KR20200076177A - Low dielectric adhesive composition and coverlay film comprising the same - Google Patents

Abstract

The present invention relates to an adhesive composition comprising a polyimide resin, an epoxy resin, and an inorganic filler, and a coverlay film comprising the same. The present invention can provide low dielectric properties as well as adhesion, heat resistance, hole reliability, resin flowability, etc. required for PCB, especially FPCB. Therefore, the adhesive composition of the present invention can be applied to a flexible copper clad laminate (FCCL) having a conductive pattern, a bonding sheet of a multilayer FPCB, etc. Furthermore, the electric loss efficiency is excellent even when the adhesive composition is applied to an electronic product.

Description

Low dielectric adhesive composition and coverlay film comprising the same

The present specification describes an adhesive composition having improved dielectric properties and a coverlay film comprising the same.

In recent years, demands for high integration, high microscopy, and high performance of electronic devices using a printed circuit board (PCB) have increased, and high-capacity high-speed transmission has become a major topic. To this end, a flexible printed circuit board (FPCB) has been adopted as a core substrate for electronic products. Flexible circuit boards are thin and easily bendable because they use a laminated plate made by attaching a metal foil to the surface of a flexible insulating film as a base material, and are capable of three-dimensional wiring, which is advantageous for downsizing and weight reduction of devices.

In the case of a PCB using a high-frequency electronic component having high-speed transmission as described above, it has excellent electrical properties, low dielectric constant, and low dielectric loss rate even in the adhesive used for the coverlay film outside the insulating layer around the copper circuit. Is required. However, the adhesive composition proposed so far is mostly composed of an epoxy resin and acrylonitrile butadiene rubber (NBR), acrylic, polyester, etc., while the adhesive strength and heat resistance are excellent, but still cannot minimize the electrical interference due to the fine pattern. , There is a problem that a high-speed transmission material is not sufficient due to a high dielectric constant. In addition, since the low-dielectric insulating materials currently introduced are low-polarity materials, and copper foil, which is an electrical transmission material, also uses copper foil of roughness to minimize transmission loss, the adhesive strength with the adhesive is weak and the heat resistance is poor, making FPCB Have difficulty.

Republic of Korea Registered Patent Publication No. 10-0829382 Republic of Korea Patent Publication No. 10-2013-0083317 Republic of Korea Patent Publication No. 10-2014-0084415

In one aspect, the problem to be solved by the present invention is to provide an adhesive composition for a coverlay having a low dielectric constant and a dielectric constant, while having excellent heat resistance and adhesive strength for application to a flexible circuit board.

In one aspect, the present invention provides an adhesive composition for a coverlay film comprising a polyimide resin, an epoxy resin, a curing agent for an epoxy resin, and an inorganic filler.

In another aspect, the present invention is an electrically insulating base film layer comprising a polyimide-based resin; And an adhesive composition layer comprising the adhesive composition coated on the electrically insulating base film layer.

In one aspect, the adhesive composition according to the present invention may further provide a composition having a low dielectric constant and a dielectric loss ratio by further comprising a polyimide-based resin and an inorganic filler together with an epoxy resin excellent in adhesion and heat resistance. Accordingly, the composition has low dielectric properties at the same time as adhesion, heat resistance, hole reliability (minimization of heat distortion during PTH processing), and resin flowability required for PCB, especially FPCB, and thus, a flexible copper foil laminate having a conductive pattern (FCCL) ), multi-layer FPCB bonding sheet, etc. Furthermore, when applied to electronic products, electric loss efficiency is excellent, and particularly, small electronic products are easy to apply.

1 is a schematic view showing a coverlay film coated with an adhesive composition layer 20 on top of an electrically insulating base film layer 30 according to one embodiment of the present invention.
2 is an adhesive composition layer 20 is coated on the top of the electrically insulating base film layer 30 according to an embodiment of the present invention, the release paper layer 10 on the top of the adhesive composition layer 20 is laminated cover It is a schematic diagram showing a ray film.

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

One embodiment of the present invention provides an adhesive composition comprising a polyimide-based resin, an epoxy resin, a curing agent for an epoxy resin, and an inorganic filler.

As an embodiment, the polyimide-based resin may be a reaction product of an acid anhydride and an aromatic diamine, and the polyimide-based resin produced by the reaction has an advantage of excellent heat resistance, mechanical properties, electrical insulation, and the like. The acid anhydride and the aromatic diamine may be included without limitation, as long as they are capable of producing a polyimide-based resin through a reaction. More specifically, as one embodiment, the polyimide-based resin is a reaction product of an aromatic diamine containing 30 mol% or more of aromatic tetracarboxylic acid anhydride and dimer diamine, and the number average molecular weight is, for example, 3,000 to 50,000. It is 5,000~15000.

