JP6645431B2 - Low dielectric adhesive composition - Google Patents

Description

  The present invention relates to an adhesive composition having a low dielectric constant and a low dielectric loss tangent. More specifically, the present invention relates to an adhesive composition used for bonding a resin substrate and a resin substrate or a metal substrate. In particular, the present invention relates to an adhesive composition for a flexible printed wiring board (hereinafter abbreviated as FPC), and a coverlay film, a laminate, a resin-coated copper foil and a bonding sheet containing the same.

In recent years, with the increase in the speed of transmission signals in printed wiring boards, the frequency of signals has been increasing. Along with this, demands for low dielectric properties (low dielectric constant, low dielectric loss tangent) in a high frequency region are increasing for FPCs. In response to such demands, liquid crystal polymers (LCP) having low dielectric properties, syndiotactic polystyrene (SPS), instead of conventional polyimide (PI) and polyethylene terephthalate films, have been used as base films for FPC. Substrate films such as polyphenylene sulfide (PPS) have been proposed.
However, since the base film having low dielectric properties has low polarity, when a conventional epoxy-based adhesive or acrylic-based adhesive is used, the adhesive strength is low, and the production of FPC members such as cover lay films and laminates is required. Was difficult. Further, epoxy-based adhesives and acrylic-based adhesives are not excellent in low dielectric properties and impair the dielectric properties of FPC.
On the other hand, polyolefin resins are known to have low dielectric properties. Therefore, an FPC adhesive composition using a polyolefin resin has been proposed. For example, Patent Document 1 proposes a modified polyamide adhesive composition into which an olefin skeleton has been introduced in order to enhance the electrical characteristics of FPC. Patent Document 2 proposes an adhesive and a flexible printed wiring board coverlay using an aromatic olefin oligomer-type modifier and an epoxy resin.

JP 2007-284515 A JP 2007-63306 A

However, although these adhesive compositions are described as having an adhesive property with polyimide, it is difficult to obtain an adhesive property with a base film having low dielectric properties such as LCP. In addition, since it is used as a modifier and has a small olefin skeleton occupying the adhesive composition, the dielectric properties of the adhesive are inferior.
When an LCP base material is used, there is a method in which the LCP is melted without using an adhesive and is bonded to a copper foil to produce a two-layer substrate. However, this method has a problem that a machine base for bonding at a high temperature is required, wrinkles are easily formed during processing, and the yield is reduced.

  As a result of intensive studies to solve the above problems, the present invention contains a crystalline acid-modified polyolefin and an amorphous polyolefin, and further has an excellent adhesive composition containing at least one of a carbodiimide resin and an epoxy resin. It exhibits low dielectric properties and has high adhesion and high solder heat resistance not only to conventional polyimide and polyethylene terephthalate films, but also to resin bases with low dielectric properties such as LCP and metal bases such as copper foil. And completed the present invention.

  That is, the present invention provides an adhesive composition having good adhesiveness to both various resin bases such as polyimide and LCP and a metal base, and also having excellent heat resistance and low dielectric properties. With the goal.

An adhesive composition containing the following components (A) and (B), and further containing at least one of the components (C) and (D).
(A) component: crystalline acid-modified polyolefin (B) component: amorphous polyolefin (C) component: carbodiimide resin (D) component: epoxy resin

  In the adhesive composition, the component (A) preferably contains 5% by mass or more.

  Component (B) may be contained in an amount of 10 to 100 parts by mass, component (C) in an amount of 0.5 to 30 parts by mass, and / or component (D) in an amount of 1 to 30 parts by mass with respect to 100 parts by mass of component (A). preferable.

  It is preferable that the organic solvent (E) is contained in an amount of 100 to 1000 parts by mass based on 100 parts by mass of the component (A).

  It is preferable that the adhesive composition according to any of the above has a dielectric constant (ε) of 3.0 or less and a dielectric loss tangent (tan δ) of 0.02 or less at a frequency of 1 MHz.

  The adhesive composition according to any one of the above is preferably used for bonding a resin substrate and a resin substrate or a metal substrate.

  A laminate of a resin substrate bonded with the adhesive composition according to any one of the above and a resin substrate or a metal substrate.

  An adhesive sheet containing the laminate.

  A printed wiring board including the laminate or the adhesive sheet as a component.

  The adhesive composition according to the present invention contains a crystalline acid-modified polyolefin and an amorphous polyolefin, and further contains at least one of a carbodiimide resin and an epoxy resin. Therefore, while exhibiting excellent low dielectric properties, it is possible to obtain not only conventional polyimide and polyester films, but also high adhesion between a low-polar resin base such as LCP and a metal base, and high solder heat resistance. .

  Hereinafter, embodiments of the present invention will be described in detail.

<(A) component: crystalline acid-modified polyolefin (A)>
The component (A) is a crystalline acid-modified polyolefin. The crystalline acid-modified polyolefin (A) used in the present invention is not limited, but is a crystalline acid-modified polyolefin obtained by grafting at least one kind of α, β-unsaturated carboxylic acid and its acid anhydride to a polyolefin resin. It is preferred that Polyolefin resin refers to homopolymerization of olefin monomers exemplified by ethylene, propylene, butene, butadiene, isoprene, or copolymerization with other monomers, and hydrocarbons such as hydrides and halides of the obtained polymers. Refers to a polymer mainly composed of a skeleton. That is, the crystalline acid-modified polyolefin is obtained by grafting at least one kind of α, β-unsaturated carboxylic acid and its anhydride to at least one kind of polyethylene, polypropylene and propylene-α-olefin copolymer. Is preferred.

