KR101074858B1 - Adhesive Composition for Halogen-Free Coverlay Film and Coverlay Film Using the 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, flowability, and the like, 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 weight average molecular weight of 10,000 to 200,000, an acrylonitrile content of 20 to 40% by weight and a carboxyl group content of 3 to 15 Nitrile-butadiene rubber (NBR) in weight%, (2) Non-halogen polyfunctional solid epoxy resin and liquid epoxy resin having two or more epoxy groups per molecule and having an EEW (g / eq) of 100 to 1,000, (3) a curing agent And inorganic particles such as (4) a curing accelerator, (5) a non-halogen phosphorus flame retardant, and (6) aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, antimony trioxide or silica.

Nitrile Butadiene Rubber, Non-Halogen Polyfunctional Epoxy Resin, Hardener, Non-Halogen Phosphorus Flame Retardant, Inorganic Particles

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, flowability, and the like, 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, development of environment-friendly materials has been 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 one side of the heat-resistant film of Figure 1 and consists 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 flame retardancy, adhesive strength, And an adhesive composition for a halogen-free coverlay film that satisfies all characteristics such as heat resistance, and particularly, flow patterns are becoming more important due to the thinning and high density of electronic materials in recent years, and coverlays having the same. It is to provide a film.

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

The purpose is (1) nitrile-butadiene rubber (NBR) containing a carboxyl group, having a weight average molecular weight of 10,000 to 200,000, an acrylonitrile content of 20 to 40% by weight and a carboxyl group content of 3 to 15% by weight. 2) Non-halogen multifunctional solid epoxy resin and liquid epoxy resin having two or more epoxy groups per molecule and having an EEW (g / eq) of 100 to 1,000, (3) curing agent, (4) curing accelerator, (5) ratio It is achieved by an adhesive composition for halogen-free coverlay films comprising a halogen phosphorus flame retardant and (6) inorganic particles such as aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, antimony trioxide or silica.

Here, the mixing ratio of the non-halogen multifunctional epoxy resin among the components of the adhesive composition is characterized in that 10 to 40 weight of the liquid epoxy resin to 100 weight of the solid epoxy resin.

Preferably, 50 to 200 parts by weight of the epoxy resin, 100 to 7 parts by weight of the non-halogen phosphorus flame retardant and 20 to 60 parts by weight of the inorganic particles, and 100 to the weight of the epoxy resin, based on 100 parts by weight of the nitrile butadiene rubber. It is characterized by including 1 to 20 parts by weight of a curing agent and 0.1 to 5 parts by weight of the curing accelerator.

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 properties such as flame retardancy, adhesion, heat resistance, and flowability 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. .

Adhesive composition for halogen-free coverlay film according to the present invention is a nitrile butadiene rubber (hereinafter also referred to as "NBR"), non-halogen multifunctional solid epoxy resin and liquid epoxy resin, curing agent, curing accelerator, non-halogen phosphorus flame retardant and It is characterized by including inorganic particles.

The nitrile butadiene rubber of the adhesive composition for halogen-free coverlay film according to the present invention is a carboxyl group-containing nitrile butadiene rubber having a weight average molecular weight of 2,000 to 200,000, preferably a molecular weight of 10,000 to 200,000, and the acrylonitrile content is It is 10-60 weight%, Preferably it is 20-40 weight%, and a carboxyl group content rate shall be 3-15 weight%. Here, 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, and when higher than 40% by weight, the electrical insulation is poor. And when the content rate of the carboxyl group is 3 to 15% 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 may be a multifunctional non-halogen epoxy resin having two or more epoxy groups per molecule, for example bisphenol A epoxy resin, bisphenol F type Epoxy resins, phenol noblock type epoxy resins, cresol type epoxy resins, and the like, and the epoxy resin is used by mixing a solid epoxy resin and a liquid epoxy resin. This is because when the solid epoxy resin is used, the wettability to the adherend is poor, and thus the adhesion and flow are inferior. On the contrary, when the liquid epoxy is used only, the wettability of the adhesive is too high and the workability is inferior. The preferred mixing ratio is 10 to 40 weight of liquid epoxy resin to 100 weight of solid epoxy resin. And EEW (g / eq) of the epoxy resin is preferably 100 to 1,000, it can be used 50 to 200 parts by weight compared to the NBR 100 weight.

