JPH08132574A - Polyimide film - Google Patents

Abstract

PURPOSE: To prevent adhesion of a polyimide film surface after alkali treatment to printing ink, a metallic plated layer, an adhesive, a cover lay, and their adhesive properties from being lowered owing to contact with water or aqueous detergent in after treatment. CONSTITUTION: A polymer film 2 of a thermosetting polymer film or a thermosoftening polymer film, or a mixed film of the thermosetting polymer film and the thermosoftening polymer film is formed on one side surface of a polyimide film 1 or its both side surfaces. Thereby, mechanical properties and chemical properties as the film can be improved, and resistance properties against alkali treatment can be especially raised.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for surface treatment of films for flexible printed circuit boards used in electronic equipment. The present invention relates to a technique capable of improving resistance to alkali without impairing the mechanical properties and chemical properties of a film. INDUSTRIAL APPLICABILITY According to the present invention, even if cleaning is performed using a water-based or hydrocarbon-based cleaning agent, the adhesion and the adhesiveness with the printing ink, the metal plating layer, the adhesive, the coverlay, etc. can be prevented from being impaired. Regarding technology.

[0002]

2. Description of the Related Art Industrial use in the field of electronics,
Consumer electronic devices have become smaller and lighter, and various high-performance materials have been developed in response to the progress. In particular,
In the field of flexible printed circuit boards, polyimide film, polyether ether ketone film, polyphenylene sulfide film, polyethylene naphthalate film, wholly aromatic polyamide film, polyparabanic acid film, polysulfone film, polyether sulfone film, polyetherimide Examples include the development of films and polyarylate films.

Among them, the polyimide film has attracted attention because it can withstand a wide temperature range because it is excellent in heat resistance in addition to excellent mechanical properties, chemical properties, and electrical properties. It is widely used in the field as a base film for copper-clad laminates and coverlays. These copper-clad laminates and coverlays are subjected to processing such as etching, metal plating, press working, soldering, etc., and then washed with flux to be incorporated in electronic equipment.

[0004]

Conventionally, the above-mentioned copper clad laminate and cover lay have been cleaned with a CFC-based cleaning agent, but an environmental problem of ozone layer depletion due to CFCs occurs. The use of system solvents is prohibited,
At present, they are replacing water-based or hydrocarbon-based cleaning agents.

Although the polyimide film is a material that is weak in alkali resistance, it is not significantly affected by the degree of alkali treatment for stripping the resist when processing the flexible printed circuit board. That is, when the polyimide film surface is printed or metal-plated after such an alkali treatment, or a cover lay or the like is laminated with an adhesive and then washed with a CFC-based or hydrocarbon-based solvent, the adhesion and The adhesiveness did not deteriorate.

However, when the cleaning agent is a water-based cleaning agent or water, the adhesion between the polyimide film surface and the printing ink, the metal plating layer, the adhesive, the cover lay, etc. deteriorates, and the adhesion There was a problem that the surface was easily peeled off.

The present invention has been made under such a background, and the film surface and the printing ink, the metal plating layer, the adhesive, and the cover are cleaned even if the cleaning is performed with an aqueous cleaning agent or water. An object of the present invention is to provide a method for surface-modifying a polyimide film that does not impair the adhesiveness and the adhesiveness with a ray or the like.

[0008]

According to the present invention, even if cleaning is performed using an aqueous cleaning agent or water, the adhesion and the adhesiveness with a printing ink, a metal plating layer, an adhesive, a coverlay, etc. are impaired. The first viewpoint is a polyimide film which is a base material of a flexible printed circuit board, and a film of thermosetting polymer and / or thermosoftening polymer is formed on at least one surface of the polyimide film. It is characterized by that. The thickness of the film is preferably 0.01 μm to 10 μm.

A second aspect of the present invention is a method for improving the surface properties of a polyimide film, which comprises forming a polymer film having a thickness of 0.01 μm to 10 μm on at least one surface. To do.

A third aspect of the present invention is a method for cleaning the surface of a polyimide film, which comprises cleaning after forming a polymer film having a thickness of 0.01 μm to 10 μm on the surface of the polyimide film. And The surface cleaning liquid is effective when it is an aqueous cleaning agent or water.

