KR20220161283A - Adhesive compositions, and adhesive sheets, laminates, and printed wiring boards - Google Patents

Abstract

[PROBLEMS] To provide an adhesive composition having excellent solvent solubility, heat resistance, adhesive strength, low dielectric constant and dielectric loss tangent, and excellent dielectric properties, and adhesive sheets, laminates, and printed wiring boards containing the same.
[Solution] An adhesive composition containing polyester and a curing agent, wherein the polyester has a polyhydric carboxylic acid component and a polyhydric alcohol component as structural units, and when the polyhydric carboxylic acid component is 100 mol%, naphthalendica An adhesive composition containing 50 mol% or more of a carboxylic acid component and containing at least one of a dimerdiol component and a tricyclodecane dimethanol component as a polyhydric alcohol component.

Description

Adhesive compositions, and adhesive sheets, laminates, and printed wiring boards

The present invention relates to adhesive compositions. More specifically, it relates to an adhesive composition used for adhesion between a resin substrate and a resin substrate or a metal substrate. In particular, it relates to an adhesive composition for a flexible printed wiring board (hereinafter abbreviated as FPC), and an adhesive sheet having a layer formed therefrom, a laminate, and a printed wiring board.

Polyester is widely used as a raw material for resin compositions used in coating agents, inks and adhesives, and is generally composed of polyhydric carboxylic acids and polyhydric alcohols. Since flexibility and molecular weight can be freely controlled by selecting and combining polyhydric carboxylic acids and polyhydric alcohols, they are widely used in various applications including coating agent applications and adhesive applications.

Among them, polyester has excellent adhesion to metals including copper, and has been used in adhesives such as FPC by mixing a curing agent such as an epoxy resin. (eg Patent Document 1).

Since FPCs have excellent flexibility, they can respond to multifunctionality and miniaturization of personal computers (PCs) and smart phones, and for this reason, they are widely used to insert electronic circuit boards into narrow and complicated interiors. In recent years, miniaturization, weight reduction, high density, and high output of electronic devices are progressing, and due to this trend, the demand for the performance of a wiring board (electronic circuit board) is becoming more and more sophisticated. In particular, with the high-speed transmission signal in the FPC, the high-frequency signal is progressing. Accordingly, demand for low dielectric properties (low dielectric constant, low dielectric loss tangent) in the high frequency region is increasing for FPCs. In addition, regarding the base material used for FPC, not only conventional polyimide (PI) and polyethylene terephthalate (PET), but also base films such as liquid crystal polymer (LCP) and syndiotactic polystyrene (SPS) having low dielectric properties are used. It is proposed. In order to achieve such a low dielectric property, measures are taken to reduce dielectric loss of FPC substrates and adhesives. As an adhesive, development of a combination of polyolefin and epoxy (Patent Document 2) and the like is in progress.

Patent Document 1: Japanese Patent Publication Hei 6-104813 Patent Document 2: WO2016/047289 Publication

However, the polyester resin described in Patent Literature 1 has a high relative permittivity and a high dielectric loss tangent, and does not have the above-described low dielectric properties, making it unsuitable for FPCs in the high frequency region. In addition, it is difficult to say that the adhesive disclosed in Patent Literature 2 is excellent in heat resistance of an adhesive used between a reinforcing plate or between layers.

The present invention is made against the background of these prior art problems. That is, an object of the present invention is to provide an adhesive composition having excellent solvent solubility, heat resistance, adhesive strength, low dielectric constant and dielectric loss tangent, and excellent dielectric properties, and adhesive sheets, laminates and printed wiring boards containing the same. .

MEANS TO SOLVE THE PROBLEM The present inventors discovered that the said subject was solvable by the means shown below, as a result of earnest examination, and reached this invention.

That is, the present invention consists of the following configurations.

An adhesive composition containing polyester and a curing agent, wherein the polyester has a polyhydric carboxylic acid component and a polyhydric alcohol component as structural units, and when the polyhydric carboxylic acid component is 100 mol%, a naphthalenedicarboxylic acid component 50 mol% or more, and as a polyhydric alcohol component, an adhesive composition containing at least one of a dimer diol component and a tricyclodecane dimethanol component.

An adhesive composition wherein the polyester has a glass transition temperature of -30°C or higher.

The adhesive composition having a dielectric constant (εc) of 3.0 or less and a dielectric loss tangent (tan δ) of 0.008 or less at 10 GHz.

An adhesive sheet having a layer formed by the adhesive composition.

A laminate having a layer formed by the adhesive composition.

A printed wiring board comprising the laminate as a component.

The adhesive composition of the present invention is excellent in solvent solubility, heat resistance and adhesive strength, and also excellent in dielectric properties. For this reason, it is suitable for FPC adhesives, adhesive sheets, laminates, and printed wiring boards in the high-frequency region.

Hereinafter, one embodiment of the present invention will be described in detail below. However, the present invention is not limited to this, and can be implemented in an aspect in which various modifications are added within the range already described.