  The propylene-α-olefin copolymer is obtained by copolymerizing α-olefin with propylene as a main component. As the α-olefin, for example, one or several kinds of ethylene, 1-butene, 1-heptene, 1-octene, 4-methyl-1-pentene, vinyl acetate and the like can be used. Among these α-olefins, ethylene and 1-butene are preferred. The ratio between the propylene component and the α-olefin component of the propylene-α-olefin copolymer is not limited, but the propylene component is preferably at least 50 mol%, more preferably at least 70 mol%.

  Examples of at least one of the α, β-unsaturated carboxylic acids and their acid anhydrides include maleic acid, itaconic acid, citraconic acid and acid anhydrides thereof. Of these, acid anhydrides are preferred, and maleic anhydride is more preferred. Specifically, maleic anhydride-modified polypropylene, maleic anhydride-modified propylene-ethylene copolymer, maleic anhydride-modified propylene-butene copolymer, maleic anhydride-modified propylene-ethylene-butene copolymer, and the like, These acid-modified polyolefins can be used alone or in combination of two or more.

The lower limit of the acid value of the crystalline acid-modified polyolefin (A) is not particularly limited from the viewpoint of heat resistance and adhesion to a resin substrate or a metal substrate, but is preferably 50 equivalents / 10 ⁶ g or more. , More preferably 100 equivalents / 10 ⁶ g or more, further preferably 150 equivalents / 10 ⁶ g or more, particularly preferably 200 equivalents / 10 ⁶ g or more, and most preferably 250 equivalents / 10 ⁶ g or more. It is. When it is less than the above value, the compatibility with the epoxy resin (D) and / or the carbodiimide resin (C) is low, and the adhesive strength may not be exhibited. Further, the crosslink density may be low and the heat resistance may be poor. Although the upper limit is not particularly limited, it is preferably 1,000 equivalents / 10 ⁶ g or less, more preferably 900 equivalents / 10 ⁶ g or less, further preferably 800 equivalents / 10 ⁶ g or less, and particularly preferably 700 equivalents. eq / 10 ⁶ g or less, and most preferably not more than 600 eq / 10 ⁶ g. If the above value is exceeded, the adhesiveness may be reduced. In addition, the viscosity and stability of the solution may be reduced, and the pot life may be reduced. Further, the production efficiency is undesirably reduced.

  The weight average molecular weight (Mw) of the crystalline acid-modified polyolefin (A) is preferably in the range of 40,000 to 180,000. It is more preferably in the range of 50,000 to 160,000, further preferably in the range of 60,000 to 150,000, particularly preferably in the range of 70,000 to 140,000, and most preferably in the range of 80,000 to 140,000. 000-130,000. If it is less than the above value, the cohesive strength may be weak and the adhesiveness may be poor. On the other hand, if it exceeds the above-mentioned value, there may be a problem in operability when bonding with low fluidity.

  The crystallinity in the crystalline acid-modified polyolefin (A) means that the temperature is raised from -100 ° C to 250 ° C at a rate of 20 ° C / min using a differential scanning calorimeter (DSC), It indicates the peak.

  Making the acid-modified polyolefin crystalline is advantageous because it has a stronger cohesive force and is more excellent in adhesiveness and heat resistance than amorphous.

  The melting point (Tm) of the crystalline acid-modified polyolefin (A) is preferably in the range of 50C to 120C. It is more preferably in the range of 60 ° C to 100 ° C, most preferably in the range of 70 ° C to 90 ° C. When the value is less than the above value, the cohesive force derived from the crystal becomes weak, and the adhesiveness and heat resistance may be poor. On the other hand, if the above value is exceeded, the solution stability and the fluidity are low, and there may be a problem in the operability at the time of bonding.

  The heat of fusion (ΔH) of the crystalline acid-modified polyolefin (A) is preferably in the range of 5 J / g to 60 J / g. It is more preferably in the range of 10 J / g to 50 J / g, and most preferably in the range of 20 J / g to 40 J / g. When the value is less than the above value, the cohesive force derived from the crystal becomes weak, and the adhesiveness and heat resistance may be poor. On the other hand, if the above value is exceeded, the solution stability and the fluidity are low, and there may be a problem in the operability at the time of bonding.

  The method for producing the crystalline acid-modified polyolefin (A) is not particularly limited, and may be, for example, a radical grafting reaction (that is, a method in which a radical species is generated with respect to a polymer serving as a main chain, and the radical species is used as a polymerization initiation point to obtain an unsaturated carboxylic acid). A reaction of graft-polymerizing an acid and an acid anhydride).

  The radical generator is not particularly limited, but it is preferable to use an organic peroxide. The organic peroxide is not particularly limited, but may be di-tert-butylperoxyphthalate, tert-butyl hydroperoxide, dicumyl peroxide, benzoyl peroxide, tert-butylperoxybenzoate, tert-butylperoxy-. Peroxides such as 2-ethylhexanoate, tert-butylperoxypivalate, methyl ethyl ketone peroxide, di-tert-butyl peroxide and lauroyl peroxide; azobisisobutyronitrile, azobisisopropionitrile and the like Azonitriles and the like.

  The content of the component (A) in the adhesive composition of the present invention is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 10% by mass or more. Further, the content is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. If the amount is too small or too large, the adhesiveness and heat resistance may decrease.

<(B) component: amorphous polyolefin (B)>
The component (B) is an amorphous polyolefin. The amorphous polyolefin (B) used in the present invention is not limited, but homopolymerization of an olefin monomer exemplified by ethylene, propylene, butene, butadiene, isoprene, or the like, or copolymerization with another monomer, and the obtained polymer are obtained. Among polymers mainly composed of a hydrocarbon skeleton, such as hydrides and halides of such polymers, amorphous ones are preferable.

