JP7444319B1 - Adhesive composition, adhesive sheet, laminate, and printed wiring board containing the same - Google Patents

Abstract

[Problem] The present invention provides an adhesive composition that has excellent solder heat resistance and adhesive strength, has good circuit embedding properties, and has excellent dielectric properties with low relative dielectric constant and dielectric loss tangent, and an adhesive sheet containing the same. , provides laminates and printed wiring boards. [Solution] The adhesive composition of the present invention is an adhesive composition containing an acid-modified resin, a compound (A), and an epoxy resin (B), wherein the content of the compound (A) is It is characterized by being 10 parts by mass or more and 40 parts by mass or less per 100 parts by mass. Compound (A): A propylene-ethylene compound that does not have a heteroatom, has a weight average molecular weight of 10,000 to 70,000, and has a solubility in cyclohexane of 25 g/100 g-C6H12 or more at 25°C. Polymer. [Selection diagram] None

Description

The present invention relates to adhesive compositions. More specifically, the present invention relates to an adhesive composition used for bonding a resin base material and a resin base material or a metal base material. In particular, the present invention relates to an adhesive composition for flexible printed wiring boards (hereinafter abbreviated as FPC), as well as adhesive sheets, laminates, and printed wiring boards containing the same.

Because FPC has excellent flexibility, it can support multi-functionality and miniaturization of personal computers (PCs) and smartphones, and is often used to incorporate electronic circuit boards into narrow and complex interiors. . BACKGROUND ART In recent years, electronic devices have become smaller, lighter, more dense, and have higher output, and demands on the performance of wiring boards (electronic circuit boards) have become increasingly sophisticated. In particular, high frequency signals are being used to increase transmission speed. Along with this, there is an increasing demand for FPCs to have low dielectric properties (low dielectric constant, low dielectric loss tangent) in a high frequency region. In order to achieve such low dielectric properties, measures have been taken to reduce the dielectric loss of FPC base materials and adhesives, and the base materials used in FPCs are conventional polyimide (PI) and polyethylene terephthalate ( In addition to PET), base films made of liquid crystal polymer (LCP) and fluororesin, which have low dielectric properties, have been proposed. As adhesives, the development of combinations of polyolefin and epoxy (Patent Document 1, Patent Document 3) and adhesives using polyphenylene ether (Patent Document 2) are progressing.

Furthermore, in recent years, the electronic circuits of FPCs have become increasingly finer. By narrowing the circuit width of electronic circuits to around 25 μm, it is possible to form high-density circuits, but some adhesives cannot completely fill in the spaces between such minute circuits. Insulation failure will occur.

International Publication No. 2016/047289 International Publication No. 2020/196718 Patent No. 7192848

However, since the adhesive described in Patent Document 1 contains an epoxy resin and an epoxy resin curing agent, it has high polarity and cannot satisfy particularly high requirements for dielectric loss tangent. The adhesive described in Patent Document 2 cannot be said to have excellent heat resistance as an FPC adhesive, and also has insufficient dielectric properties. Although the adhesive described in Patent Document 3 improves dielectric properties by further adding an unmodified polyolefin to a mixture of acid-modified polyolefin and epoxy resin, the molecular weight of the unmodified polyolefin added is large and it is difficult to melt. Due to its high viscosity, circuit embedding is insufficient and there is a risk of insulation failure.

The present invention has been made against the background of such prior art problems. That is, an object of the present invention is to provide an adhesive composition that has excellent solder heat resistance and adhesive strength, has good circuit embedding properties, and has excellent dielectric properties with low relative dielectric constant and dielectric loss tangent, and an adhesive composition containing the same. The present invention provides sheets, laminates, and printed wiring boards.

As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by the means shown below, and have arrived at the present invention. That is, the present invention consists of the following configuration.

[1] An adhesive composition containing an acid-modified resin, a compound (A) and an epoxy resin (B),
An adhesive composition characterized in that the content of the compound (A) is 10 parts by mass or more and 40 parts by mass or less based on 100 parts by mass of the acid-modified resin.
Compound (A): propylene that does not have a heteroatom, has a weight average molecular weight of 10,000 or more and 70,000 or less, and has a solubility in cyclohexane of 25g/100g-C ₆ H ₁₂ or more at 25°C -Ethylene copolymer.
[2] The adhesive composition according to [1], wherein the acid-modified resin is an acid-modified polyolefin.
[3] The adhesive composition according to [1] or [2], wherein the epoxy resin (B) is a polyfunctional epoxy resin.
[4] The adhesive composition according to any one of [1] to [3], wherein the compound (A) has a melt viscosity at 170° C. of 10,000 mPa·s or less.
[5] An adhesive sheet containing the adhesive composition according to any one of [1] to [4].
[6] A laminate containing the adhesive composition according to any one of [1] to [4].
[7] A printed wiring board comprising the laminate according to [6] as a component.

The adhesive composition of the present invention has excellent solder heat resistance and adhesive strength, as well as good circuit embedding properties and excellent dielectric properties. Therefore, it is suitable for FPC adhesives, adhesive sheets, laminates, and printed wiring boards in the high frequency range.

Hereinafter, one embodiment of the present invention will be described in detail below. However, the present invention is not limited thereto, and can be implemented with various modifications within the scope described above.

<Adhesive composition>
The adhesive composition of the present invention is an adhesive composition containing an acid-modified resin, a compound (A), and an epoxy resin (B), and the content of the compound (A) is based on 100 parts by mass of the acid-modified resin. It is characterized in that the amount is 10 parts by mass or more and 40 parts by mass or less.
Compound (A): propylene that does not have a heteroatom, has a weight average molecular weight of 10,000 or more and 70,000 or less, and has a solubility in cyclohexane of 25g/100g-C ₆ H ₁₂ or more at 25°C -Ethylene copolymer.
In the present invention, by blending a predetermined amount of a compound (A) having specific properties into an adhesive composition containing an acid-modified resin and an epoxy resin (B), the adhesive composition has excellent soldering heat resistance and adhesive strength, and is further improved in circuit embedding. An adhesive composition having good embedding properties and excellent dielectric properties is provided.

<Compound (A)>
The compound (A) in the present invention does not have a heteroatom, has a weight average molecular weight of 10,000 or more and 70,000 or less, and has a solubility in cyclohexane of 25 g/100 g-C ₆ H ₁₂ at 25°C. This is a propylene-ethylene copolymer having the above properties. By not containing heteroatoms, the adhesive can have excellent dielectric properties. Further, the present inventors have investigated and found that by lowering the weight average molecular weight of compound (A), it is possible to fill the gaps between the circuits with an adhesive so that there are no gaps even in electronic circuits with narrow circuit widths. By specifically selecting a propylene-ethylene copolymer as the compound (A), crosslinking properties can be improved compared to other polyolefin resins, thereby providing an adhesive composition with excellent soldering heat resistance. I found out. The adhesive composition of the present invention, which has excellent soldering heat resistance and exhibits good circuit embedding properties, is extremely useful from the viewpoint of improving the insulation properties of printed circuit boards.

Compound (A) does not have a heteroatom (e.g., nitrogen atom, oxygen atom, sulfur atom, chlorine atom, etc.) means that compound (A) does not have atoms other than carbon atoms and hydrogen atoms in its molecular structure. (ie, compound (A) is a propylene-ethylene copolymer consisting of carbon atoms and hydrogen atoms). Compound (A) particularly refers to an unmodified propylene-ethylene copolymer, and more specifically refers to a propylene-ethylene copolymer that has not been modified with an acid.

The propylene-ethylene copolymer of compound (A) is mainly composed of propylene and ethylene is copolymerized therewith. The ratio of the propylene component to ethylene in the propylene-ethylene copolymer is not limited, but the proportion of the propylene component is preferably 50 mol% or more, more preferably 70 mol% or more. Furthermore, these raw materials are not limited to petroleum-derived raw materials, but may also be raw materials obtained using chemical recycling technology that utilizes biomass naphtha or waste plastics.

The weight average molecular weight (Mw) of the compound (A) is preferably 11,000 or more and 52,000 or less, more preferably 12,000 or more and 47,000 or less, still more preferably 13,000 or more and 42,000 or less, and even more preferably Preferably it is 14,000 or more and 35,000 or less, particularly preferably 15,000 or more and 29,000 or less. By setting it below the above-mentioned upper limit, fluidity becomes good and excellent circuit embeddability can be exhibited. Further, by setting the amount to be equal to or higher than the lower limit, excellent soldering heat resistance can be exhibited.

