KR20220054048A - Adhesive compostion, coverlay film and printed circuit board comprising the same - Google Patents

Abstract

The present invention relates to an adhesive composition, which not only maintains good adhesiveness even when exposed to high temperatures for a long period of time, but also is capable of forming a cured product having excellent bending resistance, heat resistance, quick-press property, flowability, filling ability (embeddability), migration resistance, flame retardancy, low stretchability, and flexibility, and to a coverlay film and printed circuit board comprising the same. The adhesive composition comprises: (a) a bifunctional or higher functional epoxy resin; (b) a rubber-based binder containing acrylonitrile-butadiene rubber and acrylic rubber; (c) a soluble polyimide; and (d) an inorganic filler.

Description

Adhesive composition and coverlay film and printed circuit board comprising the same

The present invention relates to an adhesive composition, a coverlay film comprising the same, and a printed circuit board.

A coverlay film is attached to the circuit pattern forming surface to protect the circuit pattern during the manufacturing process and use of the printed circuit board. Such a coverlay film includes a substrate and an adhesive layer.

The adhesive layer of the conventional coverlay film is composed of an epoxy resin and NBR or acrylic rubber. In such a conventional coverlay film, when the adhesive layer is exposed to a high temperature for a long time, the adhesive force is rapidly reduced, thereby reducing the high temperature reliability of the printed circuit board. In addition, the conventional coverlay film did not sufficiently fill (buried) the step portion (irregularity) of the circuit pattern portion of the printed circuit board due to low flowability. For this reason, a void was generated between the adhesive layer of the conventional coverlay film and the interface of the printed circuit board, and in order to remove it, a hot press process for a long time (about 1 to 2 hours) was required. , which soon caused a problem of lowering productivity. In addition, the void portion is carbonized when left at a high temperature for a long time to deteriorate the quality of the printed circuit board. In addition, there is a problem in that the conventional coverlay film is broken when exposed to a high temperature environment in a bent shape for a long time.

An object of the present invention is not only to continue to maintain excellent adhesion even when exposed to high temperatures for a long time, but also to have flex resistance, heat resistance, quick press properties, flow properties, filling properties (burial properties), migration resistance, flame retardancy, low elasticity , to provide an adhesive composition capable of forming a cured product having excellent flexibility.

Another object of the present invention is to provide a coverlay film having improved high-temperature long-term reliability by using the above-described adhesive composition.

In order to achieve the above technical problem, the present invention is (a) a bifunctional or more epoxy resin; (b) a rubber-based binder containing acrylonitrile-butadiene rubber and acrylic rubber; (c) soluble polyimides; And (d) provides an adhesive composition comprising an inorganic filler.

In addition, the present invention is a base substrate; an adhesive layer disposed on one surface of the base substrate and formed of the adhesive composition described above; and a release substrate disposed on the adhesive layer.

In addition, the present invention is a substrate body; And disposed on at least one surface of the substrate, it provides a printed circuit board comprising the above-described coverlay film.

The adhesive composition of the present invention contains a soluble polyimide together with a bifunctional or higher epoxy resin, a rubber-based binder, and an inorganic filler, so that adhesion, flowability, filling properties (embedding properties), migration resistance, flame retardancy, low elasticity, flexibility , insulation, discoloration resistance, moisture resistance, chemical resistance, dimensional stability, moldability, etc. are excellent, as well as excellent heat resistance, high temperature long-term adhesion retention, high temperature long-term adhesion, and bending resistance.

In addition, the coverlay film of the present invention includes an adhesive layer formed of the adhesive composition described above, so that long-term high temperature reliability can be improved, and furthermore, it is possible to shorten the hot press process time with a printed circuit board, and through a roll-to-roll process When manufacturing a printed circuit board, it is possible to improve the quality, productivity and efficiency of the printed circuit board.

1 is a schematic cross-sectional view of a coverlay film according to a first embodiment of the present invention.
2 is a schematic cross-sectional view of a coverlay film according to a second embodiment of the present invention.
3 is a diagram showing the punching part of the sample after hot pressing in evaluating the resin flowability according to Experimental Example 2.
4 is a graph showing the high-temperature long-term adhesive strength of the coverlay films of Example 2 and Comparative Examples 1 and 2 according to the high-temperature long-term adhesion test of Experimental Example 2.
5 is a photograph showing the appearance of the coverlay film of Example 2 and Comparative Example 1 measured according to Experimental Example 3 over time, respectively.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

<Adhesive composition>

The adhesive composition according to the present invention includes (a) a bifunctional or more functional epoxy resin; (b) a rubber-based binder containing acrylonitrile-butadiene rubber and acrylic rubber; (c) soluble polyimides; and (d) an inorganic filler, and if necessary, may further include at least one selected from the group consisting of an organic solvent, a curing agent, and a curing accelerator.

Hereinafter, each component of the adhesive composition according to the present invention will be described.

(a) 2 sensuality more than epoxy resin

In the adhesive composition of the present invention, the epoxy resin is a thermosetting resin, and by forming a three-dimensional network structure after curing, not only improves the adhesion of the coverlay film to the printed circuit board, but also has excellent heat resistance, water resistance, and moisture resistance. It is possible to improve the heat resistance reliability of the film. In addition, the epoxy resin has excellent mechanical strength, electrical insulation, chemical resistance, dimensional stability, and moldability, as well as excellent compatibility with other resins.

The epoxy resin according to the present invention is a polymer containing 2 or more, specifically 2 to 4 epoxide groups per molecule, and is preferably a bifunctional or higher epoxy resin that does not contain a halogen atom such as bromine in the molecule. . In addition, the epoxy resin may contain not only silicone, urethane, polyimide, polyamide, etc. in the molecule, but also a phosphorus atom, a sulfur atom, a nitrogen atom, and the like in the molecule. Such an epoxy resin may impart electrical insulation, heat resistance, chemical stability, toughness, and moldability to the adhesive layer.

The epoxy resin usable in the present invention is not particularly limited as long as it is a polymer containing two or more epoxy groups in the art. For example, an epoxy resin obtained by epoxidizing a condensate of phenol or alkyl phenols with hydroxybenzaldehyde, phenol novolac Type epoxy resin, cresol novolak type epoxy resin, phenol aralkyl type epoxy resin, biphenyl type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic type Epoxy resin, epoxy resin containing spiro ring, xylok type epoxy resin, polyfunctional type epoxy resin, naphthol no block type epoxy resin, bisphenol A/bisphenol F/bisphenol AD novolak type epoxy resin, bisphenol A/bisphenol F/bisphenol AD of glycidyl ether epoxy resin, bishydroxybiphenyl-based epoxy resin, dicyclopentadiene-based epoxy resin, naphthalene-based epoxy resin, and the like, but is not limited thereto.

The epoxy equivalent weight (EEW) of the epoxy resin is not particularly limited, and may be, for example, in the range of about 100 to 500 g/eq, specifically, in the range of about 300 to 500 g/eq. In this case, the (semi)cured product (eg, the adhesive layer of the coverlay film) of the adhesive composition according to the present invention may have improved chemical resistance and moisture resistance. In addition, by mixing an epoxy resin having an epoxy equivalent in the above range with a rubber-based binder and a soluble polyimide, the flowability of the adhesive layer is further maximized, so that the adhesive layer of the coverlay film can fill the step difference between circuits of the printed circuit board in a short time. there is.

In the adhesive composition of the present invention, the content of the epoxy resin is not particularly limited, and for example, may be about 15 to 25 parts by weight based on 100 parts by weight of the total amount of the adhesive composition (provided that the solvent is not included). In this case, the excellent flowability of the adhesive composition not only maximizes the filling properties of the adhesive layer, but also increases the adhesive force with the copper foil, thereby further improving heat resistance.

(b) rubber bookbinder

The adhesive composition of the present invention includes a rubber-based binder. The rubber binder contains two or more types of rubber, and contains at least one type of amorphous rubber. Here, the amorphous rubber means a rubber having a crystallinity of 10% or less. The rubber binder of the present invention not only induces film formation of the composition by imparting mutual bonding force, but also controls the flowability of the cured product (eg, adhesive layer) after curing, while maintaining adhesion, flexibility, flexibility, and crack resistance. performance can be improved.

According to one example, the rubber-based binder contains acrylonitrile-butadiene rubber and acrylic rubber.

In this case, the ratio (mixing ratio) of the acrylonitrile-butadiene rubber and the acrylic rubber is not particularly limited, and may be, for example, 1:1.5-7 by weight. However, when the ratio (mixing ratio) of the acrylonitrile-butadiene rubber and the acrylic rubber is within the above range, the adhesive layer of the coverlay film has a viscosity at about 160 to 180 ℃ when laminating with a printed circuit board about 1,000,000 to By controlling within 10,000,000 cps to maximize the flowability of the adhesive layer, the cured product of the adhesive composition according to the present invention may have improved filling properties. In particular, the adhesive composition of the present invention can improve process efficiency by shortening the hot press process time by about 5 to 6 times or more compared to the conventional adhesive composition. In addition, the adhesive layer made of the adhesive composition of the present invention has excellent adhesiveness, heat resistance, and anti-migration properties, as well as long-term adhesiveness at high temperatures, so that long-term reliability at high temperatures can be improved.

In the rubber binder of the present invention, the acrylonitrile-butadiene rubber (NBR) is a synthetic rubber that is a copolymer of acrylonitrile and butadiene. This acrylonitrile-butadiene rubber (NBR) can react with the epoxy resin to control the flowability of the adhesive layer. In addition, acrylonitrile-butadiene rubber (NBR) has excellent oil resistance, abrasion resistance, and aging resistance, and has a high commercial temperature compared to butadiene rubber, thereby providing heat resistance. In addition, acrylonitrile-butadiene rubber (NBR) may impart adhesiveness and heat resistance to the adhesive layer.

The content of acrylonitrile in the acrylonitrile-butadiene rubber is not particularly limited, and may be, for example, about 20 to 40 wt%. However, when the content of acrylonitrile in the acrylonitrile-butadiene rubber is within the above range, excellent heat resistance properties can be realized by reacting with the epoxy resin, and the reaction rate can be easily controlled to ensure fillability and fairness of the adhesive layer. can If the acrylonitrile content is lower than 20% by weight, compatibility with a solvent is lowered, and when it is higher than 40% by weight, a problem in insulating properties may occur.

The acrylonitrile-butadiene rubber may contain at least one functional group selected from the group consisting of a carboxyl group, an amino group, an epoxy group, a hydroxyl group, a methoxy group, an isocyanate group, and a vinyl group at the terminal and/or side chain. These functional groups may react with the epoxy resin to improve physical properties such as adhesion, moisture resistance, and heat resistance.

