Low dielectric adhesive composition and flexible metal laminate using same

Abstract

The present invention relates to a low dielectric adhesive composition and a flexible metal laminate using same. The low dielectric adhesive composition is a polyolefin-based adhesive composition containing, as a main component, a polyolefin resin that has a dielectric constant of 2.5 or less at 15 GHz, and containing a multifunctional epoxy resin and an acid anhydride in specific content ranges. The low dielectric adhesive composition according to the present invention not only has high adhesion and excellent soldering resistance even when used to bond a low-illuminance metal layer to an insulating layer, but can also even reduce dielectric loss at 10 GHz or higher and thus exhibits low dielectric properties.

Description

Low-k adhesive composition and flexible metal laminate using the same

[0001] The present invention relates to a low-k adhesive composition and a flexible metal laminate using the same.

[0002] The communications and automotive markets are currently transitioning from 4G to 5G, demanding higher performance in various components. For 5G, the frequency required for communications applications ranges from 3.5 GHz for 4G to 28 GHz for 5G and up to 70 GHz for automotive applications. Consequently, low dielectric properties are required.

[0003] Flexible metal laminates are primarily used as substrates for flexible printed circuit boards (FPCBs), and are also used in surface heating elements, electromagnetic shielding materials, flat cables, and packaging materials. These flexible metal laminates mainly include an insulating layer composed of a polyimide film and a metal layer composed of copper foil. Depending on whether an adhesive layer exists between the insulating layer and the metal layer, they can be divided into adhesive and non-adhesive types.

[0004] Korean Patent Publication No. 10-2013-0027442 discloses a flexible metal laminate comprising: a first metal layer; a first polyimide layer; a polyimide layer formed on the first polyimide layer, in which a fluororesin is dispersed; and a second polyimide layer formed on the polyimide layer in which the fluororesin is dispersed, wherein in the polyimide layer in which the fluororesin is dispersed, the content per unit volume of the fluororesin is greater at a depth of 40 to 60% of the total thickness from the surface of the polyimide layer than at a depth of 5 to 10% of the total thickness, thereby improving adhesion to the metal layer and dielectric properties. However, polyimide has a problem in that it is difficult to satisfy the recently demanded high-speed level due to its own high permittivity.

[0005] In particular, in the high frequency range of 10 GHz or more, the soft metal laminate has the effect of improving the dielectric properties after laminating the insulating layer as the roughness of the metal layer is lowered, but it has the problem of difficult to secure adhesion between the metal layer and the insulating layer and low soldering resistance.

[0006] Therefore, there is a need to develop a method that can further reduce the dielectric constant and dielectric loss factor in the high frequency range of 10 GHz or higher even when using the polyimide insulator that has been used previously, and can also increase the adhesion with the insulating layer and improve soldering resistance even when the roughness of the metal layer is low.

[0007] One object of the present invention is to provide a low-k adhesive composition that exhibits low-k properties by not only having high adhesion and excellent soldering resistance when used to bond a low-luminance metal layer to an insulating layer, but also reducing dielectric loss even at frequencies exceeding 10 GHz.

[0008] Another object of the present invention is to provide a flexible metal laminate using the low-k adhesive composition.

[0009] On the one hand, the present invention includes a polyolefin resin having a dielectric constant of 2.5 or less at 15 GHz, a multifunctional epoxy resin, and an acid anhydride,

[0010] The above multifunctional epoxy resin is included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polyolefin resin,

[0011] The above acid anhydride provides a low-k adhesive composition in which the acid anhydride is included in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of polyolefin resin.

[0012]

[0013] According to one embodiment of the present invention, the low-k adhesive composition may have a dielectric loss tangent (Df) of 0.005 or less at 15 GHz of the adhesive layer after curing.

[0014] A low-k adhesive composition according to one embodiment of the present invention may be used to bond a metal layer having a 10-point average roughness (Rz) of 0.7 ㎛ or less to an insulating layer.

[0015] In one embodiment of the present invention, the multifunctional epoxy resin may have an epoxy resin equivalent of 250 g / eq or less.

