KR20120059011A - Adhesive composition having high peel strength and adhesive sheet for attaching plate of reinforce on fpcb using the same - Google Patents

Abstract

PURPOSE: An adhesive composition is provided to have high adhesive strength with a reinforcing plate in spite of maintaining excellent long-term storage ability like an acrylic adhesive under quick press condition. CONSTITUTION: An adhesive composition comprises polyurethane urea resin-containing solution of which acid value is 5-50 mg KOH/g, obtained by reaction of an amine compound, and a urethane-based prepolymer with an isocyanate terminal group; and an isocyanate hardener-containing solution of which both sides are blocked. An adhesive sheet(1) for attaching to a reinforcing plate of a flexible circuit board comprises a first release sheet(12), an adhesive layer(11) formed by spreading the adhesive composition on the first release sheet; and a second release sheet(12) laminated on the adhesive layer.

Description

Adhesive composition with improved adhesion and adhesive sheet for attaching flexible circuit board reinforcement plate using the same {ADHESIVE COMPOSITION HAVING HIGH PEEL STRENGTH AND ADHESIVE SHEET FOR ATTACHING PLATE OF REINFORCE ON FPCB USING THE SAME}

The present invention relates to an adhesive composition having improved adhesion and an adhesive sheet for attaching a flexible circuit board reinforcement plate using the same, and more particularly, the present invention relates to an isocyanate curing agent in which both ends are blocked in a specific polyurethane urea resin (A) -containing solution. (B) The present invention relates to an adhesive composition having a high adhesive strength with a reinforcing plate while maintaining a long-term storage property by mixing the containing solution, and an adhesive sheet for attaching a flexible circuit board reinforcing plate using the same.

In the field of flexible circuit boards, for example, in the manufacture of BGAs in a terminal, a switch part, or a semiconductor package requiring mechanical strength, an adhesive sheet is used to attach a reinforcement plate and a heat sink of a package substrate.

In general, metal plates, glass fiber reinforced epoxy sheets, polyester-based reinforcing plates, polyimide reinforcing plates, and the like are used as reinforcing materials for reinforcing the mechanical properties of flexible circuit boards. In particular, most flexible circuit boards have heat resistance and dimensions. Since a polyimide film having excellent stability is employed, the adhesive sheet should be excellent in adhesion to the polyimide.

Also, in recent years, efforts have been made to shorten the adhesion time made under high temperature and high pressure presses for a long time when bonding a conventional reinforcing plate.

On the other hand, in the case of a flexible circuit board, various semiconductor packages are mounted after adhering the reinforcing material. In general, the flexible circuit board is subjected to a solder reflow process, and thus heat resistance to cope with the solder reflow process is required. Other applications may require high adhesion reliability without a solder reflow process.

The most common form of sheet-like adhesive sheet is made by using a modified rubber composed of acrylic acid / acrylonitrile / butadiene, epoxy resin, epoxy curing agent and epoxy curing accelerator. In this case, aromatic diamines are generally used as curing agents. In this case, they are difficult to be stored for a long time, and sufficient adhesive strength cannot be obtained. Moreover, the curing rate is low due to the slow curing rate under soaking conditions, so that they cannot be sufficiently cured in a high temperature and high humidity environment. Hard to maintain long time adhesion

In addition, when a general acrylic adhesive is used, the reinforcement plate can be easily adhered under a short time of low pressure press conditions, but when the adhesive strength is generally low and a stress such as gravity exists, the flow of the adhesive resin occurs over time and the circuit Due to the change of position between the ash and the reinforcement plate, there is a limitation in use of the adhesion of the reinforcement plate. In order to compensate for this, an acrylic resin having an epoxy group may be used, and even in this case, when a general epoxy curing agent is used, it is difficult to obtain sufficient adhesive strength under soaking conditions, and the price is also higher than that of a general acrylic resin. There are many storage constraints when using highly reactive hardeners to make them fit. In addition, some latent hardeners may be used to increase the stability at room temperature, but they are more expensive than general hardeners, and due to the nonuniformity of the degree of curing, it is difficult to have high reliability in a high temperature and high humidity environment after the process.

