Photosensitive resin composition, and resin composition for optical waveguides and resin composition for interlayer insulation both including same

Abstract

One aspect of the present invention relates to a photosensitive resin composition which comprises a poly(amic acid) (A) having a photosensitive moiety, a (meth)acrylate monomer (B), and a photopolymerization initiator (C), wherein the (meth)acrylate monomer (B) includes a (meth)acrylate monomer (B1) having a silicone structure, the silicone structure having a siloxane structure represented by formula (1) in the main chain, and the photopolymerization initiator (C) includes a radical polymerization initiator (C1). (In the formula, n is an integer of 2 or larger.)

Description

Photosensitive resin composition, and resin composition for optical waveguide and resin composition for interlayer insulation using the same

[0001] The present invention relates to a photosensitive resin composition, and to a resin composition for optical waveguides and a resin composition for interlayer insulation that use the same.

[0002] Optical fiber has traditionally been the mainstream transmission medium in the fields of FTTH (Fiber to the Home) and long-distance and medium-distance communications in the automotive field. In recent years, high-speed optical transmission over short distances of less than 1 meter has become necessary. In this area, optical waveguide-type optical wiring boards are suitable because they offer high-density wiring (narrow pitch, branching, crossing, multilayering, etc.), surface mountability, integration with electrical substrates, and small-diameter bending capabilities that are not possible with optical fiber.

[0003] It is known that optical waveguides are formed by forming cladding layers, core layers, etc. using a highly transparent resin material, exposing (photosensitizing) the material to ultraviolet (UV) radiation, developing, and then curing the resin. It has also been reported that a resin composition containing an epoxy compound and a curing agent, which have excellent light resistance, etc., is used as the resin material for such optical waveguides (Patent Document 1). However, in recent years, there has been a demand for optical waveguide materials with even higher performance. Specifically, optical waveguide materials are expected to have low optical loss, excellent heat resistance, etc., and, in the future, low dielectric properties depending on the application.

[0004] On the other hand, polyamic acid compositions and polyimide compositions have been reported as materials that can achieve properties such as heat resistance and a low coefficient of thermal expansion (Patent Document 2).

[0005] The composition described in Patent Document 2 has excellent properties such as heat resistance, but the polyamic acid and polyimide used therein do not have photosensitive sites, making it difficult to form good patterns by photoexposure, and therefore cannot be used for applications such as optical waveguides.

[0006] JP 2017-134319 A Patent No. 6476469 A

[0007] A primary object of the present invention is to provide a photosensitive resin composition that has low optical loss and excellent low dielectric properties, as well as a resin composition for optical waveguides and a resin composition for interlayer insulation that use the same.

[0008] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved by the following configuration.

[0009] That is, a photosensitive resin composition according to one aspect of the present invention contains a polyamic acid (A) having a photosensitive moiety, a (meth)acrylate monomer (B), and a photopolymerization initiator (C), wherein the (meth)acrylate monomer (B) contains a (meth)acrylate monomer (B1) having a silicone structure, the silicone structure having a siloxane structure represented by the following formula (1) in its main chain, and the photopolymerization initiator (C) contains a radical polymerization initiator (C1):

[0010] (wherein n represents an integer of 2 or more)

[0011] FIG. 1 is a schematic cross-sectional view of a slab waveguide for evaluation, which was fabricated in the example.

[0012] Hereinafter, embodiments for carrying out the present invention will be specifically described, but the present invention is not limited to these.

[0013] <Photosensitive Resin Composition> The photosensitive resin composition of this embodiment (hereinafter sometimes simply referred to as a resin composition) contains a polyamic acid (A) having a photosensitive moiety, a (meth)acrylate monomer (B), and a photopolymerization initiator (C). The (meth)acrylate monomer (B) contains a (meth)acrylate monomer (B1) having a silicone structure. The silicone structure has a siloxane structure represented by the above formula (1) in its main chain. The photopolymerization initiator (C) also contains a radical polymerization initiator (C1).

[0014] This configuration provides a photosensitive resin composition with low optical loss and excellent low dielectric properties, as well as a resin composition for optical waveguides and a resin composition for interlayer insulation using the same. Because the resin composition of this embodiment is photosensitive, it is possible to form a good pattern by photoexposure. In this specification, "forming a good pattern" means, for example, that when used in an optical waveguide, a core of an appropriate width can be formed after the resin composition is exposed to light. Furthermore, the resin composition of this embodiment can suppress optical loss (particularly optical loss at a wavelength of 1310 nm) in its cured product. Therefore, the resin composition of this embodiment is useful for optical waveguides and can be used for both cladding layers and core layers. However, because optical loss at a wavelength of 1310 nm occurs in the core, using the resin composition of this embodiment for a core layer can provide greater benefits.

[0015] Furthermore, the resin composition of this embodiment has excellent low dielectric properties (low dielectric constant (Dk) and low dielectric loss tangent (Df)) in the cured product. Therefore, it is considered that the range of applications will be widened when used for optical waveguides. Furthermore, because of the low dielectric properties, the resin composition of this embodiment is also useful for interlayer insulation, for example.

[0016] (Polyamic Acid (A)) The polyamic acid (A) of the present embodiment is characterized by having a photosensitive moiety. There are no particular limitations on the polyamic acid that can be used as long as it has a photosensitive moiety. For example, a polyamic acid represented by the following formula (2) can be used.

[0017] In formula (2), X represents a photosensitive moiety, and n represents an integer of 1 to 20.

