JP2003031924A - Metal circuit forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive high-molecular complex used for easily forming a metal film or a metal circuit high in adhesion strength to the surface of a base, without using expensive apparatuses, and to provide a metal circuit forming method by the use of the same. SOLUTION: In a method for forming a metal circuit on the surface of a base, a polyimide precursor solution 3 is applied on the surface of a base 1 and dried up, the polyimide precursor located on the metal film or the metal circuit is made to react on palladium ions, to be turned into a photosensitive high-molecular complex thin film 5, and the high-molecular complex film 5 is irradiated with ultraviolet rays 10, in the presence of a hydrogen donor to turn palladium ions into metal, palladium which is catalystically active to electroless plating, and a metal film or a metal circuit is formed through electroless plating, electroplating, and imidization by heating. A thin film layer, having a structure where plating metal is partially bonded to a polyimide precursor, is formed, so that the metal film or the metal circuit is improved in adhesion strength by the anchor effect of the above thin film layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a substrate having a metal circuit for microfabrication.

[0002]

2. Description of the Related Art Copper-clad polyimide base materials are used as flexible printed circuit boards, TAB materials and CSP materials, but with the miniaturization of equipment and the increase in signal transmission speed, high-density fine wiring and fine vias have been used. On the other hand, there is an increasing demand for a built-up board in which a plurality of thin film circuit boards are laminated and via-connected, etc.

For this reason, there is an increasing demand for metal-clad polyimide base materials having good workability.

Conventionally, in order to obtain a metal-clad polyimide base material, a polyimide surface is subjected to a dry pretreatment such as ion bombardment or corona discharge, and then a base metal such as nickel or chromium is deposited by sputtering, and a metal is deposited on the base metal. A method of forming a metal film by performing electroless plating and electrolytic plating is adopted. However, this method requires expensive equipment in order to perform the pretreatment and the sputtering treatment for forming the underlayer conductor in a vacuum, and thus the mass productivity is low and the cost is high, which is industrially very advantageous. It is hard to say the method.

On the other hand, as a method for producing a copper-clad polyimide by catalyst addition and electroless plating or electrolytic plating after modification of the polyimide surface by pretreatment without dry pretreatment or sputtering treatment, the surface of the polyimide film is treated with an alkali. Method of hydrolyzing to polyamic acid, adsorbing copper sulfate or palladium chloride, and then irradiating ultraviolet rays of a low-pressure mercury lamp with sodium formate as a reducing agent (13th Annual Conference of Japan Institute of Electronics Packaging P.183, 1999) Has been reported.

However, the above-mentioned method has a problem that not only the time required for the formation of catalyst nuclei by ultraviolet irradiation is very long, but also the decomposition of the reducing agent produces NaOH to become alkaline, which deteriorates the polyimide itself. Further, since the metal layer formed is limited to only the polyimide surface and the so-called anchor effect cannot be expected, there is a problem that only a low adhesion strength is usually obtained.

Therefore, as a means for obtaining the anchor effect, a method of forming a coating film in which a salt of a noble metal is dissolved on the surface of an object to be plated and then reducing it with a reducing gas such as hydrogen, CO, H ₂ S ( (Japanese Patent Publication No. 5-61296) or a method of directly forming a plating base by a plating reducing agent (USP).
No. 3,523,824), the former method using a reducing gas has many problems as a method for industrially producing an electronic material in terms of safety such as explosion and toxicity of the reducing gas. In the latter method, there are problems in the plating density, the variation adhesion strength, and the like. As a method for improving them, JP-A-5-306469 proposes a method of combining a metal compound which can be directly reduced with a reducing agent and a metal compound which can be reduced only by contact in order to enhance the anchor effect.

[0008]

However, in the above-mentioned method of reducing a metal compound with a reducing agent in the course of the plating reaction, in order to obtain a highly dense metal plating surface, addition of a reducible metal compound is required. The amount required is very large, about 200 parts by weight per 100 parts by weight of the resin, and the amount of the inorganic compound in the resin is too large, resulting in the loss of the original properties of the resin. It is difficult to reduce the metal compound into a resin film, and the metal compound that is only catalytically reduced remains in the resin film without being reduced, and there is a problem in the insulation property such that metal ion migration is likely to occur.