[0011]

The thermosetting polymer, the thermosoftening polymer, or the mixture film of the thermosetting polymer and the thermosoftening polymer is formed on at least one surface of the polyimide film. By thus forming a polymer film having a film thickness of 0.01 μm to 10 μm on at least one surface, the surface properties of the polyimide film can be improved.

That is, when a polymer film is formed on the surface of a polyimide film and then washed with a water-based or hydrocarbon-based cleaning agent, the polyimide film surface and printing ink, a metal plating layer, an adhesive, It is possible to prevent the adhesion and the adhesion with the coverlay and the like from being impaired.

Further, a polymer film is formed on at least one of the polyimide films, or the resin composition of the polyimide film is a wholly aromatic, aromatic-aliphatic or aliphatic various polyimide resin. For example, the thickness of the film can be selected in the range of 12.5 μm to 125 μm as required.

For the thermosetting polymer film, phenol resin,
A thermosetting resin such as xylene resin, epoxy resin, polyol / polyisocyanate-based urethane resin, thermocrosslinking acrylic resin, photocrosslinking acrylic resin, thermosetting polybutadiene, unsaturated polyester, or polyamide polyamine is used. They are used alone or as a mixture of two or more types depending on the required properties of the membrane.

For the thermoplastic polymer film, a thermoplastic resin such as polybutadiene, SBR (styrene butadiene rubber), NBR (nitrile butadiene rubber), nylon, polyester, allyl rubber, or a thermosoftening epoxy resin is used. They are used alone or as a mixture of two or more types depending on the required properties of the membrane.

The above-mentioned thermosetting resin and thermoplastic resin can be used in the mixed film of the thermosetting polymer and the thermosoftening polymer, and if necessary, two or more kinds of resin materials can be appropriately used. It can also be mixed.

It is also possible to add various inorganic fillers, flame retardants, etc. to the thermosetting polymer film and the thermoplastic polymer film, or the mixed film of the thermosetting polymer and the thermoplastic polymer. In addition, a high-molecular or low-molecular curing agent, a catalyst, and various modifiers can be added depending on the purpose.

As described above, various polymers and low molecular weight compounds can be used in the coating film used for the surface modification of the polyimide film, but in order not to impair the heat resistance which is a major feature of the polyimide film. It is preferable to select a resin having high heat resistance, and examples thereof include a mixed system of an epoxy resin, an epoxy resin curing agent, and a polyamide resin.

The epoxy resin is preferably an epoxy resin having two or more epoxy groups in one molecule. Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin and carboxylic acid. There are polyglycidyl ether, urethane-modified epoxy resin, brominated epoxy resin and the like, and these can be used alone or in a mixture of two or more kinds. As commercially available epoxy resins, Epicoat series (made by Shell Chemical Co., Ltd.), Araldite series (made by Ciba Geigy Co., Ltd.), DER series (made by Dow Chemical Co., Ltd.), Epicron series (made by Dainippon Ink and Chemicals Co., Ltd.), etc. are used. it can.

Considering the mixing with the epoxy resin, the polyamide resin is preferably an aliphatic amidoamine compound having a solvent-soluble amide group, which acts as a curing agent for the epoxy resin. As commercially available solvent-soluble polyamide resins, Amilan CM4000 and CM
8000 (manufactured by Toray Industries, Inc.), polymite series (manufactured by Sanyo Chemical Industry Co., Ltd.), Versamide series (manufactured by Daiichi General Co., Ltd.), Zenamide series (manufactured by Henkel Hakusui Co., Ltd.) and the like can be used.

Other curing agents for epoxy resin include diethylenetriamine, triethylenetriamine, diethylaminopropylamine, N-aminoethylpiperazine,
Dicyandiamide, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and 2-dimethylaminomethylphenol, etc.,
As the curing accelerator, triethanolamine-trifluoroboron complex, salts with Lewis acids such as hexylamine-trifluoroboron complex and monomethylamine-trifluoroboron complex, and aliphatic amine compounds having a tertiary amine and There are aromatic amine imidazole compounds and the like, and one or more of these can be added.