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, an oil and an inorganic peroxide may be used as the rubber crosslinking agent, and may be used by adding 1 to 5 parts by weight based on the NBR 100 weight.

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 the non-halogen 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, phosphorus content is 10 mass% or more, and thermal decomposition It is preferable that temperature is 300 degreeC or more, and it does not melt | dissolve in water or a normal organic solvent, ie, acetone, methyl ethyl ketone, toluene, etc. solvent. 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. In addition, 7 to 50 parts by weight with respect to the NBR 100 weight may be applied to expect the UL-94 V-0 grade, it can also prevent the degradation of the coverlay adhesive properties .

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 punching property 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.

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 with reference to Examples and Comparative Examples. However, the present invention is not limited by these.

(1) NBR

A: Product name: PNR 1H, number average molecular weight: 80,000, acrylonitrile 27 wt%, carboxyl group 4.1 wt%, JSR

(2) epoxy resin

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

B: Product name: EOCN-103, Epoxy equivalent: 209, Type: Solid phase, Nippon Chemical Industries

C: Product name: YD-128M, Epoxy equivalent: 184, Type: Liquid phase, Kukdo Chemical Co., 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: Brand name: OP-935, Phosphorus content: 23% by weight, phosphinate compound, Clariant

(6) inorganic particles

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

≪ Example 1 >

As shown in Table 1, after mixing the respective components and the methyl ethyl ketone solvent in a solid content of 30%, using a homogenizer (homogenizer) is uniformly mixed and dispersed. After coating 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 and 3 minutes at 160 ° C. oven, thermal curing, and then laminating a release paper, A coverlay film was prepared.

<Examples 2 to 5>

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 5 of Table 1, respectively.

Table 1 Example Composition Table

ingredient Example 1 Example 2 Example 3 Example 4 Example 5 NBR A 30 30 30 30 30 Epoxy resin A 30 0 15 30 30 B 0 30 15 0 0 C 10 10 10 3 12 Hardener A 3 One 3 3 3 B 0 3 2 0 0 Curing accelerator A 0.05 0.05 0.05 0.05 0.05 Flame retardant A 15 15 15 15 15 Inorganic particles A 15 15 15 15 15

<Comparative Examples 1 to 9>

A coverlay film was manufactured in the same manner as in Example 1, except that the adhesive components were respectively mixed as in Comparative Examples 1 to 9 of Table 2 below.

Table 2 Comparative Example Composition Table

ingredient Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 NBR A 30 30 30 30 30 30 30 30 30 Epoxy
Suzy A 40 0 0 30 30 30 30 30 30 B 0 40 0 0 0 0 0 0 0 C 0 0 40 One 15 20 10 10 10 Hardener A 3 0 4 3 3 4 3 3 3 B 0 4 0 0 0 0 0 0 0 Hardening
accelerant A 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Flame retardant A 15 15 15 15 15 15 15 0 0 Inorganic particles A 15 15 15 15 15 15 0 15 30

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 attachment to a 35 μm thick electrolytic copper foil using a hot press under conditions of 160 ° 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, float it for 10 seconds in the solder bath of the set temperature, take it out and look for changes in appearance such as peeling and discoloration. The highest temperature not occurring was measured. Measurement was carried out in 10 ℃ increments up to 260 ~ 340 ℃.

3. 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 / 40kg _f / 40min. The flame retardancy was evaluated by the standard of -0, and when the result was passed, it was marked as "○", and in case of rejection, it was marked as "X".