The solubility of compound (A) in cyclohexane at 25° C. is preferably 30 g/100 g-C ₆ H ₁₂ or more, more preferably 40 g/100 g-C ₆ H ₁₂ or more, and even more preferably 50 g/100 g-C ₆ H ₁₂ or more, even more preferably 100 g/100 g-C ₆ H ₁₂ or more, particularly preferably 150 g/100 g-C ₆ H ₁₂ or more, particularly preferably 200 g/100 g-C ₆ H ₁₂ or more, and the upper limit is particularly Although not limited, it is preferably 3,000g/100g-C ₆ H ₁₂ or less, more preferably 2,000g/100g-C ₆ H ₁₂ or less, even more preferably 1,000g/100g-C ₆ H ₁₂ or less It is particularly preferably 800 g/100 g-C ₆ H ₁₂ or less, particularly preferably 500 g/100 g-C ₆ H ₁₂ or less. If the amount is below the lower limit, the compound (A) may not be dissolved in the solvent and an adhesive composition may not be obtained. On the other hand, by setting it below the above-mentioned upper limit, an adhesive composition with excellent workability can be obtained.

The melting point of compound (A) is, for example, 60°C or more and 250°C or less, preferably 70°C or more and 150°C or less, more preferably 75°C or more and 120°C or less, and still more preferably 80°C or more and 100°C or less. By setting the melting point of compound (A) to be equal to or higher than the lower limit, an adhesive composition with excellent workability can be obtained. Further, by setting the amount to be below the upper limit, the reaction with the epoxy resin (B) after circuit embedding becomes good, which is advantageous for improving crosslinking density (improving heat resistance).

The melt viscosity of compound (A) at 170° C. is, for example, 10,000 mPa·s or less, preferably 7,000 mPa·s or less, more preferably 5,000 mPa·s or less, and still more preferably 3,000 mPa·s or less. . Considering the effect of compound (A) on circuit embedding, it is preferable that the melt viscosity at 170°C be as low as possible. Although the lower limit is not particularly limited, it is generally 10 mPa·s or more.

The content of compound (A) in the adhesive composition of the present invention is preferably 15 parts by mass or more and 37 parts by mass or less, more preferably It is 25 parts by mass or more and 35 parts by mass or less. If the upper limit is exceeded, the amount of acid-modified resin will be relatively reduced, and the crosslinking density will be lowered, so that soldering heat resistance may deteriorate. On the other hand, if it is less than the lower limit, the effect of compound (A) will not be sufficiently exhibited, and circuit embeddability may deteriorate. Furthermore, as the content of compound (A) increases, the dielectric loss tangent tends to improve. That is, by setting the content within the above upper and lower limits, excellent dielectric properties, solder heat resistance, and circuit embedding properties can be achieved.

The solubility, melting point, melt viscosity, and weight average molecular weight in the present invention were determined using the following methods.

(solubility)
A saturated solution of the resin was prepared by mixing 100 g of cyclohexane and the resin at 25° C. for 1 hour, and the concentration of the resin in the obtained saturated solution (g/100 g-C ₆ H ₁₂ ) was defined as the solubility.

(Weight average molecular weight (Mw))
The weight average molecular weight in the present invention is determined by gel permeation chromatography (GPC, standard material: polystyrene resin, mobile phase: tetrahydrofuran, column: Shodex KF-802 + KF-804L + KF-806L, manufactured by Shimadzu Corporation). Temperature: 30°C, flow rate: 1.0 ml/min, detector: RI detector).

(Measurement of melting point)
The melting point in the present invention is determined using a differential scanning calorimeter (hereinafter referred to as DSC, manufactured by TA Instruments Japan, Q-2000), by heating and melting at a rate of 20°C/min, cooling to form a resin, and then re-melting. This is the value measured from the top temperature of the melting peak when melting at elevated temperature.

(melt viscosity)
The melt viscosity is a value measured according to DIN 53019 using a rotational viscometer at 170°C.

Note that the adhesive composition according to the present invention may contain a polyolefin resin having no heteroatoms other than compound (A) (hereinafter referred to as compound (AZ)). The polyolefin resin of compound (AZ) refers to homopolymerization of olefin monomers such as ethylene, propylene, butene, butadiene, isoprene, etc., or copolymerization with other monomers, and hydrides and halogens of the resulting polymer. Refers to polymers mainly having a hydrocarbon skeleton, such as compounds, and includes cycloolefin polymers as well as propylene-α-olefin copolymers (excluding compound (A)).

The propylene-α-olefin copolymer in compound (AZ) is mainly composed of propylene and copolymerized with α-olefin. As the α-olefin, for example, one or more of ethylene, 1-butene, 1-heptene, 1-octene, 4-methyl-1-pentene, vinyl acetate, etc. can be used. Among these α-olefins, ethylene and 1-butene are preferred. The ratio of the propylene component to the α-olefin component of the propylene-α-olefin copolymer is not limited, but the proportion of the propylene component is preferably 50 mol% or more, more preferably 70 mol% or more. Furthermore, these raw materials are not limited to petroleum-derived raw materials, but may also be raw materials obtained using chemical recycling technology that utilizes biomass naphtha or waste plastics.

As the cycloolefin polymer in the compound (AZ), either a homopolymer (COP) made from only one type of cycloolefin monomer or a copolymer (COC) composed of one or more types of cycloolefin monomer and comonomer is used. can.

Examples of the cycloolefin monomer include bicyclics such as norbornene and norbornadiene, tricyclics such as dicyclopentadiene and dihydroxypentadiene, tetracyclics such as tetracyclododecene, and pentacyclics such as cyclopentadiene trimer. , heptacyclics such as tetracyclopentadiene, or alkyl (methyl, ethyl, propyl, butyl, etc.) substituted products, alkenyl (vinyl etc.) substituted products, alkylidene (ethylidene etc.) substituted products, aryl (phenyl, etc.) substituted products of these polycyclics Examples include tolyl, naphthyl, etc.) substituted products. Among these, norbornene monomers selected from the group consisting of norbornene, tetracyclododecene, and alkyl substituted products thereof are particularly preferred.

Further, the comonomer may be any monomer that can be copolymerized with the above-mentioned cycloolefin monomer, and for example, an alkene monomer is preferable. Examples of the alkene monomer include α-olefins such as ethylene, propylene, 1-butene, and 1-hexene, and isobutene. The alkene monomer may be linear or branched.

It is preferable that 50% by mass or more of the monomer component constituting the cycloolefin polymer is the cycloolefin monomer, more preferably 60% by mass or more is the cycloolefin monomer. When the cycloolefin monomer accounts for 50% by mass or more of the total monomer components, the soldering heat resistance will be good. There are no particular limitations on the polymerization method, polymerization conditions, etc. when polymerizing the monomer components, and they may be appropriately set according to conventional methods.

<Acid modified resin>
The acid-modified resin used in the present invention is a resin that has been modified using an acid component. By using an acid-modified resin, the adhesive layer has excellent adhesion to metal substrates such as copper foil, and has excellent solder heat resistance due to the crosslinking reaction with the epoxy group of the epoxy resin (B) described later. can be formed.

The acid-modified resin used in the present invention can be produced, for example, by modifying a base resin with an unsaturated carboxylic acid component, or by copolymerizing an unsaturated carboxylic acid component during polymerization of the base resin. I can do it. The unsaturated carboxylic acid component is not particularly limited, and is preferably at least one of α,β-unsaturated carboxylic acid and its acid anhydride, specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, Examples include fumaric acid, citraconic acid, maleic anhydride, itaconic anhydride, fumaric anhydride, citraconic anhydride, and the like. Among these, maleic acid, itaconic acid, citraconic acid, and acid anhydrides thereof are preferred, acid anhydrides are more preferred, and maleic anhydride is even more preferred.

The lower limit of the acid value of the acid-modified resin used in the present invention is preferably 10 equivalents/10 ⁶ g or more, more preferably 20 equivalents, from the viewpoint of heat resistance and adhesiveness to resin base materials and metal base materials. /10 ⁶ g or more, more preferably 30 equivalents/10 ⁶ g or more. By having the above value or more, the compatibility with the epoxy resin (B) etc. increases, the adhesive strength improves, and the crosslinking density increases, so that heat resistance can also be improved. The upper limit is preferably 1000 equivalents/10 ⁶ g or less, more preferably 700 equivalents/10 ⁶ g or less, still more preferably 500 equivalents/10 ⁶ g or less. When it is below the above value, adhesiveness and low dielectric properties will be better.

