JP3407335B2 - Adhesive composition for flexible printed circuit board, flexible printed circuit board using the same, tape with adhesive for TAB, and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive composition for a flexible printed circuit board (hereinafter abbreviated as "FPC board"), and more specifically, a semiconductor integrated circuit mounting called a TAB (tape automated bonding) method. The present invention relates to an adhesive composition that is preferably used for a tape (hereinafter abbreviated as "TAB tape").

[0002]

2. Description of the Related Art The basic structure of an FPC board is, as shown in FIG. 1, usually made of a heat-resistant organic insulating film 1 such as polyimide as a base material, on which a mixed system of polyamide and epoxy (“polyamide / epoxy system”) Abbreviation, same as below
□□ / △△△ system "means a mixed system of □□□ and △△△) consisting of a conductor 4 such as a copper foil adhered via a thermosetting adhesive 2 such as an adhesive. ing. These adhesives are required to have various properties such as adhesiveness, insulation and chemical resistance. Further, the TAB tape is basically the same as the FPC board, and the material configuration and various required characteristics are basically the same, but they are properly used depending on the severity of the required characteristics.

As an adhesive for FPC, nylon (polyamide) / epoxy (“Adhesion” Vol. 17, No7, pp31-38 (1
973), JP-A-53-38169, JP-B-3-83
No. 95) is known. It is well known that polyamide / epoxy type adhesives (including curing agents such as phenolic resin and dicyandiamide (DICY)) exhibit excellent performance as adhesives for TAB tapes (JP-A-53-134365). Gazette, Japanese Patent Publication Sho 58-3
No. 0755, Japanese Patent Publication No. 61-3101), and more recently, polyamide / epoxy / polyparavinylphenol (including imidazole-based curing agent) system (JP-A 2-1).
5664) and polyamide / epoxy / phenolic resin-based (including imidazole-based curing agent) (JP-A-2-
No. 143447, JP-A-3-217035)
Are also proposed. These adhesives, nylon (polyamide) excellent adhesion of the resin, toughness, epoxy chemical resistance to the base resin and the polyamide molecular chain active end groups (-NH _2, -COOH) by reaction with, inter The basic idea is to increase the crosslink density of the epoxy resin itself with an epoxy curing agent such as DICY or imidazole to form the crosslinked structure of Has become. It is well known that the phenolic hydroxyl group in the molecular structure of a phenol resin or polyparavinylphenol acts as a curing agent for an epoxy resin to form a cured product excellent in heat resistance and electric insulation. For FPC board or TAB test
In adhesives for use in plastics, it has the effect of further modifying the properties of polyamide / epoxy resin or polyamide / epoxy / phenolic resin or polyamide / phenolic resin system.

[0004]

The FPC board and the TAB tape are basically the same, and the various properties required for these adhesives are also the same, but the following demands for insulation are stricter. The TAB tape application will be described as an example.

As a method for producing the adhesive tape for TAB, the adhesive is formed into a film, and the adhesive formed into the film is previously slit into a predetermined width so as not to reach the planned sprocket holes. What is so-called transfer laminating method, which is temporarily attached to a flexible insulating film that has been slit to a predetermined width,
A manufacturing method in which an adhesive is directly coated on the flexible insulating film so as not to reach a portion of the flexible insulating film where the sprocket holes are to be opened has become the mainstream.

In recent years, due to the demand for small size, thinness, light weight and high performance in electronic equipment, the adhesive for TAB is required to have higher insulation reliability. Conventional adhesives for TAB are polyamide / epoxy type, polyamide /
Examples using an epoxy / phenolic system and a curing agent are known. However, the TCP using these conventional adhesives cannot achieve the original purpose. When the electrical characteristics were evaluated by an unsaturated pressure cooker bias test (temperature 130 ° C., humidity 85%, pressure 2 atm, applied voltage 100 V) as so-called insulation evaluation, the unsaturated pressure cooker bias test was started 10 ⁸ to 10 ⁹ The resistance value, which was about ohms,
The phenomenon that the current flows through the adhesive tape part with the passage of the test becomes remarkable, and the resistance value gradually decreases,
After 100 hours, a short circuit occurs between the conductors, resulting in a resistance value of 10 ³ or less. The time to short circuit by unsaturated pressure cooker bias test needs to be 100 hours or more to obtain high insulation reliability. If the reliability is insufficient, small, thin, lightweight, and high-density packages are required. Since the performance as an adhesive tape for TAB cannot be exhibited at all in the required semiconductor mounting, the advent of an adhesive for TAB having high insulation reliability is desired.

