JPS63173634A - Substrate for flexible printed wiring - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a flexible printed wiring board with excellent electrical properties, particularly insulation properties.

(Conventional technology) In recent years, with the diversification and miniaturization of electrical and electronic equipment,
Demand for flexible printed wiring boards is increasing.

A flexible printed wiring board is made by etching metal foil pasted on an insulating film to form a circuit, then attaching resistors, capacitors, coils, etc. Il:.

(Holder), individual transistors, switch terminals, etc. are attached with solder to form a flexible printed circuit. The flexible printed wiring board used for this flexible printed circuit is an insulating film and metal foil (
The insulating film used is mainly polyethylene terephthalate film, polyimide film, polyether/ether ketone film, or polyether sulfone film.

Adhesives need to be flexible, and we have many suggestions including nitrile rubber adhesives, polyamide adhesives, polyester adhesives, polyacrylic adhesives, epoxy adhesives, and phenolic adhesives. has been done.

However, these conventional adhesives do not meet the requirements of high insulation between wiring and high adhesion between insulating film circuits (copper foil), which are strongly required for flexible printed wiring boards as electric and electronic devices become denser, lighter, thinner, and smaller. Even polyimide resin, which has excellent insulation and heat resistance, has problems with adhesion and lacks flexibility and flexibility, so solving these problems is an urgent issue. was.

(Structure of the Invention) As a result of intensive studies to solve the above-mentioned difficulties, the present inventors succeeded in providing a flexible printed wiring board with excellent insulation, adhesive properties, heat resistance, and flexibility. This invention has led to the invention, and the present invention is to apply dimer acid-based epoxy resin 100% to an insulating film that has been subjected to low-temperature plasma treatment.
Part by weight, bismaleimide triazine resin 50-150
The gist of the invention is a flexible printed wiring board formed by laminating and integrating metal foils via an adhesive consisting of 5 to 80 parts by weight of acrylonitrile-butadiene rubber.

The present invention will be explained in detail below.

Examples of the insulating film used in the present invention include polyimide film, polyphenylene sulfide film, polyparabanic acid film, polyester film, polyether sulfone film, and polyether/ether ketone film, with a thickness of about 12 to 135 μm. Frequently used. Further, as the metal foil, electrolytic copper foil and rolled copper foil are generally used, but aluminum foil is also used.

In the present invention, the above-mentioned insulating film and metal foil are laminated and integrated using the above-mentioned adhesive.The insulating film is previously subjected to surface treatment using low-temperature plasma of an inorganic gas, so that the film and the adhesive can be bonded together. It is necessary to improve the adhesion of the layers.

In this low-temperature plasma treatment method, the insulating film is placed in a low-temperature plasma treatment device capable of reducing pressure, and the pressure is maintained at 0.001 to 10 Torr, preferably 0.601 to 1 Torr, with an aether atmosphere of inorganic gas inside the device. In this state, a direct current or alternating current of about 0.1 to 10 KV is applied between the electrodes to cause glow discharge, thereby generating low-temperature plasma of an inorganic gas, and continuously plasma-treating the surface while sequentially moving the insulating film. Plasma treatment time is approximately 0
．． The time is preferably 1 to 100 seconds.

Inorganic gases used include inert gases such as helium, neon, and argon, oxygen, nitrogen, carbon oxide, carbon dioxide, ammonia, and air, but these are not limited to one type, but are used in a mixture of 2f1 or more. It is also considered optional.

Next, the adhesive used in the present invention is 100 parts by weight of dimer acid epoxy resin and 50 parts by weight of bismaleimide triazine resin.
~150 parts by weight, acrylonitrile-butadiene rubber 5
~80 parts by weight is an essential component, and as a dimer acid-based epoxy resin, the carboxyl group of dimer acid is epoxidized with epichlorohydrin, or the dimer acid is reacted with an epoxy resin, and it can be used alone or in combination of two or more. Mix and use.

