KR20090078051A - Adhesive composition for halogen-free coverlay film and coverlay film having same - Google Patents

Abstract

The present invention relates to an adhesive composition for a halogen-free coverlay film used in the manufacture of a coverlay film for circuit protection of a flexible printed circuit board, and a coverlay film having the same. More specifically, the flame retardancy and adhesion required in a coverlay film The present invention relates to an adhesive composition for a halogen-free coverlay film that satisfies all properties such as heat resistance, bleed-out, and flowability, and a coverlay film having the same. To this end, the adhesive composition for halogen-free coverlay film according to the present invention comprises (1) a carboxyl group, a molecular weight of 10,000 to 200,000, and an acrylonitrile content of 20 to 40 parts by weight of nitrile butadiene rubber (NBR), (2) a non-halogen polyfunctional epoxy resin having two or more epoxy groups per molecule and having a molecular weight of 200 to 1,000 or less, (3) a curing agent, (4) a curing accelerator, and (5) a non-halogen phosphorus flame retardant, A non-halogen phosphorus flame retardant having a phosphorus content of 10% by mass or more and a pyrolysis temperature of 300 ° C or more, and (6) inorganic particles such as aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, antimony trioxide or silica. do.

Description

Adhesive composition for a halogen-free coverlay film and a coverlay film having the same {Adhesive Composition for Halogen-Free Coverlay Film and Coverlay Film Using the Same}

The present invention relates to an adhesive composition for a halogen-free coverlay film used in the manufacture of a coverlay film for circuit protection of a flexible printed circuit board, and a coverlay film having the same. More specifically, the flame retardancy and adhesion required in a coverlay film The present invention relates to an adhesive composition for a halogen-free coverlay film that satisfies all properties such as heat resistance, bleed-out, and flowability, and a coverlay film having the same.

Recently, the application of flexible circuit boards has exploded with the trend of miniaturization, thinning, and high integration of electronic products. Accordingly, the use of coverlay films for circuit protection is also increasing, and the adhesion, heat resistance, flame retardancy, flowability, etc. There is an urgent need for improved performance.

In recent years, the development of environmentally friendly materials is also required by WEEE- and RoHS of Europe. However, conventional adhesives used in electronic materials such as coverlay films and semiconductor sealing materials are flame retardants and compounds containing halogen elements such as bromine have the problem of generating toxic gases such as dioxins based compounds. 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, adhesion, flame retardancy, flowability, etc. are important required properties, and all of these characteristics must be provided. Therefore, even halogen-free is required.

Conventional coverlay adhesives have been widely used in epoxy, acrylic resin, phenolic resin, polyester, and the like, but all of them use halogen flame retardants such as bromine, which is vulnerable to environmental problems. Therefore, in recent years, a coverlay film using various halogen-free flame retardants without halogen-based flame retardants has been developed, but does not satisfy all physical properties.

The present invention has been made in order to provide an adhesive composition for a halogen-free coverlay film and a coverlay film having the same, which satisfies all the above-described characteristics, and an object of the present invention is to provide a coverlay film. It is an object of the present invention to provide an adhesive composition for a halogen-free cover film and a coverlay film having the same, which satisfy all of properties such as flame retardancy, adhesion, heat resistance, bleed-out, and flowability.

The object is (1) a nitrile butadiene rubber (NBR) containing a carboxyl group, having a molecular weight of 10,000 to 200,000 and an acrylonitrile content of 20 to 40 parts by weight, and (2) two or more epoxy groups per molecule. Having a molecular weight of 200 to 1,000 or less, as a non-halogen polyfunctional epoxy resin, (3) curing agent, (4) curing accelerator, and (5) non-halogen phosphorus flame retardant, phosphorus content is 10 mass% or more, and pyrolysis temperature A non-halogen phosphorus-based flame retardant having a temperature of 300 ° C. or higher and (6) an inorganic composition such as aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, antimony trioxide or silica, comprising an adhesive composition for a halogen-free coverlay film. Is achieved.

Here, the weight ratio of the non-halogen phosphorus-based flame retardant and the inorganic particles in the components of the adhesive composition is the following conditions, (1) Y is less than or equal to [-X + 30] (Y ≤ -X + 30), X is greater than or equal to 6 and less than or equal to 25 (6 ≤ X ≤ 25), and (2) if X is greater than or equal to 6 and less than or equal to 8 (6 ≤ X ≤ 8), then Y is Is greater than or equal to [-2X + 22] (Y ≥ -2X + 22), and if X is greater than or equal to 8 and less than or equal to 12 (8 ≤ X ≤ 12), then Y is [-X + 14] If greater than or equal to (Y ≥ -X + 14) and X is greater than or equal to 12 and less than or equal to 25 (12 ≤ X ≤ 25), then Y is greater than or equal to 2 (Y ≥ 2). Where "X" is "weight of non-halogen phosphorus flame retardant to 100 weight of adhesive composition" and "Y" is "100 weight of adhesive composition to weight of non-inorganic particles".

