JP2023157050A - Resin composition with low dielectric constant - Google Patents

Abstract

To provide a resin composition and an adhesive that are sufficiently low in dielectric constant and dielectric loss tangent, and enable a substrate and copper foil to be bonded to each other only by heating without pressurization, ensuring bonding strength adequate for practical use.SOLUTION: A resin composition includes: a hydrogenated block copolymer composed of styrene and butadiene; a hydrogenated block copolymer including styrene and ethylene; a crosslinker or/and tackifier; and a silane coupling agent. The combined content of the crosslinker and the tackifier is 5-25 wt.% based on the total solid content.SELECTED DRAWING: None

Description

The present invention relates to a resin composition having low dielectric properties and an adhesive for copper-clad laminates using the same.

In recent years, electronic devices such as smartphones have rapidly become more sophisticated and functional, and the materials for electronic components used in electronic devices are also becoming more and more important in terms of physical properties such as heat resistance, mechanical strength, and electrical properties. Further improvements are required. For example, printed wiring boards on which capacitors and semiconductor components are mounted are required to have higher density and higher functionality.

In order to respond to the high speed transmission signals required for high-definition, fast-moving video, etc., electrical characteristics that can suppress signal delay and transmission loss in the high frequency range are required, and rigid printed wiring boards and BACKGROUND ART Constituent materials (for example, adhesive compositions) of flexible printed wiring boards (hereinafter referred to as FPCs) are required to have low dielectric properties such as low dielectric constant and low dielectric loss tangent (Patent Document 1).

Polyphenylene ether is well known as a substrate material with such low dielectric properties, but when used as an adhesive sheet for bonding a substrate and copper foil, it is sandwiched between adherends such as polyimide or copper foil and heated. At the same time, it was necessary to apply high pressure for bonding. However, this method is unsuitable for roll-to-roll production and has poor productivity, and also has the problem that adhesive strength is unstable unless equipment capable of applying sufficient pressure is available. Therefore, there has been a need for an adhesive with low dielectric properties that can bond a base material and copper foil together by heating alone without applying pressure.

JP2016-79354A

The present invention aims to provide a resin composition and an adhesive that have sufficiently low dielectric constants and dielectric loss tangents, and that can bond a base material and copper foil together by heating alone without applying pressure, and exhibit adhesive strength that can withstand practical use. be.

In order to solve the above problem, the invention as claimed in claim 1 provides a hydrogenated block copolymer (A) consisting of styrene and butadiene, and a hydrogenated block copolymer (B) containing styrene and ethylene (provided that (A) ), a crosslinking agent (C) or/and a tackifier (D), and a silane coupling agent (E), and the total blending ratio of (C) and (D) is the total solid content. Provided is a resin composition characterized in that the amount is 5 to 25% by weight.

The invention according to claim 2 provides the resin composition according to claim 1, wherein the (C) is a styrene oligomer.

The invention according to claim 3 provides the resin composition according to claim 1 or 2, wherein the (D) is triallylisocyanurate.

Furthermore, the invention according to claim 4 provides the resin composition according to claim 1 or 2, characterized in that the amount of (C) blended is 3 to 12% by weight based on the total solid content.

Furthermore, the invention according to claim 5 provides the resin composition according to claim 1 or 2, which is an adhesive for copper-clad laminates.

The resin composition of the present invention has a sufficiently low dielectric constant and dielectric loss tangent, and can develop adhesion strength that can withstand practical use just by heating without applying pressure. Useful as a bonding adhesive.

The present invention will be explained in detail below.

The composition of the resin composition of the present invention is a hydrogenated block copolymer (A) consisting of styrene and butadiene (hereinafter referred to as hydrogenated), a hydrogenated block copolymer (B) containing styrene and ethylene, They are a crosslinking agent (C), a tackifier (D), and a silane coupling agent (E). In this specification, (meth)acrylate includes both acrylate and methacrylate.

The hydrogenated block copolymer (A) consisting of styrene and butadiene used in the present invention is obtained by hydrogenating a block copolymer consisting of a polystyrene block as a hard segment and polybutadiene as a soft segment, and has rubber elasticity over a wide range of temperatures. It is a thermoplastic polymer (hereinafter referred to as SEBS: styrene-ethylene-butylene-styrene). Compared to non-hydrogenated styrene-butadiene block copolymer (hereinafter referred to as SBS), it has particularly excellent weather resistance, heat aging resistance, and low-temperature processability.

