KR20170061348A - Bonding sheet and flexible printed circuit board - Google Patents

Abstract

The present invention relates to a styrene-ethylene-butylene-styrene copolymer comprising 0.1 to 15% by weight of a dicarboxylic acid or an acid anhydride thereof bonded thereto; Epoxy resin; A curing catalyst comprising at least one compound selected from the group consisting of an imidazole compound, an imine compound and an amine compound; And an adhesive layer comprising an acid anhydride-based compound; and a flexible metal laminate including the bonding sheet.

Description

BONDING SHEET AND FLEXIBLE PRINTED CIRCUIT BOARD BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a bonding sheet and a flexible printed circuit board.

In recent years, signal transmission speed within the electronic device or signal transmission speed to the outside of the electronic device has been accelerating in accordance with the trend of miniaturization and high speed of electronic devices and the combination of various functions. Accordingly, a printed circuit board using an insulator having a dielectric constant and a dielectric loss coefficient lower than that of an existing insulator is required.

Previously known bonding sheets and coverlay are generally made of an adhesive epoxy resin composition. Due to the intrinsic properties of the epoxy resin, the dielectric constant increases and the dielectric constant and dielectric loss factor It is not easy to lower. Further, since the elastomer such as butadiene / acrylonitrile (CTBN) at the terminal of the carboxyl group generally used in the adhesive epoxy resin composition has a high dielectric constant and a dielectric loss coefficient, it can be applied to a printed circuit board which is finer and highly integrated, There was a limit.

Further, as the degree of integration of the printed circuit board is increased, the gap between the holes and the holes becomes narrower, the thickness of the constituent layers of the printed circuit board becomes thinner, and the intervals between the circuits become narrower, There is a possibility that a short circuit occurs and a flexible printed circuit board is widely applied to various equipments exposed to high temperature and high humidity conditions, so it is necessary to develop a technique to prevent CAF phenomenon.

However, the previously known CTBN-based elastomer used in the adhesive for flexible printed circuit boards is produced through an emulsion polymerization process using a large amount of ionic surfactant. The content of sodium or sodium ion is 1,000 ppm, The possibility of occurrence of a short circuit due to the phenomenon is further increased.

Accordingly, it is necessary to develop a method capable of preventing malfunction of the flexible printed circuit board even under high-temperature and high-humidity conditions and making the flexible printed circuit board finer and highly integrated.

The present invention provides a bonding sheet which has a low dielectric constant and a low dielectric loss coefficient and is applied to a flexible printed circuit board so as to minimize metal ion transition and prevent the occurrence of a short circuit by CAF even under high temperature and high humidity environments will be.

It is another object of the present invention to provide a flexible printed circuit board which can prevent the occurrence of a short circuit due to CAF even when exposed for a long time under a high temperature and high humidity environment and has a high product reliability, a low permittivity and a low dielectric loss coefficient, will be.

In the present specification, styrene-ethylene-butylene-styrene copolymer in which dicarboxylic acid or an acid anhydride thereof is bonded in an amount of 0.1 to 15 wt%; Epoxy resin; A curing catalyst comprising at least one compound selected from the group consisting of an imidazole compound, an imine compound and an amine compound; And an adhesive layer comprising an acid anhydride-based compound. The bonding sheet for a printed circuit board is provided.

In this specification, a flexible printed circuit board including the bonding sheet for a printed circuit board may be provided.

Further, in this specification, the first flexible metal laminate; A coverlay formed on the first flexible metal laminate; Styrene-ethylene-butylene-styrene copolymer in which dicarboxylic acid or an acid anhydride thereof is contained in an amount of 0.1 to 15% by weight; Epoxy resin; A curing catalyst comprising at least one compound selected from the group consisting of an imidazole compound, an imine compound and an amine compound; And an acid anhydride-based compound, the bonding sheet being formed on the coverlay; And a second flexible metal laminate formed on the bonding sheet.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a flexible printed circuit board according to an embodiment of the present invention; FIG.

As described above, according to one embodiment of the present invention, a styrene-ethylene-butylene-styrene copolymer having a dicarboxylic acid or an acid anhydride thereof in an amount of from 0.1% by weight to 15% by weight bonded thereto; Epoxy resin; A curing catalyst comprising at least one compound selected from the group consisting of an imidazole compound, an imine compound and an amine compound; And an adhesive layer comprising an acid anhydride-based compound. The bonding sheet for a printed circuit board can be provided.

The present inventors have found that a styrene-ethylene-butylene-styrene copolymer in which 0.1 to 15% by weight of a dicarboxylic acid or an acid anhydride thereof is combined with an epoxy resin, the aforementioned acid anhydride- Can be applied not only to a low dielectric constant and a low dielectric loss coefficient but also to a flexible printed circuit board to minimize metal ion transition and to prevent the occurrence of a short circuit due to CAF even in a high temperature and high humidity environment Through experiments, we confirmed and completed the invention.