Specifically, the acid anhydride may be an aromatic tetracarboxylic acid anhydride, more specifically pyromellitic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenone Tetra carboxylic dianhydride, 3,3', 4,4'-diphenyl ether Tetra carboxylic dianhydride, 3,3',4,4'-diphenyl sulfone tetra carboxylic dianhydride, 1,2 ,3,4-benzene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3', 4,4'-biphenyl tetracarboxylic dianhydride, 2,2',3,3'-biphenyl tetracarboxylic dianhydride, 2,3,3', 4'-biphenyl tetracarboxylic dianhydride Water, 2,3,3', 4'-benzophenonetetracarboxylic dianhydride, 2,3,3', 4'-diphenyl ether tetracarboxylic dianhydride, 2,3,3',4' -Diphenyl sulfone tetra carboxylic dianhydride, 2,2-bis(3,3', 4,4'-tetra carboxy phenyl) tetra fluoro propane dianhydride, 2,2'-bis (3,4-di Carboxyphenoxyphenyl)sulfone dianhydride, 2,2-bis(2,3-dicarboxy phenyl)propane dianhydride, 2,2-bis(3,4-dicarboxy phenyl)propane dianhydride and 4,4'[ Propane-2,2-diylbis(1,4-phenyleneoxy)]diphthalic acid dianhydride.

Specifically, the aromatic diamine is phenylenediamine (PDA), oxydianiline (ODA), o-phenylenediamine (OPD), metaphenylenediamine (MPD), 1,3-bis (4-aminophenoxy) Benzene (TPER), 4,4'-bis(4-aminophenoxy)benzene (TPEQ), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB-HG) (TFDB), 2,2'-bis(trifluoromethyl)benzidine), 1,3'-bis(3-aminophenoxy)benzene (APBN), 3,5-diaminobenzotrifluoride (DABTF) and 2,2 -Bis(4-[4-aminophenoxy]-phenyl)propane (BAPP).

As an embodiment, the polyimide-based resin may be included in an amount of 10 to 70 parts by weight, more specifically 40 to 50 parts by weight based on the total weight of the composition. When the polyimide-based resin is contained in less than 10 parts by weight, the ratio of the polyimide-based resin is small, so that satisfactory low dielectric properties are not exhibited, and when it is included in excess of 70 parts by weight, the adhesion, heat resistance, and resin flow properties are lowered, resulting in PCB There is a problem that it is difficult to apply to. More specifically, the polyimide-based resin is 10 parts by weight or more, 12 parts by weight or more, 14 parts by weight or more, 16 parts by weight or more, 18 parts by weight or more, 20 parts by weight or more, 22 parts by weight based on the total weight of the composition Above, above 24 parts by weight, above 26 parts by weight, above 28 parts by weight, above 30 parts by weight, above 32 parts by weight, above 34 parts by weight, above 36 parts by weight, above 38 parts by weight, above 40 parts by weight, above 42 parts by weight Above, above 44 parts by weight, above 46 parts by weight, above 48 parts by weight, above 50 parts by weight, above 52 parts by weight, above 54 parts by weight, above 56 parts by weight, above 58 parts by weight, above 60 parts by weight, above 62 parts by weight Or more, 64 parts by weight or more, 66 parts by weight or more, 68 parts by weight or more, or 70 parts by weight or more. In addition, the polyimide resin is 70 parts by weight or less, 68 parts by weight or less, 66 parts by weight or less, 64 parts by weight or less, 62 parts by weight or less, 60 parts by weight or less, 58 parts by weight or less, based on the total weight of the composition 56 parts by weight or less, 54 parts by weight or less, 52 parts by weight or less, 50 parts by weight or less, 48 parts by weight or less, 46 parts by weight or less, 44 parts by weight or less, 42 parts by weight or less, 40 parts by weight or less, 38 parts by weight or less, 36 parts by weight or less, 34 parts by weight or less, 32 parts by weight or less, 30 parts by weight or less, 28 parts by weight or less, 26 parts by weight or less, 24 parts by weight or less, 22 parts by weight or less, 20 parts by weight or less, 18 parts by weight or less, 16 parts by weight or less, 14 parts by weight or less, 12 parts by weight or less, or 10 parts by weight may be included.