<Polyester>

The polyester in the present invention has a chemical structure obtained by a polycondensate of a polyhydric carboxylic acid component and a polyhydric alcohol component, and the polyhydric carboxylic acid component and polyhydric alcohol component are selected from one or more selected components, respectively. is made up of

Polyester in this invention contains 50 mol% or more of naphthalenedicarboxylic acid components in 100 mol% of all polyhydric carboxylic acid components. Preferably it is 70 mol% or more, more preferably 80 mol% or more, particularly preferably 90 mol% or more, and even 100 mol% is not a problem. Dielectric properties of polyester are improved by using a large amount of naphthalenedicarboxylic acid component.

As the naphthalenedicarboxylic acid component, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 1 , 8-naphthalenedicarboxylic acid etc. can be mentioned, Any can be used, You may use 2 or more types. Among them, 2,6-naphthalenedicarboxylic acid is preferable because of its excellent reactivity and availability during polymerization.

The polyester of the present invention may contain a polyhydric carboxylic acid component other than the naphthalenedicarboxylic acid component. The polyvalent carboxylic acid component other than the naphthalene dicarboxylic acid component is not particularly limited, but the polyhydric carboxylic acid component is preferably an aromatic polycarboxylic acid component or an alicyclic polyvalent carboxylic acid component, and an aromatic dicarboxylic acid component is preferred. It is more preferable that it is a carboxylic acid component or an alicyclic dicarboxylic acid component. Excellent dielectric properties can be expressed by using an aromatic polyhydric carboxylic acid component or an alicyclic polyhydric carboxylic acid component as a copolymerization component.

The aromatic dicarboxylic acid component is not particularly limited, but terephthalic acid, isophthalic acid, orthophthalic acid, 4,4'-dicarboxybiphenyl, 5-sodium sulfoisophthalic acid, or esters thereof can be used.

Examples of the alicyclic dicarboxylic acid include, but are not particularly limited to, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, tetrahydrophthalic anhydride, Methyl tetrahydrophthalic anhydride, hydrogenated naphthalene dicarboxylic acid, etc. can be used.

Polyester in this invention needs to contain at least one of dimer diol and tricyclodecane dimethanol as a polyhydric alcohol component. Preferably, the total amount of dimerdiol and tricyclodecane dimethanol is contained at 20 mol% or more in 100 mol% of the polyhydric alcohol component. More preferably, it is 30 mol% or more, More preferably, it is 40 mol% or more. By containing dimerdiol or tricyclodecane dimethanol, the low dielectric properties of the polyester adhesive composition are improved. When tricyclodecane dimethanol is contained, the dielectric loss tangent is particularly excellent. When dimerdiol is contained, solvent solubility is also improved. It is also preferable to use dimerdiol and tricyclodecanediol together.

The dimer diol is obtained by reducing the carboxyl group of dimer acids having 20 to 48 carbon atoms obtained by dimerizing C10 to 24 unsaturated fatty acids and saturated dimer acids obtained by hydrogenating them. In addition, you may use vegetable oil as a raw material of dimer diol. Dimerdiol may also contain a trimer that is a trimer of C10-24 unsaturated fatty acids, or a saturated trimer obtained by hydrogenating a trimer.

The polyester in the present invention may contain polyhydric alcohol components other than dimer diol and tricyclodecane dimethanol. Polyhydric alcohols other than dimerdiol and tricyclodecane dimethanol are not particularly limited, but ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1 ,4-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octane diol, 2-methyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-n-propyl-1,3-propanediol, 2, 2-di-n-propyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, 2 Aliphatic polyhydric alcohols such as 4-diethyl-1,5-pentanediol and 2-ethyl-1,3-hexanediol, alicyclic polyhydric alcohols such as 1,4-cyclohexanedimethanol, polytetramethylene glycol, poly Polyalkylene ether glycol, such as propylene glycol, etc. can be used, Among these, 1 type, or 2 or more types can be used.

A trivalent or higher polyhydric carboxylic acid component and/or a trivalent or higher polyhydric alcohol component may be copolymerized with the polyester in the present invention. Examples of the trivalent or higher polyhydric carboxylic acid component include aromatic carboxylic acids such as trimellitic acid, pyromellitic acid, benzophenonetetracarboxylic acid, trimesic acid, trimellitic anhydride (TMA), and pyromellitic anhydride (PMDA). aliphatic carboxylic acids such as boxylic acid and 1,2,3,4-butanetetracarboxylic acid; and the like, and these may be used alone or in combination of two or more. Examples of the trihydric or higher polyhydric alcohol component include glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, α-methylglucose, mannitol, and sorbitol, and one or two or more of these can be used. . However, when the copolymerization amount of the trivalent or higher polyhydric carboxylic acid component and/or the trivalent or higher polyhydric alcohol component is large, the dielectric properties of polyester may be deteriorated, which is not preferable. When copolymerizing a trivalent or higher polyhydric carboxylic acid component and/or a trivalent or higher polyhydric alcohol component, the amount is preferably 5 mol% or less out of 200 mol% in total of the polyhydric carboxylic acid component and the polyhydric alcohol component, more preferably 4 mol% or less.

