JP2005045236A - Inorganic thin film pattern forming method of polyimide resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inorganic thin film pattern forming method of a polyimide resin which can makes an inorganic thin film with high adhesion reliability and high pattern accuracy be formed on a polyimide resin surface. <P>SOLUTION: This method comprises (1) a step of cleaving an imido ring of the polyimide resin to produce a carboxyl group, by applying an alkali solution on an inorganic thin film formation portion of the polyimide resin, (2) a step of producing a metal salt with the carboxyl group by contacting a solution containing a metal ion to the polyimide resin with the carboxyl group, and (3) a step of forming the inorganic thin film by making the metal salt be deposited on a surface of the polyimide resin as a metal, a metal oxide, or a semiconductor. The inorganic thin film is formed on the surface of polyimide resin through these steps. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method of forming an inorganic thin film with a fine pattern such as a circuit pattern on the surface of a polyimide resin.

Various methods have been proposed as a method of forming a circuit pattern on the surface of a substrate formed of a polyimide resin such as a polyimide film. Among them, dry processes such as a vacuum deposition method and a sputtering method are known as methods that can satisfactorily form a fine circuit pattern with excellent adhesion reliability. However, these methods are expensive devices. Therefore, the most common circuit pattern forming method is to coat the entire surface of the polyimide resin substrate with a metal film in advance. A subtractive method is widely used in which a covering material is produced and an unnecessary portion of a metal film is removed by etching using a photolithographic method. The adhesion force between the polyimide resin base material and the metal film in the metal coating material is ensured by an anchor effect accompanying the roughening of the surface of the base material or an adhesive. This subtractive method is excellent in productivity and is a method useful for forming a circuit pattern relatively easily. However, since it is necessary to remove a large amount of a metal film when forming a circuit pattern, a metal material is used. There is a problem that a lot of waste occurs. In addition, in recent years, finer circuit patterns have been demanded as electronic circuit boards have increased in density. However, in the subtractive method, unevenness and adhesive due to the occurrence of overetching and roughening of the surface of the base material are required. There is also a problem that it is difficult to cope with the required fine circuit pattern formation due to the presence of the above.

  For this reason, circuit pattern formation methods that replace the subtractive method have been actively studied. For example, the additive method, which is a type of photolithographic method, covers a portion of the substrate surface other than the circuit formation site with a mask such as a photocurable resin, and directly forms a circuit pattern on the substrate surface using an electroless plating method. It is a method to do. The electroless plating method uses a redox reaction in a solution to form a metal film on the surface of a substrate provided with plating catalyst nuclei. This additive method has superior productivity compared to the dry process described above, and can form a fine circuit pattern compared to the subtractive method. Since it is difficult to ensure, there is a problem that adhesion reliability is poor. In addition, the additive method has a complicated process and requires expensive production equipment to form a fine circuit pattern, resulting in high costs.

  Further, an ink jet method has attracted attention as a method for forming a fine circuit pattern easily and inexpensively. In the inkjet method, ink composed of metal nanoparticles is sprayed onto the surface of a substrate in a pattern shape from an inkjet nozzle, applied, and then annealed to form a circuit pattern consisting of a fine metal film. Is. However, when metal nanoparticles are sprayed and applied by the inkjet method, if the number of metal nanoparticles per unit area of the surface of the substrate is insufficient, the shrinkage caused by sintering between the metal nanoparticles during annealing The resulting metal film may break, and conversely, if the number of metal nanoparticles is excessive, the surface smoothness of the metal film formed after annealing may be lost. There is a problem that the control of the coating amount of particles is extremely severe. In addition, it is difficult to obtain sufficient adhesion reliability due to the physical properties of the metal component of the base material and the metal nanoparticles, and further, there is a problem in dimensional accuracy due to shrinkage accompanying sintering between the metal nanoparticles during annealing. Is.

In recent years, as a circuit pattern forming technique having excellent adhesion reliability, the surface of a polyimide resin substrate is treated with an alkaline aqueous solution to generate a carboxyl group, and a metal ion is coordinated to the carboxyl group to form a carboxyl group metal. After forming the salt, the polyimide resin base material is irradiated with ultraviolet rays through a photomask to selectively reduce metal ions to deposit a metal film, and if necessary, deposit the metal film by plating. A technique for increasing the film thickness has been proposed (see, for example, Patent Document 1). A part of the metal film formed by this method is embedded in the polyimide resin, and the adhesion reliability of the metal film to the substrate surface of the polyimide resin can be high. However, as in the invention of Patent Document 1, it is difficult for the pattern forming method by ultraviolet irradiation through a photomask to cope with an extremely fine circuit pattern that is desired as the density of the circuit board increases.
JP 2001-73159 A

  The present invention has been made in view of the above points, and an object of the present invention is to provide a polyimide resin inorganic thin film pattern forming method capable of forming an inorganic thin film on a polyimide resin surface with high adhesion reliability and pattern accuracy. Is.