[0018] By including the polyamic acid (A) having a photosensitive moiety, the resin composition of the present embodiment is photosensitive and can be used as a resin composition for optical waveguides. In addition, optical loss can be reduced and the cured product has excellent low dielectric properties.

[0019] The photosensitive moiety X is not particularly limited, and examples thereof include a meth(acrylate) structure and a maleimide structure. Among these, it is preferable that the photosensitive moiety X has a meth(acrylate) structure, from the viewpoint that the light-irradiated portion becomes insoluble in a developer due to a photocuring reaction of the photosensitive group. Specific preferred examples of the meth(acrylate) structure include 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate.

[0020] Examples of the polyamic acid (A) having a meth(acrylate) structure as a photosensitive moiety include polyamic acids having the structure represented by the formula (2) above, in which the photosensitive moiety X is a structure represented by the following formula (3):

[0021]

[0022] The molecular structure of the polyamic acid (A) of this embodiment is not particularly limited, and may be a random polymer, an alternating copolymer, a block copolymer, or the like, depending on the polymerization conditions.

[0023] In a preferred embodiment, the polyamic acid (A) contains elemental fluorine. It is believed that the inclusion of elemental fluorine in the polyamic acid (A) can further reduce the polarity of the resin composition of this embodiment, further reduce optical loss, and more reliably achieve low dielectric properties. The position of the elemental fluorine in the polyamic acid (A) is not particularly limited. For example, a portion of the benzene ring may be fluorinated. When the polyamic acid (A) is obtained by copolymerization of a diamine and an acid dianhydride, the fluorine may be contained in the diamine or the acid anhydride.

[0024] In another preferred embodiment, the polyamic acid (A) has a silicone structure. It is believed that the silicone structure of the polyamic acid (A) also makes it possible to further reduce the polarity of the resin composition of this embodiment, further reduce optical loss, and more reliably obtain low dielectric properties.

[0025] The silicone structure of the polyamic acid (A) may be a polydimethylsiloxane having a dimethylsiloxane unit as the main chain skeleton, a siloxane structure having a vinyl group introduced into a side chain or terminal, or a structure having a phenyl group or a fluoroalkyl group introduced into the siloxane structure. The position of the silicone structure in the polyamic acid (A) is not particularly limited.

[0026] The weight-average molecular weight (Mw) of the polyamic acid (A) of this embodiment is not particularly limited, but is preferably 1,000 or more and 40,000 or less. Having a weight-average molecular weight (Mw) within this range has the advantage of facilitating film formation when forming an optical waveguide or an interlayer insulating layer. A more preferred lower limit of the weight-average molecular weight is 2,000 or more, and more preferably 4,000 or more. A more preferred upper limit is 30,000 or less, and even more preferably 20,000 or less.

[0027] The weight average molecular weight (Mw) of the polyamic acid (A) can be measured by gel permeation chromatography (GPC).

[0028] The polyamic acid (A) as described above may be used alone or in combination of two or more kinds.

[0029] The method for producing the polyamic acid (A) of this embodiment is not particularly limited. For example, a precursor of the polyamic acid (A) of this embodiment can be obtained by polymerizing 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) as an aromatic diamine compound and 4,4'-oxydiphthalic anhydride (ODPA) as an aromatic tetracarboxylic acid compound. The molar ratio of BAPP to ODPA is preferably about 1:1.

[0030] The conditions for polymerizing the mixture of BAPP and ODPA are not particularly limited. Examples include a polymerization method in which the mixture is reacted at room temperature to 50°C under atmospheric pressure while stirring. Then, a photosensitive moiety is introduced into the resulting polyamic acid. Specifically, for example, triethylene glycol diacrylate (BAPP:ODPA molar ratio = 1:1) as an addition-polymerizable compound (precursor of polyamic acid) and 3-methacryloxypropyltrimethoxysilane (precursor of polyamic acid:adhesive (mass ratio = 100:3)) are added as an adhesive, and the mixture is stirred and dissolved overnight at room temperature, followed by filtering, thereby introducing the photosensitive moiety and obtaining polyamic acid (A) of this embodiment.

[0031] The fluorine-containing polyamic acid (A) can be obtained, for example, by polymerizing an aromatic diamine compound represented by the following formula (4) with an aromatic acid anhydride represented by the following formula (5).

[0032]

[0033]

[0034] In the case of a polyamic acid (A) having a silicone structure in addition to elemental fluorine, the fluorine-containing polyamic acid (A) can be prepared by blending a compound obtained by copolymerizing an acid anhydride having a silicone structure with a diamine, a compound obtained by copolymerizing an acid anhydride with a diamine having a silicone structure, or a compound obtained by copolymerizing an acid anhydride with a diamine having a silicone structure, to obtain a polyamic acid (A) having a siloxane structure represented by the following formula (6):

[0035] In formula (6), n represents an integer of 2 to 20.

[0036] The polyamic acid (A) obtained by the above-described production method includes, for example, polyamic acids having at least one of the repeating units represented by the following formulas (7) to (9).

[0037] In formula (7), X represents a photosensitive moiety.

[0038] In formula (8), X represents a photosensitive moiety.

[0039] In formula (9), X represents a photosensitive moiety, and a represents an integer of 0 to 20.

[0040] In the polyamic acid (A) represented by the above formulas (7) to (9), the photosensitive moiety X has the same meaning as the photosensitive moiety X already described above.