The glass transition temperature of the polyester in the present invention is preferably -30°C or higher, more preferably -20°C or higher. By setting the glass transition temperature in the range of -30°C or higher, good dielectric properties are exhibited, and tackiness (tackiness) on the surface of the resin tends to be suppressed, and handling of the resin is improved. Moreover, it is preferable that the glass transition temperature is 100 degrees C or less. By setting the glass transition temperature to 100°C or less, lamination can be performed even at a low temperature of about 80°C. Further, the lower the glass transition temperature, the better the adhesive strength tends to be.

As a polymerization condensation reaction method for producing the polyester of the present invention, for example, 1) a polyhydric carboxylic acid and a polyhydric alcohol are heated in the presence of a known catalyst, and a dehydration esterification step is followed by dehydration/polycondensation reaction 2) a method in which an alcohol ester of a polyhydric carboxylic acid and a polyhydric alcohol are heated in the presence of a known catalyst to undergo a transesterification reaction to conduct a dehydric alcohol/polycondensation reaction, and 3) a method in which depolymerization is performed. . In the methods 1) and 2) above, part or all of the acid component may be substituted with an acid anhydride.

When producing the polyester in the present invention, conventionally known polymerization catalysts such as titanium compounds such as tetra-n-butyl titanate, tetraisopropyl titanate and titaniumoxyacetyl cetonate, antimony trioxide and tributoxyantimony antimony compounds, such as germanium oxide, germanium compounds, such as tetra-n-butoxy germanium, acetate salts, such as magnesium, iron, zinc, manganese, cobalt, aluminum, etc., etc. can be used. These catalysts can use 1 type or 2 or more types together.

It is preferable that it is 5000 or more, and, as for the number average molecular weight of polyester in this invention, it is more preferable that it is 10000 or more. Moreover, it is preferable that it is 100000 or less, it is more preferable that it is 50000 or less, and it is still more preferable that it is 30000 or less. If it is within the above range, handling when dissolved in a solvent is easy, adhesive strength is improved, and dielectric properties are excellent, so it is preferable.

Although the acid value of the polyester in this invention is not specifically limited, It can design suitably by the hardening|curing agent used together. In the case of isocyanate curing, it is preferably 200 eq/10 ⁶ g or less, more preferably 100 eq/10 ⁶ g or less, still more preferably 50 eq/10 ⁶ g or less, and particularly preferably 40 eq/10 ⁶ g or less. and most preferably 30 eq/10 ⁶ g or less. In the case of epoxy curing, it is preferably 20 eq/10 ⁶ g or more, more preferably 50 eq/10 ⁶ g or more, and most preferably 100 eq/10 ⁶ g or more. By adjusting the acid value of the resin to be within the above range, effects such as excellent low dielectric properties and pot life, as well as increased adhesion to substrates and crosslinking properties can be expected.

As a method of increasing the acid value of polyester in the present invention, for example, (1) a method of reacting by adding a trivalent or higher polyhydric carboxylic acid and/or a trivalent or higher polyhydric carboxylic acid after completion of the polycondensation reaction ( Acid addition), (2) In the polycondensation reaction, there are methods such as intentionally changing the quality of the resin by applying heat, oxygen, water, etc. These methods can be arbitrarily performed. The polyhydric carboxylic acid anhydride used for acid addition in the acid addition method is not particularly limited, and examples thereof include trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, and 3,3,4,4-benzo. phenonetetracarboxylic dianhydride, 3,3,4,4-biphenyltetracarboxylic dianhydride, ethylene glycol bisanhydrotrimellitate, and the like, and these may be used singly or in combination of two or more. Preferred is trimellitic anhydride.

<curing agent>

The adhesive composition of the present invention includes polyester and a curing agent. As the curing agent, an epoxy resin, polyisocyanate, polycarbodiimide or the like can be used. By crosslinking with these curing agents, the cohesive force of the resin can be increased and the heat resistance can be improved. Among them, polyisocyanate is preferable in terms of less influence on heat resistance and dielectric properties.

<Epoxy resin>

The epoxy resin used in the present invention is not particularly limited as long as it has an epoxy group in its molecule, but preferably has two or more epoxy groups in its molecule. Specifically, although not particularly limited, biphenyl type epoxy resins, naphthalene type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, novolac type epoxy resins, alicyclic epoxy resins, dicyclopentadiene type epoxy resins , tetraglycidyldiaminodiphenylmethane, triglycidylparaaminophenol, tetraglycidylbisaminomethylcyclohexanone, N,N,N',N'-tetraglycidyl-m-xylenediamine, and At least one selected from the group consisting of epoxy-modified polybutadiene may be used. Preferably, it is a biphenyl-type epoxy resin, a novolac-type epoxy resin, a dicyclopentadiene-type epoxy resin, or an epoxy-modified polybutadiene. More preferably, it is a dicyclopentadiene type epoxy resin or a novolak type epoxy resin.