As an embodiment, the epoxy resin is for realizing the adhesive and heat resistance of the composition, specifically, a phenol novolac type epoxy compound, a cresol novolac type epoxy compound, a bisphenol A type epoxy compound, a bisphenol F type epoxy compound, and a bisphenol S type epoxy compound, hydrogenated bisphenol A type epoxy compound, hydrogenated bisphenol F type epoxy compound, stilbene type epoxy compound, triazine skeleton-containing epoxy compound, fluorene skeleton-containing epoxy compound, linear aliphatic epoxy compound, alicyclic epoxy compound, glycylic Dill amine type epoxy compound, triphenol methane type epoxy compound, alkyl-modified triphenol methane type epoxy compound, biphenyl type epoxy compound, dicyclopentadiene skeleton-containing epoxy compound, naphthalene skeleton-containing epoxy compound, aryl alkylene type epoxy compound, tetra Glycidyl xylene diamine, a modified epoxy compound obtained by modifying these epoxy compounds in dimer acid, and dimer acid diglycidyl ester may include one or more selected from the group consisting of, but is not limited thereto. According to one embodiment, the epoxy resin may be an epoxy resin having a low equivalent in terms of enhancing the adhesive strength of the composition and maintaining the low dielectric properties of the polyimide-based resin included therein. In addition, in the case of a polyimide-based resin, it exhibits a moisture absorption amount of 2-3%, but when the polyimide-based resin is combined with a curing agent for an epoxy resin and/or an epoxy resin as described above, the moisture of the polyimide-based resin is included. Moisture absorption can be controlled.

In addition, the epoxy resin according to one embodiment from the viewpoint may be included in 1 to 20 parts by weight, more specifically 3 to 10 parts by weight based on the total weight of the composition. When the weight part of the epoxy resin is less than 1, the crosslinking density and the cohesive force of the adhesive composition become weak, the adhesion strength may decrease and the heat resistance may decrease, and when it exceeds 20 parts by weight, the content of the polyimide resin is relatively low and the dielectric constant of the composition This can be high. Specifically, the epoxy resin is 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, 0.5 parts by weight or more, 0.6 parts by weight or more, 0.7 parts by weight or more, 0.8 More than parts by weight, more than 0.9 parts by weight, more than 1 part by weight, more than 2 parts by weight, more than 3 parts by weight, more than 4 parts by weight, more than 5 parts by weight, more than 6 parts by weight, more than 7 parts by weight, more than 8 parts by weight, 9 More than 10 parts by weight, more than 10 parts by weight, more than 11 parts by weight, more than 12 parts by weight, more than 13 parts by weight, more than 14 parts by weight, more than 15 parts by weight, more than 16 parts by weight, more than 17 parts by weight, more than 18 parts by weight, 19 It may be included in more than 20 parts by weight or 20 parts by weight. In addition, the epoxy is 20 parts by weight or less, 19 parts by weight or less, 18 parts by weight or less, 17 parts by weight or less, 16 parts by weight or less, 15 parts by weight or less, 14 parts by weight or less, 13 parts by weight based on the total weight of the composition Or less, 12 parts by weight or less, 11 parts by weight or less, 10 parts or less, 9 parts or less, 8 parts or less, 7 parts or less, 6 parts or less, 5 parts or less, 4 parts or less, 3 parts by weight Below, 2 parts by weight or less, 1 part by weight or less, 0.9 part by weight or less, 0.8 part by weight or less, 0.7 part by weight or less, 0.6 part by weight or less, 0.5 part by weight or less, 0.4 part by weight or less, 0.3 part by weight or less, 0.2 part by weight Or it may be included in 0.1 parts by weight. As an embodiment, the curing agent for the epoxy resin serves to cure the epoxy resin, and the heat resistance and adhesive properties of the composition may be further improved by an epoxy resin curing reaction. As the curing agent for the epoxy resin, for example, an amine curing agent may be included, and in order to enhance low dielectric properties, a phenolic curing agent, an isocyanate curing agent, an active ester curing agent, and the like may be included. As an embodiment, the amount of the curing agent for the epoxy resin may be added by calculating the amount of active hydrogen to the equivalent of the epoxy resin, for example, 50 to 300 parts by weight, more specifically 100 to 100 parts by weight of the epoxy resin 200 parts by weight may be included. In addition, if necessary, a curing catalyst that accelerates the reaction between the epoxy resin and the curing agent for the epoxy resin may be selectively used, and examples of the curing catalyst include imidazole.

In one embodiment, the composition may lower the coefficient of thermal expansion (CTE) value of the composition by including an inorganic filler. The type of the inorganic filler is not limited, for example, according to one embodiment, one selected from the group consisting of silica, alumina, magnesium oxide, talc, titanium oxide, boron nitride, zirconia, calcium carbonate, magnesium carbonate and aluminum hydroxide It may include the above. In addition, as an embodiment, the average particle size of the inorganic filler may be 0.5 to 10 μm, but is not limited thereto. Specifically, the average particle size of the inorganic filler is 0.5 µm or more, 0.6 µm or more, 0.7 µm or more, 0.8 µm or more, 0.9 µm or more, 1 µm or more, 2 µm or more, 3 µm or more, 4 µm or more, 5 µm or more , 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, or 10 μm or more. In addition, the average particle size of the inorganic filler is 10 µm or less, 9 µm or less, 8 µm or less, 7 µm or less, 6 µm or less, 5 µm or less, 4 µm or less, 3 µm or less, 2 µm or less, 1 µm or less, It may be 0.9 μm or less, 0.8 μm or less, 0.7 μm or less, 0.6 μm or less, or 0.5 μm.