  The amorphousness of the amorphous polyolefin (B) is defined as the heat of fusion (ΔH) when the temperature is raised from −100 ° C. to 250 ° C. at 20 ° C./min using a differential scanning calorimeter (DSC). It is preferably 10 J / g or less.

  By compounding the amorphous polyolefin, it is possible to improve the wettability of the adhesive to the base material and the flexibility of the adhesive composition, thereby preventing the concentration of peeling stress at the interface between the adhesive and the base material. .

  The heat of fusion (ΔH) of the amorphous polyolefin (B) is preferably 10 J / g or less, more preferably 5 J / g or less, and still more preferably 3 J / g or less. The lower limit is not particularly limited, but is 0 J / g or more. If the above value is exceeded, the crystallinity will be high, so that the wettability to the substrate will be reduced, and the peeling stress will be concentrated on the interface, so that the adhesive strength may be reduced.

  The glass transition temperature (Tg) of the amorphous polyolefin (B) is preferably in the range of -70 to 30C. It is more preferably in the range of -50 ° C to 25 ° C, and most preferably in the range of -30 ° C to 20 ° C. If it is less than the above value, the tackiness of the adhesive is so strong that the processability is poor. On the other hand, if it exceeds the above-mentioned value, there is a problem that the adhesiveness near room temperature is reduced.

  In the adhesive composition of the present invention, the content of the amorphous polyolefin (B) is preferably in the range of 10 to 100 parts by mass with respect to 100 parts by mass of the crystalline acid-modified polyolefin (A). It is more preferably in the range of 13 to 90 parts by mass, and most preferably in the range of 15 to 80 parts by mass. When the value is less than the above value, the wettability to the substrate is reduced, and the peeling stress is concentrated on the interface, so that the adhesive strength may be reduced. When the value exceeds the above-mentioned value, the strength of the adhesive composition itself decreases, so that there is a problem that the adhesive decreases.

<(C) component: carbodiimide resin (C)>
The component (C) is a carbodiimide resin. The carbodiimide resin (C) is not particularly limited as long as it has a carbodiimide group in the molecule. Preferably, it is a polycarbodiimide having two or more carbodiimide groups in the molecule. By using the carbodiimide resin (C), the carbodiimide reacts with the carboxyl group of the acid-modified polyolefin (A), thereby increasing the interaction between the adhesive composition and the base material and improving the adhesiveness.

  In the adhesive composition of the present invention, the content of the carbodiimide resin (C) is preferably in the range of 0.5 to 30 parts by mass based on 100 parts by mass of the crystalline acid-modified polyolefin (A). More preferably, it is in the range of 1 to 25 parts by mass, most preferably 2 to 20 parts by mass. When it is less than the above-mentioned value, there is a problem that no interaction with the base material is exhibited and the adhesiveness is reduced. If it exceeds the above value, there is a problem that the pot life of the adhesive is reduced and the low dielectric property is reduced.

<(D) component: epoxy resin (D)>
The component (D) is an epoxy resin. The epoxy resin (D) is not particularly limited as long as it has two or more glycidyl groups in the molecule. Specifically, although not particularly limited, 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, At least one selected from the group consisting of tetraglycidyldiaminodiphenylmethane, triglycidylparaaminophenol, tetraglycidylbisaminomethylcyclohexanone, and N, N, N ', N'-tetraglycidyl-m-xylenediamine can be used. Preferably, a bisphenol A type epoxy resin, a novolak type epoxy resin or a dicyclopentadiene type epoxy resin is used.

  In the adhesive composition of the present invention, the content of the epoxy resin (D) is preferably in the range of 1 to 30 parts by mass, and more preferably 2 to 15 parts by mass, based on 100 parts by mass of the crystalline acid-modified polyolefin (A). It is more preferably in the range of parts by mass, most preferably in the range of 3 to 10 parts by mass. If it is less than the above range, a sufficient curing effect cannot be obtained, and the adhesiveness and heat resistance may be reduced. Above the above range, there is a problem that the pot life of the adhesive is reduced and the low dielectric property is reduced.

<Adhesive composition>
The adhesive composition of the present invention contains the crystalline acid-modified polyolefin (A) and the amorphous polyolefin (B), and further contains one of the carbodiimide resin (C) and the epoxy resin (D). Things.

  The adhesive composition of the present invention contains the component (A), the component (B) and the component (C), so that the adhesive composition has excellent electric properties (low dielectric properties) and a low polarity resin base material such as LCP. High adhesiveness to the substrate can be exhibited. In addition, by containing the component (A), the component (B) and the component (D), not only the electrical characteristics are excellent, but also a high solder heat resistance between the low-polar resin base such as LCP and the metal base is exhibited. Can be. Further, by containing the components (A) to (D), all of excellent adhesiveness, solder heat resistance and electric properties (low dielectric properties) between a low-polar resin base such as LCP and a metal base are exhibited. be able to. That is, the adhesive coating film (adhesive layer) after applying and curing the adhesive composition on the substrate exhibits excellent low dielectric constant characteristics. Specifically, the dielectric constant (ε) of the cured adhesive coating film at a frequency of 1 MHz is preferably 3.0 or less, more preferably 2.6 or less, and more preferably 2.3 or less. Is more preferable. The dielectric loss tangent (tan δ) is preferably 0.02 or less, more preferably 0.01 or less, and even more preferably 0.005 or less. Furthermore, the adhesive composition of the present invention preferably has a dielectric constant (ε) of 3.0 or less, preferably 2.6 or less, in the entire range of frequencies of 1 MHz to 1 GHz of the cured adhesive coating film. More preferably, it is still more preferably 2.3 or less. The dielectric loss tangent (tan δ) is preferably 0.02 or less, more preferably 0.01 or less, and even more preferably 0.005 or less. In addition, it is particularly preferable that the dielectric constant (ε) and the dielectric loss tangent (tan δ) of the cured adhesive coating film in the entire frequency range of 1 MHz to 10 GHz are within the above ranges.

