JP3355832B2 - Circuit pattern forming method and its paste - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a circuit pattern on a circuit board when manufacturing the circuit board, and a paste for forming the pattern. More specifically, the present invention relates to a method suitable for forming a fine circuit pattern with a fine pitch on a fine line by reducing a metal salt, and a paste thereof.

[0002]

2. Description of the Related Art In recent years, the mounting density of chip components on a circuit board has increased due to the miniaturization of electronic equipment, and fine circuit patterns having fine lines and fine pitches have been required. Conventionally, as a method of forming a conductive circuit pattern on a non-conductive substrate, for example, a method of forming a thick film by screen printing is known. This method involves preparing a conductive paste by mixing a metal powder with a thick film paste obtained by dissolving a thermosetting resin in an organic solvent, and screen-printing the conductive paste on a non-conductive substrate in a predetermined pattern. Applying a coating film by a method, drying the screen-printed conductive paste and bonding the coating film to a non-conductive substrate with a resin, and applying electroless plating to the resin-bonded coating film. .

According to this method, when the conductive paste is dried, the metal powders come into contact with each other, and the printed coating film becomes conductive, and at the same time, the coating film adheres to the substrate by the resin. However, when the pattern formed by screen printing is a fine line, there is a possibility that the pattern may be cut due to shrinkage of the paste during drying. For this reason, in the conventional thick film forming method, when performing screen printing so as not to cause pattern breakage,
It was necessary to keep the pattern width at least about 100 μm. Further, when a pattern is formed with a conductive paste, the metal powder in the conductive paste has a large specific gravity, so that the metal powder tends to settle down by its own weight and cause dripping of the paste. For this reason, if the pattern pitch is narrowed to fine pitch,
There was a danger that the patterns would short-circuit due to dripping. For this reason, in the conventional thick film forming method, when performing screen printing so that patterns are not short-circuited, it is necessary to keep the pattern interval at least about 100 μm. Therefore, according to this method, only a pattern having a pattern width and a pattern interval of about 100 μm or more can be formed, and as a result, a circuit pattern cannot be made fine with a fine line and a fine pitch.

[0004] In order to improve these points, the present applicant has filed a patent application for a "method of forming a circuit on a ceramic substrate" for forming a fine pattern (Japanese Patent Laid-Open No. 4-2499).
0). That is, the method for forming a fine pattern involves dispersing metal particles having a particle size of 5 μm or less, such as gold, silver, copper, and tungsten, in a solution of a metal alkoxide such as silicon, lead, zinc, or aluminum, and Alternatively, a ceramic substrate on which a mask made of a hydrophobic material is adhered is immersed in the metal alkoxide solution and pulled up. After removing the mask from the ceramic substrate, the gel coating film remaining on the non-mask portion on the substrate is exposed to air. 800-9 in
This is a method of baking by heating to about 00 ° C. According to this method, when a ceramic substrate is immersed in a metal alkoxide solution and pulled up, a gel coating film composed of a gel oxide and metal fine particles is formed on the substrate. Next, after the mask is removed from the ceramic substrate, when the gel coating film remaining on the non-mask portion is fired, the gel oxide further shrinks and becomes a normal oxide, and softens or melts in this firing temperature range. The metal fine particles are sintered. Therefore,
A conductive fine pattern having a pattern width and a pattern interval of about 10 to 30 μm can be firmly formed on a ceramic substrate.

[0005]

However, in the above-mentioned method for forming a fine pattern, it is difficult to prepare fine metal particles of 5 μm or less, and the fine metal particles are uniformly dispersed in a metal alkoxide solution when the substrate is immersed. However, there is a problem that the production cost is high because the metal fine particles are used. SUMMARY OF THE INVENTION An object of the present invention is to provide a method of forming a circuit pattern and its paste, which can form a circuit pattern with fine lines and at a fine pitch and can be firmly bonded to a substrate. Another object of the present invention is to provide a method capable of easily and inexpensively forming a circuit pattern without using metal fine particles and a paste thereof. Yet another object of the present invention is to provide
An object of the present invention is to provide a method of forming a circuit pattern having many types of applicable substrates and a paste thereof.

