JPH0412897B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for adhering polyimide molded products, and more particularly to a method for adhering polyimide molded products that provides a laminate with excellent adhesive strength.

[Conventional technology]

Polyimide molded products, especially polyimide films, are widely used as electrical insulating materials. For example, flexible wiring boards are manufactured by bonding polyimide film to metal foil such as copper foil, and acrylic adhesives are used as adhesives as disclosed in Japanese Patent Application Laid-Open No. 50-34640. Ta. However, acrylic adhesives have low heat resistance and do not take full advantage of polyimide film's inherent heat resistance. Therefore, in order to take advantage of the heat resistance of polyimide film, polyimide adhesives were developed (see, for example, Japanese Patent Laid-Open No. 60755/1983). However, polyimide adhesives generate water during ring closure, requiring complicated and long drying times, and have drawbacks such as low peel strength due to high elastic modulus. In order to improve the adhesive strength, attempts have been made to mechanically roughen the surface of the polyimide film by sandblasting or the like, or to perform plasma treatment (Japanese Unexamined Patent Publication No. 59-21878). However, mechanical roughening does not provide sufficient adhesion, and plasma treatment, although somewhat effective, requires expensive equipment and also has the disadvantage that the treatment effect deteriorates in a short period of time. On the other hand, as shown in Japanese Patent Publication No. 52-36778, there is a method in which a polyimide film is treated with an alkali and then treated again with a metal salt that has a smaller ionization tendency than an alkali metal. Although it is effective for certain polyimide adhesives, it has drawbacks such as insufficient effectiveness for many other polyimide adhesives.

[Problem that the invention seeks to solve]

The present invention eliminates the drawbacks of the prior art as described above,
The present invention aims to provide a method for joining polyimide molded products that can obtain sufficient adhesive strength.

[Means for solving problems]

The joining method for polyimide molded products of the present invention involves first treating the surface with a solution containing a basic compound, then treating it with a silane coupling agent, and then attaching a heat-meltable polyimide sheet to the treated surface of the heat-treated polyimide molded product. It is characterized by stacking a layer of adhesive, placing an arbitrary adherend on top of it, and pressing and heating it at a temperature above the softening point of the adhesive.

The polyimide molded product used in the method of the present invention may be anything other than a film, such as a flexible printed wiring board, a laminate, etc., as long as the polyimide resin is exposed on the surface. Further, the polyimide may be one containing an imide structure, such as polyamideimide, polyetherimide, polyesterimide, or the like.

The basic compounds used in the method of the present invention include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, and tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide. Quaternary ammonium hydroxide is preferred, and potassium hydroxide and sodium hydroxide are particularly preferred.

Preferred solvents for dissolving the basic compound include water, alcohols such as methanol, ethanol, propanol, and isopropanol, and mixed solvents of water and alcohol.

The concentration of the basic compound in the solution containing the basic compound and the temperature and time for treating the polyimide molded article are determined depending on the desired degree of treatment, and are not particularly limited, but generally the concentration is between 0.1 and 50% by weight. %,
The temperature is room temperature to 80°C, and the time is 0.1 minute to 1 hour. The surface treatment of a polyimide molded article with a solution containing this basic compound can be carried out, for example, by immersing the polyimide molded article in the solution, or by using an applicator,
Any known method may be used, such as casting using a doctor knife or the like. After treatment with a solution containing a basic compound and before treatment with a silane coupling agent, treatment with an acid solution such as hydrochloric acid, sulfuric acid, or acetic acid may be performed.

Silane coupling agents used in the method of the present invention include vinylsilanes such as vinyltrimethoxysilane, epoxysilanes such as γ-glycidoxypropyltrimethoxysilane, mercaptosilanes such as γ-mercaptopropyltrimethoxysilane,
γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ
-aminopropylmethyldimethoxysilane, γ-
ureidopropyltriethoxysilane, N-benzyl-γ-aminopropyltrimethoxysilane,
Aminosilanes such as aminoethylaminomethylphenethyltrimethoxysilane, p-aminophenyltrimethoxysilane, trimethoxysilylpropyldiethylenetriamine, and 1-trimethoxysilyl-2-(aminomethyl)phenylethane are used, among which Mercaptosilane and aminosilane are preferred, and γ-mercaptopropyltrimethoxysilane and γ-aminopropylethoxysilane are particularly preferred.

Treatment with a silane coupling agent is carried out after treatment with a solution containing a basic compound, and the treatment method includes, for example, immersing a polyimide molded article in a silane coupling agent solution, or using an applicator, doctor knife, etc. Casting coating, etc.
Any known method may be used.

The solvent for dissolving the silane coupling agent may be any solvent as long as it dissolves the silane coupling agent, such as water, alcohol, acetone, ethyl acetate, toluene, etc., and water, alcohol, and acetone are particularly preferred.

The concentration of the silane coupling agent in the silane coupling agent solution is not particularly limited, but is from 0.01 to
30% by weight is preferred, and 0.1-5% by weight is particularly preferred. If the concentration is less than 0.01% by weight, the effect of the silane coupling agent treatment will be poor, and if it exceeds 30% by weight, the effect will be weak. There are no particular restrictions on the temperature or time of the treatment, but generally it is sufficient to immerse it at room temperature for 0.5 to 10 minutes, or to leave it for 0.5 to 10 minutes at room temperature after application.

After treatment with the silane coupling agent, heat treatment is performed, but the temperature and time of the heat treatment must be at least conditions that can dry the solvent of the silane coupling agent solution, and generally at a temperature of 80°C or higher for 1 to 60 minutes. It is preferable to do so. Particularly preferably 150-250℃
Do this for 5 to 20 minutes at a temperature of .