Preferably, the non-halogen phosphorus flame retardant is an organic phosphinate compound flame retardant, and the inorganic particles are characterized in that the aluminum hydroxide.

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

According to the present invention, it has the effect of satisfying all the properties such as flame retardancy, adhesion, heat resistance, bleed out and flow required in the coverlay film.

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. .

The carboxyl group-containing nitrile butadiene rubber (hereinafter also referred to as "NBR") containing a carboxyl group of the adhesive composition for halogen-free coverlay film according to the present invention has a weight average molecular weight of 2,000 to 200,000 and preferably has a molecular weight of 10,000 to 200,000. The acrylonitrile content is 10 to 60% by weight, preferably 20 to 40% by weight, and the carboxyl group content is 5 to 20% by weight. At this time, when the weight average molecular weight is lower than 10,000, the thermal stability is poor, and when the weight average molecular weight is higher than 200,000, the solubility in the solvent is deteriorated, the viscosity increases during solution preparation, and the workability is poor, and the adhesion is also lowered. In addition, when the acrylonitrile content is lower than 20% by weight, the solvent solubility is lowered. When the acrylonitrile content is higher than 40% by weight, the electrical insulation is poor. And when the content rate of the carboxyl group is 5 to 20% by weight, the adhesion between NBR and other resins, and the adhesive substrate is easy to facilitate the adhesion.

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 Resins, phenol noblock type epoxy resins, cresol type epoxy resins, and the like, and the epoxy resins may be used alone or in combination. The polyfunctional non-halogen epoxy resin may be added in an amount of 50 to 200 parts by weight based on 100 parts by weight of NBR, and an equivalent (g / eq) of epoxy may be 200 to 1000. If the content of the polyfunctional non-halogen epoxy resin is less than 50 parts by weight, the adhesive force and the heat resistance are greatly reduced, and it is not applicable. If the amount is more than 200 parts by weight, the adhesive is too brittle. Maintenance of the film state becomes impossible.

In addition, 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 commonly used as an epoxy resin curing agent. Typical examples include an amine curing agent, an acid anhydride curing agent, a phenol resin curing agent, and the like, which may be used alone or in combination of two or more thereof. The curing agent may be used 1 to 20 parts by weight based on 100 parts by weight of the epoxy resin.

In addition, oil and inorganic peroxides may be used as the rubber crosslinking agent, and may be used by adding 1 to 5 parts by weight with respect to 100 NBR.

In addition, the curing accelerator of the adhesive composition for halogen-free coverlay film according to the present invention is not particularly limited as long as it can promote the reaction between the epoxy resin and the 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. . These may also be used alone or in combination of two or more and 0.1 to 5 parts by weight based on 100 parts by weight of the epoxy resin.

In addition, as a non-halogen-based flame retardant of the adhesive composition for halogen-free coverlay film according to the present invention, a phosphorus-based compound is used as a flame retardant that does not contain a halogen atom, and as a required characteristic, the phosphorus content is 10% by mass or more, and pyrolysis temperature Is preferably 300 ° C. or higher and insoluble in water or a common organic solvent, such as acetone, methyl ethyl ketone, toluene, or the like. As a commercial item which satisfy | fills these characteristics, the organic phosphinate compound "Exolit OP935 (made by Clariant, 23 mass% of phosphorus content)" is mentioned, for example.

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. Preferred application amounts are 20 to 60 parts by weight relative to NBR 100 weight. If the application amount is 20 parts by weight or less, the flame retardancy, heat resistance and punching properties of the adhesive is lowered, and when 60 parts by weight or more, the physical properties such as decrease in adhesive flow property, decrease in adhesive strength occurs.

