to analyze it using the infrared total reflection attenuation method (IR-ATR method) with a Fourier transform infrared spectrometer (FT-IR) to identify its constituent components such as acid anhydrides and diamines. FT-IR measurements can be performed using, for example, a Nicolet 6700 (manufactured by Thermo Fisher Scientific Co., Ltd.).

[0119] (Optoelectronic fusion board) The photoelectric fusion substrate of the present disclosure comprises an electronic substrate and a laminate for the photoelectric fusion substrate of the present disclosure as described above, wherein the laminate for the photoelectric fusion substrate is fused to the electronic substrate. Furthermore, in another embodiment, the photoelectric fusion substrate comprises a photoelectric conversion element and / or an electro-optical conversion element and a laminate for the photoelectric fusion substrate described above, wherein the photoelectric conversion element and / or the electro-optical conversion element is fused with the laminate for the photoelectric fusion substrate.

[0120] One method for electrically joining a laminate for photoelectric integration substrates to an electronic substrate is to create through-holes in the planned joining area of ​​the laminate for photoelectric integration substrates, which will be placed at the joining portion of the electronic substrate, by laser processing, place it on the electronic substrate, and then form copper wiring by copper plating or the like to create through-holes.

[0121] As a method for forming an optical junction between a laminate for photoelectric fusion substrates and a photoelectric conversion element and / or an electro-optical conversion element, for example, when curing the overcladding layer, the area to be bonded is left unexposed, exposing a part of the core layer without forming the overcladding layer, the junction of the photoelectric conversion element and / or electro-optical conversion element is bonded to the exposed portion, and then sealed with underfill.

[0122] The photoelectric integration substrate disclosed herein has a laminate for photoelectric integration substrates in which a core layer and an underclad layer are already cured and have excellent heat resistance, thereby ensuring the optical performance of the optical waveguide and improving productivity on the optical waveguide side when manufacturing the photoelectric integration substrate. Furthermore, by combining it with an insulating adhesive layer, it can be easily fused with an electronic substrate via the insulating adhesive layer, resulting in excellent adhesion. In addition, when manufacturing the photoelectric integration substrate, there is no need to perform thermal curing to form the core layer and underclad layer, which reduces the degradation of the electronic substrate and improves productivity on the electronic substrate side. Therefore, it is possible to fuse optical waveguides while reducing the degradation of the electronic substrate, and a photoelectric integration substrate with excellent heat resistance, adhesion, and productivity can be provided. [Examples]

[0123] The present invention will be described more specifically below based on examples, but the present invention is not limited to the following examples.

[0124] <Example of synthesis of polyamic acid for core layer> A polyamic acid for the core layer satisfying the above general formula (1) was synthesized by the following procedure. 25 mol% of 1,4-bis(3,4-dicarboxytrifluorophenoxy)tetrafluorobenzene dianhydride (10FEDA), 25 mol% of benzene-1,2,4,5-tetracarboxylic acid dianhydride, 50 mol% of tetrafluoro-1,3-phenylenediamine (4FMPD), and the equivalent of 2500 mol% of N,N-dimethylacetamide (DMAc) were added to a flask. This solution was stirred at room temperature under a nitrogen atmosphere for 7 days to obtain polyamic acid for the core layer as a DMAc solution of partially fluorinated polyamic acid. The fluorine substitution rate of the polyamic acid for the core layer was 90%.

[0125] <Example of polyamic acid synthesis for undercladding layer> A polyamic acid for undercladding that satisfies the above general formula (1) was synthesized by the following procedure. 50 mol% of 1,4-bis(3,4-dicarboxytrifluorophenoxy)tetrafluorobenzene dianhydride (10FEDA), 50 mol% of tetrafluoro-1,3-phenylenediamine (4FMPD), and the equivalent of 2500 mol% of N,N-dimethylacetamide (DMAc) were added to a flask. This solution was stirred in a nitrogen atmosphere at room temperature for 7 days to obtain polyamic acid for the undercladding layer as a DMAc solution of total fluorinated polyamic acid.