[0041] In addition, in the polyamic acid (A) having at least one of the repeating units represented by formulas (7) to (9), the number n of the repeating units is not particularly limited, but it is preferable to adjust the weight average molecular weight (Mw) of the polyamic acid (A) to be 1,000 or more and 40,000 or less.

[0042] The content of polyamic acid (A) in the resin composition of this embodiment is preferably 70.00 parts by mass or more and 95.00 parts by mass or less, relative to 100 parts by mass of the total of polyamic acid (A), (meth)acrylate monomer (B), and photopolymerization initiator (C). It is believed that this content range more reliably achieves low dielectric properties and further reduces optical loss. A more preferred content range is 73.00 parts by mass or more and 94.00 parts by mass or less.

[0043] ((Meth)acrylate Monomer (B)) The resin composition of this embodiment contains a (meth)acrylate monomer (B). The (meth)acrylate monomer (B) contains a (meth)acrylate monomer (B1) having a silicone structure. The (meth)acrylate monomer (B) plays a role as a crosslinking agent that reacts with the polyamic acid (A). However, since the (meth)acrylate monomer (B) has a silicone structure, it is believed that the polarity of the resin composition of this embodiment can be further reduced, optical loss can be further reduced, and low dielectric properties can be more reliably obtained.

[0044] The (meth)acrylate monomer (B) of this embodiment has a silicone structure represented by the following formula (1).

[0045] In formula (1), n ​​represents an integer of 2 or more, preferably an integer of 2 to 20.

[0046] Specific examples of the (meth)acrylate monomer (B1) having such a silicone structure include methacryloxypropyl-terminated polydimethylsiloxane, (methacryloxypropyl)methylsiloxane-dimethylsiloxane copolymer, etc. As the (meth)acrylate monomer (B1), for example, commercially available reagents such as DMS-R05, DMS-R11, DMS-R18, DMS-R22, DMS-R31, RMS-044, RMS-033, and RMS-083 can also be used.

[0047] In a preferred embodiment, the silicone structure has a siloxane structure represented by the above formula (6). However, in the siloxane structure contained in the (meth)acrylate monomer (B1), n ​​in formula (6) is preferably an integer of 2 to 10.

[0048] The (meth)acrylate monomer (B1) preferably further has an imide structure, which is thought to improve the heat resistance of the resin composition and also contribute to reducing optical loss.

[0049] Examples of the (meth)acrylate monomer (B1) having an imide structure include silicone imide acrylate.

[0050] The method for producing the (meth)acrylate monomer (B1) of the present embodiment is not particularly limited. For example, in the case of methacryloxypropyl-terminated polydimethylsiloxane, the (meth)acrylate monomer (B1) can be obtained by a method in which a polymethyl methacrylate resin and a silicone oil are heated, melted, and mixed in an extruder or a mixer.

[0051] The (meth)acrylate monomer (B1) obtained by the above method includes, for example, a (meth)acrylate monomer represented by the following formula (10).

[0052]

[0053] The content of the (meth)acrylate monomer (B) in the resin composition of this embodiment is preferably 3.00 parts by mass or more and 27.00 parts by mass or less, relative to 100 parts by mass of the total of the polyamic acid (A), the (meth)acrylate monomer (B), and the photopolymerization initiator (C). It is believed that this content range more reliably achieves low dielectric properties and further reduces optical loss. A more preferred content range is 5.00 parts by mass or more and 25.00 parts by mass or less.

[0054] The (meth)acrylate monomer (B) of this embodiment may contain a (meth)acrylate monomer other than the (meth)acrylate monomer (B1) having a silicone structure, but the content of the (meth)acrylate monomer (B1) in the resin composition of this embodiment is preferably 30% by mass or more relative to 100% by mass of the (meth)acrylate monomer (B). If the content is less than 30% by mass, there is a risk that the suppression of light loss may be insufficient or that heat resistance may be reduced. A more preferred range for the content is 50% by mass or more. There is no particular limitation on the upper limit of the content of the (meth)acrylate monomer (B1), and it may be 100% by mass.

[0055] (Photopolymerization initiator (C)) The resin composition of this embodiment contains a photopolymerization initiator (C), and the photopolymerization initiator (C) contains a radical polymerization initiator (C1). This provides the resin composition of this embodiment with excellent photosensitivity and also enables fine pattern formation by photosensitivity.

[0056] The radical polymerization initiator (C1) is not particularly limited as long as it is a photoradical polymerization initiator that generates radical species when irradiated with ultraviolet light. Examples of the photoradical polymerization initiator include aromatic ketones, acylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (thioxanthone compounds, thiophenyl group-containing compounds, etc.), hexaarylbiimidazole compounds, oxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds.

[0057] Among these, the radical polymerization initiator (C1) preferably contains a photoradical polymerization initiator having photobleaching properties. A preferred example of such a photoradical polymerization initiator is an oxime ester initiator (c1). This has the advantages of suppressing outgassing when the resin composition is cured, resulting in higher sensitivity and excellent curability.

[0058] In order to further reduce the likelihood of outgassing from the cured product of the resin composition, the oxime ester photoinitiator (c1) preferably contains a compound having an aromatic ring, more preferably contains a compound having a fused ring containing an aromatic ring, and even more preferably contains a compound having a fused ring containing a benzene ring and a heterocycle.

