JPH064837B2 - Flame-retardant adhesive composition and flame-retardant flexible printed wiring board - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an adhesive composition having excellent heat resistance and flame retardancy, and a flexible printed wiring board using the adhesive composition.

(Prior Art) In recent years, the development of the electronics field has been remarkable, and electronic devices such as communication consumer products are becoming smaller, lighter, and higher in density, and requirements for these performances are becoming more and more advanced. There is.

In response to such demands, the flexible printed wiring board has flexibility, so that it can be mounted in a narrow space with a three-dimensional high density, and can withstand repeated bending, and wiring to electronic equipment,
Its applications are expanding as composite parts with cable and connector functions.

A substrate for flexible printed wiring generally uses a film of polyimide or polyester resin as an electrically insulating base material, and these base material film and a metal foil such as a copper foil or an aluminum foil are laminated and integrated via an adhesive. Based on this, a circuit is formed on it and mounted on many devices such as cameras, calculators, and computers. This flexible printed wiring board is required to have good properties such as heat resistance, chemical resistance, flexibility, and electrical insulation as well as adhesiveness between the metal foil and the film. Further, in recent years, there has been an increasing demand for safety in consumer devices, and accordingly, in addition to the above-described characteristics, particularly flame retardancy is also required for flexible printed wiring boards.

Conventionally, as an adhesive that should have these requirements, NBR
System, butyral resin, nylon / epoxy resin, N
BR / phenolic resin, carboxyl group-containing NBR /
Various adhesives using epoxy resins have been proposed, but none have been satisfied yet.

(Problems to be Solved by the Invention) The present invention has been made in order to satisfy the above various characteristics, and particularly an adhesive composition having excellent heat resistance and flame retardancy, and a flexible printed wiring using the adhesive composition. It is intended to provide a substrate.

(Means for Solving the Problems) The inventors of the present invention first conducted a diligent study on the adhesive composition in order to satisfy the above-mentioned characteristics, and as a result, have heat resistance and flame retardancy, and are suitable for a substrate for flexible printed wiring. The adhesive composition having flexibility, chemical resistance, electric insulation and adhesive strength was completed, and then the kind of electric insulation film (hereinafter abbreviated as insulation film) and the film surface treatment method were examined. As a result, a flexible printed wiring board obtained by laminating and integrating a low-temperature plasma-treated insulating film with a metal foil via this adhesive satisfies the above-mentioned various characteristics and is particularly excellent in heat resistance and flame retardancy. It was found that the present invention has been completed.

The main points are: 1. a) 100 parts by weight of polyester resin b) 20-80 parts by weight of non-halogen-containing epoxy resin having 2 or more epoxy groups in the molecule c) 2 epoxy groups in the molecule Halogen-containing epoxy resin having 20 to 80 parts by weight d) Halogen-containing epoxy resin having 3 or more epoxy groups in the molecule 30 to 100 parts by weight e) Organic acid anhydride 2 to 40 parts by weight he) Hemidazole compound 0.5 to A flame-retardant adhesive composition comprising 10 parts by weight and 4) 20 parts by weight of a flame retardant aid, and a halogen content in the resin component consisting of components a) to f) being 10% by weight or more, and 2. A flame-retardant flexible printed wiring board obtained by laminating and integrating a metal foil on a plastic film that has been subjected to low-temperature plasma treatment via the flame-retardant adhesive composition according to claim 1.

The present invention will be described in detail below.