As an embodiment, the inorganic filler may be included in 10 to 70 parts by weight based on the total weight of the composition. When the inorganic filler is included in less than 10 parts by weight, the coefficient of thermal expansion (CTE) of the composition is increased, and resin flowability may be deteriorated. When the content exceeds 70 parts by weight, the adhesive force of the composition itself decreases, and there is a problem that workability deteriorates due to dispersibility and viscosity problems. More specifically, the inorganic filler is 10 parts by weight or more, 12 parts by weight or more, 14 parts by weight or more, 16 parts by weight or more, 18 parts by weight or more, 20 parts by weight or more, 22 parts by weight or more, 24 parts by weight based on the total weight of the composition Part by weight, 26 parts by weight or more, 28 parts by weight or more, 30 parts by weight or more, 32 parts by weight or more, 34 parts by weight or more, 36 parts by weight or more, 38 parts by weight or more, 40 parts by weight or more, 42 parts by weight or more, 44 parts by weight or more Part or more, 46 part or more, 48 part or more, 50 part or more, 52 part or more, 54 part or more, 56 part or more, 58 part or more, 60 part or more, 62 part or more, 64 part or more Part by weight, 66 parts by weight or more, 68 parts by weight or more, or 70 parts by weight may be included. In addition, the inorganic filler is 70 parts by weight or less, 68 parts by weight or less, 66 parts by weight or less, 64 parts by weight or less, 62 parts by weight or less, 60 parts by weight or less, 58 parts by weight or less, 56 parts by weight or less based on the total weight of the composition , 54 parts by weight or less, 52 parts by weight or less, 50 parts by weight or less, 48 parts by weight or less, 46 parts by weight or less, 44 parts by weight or less, 42 parts by weight or less, 40 parts by weight or less, 38 parts by weight or less, 36 parts by weight or less , 34 parts by weight or less, 32 parts by weight or less, 30 parts by weight or less, 28 parts by weight or less, 26 parts by weight or less, 24 parts by weight or less, 22 parts by weight or less, 20 parts by weight or less, 18 parts by weight or less, 16 parts by weight or less , 14 parts by weight or less, 12 parts by weight or less, or 10 parts by weight.

As an embodiment, the composition may further include additives for mixing organic and inorganic substances included in the composition, if necessary. Or, if necessary, further include a suitable amount of dehydrating agent, plasticizer, weathering agent, antioxidant, heat stabilizer, lubricant, antistatic agent, bleach, colorant, surface treatment agent, viscosity modifier, dispersant, phosphorus flame retardant, flame retardant filler, fluorine filler, etc. can do.

In order to lower the moisture absorption of the polyimide, some dehydrating agents, surface treatment agents for dispersing fillers and organic substances, and dispersing agents may be added, and phosphorus-based flame retardants may be added to give flame retardant properties.

According to embodiments of the present invention, the adhesive composition may be prepared according to the following method. As an embodiment, each resin contained in the composition is diluted with an organic solvent and used. For example, the polyimide resin can be used by diluting cyclohexanone, an epoxy resin, and a curing agent such as MEK (methyl ethyl ketone) and toluene. The curing catalyst can be used by diluting in PGME (Propylene glycol mono methyl ether). The inorganic filler may be used by dispersing, and the dispersion may be a beads disperser, a 3 roll disperser, or the like. Then, the polyimide resin and the dispersed inorganic filler are mixed, and the epoxy resin and the curing agent for the epoxy resin are mixed. Then, the diluted curing catalyst is added and mixed to prepare an adhesive composition.

According to embodiments of the present invention, by including a polyimide-based resin in a composition together with an epoxy resin, not a conventional acrylonitrile-butadiene rubber, it is possible to exhibit low dielectric properties while maintaining excellent heat resistance and adhesion of the epoxy resin. Therefore, when the composition is applied to a coverlay film or a bonding sheet of a flexible printed circuit board, high-speed transmission is possible and transmission loss can be reduced.

According to embodiments of the present invention, the composition may have a dielectric constant of 3.0 Dk or less, specifically 2.5 to 3.0 Dk. More specifically, the dielectric constant is more than 0 Dk, 0.1 Dk or more, 0.5 Dk or more, 1.0 Dk or more, 1.5 Dk or more, 2.0 Dk or more, 2.1 Dk or more, 2.2 Dk or more, 2.3 Dk or more, 2.4 Dk or more, 2.5 Dk or more, 2.6 Dk or more, 2.7 Dk or more, 2.8 Dk or more, or 2.9 Dk or more, and less than 3.0 Dk, 2.9 Dk or less, 2.8 Dk or less, 2.7 Dk or less, 2.6 Dk or less, 2.5 Dk or less, 2.4 Dk or less, 2.3 Dk or less, 2.2 Dk or less, 2.1 Dk or less, 2.0 Dk or less, 1.5 Dk or less, 1.0 Dk or less, or 0.5 Dk or less. This is a significantly improved dielectric constant than the conventional epoxy resin and NBR adhesive composition of 3.2 Dk or more.

