JP3664255B2 - Adhesive polyimide - Google Patents

Description

  The present invention relates to an adhesive polyimide used for bonding a polyimide film and a metal or a substrate, which is useful for molding an electronic component or a flexible printed circuit board that requires heat resistance.

  In order to maintain the reliability of the flexible printed circuit board as an electronic device, it is required that the adhesive force between the polyimide product, in particular, the polyimide film product and the substrate does not decrease. Conventionally, as a method for improving the adhesion between a polyimide film and a substrate, plasma treatment, coupling treatment, and the like are known as disclosed in JP-A-5-279497. However, there are problems such as high cost and low productivity in plasma processing, and when trying to perform coupling processing, parts that do not require coupling processing, such as contact holes (adhesion holes between upper and lower wiring), There remains a problem that the coupling layer remains in the bonding butt (connection hole between the lead wire and the wiring) and the contact resistance increases, and it is difficult to put the surface treatment by the coupling treatment into practical use.

  As disclosed in JP-A-63-99282, an alkali treatment method is known as a polyimide surface treatment method. However, the polyimide film known as Upilex (manufactured by Ube Industries, Ltd.) is composed of biphenyltetracarboxylic acid and 1,4-diaminobenzene. In this alkali treatment method, adhesiveness cannot be obtained effectively and an appropriate treatment method is obtained. is not.

  As for the bonding method, epoxy adhesives and acrylic adhesives are mainly used, but there are problems with heat resistance, chemical resistance, etc., and there is a bonding method using polyimide adhesive with high heat resistance. It has been demanded.

Japanese Patent Laid-Open No. 5-279497 JP-A 63-99282

  Kapton (Toray DuPont Co., Ltd.) is newly proposed for bonding the above surface-treated polyimide, especially polyimide film, and metal, ceramic or polyimide substrate. By modifying the surface properties of polyimide films known as company products), apical (product of Kaneka Chemical Co., Ltd.), upilex (product of Ube Industries Co., Ltd.), etc. with a simple chemical method, It is an object of the present invention to provide an adhesive polyimide having a heat resistance effective for adhesion between the surface-treated polyimide film and a metal or other substrate while significantly improving the adhesion between the metal or other substrate.

  The present invention provides an oligomer of a polyimide compound containing bicyclo (2,2,2) oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and 3,5-diaminobenzoic acid as components. Next, an adhesive comprising a solvent-soluble block polyimide compound copolymerized by adding 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride and 1,3-bis- (3-aminophenoxy) benzene A functional polyimide is provided.

  By treating the polyimide surface with a mixed solution of ethanolamine and N-methylpyrrolidone or dimethylformamide, the adhesion between the polyimide film and the copper foil was remarkably improved. Furthermore, a specific copolymer polyimide containing bicyclo (2,2,2) oct-7-ene-2,3,5,6-tetracarboxylic dianhydride as a component is used for adhesion of the surface-treated polyimide film. And there was a remarkable effect on the adhesion between the surface-treated polyimide film and the copper foil.

  A polyimide surface treatment method suitable for applying the adhesive polyimide of the present invention will be described. After immersing the polyimide film in a mixed solution of ethanolamine and N-methylpyrrolidone or dimethylformamide, the immersed polyimide film is washed with water and dried. The composition ratio of the mixed solution of ethanolamine and N-methylpyrrolidone and / or dimethylformamide is ethanolamine: N-methylpyrrolidone and / or dimethylformamide in a weight ratio of 2:98 to 60:40, preferably 5:95 to 40:60 is effective. The immersion treatment time between the polyimide film requiring surface treatment and the ethanolamine / N-methylpyrrolidone and / or dimethylformamide mixed solution is the mixing ratio or mixing of ethanolamine and N-methylpyrrolidone or dimethylformamide. Although depending on the immersion treatment temperature with a solution, for example, when the immersion treatment temperature with a mixed solution is an N-methylpyrrolidone solution of ethanolamine (concentration 20%) at room temperature, 0.2 to 40 minutes, preferably 0. 5 to 30 minutes is effective. Furthermore, in the case of a dimethylformamide solution of ethanolamine (concentration 20%) and the immersion treatment temperature by the mixed solution is room temperature, 0.5 to 40 minutes, preferably 1 to 30 minutes is effective.

