KR102474143B1 - Method for forming metal film on polyimide resin - Google Patents

Abstract

Step (S1) of modifying the surface of the polyimide resin by contacting it with an alkaline aqueous solution; A step of treating the modified polyimide resin with an aqueous solution containing at least one soluble salt of a specific metal selected from the group consisting of nickel, copper, palladium, and cobalt and replacing the metal (S2); Reducing the metal ion substituted with polyimide resin with a reducing agent (S3); A method for forming a metal film comprising, in step (S2), at least one of a basic nitrogen atom-containing compound selected from the group consisting of ammonia, mono- and polyethylene-polyamines, and mono- and polyethanolamines in a soluble salt of a specific metal; It is possible to form a film of a specific metal with good adhesion on the surface of the polyimide resin by treating the modified polyimide resin with an aqueous solution in which species coexist, and coordinating a compound complex containing a basic nitrogen atom of metal to the polyimide resin. do.

Description

Method for forming metal film on polyimide resin

The present invention relates to a method of forming a metal film on a polyimide resin. The present invention provides a method capable of forming a metal film on a polyimide resin with excellent adhesion based on alkali modification.

Polyimide resin films have excellent heat resistance, flame resistance, and chemical resistance, and have both mechanical properties such as strength and electrical properties such as electrical insulation, so they are widely used as circuit forming materials for electronic devices and the like. .

Conventionally, as a method of forming a circuit by coating a surface of such a polyimide resin film with a metal film such as copper, a lamination method in which a polyimide resin film and metal foil are bonded with an adhesive has been employed. However, in recent years, with the miniaturization of wiring intervals due to high density, the presence of adhesives has adversely affected the electrical insulating properties and heat resistance of substrates.

Therefore, in recent years, sputtering, ion plating, evaporation, electroless plating, and the like are generally performed instead of the lamination method.

Among these, in particular, after modifying the surface of the polyimide resin with an alkali agent, then substituting/reducing with a metal to directly apply the metal on the polyimide resin, further performing electroless plating and electroplating to thicken the metal film. method is noteworthy.

Hereinafter, the mechanism of the method of forming a metal film on the polyimide resin by such alkali modification will be briefly described.

When the polyimide resin is immersed in an aqueous alkali solution such as potassium hydroxide, the imide ring is hydrolyzed to open the ring to form a carboxyl group and an amide bond. alkali metal).

Subsequently, when this ring-opened polyimide resin is immersed in an aqueous solution containing metal ions such as Ni or Cu (for example, nickel sulfate, copper sulfate, etc.), potassium of the carboxyl group dissolves in the metal (Ni, Cu, etc.) is replaced by

Further, when the polyimide resin in this state is treated with an aqueous reducing agent solution, metal ions such as Ni or Cu are reduced to metal, and a thin metal film of Ni or Cu is formed on the polyimide resin. Thereafter, electroless plating and electroplating are performed to form a thick film.

Here, a prior art related to a method of forming a metal film on a polyimide resin by alkali modification or a prior art related to a method of forming a metal film on a non-conductive substrate in which a metal complex is involved is as follows. .

(1) Patent Document 1

A polyimide resin film is treated with an aqueous alkali solution to generate carboxyl groups, adsorbs metal ions to the carboxyl groups, reduces the adsorbed metal ions with an aqueous reducing agent solution, and then electroless nickel or copper plating while maintaining the active state of the metal ions. , and a method for metallizing a polyimide resin film by performing electrocopper plating, and a flexible printed wiring board manufactured using the metallization method are disclosed (claims 1 to 8).

The metal ion is selected from nickel, cobalt, and silver (Claim 4).

In addition, if heat treatment is performed at 150° C. to 350° C. after electroplating, the adhesion between the film and the metal layer is improved (paragraph [0013]).

(2) Patent document 2

In the invention disclosed in Patent Literature 2, palladium ions (palladium-amino acid complex) are coordinated to the polyimide resin through a predetermined amino acid in the metal replacement step of the polyimide resin.

That is, a method for forming a metal plated film on a polyimide resin in which the alkali treatment of the polyimide resin, followed by catalyst imparting treatment, electroless metal plating, and electrometal plating are sequentially performed, wherein the alkali treatment and the catalyst imparting treatment are performed. In the meantime, treatment with an aqueous solution of a specific basic amino acid selected from lysine, ornithine, and arginine, strongly coordinating this basic amino acid to the polyamic acid (= polyamic acid) portion (polar portion) of the polyimide resin ring-opened by alkali treatment, Disclosed is a method for forming a metal film of a polyimide resin, wherein a palladium complex solution is allowed to act thereon to chelate-coordinate a palladium complex with an aminocarboxyl group of a basic amino acid, reduce palladium ions, and catalytically impart palladium to the polyimide resin. Yes (claims 1 to 3, paragraphs [0009], [0027] to [0037], [Formula 1] to [Formula 3]).

Thereafter, electroless nickel and copper plating is performed on the polyimide resin to which the catalyst is applied, and electrolytic copper plating is performed (paragraphs [0038] to [0040]).

In Example 1, the polyimide resin is alkali treated, immersed in an aqueous lysine solution, and then immersed in an ionic palladium catalyst solution, and the polyamic acid portion (polar portion) of the polyimide resin is coordinated with palladium ions through lysine, In addition to reducing metal palladium with a reducing agent to provide a catalyst, electrolytic copper plating is performed through electroless nickel plating and copper replacement of the nickel coating (paragraphs [0035] to [0040]).

(3) Patent document 3

In the invention disclosed in Patent Literature 3, a polyimide resin is treated with an alkali, replaced with a metal ion such as palladium, and the metal ion is not reduced, but a palladium-anmine complex salt aqueous solution is added to the copper wiring formed on the polyimide resin. The basic principle is to contact and replace copper with palladium.

That is, after degreasing and acid-cleaning a polyimide film substrate having a fine copper wiring circuit, it is immersed for a certain period of time in an aqueous solution of a palladium-anmine complex salt containing an excess of ammonium ions relative to palladium ions (divalent), and the surface of the copper wiring is treated with palladium. After substitution, a method of removing the complex salt solution by acid washing and washing with distilled water, and performing electroless nickel plating is disclosed (claims 1 to 6).

The main component of the palladium-anmine complex salt is a palladium-tetraanmine complex salt (Claim 2).

In this method, the surface of the copper wiring circuit can be uniformly coated with nickel, and at the same time, copper ions generated by the substitution reaction between copper and palladium form and stabilize an excess ammonia molecule and a tetraanmine-copper complex, Precipitation and adhesion of fine copper particles on the insulating layer can be suppressed (paragraphs [0025] to [0028]).

In Example 1, the polyimide film on which copper wiring was formed was treated with a palladium catalyst solution containing palladium-anmine complex salt and ammonium ion, the surface of the copper wiring was substituted with palladium, and electroless nickel plating was performed ( paragraphs [0063] to [0066]).

(4) Patent Document 4

(a) a step of treating a polyimide resin with an alkaline alcohol solution, dissolving a part of the resin, and ring-opening an imide ring of a nearby resin to generate a carboxyl group;

(b) a metal substitution step of generating a metal salt of a carboxyl group by contacting a metal ion-containing solution with the polyimide resin having a carboxyl group;

(c) forming a metal thin film on the surface of a polyimide resin using the metal salt as a metal;

A method for forming a metal film of polyimide resin is disclosed (Claim 1).

In the metal substitution step (b), as metal ions of the containing solution, copper ions, silver ions, nickel ions, etc., as well as palladium/anmine complexes and platinum/anmine complexes are disclosed (paragraph [0045]).

However, in the Examples, no palla-anmine complex is used in the metal replacement step (b).

(5) Patent Document 5

In Patent Document 5, a metal/ammonium complex (metal/anmine complex) is disclosed as a complex used in a catalytic process, but the metal is silver.

a sensitization step of treating a non-conductive substrate (polyimide, etc.) with an aqueous solution containing tin salt and a surfactant; a catalyst imparting step of treating with a catalyst solution containing silver ions; A process of performing chemical plating (electrolytic plating, etc.); a method for forming a metal film on a non-conductive substrate is disclosed (Claim 1, paragraphs [0010] and [0012]).

As a supply source of silver ions contained in the catalyst liquid, a silver-ammonia complex, a silver-amine complex, and a silver-chloride complex are disclosed (Claim 13, paragraph [0052]).

(6) Patent Document 6

(a) contacting the surface of the polyimide resin with an aqueous solution of tetraalkylammonium hydroxide to ring-open the imide ring of the polyimide resin to form a carboxyl group and an amide bond;

(b) contacting a metal ion-containing solution with the polyimide resin having a carboxyl group and an amide bond to form a metal salt of the carboxyl group;

(c) a step of forming a metal thin film on the surface of the polyimide resin using the metal salt as a metal; a method for forming a metal film of a polyimide resin is disclosed (claims 1 and 2).

When sodium hydroxide or potassium hydroxide is used in the step (a), these alkali metal ions may remain in the polyimide resin and the polyimide resin may decompose when heated. However, in step (a) of Patent Document 6, since tetraalkylammonium hydroxide is used as an aqueous alkali solution, these adverse effects can be eliminated (paragraph [0008]).

(7) Patent Document 7

First, the surface of the polyimide film is activated using nitric acid and alkali, then, as is or by applying a polyamic acid solution, treating with palladium chloride to give a catalyst, heat treatment at 200 ° C. or higher, and then Thus, a method for manufacturing a polyimide substrate is disclosed, in which a metal layer of copper, nickel, cobalt, or the like is formed by electroless plating or electroplating, or additionally, heat treatment is performed at 200° C. or higher (claims 1 to 10, paragraph [0036]). ][0040]).

In the heat treatment step after applying the catalyst, the polyimide resin is stabilized by a ring closure reaction of polyamic acid in the hydrophilic layer (paragraph [0034]).