[0007]

Therefore, an object of the present invention is to have the adhesiveness, heat resistance, chemical resistance, etc. which have been conventionally required as an adhesive for TAB tape, and
The above-mentioned problem is to provide a TAB tape having high insulation reliability, that is, a long time until a short circuit occurs between conductors in an unsaturated pressure cooker bias test, that is, an adhesive composition for an FPC board.

[0008]

The object of the present invention is as follows.
A polyamide resin containing (a) a dicarboxylic acid having 36 carbon atoms as an essential component , (b) an epoxy resin, and (c) a phenol resin as essential components, and having a weight composition ratio of epoxy resin / phenol resin. , 0.1 to 0.95. An adhesive composition for a flexible printed circuit board is achieved.

That is, in the present invention, as a result of diligent investigations by the present inventors on such problems, conventional adhesives are generally blended with epoxy resin / phenol resin = 1.1 or more. On the other hand, it is based on the finding that increasing the blending ratio of the phenol resin extends the time until the short circuit between the conductors in the unsaturated pressure cooker bias test.

[0010] Polyamide resin component (a) of the adhesive, those obtained by thermal polymerization of a mixture of acids and diamines, dicarboxylic acid carbon number of 36 as the acid component of the starting material for polyamides resin ( Those containing so-called "dimer acid" (so-called "dimer acid-based polyamide") are preferable. Polyamide resin generally has a high water absorption rate and thus tends to have a low insulation resistance, but by using dimer acid, it is possible to reduce the water absorption rate and increase the electrical insulation.

The dimer acid type polyamide can be obtained by thermally polymerizing an equimolar mixture of dimer acid and diamine. As the dicarboxylic acid component, not only dimer acid but also other dicarboxylic acids such as azelaic acid and sebacic acid may be contained as a copolymerization component.
At this time, the dimer acid content is more preferably 70 mol% or more in the acid component. Among the dimer acid-based polyamides, those having a high degree of polymerization are preferable because they have a relatively low water absorption rate and are likely to have high electric insulation even in a high humidity atmosphere.

As the diamine component, hexamethylenediamine, ethylenediamine, piperazine, bis (4-aminocyclohexyl) methane, bis (4-amino, 1,1)
2-Methylcyclohexyl) methane and the like can be mentioned, and particularly preferable one is hexamethylenediamine. Dimer acid-based polyamides containing hexamethylenediamine as a main component are particularly preferable because they exhibit excellent properties in overall performance. Further, the diamine component may be used not only in one kind but also in a mixture of two or more kinds.

Examples of the epoxy resin which is the component (b) of the adhesive include glycidyl ether type epoxies such as bisphenol, phenol novolac and cresol novolac, and various known epoxy resins such as cycloaliphatic epoxy and glycidyl ester type epoxy. It can be used.

Examples of the phenolic resin as the component (c) of the adhesive include known phenolic resins such as novolac phenolic resins such as alkylphenolic resins and paraphenylphenolic resins, and resole phenolic resins. In particular, a thermosetting type that is solid at room temperature is preferable. Thermosetting type or thermoplastic type that is liquid at room temperature has low heat resistance, and when sealing with a molding material such as resin, the adhesive easily melts due to pressure and temperature, and the characteristics such as adhesive strength and insulation properties. Is likely to decrease. Thermosetting phenolic resin that is solid at room temperature is 20% by weight in the phenolic resin.
It is preferable that the above content is contained, and more preferably,
It is 40% by weight or more. The thermosetting phenolic resin which is solid at room temperature can be easily obtained as a commercially available product. Specifically, Gunei Chemical Co., Ltd. PS2780, Showa High Polymer Co., Ltd. CK
Examples include M1282, TD-2625 manufactured by Dainippon Ink and PR-175 manufactured by Sumitomo Dures.

