JPH1017749A - Adhesive film for electronic part and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject film excellent in initial sticking property and an adhesion characteristics against an electronic base material and also excellent in flexibility, heat creep resistance, and adhesion processing efficiency by forming an ethylene copolymer composition as a film form. SOLUTION: This adhesive film for electronic parts is obtained by blending (A) 100-10 pt.wt. graft-modified ethylene copolymer modified by 0.05-5wt.% unsaturated carboxylic acid, (B) 0-90 pt.wt. ethylene/unsaturated ester copolymer and (C) (i) 0.05-10 pt.wt. organic peroxide having 40-180 deg.C temperature of showing a half life of 10hr, or (ii) 0.5-10 pt.wt. thermally reactive polyisocyanate based on 100 pts.wt. above polymer components to obtain an ethylene copolymer composition having 20-60wt.% averaged unsaturated ester content in the mixture of the component A with B and 5-200g/10min mean melt flow rate, and forming the ethylene copolymer composition as a film form under a condition not generating a crosslinking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive film for electronic parts which is excellent in initial tackiness, workability, heat-resistant adhesiveness, electrical insulation and flexibility.

[0002]

2. Description of the Related Art As electronic devices have become smaller, thinner and lighter, high performance adhesives have been required. In the bonding of such electronic devices, it is often performed to bond a metal such as polyimide, glass epoxy, paper phenol, or polyethylene terephthalate, which is generally used as an electronic substrate, to a metal. At the same time, emphasis is placed on workability in the bonding process. For example, in a rotary transformer used in a cylinder unit for a video cassette recorder, a ferrite core and a flexible printed board are bonded to each other. Conventionally, an epoxy-based adhesive has been used as an adhesive. However, when an epoxy-based adhesive is used, there is a drawback that manual cleaning is required as a post-processing because the adhesive oozes out of the bonding surface due to dripping of the adhesive.

[0003] For this reason, attempts have been made to bond the two with an adhesive film that does not require such post-treatment. However, in general, the adhesive strength is weak and the durability is uneasy. There were concerns. Therefore, studies have been made to use a heat-adhesive film that has a high adhesive strength and does not cause contamination.However, in many cases, the initial adhesiveness required to bond the ferrite core and the flexible printed board at a desired position is considered. Insufficient heat resistance or heat-reactive properties require a long time to achieve strong adhesion, or the heat-resistant creep resistance of the bonded surface does not shift when heated after bonding At the moment, no satisfactory products have been found.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present inventors
A study was made to find a film-like adhesive which does not have the above-mentioned disadvantages as an adhesive for electronic devices. As a result, they have found that the specific composition described below has various properties satisfying the above requirements and is suitable as an adhesive for electronic devices, and has reached the present invention. Accordingly, an object of the present invention is to provide an adhesive film for electronic parts which has excellent initial tackiness and adhesiveness, and also has excellent flexibility, heat creep resistance and adhesive workability with respect to electronic substrate materials such as metals and polyimides. Is what you do.

[0005]

According to the present invention, an unsaturated carboxylic acid or an anhydride thereof is added to an ethylene / unsaturated ester copolymer having an unsaturated ester content of 15 to 60% by weight in an amount of 0.05 to 5% by weight. % Of a graft-modified ethylene copolymer (A) having a melt flow rate of 0.5 to 200 g / 10 min, 100 to 10 parts by weight, an unsaturated ester content of 15 to 60% by weight, and a melt flow rate of 0.5 to 200 g / 10 min. 0 to 90 parts by weight of the ethylene / unsaturated ester copolymer (B) of 0.5 to 200 g / 10 min and 100 parts by weight of these polymer components have a 10-hour half-life temperature of 40 to 18
0.05 to 10 parts by weight of the organic peroxide (C-1) at 0 ° C or 0.5 to 0.5 parts by weight of the heat-reactive polyisocyanate (C-2).
An ethylene copolymer composition comprising (A) and (B) having an average unsaturated ester content of 20 to 60% by weight and an average melt flow rate of 5 to 200 g / 10 min. Provided is an adhesive film for an electronic component, which is obtained by molding a product into a film under conditions that do not substantially cause crosslinking.