[0126] (Example 1) <Manufacturing of laminate 1 for photoelectric fusion substrate> A laminate 1 for a photoelectric fusion substrate having the configuration shown in Figure 2 was manufactured by following the procedure below.

[0127] <<Formation of the undercladding layer>> A polyamic acid for the undercladding layer was spin-coated onto a polyimide film (Kapton® film, size: 100mm x 100mm, average thickness 25μm, manufactured by Toray DuPont Co., Ltd.) as a heat-resistant resin layer. The film was then heated under a nitrogen atmosphere at 70°C for 2 hours, 160°C for 1 hour, 250°C for 30 minutes, and 350°C for 1 hour to convert it to polyimide through imidation, forming an undercladding layer with an average thickness of 10μm.

[0128] <<Formation of the core layer>> Next, polyamic acid for the core layer was spin-coated onto the underclad layer, and heated under a nitrogen atmosphere at 70°C for 2 hours, 160°C for 1 hour, 250°C for 30 minutes, and 350°C for 1 hour to convert it to polyimide by imidization, forming a core layer with an average thickness of 5 μm.

[0129] <<Formation of an insulating adhesive layer>> Next, a build-up film (ABF film, average thickness 30 μm, manufactured by Ajinomoto Co., Inc.) was placed as an insulating adhesive layer on the surface of the underclad layer opposite to the core layer formation surface, and laminated by vacuum lamination to produce a laminate 1 for the photoelectric fusion substrate of Example 1 having the configuration shown in Figure 2.

[0130] <Rating> The glass transition temperature of the underclad layer, the refractive index of the core layer and underclad layer, and the coefficient of linear thermal expansion (CTE) of the underclad layer were measured and evaluated using the following procedure.

[0131] <<Measurement of glass transition temperature>> After preparing film samples, dynamic viscoelasticity was measured using a TA Instruments HR20 rheometer at 0.1% strain and 1 Hz from room temperature to 380°C at a rate of 2°C / min. The peak temperature of the obtained tanδ was defined as the glass transition temperature. The results are shown in Table 1.

[0132] <<Measurement of refractive index at a wavelength of 1550 nm>> Polyamic acid for the undercladding layer was spin-coated onto a silicon wafer, and a cladding film with an average thickness of approximately 8 μm was formed by imidization under a nitrogen atmosphere by heating at 70°C for 2 hours, 160°C for 1 hour, 250°C for 30 minutes, and 350°C for 1 hour. The refractive index of the formed cladding film was measured using a prism coupler apparatus (Model 2010 / M, Metricon) under the following measurement conditions. The results are shown in Table 1. -Measurement conditions- ·Temperature 25℃ • Prism 200-P-1 Low refractive index measuring prism n<1.80 • Single-layer film mode: refractive index and film thickness ·Wavelength: 1550nm TE mode ·Step size Half (high resolution)

[0133] <<Measurement of Linear Thermal Expansion Coefficient (CTE)>> The linear thermal expansion coefficient (CTE) of the undercladding layer was determined by TMA measurement in tensile mode using a TMA-7100 (Hitachi High-Tech Science Corporation). First, the undercladding film with an average thickness of approximately 8 μm was formed on the silicon wafer by spin coating and heating under a nitrogen atmosphere at 70°C for 2 hours, 160°C for 1 hour, 250°C for 30 minutes, and 350°C for 1 hour, through imidization. Next, the formed film was peeled from the silicon wafer by immersion in water, and the peeled film was cut into strips 20 mm long and 5 mm wide. The cut polyimide film sheets were used as measurement samples, and with the chuck spacing set to 10 mm, the CTE (linear thermal expansion coefficient) was determined from the displacement of the sample from 0°C to 200°C at a heating rate of 2°C / min while applying a load of 49 mN. The results are shown in Table 1.

[0134] (Example 2) <Manufacturing of laminate 2 for photoelectric fusion substrate> A laminate 2 for photoelectronic fusion substrates, further having an overcladding layer 22 on the core layer 10 of a laminate 1 for photoelectronic fusion substrates, was manufactured by following the procedure below.

