KR20190098471A - Adhesive composition for flexible printed circuit board excellent in adhesion and heat radiation - Google Patents

Abstract

The present invention relates to an adhesive composition for a flexible printed circuit board excellent in adhesive strength and heat dissipation and to a manufacturing method thereof and, more specifically, to an adhesive composition for a flexible printed circuit board excellent in adhesive strength and heat dissipation, which mixes 40 to 60 parts by weight of a thermally conductive filler with respect to 100 parts by weight of an adhesive mixture consisting of 40 to 60 wt% of an epoxy resin, 25 to 50 wt% of a poly vinyl butyral (PVB) resin, 5 to 10 wt% of an acrylonitrile butadiene rubber, and 15 to 20 wt% of solvents, and to a manufacturing method thereof.

Description

Adhesive composition for flexible printed circuit board excellent in adhesion and heat dissipation

The present invention relates to an adhesive composition for a flexible printed circuit board, and more particularly, to an adhesive mixture composed of an epoxy resin, a poly vinyl butyral (PVB) resin, an acrylonitrile butadiene rubber, a solvent, and a curing agent, and a thermally conductive filler. It relates to an adhesive composition for a flexible printed circuit board excellent in adhesive strength and heat radiation.

Recently, with the trend of integration, miniaturization, thin film, high density, and high bending of electronic products, the necessity of printed circuit board (PCB) that can be easily installed even in a narrow space has increased. Accordingly, a flexible printed circuit board (FPCB) has been developed, which is capable of miniaturization, high density, and repeatability. Since the flexible printed circuit board can be attached and inserted in a relatively narrow space, it is possible to effectively use three-dimensional space in a component case in a limited space. The demand for such flexible printed circuit boards is rapidly increasing due to the rapid increase in the use of mobile phones, DVDs, digital cameras, PDPs, and the like.

A typical flexible printed circuit board is a flexible base film and a circuit wiring layer made of a plastic resin (for example, polyimide or polyester) having high heat resistance and excellent electrical and mechanical properties, and a metal foil is patterned, and an adhesive layer is formed on the base. After bonding to one side of the film, the metal foil is produced in the form of a completely laminated sheet.

Such a flexible printed circuit board includes a cover film or a bonding plate, and the cover film is to protect metal foil, which is a circuit wiring layer of the flexible printed circuit board, and to improve flexibility, and the bonding plate simultaneously connects two flexible printed circuit boards. By combining, it is used to manufacture a multilayer flexible printed circuit board. In the flexible printed circuit board, various electronic devices are mounted on it by surface-mount technology. In order for the flexible printed circuit board to be used as a surface-mount product substrate material, the cover film and the bonding plate constituting the flexible printed circuit board have excellent processability. In addition to having excellent flexibility, high heat resistance and good electrical properties, it should have good interfacial adhesion.

The process of manufacturing the flexible printed circuit board or the process of mounting the component includes a hot pressing process, a soldering process, and the like. In order to perform the above process reliably, an adhesive composition excellent in all of heat resistance, adhesion, bending resistance, and conductivity Or there is a situation that the demand for the adhesive sheet product is greatly increased, the conventional adhesive composition or adhesive sheet has a limit to satisfy all the above properties.

In general, the adhesive sheet is made from a composition containing a modified rubber composed of acrylic acid / acrylonitrile / butadiene, an epoxy resin, an epoxy curing agent, and an epoxy curing accelerator, but at a high temperature and high pressure, the adhesive strength and the lead-free soldering heat resistance are low (KR2001-). 0083759A, JP2006-342238A). In order to improve this, a certain amount of curing accelerator has been added, but there is a limit in securing the desired level of physical properties. In addition, in the case of using a general acrylic adhesive, the reinforcement plate can be easily adhered even under a low pressure press condition for a short time, but if a stress such as gravity exists, the flow of the adhesive resin occurs over time and the circuit material and the reinforcement plate Positional change occurs and there is a limitation in the use of high reliability reinforcing plate. In order to compensate for this, an acrylic resin having an epoxy group may be used, and even in this case, it is difficult to obtain desired soldering heat resistance and there are many storage constraints (KR2007-0104564A). In addition, some latent curing agents may be used, but the price is very expensive, and there is a problem in that it does not yet overcome lead-free soldering heat resistance (JP2008-156570A).