[0059] More specifically, examples of the oxime ester photoinitiator (c1) that can be used include 1,2-octadione-1-[4-(phenylthio)-, 2-(o-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(o-acetyloxime), and compounds described in JP-A Nos. 2000-80068, 2001-233842, JP-T Nos. 2010-527339, 2010-527338, JP-A Nos. 2013-041153, and 2015-93842. These compounds may be used alone or in combination of two or more.

[0060] Commercially available products can also be used as the oxime ester photoinitiator (c1), for example, Irgacure OXE-02 (manufactured by BASF), Adeka Arcles NCI-831, N-1919 (manufactured by ADEKA Corporation) and TR-PBG-304 (manufactured by Changzhou Powerful Electronic New Materials Co., Ltd.) having a carbazole skeleton, Irgacure OXE-01, Adeka Arcles NCI-930 (manufactured by ADEKA Corporation), TR-PBG-345 and TR-PBG-3057 (manufactured by Changzhou Powerful Electronic New Materials Co., Ltd.), and TR-PBG-365 (manufactured by Changzhou Powerful Electronic New Materials Co., Ltd.) and SPI-04 (manufactured by Sanyang Co., Ltd.) having a fluorene skeleton can be used. In particular, by containing a compound having a carbazole skeleton, the oxime ester photoinitiator (c1) has the advantage that the exposure sensitivity is easily increased.

[0061] The content of the photopolymerization initiator (C) in the resin composition of this embodiment is preferably 0.05 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the total of the polyamic acid (A), the (meth)acrylate monomer (B), and the photopolymerization initiator (C). It is believed that a resin composition with superior photosensitivity can be obtained by using the content in this range. A more preferred content range is 0.1 parts by mass or more and 5 parts by mass or less.

[0062] The photopolymerization initiator (C) of this embodiment may contain a photopolymerization initiator (C) other than the radical polymerization initiator (C1). However, the content of the radical polymerization initiator (C1) in the photopolymerization initiator (C) of this embodiment is preferably 50% by mass or more relative to 100% by mass of the photopolymerization initiator (C). If the content is less than 50% by mass, curing may be insufficient. A more preferred range for the content is 70% by mass or more. There is no particular limitation on the upper limit of the content of the radical polymerization initiator (C1), and it may be 100% by mass.

[0063] The radical polymerization initiator (C1) of this embodiment may contain a radical polymerization initiator (C1) other than the oxime ester photoinitiator (c1). However, the content of the oxime ester photoinitiator (c1) in the radical polymerization initiator (C1) of this embodiment is preferably 60% by mass or more relative to 100% by mass of the radical polymerization initiator (C1). If the content is less than 60% by mass, curing may be insufficient. A more preferred range for the content is 70% by mass or more. There is no particular limitation on the upper limit of the content of the oxime ester photoinitiator (c1), and it may be 100% by mass.

[0064] (Other Components) In addition to the above, the resin composition of the present embodiment may also contain additives such as an antioxidant, a leveling agent, a coupling agent (silane coupling agent), a flame retardant, and an inorganic filler depending on the application.

[0065] The resin composition according to the present embodiment as described above has excellent photosensitivity and low optical loss in the cured product, making it extremely useful as an optical waveguide material. In addition, since it also has low dielectric properties, it is also useful as an interlayer insulating material, for example.

[0066] <Photosensitive resin composition for optical waveguide> The photosensitive resin composition has photosensitivity and exhibits favorable effects in suppressing optical loss, and therefore can be suitably used as a material for a dry film used in producing an optical waveguide. However, the epoxy resin composition for optical waveguide according to this embodiment does not necessarily need to be used after forming a dry film when producing an optical waveguide.

[0067] The dry film for optical waveguides according to another embodiment of the present invention is not particularly limited as long as it includes a layer made of the resin composition. Specifically, the dry film for optical waveguides includes a layer made of a semi-cured or cured product of the resin composition (hereinafter also simply referred to as a resin composition layer). The dry film of this embodiment may also include a substrate film laminated on at least one side of the resin composition layer. Furthermore, a protective film may be laminated on the other side of the resin composition layer.

[0068] The dry film for optical waveguide of this embodiment only needs to have the resin composition layer, and may have other layers in addition to the film substrate and protective film, and the film substrate and protective film are not required.

[0069] The film substrate is not particularly limited, but examples thereof include polyethylene terephthalate (PET) film, biaxially oriented polypropylene film, polyethylene naphthalate film, polyimide film, etc. Among these, PET film is preferably used.

[0070] The protective film is not particularly limited, but examples thereof include polypropylene films.

[0071] The method for producing the dry film for optical waveguides of this embodiment is not particularly limited, and examples thereof include the following methods. First, a solvent or the like is added to the resin composition for optical waveguides described above to form a varnish, and the varnish is applied to a film substrate. This application can be performed using a comma coater or the like. Then, the varnish is dried to form a resin composition layer on the film substrate. Furthermore, a protective film is laminated on this resin composition layer. Examples of the lamination method include a thermal lamination method.

[0072] The resin composition layer in this dry film for optical waveguides is used as a material for optical waveguides. The dry film for optical waveguides may be used when manufacturing the core or clad of an optical waveguide, but is preferably used for the core because it can further suppress optical loss at a wavelength of 1310 nm. The dry film of this embodiment has excellent photosensitivity, can reduce optical loss, and also has low dielectric properties.

[0073] The resin composition for an optical waveguide according to the present embodiment does not necessarily have to be used as a dry film as described above, and may be used, for example, in the form of a varnish. This composition for an optical waveguide may be used when producing a core or clad of an optical waveguide, similar to the dry film for an optical waveguide.