First, the flame-retardant adhesive composition of the first invention will be described. Examples of the polyester resin as the component (a) include those synthesized from the following polyols and acid components. Examples of polyols include ethylene glycol, diethylene glycol, triethylene glycol, propylene grill coal, neopentyl glycol, trimethylolpropane, trimethylolpropane ethylene oxide adducts, etc., and acid components include terephthalic acid, isophthalic acid, adipic acid, trimellitate. Acids, pyromellitic acid and their acid anhydrides. A polyester resin particularly suitable for the present invention has a molecular weight of 10,000 to 30,000 and has a terminal -O.
An H group or -COOH group is preferable, and known commercially available products include Byron 30P, 103, 200, 300, 500 (a polyester resin trade name manufactured by Toyobo Co., Ltd.) and the like. The component (b) epoxy resin may be any non-halogen-containing epoxy resin having two or more epoxy groups in the molecule, and examples thereof include bisphenol A type, ether type, ether ester type, novolac type and glycidyl amine type. The commercially available product is Epicort 82.
8,871,517,154, 604 (trade name of Yuka Shell Epoxy Co., Ltd.)
Sumipoxy ELA115, 127; ESCN195XL, ELM120 (trade name of Sumitomo Chemical Co., Ltd.) and the like are exemplified, and these are used alone or in combination of two or more kinds.

Further, as the halogen-containing epoxy resin of the components (c) and (d), which is the most characteristic feature of the present invention, an epoxy group of 2 is included in the molecule.
It is indispensable to use two or more of the one having two (c) and the one having three or more (d), and bisphenol A type etc. have two epoxy groups in the molecule of the component (c). Yes, as commercial products Epicoat 5046, 5048, 5050
(Trade name of Yuka Shell Epoxy Co., Ltd.), ESB400,500 (trade name of Sumitomo Chemical Co., Ltd.) and the like. D) 3 in the molecule of component
There are novolac type and the like as having one or more epoxy groups, and examples of the commercially available product include BREN-S (trade name manufactured by Nippon Kayaku Co., Ltd.). Examples of these halogen-containing epoxy resins include chlorine-based and bromine-based epoxy resins, and it is particularly preferable to use bromine-based epoxy resins. The above b) c) and d)
The total amount of the component (4) is preferably 40 to 70% by weight in the resin components (1) to (6). In addition, it is preferable that 20) to 70% by weight of the total amount of epoxy resin of (b) c) and d) of d) having three or more epoxy groups. If many of them have two epoxy groups in the molecule (ro + ha), heat resistance cannot be satisfied, and if many of them have 3 or more epoxy groups in the molecule (d), adhesiveness, The flexibility cannot be satisfied. In the present invention, two types of epoxy resin containing halogen (C + D)
And a halogen-free epoxy resin (b) are used in combination, but if halogen-containing epoxy resin is added in order to impart flame retardancy, various properties such as adhesiveness and heat resistance can be satisfied. If it is not possible, the flame retardancy cannot be satisfied if the amount is reduced. The organic acid anhydride of the component (e) is a curing agent for the resin component used in combination with the component (e) (imidazole compound), and monofunctional type and polyfunctional type are used. The former includes methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, etc. and the reaction of C ₅ and C ₁₀ gen with maleic anhydride, and the latter is anhydrous. Trimellitic acid,
Examples include pyromellitic dianhydride, benzophenone tetracarboxylic acid and the like. Among these, monofunctional acid anhydrides obtained by the reaction of C-diene and maleic anhydride are particularly preferable,
Hygroscopic pot life and cured products have excellent moisture resistance, heat resistance, and electrical characteristics. (F) The imidazole compound as the component has the general formula (Wherein R ¹ and R ² represent a hydrogen atom or an alkyl group, and R ³ represents a hydrogen atom or an alkyl derivative), 2-methylimidazole, 2-ethylimidazole, 2-ethyl- 4-methylimidazole,
2-heptadecyl imidazole and its derivative are illustrated. Flame retardant aid, Sb ₂ O ₃ , Al (OH) ₃ , Al ₂ O ₃ , SiO ₂
Among them, Sb ₂ O ₃ is particularly preferable from the viewpoint of improving flame retardancy, and it is also possible to use this Sb ₂ O ₃ in combination with the other flame retardant aid.

Further, it is optional to add other resins and additives such as NBR, acrylic resins, phenol resins, aromatic diamines, etc. within a range that does not deteriorate various properties.