  In the method for forming an inorganic thin film pattern of a polyimide resin according to claim 1 of the present invention, when forming an inorganic thin film on the surface of the polyimide resin, (1) an alkaline aqueous solution is applied to the inorganic thin film forming portion of the polyimide resin, A step of cleaving an imide ring to generate a carboxyl group, (2) a step of bringing a metal ion-containing solution into contact with the polyimide resin having a carboxyl group to generate a metal salt of a carboxyl group, and (3) a metal salt of the metal salt. Or as a metal oxide or a semiconductor, and depositing on a polyimide resin surface to form an inorganic thin film.

  According to the present invention, an inorganic thin film can be formed by selectively depositing a metal, a metal oxide or a semiconductor on an inorganic thin film forming portion of a polyimide resin coated with an alkaline aqueous solution, and using a photomask or the like. There is no need to form an inorganic thin film with high adhesion reliability and high pattern accuracy.

  The invention of claim 2 is characterized in that, in the step (1) of claim 1, an alkaline aqueous solution is applied to the inorganic thin film forming portion of the polyimide resin by an ink jet method.

  According to the present invention, the aqueous alkaline solution can be applied in a fine pattern using an ink jet method, and the inorganic thin film can be finely formed with high pattern accuracy.

  The invention of claim 3 is characterized in that, in the step (1) of claim 1, an alkaline aqueous solution is applied to an inorganic thin film forming portion of the polyimide resin by a transfer method.

  According to this invention, the alkaline aqueous solution can be applied in a fine pattern using a transfer method, and the inorganic thin film can be finely formed with high pattern accuracy.

  The invention of claim 4 is the step (1) of claim 1, wherein after forming an alkali-resistant protective layer on a portion other than the polyimide resin inorganic thin film forming portion, an aqueous solution of the polyimide resin is applied. An alkaline aqueous solution is brought into contact with the inorganic thin film forming site.

  According to the present invention, the alkaline aqueous solution can be applied only to a desired inorganic thin film formation site, and an inorganic thin film can be formed in a desired pattern.

  According to a fifth aspect of the present invention, in the step (3) of forming the inorganic thin film according to any one of the first to fourth aspects, the metal salt is deposited on the surface of the polyimide resin as a metal by reducing the metal salt. Thus, this is a process for forming a metal thin film.

  According to the present invention, a metal thin film can be formed at an inorganic thin film forming site, and by forming a circuit pattern with the metal thin film, it can be used as an electronic circuit board based on a polyimide resin. is there.

  According to a sixth aspect of the present invention, in the step (3) of forming the inorganic thin film according to any one of the first to fourth aspects, the metal salt is reacted with an active gas to convert the metal salt into a metal oxide or semiconductor. It is a step of forming a metal oxide thin film or a semiconductor thin film by depositing on the polyimide resin surface.

  According to this invention, a metal oxide thin film or a semiconductor thin film can be formed at an inorganic thin film forming site, and can be used as various electronic components having a metal oxide thin film or a semiconductor thin film.

  The invention of claim 7 is characterized in that, in the step (3) of any of claims 1 to 6, the deposited inorganic thin film is composed of an aggregate of inorganic nanoparticles.

  According to this invention, the anchoring effect of the inorganic nanoparticle aggregate can be utilized to increase the adhesion strength of the inorganic thin film, and the catalytic activity of the inorganic nanoparticle aggregate can be utilized to Electroless plating can be easily performed on the surface.

  The invention of claim 8 is characterized in that in the step (3) of claim 7, a part of the aggregate of inorganic nanoparticles is embedded in a polyimide resin.

  According to this invention, the inorganic thin film which consists of an aggregate | assembly of an inorganic nanoparticle can be firmly stuck to a polyimide resin by the anchor locking effect with respect to a polyimide resin.

  The invention of claim 9 is characterized in that after the step (3) of any one of claims 1 to 8, there is a step of (4) applying electroless plating to the polyimide resin surface on which the inorganic thin film is deposited. To do.

  According to this invention, the electroless plating film can be increased on the surface of the inorganic thin film to increase the thickness of the inorganic thin film, and the circuit of the electronic circuit board can be formed with the inorganic thin film.