[0016] In one embodiment of the present invention, the multifunctional epoxy resin may be at least one selected from the group consisting of an amino phenol type epoxy compound, a phenol novolac type epoxy compound, a bisphenol A novolac type epoxy compound, N,N'-tetraglycidyl diaminodiphenylmethane (TGDDM), and tetraphenolethane tetraglycidyl ether (TPETGE).

[0017] In one embodiment of the present invention, the acid anhydride may be at least one selected from the group consisting of succinic anhydride, phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, 3-methyl-hexahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyl-tetrahydrophthalic anhydride, nadic anhydride, methylnadic anhydride, norbornane-2,3-dicarboxylic anhydride, methylnorbornane-2,3-dicarboxylic anhydride, methylcyclohexene dicarboxylic anhydride, 3-dodecenyl succinic anhydride, and octenylsuccinic anhydride.

[0018]

[0019] On the other hand, the present invention

[0020] A flexible metal laminate comprising an insulating layer, an adhesive layer formed on at least one surface of the insulating layer, and a metal layer formed on the adhesive layer,

[0021] A flexible metal laminate is provided in which the adhesive layer is formed from the low-k adhesive composition.

[0022]

[0023] In one embodiment of the present invention, the insulating layer may be a polyimide film.

[0024] In one embodiment of the present invention, the metal layer may be copper foil.

[0025] In one embodiment of the present invention, the metal layer may have a 10-point average roughness (Rz) of 0.7 μm or less.

[0026] The low-k adhesive composition according to the present invention exhibits low-k characteristics by not only having high adhesion and excellent soldering resistance when used to bond a low-luminance metal layer to an insulating layer, but also reducing dielectric loss even at 10 GHz or higher.

[0027] FIG. 1 illustrates a flexible metal laminate according to one embodiment of the present invention.

[0028] Hereinafter, the present invention will be described in more detail.

[0029]

[0030] One embodiment of the present invention comprises a polyolefin resin having a dielectric constant of 2.5 or less at 15 GHz, a multifunctional epoxy resin, and an acid anhydride,

[0031] The above multifunctional epoxy resin is included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polyolefin resin,

[0032] The above acid anhydride relates to a low-k adhesive composition in which the acid anhydride is included in an amount of 0.1 to 5 parts by weight per 100 parts by weight of polyolefin resin.

[0033]

[0034] A low-k adhesive composition according to one embodiment of the present invention is a polyolefin-based adhesive composition containing a polyolefin resin as a main component, and including a polyolefin resin having a dielectric constant of 2.5 or less at 15 GHz as the polyolefin resin, and including a multifunctional epoxy resin and an acid anhydride in a specific content range, so that even when used to bond a low-luminance metal layer to an insulating layer, the composition exhibits high adhesion and excellent soldering resistance, and can reduce dielectric loss even at 10 GHz or higher, thereby exhibiting low-k characteristics.

[0035]

[0036] According to one embodiment of the present invention, the low-k adhesive composition may have a dielectric constant (Dk) of the adhesive layer at 15 GHz after curing of 3.0 or less, for example, greater than 1 and 3.0 or less, preferably less than 3.0.

[0037] The above dielectric constant is a physical unit that represents the effect of the medium between charges on the electric field when an electric field acts between the charges, and can also be viewed as the amount of charge that the medium can store.

[0038] The dielectric constant (Dk) at 15 GHz of the adhesive layer after curing is a value measured at a frequency of 15 GHz according to the method described in the experimental example described below for a sample in which the adhesive layer is formed after curing.

[0039] If the dielectric constant (Dk) of the adhesive layer at 15 GHz after the above-mentioned curing is outside the above range, transmission loss may increase in a high-frequency band such as 15 GHz, and electrical interference may not be minimized when applying highly integrated or highly miniaturized devices.

[0040]

[0041] According to one embodiment of the present invention, the low-k adhesive composition may have a dielectric loss factor (Df) of the adhesive layer at 15 GHz after curing of 0.005 or less, for example, greater than 0 and 0.005 or less, preferably less than 0.005.