The distribution ratio of each component of the adhesive composition used in the present invention is as shown below. 2 in the molecule for 100 parts of polyester resin (a) (hereinafter, all parts and percentages are by weight)
The non-halogen-containing epoxy resin (b) having at least one epoxy group is preferably blended in an amount of 20 to 80 parts. When the amount is too large, the flame retardancy decreases, and when the amount is too small, the heat resistance decreases. Halogen-containing epoxy resin having two epoxy groups in the molecule
It is preferable to add 20 to 80 parts of (C). If the amount is too large, the heat resistance and the adhesiveness will decrease, and if it is too small, the flame retardancy will decrease.
The halogen-containing epoxy resin (d) having 3 or more epoxy groups in the molecule is preferably blended in an amount of 30 to 100 parts. If the amount is too large, the adhesiveness decreases, and if it is too small, the flame retardancy decreases. The organic acid anhydride (e) is preferably blended in an amount of 2 to 40 parts, and if too much unreacted acid anhydride remains, heat resistance and adhesiveness are reduced, and if too little unreacted epoxy resin, etc. The remaining heat resistance and adhesiveness decrease. Imidazole compound
(F) is preferably 0.5 to 10 parts, if too much unreacted imidazole-based compound remains, heat resistance decreases, too little unreacted epoxy resin remains, heat resistance decreases To do. The flame retardant aid (g) is preferably blended in an amount of 4 to 20 parts. When it is too large, flexibility and adhesiveness are deteriorated, and when it is too small, flame retardancy is deteriorated. Further, in the present invention, the halogen content in the resin component consisting of a) to f) of the adhesive composition must be 10% or more, preferably 12% or more, and 10% or more.
If it is less than 100%, the flame retardancy decreases.

Next, the flame-retardant flexible printed wiring board according to the second invention will be described.

Examples of the insulating film used in the present invention include a polyimide film, a polyparabanic acid film, a polyester film, a polyethersulfone film, and a polyetheretherketone film, and a polyimide film is particularly preferable. As the metal foil, electrolytic copper foil, rolled copper foil and aluminum foil, dangsten foil, etc. are used.

In the present invention, the above-mentioned insulating film and metal foil are laminated and integrated using the heat-resistant and flame-retardant adhesive of the first invention. This insulating film is previously subjected to low-temperature plasma treatment with an inorganic gas. It is necessary to improve the adhesion between the film and the adhesive. As the method of this low temperature plasma processing, the insulating film is placed in a low temperature plasma processing apparatus capable of depressurizing, and the pressure in the apparatus is kept at 0.001 to 10 Torr, preferably 0.01 to 1 Torr as an atmosphere of inorganic gas. , Low-temperature plasma of inorganic gas is generated by applying a direct current or alternating current of about 0.1 to 10 KV between the electrodes and glow discharge, and the plastic film is continuously treated on the surface while sequentially moving the insulating film. Is generally 0.1 to 100 seconds. As the inorganic gas, an inert gas such as helium, neon, or argon, and oxygen, nitrogen, carbon monoxide, carbon dioxide, ammonia,
Air or the like is used, but these are not limited to one type, and two or more types may be mixed and used optionally.

Next, as a method for producing a flame-retardant flexible printed wiring board, an adhesive composition solvent solution in which a flame-retardant auxiliary agent is previously dispersed by a ball mill or the like is used, a reverse roll coater, a polyimide film or the like using a comma coater. Apply to a metal foil in a dry state to a thickness of 25 ± 15 μm,
Dry at 140 ° C for 2-20 minutes to evaporate the solvent and leave the adhesive semi-cured. Flexible by stacking metal foil (or polyimide film) such as copper foil and aluminum foil (or polyimide film) on the adhesive surface of this polyimide film (or metal foil) with adhesive, heating with a roll laminator, and performing after-curing if necessary. A printed wiring board can be obtained.The pressure bonding conditions are a temperature of 140 ± 40 ℃ and a linear pressure of 1-5.
A range of 0 kg / cm and speed of 0.5-10 m / min is good. After-cure is preferably carried out in two steps. In this case, the condition is
80 ± 20 ℃ x 0.5-5 hours as a step, 160 as a second step
It is good to do it within ± 40 ° C x 1 to 10 hours.