Accordingly, the present inventors provide an adhesive composition which maintains long-term storage like an acrylic adhesive under high pressure conditions and has a high adhesive strength with a flexible circuit board reinforcement plate, and an adhesive sheet for attaching a flexible circuit board reinforcement plate or a heat sink using the same. The invention was completed.

It is an object of the present invention to provide an adhesive composition having a high adhesive strength.

Another object of the present invention is to provide an adhesive sheet for attaching a flexible circuit board reinforcement plate or a heat sink using the adhesive composition.

Still another object of the present invention is to provide a flexible circuit board with a reinforcing plate or a heat dissipation plate having the adhesive sheet employed to secure excellent adhesion and room temperature stability.

In order to achieve the above object, the present invention is an isocyanate having both ends blocked in a solution containing a polyurethane urea resin (A) having an acid value of 5 to 50 mg KOH / g obtained by the reaction of a urethane-based prepolymer having an isocyanate end group and an amine compound. The curing agent (B) -containing solution is mixed to provide an adhesive composition with improved adhesion.

At this time, the adhesive composition of the present invention is the polyurethane urea resin (A) 90 to 99% by weight of the solution, it is implemented by 1 to 10% by weight of the solution containing both ends of the isocyanate curing agent (B).

In addition, the adhesive composition of the present invention contains 15 to 60% by weight of the total solid content of the polyurethane urea resin (A) and the isocyanate curing agent (B) blocked at both ends relative to the entire adhesive composition.

In the adhesive composition of the present invention, as a constituent of the polyurethane urea resin (A), a urethane-based prepolymer having an isocyanate end group includes: i) a polyol of polyester or polycarbonate, ii) a carboxylic acid-containing diol and iii) di Prepared by the reaction of isocyanate polyols. In addition, the functional group ratio (NCO / OH) in the reaction between the polyester polyol, carboxylic acid-containing diol and diisocyanate polyol during production is characterized in that 1.2 to 2.0.

In order to control the adhesion and resin flow of the adhesive composition, i) the number average molecular weight of the polyester or polycarbonate is preferably 500-10,000, and ii) the functional group amount of the carboxylic acid of the carboxylic acid-containing diol. It is preferable that it is 5-50 mg KOH / g based on the acid value of silver polyurethane urea resin (A).

Moreover, in the adhesive composition of this invention, the monoamine or the diamine compound is used for the amine compound which is another composition which comprises a polyurethane urea resin (A).

In this case, the amine compound may be obtained by a reaction of 0.7 to 1.1 weight ratio relative to the isocyanate end group in the urethane-based prepolymer having an isocyanate end group.

That is, the amine compound reacting with the urethane-based prepolymer having an isocyanate end group uses a monoamine or diamine compound, thereby eliminating the quaternary ammoniumation step through the reaction with the tertiary amine of the conventional carboxylic acid, while the polyurethane urea resin (A) can be manufactured.

The present invention provides an adhesive composition of the present invention in which the isocyanate curing agent (B) -containing solution in which both ends are blocked as a curing agent is mixed with the above-described polyurethane urea resin (A) -containing solution, and both ends used in the present invention are blocked. Isocyanate curing agent (B) is an isocyanate compound selected from toluene diisocyanate, isophorone diisocyanate, or hexamethylene diisocyanate, which is selected from the group consisting of phenol, ethyl acetoacetate, e-caprolactam and methyl ethyl cetoxime. It is formed by one blocking agent.

Furthermore, the present invention is a first release sheet; An adhesive layer formed by applying the adhesive composition of the present invention on the first release sheet; And a second release sheet laminated on the adhesive layer; provides an adhesive sheet for attaching a flexible circuit board reinforcement plate consisting of.

Thus, the adhesive sheet of the present invention has excellent adhesion and at the same time have a physical property that satisfies room temperature stability, it can be applied to a variety of products that do not require a solder reflow process.