  The invention of claim 10 is characterized in that, in the step (4) of claim 9, electroless plating is performed using an aggregate of inorganic nanoparticles as a plating precipitation nucleus.

  According to this invention, the electroless plating can be selectively deposited on the surface of the inorganic thin film by depositing the electroless plating on the surface of the inorganic thin film composed of the aggregate of inorganic nanoparticles. In increasing the film thickness, the pattern accuracy can be maintained even after the film increase.

  The invention of claim 11 is characterized in that, in any one of claims 1 to 10, the inorganic thin film forming portion is a circuit pattern shape.

  According to this invention, a circuit can be formed with an inorganic thin film formed at an inorganic thin film forming site, and it can be used as an electronic circuit board or the like based on a polyimide resin.

  According to the present invention, an inorganic thin film can be formed by selectively depositing a metal, a metal oxide, or a semiconductor on an inorganic thin film forming portion of a polyimide resin coated with an alkaline aqueous solution, and using a photomask or the like. There is no need to form an inorganic thin film with high adhesion reliability and high pattern accuracy.

  Hereinafter, the best mode for carrying out the present invention will be described.

  Polyimide resin is a polymer having a cyclic imide structure in the main chain, and is obtained, for example, by imidizing polyamic acid. Heat resistance, chemical resistance, mechanical strength, flame resistance, electrical insulation It is a thermosetting resin with excellent properties. In the present invention, this polyimide resin film or molded plate can be used as a substrate, and there is no particular limitation on the form.

  In the present invention, first, in step (1), an alkaline aqueous solution is applied to the surface of the polyimide resin substrate. The alkali concentration of the aqueous alkali solution is preferably 0.01 to 10M, more preferably 0.5 to 6M. Although it does not restrict | limit especially as aqueous alkali solution, A potassium hydroxide aqueous solution, sodium hydroxide aqueous solution, calcium hydroxide aqueous solution, magnesium hydroxide aqueous solution, and ethylenediamine aqueous solution are preferable. In this alkaline aqueous solution, an auxiliary agent selected from a binder resin, an organic solvent, an inorganic filler, a thickener, a leveling agent, and the like is added to control viscosity, wettability with a polyimide resin substrate, smoothness, and volatility. be able to. These are preferably selected according to the shape and line width of the coating pattern.

  In the present invention, the application of the alkaline aqueous solution to the polyimide resin substrate is carried out selectively in a desired pattern shape only at the inorganic thin film forming site. Here, when an alkaline aqueous solution is applied to the surface of the polyimide resin base material, as described in Patent Document 1, carboxyl cleavage occurs due to cleavage of the imide ring in the molecular structure of the polyimide resin as seen in Chemical Reaction Formula 1. A group (—COOA: alkali metal salt or alkaline earth metal salt of carboxylic acid) and an amide bond (—CONH—) are formed.

  Therefore, the alkaline aqueous solution 2 is partially applied to the surface of the polyimide resin base material 1 in a pattern shape, and the alkaline aqueous solution 2 is applied only to the inorganic thin film forming portion on the surface of the polyimide resin base material 1 as shown in FIG. A modified layer in which carboxyl groups are generated on the surface of the polyimide resin base material 1 as shown in FIG. 3 is formed in a pattern shape.

  Here, as the alkaline aqueous solution 2 partially applied to the surface of the polyimide resin base material 1 penetrates into the surface of the polyimide resin base material 1 as described above, the modification of the polyimide resin that generates a carboxyl group proceeds. Therefore, the thickness of the modified layer 3 can be increased by increasing the standing time after applying the alkaline aqueous solution 2 or by heat-treating the polyimide resin substrate 1. is there. 10-80 degreeC is preferable and the processing temperature at the time of apply | coating the aqueous alkali solution 2 to the surface of the polyimide resin base material 1 is 15-60 degreeC more preferably. The treatment time is preferably 5 to 1800 seconds, more preferably 30 to 600 seconds.

  As described above, the selective application of the alkaline aqueous solution to the inorganic thin film forming portion of the polyimide resin substrate can be performed by, for example, an ink jet method. That is, an alkaline aqueous solution can be selectively applied to an inorganic thin film forming site by using an alkaline aqueous solution as an ink for an ink jet printing apparatus and spraying and applying the alkaline aqueous solution on the surface of the polyimide resin substrate in a desired pattern. It is. As the ink jet printing apparatus, either a thermal method or a piezo method can be used.