[0006]

In order to achieve the above object, a method for forming a circuit pattern according to the present invention is directed to a paste comprising an inorganic or organic metal salt, metal alkoxide and resin uniformly dissolved in an organic solvent. Coating a non-conductive substrate to form a coating film having a predetermined pattern, and reducing a metal salt contained in the coating film with a solution containing a reducing agent to convert metal ions of the metal salt into a metal component. A step of depositing on a coating film and coating the coating film on which a metal component is deposited by heat-treating the coating film at a temperature of 100 to 700 ° C. in the air to hydrolyze or polycondensate the metal alkoxide and convert the reaction product to a metal oxide. This is a method including a step of bonding a film to a substrate and a step of forming a desired film thickness by electroless plating. In addition, the paste for forming a circuit pattern of the present invention is obtained by uniformly dissolving an inorganic or organic metal salt, a metal alkoxide and a resin in an organic solvent.
And the resin is an acrylic resin, an alkyd resin,
Malon-indene resin, epoxy resin, furan resin, stone
Oil resin, isobutylene resin, isocyanate resin, keto
Resin, melamine resin, oleo resin, phenol resin,
Polyamide resin, polyester resin, resorcinol tree
Fat, styrene resin, terpene resin, terpene-phenol
Resin, urea resin or vinyl resin .

Hereinafter, the present invention will be described in detail. (a) Circuit Pattern Forming Paste The paste of the present invention is prepared by dissolving a metal salt and a metal alkoxide in an organic solvent, and then adding and dissolving the above-mentioned resin to this solution. When this paste is applied in a predetermined pattern by screen printing, 3 to 80% by weight of a metal salt, 10 to 70% by weight of a metal alkoxide and 10 to 80% by weight of a resin are mixed with 100% by weight of an organic solvent. The viscosity of the paste is adjusted by changing the amount of each resin or organic solvent. 3 metal salts
If it is less than 80% by weight, metal components precipitated during reduction do not appear on the entire surface of the coating film, and if it exceeds 80% by weight, it is difficult to dissolve. If the metal alkoxide is less than 10% by weight, the adhesion of the coating film to the substrate is not sufficient, and
If it exceeds, it also becomes difficult to dissolve. Further, when the content of the resin is less than 10% by weight or more than 80% by weight, the coatability of the paste deteriorates.

Here, the metal salt may be an inorganic metal salt or an organic metal salt as long as it generates metal ions when dissolved in an organic solvent. Representative examples of the inorganic metal salt and the organic solvent in which the metal salt dissolves are shown in Tables 1 to 4. In addition, it means that the corresponding metal salt is very slightly dissolved in the organic solvent with (fine) in the table.

[0009]

[Table 1]

[0010]

[Table 2]

[0011]

[Table 3]

[0012]

[Table 4]

Tables 5 to 8 show typical examples of an organic metal salt which is a paste component of the present invention and an organic solvent in which this metal salt is dissolved.
Shown in It means that the corresponding metal salt is very slightly soluble in the organic solvents marked (fine) in the table.

[0014]

[Table 5]

[0015]

[Table 6]

[0016]

[Table 7]

[0017]

[Table 8]

The metal alkoxide which is a paste component of the present invention has an alkoxyl group which is soluble in an organic solvent as exemplified in Tables 1 to 8. Examples of the metal alkoxide include silicon alkoxide, aluminum alkoxide, zirconium alkoxide, titanium alkoxide, lithium alkoxide, copper alkoxide, zinc alkoxide, lead alkoxide, and lanthanum alkoxide. In particular, Si (OC ₂ H ₄ ) ₄ , Al (OCH ₃ ) ₃ , Zr (O
CH ₃ ) ₄ and Ti (OCH ₃ ) ₄ are preferred. The above-mentioned resin which is a paste component of the present invention is a resin which is soluble in organic solvents exemplified in Tables 1 to 8. Resins of the present invention is Ru required der to be destroyed by heat treatment step in a subsequent step.

(B) Formation of Coating Film of Predetermined Pattern It is necessary that the non-conductive substrate for forming the circuit pattern of the present invention does not deteriorate or deform in a subsequent heat treatment at 100 to 700 ° C. As this non-conductive substrate,
There is an organic plastic material, an inorganic ceramic material, or an inorganic / organic composite material. Examples of the organic plastic material include paper phenol, paper epoxy, polyimide, fluororesin, polysulfonide, and the like, and examples of the inorganic ceramic material include alumina, silicon carbide, polonitride, silicon nitride, crystallized glass, and the like. And as the inorganic-organic composite material, quartz-epoxy and the like are exemplified. As a method of applying the paste on the substrate in a predetermined pattern, a screen printing method capable of printing a fine pattern with high precision and excellent in mass productivity is preferable.
Even if the coating film is dried, since the components of the paste are dissolved, the coating film does not crack or crack.