Next, a heat-meltable polyimide sheet adhesive and an adherend are sequentially stacked on the treated surface of the polyimide molded product treated as described above and heated under pressure, thereby achieving strong adhesion.

The heat-meltable polyimide sheet adhesive that can be used in the present invention may be a film made of resin alone, or may be a resin-impregnated base material such as glass cloth or aramid cloth. The polyimide may be one containing an imide structure such as polyamideimide, polyesterimide, polyetherimide, etc., and preferably has a softening point of 400°C or less.

The adherend may be anything, including polyimide molded products, metal foils such as copper foil and aluminum foil, metal plates such as copper plates, iron plates, aluminum plates, stainless steel plates, and 42 alloy plates.

Adhesion conditions vary depending on the physical properties of the sheet adhesive used, but generally the temperature is above the softening point of the adhesive, preferably above the softening point of the adhesive and below the thermal decomposition start temperature, and the pressure is 0.1 kg. /cm ³ to 100Kg/cm ³ . This bonding method is not particularly limited, but can be carried out, for example, by stacking an arbitrary adherend on the adhesive layer and heating and pressurizing it in roll lamination, press, or autoclave.

〔Example〕

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the scope of the present invention is not limited in any way by these Examples.

Example 1 Kapton 200H (manufactured by DuPont, 50 μm polyimide film) was immersed in a 30% potassium hydroxide aqueous solution for 10 minutes at room temperature, and then washed with water. Next, it was immersed in a 1% acetone solution of γ-aminopropyltriethoxysilane for 30 seconds at room temperature, and then dried at 200°C for 10 minutes.

On the other hand, 64.4 g of 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 12.2 g of m-tolylenediamine, bis[4-(3-aminophenoxy)
After dissolving 43.2 g of phenyl]sulfone in 480 g of N-methylpyrrolidone and heating at 180°C for 6 hours,
N,N'-diphenylmethane bismaleimide 11.3g
was dissolved to obtain polyimide varnish. The concentration of polyimide in the varnish was 20% by weight. The obtained varnish was cast onto a glass plate, dried at 80℃ for 10 minutes, peeled off from the glass plate, fixed on an iron frame, and heated at 200℃ for 10 minutes.
After drying for several hours, a polyimide adhesive film was obtained. A polyimide adhesive film and a 35 μm single-sided roughened copper foil were sequentially stacked on the surface of the Kapton surface treated above and pressed at 275° C. and 50 kg/cm ³ for 30 minutes to obtain a copper-clad substrate. The 90° peel strength between Kapton and polyimide adhesive on this copper-clad board was 0.83 kg/cm.

Comparative Example 1 A copper-clad substrate was obtained in the same manner as in Example 1 except that γ-aminopropyltriethoxysilane was not used. The 90° peel strength between the Kapton and polyimide adhesive of this copper-clad board was very weak at 0.04 kg/cm.

Comparative Example 2 Example 1 except that Kapton without any treatment was used
A copper-clad board was obtained in the same manner. The 90° peel strength between the Kapton and polyimide adhesive of this copper-clad board was very weak at 0.05 kg/cm.

Example 2 Kapton 200H was immersed in a 30% sodium hydroxide aqueous solution at room temperature for 30 minutes, and then washed with water. Next, it was immersed in a 1% acetone solution of γ-mercaptopropyltrimethoxysilane for 30 seconds, and then dried at 250°C for 10 minutes.
A laminate was obtained in the same manner as in Example 1 by sandwiching a polyimide adhesive film between the surface-treated Kapton. The 90° peel strength between Kapton's polyimide adhesives in this laminate was 0.80 kg/cm.

Example 3 A copper-clad substrate was obtained in the same manner as in Example 1, except that a 5% acetone solution of γ-mercaptopropyltrimethoxysilane was used instead of γ-aminopropyltriethoxysilane. The 90° peel strength between the Kapton and polyimide adhesive film of this copper-clad board was 0.94 kg/cm.

Comparative Example 3 A laminate was obtained in the same manner as in Example 2 except that it was not immersed in the potassium hydroxide solution. The 90° peel strength between Kapton and the polyimide adhesive film of this laminate was very weak at 0.04 kg/cm.

Example 4 Kapton 200H was immersed in a 10% sodium hydroxide aqueous solution at 40° C. for 20 minutes, and then washed with water. Next, it was immersed in a 1% acetone solution of γ-aminopropyltriethoxysilane for 1 minute at room temperature, and then dried at 200°C for 10 minutes. Polyimide prepreg I-67 or I-
68 (Hitachi Chemical Co., Ltd. product name) scissors and 170 each
A laminate was obtained by pressing under the conditions of 1.5 hours at 60 Kg/cm ² at 200°C and 2 hours at 40 Kg/cm ² at 200°C. The 90° peel strength between Kapton and prepreg in this laminate was 0.98 Kg/cm and 0.65 Kg/cm, respectively.

Example 5 A polyimide adhesive film prepared using equimolar amounts of 3,3',4,4'-benzophenonetetracarboxylic dianhydride and 3,3'-diaminodiphenyl ketone was used at 350°C and 30 kg. A laminate was obtained in the same manner as in Example 1, except that pressing was carried out under the conditions of /cm ² and 20 minutes. This laminate has caputo adhesive film between
The 90° peel strength was 0.75 kg/cm.

〔Effect of the invention〕

As described above in detail, according to the joining method of the present invention, a laminate of polyimide molded products having strong adhesive strength can be obtained, and its industrial value is great.

Claims (1)

[Claims] 1 After the surface is treated with a solution containing a basic compound, it is treated with a silane coupling agent, and then a heat-meltable polyimide sheet adhesive is layered on the treated surface of the heat-treated polyimide molded product, and any arbitrary A method for bonding polyimide molded products, which involves stacking adherends and applying pressure and heating at a temperature above the softening point of the adhesive.