The weight average molecular weight (Mw) of the acid-modified resin used in the present invention is preferably in the range of 10,000 to 1,000,000. It is more preferably in the range of 20,000 to 500,000, still more preferably in the range of 40,000 to 200,000, particularly preferably in the range of 50,000 to 150,000. When the amount is equal to or more than the lower limit, the cohesive force becomes good and excellent adhesiveness can be exhibited. In addition, by setting the content to be below the upper limit value, the fluidity is excellent and the operability becomes good.

The acid-modified resin used in the present invention is preferably an acid-modified resin obtained by acid-modifying a resin mainly composed of hydrocarbons, since it has good low dielectric properties. For example, acid-modified polystyrene resin, acid-modified cyclo Olefin polymers and acid-modified polyolefins are preferred, and acid-modified polyolefins are more preferred. Furthermore, from the viewpoint of pot life, acid-modified polystyrene resins and acid-modified cycloolefin polymers are preferred. One type of acid-modified resin or a combination of two or more types can be used.

The acid-modified resin of the present invention preferably has a dielectric constant (εc) of 2.7 or less at a frequency of 10 GHz. More preferably it is 2.6 or less, still more preferably 2.3 or less. Although the lower limit is not particularly limited, it is practically 2.0. Further, the dielectric constant (εc) in the entire frequency range of 1 GHz to 60 GHz is preferably 2.7 or less, more preferably 2.6 or less, and even more preferably 2.3 or less.

The acid-modified resin of the present invention preferably has a dielectric loss tangent (tan δ) of 0.003 or less at a frequency of 10 GHz. It is more preferably 0.0025 or less, even more preferably 0.002 or less. Although the lower limit is not particularly limited, it is practically 0.0001 or more. Further, the dielectric loss tangent (tan δ) in the entire frequency range of 1 GHz to 60 GHz is preferably 0.003 or less, more preferably 0.0025 or less, and even more preferably 0.002 or less.

The content of the acid-modified resin in the adhesive composition of the present invention is preferably 10% by mass or more, more preferably 20% by mass or more, and more preferably 40% by mass or more based on 100% by mass of the solid content of the adhesive composition. is even more preferable. Further, it is preferably 99% by mass or less, more preferably 95% by mass or less, even more preferably 90% by mass or less, even more preferably 85% by mass or less, particularly preferably 80% by mass or less, and 75% by mass or less. There may be. It is preferable that it is within the above range because adhesiveness and heat resistance will be good.

<Acid-modified polyolefin>
In the present invention, acid-modified polyolefin can be preferably used as the acid-modified resin. The acid-modified polyolefin used in the present invention is not limited, but can be obtained by grafting an unsaturated carboxylic acid component (preferably at least one α,β-unsaturated carboxylic acid and its acid anhydride) to a polyolefin resin. Preferably. Polyolefin resin is produced by homopolymerization of olefin monomers such as ethylene, propylene, butene, butadiene, isoprene, etc., or copolymerization with other monomers, and hydrocarbons such as hydrides and halides of the resulting polymers. Refers to a polymer whose main component is a skeleton. The acid-modified polyolefin is preferably one obtained by grafting at least one of an α,β-unsaturated carboxylic acid and an acid anhydride thereof to at least one of polyethylene, polypropylene, and a propylene-α-olefin copolymer. .

The propylene-α-olefin copolymer is mainly composed of propylene and copolymerized with α-olefin. As the α-olefin, for example, one or more of ethylene, 1-butene, 1-heptene, 1-octene, 4-methyl-1-pentene, vinyl acetate, etc. can be used. Among these α-olefins, ethylene and 1-butene are preferred. The ratio of the propylene component to the α-olefin component of the propylene-α-olefin copolymer is not limited, but the proportion of the propylene component is preferably 50 mol% or more, more preferably 70 mol% or more. Furthermore, these raw materials are not limited to petroleum-derived raw materials, but may also be raw materials obtained using chemical recycling technology that utilizes biomass naphtha or waste plastics.

As the unsaturated carboxylic acid component, at least one kind of α,β-unsaturated carboxylic acid and its acid anhydride is preferable, and specific examples are as mentioned above, such as maleic acid, itaconic acid, citraconic acid, and acid anhydrides. Among these, acid anhydrides are preferred, and maleic anhydride is more preferred. Specifically, the acid-modified polyolefins include maleic anhydride-modified polypropylene, maleic anhydride-modified propylene-ethylene copolymer, maleic anhydride-modified propylene-butene copolymer, and maleic anhydride-modified propylene-ethylene-butene copolymer. These acid-modified polyolefins can be used alone or in combination of two or more.

The lower limit of the acid value of the acid-modified polyolefin is preferably 89 equivalents/10 ⁶ g or more, more preferably 107 equivalents/10 ⁶ g, from the viewpoint of heat resistance and adhesiveness to resin base materials and metal base materials. or more, and more preferably 125 equivalents/10 ⁶ g or more. By setting it to the above lower limit or more, compatibility with the epoxy resin (B) becomes good, and excellent adhesive strength can be exhibited. In addition, the crosslinking density is high and the soldering heat resistance is good. The upper limit is preferably 713 equivalents/10 ⁶ g or less, more preferably 534 equivalents/10 ⁶ g or less, still more preferably 356 equivalents/10 ⁶ g or less. Adhesiveness becomes good by setting it below the said upper limit value. In addition, the viscosity and stability of the solution are improved, and excellent pot life can be exhibited. Furthermore, manufacturing efficiency is also improved.

The acid-modified polyolefin is preferably a crystalline acid-modified polyolefin. Crystallinity as used in the present invention refers to crystallinity that shows a clear melting peak during the heating process when heated from -100°C to 250°C at a rate of 20°C/min using a differential scanning calorimeter (DSC). Point.

The melting point (Tm) of the acid-modified polyolefin is preferably in the range of 50°C to 120°C. The temperature range is more preferably 60°C to 100°C, and most preferably 70°C to 90°C. By setting it to the above lower limit or more, the cohesive force derived from the crystal becomes good, and excellent adhesiveness and soldering heat resistance can be exhibited. Further, by setting the amount to be below the above upper limit, the solution stability and fluidity will be excellent, and the operability during adhesion will be good.

The heat of fusion (ΔH) of the acid-modified polyolefin is preferably in the range of 5 J/g to 60 J/g. More preferably the range is 10 J/g to 50 J/g, and most preferably the range is 20 J/g to 40 J/g. By setting it to the above lower limit or more, the cohesive force derived from the crystal becomes good, and excellent adhesiveness and soldering heat resistance can be exhibited. Further, by setting the amount to be below the above upper limit, the solution stability and fluidity will be excellent, and the operability during adhesion will be good.

The weight average molecular weight (Mw) of the acid-modified polyolefin is preferably in the range of 10,000 to 500,000. It is more preferably in the range of 20,000 to 400,000, still more preferably in the range of 40,000 to 200,000, particularly preferably in the range of 50,000 to 100,000. When the amount is equal to or more than the lower limit, the cohesive force becomes good and excellent adhesiveness can be exhibited. In addition, by setting the content to be below the upper limit value, the fluidity is excellent and the operability becomes good.

The method for producing acid-modified polyolefin is not particularly limited, and for example, radical graft reaction (i.e., generating radical species for the main chain polymer, and using the radical species as a polymerization initiation point to form an unsaturated carboxylic acid component (preferably Examples include graft polymerization of α,β-unsaturated carboxylic acids and their acid anhydrides).

<Acid-modified polystyrene resin>
In the present invention, acid-modified polystyrene resin can be preferably used as the acid-modified resin. Acid-modified polystyrene resins are not limited to, but include aromatic vinyl compounds alone, copolymers of aromatic vinyl compounds and conjugated diene compounds mainly having a block and/or random structure, and hydrogenated products thereof. Preferably, it is modified with a saturated carboxylic acid component. Aromatic vinyl compounds include, but are not particularly limited to, styrene, t-butylstyrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-diethyl-p-aminoethyl. Examples include styrene, vinyltoluene, p-tert-butylstyrene, and the like. Further, examples of the conjugated diene compound include butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, and the like. Furthermore, these raw materials are not limited to petroleum-derived raw materials, but may also be raw materials obtained using chemical recycling technology that utilizes biomass naphtha or waste plastics. Specific examples of copolymers of these aromatic vinyl compounds and conjugated diene compounds include styrene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer (SEBS), and styrene-ethylene-propylene-styrene. Examples include block copolymers (SEPS), styrene-ethylene-ethylene propylene-styrene block copolymers (SEEPS), and the like. As the unsaturated carboxylic acid component, at least one kind of α,β-unsaturated carboxylic acid and its acid anhydride is preferable, and specific examples are as mentioned above, such as maleic acid, itaconic acid, citraconic acid, and acid anhydrides. Among these, acid anhydrides are preferred, and maleic anhydride is more preferred.