In addition, in the adhesive sheet, the adhesive surface from which the first release sheet is removed is attached to the flexible circuit board, and the adhesive surface from which the second release sheet is removed is attached to the flexible circuit board reinforcement plate or the heat sink surface. Flexible circuit boards; Adhesive layer; And a flexible circuit board having a structure to which a flexible circuit board reinforcement plate or a heat sink is attached.

According to the present invention, an isocyanate curing agent (B) containing both ends of the polyurethane urea resin (A) -containing solution having an acid value of 5 to 50 mg KOH / g obtained by the reaction of a urethane-based prepolymer having an isocyanate end group and an amine compound is contained. The solution is mixed It is possible to provide an adhesive composition having high adhesive strength and room temperature stability.

Accordingly, the present invention provides an adhesive sheet for attaching a flexible circuit board reinforcement plate using the adhesive composition, so that the flexible circuit board with the flexible circuit board reinforcement plate or the heat dissipation plate according to the adhesive sheet secures excellent adhesion with the reinforcement plate. Excellent long term storage.

1 is a schematic diagram of the adhesive sheet structure implemented in the present invention,
2 is a schematic diagram of a flexible circuit board structure with a reinforcing plate or a heat sink to which the adhesive sheet of the present invention is applied.

Hereinafter, the present invention will be described in detail.

The present invention relates to a solution containing an isocyanate curing agent (B) containing a polyurethane urea resin (A) containing solution having an acid value of 5 to 50 mg KOH / g obtained by the reaction of a urethane-based prepolymer having an isocyanate end group and an amine compound. Mixed to provide an adhesive composition with improved adhesion.

More specifically, the adhesive composition of the present invention is the polyurethane urea resin (A) 90 to 99% by weight of the containing solution, a solution containing 1 to 10% by weight of the isocyanate curing agent (B) blocked at both ends is mixed to achieve high adhesive strength and room temperature stability.

In the total adhesive composition of the present invention, the total solid content of the polyurethane urea resin (A) and the both-blocked isocyanate curing agent (B) contains 15 to 60% by weight, more preferably 20 to 30% by weight. . At this time, if the total content of the solid content is less than 15% by weight, when the coating on the release film is too low viscosity caused coating defects, if it exceeds 60% by weight the viscosity is too high, the coating itself is impossible.

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

1.Polyurethane Urea Resin (A)

As a composition of the adhesive composition of this invention, the said polyurethane urea resin (A) is resin with the acid value of 5-50 mgKOH / g obtained by reaction of the urethane type prepolymer which has an isocyanate terminal group, and an amine compound.

More specifically, in the adhesive composition of the present invention, the urea constituting the polyurethane urea resin (A) is a urethane-based prepolymer having an isocyanate end group as a polyurethane resin containing carboxylic acid and urea bond in the polymer chain, i) polyols of polyesters or polycarbonates, ii) carboxylic acid containing diols and iii) diisocyanate polyols.

The polyol of i) polyester or polycarbonate is not particularly limited as a polyurethane polymer, but preferably, dicarboxylic acids such as adipic acid, phthalic acid, isophthalic acid, sebacic acid; and ethylene glycol, 3-methyl -1,5-pentanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, hexanediol, diethyl glycol, dipropylene glycol, dibutylene glycol, polyethylene glycol, polybutylene glycol, etc. Polyester polyol obtained by condensation reaction with a polyol can be used.

Moreover, the polycarbonate type polyol obtained by substitution reaction of diol like bisphenol-A with carbonate ester or phosgene can be used, and it can produce | generate also by ring-opening reaction of cyclic monomer like caprolactone. At this time, the number average molecular weight of the polyester or polycarbonate polyol is preferably 500 ~ 10,000. If the molecular weight of the polyol of the polyester or polycarbonate is less than 500, the adhesion is poor due to the lack of flexibility, and if the molecular weight exceeds 10,000, the proportion of carboxylic acid in the resin decreases, which does not cause sufficient curing reaction to affect the resin flow. Can be.