Further, a thermosetting phenolic resin which is solid at room temperature is represented by the general formula (1)

[Chemical 2] (In the formula, R represents hydrogen or a hydrocarbon having 1 to 9 carbon atoms.) Those containing a structural unit represented by the formula are particularly preferable because the object of the present invention is further improved. Since the more the structural unit represented by the general formula (1) is, the better the heat pressing property is,
The content in the phenol resin is preferably 35% by weight or more, more preferably 50% by weight or more.
Further, as the carbon number of R increases, the compatibility with the polyamide resin and the epoxy resin increases, but if it increases too much, the heat pressing property decreases, so the carbon number is 4 (butyl group).
Is more preferred. In addition, a t-butyl group is particularly preferable because it is easily available. Specific examples thereof include PS2780 manufactured by Gunei Chemical Co., Ltd. and CKM1282 manufactured by Showa High Polymer Co., Ltd.

If desired, known epoxy resin curing agents such as imidazole, amines, acid anhydrides and Lewis acid catalysts may be used.

Regarding the respective component ratios, when the polyamide resin of the component (a) is 100 parts by weight, the epoxy resin of the component (b) is preferably 3 to 65 parts by weight, more preferably 10 to 65 parts by weight. 40 parts by weight. If the amount of epoxy resin is too small, the adhesive strength tends to be weak and difficult. Also,
If the amount of epoxy resin is too large, the insulating property will decrease. The amount of the phenol resin as the component (c) is preferably 10 to 100 parts by weight, more preferably 20 to 80 parts by weight.
When the amount of phenolic resin is small, the time to short circuit in the unsaturated pressure cooker bias test becomes short, which is not preferable. Further, if the amount of the phenol resin is too much, the adhesive force becomes difficult to be obtained. That is, when the polyamide resin is less than the phenol resin or the epoxy resin, sufficient adhesive force cannot be obtained.

The weight composition ratio of epoxy resin / phenolic resin must be 0.1 to 0.95.
It is more preferably 0.15 to 0.90, and even more preferably 0.25 to 0.80. When the weight composition ratio of the epoxy resin / phenolic resin is more than 0.95, the time to short circuit in the unsaturated pressure cooker bias test becomes extremely short, and when it is less than 0.1, the adhesive strength decreases, which is not preferable.

An adhesive composition solution is obtained by dissolving each of the above components in a solvent. As a solvent for dissolving each component of the adhesive, toluene, xylene, chlorobenzene,
Aromatic solvent such as benzyl alcohol and methanol,
A mixed solvent with an alcohol solvent such as ethanol, isopropyl alcohol, and butyl alcohol is suitable.
As shown in FIG. 1, the basic structure of the FPC board is such that a flexible insulating film 1 is used as a base material, and a conductor 4 is laminated on the flexible insulating film 1 via an adhesive 2. The conductor may be laminated on one side of the flexible insulating film (single-sided FPC) or may be laminated on both sides (double-sided FPC).

The flexible insulating film used for the FPC board is a so-called heat resistant film made of polyimide, polyetherimide, aromatic polyamide, polyethylene terephthalate or flexible epoxy /
A composite material such as glass cloth can be preferably used. Copper is generally used as the conductor.

The FPC board is usually manufactured by the following method.

The above adhesive composition solution is applied to a flexible insulating film and dried. At this time, the film thickness after drying is preferably applied so as to be about 10 to 35 μm for flexibility. The drying conditions are usually 100 to 200 ° C. and 1 to 5 minutes. Copper foil is attached to this, and the adhesive is cured by heating. Further, in the case of double-sided FPC, copper foil is attached to the other side by the same method.

After that, the FPC board is completed through the following steps.

(In the case of a double-sided FPC board, punching and drilling steps such as through-hole stacking pin holes) (In the case of a double-sided FPC board, electrolytic or electroless copper plating step for the through-hole, photoresist Coating or dry film sticking / pattern exposure / development process, copper foil pattern etching process, photoresist or dry film peeling process, (solder resist coating or coverlay film sticking process if necessary).

Next, the case where the adhesive of the present invention is used for TAB, which is one of FPC boards, that is, a tape with an adhesive for TAB will be described.

A schematic cross-sectional view of the adhesive tape for TAB is shown in FIG. A base material made of the flexible insulating film 1,
It is composed of a protective film 3 adhered thereto via an adhesive 2.