According to one example, the acrylonitrile-butadiene rubber may be an acrylonitrile-butadiene rubber (hereinafter, 'carboxyl group-containing NBR') containing a carboxyl group at the terminal and/or side chain. Since the carboxyl group-containing NBR contains a carboxyl group, the stability of the adhesive composition may be increased to improve compatibility with other components, and processability of the adhesive composition may be improved. In addition, the carboxyl group of the carboxyl group-containing NBR may react with the epoxy resin to not only improve adhesion but also improve physical properties such as moisture resistance and heat resistance.

The content of the carboxyl group in the carboxyl group-containing NBR is not particularly limited, and may be, for example, about 0.5 to 2 wt%. In this case, the content of acrylonitrile in the carboxyl group-containing NBR may be about 20 to 40 wt%.

In addition, as the carboxyl group-containing NBR, high-purity rubber in which the total content of ions such as K ⁺ , NH ⁴⁺ , Na ⁺ , Cl ^- is lowered to about 0.1 to 20 ppm may be used to impart migration resistance. General rubber contains about 150 ppm or more of impurities such as the above-mentioned ions. When a high-purity carboxyl group-containing NBR is used, the movement of conductive ions to the metal layer is minimized, so that a product with excellent migration resistance and high reliability can be provided. . According to one example, the carboxyl group-containing NBR may contain about 5 to 15 ppm of Na ⁺ ions, about 2 to 5 ppm of K ⁺ ions, and about 0.1 to 0.5 ppm of Cl ⁻ ions.

In the rubber binder of the present invention, the acrylic rubber is a synthetic rubber including a repeating unit derived from (meth)acrylic acid ester. This acrylic rubber is made by attaching the coverlay film to the printed circuit board, and then hot pressing the laminated body of the coverlay film-printed circuit board under the conditions of a temperature of about 150 to 190 ℃ and a surface pressure of about 10 to 100 kgf/cm2. (hot press) or a roll-to-roll (roll-to-roll) method after bonding the coverlay film to the printed circuit board, the laminated body of the laminated coverlay film-printed circuit board at a temperature of about 150 ~ 230 ℃ And when roll pressing with a pair of heating rollers under a linear pressure of about 2 to 20 kN, the adhesive layer is in an uncrosslinked or semi-crosslinked state to maximize the flowability of the adhesive layer together with the epoxy resin, and It can be crosslinked after heat curing to improve adhesion, shear properties and elasticity of the adhesive layer.

The acrylic rubber may contain at least one functional group selected from the group consisting of a carboxyl group, an amino group, an epoxy group, a hydroxyl group, a methoxy group, an isocyanate group, and a vinyl group at the terminal and/or side chain. These functional groups may react with the epoxy resin to improve physical properties such as adhesion, moisture resistance, and heat resistance. In addition, the acrylic rubber exists in an uncrosslinked or semi-crosslinked state in the adhesive layer, and when the coverlay film is applied to a printed circuit board, flowability of the adhesive layer is imparted to the adhesive layer, thereby preventing deterioration of the flowability of the adhesive layer.

According to one example, the acrylic rubber may be an acrylic rubber containing a carboxyl group at the terminal and/or side chain (hereinafter, 'carboxyl group-containing acrylic rubber').

The content of the carboxyl group in the carboxyl group-containing acrylic rubber is not particularly limited, and may be, for example, about 0.1 to 5% by weight.

The acrylic rubber usable in the present invention is not particularly limited as long as it is known in the art. For example, a homopolymer comprising a repeating unit derived from (meth)acrylic acid ester; a copolymer containing a repeating unit derived from (meth)acrylic acid ester and a repeating unit derived from acrylonitrile; copolymers containing a repeating unit derived from (meth)acrylic acid ester and a repeating unit derived from a chlorine atom-containing monomer; and the like. In addition, the copolymer may further contain repeating units derived from monomers such as acrylic acid, methacrylic acid, glycidyl acrylate, and glycidyl methacrylate in addition to the repeating units described above. Here, (meth)acrylic acid ester means acrylic acid ester or methacrylic acid ester.

Examples of the (meth)acrylic acid alkyl ester include ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylic rate, n-hexyl (meth) acrylate, 2-ethyl (meth) hexyl acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, n- (meth)acrylic acid alkyl ester containing a C1-C20 alkyl group such as decyl (meth)acrylate; conjugated diene monomers having 4 to 6 carbon atoms, such as butadiene; There are vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl propyl ether, and these may be used alone or in combination of two or more.

In addition to the acrylonitrile-butadiene rubber (NBR) and acrylic rubber, the rubber binder of the present invention may further contain other rubbers generally known in the art without particular limitation. For example, natural rubber; isoprene rubber, 1,2-polybutadiene, styrene butadiene rubber (SBR), chloroprene rubber, butyl rubber, ethylene-propylene Rubber (ethylene propylene rubber), butadiene rubber (BR), chlorosulphonated polyethylene rubber, epichlorohydrine rubber, polysulfide rubber, silicone rubber, fluorine rubber ( fluoro rubber) and synthetic rubber such as urethane rubber, but is not limited thereto. Among them, natural rubber, isoprene rubber, styrene rubber, styrene-butadiene rubber, butadiene rubber, chloroprene rubber, urethane rubber, etc. which are amorphous rubbers are preferable.

The content of these other rubbers is not particularly limited, and may be about 5% by weight or less, specifically about 3% by weight or less, more specifically about 0 to 1% by weight, and more specifically about It may be greater than 0% by weight and up to 0.5% by weight.

In the adhesive composition of the present invention, the content of the rubber binder is not particularly limited, and according to one example, may be about 30 to 40 parts by weight based on 100 parts by weight of the total amount of the adhesive composition (provided that the solvent is not included). In this case, the flowability of the adhesive composition is excellent, so that the filling properties of the adhesive layer are maximized, and the adhesive force can be further improved.

(c) soluble polyimide

The adhesive composition of the present invention includes a soluble polyimide. The soluble polyimide is a polymer material containing an imide ring, which is polymerized by dissolving diamine and acid dianhydride as monomers in a solvent, and then imidizing under the conditions of about 160 to 190 ° C. It is a soluble polyimide resin in a finished solution state. Such soluble polyimides have a solid content of about 15 to 25% by weight. The soluble polyimide has excellent heat resistance, chemical resistance, abrasion resistance and electrical properties based on the chemical stability of the imide ring. The soluble polyimide resin may be in the form of a random copolymer or a block copolymer. In addition, since the soluble polyimide is liquid, it can be mixed with other components to improve processability.

The soluble polyimide usable in the present invention may be used without any particular limitation as long as it is a polyimide resin in a solution state where imidization is usually completed in the art.

However, in the present invention, in order to implement excellent flowability, adhesion and flex resistance, resin flow (R/F) is in the range of about 10 to 25%, specifically, the soluble polyi having a range of about 15 to 20%. includes mids. Here, the resin flowability may be calculated by Equation 1 below.

[Equation 1]

(In Equation 1 above,

R ₁₁ is the radius of the punching part when forming a circular punching part in the center of the resin film in the B-stage state of the soluble polyimide,

R ₁₂ is after laminating the resin film on which the punching part is formed on the copper foil, and then pressing for 3 minutes under the conditions of 130 ° C and 5700 lb, in the copper foil part corresponding to the punching part, the resin of the resin layer does not flow It is the radius of the copper foil,

L ₁₁ , L ₁₂ , L ₁₃ and L ₁₄ are the lengths of the resin flowing in the 12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock directions of the punching part of the resin layer, respectively).

In addition, the soluble polyimide according to the present invention may satisfy at least one of the following physical properties (i) to (v) in order to provide excellent mechanical properties, heat resistance, adhesion and durability, and specifically two or more, more Specifically, all may be satisfied.

(i) The number of bending in the MIT bending resistance test according to the JIS C 6471 test method may be 1,000 or more, specifically 1,200 to 2,000 times. The MIT bending resistance test is to measure the number of bending when the soluble polyimide film inserted between the first copper foil and the second copper foil is repeatedly bent and broken. Specifically, under the conditions of a load of 0.5 kg, a bending speed of 175 cpm, a bending angle of 135°, and a line/space of 1000/1000 μm, a B-stage soluble polyimide film inserted between the first and second copper foils. was repeatedly bent with a bending radius of 0.38 mm to measure the number of bending when fractured.

(ii) the tensile strength of the soluble polyimide film (size: 15 mm × 120 mm × 0.05 mm, B-stage state) when tension was applied at a rate of 50.8 mm/min at a gage distance of 100 mm was 80 MPa or more, specifically 80 to 120 MPa.

(iii) The Young's modulus of the soluble polyimide film (size: 15 mm×120 mm×0.05 mm, B-stage state) when tension was applied at a rate of 50.8 mm/min at a gage point distance of 100 mm was 2,500 MPa or more, specifically 2,500 to 3,000 MPa.

(iv) When tension is applied at a rate of 50.8 mm/min at a gage distance of 100 mm, the elongation of the soluble polyimide film (size: 15 mm×120 mm×0.05 mm, B-stage state) is 5% or more , specifically 5 to 10%.

(v) When peeled by 90 degrees at 20±5° C., the adhesive force of the soluble polyimide film to an adherend (eg, copper foil) may be 1.2 kgf/cm or more, specifically 1.2 to 2 kgf/cm.

Since the soluble polyimide according to the present invention satisfies the above-described physical properties, the high temperature long-term reliability of a product using the adhesive composition of the present invention can be improved.

Such soluble polyimide is copolymerized with at least one diamine and at least one acid dianhydride. However, in the present invention, in order to improve the coating properties and flowability of the adhesive composition, the mixing ratio of diamine and acid dianhydride is adjusted to 1.015 to 1.03: 1 molar ratio. According to one example, the soluble polyimide is a polyimide polymerized by containing (a) two or more aromatic diamines and (b) two or more aromatic acid dianhydrides in a molar ratio of 1.015 to 1.03: 1, and the resin flowability is 10 to 25. % range.

