阅读说明：本技术 粘接剂组合物、热固性粘接片以及印刷电路板 (Adhesive composition, thermosetting adhesive sheet, and printed wiring board ) 是由 山本润 峯岸利之 伊达和宏 于 2019-01-21 设计创作，主要内容包括：本发明提供介电常数和介电损耗角正切低,耐弯折性良好的粘接剂组合物。在粘接剂组合物中,相对于该粘接剂组合物的合计100质量份,含有：75～90质量份的苯乙烯系弹性体、3～25质量份的末端具有聚合性基团的改性聚苯醚树脂、以及合计10质量份以下的环氧树脂和环氧树脂固化剂。(The invention provides an adhesive composition having low dielectric constant and dielectric loss tangent and good bending resistance. The adhesive composition contains, per 100 parts by mass of the total amount of the adhesive composition: 75 to 90 parts by mass of a styrene elastomer, 3 to 25 parts by mass of a modified polyphenylene ether resin having a polymerizable group at the end, and 10 parts by mass or less in total of an epoxy resin and an epoxy resin curing agent.)

1. An adhesive composition comprising, based on 100 parts by mass of the total amount of the adhesive composition:

75-90 parts by mass of a styrene elastomer;

3 to 25 parts by mass of a modified polyphenylene ether resin having a polymerizable group at the end; and

the total amount of the epoxy resin and the epoxy resin curing agent is 10 parts by mass or less.

2. The adhesive composition according to claim 1,

the styrene elastomer has a mass average molecular weight of 100000 or more.

3. The adhesive composition according to claim 1 or 2,

the styrene elastomer has a styrene ratio of less than 30%.

4. The adhesive composition according to any one of claims 1 to 3,

the modified polyphenylene ether resin is contained in an amount of 5 to 20 parts by mass.

5. The adhesive composition according to any one of claims 1 to 4,

the modified polyphenylene ether resin has at least one of an epoxy group and an ethylenically unsaturated bond at the terminal.

6. The adhesive composition according to any one of claims 1 to 5,

the epoxy resin curing agent is a latent epoxy resin curing agent.

7. A thermosetting adhesive sheet comprising a substrate and a thermosetting adhesive layer formed on the substrate, wherein the thermosetting adhesive layer is formed from the adhesive composition according to any one of claims 1 to 6.

8. A printed wiring board comprising a cured product of the adhesive composition according to any one of claims 1 to 6, wherein: the resin substrate with wiring comprises a substrate, a wiring pattern, a protective layer, and a wiring pattern side of the resin substrate with wiring.

9. The printed circuit board of claim 8,

the substrate is a liquid crystal polymer film.

Technical Field

The present technology relates to an adhesive composition, a thermosetting adhesive sheet, and a printed wiring board. The present application is based on the priority claim of japanese patent application No. 2018-.

Background

With the increase in speed and capacity of information communication, the trend of increasing the frequency of signals flowing through printed circuit boards has been accelerated. In order to cope with this, low dielectric characteristics such as a low dielectric constant and a low dielectric loss tangent are required for a constituent material (e.g., an adhesive composition) of a rigid substrate or a flexible printed circuit board (FPC) (see, for example, patent documents 1 and 2).

Further, although polyphenylene ether is advantageous in many cases as a material for a substrate having low dielectric characteristics, polyphenylene ether has a disadvantage of poor bending resistance because it has a very high melting point (softening point) and has a hard property at room temperature. For example, if the polyphenylene ether is contained in an amount of about 3 to 5 parts by weight based on the whole resin as in the resin composition described in patent document 2, the bending resistance tends to be poor.

Disclosure of Invention

Problems to be solved by the invention

The present technology has been made in view of the above-mentioned conventional circumstances, and provides an adhesive composition, a thermosetting adhesive sheet, and a printed wiring board, which have a low dielectric constant and a low dielectric loss tangent and are excellent in bending resistance.

Means for solving the problems

The adhesive composition of the present technology contains, relative to 100 parts by mass of the total amount of the adhesive composition: 75 to 90 parts by mass of a styrene elastomer, 3 to 25 parts by mass of a modified polyphenylene ether resin having a polymerizable group at the end, and 10 parts by mass or less in total of an epoxy resin and an epoxy resin curing agent.