The lower limit of the acid value of the acid-modified polystyrene resin is preferably 10 equivalents/10 ⁶ g or more, more preferably 20 equivalents/10 ⁶ from the viewpoint of heat resistance and adhesion to resin base materials and metal base materials. g or more, more preferably 50 equivalents/10 ⁶ g or more. By setting it to the above lower limit or more, compatibility with the epoxy resin (B) becomes good, and excellent adhesive strength can be exhibited. In addition, the crosslinking density is high and the soldering heat resistance is good. The upper limit is preferably 500 equivalents/10 ⁶ g or less, more preferably 400 equivalents/10 ⁶ g or less, still more preferably 300 equivalents/10 ⁶ g or less. Adhesiveness becomes good by setting it below the said upper limit value. In addition, the viscosity and stability of the solution are improved, and excellent pot life can be exhibited. Furthermore, manufacturing efficiency is also improved.

<Acid-modified cycloolefin polymer>
In the present invention, it is also preferable to use an acid-modified cycloolefin polymer as the acid-modified resin. Acid-modified cycloolefin polymer is a cycloolefin polymer into which a carboxyl group is introduced by modifying it with an unsaturated carboxylic acid component, and a cycloolefin polymer is a homopolymer made from only one type of cycloolefin monomer ( COP) or copolymers composed of one or more cycloolefin monomers and comonomers (COC) can be used. Further, as the unsaturated carboxylic acid component, at least one kind of α,β-unsaturated carboxylic acid and its acid anhydride is preferable, and specific examples are as mentioned above, such as maleic acid, itaconic acid, citraconic acid, and These acid anhydrides can be mentioned. Among these, acid anhydrides are preferred, and maleic anhydride is more preferred.

Examples of the cycloolefin monomer include bicyclics such as norbornene and norbornadiene, tricyclics such as dicyclopentadiene and dihydroxypentadiene, tetracyclics such as tetracyclododecene, and pentacyclics such as cyclopentadiene trimer. , heptacyclics such as tetracyclopentadiene, or alkyl (methyl, ethyl, propyl, butyl, etc.) substituted products, alkenyl (vinyl etc.) substituted products, alkylidene (ethylidene etc.) substituted products, aryl (phenyl, etc.) substituted products of these polycyclics Examples include tolyl, naphthyl, etc.) substituted products. Among these, norbornene monomers selected from the group consisting of norbornene, tetracyclododecene, and alkyl substituted products thereof are particularly preferred. Furthermore, these raw materials are not limited to petroleum-derived raw materials, but may also be raw materials obtained using chemical recycling technology that utilizes biomass naphtha or waste plastics.

Further, the comonomer may be any monomer that can be copolymerized with the above-mentioned cycloolefin monomer, and for example, an alkene monomer is preferable. Examples of the alkene monomer include α-olefins such as ethylene, propylene, 1-butene, and 1-hexene, and isobutene. The alkene monomer may be linear or branched.

It is preferable that 50% by mass or more of the monomer component constituting the acid-modified cycloolefin polymer is the cycloolefin monomer, more preferably 60% by mass or more is the cycloolefin monomer. When the cycloolefin monomer accounts for 50% by mass or more of the total monomer components, the soldering heat resistance will be good. There are no particular limitations on the polymerization method, polymerization conditions, etc. when polymerizing the monomer components, and they may be appropriately set according to conventional methods.

The weight average molecular weight (Mw) of the acid-modified cycloolefin polymer is preferably in the range of 10,000 to 500,000. It is more preferably in the range of 20,000 to 400,000, still more preferably in the range of 40,000 to 200,000, particularly preferably in the range of 50,000 to 100,000. When the amount is equal to or more than the lower limit, the cohesive force becomes good and excellent adhesiveness can be exhibited. In addition, by setting the content to be below the upper limit value, the fluidity is excellent and the operability becomes good.

The lower limit of the acid value of the acid-modified cycloolefin polymer is preferably 89 equivalents/10 ⁶ g or more, more preferably 107 equivalents/10 g, from the viewpoint of heat resistance and adhesion to resin substrates and metal substrates. ⁶ g or more, more preferably 125 equivalent/10 ⁶ g or more. By setting it to the above lower limit or more, compatibility with the epoxy resin (B) becomes good, and excellent adhesive strength can be exhibited. In addition, the crosslinking density is high and the soldering heat resistance is good. The upper limit is preferably 713 equivalents/10 ⁶ g or less, more preferably 534 equivalents/10 ⁶ g or less, still more preferably 356 equivalents/10 ⁶ g or less. Adhesiveness becomes good by setting it below the said upper limit value. In addition, the viscosity and stability of the solution are improved, and excellent pot life can be exhibited. Furthermore, manufacturing efficiency is also improved.

<Epoxy resin>
The adhesive composition of the present invention contains an epoxy resin (B). The epoxy resin used in the present invention is not particularly limited as long as it has an epoxy group in its molecule, but is preferably a polyfunctional epoxy resin having two or more epoxy groups in its molecule. Specifically, but not limited to, biphenyl type epoxy resin, naphthalene type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin, alicyclic epoxy resin, dicyclopentadiene type epoxy resin, Glycidylamine type epoxy resin, tetraglycidyldiaminodiphenylmethane, triglycidylpara-aminophenol, tetraglycidylbisaminomethylcyclohexanone, N,N,N',N'-tetraglycidyl-m-xylene diamine, diallyl monoglycidyl isocyanurate, diglycidyl mono At least one selected from the group consisting of allyl isocyanurate and epoxy-modified polybutadiene can be used. Preferably, diglycidyl monoallyl isocyanurate, N,N,N',N'-tetraglycidyl-m-xylene diamine, biphenyl type epoxy resin, novolak type epoxy resin, dicyclopentadiene type epoxy resin, glycidylamine type epoxy resin Or epoxy modified polybutadiene. Among these, polyfunctional epoxy resins having an unsaturated hydrocarbon group (preferably an allyl group CH ₂ =CH-CH ₂ -*) in the molecule are more preferred, and specifically, diglycidyl monoallyl isocyanurate, Glycidyl monoallyl isocyanurate can exhibit particularly excellent dielectric properties and adhesive properties.

In the adhesive composition of the present invention, the content of the epoxy resin (B) is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, based on 100 parts by mass of the acid-modified resin. and more preferably 1 part by mass or more. By setting it to the above lower limit or more, a sufficient curing effect can be obtained, and excellent adhesiveness and soldering heat resistance can be exhibited. Moreover, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less. By setting it below the above-mentioned upper limit, pot life property and low dielectric property become good. That is, by keeping it within the above range, it is possible to obtain an adhesive composition having excellent low dielectric properties in addition to adhesiveness and soldering heat resistance.

<Polycarbodiimide>
The adhesive composition of the present invention can contain polycarbodiimide. The polycarbodiimide is not particularly limited as long as it has two or more carbodiimide bonds in the molecule. By using polycarbodiimide, the carboxy group of the acid-modified resin or the epoxy group of the epoxy resin (B) reacts with the carbodiimide bond, making it possible to improve heat resistance and adhesiveness.

In the adhesive composition of the present invention, the content of polycarbodiimide is preferably 1 part by mass or more, more preferably 3 parts by mass or more, based on 100 parts by mass of the acid-modified resin. By setting it above the lower limit, the crosslinking density can be increased, and the soldering heat resistance can be improved. Moreover, it is preferably 20 parts by mass or less, more preferably 10 parts by mass or less. By setting it below the above upper limit, excellent solder heat resistance and low dielectric properties can be exhibited. That is, by keeping it within the above range, an adhesive composition having excellent solder heat resistance and low dielectric properties can be obtained.

<Unsaturated hydrocarbon>
The adhesive composition of the present invention may contain an unsaturated hydrocarbon having a terminal unsaturated hydrocarbon group and having a 5% weight loss temperature of 260° C. or higher. When an unsaturated hydrocarbon is contained, the unsaturated hydrocarbon has a terminal unsaturated hydrocarbon group, which increases the crosslinking density through a curing reaction by radicals generated by using a radical initiator, etc., and improves soldering heat resistance. can do. Furthermore, since hydroxyl groups that deteriorate dielectric properties are not generated after the reaction, the adhesive can have even better dielectric properties. It is preferable to have two or more terminal unsaturated hydrocarbon groups in one molecule because the crosslinking density can be further increased.

The 5% weight loss temperature of the unsaturated hydrocarbon needs to be 260°C or higher. The temperature is preferably 270°C or higher, more preferably 280°C or higher, and even more preferably 290°C or higher. When the 5% weight loss temperature is equal to or higher than the above value, it becomes possible to perform soldering without causing appearance defects even at temperatures exceeding the melting point of the solder. The upper limit is not particularly limited, but 500°C is practical.

