KR100841239B1 - Adhesive composition for multi-layered fpcb and manufacturing method by using it - Google Patents

Abstract

An adhesive composition for the interlayer insulation adhesive film of a multilayered flexible printed circuit board(FPCB), and a method for preparing the multilayered flexible printed circuit board by using the composition are provided to improve fast curing property, film management and storage stability remarkably. An adhesive composition for a multilayered flexible printed circuit board comprises a thermoplastic binder resin; a thermosetting resin; a curing agent; a radical polymerizable compound; a radical initiator; and an additive, wherein the adhesive strength is such that a peel strength is 1.3-1.8 kgf/cm^2 at a velocity of 50 mm/min of a copper foil and a curing specimen, and the bubble generation area is 1-10 % of the total area of the curing specimen when the curing specimen is dipped in a lead bath (260±5 deg.C, 30±5 sec).

Description

Adhesive composition for multilayer flexible printed circuit boards and method of manufacturing multilayer flexible printed circuit boards using the same {Adhesive Composition for Multi-layered FPCB and Manufacturing Method by using it}

1 is a photograph for explaining the concept of a hot pressing method for manufacturing a multilayer flexible printed circuit board according to the present invention.

Figure 2 is a step-by-step photograph of the hot pressing method at high temperature and high pressure conditions in accordance with the present invention.

Figure 3 is a step-by-step photograph of the hot pressing method at high temperature, high pressure and vacuum conditions according to the present invention.

Figure 4 is a step-by-step photo of the hot pressing method using induction heating according to the present invention.

The present invention relates to an interlayer insulating adhesive composition used in the manufacture of a multi-layered flexible printed circuit board and a method of manufacturing a multi-layer flexible printed circuit board using the same.

In more detail, by providing a thermosetting interlayer insulating adhesive composition capable of rapid curing at a high temperature while maintaining excellent heat resistance, adhesion and chemical resistance, the production cost is increased by increasing the production efficiency compared to the conventional method produced by a long time at high temperature. It relates to a method for manufacturing a multilayer flexible printed circuit board that can significantly reduce the cost.

Today, as the integration and miniaturization of semiconductor chips or chip components are rapidly progressing, the trend of high density mounting of electronic devices equipped with these components is rapidly progressing, especially in view of the substrate materials in which these components are mounted. As flexible wiring materials are advantageous for miniaturization, light weight, and thinness due to the inclusion of more design freedom than conventional rigid substrates, flexible printed circuit board applications have been widely used. Is also getting stronger.

Conventionally, although an acrylonitrile butadiene rubber / epoxy resin system, an acrylic rubber / epoxy resin system, an acrylonitrile butadiene rubber / phenol resin system, polyester / isocyanate system, polyamide resin system, etc. have been used as an interlayer adhesive conventionally, an interlayer insulation layer Manufacture of 4 layers or more multilayer flexible printed circuit boards because high temperature long time hot pressing process is required for at least 160 ℃ x 60 minutes or 180 ℃ x 30 minutes At the time of the adhesive curing process at least 3-4 hours or more had a problem of very low productivity. The adhesive film which can be cured in a short time and on the other hand, not only satisfies the adhesive property, the soldering heat resistance, etc. as the wiring board material, but also harmonizes the opposite characteristics such as the excellent storage stability, and the multilayer flexible printed circuit board manufacturing device using the same There is a greater demand for normal productivity gains.

Accordingly, the present inventors provide an adhesive composition for a multilayer flexible printed circuit board which is excellent in heat resistance, adhesiveness, chemical resistance, and also in terms of storage stability at room temperature even when cured for a short time in order to improve these problems. The present invention aims to provide a method for manufacturing a multilayer flexible printed circuit board that can dramatically reduce the manufacturing cost by shortening an excessive process time due to multilayer manufacturing by using at the time of lamination.

As a result of repeated studies to achieve the above object, the present inventors have been able to achieve the above object by manufacturing an adhesive film as an adhesive composition as described below and using it as an interlayer insulating layer of a multilayer flexible printed circuit board. The present invention has been completed.

That is, the adhesive composition according to the present invention can improve productivity while maintaining high temperature heat resistance, adhesiveness, and chemical resistance by appropriately mixing a radical curing component that can be cured for a short time with a thermosetting resin component that has been used conventionally so that heat curing can be performed within a short time. Fast curing properties were also realized at the same time, more specifically, the adhesive composition consisting of (A) thermoplastic binder resin (B) thermosetting resin and curing agent (C) radically polymerizable compound, (D) radical initiator (E) additive, etc. As it was manufactured and used as an interlayer adhesive layer in the manufacture of a multi-layer flexible printed circuit board, even a short curing time of 180 ° C. × 10 minutes could satisfy all the physical properties that a flexible printed circuit board should have.

Hereinafter will be described in more detail for each component of the present invention.