In addition, according to embodiments of the present invention, the composition may have a dielectric loss rate, that is, a dielectric loss tangent of less than 0.01 Df, specifically 0.002 to 0.005 Df. More specifically, more than 0 Df, 0.001 Df or more, 0.002 Df or more, 0.003 Df or more, 0.004 Df or more, 0.005 Df or more, 0.006 Df or more, 0.007 Df or more, 0.008 Df or more, or 0.009 Df or more, and less than 0.01 Df, 0.009 Df or less, 0.008 Df or less, 0.007 Df or less, 0.006 Df or less, 0.005 Df or less, 0.004 Df or less, 0.003 Df or less, 0.002 Df or less, or 0.001 Df or less. This is a significant improvement over the dielectric loss tangent of the conventional epoxy resin and the adhesive composition comprising NBR more than 0.01.

According to another embodiment, the present invention relates to a coverlay film comprising the adhesive composition, hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 show an exemplary form of the present invention. Referring to Figure 1, the coverlay film according to an embodiment may include two layers, specifically, an electrically insulating base film layer 30; And an adhesive composition layer 20 coated on the electrically insulating base film layer 30. Or, referring to Figure 2, the coverlay film according to an embodiment may include three layers, specifically, an electrically insulating base film layer 30; An adhesive composition layer 20 coated on the electrically insulating base film layer 30; And it may include a release paper layer 10 formed on the adhesive composition layer 20.

As one embodiment, the electrically insulating base film layer is a film layer having high heat resistance and flame retardant properties, and the electrically insulating base may include a polyimide resin. As an embodiment, the thickness of the electrically insulating base film layer may be, for example, 12 to 50 μm. When the thickness is 12 µm or less, the film is thin, and thus workability is reduced during FPCB manufacturing, and insulation properties may be deteriorated. If the thickness is more than 50㎛, it is a factor of cost increase, and it is thick enough to be applied to FPCB, so the flexibility can be reduced.

As an embodiment, the polyimide-based resin included in the electrically insulating base film may be a reaction product of acid anhydride and aromatic diamine, and the acid anhydride and aromatic diamine can produce a polyimide-based resin through reaction. The type is not limited and can be included. Specifically, the acid anhydride may be an aromatic tetracarboxylic acid anhydride, more specifically pyromellitic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenone Tetra carboxylic dianhydride, 3,3', 4,4'-diphenyl ether Tetra carboxylic dianhydride, 3,3',4,4'-diphenyl sulfone tetra carboxylic dianhydride, 1,2 ,3,4-benzene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3', 4,4'-biphenyl tetracarboxylic dianhydride, 2,2',3,3'-biphenyl tetracarboxylic dianhydride, 2,3,3', 4'-biphenyl tetracarboxylic dianhydride Water, 2,3,3', 4'-benzophenonetetracarboxylic dianhydride, 2,3,3', 4'-diphenyl ether tetracarboxylic dianhydride, 2,3,3',4' -Diphenyl sulfone tetra carboxylic dianhydride, 2,2-bis(3,3', 4,4'-tetra carboxy phenyl) tetra fluoro propane dianhydride, 2,2'-bis (3,4-di Carboxyphenoxyphenyl)sulfone dianhydride, 2,2-bis(2,3-dicarboxy phenyl)propane dianhydride, 2,2-bis(3,4-dicarboxy phenyl)propane dianhydride and 4,4'[ Propane-2,2-diylbis(1,4-phenyleneoxy)]diphthalic acid dianhydride. Specifically, the aromatic diamine is phenylenediamine (PDA), oxydianiline (ODA), o-phenylenediamine (OPD), metaphenylenediamine (MPD), 1,3-bis (4-aminophenoxy) Benzene (TPER), 4,4'-bis(4-aminophenoxy)benzene (TPEQ), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB-HG) (TFDB), 2,2'-bis(trifluoromethyl)benzidine), 1,3'-bis(3-aminophenoxy)benzene (APBN), 3,5-diaminobenzotrifluoride (DABTF) and 2,2 -Bis(4-[4-aminophenoxy]-phenyl)propane (BAPP).

In one embodiment, the electrically insulating base film layer may further include primer treatment, surface treatment, corona treatment, or plasma treatment in order to increase adhesion with the adhesive composition coated on the film layer. In one embodiment, the primer treatment may include coating a small amount of acrylic, urethane resin, and the like, in order to increase adhesion between the substrate and the adhesive. The surface treatment may include coating a surface with a silane coating, for example, amino, mercapto, epoxy silane, and the like, to increase adhesion between the substrate and the adhesive force. Corona treatment and plasma treatment can increase the specific surface area of the substrate with strong energy and ionic bonding, and increase the adhesion by increasing chemical bonding through ionic bonding.