(A) may be partially hydrogenated (hereinafter referred to as SBBS: styrene-butadiene-butylene-styrene), but fully hydrogenated SEBS has better weather resistance and heat resistance, and at the same time, (B) It is preferable because the compatibility with (C) is improved. Further, amine modification or acid modification tends to improve the elongation rate when formed into a sheet, which is particularly preferable. With non-hydrogenated SBS, there may be concerns that the compatibility with (B) and (C) may decrease, or that adhesive strength may decrease over time. Commercially available products include the Tuftec H series (trade name: manufactured by Asahi Kasei Corporation, SEBS), the Tuftec M series (maleic acid-modified SEBS), and the Tuftec MP series (amine-modified SEBS).

The styrene ratio in (A) is preferably 15 to 70% by weight, more preferably 18 to 40% by weight, particularly preferably 20 to 35% by weight. By setting the content to 15% by weight or more, sufficient tensile strength can be ensured, and by setting the content to 70% by weight or less, sufficient elastic force can be ensured.

The blending ratio of (A) is preferably 20 to 60% by weight, more preferably 25 to 55% by weight, and particularly preferably 30 to 50% by weight based on the total solid content of the composition. By setting the content to 20% by weight or more, sufficient cohesive force and heat resistance can be ensured when formed into a sheet, and by setting the content to 60% by weight or less, sufficient low dielectric properties can be ensured.

The hydrogenated block copolymer (B) containing styrene and ethylene used in the present invention can be expected to have the effect of improving dielectric properties and increasing elongation when formed into a sheet, such as styrene-ethylene/propylene. Hydrogenated diblock copolymer, hydrogenated block copolymer of styrene-ethylene-ethylene/propylene-styrene (hereinafter referred to as SEEPS), hydrogenated block copolymer of styrene-ethylene/propylene-styrene (hereinafter referred to as SEPS) These can be used alone or in combination of two or more types. Among these, SEEPS and SEPS are preferred in terms of their excellent compatibility with (A). Commercially available products include the Septon 2000 series (trade name: manufactured by Kuraray Co., Ltd., SEPS) and the Septon 4000 series (SEEPS). Note that ethylene/propylene indicates that the copolymerization portion of ethylene and propylene is not a block copolymerization but a random copolymerization.

The styrene ratio in (B) is preferably 15 to 40% by weight, more preferably 18 to 35% by weight. By setting the content to 15% by weight or more, a sufficient elongation rate can be ensured, and by setting the content to 40% by weight or less, gelation can be suppressed and sufficient storage stability can be ensured.

The blending ratio of (B) is preferably 20 to 50% by weight, more preferably 25 to 45% by weight, particularly preferably 28 to 40% by weight based on the total solid content of the composition. By setting the content to 20% by weight or more, a sufficient elongation rate can be ensured, and by setting the content to 50% by weight or less, sufficient storage stability can be ensured without decreasing compatibility.

The crosslinking agent (C) used in the present invention is a compound having a polyfunctional unsaturated double bond, and is blended for the purpose of improving adhesive strength even without pressure during heating. By blending (C), the crosslinking density becomes higher during the curing reaction (crosslinking reaction), and it is expected that the heat resistance of the cured product of the resin composition will be improved. The number of functional groups is preferably 2 to 6 functional, more preferably 2 to 4 functional. A sufficient crosslinking reaction can be expected when the functional content is 2 or more, and curing shrinkage can be suppressed when the functional content is 6 functional or less.

Examples of (C) include trialkenyl isocyanurate compounds such as triallyl isocyanurate, trialkenyl cyanurate compounds such as triallyl cyanurate, and polyfunctional (meth)acryloyl groups having two or more (meth)acryloyl groups in the molecule. Examples include polyfunctional vinyl compounds having two or more vinyl groups in the molecule, such as acryloyl compounds and polybutadiene, which can be used alone or in combination of two or more types. Among these, triallylisocyanurate is preferred because it has good compatibility with (A) and (B) and does not easily affect dielectric properties.

The blending ratio of (C) is preferably 20% by weight or less, more preferably 3 to 18% by weight, and particularly preferably 8 to 16% by weight based on the total solid content of the composition. By controlling the content to 20% by weight or less, the peeling force can be sufficiently improved without significantly increasing the dielectric loss tangent.

The tackifier (D) used in the present invention, like (C) above, is blended for the purpose of improving adhesive strength even without pressure during heating. The softening point is preferably 85 to 110°C, more preferably 90 to 105°C. By setting the temperature to 85°C or higher, sufficient heat resistance of the cured product can be ensured, and by setting the temperature to 110°C or lower, sufficient initial adhesive strength can be ensured when laminating the base material and copper foil. .