In the adhesive composition of the present invention, the content of the epoxy resin is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and still more preferably 1 part by mass or more with respect to 100 parts by mass of polyester, Particularly preferably, it is 2 parts by mass or more. By setting it as more than the said lower limit, sufficient hardening effect can be acquired and excellent adhesiveness and solder|pewter heat resistance can be expressed. Further, it is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 40 parts by mass or less, and particularly preferably 35 parts by mass or less. By carrying out below the said upper limit, pot life property and a low dielectric characteristic become favorable. That is, by setting it within the above range, an adhesive composition having excellent low dielectric properties in addition to adhesiveness, solder heat resistance and pot life can be obtained.

<Polycarbodiimide>

The polycarbodiimide used in the present invention 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 polycarbodiimide, the carboxyl group and carbodiimide group of polyester react, and the interaction between the adhesive composition and the base material can be enhanced and adhesiveness can be improved.

In the adhesive composition of the present invention, the content of polycarbodiimide is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and even more preferably 1 part by mass or more with respect to 100 parts by mass of polyester. and is particularly preferably 2 parts by mass or more. By setting it to more than the said lower limit, interaction with a base material is expressed and adhesiveness becomes favorable. It is also preferably 30 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. . By using below the said upper limit, excellent pot life property and low dielectric characteristic can be expressed. That is, by setting it within the above range, an adhesive composition having excellent low dielectric properties in addition to adhesiveness, solder heat resistance and pot life can be obtained.

<Polyisocyanate>

The polyisocyanate used in the present invention is not particularly limited as long as it is an isocyanate compound that reacts with polyester to cure.

As polyisocyanate, an aromatic or aliphatic diisocyanate compound, a trivalent or higher polyisocyanate compound, etc. are mentioned. These isocyanate compounds may be any of low molecular weight compounds and high molecular weight compounds. For example, aliphatic diisocyanates such as tetramethylene diisocyanate and hexamethylene diisocyanate, aromatic diisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, Alicyclic diisocyanate, such as dimer acid diisocyanate and isophorone diisocyanate, or the trimer of these isocyanate compounds is mentioned. Further, a terminal isocyanate group containing an excessive amount of the above isocyanate compound reacted with a low molecular weight active hydrogen compound such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, and triethanolamine compounds can be mentioned. Further, compounds having a terminal isocyanate group obtained by reacting an excessive amount of the above isocyanate compound with a polymeric active hydrogen compound such as various polyester polyols, polyether polyols, and polyamides are exemplified. These isocyanate compounds may be used alone or in combination of two or more. Especially, the trimer of a hexamethylene diisocyanate compound is especially preferable.

In the adhesive composition of the present invention, the content of polyisocyanate is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and still more preferably 1 part by mass or more with respect to 100 parts by mass of polyester, Particularly preferably, it is 2 parts by mass or more. By setting it to more than the said lower limit, interaction with a base material is expressed and adhesiveness becomes favorable. It is also preferably 30 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. . By using below the said upper limit, excellent pot life property and low dielectric characteristic can be expressed. That is, by setting it within the above range, an adhesive composition having particularly excellent low dielectric properties in addition to adhesiveness, solder heat resistance and pot life can be obtained.

<Organic Solvent>

The adhesive composition of the present invention may further contain an organic solvent. The organic solvent used in the present invention is not particularly limited as long as it dissolves the polyester and the curing agent. Specifically, for example, aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as hexane, heptane, octane and decane, alicyclic hydrocarbons such as cyclohexane, cyclohexene, methylcyclohexane and ethylcyclohexane, trichloro Halogenated hydrocarbons such as ethylene, dichloroethylene, chlorobenzene, and chloroform, alcohol solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, and phenol, acetone, methyl isobutyl ketone, and methyl ethyl ketone ketone solvents such as pentanone, hexanone, cyclohexanone, isophorone and acetophenone, cellosolves such as methyl cellosolve and ethyl cellosolve, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, formic acid Ester solvents such as butyl, 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, tri Glycol ether type solvents, such as ethylene glycol mono-n-butyl ether and tetraethylene glycol mono-n-butyl ether, etc. can be used, These 1 type or 2 or more types can be used together. In particular, methylcyclohexane and toluene are preferable from the viewpoint of work environment and drying properties.

The organic solvent is preferably in the range of 100 to 1000 parts by mass with respect to 100 parts by mass of polyester. Liquid state and pot life property become favorable by setting it as more than the said lower limit. Moreover, by using below the said upper limit, it becomes advantageous in terms of manufacturing cost and transportation cost.

Moreover, you may further contain other components in the adhesive composition of this invention as needed. Specific examples of such components include flame retardants, tackifiers, fillers, and silane coupling agents.

<Flame retardant>

You may mix|blend a flame retardant with the adhesive composition of this invention as needed. Examples of the flame retardant include bromine-based, phosphorus-based, nitrogen-based, and metal hydroxide compounds. Among them, phosphorus-based flame retardants are preferable, and known phosphorus-based flame retardants such as phosphate esters such as trimethyl phosphate, triphenyl phosphate, tricresyl phosphate and the like, phosphates such as aluminum phosphinic acid and phosphazene can be used. These may be used independently, and may be used combining 2 or more types arbitrarily. In the case of containing a flame retardant, 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, and preferably in the range of 10 to 100 parts by mass, based on 100 parts by mass of the total of the polyester and the curing agent component. range is most preferred. By setting it within the said range, flame retardancy can be expressed, maintaining adhesiveness, solder heat resistance, and electrical characteristics.