[0042] The above dielectric tangent is a unit that represents the ratio of power loss that occurs when an AC voltage is applied to a dielectric, and is generally expressed as tangent delta (tangent δ).

[0043] The dielectric constant (Df) at 15 GHz of the adhesive layer after curing is a value measured at a frequency of 15 GHz according to the method described in the experimental example described below for a sample on which the adhesive layer is formed after curing.

[0044] If the dielectric loss factor (Df) of the adhesive layer at 15 GHz after the above-mentioned curing is outside the above range, transmission loss may increase in a high-frequency band such as 15 GHz, and electrical interference may not be minimized when applying highly integrated or highly miniaturized devices.

[0045]

[0046] The low-k adhesive composition according to one embodiment of the present invention may be used to bond a low-roughness metal layer having a 10-point average roughness (Rz) of 0.7 µm or less, for example, 0.1 µm to 0.7 µm, to an insulating layer.

[0047] The above ten-point average roughness (ten point height of irregularities, Rz) is the sum of the average value (absolute value) of the heights of the five highest peaks and the average value (absolute value) of the depths of the five deepest valleys in the cross-sectional curve within the reference length.

[0048]

[0049] In one embodiment of the present invention, the polyolefin resin is a main component of the adhesive composition, and is a polymer having a hydrocarbon backbone as a main component, such as a homopolymer or copolymer of an olefin monomer, a copolymer of an olefin monomer and another monomer, or a hydride or halide of these polymers.

[0050] Examples of the above olefin monomers include ethylene, propylene, butene, butadiene, octene, isoprene, etc., and examples of the above other monomers include styrene, etc.

[0051] Additionally, the copolymer may be a binary copolymer, a terpolymer or a tetrapolymer.

[0052] For example, the polyolefin resin may be one or more types of (modified) polypropylene resin, (modified) polyethylene resin, cycloolefin polymer, polyterpene resin, rosin resin, aliphatic petroleum resin, alicyclic petroleum resin, copolymerized petroleum resin, hydrogenated petroleum resin, etc.

[0053]

[0054] As described above, the polyolefin resin has a dielectric constant at 15 GHz of 2.5 or less, for example, 2.0 to 2.5.

[0055] The dielectric constant of the above polyolefin resin at 15 GHz is a value measured according to ASTM D150 at a frequency of 15 GHz.

[0056] If the dielectric constant of the above polyolefin resin at 15 GHz exceeds 2.5, the dielectric constant of the adhesive composition may increase, and the transmission loss of radio waves may increase.

[0057]

[0058] In one embodiment of the present invention, the multifunctional epoxy resin refers to a compound having two or more epoxy groups in a molecule, and serves to improve adhesion and heat resistance by increasing crosslinking density and adhesive cohesion.

[0059] In terms of suppressing an increase in dielectric constant, the above multifunctional epoxy resin preferably has three, four or more epoxy groups in the molecule.

[0060] The above multifunctional epoxy resin may have an epoxy resin equivalent of 250 g / eq or less in order to secure a low dielectric constant. The lower the epoxy resin equivalent, the better the dielectric properties as fewer epoxy groups are contained.

[0061] More specifically, the epoxy resin equivalent of the multifunctional epoxy resin may be 240 g / eq or less, 230 g / eq or less, 220 g / eq or less, 210 g / eq or less, 200 g / eq or less, 190 g / eq or less, 180 g / eq or less, 170 g / eq or less, 160 g / eq or less, 150 g / eq or less, 140 g / eq or less, 130 g / eq or less, 120 g / eq or less, 110 g / eq or less, 100 g / eq or less, 90 g / eq or less, 80 g / eq or less, 70 g / eq or less, or 60 g / eq or less. In addition, the epoxy resin equivalent of the above multifunctional epoxy resin may be 50 g / eq or more, 60 g / eq or more, 70 g / eq or more, 80 g / eq or more, 90 g / eq or more, 100 g / eq or more, 110 g / eq or more, 120 g / eq or more, 130 g / eq or more, 140 g / eq or more, 150 g / eq or more, 160 g / eq or more, 170 g / eq or more, 180 g / eq or more, 190 g / eq or more, 200 g / eq or more, 210 g / eq or more, 220 g / eq or more, or 230 g / eq or more.