The bismaleimide and triazine resins have a blending ratio of bismaleimide of 5 to 100%. Further, resins containing urethane-modified or acrylic-modified resins are preferred, and these are used alone or in combination of two or more.

The acrylonitrile-butane diene rubber preferably has one or more functional groups selected from amino groups, vinyl groups, epoxy groups, and carboxyl groups,
These may be used alone or in combination of two or more.

To obtain the adhesive used in the present invention, 100 parts by weight of the above-mentioned dimer acid type epoxy resin, 50 to 150 parts by weight of bismaleimide triazine resin, preferably 60 to 120 parts by weight,
Parts by weight, acrylonitrile/butane diene rubber 5-80
Parts by weight, preferably 20 to 50 parts by weight, may be simply mixed or heated and mixed.

This mixing ratio is specified because if the amount of the bismaleimide triazine resin is less than 50 parts by weight, the adhesive used in the present invention cannot be provided with satisfactory insulation properties, and if it is more than 150 parts by weight, it will lose its flexibility. If the amount of acrylonitrile-butanediene rubber is less than 5 parts by weight, the adhesive used in the present invention cannot be provided with satisfactory flexibility and adhesive properties, and if it is more than 80 parts by weight, it will lose its insulation properties.

In addition, in the case of heating during mixing, heating may be performed at a heating temperature of 40 to 80° C. for 1 to 30 hours. In addition, an organic solvent can be used if necessary during mixing, and in this case, the solvent is preferably one that has relatively high solubility for the above components, such as ethers such as 1,4-dioxane, methyl ethyl ketone, etc. Examples include ketones such as, aromatic hydrocarbons such as toluene, N-methyl 2-pyrrolidone, etc., and these can be used alone or in a mixture of two or more.

The adhesive is dissolved in a solvent and applied in a solution state, and the above-mentioned organic solvents can be used as the solvent. Further, the solution concentration is preferably adjusted to 10 to 70 wt%.

The adhesive used in the present invention has flexibility and softness provided by an acrylonitrile-butadiene rubber component, adhesive properties provided by a dimer acid-based epoxy resin component, and insulation and heat resistance provided by a bismaleimide-triazine resin. , each component has its own characteristics, and it has particularly excellent insulation properties.

As a method of obtaining a flexible printed wiring board,
Specifically, the following methods i) to 1ii) can be mentioned.

i) Treating the insulating film with low-temperature plasma of inorganic gas,
A method in which an adhesive is applied to this plasma-treated surface, and then a metal foil is pressure-bonded at high temperature or room temperature to harden the adhesive and form a substrate.

if) A method of applying an adhesive to a metal foil, pressing an insulating film whose surface has been treated with low-temperature plasma of an inorganic gas at high temperature or room temperature, and curing the adhesive to form a substrate.

Li1) Treat the insulating film with low-temperature plasma of inorganic gas, apply an adhesive to the treated surface using this plasma, apply the same or different adhesive to the metal foil, press the two together at high temperature or room temperature, and apply the adhesive. A method of curing and making it into a substrate.

To explain these methods in more detail, mainly focusing on method i), the above-mentioned adhesive, dissolved in a solvent if necessary, is applied to the low temperature plasma treated surface of the insulating film using a coating dryer to a thickness of 5 to 150 μm. Apply and store at room temperature ~1
Heat at around 50°C for 0.5 to 30 minutes. Metal foil such as copper foil or aluminum foil is placed on the adhesive side of this adhesive-backed insulating film and heated under pressure with a heat press, or heated under pressure between the rolls of a laminator, and if necessary, after-cured. . Crimping conditions are 80-170℃, pressure 1-1
00 Kgf/cm", heating time is preferably 0.2 to 60 minutes. Also, if after-cure is required, 50 to 2
It is preferable to gradually raise the temperature to a predetermined temperature at 00° C. for 1 to 100 hours without applying pressure or under roll pressure bonding. The method described above involves applying an adhesive to an insulating film and laminating metal foil on it, but the application of this adhesive is i.
As described in methods 1) to 1ii), it may be applied to the surface of the metal foil, or it may be applied to both the insulating film and the metal foil, and then the two are laminated using an adhesive layer as an intermediate layer.