Therefore, in order to solve the problems found in the above-mentioned methods, the present inventors have proposed that the polyamic acid-type polyimide resin precursor should be treated with an inorganic acid salt of palladium, an organic acid salt or a palladium organic carbonyl complex at room temperature. Reacting to form a polymer complex, and further in the polymer complex,
We found that the palladium ion in the complex is a photosensitive polymer complex that is reduced to palladium metal by UV irradiation in the presence of a hydrogen donor, and further forms a photosensitive polymer complex thin film composed of polyamic acid and palladium. After the photosensitive polymer complex thin film is irradiated with ultraviolet rays, electroless plating is performed to form a metal thin film layer in which a polyimide resin precursor and a metal are integrated as shown in the conceptual diagram of FIG. It has been found that it is possible to form a substrate having

Compared with the conventional method, the present invention does not require steps such as liquid preparation, viscosity control, and wet coating at the time of forming a metal circuit, and the number of steps is simple and the operation is low in cost.
It is intended to provide a method for forming a metal circuit having high adhesion strength with a metal on various base materials.

[0011]

In order to solve the above-mentioned problems, in the present invention, at least the step of forming a polyimide resin precursor layer on a substrate as described in claim 1, and the polyimide resin. A step of forming a photosensitive polymer complex thin film in which a precursor and a palladium ion form a complex;
And a step of forming a metal circuit on the photosensitive polymer complex thin film.

Further, a photosensitive polymer complex thin film is formed by immersing a substrate having a polyimide resin precursor layer in an aqueous solution of an inorganic acid salt of palladium or a solution of an organic acid salt or an organic complex. Is.

As the palladium ion, an aqueous solution of an inorganic acid salt of palladium or a solution of an organic acid salt or an organic complex is used, and as a hydrogen donor, water, alcohol or an aqueous solution of alcohol is used, and as a substrate, a resin, a ceramic,
A base material made of at least one of silicon and metal is used.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows one embodiment of a metal circuit forming method according to the present invention.

After the polyimide resin precursor solution is applied onto the base material 2 and dried to form the polyimide resin precursor thin film 3 (FIG. 1A), the base material 1 is dipped in a solution 4 containing palladium ions. (FIG. 1 (b)), a polyimide resin precursor and palladium ions are contacted and reacted to form a photosensitive polymer complex thin film 5 (FIG. 1 (c)), and then the photosensitive polymer complex thin film 5 is formed. Photosensitive resin 6 is applied (FIG. 1 (d)),
The resin pattern mask 7 in which the photosensitive polymer complex thin film 5 of the metal circuit portion 8 is exposed by exposing and developing the photosensitive resin 6
Are formed (FIG. 1E).

Then, in the presence of a hydrogen donor 10 such as water, alcohol or an aqueous alcohol solution, ultraviolet rays 11 are irradiated through the resin pattern mask 7 to reduce palladium ions to palladium metal to form a plating base nucleus. (FIG. 1 (f)), the plating base metal layer 12 is formed by electroless plating (FIG. 1 (g)), and the metal circuit layer 13 having a predetermined film thickness is further formed on the plating base metal layer 12 by electrolytic plating. Are formed (FIG. 1 (h)).

Then, the resin pattern mask 7 is peeled off (FIG. 1 (i)), and the photosensitive polymer complex thin film 5 of the non-metal circuit portion 9 is removed (FIG. 1 (j)), in a vacuum or The base material 1 having a metal circuit is formed by heating at 400 ° C. in a nitrogen atmosphere to imidize the polyimide resin precursor layer 5 (FIG. 1 (k)). If imidization is performed after formation of the plating base metal layer 12 by electroless plating,
It may be performed at any stage before and after electrolytic plating.

The photosensitive polymer complex thin film 5 is formed on the substrate 2.
The process after the formation of the hydrogen donor is not limited to the above process, and the hydrogen donor 10 is formed through a photomask in which the metal circuit part 8 is opened and the non-metal circuit part 9 is shielded from light.
UV light 11 in the presence of
After irradiating the substrate, the photomask is removed, and after irradiating with ultraviolet light in the air (in the absence of a hydrogen donor), the metal circuit portion 8 is subjected to electroless plating, electrolytic plating, imidization, etc. Other methods that have been filed so far may be used.

The reaction between the polyimide resin precursor thin film 3 and the palladium ion may be such that at least the surface layer of the polyimide resin precursor thin film 3 reacts to form the photosensitive polymer complex thin film 5. All the body thin films 3 may react to form a photosensitive polymer complex.