Therefore, there is a need for an adhesive composition or adhesive sheet having excellent levels of adhesion and soldering heat resistance that can sufficiently cope with high temperature and high pressure processes.

Accordingly, the present inventors have endeavored to develop an adhesive composition for a flexible printed circuit board having excellent thermal conductivity, adhesion, and heat dissipation. As a result, an adhesive mixture consisting of epoxy resin, polyvinyl butyral resin, acrylonitrile butadiene rubber, solvents, and curing agent The adhesive composition prepared by mixing the thermally conductive filler in the adhesive composition including the epoxy resin and the polyvinyl butyral resin, and the adhesive composition including the epoxy resin and the acrylonitrile rubber, are compared with each other. The present invention was completed by confirming that the heat resistance was remarkably excellent.

An object of the present invention is 40 to 60 weight of the thermally conductive filler based on 100 parts by weight of the adhesive mixture containing an epoxy resin, poly vinyl butyral (PVB) resin, acrylonitrile butadiene rubber, solvents, and curing agents The present invention provides a mixed adhesive composition for a flexible printed circuit board having excellent adhesion and heat dissipation, and a manufacturing method thereof.

Another object of the present invention is to provide an adhesive sheet (or adhesive film) excellent in adhesive strength and heat dissipation, including the adhesive layer prepared using the adhesive composition for a flexible printed circuit board according to the present invention, and the adhesive sheet (or adhesive film) It is to provide a flexible printed circuit board comprising.

In order to achieve the above object, the present invention is thermally conductive with respect to 100 parts by weight of an adhesive mixture comprising an epoxy resin, a poly vinyl butyral (PVB) resin, an acrylonitrile butadiene rubber, a solvent, and a curing agent. Provided is an adhesive composition for a flexible printed circuit board, in which 40 to 60 parts by weight of a filler is mixed.

At this time, the adhesive composition for a flexible printed circuit board is epoxy resin 40 to 60% by weight, polyvinyl butyral resin 25 to 50% by weight, acrylonitrile butadiene rubber 5 to 10% by weight, solvents 15 to 20% by weight, curing agent With respect to 100 parts by weight of the adhesive mixture consisting of 1 to 5% by weight, it may be made by mixing 40 to 60 parts by weight of the thermally conductive filler.

The epoxy resin may be used one or a mixture of two or more of bisphenol A epoxy resin, phenol novolak-type epoxy resin, cresol novolak-type epoxy resin.

The acrylonitrile butadiene rubber may use one or more selected from acrylonitrile content of 10 to 50% by weight.

The solvent may be used one or more selected from the group consisting of methanol, ethanol, dimethylformamide, methyl cellulsolve, methyl ethyl ketone, butanone, toluene and the like.

The curing agent is diethylene triamine, triethylene tetraamine, diethylamino propyl amine, mentane diamine, meta xylenediamine, isophorone diamine, dicyanidiamide, 2-ethylimidazole, 2-phenyl-4-methyl-5 One or more selected from hydroxy methimidazole, 2,4,5-tribromoimidazole can be used.

In addition, the present invention

1) dissolving polyvinyl butyral (PVB) resin and acrylonitrile butadiene rubber in solvents;

2) preparing an adhesive mixture by adding an epoxy resin and a curing agent to the solution of step 1); And

3) adding a thermally conductive filler to the adhesive mixture of step 2);

Provided is a method of manufacturing an adhesive composition for a flexible printed circuit board.

At this time, 40 to 60% by weight of epoxy resin, 25 to 50% by weight of polyvinyl butyral resin, 5 to 10% by weight of acrylonitrile butadiene rubber, 15 to 20% by weight of solvents, 1 to 5% by weight of curing agent With respect to 100 parts by weight of the adhesive mixture consisting of, it may be made by mixing 40 to 60 parts by weight of the thermally conductive filler.

In the above production method, the epoxy resin may be used one or a mixture of two or more of bisphenol A epoxy resin, phenol novolak-type epoxy resin, cresol novolak-type epoxy resin.

In the above production method, the acrylonitrile butadiene rubber may use one or more selected from those having an acrylonitrile content of 10 to 50% by weight.

In addition, the present invention provides an adhesive sheet comprising an adhesive layer formed by applying the adhesive composition according to the present invention.

In addition, the present invention provides a flexible printed circuit board comprising the adhesive sheet according to the present invention.