Specifically, the adhesive layer includes a styrene-ethylene-butylene-styrene copolymer containing 0.1 to 15% by weight of the dicarboxylic acid or an acid anhydride thereof bonded to the flexible printed circuit board, It is possible to minimize the occurrence of a short circuit due to the CAF even in a high temperature and high humidity environment.

When an adhesive layer containing a CTBN-based elastomer used in a previously known adhesive for a flexible circuit board is used, the sodium or sodium ion concentration is excessively high, and thus a short circuit is likely to occur due to the CAF phenomenon. On the other hand, the dicarboxylic acid or its acid anhydride The adhesive layer containing the styrene-ethylene-butylene-styrene copolymer in an amount of 0.1 wt% to 15 wt% combined with the adhesive layer contains or does not substantially contain sodium or sodium ions, And it is also possible to prevent the occurrence of a short circuit due to the CAF even in a high temperature and high humidity environment. Specifically, the content of sodium or sodium ions in the adhesive layer may be 100 ppmw or less, or 10 ppmw or less, and the sodium or sodium ion in the adhesive layer may be substantially absent.

In addition, the adhesive layer included in the bonding sheet for a printed circuit board has a chlorine or chlorine ion concentration lower than that of a previously known bonding sheet, thereby minimizing the metal ion transition, and also permitting the CAF It is possible to prevent the occurrence of a short circuit due to the short circuit. Specifically, the previously known bonding sheet shows a chlorine ion content of about 600 ppmw, while the chlorine ion content in the adhesive layer included in the bonding sheet for a printed circuit board may be 150 ppmw or less, or 120 ppmw or less.

The adhesive layer may have a dielectric constant (Dk) of 2.8 or less, or 2.2 to 2.8 at 5 GHz in a dry state. The adhesive layer may also have a dielectric loss factor (Df) of 0.010 or less, or 0.010 to 0.001 at 5 GHz in a dry state.

The dicarboxylic acid or its acid anhydride may be added to the end of the styrene-ethylene-butylene-styrene copolymer in an amount of 0.1 wt% to 15 wt%, or 0.2 wt% to 10 wt% 0.1% by weight to 15% by weight, or 0.2% by weight to 10% by weight.

Wherein the dicarboxylic acid is selected from the group consisting of maleic acid, phthalic acid, itaconic acid, citraconic acid, alkenylsuccinic acid, cis-1,2,3,6 tetrahydrophthalic acid and 4-methyl-1,2,3,6-tetrahydrophthalic acid And the like.

The styrene-ethylene-butylene-styrene copolymer having 0.1 to 15% by weight of the dicarboxylic acid or its acid anhydride bonded thereto has a weight average molecular weight of 30,000 to 800,000, preferably 20,000 to 200,000, .

The styrene-ethylene-butylene-styrene copolymer in which 0.1 to 15% by weight of the dicarboxylic acid or an acid anhydride thereof is combined may contain 5 to 50% by weight of styrene-derived repeating units. If the content of styrene-derived repeating units in the styrene-ethylene-butylene-styrene copolymer is too small, the heat resistance of the adhesive layer may be significantly lowered, and the dielectric constant and dielectric loss coefficient may be lowered, It is difficult to sufficiently secure the effect of minimizing the size of the image. If the content of styrene-derived repeating units in the styrene-ethylene-butylene-styrene copolymer is too high, compatibility with the epoxy resin may be lowered in the adhesive layer.

The styrene-ethylene-butylene-styrene copolymer in which the dicarboxylic acid or an acid anhydride thereof is bonded in an amount of 0.1 to 15% by weight is added to the adhesive layer in a proportion of 30 By weight to 80% by weight or from 25% by weight to 75% by weight.

On the other hand, the adhesive layer may contain 10 to 80 parts by weight or 20 to 80 parts by weight of an epoxy resin, based on 100 parts by weight of the styrene-ethylene-butylene-styrene copolymer with 0.1 to 15% by weight of the dicarboxylic acid or its acid anhydride. 60 parts by weight.

The epoxy resin enables the adhesive layer to have high heat resistance and mechanical properties. The adhesive layer includes 10 to 80 parts by weight or 20 to 60 parts by weight of the epoxy resin with respect to 100 parts by weight of the styrene-ethylene-butylene-styrene copolymer, and the adhesive layer has a lower dielectric constant and dielectric loss factor .