It is preferable that the unsaturated hydrocarbon has an aromatic ring structure or an alicyclic structure as a structural unit. By having an aromatic ring structure or an alicyclic structure as a structural unit, soldering heat resistance can be improved and dielectric properties are also excellent. Among them, it is preferable to have an aromatic ring structure or an alicyclic structure as an unsaturated hydrocarbon skeleton, and polyphenylene ether or phenol resin is preferable. Specific examples of polyphenylene ethers having terminal unsaturated hydrocarbon groups include SA-9000 from SABIC and OPE-2St from Mitsubishi Gas Chemical. Further, as the phenol resin having a terminal unsaturated hydrocarbon group, Resitop FTC-809AE manufactured by Gunei Chemical Industry Co., Ltd. is exemplified.

The number average molecular weight of the unsaturated hydrocarbon is preferably 500 or more, more preferably 1000 or more. Further, it is preferably 100,000 or less, more preferably 10,000 or less, and even more preferably 5,000 or less. Within the above range, the solubility in the solvent is good and a uniform adhesive coating can be formed.

The content of unsaturated hydrocarbon in the adhesive composition of the present invention is preferably 1 part by mass or more, more preferably 2 parts by mass or more, based on 100 parts by mass of the acid-modified resin. Moreover, it is preferably 100 parts by mass or less, more preferably 50 parts by mass or less. Within the above range, both excellent adhesiveness and soldering heat resistance can be achieved.

<Radical generator>
It is also preferable that the adhesive composition of the present invention contains a radical generator. The radicals generated by the radical generator cause the terminal unsaturated hydrocarbon groups of the unsaturated hydrocarbons to react efficiently and increase the crosslinking density, thereby improving the soldering heat resistance and dielectric properties. The radical generator is not particularly limited, but it is preferable to use an organic peroxide. Examples of organic peroxides include, but are not limited to, di-tert-butyl peroxyphthalate, tert-butyl hydroperoxide, dicumyl peroxide, benzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxy- Peroxides such as 2-ethylhexanoate, tert-butyl peroxypivalate, methyl ethyl ketone peroxide, di-tert-butyl peroxide, lauroyl peroxide; azobisisobutyronitrile, azobisisopropionitrile, etc. Examples include azonitrile.

The 1-minute half-life temperature of the radical generator used in the present invention is preferably 140°C or higher. By heating the temperature to 140° C. or higher, it is possible to prevent radical reactions from starting when an adhesive sheet is created by volatilizing the solvent of the adhesive composition varnish, and to exhibit excellent adhesive properties.

The amount of the radical generator used in the present invention is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, per 100 parts by mass of the unsaturated hydrocarbon. Further, the amount is preferably 50 parts by mass or less, more preferably 10 parts by mass or less. By keeping it within the above range, an optimum crosslinking density can be achieved, and both adhesion and soldering heat resistance can be achieved.

<Organic solvent>
The adhesive composition of the present invention can further contain an organic solvent. The organic solvent used in the present invention is not particularly limited as long as it dissolves the acid-modified resin, compound (A), and epoxy resin (B). Specifically, for example, aromatic hydrocarbons such as benzene, toluene, and xylene, aliphatic hydrocarbons such as hexane, heptane, octane, and decane, and alicyclic hydrocarbons such as cyclohexane, cyclohexene, methylcyclohexane, and ethylcyclohexane. Hydrogen, halogenated hydrocarbons such as trichloroethylene, dichloroethylene, chlorobenzene, chloroform, alcoholic solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, phenol, acetone, methyl isobutyl ketone, Ketone solvents such as methyl ethyl ketone, pentanone, hexanone, cyclohexanone, isophorone, acetophenone, cellosolves such as methyl cellosolve, ethyl cellosolve, ester solvents such as methyl acetate, ethyl acetate, butyl acetate, methyl propionate, butyl formate, Ethylene glycol mono-n-butyl ether, ethylene glycol mono-iso-butyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-iso-butyl ether, triethylene glycol mono-n-butyl ether, tetraethylene glycol mono-n-butyl ether, etc. Glycol ether solvents and the like can be used, and one or more of these can be used in combination. In particular, methylcyclohexane and toluene are preferred from the viewpoint of work environment and drying properties.

The organic solvent is preferably used in an amount of 100 to 1000 parts by mass based on 100 parts by mass of the solid content of the adhesive composition. When the content is equal to or more than the lower limit, the liquid state and pot life properties will be good. In addition, setting it below the upper limit value is advantageous in terms of manufacturing costs and transportation costs.

Further, the adhesive composition of the present invention may further contain other components as necessary. Specific examples of such components include flame retardants, tackifiers, fillers, antioxidants, silane coupling agents, and the like.

<Flame retardant>
If necessary, a flame retardant may be added to the adhesive composition of the present invention. Examples of flame retardants include bromine-based, phosphorus-based, nitrogen-based, and metal hydroxide compounds. Among these, phosphorus-based flame retardants are preferred, and known phosphorus-based flame retardants such as phosphoric acid esters, such as trimethyl phosphate, triphenyl phosphate, and tricresyl phosphate, phosphates, such as aluminum phosphinate, and phosphazene, can be used. . These may be used alone or in any combination of two or more. When containing a flame retardant, the flame retardant is preferably contained in a range of 1 to 200 parts by mass, and preferably 5 to 150 parts by mass, based on a total of 100 parts by mass of the acid-modified resin, compound (A), and epoxy resin (B). Parts by weight are more preferred, and 10 to 100 parts by weight are most preferred. By keeping the content within the above range, flame retardancy can be exhibited while maintaining adhesion, solder heat resistance, and electrical properties.

<Tackifier>
If necessary, a tackifier may be added to the adhesive composition of the present invention. Examples of tackifiers include polyterpene resins, rosin resins, aliphatic petroleum resins, alicyclic petroleum resins, copolymer petroleum resins, styrene resins, hydrogenated petroleum resins, etc. The purpose is to improve adhesive strength. used in These may be used alone or in any combination of two or more. When containing a tackifier, it is preferably contained in a range of 1 to 200 parts by mass, and preferably 5 to 150 parts by mass, based on a total of 100 parts by mass of the acid-modified resin, compound (A), and epoxy resin (B). More preferably, the amount is in the range of 10 to 100 parts by mass. By keeping it within the above range, the effect of the tackifier can be exhibited while maintaining adhesiveness, solder heat resistance, and electrical properties.

<Filler>
Fillers may be added to the adhesive composition of the present invention, if necessary. Examples of the organic filler include powders of heat-resistant resins such as polyimide, polyamideimide, fluororesin, and liquid crystal polyester. Examples of inorganic fillers include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), titania (TiO ₂ ), tantalum oxide (Ta ₂ O ₅ ), zirconia (ZrO ₂ ), silicon nitride (Si ₃ N ₄ ), boron nitride (BN), calcium carbonate (CaCO ₃ ), calcium sulfate (CaSO ₄ ), zinc oxide (ZnO), magnesium titanate (MgO・TiO ₂ ), barium sulfate (BaSO ₄ ), organic bentonite, clay , mica, aluminum hydroxide, magnesium hydroxide, etc. Among these, silica is preferred because of its ease of dispersion and its effect of improving heat resistance.

Hydrophobic silica and hydrophilic silica are generally known as silica, but here we will use hydrophobic silica treated with dimethyldichlorosilane, hexamethyldisilazane, octylsilane, etc. to impart moisture absorption resistance. is good. When blending silica, the blending amount is preferably 0.05 to 30 parts by mass based on a total of 100 parts by mass of the acid-modified resin, compound (A), and epoxy resin (B). Further heat resistance can be exhibited by setting it to the above-mentioned lower limit or more. In addition, by setting the amount to be below the upper limit, poor dispersion of silica and excessively high solution viscosity can be suppressed, and workability can be improved.

<Antioxidant>
An antioxidant may be added to the adhesive composition of the present invention, if necessary. By blending an antioxidant, it is possible to suppress deterioration of properties such as adhesiveness and dielectric properties even when used in a high-temperature environment exposed to air, which is preferable. The antioxidant is not particularly limited, but includes phenolic antioxidants, amine antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like. These may be used alone or in combination of two or more.

When the adhesive composition contains an antioxidant, the content thereof is preferably 0.5 to 5 parts by mass, and 1 to 3 parts by mass, based on 100 parts by mass of the solid content of the adhesive composition. It is more preferable that If the content of the antioxidant is within the above range, it is possible to suppress deterioration of properties such as adhesiveness and dielectric properties even when used in a high temperature environment exposed to air.