In the present invention, a method for producing an adhesive film for electronic parts, comprising dissolving each component forming the ethylene copolymer composition in a solvent, forming a film on release paper, and drying. Is provided.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As the unsaturated ester in the ethylene / unsaturated ester copolymer serving as the base polymer of the graft-modified ethylene copolymer (A) used in the present invention, vinyl esters such as vinyl acetate and vinyl propionate are used. Unsaturated carboxylic esters such as esters, methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, isooctyl acrylate, methyl methacrylate, isobutyl methacrylate, and diethyl maleate. In such an ethylene / unsaturated ester copolymer, a third component other than ethylene and the unsaturated ester, for example, a material such as carbon monoxide may be copolymerized.

The unsaturated ester content of the base polymer is 15 to 60% by weight, preferably 25 to 60% by weight, more preferably 35 to 50% by weight. If the unsaturated ester content is less than the above range, it will be difficult to obtain an adhesive film having excellent initial tackiness, and it will be difficult to dissolve it in a solvent in a film production method described later. When the unsaturated ester content is more than the above range,
A cohesive force is insufficient and a film with sufficient strength cannot be obtained.

The amount of grafting of the unsaturated carboxylic acid or its anhydride in the graft-modified ethylene copolymer (A) is 0.05 to 5% by weight, preferably 0.1 to 3 parts by weight. If the amount of the unsaturated carboxylic acid or its anhydride grafted is less than the above range, it does not show sufficient adhesive strength to metals and electronic substrate materials. As the unsaturated carboxylic acid or its anhydride as a graft component,
Acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, maleic anhydride, itaconic anhydride, norbornene-2,3-dicarboxylic anhydride and the like can be exemplified. Of these, the use of acid anhydrides, especially maleic anhydride, is most preferred.

The graft-modified ethylene copolymer (A) has a melt flow rate of 0.5 to 200 g / 10
Min, preferably 5 to 100 g / 10 min. When the melt flow rate is smaller than the above range, it takes time to dissolve in a solvent in the film manufacturing method described later, or the viscosity of the dissolved liquid increases,
There are problems such as difficulty in forming a thin film. Further, if the thickness is larger than the above range, the cohesive strength becomes insufficient and a film having sufficient strength cannot be obtained.

The ethylene / unsaturated ester copolymer (B) blended as an optional component in the graft-modified ethylene copolymer (A) includes the same copolymer as that used as the base polymer of (A). Can be used.

Ethylene / unsaturated ester copolymer (B)
Also, for the same reason that the melt flow rate of the graft-modified ethylene copolymer (A) is specified, the melt flow rate is 0.5 to 200 g / 10 minutes,
Preferably, one having 5 to 100 g / 10 minutes is used.

A graft-modified ethylene copolymer (A),
The proportion of the ethylene / unsaturated ester copolymer (B) used is such that (A) / (B) is 100 to 10/0 to 9 by weight.
0, preferably 90-20 / 10-80. That is, although it is not necessary to use the component (B) in particular, the use of the component (B) makes it easier to control initial tackiness and solvent solubility, and can reduce the cost of raw materials.

The proportion of (A) and (B) used is such that the average unsaturated ester content in the mixture of the two is from 20 to 60% by weight, preferably from 30 to 60% by weight, particularly preferably from 35 to 60% by weight.
５０50% by weight. If the average unsaturated ester content is less than the above range, sufficient initial tackiness cannot be obtained and the solubility in a solvent decreases, which is not preferable. If the content is more than the above range, a film having sufficient strength cannot be obtained due to insufficient cohesive strength, or the workability is deteriorated due to excessively high tackiness.

Further, the average melt flow rate of the mixture is 5
(A) and (B) are blended so as to be in a range of from 200 g / 10 min, preferably from 7 to 150 g / 10 min. If the average melt flow rate is smaller than the above range, only a composition having a poor initial adhesive strength can be obtained, and if the average melt flow rate is larger than the above range, a cohesive force is insufficient and a film having sufficient strength cannot be obtained.

In the present invention, an organic peroxide (C) is added to 100 parts by weight of a polymer component comprising (A) and (B).
-1) 0.05 to 10 parts by weight, preferably 1 to 5 parts by weight, or a heat-reactive polyisocyanate (C-
2) is added in a ratio of 0.5 to 10 parts by weight, preferably 0.8 to 8 parts by weight.