4. Flowability

The flexible copper foil laminate (copper foil thickness 35㎛) was formed in a circuit with a width of 0.5mm pattern as shown in Fig. 2, and then each coverlay film was hot pressed under the conditions of 160 ° C / 40kg _f / 40min. After bonding with the circuit pattern, the cover pattern of the adhesive film of the coverlay film was 100% filled by observing through a microscope and marked with "○" when 100% filled, "X" when there is an unfilled part.

5. Processability

The flexible copper foil laminate (copper foil thickness 35㎛) was formed in a circuit with a width of 0.5mm pattern as shown in Fig. 2, and then each coverlay film cut into a size of 10cm x 10cm was placed on the patterned side with the adhesive facing the pattern and moved by hand. If the coverlay film does not wrinkle and move well, “○” wrinkles or if it does not move, it is marked with “X”.

Table 3 Example Results

Item Example 1 Example 2 Example 3 Example 4 Example 5 Adhesive force (N / cm) 14 11 12 9 16 Soldering heat resistance (℃) > 340 > 340 > 340 > 340 > 340 Flame retardant (V-0) ○ ○ ○ ○ ○ Flow ○ ○ ○ ○ ○ Machinability ○ ○ ○ ○ ○

Table 4 Comparative Example

Item compare
Example 1 compare
Example 2 compare
Example 3 compare
Example 4 compare
Example 5 compare
Example 6 compare
Example 7 compare
Example 8 compare
Example 9 Adhesive force (N / cm) 6 4 11 7 15 17 16 17 13 soldering
Heat resistance (℃) > 340 320 280 320 > 340 > 340 > 340 > 340 290 Flame retardant
(V-0) ○ ○ ○ ○ ○ ○ X X X Flow X X O X ○ ○ ○ ○ ○ Machinability ○ ○ X ○ X 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. When working in a company, the work is actually done to accurately match the width and length of the copper clad laminate and the coverlay. 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.

According to the results of the present invention according to the present invention of Table 3, all satisfy the UL 94 V-0, the adhesive force is 6 N / cm or more, all of the workability characteristics pass level, and also flowability characteristics 100 Since it is in the state of being charged in%, the circuit pattern does not cause disconnection of the pattern, the problem of lifting due to bubbles, etc., but in the comparative examples, all of the above conditions are not satisfied.

1 is a cross-sectional view of a conventional coverlay film.

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

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

10: polyimide film 20: adhesive

30: release paper 40: copper (copper) pattern

Claims (4)

delete delete In the adhesive composition for halogen-free coverlay film, (1) nitrile butadiene rubber (NBR) containing a carboxyl group, having a weight average molecular weight of 10,000 to 200,000, an acrylonitrile content of 20 to 40% by weight and a carboxyl group content of 3 to 15% by weight; (2) a non-halogen polyfunctional solid epoxy resin and a liquid epoxy resin having two or more epoxy groups per molecule and having an EEW (g / eq) of 100 to 1,000; (3) curing agent, (4) curing accelerator, (5) non-halogen phosphorus flame retardants and (6) inorganic particles such as aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, antimony trioxide or silica, The mixing ratio of the non-halogen multifunctional epoxy resin in the components of the adhesive composition is 10 to 40 weight of the liquid epoxy resin having an epoxy equivalent of 184 to 100 weight of the solid epoxy resin having an epoxy equivalent of 475 or 209, 33 to 42 parts by weight of the epoxy resin, 15 parts by weight of the non-halogen phosphorus flame retardant and 15 parts by weight of the inorganic particles, and 1 to 20 parts by weight of the curing agent relative to 100 parts by weight of the epoxy resin, and the weight of the nitrile butadiene rubber 30 An adhesive composition for halogen-free coverlay film comprising 0.1 to 5 parts by weight of a curing accelerator. The adhesive composition for halogen-free coverlay film of Claim 3 was apply | coated on the polyimide base film as an adhesive bond layer, The coverlay film provided with the adhesive composition for halogen-free coverlay film characterized by the above-mentioned.

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