The base material 2 used in the present invention includes an insulating base material made of at least one of resin, ceramic, silicon and metal, various electronic circuit boards and silicon wafer boards, for example, polyimide resin and stainless steel. , Copper, etc. Further, considering imidization, a polyimide resin or liquid crystal polymer having a heat distortion temperature of 280 ° C. or higher is preferable. As the polyimide resin, a polyimide composed of pyromellitic dianhydride (PMDA) and oxydianiline (ODA), a polyimide composed of biphenyltetracarboxylic anhydride (BTDA) and p-phenylenediamine (PDA), and a copolymer of these monomers A thermoplastic polyimide comprising a polymer, an aromatic tetracarboxylic acid anhydride and an aromatic diamine having a bending group such as -O-, -CO-, -Si- in the molecule, and further an alicyclic carboxylic acid anhydride Examples thereof include solvent-soluble thermoplastic polyimides such as copolymers with materials, and these polyimide resins are mainly used as film substrates in the field of electronic component materials.

When a polyimide resin is used as the base material 2, by imidizing, the base material 2 and the photosensitive polymer thin film 5 layer become homogeneous and the adhesion strength between the metal circuit and the base material becomes very strong. .

As the polyamic acid which is the polyimide resin precursor solution, commercially available pyromellitic anhydride (PMD) is used.
Polyamic acid consisting of A) and oxydianiline (ODA), biphenyl tetracarboxylic acid anhydride (BTDA)
And a polyamic acid varnish obtained from a copolymer of p-phenylenediamine (PDA), a copolymer of these monomers, and an alicyclic carboxylic acid anhydride, and a photosensitive group in the molecule. A polyamic acid varnish containing the like is applicable. Typical examples of polyamic acid varnishes include Toray's polyimide resin precursor varnishes "Trenis", "Photo Nice", "Semicofine", and Ube Industries' polyimide resin precursor varnish "U-varnish". To be Further, the polyimide resin precursor varnish and the solvent-soluble polyimide varnish can be mixed and used. As solvent-soluble polyimide varnish, Nippon Steel Chemical's thermoplastic polyimide varnish "SPI"
Examples include −200 ″.

The polyimide resin precursor solution 3 is, for example,
It is applied as a thin film on various substrates using spin coater, bar coater, screen printing, etc.
Usually, it is dried at a temperature of 150 ° C or lower. The film thickness of the polyimide resin precursor after drying is usually 0.1 to 10 μm, and the screen printing method is convenient for directly forming wirings and connection bumps on the substrate without going through a process such as photolithography. Is. Furthermore, after the polyimide precursor varnish is applied to a film such as polyester and appropriately dried, a dry film type polyimide precursor resin film coated with a polyolefin-based cover film is heat-bonded onto another substrate. It is possible to stick.

Palladium ions which serve as a catalyst for electroless plating in the present invention and which form a complex with a polyamic acid include various salts of palladium and organic carbonyl complexes. Examples of the palladium salt include hydrochlorides, sulfates and acetates. Examples thereof include oxalate, citrate, and phthalate. Examples of organic carbonyl compounds include β-diketones such as acetylacetone and dibenzoylmethane, and β-ketocarboxylic acid esters such as ethyl acetoacetate.

Palladium ion is obtained by dissolving the above-mentioned palladium salt in a suitable solvent, immersing the substrate on which the polyimide resin precursor solution is applied and dried in the solution, and immersing it in the solution of the palladium salt to bring it into contact with the polyimide. The resin precursor and the palladium ion can be reacted. Pattern plating using a dry film is particularly preferable because it is covered with the dry film. When an organic acid salt or organic carbonyl compound is used as the palladium ion, alcohols and ketones are preferable. The concentration of palladium ion in the solution is preferably about 0.2 to 5.0 mmol / L, preferably about 1 to 2 mmol / L. If the concentration is too low, the reaction takes too long, and if the concentration is too high, unnecessary adhesion increases and washing loss increases.

The reaction between the polyimide resin precursor solution 3 and the palladium ion is usually carried out by immersing the substrate 2 coated with the polyimide resin precursor solution in the palladium ion solution 4 at room temperature. The reaction can be accelerated by heating to the temperature below. The time required for the reaction varies depending on the concentration of palladium ions in the solution and the film thickness of the polyimide resin precursor thin film, but usually,
It is about 3 minutes to 1 hour. When the reaction is carried out for a long time, palladium ions penetrate into the polyimide resin precursor thin film, and a complex can be formed inside, so that a metal circuit having high adhesion strength can be formed.

The formation of a complex between the polyimide resin precursor solution 3 and the palladium ion means that the viscosity of the polyamic acid varnish is increased and the gel is formed when the complex is added to the polyamic acid varnish as shown in FIG. It is also clear from. When a copper (II) acetylacetone complex, salts or the like is added to the polyimide resin precursor solution 3 instead of the palladium salts, the viscosity change of the solution and the gelation phenomenon do not occur at all.