If the content of the epoxy resin in the adhesive layer is too high as compared with the styrene-ethylene-butylene-styrene copolymer, the adhesive layer may have a high dielectric constant and dielectric loss factor, and resin flow may become excessively large have. If the content of the epoxy resin in the adhesive layer is too small as compared with the styrene-ethylene-butylene-styrene copolymer, the heat resistance and mechanical properties of the adhesive layer may be deteriorated and the adhesive strength itself may decrease.

The epoxy resin may include at least one selected from the group consisting of biphenyl novolak epoxy resin, bisphenol A type epoxy resin and dicyclopentadiene phenol addition reaction type epoxy resin. Preferred examples of the epoxy resin include biphenyl Novolac epoxy resin or dicyclopentadiene phenol addition reaction type epoxy resin.

It is preferable to have an epoxy equivalent of 200 g / eq to 500 g / eq in order to increase the heat resistance of the adhesive layer while lowering the dielectric constant and the dielectric loss coefficient.

On the other hand, the acid anhydride may be selected from the group consisting of styrene-maleic anhydride copolymer, methyltetrahydrophthalic anhydride, phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, At least one compound selected from the group consisting of Methyl Himic Anhydride, NADIC Methyl Anhydride, NADIC Anhydride and Dodecenyl Anhydride.

These acid anhydride-based compounds can ensure a high adhesive strength and heat resistance while lowering the dielectric constant of the adhesive layer, and ensure high storage stability when the adhesive layer is present in a semi-cured state.

Other known curing agents, curing accelerators, curing catalysts or the like greatly increase the permittivity and dielectric loss coefficient of the adhesive layer, while the above-mentioned specific acid anhydride-based compounds are used as the styrene-ethylene-butylene- Epoxy resin so that the dielectric constant of the adhesive layer is 2.8 or less at 5 GHz in the dry state and the dielectric loss factor (Df) can be 0.010 or less at 5 GHz in the dry state.

As the styrene-maleic anhydride copolymer in the acid anhydride-based compound, a styrene-maleic anhydride copolymer having a weight average molecular weight of 1,000 to 50,000, or 5,000 to 25,000 may be used.

The styrene-maleic anhydride copolymer may contain 50 to 95% by weight, or 60 to 90% by weight, of styrene-derived repeating units.

The adhesive resin composition preferably comprises 10 to 80 parts by weight of the acid anhydride compound per 100 parts by weight of the styrene-ethylene-butylene-styrene copolymer in which the dicarboxylic acid or an acid anhydride thereof is contained in an amount of 0.1 to 15 wt% , Or 20 to 60 parts by weight.

If the content of the acid anhydride compound in the adhesive layer is too small, the film properties, heat resistance and mechanical properties of the adhesive layer may be insufficient and it may be difficult to sufficiently lower the dielectric constant and dielectric loss coefficient of the adhesive layer. If the content of the acid anhydride compound in the adhesive layer is too high, hygroscopicity may be increased, heat resistance may be lowered, and the dielectric constant and dielectric loss coefficient of the adhesive layer may be increased.

Specifically, the weight ratio of the epoxy resin to the acid anhydride compound may be 2.0 to 0.05, or 1.5 to 0.10, 1.0 to 0.12, or 0.75 to 0.15. The weight ratio of the epoxy resin to the acid anhydride compound is a weight ratio of the solid content of the acid anhydride compound and the solid content of the epoxy resin. If the weight of the epoxy resin relative to the acid anhydride compound is too high, it may be difficult to sufficiently lower the dielectric constant and dielectric loss coefficient of the adhesive layer and the resin flow may become excessively high. If the weight of the epoxy resin is too low as compared with the acid anhydride compound, the adhesive strength, heat resistance and chemical resistance of the adhesive layer may be lowered.

The adhesive layer may comprise a curing catalyst comprising at least one compound selected from the group consisting of conventionally known curing catalysts, for example imidazole compounds, imine compounds and amine compounds.

Specifically, the adhesive layer may be formed from a coating composition containing the above-mentioned components, and the coating composition forming the adhesive layer may contain 0.1 to 15% by weight of the dicarboxylic acid or an acid anhydride thereof combined with styrene-ethylene- 0.05 to 5 parts by weight, and 0.1 to 2 parts by weight of the curing catalyst may be added to 100 parts by weight of the butylene-styrene copolymer.

The coating composition for forming the adhesive layer may further include an organic solvent in addition to the components contained in the adhesive layer described above. Specifically, the coating composition for forming the adhesive layer may further include 50 to 1,000 parts by weight of an organic solvent per 100 parts by weight of the styrene-ethylene-butylene-styrene copolymer.

