KR101100381B1 - Adhesive Composition for Halogen-Free Coverlay Film and Coverlay Film Coated by the Same - Google Patents

Abstract

The present invention relates to an adhesive composition for halogen-free coverlay film and a coverlay film coated with the same, and more particularly, without applying nitrile-butadiene rubber (NBR), which is generally applied as a binder of a coverlay adhesive, The present invention relates to an adhesive composition for a halogen-free coverlay film and a coverlay film coated with the same, wherein the adhesive composition and the heat resistance do not decrease even when exposed to moisture by applying an acrylic copolymer including a group and a carboxyl group. The adhesive composition for coverlay films includes (1) an acrylic resin containing a hydroxyl group and a carboxyl group, having a weight average molecular weight of 300,000 to 800,000, a viscosity at 25 ° C of 800 to 10,000 cP, (2) a phenol resin, (3) a polyfunctional epoxy resin, (4) a curing agent, (5) a curing accelerator, (6) a non-halogen flame retardant, (7 ) Inorganic particles and (8) crosslinking agent.

Acrylic resin, coverlay, halogen free

Description

Adhesive composition for halogen free coverlay film and coverlay film coated thereon {Adhesive Composition for Halogen-Free Coverlay Film and Coverlay Film Coated by the Same}

The present invention relates to an adhesive composition for halogen-free coverlay film and a coverlay film coated with the same, and more particularly, without applying nitrile-butadiene rubber (NBR), which is generally applied as a binder of a coverlay adhesive, The present invention relates to an adhesive composition for a halogen-free coverlay film and a coverlay film coated with the same, wherein the adhesive and heat resistance of the acrylic copolymer including a group and a carboxyl group are not reduced even when exposed to moisture.

Recently, the application of flexible circuit boards has exploded with the trend of miniaturization, thinning, and high integration of electronic products, and thus, the use of coverlay films for circuit protection is also increasing. In addition, the product structure is complicated by the improvement of electronic products, and the physical properties required for the coverlay film are becoming more stringent.

Meanwhile, development of environment-friendly materials has recently been demanded by WEEE- and RoHS in Europe. However, conventional adhesives used in electronic materials such as coverlay films and semiconductor sealing materials use a compound containing a halogen element such as bromine as a flame retardant. Therefore, toxic gases such as dioxins are generated during its combustion. In recent years, halogen-free (Halogen Free) is urgently required for adhesives for electronic materials.

In general, the coverlay film is coated with a semi-cured adhesive layer on the cross section of the heat resistant film and is composed of a release paper for protecting the adhesive. Since the coverlay film is adhered to the flexible printed circuit board to protect the printed circuit, heat resistance, adhesiveness, and flame retardancy are important requirements, and all of these characteristics must be provided at the same time.

Therefore, coverlay films using various organic flame retardants without halogen-based flame retardants have been developed, but they do not satisfy all the physical properties. In particular, heat and adhesive strength decrease due to moisture repeatedly exposed during the manufacturing process or the environment. It is pointed out as the biggest problem in that it becomes.

The present invention has been made to solve the above problems, an object of the present invention devised to provide an adhesive composition for a halogen-free coverlay film and a coverlay film having the same that satisfies all the required properties as described above. According to the present invention, an object of the present invention satisfies all properties such as flame retardancy, adhesion, and heat resistance required in a coverlay film, and in particular, an adhesive composition for a halogen-free coverlay film having no deterioration in physical properties even under high humidity exposure. And to provide a coverlay film coated with the same.

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 objective includes (1) an acrylic resin containing a hydroxyl group and a carboxyl group and having a weight average molecular weight of 300,000 to 800,000 and a viscosity at 25 ° C of 800 to 10,000 cP, (2) a phenolic resin, and (3) a polytube. For a halogen-free coverlay film comprising a functional epoxy resin, (4) a curing agent, (5) a curing accelerator, (6) a non-halogen-based flame retardant, (7) inorganic particles, and (8) a crosslinking agent. Achieved by an adhesive composition.

The above object is also achieved by a coverlay film coated with an adhesive composition for halogen-free coverlay film, wherein the adhesive composition for halogen-free coverlay film is applied on a polyimide base film as an adhesive layer. do.

According to the present invention, it has the effect of satisfying all properties such as flame retardancy, adhesion, heat resistance, and exposure to high humidity that are required in the coverlay film and the like, without deterioration in physical properties.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings 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. .

1 is a cross-sectional view of a coverlay film according to the present invention. The adhesive composition for halogen-free coverlay film according to the present invention comprises (1) an acrylic resin containing a hydroxyl group and a carboxyl group, having a weight average molecular weight of 300,000 to 800,000, and a viscosity at 25 ° C. of 800 to 10,000 cP, (2 ) Phenol resin, (3) polyfunctional epoxy resin, (4) curing agent, (5) curing accelerator, (6) non-halogen flame retardant, (7) inorganic particles and (8) crosslinking agent It features.