<(E) component: organic solvent (E)>
The adhesive composition of the present invention can further contain an organic solvent (E). The organic solvent (E) used in the present invention is not particularly limited as long as it can dissolve the crystalline acid-modified polyolefin (A), the amorphous polyolefin (B), the carbodiimide resin (C), and the epoxy resin (D). Not done. 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, and chloroform; alcoholic solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, and phenol; acetone, methyl isobutyl ketone; Ketone solvents such as methyl ethyl ketone, pentanone, hexanone, cyclohexanone, isophorone, and acetophenone; cellsolves such as methylcellsolve and ethylcellsolve; methyl acetate, ethyl acetate, and vinegar Ester solvents such as butyl, methyl propionate and 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 Glycol ether solvents such as mono-n-butyl ether and tetraethylene glycol mono-n-butyl ether can be used, and one or more of these can be used in combination. As a preferred embodiment, it is a mixed solvent of an alicyclic hydrocarbon and a ketone solvent, among which it is preferable to use cyclohexane or methylcyclohexane for the alicyclic hydrocarbon, and to use methyl isobutyl ketone or methyl ethyl ketone for the ketone solvent . The mixing ratio of the alicyclic hydrocarbon and the ketone solvent is preferably alicyclic hydrocarbon / ketone solvent = 50 to 90/50 to 10 (mass ratio), and preferably 55 to 85/45. To 15 (mass ratio), more preferably 60 to 80/40 to 20 (mass ratio).

  The organic solvent (E) is preferably in the range of 100 to 1,000 parts by mass, more preferably in the range of 200 to 900 parts by mass, based on 100 parts by mass of the crystalline acid-modified polyolefin (A). Most preferably, it is at least 800 parts by mass. If it is less than the above range, the liquid and the pot life properties are reduced. Further, when the ratio exceeds the above range, there is a problem that the production cost and the transportation cost are disadvantageous.

  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, and silane coupling agents.

(Flame retardants)
The adhesive composition of the present invention may optionally contain a flame retardant. Examples of the flame retardant include bromine-based, phosphorus-based, nitrogen-based, and metal hydroxide compounds. Among them, phosphorus-based flame retardants are preferred, and known phosphorus-based flame retardants such as phosphate esters, for example, trimethyl phosphate, triphenyl phosphate, tricresyl phosphate, and the like, phosphates, for example, aluminum phosphinate, and phosphazene can be used. . When a flame retardant is contained, the flame retardant is preferably contained in the range of 1 to 200 parts by mass, more preferably in the range of 5 to 150 parts by mass, based on 100 parts by mass of the components (A) to (D) in total. , 10 to 100 parts by mass. If it is less than the above range, the flame retardancy is low. If it exceeds the above range, there is a problem that the adhesiveness, heat resistance, electric properties and the like are deteriorated.

(Tackifier)
The adhesive composition of the present invention may optionally contain a tackifier. Examples of the tackifier include polyterpene resin, rosin resin, aliphatic petroleum resin, alicyclic petroleum resin, copolymer petroleum resin, styrene resin, hydrogenated petroleum resin and the like, and improve the adhesive strength. Used for purposes. These may be used alone or in any combination of two or more.

(Filler)
The adhesive composition of the present invention may optionally contain a filler such as silica. It is very preferable to mix silica because the heat resistance characteristics are improved. As silica, hydrophobic silica and hydrophilic silica are generally known. Here, hydrophobic silica treated with dimethyldichlorosilane, hexamethyldisilazane, octylsilane, or the like to impart moisture absorption is used. Is good. The compounding amount of the silica is preferably 0.05 to 30 parts by mass based on 100 parts by mass of the total of components (A) to (D). If the amount is less than 0.05 parts by mass, the effect of improving heat resistance may not be exhibited. On the other hand, if it exceeds 30 parts by mass, poor dispersion of silica may occur, or the viscosity of the solution may become too high, resulting in a problem in workability or a decrease in adhesiveness.

(Silane coupling agent)
The adhesive composition of the present invention may optionally contain a silane coupling agent. The addition of a silane coupling agent is very preferable because the properties of adhesion to metal and heat resistance are improved. The silane coupling agent is not particularly limited, but includes those having an unsaturated group, those having a glycidyl group, those having an amino group, and the like. Among them, glycidyl such as γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane and β- (3,4-epoxycyclohexyl) ethyltriethoxysilane from the viewpoint of heat resistance A silane coupling agent having a group is more preferred. The compounding amount of the silane coupling agent is preferably 0.5 to 20 parts by mass based on 100 parts by mass of the total of components (A) to (D). If the amount is less than 0.5 parts by mass, the heat resistance may be poor. On the other hand, if it exceeds 20 parts by mass, poor heat resistance and poor adhesiveness may occur.

<Laminate>
The laminate of the present invention is obtained by laminating an adhesive composition on a base material (two-layer laminate of base material / adhesive layer) or further laminating a base material (base material / adhesive layer / (A three-layer laminate of a base material). Here, the adhesive layer refers to a layer of the adhesive composition after the adhesive composition of the present invention is applied to a substrate and dried. The laminate of the present invention can be obtained by applying and drying the adhesive composition of the present invention to various substrates according to a conventional method, and further laminating another substrate.

<Substrate>
In the present invention, the substrate is not particularly limited as long as the adhesive composition of the present invention can be applied and dried to form an adhesive layer. Examples include metal substrates such as plates and metal foils, and papers.