<Tackifier>

You may mix|blend a tackifier with the adhesive composition of this invention as needed. Examples of the tackifier include polyterpene resins, rosin-based resins, aliphatic petroleum resins, alicyclic petroleum resins, copolymerized petroleum resins, styrene resins, hydrogenated petroleum resins, and the like, and are used for the purpose of improving adhesive strength. These may be used independently, and may be used combining 2 or more types arbitrarily. When the tackifier is contained, it 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, and preferably in the range of 10 to 100 parts by mass, based on 100 parts by mass of the total of the polyester and the curing agent component. range is most preferred. By setting it within the said range, the effect of a tackifier can be expressed, maintaining adhesiveness, solder heat resistance, and electrical characteristics.

<filler>

You may mix|blend a filler with the adhesive composition of this invention as needed. Examples of the organic filler include powders of heat-resistant resins such as polyimide and polyamideimide. In addition, as an inorganic filler, for example, 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 and the like, among which silica is preferable from the viewpoint of ease of dispersion and effect of improving heat resistance.

As silica, hydrophobic silica and hydrophilic silica are generally known, but here, hydrophobic silica treated with dimethyldichlorosilane, hexamethyldisilazane, octylsilane or the like is preferable for imparting moisture absorption resistance. In the case of blending silica, the blending amount is preferably 0.05 to 30 parts by mass based on 100 parts by mass in total of the polyester and the curing agent component. Heat resistance can be expressed further by setting it as more than the said lower limit. Moreover, by setting it below the said upper limit, the poor dispersion of silica and excessively high solution viscosity are suppressed, and workability|operativity becomes favorable.

<Silane coupling agent>

You may mix|blend a silane coupling agent with the adhesive composition of this invention as needed. Incorporation of a silane coupling agent is very preferable because the properties of adhesion to metal and heat resistance are improved. Although it does not specifically limit as a silane coupling agent, The thing which has an unsaturated group, the thing which has an epoxy group, the thing which has an amino group, etc. are mentioned. Among these, from the viewpoint of heat resistance, γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane or β-(3,4-epoxycyclohexyl)ethyltriethoxysilane A silane coupling agent having an epoxy group such as the like is more preferable. When blending the silane coupling agent, the blending amount is preferably 0.5 to 20 parts by mass based on 100 parts by mass in total of the polyester and the curing agent component. By setting it within the said range, solder heat resistance and adhesiveness can be improved.

<Laminate>

The laminate of the present invention is one in which an adhesive composition is laminated on a substrate (a two-layer laminate of substrate/adhesive layer) or a substrate further bonded (a three-layer laminate of substrate/adhesive layer/substrate). Here, the adhesive layer refers to a layer of the adhesive composition after applying the adhesive composition of the present invention to a substrate and drying it. The laminate of the present invention can be obtained by applying the adhesive composition of the present invention to various substrates according to a conventional method, drying it, and further laminating another substrate.

<Description>

In the present invention, the substrate is not particularly limited as long as it can form an adhesive layer by applying and drying the adhesive composition of the present invention, but includes resin substrates such as film-type resins, metal substrates such as metal plates and metal foils, and papers. can

Examples of the resin substrate include polyester resins, polyamide resins, polyimide resins, polyamideimide resins, liquid crystal polymers, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resins, and fluorine resins. Preferably it is a film-type resin (henceforth a base film layer).

As the metal substrate, 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, and metals treated with other metals such as alloys, plated products, zinc and chromium compounds, and the like. Preferably it is metal foil, More preferably, it is 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, still more 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. When the thickness is too thin, sufficient electrical performance of the circuit may be difficult to obtain, while when the thickness is too thick, processing efficiency and the like at the time of circuit fabrication may decrease. Metal foil is usually provided in the form of a roll. The form of the metal foil used when manufacturing the printed wiring board of this invention is not specifically limited. When using the metal foil of the form of a ribbon, the length is not specifically limited. Also, the width thereof is not particularly limited, but is preferably about 250 to 500 cm. The surface roughness of the substrate is not particularly limited, but is preferably 3 μm or less, more preferably 2 μm or less, still more preferably 1.5 μm or less. Further, for practical purposes, it is preferably 0.3 μm or more, more preferably 0.5 μm or more, and still more preferably 0.7 μm or more.

As papers, high quality paper, kraft paper, roll paper, glassine paper and the like can be exemplified. Moreover, as a composite material, glass epoxy etc. can be illustrated.

In terms of adhesion to the adhesive composition and durability, as the base material, polyester resins, polyamide resins, polyimide resins, polyamideimide resins, liquid crystal polymers, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resins, and fluorine-based resins are used. Resin, SUS steel plate, copper foil, aluminum foil, or glass epoxy is preferable.

<Adhesive Sheet>

In the present invention, the adhesive sheet is obtained by laminating the laminate and the release substrate through an adhesive composition. As a specific structural aspect, a laminate/adhesive layer/release base material or a release base material/adhesive layer/laminate/adhesive layer/release base material is exemplified. 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 further transferred to another substrate.