In the present invention, the aromatic diamine may be used without limitation as long as it is commonly known as an aromatic compound having an intramolecular diamine structure in the art. For example, 2,2-bis(4-[4-aminophenoxy]-phenyl)propane (BAPP), 1,3'-Bis(3-aminophenoxy)benzene (APBN), phenylene diamine (PDA), oxydianiline (ODA) ), 1,3-bis(4-aminophenoxy)benzene (TPER), 4,4'-bis(4-aminophenoxy)benzene (TPEQ), 2,2'-Dimethyl-4,4'-diaminobiphenyl(m-TB -HG), 1,3-bis(4-aminophenoxy) benzene(TPE-R), 2,2-bis(4-[3-aminophenoxy]phenyl) sulfone(m-BAPS), 4,4'-diamino benzanilide (DABA), 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-aminophenyl)methanone, 2,2'-Bis(trifluoromethyl)-4,4'-diaminodiphenyl ether(6-FODA), 4, 4'-[1,4-Phenylenebis(oxy)]bis[3-(trifluoromethyl]benzenamine(FAPB), 4,4'-(((Perfluoropropane-2,2-diyl)bis(4,1-phenylene)) bis(oxy))dianiline, 4,4'-((Sulfonylbis(4,1-phenylene))bis(oxy))dianiline, 4,4'-(4,4'-(propane-2,2-diyl) There are bis(4,1-phenylene))bis(oxy) dianinilne, etc. Among them, two or more kinds are selected and mixed, In particular, when at least one of two or more kinds of aromatic diamines is an ether-based aromatic diamine, in the present invention, While increasing the flowability of the soluble polyimide, the mechanical properties can be further improved.

According to one example, the two or more aromatic diamines are selected from the group consisting of (a1) an alkylene group-containing aromatic diamine; and (a2) an alkylene group-free aromatic diamine, said alkylene group-containing aromatic diamine; and at least one of an allylene group-free aromatic diamine may be an ether group-containing aromatic diamine.

In this case, the use ratio (mixing ratio) of the alkylene group-containing aromatic diamine and the allylene group-free aromatic diamine is not particularly limited, and for example, a molar ratio of 20:80 to 50:50, specifically 25:75 It may be in a molar ratio of ~ 50:50.

In the present invention, the aromatic acid dianhydride may be used without limitation as long as it is commonly known as an aromatic compound having an acid dianhydride structure in a molecule. For example, 3,3'4,4'-benxophenonetetracarboxylic dianhydride (BTDA), 4'4-oxydiphthalic anhydride (ODPA), 5,5'-sulfonylbis-1,3-isobenzofurandione (DSDA), biphenyltetracarboxylic acid dianhydride (BPDA), 4,4′-(4,4′-Isopropylidenediphenoxy)bis(phthalic anhydride) (BSAA), 3,3′,4,4′-Biphenyltetracarboxylic dianhydride, pyromellitic dianhydride (PMDA), 4,4′-(hexafluoroisopropylidene)diphthalic Anhydride (6FDA), N,N-(4,4-sulfonylbis(4,1-phenylene))bis(1,3-dioxo-octahydroisobenzofurane-5-carboximide) dianhydride, 4,4'-(4,4'- isopropylidene-diphenoxy)bis(phthalic anhydride) (BPADA), etc., of which two or more types are selected and mixed. In particular, when at least one of the two or more aromatic acid dianhydrides is an aromatic acid dianhydride containing at least one of an ether group and a ketone group, in the present invention, the flowability and mechanical properties of the soluble polyimide are further improved, so that the present invention The adhesive composition can form a cured product having excellent adhesion and flex resistance.

As an example, the two or more types of aromatic acid dianhydride may contain (b1) an ether group-containing aromatic acid dianhydride, and (b2) a ketone group-containing aromatic acid dianhydride.

In this case, the ratio (mixing ratio) of the ether group-containing aromatic acid dianhydride and the ketone group-containing aromatic acid dianhydride is not particularly limited, and may be, for example, a molar ratio of 60:40 to 90:10.

The soluble polyimide of the present invention copolymerized including the aforementioned aromatic diamine and aromatic acid dianhydride may contain various repeating units depending on the types of the aromatic diamine and aromatic acid dianhydride used.

In one example, the soluble polyimide of the present invention may include a first repeating unit derived from the reaction of a first aromatic diamine with an ether group-containing aromatic dianhydride; a second repeating unit derived from a reaction of a second aromatic diamine with an ether group-containing aromatic dianhydride; a third repeating unit derived from the reaction of the first aromatic diamine with a ketone group-containing aromatic dianhydride; and a fourth repeating unit derived from the reaction of the second aromatic diamine with the ketone group-containing aromatic acid dianhydride. In this case, the copolymer may be a random or block copolymer.

Specifically, the first repeating unit is a repeating unit represented by the following formula (1), the second repeating unit is a repeating unit represented by the following formula (2), and the third repeating unit is a repeating unit represented by the following formula (3) , The fourth repeating unit may be a repeating unit represented by the following Chemical Formula 4, but is not limited thereto.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

In Formulas 1 to 4,

R ¹ is a tetravalent organic group derived from an ether group-containing aromatic dianhydride,

R ² is a tetravalent organic group derived from a ketone group-containing aromatic dianhydride,

Ar ¹ is a divalent organic group derived from an alkylene group-containing aromatic diamine,

Ar ² is a divalent organic group derived from an alkylene group-free aromatic diamine.

However, at least one of Ar ¹ and Ar ² contains an ether group,

a to d are each an integer of 1 or more, specifically an integer of 1 to 10,000, and more specifically an integer of 1 to 1,000.

The soluble polyimide according to the present invention may have a glass transition temperature (Tg) in the range of about 180 to 190 °C.

In the adhesive composition of the present invention, the content of the soluble polyimide is not particularly limited, and according to an example, it may be about 5 to 10 parts by weight based on 100 parts by weight of the total amount of the adhesive composition (provided that the solvent is not included). . In this case, the flowability of the adhesive composition is excellent, so that the filling properties of the adhesive layer are maximized, and the adhesive force can be further improved.

(d) weapons filler

The adhesive composition according to the present invention includes an inorganic filler. The inorganic filler not only improves mechanical properties such as insulation, heat resistance, strength, etc., and low stress, but also can control melt viscosity.

Non-limiting examples of inorganic fillers usable in the present invention include silica such as natural silica, fused silica, amorphous silica, crystalline silica, and the like; Aluminum hydroxide (ATH), boehmite, alumina, talc, glass (eg spherical glass), calcium carbonate, magnesium carbonate, magnesia, clay, calcium silicate, magnesium oxide (MgO), Titanium oxide, antimony oxide, glass fiber, aluminum borate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titania (eg TiO ₂ ), barium zirconate, calcium zirconate, boron nitride, silicon nitride, talc ( talc), mica, and the like. These inorganic fillers may be used alone or in combination of two or more. For example, the inorganic filler may contain at least one selected from the group consisting of alumina, magnesium oxide, and silica. In this case, even if the cured product of the adhesive composition according to the present invention is left at a high temperature for a long time, the shrinkage property is controlled, and dimensional stability can be improved. In addition, the adhesive composition according to the present invention has a low difference in coefficient of thermal expansion with the metal layer, low dielectric constant and dielectric loss tangent, and excellent flex resistance and long-term reliability at high temperatures.

The size (eg, average particle diameter), shape, and content of these inorganic fillers are important parameters affecting the properties of the adhesive layer.

Specifically, the inorganic filler may have an average particle diameter (D50) of about 0.5 to 15 μm, specifically, about 1 to 3 μm. In this case, the dispersibility of the inorganic filler may be improved. In addition, the inorganic filler may contain a first inorganic filler having an average particle diameter (D50) in a range of about 0.5 to 1 μm, and a second inorganic filler having an average particle diameter (D50) in a range of about 2 to 3 μm. In this case, the mixing ratio of the first inorganic filler and the second inorganic filler may be 2:8 to 5:5 by weight. In this case, the flowability of the adhesive layer is improved, the excessive flowability of the adhesive layer is controlled, so that the adhesiveness of the adhesive layer can be further improved.

In addition, the shape of the inorganic filler is not particularly limited, and examples thereof include a spherical shape, a flake shape, a dendrite shape, a cone shape, a pyramid shape, and an amorphous shape.

In the present invention, one type of inorganic filler having the same shape and average particle diameter may be used alone, or two or more types of inorganic fillers having different shapes and/or average particle diameter may be mixed and used.

In the adhesive composition of the present invention, the content of the inorganic filler is not particularly limited, and may be appropriately adjusted in consideration of mechanical properties such as insulation, heat resistance and strength, low stress, and the like. However, when the content of the inorganic filler is excessive, the adhesiveness of the adhesive layer may be deteriorated, and flowability and filling properties of the adhesive layer may be deteriorated. For example, the content of the inorganic filler may be about 15 to 30 parts by weight, specifically about 20 to 30 parts by weight, based on 100 parts by weight of the total amount of the adhesive composition (provided that the solvent is not included).

(e) hardener

The adhesive composition of the present invention may further include a curing agent if necessary. A curing agent is a component for curing an epoxy resin or the like.

The curing agent usable in the present invention includes curing agent components commonly known in the art, such as an acid anhydride curing agent, an amine-based curing agent, and a phenol-based curing agent.

Specifically, examples of the curing agent include tetrahydrophthalic anhydride, methyl tetrahydrophthalic anhydride, methyl hexahydrophthalic anhydride, hexahydrophthalic anhydride, trialkyl tetrahydrophthalic anhydride, methyl cyclohexenedicarboxylic anhydride, phthalic anhydride, maleic acid acid anhydride curing agents such as anhydride and pyromellitic anhydride; aromatic amine curing agents such as metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone; aliphatic amine curing agents such as diethylenetriamine and triethylenetetraamine; Phenol aralkyl type phenol resin, phenol novolak type phenol resin, xylok type phenol resin, cresol novolak type phenol resin, naphthol type phenol resin, terpene type phenol resin, polyfunctional type phenol resin, dicyclopentadiene type phenol resin, naphthalene type phenolic curing agents such as phenolic resins and novolac-type phenolic resins synthesized from bisphenol A and resol; There are latent curing agents such as dicyandiamide, and the like, but is not limited thereto. These may be used alone or in combination of two or more.

The content of the curing agent is not particularly limited, and for example, may be about 0.1 to 10 parts by weight, specifically about 1 to 5 parts by weight, based on 100 parts by weight of the total amount of the adhesive composition (provided that the solvent is not included).

(f) hardening accelerators

The adhesive composition of the present invention may further include a curing accelerator if necessary. The curing accelerator is a catalyst that shortens the curing time so that the components in the adhesive composition can be completely cured, and is not particularly limited as long as it is commonly known in the art. For example, there are imidazole-based curing accelerators, phosphonium-based curing accelerators, amine-based curing accelerators, metal-based curing accelerators, etc. These may be used alone or in combination of two or more.