Examples of (D) include rosin derivatives, terpene resins, styrene (co)polymers, coumaron resins, terpene-phenol resins, petroleum hydrocarbon resins, etc., which may be used alone or in combination of two or more. can be used. Among these, styrenic oligomers are preferred because they have good compatibility with (A), (B) and (C) and good thermal stability.

The blending ratio of (D) is preferably 15% by weight or less, more preferably 3 to 12% by weight, and particularly preferably 5 to 10% by weight based on the total solid content of the composition. Sufficient peeling force can be ensured by setting the amount to 15% by weight or less. The total blending ratio of (C) and (D) is 5 to 25% by weight, preferably 8 to 24% by weight, and more preferably 12 to 24% by weight, based on the total solid content of the composition. If it is less than 5% by weight, sufficient peeling force may not be ensured, and if it exceeds 25% by weight, the dielectric properties may deteriorate, such as the dielectric loss tangent increasing, or the peeling force may decrease.

The silane coupling agent (E) used in the present invention has a functional group bonding to an organic material and an inorganic material in its molecule, and is blended for the purpose of improving mechanical strength and adhesion. In particular, heating accelerates hydrolysis and dehydration condensation, improving the peeling force. Examples of functional groups that react with organic materials include vinyl groups, epoxy groups, amino groups, methacrylic groups, and mercapto groups, and hydrolyzable silyl groups react with inorganic materials. Among these, the oligomer type (hereinafter referred to as oligomer type) has an epoxy functional group with high heat resistance and low volatility due to its large molecular weight and bulky structure, and the isocyanurate skeleton which is highly effective in improving adhesive strength and heat resistance. It is preferable to include a type having the following (hereinafter referred to as isocyanurate type), and it is more preferable to use both types in combination. Examples of oligomer-based commercial products include COATOSIL MP 200 (trade name: manufactured by Momentive), and examples of isocyanurate-based commercial products include KBM9659 (trade name: manufactured by Shin-Etsu Chemical Co., Ltd.).

The blending ratio of (E) is preferably 0.1 to 5% by weight, more preferably 0.5 to 3.0% by weight, based on the total solid content of the composition. By setting it as this range, sufficient peel adhesive force can be ensured. Further, when oligomer type and isocyanurate type are used together, the ratio of oligomer type: isocyanurate type is preferably 1:1 to 4:1, more preferably 3:2 to 3:1.

The composition of the present invention may further contain an organic peroxide (F). In particular, when (C) is blended, it is preferable to include (F). (F) acts as a polymerization initiator and is cleaved by heating to generate radicals. For example, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butyl peroxide) hexane, 2,5-dimethyl-2,5-di(t-butyl peroxide) hexine-3 , t-butylcumyl peroxide, α,α'-di-(t-butylperoxy)diisopropylbenzene, t-butylperoxybenzoate, etc., and can be used alone or in combination of two or more types. Commercially available products include Perbutyl P and Perbutyl D (trade name: manufactured by NOF Corporation).

The blending ratio of (F) is preferably 1 to 10 parts by weight, more preferably 3 to 8 parts by weight, based on 100 parts by weight of radical reaction component (C). By keeping it within this range, sufficient curability can be ensured without excessive addition.

Additives such as antioxidants, flame retardants, ultraviolet absorbers, light stabilizers, inorganic fillers, and organic fine particles can be added to the resin composition of the present invention as long as the performance is not impaired.

By blending the antioxidant, it is possible to prevent deterioration of the physical properties of the film after curing. Examples of antioxidants include phenol-based, phosphorus-based, phenol-phosphorus, and sulfur-based antioxidants, which can be used alone or in combination of two or more. The amount of antioxidant added is preferably 5% by weight or less, more preferably 2% by weight or less based on the total solid content. Commercially available products include Sumilizer GP (trade name: manufactured by Sumitomo Chemical Co., Ltd., phenol phosphorus type).

When using the composition of the present invention, for example, it is dissolved in a parent solvent such as toluene, applied as a solution to a base film, dried, laminated with copper foil, bonded, and cured by heating. let When bonding or laminating copper foil, it is necessary to apply pressure to the extent that the base material and copper foil are in close contact and no air bubbles remain, but there is no need to apply pressure when heating. Suitable for continuous production such as roll to roll.

The thickness of the adhesive layer is exemplified to be 10 to 50 μm, but is not particularly limited and can be freely set depending on the application and the type of adherend. Heating during curing is necessary to promote the hydrolysis and dehydration condensation of (E) and at the same time cleave (F) to cause a thermal radical reaction. Although 80 minutes is exemplified, it can be set arbitrarily depending on the types of (E) and (F) and the type of base material.