[0062] As the above multifunctional epoxy resin, aminophenol type epoxy compound, phenol novolac type epoxy compound, bisphenol A novolac type epoxy compound, N,N'-tetraglycidyl diaminodiphenylmethane (TGDDM), tetraphenolethane tetraglycidyl ether (TPETGE), etc. can be preferably used. These can be used alone or in combination of two or more.

[0063]

[0064] The above multifunctional epoxy resin is included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polyolefin resin as described above.

[0065] If the above multifunctional epoxy resin is included in an amount of less than 1 part by weight based on 100 parts by weight of polyolefin resin, the crosslinking density and adhesive cohesion may be weakened, resulting in reduced adhesion and reduced heat resistance. If it is included in an amount exceeding 10 parts by weight, the dielectric constant and dielectric loss tangent of the adhesive composition may increase.

[0066]

[0067] In one embodiment of the present invention, the acid anhydride is a component that improves dielectric properties while also increasing adhesion, and is a compound having one or more acid anhydride groups in the molecule.

[0068] Examples of the above acid anhydrides include succinic anhydride, phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, 3-methyl-hexahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyl-tetrahydrophthalic anhydride, nadic anhydride, methylnadic anhydride, norbornane-2,3-dicarboxylic anhydride, methylnorbornane-2,3-dicarboxylic anhydride, methylcyclohexene dicarboxylic anhydride, 3-dodecenyl succinic anhydride, octenyl succinic anhydride, etc., and these may be used alone or in combination of two or more.

[0069]

[0070] The above acid anhydride is included in an amount of 0.1 to 5 parts by weight per 100 parts by weight of polyolefin resin.

[0071] If the above acid anhydride is included in an amount of less than 0.1 parts by weight based on 100 parts by weight of polyolefin resin, the dielectric constant may increase because not all hydroxyl groups generated in the multifunctional epoxy resin are removed, and if it is included in an amount exceeding 5 parts by weight, the adhesive strength may decrease due to an increase in crosslinking density.

[0072]

[0073] The low-k adhesive composition according to one embodiment of the present invention may further include a solvent.

[0074] The above solvent is not particularly limited as long as it dissolves the components in the adhesive composition. For example, the solvent may be an aromatic hydrocarbon such as benzene, toluene, xylene, etc., an aliphatic hydrocarbon such as hexane, heptane, octane, decane, etc., an alicyclic hydrocarbon such as cyclohexane, cyclohexene, methylcyclohexane, ethylcyclohexane, etc., a halogenated hydrocarbon such as trichloroethylene, dichloroethylene, chlorobenzene, chloroform, etc., an alcohol solvent such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, phenol, etc., a ketone solvent such as acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanone, hexanone, cyclohexanone, isophorone, acetophenone, a cellosolve such as methyl cellosolve, ethyl cellosolve, a methyl acetate, ethyl acetate, butyl acetate, methyl propionate, butyl formate, etc. Ester solvents, ethylene glycol mono-n-butyl ether, ethylene glycol mono-iso-butyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-iso-butyl ether, triethylene glycol mono-n-butyl ether, tetraethylene glycol mono-n-butyl ether, and other glycol ether solvents can be used, and one or two or more of these can be used in combination.

[0075] The above solvent is preferably a mixed solvent of an alicyclic hydrocarbon and a ketone solvent, and among them, it is preferable to use cyclohexane or methylcyclohexane as the alicyclic hydrocarbon and methyl isobutyl ketone or methyl ethyl ketone as the ketone solvent.

[0076]

[0077] The above solvent may be included in an amount of 100 to 2,000 parts by weight, preferably 200 to 1,000 parts by weight, and more preferably 300 to 900 parts by weight, based on 100 parts by weight of the polyolefin resin.