As an embodiment, the adhesive composition layer is a layer formed by coating an adhesive composition on the electrically insulating base film layer, wherein the adhesive composition may include an adhesive composition according to the embodiments of the present invention described above.

As an embodiment, the thickness of the coated adhesive composition layer may be, for example, 5 to 50 μm, and more specifically, 20 to 30 μm. When the thickness of the adhesive composition layer is less than 5 µm, sufficient adhesion is not provided when bonding to a copper circuit or the electrically insulating base film layer, and heat resistance may be deteriorated because it is not filled in the copper circuit region. When the thickness of the adhesive composition layer is more than 50 μm, it is a factor of cost increase, and a thin film FPCB requiring flexibility may have a small bending radius due to high thickness, and thus a decrease in flexibility may occur.

In one embodiment, the release paper layer is also referred to as a “release film layer”, and serves to protect the adhesive composition layer from foreign matter. As an embodiment, the release paper layer may further include a synthetic resin coating layer on paper, and may further include, for example, a polyethylene (PE)-based or polypropylene (PP)-based coating layer. Alternatively, a release agent may be further coated for peeling as necessary. The release agent is a release material for protection of the release paper layer, and the thickness, material, and the like to be coated by the user may be appropriately selected in consideration of punchability and peeling force. As an embodiment, the thickness of the release paper layer may be 50 to 150 μm. When the thickness of the release paper layer is less than 50 μm, the workability is poor due to the low thickness during processing, and when the thickness is 150 μm or more, it is not smooth in the manufacturing process due to the lack of heat transfer by the thick substrate, and there is a disadvantage of price increase. .

As an embodiment, the coverlay film may be prepared by coating an adhesive composition layer on an electrically insulating base film layer, and then selectively laminating a release paper layer on the adhesive composition layer, wherein the coating or laminating process is performed by the present invention. The methods commonly used in the technical field of can be applied. For example, the adhesive composition layer uses one or more coating processes such as gravure coating, micro gravure coating, spin coating, screen printing, comma coating, and die coating on the electrically insulating base film layer. By applying the adhesive composition on the electrically insulating base film layer may be formed by drying. As an embodiment, the coating and lamination can be done in a single process. For example, the lamination paper is coated with an adhesive composition by applying a polyimide film to the first paper, dried, and then coated with the adhesive surface coated on the dried polyimide film and the release paper applied in the second paper with a slight heat laminating roll. Can be lazy.

The coverlay film according to an embodiment may be applied to an insulating layer that protects a circuit when manufacturing a flexible circuit board (FPCB). For example, when applied to the insulating layer, the release paper layer of the coverlay film may be peeled off, and the outer surface of the adhesive composition may be attached to the circuit surface (copper surface) of the FPCB to be used to laminate the electrically insulating base film layer. After the lamination is completed, the specimen may be compressed through a hot press process to produce a product, and the conditions for the thermocompression process include a surface pressure condition of about 30 minutes to 2 hours under a temperature of 150 to 180° C., and about 20 to 45 kg. can do.

Hereinafter, the present invention will be described in detail with reference to Examples, Comparative Examples and Test Examples. These are only provided by way of example to illustrate the present invention in more detail, the scope of the present invention is not limited by these examples, comparative examples and test examples for those skilled in the art It will be self-evident.

[Example 1]

An adhesive composition according to one embodiment of the present invention was prepared according to the following method.

An adhesive composition was prepared by mixing 39 parts by weight of polyimide resin with 5 parts by weight of epoxy resin and 9 parts by weight of curing agent, mixing less than 0.1 parts by weight of curing catalyst, and mixing 40 parts by weight of filler with spherical silica.

[Comparative example]

As a prior art, an adhesive composition containing acrylonitrile butadiene rubber, together with an epoxy resin, which is not a polyimide resin, was prepared according to the following method.

Comparative Example 1

As a composition of the prior art Republic of Korea Patent Publication No. 10-2013-0083317 (non-halogen-based flame retardant adhesive composition and a coverlay film using the same), 60 parts by weight of epoxy resin of equivalent weight 320, 40 parts by weight of bisphenol A-based epoxy resin NBR An adhesive composition was prepared by adding 50 parts by weight, 4 parts by weight of the aromatic diamine curing agent 4,4-diaminodiphenylsulfone, 0.4 parts by weight of the curing accelerator 2ethyl-4 methyl imidazole, and 5 parts by weight of the phosphorus flame retardant.

Comparative Example 2

As a composition of the prior art Republic of Korea Patent Publication No. 10-2014-0084415 (non-halogen-based fast-curing adhesive composition and coverlay film using the same), 100 parts by weight of bisphenol A-based epoxy resin, 60 parts by weight of NBR, hydroxylated with inorganic filler An adhesive composition was prepared by mixing 30 parts by weight of aluminum, 20 parts by weight of a phosphorus-based flame retardant, 10 parts by weight of 3,3-diaminodiphenylsulfone as a curing agent, and 2 parts by weight of a curing catalyst 2ethyl-4methylimidazole.