According to the adhesive composition for a flexible printed circuit board of the present invention, it is possible to manufacture a flexible printed circuit board having excellent adhesive strength and excellent heat dissipation and voltage resistance.

By using polyvinyl butyral resin and acrylonitrile butadiene rubber together in the epoxy resin according to the present invention, the epoxy resin alone, a mixture of epoxy resin and polyvinyl butyral resin, or a mixture of epoxy resin and acrylonitrile butadiene rubber It showed high adhesion and heat dissipation.

In one experimental example of the present invention, in the case of using the adhesive composition according to the present invention, the comparative examples of the conventionally reported adhesive composition in the adhesive force may be limited to about 2 kgf / cm, but the embodiments of the present invention is 3 kgf / cm In addition, it was confirmed that the comparative examples of the previously reported adhesive composition in heat dissipation are less than 70 W / mk, while the examples of the present invention have a level much higher than 70 W / mk. As a result of the self test, when the thermal conductivity is increased by 5 ~ 10 W / mk, the actual LED light source temperature is reduced by 6 ~ 10 ℃ (average 8 ℃), which can improve the life of LED products by more than 20%.

Hereinafter, the present invention will be described in detail.

The present invention is made by mixing a thermally conductive filler in an adhesive mixture consisting of an epoxy resin, poly vinyl butyral (PVB), acrylonitrile butadiene rubber, solvents, and a curing agent, thereby forming an adhesive composition for a flexible printed circuit board. to provide.

The adhesive composition for a flexible printed circuit board is composed of a mixture of 40 to 60 parts by weight of a thermally conductive filler based on 100 parts by weight of an adhesive mixture composed of an epoxy resin, a polyvinyl butyral resin, an acrylonitrile butadiene rubber, a solvent, and a curing agent. Can be.

The adhesive composition for a flexible printed circuit board may include 40 to 60 wt% of epoxy resin, 25 to 50 wt% of PVB resin, 5 to 10 wt% of acrylonitrile butadiene rubber, 15 to 20 wt% of solvents, and 1 to 5 wt% of curing agent. It can be configured as.

As the epoxy resin, it is preferable to use any one or a mixture of two or more selected from the group consisting of bisphenol A type epoxy resins, phenol novolak type epoxy resins, and cresol novolak type epoxy resins. More preferably, it is preferable to mix and use a bisphenol-A epoxy resin and a phenol novolak-type epoxy resin.

At this time, the bisphenol A epoxy resin is preferably added in an amount of 80 to 90% by weight based on 100 parts by weight of the total epoxy resin. When the bisphenol A type epoxy resin is added in less than 80% by weight, there is a fear that the adhesive strength is lowered, and when the bisphenol A epoxy resin is added in excess of 90% by weight, the bridging density may increase due to an increase in crosslinking density.

The phenol novolak-type epoxy resin is preferably added in 10 to 20% by weight based on 100 parts by weight of the total epoxy resin. If the phenol novolak-type epoxy resin is added in less than 10% by weight, there is a fear that the heat resistance is lowered. When the phenol novolac-type epoxy resin is added in excess of 20% by weight, the molecular weight and viscosity are increased, there is a fear that workability and solvent resistance is lowered.

The mixed epoxy resin is preferably used 40 to 60% by weight of 100 parts by weight of the adhesive mixture. If the mixed epoxy resin is added less than 40% by weight, the heat resistance is lowered, the film formation of the basic adhesive is impossible, the adhesion may be greatly reduced. There is a fear that the brittleness of the film is increased.

The polyvinyl butyral resin is not particularly limited in kind, but it is preferable to use a resin prepared by adding butyl aldehyde having a purity of 99% or more to a polyvinyl alcohol having a degree of polymerization of 500 to 1500 under an acid catalyst. More preferably, the polyvinyl butyral resin is added in an amount of 25 to 50 wt% in 100 parts by weight of the adhesive mixture. When the polyvinyl butyral resin is added in less than 25% by weight, the content of the polyvinyl butyral resin as a binder is low, and thus the adhesive strength is lowered.