  Moreover, an alkaline aqueous solution can also be selectively applied to the inorganic thin film forming portion of the polyimide resin substrate by a transfer method. The transfer method is not particularly limited, and for example, an electrophotographic method or an offset printing method can be used. The electrophotographic method is formed by, for example, encapsulating an alkaline aqueous solution in a thermoplastic resin capsule using a known microcapsule method, and coating the surface of the microcapsule particle with a charge control agent, for example, an azo metal-containing complex. The powder can be used as a toner. The particle size of the powder is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm.

  Furthermore, after forming an alkali-resistant protective layer on a portion other than the portion where the inorganic thin film is formed on the surface of the polyimide resin base material, an alkaline aqueous solution is applied to the inorganic thin film forming portion of the polyimide resin base material by applying an alkaline aqueous solution. It can also be applied selectively. The alkali-resistant protective layer can be formed on the surface of the polyimide resin substrate by a photolithographic method, a screen printing method, a vapor deposition method, or the like. Specifically, as the alkali-resistant protective layer, a metal vapor-deposited film, titanium oxide, or the like. And metal oxide films such as tin oxide. Thus, after forming an alkali-resistant protective layer on the polyimide resin base material other than the inorganic thin film forming part, the alkali resistance is applied by applying an alkaline aqueous solution to the surface of the polyimide resin base material by spin coating or dipping. The alkaline aqueous solution can be selectively applied only to the inorganic thin film forming portion that is not covered with the protective layer and exposed.

  Here, when the alkali-resistant protective layer is formed by vapor deposition, at least one selected from gold, silver, aluminum, iron, tin, copper, titanium, nickel, tungsten, tantalum, cobalt, zinc, chromium, and manganese is used. An alkali resistant protective layer can be formed with the metal thin film contained. When the alkali-resistant protective layer is formed by a screen printing method, the alkali-resistant protective layer can be formed by printing a liquid resin containing at least one selected from an acrylic resin, a silicon resin, or a fluorine resin. Further, when the alkali-resistant protective layer is formed by photolithography, the alkali-resistant protective layer can be formed using, for example, a fluororesin for a lithography resist.

  As described above, after forming the modified layer 3 for generating a carboxyl group at the inorganic thin film forming site on the surface of the polyimide resin substrate 1 in the step (1), the surface of the polyimide resin substrate 1 in the step (2). Is treated with a metal ion-containing solution. In the metal ion-containing solution, the metal ions include gold ions, silver ions, copper ions, platinum ammine complexes, palladium ammine complexes, tungsten ions, tantalum ions, titanium ions, tin ions, indium ions, cadmium ions, titanium ions, vanadium. Examples thereof include at least one selected from ions, chromium ions, manganese ions, aluminum ions, iron ions, cobalt ions, nickel ions, and zinc ions. Among these metal ions, platinum ammine complexes and palladium ammine complexes are used in the state of an alkaline solution, and other metal ions are used in the state of an acidic solution.

Then, by treating the surface of the polyimide resin substrate 1 with the metal ion-containing solution in this way and bringing the metal ion-containing solution into contact with the modified layer 3 that has generated carboxyl groups as described above, for example, —COO ^{- ... M} 2+ ... ^- OOC-
As shown in FIG. 1C, a metal ion (M ²⁺ ) can be coordinated to the carboxyl group to form a metal salt of the carboxyl group (a metal salt of a carboxylic acid). The metal ion-containing modified layer 4 can be formed at three locations. Here, in order to promote the ligand exchange between the hydroxyl group, alkali metal or alkaline earth metal in the carboxyl group generated in the polyimide resin, and the metal ion, the hydroxyl group, alkali metal or alkaline earth metal The degree of dissociation needs to be increased. For this purpose, it is necessary to keep the polyimide resin substrate 1 in an acidic state. Therefore, in this case, it is preferable to use a metal ion-containing acidic solution as the metal ion-containing solution.

  The metal ion concentration in the metal ion-containing solution shows a close correlation with the ligand substitution reaction between the hydroxyl group, alkali metal or alkaline earth metal in the carboxyl group generated in the polyimide resin, and the metal ion. Although depending on the metal ion species, the metal ion concentration is preferably 1 to 1000 mM, more preferably 10 to 500 mM. A low metal ion concentration is not preferable because it takes time for the ligand substitution reaction to reach equilibrium. The contact time of the metal ion-containing solution to the surface of the polyimide resin substrate 1 is preferably 10 to 600 seconds, more preferably 30 to 420 seconds.