Therefore, it is considered that the metal complex formation of the polyimide resin precursor is peculiar to palladium ion. In this case, it is considered that the palladium ion probably reacts with the functional group of the polyimide resin precursor to form a complex in which a metal ion is coordinated in the polymer molecule and is incorporated as one component.

The ultraviolet rays 11 used in the present invention include:
It is effective to use ultraviolet rays having a wavelength of 300 nm or less emitted from a mercury ultraviolet lamp or an ultraviolet laser generator.
Ultraviolet rays of nm are particularly effective. A commercially available low-pressure mercury lamp can be used as the ultraviolet lamp. It is considered that when irradiated with ultraviolet rays, the palladium polymer complex compound absorbs light and is excited, and the palladium ion in the excited complex molecule is reduced to a metal in the presence of a hydrogen donor. This is also clear from the measurement result of XPS on the surface of the photosensitive polymer complex thin film 5 irradiated with the ultraviolet ray 11 in the presence of the hydrogen donor 10 shown in FIG. 4, from the fact that the palladium ion is reduced to metallic palladium. is there.

The ultraviolet irradiation amount is 500 to 150 when measured by an ultraviolet illuminance meter UV-02 manufactured by Oak Manufacturing Co., Ltd.
Requires mJ / cm ² energy of about, in particular, about 1500~9000mJ / cm ² is preferred.
If the irradiation amount of ultraviolet rays is 500 mJ / cm ² or less, the palladium ions of the palladium compound may not be completely reduced to palladium metal, and if it is 15000 mJ / cm ² or more, the polyimide resin precursor layer may be damaged. When the ultraviolet irradiation dose is 1500 to 9000 mJ / cm ² , palladium ions are stably reduced to palladium metal.

The irradiation time required to obtain the above-mentioned ultraviolet irradiation amount depends on the irradiation intensity of ultraviolet rays, but the irradiation time of an ordinary ultraviolet lamp is about 1 minute to 20 minutes, and in the case of ultraviolet irradiation from a laser generator. The irradiation time is within 60 seconds.

In order to accelerate the photoreaction of the complex compound, a sensitizer may be added as long as the adhesion between the metal and the polyimide is not adversely affected.

Examples of the hydrogen donor 10 include water, alcohol, and alcohol aqueous solution. In particular, the hydrogen donor 10 has little ultraviolet absorption in the above-mentioned ultraviolet wavelength range, and has appropriate wettability with the surface of the photosensitive polymer complex thin film 5. An alcoholic aqueous solution is preferably used. It should be noted that the reaction of reducing the metal ion to the metal is inhibited by the presence of oxygen, so it is preferable to block oxygen (air) during irradiation. Usually, the irradiation is often performed with the substrate 1 immersed in a hydrogen donor, but when the hydrogen donor 10 is water, irradiation is performed while supplying water from the outside by irradiation with water or the like. The photosensitive polymer complex thin film 5 can be used by sufficiently adsorbing water beforehand.

The electroless plating bath for forming the underlying metal layer 12 is not particularly limited, but is usually neutral considering the barrier properties against metal ions and the chemical resistance (alkali resistance) of the polyimide resin precursor. A weakly acidic hypophosphite-based or dimethylaminoborane-based nickel plating bath is preferably used. Further, as the electrolytic plating bath, a usual electrolytic copper plating or electrolytic nickel plating bath can be used.

The polyimide resin precursor solution 3 is applied to the base material 2, palladium ions are reacted to form a photosensitive polymer complex thin film 5, and then a comb-shaped plating resist pattern mask is formed on the surface thereof with a dry film for plating resist. 6 is a top view when electroless nickel plating is performed (S
An EM photograph) is shown in FIG. It can be seen that a wiring pattern of L / S = 50/50 μm is formed. The insulation resistance between the lines obtained by this method was measured by JISC-5016, and as a result, a high insulation resistance of 1.5 × 10 ¹² Ω · cm was obtained.

[0036]

[Example] (Example 1) Polyimide base material manufactured by Ube Industries "
Upilex-S "specimen 10 x 10 cm (thickness 50
μm) was treated with a 1% NaOH aqueous solution and a 1% HCL aqueous solution, washed with pure water and dried, and then a Toray polyimide resin precursor varnish “Trenice” was applied with a bar coater and dried at room temperature and 120 ° C. . The thickness of the coating film is about 5
was μm.