The acrylic resin containing a hydroxyl group and a carboxyl group of the adhesive composition for halogen-free coverlay film according to the present invention preferably has a weight average molecular weight of 300,000 to 800,000, which is poor in thermal stability when the weight average molecular weight is lower than 300,000, In addition, higher than 800,000, the solubility in the solvent is worse, the viscosity increases during the solution preparation, the workability is poor, the adhesion is also reduced. In addition, the acrylic resin preferably has a viscosity at 800C of 10,000 to 10,000 cP, and a hydroxyl value (hereinafter referred to as HV) of 5 to 35 mgKOH / g. When the content of the hydroxy group is 5 ~ 35 mgKOH / g is easy to bond the other resin and the adhesive substrate, the adhesive force increases.

In addition, the phenol resin of the adhesive composition for halogen-free coverlay film according to the present invention is preferably used alone or mixed with a resol type phenol resin and a noblock type phenol resin.

In addition, the epoxy resin of the adhesive composition for halogen-free coverlay film according to the present invention is a polyfunctional non-halogen epoxy resin having two or more epoxy groups per molecule, for example bisphenol A type epoxy resin, bisphenol F type epoxy resin , Phenol noblock type epoxy resins, cresol type epoxy resins, and the like, and two or more kinds of epoxys may be mixed and used. The sum of the applied amounts of the phenol resin and the epoxy resin may be applied in an amount of 50 to 150 weight based on 100 weight of the acrylic resin. If it is less than 50, the heat resistance of the adhesive is weak, and if it is more than 150, the adhesive is too brittle, easily crumbs and weakens.

Further, the curing agent of the adhesive composition for halogen-free coverlay film according to the present invention is not particularly limited as long as it is usually used as an epoxy resin curing agent. Representative examples include amine-based curing agents, acid anhydride-based curing agents, etc., which may be used alone or in combination of two or more. The hardener is preferably used 1 to 20 parts by weight based on 100 parts by weight of the epoxy resin.

Moreover, the hardening accelerator of the adhesive composition for halogen-free coverlay films which concerns on this invention will not be restrict | limited especially if it can accelerate reaction of said epoxy resin and a hardening | curing agent. Typical examples include imidazole compounds such as 2-methylimidazole and 2-ethyl 4-methylimidazole, and phosphine compounds such as triphenylphosphine, tetraphenylphosphine, and tetraphenylborate. It is preferable to use 0.1 to 5 parts by weight based on 100 parts by weight of the epoxy resin.

In addition, as the non-halogen flame retardant of the adhesive composition for halogen-free coverlay film according to the present invention, a flame retardant containing no halogen atoms, for example, phosphorus-based, melamine-based, or fluorine-based compounds may be used. The pyrolysis temperature is 300 deg. C or higher and insoluble in water or in a common organic solvent such as acetone, methyl ethyl ketone and toluene. As a commercial item which satisfy | fills such characteristics, the organic phosphinate compound "Exolit OP935 (made by Clariant, phosphorus content 23 mass%)" is mentioned, for example. The application amount of the flame retardant is applied to 3% or more and 15% or less of the total weight of the adhesive composition. If less than 3%, even when the inorganic particles are applied in excess, it is difficult to achieve flame retardancy (V-0), and when applied to more than 15%, physical properties such as adhesion and heat resistance become poor.

In addition, the inorganic particles of the adhesive composition for halogen-free coverlay film according to the present invention are mainly used to impart heat resistance and flame retardancy to the adhesive, and the punchability is improved by an additional function. Applicable examples include aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, antimony trioxide, silica, and the like. A preferred amount of use is 5 to 30 parts by weight based on 100 parts by weight of the acrylic resin. If the amount is less than 5 parts by weight, the flame retardancy, heat resistance and punching properties of the adhesive is lowered, and if more than 30 parts by weight causes physical property degradation such as workability degradation problems and adhesive strength decrease in the adhesive manufacturing.

In addition, the crosslinking agent of the adhesive composition for halogen-free coverlay film according to the present invention may use an oxazoline-based oil, an inorganic peroxide, and is preferably used by adding 1 to 5 parts by weight based on 100 parts by weight of the acrylic resin.

The adhesive composition for halogen-free coverlay film having the above-mentioned composition is uniformly mixed using organic solvents such as methyl ethyl ketone, methanol, benzyl alcohol, toluene, tetrahydrofuran, and chlorobenzene, and the viscosity at this time is 100 to 2,000 CPS, Preferably it is 200 ~ 800CPS, the coating after drying to a thickness of 25㎛ on the heat-resistant film and cured for 1 to 20 minutes at 50 ~ 170 ℃ and then through the process of laminating a release paper or a release-treated film (lamination) Get a film.