(C) Deposition of Metal Component on Coating Film As a method for reducing the metal salt contained in the coating film to deposit the metal component on the coating film, a substrate on which the coating film is formed contains a reducing agent. There is a method of dipping in a solution or applying a solution containing a reducing agent on a coating film. Next, this reducing agent is illustrated for each of the metals to be deposited. Sodium hypophosphite (NaH ₂ PO ₂ ), dimethylamine borane ((CH ₃ ) ₂ HN · BH ₃ ), borohydride compound (Na
BH ₄ ), hydrazine (N ₂ H ₄ ), diethylamine borane ((C ₂ H ₅ ) ₂ HN · BH ₃ ) and the like. As a reducing agent for precipitating silver, sodium hypophosphite (NaH ₂ P) is used.
O ₂ ), 37% formaldehyde (HCHO) and the like.

As the reducing agent for precipitating copper, 37% formaldehyde (HCHO), P-formaldehyde (HCHO), formic acid (HCOOH), dimethylamine borane ((CH ₃ ) ₂ HN.BH ₃ ), phosphorus hypophosphite Acid (H ₃ P
O ₂ ), hydrazine sulfate ((N ₂ H ₅ ) ₂ SO ₄ , N ₂ H ₆ S
O ₄ ). As a reducing agent for depositing palladium, sodium hypophosphite (NaH ₂ PO ₂ ), dimethylamine borane ((CH ₃ ) ₂ HN · BH ₃ ), hydrazine (N ₂ H ₄ ), triethylamine borane ((C ₂ H ₅ ) ₃ HN
BH ₃ ), 37% formaldehyde (HCHO) and the like.

On the other hand, typical examples of the solution containing the reducing agent include an electroless nickel plating bath, an electroless copper plating bath, and a bath obtained by removing a metal component from an electroless palladium plating bath. As a low temperature alkaline nickel reduction bath, there is a bath containing a reducing agent of sodium hypophosphite, sodium pyrophosphate and triethanolamine. As a high temperature alkaline nickel reduction bath, there is a bath containing a sodium hypophosphite reducing agent, sodium citrate and ammonium chloride. As an acidic nickel reduction bath, there is a bath containing a reducing agent of sodium hypophosphite, sodium acetate and lead acetate. The nickel reduction bath containing a reducing agent for sodium borohydride further contains sodium hydroxide, ethylenediamine and thallium nitrate. The nickel reduction bath containing a reducing agent for n-dimethylamine borane contains sodium acetate and lead acetate. The copper reduction bath containing a 37% formaldehyde reducing agent contains rossel salt and vanadium oxide. Further, the palladium reduction bath containing the reducing agent of sodium hypophosphite contains palladium chloride, Rossel's salt and ethylenediamine.

(D) Adhesion of Coating Film to Substrate with Metal Oxide
The coating film is adhered to the substrate by heat-treating at a temperature of 00 ° C. for 10 minutes to 1 hour to hydrolyze or polycondense the metal alkoxide and convert the reaction product to a metal oxide. The heat treatment is performed at a temperature in the range of 100 to 400 ° C. when the non-conductive substrate is an organic plastic material, 100 to 700 ° C. when the inorganic ceramic material is used, and 100 ° C. when the inorganic / organic composite material is used. The heating is carried out at a temperature of from about 300 to about 300 ° C. for about 10 to 30 minutes at a high temperature and for about 30 minutes to 1 hour at a low temperature. This is for avoiding thermal alteration or thermal deformation and for surely hydrolyzing or polycondensing the metal alkoxide. The heat treatment is performed in the air in order to hydrolyze the metal alkoxide with the water in the air. The heat treatment temperature and the heat treatment time are finally determined in consideration of not only the type of the substrate but also the types and the amounts of the metal salts, metal alkoxides, resins and the like which are the components of the paste.

(E) Electroless plating on the coating film Au, N
A metal layer is laminated by performing electroless plating of i, Cu, or the like. In this case, the metal layer is laminated in close contact with the underlying pattern. Therefore, the aspect ratio (thickness / width) of the wiring composed of the coating film and the metal layer can be increased. At this time, in the electroless plating, it is not particularly necessary to deposit the same metal as the metal component of the metal salt in the paste.