Comparative Example 3

5 parts by weight of an epoxy resin and 9 parts by weight of a curing agent were mixed with 39 parts by weight of the polyimide resin, and the curing catalyst was mixed with less than 0.1 parts by weight, and an adhesive composition was prepared except for the filler.

[Test Example 1]

In order to confirm the low dielectric properties of the adhesive composition according to an embodiment of the present invention, the following experiment was performed.

Prior to the experiment, Example 2 (plate silica filler), Example 3 (aluminum hydroxide), and Example 4 (alumina) were prepared in the same manner as in Example 1, except for the type of the inorganic filler.

Dielectric constant (Dk) and dielectric loss tangent (Df) were measured according to the IPC TM-650 2.5.5.9 standard.

division Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Dielectric constant (Dk) 2.8 2.8 2.9 2.9 3.2 3.4 2.7 Dielectric tangent (Df) 0.004 0.004 0.007 0.009 0.01 0.01 0.01 Adhesion 1.1 0.6 1.0 1.0 1.2 1.2 1.2

As a result, as shown in Table 1, it was confirmed that all of Examples 1 to 4 according to the embodiments of the present invention exhibit low dielectric constant with a dielectric constant of 3.0 Dk or less and a dielectric loss tangent of less than 0.01 Dk.

When the dielectric constant (Dk) is 3 or more, the signal speed delay time cannot be shortened in the circuit, making high-speed high-speed transmission difficult. In addition, when the dielectric loss tangent (Df) is 0.01 or more, a transmission loss becomes large, which causes a failure of high-speed transmission.

[Test Example 2]

In order to compare and confirm low dielectric properties, adhesion and heat resistance according to the content of the inorganic filler contained in the adhesive composition according to an embodiment of the present invention, the following experiment was conducted.

Prior to the experiment, Example 5 (including 20% by weight of the inorganic filler), Example 6 (including 30% by weight of the inorganic filler), and Example 7 (Inorganic filler) in the same manner except for the content of the inorganic filler in Example 1 above 50% by weight) and Example 8 (including 60% by weight of inorganic filler) were prepared. At this time, the ratio of the polyimide-based resin, the epoxy resin, and the curing agent for the epoxy resin contained in the composition was maintained in the same manner as in Example 1.

The dielectric constant and dielectric loss tangent were measured in the same manner as in Test Example 1.

The adhesion was measured as follows.

Each adhesive prepared before the polyimide film having a thickness of 25 um was coated with an adhesive having a thickness of 25 um using a bar coater or an applicator. For drying, the oven was dried at a temperature of 140 for 2 minutes. The dried adhesive film was laminated with release paper using a roll laminator.

A coverlay film is prepared by laminating (coating) each adhesive composition prepared above, removing the release paper of the film, and laminating the adhesive surface of the coverlay with the copper foil surface of the flexible copper foil laminate (FCCL), followed by hot press. Bonded. (Temperature 170~180°C, pressure 45kgF/cm ² , pressurization time 60 minutes) The specimen prepared as above was cut to a width of 10 mm to prepare a specimen for measuring adhesion. Then, the tensile strength was measured using a tensile strength tester while peeling at a rate of 50 mm/min at a 90-degree measurement angle. The heat resistance was cut to a size of 20 mm in width and 20 mm in length, and melted at 288°C. It was floated on a lead bath and evaluated for the following criteria with or without deformation and bubble formation of the specimen for 1 minute.

O: No bubble formation or surface deformation at all (good)

X: Bubble formation and surface deformation were observed (poor).

division Example 1 Example 5 Example 6 Example 7 Example 8 Dielectric constant (Dk) 2.8 2.7 2.75 2.9 3.0 Dielectric tangent (Df) 0.004 0.006 0.005 0.003 0.002 Adhesion (kgF) 1.1 1.1 1.1 1.0 0.7 Heat resistance O O O O X

As a result, as shown in Table 2, the embodiments of the present invention including the inorganic filler are excellent in dielectric constant and dielectric loss tangent, and have been shown to have low dielectric properties, whereas the dielectric constant increases as the content of the inorganic filler increases. The genetic tangent was lowered. However, as the content of the inorganic filler increased, it was confirmed that the adhesive force, that is, the adhesiveness and the heat resistance were lowered because the content ratio of the epoxy resin was lowered.

[Test Example 3]

In order to compare and confirm low dielectric properties, adhesion and heat resistance according to the average particle size of the inorganic filler contained in the adhesive composition according to the embodiment of the present invention, the following experiment was conducted.