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

  Any conventionally known conductive material that can be used for a circuit board can be used as the metal substrate. Examples of the material include various metals such as SUS, copper, aluminum, iron, steel, zinc, and nickel, and alloys, plated products, and metals treated with other metals such as zinc and chromium compounds. Preferably it is a metal foil, more preferably a 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 further preferably 10 μm or more. Further, 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 small, it may be difficult to obtain a sufficient electrical performance of the circuit. On the other hand, if the thickness is too large, the processing efficiency or the like during circuit fabrication may be reduced. The metal foil is usually provided in a roll form. The form of the metal foil used when manufacturing the printed wiring board of the present invention is not particularly limited. When a ribbon-shaped metal foil is used, its length is not particularly limited. Also, the width is not particularly limited, but is preferably about 250 to 500 cm.

  Examples of papers include high quality paper, kraft paper, roll paper, glassine paper, and the like. Further, as the composite material, glass epoxy or the like can be exemplified.

  From the adhesive force with the adhesive composition, from the durability, as the substrate, 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 obtained by laminating the laminate and the release substrate via an adhesive composition. Specific examples of the configuration include a laminate / adhesive layer / release substrate, or a release substrate / adhesive layer / laminate / adhesive layer / release substrate. By laminating the release substrate, it functions as a protective layer of the substrate. In addition, by using the release substrate, the release substrate can be released from the adhesive sheet, and the adhesive layer can be transferred to another substrate.

  The adhesive sheet of the present invention can be obtained by applying and drying the adhesive composition of the present invention to various laminates according to a conventional method. Also, after drying, if a release substrate is attached to the adhesive layer, it can be rolled up without causing set-off to the substrate, which improves operability and protects the adhesive layer for preservation. Excellent and easy to use. Further, if another release substrate is adhered to the release substrate as needed after coating and drying on the release substrate, the adhesive layer itself can be transferred to another substrate.

<Release substrate>
The release substrate is not particularly limited, for example, a high-quality paper, kraft paper, roll paper, on both sides of paper such as glassine paper, clay, polyethylene, a coating layer of a filler such as polyethylene and polypropylene. And a silicone-based, fluorine-based, or alkyd-based release agent applied on each of the coating layers. In addition, various olefin films such as polyethylene, polypropylene, ethylene-α-olefin copolymer, and propylene-α-olefin copolymer alone, and those obtained by coating the release agent on a film such as polyethylene terephthalate may also be used. For the reason that the release force between the release substrate and the adhesive layer and the silicone adversely affect the electrical properties, both sides of the high-quality paper are treated with polypropylene and treated with an alkyd-based release agent, Alternatively, it is preferable to use an alkyd release agent on polyethylene terephthalate.

  In the present invention, the method for coating the adhesive composition on the substrate is not particularly limited, and examples thereof include a comma coater and a reverse roll coater. Alternatively, if necessary, an adhesive layer can be provided directly or by a transfer method on a rolled copper foil or a polyimide film which is a constituent material of a printed wiring board. The thickness of the adhesive layer after drying is appropriately changed as necessary, but is preferably in the range of 5 to 200 μm. When the thickness of the adhesive film is less than 5 μm, the adhesive strength is insufficient. When the thickness is 200 μm or more, drying is insufficient, the residual solvent increases, and there is a problem that blisters are generated at the time of pressing for manufacturing a printed wiring board. The drying conditions are not particularly limited, but the residual solvent ratio after drying is preferably 1% by mass or less. If it exceeds 1% by mass, there is a problem in that the residual solvent foams when the printed wiring board is pressed, causing blisters.

<Printed wiring board>
The “printed wiring board” in the present invention includes, as a component, a laminate formed from a metal foil forming a conductive circuit and a resin base material. The printed wiring board is manufactured by a conventionally known method such as a subtractive method using a metal-clad laminate. If necessary, a so-called flexible circuit board (FPC), a flat cable, or a tape automated bonding, in which a conductor circuit formed by a metal foil is partially or entirely covered with a cover film, screen printing ink, or the like. General term for circuit boards for TAB).

  The printed wiring board of the present invention can have any laminated configuration that can be adopted as a printed wiring board. For example, it can be a printed wiring board composed of four layers of a base film layer, a metal foil layer, an adhesive layer, and a cover film layer. Further, for example, a printed wiring board including five layers of a base film layer, an adhesive layer, a metal foil layer, an adhesive layer, and a cover film layer can be provided.

  Furthermore, if necessary, a configuration in which two or three or more of the above-described printed wiring boards are stacked may be employed.

  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, not only conventional polyimides, polyester films, and copper foils constituting a printed wiring board, but also has high adhesiveness to a low-polarity resin base material such as LCP. In addition, solder reflow resistance can be obtained, and the adhesive layer itself has excellent low dielectric properties. Therefore, it is suitable as an adhesive composition used for coverlay films, laminates, copper foil with resin, and bonding sheets.

  In the printed wiring board of the present invention, as the base film, any resin film conventionally used as a base material of the printed wiring board can be used. Examples of the resin of 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 adhesiveness to low-polar substrates such as liquid crystal polymers, polyphenylene sulfide, syndiotactic polystyrene, and polyolefin resins.

<Cover film>
As the cover film, any conventionally known insulating film as an insulating film for a printed wiring board can be used. For example, manufactured from various polymers such as polyimide, polyester, polyphenylene sulfide, polyether sulfone, polyether ether ketone, aramid, polycarbonate, polyarylate, polyimide, polyamide imide, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, and polyolefin resin. The film to be used is usable. More preferably, it is a polyimide film or a liquid crystal polymer film.

  The printed wiring board of the present invention can be manufactured by using any conventionally known process except that the above-described materials of the respective layers are used.