The adhesive sheet of the present invention can be obtained by applying the adhesive composition of the present invention to various laminates according to a conventional method and drying them. In addition, when the release substrate is adhered to the adhesive layer after drying, it is possible to roll the substrate without getting stuck on the back side of the substrate, resulting in excellent workability, and excellent preservation and ease of use because the adhesive layer is protected. In addition, if another release substrate is adhered as needed after application and drying to the release substrate, the adhesive layer itself can be transferred to another substrate.

<Release description>

The release substrate is not particularly limited, but for example, a coating layer of a filler such as clay, polyethylene, or polypropylene is formed on both sides of paper such as high-quality paper, kraft paper, roll paper, and glassine paper, and each application layer On top of that, a silicone-based, fluorine-based, or alkyd-based mold release agent may be further applied. In addition, various olefin films such as polyethylene, polypropylene, ethylene-α-olefin copolymers and propylene-α-olefin copolymers, and those obtained by applying the release agent on films such as polyethylene terephthalate may also be mentioned. For reasons such as the release force of the release substrate and the adhesive layer, and silicone adversely affecting the electrical properties, polypropylene filler is treated on both sides of high-quality paper and an alkyd release agent is used on it, or an alkyd release agent is applied on polyethylene terephthalate. It is preferable to use

On the other hand, in the present invention, the method for coating the adhesive composition on the substrate is not particularly limited, but a comma coater, a reverse roll coater, and the like are exemplified. Alternatively, an adhesive layer may be formed directly or by a transfer method on a rolled copper foil or polyimide film as a constituent material of a printed wiring board, if necessary. The thickness of the adhesive layer after drying is appropriately changed as needed, but is preferably in the range of 5 to 200 µm. Sufficient adhesive strength is obtained by setting the adhesive film thickness to 5 µm or more. Moreover, by setting it as 200 micrometers or less, it becomes easy to control the amount of residual solvent in a drying process, and it becomes difficult to generate|occur|produce blistering at the time of pressing in printed wiring board manufacture. Drying conditions are not particularly limited, but the residual solvent rate after drying is preferably 1% by mass or less. By setting it as 1 mass % or less, it suppresses foaming of the residual solvent at the time of printed wiring board press, and it becomes difficult to produce blistering.

<Printed Wiring Board>

The printed wiring board in the present invention includes, as constituent elements, a laminate formed of a metal foil and a resin substrate forming a conductor circuit. A printed wiring board is manufactured by a conventionally known method, such as a subtractive method, using, for example, a metal-clad laminate. If necessary, a so-called flexible circuit board (FPC), flat cable, circuit board for tape automated bonding (TAB), etc., in which a conductor circuit formed of metal foil is partially or entirely covered with a cover film or screen printing ink, etc. are collectively

The printed wiring board of the present invention can have any laminated structure that can be employed as a printed wiring board. For example, it can be set as a printed wiring board comprised from 4 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 composed of five layers of a base film layer, an adhesive layer, a metal foil layer, an adhesive layer, and a cover film layer can be obtained.

Moreover, it can also be set as the structure which laminated|stacked 2 or 3 or more said printed wiring boards as needed.

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 to low-polarity resin substrates such as LCP as well as conventional polyimide, polyester film, and copper foil constituting printed wiring boards, and has 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 a coverlay film, a laminated board, a copper foil with resin, and a bonding sheet.

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

<Cover film>

As a cover film, any conventionally well-known insulating film can be used as an insulating film for printed wiring boards. For example, 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. A film made of may be used. More preferably, it is a polyimide film or a liquid crystal polymer film.

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

In a preferred embodiment, a semifinished product in which an adhesive layer is laminated on a cover film layer (hereinafter referred to as "cover film side semifinished 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 a "sub-film side two-layer semi-finished product") or an adhesive layer is laminated on the base film layer, and a metal foil layer is laminated thereon. A semi-finished product having a desired circuit pattern (hereinafter referred to as "base film side 3-layer semi-finished product") is manufactured (hereinafter, the base film-side 2-layer semi-finished product and the base film side 3-layer semi-finished product are collectively referred to as "base film side semi-finished product"). ). A 4-layer or 5-layer printed wiring board can be obtained by bonding the cover film-side half-finished product obtained in this way and the base film-side half-finished product together.

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

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

The obtained base film side semifinished product may be used for bonding with the cover film side semifinished product as it is, or may be used for bonding with the cover film side semifinished product after bonding and storing a release film.

The semifinished product on the side of the cover film is manufactured by, for example, applying an adhesive to the 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 semifinished product may be used as it is for bonding with the base film side semifinished product, or may be used for bonding with the base film side semifinished product after bonding and storing a release film.

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

In the case of a reinforcing material-side semi-finished product, for example, in the case of a softly rollable reinforcing material such as a polyimide film, it is preferable to manufacture the reinforcing material by applying an adhesive. Further, for example, in the case of a reinforcing plate that is hard and cannot be wound, such as a metal plate such as SUS or aluminum, or a plate made by curing glass fibers with an epoxy resin, it is preferable to manufacture by transfer coating an adhesive previously applied to a release substrate. In addition, a crosslinking reaction in the applied adhesive can be performed as needed. In a preferred embodiment, the adhesive layer is semi-cured.