Prior to the experiment, Example 9 (average particle size 0.3 µm), Example 1 (average particle size 0.7 µm), and Example 10 (average particle) in the same manner as in Example 1 except for the average particle size of the inorganic filler. Size 1.0 μm), Example 11 (average particle size 3.0 μm) and Example 12 (average particle size 10 μm) were prepared.

Dielectric constant, dielectric loss tangent, adhesion and heat resistance were measured in the same manner as in Test Example 2.

division 0.3㎛ 0.7㎛ 1㎛ 3㎛ 10㎛ Dielectric constant (Dk) 2.5 2.8 2.9 2.9 2.9 Dielectric tangent (Df) 0.003 0.004 0.006 0.008 0.01 Adhesion (kgF) 0.6 1.1 1.2 1.2 1.3 Heat resistance X O O O O

As a result, the smaller the average particle size of the inorganic filler, the lower the dielectric properties, whereas the adhesion and heat resistance of the composition itself decreased. This is because the function of the epoxy resin was deteriorated as the impurity amount of the epoxy resin increased because the dispersion of the other components did not occur effectively during the preparation of the adhesive composition due to the increase in the specific surface area of the inorganic filler.

10: release layer
20: adhesive composition layer
30: electrically insulating base film layer

Claims (16)

An adhesive composition comprising a polyimide resin, an epoxy resin, a curing agent for an epoxy resin, and an inorganic filler. The method of claim 1, wherein the polyimide resin is a reaction product of an acid anhydride and an aromatic diamine,
The acid anhydride component is pyromellitic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3', 4,4' -Diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride, 1,2,3,4-benzene tetracarboxylic dianhydride, 1,4 ,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 2, 2',3,3'-biphenyl tetracarboxylic dianhydride, 2,3,3', 4'-biphenyl tetracarboxylic dianhydride, 2,3,3', 4'-benzophenonetetracar Acidic dianhydride, 2,3,3', 4'-diphenyl ether tetra carboxylic dianhydride, 2,3,3',4'-diphenyl sulfone tetra carboxylic dianhydride, 2,2-bis (3,3', 4,4'-tetra carboxy phenyl) tetra fluoro propane dianhydride, 2,2'-bis(3,4-dicarboxy phenoxyphenyl) sulfone dianhydride, 2,2-bis(2 ,3-dicarboxy phenyl)propane dianhydride, 2,2-bis(3,4-dicarboxy phenyl)propane dianhydride and 4,4'[propane-2,2-diylbis(1,4-phenyleneoxy) )]Diphthalic dianhydride contains at least one selected from the group consisting of,
The aromatic diamine is phenylenediamine (PDA), oxydianiline (ODA), o-phenylenediamine (OPD), metaphenylenediamine (MPD), 1,3-bis(4-aminophenoxy)benzene (TPER) ), 4,4'-bis(4-aminophenoxy)benzene (TPEQ), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB-HG) (TFDB), 2,2 '-Bis(trifluoromethyl)benzidine), 1,3'-bis(3-aminophenoxy)benzene (APBN), 3,5-diaminobenzotrifluoride (DABTF) and 2,2-bis( An adhesive composition comprising at least one member selected from the group consisting of 4-[4-aminophenoxy]-phenyl)propane (BAPP). The adhesive composition of claim 1, wherein the inorganic filler comprises at least one selected from the group consisting of silica, alumina, magnesium oxide, talc, titanium oxide, boron nitride, zirconia, calcium carbonate, magnesium carbonate, and aluminum hydroxide. According to claim 1, The average particle size of the inorganic filler is 0.5 to 10㎛, adhesive composition. The adhesive composition of claim 1, wherein the polyimide-based resin is included in an amount of 10 to 70 parts by weight based on the total weight of the composition. The adhesive composition of claim 1, wherein the epoxy resin is included in an amount of 0.1 to 20 parts by weight based on the total weight of the composition. The adhesive composition of claim 1, wherein the curing agent for the epoxy resin is included in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the epoxy resin. The adhesive composition of claim 1, wherein the inorganic filler is included in an amount of 10 to 70 parts by weight based on the total weight of the composition. The adhesive composition of claim 1, wherein the composition has a dielectric constant (Dk) of 3.0 Dk or less. The adhesive composition of claim 1, wherein the composition has a dielectric loss tangent (Df) of less than 0.01. The adhesive composition of claim 1, wherein the composition is for a coverlay film or bonding sheet of a flexible printed circuit board. An electrically insulating base film layer comprising a polyimide resin; And
A coverlay film comprising an adhesive composition layer comprising the composition of claim 1 coated on the electrically insulating base film layer. The coverlay film of claim 12, wherein the thickness of the electrically insulating base film layer is 12 to 50 μm. The coverlay film of claim 12, wherein the adhesive composition layer has a thickness of 5 to 50 μm. The coverlay film of claim 12, further comprising a release paper layer formed on the adhesive composition layer. The coverlay film of claim 15, wherein the release paper layer has a thickness of 50 to 150 μm.

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