[0074] The present invention also includes an optical waveguide formed from the above-described resin composition for an optical waveguide and the above-described dry film for an optical waveguide. The optical waveguide included in this embodiment is an optical waveguide having a core layer and a clad layer having a refractive index lower than that of the core layer, characterized in that the clad layer and / or the core layer are formed from the above-described resin composition for an optical waveguide or a dry film. In a preferred embodiment, the core layer is formed from the above-described photosensitive resin composition or a dry film.

[0075] The optical waveguide of this embodiment, having the above-described configuration, has excellent photosensitivity and suppresses optical loss (particularly optical loss at a wavelength of 1310 nm). Therefore, a substrate on which the optical waveguide of this embodiment is formed is preferably used as an optical transmission printed wiring board or the like, and specifically, is preferably used for applications such as mobile phones, personal digital assistants, CPOs (Co-Packed Optics), and optical transceivers. Furthermore, because it has excellent low dielectric properties, it is thought that it can also be used in applications such as buffer coating films.

[0076] <Photosensitive Resin Composition for Interlayer Insulation> The photosensitive resin composition has low dielectric properties and can therefore be suitably used as an insulating material. The photosensitive resin composition for interlayer insulation can also be suitably used, for example, as a material for a layer to be laminated on a clad layer in order to insulate an optical waveguide formed from a core layer and a clad layer.

[0077] The photosensitive resin composition for interlayer insulation preferably further contains a filler from the viewpoint of reducing the thermal expansion coefficient of the cured product of the resin composition. The filler material is not particularly limited, but examples thereof include silica, alumina, glass, cordierite, silicone oxide, barium sulfate, barium carbonate, talc, clay, mica powder, and zinc oxide. Among these, silica is preferred from the viewpoints of insulating properties and industrial availability.

[0078] When the photosensitive resin composition for interlayer insulation contains a filler, the filler is generally contained in the form of particles. The average particle size of the filler particles is not particularly limited, but from the viewpoint of enabling fine pattern formation by photoexposure and obtaining an interlayer insulation layer with low surface roughness, it is preferably 5 μm or less, more preferably 2 μm or less. Furthermore, from the viewpoint of suppressing an increase in the viscosity of the varnish when made into a resin varnish and preventing a decrease in handleability, the average particle size of the filler particles is preferably 0.01 μm or more, more preferably 0.05 μm or more.

[0079] When the photosensitive resin composition for interlayer insulation contains a filler, the content of the filler is preferably 20 parts by mass or more and 300 parts by mass or less, and more preferably 50 parts by mass or more and 200 parts by mass or less, relative to 100 parts by mass of the total of the polyamic acid (A), the (meth)acrylate monomer (B), and the photopolymerization initiator (C).

[0080] As described above, this specification discloses various aspects of the technology, the main aspects of which are summarized below.

[0081] A photosensitive resin composition according to a first aspect of the present invention comprises a polyamic acid (A) having a photosensitive moiety, a (meth)acrylate monomer (B), and a photopolymerization initiator (C), wherein the (meth)acrylate monomer (B) contains a (meth)acrylate monomer (B1) having a silicone structure, the silicone structure having a siloxane structure represented by the following formula (1) in its main chain, and the photopolymerization initiator (C) contains a radical polymerization initiator (C1):

[0082] (wherein n represents an integer of 2 or more)

[0083] A photosensitive resin composition according to a second aspect of the present invention is the photosensitive resin composition according to the first aspect, wherein the content of the photopolymerization initiator (C) is 0.05 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass in total of the polyamic acid (A), the (meth)acrylate monomer (B), and the photopolymerization initiator (C).

[0084] A resin composition for optical waveguides according to a third aspect of the present invention is the photosensitive resin composition according to the first or second aspect, in which the content of the (meth)acrylate monomer (B) is 3.00 parts by mass or more and 27.00 parts by mass or less, relative to 100 parts by mass of the total of the polyamic acid (A), the (meth)acrylate monomer (B), and the photopolymerization initiator (C).

[0085] A photosensitive resin composition according to a fourth aspect of the present invention is the photosensitive resin composition according to any one of the first to third aspects, in which the content of the polyamic acid (A) is 70.00 parts by mass or more and 95.00 parts by mass or less, relative to 100 parts by mass of the total of the polyamic acid (A), the (meth)acrylate monomer (B), and the photopolymerization initiator (C).

[0086] A photosensitive resin composition according to a fifth aspect of the present invention is the photosensitive resin composition according to any one of the first to fourth aspects, wherein the photosensitive moiety has a (meth)acrylate structure.

[0087] A photosensitive resin composition according to a sixth aspect of the present invention is the photosensitive resin composition according to any one of the first to fifth aspects, in which the polyamic acid (A) contains a fluorine element.

[0088] A photosensitive resin composition according to a seventh aspect of the present invention is the photosensitive resin composition according to any one of the first to sixth aspects, in which the polyamic acid (A) has a silicone structure.

[0089] A photosensitive resin composition according to an eighth aspect of the present invention is the photosensitive resin composition according to any one of the first to seventh aspects, in which the (meth)acrylate monomer (B1) has an imide structure.

[0090] A photosensitive resin composition according to a ninth aspect of the present invention is the photosensitive resin composition according to any one of the first to eighth aspects, in which the radical polymerization initiator (C1) comprises an oxime ester initiator (c1).