In the composition of the present invention, the (A) thermoplastic binder resin gives a mutual bonding force so that each adhesive component can have a film shape in a uniformly mixed state before curing, so that the adhesive film is not easily torn and is cracked or sticky. Without this, it should have the property of imparting mechanical properties to be handled as a film in a normal state, and after curing, the brittleness of the adhesive layer is improved by uniformly dispersing thermal and mechanical stresses applied from the outside into the adhesive layer. It shows a function to make.

The binder resin component is not particularly limited as long as it has thermoplastic properties, but examples thereof include acrylic acid copolymer, polystyrene, polyimide, polyetherimide, polyamide, polyurethane, polyphenylene ether resin, and the like. Acrylic acid copolymers, polyester resins, polyimide resins, and the like are preferable in terms of dispersibility and organic solvent solubility with thermosetting resins and radically polymerizable compounds. These resins may be used alone or in combination of two or more thereof.

Examples of the acrylic acid copolymer that can be used in the present invention include copolymers containing at least one of acrylic acid, acrylic acid esters, methacrylic acid esters, and acrylonitrile as monomer components, and particularly for improving heat resistance after curing of the adhesive. It is more preferable that the structure containing a functional group in the side chain to enable the curing reaction with the epoxy resin. As the functional group addition-type acrylic monomer, glycidyl methacrylate having a glycidyl ether group, hydroxy methacrylate having a hydroxyl group, a carboxyl group Copolymers containing carboxymethyl acrylate and the like are preferred. In addition, in order to improve the film properties and heat resistance of the adhesive composition, the appropriate weight average molecular weight of the acrylic acid copolymer is preferably 10,000 to 1,000,000, more preferably 50,000 to 800,000.

The polyester resin which can be used in the present invention is prepared by esterification from divalent or higher carbonyl acid and divalent or higher glycol component, and is not particularly limited as long as it has good compatibility with thermosetting resin.

Examples of the carbonyl acid component in the polyester resin composition include terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalic acid, 2,6-naphthalic acid, 4,4'-diphenyldicarboxylic acid, and the like. Aromatic dibasic acids, such as 2, 2- diphenyl dicarboxylic acid and a 4, 4- di- diphenyl ether dicarboxylic acid, adipic acid, azeline acid, sebacic acid, 1, 4- cyclohexane dicarboxylic acid, 1, 3- Aliphatic and alicyclic dibasic acids, such as cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dimer acid, etc. are suitable.

As the glycol component, ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5 -Pentanediol, 1,6- hexanediol, 3-methyl-1,5-pentanediol, neopentylglycol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, between Clodimethanol, neopentylhydroxy pivalinic acid ester, ethylene oxide adduct and propylene oxide adduct of bisphenol A, ethylene oxide adduct and propylene oxide adduct of hydrogenated bisphenol A, 1,9-nonanediol, 2-methyloctanediol , 1,10-dodecanediol, 2-butyl-2-ethyl-1,3-propanediol, tricyclodecanedimethanol and the like, and polyether glycols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol It is also good to use ingredients, etc. It may be in addition to the functional group to enable the crosslinking reaction of the resin with the addition of a functional group addition type component in its side chain for the purpose of improving heat resistance.

As such side-chain functional group carbonic acid component, for example, benzophenone tetracarboxylic dianhydride, trimellitic anhydride, pyromellitic anhydride, ethylene glycol bishydrohydro trimellitate, glycerol tris-anhydro trimellitate, and the like are added. You may also do it.

The proper weight average molecular weight of the polyester resin is preferably used in the range of 5,000 to 200,000, more preferably 10,000 to 100,000 in terms of the adhesive properties and heat resistance as the adhesive layer between the flexible printed circuit board.

Polyimide resins that can be used in the present invention are based on its excellent heat resistance and moisture resistance, and thus the application trend of conventional semiconductor package substrate circuits or substrate substrates for circuit boards having high glass transition temperature (Hi-T _g ) has been increased. Recently, a hybrid adhesive mixed with a thermosetting resin has been developed that can be applied only to high temperature attachment of 250 ° C. or higher, and is applicable to a medium temperature attachment process of 150 ° C. or lower, and in particular, polyimide resin. Unlike other polymer resins, it is preferable to control the glass transition temperature of the final polymer by appropriately selecting the polymerization raw material.

The polyimide resin that can be used in the present invention is not particularly limited as long as it has a form having an imide bond in the side chain or the main chain, but preferably has a weight average molecular weight of 5,000 to 500,000 or less, more preferably 10,000 to 50,000. Is appropriate.

The above polyimide resin may have a thermoplastic polyimide resin which does not have a reactive functional group and a functional group capable of reacting with the thermosetting resin by heating, such as a carboxyl group or a hardoxyl group, on the side chain. An oligomeric polyimide resin can be obtained by synthesizing a polyamic acid precursor from a mixture with an aromatic tetracarboxylic dianhydride and dehydrating it by heating it again.