The organic peroxide (C-1) has a 10-hour half-life temperature of 40 to 180 ° C., preferably 50 to 17 ° C.
The one at 0 ° C is used. If a material having a half-life temperature higher than the above range is used, it is not efficient because a high temperature and a long time are required to form an adhesive layer having a large adhesive strength. This is not preferred because it may cause If the half-life temperature is lower than the above range, the storage stability of the composition is poor, and the workability of film forming and the quality of the film are adversely affected, which is not preferable.

Those suitable as organic peroxides are soluble in organic solvents, and specifically, 3,5,5-
Trimethylhexanoyl peroxide, lauroyl peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, t-butyl-α-cumyl peroxide, 1,4-
Or 1,3-bis [(t-butyldioxy) isopropyl] benzene, 2,5-dimethyl-2,5-bis (t-
Butylperoxy) -3-hexyne, 2,5-dimethyl-2,5-bis (t-butylperoxy) -3-hexane, 1,1-bis (t-butylperoxy) -3,3
5-trimethylcyclohexane, n-butyl-4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane, t-butylperoxyisobutyrate, t-butylperoxypivalate,
T-butyl peroxyoctoate and the like can be exemplified.

When an organic peroxide is used, the amount is preferably 0.1 to 100 parts by weight of the polymer component comprising (A) and (B).
It is used in an amount of 5 to 10 parts by weight, preferably 1 to 5 parts by weight. If the compounding ratio of the organic peroxide is too small, it is difficult to form an adhesive layer showing sufficient performance by heating for a short time, and if the compounding amount is too large, a large amount of decomposition by-products is generated, Bubbles are generated in the film, or a large amount of undecomposed peroxide remains, adversely affecting members.

In the present invention, a heat-reactive polyisocyanate (C-2) can be used in place of the organic peroxide. The heat-reactive polyisocyanate has two or more isocyanate groups, and may be a polyisocyanate in which the isocyanate groups are masked and inactivated. Examples of such polyisocyanates include diphenylmethane diisocyanate, hexamethylene diisocyanate, methylene bis (4-phenyl isocyanate), a reaction product of hexanetriol and 2,4-tolylene diisocyanate, and a urethane polymer having a terminal isocyanate group. can do. Examples of the isocyanate group masking agent include phenol, alcohol, active methylene compound, oxime, mercaptan, imine, lactam, amide, imide, and bisulfite. Of these, those which are soluble in organic solvents and have an activation temperature of 100
Those having a temperature of about 200 ° C to about 200 ° C are preferred.

The amount of the heat-reactive polyisocyanate used is
It is 0.5 to 10 parts by weight, preferably 0.8 to 8 parts by weight, based on 100 parts by weight of the polymer component composed of (A) and (B). If the amount is small, it is difficult to form an adhesive layer exhibiting sufficient adhesive performance by heating for a short time. On the other hand, if the amount is too large, a large amount of reaction by-products are generated or unreacted polyisocyanate remains, adversely affecting members.

(A), (B) and (C-1) or (C-
In order to obtain a film-like adhesive from the ethylene copolymer composition of 2), these components are dissolved in an appropriate solvent, and the resulting solution is cast on release paper to form a film. ,
It is good to dry.

Solvents usable for such purposes include aromatic solvents such as benzene, toluene and xylene, furans represented by tetrahydrofuran, ketones represented by methyl ethyl ketone, and esters represented by ethyl acetate. And, furthermore, trichlene, mineral spirits and the like. It is desirable to adjust the concentration of the components (A) and (B) in the solution to about 5 to 30% by weight in consideration of workability of film forming and uniformity of the film. In forming the film, the solution may be heated if necessary.

After the film is formed and dried, the film is rolled up and stored together with the release paper, and the release paper can be peeled off before use. Of course, the film may be peeled off from the release paper immediately after drying.

The thickness of the adhesive film for electronic parts is preferably about 1 to 500 μm.

The film thus obtained can be used as an adhesive for electronic parts. Since such a film has surface tackiness, it is easy to temporarily fix an adherend, and it is possible to adhere at an accurate position. At the time of bonding, the mixture is heated to a temperature equal to or higher than the decomposition temperature of the organic peroxide (C-1) or equal to or higher than the activation temperature of the heat-reactive polyisocyanate (C-2) in the ethylene copolymer composition of the present invention, and then pressed. Thereby, the adherends can be bonded to each other. At this time, by crosslinking or reacting (A) and / or (B), an adhesive layer having rubber elasticity and heat resistance can be formed and can be firmly adhered to an adherend.