[0078] If the above solvent is included in an amount below the above range, the solution state or pot life may deteriorate, and if it is included in an amount exceeding the above range, it may be disadvantageous in terms of manufacturing cost or transportation cost.

[0079]

[0080] One embodiment of the present invention is a flexible metal laminate comprising an insulating layer, an adhesive layer formed on at least one surface of the insulating layer, and a metal layer formed on the adhesive layer,

[0081] The present invention relates to a flexible metal laminate in which the adhesive layer is formed from the low-k adhesive composition described above.

[0082]

[0083] FIG. 1 is a schematic cross-sectional view of a flexible metal laminate according to one embodiment of the present invention.

[0084] Referring to FIG. 1, a flexible metal laminate according to one embodiment of the present invention has a structure in which a first adhesive layer (120) and a second adhesive layer (130) formed on both sides of an insulating layer (110) and a first metal layer (140) and a second metal layer (150) formed on the first adhesive layer (120) and the second adhesive layer (130), respectively, are laminated. FIG. 1 illustrates a structure in which an adhesive layer and a metal layer are laminated on both sides of an insulating layer (110), but the adhesive layer and the metal layer may be laminated on only one side of the insulating layer (110).

[0085]

[0086] In one embodiment of the present invention, the insulating layer (110) may be a polyimide film, a liquid crystal polymer film, a polyphenylene sulfide film, or the like, and in particular may be a polyimide film.

[0087] The polyimide film may have a dielectric constant at 15 GHz of 4.0 or less, preferably 3.3 or less, more preferably 3.0 or less, for example, 2.5 to 4.0, 2.5 to 3.3, 2.5 to 3.0, 3.0 to 3.3, or 3.0 to 4.0.

[0088] The above polyimide film may have a dielectric constant at 15 GHz of 0.015 or less, preferably 0.01 or less, or 0.005 or less, for example, 0.002 to 0.015, 0.002 to 0.01, 0.002 to 0.005, or 0.003 to 0.015.

[0089] In the present invention, since the insulating layer is bonded to a low-roughness metal layer having a 10-point average roughness (Rz) of 0.7 ㎛ or less using the low-k adhesive composition described above, it is possible to secure low-k characteristics of the entire flexible metal laminate even if a general-purpose polyimide film having a dielectric constant of 2.5 or more or a dielectric tangent of 0.002 or more at 15 GHz is used instead of an expensive low-k polyimide film having a dielectric constant of less than 2.5 or a dielectric tangent of less than 0.002 at 15 GHz.

[0090] The above polyimide may be a thermosetting polyimide produced by a dehydration condensation reaction upon heating of polyamic acid, or a solvent-soluble polyimide that is a non-dehydration condensation type.

[0091] The above thermosetting polyimide can be obtained by synthesizing polyamic acid, which is an imide precursor, by reacting diamine and tetracarboxylic dianhydride in a polar solvent, and then thermally dehydrating and cyclizing the polyamic acid, i.e., imidizing it.

[0092] As the above diamine, aromatic diamine, alicyclic diamine, aliphatic diamine, etc., which are commonly used in polyimide synthesis, can be used. These diamines can be used alone or in a mixture of two or more types.

[0093] The above tetracarboxylic dianhydride may include aromatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, aliphatic tetracarboxylic dianhydride, etc. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

[0094] When manufacturing a polyimide film using the above-mentioned thermosetting polyimide, a composition containing polyamic acid is applied to a substrate to form a film, which is then dried and heat-treated to imidize the film, thereby manufacturing the polyimide film. At this time, the coating method may be a spray method, a roll coating method, a rotary coating method, a bar coating method, an inkjet method, a screen printing method, a slit coating method, or the like. The drying may be performed at a temperature of 140°C or lower, and the heat treatment may be performed at a temperature of 200 to 600°C.