As the acid dianhydride monomer used for the polymerization of the thermoplastic polyimide resin which can be used in the present invention, for example, 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride, 3,3', 4,4 ' -Benzophenone tetracarboxylic acid dianhydride, 4,4'- oxydiphthalic acid dianhydride, 3,3 ', 4,4'- diphenyl horn tetracarboxylic acid dianhydride, 2, 2', 3, 3'-rain Phenyltetracarboxylic acid dianhydride, ethylene glycol screw trimellitic acid dianhydride, 2, 2 ', 3, 3'- benzophenone tetracarboxylic acid dianhydride, 4, 4'- bisphenol A2 anhydride, pyromellitic anhydride, 2 , 3,6,7-naphthalene tetracarboxylic dianhydride, 1,4,5,7-naphthalene tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 1,2- (ethylene ) (Bis) trimellitate acid anhydride, 1,3- (trimethylene) bis (trimerate acid anhydride), and the like. It is also possible to use these individually or in mixture of 2 or more types.

Moreover, as aliphatic or aromatic diamine which reacts with said acid dianhydride, methylenediamine, ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenedidiamine, octamethylenediamine, 2, 4- diaminotoluene, m-xylenediamine, p-xylenediamine, m-phenylenediamine, p-phenylenediamine, 2,6-diaminopyridine, 2,5-ziaminopyridine, 1,4-diaminocyclohexane, Piperazine, 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 4,4'- diamino diphenyl propane, 3,3'- diamino diphenyl ethane, 4 , 4'- diamino diphenylmethane, 3,3'- diamino diphenylmethane, 4,4'- diamino diphenylsulfone, 3,3'- diamino diphenylsulfone, 4,4'-diamino Diphenyl ether, 3,3'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 1,3-bis (3-aminophenoxy) benzene, 2,2-bis -4 -(4-aminophenoxy) phenyl propane, 1,3-bis (4-aminophenoxy) benzene, bis-4- (4-aminophenoxy) phenylsulfone, bis-4- (3-aminophenoxy) Phenyl sulfone, p-bis (2-methyl- 4-aminopentyl) benzene, etc. are mentioned.

Said aliphatic and aromatic diamine may be used individually or in combination of 2 or more types.

Moreover, it is more preferable to use diamino polysiloxane as one of the diamine components of the said polyimide resin. Examples of the diamino polysiloxanes include 1,3-bis (3-aminopropyl) tetramethylsiloxane, α, ω-bis (3-aminopropyl) polydimethylsiloxane, and 1,3-bis (4-aminophenyl) tetra Methylsiloxane, α, ω-bis (4-aminophenyl) polydimethylsiloxane, 1,3-bis (3-aminophenyl) tetramethylsiloxane, α, ω-bis (3-aminophenyl) polydimethylsiloxane, 1, 3-bis (3-aminopropyl) tetraphenylsiloxane, α, ω-bis (3-aminopropyl) polydiphenylsiloxane, and the like, may be used alone or in combination of two or more thereof. It is preferable to use within 5-50 mol% of the total amount of a diamine component.

The optimal amount of the thermoplastic binder resin as described above is preferably mixed at 20 to 80 parts by weight based on 100 parts by weight of the adhesive composition, and more preferably 30 to 60 parts by weight. If the amount is less than 20 parts by weight, the brittleness of the adhesive film becomes stronger and the handling becomes worse. On the contrary, when the amount is more than 80 parts by weight, the degree of curing of the adhesive layer decreases, resulting in insufficient high temperature heat resistance and chemical resistance.

In the (B) thermosetting resin and the curing agent of the composition of the present invention, the thermosetting resin is not cured by an organic radical, but has a three-dimensional network structure as it heats and may have a property of firmly adhering to the adherend and heat resistance. There is no restriction | limiting in particular if there is resin present.

Examples thereof include epoxy resins, unsaturated polyester resins, thermosetting acrylic resins, phenol resins, diaryl phthalate resins, polyurethane resins, and the like. These thermosetting resins can be used alone or in combination of two or more. In particular, they have relatively low melt viscosity before curing, which makes them easy to apply to the attaching process. Epoxy resin can be used very suitably in that it is.

As such epoxy resins, various conventionally known epoxy resins may be used, but in general, those having a molecular weight of about 300 to 5000 are preferable, and solid epoxy resins having a molecular weight of 500 to 2000 that are easy to control adhesive surface stickiness. It is preferable to use, for example, bisphenol A type, bisphenol F type, bisphenol S type, cancelled bisphenol A type, hydrogenated bisphenol A type, bisphenol AF type, biphenyl type, naphtharene type, florene type, phenol no. Although bifunctional or polyfunctional epoxy resins such as a rock type, a cresol novolak type, a tris hydroxyl phenylmethane type, and a tetraphenylmethane type can be used, bisphenol A is relatively excellent in physical properties such as curability, adhesiveness, heat resistance, and moisture resistance. Type, cresol novolak-type, and phenol novolak-type epoxy resins are preferable, and these may be used alone or in combination of two or more thereof.