  In a preferred embodiment, a semi-finished product in which an adhesive layer is laminated on a cover film layer (hereinafter, referred to as a “cover film side semi-finished product”) is manufactured. 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 "base film side two-layer semi-finished product") or an adhesive layer laminated on the base film layer To manufacture a semi-finished product on which a metal foil layer is laminated to form a desired circuit pattern (hereinafter, referred to as “base film-side three-layer semi-finished product”) (hereinafter referred to as base film-side two-layer semi-finished product) The term “substrate film side semi-finished product” includes the three-layer semi-finished product on the substrate film side). By laminating the semi-finished product on the cover film side and the semi-finished product on the base film thus obtained, a printed wiring board having four or five layers can be obtained.

  The base film-side semi-finished product is, for example, (A) a step of applying a solution of a resin to be a base film to the metal foil, and initially drying the coating film (B). It is obtained by a manufacturing method including a step of heat-treating and drying the laminate with the dried coating film (hereinafter, referred to as “heat-treatment / desolvation step”).

  A conventionally known method can be used for forming a circuit in the metal foil layer. An active method or a subtractive method may be used. Preferably, it is a subtractive method.

  The resulting base film side semi-finished product may be used as it is for lamination with the cover film side semi-finished product, or for lamination with the cover film side semi-finished product after the release film is laminated and stored. May be used.

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

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

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

  When the reinforcing material side semi-finished product is a soft and rollable reinforcing material such as a polyimide film, it is preferable that the reinforcing material is manufactured by applying an adhesive to the reinforcing material. Further, for example, in the case of a reinforcing plate such as SUS, a metal plate such as aluminum, a plate obtained by curing glass fiber with an epoxy resin, and the like, which cannot be rolled up hard, by transferring and applying an adhesive previously applied to a release base material, Preferably, it is manufactured. Further, if necessary, a crosslinking reaction in the applied adhesive can be performed. In a preferred embodiment, the adhesive layer is semi-cured.

  The obtained reinforcing material side semi-finished product may be used as it is for bonding to the back side of the printed wiring board, or it may be used for laminating the release film to the base film side semi-finished product after storage. May be.

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

<Example>
Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the embodiments. In the examples and comparative examples, “parts” simply indicates parts by mass.

(Physical property evaluation method)

Acid value In the present invention, the acid value (equivalent / 10 ⁶ g) is determined by using FT-IR (manufactured by Shimadzu Corporation, FT-IR8200PC) to determine the stretching peak (1780 cm) of the carbonyl (C = O) bond of maleic anhydride. ^-1 ) absorbance (I), isotactic peculiar peak (840 cm ^-1 ) absorbance (II), and factor (f) obtained from a calibration curve prepared with a chloroform solution of maleic anhydride (manufactured by Tokyo Chemical Industry). It is a value calculated using the following equation.
Acid value = [absorbance (I) / absorbance (II) × (f) / molecular weight of maleic anhydride × 2 × 10 ⁴ ]
Molecular weight of maleic anhydride: 98.06

Weight average molecular weight (Mw)
The weight average molecular weight in the present invention is a value measured by gel permeation chromatography (hereinafter, GPC, standard substance: polystyrene resin, mobile phase: tetrahydrofuran).

Melting point (Tm), heat of fusion (ΔH), glass transition temperature (Tg)
In the present invention, the melting point, heat of fusion, and glass transition temperature (Tg) are annealed at a heating rate of 20 ° C./min from room temperature to 200 ° C. using a differential scanning calorimeter (hereinafter, DSC), and quenched with liquid nitrogen. The temperature was raised from −100 ° C. to 200 ° C. at a rate of 20 ° C./min, the intersection of the tangent at the inflection point with the base line (glass transition temperature), the top temperature of the melting peak (melting point), and the It is a value measured from the area surrounded by the extension line and the melting peak.

(1) Evaluation of pot life Pot life is defined as a formula in which a crystalline acid-modified polyolefin, an amorphous polyolefin, a carbodiimide resin, and an epoxy resin are blended, and immediately after blending or after 24 hours in a room temperature atmosphere after blending. Refers to the stability of the solution. If the pot life property is good, it means that the solution has a small increase in viscosity and can be stored for a long period of time. If the pot life property is poor, the viscosity of the solution increases (thickness), and if it is severe, This indicates that gelation occurs, making it difficult to apply the composition to a base material and making it impossible to store for a long period of time.
<Evaluation criteria>
：: Applicable △: Viscosity increased and poor workability, but applicable ×: Unapplicable due to viscosity increase or gelation

(2) Peel strength (adhesion)
The adhesive composition described below is coated on a 25 μm-thick polyimide film (Kaneka Corporation, Apical) or a 50 μm-thick LCP film (Kuraray Co., Ltd., Vexter) so that the thickness after drying is 25 μm. It was applied and dried at 130 ° C. for 3 minutes. The adhesive film (B-stage product) thus obtained was bonded to a rolled copper foil of 18 μm. The bonding was performed by pressing at 160 ° C. for 30 seconds under a pressure of 40 kgf / cm ² so that the glossy surface of the rolled copper foil was in contact with the adhesive. Next, the sample was cured by heat treatment at 140 ° C. for 4 hours to obtain a peel strength evaluation sample. The peel strength was measured at 25 ° C. by pulling a film and performing a 90 ° peel test at a pulling speed of 50 mm / min. This test shows the adhesive strength at room temperature.
<Evaluation criteria>
☆: 1.5 N / mm or more ◎: 1.3 N / mm or more and less than 1.5 N / mm ○: 1.0 N / mm or more and less than 1.3 N / mm △: 0.8 N / mm or more and less than 1.0 N / mm ×: less than 0.8 N / mm