(8) Patent Document 8

(a) a step of treating the surface of a polyimide resin with an aqueous alkali solution and ring-opening an imide ring of the polyimide resin to generate a carboxyl group;

(b) neutralizing the carboxyl group with an acid;

(c) a step of generating a Cu salt or Pd salt of the carboxyl group by treating the carboxyl group with a Cu solution or a Pd solution;

(d) reducing the Cu salt or Pd salt and forming a film of the Cu metal or Pd metal on the surface of the polyimide resin;

A method for forming a conductive film of polyimide resin, comprising or further comprising a step of performing electroless copper plating or electrolytic copper plating, is disclosed (claims 1 and 2, paragraph [0009]).

The step (b) aims to neutralize the surface of the resin, which has become strongly alkaline due to conversion to a carboxyl group, with an acidic solution (paragraph [0005]).

Japanese Unexamined Patent Publication No. 2006-104504 Japanese Unexamined Patent Publication No. 2007-056343 Japanese Unexamined Patent Publication No. 2013-019044 Japanese Unexamined Patent Publication No. 2005-029735 Japanese Patent Publication No. 2005-537387 Japanese Unexamined Patent Publication No. 2008-091456 Japanese Unexamined Patent Publication No. Hei 07-321457 Japanese Unexamined Patent Publication No. 2001-073159

As described above, the method of forming a metal film on a polyimide resin by alkali modification involves bringing a metal salt into contact with an alkali-treated polyimide resin to reduce substituted metal ions and directly applying a metal to the surface of the polyimide resin. Although this is the basic principle, the techniques disclosed in Patent Literatures 1, 7, and 8 are based on these principles and further improved.

The technique disclosed in Patent Document 6 is characterized in that tetraalkylammonium hydroxide is selected instead of known potassium hydroxide or sodium hydroxide for the alkali agent used in the alkali reforming.

In Patent Document 4, it is mentioned that a palladium/anmine complex can be used in a metal replacement step, but there is no specific disclosure of examples using this complex.

In Patent Document 5, it is mentioned that a metal/mineral complex is used in the catalyst application step after the sensitization step, but the metal to be applied with the catalyst is silver.

The technique disclosed in Patent Literature 2 is to react with an aqueous solution of a specific basic amino acid selected from lysine, ornithine, and arginine following alkali treatment of a polyimide resin, and then act with a solution of a palladium complex to obtain a palladium-amino acid complex. After coordinating to the polyimide resin (paragraph [0045]), palladium ions are reduced to impart palladium to the polyimide resin as a catalyst, and is characterized in that a specific amino acid complex of palladium is used in the metal replacement step.

The technique disclosed in Patent Literature 3 uses, as a basic principle, a palladium-anmine complex salt solution in contact with a copper wiring formed in a polyimide resin to replace copper with palladium. Therefore, the principle is different from the above-described technique of forming a metal film by alkali modification, in which alkali treatment is performed on the polyimide resin, substitution with metal ions such as palladium, and reduction of the metal ions.

In the case of forming a film of a specific metal such as nickel or copper on the surface of a polyimide resin, even if the techniques disclosed in Patent Literatures 1, 6, and 8 are applied, it is insufficient to obtain strong adhesion. In the technology disclosed in Patent Document 5, the film-forming metal is silver, which is different from the specific metal selected from nickel, copper, and the like. Therefore, it is not clear whether or not good adhesion can be obtained when these specific metals are selected.

A technical problem of the present invention is to form a film of a specific metal selected from nickel, copper, or the like with good adhesion on the surface of a polyimide resin.

The inventors of the present invention, in the step of metal substitution of an alkali-modified polyimide resin, as disclosed in the patent literature, when various metal complexes act on the polyimide resin, when soluble salts of metals that are not in the form of complexes act on the polyimide resin In contrast, the level of adhesion of the formed metal film to the polyimide resin was intensively studied.

As a result, when the metal substitution treatment is performed, a specific compound having a basic nitrogen atom, including ammonia or further, mono and polyethylene polyamines such as ethylenediamine, is added to the soluble salt of the metal (copper, nickel, etc.) It has been found that when a polyimide resin is treated by coexisting, it is possible to homogenize the metal film obtained by the subsequent reduction of metal ions, thereby forming a metal film with excellent adhesion to the surface of the polyimide resin. invention is complete.

In the present invention 1,

(S1) a step of modifying the surface of the polyimide resin by bringing it into contact with an alkaline aqueous solution;

(S2) metal replacement by treating the modified polyimide resin with an aqueous solution containing at least one soluble salt of a metal selected from the group consisting of nickel, copper, palladium, and cobalt;

(S3) reducing the metal ion substituted with the polyimide resin with a reducing agent;

including,

In the step (S2), ammonia, "monoethylene polyamines and polyethylene polyamines" (hereinafter also referred to as "mono- and polyethylene polyamines"), and "monoethanolamines and polyethanolamines" are added to the metal soluble salt (hereinafter also referred to as “mono- and polyethanolamines”) selected from the group consisting of “basic nitrogen atom-containing compounds” (hereinafter also referred to as “N compounds”) coexisting in an aqueous solution, wherein the modified polyi A method for forming a metal film on a polyimide resin, characterized in that the mead resin is treated to coordinate the N-compound complex of the metal to the polyimide resin.

Invention 2 is a method for forming a metal film on a polyimide resin according to the invention 1, wherein the N compound is at least one selected from ammonia, ethylenediamine, diethylenetriamine, and triethanolamine.

In the present invention 3, in the present invention 1 or 2, after the step (S1), the step (S2), and the step (S3),

(S4) heat treatment of the polyimide resin; and/or

(S5) a step of forming a conductive film by electroless plating and/or electroplating on the metal film of polyimide resin obtained by reduction in step (S3);

A method for forming a metal film on a polyimide resin, characterized in that it comprises a.

Invention 4 is a method for forming a metal film on a polyimide resin according to the invention 3, characterized in that in the step (S4), the heat treatment temperature is 80°C to 300°C.

In the present invention 5, in the present invention 3 or 4, in the step (S5), at least one metal selected from nickel and copper is subjected to electroless plating and/or electroplating in a single layer or multiple layers. It is a method of forming a metal film on a polyimide resin.

In the present invention, in the metal substitution step (S2) in the alkali-modified polyimide resin, in an aqueous solution containing metal ions, N selected from the group consisting of ammonia, mono and polyethylene polyamines, and mono and polyethanol amines At least one of the compounds is allowed to coexist, the metal N compound complex is coordinated with the carboxyl group of the polyimide resin, and metal is substituted. Therefore, according to the present invention, the adsorption density of metal is increased by promoting the displacement action, the film of the metal selected from nickel, copper, palladium, and cobalt is uniformed on the polyimide resin, and the film is formed with excellent adhesion. can

In the electroless plating and/or electroplating step (S5), electroless plating and/or electroplating is performed on the metal film of the polyimide resin reduced in step (S3), and copper, nickel, etc. The conductive film can be thickened.

In addition, when the polyimide resin is heat treated in step S4 following the reduction treatment step S3, the polyimide resin that has been ring-opened in the alkali modification step S1 is ring-closed, and polyimide having heat resistance, chemical resistance, etc. The original properties of the resin can be maintained. In particular, such heat treatment is effective when alkali modification is performed under strong conditions (conditions where the pH of the alkali agent is high or conditions where the treatment time is long).

As described above, Patent Document 4 discloses that not only metal ions such as silver and copper can be used in the metal replacement step, but also metal complexes such as palladium/anmine complexes and platinum/anmine complexes (paragraph [ 0045]), these complexes are not used in Examples.

Patent Document 5 enumerates silver/ammonium complexes (i.e., silver/anmine complexes), silver/amine complexes, and silver/chloride complexes as silver salts used in the catalyst imparting step after the sensitization step (Claim 13), but the catalyst The metal to which is given is limited to silver, and a metal complex other than silver is not disclosed.

In the technology disclosed in Patent Document 2, a palladium-amino acid complex composed of palladium and a specific basic amino acid selected from lysine, ornithine, and arginine is coordinated with an alkali-modified polyimide resin (paragraph [0045]), and then palladium ions are reduced. The specific basic amino acid of the technology disclosed in Patent Document 2 that forms a complex with palladium is different from the specific N compound of the present invention selected from ammonia, ethylenediamine, and the like.

The present invention is a method for forming a metal film on a polyimide resin by sequentially performing the following steps (S1) to (S3).

(S1) Process of alkali-modifying the polyimide resin surface

(S2) a step of substituting modified sites of polyimide resin with ions of a specific metal selected from nickel, copper, palladium, and cobalt

(S3) a process of reducing the metal ion

A feature of the present invention is that in the metal replacement step (S2), ammonia, mono- and polyethylenepolyamines, and N compounds selected from mono- and polyethanolamines coexist with the metal ion, and treatment is performed, and the metal ( Nickel, copper, palladium, cobalt) Anmine complex, polyamine complex, etc. (a metal N compound complex in a higher level concept) are made to act on the polyimide resin.

In the above metal film formation method, after the reduction step (S3),

(S4) a step of heat-treating the polyimide resin, and/or

(S5) A step of forming a conductive film by electroless plating and/or electroplating on the metal film of the polyimide resin obtained by reduction in the step (S3).

it is possible to carry out

In the heat treatment step (S4), the polyimide resin ring-opened in the alkali reforming step (S1) is ring-closed, and chemical properties, mechanical properties, and electrical properties of the polyimide resin can be maintained. The appropriate heat treatment temperature is 80°C to 300°C.

Further, by adding an electroless plating and/or electroplating step (S5) following the reduction step (S3), a conductive film such as copper or nickel is laminated on the metal film formed in the reduction step (S3) to form a thick film. can get angry

The polyimide resin used in the present invention is a polymer having a cyclic imide structure in the main chain, and a film or sheet made of a general polyimide resin may be selected, but the shape is not particularly limited. Before alkali treatment of the polyimide resin, as a preliminary treatment, the surface of the polyimide resin may be finely roughened with an oxidizing agent such as a white fuming nitric acid solution or a potassium permanganate solution.