[0025]

As shown in FIG. 1, the paste of the present invention is obtained by mixing and dissolving a metal salt and a metal alkoxide in an organic solvent, and then further mixing and dissolving a resin. In this paste, the metal salt is in the state of metal ions. As shown in FIG. 1 and FIG. 1, when this paste is applied on a substrate in a predetermined pattern by a screen printing method or the like to form a coating film, the metal component is settled by its own weight and the paste does not drip as in the related art. As shown in FIGS. 1 and 2, when the coating film is formed and then brought into contact with a solution containing a reducing agent, metal ions of the coating film are reduced by the reducing agent, and metal components are uniformly deposited on the entire film. I do. As a result, even if the pattern is made finer, there is no break in the pattern, and the circuit pattern can be formed into fine lines and fine pitches. As shown in FIG. 1, when a substrate having a coating film in which metal components are uniformly deposited is heat-treated at 100 to 700 ° C. in the air,
Moisture in the atmosphere hydrolyzes the metal alkoxide on the substrate surface, or dealcoholation occurs in the metal alkoxide, causing polycondensation. At the same time, the reaction product becomes a metal oxide due to the heat, the coating film is firmly adhered to the substrate, the organic solvent is volatilized, and the resin for adjusting the viscosity of the paste is burned off to obtain a desired circuit pattern. FIG. 2 (a)
As shown in (1), a metal alkoxide solution (hereinafter, simply referred to as a sol) on the substrate surface is hydrolyzed by contact with atmospheric moisture. That is, the OH group of the sol and the OH group that appeared on the substrate surface due to moisture in the atmosphere combine to cause a dehydration reaction,
It becomes a metal oxide. Further, as shown in FIG. 2B, the alkoxyl group of the sol on the substrate surface and the OH group on the substrate surface combine to cause dealcoholation, thereby causing a polycondensation reaction of the metal alkoxide. The coating film is firmly adhered to the substrate by the hydrolysis and the polycondensation reaction. In FIG. 2, M and M ′ are metal atoms.

[0026]

Next, examples of the present invention will be described together with comparative examples. Examples 1 to 6 and Comparative Example 1 are examples using an inorganic metal salt, and Examples 7 to 9 and Comparative Example 2 are examples using an organic metal salt. <Example 1> 3 g of nickel sulfate and 40 g of silicon ethoxide were mixed and dissolved in 100 g of ethanol, and 50 g of a phenol resin was mixed and dissolved in this solution to prepare a paste. This paste is used for pattern width 50μ
m and a pattern interval of 100 μm were applied to the surface of the glass epoxy substrate by screen printing. After screen printing, the substrate is dried at room temperature for 1 hour to a thickness of 50
A μm coating film was obtained. The substrate on which the coating film was formed was immersed in a solution containing sodium borohydride for 0.5 hours. After immersion and drying at 100 ° C. for 0.5 hour, Ni metal was uniformly deposited on the entire surface of the coating film. Thereafter, the substrate was heat-treated at a temperature of 200 ° C. in the atmosphere for 30 minutes.

Example 2 A paste was prepared by mixing and dissolving 5 g of nickel nitrate and 30 g of aluminum methoxide in 100 g of ethanol, and mixing and dissolving 30 g of a polyester resin in this solution. This paste was screen-printed under the same conditions as in Example 1 to form Al ₂ O ₃
It was applied to the surface of the substrate. After screen printing, the substrate was dried in the same manner as in Example 1 to obtain a coating film having a thickness of 50 μm. The substrate on which the coating film is formed is immersed in a solution containing sodium borohydride for 0.5 hours,
When dried in the same manner as in Example 1, Ni metal was uniformly deposited on the entire surface of the coating film. Thereafter, the substrate was heat-treated at a temperature of 700 ° C. in the atmosphere for 5 minutes.

Example 3 A paste was prepared by mixing and dissolving 3 g of silver nitrate and 50 g of silicon ethoxide in 100 g of ethanol, and mixing and dissolving 40 g of a phenol resin in this solution. This paste was applied to the surface of the Al ₂ O ₃ substrate by screen printing under the same conditions as in Example 1. After screen printing, the substrate was dried in the same manner as in Example 1 to obtain a coating film having a thickness of 50 μm. The substrate on which the coating film was formed was immersed in a solution containing 37% formaldehyde for 1.0 hour and dried in the same manner as in Example 1.
g metal was uniformly deposited. Thereafter, the substrate is placed in air at 700
Heat treatment was performed at a temperature of 5 ° C. for 5 minutes.