Non-limiting examples of imidazole-based curing accelerators usable in the present invention include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-decylimidazole, 2-hexylimidazole, 2 -Isopropylimidazole, 2-undecyl imidazole, 2-heptanedecyl imidazole, 2-methyl-4-methyl imidazole, 2-ethyl-4-methyl imidazole, 2-phenylimidazole, 2- Phenyl-4-methyl imidazole, 1-benzyl-2-methyl imidazole, 1-benzyl-2-phenyl imidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl -4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecyl-imidazole trimelli Tate, 1-Cyanoethyl-2-phenyl imidazole trimellitate, 2,4-diamino-6-(2'-methylimidazole-(1')-ethyl-s-triazine, 2-phenyl -4,5-dihydroxymethylimidazole, 2-pecyl-4-methyl-5-hydroxymethylimidazole, 2-pecyl-4-benzyl-5-hydroxymethylimidazole, 4,4 '-methylene-bis-(2-ethyl-5-methylimidazole), 2-aminoethyl-2-methyl imidazole, 1-cyanoethyl-2-phenyl-4,5-di (cyanoethoxy methyl)imidazole, 1-dodecyl-2-methyl-3-benzylimidazolinium chloride, imidazole-containing polyamide, and the like.

Non-limiting examples of the phosphonium-based curing accelerator include benzyltriphenylphosphonium chloride, butyltriphenylphosphonium chloride, butyltriphenylphosphonium bromide, ethyltriphenylphosphonium acetate, ethyltriphenylphosphonium bromide, ethyltriphenyl phosphonium iodide, tetraphenylphosphonium bromide, tetraphenylphosphonium chloride, or tetraphenylphosphonium iodide.

Non-limiting examples of the amine-based curing accelerator include triethylamine, triethylenediamine, tetramethyl-1,3-butanediamine, ethylmorpholine, diazabicycloundecene, diazabicyclononene, and the like.

Examples of the metal-based curing accelerator include organometallic complexes or organometallic salts such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Examples of the organometallic complex include organocobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organocopper complexes such as copper(II) acetylacetonate, zinc(II) acetylacetonate, and the like. an organic zinc complex, an organic iron complex such as iron (III) acetylacetonate, an organic nickel complex such as nickel (II) acetylacetonate, and an organic manganese complex such as manganese (II) acetylacetonate. not limited Examples of the organometallic salt include, but are not limited to, zinc octylate, tin octylate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

The content of the curing accelerator is not particularly limited, and for example, about 0.0001 to 10 parts by weight, specifically about 0.01 to 5 parts by weight, more Specifically, it may be about 0.01 to 3 parts by weight.

(g) solvent

The adhesive composition of the present invention may further include a solvent if necessary.

The solvent that can be used in the present invention is for controlling the viscosity of the adhesive composition, and is not particularly limited as long as it can be easily evaporated in the drying step. For example, there are esters, alcohols, solvents, etc. known in the art. More specific examples of the solvent include ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone, and cyclopentanone; Ether solvents such as 1,4-dioxane and tetrahydrofuran; glycol ether solvents such as methyl cellosolve, ethyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, and diethylene glycol methyl ethyl ether; There are aromatic hydrocarbons such as toluene, xylene, benzene, and xylene, and other solvents include benzyl alcohol, N-methylpyrrolidone, γ-butyrolactone, ethyl acetate, and N,N-dimethylformamide. , but is not limited thereto. These may be used alone, or two or more may be used in combination.

In the adhesive composition of the present invention, the content of the solvent is not particularly limited, for example, when the adhesive composition includes a solvent, the solid content in the composition is about 30 to 50% by weight based on the total amount (including the solvent) of the composition, specifically The content of the solvent is adjusted so that it is about 35 to 45% by weight, more specifically, about 38 to 42% by weight. Accordingly, the applicability of the adhesive composition to the substrate of the coverlay film may be improved to improve work efficiency, and a uniform adhesive layer may be formed on the surface of the substrate.

(h) additives

The adhesive composition according to the present invention may optionally further include additives commonly known in the art in addition to the above-described components as needed according to the purpose and environment of use of the composition. For example, there are a flame retardant, a rubber crosslinking agent, a silane coupling agent, a dispersing agent, and the like, but is not limited thereto. According to one example, the additive may be at least one selected from the group consisting of a silane coupling agent and a dispersant.

The content of these additives is not particularly limited, and for example, about 0.0001 to 10 parts by weight, specifically about 0.01 to 5 parts by weight, more Specifically, it may be about 2 to 5 parts by weight.

The flame retardant that can be used in the present invention can be used without limitation as long as it is conventionally known in the art to impart flame retardancy, for example, a halogen-based flame retardant (specifically, a bromine-based flame retardant), an organic phosphorus flame retardant, an organic nitrogen-containing phosphorus compound, a nitrogen compound , silicon-based flame retardants, metal hydroxides, and the like. Specific examples include Decabromdiphenylethan (eg Firemaster-2100R), hexabromobenzene, pentabromotoluene, hexabromobiphenyl, decabromobiphenyl, hexabromocyclodecane, decabromodiphenyl ether, octabromodiphenyl ether, Hexabromodiphenyl ether, bis(pentabromophenoxy)ethane, ethylene-bis(tetrabromophthalimide), tetrabromobisphenol, poly(benzyl bromide), brominated polyphenylene ether, brominated bisphenol A halogen-based flame retardants such as , brominated (polystyrene), poly (brominated styrene) and the like; such as melamine phosphate, melamine pyrophosphate, ammonium polyphosphate, alkylamine phosphate, piperazine acid polyphosphate, melamine polyphosphonate, etc. nitrogen-phosphorus containing flame retardants; nitrogen containing flame retardants such as melamine, melamine cyanurate, triphenyl isocyanurate and the like; Triphenyl phosphate (TPP), trixylenyl phosphate (TXP), tricresyl phosphate (TCP), resorcinyl diphenyl phosphate (RDP), phenyl direzo Phosphorus such as Phenyl diresorcinyl phosphate, Cresyl diphenyl phosphate, Xylenyldiphenyl phosphate, Phenyl di(isopropylphenyl) phosphate, etc. There is a flame retardant, and the like, but is not limited thereto. These may be used alone or in combination of two or more.

The content of such a flame retardant is not particularly limited, and may be appropriately adjusted within a conventional range known in the art. For example, the content of the flame retardant is about 0.0001 to 10 parts by weight, specifically about 0.01 to 5 parts by weight, more specifically about 0.1 to 3 parts by weight, based on 100 parts by weight of the total amount of the adhesive composition (provided that the solvent is not included). It may be parts by weight.

The rubber crosslinking agent usable in the present invention is not particularly limited as long as it is known in the art, and for example, a vulcanizing agent, organic peroxide, and the like. Specifically, sulfur, Di-(2,4-dichlorobenzoyl)-peroxide, Dibenzoyl peroxide, 1,1-Di-(tert-butylperoxy)-3,3,5-trimethylcyclohexane, Butyl-4,4-di-(tert) -butylperoxy) valerate, Dicumyl peroxide, Di-(2-tert-butyl-peroxyisopropyl)-benzene, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexyne-3, 2,5-Dimethyl-2, Examples include 5-di-(tert-butylperoxy)-hexane, tert-Butyl peroxybenzoate, and Di-tert-butylperoxide.

The content of the rubber crosslinking agent is not particularly limited, and for example, may be about 0.0001 to 10 parts by weight, specifically about 0.01 to 5 parts by weight, and more specifically about 0.1 to 3 parts by weight, based on 100 parts by weight of the total amount of the adhesive composition.

In addition, the silane coupling agent that can be used in the present invention is not particularly limited as long as it is commonly known in the art, for example, epoxy-based, methacryloxy-based, amino-based, vinyl-based, mercapto-sulfide-based, ureide-based There exist silane coupling agents, such as these, and can be used individually or in combination of 2 or more types. Such a silane coupling agent may improve adhesion between the inorganic filler and other components when the adhesive composition is cured. According to one example, the silane coupling agent may be an epoxy-based silane coupling agent, specifically glycidyloxy (C ₁ ~C ₂₀ )alkyltri(C ₁ ~C ₂₀ )alkoxy silane. Examples of such a silane coupling agent may be 3-Glycidoxypropyltrimethoxy silane, 2-(3,4 epoxycyclohexyl) ethyltrimethoxysilane, 2-(3,4 epoxycyclohexyl) ethyltriethoxysilane, 3-glycidoxypropyl triethoxysilane, 3-glycidoxypropyl methyldimethoxysilane, or 3-glycidoxypropyl methyldiethoxysilane. .

The content of the silane coupling agent is not particularly limited, and for example, about 0.0001 to 10 parts by weight, specifically about 0.01 to 5 parts by weight, based on 100 parts by weight of the total amount of the adhesive composition (provided that the solvent is not included); More specifically, it may be about 3 to 4 parts by weight.

In addition, the dispersing agent usable in the present invention is not particularly limited as long as it is generally known in the art, for example, fatty acid salt (soap), α-sulfo fatty acid ester salt (MES), alkylbenzenesulfonate (ABS), straight chain alkylbenzenesulfonic acid low molecular weight anionic (anionic) compounds such as salts (LAS), alkyl sulfates (AS), alkyl ether sulfate salts (AES), and triethanol alkyl sulfates; low molecular weight nonionic compounds such as fatty acid ethanolamide, polyoxyethylenealkyl ether (AE), polyoxyethylene alkylphenyl ether (APE), sorbitol, sorbitan and the like; low molecular weight cationic (cataionic) compounds such as alkyltrimethylammonium salt, dialkyldimethyl ammonium chloride, and alkylpyridinium chloride; low molecular weight amphoteric compounds such as alkylcarboxylbetaine, sulfobetaine, and lecithin; and formalin condensates of naphthalene sulfonate, polystyrene sulfonate, polyacrylate, a copolymer salt of a vinyl compound and a carboxylic acid-based monomer, carboxymethyl cellulose, polyvinyl alcohol, and the like. In addition, examples of commercially available dispersants include DIC (DaiNippon Ink & Chemicals) company F-114, F-177, F-410, F-411, F-450, F493, F-494, F-443, F-444, F-445, F-446, F-470, F-471, F-472SF, F-474, F-475, F-477, F-478, F-479, F480SF, F-482, F-483, F-484, F-486, F-487, F-172D, MCF-350SF, TF-1025SF, TF-1117SF, TF-1026SF, TF-1128, TF-1127, TF-1129, TF-1126, TF- 1130, TF-1116SF, TF-1131, TF1132, TF1027SF, TF-1441, TF-1442, TF-1740, and the like, but are not limited thereto. These may be used alone or in combination of two or more.

The content of such a dispersant is not particularly limited, and for example, about 0.0001 to 10 parts by weight, specifically about 0.01 to 5 parts by weight, more specifically about 0.0001 to 10 parts by weight based on 100 parts by weight of the total amount of the adhesive composition (provided that the solvent is not included). As may be about 3 to 4 parts by weight.

As described above, in the adhesive composition of the present invention, a bifunctional or higher epoxy resin, a rubber-based binder, a soluble polyimide, and an inorganic filler may be mixed in various amounts.