<Silane coupling agent>
A silane coupling agent may be added to the adhesive composition of the present invention, if necessary. By blending a silane coupling agent, adhesion to metals and heat resistance properties are improved, which is very preferable. The silane coupling agent is not particularly limited, but examples include those having an unsaturated group, those having an epoxy group, and those having an amino group. Among these, from the viewpoint of heat resistance, epoxy resins such as γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltriethoxysilane A silane coupling agent having a group is more preferable. When blending a silane coupling agent, the blending amount should be 0.5 to 20 parts by mass per 100 parts by mass of the acid-modified resin, compound (A), and epoxy resin (B). preferable. By keeping it within the above range, soldering heat resistance and adhesiveness can be improved.

<Laminated body>
The laminate of the present invention is one in which an adhesive composition is laminated on a base material (two-layer laminate of base material/adhesive layer), or one in which a base material is further laminated (base material/adhesive layer/ It is a three-layer laminate of base materials). Here, the adhesive layer refers to a layer of the adhesive composition after applying the adhesive composition of the present invention to a base material and drying it. The laminate of the present invention can be obtained by applying the adhesive composition of the present invention to various base materials, drying, and further laminating other base materials according to a conventional method.

<Base material>
In the present invention, the base material is not particularly limited as long as it can form an adhesive layer by coating and drying the adhesive composition of the present invention, but resin base materials such as film-like resin, metal Examples include metal substrates such as plates and metal foils, papers, and the like.

Examples of the resin base material include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, and fluorine resin. Preferably it is a film-like resin (hereinafter also referred to as a base film layer).

As the metal base material, any conventionally known conductive material that can be used for circuit boards can be used. Examples of the material include various metals such as SUS, copper, aluminum, iron, steel, zinc, and nickel, alloys thereof, plated products, and metals treated with other metals such as zinc and chromium compounds. Preferably it is metal foil, more preferably copper foil. The thickness of the metal foil is not particularly limited, but is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 10 μm or more. Moreover, it is preferably 50 μm or less, more preferably 30 μm or less, and still more preferably 20 μm or less. If the thickness is too thin, it may be difficult to obtain sufficient electrical performance of the circuit. On the other hand, if the thickness is too thick, processing efficiency during circuit production may be reduced. Metal foil is usually provided in roll form. The form of the metal foil used in manufacturing the printed wiring board of the present invention is not particularly limited. When using a ribbon-shaped metal foil, its length is not particularly limited. The width is also not particularly limited, but is preferably about 250 to 500 cm. The surface roughness of the base material is not particularly limited, but is preferably 3 μm or less, more preferably 2 μm or less, and still more preferably 1.5 μm or less. Practically speaking, the thickness is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably 0.7 μm or more.

Examples of paper include high-quality paper, kraft paper, roll paper, glassine paper, and the like. Moreover, glass epoxy etc. can be illustrated as a composite material.

In terms of adhesive strength and durability with the adhesive composition, base materials include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, fluorine resin, SUS steel plate, copper foil, aluminum foil, or glass epoxy is preferred.

<Adhesive sheet>
In the present invention, the adhesive sheet is one in which the base material and the release base material are laminated with an adhesive composition interposed therebetween. Specific structural aspects include base material/adhesive layer/mold release base material, or mold release base material/adhesive layer/base material/adhesive layer/mold release base material. By laminating the release base material, it functions as a protective layer for the base material. Further, by using a release base material, it is possible to release the release base material from the adhesive sheet and further transfer the adhesive layer to another base material.

The adhesive sheet of the present invention can be obtained by applying the adhesive composition of the present invention to various laminates and drying it according to a conventional method. In addition, if a release base material is attached to the adhesive layer after drying, it can be rolled up without causing set-off to the base material, resulting in excellent operability, and the adhesive layer is protected, making it easier to store. It has excellent properties and is easy to use. Furthermore, if the adhesive layer itself is applied to a release base material and, after drying, another release base material is attached as needed, it becomes possible to transfer the adhesive layer itself to another base material.

<Release base material>
The release base material is not particularly limited, but examples include paper such as high-quality paper, kraft paper, roll paper, and glassine paper, with a coating layer of a sealant such as clay, polyethylene, or polypropylene on both sides of the paper. Examples include those in which a silicone-based, fluorine-based, or alkyd-based mold release agent is applied on each coating layer. Also included are various olefin films alone such as polyethylene, polypropylene, ethylene-α-olefin copolymer, propylene-α-olefin copolymer, and films made of polyethylene terephthalate and the like coated with the above mold release agent. For reasons such as the release force between the release base material and the adhesive layer and the adverse effects of silicone on electrical properties, we use high-quality paper with a polypropylene filling treatment on both sides and then use an alkyd release agent on top of that. Alternatively, it is preferable to use an alkyd mold release agent on polyethylene terephthalate.

In the present invention, methods for coating the adhesive composition on the substrate include, but are not particularly limited to, a comma coater, a reverse roll coater, a die coater, and the like. Alternatively, if necessary, an adhesive layer can be provided directly or by a transfer method on the rolled copper foil or polyimide film that is a constituent material of the printed wiring board. The thickness of the adhesive layer after drying may be changed as necessary, but is preferably in the range of 5 to 200 μm. Sufficient adhesive strength can be obtained by setting the adhesive film thickness to 5 μm or more. Further, by setting the thickness to 200 μm or less, it becomes easier to control the amount of residual solvent in the drying process, and blisters are less likely to occur during pressing for manufacturing printed wiring boards. The drying conditions are not particularly limited, but the residual solvent rate after drying is preferably 1% by mass or less. By controlling the content to 1% by mass or less, foaming of the residual solvent during printed wiring board pressing is suppressed, and blisters are less likely to occur.

<Printed wiring board>
The printed wiring board in the present invention includes as a component a laminate formed from a metal foil forming a conductor circuit and a resin base material. A printed wiring board is manufactured by a conventionally known method such as a subtractive method using a metal-clad laminate, for example. If necessary, we can use so-called flexible circuit boards (FPC), flat cables, tape automated bonding ( A general term for circuit boards for TAB).

The printed wiring board of the present invention can have any laminated structure that can be adopted as a printed wiring board. For example, a printed wiring board can be made up of four layers: a base film layer, a metal foil layer, an adhesive layer, and a cover film layer. Further, for example, a printed wiring board can be made up of five layers: a base film layer, an adhesive layer, a metal foil layer, an adhesive layer, and a cover film layer.

Furthermore, if necessary, it is also possible to have a structure in which two or three or more of the above printed wiring boards are laminated.

The adhesive composition of the present invention can be suitably used for each adhesive layer of a printed wiring board. In particular, when the adhesive composition of the present invention is used as an adhesive, it has high adhesion not only to conventional polyimide, polyester film, and copper foil that constitute printed wiring boards, but also to low-polarity resin base materials such as LCP. , it is possible to obtain solder reflow resistance, and the adhesive layer itself has excellent low dielectric properties. Therefore, it is suitable as an adhesive composition for use in coverlay films, laminates, resin-coated copper foils, and bonding sheets.

In the printed wiring board of the present invention, any resin film conventionally used as a base material for printed wiring boards can be used as the base film. Examples of the resin for the base film include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, and fluorine resin. In particular, it has excellent adhesion to low polarity substrates such as liquid crystal polymers, polyphenylene sulfide, syndiotactic polystyrene, and polyolefin resins.

<Cover film>
As the cover film, any insulating film conventionally known as an insulating film for printed wiring boards can be used. For example, films manufactured from various polymers such as polyimide, polyester, polyphenylene sulfide, polyether sulfone, polyether ether ketone, aramid, polycarbonate, polyarylate, polyamideimide, liquid crystal polymer, syndiotactic polystyrene, and polyolefin resin are used. It is possible. More preferred are polyimide films or liquid crystal polymer films.

The printed wiring board of the present invention can be manufactured using any conventionally known process except for using the materials for each layer described above.

In a preferred embodiment, a semi-finished product (hereinafter referred to as "cover film-side semi-finished product") is manufactured by laminating an adhesive layer on a cover film layer. On the other hand, a semi-finished product in which a desired circuit pattern is formed by laminating a metal foil layer on a base film layer (hereinafter referred to as a "two-layer semi-finished product on the base film side") or a semi-finished product in which an adhesive layer is laminated on a base film layer. , manufacture a semi-finished product (hereinafter referred to as "base film side 3-layer semi-finished product") on which a metal foil layer is laminated to form a desired circuit pattern (hereinafter referred to as "base film side 2-layer semi-finished product"). (The three-layer semi-finished product on the base film side is collectively referred to as the "semi-finished product on the base film side.") A four-layer or five-layer printed wiring board can be obtained by bonding the cover film side semi-finished product obtained in this way and the base film side semi-finished product.

