KR20110015874A - Thermosetting adhesive composition - Google Patents

Abstract

PURPOSE: A thermosetting adhesive composition is provided to ensure heat resistance corresponding to Pb free soldering and also high heat resistance even in the high temperature and high humidity environment, thereby enhancing the reliability and yield of products. CONSTITUTION: A thermosetting adhesive composition comprises thermoplastic resins, thermosetting resins, hardeners and inorganic aluminum particles. The inorganic aluminum particle has the size of 0.1~10 micron. The thermosetting adhesive composition includes, 100 parts by weight of the thermoplastic resin, 50~300 parts by weight of thermosetting resin, 1~20 parts by weight of hardener, and 0.1~20 parts by weight of inorganic aluminum particles.

Description

Thermosetting Adhesive Composition {THERMOSETTING ADHESIVE COMPOSITION}

The present invention relates to a thermosetting adhesive composition used to attach a reinforcing material to a flexible printed circuit board (FPCB), and more particularly, having excellent thermal stability at high temperatures by having improved heat resistance that can correspond to the temperature of the reflow furnace. The present invention relates to a thermosetting adhesive composition capable of preventing the lifting of the adhesive between the flexible printed circuit board and the reinforcing material even under high temperature conditions and having excellent hygroscopic resistance.

In recent years, in line with the development of embedded technology in electronic components and the shortening and thinning of electronic products, the demand for flexible printed circuit boards has been continuously growing.

In the conventional method of manufacturing such a flexible printed circuit board, a dry film is laminated on a copper foil laminated plate on which copper foil is formed on a polyimide film to form a circuit pattern through an exposure, development, and etching process, and then a coverlay film is adhered to the coverlay. The film is bonded to the outermost copper foil to produce a flexible printed circuit board. After this process, in order to bind the external device to the edge of the flexible printed circuit board, a reinforcing film such as glass epoxy or polyimide having high heat resistance is attached. It is common for the thickness difference from the circuit board to be quite large. When the reinforcement material is considerably thicker than the thickness of the flexible printed circuit board, there is a limit to press bonding using the roll, and it is difficult to bond due to the breakage of the reinforcement material and the flexible printed circuit board due to the high pressure when using the hot press. Conventionally, these reinforcing materials are attached to a double-sided tape with adhesive strength, but the adhesive strength is weak, and heat resistance that can withstand the thermal history applied in the future process is weak, which is a reality that many thermosetting adhesive films are currently employed. Accordingly, when the base material of the reinforcing plate is thin or soft, the flexible printed circuit board and the reinforcing material are increased by passing the adhesive film and the reinforcing material by pressing the adhesive film and the reinforcing material by passing the pressure between the rolls heated at about 100 ° C. to 150 ° C. at an appropriate pressure and speed. The initial adhesive force between them was improved and used. In addition, when the base material of the reinforcing material has a thick or hard property, it is punched into a form to be directly applied to the reinforcing material without passing between the rolls and press-bonded using an iron or the like. In addition, there is a disadvantage that may damage other circuit patterns other than the reinforcement when applying a high pressure during thermal compression using a hot press after pressing. For example, when hot pressing at a temperature of 140 ° C. to 170 ° C. using a hot press for 1 hour or more under a pressure condition of 20 kg / cm ² to 60 kg / cm ^2, the flexible printed circuit board may be damaged or a cushioning material may be damaged. There is a problem that can be.

For this reason, when the reinforcing material is attached to the flexible printed circuit board, it should be possible to maintain the adhesive strength under the condition that the flexible printed circuit board is not damaged. In addition, the reflow of the flexible printed circuit board after adhesion requires heat resistance to withstand high temperatures of more than 260 ° C for a certain period of time in the process.In the summer, when the weather is hot and humid, moisture absorption of the adhesive layer is very easy. Since there is a problem that occurs, the development of an adhesive film that can maintain the heat resistance even under heat and high temperature and high humidity conditions is urgently required.