[0095] The above solvent-soluble polyimide is completely imidized and is soluble in a solvent, so it can be prepared in the form of a coating solution dissolved in a solvent, applied to a substrate, and then dried to form a film. The coating method can be a spray method, a roll coating method, a rotary coating method, a bar coating method, an inkjet method, a screen printing method, a slit coating method, etc. The drying can be performed at a temperature below 200°C.

[0096]

[0097] In one embodiment of the present invention, the insulating layer (110) may have a single-layer or multi-layer structure.

[0098] The thickness of the above insulating layer (110) may be 5 to 100 μm, preferably 5 to 75 μm, and more preferably 8 to 50 μm. If the thickness of the above insulating layer is less than the above range, a problem may arise in which the transmission loss rate in the high-frequency region increases somewhat, and if it exceeds the above range, a problem may arise in which it is somewhat difficult to make the product thinner.

[0099]

[0100] The first adhesive layer (120) and the second adhesive layer (130) are each independently formed from the low-k adhesive composition described above.

[0101] The thickness of the first adhesive layer (120) and the second adhesive layer (130) may each independently be 3 to 30 μm, preferably 6 to 15 μm. If the thickness of the first adhesive layer (120) and the second adhesive layer (130) is less than 3 μm, the adhesion between the insulating layer and the metal layer may be insufficient after the flexible circuit board is manufactured, and if it exceeds 30 μm, the heat resistance of the flexible circuit board may be reduced.

[0102]

[0103] In one embodiment of the present invention, the first metal layer (140) and the second metal layer (150) may each be independently a thin film of one or more metals or alloys selected from the group consisting of copper, iron, nickel, titanium, aluminum, silver, and gold, and may preferably be a copper thin film, i.e., a copper foil layer, having excellent electrical conductivity and being inexpensive, but is not limited thereto. The copper foil layer may be a layer formed by electrolysis or a layer formed by rolling.

[0104] In addition, it is preferable that the first metal layer (140) and the second metal layer (150) are each independently subjected to various surface treatments (such as roughening and rust prevention). Examples of the rust prevention treatment include plating treatment using a plating solution containing Ni, Zn, Sn, etc., and so-called hardening treatment such as chromate treatment.

[0105] The first metal layer (140) and the second metal layer (150) may each independently have a 10-point average roughness (Rz) of 0.7 ㎛ or less, for example, 0.1 ㎛ to 0.7 ㎛. If the 10-point average roughness (Rz) of the first metal layer (140) and the second metal layer (150) exceeds 0.7 ㎛, the dielectric properties may deteriorate.

[0106]

[0107] The thickness of the first metal layer (140) and the second metal layer (150) is not particularly limited in the present invention, but may, for example, independently have a thickness of 1 to 100 μm, preferably 2 to 38 μm. If the thickness of the metal layers is less than the above-mentioned range, a heat generation problem may occur in the flexible metal laminate including them, and if it exceeds the above-mentioned range, a problem may occur in which the flexibility of the flexible metal laminate including them is somewhat reduced.

[0108]

[0109] The above flexible metal laminate can be used in the manufacture of printed wiring boards.

[0110] The above printed wiring board can be manufactured by forming a circuit pattern on at least one metal layer of the laminate through etching or the like.

[0111] The above printed wiring board may be a flexible printed wiring board.

[0112]

[0113] Hereinafter, the present invention will be described in more detail through examples, comparative examples, and experimental examples. These examples, comparative examples, and experimental examples are intended solely to illustrate the present invention, and it will be apparent to those skilled in the art that the scope of the present invention is not limited thereto.

[0114]

[0115] Examples and Comparative Examples: Preparation of Low-K Adhesive Compositions

[0116] A low-k adhesive composition was prepared by mixing the compositions shown in Tables 1 and 2 below (parts by weight).