The protective film is formed as needed. The protective film is used for the purpose of preventing dust and handling, and polyethylene, polypropylene, polyethylene terephthalate, polyphenylene sulfide, etc. are preferably used.

The adhesive tape for TAB is usually produced by any of the following methods (1) and (2).

(1) A flexible insulating film is coated with the above adhesive composition solution and dried. At this time, it is preferable to apply so that the film thickness after drying is about 10 to 15 μm. The drying condition is usually 100 to 200.
C., in the range of 1 to 5 minutes. If necessary, a protective film having releasability is laminated on the film and slit to a desired width. Its width is usually about 35 to 158 mm.

(2) The adhesive composition solution is applied and dried on the releasable film to be a protective film in the same manner as in the above (1). If necessary, a second release film (protective film) is laminated on the adhesive layer, and the adhesive film is slit into a desired width in the same manner as in the above (1). The second release film is peeled off from this to a flexible insulating film such as polyimide which is slit in advance to a desired width, and the adhesive surface is attached.

The width of the flexible insulating film, which is the base material, is usually set wider than the width of the adhesive.

However, in the method (1), since the adhesive layer is formed also in the sprocket hole portion, the adhesive composition is limited because the adhesive sticks to the heating roll during the copper foil laminating step. . The adhesive composition of the present invention is also satisfactory in this respect.

Further, the thinner the adhesive layer, the smaller the absolute amount of impurities, and therefore the higher the insulation reliability, and the longer the time until a short circuit occurs in the unsaturated pressure cooker bias test. It is preferably 12 μm or less, and more preferably 12 μm or less.

The TAB tape for mounting the IC is the TAB above.
An IC is mounted on the TAB tape thus obtained, which is manufactured through the following steps using the adhesive tape. Punching process for sprocket holes, device holes, etc., protective film removal / copper foil laminating process, adhesive heat curing process, photoresist coating / pattern exposure / development process, copper foil pattern etching process, photoresist stripping process, (solder if necessary) Resist coating process), plating process (tin, solder, gold, etc.).

The adhesive composition for FPC board according to the present invention is used for FPC board, TAB tape, LOC,
It can be used for fixing lead frames and for coverlay applications.

[0036]

The present invention will be described in more detail with reference to the following examples.

Each test in this example was conducted as follows.

<Insulation measurement method> FPC board for performance examination: conductor width 200 μm pattern pitch 250 μm space conductor spacing 50 μm TAB tape at 130 ° C., 85%, 2 atm, 100 V
Measure the time until a short circuit occurs under application. The time to short circuit is preferably 100 hours or more, and particularly preferably 500 hours or more.

<Adhesive force measuring method> FPC board for performance examination: conductor width 200 μm Measuring machine: manufactured by Orientec Tensile tester A conductor is peeled in 90 ° direction at a speed of 50 mm / min, and the stress at that time is measured. Generally, 1.0k
g / cm or more is required.

Example 1 A polyimide film having a thickness of 75 μm (“UPILEX” 75S manufactured by Ube Industries, Ltd.) was coated with the following composition at a solid content concentration of 20.
After being dissolved in a mixed solution of methanol / monochlorobenzene so as to have a weight%, the obtained adhesive solution is applied so as to have a dry film thickness of 12 μm.
It was dried at 00 ° C for 1 minute and at 150 ° C for 2 minutes.

<Adhesive Composition> 100 parts by weight of polyamide resin (Nylon 6.36 “PRIADIT” 2053 manufactured by Unichema, dimer acid and hexamethylenediamine as main components, weight average molecular weight of 100,000, MI value at 175 ° C. of 10 gr / Min) Bisphenol A type epoxy resin 20 parts by weight (Ep828 manufactured by Yuka Shell Co., Ltd.) 80 parts by weight thermosetting alkylphenol resin (PS2780 manufactured by Gunei Chemical Co., Ltd.) The polyimide film with an adhesive obtained above has a thickness of 3
A 5 μm electrolytic copper foil was laminated by a roll laminating method. Then, in the air oven, 80 ℃ × 3 hours, 1
The adhesive was cured by heat treatment under the conditions of 00 ° C x 5 hours and 150 ° C x 5 hours.