Next, the base material was immersed in a 300 mg / L palladium chloride aqueous solution at 25 ° C. for 30 minutes and then sufficiently washed with 1N hydrochloric acid and ionic water to remove the palladium chloride adhering to the surface. A 20% ethanol aqueous solution was dropped on the material, sandwiched between quartz plates, and ultraviolet rays from a low pressure mercury lamp were irradiated for 3 minutes while the air was blocked by the aqueous solution film. The irradiation amount of ultraviolet rays is the UV illuminance meter manufactured by Oak Manufacturing Co., Ltd.
The measurement result at −02 was 4500 mJ / cm ² .

The base material was immersed in an electroless nickel bath "Emplate Ni-426" (PH = 6 to 7) heated to 65 ° C. using sodium hypophosphite manufactured by Meltec as a reducing agent for 5 minutes. As a result, a plating having a uniform metallic luster was formed only in the ultraviolet irradiation portion. With respect to the nickel-plated base material, the results of measuring Auger spectra in the depth direction of the nickel-plated portion and the polyimide resin precursor thin film portion are as shown in FIG. 6, and nickel is from the plated portion to the polyimide resin precursor thin film portion. It was detected even inside, and it was confirmed that nickel metal was present in the polymer layer. With respect to this nickel-plated base material, the results of measuring Auger spectra in the depth direction of the nickel-plated portion and the polyimide resin precursor thin film portion are as shown in FIG. It was confirmed that nickel metal was present in the polymer layer.

Further, in the electrolytic copper plating bath, 3.3 A / dm
Electroplating was performed at a current density of ² to obtain a copper clad substrate having a copper film thickness of 24 μm.

The obtained copper-clad base material was dried at 150 ° C. in a nitrogen atmosphere and then heated to 400 ° C.,
After holding at 400 ° C. for 15 minutes to perform imidization, it was cooled to room temperature (20 ° C. to 25 ° C.) in a nitrogen atmosphere to obtain a copper-clad base material having metallic luster.

The adhesion (adhesion) strength between the metal of the copper clad substrate thus obtained and the polyimide was measured by the method specified in JIS C-6481 and found to be 1000 gf / cm (1
A peel strength of 0 N / cm) was obtained.

Next, a dry film type photoresist was used for the copper clad substrate obtained by the above method, exposed and developed, and then L / S = 100/1 with a ferric chloride type etchant.
00 (μm) wiring pattern was prepared, the nickel plating layer in the space was etched with an acidic hydrogen peroxide solution, and a photosensitive polymer complex thin film was formed with an aqueous solution of potassium permanganate having a concentration of 0.1 mol / L. Removed. The insulation resistance between the wirings of the obtained base material having a metal circuit is measured according to JISC-501.
As a result of measuring at 6, the applied voltage is 100 V, and is 1.5 × 101
It was 2 Ω · cm.

Example 2 A sample of polyimide base material "Kapton EN" manufactured by Toray DuPont 10 × 10 cm (thickness: 50 μ)
m) is treated with 1% NaOH aqueous solution and 1% HCL aqueous solution, washed with pure water and dried, then Toray polyimide resin precursor varnish "Semicofine" is applied with a bar coater and dried at room temperature and 120 ° C. Then, a polyimide resin precursor layer was formed. The thickness of the polyimide resin precursor layer is about 3μ
It was m.

Then, the substrate was immersed in a 300 mg / L palladium chloride aqueous solution at 25 ° C. for 30 minutes to cause a complexing reaction between the polyimide resin precursor and palladium ion to form a photosensitive polymer complex thin film. It was thoroughly washed with 1N hydrochloric acid and ion water to remove the palladium chloride adhering to the surface.

Water was dropped on the photosensitive polymer complex thin film, sandwiched between quartz plates to form a water film, and air was cut off, and then ultraviolet rays from a low-pressure mercury lamp were irradiated for 5 minutes. The irradiation amount of ultraviolet rays was 7500 mJ / cm ² as a result of measurement with an illuminance meter UV-02 manufactured by Oak Manufacturing Co., Ltd.

Next, the electroless nickel bath "Enplate Ni-426" (PH = 6 to 7) using Meltec's sodium hypophosphite heated at 65 ° C. as the reducing agent was used as the base material.
When it was dipped in the plate for 5 minutes, a plated film having a uniform metallic luster on the light-irradiated part was obtained.

Furthermore, in the electrolytic copper plating bath, 3.3 A / dm
Electroplating was performed at a current density of ² to obtain a copper-clad polyimide film having a copper film thickness of 24 μm. The adhesion strength between the metal and the polyimide of the obtained film was 1200 gf / cm (12
N / cm).