The semi-finished product on the base film side can be produced by, for example, (A) applying a solution of a resin that will become the base film to the metal foil and initially drying the coating film; (B) combining the metal foil obtained in (A) with It is obtained by a manufacturing method including a step of heat treating and drying a laminate with an initially dried coating film (hereinafter referred to as "heat treatment/solvent removal step").

A conventionally known method can be used to form a circuit in the metal foil layer. An additive method or a subtractive method may be used. Preferably, the subtractive method is used.

The obtained semi-finished product on the base film side may be used as is for lamination with the semi-finished product on the cover film side, or it may be used for lamination with the semi-finished product on the cover film side after laminating a release film and storing it. May be used.

The cover film side semi-finished product is manufactured by applying an adhesive to the cover film, for example. If necessary, a crosslinking reaction in the applied adhesive can be carried out. In a preferred embodiment, the adhesive layer is semi-cured.

The obtained semi-finished product on the cover film side may be used as is for lamination with the semi-finished product on the base film side, or it may be laminated with the semi-finished product on the base film side after laminating a release film and storing it. May be used for

The base film side semi-finished product and the cover film side semi-finished product are each stored, for example, in the form of a roll, and then bonded together to produce a printed wiring board. Any method can be used for bonding, and for example, bonding can be performed using a press or a roll. Further, the two can be bonded together while heating by a method such as using a hot press or a heated roll device.

For example, in the case of a soft and rollable reinforcing material such as a polyimide film, the reinforcing material side semi-finished product is preferably manufactured by applying an adhesive to the reinforcing material. In addition, in the case of reinforcing plates that are hard and cannot be rolled up, such as metal plates such as SUS and aluminum, or plates made of glass fibers cured with epoxy resin, it is possible to transfer the adhesive applied to the release base material in advance. Preferably, it is manufactured. Further, if necessary, a crosslinking reaction can be carried out in the applied adhesive. In a preferred embodiment, the adhesive layer is semi-cured.

The obtained semi-finished product on the reinforcing material side may be used as it is for bonding with the back side of the printed wiring board, or it may be used for bonding with the semi-finished product on the base film side after bonding a release film and storing it. You may.

The base film side semi-finished product, the cover film side semi-finished product, and the reinforcing material side semi-finished product are all laminates for printed wiring boards in the present invention.

The present invention will be specifically described below with reference to Examples. In addition, in the present Examples and Comparative Examples, the term "parts" simply indicates parts by mass.

<Physical property evaluation method>
(Acid value measurement)
The acid value (equivalent/10 ⁶ g) in the present invention was determined by dissolving the acid-modified resin in toluene and titrating with a methanol solution of sodium methoxide using phenolphthalein as an indicator.

(solubility)
A saturated solution of the resin was prepared by mixing 100 g of cyclohexane and the resin at 25° C. for 1 hour, and the concentration of the resin in the obtained saturated solution (g/100 g-C ₆ H ₁₂ ) was defined as the solubility. The resin concentration in this solubility test was a maximum of 100g/100g-C ₆ H ₁₂ .

(Weight average molecular weight (Mw))
The weight average molecular weight in the present invention is determined by gel permeation chromatography (GPC, standard material: polystyrene resin, mobile phase: tetrahydrofuran, column: Shodex KF-802 + KF-804L + KF-806L, manufactured by Shimadzu Corporation). Temperature: 30°C, flow rate: 1.0 ml/min, detector: RI detector).

(Measurement of melting point)
The melting point in the present invention is determined using a differential scanning calorimeter (hereinafter referred to as DSC, manufactured by TA Instruments Japan, Q-2000) at a rate of 20°C/min. This value is measured from the top temperature of the melting peak when the temperature is increased to melt.

(melt viscosity)
The melt viscosity is a value measured according to DIN 53019 using a rotational viscometer at 170°C.

Hereinafter, production examples of adhesive compositions serving as examples of the present invention and adhesive compositions serving as comparative examples will be shown.

The following compounds were used as compound (A).
(a1): LICOCENE PP 1302 (Clariant, propylene-ethylene copolymer, solubility approximately 250g/100g-C ₆ H ₁₂ , weight average molecular weight 19,100, melt viscosity (170°C) 200mPa・s, melting point 90°C)
(a2): LICOCENE PP 1502 (Clariant, propylene-ethylene copolymer, solubility approximately 250g/100g-C ₆ H ₁₂ , weight average molecular weight 46,900, melt viscosity (170°C) 1,800 mPa・s, melting point 86 ℃)
(a3): LICOCENE PP 1602 (Clariant, propylene-ethylene copolymer, solubility approximately 250g/100g-C ₆ H ₁₂ , weight average molecular weight 50,000, melt viscosity (170°C) 6,000 mPa・s, melting point 88 ℃)
(a4): LICOCENE PP 2502 (Clariant, propylene-ethylene copolymer, solubility 30g/100g-C ₆ H ₁₂ , weight average molecular weight 40,900, melt viscosity (170°C) 2,000 mPa・s, melting point 103°C )

The acid-modified resin was manufactured as follows.
(Manufacturing example 1)
In a 1 L autoclave, add 100 parts by mass of a cycloolefin polymer (ZEONEX (registered trademark) RS420 manufactured by Nippon Zeon Co., Ltd.), 150 parts by mass of toluene, 19 parts by mass of maleic anhydride, and 6 parts by mass of di-tert-butyl peroxide. After raising the temperature to 140°C, the mixture was further stirred for 3 hours. Thereafter, the resulting reaction solution was cooled and poured into a container containing a large amount of methyl ethyl ketone to precipitate the resin. Thereafter, the liquid containing the resin was centrifuged to separate and purify the acid-modified cycloolefin polymer graft-polymerized with maleic anhydride, (poly)maleic anhydride, and low molecular weight substances. Thereafter, by drying at 70° C. for 5 hours under reduced pressure, the maleic anhydride-modified cycloolefin polymer (acid-modified resin 1, acid value 339 equivalent/10 ⁶ g, relative permittivity 2.0 at a frequency of 10 GHz, dielectric constant at a frequency of 10 GHz) was obtained. A tangent of 0.0008 and a weight average molecular weight of 90,000 were obtained.

(Manufacturing example 2)
In a 1L autoclave, 100 parts by mass of propylene-butene copolymer ("Tafmer (registered trademark) XM7080" manufactured by Mitsui Chemicals), 150 parts by mass of toluene, 19 parts by mass of maleic anhydride, 6 parts by mass of di-tert-butyl peroxide. was added, the temperature was raised to 140°C, and the mixture was further stirred for 3 hours. Thereafter, the resulting reaction solution was cooled and poured into a container containing a large amount of methyl ethyl ketone to precipitate the resin. Thereafter, the liquid containing the resin was centrifuged to separate and purify the acid-modified propylene-butene copolymer graft-polymerized with maleic anhydride, the (poly)maleic anhydride, and the low molecular weight substance. Thereafter, by drying at 70°C under reduced pressure for 5 hours, maleic anhydride-modified propylene-butene copolymer (acid-modified resin 2, acid value 339 equivalents/10 ⁶ g, weight average molecular weight 75,000, Tm 80°C, H35J/g) was obtained.

As other acid-modified resins, the following were used.
(Acid-modified resin 3): Tuftec M1943 (manufactured by Asahi Kasei Corporation, a polymer obtained by hydrogenating the double bond of a block copolymer consisting of styrene and butadiene, modified with maleic anhydride, acid value 185 equivalents/ 10 ⁶ g)

As the epoxy resin (B), the following was used.
(b1): MA-DGIC (manufactured by Shikoku Kasei Kogyo Co., Ltd., monoallyl diglycidyl isocyanurate)
(b2): jER604 (manufactured by Mitsubishi Chemical Corporation, glycidylamine type epoxy resin)
(b3): EPICLON HP-7200 (manufactured by DIC, polyfunctional dicyclopentadiene type epoxy resin)

As other adhesive compounding components, the following were used.
(c1): LICOCENE PP 2602 (Clariant, propylene-ethylene copolymer, solubility 10g/100g-C ₆ H ₁₂ , weight average molecular weight 65,100, melt viscosity (170°C) 6,300 mPa・s, melting point 98°C )
(c2): LICOCENE PP 3602 (Clariant, propylene-ethylene copolymer, solubility 0 g/100 g-C ₆ H ₁₂ , weight average molecular weight 58,400, melt viscosity (170°C) 9,300 mPa・s, melting point 111°C )
(c3): L-MODU S901 (Idemitsu Kosan propylene homopolymer, solubility 100g/100g-C ₆ H ₁₂ or more, weight average molecular weight 130,000, melting point 80°C)
(c4): SA9000 (manufactured by SABIC, polyphenylene ether with vinyl group, number average molecular weight 1700, 5% weight loss temperature 439°C)
(c5): LICOCENE PP 6102 (Clariant, propylene homopolymer, solubility 0 g/100 g-C ₆ H ₁₂ , weight average molecular weight 9,000, melt viscosity (170°C) 60 mPa・s, melting point 145°C)

<Example 1>
30 parts of (a1) as compound (A), 100 parts of acid-modified resin (acid-modified resin 2), 4 parts of (b1) as epoxy resin (B), and 5 parts of (c4) as other components were blended. , a toluene adhesive composition (S1) dissolved in toluene to a solid content concentration of 24% was obtained.
The resulting adhesive composition (S1) was evaluated for relative dielectric constant, dielectric loss tangent, peel strength, solder heat resistance, varnish solubility, and circuit embeddability. The results are shown in Table 1.