Hereinafter, the present invention will be explained in detail based on Examples and Comparative Examples, but these are intended to be specific examples and are not particularly limited to these. Unless otherwise specified, the measurements were performed at a room temperature of 25° C. and a relative humidity of 65%. Note that the blending amount indicates parts by weight.

Examples and Comparative Examples In a container, Tuftec MP10 (trade name: manufactured by Asahi Kasei Corporation, hydrogenated amine-modified SEBS, styrene ratio 30%) was placed as (A), and Septon 4044 (as (B)) was placed in a container. Product name: SEEPS, manufactured by Kuraray Co., Ltd. (styrene ratio 32%), TAIC (product name: Nippon Kasei Co., Ltd., triallyl isocyanurate) as the above (C), FTR6100 (product name: Mitsui Chemicals) as the above (D) COATOSILMP200 (trade name: manufactured by Momentive, epoxy functional group) and KBM9659 (trade name: manufactured by Shin-Etsu Chemical Co., Ltd., isocyanurate type), and Perbutyl P (trade name: manufactured by Nippon Oil & Fats Co., Ltd., α,α'-di-(t- butylperoxy) diisopropylbenzene), Sumilizer GP (trade name: Sumitomo Chemical, phenol phosphorus antioxidant) as an additive in the amounts shown in Tables 1 and 2, and toluene so that the solid content is 20%. In addition, the resin compositions of Examples 1 to 10 and Comparative Examples 1 to 5 were prepared by mixing and stirring.

Preparation of laminate for evaluation The resin composition obtained above was placed on Kapton 200H (trade name: polyimide film, manufactured by DuPont-Toray) with a thickness of 50 μm so that the thickness after drying would be 25 μm. After applying it evenly, drying it in an oven at 80°C for 5 minutes to volatilize the toluene, apply 120% to the rough surface of a 12 μm thick copper foil CF-T9FZ-HS-12 (trade name: manufactured by Fukuda Metal Foil and Powder Industries Co., Ltd.). ℃ and 0.2 MPa, and the adhesive layer was cured at 180° C. for 1 hour to create a laminate.

The evaluation method was as follows.

Specific permittivity: The resin composition obtained above was uniformly applied onto a release PET film (50 μm) so that the thickness after drying was 25 μm, and then dried in an oven at 80°C for 5 minutes to volatilize toluene. Release PET films with different peeling forces were bonded together and cured at 180°C for 1 hour to prepare a measurement sample.A network analyzer MS46122B manufactured by Anritsu Corporation and a measurement resonator manufactured by AET Corporation 10 GHz TE mode were used. The relative dielectric constant was measured at a frequency of 10 GHz and a measurement temperature of 25° C., and 3.0 or less was rated ○, and more than 3.0 was rated ×.

Dielectric loss tangent: Measure the dielectric loss tangent at a frequency of 10 GHz and a measurement temperature of 25°C using the same sample as the specific dielectric constant, and ◎ if it is less than 0.0030, 〇, or 0 if it is from 0.0030 to 0.0033. Values exceeding .0033 were marked as x.

Peeling force: Using the laminate prepared above, cut it into 10 mm width x 150 mm length, and test the 90° peel strength of the copper foil using a Minebea tensile tester TGI-1kN at a crosshead speed of 50 mm/ min. Measured at a measurement temperature of 25° C., 0.8 N/cm or more is ◎, 0.5 to 0.8 N/cm is ○, and less than 0.5 N/cm is ×.

Evaluation Results The evaluation results are shown in Tables 3 and 4.

The resin compositions of Examples obtained good results in all evaluation items of dielectric constant, dielectric loss tangent, and peeling force.

On the other hand, Comparative Examples 1 and 2 in which the total content of (C) and (D) exceeds 25% by weight have high dielectric loss tangents, and Comparative Examples 3 and 4, which do not contain (E) and (B), have low peeling force. , Comparative Example 5, which does not contain (A), had poor compatibility and was not suitable for the present invention.

Claims (5)

A hydrogenated block copolymer (A) consisting of styrene and butadiene, a hydrogenated block copolymer (B) containing styrene and ethylene (excluding (A)), a crosslinking agent (C) or/and It is characterized in that it contains a tackifier (D) and a silane coupling agent (E), and the total blending ratio of (C) and (D) is 5 to 25% by weight based on the total solid content. Resin composition. The resin composition according to claim 1, wherein the (C) is a styrene oligomer. The resin composition according to claim 1 or 2, wherein the (D) is triallylisocyanurate. 3. The resin composition according to claim 1, wherein the amount of (C) is 3 to 12% by weight based on the total solid content. 3. The resin composition according to claim 1, which is an adhesive for copper-clad laminates.