First, the alkali modification step (S1) is a step of modifying the surface of the polyimide resin by bringing it into contact with an aqueous alkali solution.

In this alkaline treatment, the polyimide resin is immersed in a strong alkaline aqueous solution such as an aqueous potassium hydroxide solution, an aqueous sodium hydroxide solution, or an aqueous calcium hydroxide solution to modify the surface.

The concentration of the aqueous alkali solution is preferably 0.1 mol/L to 10 mol/L, more preferably 0.5 mol/L to 5 mol/L. The treatment temperature is preferably 20°C to 70°C, more preferably 30°C to 60°C. The treatment time is related to the concentration of the aqueous alkali solution and the treatment temperature, but is usually 0.5 to 15 minutes, preferably 2 to 10 minutes.

Further, alcohols such as ethanol, methanol, and monoethanolamine and a surfactant may be added to the aqueous alkali solution.

In the alkali modification step (S1), the imide ring of the polyimide is ring-opened as shown in the following formula (I) by treating the polyimide resin with alkali, for example, by treating it with potassium hydroxide, A modified layer of polyamic acid having a carboxyl group in which an amide bond and an alkali metal ion are bonded is formed on the surface of the polyimide resin.

Next, the metal replacement step (S2) of the polyimide resin will be described.

As shown in Chemical Formula (I), in the polyimide resin modified in step (S1), alkali metal ions (specifically, potassium ions) are bonded to carboxyl groups formed by ring-opening of the imide ring of polyimide. In step S2, the modified polyimide resin is treated with a “soluble salt of a specific metal” selected from nickel, copper, palladium, and cobalt (hereinafter also referred to as “M salt”), and an alkali metal ion bonded to a carboxyl group ( = potassium ion) is substituted with the ion of the specific metal (each ion of Ni, Cu, Pd, and Co).

The present invention is characterized in that, in the metal replacement step (S2), the polyimide resin is treated with an aqueous solution obtained by coexisting a predetermined N compound such as ammonia, ethylenediamine, and ethanolamine with a predetermined M salt. .

The N compound used in the step (S2) is a compound that has a basic nitrogen atom in its molecule and is capable of donating electrons from the nitrogen atom's lone electron pair to the specific metal ion used in the present invention. The N compound can be selected from the compounds listed in (1) to (3) below, and these can be used alone or together.

(1) Ammonia

(2) Mono and polyethylene polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine

(3) Mono and polyethanolamines such as ethanolamine, diethanolamine, and triethanolamine

As the N compound, ammonia, ethylenediamine, diethylenetriamine, triethylenetetramine, triethanolamine and the like are preferable, and ammonia, ethylenediamine, diethylenetriamine and triethanolamine are more preferable.

The concentration of the N compound in the metal replacement step (S2) is preferably 0.000002 mol/L to 15 mol/L, more preferably 0.00005 mol/L to 10 mol/L. For example, when the N compound is ammonia, the complex becomes unstable if the concentration of the aqueous ammonia solution is lower than the appropriate range, and conversely, if the concentration exceeds the appropriate range, the amount of ammonia gas generated increases and there is a risk of deteriorating the work environment.

Here, the mechanism of the metal replacement step (S2) will be schematically described using ammonia as a representative example of the N compound.

In the aqueous solution for the metal replacement treatment in which ammonia and M salt coexist, the specific metal ion forms a complex ion with ammonia.

For example, complex ions form a square when a specific metal ion is a copper ion, and a regular octahedron when a nickel ion or cobalt ion is used, and the metal complex ion is chelate-coordinated with the carboxyl group of the polyimide resin. Compared to the case where a specific metal ion bonds to a carboxyl group alone, the metal complex ion is strongly fixed in the modified layer of the polyimide resin. In this case, ammonia is water-soluble, and the specific metal ion surrounded by ammonia is homogeneously dispersed in the treatment aqueous solution and can be evenly spread and coordinated on the surface of the polyimide resin, which is the main factor that can be strongly fixed in the modified layer. It is speculated that this may not be the cause.

However, when the specific metal is palladium and the N compound is ammonia, the palladium-anmine complex is alkaline at the time of its formation, but it is necessary to pay attention to the fact that the coordination function can be exhibited smoothly in the polyimide resin by acid treatment. (See Example 6 described below).

The metal of the soluble salt used in the metal replacement step (S2) is selected from nickel, copper, palladium, and cobalt.

Examples of the soluble nickel salt include nickel oxide, nickel chloride, nickel sulfate, nickel carbonate, nickel nitrate, and a nickel salt of organic sulfonic acid.

Examples of the soluble copper salt include copper sulfate, copper chloride, copper oxide, copper carbonate, copper acetate, copper pyrophosphate, copper oxalate, and copper salts of organic sulfonic acid.

As said soluble palladium salt, palladium sulfate, palladium chloride, palladium acetate, palladium nitrate, the palladium salt of organic sulfonic acid, etc. are mentioned, for example.

Examples of the soluble cobalt salt include cobalt sulfate, cobalt chloride, cobalt oxide, cobalt carbonate, cobalt acetate, and cobalt salts of carboxylic acids.

The concentration of the M salt in the metal replacement step (S2) is preferably 0.00001 mol/L to 5 mol/L, more preferably 0.0001 mol/L to 2 mol/L.

The ratio (molar ratio) of N compound to M salt in the metal replacement step (S2) is preferably N compound/M salt = 0.001 to 200, more preferably N compound/M salt = 0.002 to 150. . If the value of N compound/M salt is less than the appropriate range, the ability of the N compound to form a complex with a specific metal ion is reduced, and there is a risk that the formed metal film may lack adhesion to the polyimide resin. However, improvement in the metal replacement function cannot be expected so much.

The treatment temperature in the metal replacement step (S2) is preferably 20°C to 70°C, more preferably 20°C to 40°C. The treatment time is related to the concentration of the aqueous alkali solution and the treatment temperature, but is usually 0.5 minutes to 15 minutes, preferably 2 minutes to 10 minutes.

Subsequently, a reduction step (S3) by reduction of metal ions adsorbed (substituted) by the polyimide resin will be described. As the reducing agent, boron hydride compounds such as potassium borohydride and sodium borohydride, hypophosphorous acid and salts thereof, amineboranes such as dimethylamineborane, and the like can be used. It is also possible to process with a reducing gas, such as hydrogen and its mixed gas, and borane-nitrogen mixed gas.

In addition, alcohols such as ethanol, methanol, and monoethanolamine or a surfactant may be added to the reducing agent solution.

The concentration of the reducing agent is preferably 0.005 mol/L to 1 mol/L, more preferably 0.01 mol/L to 0.5 mol/L. If the concentration of the reducing agent exceeds an appropriate range, it is undesirable because there is a risk of losing the adhesion of the metal film.

The reduction reaction temperature is preferably 20°C to 50°C, more preferably 20°C to 40°C. If the temperature is lower than the appropriate range, there is a risk of precipitation bias, and if it exceeds the appropriate range, the reducing agent may decompose and the reducing function may deteriorate.

As a result, the ions of the specific metal are reduced with the reducing agent, and a coating of the specific metal selected from nickel, copper, palladium and cobalt can be formed on the surface of the polyimide resin with good adhesion.

The plating step (S5) is a step of thickening the conductive film formed on the surface of the polyimide resin by plating, following the reduction step (S3).

In the plating step (S5), either electroless plating or electroplating may be applied, or electroplating may be applied after electroless plating.

In the case of electroless plating, for example, nickel electroless plating or copper electroless plating can be selected, and either a nickel film or a copper film is applied on the specific metal film formed in the step (S3). It may be formed as a single layer, or a copper film may be formed in the form of a plurality of layers on the nickel film.

There is no particular limitation on the composition of the electroless nickel plating solution used in the step (S5), and a known plating solution can be used.

A known electroless nickel plating solution basically contains a soluble nickel salt and a reducing agent as main components, and various additives such as a complexing agent, a pH adjusting agent, and a reaction accelerator are contained therein.

In electroless plating, when a phosphorus-based reducing agent (eg, hypophosphite) is used, a nickel-phosphorus alloy film is obtained, and when a boron-based reducing agent (eg, dimethylamineborane) is used, a nickel-boron alloy A film is obtained.

As the soluble nickel salt, any soluble salt that generates nickel ions in an aqueous solution may be used. As described in the description of the metal replacement step (S2), nickel sulfate, nickel oxide, nickel chloride, nickel ammonium sulfate, nickel acetate, nickel nitrate, nickel carbonate, nickel sulfamate, or a nickel salt of organic sulfonic acid or carboxylic acid, etc. can be heard

Examples of the complexing agent include ammonia, mono- and polyethylene polyamines, pyrophosphoric acids, oxycarboxylic acids, aminocarboxylic acids, amino acids, and polycarboxylic acids.

Regarding the mono and polyethylene polyamines, ethylenediamine, diethylenetriamine and the like are exemplified as described in the description of the metal replacement step (S2).

Examples of the oxycarboxylic acids include citric acid, tartaric acid, malic acid, gluconic acid, glucoheptonic acid, glycolic acid, lactic acid, trioxybutyric acid, ascorbic acid, isocitric acid, tartronic acid, glyceric acid, hydroxybutyric acid, leucic acid, and citra malic acid, erythorbic acid, and salts thereof; and the like.

Examples of the aminocarboxylic acids include hydroxyethylethylenediaminetriacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA), ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetrapropionic acid, Nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), hydroxyethyliminodiacetic acid, iminodipropionic acid, 1,3-propanediaminetetraacetic acid, 1,3-diamino-2-hydroxypropanetetraacetic acid, glycol ether diamine tetraacetic acid, metaphenylenediamine tetraacetic acid, 1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid, diaminopropionic acid, and salts thereof; and the like.