Next, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. All parts and percentages in the examples are by weight.

(Reference example: Low temperature plasma treatment of insulating film) A 25 cm square 25 μm thick Kapton film (DuPont polyimide film product name) was placed in a low temperature plasma treatment apparatus, oxygen was introduced at a vacuum degree of 0.2 torr, and 110 kHz, 1.5
Applying an AC voltage of kv to the electrodes to cause glow discharge.
A low temperature plasma treatment was performed for 20 seconds. The Kapton film was placed on the lower electrodes of the upper and lower counter electrodes, and the distance between the electrodes was 10 cm. This was a low temperature plasma A treatment. Similarly, low-temperature plasma treatment was performed using 0.2 torr pressure of argon and a mixed gas of argon and oxygen. These were designated as low temperature plasma B treatment and low temperature plasma C treatment, respectively.

(Example 1) Byron 295 (a polyester resin trade name manufactured by Toyobo Co., Ltd.)
500 parts of 20% solution dissolved in EK, 50% ME of Epicoat 828 (trade name, manufactured by Yuka Shell Epoxy Co., non-halogen containing epoxy resin having two bisphenol A type epoxy groups)
K solution 50 parts, BREN-S (Nippon Kayaku Co., Ltd. trade name, bromine-containing epoxy resin having 3 or more bromine novolac type epoxy groups, bromine content 34.5 to 36.5%) 50% MEK solution 120 parts,
80 parts of 50% acetone solution of Epicoat 5046 (trade name, manufactured by Yuka Shell Epoxy Co., brominated epoxy resin having two brominated bisphenol A type epoxy groups, bromine content 20-22%), pyromellitic dianhydride 10 Part, 2E4MZ-CN (Shikoku Fine Chemicals Co., Ltd. imidazole trade name) 3 parts, and antimony trioxide 10 parts were charged, and antimony trioxide was sufficiently dispersed by a ball mill or the like to prepare an adhesive solution. The bromine content in the resin component of this adhesive composition was 12.2%.

Then, a flexible printed wiring board was manufactured. That is,
This adhesive solution was applied to a Kapton film treated with low temperature plasma A (described above) so that the thickness after drying was about 20 μm, and dried at 80 ° C. for 10 minutes and 110 ° C. for 2 minutes. An electrolytic copper foil having a thickness of 35 μm was press-bonded and integrated by a roll laminator at a lamination condition of 140 ° C., a linear pressure of 5 kg / cm and a speed of 2 m / min. Then, after-curing was performed by heating in an oven at a temperature of 80 ° C. for 2 hours and at a temperature of 170 ° C. for 3 hours. The characteristics of the flexible printed wiring board thus obtained are shown in Table 1.

(Example 2) Byron 30P (trade name of polyester resin manufactured by Toyobo Co., Ltd.)
50% MEK of 500 parts of 20% solution dissolved in EK, Epicoat 154 (trade name of non-halogen containing epoxy resin having 3 or more novolac type epoxy groups, manufactured by Yuka Shell Epoxy Co., Ltd.)
60 parts of solution, 120% of 50% MEK solution of BREN-S used in Example 1
Part, Epicoat 5048 (trade name of bromine-containing epoxy resin having two brominated bisphenol A type epoxy groups, manufactured by Yuka Shell Epoxy Co., bromine content 24 to 26%), 50% MEK
Solution 80 parts, trimellitic anhydride 15 parts, 2E4MZ-CN (previously mentioned)
3 parts and 10 parts of antimony trioxide were charged and the antimony trioxide was sufficiently dispersed with a ball mill or the like to prepare an adhesive solution. The bromine content in the resin component of this adhesive composition was 12.4%. Then, a substrate for flexible printed wiring was manufactured according to the procedure shown in Example 1. The characteristics are shown in Table-1.