The present invention has been made to solve the above problems, the object of the present invention has a heat resistance that can cope with lead-free solder, and also has a high heat resistance even in a high temperature and high humidity environment, such as summer, the expansion and peeling of the adhesive layer does not occur Therefore, to provide a thermosetting adhesive composition that can increase the reliability and yield of the product.

These and other objects and advantages of the present invention will become more apparent from the following description of a preferred embodiment thereof.

The said object is achieved by the thermosetting adhesive composition characterized by including a thermoplastic resin, a thermosetting resin, a hardening | curing agent, and an inorganic aluminum particle.

Here, the inorganic aluminum particles are characterized by having a size of 0.1 ~ 10㎛.

Preferably, the thermoplastic resin includes 50 to 300 parts by weight of the thermosetting resin, 1 to 20 parts by weight of the curing agent, and 0.1 to 20 parts by weight of the inorganic aluminum particles.

According to the present invention, it has heat resistance that can cope with lead-free solder, and also has high heat resistance even in a high temperature and high humidity environment such as summer, so that expansion and peeling of the adhesive layer do not occur, thereby increasing the reliability and yield of the product. .

Hereinafter, the present invention will be described in detail with reference to examples of the present invention. These examples are only presented by way of example only to more specifically describe the present invention, it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples. .

The thermosetting adhesive composition according to the present invention is an adhesive composition for forming the adhesive layer in the adhesive film consisting of a release film and an adhesive layer formed on one side of the release film, comprising a thermoplastic resin, a thermosetting resin, a curing agent and inorganic aluminum particles. It is characterized by.

Hereinafter, the thermoplastic component, the thermosetting component, the hardening | curing agent, and the inorganic aluminum particle which are each component of the adhesive composition of this invention are demonstrated concretely.

First, in order to improve the adhesive force of the adhesive film, a thermoplastic component is contained in the adhesive composition. Such thermoplastic components are not particularly limited, and conventionally known thermoplastic components can be used. For example, A copolymer comprising a vinyl monomer and acrylonitrile, styrene, etc. as main components of acrylic rubber and acrylic acid alkyl ester (including methacrylic acid ester); Polyisoprene rubber; Polybutadiene rubber; 1,2-polybutadiene rubber; Styrene-butadiene rubber; Acrylonitrile butadiene rubber (hereinafter also referred to as 'NBR'); Ethylene butadiene rubber; Carboxylated nitrile rubber etc. are mentioned preferably, More preferably, it is an acrylic rubber, NBR, an ethylene butadiene rubber, or a polybutadiene rubber, Especially preferably, it is NBR. The polybutadiene rubber or 1,2-polybutadiene rubber may be substituted with a carboxyl group or a hydroxyl group. The styrene butadiene rubber may be substituted with a hydroxyl group. The NBR may be substituted with a carboxyl group, hydroxyl group, acryloyl group or morpholine group.

Such a thermoplastic component preferably has a functional group that reacts with the thermosetting component. When the thermoplastic component and the thermosetting component react, there is an advantage in that the heat resistance is increased. Although it depends also on the kind of thermosetting component, a carboxyl group, an epoxy group, or a hydroxyl group etc. are mentioned suitably as said functional group, A carboxyl group is more preferable from a viewpoint of reactivity, universality, etc.

The NBR containing the carboxyl group has a weight average molecular weight of 2,000 to 200,000, preferably 3,000 to 200,000, and has an acrylonitrile content of 10 to 60 parts by weight, preferably 20 to 50 parts by weight, and a carboxyl group content. It shall be 1-20 weight part. At this time, when the weight average molecular weight of NBR is lower than 2,000, the thermal stability is poor, and when it is higher than 200,000, the solubility in solvent is worsened, the viscosity increases during solution preparation, and the workability is poor, and the adhesive strength is also lowered. In addition, when the acrylonitrile content is lower than 10 parts by weight, the solvent solubility is lowered, and when higher than 60 parts by weight, the electrical insulation is poor. And when the content rate of the carboxyl group is 1 to 20 parts by weight, the adhesion between NBR and other resins, and the adhesive substrate is easy, so that the adhesive force increases.