  In general, when the ethanolamine concentration is low, the immersion treatment time becomes long. Further, when the immersion treatment temperature is increased, the treatment time is shortened. Moreover, when this immersion process temperature is higher than room temperature, you may add a fixed amount of water in this mixed solution. This mixed solution is usually heated to a temperature range of room temperature to 90 ° C., and the polyimide film is brought into contact with the immersion treatment for about 0.5 to 30 minutes, then washed with water and dried. The contact method between the polyimide film and the mixed solution is not limited to the above immersion treatment method, and brushing, printing, spraying, and the like are also possible.

  Furthermore, bicyclo (2,2,2) oct-7-ene-2,3,5,6-tetracarboxylic is preferable as a preferable adhesive for bonding the surface of the polyimide film surface-treated by the above method to a metal or a substrate. The adhesive polyimide of the present invention comprising a specific polyimide compound containing an acid dianhydride as a component can be used. In this case, when bonding the surface-treated polyimide film and the metal or other substrate, a polyimide adhesive is placed between the surface-treated polyimide film surface and the metal or the substrate, and 150 ° C. to 400 ° C., preferably This is accomplished by thermocompression bonding at 150 ° C to 350 ° C.

  The adhesive polyimide of the present invention is a polyimide compound containing bicyclo (2,2,2) oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and 3,5-diaminobenzoic acid as components. Next, a solvent-soluble block polyimide was copolymerized by adding 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride and 1,3-bis- (3-aminophenoxy) benzene It is an adhesive polyimide made of a compound. A general method for producing a solvent-soluble block polyimide compound is described in US Pat. No. 5,502,143.

  The polyimide adhesive containing the adhesive polyimide of the present invention is preferably a solution in which the block copolymerized polyimide is dissolved in a polar solvent, particularly N-methylpyrrolidone, at a concentration of 10-30%. This polyimide adhesive solution is applied on the surface-treated polyimide film and dried by heating at 250 ° C. or lower, preferably 150-200 ° C. The polyimide coating film preferably has a coating thickness of 5-30 microns. This polyimide adhesive is brought into contact with a coated polyimide film with a metal foil, such as a copper foil, a stainless steel plate, an aluminum plate, a nickel plate or the like, and subjected to thermocompression bonding.

  It is also possible to apply this polyimide adhesive to a metal foil, such as a copper foil, a stainless steel plate, an aluminum plate, or a nickel plate. It is also possible to apply this polyimide adhesive on both surfaces of the polyimide film and on the surface of a metal foil such as a copper foil, a stainless steel plate, an aluminum plate, or a nickel plate. Usually, the thermocompression bonding temperature is 150-400 ° C., preferably 150-350 ° C., and the adhesion time is about 5-60 minutes. In this case, it is also possible to use a polyimide adhesive film having the above composition instead of the polyimide adhesive.

Example 1
A 2 liter capacity three-necked separable flask is equipped with a stainless steel Ikari-type stirrer, a nitrogen gas inlet tube and a reflux condenser with a balled cooling tube on a trap with a stopcock. Reacted in.