The acrylonitrile butadiene rubber is preferably used at least one acrylonitrile butadiene rubber selected from the acrylonitrile content of 10 to 50%. More preferably, the acrylonitrile content is 25 to 30%. If the acrylonitrile content is less than 25%, the tensile strength and heat resistance is low, and if the acrylonitrile content is more than 30%, there is a fear that the adhesive strength is lowered and the mechanical strength is increased, thereby reducing the flexibility. The acrylonitrile butadiene rubber is preferably added 5 to 10% by weight in 100 parts by weight of the adhesive mixture. When the acrylonitrile butadiene rubber is added in less than 5% by weight, the adhesive strength is lowered, and when the acrylonitrile butadiene rubber is added in an amount of more than 10% by weight, the flowability is lowered due to the aggregation of rubbers and the heat resistance of the adhesive may be lowered due to the low glass transition temperature.

The solvents are preferably one or more selected from the group consisting of methanol, ethanol, dimethylformamide, methyl cellulsolve, methyl ethyl ketone, butanone, toluene and the like. More preferably butanone is preferred. The solvent is preferably used 15 to 20% by weight of 100 parts by weight of the adhesive mixture. When the solvent is added in less than 15% by weight, the resins used may not be sufficiently dissolved, but when the solvent is used in excess of 20% by weight, the solid content of the adhesive may be lowered, thereby deteriorating workability.

The curing agent is diethylene triamine, triethylene tetraamine, diethylamino propyl amine, mentane diamine, meta xylenediamine, isophorone diamine, dicyanidiamide, 2-ethylimidazole, 2-phenyl-4-methyl-5 Preference is given to using one or more selected from hydroxy methimidazole and 2,4,5-tribromoimidazole. More preferably, dicyandiamide is used. The curing agent is preferably used 1 to 5% by weight of 100 parts by weight of the adhesive mixture. When the curing agent is added in less than 1% by weight, there is little fear that the resin undergoes hardening reaction of the resin, so that the heat resistance is lowered. When the curing agent is more than 5% by weight, the heat resistance may decrease due to the residual curing agent.

The thermally conductive filler is gold, silver, copper, nickel, iron and silver coated copper powder (Ag coated Cu), silver coated nickel powder and silver coated iron powder (Ag coated Fe) excellent in thermal conductivity ), It is preferable to use at least one powder selected from the group consisting of silver coated glass (Ag coated glass). Among them, silver-coated glass powder having a low specific gravity, excellent electrical contact forming ability between filler particles, and relatively low price increase factors according to the amount of filler added in order to maintain a relatively slow sedimentation rate when mixed with the binder resin composition is preferable. Do. The thermally conductive filler in the form of particles may have a spherical shape, a plate shape, a branch shape, an amorphous shape, and the like, and it is preferable to use a powder in the form of a plate from the viewpoint of electrical contact formation. The thermally conductive filler is preferably added 40 to 60 parts by weight based on 100 parts by weight of the total adhesive mixture. When the thermally conductive filler is added in an amount of less than 40% by weight, the thermal conductivity is reduced. When the thermally conductive filler is more than 60% by weight, the content of the filler is higher than that of the binder resin, so that the thermal conductivity is improved, but the adhesive force is decreased and the viscosity is increased. have.

The adhesive composition for a flexible printed circuit board according to the present invention may be used for manufacturing a flexible printed circuit board having excellent adhesive strength and excellent heat dissipation characteristics and voltage resistance.

In the adhesive composition for a flexible printed circuit board according to the present invention, an epoxy resin alone, an epoxy resin and a polyvinyl butyral resin mixture, and / or an epoxy is used by using a polyvinyl butyral resin and an acrylonitrile butadiene rubber together in an epoxy resin. Compared to the resin and acrylonitrile butadiene rubber mixture, it showed much higher adhesion and heat dissipation.

Specifically, in one experimental example of the present invention, in the case of using the adhesive composition according to the present invention, the conventionally reported adhesive composition appeared to be over 3 kgf / cm while the limit of 2 kgf / cm appeared to be limited in the adhesive force, It was found that the degree of heat dissipation of the conventionally reported adhesive composition was 67 W / mk, while well above 70 W / mk. As a result of the self test, when the thermal conductivity is increased by 5 ~ 10 W / mk, the actual LED light source temperature is reduced by 6 ~ 10 ℃ (average 8 ℃), which can improve the life of LED products by more than 20%.