According to one example, the adhesive composition of the present invention comprises 15 to 25 parts by weight of an epoxy resin, 30 to 40 parts by weight of a rubber binder, 5 to 25 parts by weight based on 100 parts by weight of the total amount of the adhesive composition (provided that the solvent is not included). 10 parts by weight of a soluble polyimide, and 15 to 30 parts by weight of an inorganic filler.

According to another example, the adhesive composition of the present invention may include an epoxy resin, a rubber-based binder, and a soluble polyimide in a weight ratio of 2 to 6: 0.5 to 3: 1. In this case, in the rubber-based binder, acrylonitrile-butadiene rubber and acrylic rubber may be included in a weight ratio of 1:1.5-7.

According to another example, the adhesive composition of the present invention is a ratio of the total content (W _a +W _c ) of the epoxy resin and the rubber binder to the content (W _b ) of the soluble polyimide [(W _a +W _c )/ W _b ] may range from 5 to 12. In this case, the epoxy resin and the rubber-based binder may be included in a ratio of 1:1 to 3 by weight. In addition, in the rubber binder, acrylonitrile-butadiene rubber and acrylic rubber may be included in a weight ratio of 1:1.5-7.

The adhesive composition according to the present invention may be cured by drying at about 145 to 155° C. for 1 to 5 minutes to form a film, and then leaving it to stand at a temperature of about 57 to 63° C. for 71 to 73 hours for aging. In this case, the cured product of the adhesive composition is a cured product in a B-stage state, and the degree of curing may be about 35 to 45%. The cured product of this adhesive composition is cured for about 1.8 to 2.2 hours at about 138 to 142 ° C. or 0.8 to 1.2 hours at 148 to 152 ° C. after laminating with a printed circuit board to be fully cured into a C-stage cured product. can be

In addition, the adhesive composition of the present invention may have a viscosity at room temperature (20±5° C.) of about 500 to 1,500 cPs, specifically about 600 to 1400 cPs.

The adhesive composition of the present invention may be prepared through a method commonly known in the art. For example, a bifunctional or more epoxy resin; a rubber-based binder containing acrylonitrile-butadiene rubber and acrylic rubber; soluble polyimide; and an inorganic filler, and optionally at least one of a curing agent, a curing accelerator, a solvent and an additive in a ball mill, bead mill, 3 roll mill, basket mill, dyno mill, planetary (planetary) ) using mixing equipment such as mixing and stirring at room temperature to an appropriately elevated temperature to prepare an adhesive composition.

The adhesive composition of the present invention as described above has adhesiveness, flowability, fillability (burial property), migration resistance, flame retardancy, low elasticity, flexibility, insulation, discoloration resistance, moisture resistance, chemical resistance, dimensional stability, molding In addition to excellent properties, it is also excellent in heat resistance, high temperature long-term adhesion retention, high temperature long-term adhesion, and bending resistance.

According to one example, the cured product of the adhesive composition according to the present invention is allowed to stand at a temperature of about 158 ° C. for 2,000 hours, and the adhesive strength to the adherend [eg, the circuit pattern of the printed circuit board (Line/space = 1000/1000 μm)] The retention rate may be 60% or more, specifically, about 80% or more. At this time, after the cured product was left at a temperature of about 158 ° C for about 2,000 hours, the adhesion to the adherend [eg, the circuit pattern of the printed circuit board (Line/space = 1000/1000 μm)] measured at 25 ° C was 1.0 kgf/cm or more, specifically 1.2 kgf/cm or more. As such, the cured product (eg, the adhesive layer of the coverlay film) formed of the adhesive composition of the present invention can maintain excellent adhesive properties for a long time, unlike the conventional polyurethane-based or epoxy-based adhesive composition, even if left for a long time under high-temperature environmental conditions. there is. Accordingly, the adhesive composition of the present invention can be applied to various fields. Here, the cured product of the adhesive composition is a C-stage state obtained by thermal curing at about 138 to 142 ° C. for about 1.8 to 2.2 hours or at 148 to 152 ° C. for about 0.8 to 1.2 hours after filming the adhesive composition. is hardened At this time, complete curing means a case where the resin flowability (refer to Experimental Example 2 below) is 5% or less.

According to another example, the cured product of the adhesive composition according to the present invention is attached to an adherend [eg, a circuit pattern of a printed circuit board (Line/space=1000/1000 μm)] at a temperature of about 300 ° C. When it is left for a second, the void rate per unit area (3 cm×15 cm) for the adherend is 0%. As such, even if the cured product made of the adhesive composition of the present invention is attached to an adherend having a step portion and then exposed to high temperature environmental conditions, unlike the conventional polyurethane-based or epoxy-based adhesive composition, the step portion (eg, circuit pattern and void) hardly grows (generates). For this reason, even if the cured product of the adhesive composition according to the present invention is continuously left at a temperature of about 300° C. for 30 minutes or more, the carbonization rate per unit area (3 cm×15 cm) of the adherend is 0%. Therefore, since the adhesive composition of the present invention has excellent long-term heat resistance at high temperatures, it is possible to secure long-term heat resistance reliability of the final coverlay film and the printed circuit board.

According to another example, the cured product of the adhesive composition according to the present invention may satisfy at least one of the following physical properties (i) and (ii):

(i) 30 to 40% resin flowability; and

(ii) The number of flexures greater than or equal to 1,200 as measured according to the MIT flexural resistance test.

Here, the resin flowability of the cured product may be calculated according to Equation 2 below.

[Equation 2]

(In Equation 2 above,

R ₂₁ is the radius of the punching part when forming a circular punching part in the center of the cured product (eg, the adhesive layer of the coverlay film);

R ₂₂ is after laminating the cured product (eg, adhesive layer) formed with the punching part on the copper foil, and then pressing for 3 minutes under the conditions of 130 ° C and 5700 lb, and then the cured product in the copper foil part corresponding to the punching part It is the radius of the copper foil area where the melt does not flow,

L ₂₁ , L ₂₂ , L ₂₃ and L ₂₄ are lengths through which the melt of the cured product flows in the 12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock directions of the punching part, respectively).

If the cured product according to the present invention has the resin flowability in the above range, the flowability and filling properties of the cured product are maximized, and the hot press process time of the printed circuit board is reduced by about 3 to compared to the conventional coverlay film. It is possible to improve the efficiency of the process by shortening it by 5 times, and of course, it can be laminated with a printed circuit board through a roll-to-roll process.

The MIT bending resistance test is in accordance with the JIS C 6471 test method, and the number of bending until fracture when the cured product is bent to a bending radius of 0.38 mm is measured, specifically (i) a load of 0.5 kg, (ii) a bending speed of 175 cpm, (iii) a bending angle of 135°, and (iv) a line/space of 1000/1000 μm.

If the cured product according to the present invention has the above-mentioned number of bending, even if the product (eg, coverlay film) including the cured product is mounted in a bent form and exposed to a high temperature environment for a long time, the conventional coverlay film Unlike this, cracks or fractures are less likely to occur in the film, and long-term reliability at high temperatures of the coverlay film can be improved.

In addition, the cured product of the adhesive composition according to the present invention is about 300 in a state of being attached to an adherend [eg, a circuit pattern of a printed circuit board (eg, Line/space=1000/1000, 500/500, 100/100 μm)). When floating for 10 minutes in a solder bath at ℃, the change rate of appearance per unit area (3cm×15cm) is 0%. In this case, the appearance change rate refers to the presence or absence of occurrence of blaster and delamination on the exterior, and the occurrence range when it occurs. As described above, since the cured product formed from the adhesive composition of the present invention has excellent high-temperature and long-term heat resistance, even when left in a high-temperature soldering bath for a long time, blaster or delamination hardly occurs, so that the high-temperature long-term reliability of the coverlay film can be improved. can

<Coverlay Film>

The present invention provides a coverlay film using the above-described adhesive composition.

1 is a cross-sectional view schematically showing a coverlay film according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view schematically showing a coverlay film according to a second embodiment of the present invention.

The coverlay films 10A and 10B according to the present invention are a coverlay film used to protect a printed circuit board, in particular, a circuit of a printed circuit board, the base substrate 11; an adhesive layer 12 disposed on one surface of the substrate and formed of the aforementioned adhesive composition; and a release substrate 13 disposed on the adhesive layer. In addition, if necessary, the present invention may further include a surface protection substrate 14 disposed on the other surface of the base substrate 11 .

Hereinafter, with reference to FIG. 1, the coverlay film 10A according to the first embodiment of the present invention will be described.

As shown in FIG. 1 , the coverlay film 10A according to the first embodiment of the present invention has a structure in which an adhesive layer 12 and a release substrate 13 are sequentially stacked on a base substrate 11 .

(1) base material

In the coverlay film 10A according to the present invention, the base substrate 11 is attached to the printed circuit board by the adhesive layer 12 to protect the circuit of the printed circuit board.

According to one example, the base substrate 11 may be an insulating substrate. In this case, low dielectric properties of the coverlay film can be secured.

As the base substrate 11, any plastic film commonly known in the art may be used without limitation. For example, polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate, polyethylene films, polypropylene films, cellophane, diacetylcellulose films, triacetylcellulose films, acetylcellulose butyrate films, polychlorinated Vinyl film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone Films, polyetherimide films, polyimide films, fluororesin films, polyamide films, acrylic resin films, norbornene-based resin films, cycloolefin resin films, and the like. This plastic film may be transparent or translucent, or may be colored or uncolored.

According to one example, the base substrate 11 may be polyethylene terephthalate (PET).

According to another example, the base substrate 11 may be polyimide (PI).

According to another example, the base substrate 11 may be a thermoplastic polymer film having a melting point of about 300 °C or less, specifically about 150 to 300 °C. Specifically, the base substrate 11 may be a polyethylene naphthalate (PEN) film. This can impart thermal stability to the low-melting-point thermoplastic polymer film due to excellent heat resistance of the adhesive layer.

The thickness of the base substrate is not particularly limited, and may be, for example, about 5 to 50 μm.

(2) adhesive layer

In the coverlay film 10A according to the present invention, the adhesive layer 12 is disposed on one surface of the base substrate 11 to adhere the coverlay film 10A to the surface of the printed circuit board.

The adhesive layer 12 of the present invention is in a semi-cured to fully cured state, and includes a cured product formed of the above-described adhesive composition. At this time, the degree of curing (gelation degree) of the adhesive layer 12 may be in the range of about 40 to 80%, specifically, about 40 to 70% of the gelation.

However, in the present invention, the adhesive composition includes the aforementioned epoxy resin, rubber-based binder, soluble polyimide and inorganic filler, and may further include one or more curing agents, curing accelerators, solvents, and other additives as necessary.

Descriptions of such an epoxy resin, a rubber binder, a soluble polyimide, an inorganic filler, a curing agent, a curing accelerator, a solvent, and other additives are the same as those described in the adhesive composition section, and thus will be omitted.