[0091] A resin composition for an optical waveguide according to a tenth aspect of the present invention includes the photosensitive resin composition according to any one of the first to ninth aspects.

[0092] An interlayer insulating resin composition according to an eleventh aspect of the present invention includes the photosensitive resin composition according to any one of the first to ninth aspects.

[0093] The interlayer insulating resin composition according to a twelfth aspect of the present invention is the interlayer insulating resin composition according to the eleventh aspect, further comprising an inorganic filler (D).

[0094] A resin-coated film according to a thirteenth aspect of the present invention has a resin layer containing the photosensitive resin composition of any one of the first to ninth aspects or a semi-cured product of the photosensitive resin composition, and a support film.

[0095] A liquid material according to a fourteenth aspect of the present invention contains the photosensitive resin composition according to any one of the first to ninth aspects.

[0096] An optical waveguide according to a fifteenth aspect of the present invention is formed using the resin composition for an optical waveguide according to the tenth aspect.

[0097] An optical waveguide substrate according to a sixteenth aspect of the present invention includes the optical waveguide of the thirteenth aspect.

[0098] A semiconductor package according to a seventeenth aspect of the present invention includes the optical waveguide substrate according to the fourteenth aspect.

[0099] An interlayer insulating layer according to the eighteenth aspect of the present invention is formed using the interlayer insulating resin composition according to the eleventh or twelfth aspect.

[0100] A wiring board according to a nineteenth aspect of the present invention includes the interlayer insulating layer according to the eighteenth aspect.

[0101] A semiconductor package according to a twentieth aspect of the present invention includes the wiring board according to the nineteenth aspect.

[0102] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the following examples.

[0103] <Polyamic Acid (A)> First, polyamic acids (A1) to (A3) were synthesized.

[0104] Synthesis Example 1 Polyamic Acid (A1) In a nitrogen atmosphere, 81.6 g (0.26 mol) of aromatic tetracarboxylic dianhydride (ODPA) was added to 1,062 g of a solvent (N-methyl-2-pyrrolidone (NMP)) in which 107 g (0.26 mol) of aromatic diamine (BAPP) had been dissolved. The mixture was stirred and reacted at room temperature and atmospheric pressure for 3 hours to synthesize a viscous polymer solution (polyamic acid solution). This was used as a polyamic acid precursor. Thereafter, 39.2 g (0.19 mol) of N,N-dicyclohexylcarbamate solution was added to the polyamic acid precursor with stirring. 67.7 g (0.52 mol) of N,N-dicyclohexylcarbamate solution was added to the polyamic acid precursor. mol) of 2-hydroxyethyl methacrylate was added, and the mixture was stirred at 50°C for 5 hours and then at room temperature overnight. This reaction mixture was diluted with 200 ml of acetone, and insoluble matter was removed by suction filtration. The filtrate was treated with 2.0 liters of ion-exchanged water while vigorously stirring. The precipitated solid was further washed with ion-exchanged water and then with methanol, dried by suction on the filter, and dried under reduced pressure at room temperature until the water content was less than 1.0 wt%. In this way, polyamic acid (A1) represented by the following formula (11) was obtained. The weight-average molecular weight of polyamic acid (A1) was 15,000.

[0105] In formula (11), the photosensitive moiety X has the structure shown in formula (3) above.

[0106] Synthesis Example 2 Fluorine-Containing Polyamic Acid (A2) In a nitrogen atmosphere, 115.5 g (0.26 mol) of 6FDA (4,4'-(hexafluoroisopropylidene)diphthalic anhydride) was dissolved in 1062 g of a solvent (N-methyl-2-pyrrolidone (NMP)) containing aromatic diamine TFMB (2,2'-bis(trifluoromethyl)benzidine). 83.2 g (0.26 mol) of N,N-dicyclohexyl methyl methacrylate (4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl) was added to the reaction mixture, and the mixture was stirred and reacted at room temperature and atmospheric pressure for 3 hours to synthesize a viscous polymer solution (polyamic acid solution). This was used as a polyamic acid precursor. 39.2 g (0.19 mol) of N,N-dicyclohexyl methyl methacrylate solution was then added to the polyamic acid precursor while stirring. 67.7 g (0.52 mol) of 2-hydroxyethyl methacrylate was added to this reaction solution, and the resulting mixture was stirred for 5 hours. The mixture was stirred at 0°C for 5 hours and then at room temperature overnight. The reaction mixture was diluted with 200 ml of acetone, and the filtrate was subjected to suction filtration to remove insoluble material. The filtrate was treated with 2.0 liters of ion-exchanged water with vigorous stirring. The precipitated solid was washed with ion-exchanged water and then with methanol, dried on the filter by suction, and then dried under reduced pressure at room temperature until the water content was less than 1.0 wt%. Polyamic acid (A2) represented by the following formula (12) was obtained. The weight-average molecular weight of polyamic acid (A2) was 15,000.

[0107] In formula (12), the photosensitive moiety X has the structure shown in formula (3) above.