Typical examples of the bonding of electronic parts are polyimide,
Bonding of a substrate material such as polyester, glass epoxy, paper phenol and a metal, for example, a conductive material such as copper or a magnetic material such as ferrite. More specifically, it can be used for bonding a ferrite core of a rotary transformer and a flexible printed board as described above, or bonding a board material and a copper foil on a flexible printed board.

[0028]

According to the present invention, flexibility, initial tackiness,
It is possible to provide a film adhesive for electronic parts having excellent adhesive strength, heat creep resistance, adhesive workability, and insulating properties. If such an adhesive is used, there is no problem of dripping as in the case of using a one-part or two-part adhesive,
The bonding operation can be easily performed without any trouble. Further, since the reliability of the adhesive layer is high, the frequency of occurrence of defective products can be reduced.

[0029]

EXAMPLES The present invention will be specifically described below with reference to examples. In addition, the types of adhesive resin raw material resin, organic peroxide, and thermoreactive polyisocyanate used in Examples and Comparative Examples, and methods for measuring physical properties of the adhesive film are as follows.

(1) Raw material resin As the graft-modified ethylene copolymer (component A), the following two types of maleic anhydride-modified ethylene / vinyl acetate copolymer are used, and an ethylene / unsaturated ester copolymer (component B) The following three types of ethylene / vinyl acetate copolymers were used.

[0031]

[Table 1]

(2) Organic peroxide (C-1) and heat-reactive polyisocyanate (C-2)

[Table 2]

(3) Physical property measurement method (1) Initial tackiness A 100 μm thick adhesive film is formed on a ferrite plate at room temperature by a solution casting method. A polyimide film having a thickness of 50 μm is placed thereon, and is lightly pressed with a finger and bonded. After bonding, the adhesive strength is evaluated with a finger.

(2) Main adhesive strength The sample bonded in the test of the above (1) was heated at a temperature of 140 ° C.
The bonding is performed under the bonding conditions of a pressure of 9 kg / cm ² and a time of 1 minute. After bonding, the sample is cooled to room temperature, and the 90 ° peel strength is measured under the following conditions. Peeling speed: 100 mm / min Atmospheric temperature: 23 ° C. Width: 6 mm

(3) Heat Resistance Adhesion A 100 g load is applied to the other end of the polyimide film which has been heated and bonded to the end of the ferrite plate with a bonding area of 4 mm × 6 mm in parallel with the bonding surface as shown in FIG. In this state, the sample is allowed to stand in a 60 ° C. constant temperature bath for 10 minutes, and the deviation of the polyimide film before and after standing is measured.

(4) Solubility in Organic Solvent To 20 g of the resin composition mixed for preparing an adhesive film, 80 g of toluene was added, and the dissolved state at room temperature was visually evaluated.

[Example 1] Graft-modified ethylene / unsaturated ester copolymer (A-), ethylene / unsaturated ester copolymer (B-) and organic peroxide (C _1- )
Were mixed at the compounding ratio shown in Table 3, and 80 g of toluene was added to 20 g of the obtained resin composition. The mixture was dissolved at room temperature, and the solubility in toluene was evaluated. Subsequently, the resin composition solution was cast and dried on a ferrite plate to form a 100 μm thick adhesive film, and the initial adhesiveness with the polyimide film, the final adhesive strength, and the heat resistance were determined by the methods (1) to (3). The adhesion was measured. Table 3 shows the results.

[Example 2]
Instead of the unsaturated ester copolymer (B-), (B-
The adhesive film was prepared in the same manner as in Example 1 except that the above was used, and the solubility of the resin composition and the adhesive property of the adhesive film were measured. Table 3 shows the results.

Example 3 In Example 1, the compounding ratio (parts by weight) of the resin composition was (A −) / (B −) = 70 /
An adhesive film was prepared in the same manner as in Example 1 except that the value was 30. The solubility of the resin composition and the adhesiveness of the adhesive film were measured. Table 3 shows the results.

Example 4 An adhesive film was prepared in the same manner as in Example 1 except that the mixing ratio of the resin composition was changed to (A −) / (B −) = 30/70.
The solubility of the resin composition and the adhesiveness of the adhesive film were measured. Table 3 shows the results.