Next, by including the thermosetting component in the thermosetting adhesive composition according to the present invention can improve the reflow solder heat resistance and workability. In the prior art, increasing the ratio of the thermoplastic resin in order to increase the adhesive strength reduces the thermosetting portion, thereby sacrificing heat resistance and workability, and increasing the ratio of the thermosetting resin in order to increase the heat resistance and workability, has a problem in that the adhesive force is sacrificed.

However, in the present invention, since the inorganic aluminum particles play a role of improving heat resistance, it is possible to suppress a decrease in adhesive force. Details of such inorganic aluminum particles will be described later.

As the thermosetting resin used in the present invention, epoxy resin, phenol resin, vegetable oil-modified phenol resin, xylene resin, guanamine resin, diallyl phthalate resin, vinyl ester resin, unsaturated polyester resin, furan resin, polyimide resin, polyurethane A resin, a cyanate resin, a maleimide resin or a benzocyclobutene resin is preferable, more preferably an epoxy resin, a phenol resin or a vegetable oil-modified phenol resin, even more preferably an epoxy resin. It is because an epoxy resin is excellent in reactivity and heat resistance.

Examples of such epoxy resins include bisphenol-type epoxy resins, bisphenol-type epoxy resins such as bisphenol F-type resins, and bisphenol S-type resins, phenol novolak-type epoxy resins, novolak-type epoxy resins such as cresol novolak-type epoxy resins, and bisphenol A-novolak-type epoxy resins. Resin, alicyclic epoxy resin, aliphatic chain epoxy resin, diglycidyl ether of biphenol, diglycidyl ether of naphthalenediol, diglycidyl ether of phenol, diglycidyl ether of alcohol And at least one selected from the group consisting of these alkyl substituents, halides, and hydrogenated substances. Among these, bisphenol-A epoxy resin or novolak-type epoxy resin is particularly preferable.

The epoxy resin of the thermosetting adhesive composition according to the present invention may add 50 to 300 parts by weight based on 100 parts by weight of the thermoplastic resin, the epoxy equivalent (g / eq) is preferably 200 to 1000. Preferably, the epoxy resin is characterized in that 50 to 100 parts by weight with respect to 100 parts by weight of NBR, which is less elasticity of the adhesive film in the semi-cured state when added more than the epoxy resin compared to the NBR and when the reinforcement and lamination This is because the airtightness is insufficient, the adhesive film is easily expanded due to thermal stimulation, and reinforcement and lifting may occur.

Furthermore, the thermosetting adhesive composition which concerns on this invention can improve heat resistance by containing a hardening | curing agent, and can especially improve reflow solder heat resistance. As such a hardening | curing agent, a polyamine hardening | curing agent, an acid anhydride type hardening | curing agent, a boron trifluoride complex salt, a phenol resin etc. are mentioned, for example.

As said polyamine hardening | curing agent, For example, aliphatic amine hardening | curing agents, such as diethylene triamine, tetraethylene tetratamine, and tetraethylene pentamine; Alicyclic amine curing agents such as isophorone diamine; Aromatic amine curing agents such as diaminodiphenylmethane and phenylenediamine; Dicyandiamide, etc. are mentioned.

Examples of the acid anhydride curing agent include phthalic anhydride, pyromellitic anhydride, trimellitic anhydride, and hexahydrophthalic anhydride. These hardeners may be used independently and may use two or more types together as needed.

It is preferable that 1-20 weight part of said hardening | curing agents of the thermosetting adhesive composition concerning this invention are contained with respect to 100 weight part of said thermoplastic resins, More preferably, it is 1-10 weight part. When the concentration of the curing agent is 1 part by mass or more, the reflow solder heat resistance of the adhesive film made of the adhesive composition of the present invention is excellent, and when the concentration is 10 parts by mass or less, the workability of the adhesive composition is improved or the adhesive composition of the present invention is used. Outflow at the time of pressing of the made adhesive film is suppressed.