[0108] Synthesis Example 3: Fluorine- and Silicone-Containing Polyamic Acid (A3) In a nitrogen atmosphere, 83.2 g (0.26 mol) of aromatic diamine TFMB (2,2'-bis(trifluoromethyl)benzidine 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl) was dissolved or dispersed in 1,062 g of NMP (N-methyl-2-pyrrolidone) in a flask, and diaminosiloxane (PSX750, 0.026 mol) was gradually added at room temperature. After the addition was completed, the mixture was allowed to react for 2 hours. To maintain the reaction temperature below 30°C, 104 g (0.23 mol) of 6FDA (4,4'-(hexafluoroisopropylidene)diphthalic anhydride) was gradually added under ice cooling. After adding all the diamines, the mixture was allowed to react for one hour under cooling and then for three hours at room temperature, yielding a polyamic acid solution with a reduced viscosity of 1.0-1.3 (g / dL). To the resulting polyamic acid solution, 260 ml of xylene was added as an azeotropic solvent. A Dean-Stark cooling device was attached, and after the xylene reflux began, the mixture was heated for six hours to undergo dehydration and imidation. After completion of the dehydration and imidation reaction, the xylene was removed, yielding a polyamic acid precursor. Subsequently, 39.2 g (0.19 mol) of N,N-dicyclohexyl methyl acrylate solution was added to the polyamic acid precursor with stirring. 67.7 g (0.52 mol) of 2-hydroxyethyl methacrylate was added to the reaction solution, which was then stirred at 50°C for five hours and then overnight at room temperature. The reaction mixture was diluted with 200 ml of acetone, and the insoluble material was removed by suction filtration. The filtrate was then treated with 2.0 L of ion-exchanged water with vigorous stirring. The precipitated solid was washed with ion-exchanged water and then with methanol, dried on a filter, and then dried under reduced pressure at room temperature until the water content was less than 1.0 wt %. Polyamic acid (A3) represented by the following formula (9) was obtained. The weight-average molecular weight of polyamic acid (A3) was 20,000.

[0109] In formula (9), the photosensitive moiety X has the structure shown in formula (3) above.

[0110] <(Meth)acrylate Monomer (B)> <Synthesis Example 4: Silicone Structure-Containing (Meth)acrylate Monomer (B1)> 50 parts by mass of polymethyl methacrylate resin and 50 parts by mass of silicone oil were used as raw materials, and these were heated, melted, and mixed at 150°C in an extruder to obtain the (meth)acrylate monomer (B1) represented by the above formula (10).

[0111] Next, raw materials other than the polyamic acid (A) and the (meth)acrylate monomer (B) used in preparing the resin composition in this example are listed below.

[0112] <(Meth)acrylate Monomer> "Light Acrylate DPE-6A": dipentaerythritol hexaacrylate, manufactured by Kyoeisha Chemical Co., Ltd. <Photopolymerization Initiator> "OXE-01": radical polymerization initiator (oxime ester type), manufactured by BASF Japan Ltd. "CPI-200K": cationic polymerization initiator, manufactured by San-Apro Ltd.

[0113] Examples 1 to 11 and Comparative Examples 1 and 2 (Preparation of Photosensitive Resin Compositions) The components were blended according to the blending compositions (parts by mass) shown in Table 1 below, and the N-methyl-2-pyrrolidone (NMP) solvent was adjusted to 50 parts by mass per 50 parts by mass of the resin, and mixed while heating to 50 to 80° C. Next, the mixture was filtered through a membrane filter with a pore size of 0.5 μm and then degassed to prepare resin varnishes of the photosensitive resin compositions of Examples 1 to 11 and Comparative Examples 1 and 2.

[0114] (Formation of dry film) The photosensitive resin composition varnish of each example and comparative example was applied to a PET film (product number A4100) manufactured by Toyobo Co., Ltd. using a multi-coater with a comma coater head manufactured by Hirano Tecseed Co., Ltd., and dried to a predetermined thickness, and a release film, OPP-MA420 manufactured by Oji Specialty Paper Co., Ltd., was thermally laminated to obtain a dry film for evaluation having a resin layer thickness of 10 to 40 μm.

[0115] <Evaluation Method> (Dielectric Properties) For the evaluation of dielectric properties, the dry films obtained above were cured at a temperature increase rate of 2°C / min at 180°C for 1 hour and at 250°C for 2 hours to prepare cured films. The relative permittivity (Dk) and dielectric loss tangent (Df) at 10 GHz of the cured films of each Example and Comparative Example were measured using a cavity resonator perturbation method. Specifically, a network analyzer (N5230A manufactured by Keysight Technologies Inc.) was used to measure the relative permittivity and dielectric loss tangent of the evaluation substrate at 10 GHz. In this test, the evaluation was performed according to the following criteria. Regarding Dk: A: Less than 3.5; B: 3.5 or more and less than 4.0; C: 4.0 or more. Regarding Df: A: Less than 0.03; B: 0.03 or more and 0.05 or less; C: More than 0.06

[0116] (Optical Loss) First, optical waveguides were formed using the dry films of each Example and Comparative Example. For the optical waveguides of Examples 1 to 11 and Comparative Examples 1 and 2, the dry films of Examples 1 to 11 and Comparative Examples 1 and 2 obtained above were used as core dry films, and dry films having a refractive index smaller than that of the optical waveguides of Examples 1 to 13 and Comparative Examples 1 to 9 were prepared and used for the clad layers.

[0117] Using these dry films, a slab waveguide was fabricated on a substrate (R1515W, manufactured by Panasonic Corporation) with a core sandwiched between two cladding layers, as shown in Figure 1. The reference numerals in the figure indicate 1: substrate, 2: cladding, and 3: core.

[0118] Thereafter, the slab waveguide sample was cut into a size of 50 mm x 50 mm using a DAC552 manufactured by Disco Corporation at 0.3 mm / sec so that the core was exposed.