Example 5 An adhesive film was prepared in the same manner as in Example 1 except that 3 parts by weight of a thermoreactive polyisocyanate (diphenylmethane diisocyanate) was added instead of the organic peroxide. The solubility of the resin composition and the adhesiveness of the adhesive film were measured. Table 3 shows the results.

Comparative Example 1 A film was prepared in the same manner as in Example 1 except that the A-component and the C ₁ -component were not used and only the ethylene / vinyl acetate copolymer (B-) was used. The solubility of the resin and the adhesiveness of the adhesive film were measured. Table 4 shows the results.

[Comparative Example 2] Table 4 shows only the ethylene / vinyl acetate copolymer (B-) and the organic peroxide (C _1- ) without blending the graft-modified ethylene / vinyl acetate copolymer (A). And mixed in the same manner as in Example 1,
A film was prepared, and the solubility of the resin and the adhesiveness of the adhesive film were measured. Table 4 shows the results.

Comparative Example 3 An adhesive film was prepared and the solubility of the resin composition and the adhesiveness of the adhesive film were measured in the same manner as in Example 1 except that the organic peroxide was not used. . Table 4 shows the results.

[Comparative Example 4]
Instead of the unsaturated ester copolymer (B-), (B-
) Was used in the same manner as in Example 1 except that (A-) was used in place of the graft-modified ethylene / unsaturated ester copolymer (A-) to prepare an adhesive film, and to improve the solubility of the resin composition and The adhesiveness of the adhesive film was measured. Table 4 shows the results.

Comparative Example 5 An adhesive film was prepared in the same manner as in Example 1 except that the mixing ratio of the resin composition was changed to B− / A− = 90/10. The solubility and the adhesiveness of the adhesive film were measured. Table 4 shows the results. The adhesive films of Comparative Examples 4 and 5 are inferior in initial tackiness, solvent solubility, etc., because the average vinyl acetate content of the polymer composition is low.

[0047]

[Table 3]

[0048]

[Table 4]

[Brief description of the drawings]

FIG. 1 is an apparatus for measuring the heat resistance of an adhesive film.

[Explanation of symbols]

 Reference Signs List 1 ferrite plate 2 polyimide film 3 adhesive film 4 load (100 g)

Claims (2)

[Claims] An unsaturated ester content of 15 to 60% by weight.
The ethylene / unsaturated ester copolymer is graft-modified with an unsaturated carboxylic acid or an anhydride thereof at a ratio of 0.05 to 5% by weight to have a melt flow rate of 0.5 to 200 g / 1.
0 minute graft-modified ethylene copolymer (A) 100-1
0 parts by weight, 0 to 90 parts by weight of an ethylene / unsaturated ester copolymer (B) having an unsaturated ester content of 15 to 60% by weight and a melt flow rate of 0.5 to 200 g / 10 minutes, and these polymer components The organic peroxide (C-1) having a 10-hour half-life temperature of 40 to 180 ° C. is 0.05 to 10 parts by weight or the heat-reactive polyisocyanate (C-2) is 0.5 to 100 parts by weight. 10 parts by weight, the average unsaturated ester content in the mixture of (A) and (B) is 20 to 60% by weight, and the average melt flow rate is 5-2.
An adhesive film for electronic parts, wherein an ethylene copolymer composition of 00 g / 10 min is formed into a film under conditions that do not substantially cause crosslinking. 2. An unsaturated ester content of 15 to 60% by weight.
The ethylene / unsaturated ester copolymer is graft-modified with an unsaturated carboxylic acid or an anhydride thereof at a ratio of 0.05 to 5% by weight to have a melt flow rate of 0.5 to 200 g / 1.
0 minute graft-modified ethylene copolymer (A) 100-1
(A) 0 to 90 parts by weight of an ethylene / unsaturated ester copolymer (B) having an unsaturated ester content of 15 to 60% by weight and a melt flow rate of 0.5 to 200 g / 10 min. , (B) the average unsaturated ester content in the mixture is 20 to 60% by weight, and the average melt flow rate is 5 to 5%.
0.05 to 10 parts by weight of an organic peroxide (C-1) having a 10-hour half-life temperature of 40 to 180 ° C. per 100 parts by weight of a polymer component of 200 g / 10 minutes, or a heat-reactive polyisocyanate A method for producing an adhesive film for electronic parts, comprising adding 0.5 to 10 parts by weight of (C-2), dissolving in a solvent, forming a film on release paper, and drying.