In addition, the thermosetting adhesive composition according to the present invention contains inorganic aluminum particles to improve the workability of the adhesive composition, or to improve the reflow solder heat resistance of the adhesive film made of the adhesive composition of the present invention or to have excellent hygroscopicity. In addition, since the inorganic aluminum particles are included in the adhesive layer, the surface of the adhesive layer may be roughened to improve the workability of the composition, and the heat resistance of the reflow solder may be improved due to the decomposition temperature of the inorganic particles significantly higher than the organic material forming the adhesive layer. As the inorganic aluminum particles are used to improve workability and heat resistance, the adhesive force decreases slightly due to the reduced resin part, but the burr phenomenon in which the cross section of the adhesive layer becomes rough by the blade of the slitting even when slitting by maintaining the proper elasticity of the adhesive layer. Can be prevented.

In addition, since the inorganic aluminum particles have almost no water absorption, the ratio of the adhesive layer is reduced by the ratio of the particles, thereby reducing the absorption rate of the adhesive layer. Therefore, it is possible to cope with the temperature of the reflow furnace in the hot and humid atmosphere of summer. The inorganic aluminum particles may include ATH (alumina trihydrate) and aluminum oxide.

The inorganic aluminum particles are preferably contained in an amount of 0.1 to 20 parts by weight, more preferably 3 to 8 parts by weight, based on 100 parts by weight of the thermoplastic resin. When the concentration of the inorganic aluminum is 0.1 parts by weight or more, the reflow solder heat resistance and hygroscopicity of the present adhesive composition are excellent, and when the concentration is 10 parts by weight or less, workability is improved.

The adhesive layer made of the above composition has a viscosity of 100 ~ 2000cps, preferably 400 ~ 1500cps, coated on a release film so that the thickness after drying to 25 ~ 50㎛ and cured for 2 to 10 minutes at 50 ~ 200 ℃ release paper The process of laminating to obtain a thermosetting adhesive film. Although it does not restrict | limit especially as a coating method, The coating method using a comma coater, a reverse roll coater, etc. is mentioned.

In addition, the thickness, shape, etc. of the adhesive layer of the adhesive film which apply | coated the thermosetting adhesive composition which concerns on this invention are not specifically limited, It can determine suitably according to a use site and a use purpose.

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

Example 1

To 100 parts by weight of NBR containing a carboxyl group, 50 parts by weight of bisphenol A epoxy and 10 parts by weight of diamino diphenyl sulfone (DDS) as a curing agent were added and 0.1 parts by weight of ATH was mixed to prepare a mixed solution, which was then dissolved in acetone. After sufficiently stirring using the coated on a release film and dried for 5 minutes at 160 ℃ to prepare an adhesive film having a thickness of 40㎛ after coating.

[Example 2]

Under the conditions of Example 1, except that ATH was added to 100 parts by weight of NBR, 1 part by weight was the same as in Example 1.

Example 3

Except that ATH was added to 100 parts by weight of NBR under the conditions of Example 1, 5 parts by weight was the same as in Example 1.

Example 4

Except that ATH was added to 100 parts by weight of NBR under the conditions of Example 1, 20 parts by weight was the same as in Example 1.

[Comparative Example]

50 parts by weight of bisphenol A epoxy and 10 parts by weight of diamino diphenyl sulfone (DDS) as a curing agent were added to 100 parts of NBR containing a carboxyl group to prepare a mixed solution. The mixed solution was dissolved in acetone and sufficiently stirred using a high speed stirrer and then released. After coating on the film and dried for 5 minutes at 160 ℃ to prepare an adhesive film having a thickness of 40㎛ after coating.

The physical properties of the adhesive films according to the Examples and Comparative Examples were measured through the following experiments, and the results are shown in Table 1.