Further, among the components of the adhesive composition for halogen-free coverlay film according to the present invention, the weight ratio of the non-halogen phosphorus-based flame retardant and the inorganic particles is that (1) Y is less than or equal to [-X + 30] (Y ≤- X + 30), where X is greater than or equal to 6 and less than or equal to 25 (6 ≤ X ≤ 25), and (2) if X is greater than or equal to 6 and less than or equal to 8 (6 ≤ X ≤) 8), Y is greater than or equal to [-2X + 22] (Y ≥ -2X + 22), and if X is greater than or equal to 8 and less than or equal to 12 (8 ≤ X ≤ 12), then Y is Is greater than or equal to [-X + 14] (Y ≥ -X + 14), and if X is greater than or equal to 12 and less than or equal to 25 (12 ≤ X ≤ 25), then Y is greater than or equal to 2 ( Y ≥ 2) The condition must be satisfied. Here, "X" represents "the weight of the non-halogen phosphorus flame retardant to 100 weight of the adhesive composition", and "Y" represents the "weight of the inorganic particle to 100 weight of the adhesive composition".

Adhesive composition consisting of the above composition is uniformly mixed using an organic solvent such as methyl ethyl ketone, methanol, benzyl alcohol, toluene, tetrahydrofuran, chlorobenzene, the viscosity is 100 ~ 2,000CPS, preferably 200 ~ 800CPS After coating on the heat-resistant film so that the thickness after drying is 25㎛ and cured for 1 to 10 minutes at 50 ~ 170 ℃ through a process of laminating a release paper or a release-treated film (lamination) to obtain a coverlay film.

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

Materials used in Examples and Comparative Examples are as follows.

(1) NBR

A: 27 weight% of acrylonitrile, 3.5 weight% of carboxyl groups

(2) epoxy resin

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

B: Product name: Epicoat 828, Epoxy equivalent: 185, Japanese epoxy resin

C: Product name: EOCN-103, Epoxy equivalent: 209, Nippon Chemical Industries, Ltd.

(3) curing agent

A: DDS (diaminodiphenylsulfone)

B: Product name: HF-3M, OH equivalents: 107

(4) curing accelerator

A: 2MI (methylimidazole)

(5) non-halogen flame retardant

A: Product name: OP-935, Phosphorus content: 23 weight%, a phosphinate compound, Clariant company, pyrolysis temperature is 300 degreeC or more.

B: trade name: SPB-100, phosphorus content: 13% by weight, phosphazene compound, Otsuka Chemical Co., Ltd., pyrolysis temperature is less than 300 ℃.

(6) inorganic particles

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

<Example 1>

As shown in Table 1, the components consisting of each weight part and the methyl ethyl ketone solvent are mixed in a solid content of 30%, and then uniformly mixed and dispersed using a homogenizer. After the coating was applied on a polyimide film having a thickness of 12.5 μm so as to have a thickness of 25 μm, dried for 10 minutes at 50 ° C. in an oven and 3 minutes in an oven at 160 ° C., and thermally cured, and then laminated with a release paper. A coverlay film was prepared.

<Examples 2 to 14>

A coverlay film was prepared in the same manner as in Example 1, except that the adhesive components were mixed as in Examples 2 to 14 of Table 1, respectively.

Table 1 Example Composition Table (parts by weight)

NBR Epoxy resin Hardener Curing accelerator Flame retardant Inorganic particles A A B C A B A A B A Example 1 30 30 10 0 5 0 0.05 7.0 0.0 18.0 Example 2 30 30 10 0 5 0 0.05 5.5 0.0 9.0 Example 3 30 30 10 0 5 0 0.05 7.0 0.0 5.5 Example 4 30 30 10 0 5 0 0.05 9.0 0.0 3.5 Example 5 30 30 10 0 5 0 0.05 10.5 0.0 1.8 Example 6 30 30 10 0 5 0 0.05 12.5 0.0 1.8 Example 7 30 30 10 0 5 0 0.05 21.7 0.0 2.0 Example 8 30 30 10 0 5 0 0.05 25.7 0.0 2.1 Example 9 30 30 0 10 2 5 0.05 7.4 0.0 5.5 Example 10 30 30 10 0 5 0 0.05 6.5 0.0 25.8 Example 11 30 30 10 0 5 0 0.05 10.7 0.0 21.3 Example 12 30 30 10 0 5 0 0.05 15.0 0.0 17.2 Example 13 30 30 10 0 5 0 0.05 25.7 0.0 6.4 Example 14 30 30 10 0 5 0 0.05 26.7 0.0 5.3

<Comparative Examples 1 to 13>

A coverlay film was manufactured in the same manner as in Example 1, except that the adhesive components were mixed as in Comparative Examples 1 to 13 of Table 2, respectively.