[0135] <<Formation of the overcladding layer>> An acrylic hard coat (Beamset 575CB, manufactured by Arakawa Chemical Industries, Ltd.; refractive index n3: 1.51 at a wavelength of 1550 nm of the cured product) was applied to the core layer of the laminate 1 for the photoelectric fusion substrate of Example 1 as a photosensitive resin composition for forming the overcladding layer. Then, 600 mJ / cm was applied. 2 The material was cured to form an overcladding layer that covers the first surface of the undercladding layer and the side surface of the core layer having an optical waveguide circuit pattern.

[0136] Furthermore, in order to form the connection part with the photoelectric conversion element, the overcladding layer was cured by leaving unexposed areas during UV irradiation, and then washed with MEK (methyl ethyl ketone) as a solvent to expose a part of the core.

[0137] <<Formation of an insulating adhesive layer>> An OPP (MA-411, manufactured by Oji F-Tex Co., Ltd.) protective layer was applied to the overcladding layer for protection. After peeling off the laminate obtained from the glass substrate, a build-up film (ABF film, average thickness 30 μm, manufactured by Ajinomoto Co., Inc.) was placed on the surface of the undercladding layer opposite to the core layer formation surface as an insulating adhesive layer, and laminated by vacuum lamination to produce laminate 2 for the photoelectric fusion substrate of Example 2.

[0138] [Table 1]

[0139] (Example 3) <Manufacturing of laminate 3 for photoelectric fusion substrate> In Example 1, a 1 mm thick glass plate was used instead of a polyimide film as the heat-resistant resin layer, and the underclad layer and core layer were formed on the glass plate in the same manner as in Example 1. The resulting laminate was then immersed in 60°C hot water and peeled off from the glass plate. An insulating adhesive layer was laminated on the underclad layer side of the resulting two-layer laminate to produce a laminate 3 for a photoelectric fusion substrate having the configuration shown in Figure 2.

[0140] (Example 4) <Manufacturing of laminate 4 for photoelectric fusion substrate> An overcladding layer was formed on the core layer of the photoelectron fusion substrate laminate obtained in Example 3 using a photosensitive resin composition, similar to that in Example 3, to produce a photoelectron fusion substrate laminate 4 having an additional overcladding layer on the core layer of the photoelectron fusion substrate laminate 2.

[0141] As a result, it is possible to fuse optical waveguides while reducing the degradation of the electronic substrate, and the laminate for photoelectric fusion substrates and photoelectric fusion substrates can be applied, exhibiting excellent heat resistance, adhesion, and productivity.

[0142] Although embodiments have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims. [Explanation of Symbols]

[0143] 10-core layer 11 Core layer having optical waveguide circuit pattern 20 Clad layer 21 Underclad Layer 22 Overcladding Layers 30 Insulating adhesive layer 40 Heat-resistant resin layer 100, 110, 200, 210 Laminates for photoelectric fusion substrates 300, 310, 400, 410 Laminates for photoelectric fusion substrates

Claims

1. A core layer made of a heat-resistant resin with an average thickness of 1 μm or more and 10 μm or less, and a refractive index n1 at a wavelength of 1310 nm or 1550 nm, An undercladding layer made of a heat-resistant resin with an average thickness of 5 μm to 25 μm and a refractive index n2 at a wavelength of 1310 nm or 1550 nm, An insulating adhesive layer having an average thickness of 10 μm or more and 200 μm or less, made of a thermosetting resin composition, It has them in this order, The volume resistivity of the insulating adhesive layer after curing is 10 ８ It is greater than Ω·cm, A laminate for photoelectric fusion substrates characterized in that the refractive indices n1 and n2 satisfy the following relationship: 0.1 < 100 × (n1 - n2) / n1 < 5.

2. The laminate for a photoelectric fusion substrate according to claim 1, further comprising a heat-resistant resin layer between the underclad layer and the insulating adhesive layer, the heat-resistant resin having an average thickness of 15 μm or more and a glass transition temperature of 150°C or higher.