Experimental Example 1 Measurement of Adhesion

In this experiment, the adhesive films prepared in Examples and Comparative Examples of the present invention were passed between 5 rolls at a pressure of 5 kg / cm ² at 120 ° C. between the rolls and bonded to the reinforcement materials under the following conditions using a hot press. After the peel strength was measured, the angle between the sample and the adhesive force measuring instrument at this time is 180, the speed was 50mm / min. The average value was obtained through 10 tests for each condition. At this time, the specimen was peeled off the peeling film, using a glass epoxy having a thickness of 0.5mm as a reinforcing material for the exposed adhesive film surface, passed between the heated rolls, cut into 2cm wide and 12cm long, 50㎛ thick poly Placed between the mid films, using a hot press, the hot plate heated to 150 ° C. was vertically lowered, and thermally pressed for 1 minute at a pressure of 40 kg / cm ² , and then immediately measured adhesive force, and the temperature was vertically lowered and the fixed bottom plate. In all.

Experimental Example 2: Measurement of Heat Resistance

The heat resistance of the adhesive sculptures was confirmed by post-curing the specimen fabricated under the above conditions and then floating for 30 seconds in a soldering furnace at 260 ° C to lift the sample through deformation and bubbles between the reinforcing material and the adhesive film. , Good when the number of bubbles up to 1mm is less than 1 in the specimen (◎), Good when 1 ~ 2 is out (○), 3 ~ 5 is normal (△), 5 or more is bad It was set as (Х).

Experimental Example 3: Measurement of Hygroscopic Heat Resistance

Hygroscopic heat resistance of the adhesive sculptures is modified by changing the specimen prepared under the above conditions by post-curing, 40 ℃, 90% RH (Relative Humidity) for 24 hours, and floating for 30 seconds in a soldering furnace at 260 ℃. And it was confirmed whether the bubble between the reinforcement and the adhesive film is lifted up, when the number of bubbles with a maximum diameter of 1mm is less than 1 from the specimen is very good (◎), good if 1 ~ 2 comes out (○) , 3 to 5 if the normal (△), 5 or more was determined as bad (Х).

Experimental Example 4: Measurement of Peel Force

The measurement of the peel force is to determine the degree to which the prepared thermosetting adhesive film easily falls off the release paper and the release film, which is an important factor in determining the good and bad workability in actual use. As the measuring method, the above-mentioned tensile strength tester was used and the size of the specimen was also the same, but the end of the adhesive and the peeling film peeled off the release paper without fixing the hot pressing process by hot press was fixed to the jig of the tensile strength tester. The average value was calculated | required by pulling by the method mentioned above. The higher the measured value, the more the peel force is required, so the workability is inferior. On the contrary, when the peel force is too low, the adhesive film is difficult to fix in the release paper and the release film. Peeling force is closely related to the release paper coated with polyethylene or silicone resin and the tacky, surface tension, and surface roughness of the surface of the release film and the adhesive film.

TABLE 1

Experimental Example
/ Rating item Example 1 Example 2 Example 3 Example 4 Comparative example Adhesion 1970 1950 1870 1750 2000 Heat resistance ○ ○ ◎ ◎ ○ Hygroscopic Heat Resistance △ ○ ◎ ◎ X Peel force 64 60 51 40 80

As can be seen in Table 1, Examples 1 to 4 according to the present invention can be seen that the adhesive strength is somewhat reduced as the content of the inorganic aluminum particles increases, but heat resistance and moisture absorption heat resistance increase. In addition, the surface of the adhesive layer becomes rough due to the inorganic aluminum particles, so that the peeling force is lowered. In particular, when comparing the comparative example and Example 3, it can be confirmed that the heat resistance and the moisture absorption heat resistance is very improved.

Although the present invention has been described in detail only with respect to the embodiments described, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications belong to the appended claims.

Claims (3)

In the thermosetting adhesive composition, A thermosetting adhesive composition comprising a thermoplastic resin, a thermosetting resin, a curing agent and inorganic aluminum particles. The method of claim 1, The inorganic aluminum particles have a size of 0.1 ~ 10㎛, thermosetting adhesive composition. The method according to claim 1 or 2, 50-300 weight part of said thermosetting resins, 1-20 weight part of said hardening | curing agents, and 0.1-20 weight part of said inorganic aluminum particles are included with respect to 100 weight part of said thermoplastic resins, The thermosetting adhesive composition characterized by the above-mentioned.