(Example 3) Byron 300 (a polyester resin trade name manufactured by Toyobo Co., Ltd.)
500 parts of 20% solution dissolved in EK, 100 parts of 50% MEK solution of Epicoat 871 (trade name of non-halogen containing epoxy resin having two epoxy groups, manufactured by Yuka Shell Epoxy Co., Ltd.), BREN-S
50 parts of 50% MEK solution (described above), 50 of Epicoat 5050 (trade name of bromine-containing epoxy resin having two brominated bisphenol type epoxy groups, bromine content 47-51%, manufactured by Yuka Shell Epoxy Co., Ltd.) % MEK solution 60 parts, pyromellitic dianhydride 1
0 parts, 3 parts of 2E4MZ (trade name of imidazole manufactured by Shikoku Fine Chemicals Co., Ltd.) and 12 parts of antimony trioxide were charged, and antimony trioxide was sufficiently dispersed with a ball mill or the like to prepare an adhesive solution. The bromine content in the resin component of this adhesive composition was 13.0%. Then, according to the procedure shown in Example 1, a flexible printed wiring board was manufactured. The characteristics are shown in Table-1.

(Examples 4 and 5) Flexible printed wiring boards were manufactured under the same conditions except that the Kapton film treated with the low-temperature plasma A was replaced with the Kapton film treated with the low-temperature plasma B and the C in Example 1, and these were respectively implemented. Examples 4, 5
And The characteristics are shown in Table-1.

Comparative Example 1 A flexible printed wiring board was manufactured under the same conditions as in Example 1 except that 3 parts of 2E4MZ-CN (described above) was not used. This characteristic is shown in Table-1.

(Comparative Example 2) A substrate for flexible printed wiring under the same conditions except that 120 parts of 50% MEK solution of BREN-S (supra) was replaced with 100 parts of 50% acetone solution of Epicoat 5050 (supra) in Example 1. Was manufactured. This characteristic is shown in Table-1.

Comparative Example 3 A flexible printed wiring board was prepared under the same conditions except that 80 parts of 50% MEK solution of Epicoat 5048 (supra) was replaced with 80 parts of 50% MEK solution of Epicoat 828 (supra). Manufactured. This characteristic is shown in Table-1.

Comparative Example 4 A flexible printed wiring board was manufactured under the same conditions as in Example 3, except that the Kapton film treated with the low-temperature plasma A was replaced with an untreated Kapton film. This characteristic is shown in Table-1.

(Effects of the Invention) The present invention includes: a) a polyester resin, b) a non-halogen-containing epoxy resin having two or more epoxy groups in the molecule, and c) a halogen-containing epoxy resin having two epoxy groups in the molecule, D) Halogen-containing epoxy resin having 3 or more epoxy groups in the molecule , (F) acid anhydride, (f) imidazole compound, g) flame-retardant adhesive composition consisting of flame-retardant aid, low-temperature plasma-treated electrically insulating film and metal foil laminated with this adhesive Heat-resistant, flame-retardant flexible printed wiring board that has been made into a material, has excellent heat-resistance, flame-retardant and flexibility that could not be obtained with conventional adhesives, and has extremely high industrial utility value. It is a thing.

Claims (2)

[Claims] 1. A) 100 parts by weight of polyester resin b) 20 to 80 parts by weight of non-halogen-containing epoxy resin having two or more epoxy groups in the molecule c) Halogen-containing epoxy having two epoxy groups in the molecule Resin 20 to 80 parts by weight d) Halogen-containing epoxy resin having 3 or more epoxy groups in the molecule 30 to 100 parts by weight e) Organic acid anhydride 2 to 40 parts by weight He) Hemidazole compound 0.5 to 10 parts by weight and G) Flame-retardant auxiliary agent A flame-retardant adhesive composition comprising 4 to 20 parts by weight, and the halogen content in the resin component consisting of components a) to f) being 10% by weight or more. 2. A flame-retardant flexible printed wiring board obtained by laminating and integrating a metal foil on a low-temperature plasma-treated plastic film via the flame-retardant adhesive composition according to claim 1.