The adhesive layer 12 of the present invention has excellent high-temperature long-term heat resistance, high-temperature long-term adhesiveness, high-temperature long-term adhesion retention, flowability, fillability (embedding properties), flex resistance, and the like, as described in the above-described adhesive composition section.

Specifically, the adhesive layer 12 may have an adhesive force retention rate of about 60% or more, specifically, about 80% or more under high temperature and long-term conditions (158° C., 2,000 hours). In this case, the adhesive layer 12 may have an adhesive strength of 1 kgf/cm or more, specifically 1.2 kgf/cm or more. In addition, when the adhesive layer 12 is left at a temperature of 300° C. for 10 seconds, a unit area (3 cm) for a circuit pattern (eg, Line/space=1000/1000, 500/500, 100/100 μm) of a printed circuit board Since the void rate per x 15 cm) is 0%, defects due to voids between the coverlay film and the printed circuit board can be suppressed. In addition, the adhesive layer 12 is attached to the circuit pattern (eg, Line/space=1000/1000, 500/500, 100/100 μm) of the printed circuit board and floating in a solder bath at about 300° C. for 10 minutes. ), there is almost no change in appearance such as thickness change, delamination, or blaster. In addition, the adhesive layer 12 is applied to the circuit pattern (eg, Line/space=1000/1000, 500/500, 100/100 μm) of the printed circuit board when left under high temperature long-term conditions (about 300° C., 30 minutes or more). Since the carbonization rate per unit area (3cm×15cm) is 0%, the occurrence rate of defects due to carbonization can be reduced. In addition, the adhesive layer 12 has a resin flowability of 30 to 40%, and the number of bending measured according to the MIT flex resistance test is 1,200 or more.

As described above, since the adhesive layer 12 of the present invention has excellent high-temperature long-term heat resistance, high-temperature long-term adhesiveness, high-temperature long-term adhesion retention, flowability, fillability, and flex resistance, the coverlay film of the present invention has improved long-term high-temperature reliability. It can be done, and furthermore, it is possible to shorten the hot press process time with the printed circuit board. In addition, the coverlay film of the present invention may be applied to a printed circuit board through a roll-to-roll process, and in this case, the quality, productivity and efficiency of the printed circuit board may be improved.

After laminating between the coverlay film and the printed circuit board, the above-described adhesive layer 12 is thermally cured at about 138 to 142 ° C. for about 1.8 to 2.2 hours or at 148 to 152 ° C. for about 0.8 to 1.2 hours. Can be hardened with cargo.

The thickness of the adhesive layer is not particularly limited, and may be, for example, about 10 to 50 μm. However, when the adhesive layer has a thickness within the above-described range, film forming properties and thickness uniformity of the film may be improved.

(3) release substrate

In the coverlay film 10A according to the present invention, the release substrate 13 is disposed on the adhesive layer 12 until the coverlay film is applied to the printed circuit board so that the adhesive layer 12 is contaminated from foreign substances in the external environment. As a preventive part, the coverlay film is peeled off and removed before being applied on one or both sides of the printed circuit board.

The release substrate 13 is not particularly limited as long as it is a conventional one known in the art and can be peeled off without damage to the adhesive layer 12, for example, a fluorine release film, specifically a platinum catalyst containing itself It may be a fluorine silicone release agent, a fluorine release agent in which a fluorine-type curing agent and an adhesive additive are mixed.

In the present invention, the release force of the release substrate is not particularly limited, and for example, the release force of the release substrate with respect to the adhesive layer measured by ASTM D3330 may be about 20 to 150 gf/inch.

Moreover, the thickness of a mold release base material is not specifically limited. For example, the ratio (T3/T2) of the thickness (T3) of the release substrate to the thickness (T2) of the adhesive layer may be about 1 to 5.

Hereinafter, a coverlay film 10B according to a second embodiment of the present invention shown in FIG. 2 will be described.

As shown in FIG. 2 , the coverlay film 10B according to the second embodiment includes a base substrate 11 ; disposed on one surface of the base substrate, an adhesive layer 12 formed of the above-described adhesive composition; a release substrate 13 disposed on the adhesive layer 12; and a surface protection substrate 14 disposed on the other surface of the base substrate 11 .

In the coverlay film 10B which concerns on 2nd Embodiment, since the description of the base substrate 11, the adhesive layer 12, and the release substrate 13 is the same as that of 1st Embodiment, it is abbreviate|omitted.

In the coverlay film 10B according to the second embodiment, the surface protection substrate 14 is a portion disposed on the other surface (specifically, the outer surface) of the base substrate 11, and the base substrate 11 is an external foreign substance. It prevents contamination by , and protects the surface of the film, especially the surface of the substrate, when the coverlay film is attached to the printed circuit board through the hot press process. The surface protection substrate 14 may be peeled off and removed as needed when the coverlay film is applied to the printed circuit board.

The surface protection substrate usable in the present invention is not particularly limited as long as it is a protective film commonly known in the art, for example, a polyester film such as polyethylene terephthalate (PET), polybutylene terephthalate, or polyethylene naphthalate, a polyethylene film, Polypropylene film, cellophane, diacetyl cellulose film, triacetyl cellulose film, acetyl cellulose butyrate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate Film, polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone film, polyetherimide film, polyimide film, polycyclohexylene dimethylene terephthalate, fluororesin film, polyamide There are a film, an acrylic resin film, a norbornene-based resin film, a cycloolefin resin film, and the like, but is not limited thereto.

In addition, at least one surface of the surface protection substrate 14 , specifically, a surface in contact with the base substrate 11 may be a matt surface. In this case, the matte surface of the surface protection substrate 14 may have a peeling force in the range of about 30 to 150 gf/inch with respect to the substrate. The surface protection substrate 14 may be easily peeled off and removed from the coverlay film after the cover shielding film is attached to the flexible printed circuit board.

In addition, the thickness of the surface protection substrate is not particularly limited, and may be, for example, about 20 to 150 μm, and specifically about 80 to 120 μm.

The coverlay films 10A and 10B of the present invention may be manufactured by a conventional method known in the art, except for forming an adhesive layer using the above-described adhesive composition.

For example, in the method for manufacturing a coverlay film according to the present invention, the adhesive composition is coated on one surface of a base substrate, dried to form a film, then aged to form an adhesive layer, and then released on the adhesive layer After disposing the substrate, lamination may be performed, and, if necessary, a surface protection substrate may be laminated to the other surface of the base substrate.

The coating method of the adhesive composition is a conventional coating method in the art, for example, a dip coating method, an air knife coating method, a curtain coating method, a wire bar coating method, a gravure coating method, a comma coating method, a slot coating method, an extrud method. A full coat method, a spin coat method, a slit scan method, an inkjet method, etc. are mentioned.

The drying process may be appropriately carried out within conventional conditions known in the art, for example, may be carried out at about 145 ~ 155 ℃ for 1 ~ 5 minutes.

The aging process is a thermal stabilization process, and may be appropriately carried out within conventional conditions known in the art. As an example, the aging may be performed at about 58 to 62 ℃ for about 71 to 73 hours. The adhesive layer formed through this aging process is in a semi-cured state and has a degree of curing of about 40 to 80%. Therefore, the adhesive layer of the present invention has flowability when laminating with a printed circuit board later.

As described above, the coverlay film of the present invention has high-temperature long-term adhesiveness retention, high-temperature long-term adhesiveness, heat resistance, flex resistance, flowability, fillability (burial property), low elasticity, migration resistance, discoloration resistance, moisture resistance , because it contains an adhesive layer with excellent chemical resistance, etc., it is possible to improve the hot press process efficiency in the manufacture of printed circuit boards, reduce the defect rate of the printed circuit board, and further improve the high temperature long-term reliability of the printed circuit board can do it In addition, the coverlay film of the present invention can improve the quality, productivity and efficiency of the printed circuit board when the printed circuit board is manufactured by the roll-to-roll process.

<Printed circuit board>

The present invention provides a printed circuit board including the above-described coverlay film.

According to one example, the printed circuit board of the present invention includes a substrate body; and the above-described coverlay films (10A, 10B) disposed on at least one surface of the main body. It is excellent in bending resistance, flowability, filling (burial), low elasticity, migration resistance, discoloration resistance, moisture resistance, and chemical resistance. Accordingly, the printed circuit board of the present invention has high quality, productivity and efficiency, as well as excellent high-temperature long-term reliability.

Hereinafter, the present invention will be described in more detail by way of Examples and Comparative Examples. However, the present invention is not limited thereto.

[ preparation example 1-2 and Comparative preparation example 1-4] - Preparation of soluble polyimide

A soluble polyimide was prepared by mixing and copolymerizing diamine and acid dianhydride according to the composition shown in Table 1 below.

preparation example Comparative preparation example One 2 One 2 3 4 diamine BAPP:APBN
(molar ratio) 0.72:0.30 0.72:0.30 0.71:0.30 0.51:0.50 0.71:0.30 0.51:0.50 acid dianhydride ODPA: BTDA
(molar ratio) 0.80:0.20 0.50:0.50 0.80:0.20 0.80:0.20 - - BPDA:BSAA
(molar ratio) - - - - 0.50:0.50 0.50:0.50 1) BAPP: 2,2-bis(4-[4-aminophenoxy]-phenyl)propane
2) APBN: 1,3'-Bis(3-aminophenoxy)benzene
3) ODPA: 4'4-oxydiphthalic anhydride
4) BTDA: 3,3'4,4'-benxophenonetetracarboxylic dianhydride
5) BPDA: biphenyltetracarboxylic acid dianhydride
6) BSAA: 4,4'-(4,4'-Isopropylidenediphenoxy)bis(phthalic anhydride)

[ Experimental example 1] - Evaluation of physical properties of soluble polyimide

The physical properties of each polymerized soluble polyimide in Preparation Examples 1 to 2 and Comparative Preparation Examples 1 to 4 were evaluated as follows, and the results are shown in Table 2 below.

(One) coatability

The soluble polyimide was coated on the copper foil to observe the appearance of the coating layer, such as whether the thickness of the coating layer was uniform and whether or not pinholes were generated. At this time, i) If the appearance is very good, it is indicated by '◎', ii) If the appearance is excellent, it is indicated by '○', iii) If the appearance is normal, it is indicated by '△', iv) The appearance is poor , it is expressed as 'Χ'.

(2) Viscosity

The viscosity of the soluble polyimide was measured using a rheometer.