In addition, in the case of diol containing ii) carboxylic acid, which is another composition of the prepolymer of the present invention, dimethylolpropanoic acid (DMPA), dimethylolbutanoic acid, and the like may be preferably used. It doesn't work. At this time, the functional group amount of the carboxylic acid is about 5 ~ 50mg KOH / g based on the acid value of the final polyurethane urea polymer (A), if the acid value is too low below the lower limit of the acid value, it will not cause a sufficient curing reaction On the other hand, if the resin is too high with an acid value exceeding the upper limit value, the degree of curing may increase, resulting in poor adhesion and poor solubility in organic solvents. There is this.

In addition, iii) diisocyanate polyol, which is another composition in preparing the prepolymer of the present invention, may be used an aromatic diisocyanate compound, an aliphatic diisocyanate compound, a substituted aliphatic diisocyanate compound, or the like. The aromatic diisocyanate compound includes toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and the like, and the aliphatic diisocyanate compound includes hexanemethylene diisocyanate, meta-tetramethylxylene diisocyanate, and the like. As a group diisocyanate compound, cyclohexane-1, 4- diisocyanate, bis (4-isocyanate cyclohexyl) methane, etc. can be used.

In the preparation of the prepolymer having an isocyanate group in the terminal group, the functional group ratio (NCO / OH) of the polyol of i) polyester or polycarbonate, ii) carboxylic acid-containing diol and iii) diisocyanate polyol is about 1.2 to 2.0. Preferably, reaction temperature is 60-120 degreeC. At this time, when the functional group ratio is less than 1.2, the OH end is not the isocyanate end, and when it exceeds 2.0, excess isocyanate may remain as a residue through unreacted or reacted with water to lower the physical properties of the urethane resin. have.

In the adhesive composition of this invention, as another composition which comprises a polyurethane urea resin (A), a monoamine or a diamine compound is used for an amine compound.

In this case, the polyurethane urea resin (A) of the present invention is prepared by using i) a polyol of polyester or polycarbonate, ii) carboxylic acid diol, and iii) diisocyanate polyol, and then isocyanate group of the prepolymer. A polyurethane urea resin (A) is synthesized by adding a monoamine or a diamine compound immediately without undergoing quaternary ammoniumation by reaction with a tertiary amine.

That is, after formation of the water-soluble or water-dispersible prepolymer, a high molecular weight polyurethane urea adhesive resin is produced by reacting with an isocyanate group of the prepolymer with a secondary amine or a primary amine having a high reaction rate.

In this case, the amine compound is preferably a monoamine or a diamine compound, and examples thereof include ethylene diamine, propylene diamine, hexamethylene diamine, isophorone diamine, bis (4-aminophenyl) methane, bis (4-amino-3, 5-dimethylphenyl) methane, dibutylamine, etc. can be used selectively.

Moreover, the amine compound etc. which have a silane group like n, n'-bis (3-trimethoxy silylpropyl) ethylenediamine can be used.

More specifically, in the preparation of the polyurethane urea adhesive resin (A), when the monoamine or diamine compound to be added is connected with the isocyanate, the reaction is terminated and no longer has an active group at the terminal, thereby controlling the appropriate molecular weight of the desired resin. can do. Embodiments of the present invention have been described as being limited to isophorone diamine and dibutylamine, but are not limited thereto. At this time, when using the amine compound which has one amine reactor, it is preferable to contain 0.1 or less as a functional group ratio with respect to the functional group of a polyamine compound.

Therefore, in order for the polyurethane urea resin (A) of this invention to have a preferable molecular weight, the equivalence ratio of an amine group with respect to the isocyanate end group of a prepolymer is preferable 0.7-1.1. At this time, when the equivalent ratio is less than 0.7, the molecular weight of the resulting polyurethane urea is not large, and when larger than 1.1, unreacted amine is present.