It is also possible to use acid anhydrides such as methyl nadic acid anhydride, hexahydrophthalic acid anhydride, pyromellitic acid anhydride, and benzophenone tetracarboxylic acid anhydride as a curing agent.

The coating method of the thermosetting polymer and the thermoplastic polymer or the mixture of the thermosetting polymer and the thermoplastic polymer on the polyimide film surface may be wire bar coating, reverse roll coating, kiss coating, gravure coating, etc. The thin film coating method is preferable, and it can be selected depending on the property and coating thickness of the coated product, and the dilution method such as dilution with a solvent can be appropriately selected according to the property and coating method of the coated product.

The reaction or drying method after the application of the thermosetting polymer and the thermoplastic polymer or the mixture of the thermosetting polymer and the thermoplastic polymer onto the polyimide film surface is as follows:
A method suitable for the properties of the coating material, such as far-infrared heating, hot air heating, high frequency heating, or ultraviolet curing, can be selected, and the conditions therefor can be appropriately determined.

The coating film thickness of the thermosetting polymer film and the thermoplastic polymer film or the mixed film of the thermosetting polymer and the thermoplastic polymer can be in the range of 0.01 μm to 10 μm as described above. However, in the case of maintaining the mechanical properties of the polyimide film as it is, the thickness is preferably about 0.1 μm to 5 μm. When the coating thickness is less than 0.01 μm, the surface modification and curing of the polyimide film may be halved.

The polyimide film thus surface-treated is used in the following various films after the film is subjected to alkali treatment and washing with water.

1. Film for applying printing ink 2. Film for electroless plating 3. Films for metal vapor deposition and sputtering 4. Base film for coverlay 5. Adhesive film with adhesive such as bonding sheet and cover lay 6. Base film for bonding with metal foil, etc.

[0028]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view showing an example of the constitution of a polyimide film according to the present invention. In this example, a 5 μm-thick polymer film 2 made of a thermosetting polymer material or a thermosoftening polymer material is formed on one surface of a 25 μm-thick polyimide film 1. FIG. 2 is a sectional view showing an example of a structure in which the metal film according to the present invention is formed. In this example, a 25 μm polyimide film 1 is formed by an adhesive layer 5 on one surface of a 18 μm metal film (Cu) 4, and a 5 μm polymer film is formed on one surface of the polyimide film 1.

Here, some specific examples and comparative examples will be described. These are merely examples and do not limit the technical scope of the present invention.

(Example 1) As shown in FIG. 3, Macromelt 6 was formed on one side of a 25 μm thick Kapton film (polyimide film manufactured by DuPont Toray) as a polymer film.
238 (Hot melt polyamide manufactured by Henkel Hakusui Co., Ltd.) was applied with a die coater to a thickness of 5 μm, and after cooling, it was immersed in a 3 wt% sodium hydroxide aqueous solution at 40 ° C. for 2 minutes, washed with water, and dried at 80 ° C. for 30 minutes. . Next, apply Nikaflex CISV to the surface of the Kapton film coated with macromelt.
-2535 (DB) (Nickan Kogyo Co., Ltd. cover lay) adhesive surface, molding temperature 160 ℃, molding pressure 40 kg / cm
^2. Press bonding was performed at a molding time of 90 minutes. Next, press Kapton film and Nicaflex CISV-253
The adhesive strength (normal state) of 5 (DB) without chemical treatment and the adhesive strength in chemicals were measured. The chemicals used were Freon TF (a CFC-based solvent manufactured by Mitsui DuPont Fluorochemicals) and water. The measured adhesive strength is shown in Table 1.

(Example 2) Polymer film having a thickness of 25 μm
50 parts of Epicoat 828 (manufactured by Shell Chemical Co., Ltd.), 20 parts of Polymide L-45- (3) (manufactured by Sanyo Chemical Industry Co., Ltd.), and 500 parts of methyl ethyl ketone are mixed on one side of the Kapton film (polyimide film manufactured by DuPont Toray). The obtained product was applied by a casting method, dried and reacted at 130 ° C. for 1 hour to obtain a coating thickness of 2 μm. After treating with a sodium hydroxide aqueous solution, washing with water and drying in the same manner as in Example 1, Nikaflex CISV-is applied to the coated surface of the Kapton film.
The adhesive surface of 2535 (DB) was press-bonded under the same press conditions as in Example 1. The adhesive strength of the press-bonded article was measured under the same conditions as in Example 1. The measured adhesive strength is shown in Table 1.