(3) resin flow

After laminating one Sus plate (12cmx12cm) on two blue pads (13cmx13cm), 1 oz copper foil (4cmx4cm) was placed on the center of the Sus plate. On the other hand, after drying the soluble polyimide at about 190 ° C. for 5 minutes to form a soluble polyimide film, it is sampled in a size of 2.5 cm x 2.5 cm, and then X with a pen on the back side of the soluble polyimide film sample After marking the ruler, the punching part is formed by punching with a punch so that the center of the X-shape is visible. Thereafter, the soluble polyimide film was placed on the center of the copper foil, and then a PET film (12cmx12cm), an Al plate (4cmx4cm) and two blue pads (4cmx4cm) were sequentially placed. Thus, a laminate was obtained. The laminate was pressed for 3 minutes at a temperature of 130° C. and a pressure of 570 lb. Then, R ₁₁ , R ₁₂ , L ₁₁ , L ₁₂ , L ₁₃ , and L ₁₄ were measured using an optical microscope, respectively, and then the following The resin flowability was calculated according to Equation 1.

[Equation 1]

(In Equation 1 above,

R ₁₁ is the radius of the punching part when forming a circular punching part in the center of the soluble polyimide film,

R ₁₂ is the soluble polyimide film formed with the punching part is laminated on the copper foil, and then pressed for 3 minutes under the conditions of 130 ° C and 5700 lb, and the resin of the resin layer in the copper foil part corresponding to the punching part is It is the radius of the non-flowing copper foil,

L ₁₁ , L ₁₂ , L ₁₃ and L ₁₄ are the lengths of the resin flowing in the 12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock directions of the punching part of the resin layer, respectively).

(4) Mechanical properties

Tensile strength (Strength) (MPa), Young's Modulus (MPa) and elongation (%) were measured using UTM (Instron, model name: 5942) under the following conditions.

i) Sample size: width - 15 mm, length - 120 mm, thickness - 0.05 mm

ii) Jig spacing: 50.8 mm

iii) Measuring speed: 50.8 mm/min

iv) Load: 5.1 kgf/㎠

v) Gauge distance: 100 mm

(5) Peel strength

Sus Plate (thickness: 1.2 mm) / 4 blue pads / Sus plate (thickness: 1.2 mm) / release PET film / PVC film / release PET film / copper foil (thickness: 35 μm) / soluble polyimide film / release PET film /PVC film/Sus plate (thickness: 1.2 mm)/release PET film/PVC film/release PET film/copper foil (thickness: 35 μm)/soluble polyimide film/release PET film/PVC film/Sus plate (thickness: 1.2 ㎜) / 4 sheets of blue pad / Sus Plate (thickness: 1.2 mm) laminated in the order, and then hot pressed under a temperature of 150 ℃ and a pressure of 40 kgf / ㎠ for 60 minutes to laminate the soluble polyimide film on the copper foil. A sample was obtained. In this case, the soluble polyimide film used was obtained by drying the soluble polyimide on the copper foil at about 190° C. for 5 minutes, and had a thickness of about 15 μm. After that, the sample was cut to a certain size (length in TD direction: 0.5 cm, length in MD direction: 12 cm), and then the cut sample was used on both sides of a prepreg for peel strength test (size: 3 cm × 10 cm) It was attached so that the copper foil surface of the sample was in contact on the tape. Then, after peeling off only about 30 mm of the soluble polyimide film from the end of the sample, the 90 degree adhesion of the sample is measured three or more times using UTM (Instron, model name: 5942), at this time, the sample is peeled off by about 2 cm The adhesive force was measured when losing, and the average value thereof was expressed as the adhesive force.

(6) MIT flexural properties

MIT flexural properties were measured according to the JIS C 6471 test method.

Specifically, SUS plate (thickness: 1.2 mm) / 5 sheets of Kraft Paper (thickness: 0.28 mm) / Al plate (thickness: 0.8 mm) / release PET film (thickness: 25 μm) / MIT pattern substrate / soluble polyimide film /Releasable PET film (thickness: 25㎛)/PVC film (thickness: 0.25 mm)/Al plate (thickness: 0.8 mm)/5 sheets of Kraft Paper (each thickness: 0.28 mm)/SUS plate (thickness: 1.2 mm) After lamination in the order of 150 ℃ and pressed under a pressure of 25 kgf / cm 2 for 1 hour, a sample in which a soluble polyimide film was laminated on a MIT pattern substrate was obtained. At this time, the used MIT pattern substrate has a structure of a release PI film (thickness: 18 μm)/MIT copper pattern (thickness: 12 μm, line/space=1000/1000 μm), and the soluble polyimide film is the MIT pattern It was obtained by drying soluble polyimide on a substrate at 190° C. for 5 minutes, and had a thickness of 15 μm. Thereafter, the folding cycle of the sample was measured using an MIT measuring instrument (TOYOSEIKI, MIT-SA) under the following conditions.

i) Load: 0.5 kg

ii) Bending speed: 175 cpm

iii) bending angle: 135°

iv) Line/Space: 1000/1000 μm

(7) Heat resistance (Solder Floating, S/F)

Sus Plate (thickness: 1.2 mm)/4 sheets of blue pad/Sus plate (thickness: 1.2 mm)/release PET film/PVC film/release PET film/copper foil (thickness: 35㎛)/soluble polyimide film/ copper foil (thickness) : 35 μm)/Releasable PET film/PVC film/Sus plate (thickness: 1.2 mm)/Releasable PET film/PVC film/Releasable PET film/Copper foil (thickness: 35 μm)/soluble polyimide film/Copper foil (thickness: 35 ㎛) / release PET film / PVC film / Sus plate (thickness: 1.2 mm) / blue pad / Sus plate (thickness: 1.2 mm) after lamination in the order, 150 ℃ temperature and 40 kgf / ㎠ pressure A sample in which copper foil-soluble polyimide film-copper foil was laminated was obtained by hot pressing under a for 60 minutes. In this case, the soluble polyimide film used was obtained by drying the soluble polyimide on the copper foil at about 190° C. for 5 minutes, and had a thickness of about 15 μm. Thereafter, the sample was cut to a predetermined size (30 mm×30 mm), immersed in a solder bath at 300° C. for 5 minutes, and then visually observed for appearance defects such as lifting or swelling. At this time, if there was no appearance defect such as lifting/expansion, 'Pass' was indicated, and if there was an appearance defect, 'Fail' was indicated.

preparation example Comparative preparation example One 2 One 2 3 4 coatability ◎ ◎ △ ○ △ ○ Viscosity (cPs) 2,000 30,000 70,000 50,000 90,000 50,000 Resin flowability (%) 20 10 2 % 5% 3% 5% Tensile strength (MPa) 83.2 110.7 101.9 72.7 116.3 99.5 Young's modulus (MPa) 2,670 2,830 2,820 2,550 2,880 2,850 Elongation (%) 5.9 5.2 7.3 2.8 5.0 8.0 Adhesion (kgf/㎠) 1.5 1.4 0.4 1.7 1.0 1.7 MIT Flexural Characteristics (times) 1,500 1,200 300 700 800 600 Heat resistance (S/F 300 ℃) Pass Pass Pass Pass Pass Pass

[ Example One]

1-1. Preparation of adhesive composition

An adhesive composition (viscosity: about 800 cPs) was prepared by mixing each component according to the composition shown in Table 3 below. In Table 3 below, the content units of the epoxy resin, NBR, acrylic resin, soluble polyimide, inorganic filler, curing agent, and curing accelerator are parts by weight, based on 100 parts by weight of the total amount of the adhesive composition. The specifications of the raw materials constituting each composition described in Table 3 below are shown in Table 4 below.

1-2. coverlay manufacture of film

The adhesive composition prepared in Example 1-1 was applied on one side of a polyimide film (thickness: about 25 μm) as a base substrate, and then the coated composition was dried at about 150° C. for about 3 minutes. After aging, it was left at 60° C. for 72 hours and aged to prepare a coverlay film having an adhesive layer (curing degree: about 40%, thickness: about 35 μm).

[ Example 2-5 and comparative example One]

Adhesive compositions and coverlay films of Examples 2 to 5 and Comparative Example 1 were prepared in the same manner as in Example 1, except that each component was mixed according to the composition shown in Table 3 below. The specifications of the raw materials constituting each composition described in Table 3 below are shown in Table 4 below.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 A 15 25 25 15 25 25 B B1 15 10 5 15 5 15 B2 25 25 25 25 25 25 C 5 5 5 10 10 - D 30 25 30 25 25 25 E 2 3 3 2 3 3 F 3 2.5 2.5 3 2.5 2.5 G 3 2.5 2.5 3 2.5 2.5 H 2 2 2 2 2 2

Component ingredient A epoxy resin YD-011 (Kukdo Chemical) (EEW: 475 g/eq) B rubber binder B1 Acrylonitrile-butadiene rubber (NBR): XER-32 (JSR corporation) B2 Acrylic rubber: Vamac ultra IP (Dupont) C Soluble polyimide Soluble polyimide of Preparation Example 1 D inorganic filler A mixture of H42M (Showa Denkko) and SG-95 (Nopon talc) (50:50 weight ratio) E hardener DDS (Huntsman) F leveling agent F-477, DIC Korea Co., Ltd. G dispersant A-187, Momentive H catalyst 2E4MZ, Shikoku

[ comparative example 2]

As Comparative Example 2, Doosan Corporation's DFF-200 was used.

[ Experimental example 2] - Evaluation of physical properties

The physical properties of the coverlay films prepared in Examples 1 to 5 and Comparative Example 1 were evaluated as follows, and the results are shown in Table 5 and FIG. 4 below.

(1) Resin flowability

After laminating one Sus plate (12cmx12cm) on two blue pads (13cmx13cm), 1 oz copper foil (4cmx4cm) was placed on the center of the Sus plate. On the other hand, the coverlay film is sampled in a size of 2.5cmx2.5cm, and then an X is marked on the back side of the coverlay sample with a pen, and then punched with a punch so that the center of the X is visible to form a punching part. Then, the coverlay sample (the release substrate was removed) was placed on the central portion of the copper foil, followed by a PET film (12cmx12cm), an Al plate (4cmx4cm) and two blue pads (4cmx4). cm) were sequentially arranged to obtain a laminate. After the laminate was pressed for 3 minutes at a temperature of 130 ° C and a pressure of 570 lb, R ₂₁ , R ₂₂ , L ₂₁ , L ₂₂ , L ₂₃ , and L ₂₄ were measured using an optical microscope, respectively (Fig. 3), the resin flowability was calculated according to Equation 2 below.

[Equation 2]

(In Equation 2 above,

R ₂₁ is the radius of the punched portion formed on the coverlay film,

R ₂₂ is the radius of the copper foil portion where the melt of the adhesive layer does not flow in the copper foil region corresponding to the punching portion after the press;

L ₂₁ , L ₂₂ , L ₂₃ and L ₂₄ are lengths through which the melt of the adhesive layer flows in the 12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock directions of the punching part, respectively).