2. Isocyanate Curing Agent Blocked at Both Ends (B)

In the adhesive composition of the present invention, the isocyanate curing agent (B) -containing solution in which both ends are blocked is mixed with the polyurethane urea resin (A) -containing solution, and the carboxylic acid and both ends of the polyurethane urea resin (A) are blocked. As the isocyanate curing agent (B) reacts, it is excellent in storage stability because it blocks both ends very stably at room temperature, and at a temperature higher than the temperature at which both ends of the isocyanate can be deblocked during use, the polyurethane urea resin (A By hardening reaction, it is possible to produce an adhesive sheet having high adhesive strength under quick press conditions.

Preferably polyurethane urea resin (A) 1 to 10% by weight of the isocyanate curing agent (B) containing both ends of the blocked solution is mixed with 90 to 99% by weight of the containing solution, and both ends of the isocyanate curing agent (B) is used at less than 1% by weight. When the adhesive resin is insufficient, hardening of the adhesive resin may cause a problem of resin flow during the thermocompression process, and when it exceeds 10% by weight, it is not preferable because it is difficult to realize a desired adhesive strength.

The isocyanate curing agent (B) blocked at both ends used in the present invention is an isocyanate compound selected from toluene diisocyanate, isophorone diisocyanate, or hexamethylene diisocyanate, and includes phenol, ethyl acetoacetate, e-caprolactam and methyl. It is formed by any one blocking agent selected from the group consisting of ethylcetoxime. At this time, it will be understood that the selection of the blocking agent may be applied differently according to the adhesive sheet manufacturing temperature.

In addition to the above composition, the adhesive composition of the present invention may use various fillers such as silica particles, alumina particles, phosphorus flame retardant particles, aluminum trihydrooxide, antimony oxide, and the like. In particular, the particle size of the filler is not limited as long as the maximum particle size is small compared to the thickness of the adhesive sheet.

As another additional composition, it may further contain a curing accelerator such as trifluoroborane monoethylamine, imidazole series, tertiary amine and the like.

At this time, the other additive composition may be added for the desired performance improvement based on 100 parts by weight of the solid content consisting of polyurethane urea resin (A) and isocyanate curing agent (B) blocked at both ends.

Furthermore, the present invention provides an adhesive sheet for attaching a flexible circuit board reinforcement plate using the adhesive composition.

More specifically, as shown in Figure 1 , the first release sheet 12;

An adhesive layer 11 formed by applying the adhesive composition of the present invention onto the first release sheet and curing the solvent while volatilizing the solvent; And

The second release sheet 12 laminated on the adhesive layer; provides a laminated three-layer adhesive sheet (1).

The coating method of the adhesive composition of the present invention is performed by a conventional method such as a lip coater, gravure coater, die coater, curtain coater, dip coater, and drying after the coating is carried out at 50 ~ 160 ℃.

In addition, the thickness of the adhesive sheet (1) after drying is preferably 5 ~ 200㎛, to adjust the gel fraction in the heating aging oven or aging room for more stable quality, at this time, the gel fraction of the adhesive sheet (1) Is 10 to 90% by weight. The gel fraction is immersed in the adhesive sheet in methyl ethyl ketone (MEK) for about 1 hour using a mesh network (100 mesh) and shaken well to completely blow off the methyl ethyl ketone, before immersing in methyl ethyl ketone compared to the adhesive resin and then in the mesh network It is the numerical value which computed the ratio of the adhesive resin remain | surface as weight%.

In addition, as shown in FIG . 2 , in the adhesive sheet 1, the adhesive surface from which the first release sheet 12 is removed is attached to the flexible circuit board 13, and the second release sheet ( 12, the adhesive surface having been removed is attached to the flexible circuit board reinforcement plate or the heat sink 14 surface, and the flexible circuit board 13; An adhesive layer 11; And a flexible circuit board 2 having a structure to which the flexible circuit board reinforcement plate or the heat sink 14 is attached.

In this case, in the case of a flexible reinforcing plate, for example, a polyethylene terephthalate film (PET film) of 300 μm or less that can be handled in a roll shape, the adhesive composition may be directly applied, and a release sheet may be attached thereto.