The organic solvent adjusts the viscosity of the coating composition forming the adhesive layer to facilitate the production of the adhesive layer. The organic solvent may be used in consideration of specific components and viscosity of the coating composition forming the adhesive layer, and examples thereof include toluene, xylene, propylene glycol monomethyl ether acetate, benzene, acetone, methyl ethyl ketone, tetrahydrofuran , Dimethylformaldehyde, cyclohexanone, methyl cellosolve, methanol, ethanol and the like can be used.

The coating composition for forming the adhesive layer may contain other commonly known additives such as flame retardants or fillers in addition to the above-mentioned components. Examples of the flame retardant include OP-935 (Clarian), an ionic phosphorus flame retardant, and FP series (Fushimi), a non-ionic phosphorus flame retardant. . As the filler, inorganic particles such as silica can be used without limitation, and for example, SFP-30M or SFP-30MHE (DENKA) can be used, and organic fillers such as polypropylene oxide can be used. - inorganic filler may be used.

The thickness of the adhesive layer is not particularly limited and may be appropriately adjusted according to the type and structure of the printed circuit board or the flexible printed circuit board to be applied. For example, the adhesive layer may have a thickness of 1 to 100 [ have.

The bonding sheet may further include a carrier film formed on one surface of the adhesive layer together with the adhesive layer. The specific kind of the carrier film is not limited, and for example, a polyester film, a polyethylene film, a polypropylene film, or a polyethylene naphthalate film can be used. Specifically, a PET film can be used. The thickness of the carrier film is not limited to a great extent and may have a thickness of, for example, 10 mu m to 100 mu m.

The bonding sheet may further include a releasing film or release film formed on one side of the adhesive layer. The releasing paper or release film is not limited to a specific type. For example, a releasing paper coated with polyethylene on one side, a releasing paper coated with polyethylene on one side and polypropylene on the other side, a releasing paper coated with polypropylene on both sides, Polyester-based polymer films, polyethylene-based polymer films, and polypropylene-based polymer films. The thickness of the release paper or the release film is not limited to a great extent. For example, the thickness of the release paper may be 50 to 200 m, and the thickness of the release film may be 5 to 100 m.

According to another embodiment of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: a first flexible metal laminate; A coverlay formed on the first flexible metal laminate; Styrene-ethylene-butylene-styrene copolymer in which dicarboxylic acid or an acid anhydride thereof is contained in an amount of 0.1 to 15% by weight; Epoxy resin; A curing catalyst comprising at least one compound selected from the group consisting of an imidazole compound, an imine compound and an amine compound; And an acid anhydride-based compound, the bonding sheet being formed on the coverlay; And a second flexible metal laminate formed on the bonding sheet.

The inventors of the present invention have found that when the bonding sheet of the specific composition described above is applied to a flexible printed circuit board, the signal transmission loss can be lowered while securing a lower permittivity and a low dielectric loss coefficient, and a short circuit caused by CAF It is possible to provide a more highly integrated flexible circuit board by confirming through experiments that the invention has been completed.

As described above, the bonding sheet includes a styrene-ethylene-butylene-styrene copolymer containing 0.1 to 15% by weight of the dicarboxylic acid or an acid anhydride thereof bonded to the flexible printed circuit board, Ion transition can be minimized and the occurrence of a short circuit due to CAF can be prevented even under a high temperature and high humidity environment.

More specifically, the bonding sheet includes all of the bonding sheet of one embodiment of the invention described above and the adhesive layer included therein.

The flexible printed circuit board including the bonding sheet can minimize the metal ion transition when a voltage is applied, and can prevent a short circuit due to CAF even under high temperature and high humidity environments. Specifically, when a voltage of 50 V is applied to the flexible printed circuit board at 85 ° C and 85% RH, a short circuit due to CAF (Conductive Anodic Filament) may not occur within 1,000 hours.

The first soft metal laminate and the second soft metal laminate may each include a polyimide resin layer and a metal thin film formed on at least one surface of the polyimide resin layer.

The first flexible metal laminate may have a structure in which a metal thin film formed on one or both sides of the polyimide resin layer is formed, and the coverlay may be bonded or laminated on the metal thin film. Also, a signal circuit or the like may be formed on the surface of the metal thin film through a predetermined process.

The polyimide resin contained in the polyimide resin film may have a weight average molecular weight of 3,000 to 600,000, or 50,000 to 300,000. If the weight average molecular weight of the polyimide resin is too small, it is impossible to sufficiently secure the mechanical properties required in the application of the flexible metal laminate or the like. In addition, if the weight average molecular weight of the polyimide resin is too large, the elasticity of the polyimide resin film may be lowered.

The polyimide resin film may have a thickness of 1 占 퐉 to 100 占 퐉.