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

The half-finished product on the base film side, the half-finished product on the cover film side, and the half-finished product on the reinforcing material side are all laminated bodies for printed wiring boards in the present invention.

Example

Hereinafter, the present invention will be described in detail by way of examples. On the other hand, in this Example and Comparative Example, "part" simply indicates a mass part.

(physical property evaluation method)

Measurement of composition of polyester

Using a 400 MHz ¹ H nuclear magnetic resonance spectrometer (hereinafter sometimes abbreviated as NMR), the molar ratio of the polyhydric carboxylic acid component and polyhydric alcohol component constituting the polyester was quantified. Deuterated chloroform was used as the solvent. On the other hand, when the acid value of the polyester was increased by post acid addition, the molar ratio of each component was calculated by taking the total of acid components other than the acid component used for post acid addition as 100 mol%.

Measurement of glass transition temperature

It was measured using a differential scanning calorimeter (SII, DSC-200). 5 mg of the sample (polyester) was placed in an aluminum press-lid container, sealed, and cooled to -50°C using liquid nitrogen. Subsequently, the temperature was raised to 150 ° C. at a temperature increase rate of 20 ° C./min, and in the endothermic curve obtained during the temperature increase process, the extension line of the baseline before the endothermic peak appeared (below the glass transition temperature) and the tangent line toward the endothermic peak (peak The temperature at the intersection of the tangent line representing the maximum slope between the rising part of and the peak of the peak) was taken as the glass transition temperature (Tg, unit: ° C).

Measurement of number average molecular weight

A polyester sample was dissolved and/or diluted with tetrahydrofuran to a resin concentration of about 0.5% by weight, and filtered through a polytetrafluoroethylene membrane filter with a pore diameter of 0.5 µm to obtain a sample for measurement. Molecular weight was measured by gel permeation chromatography (GPC) using tetrahydrofuran as a mobile phase and using a differential refractometer as a detector. The flow rate was 1 mL/min, and the column temperature was 30°C. KF-802, 804L, and 806L manufactured by Showa Denko were used for the column. Monodisperse polystyrene was used for molecular weight standards.

acid value measurement

A polyester sample of 0.2 g was dissolved in 40 ml of chloroform and titrated with a 0.01 N potassium hydroxide ethanol solution to obtain an equivalent weight per 10 ⁶ g of polyester (eq/10 ⁶ g). Phenolphthalein was used as the indicator.

Hereinafter, synthetic examples of the polyester used in the present invention are shown.

Synthesis example of polyester (a1)

In a reaction vessel equipped with a stirrer, condenser, and thermometer, 326 parts of 2,6-naphthalenedicarboxylic acid dimethyl, 1520 parts of dimer diol (Croda Co., Pripol 2033), and tetrabutyl orthotitanate as a catalyst were added at 0.03 mol% based on the total acid components. Then, an esterification reaction was performed while passing through a temperature rising and dehydration process from 160°C to 220°C over 4 hours. Next, in the polycondensation reaction step, the pressure inside the system was reduced to 5 mmHg over 20 minutes, and the temperature was further raised to 250°C. Then, after reducing the pressure to 0.3 mmHg or less and performing a polycondensation reaction for 60 minutes, this was taken out. As a result of compositional analysis by NMR, the obtained polyester (a1) was 2,6-naphthalenedicarboxylic acid/dimerdiol = 100/100 [molar ratio] in terms of molar ratio. Moreover, the glass transition temperature was -17 degreeC. The results are listed in Table 1.

Synthesis Examples of Polyesters (a2) to (a15)

Polyesters (a2) to (a15) were synthesized according to the production example of polyester (a1) by changing the type of raw materials and the blending ratio. On the other hand, polyester (a9) was added after polymerization by further adding 8 parts by mass of trimellitic anhydride and reacting at 230°C for 30 minutes to carry out post acid addition. The results are listed in Table 1. On the other hand, PTMG1000 is polytetramethylene ether glycol (average molecular weight 1000).

(Evaluation of adhesive composition)

Relative permittivity (ε _c ) 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 was 25 μm, and dried at 130° C. for 3 minutes. Subsequently, after hardening by heat treatment at 170°C for 3 hours, the Teflon (registered trademark) sheet was peeled off to obtain an adhesive resin sheet for testing. After that, a sample was cut into a rectangle of 8 cm x 3 mm from the obtained adhesive resin sheet for testing to obtain a sample for testing. The dielectric constant (ε _c ) and the dielectric loss tangent (tan δ) were measured using a network analyzer (manufactured by Anritz Corporation) by a cavity resonator perturbation method under conditions of a temperature of 23°C and a frequency of 10 GHz.