By using the adhesive sheet having a high adhesive strength by the adhesive composition of the present invention, the flexible circuit board 2 with the flexible circuit board reinforcement plate or the heat sink 14 is very excellent in adhesion with the reinforcement plate, By showing stability at room temperature of 4 months or more [ Table 1 ], as the physical properties equivalent to the acrylic adhesive under Sok press conditions, it is possible to produce an adhesive sheet having a high adhesive strength under the soak (quick press) conditions.

Hereinafter, the present invention will be described in detail with reference to examples.

The following examples are merely illustrative of the present invention, but the scope of the present invention is not limited to the following examples.

Preparation Example 1 Synthetic Resin Adhesive A-1

401.9 g of polyester polyol (number average molecular weight 1,000) consisting of adipic acid and 3-methyl-1,5-pentanediol and 12.7 g of dimethylol butanoic acid in a reactor equipped with a stirrer, a temperature sensor, a distillation cooler, a dropping device and a nitrogen supply device , 151.0 g of isophorone diisocyanate was reacted with 340 g of toluene as a solvent at 70 ° C. for 4 hours to obtain a polyester urethane prepolymer having 906 g of isocyanate end group (NCO).

To the resin solution prepared above, 30.9 g of isophorone diamine, 3.6 g of dibutylamine, and 380 g of 2-propanol were added to a solvent of 440 g of toluene and reacted at 70 ° C. for 3 hours to prepare 1,760 g of a polyurethane urea resin solution. A solvent of 160 g of toluene and 80 g of 2-propanol was added thereto to prepare a total solution weight of 2,000 g (solid content of 30.0 wt%, acid value = 8 mg KOH / g solution).

Preparation Example 2 Synthetic Adhesive Resin A-2

313.4 g of polyester polyol (number average molecular weight 1,000) consisting of adipic acid and 3-methyl-1,5-pentanediol and 48 g of dimethylol butanoic acid in a reactor equipped with a stirrer, a temperature sensor, a distillation cooler, a dropping device and a nitrogen supply device; 198.3 g of isophorone diisocyanate was reacted with 300 g of toluene as a solvent at 70 ° C. for 4 hours to obtain a polyester urethane prepolymer having 860 g of isocyanate end group (NCO).

To the resin solution prepared above, 30.9 g of isophorone diamine, 3.5 g of dibutylamine, and 342 g of 2-propanol were added to a solvent of 396 g of toluene, and reacted at 70 ° C. for 3 hours to prepare 1632 g of a polyurethane urea resin solution. A solvent of 245 g of toluene and 123 g of 2-propanol was added to make the total solution weight 2,000 g (29.7% solids, acid value = 30 mg KOH / g solution).

Example 1 Preparation of Adhesive Composition and Adhesive Sheet Using the Same

The adhesive composition was prepared by mixing 266 g of the adhesive resin A-1 resin solution prepared in Preparation Example 1 and 14.3 g of a methyl di- p- phenylene isocyanate blocked dimethyl ketoxime solution at 50% dissolved in a MEK solvent. Prepared. The adhesive composition was coated on a release-treated 38 μm PET film and dried to form an adhesive sheet, and then a release treated release paper was laminated on the back of the adhesive sheet as shown in FIG. 1 to obtain an adhesive sheet.

Example 2 Preparation of Adhesive Composition and Adhesive Sheet Using the Same

The adhesive composition was prepared by mixing 266 g of the adhesive resin A-1 resin solution prepared in Preparation Example 1 and 2.9 g of a methyl di- p- phenylene isocyanate blocked dimethyl ketoxime solution in 50% dissolved in a MEK solvent. Prepared. The adhesive composition was coated on a release-treated 38 μm PET film and dried to form an adhesive sheet, and then a release treated release paper was laminated on the back of the adhesive sheet as shown in FIG. 1 to obtain an adhesive sheet.

Example 3 Preparation of Adhesive Composition and Adhesive Sheet Using the Same

By mixing the prepared resin adhesive resin solution A-2 and 269g of 50% melting at both terminals with an isocyanate to block MEK solvent (methyl di- p -phenylene dimethyl ketoxime blocked isocyanate) solution prepared in Example 2 14.4g of the adhesive composition Prepared. The adhesive composition was coated on a release-treated 38 μm PET film and dried to form an adhesive sheet, and then a release treated release paper was laminated on the back of the adhesive sheet as shown in FIG. 1 to obtain an adhesive sheet.