The curing agent added to such an epoxy resin can be used without particular limitation as long as it is a compound having at least one activated hydrogen in a molecule as a component that promotes a curing reaction. It is preferable to use a curing agent, and examples thereof include imidazole-based, polyisocyanate-based, amine-based, amide-based, acid-anhydride-based, or phenol-based curing agents. One of these may be used alone or two or more may be used. Although it may mix and use, it is preferable to use a phenolic hardening | curing agent from the point which is excellent in the high temperature heat resistance and latent property of hardened | cured material. For example, phenol novolak resins, cresol novolak resins, bisphenol A novolak resins, phenol aralkyl resins, poly-p-vinylphenol t-butylphenol novolak resins, naphthol novolak resins and the like may be appropriately used.

As described above, when the epoxy resin and the phenol-based curing agent are used as the thermosetting resin and the curing agent, the optimal total blending amount is preferably mixed at 10 to 40 parts by weight based on 100 parts by weight of the adhesive composition. If the total amount of the thermosetting resin and the curing agent is less than 10 parts by weight, the curing rate of the adhesive layer is lowered, so that the surface stickiness of the adhesive film is increased, resulting in poor handling. On the contrary, when more than 40 parts by weight, the brittleness of the adhesive film becomes stronger. In addition, while the storage stability at room temperature is inferior, the high temperature short time hardening properties can not be effectively implemented.

In addition, the proper amount of the epoxy resin and the phenol-based curing agent is appropriately adjusted in an equivalent ratio to obtain optimum physical properties, but it is preferable to adjust the blending amount so that the OH equivalent ratio of the phenol resin added per mole of epoxy reactor is within 0.8 to 1.2. If out of the blending ratio, the unreacted resin portion in the epoxy resin or the phenol resin increases, and crosslinking degree decreases after curing, and thus sufficient heat resistance cannot be obtained.

The radically polymerizable compound (C) in the composition of the present invention is an acrylate, methacrylate, maleimide compound having excellent heat resistance, and the like, as a compound having an unsaturated functional group capable of undergoing polymerization by free radicals generated upon heating. These may be used alone or in combination of two or more thereof. These radically polymerizable compounds may be used in any of monomers and oligomers, and monomers and oligomers may be appropriately used in combination.

Examples of acrylate monomers suitable for the present invention include methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, trimetholpropane triacrylate, and tetrameth. Tyrol methane tetraacrylate, or bisphenol A and phenol noblock epoxy resin modified acrylate, and the like, and among them, it is preferable to use an epoxy resin modified acrylate in view of obtaining excellent physical properties in terms of adhesion and heat resistance after curing.

Examples of the acrylate oligomer resins include polyester modified acrylates, isocyanurate ethylene oxide modified acrylates, urethane modified acrylates, and the like, and methacrylate modified compounds corresponding to acrylates are also suitable for the present invention. In the present invention, among the various acrylate oligomer compounds as described above, urethane-modified acrylates having excellent physical properties in terms of flexibility, chemical resistance and adhesive strength are particularly suitable. The urethane-modified acrylate has at least one urethane group in the molecule, and examples thereof include a reaction product of a polyol such as polytetramethylene glycol and a polyisocyanate and hydroxyl group-containing acrylic compound.

Moreover, it is preferable to use together the compound of a phosphate ester structure from the point which can improve the adhesive strength on the surface of metal inorganic materials, such as copper foil.

As a phosphate ester structure compound, the reactant of 2-hydroxyethyl methacrylate which is phosphoric anhydride and 2-hydroxyethyl acrylate or the corresponding methacrylate is mentioned.

In order to use the adhesive composition of the present invention for flexible printed circuit board use, high temperature heat resistance of 260 ° C. or higher is essential. In order to improve the heat resistance, a mixture of maleimide compounds is preferably used. Particularly, at least two maleimide groups are contained in a molecule. It is more suitable to use the polyfunctional maleimide compound to improve the heat resistance according to the increase in the crosslinking density after curing of the adhesive. Examples of such maleimide compounds include 1-methyl-2,4-bismaleimidebenzene, N, N'-m-phenylenebismaleimide, N, N'-p-phenylenebismaleimide, N, N '-m-toluylenebismaleimide, N, N'-4,4-biphenylenebismaleimide, N, N'-4,4- (3,3'-dimethylbiphenylene) bismaleimide, N, N'-4,4- (3,3'-dimethyldiphenylmethane) bismaleimide, N, N'-4,4- (3,3'-diethyldiphenylmethane) bismaleimide, N , N'-4,4-diphenylmethanebismaleimide, N, N'-4,4-diphenylpropanebismaleimide, N, N'-4,4-diphenyletherbismaleimide, N, N '-3,3'-diphenylsulfonbismaleimide, 2,2-bis (4- (4-maleimidephenoxy) phenyl) propane, 2,2-bis (3-s-butyl-3,4 -(4-maleimidephenoxy) phenyl) propane, 1,1-bis (4- (4-maleimidephenoxy) phenyl) decane, 4,4'-cyclohexylidene-bis (1- (4- Maleimidephenoxy) -2-cyclohexylbenzene, 2,2-bis (4- (4-maleimidephenoxy) phenyl) hexafluoropropane Etc. can be mentioned.