The polyimide resin film may further contain 5 to 75% by weight of a fluororesin together with the polyimide resin.

Examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoro (ETFE), tetrafluoroethylene-chlorotrifluoroethylene copolymer (TFE / CTFE), ethylene-chlorotrifluoroethylene resin (ECTFE), a mixture of two or more thereof, And the like. The fluororesin may include particles having a longest diameter of 0.05 mu m to 20 mu m, or 0.1 mu m to 10 mu m.

The metal thin film may have a thickness of 1 占 퐉 to 50 占 퐉. The metal thin film may include at least one selected from the group consisting of copper, iron, nickel, titanium, aluminum, silver, gold, and alloys of two or more thereof.

The flexible metal laminate may have a dielectric constant (Dk) in the dry state and 2.2 to 2.8 at 5 GHz. In addition, the soft metal laminate may have a dielectric loss factor (Df) of 0.010 or less at 5 GHz in a dry state.

On the other hand, the coverlay includes an adhesive layer in contact with the first flexible metal laminate; And a polyimide resin film formed on the adhesive layer.

Wherein the adhesive layer of the coverlay is a styrene-ethylene-butylene-styrene copolymer in which 0.1 to 15% by weight of dicarboxylic acid or an acid anhydride thereof is bonded; Epoxy resin; A curing catalyst comprising at least one compound selected from the group consisting of an imidazole compound, an imine compound and an amine compound; And acid anhydride-based compounds.

The coefficient of thermal expansion of the polyimide resin film may be from 15 ppm / K to 20 ppm / K, or from 16 ppm / K to 18 ppm / K, which is similar to a metal thin film, for example, a copper foil.

The adhesive layer of the coverlay may have a thickness of 1 탆 to 200 탆, or 5 탆 to 100 탆, and the polyimide resin film of the coverlay may have a thickness of 1 탆 to 200 탆 or 5 탆 to 100 탆 have.

The flexible printed circuit board includes a second flexible metal laminate formed on the bonding sheet, and the second flexible metal laminate is joined to the cover strip formed on the first flexible metal laminate via the bonding sheet .

The flexible printed circuit board may further include a plurality of soft metal laminates in addition to the first soft metal laminator and the second soft metal laminator. In such a case, a coverlay may be formed on the surface of each flexible metal laminate, and an additional bonding sheet having the same composition as that of the bonding sheet described above is formed on the coverlay. Through this bonding sheet, The laminate can be bonded.

For example, the flexible printed circuit board may include a coverlay formed on the second flexible metal laminate; A second bonding sheet formed on the coverlay formed on the second flexible metal laminate; And a third flexible metal laminate formed on the second bonding sheet.

According to another embodiment of the present invention, a flexible printed circuit board including a bonding sheet according to an embodiment of the present invention may be provided.

The flexible printed circuit board may include structures and components that are commonly known, except as described above with respect to the flexible metal laminate.

According to the present invention, it is possible to reduce transmission loss of a flexible printed circuit board as well as to have a low permittivity and a low dielectric loss coefficient, minimize metal ion transition, and prevent short circuit due to CAF even under high temperature and high humidity environments It is possible to provide a bonding printed sheet and a highly integrated flexible printed circuit board which can prevent occurrence of a short circuit due to CAF even if exposed for a long time under a high temperature and high humidity environment and have high product reliability, low permittivity and low dielectric loss coefficient.

1 is a graph showing a result of conducting a CAF (Conductive Anodic Filament) test on a flexible printed circuit board of Example 1. Fig.

The invention will be described in more detail in the following examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

[Example: Production of Bonding Sheet]

Example 1

(1) Preparation of a resin composition for forming an adhesive layer

200 g of a 25 wt% xylene solution of a styrene-ethylene-butylene-styrene copolymer having maleic anhydride grafted at 1.81 wt% (M1913, product of Asshi Kasei), 70 wt% of biphenyl novolac epoxy resin, 10 g of nadic methy anhydride and 0.1 g of a 25 wt% xylene solution of 2-ethyl-4-methylimidazole were mixed at room temperature to form an adhesive layer (a product of Nippon Kayaku Co., Ltd., epoxy equivalent 288 g / Was prepared.

(2) Production of bonding sheet

The resin composition for forming an adhesive layer was coated on one side of a PET film (carrier film, thickness: 38 mu m, RPK 201, manufactured by Toray Industries, Inc.) and dried at 100 DEG C for 5 minutes to form an adhesive layer of 25 mu m. The inner surface of the release paper (EX-12, manufactured by Lintec) and the outer surface of the adhesive layer were adhered using a roll liner at a temperature of 80 캜 to prepare a bonding sheet.