Comparative Example 1

An adhesive composition was prepared by mixing 266 g of the adhesive resin A-1 resin solution prepared in Preparation Example 1 and 31.0 g of a silane-modified bisphenol A epoxy (EEW483) solution dissolved in 70% MEK solvent. 38㎛ PET film release the adhesive composition After coating on and then dried to form an adhesive sheet, as shown in Figure 1 by laminating a release treated release paper on the back of the adhesive sheet to obtain an adhesive sheet.

Comparative Example 2

An adhesive composition was prepared by mixing 269 g of the adhesive resin A-2 resin solution prepared in Preparation Example 2 and 31.3 g of a silane-modified bisphenol A epoxy (EEW483) solution dissolved in 70% MEK solvent. The adhesive composition was coated on a release-treated 38 μm PET film and dried to form an adhesive sheet, and then a release treated release paper was laminated on the back of the adhesive sheet as shown in FIG. 1 to obtain an adhesive sheet.

≪ Comparative Example 3 &

113 g of carboxylic acid-containing acrylonitrile butadiene rubber (NBR), 128 g of bisphenol-A type epoxy resin, and 5 g of 3,3-aniline sulfone were mixed, and 0.05 g of 2-methylimidazole was used as an accelerator, and the solid content concentration was 27%. Phosphorous adhesive composition was prepared. The adhesive composition was coated on a release-treated 38 μm PET film and dried to form an adhesive sheet, and then a release treated release paper was laminated on the back of the adhesive sheet as shown in FIG. 1 to obtain an adhesive sheet.

Experimental Example 1 Adhesion Strength Measurement

As shown in FIG. 1, one release sheet is removed from the adhesive sheet prepared in the above embodiment, roll laminated with the polyimide surface (LN100) of the flexible printed circuit board, and then the other release sheet is removed again and the thickness is 25 μm. Rolling was performed to prevent bubbles from entering the polyimide (LN100) to prepare a specimen having a three-layer structure consisting of a flexible substrate / adhesive layer / polyimide film. The sample was pressed for 2 minutes at 145 ° C. × 3 Mpa pressure using a press and then cured for an additional hour in a 160 ° C. oven. The sample was fixed to a three-layer flexible circuit board shaft, and the 180 ° adhesive strength (N / cm) was measured by pulling the opposite shaft polyimide film at a rate of 50 mm / min.

Experimental Example 2 Soldering Heat Resistance

After the specimen having a three-layer structure composed of a flexible substrate / adhesive layer / polyimide film prepared in the same manner as in Experimental Example 1 was left under an internal temperature of 20 to 30 ° C. and a relative humidity of 30 to 60% for 24 hours, the specimen was 4 cm × 4 cm. Cut to size. Then, the specimen was floated with the three-layer flexible substrate face down in the soldering tank, and then observed for 60 seconds when the voids were generated.

Experimental Example 3 Room Temperature Stability

In Experimental Example 2, the adhesive force was measured at intervals of one week for the specimen having a three-layered structure composed of a flexible substrate / adhesive layer / polyimide film, which was left at room temperature.

The results are shown in Table 1 below.

As confirmed in Table 1, in the adhesive resin (A) component of the present invention, the adhesive sheet of Examples 1, 2, 3 produced by using an adhesive composition composed of an isocyanate curing agent (B) blocked at both ends In this case, while maintaining a significantly improved adhesive strength compared to the comparative example was maintained excellent room temperature stability. Therefore, it was confirmed that the adhesive sheet using the adhesive composition of the present invention can maintain a high adhesive strength under soaking conditions.

On the other hand, in the adhesive sheet (A) of the present invention, the adhesive sheets of Comparative Examples 1 to 2 made of an adhesive composition composed of an epoxy curing agent have excellent aging stability at room temperature, but have low results in terms of adhesive strength. Seemed.