[Table 2] Comparative Example Composition Table (parts by weight)

NBR Epoxy resin Hardener Curing accelerator Flame retardant Inorganic particles A A B C A B A A B A Comparative Example 1 30 30 10 0 5 0 0.05 0.0 0.0 23.0 Comparative Example 2 30 30 10 0 5 0 0.05 2.0 0.0 18.0 Comparative Example 3 30 30 10 0 5 0 0.05 4.0 0.0 16.0 Comparative Example 4 30 30 10 0 5 0 0.05 5.3 0.0 7.2 Comparative Example 5 30 30 10 0 5 0 0.05 6.8 0.0 3.0 Comparative Example 6 30 30 10 0 5 0 0.05 8.5 0.0 1.7 Comparative Example 7 30 30 10 0 5 0 0.05 14.0 0.0 25.0 Comparative Example 8 30 30 10 0 5 0 0.05 18.5 0.0 21.0 Comparative Example 9 30 30 10 0 5 0 0.05 26.0 0.0 17.0 Comparative Example 10 30 30 10 0 5 0 0.05 30.0 0.0 9.2 Comparative Example 11 30 30 10 0 5 0 0.05 0.0 0.0 33.0 Comparative Example 12 30 30 10 0 5 0 0.05 0.0 7.0 18.0 Comparative Example 13 30 30 10 0 5 0 0.05 0.0 9.0 16.0

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

[Characteristic Evaluation Method]

1. Adhesion

Each coverlay film prepared as in Example and Comparative Example was cut to 1 cm in width and 10 cm in length after being attached to a 35 μm thick electrolytic copper foil using a hot press under the conditions of 170 ° C. / 40 kg _f / 40 min. The polyimide film is fixed, the copper foil is pulled at a speed of 50 mm / min in the direction of an angle of 90 degrees, the force at that time is measured, and the average value is expressed as the adhesive force (JIS C6481).

2. 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, immerse it in a solder bath at the set temperature for 10 seconds, take it out and look for changes in appearance such as peeling and discoloration. The highest temperature not occurring was measured.

3. Flame retardant

Each prepared coverlay film was prepared using the coverlay film prepared by the method of Example 1 and the adhesive surfaces were adhered to each other using a hot press under a condition of 170 ° C./40kg _f / 40min. The flame retardancy was evaluated according to the standard of -0, and the result was marked as "○" and the result was marked as "X" in case of failure.

4. bleed out

Each prepared coverlay film was drilled with 5 circular holes with a diameter of 5 mm at intervals of 2 cm, and was attached to a 35 μm thick electrolytic copper foil using a hot press under a condition of 170 ° C. / 40 kg _f / 40 min. When the adhesive flowed out through the microscope was observed under the microscope and the appearance of the adhesive was regular and there was no discoloration, it was marked with "○". , 2, 3).

5. Flowability

After forming a flexible copper foil laminate with a width of 1mm pattern as shown in FIG. 4, each coverlay film was bonded to each other using a hot press under a condition of 170 ° C./40kg _f / 40min, and then a circuit pattern. Observing through the microscope whether the adhesive of the coverlay film was filled with 100% was indicated as "○" at 100% filling and "X" when there was no filling.

Table 3 Example Results

Flame Retardant (V-O) Adhesion (N / cm) Soldering Heat Resistance (℃) Bleed out Flow Example 1 ○ 12 330 ○ ○ Example 2 ○ 14 330 ○ ○ Example 3 ○ 13 330 ○ ○ Example 4 ○ 12 330 ○ ○ Example 5 ○ 11 330 ○ ○ Example 6 ○ 10 320 ○ ○ Example 7 ○ 6 300 ○ ○ Example 8 ○ 6 290 ○ ○ Example 9 ○ 12 340 ○ ○ Example 10 ○ 8 320 ○ ○ Example 11 ○ 7 320 ○ ○ Example 12 ○ 7 310 ○ ○ Example 13 ○ 6 300 ○ ○ Example 14 ○ 6 300 ○ ○

Table 4 Comparative Example

Flame Retardant (V-O) Adhesion (N / cm) Soldering Heat Resistance (℃) Bleed out Flow Comparative Example 1 X 12 330 ○ ○ Comparative Example 2 X 12 340 ○ ○ Comparative Example 3 X 12 330 ○ ○ Comparative Example 4 X 12 330 ○ ○ Comparative Example 5 X 12 330 ○ ○ Comparative Example 6 X 10 320 ○ ○ Comparative Example 7 ○ 5 310 ○ X Comparative Example 8 ○ 4 300 ○ X Comparative Example 9 ○ 3 280 ○ X Comparative Example 10 ○ 2 280 ○ X Comparative Example 11 X 7 300 ○ X Comparative Example 12 ○ 14 330 X ○ Comparative Example 13 ○ 14 330 X ○

For practical coverlay film characteristics, UL 94 V-0 must be satisfied unconditionally, and the adhesive force should be 6 N / cm or more under milder conditions than general coverlays containing halogen elements. Irregular adhesives and the like should be passed (○) level because they cause defects in the subsequent plating process. In addition, in case of the flow characteristic, the coverlay adhesive must be 100% filled (passed) because it causes a disconnection of the pattern and a problem of lifting due to bubbles when the circuit pattern is not filled.