  Bicyclo (2,2,2) octo-7-ene-2,3,5,6-tetracarboxylic dianhydride 44.9 g (200 mmol), 3,5-diaminobenzoic acid 15.22 g (100 mmol) Then, 3.0 g (30 mmol) of gamma-valerolactone, 3.6 g (40 mmol) of pyridine, 300 g of N-methylpyrrolidone and 60 g of toluene were added. The mixture was reacted at 180 ° C. (bath temperature) for 1 hour while passing nitrogen gas. Toluene and water azeotropes were removed. In this reaction solution, 29.4 g (100 mmol) of 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride and 58.46 g (200 mmol) of 1,3-bis- (3-aminophenoxy) benzene were added. ), N-methylpyrrolidone (268 g) and toluene (40 g) were added, and the mixture was reacted at room temperature for 1 hour while passing nitrogen gas. Subsequently, it reacted at 180 degreeC (bath temperature) for 3 hours, removing the azeotrope of toluene and water. The polymerized polyimide had a number average molecular weight of 58,900 and a weight average molecular weight of 95,000 in terms of polystyrene. This polyimide had a glass transition temperature of 213 to 226 ° C. and a thermal decomposition start temperature of 422 ° C.

Reference example A
A polyimide solution was synthesized by the same operation as in Example 1. A 2 liter capacity three-necked separable flask is equipped with a stainless steel Ikari-type stirrer, a nitrogen gas inlet tube and a reflux condenser with a balled cooling tube on a trap with a stopcock. React in. 2,9.4 g (100 mmol) of 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride, dicyclo (2,2,2) oct-7-ene-2,3,5,6-tetracarboic acid dihydrate 29.42 g (100 mmol) of anhydride, 58.46 g (200 mmol) of 1,3-bis- (3-aminophenoxy) benzene, 2.0 g (20 mmol) of gamma valerolactone, 2.4 g (30 mmol) of pyridine 422 g of N-methylpyrrolidone and 60 g of toluene are added. This was reacted at 180 ° C. (bath temperature) for 4 hours while passing nitrogen gas.

  Subsequently, it reacted at 180 degreeC (bath temperature) for 3 hours, removing the azeotrope of toluene and water. The polymerized polyimide had a polystyrene equivalent molecular weight of 55,000 in terms of number average molecular weight and 85,000 in terms of weight average molecular weight. This polyimide had a glass transition temperature of 210-220 ° C. and a thermal decomposition starting temperature of 451 ° C.

Reference example 1
A polyimide solution was synthesized by the same operation as in Example 1. A 2 liter capacity three-necked separable flask is equipped with a stainless steel Ikari-type stirrer, a nitrogen gas inlet tube and a reflux condenser with a balled cooling tube on a trap with a stopcock. React in. 29.78 g (120 mmol) of bicyclo (2,2,2) oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 36.04 g (180 mmol) of 3,4'-diamino-diphenyl ether ), 3.0 g (30 mmol) of gamma-valerolactone, 3.2 g (40 mmol) of pyridine, 200 g of N-methylpyrrolidone and 100 g of toluene. The mixture was reacted at 180 ° C. (bath temperature) for 1 hour while passing nitrogen gas. Toluene and water azeotropes were removed.

  In this reaction liquid, 3,4,3 ′, 4′-benzophenonetetracarboxylic dianhydride 58.00 g (180 mmol) and 1,3-bis- (3-aminophenoxy) benzene 37.59 g (128. 6 mmol), 202 g of N-methylpyrrolidone and 40 g of toluene were added and reacted at room temperature for 1 hour while passing nitrogen gas. Next, 0.84 g (8.57 mmol) of 5-norbornene-2,3 dicarponic acid dianhydride and 50 g of N-methylpyrrolidone were added, and the mixture was reacted at room temperature for 0.5 hours while passing nitrogen gas. The mixture was heated at 180 ° C. (bath temperature) for 4 hours, 150 g of N-methylpyrrolidone was added, and the reaction was carried out for 2.5 hours while removing the azeotrope of toluene and water. The polymerized polyimide had a number average molecular weight of 33,400 and a weight average molecular weight of 106,100 in terms of polystyrene. The glass transition temperature of this polyimide was 215-243 ° C.

Reference Example 2-16
After immersing a polyimide film (Ube Industries, Ltd .: Upilex-S: 200 mm × 200 mm × 50 μm thickness) in a mixed solution of ethanolamine (5 wt%) and N-methylpyrrolidone (95 wt%) at room temperature for 20 minutes The immersed polyimide film was sufficiently washed with ion-exchanged water and dried at 90 ° C. for 20 minutes in a warm air dryer. This surface-treated polyimide film is indicated by film number F-1 (Table 1).