Example 3 A sample of a polyimide base material "Kapton EN" manufactured by Toray DuPont 10 × 10 cm (thickness 50 μm)
After covering the peripheral part of m) with a protective tape, a polyimide resin precursor varnish "Semicofine" manufactured by Toray is applied with a bar coater, and the protective tape is peeled off at room temperature and 120 ° C.
And dried to form a polyimide resin precursor layer. The thickness of the polyimide resin precursor layer was about 3 μm.

Next, the substrate is immersed in an acetone solution in which 250 mg / L of palladium acetate is dissolved at 25 ° C. for 20 minutes to cause a complexing reaction between the polyimide resin precursor and palladium ion to form a photosensitive polymer complex thin film. After the formation, it was washed with acetone and sufficiently washed with deionized water to remove the palladium acetate solution adhering to the surface.

Water was dropped on the photosensitive polymer complex thin film, sandwiched between quartz plates to form a water film, and air was shut off, and then ultraviolet rays from a low pressure mercury lamp were irradiated for 5 minutes. The irradiation amount of ultraviolet rays was 7500 mJ / cm ² as a result of measurement with an illuminance meter UV-02 manufactured by Oak Manufacturing Co., Ltd. This irradiation film is an electroless nickel bath made of Meltec sodium hypophosphite heated to 65 ° C as a reducing agent "Emplate N"
When it was immersed in i-426 (PH = 6 to 7) for 5 minutes, nickel plating with a uniform metallic luster occurred only in the semicofine coated part. In addition, plating did not occur on the peripheral portion of the base material that was covered with the protective tape and was not coated with "semicofine".

Example 4 A polyimide base material having a polyimide resin precursor layer was formed in the same manner as in Example 2.

Next, on the surface of the polyimide resin precursor layer, an alkali development type dry film "NIT" made by Nigo Morton
225 "was laminated and exposed and developed through a mask having a comb-shaped electrode circuit pattern of L / S = 50/50 to form a plating resist pattern.

The substrate on which the plating resist pattern was formed was immersed in a 300 mg / L palladium chloride aqueous solution at 25 ° C.
After 30 minutes of immersion in water, it is thoroughly washed with 1N hydrochloric acid and ionic water to remove the palladium chloride adhering to the surface, and then a 20% ethanol aqueous solution is dropped onto the base material.
It is sandwiched between quartz plates, and the air is blocked by an aqueous solution film,
It was irradiated with ultraviolet rays from a low pressure mercury lamp for 5 minutes. The irradiation amount of ultraviolet rays was 7500 mJ / cm ² as a result of measurement with an illuminance meter UV-02 manufactured by Oak Manufacturing Co., Ltd.

Next, an electroless nickel bath "Enplate Ni-426" (PH = 6 to 7) using Meltec sodium hypophosphite as a reducing agent, in which the above substrate was heated to 65 ° C.
When it was immersed for 5 minutes in nickel, nickel plating with a uniform metallic luster was attached only to the part where the semicofine was exposed from the dry film, and nickel wiring was obtained.

Furthermore, in the electrolytic copper plating bath, 3.3 A / dm
^When electroplating was performed at a current density of ^2, a copper film thickness of 10
A comb-type electrode circuit having a copper / Ni wiring of μm was obtained. The insulation resistance between the wirings of the obtained film was measured by JISC-5016, and it was found to be 1.5 × 10 12 Ω at an applied voltage of 10V.
It was cm.

(Example 5) A polyimide base material "Kapton EN" having a film thickness of 50 µm was prepared by mixing an equal mixture of a polyimide resin precursor varnish "Trenis" manufactured by Toray Industries, Inc. and a thermoplastic polyimide varnish "SPI-200" manufactured by Nippon Steel Chemical. Apply on top of 1
It was dried at 20 ° C. to obtain a substrate having a thin film layer made of a polyimide precursor of 3 μm and a thermoplastic polyimide.

Then, the base material was immersed in a 300 mg / L palladium chloride aqueous solution at 25 ° C. for 1 hour to cause a complexing reaction between the polyimide resin precursor and palladium ion to form a photosensitive polymer complex thin film. It was washed with 1N hydrochloric acid and sufficiently washed with ion water to remove the palladium chloride aqueous solution adhering to the surface.

A water film is formed by wetting the surface of the substrate having the pattern resist, and L / S = 150 from above the water film.
/ 150 (μm) with a wiring pattern of a metal circuit portion having an opening photomask is adhered to the substrate with a water film sandwiched,
Ultraviolet rays from a low-pressure mercury lamp were applied to the metal circuit portion for 3 minutes through a photomask. The irradiation amount of ultraviolet rays was 7500 mJ / c as a result of measurement with an illuminance meter UV-02 manufactured by Oak Manufacturing Co., Ltd.
It was m ² .