3. The laminate for a photoelectric fusion substrate according to claim 2, wherein the heat-resistant resin layer is made of polyimide resin.

4. The laminate for photoelectric fusion substrate according to claim 1 or 2, wherein the core layer has an optical waveguide circuit pattern with a core diameter of 1 μm or more and 10 μm or less.

5. The laminate for photoelectric fusion substrate according to claim 1 or 2, wherein the transmission loss of the core layer is 0.2 dB / cm or less.

6. The laminate for photoelectric fusion substrate according to claim 1 or 2, wherein the coefficient of linear expansion of the undercladding layer is 80 ppm / K or less.

7. The laminate for a photoelectric fusion substrate according to claim 1 or 2, wherein the thermosetting resin composition contains one or more selected from the group consisting of epoxy resin, epoxy / phenol resin, epoxy / cyanate resin, and epoxy / active ester resin.

8. The core layer is made of a first polyimide having a structural unit represented by the following general formula (1), The laminate for photoelectric fusion substrate according to claim 1 or 2, wherein the undercladding layer is made of a second polyimide having a structural unit represented by the following general formula (1). 【Chemistry 1】 In the above general formula (1), R １ This is a tetravalent group selected from the group consisting of the following: 【Chemistry 2】 In the above general formula (1), R ２ This is a divalent group selected from the group consisting of the following: 【Transformation 3】 R ｆ Each is independently either hydrogen or fluorine. X is independently O, S, SO ２ , or C=O, Y is independently O, S, SO ２ , or C=O, In the first polyimide, at least one R ｆ It is hydrogen, In the first polyimide, the number of hydrogen atoms in R ｆ is N Ｈ , the number of fluorine atoms in R ｆ is N Ｆ , and the fluorine substitution rate is f ｃｏｒｅ = N Ｆ / (N Ｈ + N Ｆ ), and In the second polyimide, R ｆ The number of hydrogen atoms in N Ｈ , R ｆ The number of fluorine atoms in N Ｆ , the fluorine substitution rate is f ｃｌａｄ = N Ｆ / (N Ｈ +N Ｆ ) when The following formula: f ｃｌａｄ > f ｃｏｒｅ , satisfies.

9. The underclad layer and the core layer further comprise an overclad layer made of a cured product of a photosensitive resin composition, with a refractive index n3 at a wavelength of 1310 nm or 1550 nm. The average thickness of the overcladding layer is 2 μm or more and 35 μm or less greater than the core diameter. The laminate for a photoelectric fusion substrate according to claim 4, wherein the refractive indices n1 and n3 satisfy the following relationship: 0.1 < 100 × (n1 - n3) / n1 < 5.

10. It consists of a cured product of a photosensitive resin composition, and comprises an overcladding layer having a refractive index n3 at a wavelength of 1310 nm or 1550 nm, A core layer having an optical waveguide circuit pattern, made of a heat-resistant resin with a core diameter of 1 μm or more and a refractive index n1 at a wavelength of 1310 nm or 1550 nm, An undercladding layer made of a heat-resistant resin with an average thickness of 5 μm to 25 μm and a refractive index n2 at a wavelength of 1310 nm or 1550 nm, It has them in this order, The average thickness of the overcladding layer is 2 μm or more and 35 μm or less greater than the core diameter. If the refractive indices n1 and n2 satisfy the following relationship: 0.1 < 100 × (n1 - n2) / n1 < 5, A laminate for photoelectric fusion substrates characterized in that the refractive indices n1 and n3 satisfy the following relationship: 0.1 < 100 × (n1 - n3) / n1 < 5.

11. The laminate for a photoelectric fusion substrate according to claim 10, further comprising a heat-resistant resin layer on the surface of the underclad layer opposite to the surface in contact with the core layer, the heat-resistant resin having an average thickness of 15 μm or more and a glass transition temperature of 150°C or higher.

12. Electronic circuit board and A laminate for a photoelectric fusion substrate according to claim 1, 2, 10, or 11, comprising A photoelectric fusion substrate characterized by fusing the laminate for the photoelectric fusion substrate to the electronic substrate.

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