In addition, the present invention

1) dissolving polyvinyl butyral (PVB) resin and acrylonitrile butadiene rubber in solvents;

2) preparing an adhesive mixture by adding an epoxy resin and a curing agent to the solution of step 1); And

3) adding a thermally conductive filler to the adhesive mixture of step 2);

Provided is a method of manufacturing an adhesive composition for a flexible printed circuit board.

In the above production method, 40 to 60% by weight of epoxy resin, 25 to 50% by weight of polyvinyl butyral resin, 5 to 10% by weight of acrylonitrile butadiene rubber, 15 to 20% by weight of solvents, 1 to 5% by weight of hardener With respect to 100 parts by weight of the adhesive mixture consisting of, it may be made by mixing 40 to 60 parts by weight of the thermally conductive filler.

In the above production method, the epoxy resin may be used one or a mixture of two or more of bisphenol A epoxy resin, phenol novolak-type epoxy resin, cresol novolak-type epoxy resin.

In the above production method, the acrylonitrile butadiene rubber may be used at least one selected from the acrylonitrile (acrylonitrile) content of 10 to 50% by weight.

In addition, the present invention provides an adhesive sheet comprising an adhesive layer formed by applying the adhesive composition according to the present invention.

In addition, the present invention provides a flexible printed circuit board comprising the adhesive sheet according to the present invention.

The adhesive layer made of the adhesive composition for a flexible printed circuit board having excellent adhesive strength and heat dissipation according to the present invention is not particularly limited in thickness or shape, and can be appropriately determined according to the use site or the purpose of use.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples.

However, the following Examples and Experimental Examples are only intended to illustrate the present invention, and the scope of the present invention should not be construed as being limited to the following Examples and Experimental Examples.

Accordingly, one of ordinary skill in the art to which the present invention pertains can understand that various modifications, modifications, and applications of the following examples and experimental examples are possible within the scope of the technical idea derived from the matters described in the appended claims. There will be.

< Example  1>

<1-1> Poly  Vinyl Butyral Resin Manufacture

The polyvinyl butyral resin was added 6.5 g of 5 wt% hydrochloric acid to 100 g of 10 wt% aqueous solution of polyvinyl alcohol having a degree of polymerization of 1500, and then stirred, and 1.5 g of purity 99% butyl aldehyde was added thereto, followed by cooling the mixture to 15 ° C. 4 g of butyl aldehyde was further added while stirring. The mixture was heated to 40 ° C. at a rate of 15 ° C. in 1 hour, and then reacted at 40 ° C. for 4 hours to terminate the reaction. To remove the unreacted product from the reaction product, filtration was performed using distilled water as a solvent and then dried in an oven at 30 ° C. for 24 hours to prepare a polyvinyl butyral resin.

<1-2> Preparation of an adhesive composition for a flexible printed circuit board

10 wt% of acrylonitrile butadiene rubber (30% of acrylonitrile group) and 25 wt% of polyvinyl butyral resin prepared according to Example 1 were dissolved together in 20 wt% of butanone. Then, 40% by weight of epoxy mixed with bisphenol A epoxy (A) and phenol novolac epoxy (P) with A: P = 8: 2 and 5% by weight of dicyandiamide as a curing agent were added. The adhesive composition for a flexible printed circuit board according to the present invention was prepared by adding 40 wt% of silver coated glass powder in the form of a plate with a thermally conductive filler to the adhesive mixture thus prepared.

<1-3> Metal Copper Clad Laminate  Psalm Fabrication

In order to check the physical properties of the adhesive composition, the copper foil / polyimide film / copper foil was applied to the copper surface of the laminated laminated copper clad laminate (FCCL) 20 ㎛ thickness and dried at 150 ℃ for 5 minutes to apply the adhesive A copper foil was prepared, and an aluminum plate was placed thereon, followed by hot pressing for 1 hour at 170 ° C. at a pressure of 1 Mpa to prepare a metal copper clad laminate (MCCL) specimen.

< Example  2 to 4 and Comparative example  1 to 3

Specimens were prepared in the same manner as in <Example 1>, except that the adhesive composition was blended in the amount shown in Table 1 below.