Example 4 A paste was prepared by mixing and dissolving 5 g of palladium chloride and 50 g of zirconium methoxide in 100 g of ethanol, and mixing and dissolving 40 g of a phenol resin in this solution. This paste was applied to the surface of the polyimide substrate by screen printing under the same conditions as in Example 1. After screen printing, the substrate was dried in the same manner as in Example 1 to obtain a coating film having a thickness of 50 μm. The substrate on which the coating film was formed was immersed in a solution containing hydrated hydrazine for 1.0 hour and dried in the same manner as in Example 1. As a result, Pd metal was uniformly deposited on the entire surface of the coating film. Thereafter, the substrate is placed in air 4
Heat treatment was performed at a temperature of 00 ° C. for 20 minutes.

Example 5 A paste was prepared by mixing and dissolving 10 g of copper sulfate and 40 g of titanium methoxide in 100 g of ethanol, and mixing and dissolving 40 g of a phenol resin in this solution. This paste was applied to the surface of the polyimide substrate by screen printing under the same conditions as in Example 1. After screen printing, the substrate was dried in the same manner as in Example 1 to obtain a coating film having a thickness of 50 μm.
The substrate on which the coating film was formed was immersed in a solution containing 37% formaldehyde for 1.0 hour, and Example 1 was performed.
As a result, Cu metal was uniformly deposited on the entire surface of the coating film. Thereafter, the substrate is placed in the air for 40 minutes.
Heat treatment was performed at a temperature of 0 ° C. for 20 minutes.

<Example 6> 10 g of copper hydroxide and 40 g of silicon ethoxide were mixed and dissolved in 100 g of ethanol, and 30 g of a polyester resin was mixed and dissolved in this solution to prepare a paste. This paste was applied to the surface of the glass epoxy substrate by screen printing under the same conditions as in Example 1. After screen printing, the substrate was dried in the same manner as in Example 1 to obtain a coating film having a thickness of 50 μm. The substrate on which this coating film was formed
When immersed in a solution containing 7% formaldehyde for 1.0 hour and dried in the same manner as in Example 1, Cu metal was uniformly deposited on the entire surface of the coating film. Thereafter, the substrate was heat-treated at a temperature of 200 ° C. in the atmosphere for 30 minutes.

Comparative Example 1 3 g of nickel sulfate and 40 g of silicon ethoxide were mixed with 100 g of acetone, but the nickel sulfate was not completely dissolved. A paste was prepared by mixing 40 g of the phenolic resin with the mixed solution. This paste was applied to the surface of the Al ₂ O ₃ substrate by screen printing under the same conditions as in Example 1. After screen printing, the substrate was dried as in Example 1 to a thickness of 50 μm.
m was obtained. The substrate on which the coating film was formed was immersed in a solution containing sodium borohydride for 0.5 hour, and dried in the same manner as in Example 1.
Ni metal was unevenly deposited on the surface of the coating film.
Thereafter, the substrate was heat-treated in the atmosphere at a temperature of 500 ° C. for 20 minutes.

Table 9 shows the contents of Examples 1 to 6 and Comparative Example 1. Also, the presence or absence of pattern breakage and pattern short-circuit of these circuit patterns was examined. Table 10 shows the results.

[0034]

[Table 9]

[0035]

[Table 10]

Example 7 5 g of copper acetate and 30 g of silicon ethoxide were mixed and dissolved in 100 g of ethanol, and 30 g of a polyester resin was mixed and dissolved in this solution to prepare a paste. This paste was used in Example 1
It was applied to the surface of a glass epoxy substrate by screen printing under the same conditions as described above. After screen printing, the substrate was dried in the same manner as in Example 1 to obtain a coating film having a thickness of 50 μm. The substrate on which the coating film was formed was immersed in a solution containing 37% formaldehyde for 1.0 hour, and dried in the same manner as in Example 1. As a result, Cu metal was uniformly deposited on the entire surface of the coating film. Thereafter, the substrate was heat-treated at a temperature of 200 ° C. in the atmosphere for 30 minutes.

Example 8 Isopropyl alcohol 10
0 g to 5 g of palladium acetate and 4 parts of aluminum methoxide
0 g was mixed and dissolved, and 25 g of epoxy resin was added to this solution.
Was mixed and dissolved to prepare a paste. This paste was applied to the surface of the Al ₂ O ₃ substrate by screen printing under the same conditions as in Example 1. After screen printing, the substrate was dried in the same manner as in Example 1 to obtain a coating film having a thickness of 50 μm. The substrate on which the coating film was formed was immersed in a solution containing dimethylamine borane for 1.0 hour and dried in the same manner as in Example 1. As a result, Pd metal was uniformly deposited on the entire surface of the coating film. After this,
The substrate was heat-treated at a temperature of 600 ° C. in the atmosphere for 7 minutes.

