JPH093221A - Highly adhesive polyimide film - Google Patents

Abstract

PURPOSE: To obtain the highly adhesive polyimide film excellent in heat resistance, chemical resistance and electric characteristics and useful as a substrate for flexible printed wiring boards, etc., by applying a surface-activation treatment to the surface of a polyimide film and subsequently coating the treated surface with a coupling agent. CONSTITUTION: The surface of a polyimide film e.g. obtained from pyromellitic dianhydride and 4,4'-diaminodiphenylether is subjected to an activation treatment by a method selected from a low temperature plasma treatment, a corona discharge treatment and an UV light treatment or to a surface-activation treatment using an inorganic gas such as helium, and subsequently coated with a coupling agent such as a silane coupling agent in a coating film thickness of 0.1-5g/m<2> based on the area of the film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly adhesive polyimide film, and more particularly to a highly adhesive polyimide film having excellent adhesiveness between the polyimide film and the adhesive.

[0002]

2. Description of the Related Art Since it is preferable that the base film of a flexible printed wiring board has high heat resistance and excellent electrical and mechanical properties, a polyimide film is generally used for the base film. It is based on a base film and a copper foil which are laminated and integrated via an adhesive. Adhesiveness, heat resistance, chemical resistance, and electrical characteristics are required for this flexible printed wiring board. As it progresses, adhesion is becoming more important for this.

[0003]

However, this polyimide film generally has poor adhesiveness, and when it is used as a base film of a substrate for flexible printed wiring, peeling occurs at the interface between the polyimide and the adhesive. However, there is a drawback that the peel strength becomes low, and in order to improve this, alkali etching and treatment with a silane coupling agent are carried out, and an attempt is made to transfer this peeling to cohesive failure of the adhesive. (See JP-A-6-32926 and JP-A-6-33653).
Although the adhesiveness is improved by these methods, the adhesiveness has not yet been sufficiently obtained due to insufficient active groups on the polyimide film surface and insufficient chemical bonding. There is a problem.

[0004]

The present invention relates to a highly adhesive polyimide film which solves the above disadvantages and problems, which is obtained by subjecting the surface of a polyimide film to a surface activation treatment and then the surface treatment. It is characterized in that a coupling agent is applied to the active treatment surface.

That is, as a result of various investigations by the present inventors to develop a highly adhesive polyimide film having excellent adhesiveness between the polyimide film and the adhesive, firstly, the surface of the polyimide film was treated with a low temperature plasma. After surface activation treatment such as corona discharge treatment, ultraviolet treatment, etc., and then applying a coupling agent to this surface activation treated surface, the peel strength between the polyimide film and the adhesive increases and the solder heat resistance The present invention has been completed by finding that it also improves. This will be described in more detail below.

[0006]

The present invention relates to a highly adhesive polyimide film, which comprises subjecting the surface of a polyimide film to a surface activation treatment as described above and then applying a coupling agent to the surface activation treated surface. It will be. The polyimide film used in the present invention may be any known in the art and is therefore obtained from the reaction of a tetracarboxylic dianhydride and an aromatic diamine. For example, a polyimide film containing pyromellitic dianhydride and 4,4′-diaminodiphenyl ether, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and p-phenylenediamine as main components, and the like. It is illustrated.

The surface activation treatment of the polyimide film may be performed by treating one or both sides of the polyimide film with an inorganic gas activated by low temperature plasma treatment, corona discharge treatment, or ultraviolet treatment. The surface can be easily activated.

This low-temperature plasma treatment method is such that a polyimide film is placed in a low-temperature plasma treatment apparatus capable of reducing the pressure, and the inside of the apparatus is set to an atmosphere of inorganic gas at a pressure of 0.001-10.
A low temperature plasma of an inorganic gas is generated by applying a direct current or an alternating current of 0.1 to 10 kV between the electrodes while maintaining it at Torr, preferably 0.01 to 1 Torr, to perform glow discharge,
The surface of the film may be continuously plasma-treated while sequentially moving the film.
It should be 100 seconds. As the inorganic gas, an inert gas such as helium, neon, or argon, or oxygen, carbon monoxide, carbon dioxide, ammonia, or air may be used, but these are not limited to one type, and two or more types may be used. You may mix and use.

Further, in this corona discharge treatment method, a high voltage is applied between a roller supporting a polyimide film and an electrode installed opposite thereto to cause corona discharge, and during this period, the surface of the film to be surface treated is treated. The surface treatment may be performed sequentially with the upper side set, and the treatment conditions at this time are frequency 1 to
150kHz, output 0.5 to 40kW, processing time 0.001 to 1 second may be used, but as this inorganic gas, inert gas such as helium, neon, or argon, or oxygen, carbon monoxide, carbon dioxide, ammonia, or air is used. It suffices to do so, and these are not limited to one type, and two or more types may be mixed and used.