The optimal blending amount of the radically polymerizable compound as described above is preferably mixed at 10 to 40 parts by weight based on 100 parts by weight of the adhesive composition. If the compounding amount of these compounds is less than 10 parts by weight, as the amount of fast curable components in the composition is relatively small, the fast curing property of less than 10 minutes at 180 ° C., which is the object of the present invention, cannot be achieved. When incorporated, the amount of low-molecular oligomer in the composition becomes relatively large, which increases the surface stickiness of the adhesive film and decreases the handleability, and it is not preferable in that it causes an excessive flow of the adhesive component during the hot pressing process.

The radical initiator (D) used in the present invention may be used without particular limitation as long as it is a compound capable of generating radicals by heating, and may be appropriately selected in consideration of properties such as target curing temperature, curing time and storage stability. However, in order to properly realize the required characteristics of both fast curing and long-term storage stability, an organic peroxide having a characteristic of a half-life of 10 hours or more and a temperature of 1 minute of half-life of 190 or less is preferable, and more preferably. For example, it is preferable to apply an organic peroxide having a temperature of 10 hours for a half life of 70 ° C. or more and a temperature of 1 minute for half life of 180 ° C. or less.

Suitable organic peroxides as the radical initiator of the present invention include diacyl peroxide, peroxydicarbonate, peroxy ester, dialkyl peroxide, hydroperoxide, and the like, of which diacyl peroxides are preferably used.

Examples of the diacyl peroxides include isobutyl peroxide, lauroyl peroxide, stearoyl peroxide, succinic peroxide, benzoyl peroxy toluene, and benzoyl peroxide.

As peroxydicarbonates, di-n-propylperoxydicarbonate, diisopropylperoxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethylperoxydicarbonate, di ( 2-ethylhexyl peroxy) dicarbonate, dimethoxybutyl peroxy dicarbonate, etc. are mentioned.

As peroxy ester, cumyl peroxy neodecanoate, 1-cyclohexyl-1-methylethyl peroxy neodecanoate, t-hexyl peroxy neodecanoate, t-butylperoxy pivalate, 2,5 -Dimethyl-2,5-di (m-toluoylperoxy) hexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexyl peroxybenzoate, t -Butyl peroxy acetate, etc. are mentioned.

Examples of the dialkyl peroxides include α, α'-bis (t-butylperoxy) diisopropylbenzene, dicumylperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t -Butyl cumyl peroxyside, etc. are mentioned.

Diisopropyl benzene hydroperoxide, cumene hydroperoxide, etc. are mentioned as hydroperoxides.

In order to obtain sufficient hardening reaction rate on the adhesive agent of this invention on 180 degreeC and the conditions within 10 minutes in a high temperature hot-pressing process, it is preferable to make the compounding quantity of a radical initiator into 0.5-10 weight part, and 1-5 weight part is more preferable. If the blending amount of the radical initiator is less than 0.5 parts by weight, sufficient curing reaction rate cannot be obtained, resulting in insufficient heat resistance of the adhesive. On the other hand, if the blending amount is more than 10 parts by weight, the fluidity of the adhesive layer decreases or the storage stability is rapidly shortened.

As the (E) additive in the adhesive composition of the present invention, an organic material or an inorganic material may be added as necessary. Examples of the organic material include silane coupling agents, titanium coupling agents, surface conditioners, antioxidants, and tackifiers. As the inorganic material, inorganic particles such as alumina, silica, aluminum hydroxide, magnesium hydroxide, calcium carbonate and the like are effective in terms of adhesive film surface adhesion and cutting properties, and the addition ratio of these inorganic materials is not particularly limited, but the weight of the entire adhesive composition is increased. In view of 100 it is preferred to add less than 30 parts by weight. If the added amount exceeds 30 parts by weight, the solvent dissolving power of the adhesive composition is insufficient to ensure uniform coating properties, the film brittleness is too strong even after the adhesive film is manufactured, and the handling property is poor, and wetting characteristics with the adherend even in the interlayer adhesion process. As a result, the sufficient adhesion cannot be obtained.

In the manufacture of the multilayer flexible printed circuit board, the multilayer flexible printed circuit board may be manufactured by a hot pressing method using the adhesive composition for the multilayer flexible printed circuit board having the features described so far. (See Figure 1)

First, the adhesive composition for the multilayer flexible printed circuit board is coated with a uniform thickness to make an interlayer insulating adhesive film, and then laminated with the flexible printed circuit board and cured by a hot pressing method to manufacture the multilayer flexible printed circuit board.