Next, the base material was placed in an electroless nickel bath "Enplate Ni-426" (PH = 6 to 7) heated to 65 ° C. using sodium hypophosphite manufactured by Meltec as a reducing agent. When it was soaked for a minute, plating with uniform metallic luster was generated only on the metal circuit portion, and the same metal circuit as the opening pattern of the photomask was formed.

3.3 A / d of electrolytic copper plating bath on the substrate
Electroplating was performed at a current density of m ² to obtain a base material having a comb-shaped electrode circuit with a copper film thickness of 10 μm and a copper film thickness of 10 μm.

(Example 6) A polyimide resin precursor varnish "Semicofine" manufactured by Toray Co., Ltd. was applied to an 8-inch silicon wafer by a spin coater, and the temperature was kept at room temperature and 120 ° C.
Dried in. The thickness of the polyimide resin precursor layer is about 2 μm
Met.

Then, an alkali-developing dry film "NIT225" manufactured by Nigo Morton was laminated on the surface of the polyimide resin precursor layer, and L / S = 50/50.
A plating resist pattern was formed by exposing and developing through a mask having a comb-shaped electrode circuit pattern.

The substrate on which the plating resist pattern was formed was immersed in a 300 mg / L palladium chloride aqueous solution at 25 ° C.
After soaking for 30 minutes in water, wash thoroughly with 1N hydrochloric acid and ionic water to remove the palladium chloride adhering to the surface, then drop water on the base material, sandwich it between quartz plates, and shut off the air with a water film. In this state, the ultraviolet ray from the low pressure mercury lamp was irradiated for 5 minutes. The irradiation amount of ultraviolet rays was measured by an illuminance meter UV-02 manufactured by Oak Manufacturing Co., Ltd. and found to be 7500 mJ / cm ²
Met.

Next, the electroless nickel bath "Enplate Ni-426" (PH = 6 to 7) using Meltec's sodium hypophosphite as a reducing agent, in which the above substrate was heated to 65 ° C.
When it was immersed for 5 minutes in nickel, nickel plating with a uniform metallic luster was attached only to the part where the semicofine was exposed from the dry film, and nickel wiring was obtained.

Furthermore, in the electrolytic copper plating bath, 3.3 A / dm
^When electroplating was performed at a current density of ^2, a copper film thickness of 10
A comb-type electrode circuit having a copper / Ni wiring of μm was obtained. The insulation resistance between the wirings of the obtained base material was measured by JISC-5016, and as a result, it was 1.4 × 10 12 Ω · c at an applied voltage of 100V.
It was m.

(Example 7) A 10 cm x 10 cm ceramic substrate was coated with Toray's polyimide resin precursor varnish "Semicofine" with a spin coater and dried at room temperature and 120 ° C twice. The thickness of the polyimide resin precursor layer was about 3 μm.

Then, on the surface of the polyimide resin precursor layer, an alkali-developing dry film manufactured by Nigo Morton was used.
NIT225 "was laminated and exposed and developed through a mask having a comb-shaped electrode circuit pattern of L / S = 50/50 to form a plating resist pattern.

The substrate on which the plating resist pattern was formed was immersed in a 300 mg / L palladium chloride aqueous solution at 25 ° C.
After soaking for 30 minutes in water, wash thoroughly with 1N hydrochloric acid and ionic water to remove the palladium chloride adhering to the surface, then drop water on the base material, sandwich it between quartz plates, and shut off the air with a water film. In this state, the ultraviolet ray from the low pressure mercury lamp was irradiated for 5 minutes. The irradiation amount of ultraviolet rays was measured by an illuminance meter UV-02 manufactured by Oak Manufacturing Co., Ltd. and found to be 7500 mJ / cm ²
Met.

Next, the electroless nickel bath "Enplate Ni-426" (PH = 6 to 7) using Meltec's sodium hypophosphite as a reducing agent heated to 65 ° C.
When it was immersed for 5 minutes in nickel, nickel plating with a uniform metallic luster was attached only to the part where the semicofine was exposed from the dry film, and nickel wiring was obtained.

Furthermore, in the electrolytic copper plating bath, 3.3 A / dm
^When electroplating was performed at a current density of ^2, a copper film thickness of 10
A comb-type electrode circuit having a copper / Ni wiring of μm was obtained. The insulation resistance between the wirings of the obtained base material was measured by JISC-5016, and as a result, the applied voltage was 100 × 1.5 × 10 12 Ω · c.
It was m.