[0117]

[0118] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Polyolefin resin A-1 100 100 100 100 100 A-2 100 100 100 100 A-3 100 A-4 100 Multifunctional epoxy resin B-16.5 6.5 6.5 6.5 6.5 29 6.5 6.5 6.5 B-26.5 Acid anhydride C-12.6 2.6 2.6 2.6 2.6 2.6 2.6 0.5 4 C-22.6 Solvent D-1 3 27 327 327 327 327 327 335 327 321 332

[0119]

[0120] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Polyolefin resin A-1 100 100 100 100 100 A-2 A-3 A-4 Epoxy B-16.5 15 6.5 B-2 Acid anhydride C-12.6 2.6 6.5 C-2 Solvent D-1 3 2 7 3 2 7 3 2 7 3 2 7 3 4 7 3 2 7

[0121]

[0122] A-1: GMP3020E, Sungwon Materials (Dk: 2.3, Df: 0.001)

[0123] A-2: LIS-9447-KR, Toyo Morton (Dk: 2.1, Df: 0.001)

[0124] A-3: Poly-Pale, Eastman (Dk: 2.3, Df: 0.003)

[0125] A-4: Kristalex F85, Eastman (Dk: 2.2, Df: 0.003)

[0126] B-1: PA805, Kukdo Chemical (epoxy equivalent: 110 g / eq)

[0127] B-2: VG3101L, Printec (epoxy equivalent: 215 g / eq)

[0128] C-1: Maleic anhydride

[0129] C-2: Phthalic anhydride

[0130] D-1: Mixed solvent of methylcyclohexane and methyl ethyl ketone (MEK) (1:1, v / v)

[0131]

[0132] Experimental Example 1:

[0133] The dielectric properties, adhesion, and soldering resistance of the adhesive compositions manufactured in the examples and comparative examples were evaluated by the following methods, and the results are shown in Tables 3 and 4 below.

[0134]

[0135] (1) Genetic characteristics

[0136] An adhesive composition was coated on a PET release film to a thickness of 50 ㎛ after curing, and after drying, another PET release film was bonded on top, and cured at 120°C for 1 day to produce an adhesive layer.

[0137] A release film was peeled from the adhesive layer, only the adhesive layer was taken, and a specimen was made by cutting it into a size of 30 mm × 50 mm. Then, the specimen was measured using the SPDR method using Keysight Network Analyzer equipment to measure the dielectric constant and dissipation factor values ​​at a frequency of 15 GHz.

[0138] When the dielectric constant and dielectric loss tangent are high, the signal loss rate increases in the high frequency region, so a dielectric constant of 3.5 and a dielectric loss tangent of 0.005 or less are recommended.

[0139]

[0140] (2) Adhesion

[0141] An adhesive composition was coated on a polyimide film having a thickness of 38 ㎛ to a thickness of 6 ㎛ after curing, dried at 100°C for 2 minutes, and then bonded to a copper foil (Rz: 0.5 ㎛, thickness 12 ㎛) to produce a laminate.

[0142] The laminate thus produced was left at 120°C for one day, then cut into 10 mm wide pieces to produce specimens, and the adhesion of the specimens was measured using a 90° peel strength tester under the conditions of a peel angle of 90° and a peel speed of 50 mm / min.

[0143] The higher the adhesion, the better the mechanical properties of the flexible metal laminate.

[0144] If the adhesion is less than 1.0 N / 10mm, the bonding strength between the copper foil and the insulating layer is low, which may cause peeling during soldering or hole drilling.

[0145]

[0146] (3) Soldering resistance

[0147] An adhesive composition was coated on a polyimide film having a thickness of 38 ㎛ to a thickness of 6 ㎛ after curing, and after drying at 100°C for 2 minutes, a laminate was produced by bonding it to a copper foil (Rz: 0.5 ㎛, thickness 12 ㎛).

[0148] The laminate thus formed was left at 120°C for one day, and then a sample of a certain size was taken and placed in a 300°C soldering bath to determine whether it could withstand 10 seconds. Soldering resistance was evaluated according to the following evaluation criteria.