Hot pressing method means a method using a hot-press (Hot-Press). By using the hot pressing method, the interlayer insulating adhesive film of the multilayer flexible printed circuit board may be cured by adjusting temperature, pressure, and time.

There are three types of hot pressing methods that can be used in the present invention, including: 1) hot pressing methods under high temperature and high pressure conditions; 2) hot pressing method at high temperature, high pressure and vacuum condition; 3) hot pressing method using induction heating;

First, 1) the hot pressing method under high temperature and high pressure will be described in detail. (See Figure 2)

A. Alignment-Arrange subsidiary materials such as flexible printed circuit board and interlayer insulating adhesive film in a line before hardening work by heat press. (In units of 10-15 floors)

N. Heat Press-Heat press at high temperature (140 ~ 170 ℃) and high pressure (25 ~ 45㎏f / ㎠) to cure the insulating insulating film. In the heat presser, heating uses heat oil and cooling water uses cooling water. Heating stage => Cooling stage is one cycle (1 CYCLE). Compared to the hot pressing method under the high temperature, high pressure, and vacuum conditions, which will be described below, the productivity is excellent due to the short cycle time.

Next, 2) hot pressing method in high temperature, high pressure and vacuum conditions will be described in detail as follows. (See Figure 3)

A. Alignment-Arrange subsidiary materials such as flexible printed circuit board and interlayer insulating adhesive film in a line before hardening work by heat press. (In units of 10-15 floors)

N. Heat Press-Heat press at high temperature (140 ~ 170 ℃), high pressure (25 ~ 45㎏f / ㎠) and vacuum to cure the insulating insulating film. In the heat presser, heating uses heat oil and cooling water uses cooling water. The vacuum stage => heating stage => cooling stage => vacuum release stage is one cycle (1 CYCLE). Compared to the hot pressing method under the high temperature, high pressure, and vacuum conditions described above, the productivity is lowered, but delamination is hardly generated, so the quality is relatively good.

Finally, 3) hot pressing method using induction heating in detail as follows. (See Figure 4)

A. Alignment-Arrange subsidiary materials such as flexible printed circuit board and interlayer insulating adhesive film in a line before hardening work by heat press.

N. Induction Heating Press-Pulse heating cures the insulating insulating film by pulse heating. Pulse heating method can raise and lower temperature instantaneously and is excellent in productivity. In addition, in the case of fast curing adhesive composition it is possible to increase the temperature in a short time is advantageous compared to the hot pressing method under normal high temperature and high pressure conditions.

[ Example ]

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for illustrative purposes only and the present invention is not limited to these examples.

Preparation Example 1 Acrylic Acid Copolymer Preparation

(A1) A stirrer and reflux condenser were installed in a 1 L glass reactor capable of maintaining a temperature at 80 ° C. using cooling water, and polymerized using a device capable of detecting a temperature change according to reaction time with a thermometer. 48.17 g of butyl acrylate to be polymerized with ethyl acetate, 10.01 g of ethyl acrylate, and 3.26 g of 2-hydroxyethyl methacrylate were placed in a polymerization reactor, and charged with nitrogen to remove gas while stirring for 30 minutes. Then, 0.54 g of benzoyl peroxide (70%) as a polymerization initiator was dissolved in ethyl acetate and added dropwise using a dropping funnel. The mixture was refluxed at 80 ° C. for 12 hours to obtain a weight average molecular weight of 600,000, and a solid content of the ethyl acetate solvent. An acrylic copolymer having a solution viscosity adjusted to 40% at a temperature of 23 ° C. within 10,000 to 15,000 cps was obtained.

Preparation Example 2 Synthesis of Polyimide Resin

2,2-bis (4- (3,4-dicarboxyphenoxy) phenyl) propane dianhydride (26.1 g) was dissolved in 120 g of dimethylformamide as an acid dianhydride to obtain an acid dianhydride solution.

Also, 2,2-bis (4- (4-aminophenoxy) phenyl) propane (14.4 g) and 1,3-bis (3-aminopropyl) -1,1,3,3-tetramethyl as diamine components Disiloxane (3.8g) was dissolved in 120g of dimethylformamide to obtain a diamine solution.

This diamine solution was first introduced into a 100 ml flask reactor. The acid 2 anhydride solution was added dropwise into the flask while adjusting the temperature of the reaction system not to exceed 50 ° C, and after stirring was sufficiently stirred for 10 hours, a water pipe was attached and 50 g of toluene was added thereto to raise the temperature to 120 ° C. The mixture was kept for 8 hours, cooled to room temperature, and reprecipitated in methanol to dry the precipitate. As a result, a polyimide resin having a weight average molecular weight of 80,000 was obtained. This was redissolved in tetrahydrofuran to obtain a 20 weight% polyimide solution.