The thermosetting adhesive sheet of the present technology has a thermosetting adhesive layer formed of the adhesive composition described above on a substrate.

The printed wiring board of the present technology has laminated via a cured product of the adhesive composition: the resin substrate with wiring includes a base material, a wiring pattern side, and a protective layer (cover).

Effects of the invention

According to the present technology, an adhesive composition having a low dielectric constant and a low dielectric loss tangent and excellent bending resistance can be provided.

Drawings

Fig. 1 is a sectional view showing an example of the configuration of a printed circuit board.

Fig. 2 is a sectional view showing an example of the structure of the multilayer printed wiring board.

Fig. 3 is a plan view showing an example of a configuration of a TEG used in a bending resistance test.

Fig. 4 is a perspective view showing a measuring apparatus used in the bending resistance test.

Detailed Description

Hereinafter, embodiments of the present technology will be described. The values of the weight average molecular weight and the number average molecular weight of the components described below are calculated from the molecular weight in terms of standard polystyrene measured by a Gel Permeation Chromatography (GPC) method.

< adhesive composition >

The adhesive composition of the present technology is a thermosetting adhesive composition, and contains, per 100 parts by mass of the total of the adhesive compositions: 75 to 90 parts by mass of a styrene elastomer (component A), 3 to 25 parts by mass of a modified polyphenylene ether resin having a polymerizable group at the end (component B; hereinafter, also simply referred to as modified polyphenylene ether resin), and 10 parts by mass or less in total of an epoxy resin (component C) and an epoxy resin curing agent (component D). By adopting such a constitution, an adhesive composition having a low dielectric constant and a low dielectric loss tangent after heat curing and having a good bending resistance after heat curing can be obtained. Such an adhesive composition can be suitably used as an adhesive (interlayer adhesive) for a flexible printed wiring board, for example.

[ styrene-based elastomer ]

Styrenic elastomer the styrenic elastomer is a copolymer of styrene and an olefin (for example, a conjugated diene such as butadiene or isoprene) and/or a hydrogenated product thereof. The styrene elastomer is a block copolymer having styrene as a hard segment and a conjugated diene as a soft segment. Examples of the styrene-based elastomer include: styrene/butadiene/styrene block copolymers, styrene/isoprene/styrene block copolymers, styrene/ethylene/butylene/styrene block copolymers, styrene/ethylene/propylene/styrene block copolymers, styrene/butadiene block copolymers, and the like. Further, a styrene/ethylene/butylene/styrene block copolymer, a styrene/ethylene/propylene/styrene block copolymer, a styrene/butadiene block copolymer (also referred to as a hydrogenated styrene-based elastomer), or the like in which a double bond of the conjugated diene component is eliminated by hydrogenation may be used.

The weight average molecular weight of the styrene elastomer is preferably 100000 or more, more preferably 100000 to 150000, and further preferably 110000 to 150000. By adopting such a configuration, the peel strength (connection reliability) and the heat resistance can be further improved.

The styrene content in the styrene elastomer is preferably less than 30%, more preferably 5% to 30%, still more preferably 5% to 25%, and particularly preferably 10% to 20%. With such a configuration, the bending resistance can be further improved, and the peel strength (connection reliability) and the heat resistance can be further improved.

Specific examples of the styrene-based elastomer include Tuftec H1221(Mw120000, styrene ratio 10%), Tuftec H1041(Mw90000, styrene ratio 30%), Tuftec H1043(Mw110000, styrene ratio 67%, manufactured by asahi chemical company, supra), HYBRAR 7125(Mw110000, styrene ratio 20%, manufactured by kohli). Among them, from the viewpoint of molecular weight and styrene ratio, Tuftec H1221 and HYBRAR 7125 are preferable.

The styrene-based elastomer content in the adhesive composition may be 75 to 90 parts by mass, or 80 to 90 parts by mass, based on 100 parts by mass of the total of the components a, B, C and D. When the content of the styrene-based elastomer is less than 75 parts by mass, the bending resistance tends to be poor. In addition, when the content of the styrene-based elastomer exceeds 90 parts by mass, the content of other components (for example, component B) is relatively reduced, and thus the heat resistance tends to be deteriorated. The styrene-based elastomer may be used alone or in combination of two or more.