The present invention will be explained below with reference to Examples.

Example 1 A 25 cm square, 25 μl thick capto film (manufactured by DuPont, trade name of polyimide film) was placed in a low temperature plasma processing apparatus, and oxygen was introduced at a vacuum degree of 0.1 torr.
An AC voltage of 110 kHz and 2.5 KV was applied to the electrodes to generate glow discharge, and low-temperature plasma treatment was performed for 60 seconds. The Kapton film was placed on the lower electrode of the upper and lower opposing electrodes, and the distance between the electrodes was 12 cm. Adhesives A, B, and C shown below were applied to this plasma-treated film using a test coater, and then heated at 80° C. for 15 minutes to volatilize the solvent and bring the film into a semi-cured state.

The coating thickness was adjusted to 25 μm using a dryer. An electrolytic copper foil of 25 cm square and 35 μm thick was layered on this film and hot-pressed using a roll method, followed by after-curing to form a copper-clad board. Crimping conditions are temperature 100℃, pressure 5kgf/c
m2, and after-cure was performed at 150°C for 3 hours. Table 1 shows the characteristics of each flexible printed wiring board thus obtained.

Adhesive A: 20 parts by weight of Epicoat 871 (manufactured by Yuka Shell Epoxy Co., Ltd., trade name of dimer acid-based epoxy resin), B
10 parts by weight of a 50% solution of T-2170 (manufactured by Mitsubishi Gas Chemical Company, trade name of bismaleimide triazine resin) dissolved in methyl ethyl ketone, BT-2164 (manufactured by Mitsubishi Gas Chemical Company, trade name of urethane-modified bismaleimide triamine resin) 50% solution of dissolved in methyl ethyl ketone 10
Part by weight, BT-A135 to -A (manufactured by Mitsubishi Gas Chemical Co., Ltd., acrylic modified bismaleimide triazine resin trade name) t
o! l quantity, HYCARATBN (B, F, Good
Weighed and added 100 parts by weight of a 6% solution of modified acrylonitrile-butadiene rubber (trade name manufactured by Rich Corporation) dissolved in methyl ketone and 70 parts by weight of methyl ethyl ketone, mixed at 60°C for about 4 hours, and then filtered.

B: Epicoat 871 (mentioned above) 20 in adhesive A
! Using Evotot YD-171 (manufactured by Tobu Kasei Co., Ltd., dimer acid-based epoxy resin trade name) instead of the amount, and
This was prepared under the same conditions as Adhesive A except that 10 parts by weight of -A (described above) was removed from T-A135.

C: HYCARATBN in adhesive A (mentioned above)
H instead of 100 parts by weight of a 6% methyl ethyl ketone solution of
50 parts by weight of a 6% toluene solution of YCARATBN (described above) and HYCARVTBN (B, F, Goodri
Adhesive A was prepared under the same conditions as Adhesive A except that a mixture of 50 parts by weight of a 6% toluene solution of modified acrylonitrile-butadiene rubber (trade name, manufactured by CH Corporation) was used.

Comparative Example 1 Characteristics of each flexible printed wiring board produced under the same conditions as Example 1 except that instead of applying adhesives A, B, and C in Example, adhesives E and F shown below were applied. are shown in Table 1.

Adhesive D = BT-217 in Adhesive A of Example 1
0 (mentioned above), BT-2184 (mentioned above), BT-A135
- A was produced under the same conditions as Adhesive A except for excluding A-A (described above).

E: HYCARATBN in adhesive A of Example 1
Produced under the same conditions as Adhesive A, except for (mentioned above).