Further, the method of this ultraviolet treatment has a wavelength of 1
The polyimide film may be continuously irradiated with this ultraviolet light by using a low-pressure mercury lamp of 80 to 280 nm, and the treatment conditions at this time may be a treatment temperature of 2 to 150 ° C. and a treatment time of 1 to 100 seconds. At this time, it is preferable to carry out in an atmosphere of an inorganic gas, and as the inorganic gas, an inert gas such as helium, neon, or argon, or oxygen, carbon monoxide, carbon dioxide, ammonia, or air can be used. Not limited to
You may use it in mixture of 2 or more types. Among them, activation treatment by low temperature plasma treatment is preferable.

With respect to the polyimide film whose surface has been activated in this way, a coupling agent is then applied to this activated surface. By applying the coupling agent to the active treatment surface, a crosslinking reaction occurs between the groups present on the film surface and the coupling agent. Examples of the coupling agent used here include a silane coupling agent and a titanate coupling agent. Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropyl. Epoxysilanes such as diethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrichlorosilane, vinyltris (β-
(Methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane and other vinylsilanes, γ
-Acrylic silanes such as methacryloxypropyltrimethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl)
-Γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-
Aminosilanes such as aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-
Examples include chloropropyltrimethoxysilane and the like. Further, as titanate coupling agents, isopropyltriisostearoyl titanate, isopropyltridecylbenzenesulfonyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetra (2,2-diallyloxymethyl) Examples include -1-butyl) bis (di-tridecyl) phosphite titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, bis (dioctyl pyrophosphate) ethylene titanate, isopropyl trioctanoyl titanate, and isopropyl tricumylphenyl titanate. .

Among these, epoxysilane-based and aminosilane-based coupling agents are preferred as the silane-based coupling agent, and alkoxy titanate-based and oxyacetate titanate-based coupling agents are preferred as the titanate-based coupling agent. These may be used alone or in combination of two or more.

The coating of the coupling agent on the film may be carried out by a dry method in which it is applied as it is, but this is carried out by diluting a predetermined amount of the coupling agent with an aqueous or water-alcohol solvent to 0.05 to 5 wt%. The wet method may be used, and examples of the alcohol solvent include lower alcohols such as methanol, ethanol and isopropyl alcohol. In this case, the water / alcohol ratio is 0/100
~ 20/80 is recommended. Both the dry method and the wet method may be applied by a bar coater, a spray, or the like, and the wet method may be followed by drying the solvent.

If the amount of the coupling agent to be treated is less than 0.1 g / m ^{2 with} respect to the surface area of the treated surface, the treatment will be insufficient, and the improvement of the adhesive, which is the object of the present invention, will not be noticeable. it exceeds 5 g / m ² and got coupling agent layer is thicker, the heat resistance of the film, because the adhesion decreases, this is a good be 0.1-5 g / m ^2, which is preferably 0.3 It is preferable that the amount is ˜3 g / m ^2, which makes it possible to obtain a polyimide film having high adhesiveness regardless of the composition of the adhesive. In this way, the polyimide film coated with the coupling agent is a flexible copper clad laminate,
Used for electronic parts such as coverlay film.

[0015]

EXAMPLES Examples of the present invention and comparative examples will now be described.
The physical property values in the examples are the values measured by the following measuring methods. (Peeling strength measurement method) The sample is compliant with JIS C6481.
Measure the force when the film is cut into a width of 10 mm and peeled to the film side at a speed of 50 mm / min in the 90 ° direction. (Solder heat resistance measurement method) In accordance with JIS C6481, the sample is cut into 25 mm squares and the maximum temperature at which flow solder does not float, swell, or peel for 30 seconds is measured.

Example 1 Polyimide film Kapton 100H having a thickness of 25 μm
(Product name manufactured by DuPont, USA), vacuum degree 0.1 Torr or less,
Oxygen flow rate of 1.0 L / min, applied voltage of 2 kV, frequency of 110 kHz, output of 30 kW, line speed of 50 m / min. 4 electrodes were placed 40 mm outside the electrode of a plasma generator in a cylindrical shape, and this polyimide film was placed. The surface was subjected to a low temperature plasma treatment and a surface activation treatment.

Then, methanol / water (weight ratio 90 /
Γ-glycidoxypropyltrimethoxysilane diluted to a 5 wt% solution with the mixed solution of 10) was applied to the film surface by an applicator as an amount of the coupling agent of 0.5 g /
m ^{2 is} applied and dried at 80 ° C. for 5 minutes, and a bonding sheet E 33 [trade name, Epoxy-NB manufactured by Shin-Etsu Chemical Co., Ltd.] is provided between two treated polyimide films thus obtained.
R type adhesive sheet] and press it to 50kg / cm ² ×
A three-layer film was produced by pressure bonding at 160 ° C. for 30 minutes, and the peeling strength and solder heat resistance of this film were examined and the peeling state was observed. The results shown in Table 1 below were obtained. .

