JPH1036792A - Production of polyimide resin bonding film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyimide resin bonding film without deteriorating the tensile breaking strength thereof. SOLUTION: One or both surfaces of a film made of a polyimide resin without thermally melting at <=400 deg.C temperature are coated with a polyimide resin adhesive varnish meltable at <=400 deg.C temperature after solidification and dried to provide a polyimide resin bonding film, which is then stretched under >=0.75 and <=1.75kg/mm tension. The molecular chain orientation of the film, made of the polyimide resin and disordered by heating at the high temperature can be restored by the stretching to prevent the tensile breaking strength of the film from deteriorating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive sheet or tape used in the fields of electronics and electricity.

[0002]

2. Description of the Related Art Polyimide resin adhesive films have been used as insulating adhesive sheets or tapes in the fields of electronics and electronics because of their high reliability. An adhesive sheet having a polyimide resin adhesive layer on one side of a polyimide resin film is used for protecting the circuit surface of a flexible circuit board used at high temperatures, and those having a polyimide resin adhesive layer on both sides are used in the semiconductor field, for example. It is used for joining a lead frame and a semiconductor element, or joining a lead frame and a heat sink.

[0003] Such an adhesive film is coated on one or both sides of a polyimide resin film and then coated with a polyimide resin varnish serving as an adhesive or a polyamide acid varnish which is a precursor of the polyimide resin, or a varnish mixture thereof, and then heated. It is manufactured by scattering and drying the solvent.

[0004]

The polyimide resin film exhibits the tensile properties of the film by giving a certain orientation to the molecular chains. This film is coated with a polyimide resin adhesive varnish. When heat drying is performed, there is a problem that the orientation of the molecular chains is disturbed, and the tensile strength at break decreases.

[0005]

As a result of various studies, the present inventor has found that a polyimide resin film is coated on one or both sides with a polyimide resin adhesive varnish, dried, stretched by applying an appropriate tension, and then stretched. It has been found that the orientation of the polyimide resin film can be restored and the tensile strength at break can be maintained, and the present invention has been completed.

That is, one or both sides of a polyimide resin film which does not melt at a temperature of 400 ° C. or less are coated with a polyimide resin adhesive varnish which can be solidified and then melted at a temperature of 400 ° C. or less and dried. The resulting polyimide resin adhesive film is 0.75 kg / mm or more,
A method for producing a polyimide resin adhesive film, wherein the film is stretched under a tension of 1.75 kg / mm or less.

[0007] The polyimide resin film used in the present invention, which does not melt at a temperature of 400 ° C or less, is preferably used. What does not melt at a temperature of 400 ° C. or less means that the elastic modulus at a temperature of 400 ° C. or less is 100 M
As long as it is Pa or more, it can be used. Commercially available examples of such a polyimide resin film include Upilex (manufactured by Ube Industries), Kapton (manufactured by DuPont), Apical (manufactured by Kanegafuchi Chemical Co., Ltd.), and the like. As the thickness of the polyimide resin film, a film having a thickness of 5 to 200 μm can be used, and a film having a thickness of 10 to 125 μm is preferably used.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a polyimide resin adhesive used in the present invention, an adhesive which can be melted at a temperature of 400 ° C. or less is used. What can be thermally melted at 400 ° C. or lower means that the elastic modulus at a temperature of 400 ° C. or lower is 100
Those having a Pa or more and 1 MPa or less are preferably used.
If it is less than 100 Pa, sufficient mechanical properties cannot be obtained, and if it exceeds 1 MPa, sufficient adhesiveness to an adherend cannot be obtained.

In view of heat resistance, such a polyimide resin adhesive is preferably one which is polymerized from a diamine compound having an aromatic group and an acid dianhydride having an aromatic group. Further, the logarithmic viscosity is 0.1 g / ml or more,
2.0 g / ml or less, preferably 0.3 g / m
1 or more and 1.0 g / ml or less. Logarithmic viscosity 0.1
If the amount is less than g / ml, the mechanical properties deteriorate. If the amount exceeds 2.0 g / ml, the elastic modulus increases, and sufficient heat melting property for obtaining adhesiveness cannot be obtained.