[ modified polyphenylene ether resin ]

The modified polyphenylene ether resin has a polyphenylene ether chain in the molecule and a polymerizable group at the end. The modified polyphenylene ether resin preferably has at least one of 2 or more epoxy groups and ethylenically unsaturated bonds in 1 molecule as a polymerizable group. In particular, the modified polyphenylene ether resin preferably has at least one of an epoxy group and an ethylenically unsaturated bond (e.g., (meth) acryloyl group and vinylbenzyl group) at both ends, from the viewpoint of compatibility with the styrene-based elastomer and dielectric characteristics of the adhesive composition.

The polyphenylene ether resin not modified with the compound having a polymerizable group, that is, the polyphenylene ether resin having a hydroxyl group at the terminal is too polar, and therefore, the compatibility with the styrene-based elastomer is poor, and the adhesive composition may not be formed into a film, which is not preferable.

The modified polyphenylene ether resin having vinylbenzyl groups at both ends, which is an example of the modified polyphenylene ether resin, is obtained by, for example, subjecting terminal phenolic hydroxyl groups of a bifunctional phenylene ether oligomer obtained by oxidative coupling of a bifunctional phenol compound and a monofunctional phenol compound to vinylbenzyl etherification.

The modified polyphenylene ether resin preferably has a weight average molecular weight (or number average molecular weight) of 1000 to 3000 from the viewpoints of compatibility with the styrene-based elastomer, and step following property when the wiring pattern side of the resin substrate with wiring having a substrate and a wiring pattern and the protective layer are thermally cured (pressed) with the cured product of the adhesive composition.

Specific examples of the modified polyphenylene ether resin include OPE-2St (modified polyphenylene ether resin having vinylbenzyl groups at both ends), OPE-2Gly (modified polyphenylene ether resin having epoxy groups at both ends), OPE-2EA (modified polyphenylene ether resin having acryloyl groups at both ends, manufactured by Mitsubishi gas chemical Co., Ltd.), and Noryl SA9000 (modified polyphenylene ether resin having methacryloyl groups at both ends, manufactured by SABIC).

The content of the modified polyphenylene ether resin in the adhesive composition is 3 to 25 parts by mass, preferably 5 to 20 parts by mass, based on 100 parts by mass of the total of the component A, the component B, the component C and the component D. When the content of the modified polyphenylene ether resin exceeds 25 parts by mass, the bending resistance tends to be poor. Further, by setting the content of the modified polyphenylene ether resin to 5 parts by mass or more, the heat resistance can be further improved. The polyphenylene ether resin may be used alone or in combination of two or more.

[ epoxy resin ]

As the epoxy resin, for example, there are listed: epoxy resins having a naphthalene skeleton, bisphenol a type epoxy resins, bisphenol F type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins, siloxane type epoxy resins, biphenyl type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, hydantoin type epoxy resins, and the like. In particular, from the viewpoint of film formability, the epoxy resin is preferably an epoxy resin having a naphthalene skeleton, a bisphenol a type epoxy resin, or a bisphenol F type epoxy resin, and is liquid at room temperature. One kind of the epoxy resin may be used alone, or two or more kinds may be used in combination.

[ curing agent for epoxy resin ]

The epoxy resin curing agent is a catalyst for promoting the curing reaction of the epoxy resin. Examples of the epoxy resin curing agent include imidazole-based, phenol-based, amine-based, acid anhydride-based, and organic peroxide-based curing agents. In particular, from the viewpoint of the storage property (life) of the adhesive composition at room temperature, the epoxy resin curing agent is preferably a latent curing agent, and more preferably an encapsulated latent imidazole curing agent. The adhesive composition can be easily supplied and used because of its excellent storage property at room temperature. Specifically, as the epoxy resin curing agent, a microcapsule-type latent curing agent in which a latent imidazole modification is used as a core and the surface thereof is covered with polyurethane can be used. As a commercially available product, for example, Novacure 3941 (manufactured by Asahi Kasei corporation) can be used. One epoxy resin curing agent may be used alone, or two or more epoxy resin curing agents may be used in combination.