Example 2

(1) Preparation of a resin composition for forming an adhesive layer

Except that 200 g of a 25 wt% xylene solution of a styrene-ethylene-butylene-styrene copolymer having maleic anhydride grafted at 0.36 wt% (M1911, manufactured by Asahi Kasei) was used to form an adhesive layer Was prepared.

(2) Production of bonding sheet

A bonding sheet was prepared in the same manner as in Example 1, except that the resin composition for adhesive layer formation prepared above was used.

[Comparative Example: Production of Bonding Sheet]

Comparative Example 1

(1) Preparation of a resin composition for forming an adhesive layer

200 g of a 25 wt% xylene solution of a styrene-ethylene-butylene-styrene copolymer having maleic anhydride grafted at 1.81 wt% (M1913, product of Asshi Kasei), 70 wt% of biphenyl novolac epoxy resin, 35.5 g of 4,4'-diamino diphenyl sulfone, 21.5 g of a 25 wt% methyl cellosolve solution of 2- (2-ethylhexyl) diphenyl sulfone, And 0.12 g of a 25 wt% xylene solution of ethyl-4-methylimidazole were mixed at room temperature to prepare a resin composition for forming an adhesive layer.

(2) Production of bonding sheet

A bonding sheet was prepared in the same manner as in Example 1, except that the resin composition for adhesive layer formation prepared above was used.

Comparative Example 2

(1) Preparation of a resin composition for forming an adhesive layer

200 g of a 25 wt% xylene solution of a styrene-ethylene-butylene-styrene copolymer having maleic anhydride grafted at 1.81 wt% (M1913, product of Asshi Kasei), a liquid bisphenol A type epoxy resin (YD-128, epoxy equivalent 187 g / eq manufactured by Kukdo Chemical Co., Ltd.) and 0.5 g of 1,8-diazabicycloundec-7-ene were mixed at room temperature to prepare a resin composition for forming an adhesive layer .

(2) Production of bonding sheet

A bonding sheet was prepared in the same manner as in Example 1, except that the resin composition for adhesive layer formation prepared above was used.

[Production Example: Production of Flexible Printed Circuit Board]

1. Fabrication of flexible metal laminate

(1) Synthesis of thermoplastic polyimide precursor

To a 500 mL round bottom flask was charged 330 g of n-methyl-2-pyrrolidone, 20.0 g of pyromellitic dianhydride (PMDA), 2,2'-bis [4- (4-aminophenoxy) 38.2 g of propane (BAPP) was added and reacted with stirring with a stirrer while flowing nitrogen at 50 캜 for 10 hours to obtain a thermoplastic polyamic acid solution having a viscosity of 12,000 cP.

(2) Synthesis of precursors of low-dielectric polyimide in which fluorine resin (PTFE) is dispersed

1 L of a polyethylene bottle was filled with nitrogen, 600 g of n-methyl-2-pyrrolidone, 200 g of polytetrafluoroethylene micropowder (PTFE micro powder (particle size: about 0.2 to 3.0 탆) 600 g of beads having a diameter of 2 mm and 10.0 g of a polyester dispersant were placed and stirred in a high-speed ball milling apparatus for 12 hours.

50 g of a solution in which the PTFE micropowder was dispersed in a 500 ml round bottom flask, 260 g of n-methyl-2-pyrrolidone, 25.5 g of pyromellitic dianhydride, 2,2'-bis (trifloro Methyl) -4,4'-diaminobiphenyl, and 5.0 g of 2,2'-dimethyl-4,4'-diaminobiphenyl were charged and stirred with a stirrer while flowing nitrogen gas at 50 ° C. for 10 hours To obtain a low dielectric polyamic acid solution having a viscosity of 26,000 cP.

(3) Fabrication of flexible metal laminate

The thermoplastic polyamic acid solution prepared above was coated on a copper foil (thickness: 12 占 퐉) to have a final thickness of 2.0 占 퐉 and dried at 100 占 폚 for 5 minutes. The resulting low-k polyamic acid solution was coated on the dried polyamic acid so that the final thickness of the prepared low-k polyamic acid solution became 21 탆, followed by drying at 100 캜 for 10 minutes. The thermoplastic polyamic acid solution prepared above was coated on the dried low-k polyamic acid to a final thickness of 2.0 탆 and then dried at 100 캜 for 5 minutes.

The laminate formed after the drying was placed in an oven, gradually heated from 100 deg. C, and thermoset for 30 minutes at a temperature of about 300 deg. C and a nitrogen atmosphere. After the thermosetting, a matte surface of a copper foil (thickness: 12 mu m) was brought into contact with the other surface of the coating layer of the thermoplastic polyamic acid solution and pressed at 400 DEG C to produce a flexible metal laminate having copper foil on both sides of the outermost surface Respectively.