[0119] Using the waveguide sample manufactured as described above, optical loss at a wavelength of 1310 nm was measured using the following method. Light from a 1310 nm LED light source was passed through an optical fiber with a core diameter of 10 μm and an NA of 0.12, and silicone oil was introduced into the end of the manufactured optical waveguide sample via matching oil (refractive index 1.505). Furthermore, an optical fiber with a core diameter of 50 μm and an NA of 0.21 was passed through the same matching oil, and the other side of the optical waveguide sample was connected to a power meter, and the power (P1) when an optical circuit was inserted was measured. In addition, the power (P0) measured by butting two similar optical fibers together without an optical circuit was also measured. From the measured value, the optical loss (1310 nm) was calculated using the formula -10 log (P1 / Po).

[0120] The evaluation criteria are as follows: A: Loss of 1.2 or less B: Loss of more than 1.2 and less than 1.5 C: Loss of more than 1.5

[0121] (Overall Evaluation) If none of the above three evaluations (Dk, Df, optical loss) received a C rating, the overall evaluation was determined to be A. On the other hand, if any of the evaluations received a C rating, the overall evaluation was determined to be B. Furthermore, if all of the evaluations received a C rating, the overall evaluation was determined to be C.

[0122] The results are shown in Table 1.

[0123]

[0124] <Evaluation and Discussion> From the results in Table 1, it was confirmed that the photosensitive resin compositions of the present invention used in the examples have excellent low dielectric properties in the cured products, and also suppress optical loss.

[0125] On the other hand, the comparative examples using resin compositions that did not satisfy the requirements of the present invention showed results inferior to those of the examples in at least some of the evaluation tests. Specifically, both comparative example 1, which used a (meth)acrylate monomer without a silicone structure, and comparative example 2, which did not use a radical polymerization initiator as a photopolymerization initiator, did not achieve sufficiently low dielectric properties and also showed large optical loss.

[0126] This application is based on Japanese Patent Application No. 2024-036174, filed on March 8, 2024, the contents of which are incorporated herein by reference.

[0127] In order to express the present invention, the present invention has been properly and sufficiently described above through embodiments with reference to specific examples, drawings, etc., but it should be recognized that those skilled in the art can easily make changes and / or improvements to the above-described embodiments. Therefore, unless changes or improvements made by those skilled in the art deviate from the scope of the claims set forth in the claims, such changes or improvements are construed as being encompassed within the scope of the claims.

[0128] The present invention has wide industrial applicability in the technical fields of optical waveguides, optoelectronic composite wiring boards, and interlayer insulating materials.

Claims

1. A photosensitive resin composition comprising a polyamic acid (A) having a photosensitive moiety, a (meth)acrylate monomer (B), and a photopolymerization initiator (C), wherein the (meth)acrylate monomer (B) contains a (meth)acrylate monomer (B1) having a silicone structure, and the silicone structure has a siloxane structure represented by the following formula (1) in its main chain, and the photopolymerization initiator (C) contains a radical polymerization initiator (C1). (wherein n represents an integer of 2 or more) 2. The photosensitive resin composition according to claim 1, wherein the content of the photopolymerization initiator (C) is 0.05 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the polyamic acid (A), the (meth)acrylate monomer (B), and the photopolymerization initiator (C).

3. The photosensitive resin composition according to claim 1, wherein the content of the (meth)acrylate monomer (B) is 3.00 parts by mass or more and 27.00 parts by mass or less per 100 parts by mass of the polyamic acid (A), the (meth)acrylate monomer (B), and the photopolymerization initiator (C).

4. The photosensitive resin composition according to claim 1, wherein the content of the polyamic acid (A) is 70.00 parts by mass or more and 95.00 parts by mass or less per 100 parts by mass of the total of the polyamic acid (A), the (meth)acrylate monomer (B), and the photopolymerization initiator (C).

5. The photosensitive resin composition according to claim 1, wherein the photosensitive moiety has a (meth)acrylate structure.

6. The photosensitive resin composition according to claim 1, wherein the polyamic acid (A) contains a fluorine atom.

7. The photosensitive resin composition according to claim 1, wherein the polyamic acid (A) has a silicone structure.

8. The photosensitive resin composition according to claim 1, wherein the (meth)acrylate monomer (B1) has an imide structure.

9. The photosensitive resin composition according to claim 1, wherein the radical polymerization initiator (C1) comprises an oxime ester initiator (c1).

10. A resin composition for optical waveguides, comprising the photosensitive resin composition according to any one of claims 1 to 9.

11. An interlayer insulating resin composition comprising the photosensitive resin composition according to any one of claims 1 to 9.

12. The resin composition for interlayer insulation according to claim 11, further comprising an inorganic filler (D).

13. A resin-coated film having a resin layer containing the photosensitive resin composition according to any one of claims 1 to 9 or a semi-cured product of said photosensitive resin composition, and a support film.

14. A liquid material comprising the photosensitive resin composition according to any one of claims 1 to 9.

15. An optical waveguide formed using the resin composition for an optical waveguide according to claim 10.

16. An optical waveguide substrate comprising the optical waveguide according to claim 15.

17. A semiconductor package comprising the optical waveguide substrate according to claim 16.

18. An interlayer insulating layer formed using the interlayer insulating resin composition according to claim 11.

19. A wiring board comprising the interlayer insulating layer according to claim 18.

20. A semiconductor package comprising the wiring substrate according to claim 19.

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