  As described above, in the step (2), the metal ion-containing modified layer 4 in which the metal ion-containing solution was brought into contact with the modified layer 3 of the polyimide resin substrate 1 to form a metal salt of a carboxyl group was formed. Thereafter, the surface of the polyimide resin substrate 1 is washed with water or alcohol to remove unnecessary metal ions. Then, in step (3), the metal salt of the metal ion-containing modified layer 4 is deposited as a metal, or deposited as a metal oxide or semiconductor, and the metal ion-containing modified layer of the polyimide resin substrate 1 is then deposited. As shown in FIG. 1 (d), an inorganic thin film 5 made of metal or an inorganic thin film 5 made of metal oxide or semiconductor can be formed on the surface 4.

  In the case where the metal salt is deposited as a metal on the metal ion-containing modified layer 4, it can be performed by reducing the metal salt. The reduction treatment can be performed, for example, by treating the surface of the polyimide resin substrate 1 with a solution containing a reducing agent, or by heat-treating the polyimide resin substrate 1 in a reducing gas or inert gas atmosphere. Although the reduction conditions vary depending on the metal ion species, when treating with a solution containing a reducing agent, for example, sodium borohydride, hypophosphorous acid and its salt, dimethylamine borane, etc. can be used as the reducing agent. When processing with a reducing gas, for example, hydrogen and its mixed gas, borane-nitrogen mixed gas or the like can be used as the reducing gas. When processing with an inert gas, for example, nitrogen gas or argon is used as the inert gas. Gas or the like can be used.

  Moreover, when depositing the metal salt of the metal ion containing modified layer 4 as a metal oxide or semiconductor, it can be performed by treating the metal salt with an active gas. Although the treatment conditions differ depending on the metal ion species, for example, oxygen and a mixed gas thereof, nitrogen and a mixed gas thereof, sulfur and a mixed gas thereof are used as the active gas, and the surface of the polyimide resin substrate 1 is brought into contact with the active gas. Thus, processing can be performed.

  Here, as the metal oxide, for example, titanium oxide, tin oxide, indium oxide, vanadium oxide, manganese oxide, nickel oxide, aluminum oxide, iron oxide, cobalt oxide, zinc oxide, barium titanate, strontium titanate, indium- Tin composite oxide, nickel-iron composite oxide, cobalt-iron composite oxide, etc. can be mentioned, and the inorganic thin film 5 made of metal oxide is thus formed on the surface of the polyimide resin substrate 1. By doing so, for example, it can be used as a capacitor, a transparent conductive film, a heat radiation material, a magnetic recording material, an electrochromic element, a sensor, a catalyst, a light emitting material, and the like.

  Examples of the semiconductor include cadmium sulfide, cadmium telluride, cadmium selenide, silver sulfide, copper sulfide, and indium phosphide. In this way, the inorganic thin film 5 made of a semiconductor is formed of a polyimide resin group. By forming on the surface of the material 1, it can be used as a light emitting material, a transistor, a memory material, and the like.

  As described above, the metal, metal oxide, or semiconductor constituting the inorganic thin film 5 formed in the step (3) is composed of nanoparticles having a particle diameter of 2 to 100 nm. These inorganic nanoparticles are easily aggregated due to their extremely high surface energy and exist as an aggregate of inorganic nanoparticles. At this time, a part of the aggregate of inorganic nanoparticles is stabilized in the resin of the polyimide resin substrate 1 although the degree varies depending on the conditions of the metal ion concentration, the reducing agent concentration, the atmospheric temperature, the active gas concentration, and the like. In other words, a part of the aggregate of inorganic nanoparticles is embedded in the surface portion of the polyimide resin, and is composed of the aggregate of the polyimide resin substrate 1 and the inorganic nanoparticles due to the anchor locking effect at this time. The inorganic thin film 5 can be firmly adhered. In particular, in the general anchor locking effect obtained by chemically or physically roughening the substrate surface, the surface roughness is on the order of μm. The anchor locking effect is excellent in adhesion characteristics with a surface roughness of nanoscale, and is suitable for a wiring material for transmitting an electronic signal in a high frequency region.

  The inorganic thin film 5 can be formed on the inorganic thin film forming portion of the polyimide resin substrate 1 as described above. By setting the inorganic thin film forming portion to a circuit pattern shape, the inorganic thin film 5 can be used as a circuit. A pattern can be formed and the polyimide resin base material 1 can be processed as an electronic component such as an electronic circuit board.