Examples of the above amino acids include glutamic acid, dicarboxylmethylglutamic acid, ornithine, cysteine, glycine, N,N-bis(2-hydroxyethyl)glycine, (S,S)-ethylenediaminesuccinic acid, salts thereof, and the like. can be heard

Examples of the polycarboxylic acids include succinic acid, glutaric acid, malonic acid, adipic acid, oxalic acid, maleic acid, citraconic acid, itaconic acid, mesaconic acid, and salts thereof.

Similarly, there is no particular restriction on the composition of the electroless copper plating solution used in the step (S5), and a known plating solution can be used.

That is, the electroless copper plating solution basically contains a soluble copper salt, a reducing agent, and a complexing agent, or may further contain various additives such as surfactants and pH adjusting agents, or acids.

As the soluble copper salt, any soluble salt that generates cuprous ions or cupric ions in an aqueous solution may be used. As described in the description of the metal replacement step (S2), copper sulfate, copper oxide, copper chloride, copper pyrophosphate, copper carbonate, copper carboxylic acid salts such as copper acetate, copper oxalate, copper citrate, copper methanesulfonate, Organic sulfonic acid copper salts, such as hydroxyethanesulfonic acid copper, etc. are mentioned.

Examples of the reducing agent include boron hydrides, amineboranes, hypophosphorous acids, phosphorous acids, aldehydes, ascorbic acids, hydrazines, polyhydric phenols, polyhydric naphthols, phenolsulfonic acids, and naphtholsulfonic acids.

As the complexing agent, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA), hydroxyethylethylenediaminetriacetic acid (HEDTA), nitrilotriacetic acid (NTA) ), amino carboxylic acids such as iminodiacetic acid (IDA); polyamines such as ethylenediamine, tetramethylenediamine, hexamethylenediamine, diethylenetriamine, tetraethylenepentamine, and pentaethylenehexamine; amino alcohols such as monoethanolamine, diethanolamine, and triethanolamine; oxycarboxylic acids such as citric acid, tartaric acid, lactic acid, and malic acid; thioglycolic acid; Glycine etc. are mentioned.

The electroless copper plating solution may contain an organic acid and an inorganic acid or a salt thereof as a liquid base component.

Examples of the inorganic acid include sulfuric acid, pyrophosphoric acid, and fluoroboric acid. Examples of organic acids include oxycarboxylic acids such as glycolic acid and tartaric acid; Organic sulfonic acids, such as methanesulfonic acid and 2-hydroxyethanesulfonic acid, etc. are mentioned.

On the other hand, when electroplating is performed in the step (S5), for example, electrolytic copper plating or electrolytic nickel plating can be selected (refer to Examples 14 to 17 to be described later), and the specific formed in the step (S3) Either a nickel film or a copper film may be formed as a single layer on the metal film, or a copper film may be formed in a plurality of layers on the nickel film.

As described above, it is also possible to carry out the electroless plating and further carry out the electroplating after the reduction step (S3).

Examples of the electrolytic copper plating solution used in the step (S5) include known electrolytic copper plating solutions such as a copper sulfate plating solution and a copper pyrophosphate plating solution.

The soluble copper salt contained in the electrolytic copper plating solution is copper sulfate, copper oxide, copper hydroxide, copper chloride, copper nitrate, copper carbonate, copper acetate, copper oxalate, etc., as described in the description of the metal replacement step (S2). .

As the acid used as the base component of the electrolytic copper plating solution, acids widely used in general copper plating baths such as sulfuric acid, hydrochloric acid, oxalic acid, and acetic acid can be used, and organic acids such as organic sulfonic acid and oxycarboxylic acid can also be used. .

Further, the electrolytic copper plating solution preferably contains various additives such as a leveler, a brightener, and a polymer component in order to promote a glossing action, a smoothing action, and the like.

The leveler is a nitrogen-based organic compound containing various surfactants or dyes as a main component.

The brightener, thiourea and its derivatives; mercaptans such as 2-mercaptobenzoimidazole and thioglycolic acid; sulfides such as 2,2'-thiodiglycolic acid and diethyl sulfide; and mercaptosulfonic acids such as sodium 3-mercaptopropane 1-sulfonate and bis(3-sulfonepropyl) disulfide (disodium salt).

The polymer components include polyethylene glycol, polypropylene glycol, polyethyleneimine, stearic acid-polyethylene glycol ester, polyethylene-propylene glycol, polyvinyl alcohol, carboxylmethylcellulose and the like.

On the other hand, also as an electric nickel plating solution, a well-known electroplating solution, such as a matt nickel plating solution, a Watt bath, and a sulfamic acid plating solution, can be used.

For example, an electrical nickel-lead plating bath widely used as an electrical nickel plating bath includes soluble nickel salts; phosphorus containing compounds; complexing agents such as aminocarboxylic acids, oxycarboxylic acids, polycarboxylic acids, and polyamines; Surfactants; brightener; Buffers and the like are contained.

As described in the description of the metal replacement step (S2), the soluble nickel salt is nickel sulfate, nickel chloride, nickel ammonium sulfate, nickel oxide, nickel acetate, nickel carbonate, nickel oxalate, nickel sulfamate, nickel of organic sulfonic acid salt, etc.

Examples of the phosphorus-containing compound include phosphorous acid, hypophosphorous acid, pyrophosphoric acid, orthophosphoric acid, hydroxyethylenediaminediphosphonic acid, nitrilotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, and salts thereof.

The complexing agent is a compound that mainly forms a nickel complex in the plating bath, and includes aminocarboxylic acids, oxycarboxylic acids, aminoalcohols, polycarboxylic acids, polyamines, and saccharides.

The brightening agent is saccharin and its salts, benzenesulfonic acid and its salts, p-toluenesulfonic acid and its salts, naphthalenesulfonic acid and its salts, arylsulfonic acid and its salts, butyndiol, ethylene cyanhydrin, coumarin, propargyl alcohol, bis (3-sulfonepropyl) disulfide, mercaptopropanesulfonic acid, thiomalic acid, and the like.

In the reduction step (S3), a film of a specific metal selected from nickel, copper, palladium, and cobalt is formed on the surface of the polyimide resin, but as described above, the heat treatment step (S4) is performed after the reduction step (S3). By doing so, it is possible to effectively ring-close the polyimide resin that has been ring-opened in the alkali reforming step (S1) and keep the characteristics of the polyimide resin good.

The heat treatment temperature in the heat treatment step (S4) is preferably 80°C to 300°C, more preferably 100°C to 250°C. Basically, when the modification is performed under strong alkaline conditions, the degree of ring opening of the polyimide resin increases accordingly, so the heat treatment conditions are strengthened, for example, the heat treatment temperature is set high, or the treatment time is set long. It is desirable to do

Examples of the heat treatment include dry treatment using ovens, dryers, and infrared heaters; Wet processing, such as a water bath and an oil bath, is mentioned.

It is possible to perform the heat treatment process (S4) and the plating process (S5) by connecting them in series. For example, reduction step (S3) → electroless plating step (S5) → heat treatment step (S4), reduction step (S3) → heat treatment step (S4) → pre-plating step (S5), or reduction step (S3) → Electroless plating process (S5) → Heat treatment process (S4) → Electroplating process (S5), etc., can be mentioned variously.

[Example]

Hereinafter, an embodiment of a method for forming a metal film on a polyimide resin in which the steps (S1) to (S3) of the present invention are sequentially performed, or the step (S4) and/or the step (S5) are selectively performed. And, an evaluation test example for the appearance and adhesion of the metal film formed in the implementation will be described in turn.

In the following Examples, Comparative Examples, and Test Examples, "parts" and "%" are basically based on weight.

In addition, the present invention is not limited to the following examples, etc., and any modifications can be made within the scope of the technical idea of the present invention.

<<Examples of a method for forming a metal film on a polyimide film>>

Among Examples 1 to 5 below, Example 1 is an example in which a nickel film was formed using ammonia as an N compound and a heat treatment step (S4) was performed.

Examples 2 to 5 are examples based on Example 1.

Example 2: Increasing the concentration of ammonia in the metal replacement process (S2)

Example 3: Omitting the heat treatment step (S4)

Example 4: Change N compound to ethylenediamine

Example 5: Change N compound to diethylenetriamine

Among Examples 6 to 8 below, Example 6 is an example in which a palladium film is formed using ammonia as an N compound, and a heat treatment step (S4) and an electroless plating step (S5) are performed.

Examples 7 to 8 are examples based on Example 6.

Example 7: Omitting the heat treatment step (S4)

Example 8: Change N compound to ethylenediamine

Among Examples 9 to 11 below, Example 9 is an example in which a copper film is formed using ammonia as an N compound and a heat treatment step (S4) is performed.

Examples 10 to 11 are examples based on Example 9.

Example 10: Omitting the heat treatment step (S4)

Example 11: Change N compound to ethylenediamine

Among Examples 12 to 13 below, Example 12 is an example in which a cobalt film was formed using ammonia as an N compound and the heat treatment step (S4) was performed.

Example 13 is an example based on Example 12.

Example 13: Omitting the heat treatment step (S4)

Examples 14 to 18 below are examples in which the electroplating step (S5) is performed after the reduction step (S3) to thicken the conductive film.

Example 14: Example based on Example 1 (with heat treatment)

Formation of copper film on nickel film

Example 15: Example based on Example 6 (with heat treatment)

Formation of copper film on nickel film

Example 16: Example based on Example 7 (without heat treatment)

Formation of copper film on nickel film

Example 17: Example based on Example 9 (with heat treatment)

Formation of the same copper film on the copper film

Example 18: Example based on Example 12 (with heat treatment)

Formation of copper film on cobalt film

On the other hand, Comparative Examples 1 to 4 below are examples in which a nickel film is formed based on Example 1 and then heat treated.