Example 9 A paste was prepared by mixing and dissolving 5 g of nickel acetate and 50 g of silicon ethoxide in 100 g of ethanol, and mixing and dissolving 40 g of a phenol resin in this solution. This paste was applied to the surface of the glass epoxy substrate by screen printing under the same conditions as in Example 1. After screen printing, the substrate was dried in the same manner as in Example 1 to obtain a coating film having a thickness of 50 μm. The substrate on which the coating film is formed is immersed in a solution containing sodium borohydride for 0.5 hours,
When dried in the same manner as in Example 1, Ni metal was uniformly deposited on the entire surface of the coating film. Thereafter, the substrate was heat-treated at a temperature of 200 ° C. in the atmosphere for 30 minutes.

Comparative Example 2 Copper acetate 5 in 100 g of acetone
g and 30 g of silicon ethoxide, but the copper acetate was not completely dissolved. The polyester resin 3
A paste was prepared by mixing 0 g. This paste was applied to the surface of the polyimide substrate by screen printing under the same conditions as in Example 1. After screen printing, the substrate was dried in the same manner as in Example 1 to obtain a coating film having a thickness of 50 μm. The substrate on which the coating film was formed was placed in a solution containing 37% formaldehyde for 1.0%.
After immersion for a time and drying in the same manner as in Example 1, Cu metal was unevenly deposited on the surface of the coating film. Thereafter, the substrate was heat-treated in the atmosphere at a temperature of 400 ° C. for 20 minutes.

The contents of Examples 7 to 9 and Comparative Example 2 are shown in Table 11.
Shown in Also, the presence or absence of pattern breakage and pattern short-circuit of these circuit patterns was examined. Further, the adhesion strength of the coating film was examined in the same manner as in Example 1. Table 12 shows the results.

[0041]

[Table 11]

[0042]

[Table 12]

In Examples 1 to 9 in which the metal salt was completely dissolved, there was no pattern breakage and no pattern short circuit, whereas in Comparative Examples 1 and 2, the metal salt was slightly dissolved in the organic solvent. As a result, the pattern was cut and the pattern was short-circuited. It was presumed to be due to uneven deposition of metal components.

[0044]

As described above, according to the present invention, by reducing a coating film formed of a paste in which a metal salt is dissolved with a reducing agent, a circuit pattern can be formed in a fine line without causing dripping of the paste. Moreover, it can be formed with a fine pitch. In addition, the metal alkoxide of the paste component is hydrolyzed or polycondensed, and the reaction product is converted into a metal oxide by heat treatment, so that the coating film can be firmly adhered to the substrate. In particular, since metal fine particles are not used as compared with the conventional method of forming a fine pattern, a circuit pattern can be formed easily and inexpensively, and the heat treatment temperature is relatively low at 100 to 700 ° C. There is also the advantage that there are many types of substrates applicable to the method of the invention.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a method for forming a circuit pattern according to the present invention.

FIG. 2 is a diagram illustrating a mechanism of bonding the coating film to a substrate.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H05K 1/09 H05K 1/09 A (56) References JP-A-3-165089 (JP, A) JP-A-60-81704 ( JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05K 3/12 C07C 31/28 C09D 183/00 H01B 1/20 H05K 1/09

Claims (2)

(57) [Claims] A step of applying a paste obtained by uniformly dissolving an inorganic or organic metal salt, a metal alkoxide and a resin in an organic solvent to form a coating film of a predetermined pattern on the non-conductive substrate; A step of reducing the metal salt contained in the coating film with a solution containing a reducing agent to deposit metal ions of the metal salt as a metal component on the coating film;
Bonding the coating film to the substrate by heat-treating at a temperature of about 700 ° C. to hydrolyze or polycondense the metal alkoxide and convert the reaction product to a metal oxide. 2. A paste for forming a circuit pattern on a non-conductive substrate, wherein an inorganic or organic metal salt, a metal alkoxide and a resin are uniformly dissolved in an organic solvent.
Wherein the resin is an acrylic resin, an alkyd resin,
N-indene resin, epoxy resin, furan resin, petroleum tree
Fat, isobutylene resin, isocyanate resin, ketone tree
Fat, melamine resin, oleo resin, phenol resin, poly
Amide resin, polyester resin, resorcinol resin,
Styrene resin, terpene resin, terpene-phenol tree
Fat, urea resin or vinyl resin der paste wherein Rukoto.