  Polyimide film numbers F-2 to F- treated in the same manner as above with a mixed solution in which the mixing ratio of ethanolamine, N-methylpyrrolidone and water or dimethylformamide was changed as shown in Reference Example 3-16 below. 15 was created (Tables 1 and 2). An untreated polyimide film that was not subjected to any surface treatment was designated as F-00 (Reference Example 12).

Reference Examples B to H , Reference Examples 17 to 24
A polyimide adhesive dissolved in N-methylpyrrolidone on a copper foil (3EC-HTE: 35 micron thickness) manufactured by Mitsui Mining & Smelting Co., Ltd. (in Reference Examples B to H , the polyimide solution of Reference Example A , Reference In Example 17-20, the polyimide solution of Reference Example 1 was used, and heated at 140 ° C. for 20 minutes to scatter N-methylpyrrolidone as a solvent. The thickness of the polyimide adhesive layer applied to the copper foil after the drying treatment was 12 microns.

The copper foil coated with the polyimide adhesive and the surface-treated films shown in Tables 1 and 2 are overlapped in a planar shape with the coated polyimide adhesive interposed therebetween, and 50 kg at 285 ° C. for 5 minutes using a hot press. Heat / pressure adhesion was performed at / cm ² .

  The bonded polyimide film / copper foil sample was cut into a strip of 10 mm × 70 mm, and the peel strength was measured using a tensile / compression tester (manufactured by Imada Seisakusho: SV-55 type). Table 3 below shows the measurement results of the 180 degree peel strength of the polyimide film / copper foil surface of each film. By performing the film surface treatment and using the adhesive polyimide of the present invention as an adhesive, the adhesive strength (peeling strength) between the polyimide film (Upilex film) and the copper foil is remarkably improved.

Reference Example 25-29
In a mixed solution of ethanolamine (5% by weight) and N-methylpyrrolidone (95% by weight) at room temperature, a polyimide film (manufactured by Toray DuPont Co., Ltd .: Kapton / 200 mm × 200 mm × 50 microns thickness) was immersed for 20 minutes, The immersed polyimide film was sufficiently washed with ion-exchanged water and dried at 90 ° C. for 20 minutes in a warm air dryer. This surface-treated polyimide film is indicated by film number F-16 (Table 4).

  Polyimide film numbers F-16 to F-19 treated in the same manner as described above with a mixed solution in which the mixing ratio of ethanolamine and N-methylpyrrolidone or dimethylformamide was changed as shown in Reference Example 25-28 below. Created (Table 4). An untreated polyimide film that was not subjected to any surface treatment was designated as F-20 (Reference Example 29).

Examples 2 to 6
A polyimide adhesive dissolved in N-methylpyrrolidone on a copper foil (3EC-HTE: 35 micron thickness) manufactured by Mitsui Mining & Smelting Co., Ltd. (Example 10-14 uses the polyimide solution of Example 1) ) And heated at 140 ° C. for 20 minutes to disperse the solvent N-methylpyrrolidone. The thickness of the polyimide adhesive layer applied to the copper foil after the drying treatment was 12 microns. Table 5 below shows the measurement results of the 180 ° peel strength of the polyimide film / copper foil surface of each film prepared according to the immersion treatment conditions of Reference Examples 25-29. By performing the surface treatment and using the adhesive polyimide of the present invention as an adhesive, the adhesive strength (peeling strength) between the polyimide film (Kapton film) and the copper foil is remarkably improved.

Claims (1)

  An oligomer of a polyimide compound containing bicyclo (2,2,2) oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and 3,5-diaminobenzoic acid as components is prepared, and then 3 , 4,3 ′, 4′-biphenyltetracarboxylic dianhydride and 1,3-bis- (3-aminophenoxy) benzene are added and copolymerized to form a solvent-soluble block polyimide compound.