Comparative Example 1: An example in which no N compound is used and metal ions are not complexed in the metal replacement step (S2)

Comparative Example 2: Example using EDTA-4Na (ethylenediaminetetraacetic acid tetrasodium) instead of ammonia as a complexing agent

Comparative Example 3: Example using glycine instead of ammonia as a complexing agent

Comparative Example 4: An example in which, after the heat treatment in Comparative Example 1, a copper film was laminated by an electroplating step (S5), and the conductive film was thickened.

Comparative Examples 5 to 7 below are examples of heat treatment after forming a palladium film based on Example 6.

Comparative Example 5: Example in which no N compound is used and metal ions are not complexed in the metal replacement step (S2)

Comparative Example 6: Example using EDTA-4Na instead of ammonia as a complexing agent

Comparative Example 7: An example in which, after the heat treatment in Comparative Example 5, a copper film was laminated by an electroplating step (S5), and the conductive film was thickened.

(1) Example 1

The metal film formed on the polyimide film, the N compound (complexing agent) used in the metal replacement step (S2), the presence or absence of the heat treatment step (S4), the presence or absence of the plating step (S5), and the basic examples, They are summarized in Tables 1 and 2 to be described later (the following Examples and Comparative Examples are also the same).

[Alkali reforming step (S1)]

A polyimide film (Upilex 50S, manufactured by Ube Kosan Co., Ltd.) was immersed in a 5 mol/L aqueous solution of potassium hydroxide at 50°C for 30 minutes, and thoroughly washed with water.

[Metal Replacement Step (S2)]

Separately, 0.2 mol/L of nickel sulfate hexahydrate was once dissolved in 300 mL of distilled water, and then 400 mL of 25% aqueous ammonia was added, followed by 1 L of distilled water, containing 10% aqueous ammonia and 0.2 mol/L of nickel sulfate. A nickel-anmine complex solution was prepared. In addition, the nickel-anmine complex solution exhibited a deep blue color.

The polyimide film treated with alkali in the step (S1) was immersed in the nickel/anmine complex solution for 5 minutes to adsorb nickel ions, and then washed with water.

[Reduction process (S3)]

Then, it was immersed in 0.05 mol/L sodium borohydride aqueous solution at 25°C for 2 minutes to reduce nickel ions adsorbed on the polyimide surface in the step (S2) to deposit a metallic nickel film.

[Heat treatment process (S4)]

Thereafter, the polyimide film on which the nickel coating was formed was subjected to heat treatment in a nitrogen gas atmosphere at 250°C for 1 hour.

(2) Example 2

[Alkali reforming step (S1)]

A polyimide film (Upilex 50S, manufactured by Ube Kosan Co., Ltd.) was immersed in a 5 mol/L aqueous solution of potassium hydroxide at 50°C for 30 minutes, and thoroughly washed with water.

[Metal Replacement Step (S2)]

Separately, 0.2 mol/L of nickel sulfate hexahydrate was first dissolved in 300 mL of distilled water, then 600 mL of 25% ammonia water was added, and then the amount was 1 L with distilled water, containing 15% ammonia water and 0.2 mol/L of nickel sulfate. A nickel-anmine complex solution was prepared.

The polyimide film treated with alkali in the step (S1) was immersed in the nickel/anmine complex solution for 5 minutes to adsorb nickel ions, and then washed with water.

[Reduction process (S3)]

Subsequently, it was immersed in 0.05 mol/L sodium borohydride aqueous solution at 25°C for 2 minutes to reduce nickel ions adsorbed on the polyimide surface in the step (S2) to deposit a metallic nickel film.

[Heat treatment process (S4)]

Thereafter, the polyimide film on which the nickel coating was formed was subjected to heat treatment in a nitrogen gas atmosphere at 250°C for 1 hour.

(3) Example 3

[Alkali reforming step (S1)]

A polyimide film (Upilex 50S, manufactured by Ube Kosan Co., Ltd.) was immersed in a 5 mol/L aqueous solution of potassium hydroxide at 50°C for 30 minutes, and thoroughly washed with water.

[Metal Replacement Step (S2)]

Separately, 0.2 mol/L of nickel sulfate hexahydrate was once dissolved in 300 mL of distilled water, and then 400 mL of 25% aqueous ammonia was added, followed by 1 L of distilled water, containing 10% aqueous ammonia and 0.2 mol/L of nickel sulfate. A nickel-anmine complex solution was prepared.

The polyimide film treated with alkali in the step (S1) was immersed in the nickel/anmine complex solution for 5 minutes to adsorb nickel ions, and then washed with water.

[Reduction step (S3)]

Then, it was immersed in 0.05 mol/L sodium borohydride aqueous solution at 25°C for 2 minutes to reduce nickel ions adsorbed on the polyimide surface in the step (S2) to deposit a metallic nickel film.

(4) Example 4

[Alkali reforming step (S1)]

A polyimide film (Upilex 50S, manufactured by Ube Kosan Co., Ltd.) was immersed in a 5 mol/L aqueous solution of potassium hydroxide at 50°C for 30 minutes, and thoroughly washed with water.

[Metal Replacement Step (S2)]

Separately, 0.2 mol/L of nickel sulfate hexahydrate was once dissolved in 500 mL of distilled water, and then 5 mL of ethylenediamine was added, and then 0.07 mol/L of ethylenediamine and 0.2 mol/L of nickel sulfate were dissolved in 1 L of distilled water. A nickel complex solution containing was prepared.

The polyimide film treated with alkali in the step (S1) was immersed in the nickel complex solution for 5 minutes to adsorb nickel ions, and then washed with water.

[Reduction process (S3)]

Then, it was immersed in 0.05 mol/L sodium borohydride aqueous solution at 25°C for 2 minutes to reduce nickel ions adsorbed on the polyimide surface in the step (S2) to deposit a metallic nickel film.

[Heat treatment process (S4)]

Thereafter, the polyimide film on which the nickel coating was formed was subjected to heat treatment in a nitrogen gas atmosphere at 250°C for 1 hour.

(5) Example 5

[Alkali reforming step (S1)]

A polyimide film (Upilex 50S, manufactured by Ube Kosan Co., Ltd.) was immersed in a 5 mol/L aqueous solution of potassium hydroxide at 50°C for 30 minutes, and thoroughly washed with water.

[Metal Replacement Step (S2)]

Separately, 0.2 mol/L of nickel sulfate hexahydrate was once dissolved in 500 mL of distilled water, and then 10 mL of diethylenetriamine was added, and then 0.09 mol/L of diethylenetriamine and 0.2 mol/L of diethylenetriamine were dissolved in 1 L of distilled water. A nickel complex solution containing L nickel sulfate was prepared.

The polyimide film treated with alkali in the step (S1) was immersed in the nickel complex solution for 5 minutes to adsorb nickel ions, and then washed with water.

[Reduction process (S3)]

Then, it was immersed in 0.05 mol/L sodium borohydride aqueous solution at 25°C for 2 minutes to reduce nickel ions adsorbed on the polyimide surface in the step (S2) to deposit a metallic nickel film.

[Heat treatment process (S4)]

Thereafter, the polyimide film on which the nickel coating was formed was subjected to heat treatment in a nitrogen gas atmosphere at 250°C for 1 hour.

(6) Example 6

[Alkali reforming step (S1)]

A polyimide film (Kapton 200EN, manufactured by Toray DuPont Co., Ltd.) was immersed in a 0.5 mol/L potassium hydroxide aqueous solution at 40°C for 2 minutes, and washed sufficiently with water.

[Metal Replacement Step (S2)]

Separately, 0.001 mol/L of palladium chloride was once dissolved in 500 mL of water containing a small amount of hydrochloric acid, and then 8 mL of 25% aqueous ammonia was added, followed by 1 L of distilled water, and 0.2% aqueous ammonia and 0.001 mol/L of A palladium/anmine complex solution containing palladium chloride (adjusted to pH 4.5 with sulfuric acid) was prepared. Further, as described above, the colorless to light yellow transparent palladium-anmine complex is alkaline at the time of its formation, but the coordination function in the polyimide resin becomes smooth by acid treatment.

The polyimide film treated with alkali in the step (S1) was immersed in the palladium/anmin complex solution for 5 minutes to adsorb palladium ions, and then washed with water.

[Reduction process (S3)]

Then, it was immersed in 0.1 mol/L of dimethylamineborane aqueous solution at 40°C for 3 minutes to reduce the palladium ion adsorbed on the polyimide surface in the step (S2) to deposit a metal palladium film.

[Electroless plating process (S5)]

Then, using the electroless nickel plating solution having the composition shown in (a) below, electroless plating was performed under the conditions shown in (b) below, and a nickel plating film was deposited on the palladium film formed on the polyimide film.

(a) composition of electroless nickel plating solution

Nickel sulfate (as ^{Ni 2+} ) 0.15 mol/L

Sodium hypophosphite 0.10 mol/L

Sodium acetate 0.15 mol/L

pH (adjusted with 24% aqueous sodium hydroxide solution) 4.5

(b) Electroless plating conditions

Plating bath temperature: 80℃

Plating time: 2 minutes

Plating film thickness: 0.5μm

[Heat treatment process (S4)]

Thereafter, the polyimide film on which the nickel coating was formed was subjected to heat treatment in an air atmosphere at 120°C for 2 minutes.

(7) Example 7

[Alkali reforming step (S1)]

A polyimide film (Kapton 200EN, manufactured by Toray DuPont Co., Ltd.) was immersed in a 0.5 mol/L potassium hydroxide aqueous solution at 40°C for 2 minutes, and washed sufficiently with water.

[Metal Replacement Step (S2)]

Separately, 0.001 mol/L of palladium chloride was once dissolved in 500 mL of water containing a small amount of hydrochloric acid, and then 8 mL of 25% aqueous ammonia was added, followed by 1 L of distilled water, and 0.2% aqueous ammonia and 0.001 mol/L of A palladium/anmine complex solution containing palladium chloride (adjusted to pH 4.5 with sulfuric acid) was prepared.