F: Epicoat 871 (
Produced under the same conditions as Adhesive A except for the above).

G: Epicoat 871 (
Previous) Produced under the same conditions as Adhesive A except that the 20 parts by weight was increased to 100 parts by weight.

H: In adhesive A of Example 1) IYCARATB
HYCARCTBN (B, F, Goodri
One was prepared under the same conditions as Adhesive A except that 100 parts by weight of a 50% methyl ethyl ketone solution of modified acrylonitrile-butadiene rubber (trade name, manufactured by CH Corporation) was used.

Example 2 Inside the low temperature plasma processing equipment, a 25 cm square, 25 μm thick
A Kapton film (manufactured by Dupont, trade name of polyimide film) was introduced, oxygen was introduced at a vacuum level of 0.2 torr, and an alternating current voltage of 110 kV and 1.5 kV was applied to the electrodes to generate a glow discharge for 20 seconds. Low temperature plasma treatment was performed. The Kapton film was placed on the lower electrode of the upper and lower opposing electrodes, with a distance of 10 cm between the electrodes. Similarly, low-temperature plasma treatment was performed in a single gas or mixed gas (02 and Ar) of He, Ar%N2, Co, CO2, and NH3 (02 and Ar) or air atmosphere at a pressure of 0.2 Torr.

These plasma IA3! ! Adhesive A in Example 1 was applied to the film using a test coater, and then 8
It was heated at 0° C. for 15 minutes to volatilize the solvent and bring it into a semi-cured state.

The coating thickness was adjusted to 25 μm after drying. An electrolytic copper foil of 25 cm square and 35 μm thick was layered on this film and hot-pressed using a roll method, followed by after-curing to form a copper-clad board. Crimping conditions are temperature 110℃, pressure 10Kgf
/cm', and the after-cure conditions were 130° C. for 4 hours. Table 2 shows the characteristics of each flexible printed wiring board thus obtained.

Comparative Example 2 Example 2 except that adhesive A was applied to an untreated film instead of the low temperature plasma treated film in Example 2.
Table 2 shows the characteristics of the flexible printed wiring board manufactured under the same conditions as above.

Example 3 Kapton film with a thickness of 25 μm and a width of 508 mm (described above)
50m roll of 60m per minute by continuous plasma processing equipment
Plasma treatment was performed at a rate of Il.

Conditions are 0.51/1I helium at vacuum level 0.3 torr.
Supplied by Iin, applied voltage 2KV, input 2 at 110kHz
At 0 KW, the device had four electrodes arranged in a cylindrical shape and was moved along the outer periphery of the film electrode group at a distance of 4 cm from the outside of the electrodes for processing. Adhesive A of Example 1 was continuously applied to the above plasma-treated film using a small continuous laminator and dried.Meanwhile, Adhesive A was used as the metal foil, and rolled copper was continuously applied and dried using a roll coater. Using foil, both were laminated by roll pressure bonding.

The copper clad plate, which had been wound up into a zero-order roll and the thickness of the applied adhesive was adjusted to 25 μm, was placed in a circulating dryer, kept at 130° C. for 6 hours, and then allowed to cool. This flexible printed wiring board was cut, test pieces were taken, and characteristics were measured. Table 3 shows the results.

(Effects of the Invention) As explained above, the flexible printed wiring board produced by the manufacturing method of the present invention has excellent electrical insulation, adhesiveness, heat resistance, and flexibility, and is particularly highly insulating. Therefore, it is suitable as a high-density flexible printed circuit board.

Claims (1)

[Claims] 1. Metal foil is attached to the low-temperature plasma-treated insulating film via an adhesive consisting of 100 parts by weight of dimer acid epoxy resin, 50 to 150 parts by weight of bismaleimide triazine resin, and 5 to 80 parts by weight of acrylonitrile butadiene rubber. A flexible printed wiring board made by integrating layers.