In particular, the adhesive sheet of Comparative Example 3 prepared as a composition for bonding a conventional flexible circuit board reinforcement plate was significantly lower than the adhesive sheets of Examples 1 to 3 in terms of adhesive strength and room temperature stability.

As described above, the present invention contains an isocyanate curing agent (B) having both ends blocked in a polyurethane urea resin (A) prepared by the reaction of a urethane-based prepolymer having an isocyanate end group with a monoamine or diamine compound, An adhesive composition with improved adhesion was provided. Since the adhesive composition of the present invention is excellent in room temperature stability under soak conditions, long-term storage is possible, and high adhesive strength with a flexible circuit board reinforcing plate is realized.

Thus, by using the adhesive composition of the present invention, it is possible to provide an adhesive sheet for attaching a flexible circuit board reinforcement plate in which physical properties of high adhesive strength and room temperature stability are maintained.

While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims.

1: adhesive sheet 11: adhesive layer
12: First and second release sheet 2: Flexible circuit board with reinforcement plate or heat sink
13: Flexible circuit board 14: Flexible circuit board reinforcement plate or heat sink

Claims (13)

An isocyanate curing agent (B) -containing solution in which both ends are blocked is mixed with a polyurethane urea resin (A) -containing solution having an acid value of 5 to 50 mg KOH / g obtained by the reaction of a urethane-based prepolymer having an isocyanate end group with an amine compound. This improved adhesive composition. The said polyurethane urea resin (A) of Claim 1 characterized by the above-mentioned. The adhesive composition, characterized in that 1 to 10% by weight of the solution containing 90 to 99% by weight of the isocyanate curing agent (B) blocked at both ends. The adhesive composition according to claim 1, wherein the total amount of solid content of the polyurethane urea resin (A) and the isocyanate curing agent (B) blocked at both ends is contained in an amount of 15 to 60% by weight relative to the adhesive composition. The urethane-based prepolymer of claim 1, wherein the urethane-based prepolymer having Said adhesive composition, which is prepared by the reaction of a polyol of polyester or polycarbonate, ii) carboxylic acid containing diol and iii) diisocyanate polyol. The method according to claim 4, wherein the functional group ratio (NCO / OH) in the reaction between the polyester polyol, the carboxylic acid-containing diol and the diisocyanate polyol when the urethane-based prepolymer having the isocyanate end group is manufactured is 1.2 to 2.0. Adhesive composition. The said adhesive composition of Claim 4 whose number average molecular weights of the said polyester or polycarbonate polyol are 500-10,000. The said adhesive composition of Claim 4 whose functional group amount of the carboxylic acid of the said carboxylic acid containing diol is 5-50 mg KOH / g based on the acid value of a polyurethane urea resin (A). The isocyanate curing agent (B) in which both ends are blocked is an isocyanate compound selected from toluene diisocyanate, isophorone diisocyanate, or hexamethylene diisocyanate, and a phenol, ethyl acetoacetate, e-caprolactam And methyl ethyl cetoxime, the adhesive composition formed by any one of blocking agents selected from the group consisting of. The said adhesive composition of Claim 1 whose said amine compound is a monoamine or a diamine compound. The adhesive composition according to claim 1, wherein the equivalent ratio between the amine compounds and the isocyanate end groups of the prepolymer is 0.7 to 1.1. First release sheet;
An adhesive layer formed by applying the adhesive composition of claim 1 on the first release sheet; And
An adhesive sheet for attaching a flexible circuit board reinforcement plate consisting of; a second release sheet laminated on the adhesive layer. The adhesive sheet according to claim 11, wherein the adhesive layer has an adhesive strength of 15 N / cm or more. In the adhesive sheet of claim 11, the adhesive surface from which the first release sheet is removed is attached to the flexible circuit board, and the adhesive surface from which the second release sheet is removed is attached to the flexible circuit board reinforcement plate or the heat sink surface, ; The adhesive layer of claim 11; And a flexible circuit board having a structure to which a flexible circuit board reinforcement plate or a heat sink is attached.

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