(3) Solder heat resistance A sample was prepared in the same manner as described above, and a 2.5 cm × 2.5 cm sample piece was dried at 120 ° C. for 30 minutes, and flowed for 1 minute in a molten solder bath at each temperature. The temperature at which no change in appearance such as swelling occurred was measured.
<Evaluation criteria>
☆: 310 ° C or more ◎: 300 ° C or more and less than 310 ° C ○: 290 ° C or more and less than 300 ° C △: 270 ° C or more and less than 290 ° C ×: less than 270 ° C

(4) Dielectric constant (ε) and dielectric tangent (tan δ)
The adhesive composition described below was applied to a release film having a thickness of 50 μm so that the thickness after drying was 30 μm, and dried at 130 ° C. for 3 minutes. Next, it was cured by heat treatment at 140 ° C. for 4 hours, peeled off from the release film, and measured. The measurement was performed using PRECISION LCR meter HP-4284A under the conditions of 22 ° C. and 58% RH at a frequency of 1 MHz, and evaluated as follows. Similarly, measurement was performed using VECTOR NETWORK ANALYZER HP8510C, SYNTHESIZED SWEEPER HP83651A, and TEST SET HP8517B under the conditions of 22 ° C., 58 RH%, and a frequency of 1 GHz, and evaluated as follows.
<Evaluation criteria for dielectric constant>
◎: 2.3 or less ○: More than 2.3 to 2.6 or less Δ: More than 2.6 to 3.0 or less ×: More than 3.0 <Evaluation criteria for dielectric loss tangent>
◎: 0.005 or less ○: More than 0.005 and less than 0.01 △: More than 0.01 and less than 0.02 ×: More than 0.02

(Crystalline acid-modified polyolefin)
Production Example 1
In a 1 L autoclave, 100 parts by mass of a propylene-butene copolymer ("Tafmer (registered trademark) XM7080" manufactured by Mitsui Chemicals, Inc.), 150 parts by mass of toluene, 22 parts by mass of maleic anhydride, 6 parts by mass of di-tert-butyl peroxide Was added, and the mixture was heated to 140 ° C., and further stirred for 3 hours. Then, after cooling the obtained reaction solution, it was poured into a container containing a large amount of methyl ethyl ketone to precipitate a resin. Thereafter, a liquid containing the resin was centrifuged to separate and purify an acid-modified propylene-butene copolymer on which maleic anhydride was graft-polymerized, and (poly) maleic anhydride and a low molecular weight product. Thereafter, by drying under reduced pressure at 70 ° C. for 5 hours, a maleic anhydride-modified propylene-butene copolymer (CO-1, acid value 570 equivalent / 10 ⁶ g, weight average molecular weight 55,000, Tm 75 ° C., ΔH25J / G).

Production Example 2
A maleic anhydride-modified propylene-butene copolymer (CO-2, acid value 410 equivalents / 10 ⁶ g, weight) was prepared in the same manner as in Production Example 1 except that the charged amount of maleic anhydride was changed to 19 parts by mass. An average molecular weight of 60,000, Tm of 75 ° C, and ΔH30J / g) were obtained.

Production Example 3
The same procedure as in Production Example 1 was carried out except that the charged amount of maleic anhydride was changed to 4 parts by mass, and di-tert-butyl peroxide was changed to 0.5 parts by mass, whereby a maleic anhydride-modified propylene-butene copolymer ( CO-3, acid value 150 equivalent / 10 ⁶ g, weight average molecular weight 160,000, Tm80 ° C, ΔH25J / g) were obtained.

Production Example 4
A maleic anhydride-modified propylene-butene copolymer (CO-4, acid value 980 equivalent / 10 ⁶ g, weight) was prepared in the same manner as in Production Example 1 except that the charged amount of maleic anhydride was changed to 30 parts by mass. An average molecular weight of 40,000, Tm of 70 ° C. and ΔH25J / g) were obtained.

Production Example 5
The same procedure as in Production Example 1 was carried out except that the charged amount of maleic anhydride was changed to 2 parts by mass and di-tert-butyl peroxide was changed to 0.5 parts by mass, whereby a maleic anhydride-modified propylene-butene copolymer ( CO-5, acid value 53 equivalents / 10 ⁶ g, weight average molecular weight 200,000, Tm80 ° C, ΔH25J / g) were obtained.

(Amorphous polyolefin)
Production Example 6
To a 1 L autoclave, 100 parts by mass of an amorphous polyolefin ("Tafselen (registered trademark) X1102" manufactured by Sumitomo Chemical Co., Ltd.), 150 parts by mass of methylcyclohexane, 1 part by mass of maleic anhydride, and 1 part by mass of di-tert-butyl peroxide were added. After stirring for 3 hours, the mixture was further added with 130 parts by mass of methylcyclohexane and 120 parts by mass of methyl ethyl ketone, and then an amorphous acid-modified polyolefin (AO-1, acid value 50 equivalent / 10 ⁶ g, A solution having a weight average molecular weight of 140,000, (H0J / g, Tg-10 ° C) was obtained.

Production Example 7
In a 500 ml four-necked flask equipped with a water-cooled reflux condenser and a stirrer, 100 parts by mass of an amorphous polyolefin ("Tafselen (registered trademark) X1102" manufactured by Sumitomo Chemical Co., Ltd.), 280 parts by mass of methylcyclohexane, and 120 parts by mass of methylethylketone were added. In addition, a solution of an amorphous polyolefin (Tafselen X1102, acid value 0 equivalent / 10 ⁶ g, weight average molecular weight 658,000, ΔH0J / g, Tg-9 ° C.) was obtained.