(2) MIT flexural properties

SUS plate (thickness: 1.2 mm) / 5 sheets of Kraft Paper (thickness: 0.28 mm) / Al plate (thickness: 0.8 mm) / release PET film (thickness: 25 μm) / FCCL / coverlay film / release PET film (thickness: 0.28 mm) : 25 μm)/PVC film (thickness: 0.25 mm)/Al plate (thickness: 0.8 mm)/5 sheets of Kraft Paper (each thickness: 0.28 mm)/SUS plate (thickness: 1.2 mm) , by pressing for 1 hour at a temperature of 150 °C and a pressure of 25 kgf/cm 2 to obtain a sample in which the coverlay was laminated on the copper pattern of FCCL. Thereafter, the folding cycle of the sample was measured using an MIT measuring instrument (TOYOSEIKI, MIT-SA) under the following conditions. The FCCL used above had a copper pattern (thickness: 12 µm, Line/Space: 1000/1000 µm) formed on polyimide (thickness: 18 µm).

i) Load: 0.5 kg

ii) Bending speed: 175 cpm

iii) bending angle: 135°

iv) Line/Space: 1000/1000 μm

(3) Solder Floating (S/F)

SUS plate (thickness: 1.2 mm)/4 blue pad/Al plate (thickness: 1 mm)/release PET film/PVC film/release PET film/FCCL/coverlay film/release PET film/PVC film/release PET film / FCCL/Coverlay Film/Release PET Film/PVC Film/Release PET Film/ FCCL/Coverlay Film/Release PET Film/PVC Film/Release PET Film/FCCL/Coverlay Film/Release PET Film/PVC Film/Release PET After laminating in the order of film/Al plate (thickness: 1 mm)/4 sheets of blue pad/SUS plate (thickness: 1.2 mm), hot-pressed for 60 minutes under a temperature of 150 °C and a pressure of 40 kgf/100cm2. A sample in which a coverlay was laminated on the copper pattern of FCCL was obtained. Thereafter, the sample was floated in a solder bath (lead-free 63%) at 300° C. for 5 minutes, and then the appearance of the sample was visually checked. The FCCL used above had a copper pattern (thickness: 12 µm, Line/Space: 1000/1000 µm) formed on polyimide (thickness: 18 µm). Here, the abnormal appearance means that a change in the thickness of the sample, bubbles, blisters, delamination, or the like occurred. At this time, if thickness change, bubbles, blisters, or delamination occurred in the appearance of the sample, 'Fail' was indicated, and if thickness change, bubbles, blisters, or delamination did not occur, it was indicated as 'Pass'.

(4) Adhesion at high temperature

Sus Plate (thickness: 1.2 mm)/4 sheets of blue pad/Sus plate (thickness: 1.2 mm)/release PET film/PVC film/release PET film/FCCL/coverlay film/release PET film/PVC film/Sus plate( Thickness: 1.2 mm)/Release PET Film/PVC Film/ Release PET Film/FCCL/Coverlay Film/Release PET Film/PVC Film/Sus plate(Thickness: 1.2 mm)/4 Blue Pad/ Sus Plate(Thickness: 1.2 mm), and then hot-pressed for 60 minutes under a temperature of 150° C. and a pressure of 40 kgf/cm 2 to obtain a sample in which the coverlay was laminated on the copper pattern of FCCL. The FCCL used above had a copper pattern (thickness: 12 µm, Line/Space: 1000/1000 µm) formed on polyimide (thickness: 18 µm). After that, the sample was cut to a certain size (length in TD direction: 0.5 cm, length in MD direction: 12 cm), and then the cut sample was used on both sides of a prepreg for peel strength test (size: 3 cm × 10 cm) It was attached so that the copper foil surface of the sample was in contact on the tape. Then, after peeling off only about 30 mm of the coverlay film from the end of the sample, the 90-degree adhesive force of the sample is measured three or more times using UTM (Instron, model name: 5942), at which time the sample is peeled off by about 2 cm. The adhesive force at the time was measured, and the average value of these was expressed as adhesive force. In addition, after the pedestal-sample laminate was left under a high temperature of 158° C. for 2,000 hours, the 90-degree adhesive force of each sample was measured every 1,000 hours as described above. In this case, the coverlay film of Comparative Example 2 was used as a control.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Resin flowability (%) 25 35 45 15 10 40 MIT Flexural Characteristics (times) 1,300 1,400 1,000 1,500 1,400 1,200 Soldering heat resistance (300℃, 10 minutes) Pass Pass Pass Pass Pass Pass adhesion
(kgf/cm2) 0 h 1.5 1.6 1.7 1.2 1.6 1.5 1,000 h 1.4 1.5 1.4 1.2 1.4 1.2 2,000 h 1.2 1.4 1.1 1.1 1.0 0.6

As can be seen from Table 5, the coverlay films of Examples 1 to 5 were excellent in resin flowability, bending resistance, and heat resistance, like the coverlay film of Comparative Example 1.

In addition, the coverlay films of Examples 1 to 5 had an initial adhesive strength as high as 1.2 kgf/cm 2 or more, similarly to the coverlay film of Comparative Example 1. However, unlike Comparative Example 1, the coverlay films of Examples 1 to 5 had adhesive strength of about 1.0 kgf/cm 2 or more, even when left for 2,000 hours under high temperature conditions. On the other hand, when the coverlay film of Comparative Example 1 was left at a high temperature for 2,000 hours, the adhesive strength was lowered to 0.6 kgf/cm 2 . As shown in FIG. 4, even when the coverlay films of Examples 1 to 5 were left under a high temperature for 2,000 hours, the excellent adhesive strength gradually decreased, and as a result, the adhesive strength retention rate was about 60% at 2,000 hours. or more, and in particular, Examples 1, 2, and 4 were 80% or more. On the other hand, the coverlay film of Comparative Example 1 had a sharp decrease in adhesive force, and as a result, the adhesive force retention rate was 40% at 2,000 hours (see FIG. 4 ). On the other hand, as in Comparative Example 1, the coverlay film of Comparative Example 2 had a sharp decrease in adhesion when left at a high temperature for a long time, and the adhesion was about 0 kgf/cm 2 at 1,500 hours (see FIG. 4 ).

[ Experimental example 3] - coverlay of film fillability

The filling properties of the coverlay films of Example 2 and Comparative Example 1 were tested as follows, and the results are shown in FIG. 5 .

A sample was obtained by laminating a coverlay film on the copper pattern of FCCL. In this case, the FCCL used was one in which a copper pattern (thickness: 12 µm, Line/Space: 1000/1000 µm) was formed on polyimide (thickness: 18 µm). Thereafter, the sample was left at a temperature of 300° C. for 30 minutes to observe whether carbides were formed.

As can be seen from FIG. 5 , in the coverlay film of Example 2, carbonization did not occur in the step portion with the copper pattern of FCCL. On the other hand, in the coverlay film of Comparative Example 1, voids grew on the step portion with the copper pattern of FCCL after 10 seconds, and carbonization occurred on the portion with the step difference with the copper pattern of FCCL after 30 minutes passed.

As described above, even if the coverlay film according to the present invention is stored at a high temperature for a long time, since voids and carbides are not formed in the step portion with the pattern of the printed circuit board, it can be estimated that the fillability is excellent.

10A, 10B: coverlay film, 11: substrate,
12: adhesive layer, 13: release substrate,
14: surface protection substrate

Claims (17)

(a) a bifunctional or more functional epoxy resin;
(b) a rubber-based binder containing acrylonitrile-butadiene rubber and acrylic rubber;
(c) soluble polyimides; and
(d) inorganic fillers
Adhesive composition comprising a. According to claim 1,
The soluble polyimide has a resin flow (R/F) in the range of 10 to 25%, the adhesive composition. 3. The method of claim 2,
The soluble polyimide is obtained by polymerizing diamine and acid dianhydride in a molar ratio of 1.015 to 1.03: 1, the adhesive composition. 3. The method of claim 2,
The soluble polyimide satisfies at least one of the physical properties of (i) to (v), the adhesive composition:
(i) more than 1,000 flexion times;
(ii) a tensile strength of at least 80 MPa;
(iii) a Young's modulus of at least 2,500 MPa;
(iv) an elongation of at least 5%; and
(v) Adhesive force of 1.2 kgf/cm or more. According to claim 1,
wherein the epoxy resin has an epoxy equivalent weight (EEW) in the range of 100 to 500 g/eq. According to claim 1,
The epoxy resin, the acrylonitrile-butadiene rubber, and the soluble polyimide are 2 to 6: 0.5 to 3: 1 to be included in a weight ratio, the adhesive composition. According to claim 1,
The ratio of the total content (W _a +W _c ) of the epoxy resin and the rubber-based binder to the content (W _b ) of the soluble polyimide [(W _a +W _c )/W _b ] is in the range of 5 to 12 , adhesive composition. 8. The method of claim 7,
The epoxy resin and the rubber-based binder are 1: 1 to 3 weight ratio, the adhesive composition. 9. The method of claim 8,
The acrylonitrile-butadiene rubber and the acrylic rubber are included in a weight ratio of 1: 1.5 to 7, the adhesive composition. According to claim 1,
Based on 100 parts by weight of the total amount of the adhesive composition,
15 to 25 parts by weight of an epoxy resin,
30 to 40 parts by weight of a rubber-based binder,
5 to 10 parts by weight of a soluble polyimide, and
15 to 30 parts by weight of inorganic filler
Containing, the adhesive composition. According to claim 1,
After the cured product of the adhesive composition is left at a temperature of 158 ° C. for 2,000 hours, the adhesive strength retention rate is 60% or more, the adhesive composition: According to claim 1,
After the cured product of the adhesive composition is left at a temperature of 158° C. for 2,000 hours, the adhesive strength to the adherend measured at 25° C. is 1.0 kgf/cm or more, the adhesive composition. According to claim 1,
After the cured product of the adhesive composition is left at a temperature of 300° C. for 10 seconds, the void ratio per unit area (3 cm×15 cm) to the adherend is 0%. According to claim 1,
After the cured product of the adhesive composition is left at a temperature of 300° C. for 30 minutes, the carbonization rate per unit area (3 cm×15 cm) of the adherend is 0%. According to claim 1,
The cured product of the adhesive composition satisfies at least one of the following (i) and (ii) physical properties, the adhesive composition:
(i) 30 to 40% resin flowability; and
(ii) The number of flexures greater than or equal to 1,200 as measured according to the MIT flexural resistance test. base substrate;
An adhesive layer disposed on one surface of the base substrate and formed of the adhesive composition according to any one of claims 1 to 15; and
The release substrate disposed on the adhesive layer
A coverlay film comprising a. substrate body; and
It is disposed on at least one surface of the substrate, the coverlay film according to claim 16
A printed circuit board comprising a.

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