(Examples 1-4, Comparative Examples 1-4)

As shown in Table 1 below, eight adhesive compositions each containing components of a thermoplastic binder resin and a thermosetting resin such as an acrylic copolymer, a polyester resin, and a polyimide resin at the ratio shown in the table are prepared, and the composition is prepared by toluene / A homogeneous solution having a solid content of 40% was prepared using a 50:50 mixed solvent of methyl ethyl ketone, respectively. The mixed solution was applied on a release-treated polyester film with a bar coater so as to have a solid reference thickness of 25 μm, dried at 120 ° C. for 5 minutes, and then laminated with a release paper having a thickness of 100 μm. The interlayer adhesive film for substrates was obtained.

Table 1 Comparative Examples 1-4 and Comparative Examples 1-4

Ingredient Name Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Plastic Resin 1 30 35 35 20 35 39 30 - Plastic Resin 2 15 10 10 15 17 15 8 - Plastic Resin 3 -  5 - 10 - - - - Rubber resin - - - - - - - 44.5 Epoxy Resin 1 8 8 5 5 10 - 5 20 Epoxy Resin 2 10 15 5 15 20 7 5 20 Phenolic Hardeners 1 5 5 - - 8 - 5 15 Phenolic Hardeners 2 - - 3 3 - 2 - - Radical polymerizable compound 1 10 10 20 10 5 15 20 - Radical polymerizable compound 2 15 5 15 15 3 15 20 - Radical polymerizable compound 3 5 5 5 5 0 5 5 - Radical initiator 2 2 2 2 2 2 2 - Curing accelerator - - - - - - - 0.5 additive 15 15 15 15 15 15 15 15

(However, the ratio of the additive is the addition ratio when the total adhesive composition is 100)

Plastic Resin 1: Acrylic Copolymer Resin (Preparation Example 1 Polymer)

Plastic Resin 2: Polyimide Resin (Preparation Example 2 Polymer)

Plastic resin 3: Polyester resin (ESCEI ES-360, glass transition temperature: 17 ℃, number average molecular weight: 28,000)

Rubber Resin: Nitrile Butadiene Rubber (NBR) (Nippon-ion Nipol 1072, Glass Transition Temperature: -30 ℃)

Epoxy Resin 1: Bisphenol A epoxy resin (Kukdo Chemical YD-011 equivalent: 450 g / eq, Softening point: 70)

Epoxy Resin 2: Cresol Novolac Epoxy Resin (Kukdo Chemical YDCN-505 Equivalent: 200g / eq, Softening Point: 62)

Curing agent 1: Novolak-type phenolic resin (Gangnam Chemical phenolite TD-2131 OH equivalent: 110 g / eq, softening point: 80 ℃)

Curing agent 2: Novolac-type phenolic resin (Gangnam Chemical phenolite TD-2090, OH equivalent weight: 115 g / eq, softening point: 125 ° C)

Radical polymerizable compound 1: phenol noblock type acrylate monomer (Japan Chemical, EAM-2300, molecular weight: 650, average number of functional groups: 4.5 viscosity 150 ~ 400 cPs)

Radical polymerizable compound 2: Urethane modified acrylate oligomer (Nihon Kosei, UV-3000B molecular weight 25,000, Tg: -5 ° C, number of functional groups: 2-3)

Radical polymerizable compound 3: Bismaleimide (KI chemical, BMI-70 bis- (3-ethyl-5-methyl-4-maleimidephenyl) methane)

Radical initiator: lauryl peroxide (Atopina Chemical, Luperox LP, 98%)

Curing accelerator: 2-methylimidazole (Gratinization, 2MZ, Melting Point: 140 ℃)

Additive: Aluminum Hydroxide (Showa Denko, H42M, Average particle size 2-3㎛)

For the adhesive films obtained in the compositions of Examples 1 to 4 and Comparative Examples 1 to 4 above, the film handling properties, adhesive properties, heat resistance, and storage stability were evaluated, respectively, and the results are shown in Table 2 below. At this time, the method of measuring physical properties of the applied adhesive film is as follows.

(1) Film Handling

-Adhesive surface tack (stickiness): Cut the adhesive film into 10cm × 10cm size, peel off the release film and place it on the glass plate with the adhesive layer facing each other, and put the glass plate 15cm x 15cm and thickness 5mm on it at room temperature. After placing for a time, it was determined whether the re-peel between the adhesive layer.

-Film flexibility: The adhesive film was cut into 10cm × 10cm size and left in a thermostat maintained at 10 ° C. for 1 hour.

(2) adhesive

If possible, each adhesive film prepared in Examples and Comparative Examples was cut to a size of 10 cm × 10 cm to measure the adhesion under similar conditions to the manufacturing process of the multilayer flexible printed circuit board, and then polyimide film (Kapton 25 μm) and copper foil ( Mitsui, 3EC, 38㎛) A hardened specimen was prepared by hot pressing for 10 minutes at a temperature of 180 ° C. and a pressure of 20 kg / cm 2 placed between smooth surfaces.