The present invention also includes a coverlay film coated with an adhesive composition for halogen-free coverlay film, wherein the adhesive composition for halogen-free coverlay film is applied on a polyimide base film as an adhesive layer. .

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited by these.

The following is a description of the materials used in the Examples and Comparative Examples.

(1) acrylic resin

A: Brand name: WS-023, Weight average molecular weight: 500,000, HV: 20mgKOH / g, Nagase Chemtex

(2) acrylonitrile butadiene rubber (NBR)

A: Product name: N-34, carboxyl group-containing NBR, Nippon Xeon company

(3) phenolic resin

A: Product name: Hitanol H2181, Resol phenol type resin, Hitachi Chemical Industry

B: Product Name: HF-4M, Noblock Type Phenolic Resin, Meihwa Chemical

(4) epoxy resin

A: Product name: EOCN-104S, Epoxy equivalent: 218, Nippon Chemical Co., Ltd.

B: Product name: YD-011, Epoxy equivalent: 475, Kukdo Chemical Co., Ltd.

(5) curing agent

A: DICY (dician diamide)

(6) curing accelerator

A: 2MI (methylimidazole)

(7) non-halogen flame retardant

A: Brand name: OP-935, Phosphorus content: 23% by weight, phosphinate compound, Clariant

(8) inorganic particles

A: aluminum hydroxide (average particle diameter: 1 mu m)

(9) crosslinking agent

A: 2, 2 '-(1, 3-phenyl) -bis (2-oxazoline)

Example 1

As shown in Table 1 below, each of the components and the methyl ethyl ketone solvent were mixed in a solid content of 30%, and then mixed and dispersed evenly using a homogenizer. After drying on a polyimide film having a thickness of 12.5 μm so as to have a thickness of 25 μm, drying for 10 minutes at 50 ° C. oven, 3 minutes at 160 ° C. oven, heat curing, and then laminating a release paper and covering A ray film was prepared.

[Examples 2 to 4]

A coverlay film was manufactured in the same manner as in Example 1, except that the adhesive components were respectively mixed as in Examples 2 to 4 of Table 1 below.

[Table 1]

ingredient Example 1 Example 2 Example 3 Example 4 Acrylic resin A 100 100 100 100 NBR A 0 0 0 0 Phenolic resin A 30 0 30 30 B 0 30 0 0 Epoxy resin A 40 40 0 20 B 0 0 40 20 Hardener A 3 3 3 3 Hardening accelerator A 0.05 0.05 0.05 0.05 Flame retardant A 15 15 15 15 Inorganic particles A 15 15 15 15 Crosslinking agent A One One One One

[Comparative Examples 1 to 7]

A coverlay film was prepared in the same manner as in Example 1, except that the adhesive components were respectively mixed as in Comparative Examples 1 to 7 of Table 2 below.

TABLE 2

ingredient Comparative example
One Comparative example
2 Comparative example
3 Comparative example
4 Comparative example
5 Comparative example
6 Comparative example
7 Acrylic resin A 0 0 0 0 100 100 100 NBR A 100 100 100 100 0 0 0 Phenolic resin A 30 0 30 30 30 30 30 B 0 30 0 0 0 0 0 Epoxy resin A 40 40 0 20 40 40 40 B 0 0 40 20 0 0 0 Hardener A 3 3 3 3 3 3 3 Hardening accelerator A 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Flame retardant A 15 15 15 15 0 15 15 Inorganic particles A 15 15 15 15 15 0 15 Crosslinking agent A One One One One One One 0

The properties of the coverlay film obtained by the same composition and method as in the above Examples and Comparative Examples were evaluated in the following manners, and the results are shown in Tables 3 and 4 below.

[Characteristic Evaluation Method]

1. Adhesion

Each coverlay film prepared as in Examples and Comparative Examples was attached to a 35 μm thick electrolytic copper foil using a hot press under a condition of 160 ° C./40 kgf / 30 min, cut into 1 cm in width and 10 cm in length, and then The mid film is fixed, the copper foil is pulled at a speed of 50 mm / min in the direction of a 90 degree angle, the force at that time is measured, and the average value is expressed as adhesive force (JIS C6481).

2. hygroscopic adhesion

After fabrication of the specimen in the same manner as the method of measuring the adhesion strength, using a thermo-hygrostat is exposed to moisture for 40 hours at 40 ℃ / 90 RH% conditions. Thereafter, the measurement was performed in the same manner as in the above-described adhesive force measurement method.