2. Manufacture of flexible printed circuit board

The resin composition for forming an adhesive layer of Example 1 was coated on one side of a polyimide film (LN050, product of SKC KOLON PI, thickness 12 占 퐉) to a thickness of 15 占 퐉 and dried at 100 占 폚 for 5 minutes, . A copper foil on one side of the manufactured flexible metal laminate was selectively etched to form a signal line, and then a signal line was formed on the adhesive side of the coverlay. Then, Lt; RTI ID = 0.0 > MPa < / RTI > for 1 hour.

Then, the release paper and the carrier film were removed from the bonding sheet prepared in Examples 1 and 2 and Comparative Examples 1 and 2, and the resultant laminate was laminated on the polyimide film of the coverlay. Then, the other soft metal laminate Was laminated on the bonding sheet, and then a pressure of 3 MPa was applied at 160 캜 for 1 hour to thermally cure the flexible printed circuit board.

[Experimental Example]

1. Experimental Example 1: Measurement of dielectric constant and dielectric loss coefficient of a bonding sheet

The dielectric constant and dielectric loss coefficient of the bonding sheet prepared in the above example were measured as follows, and the results are shown in Table 1 below.

Specifically, the permittivity of the bonding sheet prepared in the above example was measured by a split post dielectric resonance (SPDR) method at 25 ° C and 50% RH using a Agiletn E5071B ENA apparatus at a dielectric constant of 5 GHz and dielectric loss coefficient Were measured.

2. Adhesion measurement with PI

The bonding sheet prepared in the above example was laminated between a polyimide film (LN050) and a polyimide film (LN050) according to the criteria of IPC-TM-650 2.4.9D, and a pressure of 3 MPa was applied at 160 DEG C for 1 hour The adhesive strength between the polyimide film and the bonding sheet was measured using a Universal Testing Machine at room temperature after curing the bonding sheet.

3. Heat resistance measurement

Based on the criteria of IPC-TM-650 2.4.13, the heat-resisting property of the flexible printed circuit board manufactured in the above production example was measured by Floating method at 288 캜 using a solder bath. As a result of the measurement, the occurrence of bubbles was evaluated as NG, and the case where no bubbles were generated was defined as PASS.

4. Chemical resistance measurement

Based on the criteria of IPC-TM-650 2.3.2, the flexible printed circuit board manufactured in the above production example was immersed in each organic solvent for a predetermined time using a universal testing machine, and then the adhesive force of the bonding sheet was measured To measure the chemical resistance. PASS was evaluated when the adhesive strength was maintained or decreased to 20% or less, and evaluated as NG when the adhesive strength reduction exceeded 20%.

5. Measurement of transmission loss

For the flexible printed circuit board manufactured in the above production example, transmission loss was measured on a transmission line of 10 cm using Agilent's Network Analyzer E5071C equipment based on the method of manufacturing the stripline.

Bonding sheet in flexible printed circuit board Example 1 Example 2 Comparative Example 1 Comparative Example 2 Permittivity (Dk) @ 5 GHz 2.6 2.6 3.1 2.5 Dielectric loss factor (Df) @ 5 GHz 0.006 0.006 0.015 0.003 Adhesion to PI 1.1 1.0 1.1 1.2 Heat resistance PASS PASS PASS NG Chemical resistance PASS PASS PASS NG Transmission Loss @ 10GHz -5.4 dB -5.4 dB -6.4 dB -5.2 dB

As shown in Table 1, the low-dielectric-bonding sheets produced in Examples 1 and 2 had a lower dielectric constant and dielectric loss coefficient than the bonding sheets of Comparative Examples 1 and 2, Low transmittance loss can be realized, and the overall physical properties of adhesion, heat resistance and chemical resistance to polyimide films are relatively excellent.

Claims (25)