Item Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Epoxy
Suzy Bisphenol A 32 40 16 32 32 48 32 Phenolic Novolac 8 - 4 8 8 12 8 Polyvinyl butyral
Suzy 25 25 45 25 25 - 25 Acrylonitrile Butadiene Rubber 10 10 10 10 - 10 10 Hardener 5 5 5 5 5 5 5 solvent 20 20 20 20 20 20 20 Thermal conductivity
filler Ag coated glass 40 40 40 60 40 40 - Manganese Dioxide (MnO ₂ ) - - - - - - 40

< Experimental Example  1>

<1-1> Thermal conductivity

MCCL specimens were measured using a NETZSCH LFA Analysis instrument, a thermal conductivity analyzer according to ASTM E 1461.

<1-2> Peel strength

After cutting the MCCL specimen to a width of 10 mm and a length of 150 mm, separate the copper foil and the aluminum plate on the top of the specimen. After pulling five times at the speed, the average was measured with the remaining three except for the highest and lowest values.

<1-3> Solder floating

The MCCL specimens were cut into 50 mm in width and 50 mm in length and immersed in a solder bath heated to 288 ° C. for 30 seconds to verify that there was no swelling and peeling and no significant change in appearance.

OK: no bubble or change of appearance

N.G: Deformation of bubbles or appearance

<1-4> Breakdown Voltage

MCCL specimens were evaluated by increasing the voltage from 0.5 KV / sec to 10 KV / sec at a constant rate in accordance with ASTM D 149 (Test condition A).

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Thermal conductivity 76 W / m.k 74 W / m.k 74 W / m.k 75 W / m.k 65 W / m.k 67 W / m.k 35 W / m.k Adhesion 3.7 kgf / cm 3.9 kgf / cm 2.6 kgf / cm 2.8 kgf / cm 1.5 kgf / cm 1.8 kgf / cm 2.1 kgf / cm soldering
Heat resistance OK N.G OK N.G N.G OK OK Breakdown
Voltage 5.5 KV 4.5 KV 4.8 KV 4.3 KV 3.8 KV 4.5 KV 5.4 KV

As a result, as shown in the above [Table 2], due to the use of polyvinyl butyral resin and acrylonitrile butadiene rubber, a much higher adhesion than that used by epoxy resin alone was obtained.

Through this, using the adhesive composition prepared according to the present invention was able to significantly improve the adhesion and heat dissipation of the FPCB.

Claims (9)

40 to 60 parts by weight of a thermally conductive filler mixed with 100 parts by weight of an adhesive mixture containing an epoxy resin, a poly vinyl butyral (PVB) resin, an acrylonitrile butadiene rubber, a solvent, and a curing agent. Adhesive composition for printed circuit boards.
The method according to claim 1,
The adhesive mixture comprises 40 to 60% by weight of epoxy resin, 25 to 50% by weight of PVB resin, 5 to 10% by weight of acrylonitrile butadiene rubber, 15 to 20% by weight of solvents and 1 to 5% by weight of curing agent. Adhesive composition for flexible printed circuit boards.
The method according to claim 1,
The epoxy resin is an adhesive composition for a flexible printed circuit board, characterized in that one or two or more selected from the group consisting of bisphenol A epoxy resin, phenol novolak-type epoxy resin and cresol novolak-type epoxy resin.
The method according to claim 1,
The polyvinyl butyral resin is an adhesive composition for a flexible printed circuit board prepared by adding butyl aldehyde having a purity of 99% or more to a polyvinyl alcohol having a polymerization degree of 500 to 1500 under an acid catalyst.
The method according to claim 1,
The acrylonitrile butadiene rubber is an adhesive composition for a flexible printed circuit board, characterized in that it contains 10 to 50% by weight of acrylonitrile.
1) dissolving polyvinyl butyral (PVB) resin and acrylonitrile butadiene rubber in solvents;
2) preparing an adhesive mixture by adding an epoxy resin and a curing agent to the solution of step 1); And
3) adding a thermally conductive filler to the adhesive mixture of step 2);
Method for producing an adhesive composition for a flexible printed circuit board.
The method according to claim 6,
Flexible printed circuit, characterized in that 40 to 60% by weight of epoxy resin, 25 to 50% by weight of PVB resin, 5 to 10% by weight of acrylonitrile butadiene rubber, 15 to 20% by weight of solvents and 1 to 5% by weight of hardener The manufacturing method of the adhesive composition for board | substrates.
Adhesive sheet comprising an adhesive layer formed by applying the adhesive composition of any one of claims 1 to 5.
A flexible printed circuit board comprising the adhesive sheet of claim 9.