3. soldering heat resistance

After attaching the electrolytic copper foil and coverlay film in the same way as measuring the adhesive force, cut it into 5cm X 5cm, float it in a solder bath at the set temperature for 10 seconds and take it out to see the change in appearance such as peeling and discoloration. The highest temperature not occurring was measured. The measurement was carried out in 10 ℃ increments from 210 to 340 ℃ and all three specimens were evaluated at each temperature and considered OK at that temperature.

4. Hygroscopic soldering heat resistance

After the specimen is prepared in the same manner as the method for measuring the soldering heat resistance, it is exposed to moisture for 96 hours at 40 ° C./90 RH% using a thermo-hygrostat. Then, the same measurement as the soldering heat resistance measuring method described above.

5. Flame retardant

Each prepared coverlay film was prepared using a coverlay film prepared by the method of Example 1 and adhesive surfaces were adhered to each other using a hot press under a condition of 160 ° C / 40kgf / 30min. The flame retardancy was evaluated by the standard of 0. If the result was passed, it was marked as “○” and in the case of failed, it was marked as “X”.

Table 3 Example Property Evaluation Results

Item Example 1 Example 2 Example 3 Example 4 Adhesive force (N / cm) 14 11 15 12 Hygroscopic Adhesion (N / cm) 13 11 12 11 Soldering heat resistance (℃) > 340 > 340 > 340 > 340 Hygroscopic Soldering Heat Resistance (℃) 270 280 260 270 Flame retardant (V-0) ○ ○ ○ ○

Table 4 Comparative Example Characteristic Evaluation Results

Item Comparative example
One Comparative example
2 Comparative example
3 Comparative example
4 Comparative example
5 Comparative example
6 Comparative example
7 Adhesive force (N / cm) 15 13 15 13 15 16 14 Hygroscopic Adhesion (N / cm) 8 5 7 6 14 15 10 Soldering heat resistance (℃) > 340 > 340 > 340 > 340 > 340 > 340 > 340 Hygroscopic Soldering Heat Resistance (℃) 220 230 210 220 280 270 250 Flame retardant (V-0) O O O O X X O

In general, suitable characteristics of the coverlay film for practical use should be at least 10 N / cm adhesion, even in the case of hygroscopic adhesion is required to be at least 8 N / cm. In addition, in the case of soldering heat resistance, at least 290 ° C or higher at the initial stage and 260 ° C or higher are required after the moisture absorption. In case of flame retardancy, V-0 is required. The coverlay film must satisfy all of the above properties at the same time.

According to the results of the evaluation of the characteristics of the Examples and Comparative Examples of Tables 3 and 4, in the case of Examples, all the characteristics of adhesion, moisture absorption adhesion, soldering heat resistance, moisture absorption soldering heat resistance, and flame retardancy are satisfied, but in case of Comparative Example, not all characteristics are satisfied. Able to know. In the case of the coverlay films of Comparative Examples 1 to 4, that is, when the NBR is applied as in the conventional technology, the properties before the moisture absorption is excellent, but it can be seen that the properties after the moisture absorption are greatly reduced. This is because there are carbon and carbon double bonds in the molecular structure of NBR because these parts are structurally weak and are easily disconnected due to oxidation and moisture absorption. The breakage of these molecules reduces the elasticity of the rubber and causes degradation of physical properties. On the other hand, the acrylic resin according to the embodiment of the present invention has a completely saturated structure without the unsaturated structure in the molecule, so that there is no or small decrease in physical properties due to oxidation and moisture absorption. In addition, in Comparative Examples 5 and 6, there is no flame retardant or inorganic particles, or when only one of them is applied, it shows difficulty in achieving flame retardancy. And in the case of Comparative Example 7, it can be seen that due to the absence of the crosslinking agent, the crosslinking of the adhesive is insufficient and the moisture absorption solder heat resistance characteristics are insufficient.

1 is a cross-sectional view of a coverlay film according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

10: polyimide film 20: adhesive

30: release paper

Claims (2)

In the adhesive composition for halogen-free coverlay film, (1) hydroxy group include a carboxyl group, and is 300,000 ~ 800,000 weight-average molecular weight, a viscosity at 25 ℃ of 800 ~ 10,000 cP acrylic resin 100 parts by weight, (2) 30 weight part of phenol resins, (3) 40 parts by weight of a polyfunctional epoxy resin having two or more epoxy groups per molecule, (4) 1 to 20 parts by weight of a curing agent, (5) 0.1 to 5 parts by weight of a curing accelerator, (6) non-halogen flame retardants (3-15% of the total composition weight), (7) 5 to 30 parts by weight of inorganic particles, and (8) The adhesive composition for halogen-free coverlay films containing 1-5 weight part of crosslinking agents. The adhesive composition for halogen-free coverlay films of Claim 1 was apply | coated on the polyimide base film as an adhesive bond layer, The coverlay film which apply | coated the adhesive composition for halogen-free coverlay films characterized by the above-mentioned.

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