Examples 2 to 4 Coupling agent was isopropyltriisostearoyl titanate (diluted with methanol alone to a 5 wt% solution), N-
Same as Example 1 except that β (aminoethyl) -γ-aminopropyltrimethoxysilane (diluted with water / methanol mixed solvent) and isopropyl tricumylphenyl titanate (diluted with water / methanol mixed solvent) were used. To produce a three-layer film, and the peel strength of these films,
When the peeling state was observed by examining the solder heat resistance, the results shown in Table 1 below were obtained.

COMPARATIVE EXAMPLE 1 The polyimide film used in Example 1 was untreated and was not coated with a coupling agent.
A three-layer film was prepared by the same method as in Example 1, and the peel strength and solder heat resistance of this film were examined and the peeled state was observed.
The results shown in Table 1 described later were obtained.

Comparative Example 2 The polyimide film used in Example 1 was not subjected to low-temperature plasma treatment, but the same coupling agent as in Example 1 was applied thereto in the same manner as in Example 1, and the same as in Example 1 from now on. A three-layer film is produced by the method, and the peel strength
When the peeling state was observed by examining the solder heat resistance, the results shown in Table 1 below were obtained.

Comparative Example 3 The polyimide film used in Example 1 was subjected to low temperature plasma treatment in the same manner as in Example 1, and the treated surface was coated with γ-glycidoxypropyltrimethoxysilane at a coating amount of 10.0.
After coating in the same manner as in Example 1 except that the amount was increased to g / m ² , a three-layer film was prepared in the same manner as in Example 1, and the peel strength and solder heat resistance of this film were examined and the peeled state was observed. However, the results shown in Table 1 below were obtained.

[0022]

[Table 1]

Example 5 The polyimide film used in Example 1 was subjected to low-temperature plasma treatment in the same manner as in Example 1, and ethanol / water (weight ratio 90/10) was placed on the plasma-treated surface. Γ-Aminopropyltriethoxysilane diluted to a 5 wt% solution with the mixed solution was applied to the film surface by an applicator at 0.8 g / m ^{2 and} dried at 80 ° C. for 5 minutes. After the epoxy-nylon adhesive is applied to the treated surface of the treated polyimide film thus obtained, this and 35 μm-thick electrolytic copper foil / JIC mat (product name of Japan Energy Co., Ltd.) is rolled. Laminating roll (roll temperature
120 ° C, linear pressure 20kg / cm, line speed 3m / min), and heat treatment at 150 ° C for 3 hours to cure the adhesive to make a laminated film for flexible printed wiring board. When the peeling strength and solder heat resistance of the film were examined and the peeled state was observed, the results shown in Table 2 below were obtained.

Examples 6 and 7 A three-layer film was prepared in the same manner as in Example 1 except that the coating amount of the coupling agent was changed, and the peeling strength and solder heat resistance of this film were examined and the peeled state was observed. The results shown in Table 2 below were obtained.

Examples 8 and 9 Three layers were prepared in the same manner as in Example 1 except that a 25 μm thick polyimide film apical (manufactured by Kanegafuchi Chemical Industry Co., Ltd.) was used and the low temperature plasma treatment was changed to corona discharge and UV irradiation. A film was made. Corona discharge treatment: Frequency 100kHz, output 5kW, Air atmosphere line speed 10m / min Ultraviolet irradiation: Output 200w, temperature 80 ° C, Air atmosphere line speed 5m / min, wavelength 254nm

Comparative Example 4 A laminated film for a flexible wiring substrate was prepared in the same manner as in Example 4 except that the low temperature plasma treatment was not performed, and the peel strength and solder heat resistance of this film were examined. When the peeled state was observed, the results shown in Table 2 below were obtained.

[0027]

[Table 2]

[0028]

Industrial Applicability The present invention relates to a highly adhesive polyimide film, which can improve the adhesiveness of the polyimide film regardless of the composition of the adhesive. This provides an advantage that a film useful for manufacturing such as can be easily supplied.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshitsugu Sakae No. 1 Towada, Kamisu-cho, Kashima-gun, Ibaraki Prefecture Shin-Etsu Chemical Co., Ltd.

Claims (3)

[Claims] 1. A highly-adhesive polyimide film which is obtained by subjecting the surface of a polyimide film to a surface activation treatment and then applying a coupling agent to the surface activation treated surface. 2. The highly adhesive polyimide film according to claim 1, wherein the surface activation treatment is performed with an inorganic gas activated by a method selected from low temperature plasma treatment, corona discharge treatment, and ultraviolet treatment. . 3. The highly adhesive polyimide film according to claim 1, wherein the treating amount of the coupling agent is in the range of 0.1 to 5 g / m ² with respect to the film area.