[0149] <Evaluation Criteria>

[0150] ○: Endure

[0151] ×: Unable to bear

[0152]

[0153] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Dielectric constant 2.6 2.5 2.6 2.6 2.7 2.5 2.7 2.7 2.7 2.5 Dielectric tangent 0.00 30.00 20.00 30.00 20.00 40.00 10.00 40.00 30.00 30.00 2 Adhesion (N / 10 mm) 1.2 1.4 1.11 21.3 1.11 6 1.3 1.4 1.2 Soldering resistance ○○○○○○○○○○

[0154]

[0155] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Dielectric constant 2.3 3.0 2.4 3.0 2.6 Dielectric tangent 0.001 0.005 0.002 0.01 3 0.002 Adhesion (N / 10mm) 0.8 1.4 0.7 1.8 0.8 Soldering resistance ×○×○×

[0156]

[0157] Through the above Tables 3 and 4, it can be confirmed that the adhesive compositions of Examples 1 to 10, which include a polyolefin resin having a dielectric constant of 2.5 or less at 15 GHz as a polyolefin resin according to the present invention and include a multifunctional epoxy resin and an acid anhydride in a specific content range, have high adhesion and excellent soldering resistance even when used to bond a low-roughness metal layer having an Rz of 0.7 ㎛ or less to an insulating layer, and can lower the dielectric loss even at 10 GHz or higher.

[0158] On the other hand, the adhesive compositions of Comparative Examples 1 to 5 that do not contain either a multifunctional epoxy resin or an acid anhydride or have a content of them outside a specific range were found to have poor adhesion and soldering resistance or poor dielectric properties when bonding a low-roughness metal layer having an Rz of 0.7 ㎛ or less to an insulating layer.

[0159]

[0160] [Explanation of symbols]

[0161] 110: Insulating layer 120: First adhesive layer

[0162] 130: Second adhesive layer 140: First metal layer

[0163] 150: Second metal layer

Claims

Containing a polyolefin resin, a multifunctional epoxy resin and an acid anhydride having a dielectric constant of 2.5 or less at 1.15 GHz, The above multifunctional epoxy resin is included in an amount of 1 to 10 parts by weight per 100 parts by weight of the polyolefin resin. A low-k adhesive composition, wherein the acid anhydride is contained in an amount of 0.1 to 5 parts by weight per 100 parts by weight of polyolefin resin.

2. A low-dielectric adhesive composition in claim 1, wherein the dielectric constant (Df) of the adhesive layer at 15 GHz after curing is 0.005 or less.

3. A low-k adhesive composition used for bonding a metal layer having a 10-point average roughness (Rz) of 0.7 ㎛ or less to an insulating layer in the first paragraph.

4. In the first paragraph, the multifunctional epoxy resin is a low-k adhesive composition having an epoxy resin equivalent of 250 g / eq or less.

5. A low-k adhesive composition in claim 1, wherein the multifunctional epoxy resin is at least one selected from the group consisting of an amino phenol type epoxy compound, a phenol novolac type epoxy compound, a bisphenol A novolac type epoxy compound, N,N'-tetraglycidyl diaminodiphenylmethane (TGDDM), and tetraphenolethane tetraglycidyl ether (TPETGE).

6. A low-k adhesive composition in the first paragraph, wherein the acid anhydride is at least one selected from the group consisting of succinic anhydride, phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, 3-methyl-hexahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyl-tetrahydrophthalic anhydride, nadic anhydride, methylnadic anhydride, norbornane-2,3-dicarboxylic anhydride, methylnorbornane-2,3-dicarboxylic anhydride, methylcyclohexene dicarboxylic anhydride, 3-dodecenyl succinic anhydride, and octenylsuccinic anhydride.

7. A flexible metal laminate comprising an insulating layer, an adhesive layer formed on at least one surface of the insulating layer, and a metal layer formed on the adhesive layer, A flexible metal laminate, wherein the adhesive layer is formed from a low-k adhesive composition according to any one of claims 1 to 6.

8. A flexible metal laminate in the 7th paragraph, wherein the insulating layer is a polyimide film.

9. In the 7th paragraph, the metal layer is a flexible metal laminate of copper foil.

10. In the 7th paragraph, the metal layer is a flexible metal laminate having a 10-point average roughness (Rz) of 0.7 ㎛ or less.

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