<Examples 2 to 12, Comparative Examples 1 to 9>
Adhesive compositions (S2) to (S21) were prepared in the same manner as in Example 1, except that the types and amounts of each component of the adhesive composition were changed as shown in Tables 1 and 2, and each evaluation was performed. did. The results are listed in Tables 1 and 2.

<Evaluation of adhesive composition>
(Relative permittivity (εc) and dielectric loss tangent (tanδ))
The adhesive composition was applied to a Teflon (registered trademark) sheet having a thickness of 100 μm so that the thickness after drying would be 25 μm, and dried at 130° C. for 3 minutes. After curing by heat treatment at 180° C. for 3 hours, the Teflon (registered trademark) sheet was peeled off to obtain an adhesive sheet for testing. Thereafter, the obtained test adhesive sheet was cut into strips of 8 cm x 3 mm to obtain test samples. The relative permittivity (εc) and the dielectric loss tangent (tanδ) were measured using a network analyzer (manufactured by Anritsu Corporation) by the cavity resonator perturbation method at a temperature of 23° C. and a frequency of 10 GHz.
<Evaluation criteria for relative dielectric constant>
○: 2.4 or less ×: More than 2.4 <Evaluation criteria for dielectric loss tangent>
○: 0.0010 or less △: More than 0.0010, less than 0.0020 ×: 0.0020 or more

(Peel strength (adhesion))
The adhesive composition was applied to a polyimide film (manufactured by Kaneka Corporation, Apical (registered trademark)) with a thickness of 12.5 μm so that the thickness after drying would be 25 μm, and dried at 130° C. for 3 minutes. The adhesive film (B-stage product) thus obtained was bonded to a rolled copper foil having a thickness of 18 μm (manufactured by Nippon Steel Chemical & Materials Co., Ltd., Espanex series). The bonding was carried out by pressing the rolled copper foil for 280 seconds at 170° C. under a pressure of 2 MPa so that the shiny surface of the rolled copper foil was in contact with the adhesive layer. Next, it was heat-treated at 180° C. for 3 hours to harden it, and a sample for evaluation of peel strength was obtained. The peel strength was measured under the conditions of 25° C., film pulling, tensile speed of 50 mm/min, and 90° peeling. This test shows the adhesive strength at room temperature.
<Evaluation criteria>
○: 1.0N/mm or more ×: Less than 1.0N/mm

(soldering heat resistance)
An evaluation sample was prepared in the same manner as for the peel strength measurement described above, and a 2.0 cm x 2.0 cm sample piece was immersed in a solder bath melted at 288° C. to check for changes in appearance such as blistering.
<Evaluation criteria>
○: No blistering for 60 seconds or more △: Blistering for 30 seconds or more but less than 60 seconds ×: Blistering for less than 30 seconds

(Varnish solubility)
After blending each component, the solubility of the adhesive composition was checked after stirring at room temperature.
<Evaluation criteria>
○: All the ingredients are completely dissolved △: Some of the ingredients are not dissolved ×: The ingredients are not completely dissolved

(Circuit embeddability)
The adhesive composition was applied to one side of a polyimide film (manufactured by Kaneka Corporation, Apical (registered trademark)) having a thickness of 12.5 μm so that the thickness after drying would be 25 μm, and dried at 130° C. for 3 minutes. The adhesive film obtained in this way (B stage product) was used as a base material in which circuits were formed at a pitch of 25 μm on rolled copper foil with a thickness of 18 μm (manufactured by Nippon Steel Chemical & Materials Co., Ltd., Espanex series). Pasted together. The circuit surfaces were bonded together by pressing at 170° C. for 280 seconds under a pressure of 2 MPa so that the circuit surface was in contact with the adhesive layer. The amount of adhesive flowing out from the bonded surface along the circuit was measured using a microscope. This test was conducted immediately after the adhesive film was prepared and on an adhesive film (B stage product) stored at 25° C. for one week, and changes in measured values were confirmed. If the measured value after storage for one week at 25° C. decreases to less than 50% of the initial measured value, the circuit embeddability cannot be satisfied under practical conditions, and there is a risk that insulation failure of the printed circuit board will occur.
<Evaluation criteria>
○: Rate of change 80% or more and 100% or less △: Rate of change 50% or more and less than 80% ×: Rate of change less than 50%

As is clear from Table 1, Examples 1 to 12 are excellent in dielectric properties, peel strength, solder heat resistance, and circuit embeddability. Furthermore, Examples 1 to 12 also had good varnish solubility.
As shown in Examples 2 to 5, it can be seen that the dielectric properties are improved by increasing the content of compound (A).
Comparing Examples 1, 3, 6, and 7, it is possible to change solder heat resistance, varnish solubility, and circuit embedding properties depending on the properties of compound (A).
Comparing Examples 3 and 10 to 11, it is found that the dielectric properties can be further improved when an epoxy resin (B) having an unsaturated hydrocarbon group in the molecule is especially blended.
Although (c4) was not blended in Example 12, a comparison with Example 3 shows that (c4) contributes to excellent adhesion and improved soldering heat resistance.

On the other hand, in Comparative Example 1, since the amount of compound (A) was too small, the adhesive film lost fluidity after being stored at 25° C. for one week, and the circuit embeddability deteriorated.
In Comparative Example 2, since the amount of compound (A) was too large, the amount of acid-modified resin was relatively reduced, and the solder heat resistance as an adhesive composition was poor.
In Comparative Examples 3 and 4, propylene-ethylene copolymers with low solubility were used instead of compound (A), but these propylene-ethylene copolymers were highly crystalline and could not be dissolved in solvents. Therefore, it was not possible to conduct various evaluations.
As shown in Comparative Examples 5 to 9, when a propylene homopolymer was blended, an adhesive composition that could satisfy circuit embedding properties and soldering heat resistance could not be obtained.
In Comparative Example 7, since no unmodified polyolefin resin was blended, the dielectric properties and circuit embedding properties deteriorated.

The adhesive composition of the present invention has excellent solder heat resistance and adhesive strength, low dielectric constant and dielectric loss tangent, and also has good circuit embedding properties. Therefore, it is useful as an FPC adhesive or adhesive sheet in the high frequency range.

Claims (7)

An adhesive composition comprising at least one acid-modified resin selected from acid-modified polystyrene resin, acid-modified cycloolefin polymer and acid-modified polyolefin, compound (A) and epoxy resin (B),
The content of the acid-modified resin is 40% by mass or more based on 100% by mass of solid content of the adhesive composition,
The content of the epoxy resin (B) is 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the acid-modified resin,
An adhesive composition characterized in that the content of the compound (A) is 10 parts by mass or more and 40 parts by mass or less based on 100 parts by mass of the acid-modified resin.
Compound (A): propylene that does not have a heteroatom, has a weight average molecular weight of 15,000 or more and 70,000 or less, and has a solubility in cyclohexane of 25g/100g-C ₆ H ₁₂ or more at 25°C -Ethylene copolymer. The adhesive composition according to claim 1, wherein the acid-modified resin is an acid-modified polyolefin. The adhesive composition according to claim 1 or 2, wherein the epoxy resin (B) is a polyfunctional epoxy resin. The adhesive composition according to claim 1 or 2, wherein the compound (A) has a melt viscosity at 170° C. of 10,000 mPa·s or less. An adhesive sheet containing the adhesive composition according to claim 1 or 2. A laminate containing the adhesive composition according to claim 1 or 2. A printed wiring board comprising the laminate according to claim 6 as a component.