Styrene-ethylene-butylene-styrene copolymer in which dicarboxylic acid or an acid anhydride thereof is contained in an amount of 0.1 to 15% by weight; Epoxy resin; A curing catalyst comprising at least one compound selected from the group consisting of an imidazole compound, an imine compound and an amine compound; And an adhesive layer comprising an acid anhydride-based compound.
The method according to claim 1,
Wherein the adhesive layer has a dry state and a dielectric constant (Dk) of 2.8 or less at 5 GHz.
The method according to claim 1,
Wherein the content of sodium or sodium ions in the adhesive layer is not more than 100 ppmw.
The method according to claim 1,
Wherein the styrene-ethylene-butylene-styrene copolymer having 0.1 to 15% by weight of the dicarboxylic acid or its acid anhydride bonded thereto has a weight average molecular weight of 30,000 to 800,000.
The method according to claim 1,
Wherein the styrene-ethylene-butylene-styrene copolymer comprising 0.1 to 15% by weight of the dicarboxylic acid or an acid anhydride thereof comprises 5 to 50% by weight of styrene-derived repeating units.
The method according to claim 1,
Wherein the epoxy resin comprises at least one member selected from the group consisting of biphenyl novolac epoxy resin, bisphenol A type epoxy resin and dicyclopentadiene phenol addition reaction type epoxy resin.
The method according to claim 1,
The acid anhydride compound may be at least one selected from the group consisting of styrene-maleic anhydride copolymer, methyltetrahydrophthalic anhydride, phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, Wherein the bonding sheet comprises at least one compound selected from the group consisting of Methyl Himic Anhydride, NADIC Methyl Anhydride, NADIC Anhydride and Dodecenyl Anhydride.
The method according to claim 1,
Based on 100 parts by weight of the styrene-ethylene-butylene-styrene copolymer containing 0.1 to 15% by weight of the dicarboxylic acid or an acid anhydride thereof,
10 to 80 parts by weight of the epoxy resin;
10 to 80 parts by weight of an acid anhydride-based compound; And
0.05 to 5 parts by weight of a curing catalyst comprising at least one compound selected from the group consisting of an imidazole compound, an imine compound and an amine compound.
The method according to claim 1,
Wherein the weight ratio of the epoxy resin to the acid anhydride compound is 2.0 to 0.05.
The method according to claim 1,
Wherein the bonding sheet further comprises a carrier film formed on one surface of the adhesive layer.
The method according to claim 1,
Wherein the bonding sheet further comprises a release film formed on one surface of the adhesive layer.
A first flexible metal laminate;
A coverlay formed on the first flexible metal laminate;
Styrene-ethylene-butylene-styrene copolymer in which dicarboxylic acid or an acid anhydride thereof is contained in an amount of 0.1 to 15% by weight; Epoxy resin; A curing catalyst comprising at least one compound selected from the group consisting of an imidazole compound, an imine compound and an amine compound; And an acid anhydride-based compound, the bonding sheet being formed on the coverlay; And
And a second flexible metal laminate formed on the bonding sheet.
13. The method of claim 12,
Wherein a short circuit caused by CAF (Conductive Anodic Filament) does not occur within 1,000 hours when a voltage of 50 V is applied to the flexible printed circuit board at 85 ° C and 85% RH.
13. The method of claim 12,
Wherein the first flexible metal laminate comprises a polyimide resin layer and a metal thin film formed on at least one side of the polyimide resin layer.
13. The method of claim 12,
Wherein each of the first soft metal laminate and the second soft metal laminate comprises 30 to 95% by weight of a polyimide resin; And a polyimide resin layer containing 5 to 70% by weight of fluoric resin particles; And a metal thin film.
16. The method of claim 15,
Wherein said polyimide resin layer has a permittivity of 2.7 or less at 5 GHz and an environment of 25 캜 and 50% RH.
16. The method of claim 15,
Wherein the polyimide resin has a weight average molecular weight of 1,000 to 500,000.
16. The method of claim 15,
Wherein the maximum diameter of each of the fluororesin particles is 0.05 占 퐉 to 20 占 퐉.
16. The method of claim 15,
The polyimide resin layer has a thickness of 1 탆 to 100 탆,
Wherein the metal thin film has a thickness of 1 占 퐉 to 50 占 퐉.
13. The method of claim 12,
Wherein the coverlay comprises an adhesive layer in contact with the first flexible metal laminate; And a polyimide resin film formed on the adhesive layer.
21. The method of claim 20,
Wherein the adhesive layer of the coverlay is a styrene-ethylene-butylene-styrene copolymer in which 0.1 to 15% by weight of dicarboxylic acid or an acid anhydride thereof is bonded; Epoxy resin; A curing catalyst comprising at least one compound selected from the group consisting of an imidazole compound, an imine compound and an amine compound; And an acid anhydride-based compound.
21. The method of claim 20,
Wherein the polyimide resin film has a thermal expansion coefficient of 15 ppm / K to 20 ppm / K.
21. The method of claim 20,
Wherein the adhesive layer of the coverlay has a thickness of 1 占 퐉 to 200 占 퐉,
Wherein the polyimide resin film of the coverlay has a thickness of 1 占 퐉 to 200 占 퐉.
13. The method of claim 12,
A coverlay formed on the second flexible metal laminate;
A second bonding sheet formed on the coverlay formed on the second flexible metal laminate; And
And a third flexible metal laminate formed on the second bonding sheet.
A flexible printed circuit board comprising the bonding sheet of claim 1.

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