Example 1
In a 500 ml four-necked flask equipped with a water-cooled reflux condenser and a stirrer, 100 parts by mass of the maleic anhydride-modified propylene-butene copolymer (CO-1) obtained in Production Example 1 was mixed with an amorphous acid. 100 parts by mass of the polyolefin solution (20 parts by mass as a solid resin), 224 parts by mass of methylcyclohexane and 96 parts by mass of methyl ethyl ketone were charged, and the mixture was heated to 80 ° C. with stirring and dissolved by continuing stirring for 1 hour. The solution obtained by cooling was mixed with 5 parts by mass of carbodiimide resin V-05 and 10 parts by mass of epoxy resin YDCN-700-10 to obtain an adhesive composition. Table 1 shows the compounding amount, pot life, adhesive strength, solder heat resistance, and electrical characteristics (frequency 1 MHz).

Examples 2 to 13
The crystalline acid-modified polyolefin, the amorphous polyolefin, the carbodiimide resin, and the epoxy resin were changed to those shown in Table 1, and in the same manner as in Example 1, the amounts were changed so as to become the respective compounding amounts shown in Table 1. Examples 2 to 13 were performed. Table 1 shows the pot life, adhesive strength, solder heat resistance, and electrical properties (frequency 1 MHz). In Example 2, when the electrical characteristics were measured under the condition of a frequency of 1 GHz, the evaluation of the dielectric constant (ε) was “◎”, and the evaluation of the dielectric loss tangent (tan δ) was “◎”.

Comparative Example 1
The crystalline acid-modified polyolefin, amorphous polyolefin, carbodiimide resin, and epoxy resin were changed to those shown in Table 2, and in the same manner as in Example 1, the amounts were changed so as to become the respective compounding amounts shown in Table 2. Example 1 was performed. Table 2 shows the compounding amount, pot life, adhesive strength, solder heat resistance, and electrical characteristics (frequency 1 MHz).

Comparative Example 2
The carboxyl group-containing acrylonitrile butadiene rubber NBR (manufactured by JSR Corporation), carbodiimide resin, and epoxy resin were changed to those shown in Table 2, and the amounts were changed in the same manner as in Example 1 so as to obtain the compounding amounts shown in Table 2. Comparative Example 2 was performed. Table 2 shows the compounding amount, pot life, adhesive strength, solder heat resistance, and electrical characteristics (frequency 1 MHz). When the electrical characteristics were measured under the condition of a frequency of 1 GHz, the evaluation of the dielectric constant (ε) was “x” and the evaluation of the dielectric loss tangent (tan δ) was “x”.

The carbodiimide resin (C) and epoxy resin (D) used in Tables 1 and 2 are as follows.
Carbodiimide resin: V-05 (manufactured by Nisshinbo Chemical Inc.)
Carbodiimide resin: V-03 (manufactured by Nisshinbo Chemical Inc.)
o-Cresol novolak epoxy resin: YDCN-700-10 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.)
Bisphenol A type epoxy resin: JER-828 (Mitsubishi Chemical Corporation)
Dicyclopentadiene type epoxy resin: HP-7200 (manufactured by DIC)

  As is clear from Table 1, in Examples 1 to 13, the liquid crystal polymer (LCP) and the copper foil were excellent in pot life, while having excellent adhesiveness and solder heat resistance with the polyimide (PI) and the copper foil. Has excellent adhesion and solder heat resistance. In addition, the electrical properties of the adhesive composition are good because both the dielectric constant and the dielectric loss tangent are low. On the other hand, as is clear from Table 2, in Comparative Example 1, since the amorphous polyolefin was not blended, the stress could not be relaxed and the adhesive strength was low. In Comparative Example 2, since no crystalline acid-modified polyolefin was blended, the adhesive strength to LCP was low, and the low dielectric properties of the adhesive composition were inferior.

  According to the present invention, not only conventional polyimide and polyethylene terephthalate films, but also a resin base material having low dielectric properties such as LCP and a metal base material such as copper foil have a high adhesiveness and a high solder heat resistance. It is possible to obtain an adhesive composition, an adhesive sheet, and a laminate bonded using the same, which are excellent in low dielectric properties. Due to the above properties, it is useful in flexible printed wiring board applications, particularly in FPC applications requiring low dielectric properties (low dielectric constant and low dielectric loss tangent) in a high frequency range.

Claims (9)

Following component (A) contain the component (B) and (C) component in the frequency 1 MHz, the dielectric constant (epsilon) is not more than 3.0, the adhesive dielectric loss tangent (tan [delta) is 0.02 or less Composition.
(A) component: crystalline acid-modified polyolefin (B) component: amorphous polyolefin (C) component: carbodiimide resin   The adhesive composition according to claim 1, wherein the component (A) contains 5% by mass or more.   It contains the component (A), the component (B) and the component (C), and 10 to 100 parts by mass of the component (B) and 0.5 to 30 parts by mass of the component (C) based on 100 parts by mass of the component (A). The adhesive composition according to claim 1, further comprising: It contains the component (A), the component (B), the component (C) and the component (D), and 10 to 100 parts by mass of the component (B), and 100 parts by mass of the component (C) per 100 parts by mass of the component (A). 5-30 parts by weight, the adhesive composition according to claim 1, containing from 1 to 30 parts by weight component (D).
Component (D): epoxy resin The adhesive composition according to any one of claims 1 to 4 , comprising 100 to 1000 parts by mass of the organic solvent (E) based on 100 parts by mass of the component (A). The adhesive composition according to any one of claims 1 to 5 , which is used for bonding a resin substrate and a resin substrate or a metal substrate. Laminate of the resin substrate which is bonded, the resin substrate or a metal substrate by an adhesive composition according to any one of claims 1-6. An adhesive sheet containing the laminate according to claim 7 . A printed wiring board comprising the laminate according to claim 7 or the adhesive sheet according to claim 8 as a constituent element.