The polyimide film treated with alkali in the step (S1) was immersed in the palladium/anmin complex solution for 5 minutes to adsorb palladium ions, and then washed with water.

[Reduction process (S3)]

Then, it was immersed in 0.1 mol/L of dimethylamineborane aqueous solution at 40°C for 3 minutes to reduce the palladium ion adsorbed on the polyimide surface in the step (S2) to deposit a metal palladium film.

[Electroless plating process (S5)]

Subsequently, electroless plating was performed under the same conditions using the same electroless nickel plating solution as in Example 6, and a nickel plating film was deposited on the palladium film formed on the polyimide film.

(8) Example 8

[Alkali reforming step (S1)]

A polyimide film (Kapton 200EN, manufactured by Toray DuPont Co., Ltd.) was immersed in a 0.5 mol/L potassium hydroxide aqueous solution at 40°C for 2 minutes, and washed sufficiently with water.

[Metal Replacement Step (S2)]

Separately, 0.001 mol/L of palladium chloride was once dissolved in 500 mL of water containing a small amount of hydrochloric acid, and then 0.5 mL of ethylenediamine was added, and 0.007 mol/L of ethylenediamine and 0.001 mol of 0.007 mol/L of ethylenediamine were dissolved in 1 L of distilled water. A palladium complex solution containing /L palladium chloride was prepared.

The polyimide film treated with alkali in the above step (S1) was immersed in the palladium complex solution for 5 minutes to adsorb palladium ions, and then washed with water.

[Reduction process (S3)]

Then, it was immersed in 0.1 mol/L of dimethylamineborane aqueous solution at 40°C for 3 minutes to reduce the palladium ion adsorbed on the polyimide surface in the step (S2) to deposit a metal palladium film.

[Electroless plating process (S5)]

Subsequently, electroless plating was performed under the same conditions using the same electroless nickel plating solution as in Example 6, and a nickel plating film was deposited on the palladium film formed on the polyimide film.

[Heat treatment process (S4)]

Thereafter, the polyimide film on which the nickel coating was formed was subjected to heat treatment in an air atmosphere at 120°C for 20 minutes.

(9) Example 9

[Alkali reforming step (S1)]

A polyimide film (Kapton 200EN, manufactured by Toray DuPont Co., Ltd.) was immersed in a 5 mol/L potassium hydroxide aqueous solution at 50°C for 5 minutes, and washed sufficiently with water.

[Metal Replacement Step (S2)]

Separately, 0.2 mol/L of copper sulfate pentahydrate was once dissolved in 300 mL of distilled water, then 400 mL of 25% ammonia water was added, and then the amount was 1 L with distilled water. Copper containing 10% ammonia water and 0.2 mol/L of copper sulfate ㆍAnmin complex solution was prepared. In addition, the copper-anmine complex solution exhibited a deep blue color.

The polyimide film treated with alkali in the step (S1) was immersed in the copper/anmine complex solution for 5 minutes to adsorb copper ions, and then washed with water.

[Reduction process (S3)]

Then, it was immersed in 0.05 mol/L sodium borohydride aqueous solution at 25°C for 5 minutes to reduce copper ions adsorbed on the polyimide surface in the step (S2) to deposit a metallic copper film.

[Heat treatment process (S4)]

Thereafter, the polyimide film on which the copper film was formed was subjected to heat treatment in a nitrogen gas atmosphere at 250°C for 1 hour.

(10) Example 10

[Alkali reforming step (S1)]

A polyimide film (Kapton 200EN, manufactured by Toray DuPont Co., Ltd.) was immersed in a 5 mol/L potassium hydroxide aqueous solution at 50°C for 5 minutes, and washed sufficiently with water.

[Metal Replacement Step (S2)]

Separately, 0.2 mol/L of copper sulfate pentahydrate was once dissolved in 300 mL of distilled water, then 400 mL of 25% ammonia water was added, and then the amount was 1 L with distilled water. Copper containing 10% ammonia water and 0.2 mol/L of copper sulfate ㆍAnmin complex solution was prepared.

The polyimide film treated with alkali in the step (S1) was immersed in the copper/anmine complex solution for 5 minutes to adsorb copper ions, and then washed with water.

[Reduction process (S3)]

Then, it was immersed in 0.05 mol/L sodium borohydride aqueous solution at 25°C for 5 minutes to reduce copper ions adsorbed on the polyimide surface in the step (S2) to deposit a metallic copper film.

(11) Example 11

[Alkali reforming step (S1)]

A polyimide film (Kapton 200EN, manufactured by Toray DuPont Co., Ltd.) was immersed in a 5 mol/L potassium hydroxide aqueous solution at 50°C for 5 minutes, and washed sufficiently with water.

[Metal Replacement Step (S2)]

Separately, 0.2 mol/L of copper sulfate pentahydrate was once dissolved in 500 mL of distilled water, then 5 mL of ethylenediamine was added, and then the amount was 1 L with distilled water, containing 0.07 mol/L of ethylenediamine and 0.2 mol/L of copper sulfate. A copper-anmine complex solution was prepared.

The polyimide film treated with alkali in the step (S1) was immersed in the copper/anmine complex solution for 5 minutes to adsorb copper ions, and then washed with water.

[Reduction process (S3)]

Then, it was immersed in 0.05 mol/L sodium borohydride aqueous solution at 25°C for 5 minutes to reduce copper ions adsorbed on the polyimide surface in the step (S2) to deposit a metallic copper film.

[Heat treatment process (S4)]

Thereafter, the polyimide film on which the copper film was formed was subjected to heat treatment in a nitrogen gas atmosphere at 250°C for 1 hour.

(12) Example 12

[Alkali reforming step (S1)]

A polyimide film (Kapton 200EN, manufactured by Toray DuPont Co., Ltd.) was immersed in a 5 mol/L potassium hydroxide aqueous solution at 50°C for 5 minutes, and washed sufficiently with water.

[Metal Replacement Step (S2)]

Separately, 0.2 mol/L of cobalt sulfate heptahydrate was once dissolved in 300 mL of distilled water, then 400 mL of 25% aqueous ammonia was added, and then the amount was 1 L with distilled water, containing 10% aqueous ammonia and 0.2 mol/L of cobalt sulfate. A cobalt-anmine complex solution was prepared. In addition, the cobalt-anmine complex solution exhibited a dark brown color.

The polyimide film treated with alkali in the step (S1) was immersed in the cobalt/anmine complex solution for 5 minutes to adsorb cobalt ions, and then washed with water.

[Reduction process (S3)]

Subsequently, it was immersed in 0.05 mol/L sodium borohydride aqueous solution at 25°C for 5 minutes to reduce cobalt ions adsorbed on the polyimide surface in the step (S2) to deposit a metallic cobalt film.

[Heat treatment process (S4)]

Thereafter, the polyimide film on which the cobalt coating was formed was subjected to heat treatment in a nitrogen gas atmosphere at 250°C for 1 hour.

(13) Example 13

[Alkali reforming step (S1)]

A polyimide film (Kapton 200EN, manufactured by Toray DuPont Co., Ltd.) was immersed in a 5 mol/L potassium hydroxide aqueous solution at 50°C for 5 minutes, and washed sufficiently with water.

[Metal Replacement Step (S2)]

Separately, 0.2 mol/L of cobalt sulfate heptahydrate was once dissolved in 300 mL of distilled water, and then 400 mL of 25% aqueous ammonia was added, followed by 1 L of distilled water, containing 10% aqueous ammonia and 0.2 mol/L of cobalt sulfate. A cobalt-anmine complex solution was prepared.

The polyimide film treated with alkali in the step (S1) was immersed in the cobalt/anmine complex solution for 5 minutes to adsorb cobalt ions, and then washed with water.

[Reduction process (S3)]

Then, it was immersed in 0.05 mol/L sodium borohydride aqueous solution at 25°C for 5 minutes to reduce the cobalt ions adsorbed on the polyimide surface in the step (S2) to deposit a metallic cobalt film.

(14) Example 14

Based on Example 1, alkali reforming process (S1) → metal replacement process (S2) → reduction process (S3) → heat treatment process (S4) was performed under the same conditions as in Example 1. The metal film deposited on the polyimide film is a nickel film.

[Electroplating process (S5)]

Then, using the electrolytic copper plating solution having the composition shown in (a) below, electroplating was performed under the conditions shown in (b) below, and a copper plating film was deposited on the nickel film formed on the polyimide film.

(a) Composition of electrolytic copper plating solution

Copper sulfate pentahydrate (as ^{Cu 2+} ) 0.8 mol/L

Sulfuric acid 1.0 mol/L

Hydrochloric acid 0.1 mmol/L

Bis(3-sulfonpropyl)disulfide 1.0mg/L

Polyethylene glycol (molecular weight 4000) 1.0g/L

Polyethyleneimine 3.0mg/L

(b) electroplating conditions

Plating bath temperature: 25℃

Current density: 1A/dm ²

Plating time: 5 minutes

Plated film thickness: 1.0μm

(15) Example 15

Based on Example 6, alkali reforming step (S1) → metal replacement step (S2) → reduction step (S3) → electroless plating step (S5) → heat treatment step (S4) under the same conditions as Example 6 performed. The metal film deposited on the polyimide film is a palladium film, and the film formed by electroless plating is a nickel film.

[Electroplating process (S5)]

Subsequently, electroplating was performed under the same conditions using the same electrolytic copper plating solution as in Example 14, and a copper film was deposited on the nickel film formed on the polyimide film.

(16) Example 16

Based on Example 7, an alkali reforming process (S1) → metal replacement process (S2) → reduction process (S3) → electroless plating process (S5) was performed under the same conditions as in Example 7. The metal film deposited on the polyimide film is a palladium film, and the film formed by electroless plating is a nickel film.

[Electroplating process (S5)]

Subsequently, electroplating was performed under the same conditions using the same electrolytic copper plating solution as in Example 14, and a copper film was deposited on the nickel film formed on the polyimide film.