Peel strength was measured at a peel angle of 180 ° and a peel rate of 50 mm / min using a tensile strength meter.

(3) heat resistance

Curing specimens prepared under the same conditions as the adhesive measurement specimen of paragraph (2) were cut into 20 mm x 50 mm sizes, respectively, and deposited in a 260 ° C. bath for 30 seconds, and then confirmed whether bubbles were formed by surface observation through a microscope. . The soldering heat resistance evaluation criteria are as follows.

○: Bubble generation area is 10% or less of the total area

△: bubble generation area within 10-50%

X: bubble generation area of 50% or more

(4) storage stability

The adhesive film samples prepared in Examples and Comparative Examples were placed in a thermostat maintained at 40 ° C. to measure the adhesiveness for each elapsed date. At this time, the date of falling 20% or more from the initial adhesive strength based on the peel strength of 180 ° was determined as the storage stability reference date.

Table 2 Examples 1 to 4 and Comparative Examples 1 to 4 adhesive properties comparison

Furtherance Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Film Handling ○ ○ ○ ○ × △ × △ 180 ° Peeling Strength (㎏f / ㎠) PI film 1.8 2.1 1.8 1.7 1.9 1.5 1.2 1.5 Copper foil 1.4 1.6 1.4 1.5 1.4 1.2 1.0 1.2 Heat resistance ○ ○ ○ ○ × △ × × Storage stability 30 days 40 days 30 days 30 days 5 days 10 days 3 days 5 days Total evaluation result ○ ○ ○ ○ × △ × ×

As described above, when the adhesive composition according to the present invention is used, adhesiveness and heat resistance are maintained at an equivalent level or higher than those of conventional interlayer adhesive films used in the manufacture of conventional multilayer flexible printed circuit boards. And it is possible to provide a novel adhesive film with significantly improved storage stability. In addition, when this is used in the manufacturing process of the multilayer flexible printed circuit board, productivity can be significantly improved compared to the conventional multilayer flexible printed circuit board manufacturing process.

Claims (6)

In the adhesive composition used to make an interlayer insulating adhesive film of a multi-layered flexible print circuit board, It consists of thermoplastic binder resin, thermosetting resin and curing agent, radically polymerizable compound, radical initiator, additives, Even at fast curing conditions within 180 minutes at 10 50 mm / min rate of peeling strength of the cured test piece with the copper foil of the adhesive composition has an adhesive force of 1.3 to 1.8 kgf / cm 2, and the cured test piece is deposited (260 ± 5 ° C., 30 ± 5 seconds) in a lead bath. Adhesive composition for a multilayer flexible printed circuit board having a soldering heat resistance in which the bubble generation area at the time occupies 1 to 10% of the total cured specimen area. The method according to claim 1, The thermoplastic binder resin is a mixture of at least one selected from the group consisting of an acrylic acid copolymer, a polyester resin and a polyimide resin, Adhesive composition for multilayer flexible printed circuit board, characterized in that it comprises 30 to 60 parts by weight based on 100 parts by weight of the total adhesive composition. The method according to claim 1, As the thermosetting resin and the curing agent, a solid epoxy resin having a molecular weight of 500 to 2,000 and a phenolic curing agent are used, Each compounding amount is adjusted and mixed so that the OH equivalent ratio of the said phenolic hardening | curing agent per 0.8 mol of epoxy reactors of the said epoxy resin may be 0.8-1.2, Adhesive composition for multilayer flexible printed circuit board, characterized in that it comprises 10 to 40 parts by weight based on 100 parts by weight of the total adhesive composition. The method according to claim 1, The radically polymerizable compound is a mixture of at least one selected from the group consisting of epoxy-modified acrylate, urethane-modified acrylate and maleimide, Adhesive composition for multilayer flexible printed circuit board, characterized in that it comprises 10 to 40 parts by weight based on 100 parts by weight of the total adhesive composition. The method according to claim 1, The radical initiator is a mixture of at least one selected from the group consisting of isobutyl peroxide, lauroyl peroxide, benzoyl peroxy toluene and benzoyl peroxide, which is an organic peroxide having a temperature of 1 minute at half-life of 190 ° C. or less. Thing, Adhesive composition for a multilayer flexible printed circuit board comprising 0.5 to 10 parts by weight based on 100 parts by weight of the total adhesive composition. In the method of manufacturing a multi-layered flexible print circuit board, which is obtained by laminating an interlayer insulating adhesive film made of an adhesive composition with a flexible printed circuit board and curing by hot pressing. The adhesive composition, using the adhesive composition for multilayer flexible printed circuit board according to any one of claims 1 to 5, The hot pressing method Hot pressing method at high temperature and high pressure conditions; Hot pressing method at high temperature, high pressure and vacuum conditions; or Hot pressing method using induction heating; Multi-layer flexible printed circuit board manufacturing method characterized in that.

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