  Here, the inorganic thin film 5 formed in the step (3) has a thickness of about 10 to 500 nm. On the other hand, in an electronic circuit board, the circuit needs to have a thickness of about μ units. For this reason, when used as an electronic circuit board, it is preferable to increase the thickness of the inorganic thin film 5 so as to increase the thickness of the circuit. That is, after the step (3), in the step (4), electroless plating is performed on the surface of the inorganic thin film 5 provided on the polyimide resin substrate 1, and the thickness of the inorganic thin film 5 is increased by electroless plating. It is something that can be done.

  The electroless plating can be performed, for example, by immersing the polyimide resin substrate 1 in an electroless plating bath. The inorganic nanoparticle aggregate forming the inorganic thin film 5 is used as a deposition nucleus of plating. The electroless plating film 6 can be deposited on the surface of the inorganic thin film 5 as shown in FIG. That is, the aggregate of inorganic nanoparticles has an extremely large specific surface area, and thus exhibits excellent catalytic activity. When used as a precipitation nucleus for depositing the electroless plating film 6, from many points. Since the deposition of the plating film starts uniformly, the electroless plating film 6 exhibiting good adhesion and electrical characteristics can be obtained. In this way, by depositing the electroless plating film 6 on the surface of the inorganic thin film 5 using the inorganic nanoparticle aggregate as the deposition nucleus of the plating, the surface of the polyimide resin substrate 1 is selectively only on the surface of the inorganic thin film 5. The electroless plating film 6 can be formed on the inorganic thin film 5 and the circuit of the circuit can be formed after the film formation without using a mask or the like when the electroless plating film 6 is formed on the inorganic thin film 5 to form a circuit. The pattern accuracy can be maintained. The electroless plating bath is preferably a neutral or weak alkaline electroless plating bath in order to prevent re-modification of the polyimide resin substrate 1.

  Next, the present invention will be specifically described with reference to examples.

(Example 1)
An alkaline aqueous solution was prepared by adding 10 parts by mass of polyethylene glycol as a thickener to 100 parts by mass of a 5M KOH aqueous solution, and stirring and dissolving the resultant.

  On the other hand, a polyimide film (trade name “Kapton 200-H” manufactured by Toray DuPont Co., Ltd.) is immersed in an ethanol solution, subjected to ultrasonic cleaning for 5 minutes, and then dried in an oven at 100 ° C. for 60 minutes. The surface of the polyimide film was cleaned.

  The ink cartridge of the print head is filled with the alkaline aqueous solution, a circuit pattern having a line width of 50 μm is drawn on the surface of the polyimide film using a piezo ink jet printing apparatus, and the alkaline aqueous solution is applied for 10 minutes at room temperature. Left at rest. Thereafter, the polyimide film was immersed in an ethanol solution and subjected to ultrasonic cleaning for 10 minutes. The modified layer was formed in the circuit pattern shape on the surface of the polyimide film (refer FIG.1 (b)).

Next, a 50 mM CuSO ₄ aqueous solution is used as the metal ion-containing acidic solution, the polyimide film is immersed in this aqueous solution for 5 minutes, Cu ions are coordinated to the modified layer, and the metal ion-containing modified layer is formed. It formed (refer FIG.1 (c)). Thereafter, excess CuSO ₄ was removed with distilled water.

Next, a 5 mM NaBH ₄ aqueous solution was used as the reducing solution, and after immersing the polyimide film in this aqueous solution for 5 minutes and washing with distilled water, it was confirmed that a copper thin film was deposited on the surface of the metal ion-containing modified layer. (See FIG. 1 (d)). The thickness of the copper thin film was 300 nm, the line width was 50 μm, and the electrical resistance of the copper thin film was 5 × 10 ⁻³ Ωcm, and a circuit pattern having the same shape as the application shape of the alkaline aqueous solution could be formed.

  Thereafter, the polyimide film was immersed in a neutral electroless copper plating bath having the following bath composition whose temperature was adjusted to 50 ° C. for 3 hours.

CuCl ₂ : 0.05M
Ethylenediamine: 0.60M
Co (NO ₃ ) ₂ : 0.15M
Ascorbic acid: 0.01M
2,2′-bipyridyl: 20 ppm
pH: 6.75
The electroless copper plating film was deposited on the copper thin film, and a uniform copper plating film having a thickness of 4 μm was obtained. The electric resistance of the copper plating film was 3 × 10 ⁻⁵ Ωcm, and the circuit of the electronic circuit board could be formed with the copper thin film and the copper plating film (see FIG. 1 (e)).

(Example 2)
An aqueous alkaline solution was prepared by adding 30 parts by mass of polyvinylpyrrolidone and 15 parts by mass of glycerin as a thickener to 100 parts by mass of a 5M KOH aqueous solution, and stirring and dissolving them.