Specific examples of the above diamines include p
Phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylether, 4,
4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 1,3-bis (3-aminophenoxy)
Benzene, bis 4- (3-aminophenoxy) biphenyl, bis 4- (4-aminophenoxy) biphenyl,
2,2-bis (4- (3-aminophenoxy) phenyl) propane, 2,2-bis (4- (4-aminophenoxy) phenyl) propane and the like are used alone or as a mixture. Specific examples of the acid dianhydride include:
Pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, oxyphthalic dianhydride, biphenyltetracarboxylic dianhydride and the like can be used alone or as a mixture. However, the present invention is not limited to these examples, and any of those having an aromatic group and exhibiting thermal fusibility at a temperature of 400 ° C. or less when finally made into an adhesive can be used. . An aliphatic diamine or a silicone diamine can be used in combination as long as the heat resistance is not impaired.

In the present invention, one or both surfaces of a polyimide resin film are coated in a varnish state in which a polyimide resin or a polyamic acid which is a precursor of the polyimide resin is dissolved in a solvent. As a solvent that can be used, any solvent can be used as long as the polyimide resin or the polyamic acid resin shows solubility. Preferred examples of the solvent include N-methyl-2-pyrrolidone, dimethylacetamide, dimethylformamide, diglyme, triglyme and the like.

In the present invention, after one or both surfaces of the polyimide resin film are coated with the above-mentioned polyimide resin varnish or polyamic acid resin varnish using a die coater, a bar coater, a gravure coater or the like, a continuous drying step is carried out. The solvent is scattered, dried and solidified to form an adhesive layer. In the drying step, it is preferable to perform drying while increasing the temperature stepwise in order to obtain a good surface state. Also at this time, it is necessary to increase the maximum drying temperature to reduce the amount of residual solvent in the adhesive,
Generally, it is performed at a temperature of about 250 ° C. to 350 ° C.

The drying method is not particularly limited, and a heating air method, an infrared ray, a far infrared ray method, or the like is used. The thickness of the polyimide resin adhesive layer, 1 ~ 50μ
m is sufficient, but preferably 5 to 25 μm. If the thickness is less than 1 μm, sufficient adhesiveness cannot be obtained.
When it exceeds, drying takes time and productivity is greatly reduced.

When the polyimide resin adhesive film thus obtained is exposed to a high temperature, the orientation of molecular chains is disturbed. This disturbance is observed by X-ray diffraction measurement. FIG. 1 is an X-ray diffraction chart of the polyimide resin film before being exposed to a high temperature, and a sharp almost single peak is observed around a measurement angle of 19 °. , Measurement angle 1
It can be seen that a shoulder peak appears around 8 °, and the orientation is disordered. 0.75 kg / mm or more of the polyimide resin adhesive film obtained as described above,
The orientation is restored by stretching with a tension of 1.75 kg / mm or less. 1.0Kg / mm or more, 1.50K
More preferably, the film is stretched under a tension of g / mm or less. If the tension is less than 0.75 Kg / mm, sufficient restoration of the orientation of the molecular chain cannot be obtained, and if the film is stretched with a tension exceeding 1.75 Kg / mm, the molecular chain will be broken. The polyimide resin adhesive film produced as described above does not cause a decrease in tensile rupture strength, and is useful for insulating adhesive applications in the electronic and electric fields where high reliability is required. Hereinafter, advantages of the present invention will be described with reference to examples.

[0015]

【Example】

Examples 1 to 5 and Comparative Examples 1 to 3 A polyamide acid varnish PAA-Pm (manufactured by Mitsui Toatsu Chemicals) was dried on both sides of a 50 μm Iupirex film (manufactured by Ube Industries) so as to have a thickness of 20 μm. The polyimide resin adhesive film obtained by coating and drying at a maximum drying temperature of 300 ° C. was stretched by tension, and its X-ray diffraction measurement and tensile breaking strength were measured. Table 1 shows the measurement results.

[0016]

[Table 1]

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction chart of a polyimide resin film before being exposed to a high temperature.

FIG. 2 is an X-ray diffraction chart of a polyimide resin film after being exposed to a high temperature.

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Claims (1)

[Claims] 1. After solidifying on one or both surfaces of a polyimide resin film which does not melt at a temperature of 400 ° C. or less,
The polyimide resin adhesive film obtained by coating and drying a polyimide resin adhesive varnish that can be thermally melted at a temperature of 00 ° C. or less is applied to obtain a 0.75 kg / mm or more and 1.75 K
A method for producing a polyimide resin adhesive film, wherein the film is stretched by a tension of not more than g / mm.