Using the obtained tape for TAB adhesive, a comb pattern was formed on a copper foil surface by a conventional method through photoresist coating, pattern exposure, development, copper foil pattern etching, and photoresist stripping steps. Further, an immersion tin plating solution was used to perform plating with a thickness of 0.5 μm to prepare an FPC board for performance study.

Example 2 An FPC board for performance study was prepared in the same manner as in Example 1 except that the adhesive components were as follows.

<Adhesive composition> 100 parts by weight of polyamide resin (Nylon 6.36 "PRIADIT" 2053 manufactured by Unichema) 40 parts by weight of bisphenol A type epoxy resin (Ep828 manufactured by Yuka Shell Co., Ltd.) 60 parts by weight of thermosetting alkylphenol resin (Showa High Polymer Co., Ltd. CKM1282) Comparative Example 1 An FPC board for performance examination having exactly the same contents as in Example 1 was prepared except that the adhesive composition used was one having the following composition.

<Adhesive composition> Polyamide resin 100 parts by weight (Unichema nylon 6.36 "PRIADIT" 2053) Bisphenol A type epoxy resin 80 parts by weight (Oka Shell Ep828 Ep828) thermosetting alkylphenol resin 10 parts by weight (PS2780 manufactured by Gunei Chemical Co., Ltd.) Comparative Example 2 An FPC board for performance examination having exactly the same contents as in Example 1 was prepared except that the adhesive components having the following compositions were used.

[0046] <Adhesive composition>   Polyamide resin 100 parts by weight     (Unichema nylon 6.36 "PRIADIT" 2053)   Bisphenol A type epoxy resin 60 parts by weight     (Yukaka Shell Co. Ep828)   Thermosetting alkylphenol resin 40 parts by weight     (Showa High Polymer Co., Ltd. CKM1282)   2-ethylimidazole 1 part by weight

[Table 1]

[0047]

The FPC board and TAB tape made from the adhesive composition for an FPC board according to the present invention have the same adhesiveness, insulation and chemical resistance as conventional ones, and have an unsaturated pressure cooker bias. It takes a long time to short-circuit between conductors in the test. Further, in the process of producing the TAB tape, the flexible insulating film can be produced without any problem even if the adhesive layer is provided on the entire surface.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an FPC board.

FIG. 2 is a schematic sectional view of a TAB tape.

[Explanation of symbols]

1: Flexible insulating film 2: Adhesive 3: Protective film 4: conductor

Claims (8)

(57) [Claims] 1. A polyamide resin containing (a) a dicarboxylic acid having 36 carbon atoms as an essential component, (b) an epoxy resin, and (c) a phenol resin as an essential component, and an epoxy resin / phenol resin weight composition ratio. But 0.1
The adhesive composition for flexible printed boards is characterized in that 2. An epoxy resin (b) is blended in an amount of 3 to 65 parts by weight and a phenolic resin (c) is in an amount of 10 to 100 parts by weight, based on 100 parts by weight of a polyamide resin. Item 2. An adhesive composition for a flexible printed board according to Item 1. 3. The adhesive composition for a flexible printed board according to claim 1, wherein the phenol resin contains a thermosetting phenol resin which is solid at room temperature as an essential component. 4. A thermosetting phenolic resin which is solid at room temperature,
General formula (1) (In formula, R represents hydrogen or a C1-C9 hydrocarbon.) The structural unit represented by these is contained, The adhesive composition for flexible printed boards of Claim 3 characterized by the above-mentioned. 5. A flexible insulating film on at least one side,
A flexible printed board in which a conductor is laminated via an adhesive layer, wherein the adhesive layer is the adhesive composition for a flexible printed board according to any one of claims 1 to 4. 6. A tape with an adhesive for TAB, which comprises at least a flexible insulating film and an adhesive layer on the flexible insulating film, wherein the adhesive layer is any one of claims 1 to 4. A tape with an adhesive for TAB , which is the adhesive composition for a flexible printed circuit as described above. 7. The adhesive tape for TAB according to claim 6, wherein the thickness of the adhesive layer is 15 μm or less. 8. The method according to any one of claims 1 to 4 on the flexible insulating film.
An adhesive dier layer is directly formed by coating the adhesive composition for a flexible printed circuit according to any one of 1 to 3, and a protective film is laminated on the adhesive layer, and then slit to a desired width. A method for producing a tape with an adhesive for TAB.