  Next, a circuit pattern having a line width of 15 μm is formed on the surface of the polyimide film, which is filled with the above alkaline aqueous solution in the ink cartridge of the print head and cleaned on the surface in the same manner as in Example 1 using a thermal ink jet printing apparatus. Drawing and standing at room temperature for 30 minutes. Thereafter, the polyimide film was immersed in a 1-propanol solution, subjected to ultrasonic cleaning for 10 minutes, and dried at 100 ° C. for 30 minutes. As a result, a modified layer having a circuit pattern shape was formed on the surface of the polyimide film (see FIG. 1B).

  Next, a 0.1 M concentration indium sulfate aqueous solution and a 0.1 M concentration tin sulfate aqueous solution are mixed to prepare a metal ion-containing acidic aqueous solution in which the molar ratio of indium ions to tin ions is indium / tin = 15/85. The polyimide film was immersed in this metal ion-containing aqueous solution for 20 minutes, and indium ions and tin ions were coordinated to the modified layer to form a metal ion-containing modified layer (see FIG. 1C). Thereafter, excess metal ions were removed with distilled water.

  Next, this polyimide film was heat-treated in a hydrogen atmosphere at 350 ° C. for 3 hours to obtain a nanoparticle aggregate made of an indium-tin alloy. At this time, the film thickness of the nanoparticle aggregate was 200 nm. Thereafter, the polyimide film was heat-treated in an air atmosphere at 300 ° C. for 6 hours to react the indium-tin alloy with oxygen to form an ITO thin film (see FIG. 1D). The ITO thin film had a line width of 16 μm and a sheet resistance of 0.7Ω / □.

(Example 3)
An aqueous alkaline solution was prepared by adding 35 parts by mass of polyvinylpyrrolidone and 25 parts by mass of glycerin as a thickener to 100 parts by mass of a 5M ethylenediamine aqueous solution, and stirring and dissolving them.

  Next, a circuit pattern having a line width of 10 μm is formed on the surface of the polyimide film which is filled with the above alkaline aqueous solution in the ink cartridge of the print head and cleaned on the surface in the same manner as in Example 1 using a thermal ink jet printing apparatus. Drawing and heat-treated at 50 ° C. for 10 minutes. Thereafter, the polyimide film was immersed in a 1-propanol solution, subjected to ultrasonic cleaning for 10 minutes, and dried at 100 ° C. for 30 minutes. As a result, a modified layer having a circuit pattern shape was formed on the surface of the polyimide film (see FIG. 1B).

  Next, a polyimide film was immersed in a metal ion-containing acidic aqueous solution composed of a 50 mM cadmium nitrate aqueous solution for 3 minutes, and cadmium (II) ions were coordinated to the modified layer to form a metal ion-containing modified layer. (See FIG. 1 (c)). Thereafter, excess cadmium nitrate was removed with distilled water.

  Next, an aqueous solution having a composition of 100 ppm sodium sulfide, 5 mM disodium hydrogen phosphate, 5 mM potassium dihydrogen phosphate was kept at 30 ° C., and the polyimide film was immersed for 20 minutes for sulfiding treatment. Cadmium nanoparticle aggregates were obtained. And the density | concentration of the nanoparticle aggregate | assembly of a cadmium sulfide was increased by repeating the process after the process by said alkaline aqueous solution 5 times.

  Thereafter, a cadmium sulfide thin film was formed by performing heat treatment under conditions of 300 ° C. for 5 hours in an air atmosphere (see FIG. 1D). The cadmium sulfide thin film had a thickness of 1.0 μm and a line width of 10 μm.

(Example 4)
A 5M aqueous ethylenediamine solution was used as the aqueous alkaline solution. Then, this alkaline aqueous solution is filled in the ink cartridge of the print head, and a circuit pattern having a line width of 20 μm is drawn on the surface of the polyimide film whose surface is cleaned in the same manner as in Example 1 using a piezo ink jet printing apparatus. And left at 30 ° C. for 30 minutes. Thereafter, the polyimide film was immersed in distilled water, subjected to ultrasonic cleaning for 3 minutes, and dried at 50 ° C. for 5 minutes. As a result, a modified layer was formed in a circuit pattern shape having a width of 21 μm on the surface of the polyimide film (see FIG. 1B).

Next, a 50 mM CuSO ₄ aqueous solution is used as the metal ion-containing acidic solution, the polyimide film is immersed in this aqueous solution for 5 minutes, and Cu ions are coordinated to the modified layer to form a metal ion-containing modified layer. (See FIG. 1 (c)). Thereafter, excess CuSO ₄ was removed with distilled water.