(17) Example 17

Based on Example 9, alkali reforming process (S1) → metal replacement process (S2) → reduction process (S3) → heat treatment process (S4) was performed under the same conditions as in Example 9. The metal film deposited on the polyimide film is a copper film.

[Electroplating process (S5)]

Subsequently, electroplating was performed under the same conditions using the same electrolytic copper plating solution as in Example 14, and a copper film was deposited on the copper film formed on the polyimide film in the same way.

(18) Example 18

Based on Example 12, alkali reforming process (S1) → metal replacement process (S2) → reduction process (S3) → heat treatment process (S4) was performed under the same conditions as in Example 12. The metal film deposited on the polyimide film is a cobalt film.

[Electroplating process (S5)]

Subsequently, electroplating was performed under the same conditions using the same electrolytic copper plating solution as in Example 14, and a copper film was deposited on the cobalt film formed on the polyimide film.

(19) Comparative Example 1

[Alkali reforming step (S1)]

A polyimide film (Upilex 50S, manufactured by Ube Kosan Co., Ltd.) was immersed in a 5 mol/L aqueous solution of potassium hydroxide at 50°C for 30 minutes, and thoroughly washed with water.

[Metal Replacement Step (S2)]

Separately, after dissolving 0.2 mol/L of nickel sulfate hexahydrate once in 500 mL of distilled water, a nickel solution containing 0.2 mol/L of nickel sulfate was prepared by dissolving 1 L of distilled water.

The polyimide film treated with alkali in the step (S1) was immersed in the nickel solution for 5 minutes to adsorb nickel ions, and then washed with water.

[Reduction process (S3)]

Subsequently, it is immersed for 2 minutes in an aqueous solution of 0.05 mol/L sodium borohydride at 25°C, reducing the nickel ions adsorbed on the polyimide surface in the step (S2), washing with water and drying, and depositing a metallic nickel film. made it

[Heat treatment process (S4)]

Thereafter, the polyimide film on which the nickel coating was formed was subjected to heat treatment in a nitrogen gas atmosphere at 250°C for 1 hour.

(20) Comparative Example 2

[Alkali reforming step (S1)]

A polyimide film (Upilex 50S, manufactured by Ube Kosan Co., Ltd.) was immersed in a 5 mol/L aqueous solution of potassium hydroxide at 50°C for 30 minutes, and thoroughly washed with water.

[Metal Replacement Step (S2)]

Separately, 0.2 mol/L of nickel sulfate hexahydrate was once dissolved in 500 mL of distilled water, and then 20 g of EDTA-4Na was added, and 0.07 mol/L of EDTA-4Na and 0.2 mol/L of 0.07 mol/L of EDTA-4Na and 0.2 mol/L of distilled water were added in 1 L quantity. A nickel solution containing nickel sulfate was prepared.

The polyimide film treated with alkali in the step (S1) was immersed in the nickel solution for 5 minutes, and then washed with water.

[Reduction process (S3)]

Then, it was immersed in 0.05 mol/L sodium borohydride aqueous solution at 25 degreeC for 2 minutes, but the metal nickel film was not obtained.

(21) Comparative Example 3

[Alkali reforming step (S1)]

A polyimide film (Upilex 50S, manufactured by Ube Kosan Co., Ltd.) was immersed in a 5 mol/L aqueous solution of potassium hydroxide at 50°C for 30 minutes, and thoroughly washed with water.

[Metal Replacement Step (S2)]

Separately, 0.2 mol/L of nickel sulfate hexahydrate was once dissolved in 500 mL of distilled water, and then 5.3 g of glycine was added, and 0.07 mol/L of glycine and 0.2 mol/L of nickel sulfate were dissolved in 1 L of distilled water. A nickel solution was prepared.

The polyimide film treated with alkali in the step (S1) was immersed in the nickel solution for 5 minutes, and then washed with water.

[Reduction process (S3)]

Then, it was immersed in 0.05 mol/L sodium borohydride aqueous solution at 25 degreeC for 2 minutes, but the metal nickel film was not obtained.

(22) Comparative Example 4

Based on Comparative Example 1, an alkali reforming process (S1) → metal replacement process (S2) → reduction process (S3) → heat treatment process (S4) was performed under the same conditions as Comparative Example 1. The metal film deposited on the polyimide film is a nickel film.

[Electroplating process (S5)]

Subsequently, electroplating was performed under the same conditions using the same electrolytic copper plating solution as in Example 14, and a copper film was deposited on the nickel film formed on the polyimide film.

(23) Comparative Example 5

[Alkali reforming step (S1)]

A polyimide film (Kapton 200EN, manufactured by Toray DuPont Co., Ltd.) was immersed in a 0.5 mol/L potassium hydroxide aqueous solution at 40°C for 2 minutes, and washed sufficiently with water.

[Metal Replacement Step (S2)]

Separately, 0.001 mol/L of palladium chloride was once dissolved in 500 mL of water containing a small amount of hydrochloric acid, and then a 1-liter volume of distilled water was used to prepare a palladium solution containing 0.001 mol/L of palladium chloride.

The polyimide film treated with alkali in the above step (S1) was immersed in the palladium solution for 5 minutes to adsorb palladium ions, and then washed with water.

[Reduction step (S3)]

Then, it was immersed in 0.1 mol/L of dimethylamineborane aqueous solution at 40°C for 3 minutes to reduce the palladium ion adsorbed on the polyimide surface in the step (S2) to deposit a metal palladium film.

[Electroless plating process (S5)]

Subsequently, electroless plating was performed under the same conditions using the same electroless nickel plating solution as in Example 6, and a nickel plating film was deposited on the palladium film formed on the polyimide film.

[Heat treatment process (S4)]

Thereafter, the polyimide film on which the nickel coating was formed was subjected to heat treatment in an air atmosphere at 120°C for 20 minutes.

(24) Comparative Example 6

[Alkali reforming step (S1)]

A polyimide film (Kapton 200EN, manufactured by Toray DuPont Co., Ltd.) was immersed in a 0.5 mol/L potassium hydroxide aqueous solution at 40°C for 2 minutes, and washed sufficiently with water.

[Metal Replacement Step (S2)]

Separately, 0.001 mol/L of palladium chloride was once dissolved in 500 mL of water containing a small amount of hydrochloric acid, and then 20 g of EDTA-4Na was added, and 0.07 mol/L of EDTA-4Na and 0.001 A palladium complex solution containing mol/L of palladium chloride was prepared (the phase of the solution was slightly lacking in uniformity).

The polyimide film treated with alkali in the step (S1) was immersed in the palladium complex solution for 5 minutes, and then washed with water.

[Reduction process (S3)]

Then, it was immersed in 0.1 mol/L of dimethylamineborane aqueous solution at 40 degreeC for 3 minutes, but the metal palladium film was not obtained.

(25) Comparative Example 7

Based on Comparative Example 5, under the same conditions as Comparative Example 5, alkali reforming step (S1) → metal replacement step (S2) → reduction step (S3) → electroless plating step (S5) → heat treatment step (S4) performed. The metal film deposited on the polyimide film is a palladium film, and the film formed by electroless plating is a nickel film.

[Electroplating process (S5)]

Subsequently, electroplating was performed under the same conditions using the same electrolytic copper plating solution as in Example 14, and a copper film was deposited on the nickel film formed on the polyimide film.

≪Appearance evaluation test example of metal film≫

Example 1 finally obtained on a polyimide film by sequentially carrying out steps (S1) to (S3) in the present invention, or selectively carrying out step (S4) and/or step (S5) in addition. About the metal coating of -18 and the metal coating of Comparative Examples 1-7, the external appearance was evaluated based on the following evaluation criteria.

In addition, the evaluation of the said external appearance was made into the object of the metal film finally obtained. Therefore, for example, in Example 6, after forming a palladium film on the polyimide film, the nickel film is laminated by electroless plating, so the target for external appearance evaluation is the nickel film.

(Evaluation standard)

○: The film was uniform and there was no bias in thickness.

(triangle|delta): Inclination of the thickness was confirmed in the film.

Х: No film was deposited.

≪Example of Test Example for Evaluating Adhesion of Metal Coating to Polyimide Film≫

Example 1 finally obtained on a polyimide film by sequentially carrying out steps (S1) to (S3) in the present invention, or selectively carrying out step (S4) and/or step (S5) in addition. Adhesion strength was measured for the metal coatings of Examples 14 to 18 and Comparative Examples 4 and 7 among the metal coatings of ~18 and among the metal coatings of Comparative Examples 1 to 7. Adhesion strength cannot be measured when the film thickness of the metal film increases to some extent, so the metal film of Examples 14 to 18 and Comparative Examples 4 and 7, which were thickened by performing the electroplating step (S5) was measured for.

Using a tensile strength tester (EZ-SX 500N, manufactured by Shimadzu Corporation), the metal film formed in a width of 10 mm was peeled off at an angle of 90° from the polyimide film, and the adhesion strength (kN/m) was measured. measured.

≪Test results on appearance and adhesion of metal film≫

In Table 3 below, the results of the appearance evaluation and adhesion evaluation (adhesion strength (kN/m)) of the metal film are summarized and shown. In addition, as described above, since the adhesion evaluation was performed only on the metal coatings of Examples 14 to 18 and Comparative Examples 4 and 7, other Examples and Comparative Examples were marked with "--".

Test result Exterior Adhesion strength (kN/m) Example 1 ○ -- 2 ○ -- 3 ○ -- 4 ○ -- 5 ○ -- 6 ○ -- 7 ○ -- 8 ○ -- 9 ○ -- 10 ○ -- 11 ○ -- 12 ○ -- 13 ○ -- 14 ○ 0.6 15 ○ 0.7 16 ○ 0.4 17 ○ 0.8 18 ○ 0.5 Comparative Example 1 △ -- 2 × -- 3 × -- 4 △ 0.1 5 △ -- 6 × -- 7 △ 0.1

≪Comprehensive evaluation of the appearance and adhesion of the metal film≫

Hereinafter, the evaluation of the test results of Table 3 will be described.