[0071]

As described above, in the present invention, focusing on the fact that the polyimide precursor polyamic acid and palladium ions form a photosensitive polymer complex, the polyimide resin precursor solution is applied to the substrate surface. After drying to form a polyimide resin precursor thin film, it is immersed in a palladium ion solution to react the polyimide resin precursor with palladium ions to form a photosensitive polymer complex, which is then exposed to ultraviolet light and electroless plated to form a metal. Is a method of forming a film,
By photolithography using a plating resist and mask exposure, a wiring circuit or the like can be easily formed in a small number of steps. Compared to conventional adsorption methods such as surface hydrolysis method, since there is a polyamic acid film with an appropriate film thickness, it has good reactivity with palladium and reacts in a relatively short time, and forms a stable metal film. be able to. As described above, the manufacturing process of the base material using the polyimide precursor resin palladium complex is extremely excellent for fine wiring processing and has high utility value.

According to the method for forming a metal circuit of the present invention, as described in claim 1, after forming a polyimide resin precursor layer on a substrate, palladium ions are reacted to form a photosensitive polymer complex thin film. In the past, steps such as liquid preparation, viscosity control, and wet coating, which are conventionally required when forming a solution-like photosensitive polymer complex, are unnecessary.

A substrate having a polyimide resin precursor layer is dipped in an aqueous solution of an inorganic acid salt of palladium or a solution of an organic acid salt or an organic complex to form a photosensitive polymer complex thin film. Solution control and viscosity control when forming a solution type photosensitive polymer complex, which was conventionally required when forming a metal circuit, by using the aqueous solution of inorganic acid salt or solution of organic acid salt or organic complex of In addition, steps such as wet coating are not necessary, and palladium ions reliably react with the polyimide resin precursor. Therefore, the amount of palladium ions can be reduced as compared with the case where a metal circuit is formed using a polyimide resin precursor solution in which a palladium compound is uniformly mixed, which has been used conventionally.

Since the base material forming the metal circuit is made of at least one of resin, ceramic, silicon, and metal, it is possible to form a metal circuit having excellent adhesion to the base material.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a method for forming a metal circuit pattern according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a substrate formed by the metal circuit forming method of the present invention.

FIG. 3 is a diagram showing a change in viscosity when a palladium acetylacetone complex is added to a polyimide resin precursor solution and a change in viscosity of the polyimide resin precursor solution.

FIG. 4 is a diagram showing an XPS analysis result showing changes in palladium binding energy of a palladium complex-containing resin thin film layer before and after irradiation with ultraviolet rays.

FIG. 5 is an Auger analysis chart of a nickel plated portion and a polyimide resin precursor thin film after electroless nickel plating.

FIG. 6 is a top view of a metal circuit formed by the metal circuit forming method of the present invention.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 3/38 H05K 3/38 D // C08L 79:08 C08L 79:08 A (72) Inventor Atsushi Suzuki 1 103-54, Yoshinodai, Kawagoe City, Saitama Prefecture Ray Tech Co., Ltd. (72) Inventor Yuko Hashino 1-103-54, Yoshinodai, Kawagoe City, Saitama Ray Tech Co., Ltd. F-term (reference) 4F073 AA32 BA31 BB01 EA52 4K022 AA02 AA04 AA15 AA42 BA14 BA31 CA03 CA06 DA03 DA04 DB02 4K024 AA09 AB01 BA01 BA12 BA15 BB11 CA06 DA06 5E343 AA12 AA18 AA22 AA23 BB05 BB24 BB44 CC73 DD33 DD43 EE32 EE42 ER02 GG02 GG11

Claims (4)

[Claims] 1. At least a step of forming a polyimide resin precursor layer on a substrate, a step of forming a photosensitive polymer complex thin film in which the polyimide resin precursor and palladium ions form a complex, And a step of forming a metal circuit on the molecular complex thin film. 2. A photosensitive polymer complex thin film is formed by immersing a base material having a polyimide resin precursor layer in an aqueous solution of an inorganic acid salt of palladium or a solution of an organic acid salt or an organic complex. Item 1. The metal circuit method according to Item 1. 3. The metal circuit forming method according to claim 1, wherein an aqueous solution of an inorganic acid salt of palladium or a solution of an organic acid salt or an organic complex is used as the palladium ion. 4. The method for forming a metal circuit according to claim 1, wherein a base material made of at least one of resin, ceramic, silicon, and metal is used as the base material.