<Evaluation Criteria for Relative Permittivity>

◎: 2.3 or less

○: more than 2.3 and less than 3.0

×: greater than 3.0

<Evaluation Criteria for Dielectric Loss Tangent>

◎: 0.005 or less

○: More than 0.005 and 0.008 or less

×: greater than 0.008

solvent solubility

Solvent solubility was evaluated with a toluene varnish of polyester before addition of a curing agent. The solubility when the polyester was dissolved in toluene with stirring at 80°C for 6 hours so as to have a solid content concentration of 60% by mass, 50% by mass, or 30% by mass was evaluated according to the following criteria.

<Evaluation Criteria for Solvent Solubility>

◎: Completely dissolved without dissolution residue at a solid content concentration of 60% by mass

○: Completely dissolved without dissolution residue at a solid content concentration of 50% by mass

△: Completely dissolved without dissolution residue at a solid content concentration of 30% by mass

×: Residual dissolution of resin at a solid content concentration of 30% by mass

Peel strength (adhesiveness)

The adhesive composition was applied to a polyimide film (manufactured by Kaneka Corporation, Apical (registered trademark)) having a thickness of 12.5 μm so that the thickness after drying was 25 μm, and dried at 130° C. for 3 minutes. The adhesive film (B stage product) obtained in this way was bonded to a rolled copper foil (manufactured by JX Metal Co., Ltd., BHY series) having a thickness of 18 µm. For joining, the glossy surface of the rolled copper foil was brought into contact with the adhesive layer, and it was bonded by pressing at 160°C under a pressure of 2 MPa for 30 seconds. Subsequently, it was hardened by heat treatment at 170°C for 3 hours, and a sample for evaluation of peel strength was obtained. The peel strength was measured by pulling the film at 25°C and conducting a 90° peel test at a tensile speed of 50 mm/min. This test shows the adhesive strength at room temperature.

<Evaluation Criteria>

◎: 1.0 N/mm or more

○: 0.8 N/mm or more and less than 1.0 N/mm

△: 0.5 N/mm or more and less than 0.8 N/mm

×: less than 0.5 N/mm

heat resistance

The adhesive composition was applied to a Teflon (registered trademark) sheet having a thickness of 100 μm so that the thickness after drying was 25 μm, and dried at 130° C. for 3 minutes. Subsequently, after hardening by heat treatment at 170°C for 3 hours, the Teflon (registered trademark) sheet was peeled off to obtain an adhesive resin sheet for testing.

It was measured using a differential thermal/thermogravimetric simultaneous measuring device (Shimadzu Corporation, DTG-60). 50 mg of the adhesive resin sheet was placed in a platinum cell, and the temperature was raised to 1000°C at a heating rate of 5°C/min under a nitrogen atmosphere at a flow rate of 20 ml/min. The temperature at which decomposition at high temperature progresses and the weight becomes 95% of the initial value was set as the 5% weight loss temperature, and was used as an index of heat resistance.

<Evaluation criteria for heat resistance>

○: 5% weight loss temperature is 300 ° C. or higher

×: 5% weight loss temperature is less than 300°C

Hereinafter, production examples of adhesive compositions used as examples of the present invention and adhesive compositions used as comparative examples are shown.

As the curing agent, the following were used.

(b1): Polyisocyanate (Smijul N3300 (manufactured by Sumica Covestro Urethane Co.))

(b2): Epoxy resin (Epiclon HP-7200H (manufactured by DIC))

(Example 1)

Polyester (a1) obtained in the above Synthesis Example was dissolved in toluene to prepare a toluene varnish having a solid content concentration of 30% by mass. To this toluene varnish, the curing agent (b1) was blended in an amount of 2 parts per 100 parts of the polyester (a1) to obtain an adhesive composition (A1).

Regarding the obtained adhesive composition (A1), each evaluation of solvent solubility, dielectric constant, dielectric loss tangent, heat resistance, and peeling strength was performed. The results are listed in Table 2.

(Examples 2 to 12, Comparative Examples 1 to 5)

Adhesive compositions (A2) to (A17) were prepared in the same manner as in Example 1, except that the type of polyester and the type and compounding amount of the curing agent were changed as shown in Table 2, and each evaluation was performed. The results are listed in Table 2.

The adhesive composition of the present invention is excellent in solvent solubility and has a low dielectric constant and dielectric loss tangent, and is useful as an adhesive for FPCs in a high frequency region.

Claims (6)

An adhesive composition containing polyester and a curing agent, wherein the polyester has a polyhydric carboxylic acid component and a polyhydric alcohol component as structural units, and when the polyhydric carboxylic acid component is 100 mol%, a naphthalenedicarboxylic acid component 50 mol% or more, and as a polyhydric alcohol component, an adhesive composition containing at least one of a dimer diol component and a tricyclodecane dimethanol component. The adhesive composition according to claim 1, wherein the polyester has a glass transition temperature of -30°C or higher. The adhesive composition according to claim 1 or 2, wherein the relative permittivity (εc) at 10 GHz is 3.0 or less and the dielectric loss tangent (tan δ) is 0.008 or less. An adhesive sheet having a layer formed of the adhesive composition according to any one of claims 1 to 3. A laminate having a layer formed of the adhesive composition according to any one of claims 1 to 3. A printed wiring board comprising the laminate according to claim 5 as a component.