The total content of the epoxy resin and the epoxy resin curing agent in the adhesive composition is 10 parts by mass or less, preferably 5 parts by mass or less, with respect to 100 parts by mass of the total of the component a, the component B, the component C, and the component D. When the total content of the epoxy resin and the epoxy resin curing agent exceeds 10 parts by mass, the dielectric characteristics tend to be deteriorated.

[ other ingredients ]

The adhesive composition may contain other components than the components a to D described above within a range not to impair the effects of the present technology. Examples of the other components include an organic solvent, a silane coupling agent, and a filler for adjusting fluidity. The organic solvent is not particularly limited, and examples thereof include alcohol solvents, ketone solvents, ether solvents, aromatic solvents, and ester solvents. Among them, from the viewpoint of solubility, aromatic solvents and ester solvents are preferable. One kind of the organic solvent may be used alone, or two or more kinds may be used in combination.

< thermosetting adhesive sheet >

The thermosetting adhesive sheet of the present technology has a film shape in which a thermosetting adhesive layer formed of the adhesive composition is formed on a substrate. For example, the adhesive composition is diluted with a solvent, applied to at least one surface of a base material by a bar coater, roll coater or the like so that the thickness after drying is 10 to 60 μm, and dried at a temperature of about 50 to 130 ℃. As the substrate, a release substrate obtained by, for example, optionally subjecting a substrate such as a polyethylene terephthalate film or a polyimide film to a release treatment with silicone (silicone) can be used.

The thickness of the thermosetting adhesive layer constituting the thermosetting adhesive sheet may be appropriately set according to the purpose, and may be set to 1 to 100 μm or 1 to 30 μm, for example.

As described above, the thermosetting adhesive layer constituting the thermosetting adhesive sheet is formed of an adhesive composition having a low dielectric constant and a low dielectric loss tangent even after thermosetting and having a good bending resistance even after thermosetting, and therefore, is suitable for use in, for example, an interlayer adhesive for a flexible printed circuit board and an application for bonding and fixing a terminal portion of a flexible printed circuit board and a connecting base material for a backing thereof. Further, the thermosetting adhesive sheet has good peel strength and heat resistance after thermosetting and good storage properties at room temperature.

< printed Circuit Board >

The printed wiring board of the present technology has laminated via a cured product of the above adhesive composition (thermosetting adhesive layer): the wiring pattern side of the substrate with wiring, which is provided with a substrate and a wiring pattern, and a protective layer. The printed wiring board is obtained by, for example, arranging a thermosetting adhesive layer of a thermosetting adhesive sheet between the wiring pattern side of the wiring-provided base material and the protective layer, and thermocompression bonding the thermosetting adhesive layer to integrate the wiring-provided base material and the protective layer.

The wiring-provided substrate has excellent electrical characteristics in a high frequency range, as in the adhesive composition, and preferably has a low dielectric constant and a low dielectric loss tangent in a frequency range of 1 to 10GHz, for example. Specific examples of the substrate include substrates containing as a main component any of Liquid Crystal Polymers (LCP), polytetrafluoroethylene, polyimide, and polyethylene naphthalate. Among these substrates, a substrate (liquid crystal polymer film) containing a liquid crystal polymer as a main component is preferable. This is because the liquid crystal polymer has a very low moisture absorption rate as compared with polyimide, and is not easily affected by the use environment.

An example of the structure of a printed wiring board using the adhesive composition of the present technology will be described. In the printed circuit board 1 shown in fig. 1, a copper foil 3 side of a substrate with wiring (copper clad laminate: CCL) including a liquid crystal polymer film 2 and a copper foil (rolled copper foil) 3 and a liquid crystal polymer film 4 are laminated via a cured product layer 5 formed of the above adhesive composition (thermosetting adhesive layer).

In addition, the printed circuit board may have a multilayer structure as shown in fig. 2, for example. In the printed wiring board 6 shown in fig. 2, the copper plating layer 9 side of the wiring-attached base material having the polyimide layer 7 (thickness 25 μm), the copper foil 8 (thickness 18 μm), and the copper plating layer 9 (thickness 10 μm) and the protective layer 10 (thickness 25 μm) are laminated via the cured layer 5 (thickness 35 μm) formed of the above adhesive composition (thermosetting adhesive layer) (total thickness 201 μm).