First, in Comparative Examples 1 to 4, the metal reduced in step (S3) is nickel.

Comparative Example 1 is an example in which a nickel film is formed on a polyimide film without complexing the metal in the metal replacement step (S2) (ie, without using a complexing agent), and the appearance of the film is biased in thickness this has been confirmed Comparative Example 2 is an example using EDTA-4Na in the metal replacement step (S2), and Comparative Example 3 is an example using the same glycine, but no nickel film was deposited in either case.

Therefore, in the metal replacement step (S2), nickel ions are metal complexed using a predetermined N compound such as ammonia and ethylenediamine, and then a nickel film is formed on the polyimide film. Comparison with Examples 1 to 5, Comparing Examples 1 to 3, the following was found. That is, in order to smoothly deposit a metal film on the polyimide film and to form a good film, it is necessary to complex the metal ion to act, and furthermore, in the complexation, in the present invention, ammonia and ethylene It is necessary to select a predetermined N compound such as diamine, and even when an N compound other than those specified in the present invention such as EDTA-4Na or glycine is used, a good metal film cannot be formed.

In Comparative Example 4, based on Comparative Example 1, electrolytic copper plating was applied to the nickel coating after heat treatment. However, the appearance of the metal coating also showed a bias in thickness, and the adhesion strength was 0.1 kN/m, indicating that the adhesion was good. It wasn't good. On the other hand, in Example 14 in which a nickel-anmine complex is formed in the metal replacement step (S2), a nickel film is formed in the reduction step (S3), and the nickel film is subjected to electrolytic copper plating after the same heat treatment, the metal film The adhesive strength of was 0.6 kN/m, and the adhesiveness was remarkably shown when compared to Comparative Example 4 (0.1 kN/m). Therefore, as in the present invention, when a predetermined N compound such as ammonia or ethylenediamine is reacted to complex metal ions in the metal replacement step (S2), the adhesion of the metal film to the polyimide film can be significantly improved. can know that

On the other hand, Comparative Examples 5 to 7 are examples in which the metal reduced in step (S3) is palladium.

Comparative Example 5 is an example in which a palladium film is formed without metal complexation in the metal replacement step (S2) and a nickel film is laminated by electroless plating, and the thickness of the film is biased. Comparative Example 6 is an example in which EDTA-4Na was used in the metal replacement step (S2), but no palladium film was deposited.

Therefore, in the metal replacement step (S2), ammonia and ethylenediamine were used to form a metal complex with palladium ions, and then Examples 6 to 8 in which a palladium film was formed on the polyimide film and Comparative Examples 5 to 6 were compared. Looking at it, I could see the following: That is, in order to deposit a metal film on the polyimide film smoothly and to form a film well, it is necessary to complex the metal ion to act, and furthermore, for the complexation, in the present invention, ammonia and ethylenediamine It is necessary to select a predetermined N compound, such as EDTA-4Na, etc., and even if an N compound other than those stipulated by the present invention, such as EDTA-4Na, is used, a good metal film cannot be formed.

In Comparative Example 7, based on Comparative Example 5, electrolytic copper plating was applied to the nickel coating after heat treatment, but the appearance of the coating was also found to be biased in thickness, and the adhesion of the coating was poor. On the other hand, a nickel film is laminated through the formation of a palladium/anmin complex in the metal replacement step (S2) and the formation of a palladium film in the reduction step (S3), and after the same heat treatment, the nickel film is subjected to electrolytic copper plating. In Example 15, the adhesion strength of the metal film was 0.7 kN/m, and compared to Comparative Example 7 (0.1 kN/m), adhesion was remarkably exhibited. Therefore, as in the present invention, when a predetermined N compound such as ammonia or ethylenediamine is reacted to complex metal ions in the metal replacement step (S2), the adhesion of the metal film to the polyimide film can be significantly improved. can know that

Further, Example 16 is based on Example 7 and is an example in which electrolytic copper plating is performed without heat treatment, but the adhesion strength of the metal film is 0.4 kN/m, and Comparative Example 7 (0.1 kN/m) in which electrolytic copper plating is performed after heat treatment ), it shows a clear superiority. From this, it was found that metal complexation by a predetermined N compound such as ammonia in the metal replacement step (S2) is important for improving the adhesion.

Hereinafter, Examples 1 to 18 will be described in detail.

First, Examples 1 to 5 are examples in which the reduced metal in the reduction step (S3) is nickel, and the nickel film can be formed satisfactorily regardless of the presence or absence of heat treatment. However, in the alkali reforming step (S1), the polyimide film is immersed under the condition that the concentration of the aqueous solution of potassium hydroxide is 5 mol/L for 30 minutes, the polyimide is sufficiently ring-opened, and the nickel ion is ionized in the metal replacement step (S2). Substitution of was performed. Accordingly, the heat treatment conditions were set to 250 ° C. for 1 hour (see Examples 1 and 2 and Examples 4 and 5).

In Examples 1 and 2, the ammonia concentration in the metal replacement step (S2) was changed, but since there was no difference in the appearance of the metal film, it can be judged that ammonia does not need to be used in a very high concentration.

In Examples 1 to 5, the complexing agent used in the metal replacement step (S2) was changed to ammonia, ethylenediamine, and diethylenetriamine, but since the appearance of the metal film was good, metal complexation with these N compounds It can be judged that there is no difference in the validity of

Subsequently, Examples 6 to 8 are examples in which the reduced metal in the reduction step (S3) is palladium, and the palladium film could be formed satisfactorily regardless of the presence or absence of heat treatment. Further, in the metal complexation in the metal replacement step (S2), a palladium film could be formed satisfactorily regardless of ammonia or ethylenediamine.

In the case of using palladium as the metal of the metal film formed on the surface of the polyimide film, in the alkali reforming step (S1), the concentration of the aqueous solution of potassium hydroxide is 0.5 mol/L and the polyimide film is immersed for 2 minutes, Polyimide is ring-opened and alkali-modified under weaker conditions than in the case of nickel. Therefore, in the heat treatment step (S4), unlike the case of Examples 1 to 5 (nickel), the polyimide can be ring-closed satisfactorily under the condition of 120°C for 20 minutes.

Examples 9 to 11 are examples in which the reduced metal in the reduction step (S3) is copper, regardless of whether or not heat treatment is performed, or in the case of metal complexation in the metal substitution step (S2), regardless of ammonia or ethylenediamine, A copper film could be formed satisfactorily.

Similarly, Examples 12 to 13 are examples in which the reduced metal in the reduction step (S3) is cobalt, and the cobalt film could be formed satisfactorily regardless of the presence or absence of heat treatment.

Further, in the case of using these copper and cobalt as the metal of the metal film formed on the surface of the polyimide film, the conditions of the alkali reforming step (S1) and heat treatment step (S4) are the same as in Examples 1 to 5 using nickel. complied.

On the other hand, in Examples 14 to 18, after forming each metal film of nickel, palladium, copper, and cobalt on the polyimide film in the reduction step (S3), heat treatment is performed (Examples 14 to 15 and 17 to 18), or , This is an example in which a copper film is laminated by electroplating without heat treatment (Example 16).

In the case of heat treatment, the adhesion strength of the copper electrodeposition film to the polyimide was 0.5 to 0.8 kN/m, and the metal replacement process (S2) was performed without metal complexation. Compared to Comparative Example 7 (0.1 kN/m), significant superiority was shown.

Further, in the case of Example 16 without heat treatment, the adhesion strength of the copper electrodeposition film to polyimide was 0.4 kN/m, and the metal replacement step (S2) was performed without heat treatment and without metal complexation. In addition to showing clear superiority over Comparative Example 4 (0.1 kN/m), it also showed clear superiority to Comparative Example 7 (0.1 kN/m) in which the metal replacement step (S2) was performed without heat treatment and metal complexation. showed

According to the method for forming a metal film of the present invention, a metal film can be formed on a polyimide resin with excellent adhesion, and the polyimide resin having such a metal film is useful as a circuit forming material for electronic devices and the like.

Claims (6)

(S1) a step of modifying the surface of the polyimide resin by bringing it into contact with an alkaline aqueous solution;
(S2) treating the modified polyimide resin with an aqueous solution containing at least one soluble salt of a metal selected from the group consisting of nickel, copper, palladium, and cobalt, followed by metal replacement;
(S3) reducing the metal ion substituted with the polyimide resin with a reducing agent;
including,
In the step (S2), at least one compound containing a basic nitrogen atom selected from the group consisting of ammonia, monoethylene polyamines, polyethylene polyamines, monoethanol amines, and polyethanol amines coexists with the metal soluble salt. The modified polyimide resin is treated with an aqueous solution, and a basic nitrogen atom-containing compound complex of a metal selected from the group consisting of nickel, copper, palladium, and cobalt is coordinated to the polyimide resin. A method of forming a metal film. According to claim 1
A method for forming a metal film on a polyimide resin, characterized in that the basic nitrogen atom-containing compound is at least one selected from ammonia, ethylenediamine, diethylenetriamine, and triethanolamine. According to claim 1 or 2,
After the step (S1), the step (S2), and the step (S3),
(S4) heat treatment of the polyimide resin; and/or
(S5) a step of forming a conductive film by electroless plating and/or electroplating on the metal film of the polyimide resin obtained by reduction in the step (S3);
A method for forming a metal film on a polyimide resin, comprising: According to claim 3,
In the step (S4), the method for forming a metal film on a polyimide resin, characterized in that the heat treatment temperature is 80 ° C. to 300 ° C. According to claim 3,
In the step (S5), at least one metal selected from nickel and copper is subjected to electroless plating and/or electroplating in a single layer or multiple layers. According to claim 4,
In the step (S5), at least one metal selected from nickel and copper is subjected to electroless plating and/or electroplating in a single layer or multiple layers.