Next, a dimethylamine borane aqueous solution having a concentration of 100 mM was used as the reducing solution, and after immersing the polyimide film in this aqueous solution for 10 minutes and washing with distilled water, the copper thin film was deposited on the surface portion of the metal ion-containing modified layer. It was confirmed (see FIG. 1 (d)). The thickness of the copper thin film was 200 nm, and the electrical resistance of the copper thin film was 5 × 10 ⁻³ Ωcm, and a circuit pattern having the same shape as the application shape of the alkaline aqueous solution could be formed.

  Thereafter, the polyimide film was immersed in a neutral electroless nickel plating bath having the following bath composition whose temperature was adjusted to 75 ° C. for 3 hours.

NiSO ₄ : 0.1M
CH ₃ COOH: 1.0M
NaH ₂ PO ₂ : 0.2M
pH: 4.5
The electroless nickel plating film was deposited on the silver thin film, and a uniform nickel plating film having a thickness of 4 μm was obtained. The electric resistance of the nickel plating film was 3 × 10 ⁻⁵ Ωcm, and the circuit of the electronic circuit board could be formed with the silver thin film and the nickel plating film (see FIG. 1E).

  INDUSTRIAL APPLICABILITY The present invention can be widely used in the manufacture of electronic parts, mechanical parts, particularly circuit boards such as flexible circuit boards, flex-rigid circuit boards, and TAB carriers.

An example of embodiment of this invention is shown, (a) thru | or (e) is a schematic sectional drawing, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polyimide resin base material 2 Alkaline aqueous solution 3 Modified layer 4 Metal ion containing modified layer 5 Inorganic thin film 6 Electroless plating film

Claims (11)

  In forming an inorganic thin film on the surface of the polyimide resin, (1) applying an alkaline aqueous solution to the inorganic thin film forming portion of the polyimide resin and cleaving the imide ring of the polyimide resin to generate a carboxyl group, (2) the carboxyl A step of bringing a metal ion-containing solution into contact with a polyimide resin having a group to form a metal salt of a carboxyl group; (3) inorganic deposition by depositing the metal salt as a metal or as a metal oxide or semiconductor on the polyimide resin surface Forming a thin film; and a method for forming an inorganic thin film pattern of polyimide resin.   2. The method for forming an inorganic thin film pattern of polyimide resin according to claim 1, wherein, in the step (1), an alkaline aqueous solution is applied to the inorganic thin film forming portion of the polyimide resin by an ink jet method.   2. The method for forming an inorganic thin film pattern of polyimide resin according to claim 1, wherein, in the step (1), an alkaline aqueous solution is applied to the inorganic thin film forming portion of the polyimide resin by a transfer method.   In the step (1), after forming an alkali-resistant protective layer on a portion other than the polyimide resin inorganic thin film forming portion, an alkaline aqueous solution is applied to bring the polyimide resin inorganic thin film forming portion into contact with the alkali aqueous solution. The method for forming an inorganic thin film pattern of polyimide resin according to claim 1.   The step of forming the inorganic thin film of (3) is a step of forming a metal thin film by reducing the metal salt to deposit the metal salt as a metal on a polyimide resin surface. 5. A method for forming an inorganic thin film pattern of a polyimide resin according to any one of 1 to 4.   In the step (3) of forming the inorganic thin film, the metal salt is reacted with an active gas to deposit the metal salt as a metal oxide or semiconductor on the polyimide resin surface to form a metal oxide thin film or a semiconductor thin film. The method for forming an inorganic thin film pattern of polyimide resin according to claim 1, wherein   The method for forming an inorganic thin film pattern of polyimide resin according to any one of claims 1 to 6, wherein in the step (3), the deposited inorganic thin film is composed of an aggregate of inorganic nanoparticles.   The method for forming an inorganic thin film pattern of a polyimide resin according to claim 7, wherein in the step (3), a part of the aggregate of inorganic nanoparticles is embedded in the polyimide resin.   9. The polyimide resin inorganic thin film according to claim 1, further comprising: (4) a step of performing electroless plating on the polyimide resin surface on which the inorganic thin film is deposited, after the step (3). Pattern forming method.   10. The method for forming an inorganic thin film pattern of polyimide resin according to claim 9, wherein in the step (4), electroless plating is performed using an aggregate of inorganic nanoparticles as a plating precipitation nucleus.   The method for forming an inorganic thin film pattern of polyimide resin according to any one of claims 1 to 10, wherein the inorganic thin film forming portion has a circuit pattern shape.

Images