(Example 3) Polymer film having a thickness of 50 μm
100 parts of ThreeBond 1570 (epoxy knitting resin manufactured by ThreeBond Co., Ltd.), 5 parts of JA-7405 (phenoxy resin manufactured by Sumitomo 3M Co., Ltd.), and 500 parts of methyl ethyl ketone were mixed on one surface of an apical film (polyimide film manufactured by Kanegafuchi Chemical Co., Ltd.). The product was applied with a kiss coater, dried and cured at 160 ° C. for 30 minutes to obtain a coating film thickness of 1 μm. After treating with an aqueous sodium hydroxide solution in the same manner as in Example 1, washing with water and drying, the adhesive surface of Nicaflex CISV-2535 (DB) was applied to the application surface of the apical film under the same pressing conditions as in Example 1. Press bonded. The adhesive strength of the press-bonded article was measured under the same conditions as in Example 1. The measured adhesive strength is shown in Table 1.

(Example 4) Polymer film having a thickness of 25 μm
40% ethyl acrylate on one side of the apical film
And 200 parts of a methyl ethyl ketone solution (solid content 20 wt%) of a copolymer of methyl methacrylate 40% and glycidyl ether acrylate 20%, 1-benzyl-
What added 3 parts of 2-methyl imidazole was apply | coated by the cast method, it was made to dry and react at 130 degreeC for 1 hour, and 3 micro | micron | mu.
A coating thickness of m was obtained. Next, it was immersed in a 3 wt% potassium hydroxide aqueous solution at 40 ° C. for 2 minutes, washed with water, and dried at 105 ° C. for 30 minutes. Next, as in Example 3, the adhesive surface of Nicaflex CISV-2535 (DB) was press-bonded to the coated surface of the apical film, and the adhesive strength was measured. The measured adhesive strength is shown in Table 1.

(Comparative Example 1) The measurement was performed in the same manner as in Example 1 except that the surface modification treatment with Macromelt 6238 was not performed. The adhesive strength is shown in Table 1.

Comparative Example 2 Example 4 is the same as Example 4 except that the surface modification treatment on one side of the apical film is not performed.
It measured similarly to. The adhesive strength is shown in Table 1.

[0036]

[Table 1] As shown in Table 1, in the case of Examples 1 to 4, there was no change in the adhesive force even after washing with water, and in the cases of Comparative Example 1 and Comparative Example 2, a remarkable decrease in the adhesive force was observed. .

[0037]

As described above, according to the present invention, the surface properties of a polyimide film can be improved, and even if cleaning is performed using an aqueous system or water, the polyimide film surface and printing ink, metal plating The adhesiveness with the layer, the adhesive, the coverlay, and the like can be prevented from being impaired, and the reliability of the flexible printed circuit board can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of the configuration of a polyimide film according to the present invention.

FIG. 2 is a sectional view showing an example of a structure in which a metal film according to the present invention is formed.

FIG. 3 is a cross-sectional view showing the structure of the polyimide film of Example 1 according to the present invention.

[Explanation of symbols]

 1 Polyimide film 2 Polymer film 4 Metal film (Cu) 5 Adhesive layer

Claims (5)

[Claims] 1. A polyimide film having a film of a thermosetting polymer and / or a thermosoftening polymer formed on at least one surface thereof. 2. The thickness of the film is 0.01 μm to 10 μm.
The polyimide film according to claim 1, which has a thickness of μm. 3. A thickness of 0.01 on at least one surface.
A method for improving the surface properties of a polyimide film by forming a polymer film having a thickness of 10 μm to 10 μm. 4. A polyimide film having a thickness of 0.
A method for cleaning the surface of a polyimide film, which comprises cleaning a polymer film having a thickness of 01 μm to 10 μm and then cleaning the film. 5. The method according to claim 3, wherein the polymer film contains a thermosetting polymer and / or a thermosoftening polymer.