However, when the results of Comparative Examples are detailed (Table 4), in Comparative Examples 1 and 11, halogen-free phosphorus-based flame retardants are not included, and thus flame retardancy is not satisfied. In Comparative Examples 2, 3, 4, 5, and 6, flame retardants and Inorganic particles were used, but too little was applied to satisfy the flame retardancy. On the contrary, in Comparative Examples 7, 8, 9, and 10, too many flame retardants and inorganic particles were used, and thus the flame retardancy was satisfied but the flowability was not satisfied. In addition, in the case of Comparative Examples 12 and 13, a non-halogen phosphorus-based flame retardant was applied, but since the pyrolysis temperature was low (less than 300 ° C.), bleed-out characteristics could be failed even if other physical properties were satisfied.

Table 3, which is a result of the embodiment according to the present invention, satisfies UL 94 V-0, the adhesive force is 6 N / cm or more, and all of the bleed-out characteristics are pass levels, and also in the case of flow characteristics. Since it is in the state of being charged, the circuit pattern does not cause disconnection of the pattern, the problem of lifting due to bubbles, etc., but it can be seen that the above examples do not satisfy all of the above conditions.

1 is a side view of a coverlay film attached to an electrolytic copper foil.

It is a schematic diagram which shows the bleed out characteristic of a pass ((circle)) level.

Figure 3 is a schematic diagram showing the bleed out characteristics of the reject (X) level.

It is a schematic diagram of the flexible copper foil laminated board with a pattern formed.

<Brief description of symbols for the main parts of the drawings>

1: coverlay film 2: electrolytic copper foil

3: adhesive leaked from the coverlay film

4: Copper pattern formed in 1mm width

Claims (4)

In the adhesive composition for halogen-free coverlay film, (1) containing a carboxyl group, having a molecular weight of 10,000 to 200,000, acrylonitrile content of 20 to 40% by weight, phosphorus nitrile butadiene rubber (NBR), (2) a non-halogen polyfunctional epoxy resin having two or more epoxy groups per molecule and having a molecular weight of 200 to 1,000 or less; (3) a curing agent, (4) a curing accelerator, (5) Non-halogen phosphorus flame retardant, non-halogen phosphorus flame retardant whose phosphorus content is 10 mass% or more, and pyrolysis temperature is 300 degreeC or more, and (6) An adhesive composition for halogen-free coverlay film comprising inorganic particles such as aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, antimony trioxide or silica. The method of claim 1, The weight ratio of the non-halogen phosphorus flame retardant and the inorganic particles in the components of the adhesive composition is the following conditions, (1) Y is less than or equal to [-X + 30] (Y ≤ -X + 30), where X is greater than or equal to 6 and less than or equal to 25 (6 ≤ X ≤ 25), (2) where X is greater than or equal to 6 and less than or equal to 8 (6 ≦ X ≦ 8), then Y is greater than or equal to [-2X + 22] (Y ≥ -2X + 22), If X is greater than or equal to 8 and less than or equal to 12 (8 ≤ X ≤ 12), then Y is greater than or equal to [-X + 14] (Y ≥ -X + 14), When X is greater than or equal to 12 and less than or equal to 25 (12 ≦ X ≦ 25), Y satisfies the condition that is greater than or equal to 2 (Y ≥ 2), Wherein "X" is "weight of non-halogen phosphorus flame retardant to 100 weight of adhesive composition" and "Y" is "weight of inorganic particles to 100 weight of adhesive composition", halogen-free coverlay Adhesive composition for films. The method of claim 2, The non-halogen phosphorus flame retardant is an organic phosphinate compound flame retardant, wherein the inorganic particles are aluminum hydroxide, adhesive composition for a halogen-free coverlay film. The adhesive composition for halogen-free coverlay films according to any one of claims 1 to 3 is applied onto a polyimide base film as an adhesive layer. Coverlay film to be provided.

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